CN109246063B

CN109246063B - L SB (Business card Specification) wrapping optimization method and device

Info

Publication number: CN109246063B
Application number: CN201710560376.1A
Authority: CN
Inventors: 程岳
Original assignee: Datang Mobile Communications Equipment Co Ltd
Current assignee: Datang Mobile Communications Equipment Co Ltd
Priority date: 2017-07-11
Filing date: 2017-07-11
Publication date: 2020-07-31
Anticipated expiration: 2037-07-11
Also published as: CN109246063A

Abstract

The application discloses aL SB loop-back optimization method and device, the method includes recording the time T of receiving PDU when the R L C layer receives PDU submitted by MAC layer_iThe method comprises the steps of sending voice SDUs corresponding to the PDU to a PDCP layer, calculating an average time interval T of N voice SDUs before the currently received voice SDU at the PDCP layer, wherein N is a positive integer larger than or equal to 2, and determining whether the least significant bit L SB of a serial number SN in a real-time transmission protocol RTP packet is wrapped or not according to the average time interval T when the i-th complete voice packet a (i) fails CRC.

Description

L SB (Business card Specification) wrapping optimization method and device

Technical Field

The present application relates to the field of communications technologies, and in particular, to an L SB wrap-around optimization method and apparatus.

Background

In an L TE (L ong Term Evolution ) mobile communication network, VO L TE (Voice Over L TE, L TE-based Voice service) is an end-to-end Voice solution under all IP conditions, in which Voice data packets have the characteristics of periodic arrival and relatively fixed packet size, and Voice is encoded by AMR (Adaptive Multi-Rate) compression and then encapsulated into IP data packets for transmission.

For example: the maximum rate is 61 bytes for the broadband voice data packet of 23.85Kbps, but the ARM message header RTP (Real-time Transport Protocol), RTP/UDP (User Datagram Protocol)/IPv 6(Internet Protocol Version 6, Internet Protocol 6) reaches 60 bytes, so the actual utilization rate of the air bandwidth is only about 50%; the voice silence packet size is only 7 bytes, but the packet Header reaches 60 bytes, the bandwidth utilization rate is lower to 10%, and the ROHC (Robust Header Compression) protocol RFC3095 can compress the packet Header (e.g., the packet Header RTP/UDP/IPv6) to the extent of 1 to 3 bytes, so that the bandwidth utilization rate can reach more than 90% in general.

VO L TE voice data packet is generally transmitted in UM (Unacknowledged Mode) in the access network protocol, because when the user is at a signal difference point, if VO L TE service is performed or concurrent transmission is generated with other services, packet loss may occur or voice packet overtime is not scheduled and discarded, leading to Wraparound (Wraparound) of L SB (L east Significant Bit) of SN (serial number) in RTP, and the base station or UE cannot confirm correct SN, leading to CRC (Cyclic Redundancy Check) error.

In order to solve the above problems, the conventional RFC3095 protocol 5.3.2.2.4 provides the following determination methodWhen the number of the continuous lost packets is judged to be larger than the numerical range which can be represented by the L SB bit K in the current packet type, the arrival time a (i) of the current packet i to be decompressed is recorded, the average arrival time interval T of 2 packets before i is recorded, and whether the time difference between a (i) and a (i-1) is larger than 2 or not is calculated^kT, if greater than 2^kT, SN reference SNv — ref is updated as: SNv _ ref +2^kWhen a product is implemented at present, the recorded ith Packet arrival time a (i) is the time when the ROHC Protocol module receives a Packet to be decompressed, that is, the time when the Packet arrives at the ROHC Protocol module after being processed by the Protocol layers of R L C (Radio L inkControl, Radio link layer control Protocol) and PDCP (Packet Data Convergence Protocol).

