CN101540634B - Uplink synchronisation method, base station, terminal and communication system - Google Patents

Abstract

The invention discloses an uplink synchronization method, a base station, a terminal and a communication system. One of the uplink synchronization methods includes: receiving a MAC PDU sent by the base station, the MAC PDU includes a TA value; identifying whether the TA value is the TA value of the sounding reference signal according to the TA value identification information in the MAC PDU; When the TA value is the TA value of the sounding reference signal, the time offset adjustment is performed according to the TA value. The embodiment of the present invention can identify whether the TA value in the MAC PDU is the TA value of the sounding reference signal or the TA value detected by the RACH according to the TA value identification information in the MAC PDU. Only when the TA value in the MAC PDU is the TA value of the sounding reference signal, Accordingly, a corresponding time offset adjustment is performed to ensure the uplink synchronization performance of the OFDM system.

Description

Uplink synchronization method, base station, terminal and communication system

technical field

The invention relates to communication technology, especially an uplink synchronization method, a base station, a terminal and a communication system.

Background technique

Orthogonal Frequency Division Multiplexing (hereinafter referred to as: OFDM) is the core technology of the fourth generation (the 4th Generation, hereinafter referred to as: 4G) mobile communication. Converts to a flat channel, thereby reducing the effects of multipath fading while improving spectrum utilization. However, the OFDM system is extremely sensitive to synchronization errors and has high requirements for time synchronization. In terms of frequency synchronization, frequency offset (abbreviation: frequency offset) will introduce inter-channel interference (Internal Channel Interference, hereinafter referred to as: ICI), that is: inter-carrier interference, which deteriorates the signal-to-noise ratio of each subcarrier, thereby deteriorating the entire Transmission performance of communication systems. The error of frame synchronization will introduce inter-symbol interference (Inter Symbol Interference, hereinafter referred to as: ISI), that is, inter-symbol interference, and will also have a serious impact on channel estimation. In the existing OFDM system, the following three types of synchronization methods are mainly adopted: symbol timing synchronization, carrier synchronization and sampling clock synchronization.

To realize OFDM signal synchronization, it is necessary to find the starting position and carrier offset of OFDM symbols. OFDM modulation technology is a multi-carrier technology, and there is a big difference between the symbol synchronization of an OFDM signal and the symbol synchronization of a single carrier signal. Since each OFDM symbol is composed of many sub-carriers, the multi-carrier system does not have an "eye diagram" like a single-carrier signal. Therefore, it is impossible to find the best sampling moment by analyzing the "eye diagram". Multi-carrier systems are more sensitive to timing deviation than single-carrier systems. When there is a cyclic prefix (Cyclic Prefix, hereinafter referred to as: CP), the timing synchronization of the OFDM signal to the symbol can only allow a limited error, allowing the timing to fall within the length of the CP, and the residual small deviation caused by Adverse effects can be eliminated by subsequent channel estimation. Since the OFDM system uses CP, when the length of CP is greater than the additional channel delay extension τ _max , there will be a non-interference area in the CP, that is: no ISI area, and the method of frequency domain estimation can be used in the non-interference area Corrects the phase rotation of the desired signal. Therefore, within the scope of the non-interference zone, the OFDM symbol will not be affected by the ISI from the previous OFDM symbol caused by the multipath channel. Outside this non-interference zone, timing errors will cause ISI and ICI to the OFDM system. At the same time, it will cause attenuation and phase rotation of useful signals. More seriously, it will seriously affect the performance of the channel estimator, thus increasing the channel estimation error. As shown in FIG. 1 , it is a schematic diagram of a data structure of OFDM symbols selected in a Fast Fourier Transform (Fast Fourier Transform, FFT for short) window. In FIG. 1 , 101 represents an ISI interference area, and 102 represents a non-interference area.

In the prior art, a user terminal (User Equipment, hereinafter referred to as: UE) sends a sounding reference (Sounding ) signal to achieve symbol timing synchronization.

After the baseband digital signal processing (Digital Signal Processing, hereinafter referred to as: DSP) in the eNB calculates the timing advance (Timing Advance, hereinafter referred to as: TA) of the sounding reference signal, through a sounding reference function and random access channel (Random Access Channel, hereinafter referred to as: RACH) detection function shared message, will report the TA value detected based on the sounding reference to the medium access control (Medium Access control, hereinafter referred to as: MAC) module in the base station. Among them, TA is also adjusted in real time. The MAC module sends the TA value to the UE through the MAC protocol data unit (Protocol Data Unit, hereinafter referred to as: PDU), and the UE performs corresponding time offset adjustment according to the TA value, so as to realize the uplink synchronization of the OFDM signal.

