RU2801697C1 - Device and method of allocating resources in the time domain based on their aggregation - Google Patents

Abstract

FIELD: wireless communication.

SUBSTANCE: invention relates to the field of wireless communication. The method of allocating resources in the time domain, carried out at a base station that supports simultaneous transmission of multiple spatial MIMO streams for data transmission, each of which is associated with a DMRS signal that differs from the others, contains stages at which a specified number of adjacent OFDM are allocated in the part of the DL/UL period of the frame corresponding to the downlink symbols for transmitting PDCCH, form a block of time intervals containing an integer number of adjacent time intervals, and each time interval includes a specified number of OFDM symbols, while PDCCH refers to the entire block of time intervals, allocate at least one subblock OFDM symbols for transmitting a DMRS structure in which DMRS signals are multiplexed for the required number of PDSCH MIMO streams, and allocate OFDM symbols for transmitting PDSCH in the block of time intervals.

EFFECT: technical result is to make it possible to use less frequent transmissions of DMRS demodulation reference signals without reducing the quality of the channel evaluation.

28 cl, 28 dwg, 4 tbl

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The present invention relates generally to wireless communications using advanced demodulation reference signals (DMRS), and more specifically to devices and methods for allocating resources in the time domain based on their aggregation.

PRIOR ART

At the present stage, there is an increasingly active deployment of ^5th generation (5G) wireless networks of the New Radio (NR) standard, the advantages and capabilities of which are widely known.

At the base stations (Transmission-Reception Point, TRP) in the 5G NR system, complex antenna arrays containing multiple transceiver antenna elements are used, which make it possible to effectively implement MIMO technology

("multi-input-multi-output"), when a number of parallel transmitted spatial MIMO streams or layers (MIMO-1ayers) is formed for data transmission (eg, a physical downlink shared data channel (PDSCH)) .

The digital signal is transmitted or received using one or more digital ports connected to the antenna elements of the base station, using an RF unit that performs the function of converting the digital signal to analog and vice versa. So, for the frequency range of 3.5 GHz, up to 64 digital antenna ports can be used, allowing the base stations to use various spatial digital signal processing schemes. For example, using the technology of spatial multiplexing (SM), it is possible to reuse the same time-frequency resources for transmitting multiple signals (MIMO streams) to one or more user equipments (UEs), and using the technology of adaptive beamforming ( beamforming) provides dynamic

focusing the energy of the transmitted signal in one or more predetermined directions. Through the use of advanced modulation techniques such as Orthogonal Frequency Division Modulation (OFDM), efficient wideband signal transmission is achieved. OFDM provides orthogonality for signals transmitted simultaneously on different subcarriers (ie orthogonality in the frequency domain). Spatial MIMO streams are generally not orthogonal, and signals transmitted in different MIMO streams interfere at the receiver side. To reduce mutual interference, as a rule, various adaptive beamforming techniques are used at the transmitter and receiver.

Accordingly, the transmitted MIMO streams are properly received by user devices that also support these technologies.

Multiple MIMO streams transmitted from a base station may all be destined to one UE, in which case it is referred to as Single User MIMO (SU-MIMO), or may be destined to different UEs, in which case it is referred to as Multi-User MIMO (MU). -MIMO).

To provide communication between various devices in the 5G NR system, including between base stations and user devices, specialized reference signals (RS) are used. One such reference signal is the demodulation reference signal (DMRS). DMRS signals are transmitted only as part of the corresponding physical channel (in particular, the following physical data channels: PDSCH and physical uplink shared data channel (PUSCH)). Thus, they are not continuously or intermittently transmitted reference signals, which are associated with additional bandwidth overhead. More specifically, a different DMRS signal is transmitted along with each of the PDSCH/PUSCH spatial MIMO streams, simultaneously

transmitted by the respective transferring party; in addition, the same adaptive spatial signal processing (precoding) is used with respect to the DMRS signal. Each DMRS signal in a 5G NR communication system has a unique index (number) associated with it, called a DMRS port. Thus, for example, each spatial MIMO PDSCH stream transmitted from a TRP in a 5G NR communication system is uniquely associated with a DMRS port; therefore, the number of MIMO layers is equal to the number of DMRS ports.

The transmission sequence of multiple spatial MIMO streams in conjunction with DMRS signals is illustrated in FIG. 1.

On FIG. 1 shows a simplified scheme of spatial processing at the transmitter, where in the first stage adaptive digital spatial signal processing is performed, converting the input signal of MIMO streams into a signal of digital antenna ports. At the same time, the corresponding spatial processing in OFDM systems can be carried out in the frequency domain, which allows flexible formation of different radiation patterns on different subcarriers. After the digital spatial processing procedure, an analog beamforming procedure is applied, converting the input signal of the digital port into the signals of the physical antennas of the subarray. This spatial signal processing is carried out in the time domain for the entire OFDM signal, which imposes restrictions on the number of simultaneously generated beams.

The main purpose of DMRS signals is to provide coherent reception of physical data channels (PDSCH and PUSCH). More specifically, in the course of passing through the communication channel, each of the transmitted MIMO streams is subjected to various kinds of distortions, and for the correct reception of this MIMO stream, the channel estimation procedure is performed on the receiver side, the algorithms of which use the DMRS corresponding to this MIMO stream. signal. Channel estimation is a critical procedure in a 5G NR communication system, and its reliability is of paramount importance. In this regard, high-quality reception of DMRS signals on the receiving side is of great importance.

For the simultaneous transmission of multiple DMRS signals of the respective MIMO layers in the 5G NR communication system, their proper resource element multiplexing (RE) is used. In the context of DMRS multiplexing in the 5G NR communication system, two types of DMRS structures are supported: a Type 1 (Type 1) DMRS structure and a Type 2 (Type 2) DMRS structure, which are illustrated in the resource element grid in FIG. 2a and 2b, where each RE is defined by a subcarrier in the frequency domain and an OFDM symbol in the time domain.

First of all, the subcarriers in the frequency domain are divided into CDM groups. For the Type 1 structure, two CDM groups are defined, in which case the distribution of subcarriers in the frequency domain is uniform, i.e. the distance between subcarriers of different CDM groups is always the same (see Fig. 2a). CDM groups are indexed by the index Δ. Further, in each of the two CDM groups, DMRS signals are multiplexed by applying orthogonal codes (OCCs) in the frequency domain (FD) of length 2 and OCCs in the time domain (TD) of length 2. Each of the FD-OCCs and each of the TDs -OCC also has its own index. Thus, in a Type 1 structure, 8 DMRS signals are multiplexed: 2 CDM groups × 2 FD-OCCs of length 2×2 TD-OCCs of length 2, i.e. 8 DMRS ports are defined for corresponding 8 parallel spatial MIMO streams.

For the Type 2 structure, three CDM groups with non-uniform distribution in the frequency domain are defined (see Fig. 2b). Further, in each of the three CDM groups, the DMRS signals are multiplexed again by applying a FD-OCC of length 2 and a TD-OCC of length 2. Thus, 12 DMRS signals are multiplexed in a Type 2 structure: OCC length 2×2 TD-OCC length 2, i.e. 12 DMRS ports are defined for the corresponding 12 spatial MIMO streams.

Therefore, a maximum of 12 spatial MIMO streams on the TRP side is supported in the 5G NR communication system.

It should be emphasized that the multiplexed DMRS signals in each CDM group of both Type 1 and Type 2 structures are orthogonal, i.e. do not interfere with each other. Orthogonality in this case is of utmost importance for the correct reception of DMRS signals and, therefore, reliable channel estimation.

It should be noted here that although, as follows from the above, up to 12 MIMO streams are generally supported on the base station side, a maximum of 8 MIMO streams are supported in the SU-MIMO mode, i. no more than 8 MIMO streams can be transmitted to one UE at a time. In addition, the 5G NR communication system provides semi-static switching between Type 1 and Type 2 DMRS structures through Radio Resource Control (RRC) signaling when the maximum number of transmitted MIMO streams needs to be increased or decreased accordingly; in other words, their number before transmission is not known a priori. Thus, the UE needs to know in advance which DMRS ports to use for receiving the downlink (DL) data channel as well as for transmitting the uplink (UL) data channel.

The general scheme for informing the user equipment (UE) about the used DMRS ports in the 5G NR system is shown in FIG. 3.

According to FIG. 3, a Physical Downlink Control Channel (PDCCH) carrying a signaling message of Downlink Control Information (DCI) is initially transmitted from the TRP to the UE. In DCI, the user equipment is informed of the PDSCH/PUSCH transmission parameters selected by the scheduler on the TRP side, primarily that a PDSCH transmission is scheduled to the user equipment. The DCI also sends information to the UE about the DMRS port numbers to be used for demodulating the scheduled number of MIMO PDSCH streams, as well as for scheduling the PUSCH transmission. In addition, other overhead information may be included in the DCI, such as modulation and coding scheme (MCS), frequency domain resource allocation (FDRA), adaptive spatial signal processing, and the like.

The above communication is relatively fast (in terms of low latency) since it is carried out at the physical layer in a compact DCI message. At the same time, this compactness implies a hard limit on the total number of bits in a DCI message (no more than 50-70 bits in a 5G NR system), and, therefore, information about the DMRS ports used should be encoded in DCI with minimization of bit consumption.

On FIG. 4a, 4b illustrate the data organization approach used in the 5G NR system to implement informing the UE about the DMRS ports to be used. In accordance with the multiplexing described above, each DMRS port may be associated with a unique set of CDM group index, FD-OCC, and TD-OCC. It should be noted that the term 'DMRS port' often refers directly to the unique combination of CDM group, FD-OCC and TD-OCC. On FIG. 4a, the correspondence of the DMRS port number to the combination of the above parameters is shown as a table for Type 1 DMRS. MIMO Physical Data Channel Streams), FIG. 4b illustrates in tabular form the coding of the DMRS port combination to use (right column) with its one-to-one mapping of the encoding parameter (left column). It is the value of this code parameter that is transmitted from the TRP in the DCI to the UE to inform the UE of the specific combination of DMRS ports to be used for the PDSCH or for the PUSCH. It should be noted here that the DMRS port index notation '0', '1', '2', '3' used in the right column of the table in FIG. 4b is respectively equivalent to the DMRS port index notation '1000', '1001', '1002', '1003' used in the left column of the table in FIG. 4a; these notations can be used interchangeably in the present application in a manner understandable to those skilled in the art.

With respect to the middle column in the table in FIG. 4b, it should be noted that the OFDM symbols allocated for the transmission of DMRS signals may be partly used for the transmission of the physical data channel (PDSCH or PUSCH). In particular, the DMRS port combination informing code parameter of the UE according to FIG. 4b is mapped to the number of CDM groups not used for data transmission. For example, for a code parameter equal to '0', the first CDM group of the DMRS OFDM symbol should be used for DMRS transmission, while the second CDM group for transmission of the physical data channel (PDSCH). For a code parameter equal to '3', the physical data channel on the OFDM symbol allocated for DMRS is not transmitted. Here, the first and second CDM groups are used for DMRS transmission for two or more users. Multiplexing DMRS with a data channel in one OFDM symbol can reduce the overhead associated with DMRS transmission.

Fig. 5a-5c illustrate timing resource allocation methods in a 5G NR wireless communication system at the physical layer.

The 5G NR system supports two types of timing schemes for transmission of the physical data channel: Type A and Type B. FIG. 5a shows the first approach (Type A) in which the minimum time resource allocation unit for PDSCH transmission is one downlink slot (DL slot) consisting of 14 OFDM symbols. The illustration in FIG. 5a is shown for the frequency range used in 5G NR with a carrier frequency of about 3.5 GHz. Similarly, the minimum time resource allocation unit for PUSCH transmission is one slot (UL slot). Type A is characterized by limited ability to vary the start OFDM symbol (0 to 3) of the data channel within a slot.

On FIG. 5b illustrates an example of the distribution of time resources according to the scheme Type A over a longer time interval. Each 10 ms frame in the system is partitioned into a number of downlink-uplink (DL/UL) periods, each including a corresponding number of DL slots and UL slots separated by a guard interval to allow switching between DL and UL. As can be seen from the illustrations in Fig. 5a, 5b, OFDM symbols are allocated in each DL/UL slot for transmitting a physical control channel and DMRS signals. It should be noted that the ratio between the number of DL slots and UL slots in a DL/UL period is flexibly configurable.

Type A is typically used for enhanced mobile broadband (eMBB) traffic, which corresponds to, for example, regular Internet traffic on smartphones.

On FIG. 5c illustrates another type of time allocation used in 5G NR, namely Type B, whose minimum time allocation unit is a minislot. constituting 2 (as shown in FIG. 5c), 4, or 7 OFDM symbols. Typically, a downlink physical control channel (DL-ctrl) is associated with each of these PDSCH transmissions, each minislot also contains DMRS signals (not shown in FIG. 5c). The same is true for PUSCH transmissions. This type, in particular, is characterized by greater flexibility in varying the start symbol of the data channel (from 0th to 12th) within the slot. PDSCH minislot start symbol information is reported to the UE in DL-ctrl.

Type B is typically used for Ultra Reliable Low Latency Communication (URLLC) traffic, which is mostly used for communication in industrial applications (eg, between robots, etc.) where reliability/reliability and latency requirements are high.

It should be noted again that the frame, slot, minislot configurations shown are quite flexible in 5G NR, and FIG. 5a-5c are provided by way of illustration only to provide a thorough understanding of the present application.

