A Hybrid Automatic Repeat Request Method for an NR System

Abstract

The present invention discloses a hybrid automatic repeat request (HARQ) method for a New Radio (NR) system, which includes a base station transmitting scrambled data to a user equipment (UE) through a Physical Downlink Shared Channel (PDSCH) and a Physical Downlink Control Channel (PDCCH); the UE receiving the data from the base station, descrambling the data, performing a Cyclic Redundancy Check (CRC) on the descrambled data to determine the service type; if it is a joint service, the UE selects an Opportunistic CharQ (OCCHARQ) scheme for data decoding, if the service is a Ultra-Reliable Low-Latency Communication (URLLC) or Enhanced Mobile Broadband (eMBB) single service, the UE selects a Chase Combining - Hybrid Automatic Repeat Request (CC-HARQ) scheme for data decoding, judging whether the decoding failure probability meets a threshold, if not satisfied, the UE feeds back a negative acknowledgment signal (NACK), and repeats the above steps until the decoding failure probability meets the set requirements; if the decoding failure probability P meets the set requirements, the UE feeds back an acknowledgment signal (ACK), and the data reception is completed. The present invention ensures both the reliability and low latency of the URLLC service.

Description

Technical Field

[0001] The present invention relates to a hybrid automatic repeat transmission method for a NR system, and belongs to the technical field of mobile communications. Background Art

[0002] The emerging 5G (5th Generation Mobile Communication Technology) network supports a variety of applications and services, especially three main types of services:

[0003] (1) eMBB (Enhanced Mobile Broadband), for longer flows that require high network throughput;

[0004] (2) URLLC (Ultra Reliable & Low Latency Communication), which supports mission-critical applications such as real-time telemedicine and autonomous vehicles;

[0005] (3) Massive Machine Type Communication (mMTC) in the Internet of Things (IoT). For URLLC services, current technologies have proposed a high reliability of 99.9999% and a one-way air interface latency of 0.5 to 1 ms.

[0006] However, since multiple network services may exist simultaneously in NR, in the joint service of URLLC and eMBB, if the eMBB service is sent first, when the duration of the eMBB data is as high as 1ms, it will cause the URLLC data packet to have a large delay, which is very unfavorable for the URLLC service with high latency requirements. Summary of the invention

[0007] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a hybrid automatic repeat transmission method for an NR system, which ensures both the reliability and low latency of the URLLC service.

[0008] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0009] The present invention provides a hybrid automatic repeat transmission method of a NR system, comprising:

[0010] Detect the data received by the base station and scramble the data to be sent to the user end with a group of cell radio network temporary identifiers C-RNTI allocated by the high layer;

[0011] The scrambled data is transmitted from the base station to the user equipment via the Physical Downlink Shared Channel (PDSCH) and the Physical Downlink Control Channel (PDCCH).

[0012] The data received by the user equipment from the base station is descrambled, and the descrambled data is subjected to Cyclic Redundancy Check (CRC) to determine the service type.

[0013] If the service type is Ultra-Reliable Low-Latency Communication (URLLC) or Enhanced Mobile Broadband (eMBB) single service, the OCCHARQ scheme is selected for data decoding; if it is a joint service, the CC-HARQ scheme is selected for data decoding.

[0014] Determine whether the decoding failure probability meets the threshold. If the decoding failure probability P meets the set requirements, an Acknowledgment (ACK) signal is fed back from the user equipment and the data reception is completed. If not, a Negative Acknowledgment (NACK) signal is fed back from the user equipment, and the scrambled data is re-transmitted from the base station to the user equipment via the PDSCH and the PDCCH, and data decoding is performed at the user equipment until the decoding failure probability meets the set requirements.

[0015] Furthermore, the C-RNTI is a set of primary and secondary data allocated by the higher layer, including two identity identification information, namely the secondary C-RNTI and the primary C-RNTI, allocated by the base station side. The values of the two identity identification information are different. When only the primary C-RNTI is used for scrambling, it represents URLLC service data. When the secondary C-RNTI is used for scrambling, it represents eMBB service data. If both the primary and secondary C-RNTIs are used for scrambling simultaneously, it represents URLLC / eMBB joint service.

[0016] Furthermore, the C-RNTI is represented by 16-bit binary. During scrambling, the bits of the 16-bit binary of the C-RNTI are subjected to modulo-2 addition with the CRC added to the data stream part to complete the scrambling operation.