Since the time a (i) of packet arrival is recorded as the time when the ROHC Protocol module receives the voice packet, the processing delay of the underlying radio Protocol stack below ROHC is considered to be fixed, but in essence, the radio system is a system that is time-varying according to the quality scheduling capability of the air interface, there is often a phenomenon that when the UE is at a bad point, it is not possible to send a complete voice packet within one TTI time, and therefore it is necessary for the base station or UE to divide a voice packet into a plurality of smaller fragments (i.e., R L CSegment) at the R L C layer, and transmit the smaller fragments within a plurality of TTIs, during which, due to the MAC (Media Access Control, Media Access Control sublayer Protocol) layer, a reception window is set at the R L C Protocol layer for ordering, and due to the possibility of packet loss at the air interface, the UM mode R L C receiver retransmits a PDU (Protocol Data Unit, PDU of the PDU (Protocol Data Unit) at the delivery layer only if the reordering timer has expired, the PDU is a, the time when the packet arrival at the time a (i) of the packet is not greater than the time a (i), and the subsequent packet transmission time when the packet is considered to be discarded, the PDU (R461), the packet is not greater than the PDU, and the PDU (PDU) of the PDU, the PDU is considered to be discarded, and the PDU after the retransmission time when the packet transmission time when the packet is considered to be discarded, the packet retransmission module (PDCP PDU (PDU +1) of the PDU, the PDU is not discarded, the PDU after the PDU is considered to be discarded, the PDU is not discarded, the PDU (PDU after the PDU is not discarded, and the PDU after the PDU is considered to be discarded, the PDU (PDU after the PDU is considered to be discarded, the PDU is considered.

In summary, in the conventional ROHC header compression algorithm, the method for determining whether L SB of SN has wrap-around cannot correctly determine the packet loss number and 2 in the time-varying system L TE^kThe size relationship of the packets, and therefore the reference value SNv _ ref cannot be updated correctly, which causes the CRC error of the decompressed voice packets to cause packet loss and affects the user perception and increases the packet loss rate index.

Disclosure of Invention

The application provides an L SB rewinding optimization method and device, which are used for solving the technical problem of high packet loss rate caused by a method for judging whether the SN L SB is rewound in the prior art.

In a first aspect, the present application provides an L SB wrap-around optimization method, comprising:

when a Protocol Data Unit (PDU) submitted by a Media Access Control (MAC) layer is received by a radio link control protocol (R L C) layer, recording the time T of receiving the PDU_i；

Sending a voice Service Data Unit (SDU) corresponding to the PDU to a Packet Data Convergence Protocol (PDCP) layer, and calculating an average time interval T of N voice SDUs before the currently received voice SDU at the PDCP layer; wherein N is a positive integer greater than or equal to 2;

when the i-th complete speech packet a (i) fails CRC, it is determined whether wrap-around occurs in the least significant bit L SB of the sequence number SN in the RTP packet according to the average time interval T.

In an implementable embodiment, determining whether a wrap-around of the least significant bit L SB of the sequence number SN in the real-time transport protocol RTP packet occurs based on the averaging time interval comprises:

judging the time T of receiving the ith PDU_iTime T of receiving (i-1) th PDU_i-1The difference isWhether or not it is not less than 2^kT, if yes, wrap around occurs, otherwise no wrap around occurs, where K is the number of bits of L SB.

In an implementation, sending the voice service data unit SDU corresponding to the PDU to a packet data convergence protocol PDCP layer includes:

and sending the received complete SDU corresponding to the PDU or the incomplete SDU with the length larger than a set threshold value and including the SDU header to the PDCP layer.

In an implementation, the set threshold is the sum of the sequence number length of the PDCP PDU and the basic packet length of the voice message type UOR-2.

In an implementation, when the i-th complete speech packet a (i) fails CRC, the method further comprises:

and judging whether the incomplete SDU is received or not, if so, comparing the L SB value of the SN field in the incomplete SDU with the L SB value a of the SN field in the a (i), and judging whether SN wrapping exists or not according to the comparison result.

In an implementation manner, the judging whether SN wraps around according to the comparison result comprises:

if the L SB value of the SN field analyzed from the packet header of the incomplete SDU is b, the L SB value of the SN field in the i-1 th complete voice packet a (i-1) is c, and the L SB value a of the SN field in a (i);

if a > c and b > -a, it is determined that wrap around has occurred, otherwise, no wrap around has occurred.

In an implementable embodiment, the method further comprises:

when the rewinding occurs, the reference value SNv _ ref for restoring the original value is updated to SNv _ ref1, SNv _ ref1 is SNv _ ref +2^k；

When the rewinding does not occur, the reference value SNv _ ref for restoring the original value is updated to SNv _ ref2, SNv _ ref2 is SNv _ ref-1.