In the process of realizing the present invention, the inventor found that when the prior art realizes the uplink synchronization of OFDM signals, there are at least the following problems:

Because the baseband DSP not only reports the TA value detected based on the sounding reference to the MAC module through the above message, but also reports the TA value detected based on the preamble (Preamble) sent by the RACH to the MAC module through the message, that is, the baseband DSP Through the same message, two TA values detected based on the sounding reference signal and the preamble are reported to the MAC module. The MAC module cannot distinguish whether the received TA value is based on the TA value detected by the sounding reference signal or based on the preamble. The detected TA value is not distinguished when sending the TA value to the UE through the MAC PDU. When the UE receives the TA value delivered by the MAC module, it cannot distinguish its type. Since the TA value detected based on the preamble has a relatively high probability of being wrong, the performance of time offset adjustment may be reduced, that is to say, it will cause The degradation of the uplink synchronization performance of the OFDM system. In addition, due to the influence of noise, there is a possibility of a false alarm when the UE detects the TA value. In this case, the performance of the time offset adjustment will be further affected.

Contents of the invention

Embodiments of the present invention provide an uplink synchronization method, a base station, a terminal, and a communication system, so as to correctly perform time offset adjustment according to a TA value of a sounding reference signal, thereby ensuring the uplink synchronization performance of the communication system.

An embodiment of the present invention provides an uplink synchronization method, including:

receiving the sounding reference signal reported by the terminal;

Acquiring a time advance TA value according to the sounding reference signal;

Sending a media access control MAC protocol data unit PDU to the terminal, the MAC PDU includes the TA value and TA value identification information, and the TA value identification information is used to identify that the TA value is the TA value of the sounding reference signal .

Another uplink synchronization method provided by an embodiment of the present invention includes:

Receive the MAC PDU sent by the base station, the MAC PDU includes TA value and TA value identification information;

identifying whether the TA value is the TA value of a sounding reference signal according to the TA value identification information;

When the TA value is the TA value of the sounding reference signal, time offset adjustment is performed according to the TA value.

A base station provided by an embodiment of the present invention includes:

The first receiving module is configured to receive the sounding reference signal reported by the terminal;

a calculation module, configured to obtain a TA value according to the sounding reference signal;

The sending module is configured to send a MAC PDU to the terminal, the MAC PDU includes the TA value and TA value identification information, and the TA value identification information is used to identify the TA value as the TA value of the sounding reference signal.

A terminal provided by an embodiment of the present invention includes:

The second receiving module is used to receive the MAC PDU sent by the base station, and the MAC PDU includes TA value and TA value identification information;

An identification module, configured to identify whether the TA value is the TA value of a sounding reference signal according to the TA value identification information;

An adjustment module, configured to adjust the time offset of the terminal according to the TA value when the TA value is the TA value of the sounding reference signal according to the identification result of the identification module, so that the terminal adjusts the time offset according to the time offset of the terminal. The adjusted result is communicated with the base station.

A communication system provided by an embodiment of the present invention includes a terminal and a base station, the base station is configured to receive a sounding reference signal reported by the terminal, obtain a TA value according to the sounding reference signal, and deliver a MAC PDU to the terminal , the MAC PDU includes the TA value and TA value identification information for identifying the TA value of the sounding reference signal;

The terminal is used to receive the MAC PDU issued by the base station, identify whether the TA value is the TA value of the sounding reference signal according to the TA value identification information in the MAC PDU, and determine whether the TA value is the TA value of the sounding reference signal When the TA value is selected, the time offset adjustment is performed according to the TA value.