Finally, although as discussed above, DMRS signals transmitted from one base station are orthogonal, i.e. they do not interfere with each other within the cell served by the base station, however, there is initially no orthogonality between the DMRS signals of neighboring cells, which can lead to mutual interference at cell boundaries. To randomize the interference, DMRS signals transmitted from the base station are also subjected to quadrature phase modulation (QPSK modulation). In the 5G NR QPSK system, modulation is performed using a Gold sequence of length 31 with initialization common across CDM groups or individual for each CDM group. In the latter case, two initialization values (seed) are configured for each base station by RRC signaling and dynamically reported to the UE by DCI for subsequent demodulation. Thus, the sets of initialization values are different for different TRPs, which ensures that the DMRS signals transmitted by different TRPs are different. It should be noted that a similar procedure is used in UL to randomize interference between DMRS signals from users served by adjacent TRPs.

The operational aspects of 5G NR wireless communication systems, briefly described above, are detailed in TS 38.211, 38.212 "NR; Physical channels and modulation", v17.3.0, 2022-09-21, 3gpp.org, which are included in their entirety in the present description by reference.

Although the deployment of 5G NR systems in the world is just beginning to gain momentum, active research is already underway in various directions to standardize next-generation wireless communication systems, the so-called. 6G, which will have characteristics that are superior to 5G NR.

In particular, for the 6G 10-12 GHz operating band (UPPER MID BAND) at base stations (TRP), it is planned to support ultra-large antenna arrays, with at least 1024 antenna elements, hybrid analog and digital beamforming with a large number of antenna ports (≥128 ). Thus, with support for, in particular, up to 64 simultaneously transmitted spatial MIMO streams in UPPER MID BAND communication systems, the concept of a radio interface with an extra large antenna array (Massive MIM0) will be taken to a fundamentally new level.

In 6G, it is planned to support a set of reference signals similar to those used in 5G NR, such as DM-RS, CSI-RS, SRS, PT-RS, PSS/SSS. Details regarding the specified RS are given in the above specifications. At the same time, approaches to working with reference signals used in 5G NR cannot always be extrapolated to next generation wireless communication systems.

In particular, the above-described DMRS structures used in 5G NR systems can provide multiplexing of a maximum of 12 DMRS signals, while in a 6G system, at least 64 spatial MIMO channels and, accordingly, 64 DMRS signals must be provided in parallel. In other words, the existing DMRS structures cannot provide multiplexing of the number of DMRS signals required for 6G.

Then, as mentioned earlier with reference to FIG. 2a, 2b, the Type 2 DMRS structure has a non-uniform distribution of subcarriers in the frequency domain, in contrast to the uniform nature of the Type 1 structure. higher complexity. This is not a serious problem for the relatively small number of DMRS ports in 5G NR, but may be unacceptable for the significantly larger number of them in 6G, since the complexity of the channel estimation algorithm in the case of the above unevenness increases significantly.

Further, when it becomes necessary to adjust the density of the DMRS structure in the frequency domain (due to the regulation of the number of available DMRS ports), the 5G NR communication system performs a corresponding switch between Type 1 and Type 2 structures, which are associated with different channel estimation algorithms that differ in that number by difficulty. Given that this switching, as mentioned earlier, has a semi-static character, i.e. dynamic switching between Type 1 and Type 2 structures is not supported in 5G NR. In other words, there is very limited flexibility in adapting the DMRS structure, with switching between actually inconsistent structure types. In 6G, implementing this approach would lead to an unacceptable increase in complexity on the receiver side.

Thus, there is an urgent need to develop a new DMRS structure for next generation wireless communication systems (including 6G), which would satisfy the following design requirements:

support for more DMRS ports (up to 64);

adaptability of the DMRS structure depending on the bandwidth requirements, with the possibility of varying its density in frequency and time without modifying the DMRS structure itself;

maintaining a low complexity of the channel estimation algorithm.

When designing this DMRS structure, it must be taken into account that, in view of the above requirement to increase its capacity (the possibility of multiplexing a larger number of DMRS signals for a corresponding larger number of MIMO channels), such a structure will include a larger number of REs, including taking up a larger number of OFDM symbols in the time domain. If we use time allocation similar to 5G NR, then the relatively high DMRS transmission rate characteristic of 5G NR will inevitably lead to an undesirable increase in overhead in the case of a more capacious DMRS structure.

In the prior art known technical solutions related to the allocation of resources in the time domain for advanced communication systems. Such technical solutions are proposed, in particular, in US 11297635, US 10560934, CN 110121849.

US 112 97 635 proposes a minislot grouping method in an OFDM-based wireless communication system in which minislots are aggregated to increase the probability of successful reception by retransmitting a given block of data. This may aggregate minislots that are adjacent in time and/or frequency, and may also aggregate minislots from different slots. The disadvantage of the approach proposed in US 11297635 in this context is the impossibility of using this approach to solve the above problem of overhead associated with DMRS.

US 10560934 proposes transmission time interval (TTI) aggregation for downlink (DL) communications. The base station may determine to provide TTI aggregation for DL communications for at least one wireless link carrier. The base station may instruct the user device to provide TTI aggregation for DL communications for said specific wireless link carrier(s). The base station may subsequently perform downlink transmissions based on TTI aggregation to the user device on said specific carrier(s). This approach according to US 10560934 provides an improvement in the DL coverage of the PDSCH based on the component carrier. At the same time, its main disadvantage is that the PDSCH structure remains unchanged and, therefore, the overhead problem associated with DMRS cannot be solved based on this approach for next generation communication systems, including 6G with massive MIMO and operation in UPPER MID BAND.

In accordance with the approach proposed in CN 11012184 9, the first device can eliminate the first type of data or control information in at least two minislots and replace it with a second type of data or control information. Here, the first device may aggregate these at least two minislots within a subframe, wherein the subframe may include a portion for carrying positive acknowledgment (ACK)/negative acknowledgment (NACK) information associated with the second type of data or control information, and the first the device may communicate with the UE during said at least two minislots in a subframe. The second device may receive ACK/NACK information associated with the second type of data or control information, and the second device may reduce the transmit power for the first type of data or control information during a subsequent subframe when the ACK/NACK information indicates a negative acknowledgment. The disadvantages of the approach proposed in CN 11012184 9 are that the position of the DMRS (if present) is fixed in the slot, and that the same DMRS density is implied, whereas for scheduler decisions in next generation communication systems it is possible variation in the DMRS structure.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide techniques for allocating time domain resources for broadband data transmission that would avoid these negative effects, primarily the increase in overhead associated with DMRS.

In the context of solving this problem, according to the first aspect of the present invention, a method for allocating resources in the time domain performed at a base station (TRP) in a wireless communication system is provided. The TRP is configured to support simultaneous transmission of multiple spatial MIMO streams for data transmission, with each of the multiple MIMO streams associated with a different demodulation reference signal (DMRS signal).

The proposed method comprises, in the downlink-uplink period (DL/UL period) portion of a frame corresponding to the DL transmission (DL portion): allocate a predetermined number of contiguous OFDM symbols for downlink control channel transmission; generating a DL block of slots containing an integer number of adjacent slots, each slot including a predetermined number of OFDM symbols, wherein the downlink control channel refers to the entire DL block of slots; allocating at least one DL subblock of OFDM symbols for transmitting DMRS signals (DL DMRS subblock) for the required number of downlink physical shared data channel (PDSCH) MIMO streams; and allocating OFDM symbols in the DL slot block for PDSCH transmission. The method also comprises allocating a DL block of slots for DL transmission. At the same time, overhead information is carried in the downlink control channel, including at least an indication of the beginning of the DL block of time intervals and the duration of the DL block of time intervals. Preferably, the frame duration is 10 ms, the frame contains a plurality of DL/UL periods and the duration of the DL/UL period is set by the base station.

The downlink control channel is preferably a physical downlink control channel (PDCCH) and the overhead is represented as a downlink control information (DCI) carried on the PDCCH, wherein the slot block DL start indication is preferably the slot block DL start OFDM symbol indication. intervals.

According to an embodiment of the present invention, a timeslot is a slot containing 12 or 14 OFDM symbols. Meanwhile, the OFDM symbols allocated for transmission of the downlink control channel may be the initial OFDM symbols of the first DL slot of the slot block. Moreover, the DL block of slots may include the at least one DL DMRS sub-block, wherein the first DL DMRS sub-block of the at least one DL DMRS sub-block may be adjacent to the OFDM symbols allocated for downlink control channel transmission. . The indication of the beginning of the slot block DL may be the indication of the start slot of the slot block DL.

According to an embodiment of the present invention, said at least one DL DMRS subblock is a plurality of DL DMRS subblocks separated from each other by a DL period of a controlled number of OFDM symbols, the overhead further including a DL period. The DL period is adjustable on TRP. At the same time, the amount of resources allocated for the transmission of DMRS signals in the first DL DMRS sub-block of the above set may be greater than the amount of resources allocated for the transmission of DMRS signals in each of the subsequent DL DMRS sub-blocks of the above set, so that the number of OFDM symbols of this subsequent DL DMRS subblock is less than the number of OFDM symbols of the first DL DMRS subblock.

According to an embodiment of the present invention, a timeslot is a minislot, whereby a minislot may comprise 1, 2, 4, or 7 OFDM symbols. In this case, the boundaries of at least the first DL DMRS sub-block of the said at least one DL DMRS sub-block in the time domain can be aligned with the boundaries of the minislot.

According to an embodiment of the present invention, the proposed method further comprises performing, on data to be transmitted in OFDM symbols allocated to a PDSCH in a DL slot block, channel coding and obtaining code blocks representing encoded data. The number and length of code blocks are selected according to the duration of the time interval so that, when allocating time-frequency resources for each set of code blocks in the mentioned number, the boundaries of this set in the time domain are aligned with the boundaries of the time interval in the DL block of time intervals. The channel coding is preferably LDPC coding, with the number and length of code blocks selected according to the number of available resource elements (RE) in the time slot, the modulation used, and the coding rate.

According to an embodiment of the present invention, the DL/UL period further comprises a portion corresponding to the UL transmission (UL portion) after the DL portion. At the same time, the proposed method further comprises the steps, in which, in the UL part: form a UL block of time intervals containing an integer number of adjacent time intervals; allocating at least one UL subblock of OFDM symbols for transmitting DMRS signals (UL DMRS subblock) for a required number of MIMO streams of an uplink physical shared data channel (PUSCH); and allocating, in the UL block of slots, OFDM symbols for PUSCH transmission. The method also comprises allocating a UL block of slots for UL transmission. Here, the overhead information further includes an indication of the beginning of the UL of the slot block and a duration of the UL of the slot block. The method according to this embodiment may further comprise allocating a predetermined number of contiguous OFDM symbols in the UL portion for transmitting a Physical Uplink Control Channel (PUCCH). Here, the OFDM symbols allocated for PUCCH transmission may follow the UL of the DMRS subblock and the OFDM symbols allocated for PUSCH transmission. Or, the UL DMRS subblock and OFDM symbols allocated for PUSCH transmission may follow the OFDM symbols allocated for PUCCH.

According to an embodiment of the present invention, a UL slot is a slot containing 12 or 14 OFDM symbols. Here, the OFDM symbols allocated for PUCCH transmission may be the final OFDM symbols of the last UL slot of the slot block. The UL block of slots may include the at least one UL DMRS subblock; in particular, the UL block of slots may contain all the slots of the UL part.

According to an embodiment of the present invention, said at least one UL DMRS subblock is a plurality of UL DMRS subblocks separated from each other by a UL period of a controlled number of OFDM symbols, the overhead further including a UL period. At the same time, the amount of resources allocated for the transmission of DMRS signals in the first UL DMRS sub-block of the above set may be greater than the amount of resources allocated for the transmission of DMRS signals in each of the subsequent UL DMRS sub-blocks of the above set, so that the number of OFDM symbols of this subsequent UL DMRS sub-block is less than the number of OFDM symbols of the first UL DMRS sub-block.

According to an embodiment of the present invention, in the case where the UL timeslot is a minislot, the boundaries of at least the first UL DMRS subblock of the at least one UL DMRS subblock in the time domain are aligned with the minislot boundaries.

According to an embodiment of the present invention, the proposed method may further comprise performing, on data to be transmitted in OFDM symbols allocated for PUSCH in a UL slot block, channel coding and obtaining code blocks representing encoded data. The number and length of code blocks are selected according to the duration of the time interval so that, when allocating time-frequency resources for each set of code blocks in the mentioned number, the boundaries of this set in the time domain are aligned with the boundaries of the time interval in the UL block of time intervals. The channel coding is preferably LDPC coding, with the number and length of code blocks selected according to the number of available REs in the time slot, the modulation used, and the coding rate.

According to a second aspect of the present invention, there is provided a base station (TRP) in a wireless communication system, comprising at least: transceivers; data processing devices; and data storage devices storing computer executable codes which, when executed by data processing devices, cause the base station to execute the method according to any embodiment of the first aspect of the present invention. A computer-readable storage medium is also provided, on which computer-executable codes are stored, which, when executed by at least one data processing device of the base station (TRP) in the wireless communication system, cause the TRP to perform the method according to any embodiment of the first aspect of the present invention.

