CN113892284A

CN113892284A - Reduced preparation time for transport block retransmission in wireless communications

Info

Publication number: CN113892284A
Application number: CN201980091759.6A
Authority: CN
Inventors: 本特·林多夫; 托斯顿·斯科尔; 迈克尔·坦普林; 菲利普·曼森; 冯淑兰; 拉马·库马尔·莫匹代韦
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-02-21
Filing date: 2019-02-21
Publication date: 2022-01-04
Anticipated expiration: 2039-02-21
Also published as: WO2020169198A1; CN113892284B

Abstract

The present disclosure relates to a preparation time for retransmission of a transport block. If a transmission grant is associated with an initial transmission of a transport block, the client device based on the received transmission grant and a first preparation time N_2:1To perform a first uplink transmission of a transport block; and if the transmission grant is associated with a retransmission of the transport block, the client device based on the transmission grant and the second preparation time N_2:1To perform a second uplink transmission of the transport block. Second preparation time N_2:2And a first preparation time N_2:1Different. Corresponding transmissions and retransmissions may also be performed by the network access node in the downlink data channel. Thus, a time reduction of the retransmission of the transport block is achieved. Furthermore, the present disclosure also relates to corresponding methods and computer programs.

Description

Reduced preparation time for transport block retransmission in wireless communications

Technical Field

The present disclosure relates to a client device and a network access node for reduced preparation time for transmission block retransmissions. Furthermore, the present disclosure also relates to corresponding methods and computer programs.

Background

The 3GPP 5G is a latest-generation cellular mobile communication system following the 4G also called Long Term Evolution (LTE). Among other things, the goals of 5G are high data rate, reduced latency, power savings, high system capacity, and large-scale device connectivity.

An important requirement of 3GPP 5G (also known as New Radio (NR)) is to support ultra-reliable and low latency communication (URLLC) services. The latency requirement of URLLC services is expressed as the time required to send a message over the network. For URLLC, the requirements for one way through a Radio Access Network (RAN) have been set for some services with a delay of 1ms and a PER of 10 e-5.

Disclosure of Invention

It is an object of embodiments of the present invention to provide a solution that alleviates or solves the drawbacks and problems of conventional solutions.

It is a further object of embodiments of the present invention to provide a solution that reduces the retransmission time of a transport block compared to conventional solutions.

The above and further objects are solved by the subject matter of the independent claims. Further embodiments of the invention can be found in the dependent claims.

According to a first aspect of the present invention, the above-mentioned and other objects are achieved with a client device for a wireless communication system, the client device being configured to:

receiving a transmission grant associated with an uplink transmission of a transport block;

based on a transmission grant and a first preparation time N, if the transmission grant is associated with an initial transmission of a transport block_2:1To perform a first uplink transmission of a transport block;

based on the transmission grant and the second preparation time N, if the transmission grant is associated with a retransmission of the transport block_2:2To perform a second uplink transmission of the transport block, wherein a second preparation time N_2:2And a first preparation time N_2:1Different.

A transmission grant may be received from a network access node, such as a base station, for example, in a Physical Downlink Control Channel (PDCCH). More precisely, such a transmission grant may be an uplink grant in Downlink Control Information (DCI) transmitted in the PDCCH. Conventionally, a transmission grant is received in response to a Scheduling Request (SR) being sent by a client device to a network access node.

The preparation time herein is sometimes denoted as Physical Uplink Shared Channel (PUSCH) preparation time in NR systems.

An advantage of the client device according to the first aspect is a reduced processing time and a limited complexity increase in the client device. In addition, by reducing the processing time for retransmission of transport blocks, the delay budget for URLLC services can be met.

In an implementation form of the client device according to the first aspect, the second preparation time N is_2:2Shorter than the first preparation time N_2:1。

An advantage of this implementation form is that the overall delay budget is reduced, since the retransmission of the transport block can be made faster compared to conventional solutions using the same preparation time for the initial transmission and the retransmission of the transport block.

In an implementation form of the client device according to the first aspect, the second preparation time N is_2:2Is less than the first preparation time N_2:180% of the total.

An advantage of this implementation form is that the overall delay budget is reduced, since retransmissions can be made faster compared to conventional solutions using the same preparation time for initial transmission and retransmissions of a transport block.

In an implementation form of the client device according to the first aspect, the second preparation time N is_2:2Is less than the first preparation time N_2:160% of the total.

In an implementation form of the client device according to the first aspect, the first preparation time N is_2:1And a second preparation time N_2:2Is dependent on at least one of the following:

a subcarrier spacing value for uplink transmission of a transport block,

the size of the transport block, and

timing capabilities of the client device.

This implementation form has the advantage that the client device implementation can be made less complex, since the first preparation time N_2:1And a second preparation time N_2:2Depending on the parameters mentioned above. Furthermore, since conventional solutions use the same preparation time for the first transmission and retransmission of a transport block, with this implementation and at the same time, a shorter preparation time is possible, suitable for the system configuration. Furthermore, when different processing times are introduced for initial transmission and retransmission only for certain client device capabilities, complexity may be further reduced, since the requirement only applies for certain client devices having strict latency requirements, not for client devices that do not require strict latency requirements.

In an implementation form of the client device according to the first aspect, the first preparation time N is_2:1And a second preparation time N_2:2Expressed in terms of the number of orthogonal frequency division multiplexing symbols.

An advantage of this implementation form is that well-defined preparation timings are defined that are suitable for wireless communication systems using OFDM, such as LTE and NR.

In an implementation form of the client device according to the first aspect, wherein performing the first uplink transmission comprises:

preparing a transport block for a first uplink transmission based on a transmission grant;

the prepared transport blocks are transmitted in an uplink data channel.

The uplink data channel may be a PUSCH in an NR system.

This implementation has the advantage that the data is transmitted in the data channel according to the defined standard for NR, enabling the network access node to receive and decode the prepared transport blocks according to the standard procedure.