In a second aspect, the present application also provides an L SB wrap-around optimization device, comprising:

recording unit for receiving medium access control protocol at radio link control protocol R L C layerWhen a Protocol Data Unit (PDU) is submitted by an MAC layer, the time T of receiving the PDU is recorded_i；

A sending unit, configured to send a voice service data unit SDU corresponding to the PDU to a packet data convergence protocol PDCP layer;

a calculating unit, configured to calculate, at the PDCP layer, an average time interval T at which N voice SDUs arrive before a currently received voice SDU; wherein N is a positive integer greater than or equal to 2;

and the judging unit is used for determining whether the least significant bit L SB of the sequence number SN in the RTP packet of the real-time transport protocol is wrapped according to the average time interval T when the i-th complete voice packet a (i) fails CRC.

In an implementation manner, the determining unit is specifically configured to determine a time T for receiving an ith PDU_iTime T of receiving (i-1) th PDU_i-1Whether the difference is not less than 2^kT, if yes, wrap around occurs, otherwise no wrap around occurs, where K is the number of bits of L SB.

In an implementation manner, the sending unit is specifically configured to send a complete SDU corresponding to the received PDU or a incomplete SDU with a length greater than a set threshold and including an SDU header to the PDCP layer.

In an implementation manner, the determining unit is further configured to determine whether the incomplete SDU is received, compare, if received, the L SB value of the SN field in the incomplete SDU with the L SB value a of the SN field in a (i), and determine whether SN wraps around according to the comparison result.

In an implementation manner, the determining unit determines whether SN wraps around according to the comparison result includes:

In an implementable embodiment, the apparatus further comprises:

a reference value updating unit for updating the reference value SNv _ ref of the restored original value to SNv _ ref1, SNv _ ref1 ═ SNv _ ref +2 when wrap-around occurs^k(ii) a When the rewinding does not occur, the reference value SNv _ ref for restoring the original value is updated to SNv _ ref2, SNv _ ref2 is SNv _ ref-1.

In a third aspect, the present invention further provides a computer apparatus, where the computer apparatus includes a processor, and the processor is configured to implement, when executing a computer program stored in a memory, the steps of the interface adjustment method in any one implementation manner selectable in the method provided in the first aspect.

In a fourth aspect, the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the interface adjustment method in any one of the optional implementations of the method provided in the first aspect.

The beneficial effect of this application is as follows:

the L SB wrap-around optimization method and device provided by the application have the advantages that when the R L C PDU is received from the MAC layer, timestamp information is printed on the R L C PDU, when the PDCP is submitted by the SDU analyzed from the R L C PDU, the timestamp of the R L C PDU where the SDU is located is submitted to the PDCP together for calculating the average arrival time of the packets and the receiving interval of the voice packets, the time of the R L C PDU received by the MAC layer can be used for calculating the transmission interval of the packets more accurately, the condition of the L SB wrap-around misjudgment of the SN can be avoided, the CRC verification success rate of a decompression end is improved, packet loss and frequent ROHC state migration are avoided, and the utilization rate of air interface bandwidth is improved.

Drawings

Fig. 1 is a schematic flowchart of an L SB wrap-around optimization method according to an embodiment of the present disclosure;

fig. 2 is a schematic diagram illustrating a format of a PDU including a PDCP SDU according to an embodiment of the present application;

fig. 3 is a schematic diagram illustrating a format of a PDU including a plurality of PDCP SDUs according to an embodiment of the present application;

FIG. 4 is a schematic structural diagram of an incomplete UO-1 packet provided in an embodiment of the present application;

FIG. 5 is a schematic diagram of a structure of a UOR-2 packet provided in an embodiment of the present application;

fig. 6 is a schematic structural diagram of an L SB wrap-around optimizing apparatus according to an embodiment of the present disclosure;

fig. 7 is a schematic structural diagram of an L SB wrap-around optimization apparatus according to an embodiment of the present application.

Detailed Description

According to the scheme provided by the embodiment of the application, the recorded receiving time of the RTP voice packet is the time of submitting R L C PDU by the MAC layer, the average arrival time of N voice packets before the currently received RTP voice packet is calculated according to the recorded time, the average arrival time is taken as the expected receiving interval of the two packets, and then whether the L SB of the SN in the RTP voice packet is rewound or not is calculated by using the receiving interval.

Example one

An L SB wrap-around optimization method provided by the embodiments of the present application is described in further detail below with reference to the drawings in the specification, and a specific implementation manner of the method may include the following steps (a method flow is shown in fig. 1):

step 101, when a radio link control protocol R L C layer receives a protocol data unit PDU submitted by a media access control protocol MAC layer, recording the time Ti for receiving the PDU;

when the R L C receives the PDU, time stamp information (e.g., Half frame number Half SFN) is stamped on the PDU, and when the reordering timer expires or the UM receiving window receives the delivered SDU (Service Data Unit) in sequence, the time stamp information is delivered to the PDCP protocol layer together.

