WO2021228129A1 - Non-sequential hybrid automatic repeat request method and apparatus, base station, and storage medium - Google Patents

Abstract

The present invention provides a non-sequential hybrid automatic repeat request (HARQ) method and apparatus, a base station, and a storage medium, and analyses the relationship between two HARQ processes to determine whether there is transmission unit overlap or HARQ feedback overlap, and introduces a new information element (IE) related to the capability of a UE to process a physical downlink shared channel (PDSCH), used for reflecting the capability of the UE to process the overlap. The new information element can help the base station to implement better data retransmission decision-making.

Description

Non-sequential hybrid automatic retransmission request method, device, base station and storage medium

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office, the application number is 202010414170.X, and the invention title is "Non-sequential hybrid automatic repeat request method, device, base station and storage medium" on May 15, 2020. The entire content is incorporated into this application by reference.

Technical field

The present invention relates to the field of information processing technology, and in particular to a method, device, base station and storage medium for non-sequential hybrid automatic repeat request.

Background technique

Ultra-reliable low-latency communication (URLLC) is one of several different types of use cases supported by the fifth generation (5G) new radio (NR) standard. As specified in the 15th edition of the 3rd Generation Partnership Project (3rd Generation Partnership Project, 3GPP), URLLC is a communication service that has strict requirements for the successful transmission of data packets, especially in terms of availability and delay ( latency) and reliability (availability). URLLC will support emerging applications and services, such as wireless control and automation in industrial factory environments, inter-vehicle communications to improve safety and efficiency, and tactile internet services. Especially considering that the effective support of the automotive sector will bring new services to the entire telecommunications industry, which is particularly important for 5G.

One of the main features of URLLC is low latency. Low latency is important for some applications, such as autonomous vehicles and telemedicine operations. Low latency allows the network to process massive amounts of data with minimal delay and optimize the network. The network needs to adapt to a large amount of changing data in real time to adapt to a wide range of data volumes. 5G will enable such services to work. It can be said that URLLC is the most promising new feature in the upcoming 5G capabilities, but it will also be the most difficult to guarantee. The quality of service (QoS) required by URLLC services is completely different from that of mobile broadband services, and will provide an instantaneous intelligent system for the network.

This new URLLC wireless connection will guarantee a delay within 1 millisecond (millisecond, ms). In order to achieve low latency, all devices must be synchronized to the same time basis. Time-sensitive networking (TSN) is another component of 5G URLLC capabilities. TSN will make the Shaper used to manage traffic time-aware.

The design of low-latency and high-reliability services involves several components, including: integrated frame structure, fast turnaround, efficient control and data resource sharing, grant-free uplink (uplink, UL) ) Transmission, and advanced channel coding schemes. The uplink grant-free structure avoids the process of obtaining dedicated scheduling grants, and ensures the reduction of user equipment (UE) delayed transmission.

technical problem

In NR version 16 or later, non-sequential hybrid automatic repeat reQuest (HARQ) operations and non-sequential physical uplink shared channel (PUSCH) will be supported. In the 16th edition, the intra-UE prioritization within the user equipment (UE) has been covered. However, in the 17th edition, the intra-UE multiplexing (intra-UE multiplexing) is still lacking.

Appropriately adding more UE feedback can achieve better Hybrid Automatic Repeat reQuest (HARQ) operation and/or Modulation and Coding Scheme (MCS) selection.

Technical solutions

A first aspect of the embodiments of the present invention provides a non-sequential hybrid automatic repeat request method, which is executed on a user equipment, and includes: sending a user equipment for indicating the processing capability of the user equipment for multiple overlapping downlink transmission units Downlink capability information; receiving the first transmission unit in the downlink transmission operation associated with the HARQ procedure of the first hybrid automatic repeat request; receiving the first transmission unit in the downlink transmission operation associated with the HARQ procedure of the second hybrid automatic repeat request To determine whether the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain; and when the first transmission unit and the second transmission unit are in When at least one of the time domain and frequency domain overlaps, the user equipment processes the first transmission unit and the second transmission unit according to the processing capabilities indicated by the user equipment downlink capability information, and HARQ feedback of the first transmission unit and the second transmission unit.

The second aspect of the embodiments of the present invention provides a user device that can execute the non-sequential hybrid automatic repeat request method.

A third aspect of the embodiments of the present invention provides a non-sequential hybrid automatic repeat request method, which is executed in a base station, and includes: determining whether to receive a user equipment downlink capability indicating the processing capability of the user equipment for multiple overlapping transmission units Information; send the first transmission unit in the downlink transmission operation associated with the HARQ program of the first hybrid automatic repeat request; send the second transmission in the downlink transmission operation associated with the HARQ program of the second hybrid automatic repeat request Unit; and when the HARQ feedback of one of the first transmission unit and the second transmission unit is received, but the other transmission unit of the first transmission unit and the second transmission unit is not received When HARQ feedback, perform the following steps:

When the downlink capability information of the user equipment is received, it is determined according to the downlink capability information of the user equipment and the received HARQ feedback that the first transmission unit and the second transmission unit need to be reproduced. Transmission unit of transmission.

The fourth aspect of the embodiments of the present invention provides a base station that can execute the non-sequential hybrid automatic repeat request method.

The method disclosed in the present invention can be programmed as computer-executable instructions stored in a non-volatile computer-readable medium. When loaded into the computer, the non-volatile computer-readable medium instructs the processor of the computer to perform the method.

The non-volatile computer-readable medium may include at least one consisting of at least one of the following: hard disk, optical disk, optical storage device, magnetic storage device, read-only memory, programmable read-only memory, erasable programmable only Read memory, EPROM, electronically erasable programmable read-only memory and flash memory.

The method disclosed in the present invention can be compiled into a computer program product, which can cause a computer to execute the method of the present invention.

