Method And Apparatus For Hybrid Automatic Repeat Request Design In Non-Terrestrial Network Communications

Various solutions for hybrid automatic repeat request (HARQ) design in non-terrestrial network (NTN) communications with respect to user equipment and network apparatus in mobile communications are described. An apparatus may determine a maximum number of HARQ processes that the apparatus can support. The apparatus may transmit a capability report to indicate the maximum number of HARQ processes. The apparatus may perform HARQ process transmissions based on the maximum number of HARQ processes.

TECHNICAL FIELD

The present disclosure is generally related to mobile communications and, more particularly, to hybrid automatic repeat request (HARQ) design in non-terrestrial network (NTN) communications with respect to user equipment and network apparatus in mobile communications.

BACKGROUND

A non-terrestrial network (NTN) refers to a network, or a segment of network(s), using radio frequency (RF) resources on board a satellite or an unmanned aircraft system (UAS) platform. A typical scenario of an NTN providing access to a user equipment (UE) involves either NTN transparent payload, with the satellite or UAS platform acting as a relay, or NTN regenerative payload, with a base station (e.g., gNB) on board the satellite or UAS platform.

In Long-Term Evolution (LTE) or New Radio (NR), hybrid automatic repeat request (HARQ) procedure is introduced to improve transmission reliability. The user equipment (UE) needs to report HARQ-acknowledgement (HARQ-ACK) information for corresponding downlink transmissions in a HARQ-ACK codebook. The HARQ procedure may involve a plurality of HARQ processes (e.g., 8 HARQ processes). Each downlink transmission may associate with one HARQ process identifier (ID). The HARQ process ID is used to identify a unique HARQ process. The same HARQ process ID can be used to identify a re-transmission of data. This can enable the UE to make use of the repeated transmission for soft combining. To perform soft combining, incorrectly received coded data blocks are often stored at the receiver (e.g., stored in the soft buffer) rather than discarded, and when the re-transmitted block is received, the two blocks are combined. The soft buffer may be implemented as buffers or memories for storing the soft combining data.

In NTN communications, the long propagation delay is expected and leads to very long HARQ round trip time (RTTHARQ). The HARQ RTT is time interval between initial transmission and retransmission. If the HARQ RTT increases, the quality of service (QoS) requirement of the retransmitted packet would not be satisfied by increased end-to-end latency. Thus, these very long HARQ RTT times in NTN communications lead to an increase in the minimum number of required HARQ processes. This represent a challenge since the NR terrestrial network only allows for 16 HARQ processes. Increasing the number of HARQ processes may lead to higher soft buffer requirements leading to higher UE implementation complexity and cost.

Accordingly, for the long HARQ round trip time in NTN communications, how to design/support HARQ processes without increasing the soft buffer of the UE becomes an important issue in the newly developed wireless communication network. Therefore, there is a need to provide proper schemes to perform HARQ process transmissions without increasing UE implementation complexity and cost.

SUMMARY

An objective of the present disclosure is to propose solutions or schemes that address the aforementioned issues pertaining to HARQ design in NTN communications with respect to user equipment and network apparatus in mobile communications.

In one aspect, a method may involve an apparatus determining a maximum number of HARQ processes that the apparatus can support. The method may also involve the apparatus transmitting a capability report to indicate the maximum number of HARQ processes. The method may further involve the apparatus performing HARQ process transmissions based on the maximum number of HARQ processes.

In one aspect, a method may involve an apparatus receiving a capability report from a UE. The method may also involve the apparatus determining a maximum number of HARQ processes that the UE can support according to the capability report. The method may further involve the apparatus performing HARQ process transmissions based on the maximum number of HARQ processes.

It is noteworthy that, although description provided herein may be in the context of certain radio access technologies, networks and network topologies such as Long-Term Evolution (LTE), LTE-Advanced, LTE-Advanced Pro, 5th Generation (5G), New Radio (NR), Internet-of-Things (IoT), Narrow Band Internet of Things (NB-IoT) and Industrial Internet of Things (IIoT), the proposed concepts, schemes and any variation(s)/derivative(s) thereof may be implemented in, for and by other types of radio access technologies, networks and network topologies. Thus, the scope of the present disclosure is not limited to the examples described herein.

