Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
  • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
  • H04B7/0413—MIMO systems
  • H04B7/0452—Multi-user MIMO systems

Definitions

• the present invention relates to a wireless communication system. More specifically, the present invention relates to a reference signal antenna port allocation method and apparatus for the transmission diversity scheme in a wireless communication system.
• E-UMTSC Evolved Universal Mobile Telecommunications System
• UMTS Universal Mobile Telecommunications System
• LTE Long Term Evolution
• an E-UMTS is located at an end of a user equipment (UE), a base station (eNode B; eNB), and a network (E-UT AN) and connected to an external network (Access gateway). Gateway; AG).
• the base station may transmit multiple data streams simultaneously for broadcast service, multicast service and / or unicast service.
• the cell is set to one of bandwidths such as 1.44, 3, 5, 10, 15, and 20Mhz to provide downlink or uplink transmission services to multiple terminals. Different cells may be set to provide different bandwidths.
• the base station controls data transmission and reception for a plurality of terminals.
• For downlink (DL) data the base station transmits downlink scheduling information to inform the corresponding terminal of time / frequency domain, encoding, data size, and HARQ Hybrid Automatic Repeat and reQuest (related information) related data.
• the uplink (UL) data In addition, the uplink (UL) data .
• the base station transmits uplink scheduling information to the corresponding terminal and informs the time / frequency domain, encoding, data size, HARQ related information, etc.
• the core network may consist of an AG and a network node for user registration of the terminal.
• the AG manages the mobility of the UE in units of a tracking area (TA) composed of a plurality of cells.
• a method for transmitting a downlink control channel to a terminal by a base station includes: setting resource element subsets comprising a plurality of resource elements; Allocating transmission resources for the downlink control channel in units of the resource element subset; Alternating allocation of two antenna ports for DM-RS (Demodulat ion-Reference Signal) to the plurality of resource elements; And transmitting the downlink control channel to the terminal through the allocated transmission resource by using the DM-RSs of the allocated antenna ports. Characterized in that it comprises a step.
• a base station apparatus sets resource element subsets composed of a plurality of resource elements and allocates transmission resources for a downlink control channel in units of the resource element subsets.
• a processor for alternately allocating two antenna ports for a demodul at ion-reference signal (DM-RS) to the plurality of resource elements;
• wireless communication modules for transmitting the downlink control channel to the terminal through the allocated transmission resource by using the DM-RSs of the allocated antenna ports.
• DM-RS demodul at ion-reference signal
• the indexes of the antenna ports of the two DM-RSs are based on the number of available resource elements or the length of the cyclic prefix of the subframe in which the downlink control channel is transmitted. It is characterized in that determined based on.
• the antenna ports of the two DM-RSs are antenna ports of the DM-RS that are not multiplexed on the same resource element. It features.
• the antenna ports of the two DM-RSs are antenna ports of the DM-RS multiplexed on the same resource element.
• the indexes of the antenna ports of the two DM-RSs are 7 and 9, respectively.
• the indexes of the antenna ports of the two DM-RSs are 7 and 8.
• a reference signal for a downlink control channel particularly an antenna port of a DM-RS.
• FIG. 1 is a diagram schematically illustrating an E-UMTS network structure as an example of a wireless communication system.
• FIG. 2 is a diagram illustrating a control plane and a user plane structure of a radio interface protocol between a UE and an E-UTRAN based on the 3GPP radio access network standard.
• FIG. 3 is a diagram for explaining physical channels used in a 3GPP system and a general signal transmission method using the same.
• FIG. 4 is a configuration diagram of a multi-antenna communication system.
• FIG. 5 is a diagram illustrating a structure of a downlink radio frame used in an LTE system.
• FIG. 6 is a diagram illustrating a resource unit used to configure a downlink control channel in an LTE system.
• FIG. 7 is a diagram illustrating a structure of an uplink subframe used in an LTE system.
• FIG. 8 is a diagram illustrating a multiple node system in a next generation communication system.
• FIG. 9 is a diagram illustrating a PDSCH scheduled by an E-PDCCH and an E-PDCCH.
• FIG. 10 shows an example of a PDCCH region and an E-PDCCH region in one subframe.