Beneficial effect

This disclosure mainly studies the operation of non-sequential HARQ feedback and non-sequential uplink. The uplink includes a physical uplink shared channel (PUSCH). The scheduling of non-sequential HARQ-ACK and PUSCH is helpful to meet the requirements of URLLC. In NR version 16 or later, non-sequential HARQ and non-sequential PUSCH will be supported. In the present invention, the whole mechanism of non-sequential HARQ operation in the overlapping physical downlink shared channel (PDSCH) scenario and the non-overlapping PDSCH scenario is provided. In terms of uplink, the present invention also analyzes the relationship between the two HARQs, and introduces a new information element (Information element, IE) about the ability of the UE to process PDSCH. This new element can help the base station to better perform data Retransmission decision. In addition, the present invention also introduces a new information element for the UE's ability to process PUSCH, which can also bring benefits to data retransmission. The proposed design can reduce the complexity of the system and improve the reliability of communication.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor.

FIG. 1 is a schematic diagram of a base station, a user device, and a network entity device provided by an embodiment of the present invention;

2 is a flowchart of a non-sequential hybrid automatic retransmission request method according to an embodiment of the present invention;

FIG. 3 is a flowchart of a non-sequential hybrid automatic repeat request method executed at a base station according to an embodiment of the present invention;

4 is a flowchart of a non-sequential hybrid automatic retransmission request method executed on a user device according to an embodiment of the present invention;

Fig. 5 is a flowchart of a user device executing a judgment on whether to discard an overlapping transmission unit in an embodiment of the present invention;

FIG. 6 is a flow chart of determining whether to discard the confirmation response or the non-confirmation response of the overlapping transmission unit on the user equipment in an embodiment of the present invention;

FIG. 7 is a schematic diagram of an example in which the transmission unit and the HARQ feedback are not overlapped in the application embodiment of the present invention;

8 is a schematic diagram of an example in which transmission units are not overlapped but HARQ feedback overlaps in an application embodiment of the present invention;

9 is a schematic diagram of an example in which transmission units overlap but HARQ feedback is not overlapped in an application embodiment of the present invention;

10 is a schematic diagram of an example of overlapping transmission units and overlapping HARQ feedback in an application embodiment of the present invention;

FIG. 11 is a schematic diagram of a system to which a non-sequential hybrid automatic repeat request method provided by an application embodiment of the present invention is applied.

Embodiments of the present invention

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

The terms "first", "second", "third", "fourth", etc. (if any) in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used Describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described herein can be implemented in a sequence other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any variations of them are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to a clearly listed Instead, it may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or equipment.

The issues of non-sequential HARQ and non-sequential PUSCH have been discussed in 3GPP, but there is no conclusion about the overlap problem on the uplink side. The behavior of the UE and the interaction between the UE and the base station are currently unclear. The present invention proposes an overall mechanism for non-sequential HARQ in overlapping PDSCH scenarios and non-overlapping PDSCH scenarios. In terms of uplink, the present invention proposes different solutions for whether there is a collision between HARQs. Moreover, the present invention also proposes new UE capability signaling, which respectively proposes new UE capability signaling for PDSCH processing and PUSCH processing.

1, a user equipment (UE) 10a, a UE 10b, a base station (BS) 200a, and a network entity device 300 perform a method according to an embodiment of the present invention. The connections between the device and the device components are shown in the form of lines and arrows in FIG. 1. The UE 10a may include a processor 11a, a memory 12a, and a transceiver 13a. The UE 10b may include a processor 11b, a memory 12b, and a transceiver 13b. The base station 200a may include a processor 201a, a memory 202a, and a transceiver 203a. The network entity device 300 may include a processor 301, a memory 302, and a transceiver 303. Each of the processors 11a, 11b, 201a, and 301 may be configured to implement the functions, procedures, and/or methods described in this description. Multiple layers of the radio interface protocol can be implemented in the processors 11a, 11b, 201a, and 301. Each of the memories 12a, 12b, 202a, and 302 stores various programs and information in an operable state to operate the connected processor. Each of the transceivers 13a, 13b, 203a, and 303 is coupled with the connected processor in an operable state to transmit and/or receive radio signals. The base station 200a may be one of eNB, gNB, or other radio nodes.

Each of the processors 11a, 11b, 201a, and 301 may include a general-purpose central processing unit (CPU), an application specific integrated circuit (ASIC), other chipsets, logic circuits, and/or data processing devices. Each of the memories 12a, 12b, 202a, and 302 may include read-only memory (ROM), random access memory (RAM), flash memory (random access memory), and memory card (memory card). ), storage medium, other storage device, and/or any combination of memory and storage device. Each of the transceivers 13a, 13b, 203a, and 303 may include a baseband circuit and a radio frequency (RF) circuit to process radio frequency signals. When the embodiments of the present invention are implemented in software, the technology described herein can be implemented by modules, programs, functions, entities, etc. that perform the functions described herein. These modules can be stored in the memory and executed by the processor. The memory may be implemented inside the processor or outside the processor, where the memory may be communicatively coupled with the processor in various ways known in the art.

The network entity device 300 may be a node in a central network (central network, CN). CN may include LTE CN or 5G core (5G core, 5GC), which may include user plane function (UPF), session management function (session management function, SMF), mobility management function (mobility management function, AMF) ), unified data management (UDM), policy control function (PCF), control plane/user plane separation (CUPS), authentication server function (AUSF) , Network slicing selection function (network slice selection function, NSSF), network exposure function (network exposure function, NEF) and other network entities.

Referring to FIG. 2, a user equipment (for example, at least one of UE 10a and UE 10b in FIG. 1) generates and transmits user equipment capability information 212 to a base station (for example, base station 200a in FIG. 1) (step 210). The base station receives the user equipment capability information (step 213). The user equipment capability information may include user equipment downlink capability information indicating the processing capability of the user equipment for a plurality of overlapping downlink (DL) transmission units. In addition, the user equipment capability information may further include user equipment uplink capability information for indicating the processing capability of the user equipment for a plurality of overlapping uplink (UL) transmission units. The uplink capability information of the user equipment indicates that the user equipment can only process one of multiple overlapping uplink transmission units, or simultaneously process two of multiple overlapping uplink transmission units. The downlink includes at least one of a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH). The uplink includes at least one of a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH). The transmission unit may include a transport block (TB), a code block (CB), and a code block group (CBG).

