Frequency synchronization method for 5G fdd inventory mobile phone direct connection satellite

Abstract

The application discloses a frequency synchronization method for 5G FDD inventory mobile phone direct satellite connection, mainly solves the problem that the existing technology needs to change the mobile phone and the frequency correction has limitations on the beam range. The implementation scheme is: the base station carries out integer multiple frequency offset pre-compensation on the SSB in the SSB burst set and the corresponding SIB1; after the random access is initiated, different preamble detection windows are created according to the preamble occasions; the base station adjusts the uplink and downlink signal frequency domain resource allocation of the random access and the service transmission based on the satellite scheduling algorithm, carries out integer multiple frequency offset compensation in the form of resource grid offset, and combines the frequency offset compensation amount of the inventory mobile phone itself, so that the uplink and downlink signals are as much as possible without offset, and the frequency synchronization in the 5G mobile phone and satellite connection process is completed. The application can reduce the limitation of the beam range during frequency synchronization, avoid changing the mobile phone, adapt to the current inventory mobile phone technical standard, and can be used for satellite communication service of the 5G mobile phone.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of satellite communication, and mainly relates to a frequency synchronization method for connecting a stock 5G mobile phone to a satellite in an FDD system, which can be used for satellite communication services of 5G mobile phones. BACKGROUND

[0002] In recent years, with the popularization of smart phones and the rapid development of satellite launching technology, mobile communication is evolving towards the direction of satellite-terrestrial integration. Through satellite communication directly connected by mobile phones, the geographical restrictions can be overcome, and global coverage can be achieved. However, due to the high speed and large coverage range of satellites, the channel between the satellite and the mobile terminal has a serious Doppler effect, which affects the normal data transmission between the terminal and the satellite.

[0003] The prior art scheme can solve the problem of large Doppler shift by additionally modifying the terminal. For example, a chip that adapts to the satellite system protocol is added to the mobile phone to obtain real-time ephemeris information and terminal position information to compensate for the large Doppler frequency offset in satellite-terrestrial communication. Currently, this method is used in Huawei mobile phone + Beidou satellite, Huawei mobile phone + Tiantong satellite, Apple mobile phone + Globalstar, etc.

[0004] The non-terrestrial network (NTN) project hosted by the 3rd Generation Partnership Project (3GPP) has also carried out a lot of research and standardization work for satellite-terrestrial communication. The Rel-17, Rel-18 and other version standards have been completed, and the air interface enhancement protocol is designed, which introduces a variety of enhancement technologies to effectively solve the large frequency offset problem in satellite communication scenarios.

[0005] However, the above-mentioned solutions all need to upgrade or modify the existing terminal or protocol, which will increase the development cost of the hardware and software of the mobile terminal, and is not conducive to the expansion of the mobile phone satellite direct connection service, so it is necessary to explore how to compensate for the frequency offset on the base station side.

[0006] A frequency offset compensation method based on a base station side is proposed in patent document No. 202310658355.9. The satellite base station determines the ground reference point in real time using the coverage range of the ground beam, then determines the relative speed of the satellite with the point and the elevation angle of the point to the satellite according to the ground reference point, and then calculates the Doppler frequency offset compensation value according to the obtained parameters. Finally, the satellite base station downlink beam signal is compensated for Doppler frequency offset. Taking the satellite orbit height of 780 km, the carrier frequency of 2.1 GHz, the subcarrier spacing of 30 KHz, the maximum Doppler frequency shift of the beam of + 56 KHz, and the upper limit of the frequency offset resistance of the mobile phone of + 15 KHz as an example, when the satellite coverage beam center position observation elevation angle is 60°, the corresponding Doppler frequency shift is + 20 KHz, and the satellite base station pre-compensates the downlink signal by - 20 KHz. If the downlink channel Doppler frequency shift of UE1 is + 7 KHz, the residual frequency offset of the downlink signal after compensation by the base station is - 13 KHz, which does not exceed 15 KHz, so UE1 can complete downlink synchronization. If the downlink channel Doppler frequency shift of UE2 is + 50 KHz, the residual frequency offset of the downlink signal after compensation by the base station is - 30 KHz, which exceeds the frequency offset resistance of the mobile phone, so UE2 cannot complete downlink synchronization. It can be seen that this method only compensates the downlink signal sent to the beam at the beam center point, and when the beam range is large, it may cause the residual frequency offset of part of the terminal to exceed its correction ability and cannot complete frequency synchronization. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings of the prior art and provide a frequency synchronization scheme for 5G FDD inventory mobile phone direct connection satellite. In the case that the terminal is not modified and the beam range is only limited by the beam gain, the influence of user differential Doppler frequency shift is reduced, so that all inventory terminals within the beam range can complete frequency synchronization with the satellite.