• 11 and 12 illustrate the structure of a reference signal in an LTE system supporting downlink transmission using four antennas.
• FIG. 13 and 14 illustrate examples of DM-RS allocation in a subframe to which a general CP defined in the 3GPP standard document is currently applied.
• FIG. 15 shows an example of DM-RS allocation in a subframe to which an extended CP defined in the current 3GPP standard document is applied.
• FIG 16 illustrates resource elements for E-PDCCH transmission according to an embodiment of the present invention. An example of assigning an antenna port is shown.
• FIG. 17 illustrates a block diagram of a communication device according to an embodiment of the present invention.
• the present specification uses an LTE system and an LTE-A system to describe an embodiment of the present invention.
• FIG. 2 is a diagram illustrating a radio between a UE and an E-UTRAN based on a 3GPP radio access network standard.
• Control plane is terminal (User
• the user plane is the data generated by the application tradeoff,
• the physical layer which is the first layer, is overlaid using a physical channel.
• the physical layer is different from the upper medium access control layer.
• the physical channel is time and
• the physical channel is in the downlink
• SC-FDMA Single Carrier Frequency Division Multiple Access
• the Medium Access Control (MAC) layer of the second layer It provides a service to a radio link control (RLC) layer, which is a higher layer, through a logical channel.
• RLC radio link control
• the RLC layer of the second layer supports reliable data transmission.
• the functions of the RIX layer may be implemented as functional blocks inside the MAC. Almost 12 layers of Packet Data Convergence Protocol (PDCP) negotiations perform header compression, which reduces unnecessary control information for efficient transmission of IP packets such as IPv4 or IPv6 over narrow bandwidth interfaces.
• PDCP Packet Data Convergence Protocol
• the radio resource control (RRC) layer located at the bottom of the third layer is defined only in the control plane.
• the RRC layer is responsible for the control of logical channels, transport channels, and physical channels in connection with configuration, re-conf igurat ion, and release of radio bearers (RBs).
• RB means a service provided by the second layer for data transmission between the terminal and the network.
• the RRC layers of the UE and the network exchange RC messages with each other.
• RRC connected RRC Connected
• the non-access stratum (NAS) layer above the RRC layer performs functions such as session management and mobility management.
• One cell constituting the base station (e NB) is set to one of bandwidths such as 1.4, 3, 5, 10, 15, and 20Mhz to provide downlink or uplink transmission services to various terminals. Different cells may be configured to provide different bandwidths.
• a downlink transport channel for transmitting data from a network to a terminal includes a broadcast channel (BCH) for transmitting system information, a paging channel (PCH) for transmitting a paging message, and a downlink shared channel (SCH) for transmitting user traffic or a control message. ). Traffic or control messages of a downlink multicast or broadcast service may be transmitted through a downlink SCH or may be transmitted through a separate downlink multicast channel (MCH). Meanwhile, the uplink transmission channel for transmitting data from the terminal to the network includes a random access channel (RAC) for transmitting an initial control message and an uplink shared channel (SCH) for transmitting user traffic or a control message.
• BCH broadcast channel
• PCH paging channel
• SCH downlink shared channel
• Logical channels mapped to a transport channel include a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), an MCCHC multicast control channel (MTCH), a multicast traffic channel (MTCH), and the like.
• BCCH broadcast control channel
• PCCH paging control channel
• CCCH common control channel
• MTCH MCCHC multicast control channel
• MTCH multicast traffic channel
• FIG. 3 is a diagram for describing physical channels used in a 3GPP system and a general signal transmission method using the same.
• the terminal performs an initial cell search operation such as synchronizing with the base station (S301).
• the UE receives a Primary Synchronization Channel (P-SCH) and a Secondary Synchronization Channel (S—SCH) from the base station, synchronizes with the base station, and obtains information such as a Sal ID. have.
• the terminal may receive a physical broadcast channel from the base station to obtain broadcast information in the cell.
• the terminal may receive a downlink reference signal (DL RS) in the initial cell search step to confirm the downlink channel state.
• DL RS downlink reference signal
• the UE which has completed the initial cell search receives a physical downlink control channel (PDCCH) and a physical downlink control channel (PDSCH) according to the information carried on the PDCCH for a more specific system.