The technical result achieved by the present invention is to create efficient time domain resource allocation techniques for broadband data transmission based on flexible slot or mini-slot aggregation, providing a larger time domain resource allocation/scheduling unit, which allows the use of less frequent DMRS and downlink control channel transmissions. and thus at least avoid the increase in overhead, which is especially true in the case of higher capacity DMRS structures for next generation communication systems. It also provides an increase in the efficiency of pipelining the processing of code data blocks on the receiver side.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an exemplary transmitter-side spatial signal processing diagram;

Fig. 2a, 2b show Type 1 5G NR DMRS structure and Type 2 5G NR DMRS structure, respectively;

Fig. 3 is a general diagram of informing the UE about the used DMRS ports in 5G NR;

Fig. 4a, 4b illustrate the 5G NR approach to informing the UE about the DMRS ports to be used;

Fig. 5a-5c are illustrations of time resource allocation in 5G NR;

Fig. 6 is an illustrative diagram of a wireless communication system in which embodiments of the present invention may be implemented;

Fig. 7 is a schematic representation of a DMRS structure according to a preferred embodiment of the present application;

Fig. 8 is a schematic representation of a DMRS structure according to another embodiment of the present application;

Fig. 9 is a block diagram of an embodiment of a method for multiplexing DMRS signals according to the present application;

Fig. 10 is a schematic representation of an adapted DMRS structure according to an embodiment of the present application;

Fig. 11 is a block diagram of an embodiment of a wireless communication method according to the present application;

Fig. 12a - 12d show illustrative embodiments of the adaptation according to the present application;

Fig. 13a, 13b illustrate the selection of a reduced DFT OSS configuration according to an embodiment of the present application;

Fig. 14 is a block diagram of another embodiment of a wireless communication method according to the present application;

Fig. 15 is a flowchart of a method for specifying DMRS ports for a UE according to one embodiment of the present application;

Fig. 16a, 16b, 17 are illustrations of a tree hierarchy of DMRS port groups and their coding;

Fig. 18 is a flowchart of a method for specifying DMRS ports for a UE according to another embodiment of the present application;

Fig. 19a-19c are illustrations of a tabular representation of DMRS adjacent port grouping;

Fig. 20 is a flowchart of a method for specifying DMRS ports for a UE according to another embodiment of the present application;

Fig. 21 is an example of coding a combination of DMRS ports according to an embodiment of the method of FIG. 20;

Fig. 22a is an illustration of a general DMRS port table preprocessing approach for the case of deleting a portion of DMRS ports according to an embodiment of the present application;

Fig. 22b is an example implementation of the general approach of FIG. 22a;

Fig. 23 illustrates an attempt to use a 5G NR approach to time resource allocation in a next generation wireless communication system;

Fig. 24a, 2-4b show exemplary embodiments of time domain resource aggregation for the DL portion of a DL/UL frame period according to the present invention;

Fig. 25a, 25b are a high-level representation of resource aggregation according to the present invention;

Fig. 26a, 26b are illustrations of periodic allocation of DMRS sub-blocks in time domain resource allocation according to an embodiment of the present invention;

Fig. 27 is an illustration of time domain resource aggregation for providing pipelining of code block processing at the receiver side according to an embodiment of the present invention;

Fig. 28a, 28b are a flowchart of a time domain resource allocation method according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to exemplary embodiments of the present invention, which are illustrated in the accompanying drawings, where like reference numerals designate like elements. It should be understood that embodiments of the invention may take various forms and should not be construed as limited by the descriptions given here. Accordingly, illustrative embodiments are described below with reference to the figures of the drawings in order to clarify the essence of the aspects of the present invention.

On FIG. 6 generally illustrates a wireless communication system in which various aspects of the present invention may be implemented. As shown in FIG. 6, user equipments (UEs) 601 communicate with base stations (TRPs) 602 in a radio access network (RAN) 600. UEs 601 (e.g., UEs 601-1, 601-2, 601-3, ...) are distributed across RANs 600, and each of the UEs 601 may be fixed or mobile. Well-known examples of UEs are smartphones, tablets, modems, and the like.

Base stations 602 (eg, TRPs 602-A, 602-B, 602-C) can provide radio coverage for a specific geographic area, often referred to as a "cell". Base stations 602 are generally fixed in design, but may also be mobile. In general, base stations can be macro TRP (as illustrated by TRPs 602-A, 602-B, 602-C in FIG. 6) as well as pico TRP for pico or femto TRP for femto. Cells, in turn, can be divided into sectors.

Base stations 602 may be coordinated and controlled by a network controller in communication with them (eg, via a backhaul). The RAN 600 may be in communication with a core network (CN) (eg, via a network controller) that provides various network functions such as, for example, access and mobility control, session management, authentication server function, application function, and the like. . However, base stations 602 in RAN 600 may also be interconnected (eg, via a direct physical connection).

As a user device moves within the RAN 600, it can be handovered from one TRP to another TRP. For example, UE 601-3 may be handed over from TRP 602-B to TRP 602-A. This reconfigures the corresponding operating parameters of the UE to work with the new TRP. UE handoff may also be performed between sectors of the same TRP.

The 5G NR wireless communication system implements the concept of cloud RAN (Cloud RAN, C-RAN), which consists in dividing the base station into three parts and using a special interface defined to exchange information between these functional parts. Thus, the TRP can be divided into a radio unit (RU) that performs the functions of a radio transceiver, a distributed unit (DU) for L1 calculations (physical layer) and L2 calculations (MAC layer), and a centralized unit (CU) for L2 and L3 calculations (layer RRC). This separation allows the CUs to be centralized at the respective central node of the network, while the DUs can be more distributed, at the cell sites. In this case, connection switching between cell sites can be carried out at the L1 level, that is, with relatively low delays. This concept is also expected to be supported in next generation wireless networks.

It should be noted that the description in FIG. 6 and this figure itself are purely illustrative, non-limiting, for the purpose of delineating the general working environment of the present invention. Although in Fig. 6 illustrates only known basic components of a communication system, it should be understood that the communication system may further include a variety of other elements.

Each of the TRPs 602 shown in FIG. 6 includes the hardware and logic to implement the respective functions in the TRP. Hardware includes, in particular, an antenna array consisting of transceiver antenna elements discussed above, various specially configured processors, controllers, data storage devices, other circuit elements, as well as buses connecting them. The logic means includes software stored in the respective storage devices and configuring the respective circuit elements. Software also includes firmware directly embedded in processors and controllers. These hardware are configured, among other things, to perform various processing on transmitted and received signals, including (de)modulation, (de)multiplexing, (de)coding, amplification, filtering, digitizing, (de)interleaving, resource allocation, reception/transmission planning.

Similarly, each of the UEs 601 shown in FIG. 6 includes hardware and logic for implementing the respective functions in the UE. Hardware includes, in particular, transceivers with appropriate antenna elements, various specially configured processor(s), controllers, data storage devices, other circuit elements, as well as the buses connecting them. The logic means includes software stored in the respective storage devices and configuring the respective circuit elements. The software also includes the firmware directly flashed into the controllers. These hardware are configured, inter alia, to perform various processing on transmitted and received signals, including (de)modulation, (de)multiplexing, (de)coding, amplification, filtering, digitization, (de)interleaving. In addition, the UE contains means for user interaction, including a touch screen, speakers/microphone, buttons, as well as user applications stored in the memory of the UE and executed by the processor of the UE in the corresponding operating system.

Examples of the above processors/controllers include microprocessors, microcontrollers, digital signal processing (DSP) devices, field programmable gate arrays (FPGAs), discrete hardware chips, and the like. (Firmware) executable by processors/controllers should be interpreted broadly to mean computer-executable instructions, instruction sets, program code, code segments, subroutines, program modules, objects, procedures, and the like. The software is stored on suitable computer-readable media, which may be implemented as RAM, ROM, EEPROM, solid state memory, magnetic memory, optical memory, and the like, for example. , on which the corresponding program codes and data structures can be written or stored, which can be accessed by the corresponding processors/controllers.

The above hardware and software elements of the TRP and UE are configured to enable the TRP and UE to perform the methods of the present application, which are described below. The very implementation of the TRP and UE component hardware and their specialized configuration, incl. by appropriate logical means, is known in the technical field to which the present application relates. In this case, various functions according to the methods of the present application can be performed in a variety of individual elements or one or more integral elements, which is determined by the design structural characteristics.

I. DMRS Multiplexing

Next, with reference to FIG. 7-9 describe a method for multiplexing DMRS signals for wideband transmission according to the present application.

The proposed method is carried out on a communication device of the transmitting party in a wireless communication system, preferably a next generation communication system. The communication device of the transmitting side supports the simultaneous transmission of multiple spatial MIMO streams to transmit one physical data channel. As mentioned earlier, a different DMRS signal is associated with each of the multiple MIMO streams. The transmitting side communications device may be a TRP (eg, TRP 602 of FIG. 6), in which case the physical data channel is the PDSCH. Alternatively, the transmitting side communication device may be a UE (eg, UE 601 of FIG. 6), in which case the physical data channel is PUSCH.

Below, without loss of generality, description will be made for the case where the communication device of the transmitting side is TRP.

As noted above, in a 6G wireless communication system for the 10-12 GHz band, it is implied to support a significantly larger number of spatial MIMO streams than in 5G NR. In the following, the case of 64 simultaneously transmitted spatial MIMO streams will be considered as a preferred exemplary embodiment of the present invention. As will be shown below, the proposed technical solution covers the cases of both more and fewer MIMO streams.

On FIG. 7, the DMRS structure of the present application is illustrated on a time-frequency grid of resource elements (REs). This DMRS structure provides multiplexing of 64 DMRS signals for respectively 64 spatial MIMO PDSCH streams. That is, the DMRS signals are multiplexed over the resource elements of the DMRS structure.

As noted earlier, on a time-frequency grid, each RE in the frequency domain is defined by an OFDM subcarrier, and in the time domain by an OFDM symbol. According to OFDM, the frequency band of a system is partitioned into a plurality of subcarriers, and each of the OFDM subcarriers can be modulated with data. The total number of OFDM subcarriers depends on the frequency range of the system, and the spacing between adjacent subcarriers may be fixed or variable. So, in 5G NR, a basic subcarrier spacing (SCS) of 15 kHz is supported, and other SCSs are also supported relative to the basic SCS, for example, 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc.

As shown in FIG. 7, each of the OFDM subcarriers in the proposed DMRS structure is assigned to one of four CDM groups. Each of the CDM groups shown in FIG. 7 has its index Δ, from 0 to 3, and is shown in a different manner. In each of the CDM groups, modulation of DMRS signals is performed by applying length 4 discrete Fourier transform (DFT) based FD-OCC (DFT FD-OCC) and length 4 DFT based TD-OCC (DFT TD-OCC).

In general, FD-OCC DFTs are given by the following equation

where k _ƒ is the index of the frequency domain orthogonal code, K _f is the code length, j is the imaginary unit. In this case, K _f =4, and the possible FD-OCC DFTs are illustrated in Table 1.

Similarly, in general, TD-OCC DFTs are given by the following equation

where k _t is the index of the time domain orthogonal code, K _t is the code length. In this case, K _t =4, and the possible TD-OCC DFTs are illustrated in Table 2.

As a result, the DMRS signals in each CDM group are mutually orthogonal.

So, the proposed DMRS structure provides orthogonal multiplexing of 64 DMRS signals: 4 CDM groups ×4 DFT FD-OCC of length 4 × 4 DFT TD-OCC of length 4.

From FIG. 7 it can be seen that the DMRS structure is continuously repeating over the set of OFDM subcarriers, while this structure is uniform in the frequency domain - the distance between the subcarriers of any one CDM group in the DMRS structure is the same, due to which, in turn, the complexity of the channel estimation algorithm on the receiving side is maintained at a relatively low level.

As noted earlier, the DMRS structure described above is preferred, but not the only possible one. Below in FIG. 8 shows a uniform DMRS structure in accordance with the present application, providing orthogonal multiplexing of 128 DMRS signals for respectively 128 simultaneously transmitted spatial MIMO PDSCH streams by using a DFT TD-OCC of length 8, i.e. in Equation (2) K _t =8.

In modern communication systems, resource planning in the frequency domain is not carried out at the level of individual subcarriers, but with some granularity. Say, in a 5G NR wireless communication system, the minimum resource allocation unit in the frequency domain is 1 resource block (RB) consisting of 12 consecutive OFDM subcarriers.

As seen from FIG. 7, 8, the boundary of the present DMRS structure containing 16 consecutive OFDM subcarriers in the frequency domain will not coincide with the boundary of one RB. Therefore, according to the present application, it is proposed to perform resource scheduling for transmission with such granularity that in the frequency domain the boundary of the integer S of consecutive DMRS structures is aligned with the boundary of the integer number PPRB of consecutive PRBs. In the case illustrated in FIG. 7, 8, resource scheduling in the frequency domain should be performed with a granularity of 4 PRBs (P _PRB =4), which will accommodate 3 consecutive DMRS structures (S=3). More examples of resource planning granularity will be shown below.

Next, with reference to FIG. 9 describes an embodiment of a method 900 for multiplexing DMRS signals according to the present application. By way of illustration, and not limitation, method 900 is performed at a base station (eg, TRP 602 in FIG. 6) that supports simultaneous transmission of multiple spatial MIMO PDSCH streams.

At step 910, for N MIMO streams (N is a positive integer), a DMRS structure is determined, consisting of resource elements RE, on which the corresponding N DMRS signals are multiplexed. Here, each of the OFDM subcarriers in the DMRS structure is assigned to one of the L CDM groups such that the distance between the OFDM subcarriers of any one CDM group in the DMRS structure is the same. In each CDM group, DMRS multiplexing is provided by using a DFT FD-OCC of length K _f and a DFT TD-OCC of length K _t . As previously stated, the DMRS structure is continuously repeating over a plurality of OFDM subcarriers in the frequency domain.

For the case discussed in Fig. 7, L=4, K _f =4, K _t =4 and, respectively, N=64; for the case discussed in Fig. 8, L=4, K _f =4, K _t =8 and, respectively, N=128. Below are examples with other values of the specified integer parameters. It should be noted here that K _f according to the present disclosure can also take on a value of 8.