[0017] Furthermore, in the OCCHARQ scheme, (1) after the data is descrambled and CRC-checked, regardless of whether eMBB data is being processed, the URLLC service is decoded first; (2) if the reception decoding fails, the base station will re-transmit the same packet, and each transmitted data packet is decoded independently of the previous packets. At the k-th transmission, the receiver combines the data received in the previous k - 1 times and decodes the data received at the k-th time using Maximum Ratio Combining (MRC), where In the formula is The decoding failure probability at the k-th transmission is As shown in formula (1):

[0018]

[0019] Wherein, a and g are parameters derived according to the modulation and demodulation scheme MCS, is the maximum signal-to-interference-plus-noise ratio SINR when the decoding failure probability is 1, calculated according to MCS, is the signal-to-noise ratio at the k-th transmission of the data packet.

[0020] Furthermore, in the joint service, if eMBB is PDSCH1 and URLLC is PDSCH2, although the PDSCH1 process is before PDSCH2, when PDSCH2 arrives, the decoding of PDSCH1 is stopped and PDSCH2 is decoded preferentially.

[0021] Furthermore, in the CC-HARQ scheme, if the receiving decoding fails, the base station will retransmit the same packet, and the decoding failure probability of the k-th time is calculated by formula (1). In the CC-HARQ scheme, the data packet transmitted each time is decoded independently of the previous packets. At the k-th transmission, the receiver combines the data received in the previous k - 1 times and decodes the data received at the k-th time using maximum ratio combining MRC, where in the formula is At this time, the decoding failure probability at the k-th transmission is

[0022] Furthermore, the decoding failure probability where K in the formula is the number of successful transmissions, is the decoding failure probability at the k-th transmission.

[0023] Furthermore, when the decoding failure probability P does not reach the threshold, if it is a single service, NACK is directly fed back to the base station; if it is a joint service, the URLLC service is decoded preferentially. If the URLLC decoding fails, it means that all decodings fail, and NACK is fed back to the base station.

[0024] Compared with the prior art, the beneficial effects achieved by the present invention:

[0025] The present invention provides a hybrid automatic repeat request method for an NR system. By supporting the multiplexing of URLLC services and eMBB services in the NR system and adopting the OCCHARQ scheme, both the reliability of the URLLC service and low latency are ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the system model of the NR system provided by the embodiment of the present invention;

[0027] Figure 2 is a flowchart of the hybrid automatic repeat request method for the NR system provided by the embodiment of the present invention;

[0028] Figure 3 It is a schematic diagram of the modulation and demodulation solution provided by an embodiment of the present invention;

[0029] Figure 4 It is a schematic diagram of the order of receiving and processing two PDSCHs in the OCCHARQ solution provided by an embodiment of the present invention. Detailed implementation manners

[0030] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0031] Embodiment 1

[0032] As Figure 1 shown, this embodiment is the service multiplexing between the same base station and the same user. The service multiplexing within the user means that under the same serving base station, the receiving user of the eMBB service and the receiving user of the URLLC service are the same user. In this case, even if there is no time-domain conflict between the two services, serious problems may still occur. Since the two services have different requirements for latency, the corresponding HARQ-ACK timings are also different, and it is very likely that there is a need for non-sequential feedback, that is, the PDSCH of the later-arriving URLLC service needs to be fed back earlier than the PDSCH of the earlier-arriving eMBB service. As Figure 4 shown, in the OCCHARQ solution, eMBB is PDSCH1 and URLLC is PDSCH2. Although the PDSCH1 process is before PDSCH2, PDSCH2 is fed back first, ensuring the low latency of the URLLC service.

[0033] As Figure 2 shown, this embodiment introduces a hybrid automatic repeat request method for an NR system, including:

[0034] Step 1: The base station checks the received data and scrambles a group of C-RNTIs (Cell-Radio Network Temporary Identifier) assigned at the high layer for the data to be sent to the user terminal;

[0035] Step 2: The base station transmits the scrambled data through the PDSCH (Physical Downlink Shared Channel) & PDCCH (Physical Downlink Control Channel);

[0036] Step 3: The user terminal receives the data from the base station, descrambles the data, performs a CRC (Cyclic Redundancy Check Code) check on the descrambled data, and determines the service type;