DETAILED DESCRIPTION OF PREFERRED IMPLEMENTATIONS

Overview

In NTN communications, the long propagation delay is expected and leads to very long HARQ round trip time (RTTHARQ). The HARQ RTT is time interval between initial transmission and retransmission.FIG. 1illustrates an example table100showing RTT requirements for different communication distances. For terrestrial communications, the maximum RTTHARQmay be 16 milliseconds (ms), and the minimum number of HARQ processes (NHARQ,min) required for 1 ms slot operation may be 16. For low earth orbit (LEO) communications, the maximum RTTHARQmay be 50 ms, and the NHARQ,minrequired for 1 ms slot operation may be 50. For medium earth orbit (MEO) communications, the maximum RTTHARQmay be 180 ms, and the NHARQ,minrequired for 1 ms slot operation may be 180. For geosynchronous equatorial orbit (GEO)/highly elliptical orbit (HEO) communications, the maximum RTTHARQmay be 600 ms, and the NHARQ,minrequired for 1 ms slot operation may be 600.

If the HARQ RTT increases, the quality of service (QoS) requirement of the retransmitted packet would not be satisfied by increased end-to-end latency. Thus, these very long HARQ RTT times in NTN communications lead to an increase in the minimum number of required HARQ processes. This represent a challenge since the NR terrestrial network only allows for 16 HARQ processes. Increasing the number of HARQ processes may lead to higher soft buffer requirements leading to higher UE implementation complexity and cost. However, different implementations may provide different flexibilities and soft buffer requirement. Some UEs may be able to support a much larger number of HARQ processes than 16. Given that for NTN bandwidth, number of spatial layers and number carrier are smaller than those typically use for NR terrestrial network (NR-TN). The UE may be able to re-use the same NR-TN soft buffer to support a higher number of HARQ processes for NTN without increasing the soft buffer.

In view of the above, the present disclosure proposes a number of schemes pertaining to HARQ design in NTN communications with respect to the UE and the network apparatus. According to the schemes of the present disclosure, the UE may be able to signal a maximum number of HARQ processes it can support without increasing its soft buffer as a capability. Then, the network node may determine the maximum number of HARQ processes it can configure for the UE and perform HARQ transmissions based on the supported maximum number of HARQ processes. On the other hand, the network node may also configure two HARQ process pools to the UE. HARQ process pool 1 may be configured to support soft combining and HARQ process pool 2 may be configured without supporting soft combining. Accordingly, the UE only need to meet the HARQ soft combining performance only for pool 1 and don't need to meet the soft combining performance for pool 2. The complexity, cost and requirements on UE design and implementation may be relaxed and may have more flexibility.

Specifically, the UE may be configured to determine a maximum number of HARQ processes it can support. The UE may determine the maximum number of HARQ processes supported under the condition of using the same soft buffer as NR-TN without increasing the soft buffer. The maximum number of HARQ processes may comprise at least one of the HARQ processes UE can support with soft combining and the HARQ processes UE can support without soft combining. The UE may be configured to transmit a capability report to indicate the maximum number of HARQ processes to a network node of the NTN. Then, the UE may perform HARQ process transmissions based on the maximum number of HARQ processes.

The UE may explicitly signalling the maximum number of HARQ process supported to the network node. For example, the UE may transmit the capability report associated with at least one of a maximum number of resource block (RB), a maximum number of spatial layers, and a maximum number of transport block size (TBS). Alternatively, the UE may implicitly signal its capability in the capability report such as at least one of an unlimited number of HARQ processes, a specified maximum number of HARQ processes, and no increase in the maximum number of HARQ processes at all with respect to NR-TN. The signalling may be restricted to the downlink only or supported for uplink as well.

At the network side, the network node may be configured to receive the capability report from the UE. The network node may determine the maximum number of HARQ processes that the UE can support according to the capability report. For example, the network node may determine the maximum number of HARQ processes according to the explicitly signalling of maximum number of HARQ process supported by the UE. The network node may also determine the maximum number of HARQ processes according to at least one of a maximum number of RB, a maximum number of spatial layers, and a maximum number of TBS. The network node may further determine the maximum number of HARQ processes according to at least one of an unlimited number of HARQ processes, a specified maximum number of HARQ processes, and no increase in the maximum number of HARQ processes at all with respect to NR-TN signaled from the UE. Then, the network node may perform HARQ process transmissions based on the maximum number of HARQ processes.