The base station transmits the first transmission unit in the downlink transmission operation associated with the first HARQ program (step 214), and transmits the second transmission unit in the downlink transmission operation associated with the second HARQ program (step 216). ). The identifier (ID) of the first HARQ program is y, and the ID of the second HARQ program is x. The first and second HARQ may be URLLC services with low latency requirements.

The base station performs PDSCH retransmission according to the user equipment capability information and the HARQ feedback received from the user equipment (step 218). 3 to 6 are cross-referenced to illustrate specific embodiments of the present invention.

In FIG. 3, the base station transmits the first transmission unit in the downlink transmission operation associated with the first HARQ program (step 310) and the second transmission unit in the downlink transmission operation associated with the second HARQ program (Step 311) to the user device.

In FIG. 4, the user equipment receives from the base station the first transmission unit (step 400) in the downlink transmission operation associated with the first HARQ program and the downlink associated with the second HARQ program The second transmission unit in the transmission operation (step 401). The user equipment determines whether the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain (step 403).

For the 16th version of the 3GPP standard (Rel.16) enhanced URLLC (enhanced URLLC, eURLLC) UE and dynamic downlink scheduling, the effective bandwidth part (BWP) of a given serving cell (serving cell) Above, for the second PDSCH with the HARQ process ID x received after the first PDSCH with the HARQ process ID y, the HARQ-ACK of the second PDSCH can be sent before the HARQ-ACK of the first PDSCH. Where x is not equal to y. Two PDSCHs may overlap. Regarding the relationship between the two PDSCHs, in the following description, the scheduling operation can be divided into two cases, non-overlapping PDSCH and overlapping PDSCH.

The first embodiment:

The following describes the implementation of non-overlapping PDSCH non-sequential HARQ operation.

As shown in Figures 7 and 8, for the non-overlapping PDSCH1 and PDSCH2, since the two PDSCHs do not overlap in the time domain and the frequency domain, there will be no PDSCH processing problems. The user equipment (for example, one of UEs 10a and 10b in FIG. 1) can receive and decode both PDSCHs, and does not discard any PDSCHs (step 404). The user equipment reports the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit respectively according to the reception and decoding conditions of the two PDSCHs (step 405). However, as shown in FIG. 8 and FIG. 10, regarding the uplink, if there is overlap or collision between two HARQs, non-sequential HARQ operations will occur, and non-sequential HARQ operations may have different situations.

When the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain ("Yes" in step 403), the user equipment is determined according to the downlink capability information of the user equipment. The indicated processing capability is to process the first transmission unit PDSCH1 and the second transmission unit PDSCH2, and the HARQ feedback HARQ1 and HARQ2 of the first and second transmission units (step 408). Refer to FIG. 5 to explain step 408 in FIG. 4.

In FIG. 5, the user device determines the processing capability of the user device, and the processing capability indicates whether the user device can simultaneously process the overlapping of the first transmission unit and the second transmission unit (step 510)? When the user equipment can simultaneously process the overlapping of the first transmission unit and the second transmission unit, the user equipment reports the HARQ feedback of the first transmission unit and the HARQ of the second transmission unit respectively Feedback (step 512). When the user equipment cannot process the overlapping of the first transmission unit and the second transmission unit at the same time, the user equipment uses the processing capability indicated by the user equipment downlink capability information, and according to the The characteristics of the first transmission unit and the second transmission unit, discard one transmission unit of the first and second transmission units, and decode the other transmission unit (step 514), and report the first and second transmission units respectively The HARQ feedback of the discarded and sent transmission units in the second transmission unit (step 516). In the following description, one of the first and second transmission units that is discarded is referred to as the one transmission unit that is selected for abandonment, and the other one of the first and second transmission units that is sent The unit is called a transmission unit selected for reporting. In HARQ feedback, the acknowledgement (acknowledgement, ACK) is used to inform the sender (the base station in this embodiment) that the associated transmission unit does not need to be retransmitted; the non-acknowledgement (NACK) is used It informs the sending end (the base station in this embodiment) that the associated transmission unit needs to be retransmitted. Step 405 in FIG. 4 and step 512 and step 516 in FIG. 5 can be described with reference to FIG. 6.

In FIG. 6, the user equipment determines whether the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit overlap in at least one of the time domain and the frequency domain (step 610). When the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit do not overlap, the user equipment sends the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit respectively (Step 612). When the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit overlap, the user equipment determines whether the HARQ feedback of the first transmission unit and the second transmission unit can be multiplexed. HARQ feedback (step 614)?

When the user equipment can multiplex the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit, the user equipment multiplexes the first transmission in one uplink resource The HARQ feedback of the unit and the HARQ feedback of the second transmission unit (step 616). When the user equipment cannot transmit the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit in multiplexing, the user equipment performs processing according to the processing capability indicated by the user equipment downlink capability information , And according to the characteristics of the first transmission unit and the second transmission unit, discard the HARQ feedback of the transmission unit selected to give up the report among the first and second transmission units, and send the first and second transmission units The HARQ feedback of a transmission unit selected for reporting among the two transmission units (step 618).

In Figure 3, the base station judges whether the HARQ feedback of the first and second transmission units is received (step 313)? When the base station receives the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit, it judges and performs retransmission according to the received HARQ feedback of the first and second transmission units (step 314 ). When the base station does not receive the HARQ feedback of the first transmission unit and the second transmission unit, it means that the base station has received the HARQ feedback of one of the first and second transmission units, but did not receive the HARQ feedback. HARQ feedback of another transmission unit (step 315), the base station determines whether the user equipment downlink capability information is received (step 316)? When the base station does not receive the user equipment downlink capability information, the base station performs retransmission of the transmission unit according to the received HARQ feedback (step 319). When the base station has received the user equipment downlink capability information, the base station determines the first transmission unit and the second transmission unit according to the user equipment downlink capability information and the received HARQ feedback. The transmission unit among the transmission units that needs to be retransmitted, and retransmission is performed (step 318).

