KR20180123205A - Method for transmitting and receiving message for random access in multi beam system - Google Patents

Abstract

Transmitting a synchronization signal block in which a synchronization signal is transmitted by performing beam sweeping of multiple beams, receiving a message 1 of the RA procedure from a UE, combining mapping between a PRACH resource and a synchronization signal block used for transmission of the message 1 Determining an optimal transmission beam to transmit message 2 of the RA procedure based on information about the optimal transmission beam, and transmitting message 2 using the optimal transmission beam, is provided .

Description

[0001] METHOD FOR TRANSMITTING AND RECEIVING MESSAGE FOR RANDOM ACCESS IN MULTI BEAM SYSTEM [0002]

The present disclosure relates to a method for transmitting and receiving a random access message in a multi-beam system.

The work item (WI) of the 3GPP NR (new radio) system aims to meet 5G requirements. 3GPP NR employs multi-beam operation based on hybrid beamforming to improve system performance.

One embodiment provides a method for a base station of a multi-beam system to transmit and receive a message for an RA to and from a UE.

Another embodiment provides a method for a UE of a multi-beam system to transmit and receive a message for an RA to and from a base station.

Another embodiment provides another way for the base station of the multi-beam system to send and receive messages for the RA to and from the UE.

According to one embodiment, a method is provided for a base station of a multi-beam system to send and receive messages for user equipment (UE) and for random access (RA). The RA message transmission method includes: performing a beam sweep of multiple beams to transmit a synchronization signal block including a synchronization signal; receiving a message 1 of an RA procedure from a user equipment (UE); Determining an optimal transmission beam to transmit message 2 of the RA procedure based on information about a binding mapping between a physical random access channel (PRACH) resource used for transmission and a synchronization signal block, And transmitting the message 2 using the second message.

The step of receiving the message 1 in the RA message transmitting / receiving method may include a step of performing reception beam sweeping to successfully receive the message 1 and then calibrating the reception beam of the base station.

In the RA message transmission / reception method, the multi-beam and the optimal transmission beam for transmitting the synchronization signal block may be a wide transmission beam.

The method of transmitting and receiving an RA message includes transmitting a signal for fine calibration of a transmission beam to a UE and receiving information about an optimal transmission beam determined as a result of measurement of a signal for fine calibration through a message 3 of an RA procedure .

In the RA message transmission / reception method, information on the optimal transmission beam may be included in a payload added to the message 3 or included in a physical uplink shared channel (PUSCH).

In the RA message transmission / reception method, the synchronization signal block may include a time index indication corresponding to index information of multiple beams.

In the combining mapping of the RA message transmission / reception method, the synchronization signal block may be mapped 1: 1 with the PRACH resource.

In the combined mapping of the RA message transmission / reception method, the synchronization signal block may be mapped to a plurality of PRACH resources.

According to another embodiment, a method is provided for a user equipment (UE) of a multi-beam system to transmit and receive messages for a random access (RA) with a base station. The RA message transmission / reception method includes: receiving a synchronization signal block including a synchronization signal from multiple beams of a base station; generating synchronization information based on information on a mapping between a synchronization signal block and a physical random access channel (PRACH) Determining a PRACH resource to transmit message 1 of the RA procedure to the base station, and sending message 1 to the base station using the determined PRACH resource.

In the RA message transmission / reception method, the multi-beam may be a wide transmission beam.

The RA message transmission / reception method comprises the steps of: receiving a signal for fine calibration of a transmission beam of a base station from a base station; determining information about an optimal transmission beam of a base station based on a measurement result of a signal for fine calibration; And transmitting information on the transmission beam to the base station through message 3 of the RA procedure.

In the RA message transmission / reception method, the step of transmitting the information on the optimal transmission beam may be performed by using a payload added to the message 3 or using a physical uplink shared channel (PUSCH) And transmitting the information.

The RA message transmission / reception method may further comprise determining index information of a transmission beam of the base station based on a time index indication included in the synchronization signal block.

In the combining mapping of the RA message transmission / reception method, the synchronization signal block may be mapped 1: 1 with the PRACH resource.

In the combined mapping of the RA message transmission / reception method, the synchronization signal block may be mapped to a plurality of PRACH resources.