In some implementations, the network node (e.g., gNB) may assume that the UE can support any number of HARQ processes that does not increase the soft buffer size beyond NR-TN. The network node may also determine the maximum number of HARQ process that the UE can support according to some scaling factors. For example, the network node may derive the maximum number of HARQ process according to a formula of floor (16×(maximum number of RB NR-TN)/(maximum number of RB NTN)×(maximum number of layers NR-TN)/(maximum number of layers NTN)). In another example, the scaling for number carrier components that can be supported for NR-TN/NTN may also be added to the formula. Other scaling such as the one corresponding to the modulation and/or coding rate may as well be added to the formula.

In some implementations, the network node may determine the maximum number of HARQ processes according to a ratio of a maximum number of RB in NR-TN to a maximum number of RB in NR-NTN. The NR-TN maximum number of RB in NR-TN may be, for example, 100 MHz. The available RB for NR-NTN may be limited to 20-30 MHz. The network node may determine the maximum number of HARQ processes according to a ratio of a maximum number of spatial layers in NR-TN to a maximum number of spatial layers in NR-NTN. The maximum number of spatial layers in NR-TN may depend on the UE implementation. The maximum number of spatial layers in NR-NTN may comprise only one spatial layer. The network node may determine the maximum number of HARQ processes according to a scaling of number of carrier components that can be supported in NR-TN and NR-NTN. The network node may determine the maximum number of HARQ processes according to a scaling of modulation and coding rate used in NR-TN and NR-NTN.

On the other hand, the UE may signal whether it supports the scaling of the number of HARQ processes along with details on how to do the scaling. The UE may be configured to transmit an indication to indicate whether a scaling of maximum number of HARQ processes is supported. The indication may be comprised in the capability report. The scaling may be restricted to the downlink only or supported for uplink as well.

In some implementations, the number of HARQ processes for NR-NTN does not increase the soft buffer size requirement beyond the NR-TN soft buffer size. This condition may be based on a reference calculation for the soft buffer size using reference configurations for NR-NTN/NT including, for example and without excluding other parameters, the number of RB, number of layers, constellation, coding rate or overhead.

In some implementations, to support configuration of a number of HARQ processes greater than 16, the network node or the UE may be configured to determine the number of downlink control information (DCI) bits used for signalling HARQ identification (ID) (e.g., uplink or downlink) by a formula of Number_bits=max (4, ceiling (log2(number of HARQ processes configured on the link))), where the link may be either downlink or uplink. The network node or the UE may determine the number of DCI bits used to signal the HARQ process ID according to the maximum number of HARQ processes supported.

To cover the RTT, the network node may need to configure the UE with a number of HARQ processes more than what the UE can perform soft combining for. The proposal is that the UE may be able to support two kinds of HARQ processes pools.FIG. 2illustrates an example scenario200under schemes in accordance with implementations of the present disclosure. Scenario200involves a UE and a network node, which may be a part of a wireless communication network (e.g., an LTE network, an LTE-Advanced network, an LTE-Advanced Pro network, a 5G network, an NR network, an IoT network, an NB-IoT network or an IIoT network). The network node may configure a first HARQ process pool (e.g., pool 1) and a second HARQ process pool (e.g., pool 2) to the UE. The UE may be configured to determine the first HARQ process pool and the second HARQ process pool. The first HARQ process pool may comprise HARQ process ID (PID) 0 to N1which may be configured for HARQ processes with soft combining requirements. The second HARQ process pool may comprise HARQ process PID N1+1 to N which may be configured for HARQ processes without soft combining requirements. Then, the network node and/or the UE may perform the HARQ process transmissions with soft combining with respect to the first HARQ process pool and perform the HARQ process transmissions without soft combining with respect to the second HARQ process pool. Accordingly, the UE may need to meet the HARQ soft combining performance only for the first HARQ process pool. The UE may store past soft combined data to perform soft combining with future receptions only for the first HARQ process pool. This is not required for the second HARQ process pool. The UE may still send acknowledgement (ACK)/negative-ACK (NACK) report but it is not required to meet the soft combining performance for the second HARQ process pool.