In the example in Figure 8, there is a collision between HARQ1 and HARQ2, which requires analysis operations. The first case is that if HARQ1 and HARQ2 meet the multiplexing conditions, then HARQ1 and HARQ2 can be multiplexed and transmitted together. In addition, the multiplexing conditions can use the multiplexing strategy in Section 9.2.5 of Release 15 38.214 or the multiplexing strategy for subsequent versions of 3GPP. The priority can be obtained from Uplink Control Information (DCI). Otherwise, if HARQ1 and HARQ2 do not meet the multiplexing conditions, one of HARQ needs to be discarded. In this case, the latter HARQ1 needs to be discarded, or the HARQ with a lower priority is discarded. For the UE, only the HARQ corresponding to the second PDSCH or the HARQ with a higher priority is sent. The base station should be able to determine that if only one HARQ feedback is received, it needs to retransmit the first PDSCH1 or the PDSCH with a lower priority.

The second embodiment:

The following describes the implementation of overlapping PDSCH non-sequential HARQ operations. Two overlapping PDSCHs may include two situations:

●Case 1-1: Time domain overlap, frequency domain does not overlap

●Case 1-2: Overlap of time domain and frequency domain

For Case 1-1 and Case 1-2, if the UE has the ability to decode two PDSCHs at the same time, then the non-sequential HARQ operation for Case 1-1 and Case 1-2 may be the same. Moreover, the HARQ feedback strategy can reuse the mechanism of the non-overlapping PDSCH scenario as shown in the first embodiment.

If the UE does not have the ability to decode two PDSCHs at the same time, a different strategy should be determined for each scenario. The user equipment has the following UE capabilities to handle collisions between two unicast PDSCHs.

● Capability A: The ability of the UE to handle two overlapping PDSCHs in case 1-1.

● Capability B: the ability of the UE to handle two overlapping PDSCHs in case 1-2;

● Capability C: UE always handles high priority PDSCH. Under certain scheduling conditions, the UE only processes low-priority PDSCH.

In this case, a new parameter needs to be introduced for the downlink capability information of the user equipment. The UE should set the content of the UECapabilityInformation message to provide it to the network. And this new parameter PDSCH-ProcessingCapability should be included in the information element (IE) UE-NR-Capability, and rat-Type is set to nr. The parameter PDSCH-ProcessingCapability can be defined in the following ways:

PDSCH-ProcessingCapability ENUMERATED{capabilityA,capabilityB,capabilityC,…}OPTIONAL,

Each entry in PDSCH-ProcessingCapability corresponds to each capability defined above. Specifically, capabilityA, capabilityB, and capabilityC correspond to the capability A, capability B, and capability C, respectively. The PDSCH-ProcessingCapability may be included in the phy-ParametersCommon parameter in the information element Phy-Parameters. Or PDSCH-ProcessingCapability may be included in the mac-ParametersCommon parameter in IE MAC-Parameters.

Regarding case 1-1, if the UE has the ability to process two PDSCHs at the same time, but the two PDSCHs cannot be decoded at the same time, one of the PDSCHs should be discarded. Therefore, the HARQ feedback corresponding to the discarded PDSCH should reply with a NACK to the base station. In this embodiment, the PDSCH expected to be discarded should be an earlier PDSCH, such as PDSCH1 in FIG. 9. As shown in FIG. 9, similar to the description in the first embodiment, if there is no collision between two HARQs, the HARQ feedback of the discarded PDSCH and the reserved PDSCH can be transmitted separately.

However, as shown in Figure 10, if HARQ1 and HARQ2 overlap each other, the two HARQs cannot be reported separately. The combination of the user equipment capability information and HARQ feedback information reported by the UE can help the base station make better decisions. If HARQ1 and HARQ2 meet the multiplexing conditions, the two HARQ feedbacks of PDSCH1 and PDSCH2 can be transmitted together. However, if the multiplexing conditions are not met, one of the HARQ feedback needs to be discarded, and the base station cannot determine which PDSCH needs to be retransmitted. In this case, UE capability information is required. When the base station receives only one HARQ feedback, and the PDSCH-ProcessingCapability in the received UE capability information is set to CapabilityA, the base station can determine that the HARQ feedback corresponding to the previous PDSCH has not been sent. Based on this, if the decoding of PDSCH2 is successful, the UE returns an ACK to the base station, and the PDSCH-ProcessingCapability is set to CapabilityA, the base station can perform retransmission of PDSCH1. The base station may determine, according to the delay requirement of the PDSCH1, that the PDSCH1 needs to be retransmitted when the HARQ feedback of the PDSCH1 is not received. In addition, if the UE fails to decode PDSCH2, the UE responds with a NACK to the base station, and the base station can retransmit the information of PDSCH1 and PDSCH2 with PDSCH1 and PDSCH2 respectively without overlapping in the time domain.

The mechanism for case 1-2 can be the same as that for case 1-1. If the UE is capable of processing two PDSCHs, but the two PDSCHs cannot be decoded at the same time, then one of the PDSCHs should be discarded. The HARQ feedback corresponding to the discarded PDSCH should respond with NACK, and the user equipment replies with NACK to the base station. In this embodiment, the PDSCH determined to be discarded should be the earlier PDSCH1. Similar to the description in the first embodiment, if there is no collision between the two HARQs, the HARQ feedback of the discarded PDSCH and the reserved PDSCH can be transmitted separately.