• Information can be obtained (S302).
• the terminal may perform a random access procedure (RACH) for the base station (steps S303 to S306).
• RACH random access procedure
• the UE may transmit a specific sequence to the preamble through a physical random access channel (PRACH) (S303 and S305), and may receive a voice response message for the preamble through the PDCCH and the Daesung PDSCH ( S304 and S306).
• PRACH physical random access channel
• a contention resolution procedure may be additionally performed.
• the UE After performing the above procedure, the UE performs a PDCCH / PDSCH reception (S307) and a physical uplink shared channel (PUSCH) / physical uplink control channel as a general uplink / downlink signal transmission procedure. Physical Uplink Control Channel; PUCCH) may be performed (S308).
• the terminal receives downlink control information (DCI) through the PDCCH.
• DCI downlink control information
• the DCI includes control information such as resource allocation information for the terminal, and the format is different depending on the purpose of use.
• the control information transmitted by the terminal to the base station through the uplink or received by the terminal from the base station is a downlink / uplink ACK / NACK signal, CQK Channel Quality Indicator (CQK), ⁇ (Precoding Matrix Index), RI ( Rank Indicator).
• CQK CQK Channel Quality Indicator
• ⁇ Precoding Matrix Index
• RI Rank Indicator
• the terminal may transmit the above-described control information such as CQI / PMI / RI through the PUSCH and / or PUCCH.
• MIMO Multiple-Input Multiple-Output
• MIM0 may be referred to as a “multi-antenna”.
• multi-antenna technique it does not rely on a single antenna path to receive one entire message. Instead, in multi-antenna technology, data fragments received from multiple antennas are gathered and merged to complete the data. Using multi-antenna technology, it is possible to improve the data transmission rate within a cell area of a specified size or to increase system coverage while guaranteeing a specific data transmission rate. In addition, this technique can be widely used in mobile communication terminals and repeaters. According to the multiple antenna technology, it is possible to overcome the transmission limit in the mobile communication according to the prior art, which used a single antenna.
• FIG. 4 is a configuration diagram of a multiple antenna (MIM0) communication system according to the present invention.
• Transmitter had a transmitting antenna is installed dog ⁇ ⁇
• the receiving end has a receiving antenna installed dog N R.
• N R the theoretical channel transmission capacity is increased than when the plurality of antennas are used at either the transmitting end or the receiving end.
• Channel transmission The increase in capacity is proportional to the number of antennas. Therefore, the transmission rate is improved and the frequency efficiency is improved.
• the maximum transmission rate when using one antenna is R ⁇
• the transmission rate when using multiple antennas is theoretically the maximum transmission as shown in Equation 1 below.
• the rate R ⁇ may be increased by multiplying the rate increase rate Ri. Where Ri is the lesser of N and ⁇ ⁇ R.
• the current trends of multi-antenna researches include the study of information theory aspects related to the calculation of multi-antenna communication capacity in various channel and multi-access environments, the measurement of radio channels and model derivation of multi-antenna systems, and the improvement of transmission reliability.
• Active research is being conducted from various viewpoints, such as research on space-time signal processing technology for improving data rate.
• Equation 2 Equation 2
• each transmission information To do different transmit power if each transmission power is ⁇ ' ⁇ ' '" ' " ⁇ , the transmission information of which transmission power is adjusted is represented by a vector as in Equation 3 below.
• ⁇ can be expressed as Equation 5 below using a vector. here It means the weight between the first transmission antenna and the first information. W is called a weight matrix or a precoding matrix.
• the physical meaning of the rank of a channel matrix is : It is the maximum number of other information that can be sent. Therefore, the rank of a channel matrix is defined as the minimum of the number of independent rows or columns, so the rank of the matrix can be greater than the number of rows or columns. There will be no.
• the tank (rank (H)) of the channel matrix H is limited as shown in Equation 6 below.
• each of the different information transmitted using the multi-antenna technique will be defined as a 'stream' or simply 'stream'.
• a 'stream' may be referred to as a 'layer ' .
• the number of transport streams can then, of course, be no greater than the rank of the channel, which is the maximum number that can send different information. Therefore, the channel matrix H can be expressed as Equation 7 below.