According to yet another embodiment, a method is provided for a base station of a multi-beam system to send and receive messages for a random access (RA) with a terminal. The RA message transmission / reception method includes: performing a beam sweep of multiple beams to transmit a synchronization signal block including a synchronization signal; receiving a message 1 of an RA procedure from a user equipment (UE); Determining an optimal transmission beam to transmit message 2 of the RA procedure based on information about the association mapping between the preamble index of the preamble and the synchronization signal block included and transmitting the message 2 using the optimal transmission beam do.

In the RA message transmission / reception method, the preamble may be transmitted through the same or a different physical random access channel (PRACH) resource.

In the RA message transmission / reception method, the preamble can be transmitted through all available physical random access channel (PRACH) resources.

In the RA message transmission / reception method, the preamble may be a coded preamble orthogonal to each other.

In the combined mapping of the RA message transmission / reception method, the synchronization signal block is mapped to a preamble and a physical random access channel (PRACH) resource, and the step of receiving the message 1 comprises: And receiving the data.

It is possible to provide a random access procedure suitable for a multi-beam system through a coupling mapping between the SS block and the PRACH resource.

1 is a conceptual diagram illustrating a multi-beam pattern of a base station according to an embodiment.
2 is a conceptual diagram illustrating a synchronization signal structure according to an embodiment.
3 is a diagram illustrating an association mapping between an SS burst set and an RA preamble resource in a PRACH resource according to an embodiment.
4 is a diagram illustrating a binding mapping between an SS burst set and an RA preamble resource in a PRACH resource according to another embodiment.
5 is a diagram illustrating a joint mapping between an SS burst set and an RA preamble resource in a PRACH resource according to yet another embodiment.
FIG. 6 is a flowchart illustrating a 4-step RA procedure of the multi-beam system according to the embodiments.
7 is a conceptual diagram illustrating a mapping between a PRACH resource and a base station receive beam according to an embodiment.
8 is a conceptual diagram illustrating a wide transmission beam transmitting an SS block according to an embodiment.
9 is a conceptual diagram illustrating a mapping between a PRACH resource and a reception beam of a base station according to another embodiment.
10 is a conceptual diagram illustrating an RA procedure performed in parallel through a plurality of beam groups according to one embodiment.
11 is a block diagram illustrating a wireless communication system according to an embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present disclosure can be embodied in various different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention in the drawings, parts not related to the description are omitted, and like reference numerals are given to similar parts throughout the specification.

Throughout the specification, a user equipment (UE) is referred to as a terminal, a mobile station (MS), a mobile terminal (MT), an advanced mobile station (AMS) a high reliability mobile station (HR-MS), a subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT), a machine type communication device MTC device and the like and may include all or some functions of MT, MS, AMS, HR-MS, SS, PSS, AT, UE,

Also, a base station (BS) is an advanced base station (ABS), a high reliability base station (HR-BS), a node B, an evolved node B, eNodeB), a 5G-NR Node B, an access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR) A relay station (RS) serving as a base station, a relay node (RN) serving as a base station, an advanced relay station (ARS) serving as a base station, A high reliability relay station (HR-RS), a small base station (femto BS), a home node B (HNB), a home eNodeB (HeNB), a pico BS BS, RS, RN, ARS, HR-RS, small base station, etc.) may be referred to as " It may include all or some of the features.

FIG. 1 is a conceptual diagram illustrating a multi-beam pattern of a base station according to an embodiment, and FIG. 2 is a conceptual diagram illustrating a structure of a synchronization signal according to an embodiment.

Referring to FIG. 1, a base station of 5G NR uses a multi-beam pattern based on a beam group including N beams. Referring to FIG. 2, a synchronization signal (SS) structure of 5G NR is represented by an SS burst set, and an SS burst set includes one or more SS bursts. The SS block included in each SS burst corresponds to one SS beam exhibiting inherent directivity. That is, since beam sweeping is based on hybrid beamforming, each SS burst included in the SS burst set includes a plurality of SS blocks corresponding to beams having different directivities in the time domain. The SS burst of FIG. 2 can be regarded as corresponding to the beam group of FIG. The SS structure of Fig. 2 may be suitable for both single beam operation and multi-beam operation. The parameters related to the SS and the physical broadcast channel (PBCH) may also satisfy the following conditions.

- The period of the SS burst set is 20ms.

- The PBCH can be transmitted in each SS block.

In a multi-beam random access (RA), there is an association between an SS block and a physical random access channel (PRACH) resource.