For the second HARQ process pool, since no soft combining will be performed, the expected redundancy version (RV) that the UE expect to receive may be restricted to ensure that the transmissions/re-transmissions are self-decodable. This may be implemented by a restriction on the redundancy version. For example, either rv0 or rv2 independently of the coding rate may be used for the second HARQ process pool. Alternatively, the UE may expect the combination of the redundancy version and the coding to be self-decodable. Thus, the network node may be restricted to transmit a specific redundancy version of downlink data to the UE with respect to the second HARQ process pool. The UE may expect to receive a specific redundancy version of downlink data with respect to the second HARQ process pool and decode the downlink data based on the specific redundancy version. The specific redundancy version should be self-decodable. In addition, the new data indicator (NDI) may still be used for the second HARQ process pool to differentiate between an initial transmission and a retransmission.

To differentiate between the first HARQ process pool and the second HARQ process pool processes, several approaches may be possible. For example, the network node may transmit an explicit signalling (e.g., an explicit indication) to the UE to differentiate the first HARQ process pool and the second HARQ process pool. The UE may receive the indication to differentiate the first HARQ process pool and the second HARQ process pool. Alternatively, an implicit signalling may be used to differentiate the first HARQ process pool and the second HARQ process pool. The network node may configure a number of HARQ processes which is greater than the maximum number of HARQ processes that the UE can support with soft combining. For example, the network node may configure a number of HARQ processes (e.g., N_HARQ_processes) more than what the UE can support with soft combining (e.g., N1_HARQ_processes_soft_combining). After receiving such configuration, the UE may determine that HARQ processes 1 to N1_HARQ_processes_soft_combining should corresponds to the first HARQ process pool and HARQ processes N1_HARQ_processes_soft_combining+1 to N_HARQ_processes corresponds to the second HARQ process pool. The value of N1_HARQ_processes_soft_combining may be either signalled by the UE or may be evaluated by scaling of soft buffer as described above.

In some implementations, for the second HARQ process pool, the re-transmission with the same NDI (e.g., no toggling of the NDI) may be allowed to achieve lower block error rate (BLER). The re-transmissions may be performed by using different resource allocation and/or modulation and coding scheme (MCS). The restriction on the TBS to be the same in the re-transmissions may be removed for the HARQ processes in the second HARQ

process pool. The network node scheduler may re-transmit one or several media access control (MAC) protocol data units (PDUs) from one or several radio link control (RLC) packets in a larger TBS mapped to one HARQ process ID in the second HARQ process pool. This may be used to overcome shortage of HARQ process IDs. In addition, the differentiation between HARQ process pools may be made visible at the RLC layer or the MAC layer to ensure that each RLC service data unit (SDU) is only transmitted using one pool for the corresponding MAC PDU.

Illustrative Implementations

FIG. 3illustrates an example communication apparatus310and an example network apparatus320in accordance with an implementation of the present disclosure. Each of communication apparatus310and network apparatus320may perform various functions to implement schemes, techniques, processes and methods described herein pertaining to HARQ design in NTN communications with respect to user equipment and network apparatus in wireless communications, including scenarios/schemes described above as well as processes 400 and 500 described below.

Communication apparatus310may be a part of an electronic apparatus, which may be a UE such as a portable or mobile apparatus, a wearable apparatus, a wireless communication apparatus or a computing apparatus. For instance, communication apparatus310may be implemented in a smartphone, a smartwatch, a personal digital assistant, a digital camera, or a computing equipment such as a tablet computer, a laptop computer or a notebook computer. Communication apparatus310may also be a part of a machine type apparatus, which may be an IoT, NB-IoT, or IIoT apparatus such as an immobile or a stationary apparatus, a home apparatus, a wire communication apparatus or a computing apparatus. For instance, communication apparatus310may be implemented in a smart thermostat, a smart fridge, a smart door lock, a wireless speaker or a home control center. Alternatively, communication apparatus310may be implemented in the form of one or more integrated-circuit (IC) chips such as, for example and without limitation, one or more single-core processors, one or more multi-core processors, one or more reduced-instruction set computing (RISC) processors, or one or more complex-instruction-set-computing (CISC) processors. Communication apparatus310may include at least some of those components shown inFIG. 3such as a processor312, for example. Communication apparatus310may further include one or more other components not pertinent to the proposed scheme of the present disclosure (e.g., internal power supply, display device and/or user interface device), and, thus, such component(s) of communication apparatus310are neither shown inFIG. 3nor described below in the interest of simplicity and brevity.