• FIG. 5 is a diagram illustrating a control channel included in a control region of one subframe in a downlink radio frame.
• the number of OFDM symbols included in one subframe may vary depending on the length of the cyclic prefix (CP) or whether it is a normal CP or an extended CP and the spacing of subcarriers. And subcarrier spacing is 15 kHz.
• a subframe consists of 14 0FDM symbols. According to the subframe configuration, the first 1 to 3 OFDM symbols are used as the control region and the remaining 13-11 OFDM symbols are used as the data region.
• R1 to R4 represent reference signals (RSs) or pilot signals for antennas 0 to 3.
• the RS is fixed in a constant pattern in a subframe regardless of the control region and the data region.
• the control channel is allocated to a resource to which no RS is allocated in the control region, and the traffic channel is also allocated to a resource to which no RS is allocated in the data region.
• Control channels allocated to the control region include a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid-ARQ Indicator CHannel (PHICH), and a Physical Downlink Control CHannel (PDCCH).
• PCFICH Physical Control Format Indicator CHannel
• PHICH Physical Hybrid-ARQ Indicator CHannel
• PDCCH Physical Downlink Control CHannel
• the PCFICH is a physical control format indicator channel and informs the UE of the number of OFDM symbols used for the PDCCH in every subframe.
• the PCFICH is located in the first OFDM symbol and is set in preference to the PHICH and PDCCH.
• the PCFICH is composed of four Resource Element Groups (REGs), and each REG is distributed in the control region based on the cell ID Cell IDentity.
• REG is composed of four resource elements (REs).
• RE represents a minimum physical resource defined by one subcarrier and one OFDM symbol.
• the PCFICH value indicates a value of 1 to 3 or 2 to 4 depending on the bandwidth and is modulated by Quadrature Phase Shift Keying (QPSK).
• QPSK Quadrature Phase Shift Keying
• the PHICH is a physical hybrid automatic repeat and request (HARQ) indicator channel and is used to carry HARQ ACK / NACK for uplink transmission. That is, PHICH represents a channel through which DL ACK / NACK information for UL HARQ is transmitted. PHICH is 1
• HARQ physical hybrid automatic repeat and request
• It is composed of REGs and is cell-specifically scrambled.
• ACK / NACK is indicated by 1 bit and modulated by binary phase shift keying (BPSK).
• SF Spreading Factor
• a plurality of PHICHs mapped to the same resource constitutes a PHICH group.
• the number of PHICH to the PHICH groups to be multiplexed is, it is determined according to the number of spreading codes.
• the PHICH (group) is repeated three times to obtain diversity gain in the frequency domain and / or the time domain.
• the PDCCH is a physical downlink control channel for the first n OFDM symbols of a subframe. Is assigned. Here, n is indicated by the PCFICH as an integer of 1 or more.
• the PDCCH consists of one or more CCEs.
• the PDCCH informs each UE or UE group of information related to resource allocation of a transmission channel (PCH) and a DL ink-shared channel (DL-SCH), an uplink scheduling grant, and HARQ information.
• PCH transmission channel
• DL-SCH Down 1 ink-shared channel
• the base station and the terminal generally transmit and receive data through the PDSCH except for specific control information or specific service data.
• Data of PDSCH is transmitted to which UE (one or a plurality of UEs), and information on how the UEs should receive and decode PDSCH data is included in the PDCCH and transmitted.
• a particular PDCCH is masked with a cyclic redundancy check (CRC) with a Radio Network Temporary Identity (RTI) of "A", and a radio resource (eg, frequency location) of "B" and "C”.
• CRC cyclic redundancy check
• RTI Radio Network Temporary Identity
• the terminal in the sal monitors the PDCCH using the R TI information it has, and if there is at least one terminal having an "A" RNTI, the terminals receive the PDCCH, and the information of the received PDCCH Receive the PDSCH indicated by " B "
• FIG. 6 shows a resource unit used to configure a downlink control channel in an LTE system.