[0037] Step 4: If the service is ultra-reliable and low-latency communication (URLLC) or enhanced mobile broadband (eMBB) single service, go to Step 6; if it is a joint service, go to Step 5;

[0038] Step 5: The user side selects the OCCHARQ (Out-Of-Orde Chase Combining HARQ) scheme for data decoding and enters Step 7;

[0039] Step 6: The user side selects the CC-HARQ scheme for data decoding and enters Step 7;

[0040] Step 7: Determine whether the decoding failure probability meets the threshold. If the decoding failure probability P satisfies δ = 10 -6 requirements, go to Step 9; if not, go to Step 8;

[0041] Step 8: The user side feeds back a negative acknowledgment signal (NACK) and enters Step 2. Repeat the above steps until the decoding failure probability meets 10 -6 requirements;

[0042] Step 9: The user side feeds back an acknowledgment signal (ACK), and the data reception is completed.

[0043] In this embodiment, in Step 1, the C-RNTI is a set of primary and secondary data assigned by the higher layer, including two identity identification information assigned by the base station side for the secondary C-RNTI and the primary C-RNTI. The values of the two identity identification information are different and are both represented by 16 bits. When only scrambled by the primary C-RNTI, it represents URLLC service data. When scrambled by the secondary C-RNTI, it represents eMBB service data. If scrambled by both the primary and secondary C-RNTIs simultaneously, it represents URLLC / eMBB joint service.

[0044] In this embodiment, in Step 1, the C-RNTI is represented by 16-bit binary. When scrambling, modulo-2 addition is performed on the 16-bit binary bits of the C-RNTI and the CRC added to the data stream part to complete the scrambling operation.

[0045] In this embodiment, in Step 5, in the OCCHARQ scheme, (1) After the data is descrambled and CRC-checked, regardless of whether it is processing eMBB data, the URLLC service is decoded first; (2) If the reception decoding fails, the base station will retransmit the same packet, and each transmitted data packet is decoded independently of the previous packets. At the kth transmission, the receiver combines the data received in the previous (k - 1) times and uses MRC (Maximum Ratio combination) to decode the data received at the kth time, where In the formula is The decoding failure probability at the k-th transmission is As shown in formula (1):

[0046]

[0047] In the formula, a and g are parameters derived according to MCS (Modulation and Coding Scheme), as Figure 3 shown, is the maximum signal-to-interference-plus-noise ratio SINR when the decoding failure probability is 1, calculated according to MCS, is the signal-to-noise ratio of the data packet at the k-th transmission.

[0048] In this embodiment, in step 5, in the joint service, if eMBB is PDSCH1 and URLLC is PDSCH2, although the PDSCH1 process is before PDSCH2, when PDSCH2 arrives, the decoding of PDSCH1 is stopped and PDSCH2 is preferentially decoded.

[0049] In this embodiment, in step 6, in the CC-HARQ scheme, if the received decoding fails, the base station will retransmit the same packet. The decoding failure probability pk at the k-th time is calculated by formula (1). In the CC-HARQ scheme, each transmitted data packet is decoded independently of the previous packets. At the k-th transmission, the receiver combines the data received in the previous (k - 1) times and uses MRC (Maximum Ratio combination) to decode the data received at the k-th time, where In the formula is The decoding failure probability at the k-th transmission is

[0050] In this embodiment, in step 7, the decoding failure probability In the formula, K is the number of successful transmissions.

[0051] For joint services, if eMBB uses PDSCH1 and URLLC uses PDSCH2, although the PDSCH1 process comes before PDSCH2, when PDSCH2 arrives, stop decoding PDSCH1 and preferentially decode PDSCH2. If the URLLC service decoding fails, indicating that all decoding has failed, immediately feedback NACK to the base station for both. The base station immediately retransmits all data and selects the OCCHARQ scheme, repeating the above steps until the URLLC service decoding is successful and ACK is feedback to the base station. Subsequently, process the eMBB data. If the decoding is successful, feedback ACK to the base station, and the joint service processing is completed; if the decoding fails, feedback NACK to the base station. At this time, retransmit the eMBB data and select the CC-HARQ scheme until the decoding is successful and ACK is feedback to the base station; as Figure 4 shown.