However, if HARQ1 and HARQ2 overlap each other, then these two HARQs cannot all be reported to the base station. In this case, if the two HARQs meet the multiplexing conditions, both HARQs can be transmitted together. Otherwise, HARQ1 and HARQ2 cannot meet the multiplexing conditions, and one of HARQ must be discarded. Similar to the mechanism of Scheme 1-1, combining the UE capability report and HARQ feedback information can help the base station make better decisions. When the base station receives only one HARQ feedback and the PDSCH-ProcessingCapability is set to CapabilityB, the base station can determine that the HARQ feedback corresponding to the previous PDSCH has not been sent. Based on this, if the user equipment successfully decodes PDSCH2, the user equipment returns an ACK to the base station. Upon receiving the ACK and setting the PDSCH-ProcessingCapability to CapabilityB, the base station can independently perform the retransmission of PDSCH1. In addition, if the UE fails to decode PDSCH2, the UE responds with a NACK to the base station. The base station may use the information of PDSCH-ProcessingCapability and according to the NACK, retransmit PDSCH1 and PDSCH2 respectively when the time and frequency regions do not overlap.

Therefore, when the first transmission unit (e.g. PDSCH1) and the second transmission unit (e.g. PDSCH2) overlap in at least one of the time domain and the frequency domain, the user equipment is The processing capability CapabilityA or CapabilityB indicated by the capability information, discard the first transmission unit and the second transmission unit received first, as the transmission unit selected to give up the report, and to the first transmission unit The transmission unit and the transmission unit received later in the second transmission unit are decoded as the transmission unit selected for reporting.

When the later-received transmission unit is successfully decoded, an acknowledgement response ACK for the later-received transmission unit is sent, wherein the acknowledgement response ACK and the downlink capability information of the user equipment provide the judgment to retransmit the The judgment basis information required by the first received transmission unit.

When the decoding of the later-received transmission unit is unsuccessful, the non-acknowledgement response NACK of the later-received transmission unit is sent, wherein the non-acknowledgement response NACK and the user equipment downlink capability information provide judgment Retransmit the judgment basis information required by the first-received transmission unit and the later-received transmission unit.

Regarding capability C, the user equipment handles overlapping transmission units based on the priority of each PDSCH. That is, the UE always processes the high-priority PDSCH, and the UE only processes the low-priority PDSCH under certain scheduling conditions. If it is determined that there is no scheduling condition or the scheduling condition is not met, the UE skips decoding the low-priority PDSCH, and the HARQ feedback corresponding to the low-priority PDSCH is NACK. The user equipment replies the NACK to the base station. If there is no collision or overlap between the two HARQs, the HARQ feedback of the dropped PDSCH and the reserved PDSCH can be transmitted separately. However, if HARQ1 and HARQ2 overlap each other, the two HARQs cannot be sent to the base station separately. In this case, if the two HARQs meet the multiplexing condition, the two HARQs can be transmitted together. Otherwise, HARQ1 and HARQ2 cannot meet the multiplexing conditions, and the feedback of the low-priority HARQ program will be discarded. Similar to the mechanism of Case 1-1, combining UE capability information and HARQ feedback information can help the base station make better decisions. When the base station receives only one HARQ feedback and the PDSCH-ProcessingCapabilityC is set to CapabilityC, the base station can determine that the HARQ feedback corresponding to the low-priority PDSCH1 has not been sent. Based on this, if the decoding of PDSCH2 is successful, the UE returns an ACK to the base station, and the PDSCH-ProcessingCapability is set to CapabilityC, the base station can retransmit PDSCH1 alone. In addition, if the UE fails to decode PDSCH2, the UE responds with a NACK to the base station, and the base station can use the information of PDSCH-ProcessingCapability to retransmit PDSCH1 and PDSCH2 respectively.

Therefore, when the first transmission unit (e.g. PDSCH1) and the second transmission unit (e.g. PDSCH2) overlap in at least one of the time domain and the frequency domain, the user equipment is The processing capability CapabilityC indicated by the capability information, discarding the transmission unit with low priority among the first transmission unit and the second transmission unit, as the transmission unit selected to give up the report, and to the first transmission The unit and the transmission unit with a high priority in the second transmission unit are decoded as the transmission unit selected for reporting.

When the transmission unit with the high priority is successfully decoded, the transmission unit with the high priority is sent an acknowledgement response ACK. The acknowledgment response ACK and the downlink capability information of the user equipment provide judgment basis information required for judging to retransmit the transmission unit with the low priority.

When the decoding of the transmission unit with high priority is unsuccessful, the non-acknowledgement response NACK of the transmission unit with high priority is sent, wherein the non-acknowledgement response NACK and the user equipment downlink capability information Provide judgment basis information required for judging retransmission of the transmission unit with low priority and the transmission unit with high priority.

The third embodiment:

The following describes the implementation of non-sequential PUSCH operation.

For non-sequential PUSCH, on the active BWP of a given serving cell, the UE can use the second PUSCH associated with HARQ process x for scheduling, and the start time of this PUSCH is earlier than the first one associated with HARQ process y The end symbol of the PUSCH, and the end symbol of the PUSCH is not earlier than the end symbol of the first scheduled PUSCH. Unlike non-sequential HARQ, if PUSCH1 and PUSCH2 overlap in time and/or frequency regions, one of the PUSCHs must be discarded. In order to adapt to this situation, it is necessary to discard the PUSCH corresponding to the previous PDCCH or the PUSCH with a lower priority. For the base station side, the base station needs to know which PDCCH needs to be retransmitted, and a new UE capability parameter needs to be introduced. The UE should set the content of the UECapabilityInformation message and provide it to the base station. This new parameter PUSCH-ProcessingType should be included in the information UE-NR-Capability, and rat-Type is set to nr. The PUSCH-ProcessingType can be set in the following ways:

PUSCH-ProcessingType ENUMERATED{type1,type2,…}OPTIONAL,

Each entry in the PUSCH-ProcessingType corresponds to a different type of PUSCH processing capability type. For example, type1 indicates that the UE can only process one PUSCH in a non-sequential PUSCH scenario, and type2 corresponds to the UE can process two PUSCHs. This user equipment uplink capability information (PUSCH-ProcessingType) may be included in the mac-ParametersCommon parameter in the information element MAC-Parameters or the phy-ParametersCommon parameter in the information element Phy-Parameters.