In an implementation form of the client device according to the first aspect, the client device is further configured to:

storing a version of a copy of the prepared transport block for the first uplink transmission; and wherein performing the second uplink transmission comprises:

transmitting the stored version of the prepared copy of the transport block in an uplink data channel.

The version may be a redundancy version of the prepared copy of the transport block.

An advantage of this implementation form is that the client device may reduce the retransmission preparation time, since most of the pre-processing for possible retransmissions may be done in advance.

a first time instance T after receiving a transmission grant_2：1Transmitting the transport block; and is

Wherein performing the second uplink transmission comprises:

a second time instance T after receiving a transmission grant_2：2The transport block is transmitted.

An advantage of this implementation form is that the timing of the uplink data transmission is well defined, thereby reducing the complexity of the network access node in decoding the uplink transport blocks.

In an implementation form of the client device according to the first aspect, the first time instance T_2：1Given by:

T_2：1＝max((N_2：1+d_2，1)(2048+144)·κ2^-μ·T_c，d_2，2)

and a second time instance T_2：2Given by:

T_2：2＝max((N_2：2+d_2，1)(2048+144)·κ2^-μ·T_c，d_2，2)

where max is a function of the maximum value, d_2，1For the indicator function, κ is the slot offset, μ is the subcarrier spacing, T_cIs the chip time period (chip time period), and d_2，2Is the switching time.

Maximum function in the formula for a first time instance T_2：1And (N)_2：1+d_2，1)(2048+144)·κ2^-μ·T_cOr d_2，2Is related to the maximum value of; and for a second time instance T_2：2And (N)_2：2+d_2，1)(2048+144)·κ2^-μ·T_cOr d_2，2Is related to the maximum value of (c).

An advantage of this implementation form is that the timing of the uplink data transmission is well defined, thereby reducing the complexity of the network access node in decoding the received transport blocks.

determining whether a transmission grant is associated with an initial transmission or a retransmission of a transport block based on downlink control information received in a downlink control channel.

In an example, this may be indicated in a new data indication field of the DCI.

An advantage of this implementation form is that the client device can determine whether to perform an initial transmission of a transport block or a retransmission of a transport block in a simple manner.

According to a second aspect of the present invention, the above-mentioned and other objects are achieved with a network access node for a wireless communication system, the network access node being configured to:

obtaining a transmission request associated with a downlink transmission of a transport block;

based on the transmission request and a first preparation time N, if the transmission request is associated with an initial transmission of a transport block_2：1To perform a first downlink transmission of a transport block;

based on the transmission request and a second preparation time N, if the transmission request is associated with a retransmission of the transport block_2：2To perform a second downlink transmission of the transport block, wherein a second preparation time N_2：2And a first preparation time N_2：1Different.

Herein, the transmission request for initial transmission may be a request from a higher layer to send data to the client device, and the transmission request for retransmission may be a hybrid automatic repeat request (HARQ) Negative Acknowledgement (NACK) sent from the client device to request retransmission of a transport block.

An advantage of the network access node according to the second aspect is a reduced processing time and limited complexity increase in the network access node. In addition, by reducing the processing time for retransmission of transport blocks, the delay budget for URLLC services can be met.

In an implementation form of the network access node according to the second aspect, the second preparation time N_2:2Shorter than the first preparation time N_2:1。

In an implementation form of the network access node according to the second aspect, the second preparation time N_2:2Is less than the first preparation time N_2:180% of the total.

In an implementation form of the network access node according to the second aspect, the second preparation time N_2:2Is less than the first preparation time N_2:160% of the total.

In an implementation form of the network access node according to the second aspect, the first preparation time N_2:1And a second preparation time N_2:2Is dependent on at least one of the following:

a subcarrier spacing value for downlink transmission of a transport block,

the size of the transport block, and

timing capabilities of network access nodes.

This implementation form has the advantage that the network access node implementation can be made less complex, since the first preparation time N_2:1And a second preparation time N_2:2Depending on the parameters mentioned above. Furthermore, since conventional solutions use the same preparation time for the initial transmission and the retransmission of the transport block, with this implementation and at the same time, with adaptation to the system configuration, shorter preparation times are possible.

In an implementation form of the network access node according to the second aspect, the first preparation time N_2:1And a second preparation time N_2:2Expressed in terms of the number of orthogonal frequency division multiplexing symbols.

An advantage of this implementation form is that a well-defined preparation time is defined that is suitable for wireless communication systems using OFDM, such as LTE and NR.

In an implementation form of the network access node according to the second aspect, wherein performing the first downlink transmission comprises:

preparing a transport block for a first downlink transmission based on the transmission request;

the prepared transport blocks are transmitted in a downlink data channel.

This implementation has the advantage that the transport blocks are transmitted in the data channel according to the defined standard of NR, enabling the network access node to receive and decode the prepared transport blocks according to the standard procedures.

In an implementation form of the network access node according to the second aspect, the network access node is further configured to:

storing a version of a copy of the prepared transport block for the first downlink transmission;

and wherein performing the second downlink transmission comprises:

the stored version of the copy of the prepared transport block is sent in a downlink data channel.

a first time instance T after receiving a transmission request_2:1Transmitting the transport block;

and wherein performing the second downlink transmission comprises:

a second time instance T after receiving the transmission request_2:2The transport block is transmitted.

An advantage of this implementation form is that the timing of the downlink data transmission is well defined, thereby reducing the complexity of the client device in decoding the downlink transport blocks.

In accordance with the secondIn an implementation form of the network access node of the aspect, the first time instance T_2:1Is a first preparation time N_2:1And wherein the second time instance T_2:2Is the second preparation time N_2:2As a function of (c).

An advantage of this implementation form is that different functions can be applied to initial transmission and retransmission and thus a more flexible solution can be provided in the network access node.

According to a third aspect of the present invention, the above-mentioned and other objects are achieved with a method for a client device, comprising:

The method according to the third aspect may be extended to implementation forms corresponding to the implementation forms of the client device according to the first aspect. An implementation form of the method therefore comprises the features of a corresponding implementation form of the client device.