As previously stated, step 910 of method 900 may also be performed on a UE capable of broadband transmission, given that a lower maximum number of simultaneous MIMO streams is supported on a UE than on a TRP. Let's say for the above case of planned support of 64 DMRS ports per TRP for 10-12 GHz 6G, a maximum of 16 DMRS ports will be supported per UE.

The method 900 may include subsequent steps performed on the TRP associated with using the DMRS structure defined in step 910 for communication.

Thus, in step 920, the TRP scheduler schedules PDSCH transmission to one or more UEs (eg, UE 601 of FIG. 6) using N MIMO streams. Also at this stage, the TRP scheduler may also schedule the PUSCH transmission with the UE.

In step 940, the TRP sends overhead information to the UE. The overhead contains information about the DMRS structure determined in step 910, including at least the parameters L, K _f and K _t . The signaling aspects of DMRS related UE signaling are described in more detail below.

According to a preferred embodiment, the overhead information is transmitted to the UE in a DCI carried by the PDCCH. The DCI also contains other information, as discussed above with reference to FIG. 3. In particular, the UE is also informed by DCI that a transmission is scheduled for it.

In accordance with other embodiments, the overhead information may be transmitted to the UE at the RRC layer (i.e. L3) or at the MAC layer (i.e. L2), which are higher layers than the physical layer (i.e. L1) on which DCI is transmitted.

In step 950, the TRP performs the scheduled broadband PDSCH transmission.

Below with reference to FIG. 10-14, options for adapting the proposed DMRS structure according to the present application will be described.

The need for such adaptation may arise in cases where the transmission of a large number (for example, 64) of spatial MIMO streams is no longer required, for example, in view of reducing the user load on the data channel, in which case they are reduced at the base station. Naturally, the DMRS structure must also be adapted to such a reduction by a corresponding decrease in the number of DMRS signals orthogonally multiplexed in it, or, in other words, by a corresponding decrease in the DMRS capacity.

One embodiment of the adaptation is based on the fact that the DFTs of the SSNs are highly parameterizable. So, in Fig. 10 shows the adaptation of the DMRS structure by setting the length K _f ' DFT FD-OCC and the length K _t ' DFT TD-OCC to 2 (see Equations (1), (2)), with the same four CDM groups.

This DMRS structure, which is continuously repeated over a plurality of OFDM subcarriers, provides orthogonal multiplexing of 16 DMRS ports for respectively 16 MIMO streams. This adapted structure has less DMRS capacity, but it has lower overhead (overhead) as well as better channel estimation due to higher DMRS density in the frequency domain.

As shown in FIG. 10, resource scheduling in the frequency domain in the case of this adaptation will be carried out with a granularity of 2 PRBs, which will accommodate 3 consecutive DMRS structures.

An additional possible implementation of the considered one embodiment is to adapt the DMRS structure by using two CDM groups and again setting the FD-OCC DFT length and TD-OCC DFT length to 2. The adapted DMRS structure thus obtained provides orthogonal multiplexing of 8 DMRS ports for, respectively, 8 MIMO streams. It should be emphasized that this adapted DMRS structure exactly corresponds to the 5G NR Type 1 DMRS structure discussed above with reference to FIG. 2a. Thus, the DMRS structure proposed here is backward compatible and can be used in existing wireless communication systems.

It should also be noted in light of the above that the DMRS structure shown in FIG. 7 can be obtained by adapting the DMRS structure shown in FIG. 8 by setting the length of the TD-OCC DFT to 4 while keeping the length of the FD-OCC DFT unchanged and four CDM groups.

Next, with reference to FIG. 11 describes an embodiment of a wireless communication method 1100 according to the present application. Method 1100 is performed at a base station (eg, TRP 602 of FIG. 6) that supports simultaneous transmission of N spatial MIMO PDSCH streams (eg, 64), each with a different DMRS signal associated with it.

At 1110, a PDSCH transmission is scheduled to at least one UE (eg, UE 601 of FIG. 6) using the required number M of MIMO streams out of N MIMO streams, where M is a positive integer less than N (eg, M=16 or 8).

At block 1120, an appropriate adaptation of the DMRS structure originally defined for the N MIMO streams is performed (see block 910 with reference to FIG. 9). As noted above, this original DMRS structure is characterized by the use of L CDM groups {L=4), DFT FD-OCC of length K _f and DFT TD-OCC of length K _t . For the present exemplary case N=64, this initial DMRS structure is illustrated in FIG. 7, where K _f =4 and K _t =4.

The DMRS structure is adapted in step 1120 by reducing the FD-OCC DFT length K _f to K _f ' and/or the TD-OCC DFT length K _t to K _t ', where K _f ' is a positive integer less than K _f and K _t ' a positive integer less than K _t ; wherein L may be set to 2 or 4. The adapted DMRS structure provides multiplexing of M DMRS signals for M MIMO streams.

For the case illustrated in FIG. 10 (M=16), L remains at 4, K _f '=2 and K _t '=2. For the case illustrated in FIG. 2a (M=8), L is set to 2, K _f '=2 and K _t '=2.

In step 1140, similar to step 940, the TRP sends overhead information to the UE. The overhead contains information about the DMRS structure adapted in step 1120, including at least the parameters L, K _f ' and K _t '.

At 1150, similar to 950, a scheduled PDSCH transmission is performed.

Another embodiment of adapting the DMRS structure proposed here is based on the exclusion of specific FD-OCC DFTs and/or specific TD-OCC DFTs from the respective available OCC DFTs, in the required number and without changing their length.

The considered another embodiment of the adaptation, as discussed earlier, is aimed at changing the corresponding density of DMRS signals in order to improve the quality of the channel estimate at the receiving side.

Broadly speaking, there is a DMRS structure in accordance with the present application with a set of K _f DFT FD-OCC and a set of K _t DFT TD-OCC available. For the DMRS structure illustrated in FIG. 7, the available sets of DFT OSS are shown in Tables 1 and 2, respectively {K _f =4, K _t =4). The approach under consideration is generally based on such exclusion of orthogonal codes from the available FD-OCC DFT set and/or from the available TD-OCC DFT set, i.e. such creation of the corresponding reduced subset of them, so that the reduced subset includes DFT OSS, for which the distance between code indices modulo code length was maximum. This maximization, in turn, provides an increase in the efficiency of the channel estimation at the receiving side, which will be discussed in more detail below.

The approach in accordance with the present application to the considered adaptation option is generally illustrated in FIG. 12a-12d: Fig. 12a, 12c for DFT TD-OCC and FIG. 12b, 12d are for DFT FD-OCC.

On each of Figs. 12a, 12b, the available DFT OSS sets are shown on a circle for clarity, with the indexing of the orthogonal codes in the set counterclockwise. While 8 DFT OCCs are shown, it should be understood that the available set may contain a different number of DFT OCCs, as implied by the dots in these figures.

The reduced DFT FD-OCC subset is defined according to the following expression:

Where

K _{t_reduced} is the required number of orthogonal codes in the subset, i.e. after reduction; K _t is the length of the DFT TD-OCC;

- TD-OCC DFT subset index;

i=0,1, ..., K _{t_reduced} -1 - DFT TD-OCC index in the reduced subset;

- operation of rounding up to the nearest smaller integer;

mod{a, b] (or b⋅mod(a)) - the operation of taking the remainder of dividing b by a;

k _t is the index of the TD-OCC DFT code sequence (code vector) in the initially available TD-OCC DFT set (see, for example, Table 2).

Black circles in Fig. 12a illustrates the TD-OCC DFTs constituting a reduced subset.

At the same time, in Fig. 12c specifically illustrates the options for reducing the initially available set of 8 TD-OCC DFTs, which corresponds to the exemplary DMRS structure of FIG. 8, up to a subset of 4 DFT TD-OCC according to the present application. As can be seen from this figure, subset 0 of 4 DFT TD-OCCs with indices k _t {0, 2, 4, 6} and subset 1 of 4 DFT TD-OCCs with indices k _t {1, 3, 5, 7} according to Equation (3).

Further, the reduced DFT FD-OCC subset is similarly defined according to the following expression:

Where

K _{f_reduced} - required number of orthogonal codes in the reduced subset;

_Kf is the length of the DFT FD-OCC;

- DFT FD-OCC subset index;

i=0,1, …, K _{ƒ_reduced} -1 - DFT FD-OCC index in the reduced subset;

k _ƒ is the DFT FD-OCC code sequence index in the initially available DFT FD-OCC set (see, for example, Table 1).

Black circles in Fig. 12b also illustratively labels the FD-OCC DFTs constituting a reduced subset. At the same time, in Fig. 12d, for illustration purposes only, shows possible options for reducing the available set of 2 DFT FD-OCCs to 1 DFT FD-OCC according to the present application.

On the circles in Fig. 12a-12c show the maximum 'distance' between DFT OSS remaining in the reduced subset. It should also be understood that the configuration of three reduced subset TD-OCC DFTs shown by way of illustration in FIG. 12a is not the only possible implementation, and subsets of the same size can be obtained from other code sequences with the same `distance' characteristic.

Similarly, the configuration of four reduced subset FD-OCC DFTs illustrated in FIG. 12b is not the only possible implementation, and subset(s) of the same size can be obtained from other k _ƒ code sequences with the same `distance' characteristic. Such possible implementations of one configuration are illustrated in FIG. 12s.

Table 3 below shows various configurations of reduced orthogonal code subsets for the DMRS structure proposed here, illustrated in FIG. 7 and in Tables 1, 2.

As mentioned above, DMRS capacity in Table 3 refers to the required number of DMRS ports used.

The selection of the reduced OSN DFT configuration from the corresponding initially available set of orthogonal codes is illustrated in FIG. 13a, 13b.

On FIG. 13a shows the formation of a reduced subset 0, consisting of DFT FD-OCC with index 0 and DFT FD-OCC with index 2, according to the approach according to the considered embodiment of the present application, which corresponds to configuration 1 or 3 in Table 3. Similarly, in FIG. 13b shows the formation of a reduced subset 1 consisting of a TD-OCC DFT with index 1 and a TD-OCC DFT with index 3, corresponding to configuration 2 or 3 in Table 3.

It should be emphasized here that the required orthogonality is maintained in each of the considered options for reduced subsets of DFT OSS.

The above-described alternative implementation of adapting the DMRS structure provides an additional gain on the receiving side, since the approach proposed in this application for the formation of reduced code sets in order to reduce the capacity of DMRS provides a more reliable elimination of mutual interference between DMRS signals, especially in view of various kinds of distortions that are transmitted MIMO streams may be subject to propagation; this in turn leads to better channel estimation at the receiving end.

It should be clarified here that when using orthogonal codes (OCC) in the DMRS structure, in order to eliminate mutual interference between orthogonal codes on the receiver side, it is necessary to carry out the compression (de-spreading) procedure of the received DMRS sequence over the entire length of the corresponding orthogonal code (for example, at length 4 , which corresponds to a number of embodiments of the present application). The code distance maximizing short set generation procedure as discussed above with reference to FIG. 12-13 provides full interference cancellation by decompressing the received DMRS sequence over a shorter length (eg, length 2). This makes it possible to minimize the impact of possible loss of orthogonality between codes in scenarios with significant frequency selective or time channel fading.

Next, with reference to FIG. 14 describes another embodiment of a wireless communication method 1400 according to the present application. Method 1400 is performed at a base station (eg, TRP 602 of FIG. 6) that supports simultaneous transmission of N spatial MIMO PDSCH streams (eg, 64), each with a different DMRS signal associated with it.

At 1410, a PDSCH transmission is scheduled to at least one UE (eg, UE 601 in FIG. 6) using the required number M of MIMO streams out of N MIMO streams, where M is a positive integer less than N (eg, M=32, 16 or 8).

At block 1420, an appropriate adaptation of the DMRS structure originally defined for the N MIMO streams is performed (see block 910 with reference to FIG. 9). As noted above, this original DMRS structure is characterized by the use of L CDM groups (L=4), DFT FD-OCC of length K _f and DFT TD-OCC of length K _t . For the present exemplary case N=64, this initial DMRS structure is illustrated in FIG. 7, where K _f =4 and K _t =4.

The DMRS structure is adapted at 1420 by reducing K _f of initially available FD-OCC DFTs to a reduced subset of K _{f_reduced} FD-OCC DFTs and/or K _t of initially available TD-OCC DFTs to a reduced subset of K _{t reduced} TD-OCC DFTs, K _{f reduced} is a positive integer less than K _f and K _{t_reduced} is a positive integer less than K _t ; wherein L may be set to 2 or 4. The adapted DMRS structure provides multiplexing of M DMRS signals for M MIMO streams. Said reduction is performed such that the corresponding reduced subset includes the DFT-based OCRs for which the distance between code indices modulo code length is the maximum, as discussed above with reference to FIG. 12, 13 and Table 3.

In step 1440, similar to step 940, the TRP sends overhead information to the UE. The service information, in addition to the parameters L, K _f and K _t , also contains an indication of the reduced subset DFT FD-OCC and/or the reduced subset DFT TD-OCC. Aspects of overhead signaling, including indication of the set(s) of orthogonal codes, will be discussed below.

At 1450, similar to 950, a scheduled PDSCH transmission is performed.

It is necessary to pay attention to the fact that in any of the above adaptation options, the DMRS structure of the present application remains constant and maintains uniformity in the frequency domain. That is, the technical solution proposed here avoids switching to, in fact, a fundamentally different DMRS structure when it is necessary to change the DMRS capacity, as, for example, in the case of switching between Type 1 and Type 2 in 5G NR, and the associated increase in the complexity of the channel estimation algorithm on the receiving side.

