TW202329741A - Method and user equipment for rach procedure - Google Patents

Abstract

A method for random access channel (RACH) procedure is proposed. The network node allocates a transmission configuration indicator (TCI) state associated with the RACH procedure for a user equipment (UE) and transmits a command triggering the RACH procedure for a candidate cell to the UE. The UE determines the RACH resource configured to the candidate cell based on the TCI state associated with the candidate cell. Then, the UE transmits a message on the RACH resource to the network node.

Description

Method and user equipment for random access channel procedure

Embodiments of the present invention relate generally to wireless communication systems, and, more particularly, to random access channels with state activation/indication of a transmission configuration indicator (TCI). RACH) process.

Wireless communication networks have grown exponentially over the years. Long-Term Evolution (LTE) systems offer high peak data rates, low latency, improved system capacity, and low operating costs brought about by a simple network architecture. The LTE system, also known as the 4th Generation (4G) system, also provides seamless integration with older networks, such as Global System For Mobile Communications (GSM), Code Division Multiple Access ( Code Division Multiple Access, CDMA) and Universal Mobile Telecommunications System (UMTS). In the LTE system, the evolved universal terrestrial radio access network (evolved universal terrestrial radio access network, E-UTRAN) includes a plurality of evolved node Bs communicating with a plurality of mobile stations called user equipment (UE). (evolved Node-B, eNodeB or eNB). A ^3rd generation partner project (3GPP) network typically includes a mix of 2nd Generation (2G)/3rd Generation (3G)/4G systems. The Next Generation Mobile Network (NGMN) Board of Directors has decided to focus future NGMN activities on defining the end-to-end requirements for 5th Generation (5G) new radio (NR) systems.

In traditional 5G technology, after the UE triggers the cell change or handover process through radio resource control (radio resource control, RRC) signaling, only downlink synchronization (DL sync) operations and uplink (uplink synchronization) operations will be performed. , UL) synchronous operation (for example, RACH procedure). However, in the current RACH procedure, there is no TCI status associated with the RACH procedure. UE may not have enough information to perform RACH procedure. Furthermore, in the current RACH procedure, DL synchronization operation and UL synchronization operation need to be operated based on two separate procedures.

So, seek a solution.

A method for RACH procedure is proposed. The network node assigns the TCI state associated with the RACH procedure to the UE, and sends a command to the UE to trigger the RACH procedure of the candidate cell. The UE may determine the RACH resources configured for the candidate cell based on the TCI state associated with the candidate cell. In addition, the UE can send a message to the network node on the RACH resource. When the command indicates to trigger the RACH procedure associated with the TCI for cell change or handover, the UE may trigger the cell change or handover based on the TCI status. Therefore, in the present invention, TCI status can be associated with RACH procedure, and DL synchronization operation and UL synchronization operation can be combined in the same procedure.

In one embodiment, the UE may receive an order from the network node, the order triggering the RACH procedure of the candidate cell. The UE may determine the RACH resources configured for the candidate cell based on the TCI state associated with the candidate cell. In addition, the UE can send a message to the network node on the RACH resource.

In one embodiment, the UE also monitors a random access response (random access response, RAR) of the RACH procedure based on the TCI state. In addition, when the command indicates to trigger the RACH procedure for cell change or handover, the UE may further trigger the cell change or handover based on the TCI state.

The RACH process with TCI state indication proposed by the present invention can combine DL synchronization operation and UL synchronization operation in the same process, and accelerate the speed of cell change or switching.

Other embodiments and advantages are described in the detailed description below. This summary is not intended to define the invention. The present invention is limited by the patent scope of the invention application.

Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.

Figure 1 depicts an exemplary 5G NR network 100 in accordance with aspects of the present invention. The 5G NR network 100 includes a network node 101 communicatively connected to a licensed frequency band in an access network 110 (e.g., For UE 102 operating in mmWave, 30GHz~300GHz), the access network 110 provides radio access using radio access technology (RAT) (eg, 5G NR technology). The access network 110 is connected to the 5G core network 120 through the NG interface, more specifically, connected to the user plane function (UPF) through the NG user-plane part (NG user-plane part, NG-u) , and connect to the Mobility Management Function (AMF) through the NG control-plane part (NG-c). One gNB can be connected to multiple UPFs/AMFs for load sharing and redundancy purposes. The network node 101 may be a base station (base station, BS) or a gNB. The UE 102 may be a smart phone, a wearable device, an Internet of Things (Internet of Things, IoT) device, a tablet computer, and the like. Optionally, UE 102 may be a notebook computer (Notebook, NB) or a personal computer (Personal Computer, PC) inserted or installed with a data card, wherein the data card includes a modem (modem) and an RF transceiver to provide wireless communication Function.