According to one embodiment, an association mapping relationship between the SS block and the PRACH is provided, and a new four-step RA procedure in multi-beam operation is provided in this regard.

In the following, a single beam operation is treated as a special case of multi-beam operation, and the embodiments described below taking multi-beam operation as an example can be applied to a single beam operation as well. Below, after searching for the SS block from the base station (or the transmit / receive point (TRP) of the 3GPP NR, etc.), the user equipment (UE) Perform the 4 step RA procedure in which the message is used. First, a mapping mapping between the SS block and the PRACH resource will be described.

FIG. 3 is a diagram illustrating an association mapping between an SS burst set and an RA preamble resource in a PRACH resource according to an embodiment. FIG. 4 is a diagram illustrating a mapping mapping between an SS burst set and an RA preamble resource in a PRACH resource according to another embodiment. And FIG. 5 is a diagram illustrating a joint mapping between an SS burst set and an RA preamble resource in a PRACH resource according to yet another embodiment.

The PRACH resources shown in FIGS. 3 to 5 may represent time / frequency resources. The binding mapping shown in Figs. 3 to 5 assumes a scenario in which the base station transmits a beam group as shown in Fig. In FIG. 1, the base station transmits a downlink using M beam groups each including N beams. Also, the base station receives the uplink using m beam groups each including n beams. At this time. The total number of Tx beams of the base station is M * N, and the total number of reception beams (Rx beams) is m * n. 1 illustrates a direction of a transmission beam and a direction of a reception beam of a base station. The direction of the transmission beam and the direction of the reception beam at the base station may be different from each other, and the number of transmission beams and the number of reception beams may also be different from each other.

Combined mapping 1: Referring to FIG. 3 and FIG. 4, the SS block and the PRACH resource are mapped to 1: 1. In joint mapping 1 according to one embodiment, one SS block in the SS burst set is mapped to one PRACH resource. Thus, the preamble sequence of the PRACH resource can be transmitted by the UE corresponding to one beam direction. In FIG. 1, the transmission beam of the base station has M * N narrow beams, and the number of reception beams of the base station may be equal to the number of transmission beams. According to Fig. 3, M SS block groups (one SS block group including N SS blocks) included in the SS burst set can be distributed in the time domain. That is, each SS block group is spaced from the time domain. Then, M PRACH resource groups (each PRACH resource group includes N PRACH resources) can also be distributed in the time domain. In FIG. 3, each SS burst is mapped to one RA preamble in one PRACH resource. On the other hand, the M SS block groups included in the SS burst set can be consecutive in the time domain. That is, if the base station's beam is not grouped (i.e., the base station does not have a beam group), a plurality of SS blocks (or SS block groups) may be 1: 1 mapped in succession with a plurality of preambles in one PRACH resource . Referring to FIG. 4, one SS burst is mapped to one PRACH resource having a plurality of preamble indexes.

Combining Mapping 2: In general, in a base station, the number of transmission beam groups may be different from the number of reception beam groups. For example, when the periodicity of the SS burst set is 20 ms, the total number of beams transmitted from the base station side is quite large in a high frequency band (for example, 70 GHz band) such as a millimeter wave (mmWave) frequency band Therefore, 1: 1 mapping as shown in FIG. 3 may be difficult considering the radio frequency efficiency of the SS block. That is, the total number of SS blocks in the SS burst set may be less than the number of PRACH resources (which may be the same as the reception beam direction of the base station). Thus, referring to FIG. 5, in an association mapping 2, one SS block may be mapped to a plurality of PRACH resources. The joint mapping 2 shown in FIG. 5 can be applied irrespective of whether the base station includes a beam group. On the other hand, it is also possible that a plurality of SS blocks are mapped to one PRACH resource. The combining mapping between a plurality of SS blocks and one PRACH resource can be intuitively understood through FIG.

Combined Mapping 3: An SS block is combined with a different preamble index, and each preamble can be transmitted on the same or different PRACH resources. The preamble having an index different from that of the SS block may be a coded preamble orthogonal to each other, such as an orthogonal cover code. The combined SS blocks and RA preambles with different indices may be 1: 1 mappings or 1: mappings. That is, the preamble index is predetermined and combined with the base station receive beam direction. One SS block may be combined with one or more preamble indices (or coded preambles).