According to the present application, the combined use of both disclosed options for adapting the DMRS structure is not excluded. For example, the DMRS structure shown in FIG. 8 can be adapted to the DMRS structure shown in FIG. 7 by correspondingly reducing the length of the TD-OCC DFT as previously discussed, and subsequently further adaptation can be performed on this adapted DMRS structure by eliminating orthogonal codes in accordance with the disclosure of FIG. 12, 13 with reference to Table 3.

Although the above adaptation methods according to the present application have been described for the case of decreasing DMRS capacity, it should be understood that they are applicable for the case of increasing it, when more MIMO streams may need to be transmitted again.

So, with reference to FIG. 11 illustrates an embodiment of a wireless communication method 1100 corresponding to at least a partial inversion of said first embodiment of adapting the DMRS structure. Method 1100 is performed at a base station (eg, TRP 602 of FIG. 6) that supports simultaneous transmission of N spatial MIMO PDSCH streams (eg, 64), each with a different DMRS signal associated with it. In the embodiment discussed here, it is understood that a previously adapted DMRS structure is currently used on the TRP in which M(M<N) DMRS signals are multiplexed (eg, the adapted DMRS structure illustrated in Fig. 10, where M=16).

At step 1110, another PDSCH transmission is scheduled for at least one UE (eg, UE 601 of FIG. 6) using M' MIMO streams, where M<M'≤N.

At step 1120, the adaptation of the DMRS structure is performed by correspondingly increasing the length K _f ' DFT FD-OCC to K _f '', where K _f '<K _f ''≤K _f , and/or increasing the length K _t ' DFT TD-OCC to K _t '', where K _t '<K _t ''≤K _t (see Equations (1), (2)). The adapted DMRS structure provides multiplexing of M' DMRS signals for M' MIMO streams. For the exemplary case discussed here, M'=N=64, the resulting DMRS structure in step 1120 is illustrated in FIG. 7, where K _f ''=K _f =4 and K _t ''=K _t =4 when L=4.

In step 1140, the TRP sends overhead information to the UE. The service information contains information about the structure of the DMRS received at step 1120, including at least the parameters L, K _f '' and K _t ''.

At 1150, another scheduled PDSCH transmission is performed.

For the case of inversion of said other implementation of the adaptation of the DMRS structure, the base station uses a new, increased value of the number of RSNs, for example, K _{t_reduced} =K _t (see Equation (3)) and/or K _{f_reduced} =K _f (see Equation (4) ) and signals this new value(s) to the UE.

Summarizing the above, the DMRS structure of the present application, on the one hand, allows multiplexing of a larger number of DMRS signals, corresponding to the requirements of next generation wireless communication systems (in particular, 64 in the case of the 10-12 GHz 6G frequency range), and, on the other hand, has flexible, dynamic (as opposed to semi-static in 5G NR) adaptability, without significant change in the DMRS structure itself (i.e., the proposed DMRS structure is unified) and maintaining proper quality and low complexity of the channel estimation on the receiving side, as well as supporting the reverse compatibility.

Further, as has been said many times before, DMRS signals transmitted from one base station are orthogonal, i.e. they do not interfere with each other within the cell served by that base station. For example, referring to the diagram in Fig. 6, DMRS signals transmitted from TRP 602-B do not interfere with each of UE 601-1, UE 601-2, UE 601-3 located in the cell served by TRP 602-B; The DMRS signals transmitted from the TRP 602-C do not interfere with each of the UE 601-4, UE 601-5, UE 601-6, UE 601-7 located in the cell served by the TRP 602-C. At the same time, orthogonality between DMRS signals of neighboring cells is not initially guaranteed, which can lead to interference at cell boundaries. As can be seen from FIG. 6, UE 601-3 is simultaneously within the radio coverage areas of the base stations TRP 602-A and TRP 602-B and in close proximity to the cell boundary served by the base station TRP 602-C. Therefore, at UE 601-3, interference may occur between DMRS signals received simultaneously from TRP 602-A, TRP 602-B, TRP 602-C. This possible non-orthogonality may lead to a highly undesirable reduction in the quality of the channel estimate at UE 601-3.

As in the case of the known wireless communication systems discussed above, in this application, in order to alleviate this problem, QPSK modulation is performed on the DMRS signals transmitted from each of the TRPs to provide inter-TRP randomization of the DMRS signals and , thereby avoiding mutual interference between them. As in the case of the mentioned known systems (in particular, 5G NR), according to the present application, the sequence of QPSK symbols for modulating the DMRS structure is obtained from pseudo noise (PN) sequences. More specifically, the PN sequences are Gold sequences of length 31. The initialization of the PN sequences is individually configurable for each base station. The initialization parameter (seed) of the PN sequence is referred to in this application as N _ID .

Initialization of PN sequences in accordance with the present application is illustrated below in Table 4 for the case of using the unified DMRS structure proposed here (see, for example, Fig. 7).

According to the present application, a set of sets of initialization parameters {N _ID ⁱ } is proposed. For Table 4, such sets correspond to its columns. Each initialization parameter in each of the sets is set independently for each of the L CDM groups, i.e. in general i=0, …, L-1; specifically for the case of Fig. 7 and Table 4 i=0, 1, 2, 3. Further, each of the sets of initialization parameters is associated with a unique parameter - scrambling parameter n _SCID - which, in fact, uniquely identifies the corresponding set of initialization parameters. The initialization parameter sets identified by any different n _SCIDs are element-wise distinct. The order of the initialization parameters {N _ID ⁱ }, i=0, 1, 2, 3 in the sets of initialization parameters respectively identified by the four scrambling parameters n _SCID , is specifically illustrated in Table 4. In this case, the cells highlighted in Table 4 with a thicker line , refer to the case of a structure with two CDM groups (i.e., L=2, Δ=0.1, i=0.1), which corresponds to the above-described 5G NR DMRS structures, as well as the aforementioned adapted DMRS structure according to the present application. Each of the neighboring base stations is assigned its own different n _SCID , i. e. its own different set of initialization parameters.

For the purposes of explaining the above in Table 4, for the set of initialization parameters identified by n _SCID equal to 0, the signals of the CDM group with index Δ=0 are modulated by the PN sequence initialized by N _ID ⁰ , the signals of the CDM group with index Δ=1 are modulated by the PN sequence , initialized by N _ID ¹ , the signals of the CDM group with the index Δ=2 are modulated by the PN sequence, initialized by N _ID ² , and the signals of the CDM group with the index Δ=3 are modulated by the PN sequence, initialized by N _ID ³ . A similar picture will be in the cases of n _SCID equal to 1, 2 or 3.

The use of scrambling parameters that uniquely identify the respective different sets of initialization parameters of PN sequences makes it possible to quickly, dynamically notify user devices about which initialization parameters to use for QPSK demodulation of received signals. This notification is preferably carried out by the DCI transmitted on the PDCCH. For example, including in the DCI transmitted with a TRP (eg, TRP 602-B of FIG. 6) n _SCID equal to 1 instructs all UEs currently served by this TRP to use the initialization parameter set {N _ID ¹ , N _ID ⁰ , N _ID ³ , N _ID ² } for CDM groups Δ=0, 1, 2, 3, respectively. It should be noted that the use of a single _SCID parameter n avoids excessive bit load on the DCI. It also provides fast (ie, low latency) initialization parameter set switching on the UE side. Following the example above, if a UE (eg, UE 601-3 of FIG. 6) subsequently receives from a TRP (eg, TRP 602-A of FIG. 6) a DCI with a different scrambling parameter, such as n _SCID equal to 3, then the UE 601-3 provides a hot switch to the corresponding set of initialization parameters {N _ID ³ , N _ID ² , N _ID ¹ , N _ID ⁰ }. It should be noted that the example of switching initialization parameters of PN sequences given here is purely illustrative.

It should be emphasized here that, thanks to the use of the C-RAN technology discussed above, in current and future wireless communication systems, in particular, fast switching of UEs between base stations is ensured. Therefore, there is a need for a corresponding operational switching between sets of initialization parameters. The technical solution described here allows to provide the required efficiency.

Thus, each of the methods 900, 1100, 1400 described above with reference to FIG. 9, 11, 14 is complemented, preferably before steps 940, 1140, 1440 sending overhead, with step 930, 1130, 1430, in which the DMRS is modulated with a sequence of QPSK symbols, which is obtained from PN sequences, each of which is initialized with a different parameter N An initialization _ID from a set containing L initialization parameters, with each of the L initialization parameter sets associated with a different scrambling parameter n _SCID , wherein in each of the L initialization parameter sets, each of the L initialization parameters is set different for each of the L CDM groups, so that for each of the L CDM groups, the initialization parameters are different for different scrambling parameters (see Table 4 for illustration). Here, the overhead for scheduling a PDSCH or PUSCH transmission, respectively transmitted in steps 940, 1140, 1440, preferably by DCI to each of the UEs served by the base station, further comprises the current value of the _scrambling parameter n used for said modulation, to instruct the UE to use the set of initialization parameters it identifies.

As noted earlier, a similar procedure is applied in the uplink to randomize interference between DMRS signals from UEs served by neighboring TRPs.

Approaches to the present application for multiplexing DMRS signals, disclosed above with reference to FIG. 7-14 are summarized by the following mathematical expression describing the DMRS signal value α for DMRS port p on subcarrier k and OFDM symbol 1:

Where

β ^DMRS - power offset for DMRS;

w _ƒ (k') - DFT FD-OCC (see Equation (1) and its explanation), where k _ƒ - DFT FD-OCC code vector index, - DFT FD-OCC length, k' - DMRS subcarrier index in CDM group (for the DMRS structure according to the present application, shown in Fig. 7, see Table 1: K _ƒ =4, k'=0, 1, 2, 3, k _ƒ =0, 1, 2, 3);

- DFT TD-OCC (see equation (2) and explanations thereto), where k _t is the code vector index of the DFT TD-OCC, K _t is the length of the DFT TD-OCC, - index of the DMRS OFDM symbol in the CDM group (for the DMRS structure according to the present application, shown in Fig. 7, see Table 2: K _t =4, k _t =0, 1, 2, 3);

k is the subcarrier index, where Δ is the index of the CDM group, L is the number of CDM groups (for the DMRS structure according to the present application, shown in Fig. 7, L=4, K _f -L=16);

- OFDM symbol index, where - index of the start OFDM symbol of the PDSCH slot block in the DL/UL period, - DMRS transmission event index in DL/UL period, T _DMRS - DMRS period. We are talking about DL / UL periods, as well as parameters T _DMRS will go in more detail in the following sections of the description of the present invention;

r(n) is a QPSK sequence, where c(…) is a Gold sequence of length 31, which is unique for each CDM group and, accordingly, is initialized for each CDM group with its own c _init . For the embodiment discussed above with reference to Table 4,

Where

n _SCID - scrambling parameter (according to the above with reference to Table 4, may be dynamically indicated in DCI among the values {00, 01, 10, 11}), N _ID - initialization parameter (see Table 4, while )

- the number of OFDM symbols in the DL/UL period,

- DL/UL-period index.

II. Specifying DMRS Ports for a UE

In view of the above when describing the prior art, in the context of designing next generation wireless communication systems (including 6G), the following problem occurs.

On the one hand, it is necessary to increase the capacity of the DMRS structure in view of a significant increase in the supported number of spatial MIMO streams for broadband data transmission. Meanwhile, in 5G NR, the DMRS port designation scheme outlined above with reference to FIG. 4a, 4b supports a maximum of 12 DMRS ports on the TRP side and a maximum of 8 DMRS ports per UE (SU-MIMO), in the absence of a systematic approach to expand this existing scheme to the required higher number of DMRS ports - specifically 64 on the TRP side and 16 on the UE side.

On the other hand, information about DMRS, incl. DMRS ports to be used should be reported to user devices with low latency, typically using DCI transmission on the PDCCH; however, there is a hard limit on the total number of DCI bits, as noted above. As a consequence, attempting to directly extrapolate existing scheme or similar approaches in next generation wireless communication systems to communicate to the UE the information about the DMRS ports to be used over the physical control channel will result in an unacceptably large number of bits in the DCI.

In the present application, in this context, techniques are proposed that provide efficient encoding of overhead information transmitted with TRP about a subset of DMRS ports to be used by a UE, with a relatively small bit load on the overhead.

Embodiment 1: Tree-Based Indication of DMRS Ports with Prefix Encoding

Next, with reference to FIG. 15-17 describe a tree-hierarchy-based implementation of specifying DMRS ports with prefix encoding according to the present application. First of all, with reference to FIG. 15 describes an embodiment of a method 1500 for specifying DMRS ports for at least one UE in a wireless communication system according to the general approach of this embodiment. Method 1500 is performed at a base station (eg, TRP 602 of FIG. 6) that supports simultaneous transmission of N spatial MIMO PDSCH streams (eg, 64), each associated with a different DMRS signal.

At 1510, a tree hierarchy of DMRS port groups is formed, where each hierarchy node corresponds to a group of one or more DMRS ports. Thus, each node at the lowest (leaf) level of the hierarchy corresponds to one of the given number N' of DMRS ports. Preferably, N'=N, ie. the total number of DMRS ports available for use on the TRP. At each subsequent level of the tree hierarchy, counting from its leaf level, each node corresponds to a group of DMRS ports obtained by combining the same number of different groups of DMRS ports from the previous level of the hierarchy. The topmost (sub-root) level of the DMRS port group tree is the level at which the number of DMRS ports in each DMRS port group is equal to the total number M of DMRS ports available for use by the UE (eg, 16), where M≤N' .