The advantages of the method according to the third aspect are the same as the advantages of the corresponding implementation form of the client device according to the first aspect.

According to a fourth aspect of the present invention, the above mentioned and other objects are achieved with a method for a network access node, the method comprising:

based on the transmission request and a first preparation time N, if the transmission request is associated with an initial transmission of a transport block_2:1To perform a first downlink of transport blocksPath transmission;

based on the transmission request and a second preparation time N, if the transmission request is associated with a retransmission of the transport block_2:2To perform a second downlink transmission of the transport block, wherein a second preparation time N_2:2And a first preparation time N_2:1Different.

The method according to the fourth aspect may be extended to implementations corresponding to the implementations of the network access node according to the second aspect. An implementation form of the method therefore comprises the features of a corresponding implementation form of the network access node.

The advantages of the method according to the fourth aspect are the same as the advantages of the corresponding implementation form of the network access node according to the second aspect.

The invention also relates to a computer program, characterized by program code which, when executed by at least one processor, causes the at least one processor to perform any of the methods according to embodiments of the invention. Furthermore, the invention relates to a computer program product comprising a computer readable medium and said mentioned computer program, wherein said computer program is comprised in the computer readable medium and comprises one or more of the group of: Read-Only Memory (ROM), Programmable ROM (PROM), Erasable PROM (EPROM), flash Memory, Electrically EPROM (EEPROM), and hard disk drives.

Other applications and advantages of embodiments of the present invention will be apparent from the following detailed description.

Drawings

The accompanying drawings are intended to illustrate and describe various embodiments of the present invention, in which:

figure 1 shows a client device according to an embodiment of the invention;

figure 2 shows a method for a client device according to an embodiment of the invention;

figure 3 shows a network access node according to an embodiment of the invention;

figure 4 shows a method for a network access node according to an embodiment of the invention;

figure 5 shows a wireless communication system according to an embodiment of the present invention;

figure 6 shows a timing diagram of control signaling and data transmission of transport blocks in the uplink from a client device to a network access node; and

fig. 7 shows a flow chart of a method according to an embodiment of the invention.

Detailed Description

As previously mentioned, URLLC traffic requires higher reliability and lower latency compared to, for example, enhanced mobile broadband (eMBB) traffic. Therefore, in order to meet the latency requirement of URLLC service, it is necessary to reduce User Equipment (UE) and gNB packet processing time as much as possible. It is also important to meet latency requirements without significantly increasing the complexity and power consumption of modem chipset design in the UE or the gNB. In this regard, the inventors have recognized that one of the most challenging from a latency perspective is the preparation time required for uplink transmission from the reception of an Uplink (UL) grant to a transport block.

Thus, embodiments of the present invention take advantage of the fact that: the client device may prepare the uplink transmission for retransmission of the transport block (when such retransmission is needed). Thus, the uplink preparation time for retransmission of transport blocks may be significantly reduced. Embodiments of the present invention also relate, mutatis mutandis, to corresponding Downlink (DL) transmission and retransmission of transport blocks performed by a network access node.

Fig. 1 shows a client device 100 according to an embodiment of the invention. In the embodiment shown in fig. 1, client device 100 includes a processor 102, a transceiver 104, and a memory 106. Processor 102 is coupled to transceiver 104 and memory 106 by communication means 108 as known in the art. The client device 100 also comprises an antenna or antenna array 10 coupled to the transceiver 104, which means that the client device 100 is configured for wireless communication in a wireless communication system. The configuration of the client device 100 to perform certain actions may be understood in this disclosure to mean that the client device 100 includes suitable means, e.g., including the processor 102 and the transceiver 104, configured to perform the actions.

According to an embodiment of the invention, the client device 100 is configured to receive a transmission grant 502 (see fig. 5) associated with an uplink transmission of a transport block. The client device 100 is further configured to: based on the transmission grant 502 and the first preparation time N, if the transmission grant 502 is associated with an initial transmission of a transport block_2:1To perform a first uplink transmission of the transport block. The client device 100 is further configured to: based on the transmission grant 502 and the second preparation time N, if the transmission grant 502 is associated with a retransmission of a transport block_2:2To perform a second uplink transmission of the transport block. According to an embodiment of the present invention, the second preparation time N_2:2And a first preparation time N_2:1Different.

Fig. 2 shows a flow diagram of a corresponding method 200 that may be performed in a client device 100, such as the client device shown in fig. 1. The method 200 includes receiving 202 a transmission grant 502 associated with uplink transmission of a transport block. The method 200 further comprises: based on the transmission grant 502 and the first preparation time N, if the transmission grant 502 is associated with an initial transmission of a transport block_2:1A first uplink transmission of transport blocks is performed 204. The method 200 further comprises: based on the transmission grant 502 and the second preparation time N, if the transmission grant 502 is associated with a retransmission of a transport block_2:2To perform 206 a second uplink transmission of the transport block. Second preparation time N_2:2And a first preparation time N_2:1Different.

According to an embodiment of the present invention, performing the first uplink transmission includes preparing a transport block for the first uplink transmission (i.e., initial transmission) based on the transmission grant 502, and thereafter transmitting the prepared transport block in an uplink data channel, e.g., PUSCH. During the processing time for the first uplink transmission, the client device 100 also stores a version of the copy of the transport block prepared for the first uplink transmission. Thus, the client device 100 can communicateThe second uplink transmission (i.e., retransmission) is performed by sending a version of the stored copy of the prepared transport block (i.e., a redundancy version of the transport block) in the uplink data channel. Obviously, further retransmissions of the stored copy of the transport block version may be performed. This is to reduce the second preparation time N in the retransmission of the transport block_2:2One mode of (1).

Furthermore, performing the first uplink transmission may mean a first time instance T after receiving the transmission grant 502_2:1Transmitting the transport block; while performing a second uplink transmission may mean a second time instance T after receiving the transmission grant 502_2:2The transport block is transmitted. The details about how the first time instance T may be determined are described in more detail in the following disclosure_2:1And a second time instance T_2:2In a different aspect of (1).