Network apparatus320may be a part of an electronic apparatus, which may be a network node such as a base station, a small cell, a router or a gateway. For instance, network apparatus320may be implemented in an eNodeB in an LTE, LTE-Advanced or LTE-Advanced Pro network or in a gNB in a 5G, NR, IoT, NB-IoT or IIoT network. Alternatively, network apparatus320may be implemented in the form of one or more IC chips such as, for example and without limitation, one or more single-core processors, one or more multi-core processors, or one or more RISC or CISC processors. Network apparatus320may include at least some of those components shown inFIG. 3such as a processor322, for example. Network apparatus320may further include one or more other components not pertinent to the proposed scheme of the present disclosure (e.g., internal power supply, display device and/or user interface device), and, thus, such component(s) of network apparatus320are neither shown inFIG. 3nor described below in the interest of simplicity and brevity.

In some implementations, communication apparatus310may also include a transceiver316coupled to processor312and capable of wirelessly transmitting and receiving data. In some implementations, communication apparatus310may further include a memory314coupled to processor312and capable of being accessed by processor312and storing data therein. In some implementations, network apparatus320may also include a transceiver326coupled to processor322and capable of wirelessly transmitting and receiving data. In some implementations, network apparatus320may further include a memory324coupled to processor322and capable of being accessed by processor322and storing data therein. Accordingly, communication apparatus310and network apparatus320may wirelessly communicate with each other via transceiver316and transceiver326, respectively. To aid better understanding, the following description of the operations, functionalities and capabilities of each of communication apparatus310and network apparatus320is provided in the context of a mobile communication environment in which communication apparatus310is implemented in or as a communication apparatus or a UE and network apparatus320is implemented in or as a network node of a communication network.

In some implementations, processor312may be configured to determine a maximum number of HARQ processes it can support. Processor312may determine the maximum number of HARQ processes supported under the condition of using the same soft buffer as NR-TN without increasing the soft buffer. The maximum number of HARQ processes may comprise at least one of the HARQ processes processor312can support with soft combining and the HARQ processes processor312can support without soft combining.

Processor312may be configured to transmit, via transceiver316, a capability report to indicate the maximum number of HARQ processes to network apparatus320. Then, processor312may perform, via transceiver316, HARQ process transmissions based on the maximum number of HARQ processes.

In some implementations, processor312may explicitly signalling the maximum number of HARQ process supported the network apparatus320. For example, processor312may transmit, via transceiver316, the capability report associated with at least one of a maximum number of RB, a maximum number of spatial layers, and a maximum number of TBS. Alternatively, processor312may implicitly signal its capability in the capability report such as at least one of an unlimited number of HARQ processes, a specified maximum number of HARQ processes, and no increase in the maximum number of HARQ processes at all with respect to NR-TN.

In some implementations, processor322may be configured to receive, via transceiver326, the capability report from communication apparatus310. Processor322may determine the maximum number of HARQ processes that communication apparatus310can support according to the capability report. For example, processor322may determine the maximum number of HARQ processes according to the explicitly signalling of maximum number of HARQ process supported by communication apparatus310. Processor322may also determine the maximum number of HARQ processes according to at least one of a maximum number of RB, a maximum number of spatial layers, and a maximum number of TBS. Processor322may further determine the maximum number of HARQ processes according to at least one of an unlimited number of HARQ processes, a specified maximum number of HARQ processes, and no increase in the maximum number of HARQ processes at all with respect to NR-TN signaled from communication apparatus310. Then, processor322may perform HARQ process transmissions based on the maximum number of HARQ processes.