Combination mapping 4: One SS block is combined with a PRACH resource and a preamble index (or coded preamble). Therefore, the combining mapping 4 may be a combination of the combining mappings described above, and there are four combinations of the combining mappings described above: 1) one PRACH resource having one SS block and one preamble index (or coded preamble) (2) a mapping between one SS block and one PRACH resource having a plurality of preamble indexes (or a coded preamble), and (3) one SS block and one preamble index (or coded preamble) A binding mapping between a plurality of PRACH resources, and 4) a mapping between one SS block and a plurality of PRACH resources each having a plurality of preamble indices (or coded preambles).

The number of PRACH resources may be smaller than the number of reception beams of the base station. In this case, one PRACH resource may correspond to a plurality of beam directions. However, the binding mapping between the SS block and the PRACH resource (or preamble index) is independent of the relationship between the number of PRACH resources and the number of beams.

If there is no beam correspondence at the base station and the beam corresponding information is not available at the UE, beam sweeping and beam calibration are essential to accurately locate the beam at the base station. The UE can also successfully connect to the network through beam sweep and beam calibration. The absence of beam correspondence does not mean that there is no information about the transmit and receive beams of the base station. For example, without beam mapping, the base station can still roughly know the relationship between the transmission beam direction and the reception beam direction of the base station. There may be partial knowledge between the transmission beam direction and the reception beam direction of the base station. For a specific transmit beam direction, the base station may know the index of one or several receive beams and receive beams located in the periphery of the transmit beam direction. Conversely, for a specific receive beam direction, the base station can know the index of one or several transmit and transmit beams that are in the periphery of the receive beam direction. Here, beam management of the UE side is not described. This is because the UE can perform beam switching and repeat the network RA procedure. The beam switching of the UE is an implementation issue of the UE side.

The combination mapping described above can be applied to the 4-step RA procedure.

- 4 steps RA procedure 1

In the fourth step RA procedure 1, it is assumed that the total number of base station transmission beams is equal to the total number of base station reception beams. The beam direction of the base station transmit beam may be the same as or different from the beam direction of the base station receive beam. A binding mapping 1 between the SS block and the PRACH resource can be applied to the 4-step RA procedure 1. [ In the fourth step RA procedure 1, the number of SS blocks is equal to the number of PRACH resources (or the number of preamble indexes), and the number of SS blocks is equal to the number of transmission beams and reception beams of the base station.

1. SS block transmission of base station

The base station (gNB or TRP, etc.) performs beam sweeping to transmit the SS block. Each SS block is transmitted via a base station transmit beam, and each SS block corresponds to a different beam. Each SS block may carry a unique time index indication. The time index indication corresponds to the index information of the base station transmit beam. If the UE successfully detects one or more SS blocks, the UE may know the index information of the base station transmit beam with the time index indication of the detected SS block. It is the base station's transmit beam calibration that the base station transmits multiple SS blocks using transmit beam sweeping.

2. Send Message 1 (Msg. 1)

The index information of the transmission beam of the base station is required for the transmission of the message 2 (Msg. 2) and the message 4 (Msg. 4) of the base station and for the downlink transmission. Accordingly, the UE can feed back the index information of the transmission beam of the base station to the base station through the message 1. [ Combined mapping 1 may be used to carry the index information of the transmission beam of the base station. That is, since the SS block detected by the UE corresponds to the information of the combined PRACH resource used by the UE to transmit the message 1, the UE transmits the index information of the transmission beam of the base station to the base station . In this case, the base station can know the optimal transmission beam to be fed back by the UE based on the information about the PRACH resource used by the UE. For example, the UE determines the PRACH resource corresponding to the detected SS block based on the mapping relationship between the SS block and the PRACH resource, and transmits the message 1 to the base station using the determined PRACH resource. The base station can then determine an optimal transmission beam from the information about the transmission beam used when transmitting the SS block corresponding to the PRACH resource used for transmission of message 1.

Also, message 1 may be transmitted over multiple PRACH resources for receive beam calibration of the base station when there is no beam correspondence of the base station. For example, after the UE detects several SS blocks, the UE may know the location of a plurality of PRACH resources for message 1 transmission based on the association between the predefined SS block and PRACH resources. The number of PRACH resources used by the UE at this time may be different from the number of SS blocks detected by the UE, even if the PRACH resource is selected by the UE based on the 1: 1 association mapping (binding mapping 1).