Fig. 3 shows a network access node 300 according to an embodiment of the invention. In the embodiment shown in fig. 3, the network access node 300 includes a processor 302, a transceiver 304, and a memory 306. The processor 302 is coupled to the transceiver 304 and the memory 306 by communication means 308 as is known in the art. The network access node 300 may be configured for both wireless and wired communication in a wireless and wired communication system, respectively. Wireless communication capability is provided using an antenna or antenna array 310 coupled to the transceiver 304, while wired communication capability is provided using a wired communication interface 312 coupled to the transceiver 304. The network access node 300 being configured to perform certain actions may be understood in this disclosure to mean that the network access node 300 comprises suitable means configured to perform said actions, for example comprising a processor 302 and a transceiver 304.

According to an embodiment of the invention, the network access node 300 is configured to obtain a transmission request 504 associated with a downlink transmission of a transport block. The network access node 300 is further configured to: based on the transmission request 504 and the first preparation time N, if the transmission request 504 is associated with an initial transmission of a transport block_2:1To perform a first downlink transmission of the transport block. The network access node 300 is further configured to: if the request 50 is transmitted4 is associated with the retransmission of the transport block, based on the transmission request 504 and the second preparation time N_2:2To perform a second downlink transmission of the transport block. According to an embodiment of the present invention, the second preparation time N_2:2And a first preparation time N_2:1Different.

Fig. 4 shows a flow diagram of a corresponding method 400 that may be performed in a network access node 300, such as the network access node shown in fig. 3. The method 400 includes obtaining 402 a transmission request associated with a downlink transmission of a transport block 504. The method 400 further includes: based on the transmission request 504 and the first preparation time N, if the transmission request 504 is associated with an initial transmission of a transport block_2:1A first downlink transmission of transport blocks is performed 404. The method 400 further includes: based on the transmission request 504 and the second preparation time N, if the transmission request 504 is associated with a retransmission of a transport block_2:2To perform 406 a second downlink transmission of the transport block. Second preparation time N_2:2And a first preparation time N_2:1Different.

Consistent with corresponding embodiments of the client device 100, the network access node 300 may perform the first downlink transmission by preparing a transport block for the first downlink transmission, i.e. the initial transmission, based on the transmission request 504, and thereafter sending the prepared transport block in a downlink data channel, e.g. PDSCH. During the processing time for the first downlink transmission, the network access node 300 stores a version of the copy of the transport block prepared for the first downlink transmission. Thus, the network access node 300 may perform the second downlink transmission, i.e. the retransmission, by sending a redundant version of the stored copy of the prepared transport block in the downlink data channel. Obviously, further retransmissions of the prepared version of the stored copy of the transport block may be performed. As previously described, in a 5G system, the transmission request for initial transmission may be a request from a higher layer to send data to the client device. The transmission request for retransmission may be a hybrid automatic repeat request (HARQ) Negative Acknowledgement (NACK) transmitted from the client device 100 in order to request retransmission of a transport block when reception failure is detected in the CRC check, for example.

Furthermore, the performance of the first downlink transmission by the network access node 300 may mean a first time instance T after receiving the transmission request 504_2:1The transport block is transmitted. Accordingly, performing the second downlink transmission by the network access node 300 may mean a second time instance T after receiving the transmission request 504_2:2The transport block is transmitted. In an embodiment of the invention, the first time instance T is, respectively_2:1Is a first preparation time N_2:1And a second time instance T, and_2:2is the second preparation time N_2:2As a function of (c).

A transport block in this context may be considered as information to be transmitted over a radio channel. Thus, a different encoded version of the transport block, i.e. the redundancy version, is sent in the initial transmission compared to the retransmission of the transport block. A transport block may be generated in a Medium Access Control (MAC) layer by concatenating Radio Link Control (RLC) Packet Data Units (PDUs) from different resource blocks.

Fig. 5 illustrates a wireless communication system 500 according to an embodiment of the present invention. The wireless communication system 500 includes a client device 100 and a network access node 300 configured to operate in the wireless communication system 500. For simplicity, the wireless communication system 500 shown in fig. 5 includes only one client device 100 and one network access node 300. However, the wireless communication system 500 may include any number of client devices 100 and any number of network access nodes 300 without departing from the scope of the present invention.

In the wireless communication system 500, as shown in fig. 5, the client device 100 is configured to perform uplink initial transmission and retransmission of one or more transport blocks 520 to the network access node 300. Accordingly, the network access node 300 is configured to perform downlink initial transmission and retransmission of one or more transport blocks 540 to the client device 100.

Fig. 6 illustrates the overall latency considerations for transport block transmission by describing the communication between the client device 100 and the network access node 300. In fig. 6, an initial transmission of a transport block and one retransmission of the transport block are illustrated. However, within the scope of the invention, more than one retransmission of a transport block may be performed. Furthermore, the communication shown in fig. 6 is conducted in the context of a 3GPP NR system, hence the terminology is used such that the UE corresponds to the client device 100 and the gNB corresponds to the network access node 300. However, the embodiments of the present invention are not limited thereto.

In step I of fig. 6, data or information may be used for uplink transmission at the UE. Therefore, the latency considerations in step I first involve the UE Scheduling Request (SR) processing, i.e. preparing for transmission of the SR and determining when the SR may be transmitted to the gNB. Second, the SR transmission alignment delay is added to the overall delay. The latter delay relates to the fact that the gNB monitors only after the SR in the predefined symbol. Therefore, when the UE has made a decision to send the SR to the gNB, the UE must wait until the next transmission opportunity to send the SR to the gNB.

In step II in fig. 6, the SR duration is shown, and the latency is related to the time it takes to transmit the SR from the UE to the gNB in the PUCCH.