In step 1520, each node of the generated DMRS port group tree is represented by a code set. Each code set consists of a first subset of bits and a second subset of bits, with the number of bits in the first subset and the number of bits in the second subset being variable. For each DMRS port group hierarchy node at a particular hierarchy level, the first subset bits encode the number of DMRS ports in each DMRS port group at that particular hierarchy level, and the second subset bits encode the DMRS port group corresponding to that hierarchy node.

Step 1530 selects, in the DMRS port group tree hierarchy, a group containing C of the DMRS ports to be used by the UE, where C≤M.

At step 1540, a code set corresponding to the selected DMRS port group is determined from the code sets obtained at step 1520.

In step 1550, the overhead information is signaled to the UE, which includes the code set determined in step 1540. This signaling is preferably performed by the DCI transmitted on the PDCCH. The code set message at 1550 may direct the UE to use the selected C DMRS ports to receive the C MIMO PDSCH streams. Alternatively, this message may direct the UE to use the selected C DMRS ports to transmit C MIMO PUSCH streams.

The general approach outlined above with reference to FIG. 15 is illustrated in FIG. 16a, 16b with a specific embodiment of pairwise hierarchical grouping of DMRS port groups, in which case N and M are integers of degree 2.

On FIG. 16a, 16b show a single DMRS port group tree obtained according to this particular embodiment for the case N'=N=64 and M=16 (upper part of the figures), as well as their corresponding code sets (lower part of the figures).

The indexes used in the DMRS Port Group Tree Hierarchy shown correspond to consecutive DMRS Port Indexes. Each node at the lowest level of the hierarchy (leaf) corresponds to one of the 64 DMRS ports available for use on the TRP. Starting from the leaf level, each DMRS port group of the next level of the tree is obtained by combining two adjacent DMRS port groups from the previous level of the hierarchy so that each group of DMRS ports of the previous level of the hierarchy is included in only one group of DMRS ports of the next level of the hierarchy. At the topmost level of the tree in question, nodes correspond to four combinations of 16 serial DMRS ports that may be available for use by the UE.

Further, in each code subset, which are illustrated at the bottom of FIG. 16a, 16b, the second bit subset is the postfix subset and the first bit subset is the prefix subset. For each node in the tree hierarchy of DMRS port groups at its particular level, the prefix subset bits encode the number of DMRS ports in each DMRS port group at that particular hierarchy level, and the postfix subset bits encode the specific DMRS port group corresponding to that node. Thus, according to the illustration in Fig. 16a, the group of DMRS ports {12,13,14,15} is represented by the code set {0,0,1,0,0,1,1}, in which the prefix (0,0,1) essentially encodes the level a tree in which nodes represent groups of 4 DMRS ports each, and the postfix (0,0,1,1) encodes a specific group {12,13,14,15} at this level. Accordingly, at step 1550, the code set {0,0,1,0,0,1,1} will be signaled in DCI. Similarly, in FIG. 16a, the tree leaf corresponding to DMRS port 8 is represented by the code set {1,0,0,1,0,0,0}, in which the prefix (1) encodes the lowest level of the tree, and the postfix (0,0,1, 0,0,0) encodes a particular single port. In this case, at step 1550, the code set {1,0,0,1,0,0,0} will be signaled to the DCI. In both illustrative cases considered, the size of the code set is only 7 bits, i.e. the bit load on the DCI to indicate the desired combination of DMRS ports is low.

On FIG. 17 similarly illustrates the adaptation of the considered approach, when groups of DMRS ports are formed from a total of 16 DMRS ports, i.e. N'=M=16 (upper part of the figure), and are respectively represented by code sets (lower part of the figure). Each leaf at the lowest level of the tree hierarchy corresponds to a specific one of the 16 DMRS ports, and its topmost level corresponds to a combination of all 16 consecutive DMRS ports. Each code set similarly encodes a tree level with its prefix part and a specific group of DMRS ports with its postfix part. In the illustrative case discussed here, the size of the code set is 5 bits, i.e. the bit load on the DCI to indicate the desired combination of DMRS ports is again very low.

It should be understood that shown in FIG. 16, 17 and the corresponding disclosure, the bit representation of the code sets is illustrative, but not the only possible one. So, without loss of generality, in each code set, its postfix subset can encode a level of the DMRS group tree, and the prefix subset can encode a specific DMRS group from this level; in addition or in addition to this, in one or both of the postfix subset and the prefix subset, other combinations of bits may be used for encoding - in particular, the bit values in one or both of the postfix subset and the prefix subset may be respectively inverted: 0→1 , 1→0.

The advantages of the considered embodiment 1 are very low DCI bit load and good scalability. Its main disadvantage is its low flexibility, since only a relatively small number of well-defined combinations of adjacent DMRS ports can be specified for use.

Embodiment 2: Specifying Contiguous DMRS Ports

Next, with reference to FIG. 18, 19, a unique encoding (mapping) based implementation of specifying adjacent DMRS ports according to the present application is described. First of all, with reference to FIG. 18, an embodiment of a method 1800 for specifying DMRS ports for at least one UE in a wireless communication system according to the general approach of this embodiment is described. Method 1800 is performed at a base station (eg, TRP 602 of FIG. 6) that supports simultaneous transmission of multiple MIMO spatial PDSCH streams, each with a different DMRS signal associated with it.

In step 1810, a DMRS port group is selected containing C consecutive DMRS port indices to be used by the UE from a total of M consecutive DMRS port indices available for use by the UE, where C≤M.

In step 182 0, a code parameter P representing the DMRS port group selected in step 1810 is obtained. The code parameter is calculated as follows: if (C - 1) ≤ M/ ₂

otherwise

where s is the starting index of the DMRS port in the selected group of DMRS ports, s=0, 1, ..., C - 1.

At step 1830, the overhead information is signaled to the UE, which includes a binary representation of the code parameter P obtained at step 1820. This signaling is preferably performed by the DCI transmitted on the PDCCH. At the UE, the corresponding group of DMRS ports to be used can be explicitly recovered based on the received code parameter P. Here, similar to option 1, the code parameter message at step 1830 can direct the UE to use the selected DMRS ports C to receive C MIMO PDSCH streams, or tell the UE to use the selected C DMRS ports to transmit C MIMO PUSCH streams.

If a requirement is imposed to limit the bit size of the code parameter P, then the possible values of C can be further limited at step 1810 as 2 ^γ 3 ^ς , where γ and ς are non-negative integers, for example, C=2, 3, 4, 6, 8 , 9, 12, 16.

The general approach outlined above with reference to FIG. 18 is illustrated in FIG. 19a-19 with a tabular representation of specific embodiments of generating possible DMRS adjacent port groups from a total of M=16 consecutive DMRS port indices.

For example, by signaling code parameter P=12 in step 1830, the UE is directed to use the DMRS port combination {8,9,10,11,13} (see Fig. 19b).

Crossing out the table in FIG. 19c illustrates the above limitation of C values at step 1810 of method 1800; those. C=9 is excluded from use.

In the illustrative case considered here, the size of the code parameter does not exceed 8 bits, i.e. the bit load on the DCI to indicate the required combination of DMRS ports is again low, although generally higher than that according to Embodiment 1.

The advantages of the considered Embodiment 2 are low DCI bit load, good scalability for different number of DMRS ports supported, and greater flexibility compared to Embodiment 1 in terms of a greater variety of DMRS port combinations to choose from. It should also be noted that the coding considered here is highly efficient in terms of the compactness of representing all possible groups of adjacent DMRS ports from the total available number of them by means of the code parameter defined by Equation (6), without scatter and gaps.

Embodiment 3: Specifying DMRS Ports Based on Combinatorial Coding

Next, with reference to FIG. 20, 21 describes a combinatorial-based implementation of specifying generally non-adjacent DMRS ports according to the present application. First of all, with reference to FIG. 20, an embodiment of a method 2000 for specifying DMRS ports for at least one UE in a wireless communication system according to the general approach of this embodiment is described. Method 2000 is performed at a base station (eg, TRP 602 of FIG. 6) that supports simultaneous transmission of multiple MIMO spatial PDSCH streams, each with a different DMRS signal associated with it.

In step 2 010, a DMRS port group is selected containing C DMRS port indices to be used by the UE from a total of M consecutive DMRS port indices available for use by the UE, where C≤M.

In step 2020, a code parameter P representing the DMRS port group selected in step 2010 is obtained. The code parameter is calculated by combinatorial coding as follows:

Where

{p _i } - ordered set of indices pi of the selected group of DMRS ports, i=0,…,C ₁ , p _i =1,2,…,M.

In step 2030, overhead information is signaled to the UE, which includes a binary representation of the code parameter P obtained in step 2020, as well as the value of C. This signaling is preferably performed by the DCI transmitted on the PDCCH. Here, similarly to embodiments 1 and 2 described above, the code parameter message in step 2030 may direct the UE to use the selected C DMRS ports to receive C MIMO PDSCH streams, or direct the UE to use the selected C DMRS ports to transmit C MIMO- PUSCH streams.

Suppose, to illustrate the general approach disclosed above with reference to FIG. 20 that, in step 2010, the following combination of C=4 DMRS ports - {9,10,13,14} - is selected for use at the UE, where, in total, M=16 DMRS ports are available for use. Then, using Equation (7) for stage 2020, we get the code parameter:

This example is illustrated in Fig. 21.

Accordingly, by signaling code parameter P=60 and C=4 in step 2030, the UE is directed to use a non-sequential combination of DMRS ports {9,10,13,14} (see FIG. 21). In the illustrative example discussed here, the DCI bit load is 14 bits.

There are a number of known approaches that can be implemented at the UE to recover the combination of DMRS ports to be used based on the received overhead information transmitted with TRP at step 2030, primarily the code parameter obtained by combinatorial coding according to Equation (7).

The main advantage of the discussed Embodiment 3 is a much higher flexibility even compared to Embodiment 2, since Embodiment 3 allows a virtually arbitrary combination of DMRS ports to be specified. The disadvantage of this embodiment is a markedly higher bit load on the DCI.

The possible application of the above embodiments 1-3 will be described below for the case where MIMO stream reduction and corresponding adaptation of the DMRS structure is performed on the TRP, the embodiments of which have been described in detail above in subsection I of the description of the invention with reference to FIG. 10-14.

It should be noted here that in Embodiments 1-3, where the DMRS port indices are appropriately encoded for DCI signaling, it is assumed that there is a table characterizing the DMRS ports, such as that illustrated in FIG. 4a. For example, when using the DMRS structure of the present application illustrated in FIG. 7, 64 DMRS ports will be indexed in such a common table, each of which will have its own unique set of CDM group, DFT FD-OCC length 4 and DFT TD-OCC length 4.

In this context of adapting the DMRS structure, before the method according to any of the embodiments 1-3 disclosed above in this subsection of the invention is carried out, an appropriate 'decimation' of the mentioned common table must be performed so that the encoding according to these embodiments is performed in regarding actual DMRS ports.

On FIG. 22a shows a general DMRS port table pre-processing approach for the case of omitting a portion of the DMRS ports from use due to the aforementioned adaptation of the DMRS structure.

First, each of the CDM group index set D, the FD-OCC index set {k _ƒ }, and the TD-OCC index set {k ^t } corresponding to the basic, non-adapted DMRS structure used in TRP, is bit-reversed permuted (bit reverse permutation). Say, for the one illustrated in FIG. 7 of the DMRS structure according to the present application, Δ={0.1.2.3}, k _ƒ ={0.1.2.3}, k _t ={0.1.2.3} (respectively, N=64 in Fig. 22a). Briefly, in a bit-reversal permutation, each index in each of the indicated sets is represented in binary, then the order of the bits is inverted with respect to this binary representation (i.e., the first bit becomes the last, and the last - the first; the second bit becomes the penultimate, and the penultimate second; etc.), after which the inverted bit representation is converted back to a numeric representation. As a result, the corresponding transformed index sets are obtained, which are indicated in FIG. 22a as {Δ'}, , , respectively.

The corresponding exclusion is made against exactly one or more of these converted index collections. Exception for each of {Δ'}, indicated in Fig. 21a as optional, which means that it is not necessary that all of these populations be reduced - as follows from the corresponding disclosure under subsection I of the description of the invention, the reduction can be performed only in relation to a specific one of these populations, or in relation to two of them, or regarding them all. As a result of this reduction, the corresponding thinned index populations are obtained, which are indicated in FIG. 22a as {Δ'''}, , , respectively.

Finally, based on the general table of DMRS ports, an adapted, reduced table is built, which lists the indices of DMRS ports according to the thinned sets of indices {Δ'''}, ,

The general approach described above with reference to FIG. 22a is illustrated in the specific example of FIG. 22b. This example essentially corresponds to the adaptation of the DMRS structure illustrated in FIG. 8, according to the approach disclosed with reference to FIG. 12c in subsection I of the specification.

As can be seen from FIG. 22b, decimation is performed only on the TD-OCC DFT by discarding the last four indices in their transformed constellation, which corresponds to the left branch in FIG. 12s. The result is a reduced DMRS port table with no entries for indexes of DMRS ports with excluded TD-OCC DFTs.

It should be noted here that from a mathematical point of view, the bit-reversal permutation puncturing described with reference to FIG. 22a, 22b is equivalent to the embodiment of the adaptation according to the present application disclosed in subsection I of the specification with reference to FIG. 12-14.

As mentioned above, the methods according to embodiments 1-3 will in this case be carried out based on the abbreviated tables obtained according to the approach disclosed above with reference to FIGS. 22a, 22b. An illustration of this is the DMRS port group tree of FIG. 17 as corresponding to the exclusion of 48 DMRS ports out of a total of 64 available, which case corresponds to the DMRS port group tree hierarchy of FIG. 16a, 16b. It can be seen from these figures that for the code representation of the tree node of FIG. 16a, 16b requires 7 bits, while the tree node encoding of FIG. 17 requires 5 bits. That is, by applying the approach of FIG. 22a, 22b, additional bit load reduction on the DCI can be provided.