3. Message 2 (Msg. 2) transmission

After successfully receiving message 1 from the UE, the base station can know the index of the optimal transmit beam for the UE based on information about the PRACH resource used by the UE. In addition, since the base station performs reception beam sweeping when receiving the message 1 on the plurality of PRACH resources, the reception beam correction of the base station can also be successful. In this case, one PRACH resource corresponds to one base station receive beam. 7 is a conceptual diagram illustrating a mapping between a PRACH resource and a base station receive beam according to an embodiment. The base station can also know the optimal receive beam for the UE since the base station searches for PRACH resources in the direction with the best performance metric. At this time, the best performance metric may be the maximum received power or the like. Thus, the base station can send message 2 to the UE via the optimal transmission beam based on the feedback of the UE. It should be borne in mind that, after successfully receiving message 1 from the UE, the transmit beam and receive beam calibration of the base station is performed.

4. Send Message 3 (Msg. 3)

Since the base station has performed beam calibration on the transmit and receive beams, the message 3 transmission of the UE is identical to the message 3 transmission of the single beam system.

5. Send Message 4 (Msg. 4)

Since the base station has performed beam calibration on the transmit and receive beams, the transmission of the message 4 of the base station is also the same as the transmission of the message 4 of the single beam system.

Since it is a multi-beam operation, in the 4-step RA procedure 1 according to the embodiment, the reception beam calibration for the uplink of the base station and the transmission beam calibration for the downlink are necessary. However, considering the radio resource efficiency, the number of SS blocks in the SS burst set period may be smaller than the number of PRACH resources and the number of transmission / reception beams of the base station.

- 4 steps RA procedure 2

In a four-step RA procedure 2 according to one embodiment, the number of transmit beams (or beam groups) of the base station is equal to or different from the number of receive beams (or beam groups). And the number of SS blocks is smaller than the number of transmission beams or the number of reception beams of the base station. The number of PRACH resources is equal to the number of reception beams of the base station. The binding mapping 2 described above can be applied to the four-step RA procedure 2 according to one embodiment.

1. SS block transmission of base station

The base station transmits the SS block through beam sweeping. Each SS block is transmitted from a base station via a wide Tx beam, and each of the SS blocks corresponds to a different wide-width transmission beam. 8 is a conceptual diagram illustrating a wide transmission beam transmitting an SS block according to an embodiment. According to one embodiment, a wide transmission beam may be used when the number of SS blocks included in one SS burst set is small. That is, when the number of SS blocks included in one SS burst set is not enough compared to the number of narrow transmission beams, a wide transmission beam can be used for transmission of SS blocks. The SS block carries a unique time index indication, and the time index indication corresponds to the index information of the wide transmission beam of the base station. If the UE successfully detects one or more SS blocks with the system information, the UE knows the time index indication of the SS block and also knows the index information of the wide transmission beam of the base station. The base station transmits a plurality of SS blocks through transmission beam sweeping for beam calibration of the broad beam of the base station (coarse transmission beam correction).

2. Send message 1

The index information of the transmission beam of the base station is also required for the base station. Therefore, the UE can feed back the index information of the transmission beam to the base station through the message 1. The index information of the transmission beam can be fed back through the combining mapping 2 described above. According to one embodiment, the base station can know information about the optimal transmission beam being fed back by the UE based on information about the PRACH resources used by the UE. Also, when there is no beam correspondence of the base station, Message 1 of the UE includes a plurality of PRACH resources for receive beam calibration of the base station. After detecting several SS blocks, the UE learns the location of a plurality of PRACH resources to be used for transmission of message 1 based on a predetermined binding mapping between the SS block and the PRACH resources. That is, the UE transmits the message 1 through the preamble of the plurality of PRACH resources determined based on the binding mapping between the SS block and the PRACH resource.

3. Send message 2

After successfully detecting message 1 transmitted from the UE, the base station can determine the index information of the optimal transmission beam for the UE based on the information on the PRACH resource used for transmission of the message 1. Further, since the base station performs reception beam sweeping and receives message 1 in the plurality of PRACH resources from the UE, the base station can also successfully perform reception beam calibration. In this case, one PRACH resource corresponds to one reception beam at the base station, as shown in Fig. 7 is a conceptual diagram illustrating a mapping between a PRACH resource and a reception beam of a base station according to an embodiment. The base station can also determine the optimal receive beam for the UE since it determines the PRACH resource corresponding to the direction with the highest performance metric. The best performance metric may be the maximum received power or the like. That is, the base station can roughly perform wide transmission beam calibration and can precisely perform reception beam calibration. That is, message 2 may be transmitted from the base station to the UE over the optimal wide transmission beam determined based on the feedback of the UE.