In step III in fig. 6, the first latency consideration involves the gNB SR processing, which is the time it takes to process the SR, decide the PUSCH grant, schedule and encode by the gNB once it has been fully received. The gbb SR processing time may vary significantly depending on the load and implementation of the cell of the gbb. The second latency consideration in step III is PDCCH transmission alignment, which involves the fact that the UE monitors the PDCCH only with respect to predefined symbols. When the gNB makes its scheduling decision, the gNB must wait until the next PDCCH transmission opportunity to send a grant to the UE. Sometimes PDCCH blocking occurs, which means that the gNB must wait until PDCCH blocking is released before sending a grant.

In step IV of fig. 6, the PDCCH duration is shown and the delay is related to the time it takes to send a transmission grant from the gNB to the UE in the PDCCH.

In step V of FIG. 6, upon receiving authorization in the PDCCH, the UE responds to the received subtendgrant for initial transmission by the gNB prepares data information into a transport block. In this step, a first preparation time N for preparing an initial transport block_2:1Contributing to the delay. First preparation time N_2:1Can be seen as the time from the end of PDCCH reception at the UE until the earliest possible time that PUSCH can be transmitted. In the 3GPP NR specification TS38.214, the maximum allowed PUSCH preparation time is specified in terms of OFDM symbols. For active UE cap #2, N2 is a {5,5.5,11} OFDM symbol for a {15,30,60} kHz subcarrier spacing. Another factor contributing to the overall latency in step V is the PUSCH transmission alignment, which is the time between the PUSCH having been assembled, encoded, and ready for transmission. Sometimes, it is assumed that PUSCH may be at first preparation time N_2:1Immediately thereafter, i.e. the time equals zero and does not introduce any additional delay.

In step V, the UE may also store the redundancy version of the copy of the transport block prepared for the initial transmission in a transmission buffer of the UE for possible retransmission of the transport block.

In step VI in fig. 6, the PUSCH duration for the initial transmission of a transport block is shown and is related to the time it takes to send the transport block from the UE to the gNB in the PUSCH.

In step VII in fig. 6, the gNB PUSCH processing must be considered in the overall latency. The gNB PUSCH processing latency is the time it takes for the gNB to process the PUSCH once it is received from the UE. In case of transmission errors, a retransmission grant is scheduled. Thus, the processing time is divided into two components, first the PUSCH decoding, for which the duration of N1 symbols is assumed, i.e. it is assumed to be the same as the PDSCH decoding on the UE side. Second is scheduling for which two values similar to those for PDSCH scheduling are assumed. N1 is a specified maximum UE processing time for PDSCH processing based on UE capability #2 and may be predefined, for example, as defined in 3GPP TS 38.214.

In step VIII in fig. 6, the transmission of a retransmission grant from the gNB to the UE in the PDCCH is shown. The retransmission may be indicated in a dedicated field of DCI included in the PDCCH.

In step IX in fig. 6, upon receiving the PDCCH and the UE determining that retransmission is requested, the UE prepares for retransmission of the transport block previously sent in step VI. In this step, the second preparation time N_2:2Facilitating latency, wherein a second preparation time N according to an embodiment of the invention_2:2Shorter than the first preparation time N_2:1. Second preparation time N_2:2Can be seen as the time from the end of PDCCH reception at the UE until the earliest possible time that PUSCH can be transmitted. The second preparation time N may be achieved by the UE sending a stored version of the copy of the transport block in step V_2:2Shorter than the first preparation time N_2:1. Another factor contributing to the overall delay in step IX is the PUSCH transmission alignment, which is the time between PUSCH has been assembled, encoded, and ready for transmission to the gNB.

In step X of fig. 6, the PUSCH duration for retransmission of a transport block is shown, which is the duration of retransmission of a transport block from UE to gNB in PUSCH.

In step XI in fig. 6, the gNB PUSCH processing must be considered in the overall latency. Typically, the gbb processes the PUSCH and, assuming correct decoding, the decoded data is fed to higher layers for further processing. It should be appreciated that the gNB PUSCH processing must also be considered for the overall delay through the RAN in steps I to XI.

Fig. 7 shows a flow chart of a method 210 according to another embodiment of the invention. The description of this embodiment is also made in the context of 3GPP NR, which means that the UE corresponds to the client device 100 and the gNB corresponds to the network access node 300.

In step 212 in fig. 7, the UE monitors DCI of the PDCCH.

In step 214 in fig. 7, at a first time instance T-T0, the UE detects DCI in the PDCCH. The detected DCI includes an uplink grant determined by the UE. The UL grant typically includes information on time-frequency resources and modulation and coding to be used for uplink data transmission.

In step 216 in fig. 7, the UE obtains information on whether the uplink grant is associated with an initial uplink transmission or a retransmission of the transport block. This information may be obtained from a "new data field indication" in the DCI indicating whether new data or authorized retransmission is possible.

In step 218 in fig. 7, the UE performs preparation of a transport block according to the obtained DCI and transmits the transport block on the PUSCH at a second time instance T0+ x, where time x is a function of a preparation time value, typically expressed in OFDM symbols. If it is an initial transmission of a transport block, a first preparation time value N is used_2:1And if it is a retransmission of the transport block, using a second preparation time value N_2:2。

According to an embodiment of the invention, the first preparation time value N_2:1Greater than a second preparation time value N_2:2I.e. if it is the first transmission, the allowed preparation time is longer than if it is a retransmission of an already transmitted transport block, e.g. due to a failed decoding in the gNB. According to a further embodiment of the invention, the second preparation time N_2:2Shorter than the first preparation time N_2:1So that the second preparation time N_2:2Is less than the first preparation time N_2:1And in some cases less than the first preparation time N_2:160% of the total.

However, in the embodiment of the present invention, the second preparation time N_2:2May alternatively be greater than the first preparation time N_2:1. This may be the case, for example, when a retransmission grant requires a large number of re-encoding of a data block. This may occur when the gbb requires a significantly lower coding rate than first expected to perform reliable retransmissions. Another non-limiting example may be when the gNB configures retransmission on another bandwidth portion or another carrier frequency compared to the initial transmission.