FIG. 11 is a schematic diagram of an exemplary wireless communication system 700 for performing the method disclosed according to the embodiments of the present invention. The embodiments described herein can be implemented using any suitably configured hardware and/or software. FIG. 11 illustrates a system 700, including a radio frequency circuit 710, a baseband circuit 720, a processor 730, a memory/storage device 740, a sensor 770, and an input/output (input/output, I/O) interface 780, which are connected to each other as shown .

The processor 730 may include circuitry, such as (but not limited to) one or more single-core or multi-core processors. The processor may include any combination of a general-purpose processor and a special-purpose processor, such as a graphics processor and an application processor (application processor). The processor may be coupled to the memory/storage device 740 and configured to execute instructions stored in the memory/storage device 740 to enable various application programs and/or operating systems running on the system.

The transceiver 720 may include circuitry, such as (but not limited to) one or more single-core or multi-core processors. The processor may include a baseband (baseband) circuit and a radio frequency (RF) circuit. The baseband circuit can handle various radio control functions and communicate with one or more radio networks through radio frequency circuits. Radio control functions can include, but are not limited to, signal modulation, encoding, decoding, radio frequency conversion, and so on. In some embodiments, the baseband circuit can provide communications compatible with one or more radio technologies. For example, in some embodiments, the baseband circuit can support and evolve the universal terrestrial radio access network (Evolved Universal Terrestrial Radio Access Network, EUTRAN) and/or other wireless metropolitan area network (Wireless Metropolitan Area Network, WMAN), wireless local area network (Wireless Local Area Network, WLAN), Wireless Personal Area Network (Wireless Personal Area Network, WPAN). An implementation in which the baseband circuit is configured to support radio communication of multiple wireless protocols may be referred to as a multi-mode baseband circuit. In various embodiments, the baseband circuit may include circuits for operating signals that are not strictly regarded as baseband frequencies. For example, in some embodiments, the baseband circuit may include a circuit that operates on a signal having an intermediate frequency (i.e., baseband frequency and radio frequency).

The radio frequency circuit can communicate with a wireless network using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuit may include switches, filters, amplifiers, etc. for communication with a wireless network. In various embodiments, the RF circuit may include circuits for operating with signals that are not strictly considered to be in radio frequency. For example, in some embodiments, the RF circuit may include a circuit for working with signals having an intermediate frequency between the baseband frequency and the radio frequency.

As used herein, "circuit" may refer to, participate in, or include application specific integrated circuits (Application Specific Integrated Circuit, ASIC), electronic circuits, processors (shared, dedicated chips or chipsets), and/or execute one or more software or Firmware programs, combinational logic circuits, and/or other suitable hardware components that provide the above-mentioned functions. In some embodiments, the circuit of the electronic device or the function related to the circuit may be implemented in one or more software or firmware modules. In some embodiments, part or all of the components of the baseband circuit, application circuit, and/or memory/storage device 740 may be implemented together on a system on a chip (SOC).

The memory/memory 740 can be used to load and store data and/or instructions for the system, for example. In one embodiment, the memory/memory may include any combination of suitable volatile memory, such as dynamic random access memory (DRAM) and/or non-volatile memory, such as flash memory. In various embodiments, the I/O interface 780 may include one or more user interfaces for implementing user interaction with the system and/or peripheral component interfaces for implementing the interaction between peripheral components and the system. The user interface may include, but is not limited to, a physical keyboard or keypad, touch pad, speaker, microphone, etc. The peripheral component interface may include, but is not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power interface.

0065] [0067] In various embodiments, the sensor 770 may include one or more sensing devices to determine environmental conditions and/or location information related to the system. In some embodiments, the sensor may include, but is not limited to, a gyroscope sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be a part of the baseband circuit and/or radio frequency circuit, or interact with the baseband circuit and/or radio frequency circuit to communicate with components of the positioning network, for example, global positioning system (GPS) satellite communication. In various embodiments, the system 700 may be a mobile computing device, such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smart phone, etc. In various embodiments, the system may have more or fewer components, and/or different architectures. Where appropriate, the methods described here can be implemented as computer programs. The computer program can be stored in a storage medium, such as a non-transitory storage medium.

The embodiments of the present disclosure may adopt a combination of technologies/processes in the 3GPP specification to create a final product.

A person with ordinary skills can understand that each unit, algorithm, and step described and disclosed in the embodiment of the present disclosure is implemented using electronic hardware or a software combination of computer and electronic hardware. Whether these functions run in hardware or in software depends on the application conditions and design requirements of the technical solution. People with ordinary skills can use different ways to implement functions for each specific application, and such implementation should not go beyond the scope of the present disclosure. A person with an ordinary technical level can understand that since the working processes of the above systems, devices, and units are basically the same, they can refer to the working processes of the systems, devices, and units in the above embodiments. For ease of description and simplification, these working processes are not described in detail here.

It can be understood that the system, device, and method disclosed in the embodiments of the present invention may also be implemented in other ways. The above embodiment is only exemplary. The division of the unit is only based on the division of logic functions, and other divisions exist in the implementation. It is possible to combine or integrate multiple units or components in another system. It is also possible to omit or skip certain features. On the other hand, the displayed or discussed mutual coupling, direct coupling, or communication coupling, etc., operate indirectly or communicatively through some ports, devices, or units through electrical, mechanical, or other types of means.

A unit that is a separate component is or is not a physically separate unit. These units are physical units or not, that is, they are located in one place or distributed on multiple network units, and these units are physical units or not. According to the purpose of the embodiment of the present invention, part or all of the units are used. In addition, each functional unit in this embodiment may be integrated in one processing unit, or physically independent, or two or more units integrated in one processing unit.