Step 102, sending a voice service data unit SDU corresponding to the PDU to a packet data convergence protocol PDCP layer, and calculating an average time interval T of arriving N voice SDUs before a currently received voice SDU on the PDCP layer; wherein N is a positive integer greater than or equal to 2;

and 103, when the i-th complete voice packet a (i) fails in CRC, determining whether the least significant bit L SB of the sequence number SN in the RTP packet of the real-time transport protocol is wrapped according to the average time interval T.

Optionally, a specific implementation manner of determining whether the least significant bit L SB of the sequence number SN in the RTP packet of the real-time transport protocol is wrapped according to the average time interval may be:

judging the time T of receiving the ith PDU_iTime T of receiving (i-1) th PDU_i-1Whether the difference is not less than 2^kT, if yes, wrap around occurs, otherwise no wrap around occurs, where K is the number of bits of L SB.

In this embodiment, the obtained arrival time of the data packet is the exact time of successful air interface transmission, and the packet transmission interval can be calculated more accurately by using this time, so as to avoid the situation of L SB wrap-around misjudgment of the SN.

Further, because the MAC layer HARQ processes and retransmissions are possible, the time when the R L C layer may receive the PDUs is in reverse order, when this happens, the time stamp of the R L C PDU is set according to the sequence number SN of the R L C PDU, because at the sending side, the time point of the previous data packet transmission must be prior to the next R L C PDU, when delivering the SDU to the PDCP, the time stamp information of the ith SDU is the same as the time stamp of the ith-1 SDU, and it is determined whether the length of the voice payload in the ith SDU is a silence packet or an activation packet, if the SDU is a silence packet, the time stamp of the ith-1 SDU is updated to be 160ms, and if the SDU is an activation packet, the time stamp of the ith-1 SDU is updated to be 20 ms.

In a specific implementation, when the length of a receiving window of an R L C entity in UM mode is 10 for an R L C PDU SN, the window length is 512, when a transmitting end of R L C is used, a PDU of PDCP is used as an SDU of an R L C layer and is disassembled into a plurality of R L C PDUs, and the PDUs need to be combined in sequence at the receiving end to be recovered into SDUs normally, because of multi-HARQ process transmission or air interface packet loss at a MAC layer, a receiving window of R L C needs to be set at the receiving end to wait for a packet that arrives discontinuously, when a GAP is detected and a packet cannot be packed, a reordering timer is started for a period of time, and if the timer is overtime, the missing packet cannot be obtained in an incorrect manner, the receiving window slides, and a complete SDU is completely submitted outside the window, that is discarded, that is R L C is used when a PDCP layer is packed and submitted to the PDCP layer, a complete SDU is submitted to the PDCP layer only, and when a packet header of a packet that is not received from a beginning or tail of an intermediate data is received, the PDCP, a packet header of the packet, a packet compression method that is implemented by a TS compression method, and a packet header of a packet compression packet including an SN compression packet header of a packet, and a packet header of an embodiment (including an SN compression method for implementing a packet) including:

in a specific embodiment, the method for calculating the average arrival time interval of the packets in steps 101 to 103 is more suitable for the case of continuous silent voice packets or activated packets, and for the packets that are activated by silence and may be switched at any time, the following method may be adopted to assist in the determination:

and A, sending the received complete SDU corresponding to the PDU or the incomplete SDU with the length larger than a set threshold value and including the SDU message header to the PDCP layer.

In this embodiment, the set threshold L en may be set to L en ═ sequence number length of PDCP PDU + basic packet length of voice packet type UOR-2(UOR-2 is a type of compressed voice packet in header compression protocol RFC 3095), and the default value may be 2+3 ═ 5.

In a specific embodiment, determining whether the SDU corresponding to the PDU is a complete SDU or a defective SDU may include:

in the 3GPP TS 36.322 protocol, when the SN length of R L C PDU is 10, the PDU includes one PDCP SDU in the format as shown in fig. 2, and when there is no L I field, FI ═ 01 indicates that the PDU includes the beginning of one PDCP SDU, and FI ═ 00 indicates that the PDU includes one complete PDCP SDU.

The format of the PDU containing a plurality of PDCP SDUs is shown in fig. 3, and in this embodiment, there is an L I field, specifically:

FI 00 indicates that at least two complete PDCP SDUs are included in the PDU.