The network node 101 can provide communication coverage for a geographic coverage area, where communication with the UE 102 is supported via the communication link 103 . The communication link 103 between the network node 101 and the UE 102 may utilize one or more frequency carriers to form one or more cells (eg, a PCell and one or more SCells). The communication link 103 shown in the 5G NR network 100 may include an uplink transmission from the UE 102 to the network node 101 (for example, on a Physical Uplink Control Channel (PUCCH) or a Physical Uplink on the physical uplink shared channel (Physical Uplink Shared Channel, PUSCH)), or the downlink transmission from the network node 101 to the UE 102 (for example, on the physical downlink control channel (Physical Downlink Control Channel, PDCCH) or the physical downlink shared channel (Physical Downlink Shared Channel, PDSCH)).

According to a novel aspect, UE 102 may receive commands from network node 101 . The order may trigger the RACH procedure of the candidate cell. UE 102 can then perform RACH procedures based on the order. Specifically, the UE 102 may determine the RACH resource configured for the candidate cell based on the TCI state associated with the candidate cell. UE 102 may receive commands based on TCI status. In addition, the UE 102 can send messages or information corresponding to the RACH procedure to the network node 101 on the RACH resource.

According to a novel aspect, the command from the network node 101 may indicate at least an index of the TCI state. In addition, the command may indicate at least a preamble index of the RACH procedure and a physical RACH (physical RACH, PRACH) mask index for contention free random access (CFRA).

In one example, the command may be downlink control information (DCI) indicating TCI status to UE 102 at least for DL reception. In another example, the command may be a medium access control (MAC) control element (CE) that indicates the TCI status to the UE 102 at least for enabling the TCI status. In the application, the command may indicate to trigger the RACH procedure for handover (or cell change), or indicate to trigger the RACH procedure for other operations (for example, timing advance (timing advance, TA) acquisition).

According to a novel aspect, the UE 102 may select or determine a synchronization signal (SS) and a physical broadcast channel (PBCH) block (SSB) or channel state information (channel state information) based on a TCI state associated with a RACH procedure status information, CSI) - reference signal (reference signal, RS). That is, the triggered RACH procedure may be associated with the SSB or CSI-RS determined or selected by the UE 102 based on the TCI status. The SSB or CSI-RS may be a source RS associated with at least quasi co-location (QCL) type D, which is directly or indirectly associated with the TCI status.

According to a novel aspect, a TCI state associated with a RACH procedure may be associated with an additional physical cell index (PCI) corresponding to a candidate cell. That is, if the TCI state is associated with an additional PCI, the SSB or CSI-RS can be associated with the additional PCI. Also, PRACH resources can be associated with SSB or CSI-RS. The network node 101 may configure parameters of RACH resource configuration (eg, RACH configuration and RACH timing) to the UE 102 for each additional PCI. In one example, UE 102 can determine or select RACH resources corresponding to SSB or CSI-RS. In another example, the network node 101 may allocate RACH resources corresponding to SSB or CSI-RS through RACH resource configuration. In another example, UE 102 may determine or select RACH resources corresponding to SSB or CSI-RS, and network node 101 may allocate RACH resources corresponding to SSB or CSI-RS through RACH resource configuration.

According to a novel aspect, UE 102 may determine a spatial transmission (Tx) filter based on a TCI state associated with a RACH procedure.

According to a novel aspect, after the UE 102 sends a message or information corresponding to the RACH procedure to the network node 101 on the RACH resource, the UE 102 can monitor and receive the RAR of the RACH procedure based on the TCI status.

According to a novel aspect, when the UE 102 monitors the RAR of the RACH procedure based on the TCI status, the UE 102 can detect the RAR on the control channel by assuming the demodulation reference signal (DM-RS) antenna port QCL attribute based on the TCI status DCI. In addition, UE 102 can receive RAR by assuming DM-RS antenna port QCL attributes based on TCI status. UE 102 may determine settings for the control channel. In one example, UE 102 may determine the setting of the control channel based on the configuration of the serving cell associated with the RACH procedure (or the cell triggering the RACH procedure). In another example, the UE 102 can determine the setting of the control channel based on the configuration of the candidate cell associated with the TCI state. In another example, the UE 102 may determine the setting of the control channel based on a system information block (SIB), where the SIB is associated with the SSB determined based on the TCI state.

According to a novel aspect, the network node 101 may indicate to the UE 102 whether to monitor RAR. In one example, the network node 101 may instruct the UE 102 whether to monitor the RAR through a command associated with the RACH procedure. In other words, the order may indicate whether UE 102 needs to monitor RAR for RACH procedures. If the command indicates that the UE does not need to monitor the RAR of the RACH procedure, it means that the UE only needs to send the random access preamble to the network.