4. Send message 3

According to one embodiment, after the beam calibration is performed roughly for the wide transmission beam of the base station, it is necessary to perform transmission beam calibration elaborately for transmission of message 3 and message 4. Unlike the four-step RA procedure 1 described above, the fine transmission beam calibration can be performed based on the UE's measurement of the signaling or channel other than the SS block. For example, fine calibration of the transmission beam of a base station may be performed based on a measurement of a signal, signaling, or channel, such as a channel state information-reference signal (CSI-RS). In order to perform fine calibration of the transmission beam of the base station, the UE can report the index information of the optimal transmission beam of the base station to the base station based on the measurement result. A method for the UE to report the index information of the transmission beam of the base station is as follows.

First, the index information of the optimal transmission beam of the base station determined after the fine calibration can be reported to the base station through the additional payload added to the message 3. Or the index information of the optimal transmission beam of the base station determined after the fine calibration may be reported to the base station via a physical uplink shared channel (PUSCH).

5. Send message 4

If fine beam calibration is performed on the transmission beam of the base station and information on the optimal transmission beam of the base station is reported to the base station via message 3, then the base station transmits message 4 using the reported optimal transmission beam (i.e., the narrow transmission beam) To the UE. However, if the information about the optimal transmission beam of the base station is not reported via message 3 (i.e., reported via the PUSCH after the RA procedure), the base station reuses the wide transmission beam used for transmission of message 2, To the UE. At this time, the information included in the message 4 may be the same as the message 4 of the single beam system.

- Step 4 RA Procedure 3

The 4-step RA procedure 3 according to an embodiment is for a case where the number of PRACH resources is smaller than the number of reception beams of the base station. Where coarse beam calibration and fine beam calibration are required for both the transmit and receive beams of the base station. FIG. 9 shows the mapping between the PRACH resource and the reception beam of the base station applied in the 4-step RA procedure 3. 9 is a conceptual diagram illustrating a mapping between a PRACH resource and a reception beam of a base station according to another embodiment. 9, since the number of available PRACH resources can not cover all receive beams (i.e., narrow receive beam) direction of the base station, a wide receive beam may be used during the RA procedure for sparse beam calibration. If a wide beam is used in the RA procedure, radio resources can be saved and the delay of the RA procedure can be reduced. However, prior to performing the general communication after the RA procedure, microbeam calibration is required for the transmit and receive beams of the base station. In a four-step RA procedure 3 according to one embodiment, all SS blocks and RA messages are transmitted and received via a wide transmission beam and a wide reception beam, and the fine beam calibration is performed prior to the general data communication after the RA procedure. At this time, the number of transmission beams and reception beams may be different from the beam width.

In the following description, the number of SS blocks and the number of PRACH resources are smaller than the number of transmission beams and reception beams of the base station, and the RA procedure can be performed using beams in the beam group.

- Four-step RA procedure 4

The fourth step RA procedure 4 according to an exemplary embodiment is for a case where the number of SS blocks is smaller than the number of transmission beams of the base station and / or the number of PRACH resources is smaller than the number of reception beams of the base station. In this case, in view of combining mappings 1 and 2, a four-stage RA procedure 4 may be implemented for each beam group. For example, the number of SS blocks may be less than the number of transmission beams of the base station, but may be equal to the number of beams in the beam group. In this case, the RA procedure can be performed on a beam group basis. That is, a plurality of RA procedures can be performed simultaneously in parallel through a plurality of beam groups. 10 is a conceptual diagram illustrating an RA procedure performed in parallel through a plurality of beam groups according to one embodiment. Referring to FIG. 10, SS blocks and PRACH resources may be reused in different beam groups due to the degree of freedom of the spatial domain. That is, when N beams are included in each beam group, the SS block and the PRACH resource can be transmitted / received through a beam of the same index at one point in time. For example, beam 1 is used in each beam group at time 1, beam 2 of each beam group is used at time 2, and beam N of each beam group is used at time N. [ The four-step RA procedures 1, 2, and 3 described above can also be performed on a beam group basis.