If the software functional unit is implemented and used and sold as a product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solutions proposed by the technical solutions of the present disclosure may be implemented essentially or partially in the form of software products. Alternatively, a part of the technical solution that is advantageous to the traditional technology can be implemented in the form of a software product. The software product in the computer is stored in a storage medium, and the software product includes commands for a computing device (for example, a personal computer, a server, or a network device) to run all or part of the steps disclosed in the technical solution of the present disclosure. The storage medium includes a USB disk (USB disk), a mobile hard disk, a read-only memory (read-only memory, ROM), a random access memory (random access memory, RAM), a floppy disk, or other media capable of storing program codes.

The foregoing describes in detail a non-sequential hybrid automatic retransmission request method, device, system, and storage device provided by the embodiments of the present invention. Specific examples are used in this article to illustrate the principles and implementations of the present invention. The above embodiments The description is only used to help understand the method and core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and the scope of application. In summary As mentioned, the content of this specification should not be construed as a limitation of the present invention.

Claims (22)

1. A non-sequential hybrid automatic retransmission request method, executed on a user device, characterized in that it includes:

   Sending user equipment downlink capability information used to indicate the processing capability of the user equipment for a plurality of overlapping downlink transmission units;

   Receiving the first transmission unit in the downlink transmission operation associated with the first hybrid automatic repeat request HARQ procedure;

   Receiving the second transmission unit in the downlink transmission operation associated with the second hybrid automatic repeat request HARQ procedure;

   Determining whether the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain; and

   When the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain, the user equipment processes all areas according to the processing capabilities indicated by the user equipment downlink capability information. The first transmission unit and the second transmission unit, and the HARQ feedback of the first transmission unit and the second transmission unit.
2. The non-sequential hybrid automatic repeat request method according to claim 1, wherein the method further comprises:

   Determine whether the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit overlap in at least one of the time domain and the frequency domain.
3. The non-sequential hybrid automatic repeat request method according to claim 2, wherein the method further comprises:

   When the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit overlap in at least one of the time domain and the frequency domain, it is determined whether the HARQ feedback and the HARQ feedback of the first transmission unit can be multi-tasked. HARQ feedback of the second transmission unit; and

   When the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit can be multi-tasked, the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit are transmitted in one uplink resource in multiple tasks. HARQ feedback of the second transmission unit.
4. The non-sequential hybrid automatic repeat request method according to claim 3, wherein the method further comprises:

   When the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit overlap in at least one of the time domain and the frequency domain, and the HARQ feedback and the HARQ feedback of the first transmission unit cannot be transmitted in multitasking. In the HARQ feedback of the second transmission unit, the user equipment discards all the processing capabilities indicated by the user equipment downlink capability information and the characteristics of the first transmission unit and the second transmission unit. HARQ feedback of the one of the first transmission unit and the second transmission unit that is selected to give up reporting, and send the one of the first transmission unit and the second transmission unit that is selected for reporting HARQ feedback.
5. The non-sequential hybrid automatic repeat request method according to claim 4, wherein the method further comprises:

   When the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain, the user equipment discards the processing capability indicated by the user equipment downlink capability information. The transmission unit received first among the first transmission unit and the second transmission unit is used as the transmission unit that is selected to give up the report, and the transmission unit received first among the first transmission unit and the second transmission unit The transmission unit is decoded as the transmission unit selected for reporting.
6. The non-sequential hybrid automatic repeat request method according to claim 5, wherein the method further comprises:

   When the later-received transmission unit is successfully decoded, an acknowledgement response of the later-received transmission unit is sent, wherein the acknowledgement response and the downlink capability information of the user equipment provide a judgment to retransmit the first-received Information on the basis of judgment required by the arriving transmission unit; and

   When the decoding of the later-received transmission unit is unsuccessful, send the non-acknowledged response of the later-received transmission unit, wherein the non-acknowledged response and the user equipment downlink capability information provide judgment retransmission The judgment basis information required by the first-received transmission unit and the later-received transmission unit.
7. The non-sequential hybrid automatic repeat request method according to claim 4, wherein in the step of judging whether the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain After that, the method further includes:

   When the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain, the user equipment discards the processing capability indicated by the user equipment downlink capability information. The transmission unit with a low priority among the first transmission unit and the second transmission unit is used as the transmission unit that is selected to give up the report, and the transmission unit with a high priority for the first transmission unit and the second transmission unit The priority transmission unit is decoded as the transmission unit selected for reporting.
8. The non-sequential hybrid automatic repeat request method according to claim 7, wherein the method further comprises:

   When the transmission unit with high priority is successfully decoded, an acknowledgement response of the transmission unit with high priority is sent, wherein the acknowledgement response and the downlink capability information of the user equipment provide the judgment to retransmit the Judgment basis information required by transmission units with low priority; and

   When the decoding of the transmission unit with high priority is unsuccessful, the non-acknowledgement response of the transmission unit with high priority is sent, wherein the non-acknowledgement response and the user equipment downlink capability information provide judgment The judgment basis information required by the transmission unit with low priority and the transmission unit with high priority is retransmitted.
9. The non-sequential hybrid automatic repeat request method according to claim 2, wherein the method further comprises:

   When the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit do not overlap in at least one of the time domain and the frequency domain, the HARQ feedback of the first transmission unit and the first transmission unit are reported respectively. The HARQ feedback of the second transmission unit includes sending the non-acknowledgement response of the transmission unit selected to give up the report, and sending the acknowledgement response of the transmission unit selected to perform the report.
10. The non-sequential hybrid automatic repeat request method according to claim 2, wherein the method further comprises:

    When the first transmission unit and the second transmission unit do not overlap in at least one of the time domain and the frequency domain, the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit are reported respectively ;as well as