It should be emphasized that while the embodiments discussed in this subsection of the invention have used the DMRS structures disclosed with reference to FIGS. 7, 8, it should be understood that the approach proposed here for specifying DMRS ports for UEs can equally be applied to other promising DMRS structures planned for use in next generation wireless communication systems.

III. Time Domain Resource Allocation In view of the prior art described above, increasing the capacity of the new DMRS structure for next generation wireless communication systems (including 6G) causes such a structure to occupy more OFDM symbols in the time domain. areas. If 5G NR time resource allocation is used, for example, according to Type A described with reference to FIG. 5a, 5b, having a larger DMRS structure along with a control channel in each slot will result in an undesirable increase in overhead. This aspect is clearly illustrated in Fig. 23, where by way of example, as said new DMRS structure, the DMRS structure proposed in the present application, described with reference to FIG. 7 and from the right side of FIG. 23 shows that for 6G PDSCH transmission, only 4 OFDM symbols will remain in the slot.

It should be recalled here that in Type A 5G NR, it is typically necessary to allocate at least one OFDM symbol for the DMRS signal(s) in each slot. Thus, the DMRS signal will be transmitted to the UE with each slot even if there is no change in the DMRS port allocation; also in each slot at least one character is occupied by a control channel.

Therefore, in this context, improved techniques for allocating time domain resources for broadband data transmission are required to avoid these negative effects.

In accordance with the present invention, an aggregated approach to resource allocation in the time domain, both at the slot level and at the minislot level, is provided, which is detailed below with reference to FIG. 24-28.

As with 5G NR, from a macro level perspective, a 10ms frame is broken into a number of equal DL/UL periods, with the DL/UL period length being configurable at the base station. The base station may communicate the specified DL/UL period length to the UEs it serves using the aforementioned DCI (L1) signaling, MAC (L2) signaling, RRC (L3) signaling, or even some combination thereof. Each DL/UL period is divided into slots, and each slot can consist of 14 or 12 (if the extended cyclic prefix is used in the slot) OFDM symbols. In total, each DL/UL period contains OFDM symbols.

Typically, a portion of the slots of the DL/UL period is assigned to the downlink (DL) transmission (DL portion), and another portion of the slots of the DL/UL period may be allocated to the uplink (UL) transmission (UL portion). The DL part and the UL part are separated from each other by a guard interval (GI) to allow time for switching between DL and UL transmission. The guard interval is usually allocated to the slot part of the DL part or the UL part. It should be noted that the allocation of slots between the DL and UL parts is configurable at the base station - say, all The OFDM symbols of the DL/UL period can only be allocated to the DL part.

The present invention provides flexible slot or minislot aggregation such that a larger time domain resource allocation/scheduling unit is introduced than a single slot (Type A in 5G NG) or a single minislot (Type B in 5G NG). That is, it is assumed that the allocation of resources in the time domain for data transmission can be carried out in such aggregated units.

Below with reference to FIG. 24a, 24b, exemplary embodiments of aggregation for the DL portion of a DL/UL frame period will first be described.

On FIG. 24a shows the OFDM symbols constituting three slots of the DL portion of a DL/UL period along the time axis. These slots are aggregated into a single slot bundle, which constitutes a new time domain scheduling/allocation unit.

Unlike the corresponding Type A 5G NR (see FIG. 5a), adjacent OFDM symbols allocated for downlink control channel (DL-ctrl) transmission are allocated per slot block rather than per slot as in the case of Type A 5G NR. Contiguous OFDM symbols are also allocated to transmit the DMRS structure; such adjacent characters may be referred to hereinafter as a DMRS sub-block. In the DMRS structure, DMRS signals are multiplexed for the required number of MIMO streams of the transmitted PDSCH. Here, as an example, the DMRS structure of the present application described with reference to FIG. 7. Each DMRS subblock transmission event in the DL/UL period is indexed by an index

It should be emphasized that the distribution of DMRS sub-blocks shown in FIG. 24a is illustrative and other distributions may be used. Further, less and more capacious DMRS structures have been discussed above having, respectively, higher and lower density in the time domain and/or frequency domain than the structure of FIG. 7; that is, shown in FIG. 24a, the size of the DMRS sub-block of 4 OFDM symbols is also not limited. Aspects of allocation of DMRS sub-blocks will be discussed in more detail below.

The remaining OFDM symbols in the block of slots may be allocated for PDSCH transmission. Although in Fig. 24a shows the allocation of all other symbols, it should be understood that a smaller number of them can be allocated for PDSCH transmission. Further, each slot in FIG. 24a is shown containing 14 OFDM symbols; at the same time, as mentioned earlier, the slot can contain 12 OFDM symbols. These points do not impose any restrictions on the invention in question.

On FIG. 24b, along the same time axis, shows OFDM symbols constituting four minislots of the DL portion of a DL/UL period, each containing 4 OFDM symbols. These minislots are aggregated into a single block of minislots, which also constitutes a new time domain scheduling/allocation unit. Unlike the corresponding 5G NR Type B (see FIG. 5c), the downlink control channel (DL-ctrl) adjacent OFDM symbols, as in the case of FIG. 24a are allocated per block of minislots rather than per minislot as in the case of Type B 5G NR. It should be noted that in the example under consideration, adjacent OFDM symbols allocated for DL-ctrl transmission precede the minislot block without being part of it. This is not limited, and the minislot block may be arranged to include DL-ctrl OFDM symbols.

Similar to the discussion in FIG. 24a, a DMRS sub-block can also be allocated in the minislot block to transmit the DMRS structure. In this case, by way of illustration only, the DMRS sub-block is shown occupying an entire mini-slot in the mini-slot block following the DL-ctrl symbols.

The remaining OFDM symbols in the minislot block may be allocated for PDSCH transmission. Although in Fig. 24b shows the allocation of all other symbols, it should be understood that fewer can be allocated for PDSCH transmission.

Further, each minislot in FIG. 24b is shown containing 4 OFDM symbols; meanwhile, as said before, a minislot may also be 1 or 2 or 7 OFDM symbols, and the DMRS sub-block may itself have a different size, as noted with respect to FIG. 24a and not be aligned with the minislot boundaries. These points do not impose any restrictions on the invention in question.

The minislot duration is generally set on the TRP and signaled with the TRP to the UE with an overhead message. For example, an RRC message or a DCI message can be used to indicate the duration of a minislot. A combination of RRC and DCI messages may also be used, where the RRC message specifies a subset of minislot duration values: for example, a subset of {2, 7} from the total set of {2, 4, 7, 14} is specified, and the DCI message specifies one specific value from of this subset (eg, 1 bit in DCI selects either 2 or 7), which is related to the current transmission of the PDSCH signal.

On FIG. 25a, 25b, the aggregation proposed in this application is shown from a macro level perspective.

On FIG. 25a shows the case where a block of slots or minislots occupies the entire DL portion, and FIG. 25b illustrates the case where a block of slots or minislots is preceded by a slot. For the embodiment of FIG. 25b, it should be emphasized that the aforementioned OFDM symbols for DL-ctrl are included in the previous slot, while this DL-ctrl contains overhead information for scheduling a block of slots/minislots. In other words, the presence of DL-ctrl OFDM symbols in the slot block as shown in FIG. 24a is not mandatory according to the present application. The embodiment of FIG. 25b can be considered as corresponding to a combination of the known approach (Type A 5G NR) and the approach proposed in this application. It should also be understood that a block of slots/minislots may be preceded by more than one slot; in addition, it is possible that the block of slots/minislots will precede one or more slots.

It should be clarified that according to the approach of the present invention, DL-ctrl can generally be anywhere in the DL/UL period according to the control channel decoding configuration. The main requirement is that, for a particular UE, the DL-ctrl transmission occurs before the start of the slot/mini-slot block so that the UE can receive the control channel and decode the DCI, which will contain the PDSCH scheduling information (including information about the start of the slot/mini-slot block transmission). minislots and its duration).

From the illustrations in Fig. 25a, 25b clearly show the reduction in overhead - thus, reservation of OFDM symbol(s) for DL-ctrl for each slot/minislot is avoided; it is also possible to use less frequent DMRS transmissions in the DL/UL period without degrading the quality of the channel estimate.

According to the preferred embodiment

of the present invention, DMRS sub-blocks are allocated in a DL portion with a predetermined T-DMRS period. On FIG. 26a shows the periodic occurrence of DMRS sub-blocks allocated to transmit a fixed density DMRS structure in a block of slots/mini-slots. This case corresponds to the illustration in Fig. 24a.

It should be emphasized that the periodic configuration of the DMRS sub-blocks need not take place exactly within the slot/mini-slot block boundaries, as shown in FIG. 24a, 26a - say, in the embodiment of FIG. 25b, this DMRS periodicity may not be tied to slot/minislot block boundaries. In other words, this does not impose a limitation on the subject invention.

On FIG. 26b shows another preferred embodiment where the DMRS sub-blocks are allocated in the DL part also with a given T-DMRS period, but the amount of resources allocated for transmitting the DMRS structure in the first DMRS sub-block is greater than the amount of resources allocated for transmitting the structure DMRS in each of the subsequent DMRS sub-blocks. In particular, as seen from FIG. 26b, the number of OFDM symbols of the subsequent DMRS sub-block is less than the number of OFDM symbols of the first DMRS sub-block, in contrast to FIG. 26a and in the case of FIG. 26b, the first DMRS subblock may be referred to as a high density (HD) DMRS subblock, and each subsequent subblock as a low density (LD) DMRS subblock. In this case, obviously, there is an additional reduction in the service load.

For example, the DMRS structure corresponding to that illustrated in FIG. 10 or 2a may be transmitted with duplication in the HD DMRS sub-block, thus occupying 4 OFDM symbols in the time domain, and without duplication in each subsequent LD DMRS sub-block, occupying 2 OFDM symbols. This example can be considered conditionally corresponding to the illustration of FIG. 26b.

The situation illustrated in Fig. 26b may take place in the following case. When establishing a connection between a TRP and a UE, a more reliable channel estimation may be needed at the UE side, and this may require a higher DMRS density in the time and frequency domain, and therefore an HD DMRS sub-block will be allocated. Subsequently, after the connection is established, at the UE, the channel estimation will be carried out essentially at the adjustment level, based on the relevant knowledge/measurements already obtained previously. In such a case, LD DMRS subblocks will be used for DMRS transmission.

It should be emphasized that the considered periodic approach to the distribution of DMRS is preferred, but not restrictive, and DMRS sub-blocks can be allocated in a non-periodic manner, which, in particular, follows from the illustration of FIG. 25a, 25b.

As noted above, the time domain resource scheduling for data transmission is performed by the base station scheduler (TRP), and the UEs are informed of the resources reserved by the scheduler via the downlink control channel transmitted with the TRP. According to the present invention, a block of slots or minislots can be used as a unit of time domain scheduling/allocation for transmission, as opposed to a single slot or minislot according to 5G NR. The aggregation configuration according to the present application is set by the base station (TRP) and its information is signaled to the UE in the downlink control channel (DL-ctrl). According to a preferred embodiment, this information is at least partly conveyed in a DCI message carried on the PDCCH. In DCI, in particular, the indication of the beginning of the block of slots/minislots in the DL/UL period, the duration of the block of slots/minislots, the indication of the number of slots/minislots allocated in the block of slots/minislots for the PDSCH, the DMRS period, which, in general, may be different for DL part and UL part. It should be noted that other service information, which was discussed in this and previous subsections of the description of the invention, can also be signaled in DCI.

As the start of a block of slots/minislots, the DCI may indicate its start OFDM symbol within the DL/UL period; for a block of slots, its start slot can be specified as the start.

The duration of the block of slots/minislots is set on TRP depending on the decision of the scheduler, which may depend on the size of the transmitted data to the user, the need to transmit data to another user, the type of traffic transmitted, the channel state (modulation, code rate, number of MIMO channels), the transmission of other scheduled signals, etc.

The slot/minislot block T-DMRS period may be set to the TRP depending on the rate of change of the transmission channel over time. Thus, there may be a rapid channel change due to, in particular, the movement of the UE, and due to this change in TRP, a decision may be made to adjust the T-DMRS downward so that DMRS signals are sent more often to adjust accordingly.

Next, the data to be transmitted on the PDSCH is typically channel-coded. Channel coding is block coding, and as a result, the encoded data is represented as code blocks of a certain length. An option for channel coding is LDPC coding. The code blocks are then appropriately mapped to time-frequency resources for transmission on the PDSCH. Each code block is mapped onto time-frequency resources as a whole.

At the same time, if the existing procedure for determining the number of code blocks for data transmission, which is described in the TS 38.212 5G NR specification, is directly applied when mapping code blocks to time-frequency resources, then this procedure will have to be applied to the entire block of slots / mini-slots according to the present invention ( for example, the entire DL portion of a DL/UL period), and as a consequence, matching the time boundaries of an integer number of code blocks will only be guaranteed by the end of such a block of slots/minislots. That is, by directly using the existing approach, alignment of time boundaries of an integer number of code blocks with a slot or minislot boundary will generally not be guaranteed. As a consequence, processing of received data cannot begin at the receiver side until the entire aggregate block of slots/minislots has been received. In other words, on the receiver side, there is a downtime associated with the need to buffer the received code blocks while waiting for the end of the reception of the aggregated block in order to start processing them.

The flexible time domain resource aggregation approach proposed in this application eliminates this problem and improves the efficiency of code block processing pipelining at the receiver side, as illustrated in FIG. 27.