If the number of SS blocks and the number of PRACH resources are smaller than the number of transmission and reception beams of the base station, messages 2 and 4 may be transmitted through beam sweeping for fine calibration of the transmission beam of the base station.

- Four-step RA procedure 5

Step 4 RA Procedure 5 is similar to Step 4 RA Procedures 1, 2, 3, and 4 in terms of Combination Mappings 1 and 2 described above. Step 4 In the RA procedure 5, messages 2 and 4 can be transmitted via beam sweeping for fine calibration of the transmission beam of the base station. Correspondingly, the index information about the fine transmission beam can be reported to the base station via the additional payload of message 3 or the PUSCH.

Combination mappings 1 and 2 can be applied to the above-described four-step RA procedure. That is, in the 4-step RA procedures 1, 2, 3, 4, and 5, the PRACH resource is mapped to the reception beam of the base station in the time and frequency domains. However, in binding mappings 3 and 4, the preamble (or coded preamble) may be mapped to the receive beam of the base station in the time and frequency domain. In the following, the 4-step RA procedure 6 and the 4-step RA procedure 7, to which join mapping 3 and 4 can be applied, are described in detail.

- Four-step RA procedure 6

In joint mapping 3, the SS block is mapped to one or more preambles (or coded preambles). Different SS blocks may be mapped to different preambles (or coded preambles). At this time, all UEs can transmit message 1 through all available PRACH resources using the preamble (or coded preamble) mapped to the detected SS block. The contention between each UE (i.e. collisions that may occur when transmitting a preamble through all PRACH resources) can be resolved by using different orthogonal preambles (or coded preambles). The base station can determine an optimal transmission beam based on the preamble received from the UE. At this time, the optimal transmission beam may be a narrow beam if the number of SS blocks is sufficient to correspond to all transmission beams, and may be a wide beam if the number of SS blocks is limited. The transmission and reception of the messages 2 to 4 are the same as the four-step RA procedures 1 to 5 described above. In step 4 RA procedure 6, the PRACH resource efficiency may be higher due to the degree of freedom in the code domain in the message 1 transmission.

- Four-step RA procedure 7

In joint mapping 4, one SS block is all mapped with a preamble (or coded preamble) and a PRACH resource. At this time, since message 1 is not transmitted using all the PRACH resources, it may be different from the format of message 1 of the 4-step RA procedure 6. [ That is, in the 4-step RA procedure 7, each UE can transmit a message 1 including a preamble (or a coded preamble) mapped to an SS block detected through the detected SS block and the PRACH resource mapped. The transmission and reception of the messages 2 to 4 are the same as the four-step RA procedures 1 to 5 described above.

As described above, according to one embodiment, a random access method suitable for a multi-beam system can be provided based on a combination mapping between a synchronization signal block and a PRACH resource or a combination mapping of a synchronization signal block and a preamble index.

11 is a block diagram illustrating a wireless communication system according to an embodiment.

Referring to FIG. 11, a wireless communication system according to an embodiment includes a base station 1110 and a UE 1120. The base station 1110 includes a processor 1111, a memory 1112, and a radio frequency unit (RF unit) 1113. The memory 1112 may be coupled to the processor 1111 to store various information for operating the processor 1111 or at least one program executed by the processor 1111. [ The wireless communication unit 1113 is connected to the processor 1111 to transmit and receive a wireless signal. The processor 1111 may implement the functions, processes, or methods proposed in the embodiments of the present disclosure. At this time, in the wireless communication system according to an embodiment of the present invention, the wireless interface protocol layer may be implemented by the processor 1111. [ The operation of base station 1110 in accordance with one embodiment may be implemented by processor 1111. [

The UE 1120 includes a processor 1121, a memory 1122, and a wireless communication unit 1123. The memory 1122 may be coupled to the processor 1121 to store various information for driving the processor 1121 or at least one program to be executed by the processor 1121. [ The wireless communication unit 1123 is connected to the processor 1121 to transmit and receive a wireless signal. The processor 1121 may implement the functions, steps, or methods suggested in the embodiments of the present disclosure. At this time, in the wireless communication system according to an embodiment of the present invention, the wireless interface protocol layer can be implemented by the processor 1121. [ The operation of the UE 1120 according to one embodiment may be implemented by the processor 1121. [

In an embodiment of the present disclosure, the memory may be located inside or outside the processor, and the memory may be connected to the processor through various means already known. The memory may be any type of volatile or nonvolatile storage medium, e.g., the memory may include read-only memory (ROM) or random access memory (RAM).