Based on the uplink synchronization method, base station, terminal and communication system provided by the above embodiments of the present invention, when the base station sends the TA value of the sounding reference signal to the terminal, it can set the TA value used to identify the sounding reference signal in the MAC PDU After receiving the MAC PDU sent by the base station, the terminal can identify whether the TA value is the TA value of the sounding reference signal or the preamble detected by RACH according to the TA value identification information in the MAC PDU. TA value, only when the TA value in the MAC PDU is the TA value of the sounding reference signal, the corresponding time offset adjustment is performed accordingly, so as to ensure the uplink synchronization performance of the OFDM system and avoid the detection of the terminal based on the synchronization code in the prior art. The uplink synchronization performance of the OFDM system is degraded due to the time offset adjustment of the TA value.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a schematic diagram of the data structure of the OFDM symbol selected in the FFT window;

FIG. 2 is a flowchart of an embodiment of the uplink synchronization method of the present invention;

Fig. 3 is a schematic diagram of the amount of time offset adjustment in the embodiment shown in Fig. 2;

FIG. 4 is a flow chart of another embodiment of the uplink synchronization method of the present invention;

FIG. 5 is a schematic structural diagram of an embodiment of a base station of the present invention;

FIG. 6 is a schematic structural diagram of another embodiment of the base station of the present invention;

FIG. 7 is a schematic structural diagram of an embodiment of the UE of the present invention;

FIG. 8 is a schematic structural diagram of another embodiment of the UE of the present invention;

FIG. 9 is a schematic structural diagram of an embodiment of the communication system of the present invention;

Fig. 10 is a schematic structural diagram of another embodiment of the communication system of the present invention.

Detailed ways

In the embodiment of the present invention, when the base station sends the TA value of the sounding reference signal to the UE through the MAC PDU, the MAC PDU carries the TA value identification information used to identify the TA value as the TA value of the sounding reference signal, and the UE according to the TA value in the MAC PDU The TA value identification information can determine that the TA value is the TA value of the sounding reference signal, thereby distinguishing the TA value of the sounding reference signal from the preamble, and correctly adjusting the time offset according to the TA value of the sounding reference signal, thereby ensuring the communication system. Uplink synchronization performance. Various embodiments of the present invention can be applied to a Long Term Evolve (Long Term Evolve, hereinafter referred to as: LTE) system, and in the LTE system, a base station is specifically an eNB. In addition, each embodiment of the present invention can also be used in other communication systems, for example: wideband code division multiple access (Wideband Code Division Multiple Access, hereinafter referred to as: WCDMA) system, third generation (3rdGeneration, hereinafter referred to as: 3G) digital communication system wait.

As shown in FIG. 2, it is a flow chart of an embodiment of the uplink synchronization method of the present invention. The process of this embodiment can be implemented by the base station, which includes the following steps:

Step 201, receiving a sounding reference signal reported by a UE.

As a specific embodiment of the present invention, when the sounding reference function is activated, the UE does not send user data on the first symbol of each subframe, but sends a sounding reference signal separately.

Step 202, acquire a TA value according to the sounding reference signal.

Specifically, as a specific embodiment of the present invention, the UE can continuously send sounding reference signals through 32 subframes. After the baseband DSP module in the base station correctly receives the sounding reference signals, it can demodulate and interpret the received sounding reference signals. A series of processing such as code, get an array with a length of 128 points. Then search for the first path within the range of the array, for example, find the first point whose energy exceeds a preset threshold. If no point with energy exceeding the preset threshold is found, the maximum energy value is considered to be the head path. Calculate the distance from the head path to the 64th point in the array, and get how many points Ts the time deviation is ahead or behind. Since each point corresponds to a frequency band, by performing a linear correlation operation on Ts, and then performing a linear correlation operation on the time offset advance or lag point Ts, for example: TA=k·Ts, k is an empirical coefficient, and the TA value is obtained. As shown in FIG. 3 , it is a schematic diagram of the time offset adjustment amount in the embodiment shown in FIG. 2 .

Step 203: Send a MAC PDU to the UE, the MAC PDU includes a TA value and TA value identification information, and the TA value identification information is used to identify that the TA value is the TA value of the sounding reference signal.

Specifically, the operation process of the foregoing step 203 may be implemented through a MAC module in the base station.

As another embodiment of the present invention, between step 202 and step 203, an uplink synchronization message may also be reported to the MAC module, and the uplink synchronization message includes the TA value and the TA value identification information of the TA value. Correspondingly, in step 203, the MAC module sends a MAC PDU to the UE.