FI 01 denotes the beginning of the PDU containing at least one complete PDCP SDU and one PDCP SDU.

FI 10 indicates that at least one complete PDCP SDU is contained in the PDU.

FI 11 indicates that the PDU may contain the complete PDCP SDU.

After receiving voice R L C PDU with QCI of 1, the R L C protocol layer at the decompression end resolves whether FI field and L I field exist in the header of R L C PDU, if L I field does not exist, but FI field is 00 or 01, or L I field exists, and time stamp information is printed on the R L C PDU.

B, when the i-th complete voice packet a (i) fails CRC check, judging whether the incomplete SDU is received, if so, comparing the L SB value of the SN field in the incomplete SDU with the L SB value a of the SN field in a (i), wherein the concrete implementation of the comparison can be as follows:

And C, judging whether SN is rewound according to the comparison result.

In a specific embodiment, SN of 0x11 in the current context (L SB bit: 0001), 1 st UO-0 packet is received, but R L C notifies a non-complete voice packet, SN L SB bit is 1000, 2 nd UO-0 complete voice packet is received, SN L SB bit is 0010, at this time, it can be determined that SN wraps around, SN in 2 nd UO-0 packet can be restored to 0 × 22, further, since voice silence and active period are possibly reversed when packet loss continues, R L C reports a non-complete packet, which helps ROHC module to obtain TS _ SCA L E value in packet type, for example, report a non-complete UO-1 packet, the packet type of UO-1 packet is shown in fig. 4, where 10 bits of the first byte represents packet type, TS bits represents SB 5 bits of TS-SCA L E, for updating TS-L and calculating TS-483 value, and further, the header of the un-0 SN-0 packet may include a synchronization header of a further packet (or 5).

After determining L SB whether wrap-around occurs based on the above method, the reference value for restoring the original value may be updated in the following manner:

when the rewinding occurs, the reference value SNv _ ref for restoring the original value is updated to SNv _ ref1, SNv _ ref1 is SNv _ ref +2^kWherein K is the number of L SB;

Step 104, setting a decoding interval, calculating the serial number SN of the RTP packet according to the W L SB algorithm, further calculating TS, decompressing the data packet and calculating CRC.

Wherein, the decoding interval may be: [ SNv _ ref1+1, SNv _ ref1+2^k]

Step 105: if the CRC is successfully calculated, quitting, if the CRC is unsuccessfully calculated, the default rewinding and the rollback are recalculated once again, and the calculation times are more than the set times, and the NACK flow is executed.

After the new calculation, if no wrap-around occurs, the updated reference value is SNv _ ref +2^k。

When the rewinding occurs, the updated reference value is SNv _ ref-1;

the decoding interval is set to [ SNv _ ref1+1, SNv _ ref1+2k ] according to W L SB algorithm, calculating the SN of the serial number of RTP packet, and further calculating TS, decompressing data packet and calculating CRC.

Example two

As shown in fig. 6, based on the same inventive concept of the method provided in the first embodiment, the first embodiment of the present invention further provides an L SB wrap-around optimizing apparatus, which includes:

a recording unit 601, configured to record, when receiving a protocol data unit PDU submitted by a medium access control protocol MAC layer in a radio link control protocol R L C layer, a time T of receiving the PDU_i；

A sending unit 602, configured to send a voice service data unit SDU corresponding to the PDU to a packet data convergence protocol PDCP layer;

a calculating unit 603, configured to calculate, at the PDCP layer, an average time interval T of arrival of N voice SDUs before a currently received voice SDU; wherein N is a positive integer greater than or equal to 2;

the determining unit 604 is configured to determine whether the least significant bit L SB of the sequence number SN in the RTP packet of the real-time transport protocol is wrapped around according to the average time interval T when the i-th complete voice packet a (i) fails to perform CRC check.

Optionally, the determining unit is specifically configured to determine a time T for receiving the ith PDU_iTime T of receiving (i-1) th PDU_i-1Whether the difference is not less than 2^kT, if yes, wrap around occurs, otherwise no wrap around occurs, where K is the number of bits of L SB.

Optionally, the sending unit is specifically configured to send a complete SDU corresponding to the PDU or a incomplete SDU with a length greater than a set threshold and including an SDU header to the PDCP layer.