• FIG. 6 shows a case where the number of transmit antennas of the base station is 1 or 2
• FIG. 6 (b) shows a case where the number of transmit antennas of the base station is four. Only the RS (Reference Signal) pattern is different according to the number of transmitting antennas, and the method of setting a resource unit associated with the control channel is the same.
• RS Reference Signal
• the basic resource unit of the downlink control channel is a resource element group (REG).
• the REG consists of four neighboring resource elements (REs) with the exception of the RS. REG is shown in bold in the figures.
• PCFICH and PHICH include 4 REGs and 3 REGs, respectively.
• the PDCCH is composed of CCE (Control Channel Elements) units, and one CCE includes nine REGs.
• the UE is configured to check M (L) ( ⁇ L) CCEs arranged in consecutive or specific rules. There may be a plurality of L values to be considered by the UE for PDCCH reception.
• the CCE sets that the UE needs to check for PDCCH reception are called a search space. For example, the LTE system defines a search area as shown in Table 1.
• CCE aggregation level L represents the number of CCEs constituting the PDCCH
• 3 ⁇ 4 (1) represents the search region of the CCE aggregation level L
• 3 ⁇ 41 () is a candidate to be monitored in the search region of the aggregation level L Number of PDCCHs.
• the search area may be divided into a UE-specific search space that is accessible only to a specific terminal and a co- on search space that allows access to all terminals in a cell. Can be.
• the terminal monitors a common search region with CCE aggregation levels of 4 and 8, and monitors a terminal-specific search region with CCE aggregation levels of 1, 2, 4, and 8.
• the common search area and the terminal specific search area may overlap . have/
• the position of the first (with the smallest index) CCE in the PDCCH search region given to any UE for each CCE aggregation level value is changed every subframe according to the UE. This is called hashing of the PDCCH search region.
• the CCE may be distributed in a system band. More specifically, a plurality of logically continuous CCEs may be input to an interleaver, and the interleaver performs a function of mixing the input CCEs in REG units. Thus, one CCE Frequency / time resources are physically transmitted in the entire frequency / time domain in the control region of the subframe. As a result, the control channel is configured in units of CCE, but interleaving is performed in units of REGs, thereby maximizing frequency diversity and interference randomization gain.
• FIG. 7 is a diagram illustrating a structure of an uplink subframe used in an LTE system.
• an uplink subframe may be divided into a region to which a Physical Uplink Control CHannel (PUCCH) carrying control information is allocated and a region to which a Physical Uplink Shared CHannel (PUSCH) carrying user data is allocated.
• the middle part of the subframe is allocated to the PUSCH, and both parts of the data area are allocated to the PUCCH in the frequency domain.
• Control information transmitted on the PUCCH includes an ACK / NAC used for HARQ, a CQKChannel Quality Indicator indicating a downlink channel state, a RKRank Indicator for MIM0), and a SR (Scheduling Request), which is an uplink resource allocation request.
• the PUCCH for one UE uses one resource block occupying a different frequency in each slot in a subframe. That is, two resource blocks allocated to the PUCCH are frequency hopping at the slot boundary.
• the current wireless communication environment is rapidly increasing the data demand for the cellular network due to the emergence and spread of various devices that require M2M (Machine ⁇ to Machine) communication and high data transmission.
• M2M Machine ⁇ to Machine
• communication technologies are evolving into multi-antenna technology, multi-base station cooperation technology, etc. to increase data capacity within a limited frequency, such as carrier aggregation technology to efficiently use more frequency bands.
• Communication environment evolves toward increasing density of nodes that can be accessed around users. Systems with such high density nodes can exhibit higher system performance by cooperation between furnaces.
• BS Base Station
• ABS Advanced BS
• NB Node-B
• eNB eNode-B
• AP Access Point
• FIG. 8 is a diagram illustrating a multi-node system in a next generation communication system. .
• the system is a distributed multi-node forming one cell. It can be seen as a distributed multi-node system (D ⁇ S).
• D ⁇ S distributed multi-node system
• individual nodes may be given a separate Node ID, or may operate like some antennas in a cell without a separate Node ID.
• IDs cell identifiers
• this can be viewed as a multi-cell system. If the multiple cells are configured in an overlapped form according to coverage, this is called a multi-tier network.