According to a novel aspect, the UE 102 can apply the initial TA value indicated in the RAR or TA command to the TA group associated with the TCI state.

According to a novel aspect, if the command indicates to trigger a RACH procedure for cell change or handover, UE 102 may send a message or information (e.g., random access preamble) corresponding to the RACH procedure to the candidate cell (or another network node in the target cell). After the UE 102 receives the RAR from the network node of the candidate cell (or target cell), the UE 102 may perform a cell change or handover based on the TCI status.

Figure 2 depicts a simplified block diagram of a network node and a UE according to some embodiments of the present invention. The network node 201 may be a BS or a gNB, but the present invention should not be limited thereto. UE 202 may be a smart phone, a wearable device, an IoT device, a PC, etc. Alternatively, the UE 202 may be a NB or a PC with a data card inserted or installed, wherein the data card includes a modem and an RF transceiver to provide wireless communication functions.

The network node 201 has an antenna array 211 (the antenna array 211 has a plurality of antennas for transmitting and receiving radio signals), one or more radio frequency (radio frequency, RF) transceivers 212, coupled with the antenna array 211, from the antenna array 211 The RF signals are received, converted to baseband signals, and sent to the processor 213 . The RF transceiver 212 also converts the baseband signals received from the processor 213 , converts them to RF signals, and sends them to the antenna array 211 . The processor 213 processes the received baseband signal and invokes various functional modules and circuits 220 to perform functions in the network node 201 . The memory 214 stores program instructions and data 215 to control the operation of the network node 201 . The network node 201 also includes a plurality of functional modules and circuits for realizing different tasks according to the embodiments of the present invention.

Similarly, UE 202 has an array of antennas 231 for sending and receiving radio signals. The RF transceiver 232 is coupled to the antenna, receives RF signals from the antenna array 231 , converts them into fundamental frequency signals, and sends them to the processor 233 . The RF transceiver 232 also converts the baseband signals received from the processor 233 , converts them to RF signals, and sends them to the antenna array 231 . The processor 233 processes the received baseband signal and invokes various functional modules and circuits 240 to perform functions in the UE 202 . Memory 234 stores program instructions and data 235 to control the operation of UE 202 . The UE 202 also includes a plurality of functional modules and circuits for implementing different tasks according to the embodiments of the present invention.

The functional modules and circuits 220 and 240 can be realized and configured by hardware, firmware, software and any combination thereof. When executed by processors 213 and 233 (eg, by executing program instructions and data 215 and 235), functional modules and circuits 220 and 240 allow network node 201 and UE 202 to perform embodiments of the present invention.

In the example of FIG. 2 , the network node 201 includes a resource allocation circuit 221 and a configuration circuit 222 . Resource allocation circuitry 22 may allocate UE 202 a TCI state associated with a RACH procedure. The configuration circuit 222 may send a command to the UE 202 to trigger the RACH procedure of the candidate cell.

In the example of FIG. 2 , UE 202 may include determining circuitry 241 and reporting circuitry 242 . The determination circuit 241 may trigger the PRACH procedure based on the command from the network node 201, and determine the RACH resource configured for the candidate cell based on the TCI state associated with the candidate cell. The reporting circuit 242 may send messages or information (eg, random access preamble) corresponding to the RACH procedure to the network node 201 on the RACH resource.

Figure 3 depicts RACH procedures for cell change or handover in accordance with novel aspects. In step 310 , the network node 301 in the serving cell sends a command to the UE 302 . The command triggers the RACH procedure of the candidate cell.

In step 320, the UE 302 determines the RACH resources configured for the candidate cell based on the TCI state associated with the candidate cell. UE 302 can receive the order based on the TCI status associated with the candidate cell.

In step 330, the UE 302 sends the message or information of the RACH procedure (eg, random access preamble) to the network node 303 in the candidate cell (or target cell) on the RACH resource.

Steps 320 and 330 are applicable to message 1 (Msg1 ) of the conventional RACH procedure.

In step 340, the UE 302 may monitor the RAR of the RACH procedure based on the TCI status. The order may indicate whether the UE 302 needs to monitor the RAR of the RACH procedure.

In step 350 , the network node 303 in the candidate cell may send the RAR of the RACH procedure to the UE 302 .

Steps 340 and 350 are applicable to message 2 (Msg2) of the conventional RACH procedure.

In step 360, the UE 302 may perform a cell change or handover (ie, handover from a serving cell to a target cell) based on the TCI state.

Figure 4 is a method flow diagram of a RACH procedure in accordance with the novel aspects of the present invention. In step 401, the UE receives an order from the network node, the order triggers the RACH procedure of the candidate cell.

In step 402, the UE determines RACH resources configured for the candidate cell based on the TCI state associated with the candidate cell. In the described embodiment, the UE may receive the order based on the TCI status associated with the candidate cell.