Specifically, the TA value identification information may be set according to a preset rule. As long as the TA value identification information of the SRS and the TA value of the preamble are different, it is sufficient to distinguish whether the TA value is the TA value of the SRS or the TA value of the preamble according to the TA value identification information. If it is pre-set to add the TA value identification information only for the TA value of the sounding reference signal, then only when the TA value is the TA value of the sounding reference signal, the TA value identification information is set in the uplink synchronization message; as an optional method , for the TA value of the sounding reference signal, the TA value flag can be left blank. If it is set in advance that only the TA value identification information is added to the TA value of the preamble, and the TA value identification information is not added to the TA value of the sounding reference signal, the TA value identification set in the uplink synchronization message is empty. If it is pre-set to set different TA value identification information for the TA value of the sounding reference signal and the TA value of the preamble detection, for example: for the TA value of the sounding reference signal, set the TA value identification information to 1, and for the preamble detection TA value, set the TA value identification information to 0, then according to the preset correspondence information between the TA value identification and the identified object, obtain the TA value identification information of the TA value of the sounding reference signal, and send it to the uplink synchronization message Set the corresponding TA value identifier in . The above-mentioned steps 201-202 and the operation process of reporting the uplink synchronization message to the MAC module can be specifically realized by the baseband DSP in the base station.

As a specific embodiment of the present invention, the uplink synchronization message may specifically be a BESA_DSP_GBL_STRU_RachRpt message, in which the TA value identification information may be set as a reserved bit before the TA value in the BESA_DSP_GBL_STRU_RachRpt message, and its number of bits may be equal to or less than eight bits. As shown in Table 1 below, it is another specific structure example of the BESA_DSP_GBL_STRU_RachRpt message. It can be seen from Table 1 that the variable uwTAid is set on the eight reserved bits before the TA value in the BESA_DSP_GBL_STRU_RachRpt message to record the TA value identification information.

Table 1 BESA_DSP_GBL_STRU_RachRpt message instance

Identification (Syntax) Bits (Sizebits) Notes uwSendCPUID 32 The unified serial number of the CPU on the board uwSendPID 32 There are several PIDs under each CPUID, and each subsystem (RRM, SSM, DSP0, DSP1...) corresponds to a PID, and the corresponding PID must be filled in when sending and receiving uwReceiveCPUID 32 The unified serial number of the CPU on the board uwReceivePID 32 There are several PIDs under each CPUID, and each subsystem (RRM, SSM, DSP0, DSP1...) corresponds to a PID, and the corresponding PID must be filled in when sending and receiving uwMsgLength 32 The convention is the length of the message packet entity behind the uwMsgLength field, in byte, excluding MsgLength

uwMsgType 32 message type indication uwTransactionID 32 For response messages, DSP backfills (RRM may send several messages of the same type, but the response may not be received before, and the upper layer guarantees that the number of times this mark is not repeated); for proactively reported messages, this field is invalid uwRsvWord 32 reserved bit uwFrmNo 20 frame number uwSubfrmNo 4 subframe number uwUserNum 8 The number of users performing Rach detection for(i=0; i<BESA_DSP_GBL_RACH_MAXUSER22_NUM; i++){ - The value of BESA_DSP_GBL_RACH_MAXUSER22_NUM is 22 uwPreambleIndex 8 Preamble sequence index uwTAid 8 TA flag usTimeAdjust 16 TA value } }

In the BESA_DSP_GBL_STRU_RachRpt message reported by the existing baseband DSP to the MAC module, the TA value flag is set on the 8 bits reserved before the usTimeAdjust variable that records the TA value, to distinguish whether it reports the TA value of the sounding reference signal or the TA of the preamble Value, without adding new messages, and without changing the existing message format, the MAC module and UE can distinguish the corresponding TA value, and push up the uplink synchronization performance.

As shown in FIG. 4, it is a flow chart of another embodiment of the uplink synchronization method of the present invention. The process of this embodiment can be implemented by the UE, which includes the following steps:

Step 301: Receive a MAC PDU sent by the base station, the MAC PDU includes TA value and TA value identification information.

Step 302: Identify whether the TA value in the MAC PDU is the TA value of the sounding reference signal according to the TA value identification information in the MAC PDU. If it is the TA value of the sounding reference signal, go to step 303 . Otherwise, if it is the TA value detected by RACH, the subsequent uplink synchronization procedure is not executed.

Step 303, time offset adjustment is performed according to the TA value.