• Node—B eNode-B, PeNB), HeNB, Remote Radio Head (RRH), relay, and distributed antenna may be nodes, and at least one antenna is installed in one node. Nodes are also called transmission points.
• a node generally refers to an antenna group separated by a predetermined interval or more, but in the present invention, the node may be applied even if the node is defined as an arbitrary antenna group regardless of the interval.
• the introduction of the multi-node system and the relay node described above it is possible to apply various communication techniques to improve channel quality, but to apply the aforementioned MIM0 technique and inter-cell cooperative communication technique to a multi-node environment.
• the introduction of a new control channel is required. Due to this necessity, the newly introduced control channel is E-PDCCH (Enhanced-PDCCH), and it is decided that the control channel is allocated to a data region (hereinafter, referred to as a PDSCH region) instead of an existing control region (hereinafter, referred to as a PDSCH region).
• E-PDCCH Enhanced-PDCCH
• the E-PDCCH is not provided to the legacy legacy terminal, and can be received only by the LTE-A terminal.
• the E-PDCCH is transmitted and received based on the DM-RS, which is a UE-specific reference signal, rather than the CRS, which is an existing cell specific reference signal.
• a radio frame consists of two half frames, each half frame comprising four general subframes including two slots, a downlink pilot time slot (DwPTS), a guard period (GP) and It consists of a special subframe including an UpPTSOJplink Pilot Time Slot.
• DwPTS downlink pilot time slot
• GP guard period
• the DwPTS is used for initial cell search, synchronization, or channel estimation at the terminal.
• UpPTS is used for channel estimation at the base station and synchronization of uplink transmission of the terminal. That is, DwPTS is used for downlink transmission and UpPTS is used for uplink transmission.
• UpPTS is used for PRACH preamble or SRS transmission.
• the guard interval is a period for removing interference caused in the uplink due to the multipath delay of the downlink signal between the uplink and the downlink.
• UpPTS is indicated and the remaining area is set as a protection interval.
• FIG. 10 is a diagram illustrating a PDSCH scheduled by an E-PDCCH and an E-PDCCH.
• an E-PDCCH generally indicates a PDSCH region for transmitting data.
• the UE may perform a blind decoding process on the search region for the E-PDCCH in order to detect the presence or absence of its own E-PDCCH.
• the E-PDCCH performs the same scheduling operation as that of the existing PDCCH (ie, PDSCH and PUSCH control), but when the number of UEs connected to a node such as an RRH increases, more E-PDCCHs are added in the PDSCH region. There may be a drawback that the complexity may increase due to an increase in the number of blind decodings allocated and performed by the UE.
• a single PRB-pair control channel signal includes a large amount of resource elements
• the available resource elements included in the single PRB pair are divided into one or more resource element subsets, and the resource element subsets. It is desirable to transmit the E-PDCCH by using appropriately.
• the resource element subset may be referred to as an E-CCE which is a transmission unit of the E-PDCCH, and one E-PDCCH may combine and transmit one or a plurality of E-CCEs according to an aggregation level.
• the resource element subset may be referred to as another unit constituting the E-CCE, E-REG.
• the E—CCE may be defined as a set of E-REGs located in a plurality of PRB-pairs.
• one E-PDCCH may combine and transmit one or a plurality of E-CCEs according to an aggregation level.
• a reference signal that is known to both the transmitting side and the receiving side together with data is transmitted from the transmitting side to the receiving side for channel measurement.
• a reference signal informs the modulation technique as well as the channel measurement to play a demodulation process.
• a reference signal is divided into a dedicated RS (DRS) for a base station and a specific UE, that is, a UE-specific reference signal and a common reference signal (co'on RS), which is a cell-specific reference signal for all UEs in a cell.
• the cell-specific reference signal includes a reference signal for measuring the CQI / PMI / RI in the terminal to report to the base station, this is referred to as Channel State Informat ion-RS (CSI-RS).
• CSI-RS Channel State Informat ion-RS
• FIG. 11 and 12 illustrate LTE supporting downlink transmission using four antennas. It is a figure which shows the structure of the reference signal in a system. In particular, FIG. 11 illustrates a case of normal cyclic prefix, and FIG. 12 illustrates a case of extended cyclic prefix.