According to a further embodiment of the invention, the first preparation time N_2:1And a second preparation time N_2:2At least one of which depends on the size of the transport block to be transmitted. For example, if a transport block is smaller than a first threshold, i.e. the entire transport block can be assembled in one code block group, the second preparationTime N_2:2The value may be the first preparation time N_2:180% of the value, while if the transport block is large and comprises several code block groups, and only the code block groups are retransmitted, the first preparation time N_2：1And a second preparation time N_2：2The relationship between the values may be different from the first case, for example 60%.

Further, in the embodiment of the present invention, the first preparation time N_2：1And a second preparation time N_2：2Depends on the subcarrier spacing used or configured for uplink transmission, where subcarrier spacing is denoted as μ, which corresponds to a scaling of the reference subcarrier factor, i.e. Δ f ═ 2^μ·15[kHz]Where, μ ═ 0 means that the (reference) subcarrier spacing is 15kHz, and μ ═ 1 means that the subcarrier spacing is 30kHz, and the like. As a non-limiting example, for a 15kHz subcarrier spacing, a first preparation time N_2：1The value may be 5 and the second preparation time N_2：2The value may be 2.5 expressed in OFDM symbols. For a 30kHz subcarrier spacing, a first preparation time N_2：1The value may be 5 and the second preparation time N_2：2The value may be 3 expressed in OFDM symbols.

In a further embodiment of the invention, the first preparation time N_2：1And a second preparation time N_2：2Based on the timing capabilities of the client device 100. Second preparation time N_2：2The values may be used for only certain timing capabilities. Thus, for some client device capabilities, only the first preparation time N_2：1The value applies to first transmission and retransmission, while for other client device capabilities, the first preparation time N_2：1Value for initial transmission, and a second preparation time N_2：2The value is used for retransmission. Timing capabilities are typically the possibility of a client device preparing for uplink transmissions. Since the preparation time is directly related to complexity and processing power, some client device capabilities that do not require low latency may have relaxed timing capabilities, and thus the modem chipset may be less complex and less expensive, while other client devices or modems are designed for low latency applications, andand thus may be more complex and expensive.

It should be appreciated that the first preparation time N_2：1And a second preparation time N_2：2At least one of the above parameters may depend on one or more of the above parameters: a subcarrier spacing value for uplink transmission of a transport block, a size of the transport block, and a timing capability. It is also recognized that the first preparation time N_2：1And a second preparation time N_2：2It may be expressed in the number of OFDM symbols, for example, in LTE and NR using OFDM-based transmission techniques, but may be expressed in time units in other embodiments. Furthermore, a first preparation time N for the network access node 300_2：1And a second preparation time N_2：2It may also depend on one or more of the above parameters: a subcarrier spacing value for uplink transmission of a transport block, a size of the transport block, and a timing capability.

Furthermore, a first preparation time N for the client device 100_2：1And a second preparation time N_2：2It may also depend on or be a function of other parameters, and may be expressed in some embodiments as follows, defined in terms of time after receiving the uplink grant. First uplink symbol in PUSCH allocation of transport block (including by slot offset K)₂And the start of the scheduling DCI and the length indicate the SLIV defined DM-RS and include the effect of timing advance) is no earlier than the symbol L₂Wherein L is₂Defined as the next uplink symbol whose CP starts after the end of the reception of the last symbol of the PDCCH carrying DCI scheduling PUSCH, the UE will transmit a transport block.

Thus, performing the first uplink transmission by the client device 100 includes a first time instance T after receiving the transmission grant 502_2：1To transmit a transport block, wherein a first time instance T_2：1Given by:

T_2：1＝max((N_2：1+d_2，1)(2048+144)·κ2^-μ·T_c，d_2，2) Formula (1)

Where max is a function of the maximum value, N_2：1For the first preparation time, d_2，1For the indicator function, κ is the slot offset, μ is the subcarrier spacing, T_cIs the chip time period, and d_2，2Is the switching time.

Further, performing the second uplink transmission by the client device 100 includes a second time instance T after receiving the transmission grant 502_2：2To transmit a transport block, wherein the second time instance T_2：2Given by:

T_2：2＝max((N_2：2+d_2，1)(2048+144)·κ2^-μ·T_c，d_2，2) Formula (2)

Where max is a function of the maximum value, N_2：2For a second preparation time, d_2，1For the indicator function, κ is the slot offset, μ is the subcarrier spacing, T_cIs the chip time period, and d_2，2Is the switching time.

Maximum function in the formulae according to

formulae

1 and 2 for a first time instance T_2：1And (N)_2：1+d_2，1)(2048+144)·κ2^-μ·T_cOr d_2，2Is related to the maximum value of; and for a second time instance T_2：2And (N)_2：2+d_2，1)(2048+144)·κ2^-μ·T_cOr d_2，2Is related to the maximum value of (c). Naturally, the first preparation time and the second preparation time may be represented herein with the notation used here, i.e. N_2：1And N_2：2Different.

Embodiments of the present invention may be readily implemented in the 3GPP NR specification, e.g., TS38.214 section 6.4. A non-limiting example of the mentioned section 6.4 of TS38.214 is given below, where an exemplary addition to the specification is given in bold italics, i.e. the text "furthermore, for UE processing capability 3, N₂Depending on whether it is the first transmission of a transport block or the retransmission of a transport block. ".

TS38.214 section 6.4, UE PUSCH preparation procedure time:

if the first uplink symbol in the PUSCH allocation of the transport block (including by slot offset K)₂And the start of the scheduling DCI and the length indicate the SLIV defined DM-RS and include the effect of timing advance) is no earlier than the symbol L₂Wherein L is₂Defined as its CP starting T after the end of reception of the last symbol of PDCCH carrying DCI that schedules PUSCH_proc，2＝max((N₂+d_2，1)(2048+144)·κ2^-μ·T_c，d_2，2) The next uplink symbol, the UE will send a transport block.