In the embodiment of the present invention, according to the TA value identification information carried in the MAC PDU sent by the base station, the UE can distinguish whether the TA value is the TA value of the sounding reference signal or the TA value of the preamble, so as to ensure that the UE Correctly adjust the time offset with the TA value to ensure the uplink synchronization performance of the OFDM system.

Specifically, according to preset settings, if the base station only adds TA value identification information for the TA value of the sounding reference signal or preamble, then in step 302, it can be identified whether the TA value is a sounding value according to whether the TA value identification information is included in the MAC PDU. The TA value of the reference signal. If the base station sets different TA value identification information for the TA value of the sounding reference signal and the TA value of the preamble, for example: for the TA value of the sounding reference signal, set the TA value identification information to 1, and for the TA value of RACH detection, Set the TA value identification information to 0, then in step 302, according to the correspondence information between the preset TA value identification and the identified object, identify whether the identified object of the TA value identification information in the MAC PDU is a sounding reference signal.

As shown in FIG. 5 , it is a schematic structural diagram of an embodiment of a base station according to the present invention. The base station of this embodiment can be used to realize the process of the embodiment shown in FIG. 2 of the present invention. As shown in FIG. 5 , the base station in this embodiment includes a first receiving module 401 , a computing module 402 and a sending module 403 . Wherein, the first receiving module 401 is configured to receive the sounding reference signal reported by the UE. The calculation module 402 is used to perform demodulation and decoding processing according to the sounding reference signal received by the first receiving module 401, and calculate how many points the time offset is advanced or delayed, and further obtain the TA value. The sending module 403 is used to send a MAC PDU to the UE, and the MAC PDU includes the TA value calculated by the calculation module 402 and the TA value identification information, and the TA value identification information is used to identify the TA value as the TA value of the sounding reference signal. Specifically, the sending module 403 may be implemented by a MAC module.

As shown in FIG. 6 , it is a schematic structural diagram of another embodiment of the base station of the present invention. Compared with the embodiment shown in FIG. 5 , the base station of this embodiment also includes a reporting module 404 for reporting uplink A synchronization message, the uplink synchronization message includes the TA value calculated by the calculation module 402 and the TA value identification information. Specifically, the above-mentioned uplink synchronization message may be a BESA_DSP_GBL_STRU_RachRpt message. As an embodiment of the present invention, the first receiving module 401, the calculating module 402 and the reporting module 404 may be integrated, which is specifically implemented by a baseband DSP in the base station. The reporting module 404 specifically includes a generating unit 501 , an acquiring unit 502 , a writing unit 503 and a reporting unit 504 . Wherein, the generating unit 501 is configured to generate an uplink synchronization message. The acquiring unit 502 is configured to acquire TA value identification information identifying the TA value as the TA value of the sounding reference signal. Specifically, the TA value identifier corresponding to the sounding reference signal can be obtained according to the pre-stored correspondence between the TA value identifier and the identified object, and the TA value identifier can be empty, as long as it is different from the TA value identifier of the preamble That's it. The writing unit 503 is used to write the TA value calculated by the calculation module 402 into the uplink synchronization message generated by the generation unit 501, and set the TA value identification information obtained by the acquisition unit 502 in the uplink synchronization message, for example: to BESA_DSP_GBL_STRU_RachRpt The variable usTimeAdjust in the message writes the TA value obtained by the calculation module 402, and writes the TA value identification information obtained by the obtaining unit 502 into the variable uwTAid set on the reserved bit before usTimeAdjust. The reporting unit 504 is configured to report the uplink synchronization message of the TA value and the TA value identification information written by the writing unit 503 to the sending module 403 .

As shown in FIG. 7 , it is a schematic structural diagram of an embodiment of the UE of the present invention. The UE of this embodiment can be used to implement the process of the embodiment shown in FIG. 4 of the present invention. As shown in FIG. 7 , the UE in this embodiment includes a second receiving module 601 , an identification module 602 and an adjustment module 603 . Wherein, the second receiving module 601 is used for receiving the MAC PDU issued by the base station, and the MAC PDU includes TA value and TA value identification information. The identification module 602 is configured to identify whether the TA value in the MAC PDU received by the second receiving module 601 is the TA value of the SRS according to the TA value identification information in the MAC PDU, and output the identification result. The adjustment module 603 is configured to adjust the time offset of the terminal according to the identification result of the identification module 602 when the TA value is the TA value of the sounding reference signal, so that the terminal can communicate with the base station according to the adjusted result of the time offset. to communicate.