In some implementations, processor322may assume that communication apparatus310can support any number of HARQ processes that does not increase the soft buffer size beyond NR-TN. Processor322may also determine the maximum number of HARQ process that communication apparatus310can support according to some scaling factors. For example, processor322may derive the maximum number of HARQ process according to a formula of floor (16×(maximum number of RB NR-TN)/(maximum number of RB NTN)×(maximum number of layers NR-TN)/(maximum number of layers NTN)). In another example, processor322may derive the maximum number of HARQ process according to the scaling for number carrier components that can be supported for NR-TN/NTN. Processor322may also derive the maximum number of HARQ process according to other scaling such as the one corresponding to the modulation and/or coding rate.

In some implementations, processor322may determine the maximum number of HARQ processes according to a ratio of a maximum number of RB in NR-TN to a maximum number of RB in NR-NTN. Processor322may determine the maximum number of HARQ processes according to a ratio of a maximum number of spatial layers in NR-TN to a maximum number of spatial layers in NR-NTN. Processor322may determine the maximum number of HARQ processes according to a scaling of number of carrier components that can be supported in NR-TN and NR-NTN. Processor322may determine the maximum number of HARQ processes according to a scaling of modulation and coding rate used in NR-TN and NR-NTN.

In some implementations, processor312may signal whether it supports the scaling of the number of HARQ processes along with details on how to do the scaling. Processor312may be configured to transmit, via transceiver316, an indication to indicate whether a scaling of maximum number of HARQ processes is supported. Processor312may the indication in the capability report.

In some implementations, processor312may determine the number of HARQ processes for NR-NTN without increasing the soft buffer size requirement beyond the NR-TN soft buffer size.

In some implementations, processor312and/or processor322may be configured to determine the number of DCI bits used for signalling HARQ ID (e.g., uplink or downlink) by a formula of Number_bits=max (4, ceiling (log2(number of HARQ processes configured on the link))), where the link may be either downlink or uplink. Processor312and/or processor322may determine the number of DCI bits used to signal the HARQ process ID according to the maximum number of HARQ processes supported.

In some implementations, processor322may configure communication apparatus310with a number of HARQ processes more than what communication apparatus310can perform soft combining for. Processor312may be able to support two kinds of HARQ processes pools. Processor322may configure a first HARQ process pool and a second HARQ process pool to processor312. Processor312may be configured to determine the first HARQ process pool and the second HARQ process pool. Then, processor312and/or processor322may perform the HARQ process transmissions with soft combining with respect to the first HARQ process pool and perform the HARQ process transmissions without soft combining with respect to the second HARQ process pool. Accordingly, processor312may need to meet the HARQ soft combining performance only for the first HARQ process pool. Processor312may store past soft combined data to perform soft combining with future receptions only for the first HARQ process pool. This is not required for the second HARQ process pool. Processor312may still send ACK/NACK report but it is not required to meet the soft combining performance for the second HARQ process pool.

In some implementations, processor322may be restricted to transmit, via transceiver326, a specific redundancy version of downlink data to communication apparatus310with respect to the second HARQ process pool. Processor312may expect to receive, via transceiver316, a specific redundancy version of downlink data with respect to the second HARQ process pool and decode the downlink data based on the specific redundancy version. In addition, processor322may still use the NDI for the second HARQ process pool to differentiate between an initial transmission and a retransmission.

In some implementations, processor322may transmit, via transceiver326, an explicit signalling to communication apparatus310to differentiate the first HARQ process pool and the second HARQ process pool. Processor312may receive, via transceiver316, the indication to differentiate the first HARQ process pool and the second HARQ process pool. Alternatively, processor312and/or processor322may use an implicit signalling to differentiate the first HARQ process pool and the second HARQ process pool. Processor322may configure a number of HARQ processes which is greater than the maximum number of HARQ processes that processor312can support with soft combining.

Illustrative Processes

FIG. 4illustrates an example process400in accordance with an implementation of the present disclosure. Process400may be an example implementation of above scenarios/schemes, whether partially or completely, with respect to HARQ design in NTN communications with the present disclosure. Process400may represent an aspect of implementation of features of communication apparatus310. Process400may include one or more operations, actions, or functions as illustrated by one or more of blocks410,420and430. Although illustrated as discrete blocks, various blocks of process400may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation. Moreover, the blocks of process400may executed in the order shown inFIG. 4or, alternatively, in a different order. Process400may be implemented by communication apparatus310or any suitable UE or machine type devices. Solely for illustrative purposes and without limitation, process400is described below in the context of communication apparatus310. Process400may begin at block410.