In step 403, the UE sends a message to the network node on the RACH resource.

Fig. 5 is a method flow diagram of a RACH procedure according to another novel aspect of the present invention. In step 501, a UE receives an order from a first network node in a serving cell, and the order triggers a RACH procedure of a candidate cell. In said embodiment, said order also indicates to trigger RACH procedure for cell change or handover.

In step 502, the UE determines RACH resources configured for the candidate cell based on the TCI state associated with the candidate cell. In the described embodiment, the UE may receive the order based on the TCI status associated with the candidate cell.

In step 503, the UE sends a message to the second network node in the candidate cell (or target cell) on the RACH resource.

In step 504, the UE receives the RAR of the RACH procedure from the second network node.

In step 505, the UE triggers a cell change or handover based on the TCI state.

Although the invention has been described in connection with certain specific embodiments for instructional purposes, the invention is not limited thereto. Accordingly, various modifications, adaptations and combinations of the various features of the described embodiments may be effected without departing from the scope of the invention as set forth in the claims.

100:5G NR network 101,201,301,303: network nodes 102,202,302:UE 103: Communication link 110: access network 120: Core network 211,231: Antenna array 212,232: RF transceiver 213,233: Processor 214,234: memory 215, 235: Program instructions and data 220,240: Functional modules and circuits 221: Resource allocation circuit 222: Configuration circuit 241: Determine the circuit 242: Determine the circuit 310,320,330,340,350,360,401,402,403,501,502,503,504,505: steps

The drawings depict embodiments of the invention, wherein like numerals refer to like parts. FIG. 1 depicts an exemplary 5G NR network 100 in accordance with aspects of the present invention. Figure 2 depicts a simplified block diagram of a network node and a UE according to some embodiments of the present invention. Figure 3 depicts RACH procedures for cell change or handover in accordance with novel aspects. Figure 4 is a method flow diagram of a RACH procedure in accordance with the novel aspects of the present invention. Fig. 5 is a method flow diagram of a RACH procedure according to another novel aspect of the present invention.

302:UE

301,303: network nodes

310, 320, 330, 340, 350, 360: steps

Claims (13)

A method of randomly accessing a channel process, comprising: a UE receives a command from a network node that triggers a random access channel procedure for a candidate cell; and determining, by the UE, a RACH resource allocated to the candidate cell based on a transmission configuration indicator state associated with the candidate cell; and The UE sends a message to the network node on the RACH resource. The method for random access channel procedure as claimed in claim 1, wherein said command indicates at least an index of said transmission configuration indicator state. The method for random access channel procedure as claimed in claim 1, wherein the UE receives the command based on the transmission configuration indicator state. The method for random access channel procedure according to claim 1, wherein the command indicates at least a preamble index and a physical random access channel mask index. The method for random access channel procedure as claimed in claim 1, wherein the command is a downlink control information or a media access control control element. The method for random access channel process as claimed in claim 1, wherein the triggered random access channel process is associated with a synchronization signal and a physical broadcast channel block or a channel state information reference signal, wherein the synchronization signal and the physical broadcast channel block or the channel state information reference signal is determined based on the transmission configuration indicator state, and the random access channel resource is related to the synchronization signal and the physical broadcast channel block or the channel state information reference signal couplet. The method for the random access channel process as described in claim item 1, further comprising: The UE monitors a random access response of the random access channel process based on the transmission configuration indicator state. The method for a random access channel procedure according to claim 1, wherein the command indicates whether the UE needs to monitor a random access response of the random access channel procedure. The method for the random access channel process as described in claim item 7, further comprising: In case the command indicates to trigger the random access channel procedure for a cell change or handover, the UE performs the Cell change or handover. As the method for the random access channel process described in claim item 7, the monitoring also includes: A downlink control message on a control channel is detected by assuming a DRS antenna port quasi-co-location property based on the TCI state. The method for the random access channel process as described in claim item 10, further comprising: The UE is based on a configuration of a serving cell associated with the random access channel procedure, a configuration of a candidate cell associated with the transmission configuration indicator state and based on the transmission configuration indicator The state of at least one of a system block associated with a sync signal block is determined to determine a setting of the control channel. The method for the random access channel process as described in claim item 7, further comprising: The UE applies an initial timing advance value indicated in the random access response or a certain timing advance command to a certain timing advance group associated with the transmission configuration indicator state. A user equipment for a random access channel process, comprising: a receiver for receiving a command from a network node, the command triggering a random access channel procedure for a candidate cell; a processor for determining a random access channel resource allocated to the candidate cell based on a transmission configuration indicator state associated with the candidate cell; and A sender sends a message to the network node on the random access channel resource.

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