-N₂Based on μ in tables 6.4-1 and 6.4-2 for UE processing capability 1 and UE processing capability2, respectively, where μ corresponds to the maximum T_proc，2Produced of (mu)_DL，μ_UL) One of, in which_DLSubcarrier spacing corresponding to downlink utilized for transmitting PDCCH carrying DCI for scheduling PUSCH, and μ_ULSubcarrier spacing corresponding to an uplink channel utilized to transmit PUSCH, and κ at [4, TS 38.211]Sub-clause 4.1 of (a). Furthermore, for UE processing capability 3, N₂Depending on whether it is the first transmission of a transport block or the retransmission of a transport block.

-d if the first symbol of the PUSCH allocation only comprises DM-RS_2，1Not more than 0, otherwise d_2，1＝1。

-if the UE is configured with multiple active component carriers, the first uplink symbol in the PUSCH allocation also includes the effect of timing differences between the component carriers as given in [11, TS 38.133 ].

-if scheduling DCI triggers a handover of BWP, d_2，2Equal to e.g. [11, TS 38.133]Switching time defined in (1), otherwise d_2，2＝0。

For a UE supporting Capability2 on a given cell, if the higher layer parameter Capability2-PUSCH-Processing in the PUSCH-Config is configured for the cell and set to enabled (enable), the Processing time according to UE Processing Capability2 is applied,

-if the PUSCH indicated by DCI overlaps with one or more PUCCH channels, multiplexing the transport block according to the procedure in subclause 9.2.5 of [9, TS 38.213], otherwise transmitting the transport block on the PUSCH indicated by DCI.

Otherwise, the UE may ignore the scheduling DCI.

T_proc，2The value of (c) is used in both the case of a normal cyclic prefix and the case of an extended cyclic prefix. In addition, tables 6.4-1 and 6.4-2 in the specification are also given below, which give the PUSCH preparation time for PUSCH timing capability 1 and PUSCH timing capability 2.

Table 6.4-1: PUSCH preparation time for PUSCH timing capability 1.

Tables 6.4-2: PUSCH preparation time for PUSCH timing capability 2.

μ	PUSCH preparation time N₂[ symbol]
		0	5
1	5.5
		2	11 for frequency range 1

However, two more tables may be introduced into the specification, which are labeled 6.4-3 and 6.4-3 below, and which conform to the general principles of embodiments of the present invention. These tables give the PUSCH preparation time for initial transmission and retransmission.

Tables 6.4-3: for PUSCH timing capability 3 PUSCH preparation time for initial transmission of a transport block.

μ	PUSCH preparation time N₂[ symbol]
		0	5
1	5.5
		2	11 for frequency range 1

Tables 6.4-4: for PUSCH timing capability 3 PUSCH preparation time for retransmission of transport block.

μ	PUSCH preparation time N₂[ symbol]
		0	2.5
1	3
		2	For a frequency range 1 of 6

The general principles described and illustrated previously may also be applied to retransmission of one or more transport blocks in the case of an unlicensed transmission, according to embodiments of the present invention. In such embodiments, the initial transmission of the transport block occurs at a preconfigured time instance, however, as in the grant-based case, the retransmission of the transport block is scheduled via DCI. Thus, in case an unlicensed transmission is configured, based on the second preparation time value N_2:2To perform timing of retransmission of the transport block.

The client device 100 herein, which may be represented as a User Equipment (UE), a mobile station, an internet of things (IoT) device, a sensor device, a wireless terminal, and/or a mobile terminal, is capable of communicating wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. A UE may also be referred to as a mobile phone, a cellular phone, a tablet computer, or a laptop computer with wireless capabilities. A UE in this context may be, for example, a portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile device capable of communicating voice and/or data with another entity (e.g., another receiver or server) via a radio access network. The UE may be a Station (STA), which is any device that contains IEEE 802.11 compliant Medium Access Control (MAC) and Physical Layer (PHY) interfaces to the Wireless Medium (WM). The UE may also be configured for communication in LTE and LTE-advanced related to 3GPP, in WiMAX and its evolution, and in fifth generation wireless technologies (e.g., New Radio).

The network access node 300 herein may also be denoted as a Radio network access node, access point or Base Station (e.g., Radio Base Station (RBS)), which in some networks may be referred to as a transmitter, "gNB", "gnnodeb", "eNB", "eNodeB", "NodeB" or "B node", depending on the technology and terminology used. Based on the transmission power and thus also on the cell size, the radio network access nodes may have different categories, e.g. macro eNodeB, home eNodeB or pico base station. A radio network Access node may be a Station (STA), which is any device that contains IEEE 802.11 compliant Medium Access Control (MAC) and Physical Layer (PHY) interfaces to the Wireless Medium (WM). The radio network access node may also be a base station corresponding to a fifth generation (5G) wireless system.

Furthermore, any method according to embodiments of the present invention may be implemented in a computer program having code means which, when run by processing means, causes the processing means to perform the steps of the method. The computer program is embodied in a computer readable medium of a computer program product. The computer-readable medium may include substantially any Memory, such as a Read-Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable PROM (EPROM), a flash Memory, an Electrically Erasable PROM (EEPROM), or a hard disk drive.

Furthermore, the skilled person realizes that embodiments of the client device 100 and the network access node 300 comprise necessary communication capabilities in the form of e.g. functions, means, units, elements, etc. for performing the solution. Examples of other such devices, units, elements and functions are processors, memories, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multiplexers, decision units, selection units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, MSDs, TCM encoders, TCM decoders, power supply units, power feeders, communication interfaces, communication protocols, etc. suitably arranged together to perform a solution.

In particular, the processors of the client device 100 and the network access node 300 may comprise, for example, one or more of the following: a Central Processing Unit (CPU), a Processing Unit, a Processing Circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other Processing logic that may interpret and execute instructions. Thus, the expression "processor" may denote a processing circuit comprising a plurality of processing circuits, such as any, some or all of those mentioned above. The processing circuitry may also perform data processing functions including data buffering for inputting, outputting and processing data, and device control functions such as call processing control, user interface control, etc.