At410, process400may involve processor312of apparatus310determining a maximum number of HARQ processes that the apparatus can support. Process400may proceed from410to420.

At420, process400may involve processor312transmitting a capability report to indicate the maximum number of HARQ processes. Process400may proceed from420to430.

At430, process400may involve processor312performing HARQ process transmissions based on the maximum number of HARQ processes.

In some implementations, process400may involve processor312transmitting the capability report to a network node of an NTN.

In some implementations, the maximum number of HARQ processes may comprise at least one of a maximum number of HARQ processes with soft combining and a maximum number of HARQ processes without soft combining.

In some implementations, the capability report may comprise at least one of a maximum number of resource block, a maximum number of spatial layers, and a maximum number of transport block size.

In some implementations, the capability report may comprise at least one of an unlimited number of HARQ processes, a specified maximum number of HARQ processes, and no increase in the maximum number of HARQ processes.

In some implementations, the capability report may comprise an indication of whether a scaling of maximum number of HARQ processes is supported.

In some implementations, a soft buffer size of the apparatus is not increased.

In some implementations, process400may involve processor312determining a first HARQ process pool and a second HARQ process pool. Process400may further involve processor312performing the HARQ process transmissions with soft combining with respect to the first HARQ process pool and performing the HARQ process transmissions without soft combining with respect to the second HARQ process pool.

In some implementations, process400may involve processor312receiving a specific redundancy version of downlink data with respect to the second HARQ process pool. Process400may further involve processor312decoding the downlink data. The specific redundancy version may be self-decodable.

In some implementations, process400may involve processor312receiving an indication to differentiate the first HARQ process pool and the second HARQ process pool.

FIG. 5illustrates an example process500in accordance with an implementation of the present disclosure. Process500may be an example implementation of above scenarios/schemes, whether partially or completely, with respect to HARQ design in NTN communications with the present disclosure. Process500may represent an aspect of implementation of features of network apparatus320. Process500may include one or more operations, actions, or functions as illustrated by one or more of blocks510,520and530. Although illustrated as discrete blocks, various blocks of process500may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation. Moreover, the blocks of process500may executed in the order shown inFIG. 5or, alternatively, in a different order. Process500may be implemented by network apparatus320or any suitable network nodes or network elements. Solely for illustrative purposes and without limitation, process500is described below in the context of network apparatus320. Process500may begin at block510.

At520, process500may involve processor322determining a maximum number of HARQ processes that the UE can support according to the capability report. Process500may proceed from520to530.

At530, process500may involve processor322performing HARQ process transmissions based on the maximum number of HARQ processes.

In some implementations, process500may involve processor322determining the maximum number of HARQ processes according to a ratio of a maximum number of RB in NR-TN to a maximum number of RB in NR-NTN.

In some implementations, process500may involve processor322determining the maximum number of HARQ processes according to a ratio of a maximum number of spatial layers in NR-TN to a maximum number of spatial layers in NR-NTN.

In some implementations, process500may involve processor322determining the maximum number of HARQ processes according to a scaling of number of carrier components that can be supported in NR-TN and NR-NTN.

In some implementations, process500may involve processor322determining the maximum number of HARQ processes according to a scaling of modulation and coding rate used in NR-TN and NR-NTN.

In some implementations, process500may involve processor322determining a number of DCI bits used to signal a HARQ process identification according to the maximum number of HARQ processes.

In some implementations, process500may involve processor322configuring a first HARQ process pool and a second HARQ process pool to the UE. Process500may further involve processor322performing the HARQ process transmissions with soft combining with respect to the first HARQ process pool and performing the HARQ process transmissions without soft combining with respect to the second HARQ process pool.

In some implementations, process500may involve processor322transmitting a specific redundancy version of downlink data to the UE with respect to the second HARQ process pool.

In some implementations, process500may involve processor322transmitting an indication to the UE to differentiate the first HARQ process pool and the second HARQ process pool.

In some implementations, process500may involve processor322configuring a number of HARQ processes which is greater than the maximum number of HARQ processes that the UE can support with soft combining.

Additional Notes