• CRS Co (on Reference Signal) which is a cell-specific reference signal transmitted for channel measurement and data demodulation for each of antenna ports 0 to 3.
• the CRS which is the cell specific reference signal, may be transmitted to the terminal not only in the data information region but also in the entire control information region.
• 'D' described in the grid refers to a downlink DM-RS (DM-RS) which is a UE-specific RS, and the DM-RS supports single antenna port transmission through a data region, that is, a PDSCH.
• the terminal is signaled through the upper layer whether the DM-RS which is the terminal specific RS is present.
• 11 and 12 illustrate DM-RSs for antenna port 5, and 3GPP standard document 36.211 also defines DM-RSs for antenna ports 7 to 14, that is, 8 antenna ports in total.
• FIG. 13 and 14 illustrate examples of DM-RS allocation in a subframe to which a general CP defined in the 3GPP standard document is currently applied.
• FIG. 13 shows the case of antenna port 7 and antenna port 8
• FIG. 14 shows the case of antenna port 9 and antenna port 10.
• FIG. 13 shows the case of antenna port 7 and antenna port 8
• FIG. 14 shows the case of antenna port 9 and antenna port 10.
• DM-RS group 1 a DM-RS corresponding to an antenna port ⁇ 7, 8 ⁇ is mapped to the same resource element by a code division multiplexing scheme using an antenna port sequence.
• DM-RS group 2 DM-RSs corresponding to antenna ports ⁇ 9, 10 ⁇ are similarly mapped to the same resource elements by code division multiplexing using antenna-specific sequences.
• FIG. 15 shows an example of DM-RS allocation in a subframe to which an extended CP defined in the current 3GPP standard document is applied.
• the present invention proposes a method of determining an antenna port of a DM-RS for an E-PDCCH.
• FIG. 13 and FIG. 14 which is a case of a general CP
• FIG. 15 which is a case of an extended CP
• a large number of resource elements can be used for downlink transmission in a general downlink subframe.
• the DM-RS overhead can be kept relatively low, while the number of resource elements that can be used for downlink transmission, such as in a short length DwPTS, is similar to that of a typical downlink subframe.
• less resources should be used as DM-RS.
• the antenna port 7 and the antenna port 8 are separated and transmitted by mutually orthogonal codes in the same resource element, and the antenna port 9 and the antenna port 10
• the code is divided into two orthogonal codes and transmitted in separate resources.
• DM-RSs transmitted by being separated by codes in the same resource element may be referred to as one code division multiplex (CDM) group.
• the transmission powers of the DM-RSs transmitted to the antenna port 7 and the antenna port 8 are summed up, respectively, and the transmission of the DM-RS transmitted to the antenna port 9 and the antenna port 10 is performed.
• the power is transmitted in the form of summing. That is, when there is a limit on the power available in the individual resource element, the DM-RS of the antenna port transmitted in the same resource element is divided and divided into the power, and as a result, the transmission power of the individual antenna port is reduced.
• DM-RS transmission power amplification may be easier because all transmission powers of the corresponding resource element may be used by the DM-RS of the corresponding antenna port.
• the DM-RS overhead may increase.
• the present invention proposes a method of properly selecting a set of DM-RSs to be used for transmission in consideration of the relationship between the DM-RS transmission power amplification effect and the DM-RS overhead.
• two of the antenna port 7 to the antenna port 10 An example of a method of transmitting DM-RS using an antenna port will be described.
• a transmission diversity scheme may be applied to a signal (ie, E ⁇ PDCCH or PDSCH) that is modulated and demodulated using the DM-RS.
• Examples of the city method include a space frequency block coding (SFBC) or a beam cycling method for converting a precoder applied to each resource element according to a predefined method.
• SFBC space frequency block coding
• a specific example of the beam cycling method may include that different antenna ports are applied to each resource element.
• this transmission diversity scheme is suitable for transmission of control signals that require more stable transmission.
• DM-RSs belonging to different CDM groups are used to utilize transmit power amplification. That is, DM-RS to be used for channel demodulation is transmitted using antenna port 7 and antenna port 9 (or antenna port 8 and antenna port 10). More specifically, in order to apply the beam cycling method, the antenna port 7 and the antenna port 9 (or the antenna port 8 and the antenna port 10) belonging to different CDM groups for each resource element are cyclically applied. will be.