Finally, it is to be understood that the invention is not limited to the embodiments described above, but also relates to and encompasses all embodiments within the scope of the appended independent claims.

Claims

1. A client device (100) for a wireless communication system (500), the client device (100) being configured to:

receiving a transmission grant associated with an uplink transmission of a transport block (502);

based on the transmission grant (502) and a first preparation time N, if the transmission grant (502) is associated with an initial transmission of the transport block_2:1To perform a first uplink transmission of the transport block;

based on the transmission grant (502) and a second preparation time N, if the transmission grant (502) is associated with a retransmission of the transport block_2:2To perform a second uplink transmission of the transport block, wherein the second preparation time N_2:2And the first preparation time N_2:1Different.

2. The client device (100) of claim 1, wherein the second preparation time N_2:2Is shorter than the first preparation time N_2:1。

3. The client device (100) of claim 2, wherein the second preparation time N_2:2Less than the first preparation time N_2:180% of the total.

4. The client device (100) of claim 3, wherein the second preparation time N_2:2Less than the first preparation time N_2:160% of the total.

5. The client device (100) according to any one of the preceding claims, wherein the first preparation time N_2:1And the second preparation time N_2:2Is dependent on at least one of the following:

a subcarrier spacing value for the uplink transmission of the transport block,

the size of the transport block, an

Timing capabilities of the client device (100).

6. The client device (100) according to any one of the preceding claims, wherein the first preparation time N_2:1And the second preparation time N_2:2Expressed in terms of the number of orthogonal frequency division multiplexing symbols.

7. The client device (100) of any one of the preceding claims, wherein performing the first uplink transmission comprises:

preparing the transport block for the first uplink transmission based on the transmission grant (502);

the prepared transport blocks are transmitted in an uplink data channel.

8. The client device (100) of claim 7, configured to:

transmitting the stored version of the prepared copy of the transport block in the uplink data channel.

9. The client device (100) of any one of the preceding claims, wherein performing the first uplink transmission comprises:

a first time instance T after receiving the transmission grant (502)_2:1Transmitting the transport block; and is

Wherein performing the second uplink transmission comprises:

a second time instance T after receiving the transmission grant (502)_2:2The transport block is transmitted.

10. The client device (100) of claim 9, wherein the first time instance T_2:1Given by:

T_2:1＝max((N_2:1+d_2,1)(2048+144).κ2^-μ·T_c,d_2,2)

and wherein said second time instance T_2:2Given by:

T_2:2＝max((N_2:2+d_2,7)(2048+144).κ2-^μ·T_c,d_2，2)

where max is a function of the maximum value, d_2,1For the indicator function, κ is the slot offset, μ is the subcarrier spacing, T_cIs the chip time period, and d_2,2Is the switching time.

11. A network access node (300) for a wireless communication system (500), the network access node (300) being configured to:

obtaining a transmission request (504) associated with a downlink transmission of a transport block;

based on the transmission request (504) and a first preparation time N, if the transmission request (504) is associated with an initial transmission of the transport block_2:1To executeA first downlink transmission of the transport block;

if the transmission request (504) is associated with a retransmission of the transport block, based on the transmission request (504) and a second preparation time N_2:2To perform a second downlink transmission of the transport block, wherein the second preparation time N_2:2And the first preparation time N_2:1Different.

12. The network access node (300) of claim 11, wherein the second preparation time N_2:2Is shorter than the first preparation time N_2:1。

13. The network access node (300) of claim 12, wherein the second preparation time N_2:2Less than the first preparation time N_2:180% of the total.

14. The network access node (300) of claim 13, wherein the second preparation time N_2:2Less than the first preparation time N_2:160% of the total.

15. The network access node (300) of any of claims 11-14, wherein the first preparation time N_2:1And the second preparation time N_2:2Is dependent on at least one of the following:

a subcarrier spacing value for the downlink transmission of the transport block,

the size of the transport block, an

Timing capabilities of the network access node (300).

16. The network access node (300) of any of claims 11-15, wherein the first preparation time N_2:1And the second preparation time N_2:2Expressed in terms of the number of orthogonal frequency division multiplexing symbols.

17. The network access node (300) of any of claims 11-16, wherein performing the first downlink transmission comprises:

preparing the transport block for the first downlink transmission based on the transmission request (504);

the prepared transport blocks are transmitted in a downlink data channel.

18. The network access node (300) of claim 17, configured to:

and wherein performing the second downlink transmission comprises:

transmitting the stored version of the prepared copy of the transport block in the downlink data channel.

19. The network access node (300) of any of claims 11-18, wherein performing the first downlink transmission comprises:

a first time instance T after receiving the transmission request (504)_2:1Transmitting the transport block;

and wherein performing the second downlink transmission comprises:

a second time instance T after receiving the transmission request (504)_2:2The transport block is transmitted.

20. A method (200) for a client device (100), the method (200) comprising:

receiving (202) a transmission grant (502) associated with an uplink transmission of a transport block;

based on the transmission grant (502) and a first preparation time N, if the transmission grant (502) is associated with an initial transmission of the transport block_2:1To perform (204) a first uplink transmission of the transport block;

if the transmission grant (502) is associated with a retransmission of the transport block,based on the transmission grant (502) and a second preparation time N_2:2To perform (206) a second uplink transmission of the transport block, wherein the second preparation time N_2:2And the first preparation time N_2:1Different.

21. A method (400) for a network access node (300), the method (400) comprising:

obtaining (402) a transmission request (504) associated with a downlink transmission of a transport block;

based on the transmission request (504) and a first preparation time N, if the transmission request (504) is associated with an initial transmission of the transport block_2:1To perform (404) a first downlink transmission of the transport block;

if the transmission request (504) is associated with a retransmission of the transport block, based on the transmission request (504) and a second preparation time N_2:2To perform (406) a second downlink transmission of the transport block, wherein the second preparation time N_2:2And the first preparation time N_2:1Different.

22. Computer program having a program code for performing the method according to claim 20 or 21, when the computer program runs on a computer.