    When the HARQ feedback of the first transmission unit and the HARQ feedback of the second transmission unit overlap in at least one of the time domain and the frequency domain, and the HARQ feedback and the HARQ feedback of the first transmission unit cannot be transmitted in multitasking. In the HARQ feedback of the second transmission unit, the user equipment discards the transmission unit with low priority among the first transmission unit and the second transmission unit as the transmission unit that is selected to give up the report, and to the A transmission unit with a high priority among the first transmission unit and the second transmission unit performs decoding as the transmission unit selected for reporting.
11. The non-sequential hybrid automatic repeat request method according to claim 1, wherein the downlink capability information of the user equipment is included in the mac-ParametersCommon parameter in the information element MAC-Parameters, or in the information element Phy-Parameters The phy-ParametersCommon parameters.
12. The non-sequential hybrid automatic repeat request method according to claim 1, wherein the method further comprises:

    Sending user equipment uplink capability information for indicating the processing capability of the user equipment for a plurality of overlapping uplink transmission units; and

    Wherein, the uplink capability information of the user equipment indicates that the user equipment can only process one of the multiple overlapping uplink transmission units, or simultaneously process two of the multiple overlapping uplink transmission units.
13. The non-sequential hybrid automatic repeat request method according to claim 12, wherein the uplink capability information of the user equipment is included in the mac-ParametersCommon parameter in the information element MAC-Parameters, or in the information element Phy-Parameters The phy-ParametersCommon parameters.
14. A non-sequential hybrid automatic retransmission request method, executed in a base station, and characterized in that it includes:

    Determining whether to receive user equipment downlink capability information indicating the processing capability of the user equipment for multiple overlapping transmission units;

    Sending the first transmission unit in the downlink transmission operation associated with the first hybrid automatic repeat request HARQ procedure;

    Sending the second transmission unit in the downlink transmission operation associated with the second hybrid automatic repeat request HARQ procedure; and

    When the HARQ feedback of one of the first transmission unit and the second transmission unit is received, but the HARQ feedback of the other transmission unit of the first transmission unit and the second transmission unit is not received , Perform the following steps:

    When the downlink capability information of the user equipment is received, it is determined according to the downlink capability information of the user equipment and the received HARQ feedback that the first transmission unit and the second transmission unit need to be reproduced. Transmission unit of transmission.
15. The non-sequential hybrid automatic repeat request method according to claim 14, wherein the method further comprises:

    Retransmit the first transmission unit and the second transmission unit that was sent first in response to the processing capability of the user equipment indicated by the user equipment downlink capability information, wherein the user equipment downlinks The processing capability of the user equipment indicated by the link capability information indicates that when the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain, the user equipment is The processing capability indicated by the downlink capability information of the user equipment, discarding the transmission unit received first among the first transmission unit and the second transmission unit as the transmission unit selected to give up the report, and A transmission unit and a transmission unit received later in the second transmission unit are decoded as the transmission unit selected for reporting.
16. The non-sequential hybrid automatic repeat request method according to claim 14, wherein the method further comprises:

    Retransmit the low-priority transmission unit of the first transmission unit and the second transmission unit in response to the processing capability of the user equipment indicated by the user equipment downlink capability information, wherein the user equipment The processing capability of the user equipment indicated by the downlink capability information indicates: when the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain, the user equipment is based on The processing capability indicated by the downlink capability information of the user equipment, discarding the transmission unit with low priority among the first transmission unit and the second transmission unit, as the transmission unit selected to give up the report, and The transmission unit with high priority among the first transmission unit and the second transmission unit performs decoding as the transmission unit selected for reporting.
17. The non-sequential hybrid automatic repeat request method according to claim 14, wherein the method further comprises:

    When the user equipment downlink capability information is not received, retransmit a transmission unit with a low priority among the first transmission unit and the second transmission unit.
18. The non-sequential hybrid automatic repeat request method according to claim 14, wherein the method further comprises:

    Receiving user equipment uplink capability information used to indicate the processing capability of the user equipment for a plurality of overlapping uplink transmission units;

    Wherein, the uplink capability information of the user equipment indicates that the user equipment can only process one of the multiple overlapping uplink transmission units, or simultaneously process two of the multiple overlapping uplink transmission units.
19. A computer-readable storage medium storing a computer program that causes a computer to execute the method of any one of claims 1 to 13.
20. A computer-readable storage medium storing a computer program that causes a computer to execute the method of any one of claims 14 to 18.
21. A user device, characterized in that it comprises:

    Transceiver; and

    The processor is connected to the transceiver and configured to perform the following steps, including:

    Sending user equipment downlink capability information used to indicate the processing capability of the user equipment for a plurality of overlapping downlink transmission units;

    Receiving the first transmission unit in the downlink transmission operation associated with the first hybrid automatic repeat request HARQ procedure;

    Receiving the second transmission unit in the downlink transmission operation associated with the second hybrid automatic repeat request HARQ procedure;

    Determining whether the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain; and

    When the first transmission unit and the second transmission unit overlap in at least one of the time domain and the frequency domain, the user equipment processes all areas according to the processing capabilities indicated by the user equipment downlink capability information. The first transmission unit and the second transmission unit, and the HARQ feedback of the first transmission unit and the second transmission unit.
22. A base station, characterized in that it comprises:

    Transceiver; and

    The processor is connected to the transceiver and configured to perform the following steps, including:

    Determining whether to receive user equipment downlink capability information indicating the processing capability of the user equipment for multiple overlapping transmission units;

    Sending the first transmission unit in the downlink transmission operation associated with the first hybrid automatic repeat request HARQ procedure;

    Sending the second transmission unit in the downlink transmission operation associated with the second hybrid automatic repeat request HARQ procedure; and

    When the HARQ feedback of one of the first transmission unit and the second transmission unit is received, but the HARQ feedback of the other transmission unit of the first transmission unit and the second transmission unit is not received , Perform the following steps:

    When the downlink capability information of the user equipment is received, it is determined according to the downlink capability information of the user equipment and the received HARQ feedback that the first transmission unit and the second transmission unit need to be reproduced. Transmission unit of transmission.

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