• antenna port 7 and antenna port 8 are used. More specifically, to apply the beam cycling method, antenna port 7 and antenna port 8 or antenna port 9 and antenna port 10 belonging to the same CDM group for each resource element are applied cyclically.
• a proper threshold may be defined and appropriate actions may be taken depending on whether the number of resource elements available for E-PDCCH transmission or the number of OFDM symbols is above or below the above threshold.
• antenna port 7 and antenna belonging to different CDM groups Port 9 is used, but in special subframe, antenna port 7 and antenna port 8 belonging to the same CDM group are used.
• CP length For example, use antenna port 7 and antenna port 9 in a normal CP with a relatively large number of resource elements, but use antenna port 7 and antenna in an extended CP with fewer resource elements. Is to use port 8.
• the base station may inform the set of antenna ports to be used for each subframe through a higher layer signal in advance.
• a DM-RS always located in a different CDM group is used, and the number of resource elements available for E-PDCCH transmission is small.
• the remaining DM-RS resource elements may be used as available resource elements for the E-PDCCH.
• the DM-RS may be transmitted using only two OFDM symbols, which are the first or the subsequent OFDM symbols among the four OFDM symbols.
• FIG. 16 shows an example of allocating an antenna port to resource elements for E-PDCCH transmission according to an embodiment of the present invention.
• FIG. 16 illustrates an example of allocating antenna ports in units of available resource elements constituting E ⁇ REG.
• FIG. 16A illustrates a subframe of a general CP
• FIG. 16B illustrates a subframe of an extended CP.
• the number in the grid indicates the corresponding resource. Indicates the DM-RS antenna port index assigned to the element.
• antenna port 7 and antenna port 9 are E for the beam cycling method. It can be seen that the resources are cyclically allocated for the available resource elements constituting the -REG.
• the antenna port 7 and the antenna port 8 It can be seen that is recursively allocated for the available resource elements constituting the E-REG.
• FIG. 17 illustrates a block diagram of a communication device according to an embodiment of the present invention.
• the communication device 1700 includes a processor 1710, a memory 1720, an RF module 1730, a display module 1740, and a user interface modules 1750.
• the communication device 1700 is illustrated for convenience of description and some modules may be omitted. In addition, the communication device 1700 may further include necessary modules. In addition, some of the hairs in the communication device 1700 can be divided into more granular hairs.
• the processor 1710 is configured to perform an operation according to an embodiment of the present invention illustrated with reference to the drawings. In detail, the detailed operation of the processor 1710 may refer to the contents described with reference to FIGS. 1 to 16.
• the memory 1720 is connected to the processor 1710 and stores an operating system, an application, a program code, and a data set.
• the RF modules 1730 are connected to the processor 1710 and perform a function of converting a baseband signal into a radio signal or converting a radio signal into a baseband signal. To this end, the RF modules 1730 perform analog conversion, amplification, filtering and frequency up-conversion or their reverse processes.
• Display modules 1740 are connected to the processor 1710 and display various information.
• the display modules 1740 may use well-known elements such as, but not limited to, a liquid crystal display (LCD), a light emitting diode (LED), and a zero light emitting diode (0LED).
• the user interface modal 1750 is connected with the processor 1710 and is well connected such as a keypad, touch screen, etc. It can consist of any combination of known user interfaces.
• an embodiment according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof.
• an embodiment of the present invention may include one or more appli cation specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), Field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.
• ASICs appli cation specific integrated circuits
• DSPs digital signal processors
• DSPDs digital signal processing devices
• PLDs programmable logic devices
• FPGAs Field programmable gate arrays
• processors controllers, microcontrollers, microprocessors, and the like.
• an embodiment of the present invention may be implemented in the form of modules, procedures, functions, etc. that perform the functions or operations described above.
• the software code may be stored in a memory unit and driven by a processor.
• the memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

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Citations (4)

• 2013
  • 2013-02-07 WO PCT/KR2013/000991 patent/WO2013119053A1/fr not_active Ceased

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