[0052] The present invention provides a hybrid automatic repeat transmission method for OCCHARQ (Out-Of-Orde ChaseCombining HARQ, out-of-order Chase combining HARQ) that supports hybrid service multiplexing in an NR system. The method described above not only ensures the reliability requirements of the URLLC service but also reduces the number of retransmissions of the URLLC service to a certain extent, ensuring the low-latency requirements of the URLLC service.

[0053] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principles of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A hybrid automatic repeat request method for a NR system, characterized in that Including: Detecting the data received by the base station, and scrambling a group of Cell Radio Network Temporary Identifiers (C-RNTIs) for the data to be sent to the user terminal for high-layer allocation; Transmitting the scrambled data from the base station to the user terminal through the Physical Downlink Shared Channel (PDSCH) and the Physical Downlink Control Channel (PDCCH); Descrambling the data received by the user terminal from the base station, performing Cyclic Redundancy Check (CRC) on the descrambled data, and determining the service type; If the service type is Ultra-Reliable Low-Latency Communication (URLLC) or Enhanced Mobile Broadband (eMBB) single service, select the OCCHARQ scheme for data decoding; if it is a joint service, select the CC-HARQ scheme for data decoding; In the OCCHARQ scheme, (1) after data is descrambled and CRC-checked, regardless of whether eMBB data is being processed, URLLC services are preferentially decoded; (2) if the reception decoding fails, the base station will retransmit the same packet, and each transmitted data packet is decoded independently of the previous packets. At the k-th transmission, the receiver combines the data received in the previous k - 1 times and uses Maximum Ratio Combining (MRC) to decode the data received at the k-th time, where In the formula is ( ), at this time the decoding failure probability at the k-th transmission is , as shown in formula (1): ； where a and g are parameters derived according to the modulation and demodulation scheme MCS, is the maximum signal-to-interference-plus-noise ratio SINR when the decoding failure probability is 1, calculated according to MCS, is the signal-to-noise ratio at the k-th transmission of the data packet; In the CC-HARQ scheme, if the receiving and decoding fails, the base station will retransmit the same packet, and the decoding failure probability for the k-th time is calculated by formula (1). In the CC-HARQ scheme, each transmitted data packet is decoded independently of the previous packets. At the k-th transmission, the receiver combines the data received in the previous k - 1 times and uses maximum ratio combining (MRC) to decode the data received at the k-th time, where in the formula is , and at this time, the decoding failure probability at the k-th transmission is ; Judging whether the decoding failure probability meets the threshold. If the decoding failure probability P meets the set requirements, feedback an Acknowledgment (ACK) signal from the user terminal, and the data reception is completed. If not, feedback a Negative Acknowledgment (NACK) signal from the user terminal, re-transmit the scrambled data from the base station to the user terminal through the PDSCH and the PDCCH, and perform data decoding at the user terminal until the decoding failure probability meets the set requirements.

2. The hybrid automatic repeat request transmission method of the NR system according to claim 1, wherein The C-RNTI is a group of primary and secondary data allocated at the high layer, including two identity identification information allocated for the secondary C-RNTI and the primary C-RNTI on the base station side. The values of the two identity identification information are different. When only scrambled with the primary C-RNTI, it represents URLLC service data. When scrambled with the secondary C-RNTI, it represents eMBB service data. If scrambled with both the primary and secondary C-RNTIs at the same time, it represents URLLC / eMBB joint service.

3. The hybrid automatic repeat request method of the NR system according to claim 2, wherein The C-RNTI is represented by 16-bit binary. During scrambling, modulo 2 addition is performed on the 16-bit binary bits of the C-RNTI and the CRC added to the data stream part to complete the scrambling operation.

4. The hybrid automatic repeat request method of the NR system according to claim 1, wherein In the joint service, if eMBB is PDSCH1 and URLLC is PDSCH2, although the PDSCH1 process is before PDSCH2, when PDSCH2 arrives, stop the decoding of PDSCH1 and preferentially decode PDSCH2.

5. The hybrid automatic repeat request method of the NR system according to claim 1, wherein Decoding failure probability , where K is the number of successful transmissions, is the decoding failure probability of the k-th transmission.

6. The hybrid automatic repeat request method of the NR system according to claim 1, wherein When the decoding failure probability P does not reach the threshold, if it is a single service, directly feedback NACK to the base station; if it is a joint service, preferentially decode the URLLC service. If the URLLC decoding fails, it means that all decodings fail, and feedback NACK to the base station.

Images