Optionally, the determining unit is further configured to determine whether the incomplete SDU is received, and if the incomplete SDU is received, compare the L SB value of the SN field in the incomplete SDU with the L SB value a of the SN field in the a (i), and determine whether SN wraps around according to the comparison result.

Optionally, the determining, by the determining unit, whether SN is wrapped according to the comparison result includes:

Optionally, the apparatus further comprises:

EXAMPLE III

Based on the same inventive concept, an L SB wrap-around optimization apparatus is provided in an embodiment of the present invention, and specific implementation of the apparatus may refer to the description of the method embodiment, and repeated parts are not repeated, as shown in fig. 7, the apparatus mainly includes a processor 701 and a memory 702, where the memory 702 stores a preset program, and the processor 701 reads the program in the memory 702, and executes the following processes according to the program:

when the i-th complete speech packet a (i) fails the CRC check, it is determined whether the least significant bit L SB of the sequence number SN in the RTP packet of the real-time transport protocol is wrapped around according to the average time interval T.

Optionally, determining whether the least significant bit L SB of the sequence number SN in the RTP packet of the real-time transport protocol is wrapped according to the average time interval includes:

Optionally, sending the voice service data unit SDU corresponding to the PDU to the packet data convergence protocol PDCP layer includes:

Optionally, the set threshold is the sum of the sequence number length of the PDCP PDU and the basic packet length of the voice message type UOR-2.

Optionally, when the i-th complete voice packet a (i) fails the CRC check, the method further includes:

Optionally, the determining whether SN is wrapped according to the comparison result includes:

Optionally, the method further includes:

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims

1. An L SB optimization method, comprising:

when the i-th complete speech packet a (i) fails the cyclic redundancy check CRC, it is determined whether the least significant bit L SB of the sequence number SN in the RTP packet of the real-time transport protocol is wrapped around according to the average time interval T.

2. The method of claim 1, wherein determining whether a wrap-around occurs for the least significant bit L SB of the sequence number SN in a real-time transport protocol RTP packet based on the averaging time interval comprises:

3. The method of claim 1, wherein sending voice Service Data Units (SDUs) corresponding to the PDUs to a Packet Data Convergence Protocol (PDCP) layer comprises:

4. The method of claim 3, wherein the set threshold is a sum of a sequence number length of the PDCP PDU and a basic packet length of the voice message type UOR-2.

5. The method according to claim 3, wherein when the i-th complete speech packet a (i) fails CRC, the method further comprises:

and judging whether the incomplete SDU is received or not, if so, comparing the L SB value of the SN field in the incomplete SDU with the L SB value a of the SN field in the a (i), and judging whether SN wraps around or not according to the comparison result.

6. The method of claim 5, wherein determining whether the SN wraps around based on the comparison comprises:

7. The method of any of claims 1 to 6, further comprising:

when the rewinding occurs, the reference value SNv _ ref for restoring the original value is updated to SNv _ ref1, SNv _ ref1 is SNv _ ref +2^kWherein K is the number of bits of L SB;

8. An L SB loop-back optimization device, comprising:

a recording unit, configured to record, when a protocol data unit PDU submitted by a medium access control protocol MAC layer is received by a radio link control protocol R L C layer, a time T of receiving the PDU_i；

9. The apparatus as claimed in claim 8, wherein the determining unit is specifically configured to determine the time T for receiving the ith PDU_iTime T of receiving (i-1) th PDU_i-1Whether the difference is not less than 2^kT, if yes, wrap around occurs, otherwise no wrap around occurs, where K is the number of bits of L SB.

10. The apparatus of claim 8, wherein the sending unit is specifically configured to send a complete SDU or a missing SDU with a length greater than a set threshold and including an SDU header, corresponding to the received PDU, to the PDCP layer.

11. The apparatus of claim 10, wherein the determining unit is further configured to determine whether the malformed SDU is received, compare L SB value of SN field in the malformed SDU with L SB value a of SN field in a (i) if received, and determine whether SN wraps around according to the comparison result.

12. The apparatus of claim 11, wherein the determining unit determines whether SN wraps around according to the comparison result comprises:

13. The apparatus of any of claims 8 to 12, further comprising:

a reference value updating unit for updating the reference value SNv _ ref of the restored original value to SNv _ ref1, SNv _ ref1 ═ SNv _ ref +2 when wrap-around occurs^kWhere K is the number of bits of L SB, the reference value SNv _ ref for restoring the original value is updated to SNv _ ref2 when wrap-around does not occur, SNv _ ref2 is SNv _ ref-1.