Referring again to FIG. 7 , the terminal according to the embodiment of the present invention may further include a communication module 600 for processing communication services with other communication devices, for example: processing communication services between the UE and a base station. Correspondingly, the adjustment module 603 is configured to adjust the time offset of the communication module 600 according to the TA value when the TA value is the TA value of the sounding reference signal according to the identification result of the identification module 602, so that the communication module 600 adjusts the time offset according to the time offset The adjusted result is communicated with the base station. As an embodiment of the present invention, the communication module 600 can be specifically implemented by a layer-3 module, a layer-2 module, and a layer-1 module. When the UE accesses the network, the layer-3 module triggers the layer-2 module to generate a sounding reference signal, and The sounding reference signal is encoded and modulated by a layer module and sent to the base station. The third layer is the network layer, and the second layer is the link layer. During specific implementation, the second receiving module 601 may also be set in the communication module 600 and implemented integrally with the communication module 600 .

According to presets, if the base station adds TA value identification information only for the TA value of the sounding reference signal or the preamble, the identification module 602 identifies whether the TA value is the sounding reference signal according to whether the TA value identification information is included in the MAC PDU. TA value. If the base station sets different TA value identification information for the TA value of the sounding reference signal and the TA value detected by the preamble, the identification module 602 specifically identifies the correspondence between the identified object and the identified object according to the preset TA value, Identify whether the identified object of the TA value identification information in the MAC PDU is a sounding reference signal. As shown in FIG. 8, it is a schematic structural diagram of another embodiment of the UE of the present invention. Compared with the embodiment shown in FIG. 7, the UE of this embodiment also includes a storage module 604 for storing a preset TA value identifier Correspondence information with the identified object. Correspondingly, the identification module 602 identifies whether the identified object of the TA value identification information in the MAC PDU is the TA value of the sounding reference signal according to the correspondence relationship information between the TA value identification and the identified object stored in the storage module 604.

A communication system provided by an embodiment of the present invention includes a UE1 and a base station 2 . Among them, base station 2 is used to receive the sounding reference signal reported by UE1, obtain the TA value according to the sounding reference signal, and send a MAC PDU to UE1, the MAC PDU includes the TA value and the TA value used to identify the TA value as the sounding reference signal The TA value identification information. UE1 is used to receive the MAC PDU sent by base station 2, identify whether the TA value is the TA value of the sounding reference signal according to the TA value identification information in the MAC PDU, and when the TA value is the TA value of the sounding reference signal, according to the TA value Perform time offset adjustment. Specifically, base station 2 in this embodiment may be implemented by using the embodiment shown in FIG. 5 or FIG. 6 , and UE1 in this embodiment may be implemented by using the embodiment shown in FIG. 7 or FIG. 8 . As shown in FIG. 9 , it is a schematic structural diagram of an embodiment of the communication system of the present invention. In this embodiment, UE1 adopts the UE of the embodiment shown in FIG. 7 , and base station 2 adopts the base station of the embodiment shown in FIG. 5 . Wherein, the first receiving module 401 in the base station 2 receives the sounding reference signal reported by the communication module 600 in the UE1, and the sending module 403 sends a MAC PDU to the second receiving module 601 in the UE1.

As shown in FIG. 10 , it is a schematic structural diagram of another embodiment of the communication system of the present invention. In this embodiment, UE1 adopts the UE of the embodiment shown in FIG. 8 , and base station 2 adopts the base station of the embodiment shown in FIG. 6 .

Those of ordinary skill in the art can understand that all or part of the steps for realizing the above-mentioned method embodiments can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the It includes the steps of the above method embodiments; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other various media that can store program codes.

In the embodiment of the present invention, the TA value identification information used to identify the TA value of the sounding reference signal can be set in the MAC PDU, and the UE can identify the TA value as the sounding reference signal according to the TA value identification information in the MAC PDU The TA value of the preamble is also the TA value of the preamble. Only when the TA value in the MAC PDU is the TA value of the sounding reference signal, the corresponding time offset adjustment is performed accordingly, so as to ensure the uplink synchronization performance of the OFDM system.

Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present invention, rather than limiting the understanding of the present invention. Although the present invention has been described in detail with reference to the above-mentioned preferred embodiments, those skilled in the art should understand that: it can still modify or replace the technical solution of the present invention, and such modification or replacement does not depart from the technology of the present invention. The spirit and scope of the programme.

Claims (12)

1. An uplink synchronization method, characterized in that, comprising: receiving the sounding reference signal reported by the terminal; Acquiring a time advance TA value according to the sounding reference signal; Sending a media access control MAC protocol data unit PDU to the terminal, the MAC PDU includes the TA value and TA value identification information, and the TA value identification information is used to identify that the TA value is the TA value of the sounding reference signal . 2. The method according to claim 1, wherein the TA value identification information of the sounding reference signal and the TA value of the preamble are different. 3. The method according to claim 1 or 2, wherein, between obtaining the TA value according to the sounding reference signal and sending the MAC PDU to the terminal, further comprising: Reporting an uplink synchronization message to the MAC module, where the uplink synchronization message includes the TA value and the TA value identification information. 4. The method according to claim 3, wherein the uplink synchronization message is a BESA_DSP_GBL_STRU_RachRpt message; The TA value identification information is set in the reserved bit before the TA value in the BESA_DSP_GBL_STRU_RachRpt message. 5. A method for uplink synchronization, comprising: Receive the MAC PDU sent by the base station, the MAC PDU includes TA value and TA value identification information; identifying whether the TA value is the TA value of a sounding reference signal according to the TA value identification information; When the TA value is the TA value of the sounding reference signal, time offset adjustment is performed according to the TA value. 6. The method according to claim 5, wherein the TA value for identifying whether the TA value is a sounding reference signal according to the TA value identification information is specifically: Identify whether the TA value is the TA value of the sounding reference signal according to whether the TA value identification information is empty; or, identify the TA value according to the preset correspondence relationship information between the TA value identification and the identified object Whether the identified object of the identification information is a sounding reference signal. 7. A base station, characterized in that, comprising: The first receiving module is configured to receive the sounding reference signal reported by the terminal; a calculation module, configured to obtain a TA value according to the sounding reference signal; The sending module is configured to send a MAC PDU to the terminal, the MAC PDU includes the TA value and TA value identification information, and the TA value identification information is used to identify the TA value as the TA value of the sounding reference signal. 8. The base station according to claim 7, further comprising: A reporting module, configured to report an uplink synchronization message to the delivery module, where the uplink synchronization message includes the TA value and the TA value identification information obtained by the calculation module. 9. The base station according to claim 8, wherein the reporting module comprises: a generating unit, configured to generate the uplink synchronization message; An acquiring unit, configured to acquire TA value identification information that identifies the TA value as the TA value of the sounding reference signal; A writing unit, configured to write a TA value into the uplink synchronization message, and set the TA value identification information in the uplink synchronization message; A reporting unit, configured to report an uplink synchronization message in which the TA value and the TA value identification information are written to the sending module. 10. A terminal, characterized in that, comprising: The second receiving module is used to receive the MAC PDU sent by the base station, and the MAC PDU includes TA value and TA value identification information; An identification module, configured to identify whether the TA value is the TA value of a sounding reference signal according to the TA value identification information; An adjustment module, configured to adjust the time offset of the terminal according to the TA value when the TA value is the TA value of the sounding reference signal according to the identification result of the identification module, so that the terminal adjusts the time offset according to the time offset of the terminal. The adjusted result is communicated with the base station. 11. The terminal according to claim 10, further comprising: A storage module, configured to store the correspondence relationship information between the preset TA value identification information and the identified object; The identification module identifies whether the identified object of the TA value identification information is a sounding reference signal according to the correspondence relationship information between the TA value identification information and the identified object. 12. A communication system, comprising a terminal and a base station, wherein the base station is configured to receive a sounding reference signal reported by the terminal, obtain a TA value according to the sounding reference signal, and send a MAC PDU to the terminal , the MAC PDU includes the TA value and TA value identification information for identifying the TA value of the sounding reference signal; The terminal is used to receive the MAC PDU issued by the base station, identify whether the TA value is the TA value of the sounding reference signal according to the TA value identification information in the MAC PDU, and determine whether the TA value is the TA value of the sounding reference signal When the TA value is set, the time offset adjustment is performed according to the TA value.

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