Although the embodiments have been described in detail, the scope of the rights is not limited thereto, and various modifications and improvements of the skilled person using the basic concepts defined in the following claims are also within the scope of the right.

Claims (20)

A method for a base station of a multi-beam system to send and receive messages for user equipment (UE) and for random access (RA)
Performing beam sweeping of multiple beams to transmit a sync signal block including a sync signal,
Receiving message 1 of the RA procedure from user equipment (UE)
Determines an optimal transmission beam to transmit message 2 of the RA procedure based on information on a physical random access channel (PRACH) resource used for transmission of the message 1 and a mapping mapping between the synchronization signal block Step, and
And transmitting the message 2 using the optimal transmission beam
And transmitting the RA message. The method of claim 1,
The step of receiving the message 1 comprises:
Performing reception beam sweeping to successfully receive the message 1, and then calibrating a reception beam of the base station
And transmitting the RA message. The method of claim 1,
Wherein the multi-beam and the optimal transmission beam for transmitting the synchronization signal block are wide-width transmission beams. 4. The method of claim 3,
Transmitting a signal for fine calibration of the transmission beam to the UE, and
Receiving information regarding the optimal transmission beam determined as a result of measurement of the signal for fine calibration through message 3 of the RA procedure;
And transmitting the RA message. 5. The method of claim 4,
Wherein the information about the optimal transmission beam is included in a payload added to the message 3 or included in a physical uplink shared channel (PUSCH). The method of claim 1,
Wherein the synchronization signal block includes a time index indication corresponding to index information of the multi-beam. The method of claim 1,
Wherein the synchronization signal block is mapped 1: 1 with the PRACH resource in the binding mapping. The method of claim 1,
Wherein the synchronization signal block in the binding mapping is mapped to a plurality of PRACH resources. A method for a user equipment (UE) of a multi-beam system to send and receive messages for a random access (RA) with a base station,
Receiving a synchronization signal block including a synchronization signal from multiple beams of the base station,
Determining a PRACH resource for transmitting message 1 of the RA procedure based on information about a binding mapping between the synchronization signal block and a physical random access channel (PRACH) resource, and
Transmitting the message 1 to the base station using the determined PRACH resource
And transmitting the RA message. The method of claim 9,
Wherein the multi-beam is a wide transmission beam. 11. The method of claim 10,
Receiving a signal for fine calibration of a transmission beam of the base station from the base station,
Determining information about the optimal transmission beam of the base station based on the measurement result of the signal for the fine calibration, and
Transmitting information about the optimal transmission beam to the base station via message 3 of the RA procedure
And transmitting the RA message. 12. The method of claim 11,
Wherein the step of transmitting information regarding the optimal transmission beam comprises:
Transmitting information about the optimum transmission beam using a payload added to the message 3 or using a physical uplink shared channel (PUSCH)
And transmitting the RA message. The method of claim 9,
Determining index information of a transmission beam of the base station based on a time index indication included in the synchronization signal block
And transmitting the RA message. The method of claim 9,
Wherein the synchronization signal block is mapped 1: 1 with the PRACH resource in the binding mapping. The method of claim 9,
Wherein the synchronization signal block in the binding mapping is mapped to a plurality of PRACH resources. A method for a base station of a multi-beam system to transmit and receive a message for a random access (RA) with a terminal,
Performing beam sweeping of multiple beams to transmit a sync signal block including a sync signal,
Receiving message 1 of the RA procedure from user equipment (UE)
Determining an optimal transmission beam to transmit message 2 of the RA procedure based on information about a mapping between a preamble index of the preamble included in the message 1 and the synchronization signal block,
And transmitting the message 2 using the optimal transmission beam
And transmitting the RA message. 17. The method of claim 16,
Wherein the preamble is transmitted through the same or a different physical random access channel (PRACH) resource. 17. The method of claim 16,
Wherein the preamble is transmitted through all available physical random access channels (PRACH) resources. 17. The method of claim 16,
Wherein the preamble is a coded preamble orthogonal to each other. 17. The method of claim 16,
In the combining mapping, the synchronization signal block is mapped to the preamble and a physical random access channel (PRACH) resource,
The step of receiving the message 1 comprises:
Receiving a message 1 including the preamble through the PRACH resource
And transmitting the RA message.

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