According to a preferred embodiment, the number and length of code blocks are selected according to the duration of the minislot so that, when allocating time-frequency resources for each set of code blocks in the mentioned number, the boundaries of this set in the time domain are aligned precisely with the boundaries of the minislot in the block of minislots. More specifically, the number and length of code blocks are selected according to the number of available REs in the minislot, the modulation used, and the channel coding rate. At the same time, in the considered embodiment, the use of the mentioned existing procedure for determining the number of code blocks described in the TS 38.212 5G NR specification, in fact, is carried out specifically with respect to each group of OFDM symbols that make up the minislot, separately.

On FIG. 27 shows the alignment of sets of three code blocks along minislot boundaries in a minislot block. As a consequence, data processing at the receiver may actually begin immediately upon receipt of the first minislot containing three (ie, an integer) code blocks; then, upon receipt of the second minislot, the next three code blocks will be processed; etc. Obviously, in the present embodiment, downtime associated with the processing of received data is reduced to a great extent. It should also be noted the high flexibility of the considered embodiment, since, in addition to the length and number of code blocks, the length of the minislot itself is flexibly configurable.

It should be emphasized that while the above embodiment is preferred for minislot level aggregation, it is equally applicable to slot level aggregation. In view of the foregoing, there will obviously be more latency when implemented at the slot level than in the illustrated case of minislots.

The time domain resource aggregation techniques of the present application described above with reference to FIG. 24-27 for the DL portion of a DL/UL frame period apply to its UL portion. In this case, the specificity is that the decision of the TRP scheduler is the same for the DL part and the UL part, and the time domain resource allocation information for the UL part is also signaled in the downlink control channel (DL-ctrl), as discussed higher. Thus, the start and duration of the UL block of slots/minislots is selected at the TRP and signaled to the UE by overhead on the downlink control channel; more specifically, this selection is made by the TRP scheduler and the signaling is done by the DCI on the PDCCH.

Accordingly, the uplink control channel, which in this case is the PUCCH, will have a generally different functionality compared to the downlink control channel. In particular, there is no mandatory requirement in the UL part that the control channel precede the DMRS and PUSCH; moreover, there may be no uplink control channel in the UL part at all.

So, in Fig. 25a, 25b, by way of illustration only, the control channel is shown as being at the tail of a block of slots/minislots and containing acknowledgment (ACK/NACK) information. However, in the UL part, the OFDM symbols allocated for the uplink control channel may precede the OFDM symbols allocated for DMRS and PUSCH. It should be emphasized that, in general, the block of slots/minislots according to the present invention can be essentially anywhere in the UL part.

Since the PUCCH is not directly related to resource scheduling, it is possible that the PUCCH transmission will not be related to the block(s) of slots/minislots (and slots or minislots in general), for example, be used to transmit a Scheduling Request or information channel state (CSI), or when the PUCCH transmission will refer to previous slots, minislots, or block(s) of slots/minislots.

Next, with reference to FIG. 28a, 28b describe an embodiment of a time domain resource allocation method 2800 according to the present invention. By way of illustration, method 2800 is performed at a base station (eg, TRP 602 of FIG. 6) that supports simultaneous transmission of multiple spatial MIMO PDSCH streams.

Below with reference to FIG. 28a discusses steps 2810-2860 of method 2800 performed on the DL portion of a DL/UL frame period.

At 2810, a predetermined number of contiguous OFDM symbols are allocated for transmission of a downlink control channel, which is preferably a PDCCH.

At step 2820, a DL block of slots is generated containing an integer number of contiguous slots, each slot including a predetermined number of OFDM symbols. Here, the PDCCH to be carried in the OFDM symbols of the DL part assigned to it refers to the entire block of time slots. According to the above disclosure, a time slot may be a slot, which may contain 12 or 14 OFDM symbols, or a mini-slot, which may contain 1, 2, 4, or 7 OFDM symbols.

At 2830, at least one DL DMRS subblock is allocated to transmit DMRS signals for the required number of MIMO PDSCH streams.

At 2840, OFDM symbols are allocated in the DL slot block for PDSCH transmission.

The possible relative positions of the OFDM symbols for the PDCCH, DL DMRS subblock(s) and block(s) of slots/minislots in the DL part are described above, including with reference to FIG. 24-26.

At 2850, a DL block of slots is allocated for the scheduled DL transmission.

As repeatedly mentioned earlier, overhead information must be carried in the PDCCH, more specifically in the DCI message. In addition to the service information discussed above, in this case, the service information will include an indication of the beginning of the DL block of time intervals and the duration of the DL block of time intervals. If, according to the preferred embodiment (see FIG. 26), the DMRS subblocks are organized with a T-DMRS period, then the T-DMRS is also included in the overhead.

In step 2860, for the data to be transmitted in the OFDM symbols allocated to the PDSCH in the DL block of slots, the size and number of code blocks to perform channel coding (preferably LDPC) are determined, and code blocks representing the encoded data are obtained. The number and length of code blocks are selected so that, when allocating time-frequency resources for each set of code blocks in the mentioned number, the boundaries of this set in the time domain are aligned with the boundaries of the time interval in the block of time intervals (see Fig. 27).

Below with reference to FIG. 28b discusses steps 2870-2875 of method 2800 performed on the UL portion of a DL/UL period.

At step 2870, a UL block of slots is formed containing an integer number of contiguous slots.

At 2871, at least one UL DMRS subblock is allocated to transmit a DMRS structure in which the DMRS signals are multiplexed for the desired number of MIMO PUSCH streams.

At 2872, OFDM symbols are allocated in the UL slot block for PUSCH transmission.

At 2873, a predetermined number of contiguous OFDM symbols are allocated for PUCCH transmission.

The possible relative positions of OFDM symbols for PUCCH, UL DMRS sub-block(s) and block(s) of slots/mini-slots in the UL part are described above.

At 2874, a UL block of slots is allocated for UL transmission.

In step 2875, similarly to step 2860, the data to be transmitted in the OFDM symbols allocated to the PUSCH in the UL slot block is channel-coded with the number and length of code blocks appropriately selected.

It should be emphasized that although in the embodiments discussed in this subsection of the description of the invention, the DMRS structure disclosed with reference to FIG. 7 and other DMRS structures proposed herein, it should be understood that the time domain resource allocation approach proposed here may equally be applicable to other promising DMRS structures planned for use in next generation wireless communication systems.

It should also be understood that the illustrated exemplary embodiments are merely preferred and not the only possible embodiments of the present invention. More precisely, the scope of the present invention is defined by the following claims and their equivalents.

Claims (44)

1. A time domain resource allocation method performed at a base station (TRP) in a wireless communication system, wherein the TRP is configured to support simultaneous transmission of a plurality of spatial MIMO streams for data transmission, with each of the plurality of MIMO streams associated with a different other demodulation reference signal (DMRS signal), wherein the method comprises the steps of: in the downlink-uplink period (DL/UL-period) part of the frame corresponding to the DL-transmission (DL-part), allocate a predetermined number of adjacent OFDM symbols for downlink control channel transmission, forming a DL block of time intervals containing an integer number of adjacent time intervals, each time interval including a predetermined number of OFDM symbols, wherein the downlink control channel refers to the entire DL block of time intervals, allocating at least one DL subblock of OFDM symbols for transmitting DMRS signals (DL DMRS subblock) for the required number of downlink physical shared data channel (PDSCH) MIMO streams, and allocate in the DL-block of time intervals OFDM symbols for PDSCH transmission; And allocate a DL block of time slots for DL transmission, wherein the downlink control channel carries overhead information including at least an indication of the beginning of the DL block of time slots and a duration of the DL block of time intervals. 2. The method of claim 1, wherein the timeslot is a slot containing 12 or 14 OFDM symbols. 3. The method of claim 2, wherein the OFDM symbols allocated for downlink control channel transmission are initial OFDM symbols of the first slot of the DL block of slots. 4. The method of claim 3, wherein the DL block of slots includes said at least one DL DMRS subblock, wherein the first DL DMRS subblock of the at least one DL DMRS subblock is adjacent to the OFDM symbols allocated for transmission of the downlink control channel. 5. The method of claim 1, wherein said at least one DL DMRS subblock is a collection of DL DMRS subblocks separated from each other by a DL period of an adjustable number of OFDM symbols, wherein the DL period is adjustable on a TRP, wherein the overhead information further includes a DL period. 6. The method according to claim 5, in which the amount of resources allocated for the transmission of DMRS signals in the first DL DMRS sub-block of the mentioned set is greater than the amount of resources allocated for the transmission of DMRS signals in each of the subsequent DL DMRS sub-blocks of the mentioned set, so that the number of OFDM symbols of this subsequent DL DMRS subblock is less than the number of OFDM symbols of the first DL DMRS subblock. 7. The method of claim 1, wherein the timeslot is a mini-slot, wherein the mini-slot contains 1, 2, 4, or 7 OFDM symbols. 8. The method of claim 7, wherein the boundaries of at least a first DL DMRS sub-block of said at least one DL DMRS sub-block in the time domain are aligned with mini-slot boundaries. 9. The method of claim 1, further comprising performing channel coding on data to be transmitted in OFDM symbols allocated to the PDSCH in the DL slot block, and obtaining code blocks representing encoded data, wherein the number and length of code blocks are selected according to the duration of the time interval so that, when allocating time-frequency resources for each set of code blocks in the mentioned number, the boundaries of this set in the time domain are aligned with the boundaries of the time interval in the DL block of time intervals. 10. The method of claim 9, wherein the channel coding is LDPC coding, wherein the number and length of code blocks are selected according to the number of available resource elements (RE) in the time slot, the modulation used, and the coding rate. 11. The method of claim 1, wherein the downlink control channel is a physical downlink control channel (PDCCH) and the overhead information is included in the downlink control information (DCI) carried on the PDCCH, wherein the indication of the start of the DL slot block is the indication start OFDM symbol of the DL slot block. 12. The method of claim 2, wherein the downlink control channel is the PDCCH and the overhead information is included in the DCI carried on the PDCCH, wherein the indication of the start of the DL block of slots is the indication of the start slot of the DL block of slots. 13. The method of claim 1, wherein the DL/UL period further comprises a portion corresponding to a UL transmission (UL portion) after the DL portion, the method further comprising: in UL part forming a UL block of time slots containing an integer number of adjacent time slots, allocating at least one UL subblock of OFDM symbols for transmitting DMRS signals (UL DMRS subblock) for transmitting DMRS signals for a required number of MIMO physical uplink shared data channel (PUSCH) streams, and allocate, in the UL block of time slots, OFDM symbols for PUSCH transmission; And allocate a UL block of slots for UL transmission, wherein the overhead information further includes an indication of the beginning of the UL block of slots and a duration of the UL block of slots. 14. The method of claim 13, further comprising allocating a predetermined number of contiguous OFDM symbols in the UL portion to transmit a physical uplink control channel (PUCCH). 15. The method of claim 14, wherein the OFDM symbols allocated for PUCCH transmission follow said at least one UL DMRS sub-block and OFDM symbols allocated for PUSCH transmission. 16. The method of claim 14, wherein said at least one UL DMRS subblock and the OFDM symbols allocated for PUSCH transmission follow the OFDM symbols allocated for PUCCH. 17. The method of claim 15, wherein the slot in the UL portion is a slot containing 12 or 14 OFDM symbols, where the OFDM symbols allocated for PUCCH transmission are the final OFDM symbols of the last slot of the UL block of slots. 18. The method of claim 17, wherein the UL block of slots includes said at least one UL DMRS subblock. 19. The method of claim 18, wherein the UL block of slots contains all the slots of the UL part. 20. The method of claim 13, wherein said at least one UL DMRS subblock is a collection of UL DMRS subblocks separated from each other by a UL period of a controlled number of OFDM symbols, wherein the overhead further includes UL- period. 21. The method of claim 20, wherein the amount of resources allocated for transmission of DMRS signals in the first UL DMRS subblock of said set is greater than the amount of resources allocated for transmission of DMRS signals in each of the subsequent UL DMRS subblocks of said set, so that the number of OFDM symbols of this subsequent UL DMRS sub-block is less than the number of OFDM symbols of the first UL DMRS sub-block. 22. The method of claim 13, wherein the time slot in the UL portion is a mini-slot, wherein the mini-slot contains 1, 2, 4, or 7 OFDM symbols. 23. The method of claim 22, wherein the boundaries of at least a first UL DMRS sub-block of said at least one UL DMRS sub-block in the time domain are aligned with mini-slot boundaries. 24. The method of claim 13, further comprising performing, with respect to data to be transmitted in OFDM symbols allocated for PUSCH in the UL slot block, channel coding, and obtaining code blocks representing encoded data when in this case, the number and length of code blocks are selected according to the duration of the time interval so that, when allocating time-frequency resources for each set of code blocks in the mentioned number, the boundaries of this set in the time domain are aligned with the boundaries of the time interval in the UL block of time intervals. 25. The method of claim 24, wherein the channel coding is LDPC coding, wherein the number and length of code blocks are selected according to the number of available REs in the time slot, the modulation used, and the coding rate. 26. The method of claim. 1, wherein the frame duration is 10 ms, the frame contains a plurality of DL/UL periods, and the duration of the DL/UL period is set by the base station. 27. A base station (TRP) in a wireless communication system, comprising at least: transceiver devices; data processing devices; And data storage devices in which computer-executable codes are stored, which, when executed by data processing devices, ensure that the base station performs the method according to any one of the preceding claims. 28. A computer-readable storage medium that stores computer-executable codes that, when executed by at least one base station data processor (TRP) in a wireless communication system, cause the TRP to perform the method according to any one of paragraphs. 1-26.