[0008] To achieve the above purpose, the technical scheme of the present application is as follows:

[0009] (1) In the downlink direction, the satellite base station periodically transmits synchronization signals in the form of synchronization signal block (SSB) burst set, and divides the Doppler frequency shift into integer multiple frequency offset and fractional multiple frequency offset, wherein the integer multiple frequency offset is compensated by the satellite base station, and the fractional multiple frequency offset is compensated by the inventory mobile phone;

[0010] (2) The satellite base station pre-compensates each SSB and its corresponding system information block (SIB1) of the SSB burst set by different integer multiple frequency offsets;

[0011] (3) After the signal reaches the terminal, the terminal can at least decode one of the SSBs, and then the terminal continues to compensate the residual fractional multiple frequency offset;

[0012] (4) All terminals in the beam correctly decode SSB and SIB1 respectively to complete downlink synchronization and obtain preamble occasions;

[0013] (5) The terminal initiates a random access request to attempt to establish a connection with the satellite, and pre-compensates the transmitted preamble sequence Msg1 according to the carrier frequency and fractional frequency offset;

[0014] (6) The base station indicates different SSB signals corresponding to different preamble occasions through SIB1, and creates different preamble detection windows according to the preamble occasions. The base station compensates the uplink frequency offset according to the downlink integer multiple frequency offset corresponding to each window, so that the received preamble sequence in each preamble detection window is as unbiased as possible;

[0015] (7) The base station detects the preamble of the frequency-compensated signal, obtains the preamble sequence ID and TA that identifies the terminal, and stores the corresponding downlink direction integer multiple frequency offset at the base station side;

[0016] (8) The base station adjusts the frequency domain resource allocation of Msg2, Msg3 and Msg4 in the random access process of each user based on the integer multiple frequency offset it saves and the satellite scheduling algorithm, and compensates the integer multiple frequency offset in the form of resource grid offset;

[0017] (9) The base station adjusts the uplink and downlink signal frequency domain resource allocation of each user's subsequent service transmission, uses the same compensation method as in (8) to compensate the integer multiple frequency offset, and combines the frequency offset compensation capability of the inventory handset itself to realize frequency synchronization in the connection process of 5G handset and satellite;

[0018] Compared with the prior art, the present application has the following advantages:

[0019] First, the prior art pre-compensates the downlink signal by taking the center point of the beam range as the reference point to achieve the downlink synchronization of the inventory handset and the satellite, but when the beam range is large, it cannot guarantee that all handsets complete synchronization, so it is necessary to strictly limit the beam range. The beam range of the present application is only limited by the beam gain, and by compensating different frequency offset values for different SSB signals in the burst set, all inventory handsets in the satellite coverage beam can complete downlink synchronization.

[0020] Second, the prior art needs to modify the handset side to solve the problem of excessive residual uplink frequency offset in satellite-ground communication, and the handset compensates the uplink frequency offset by itself, which cannot be compatible with inventory handsets. The present application modifies the base station side, and compensates the uplink frequency offset through the base station side, which can adapt to the technical standards of inventory handsets. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The flowchart for the implementation of the present application;

[0022] Figure 2 The application scenario of the present application is shown in the figure;

[0023] Figure 3 The existing downlink synchronization signal frequency offset compensation is shown in the figure;

[0024] Figure 4 The downlink synchronization signal frequency offset compensation in the present application is shown in the figure;

[0025] Figure 5 The preamble sequence frequency offset compensation in the present application is shown in the figure;

[0026] Figure 6 The uplink and downlink signal frequency offset compensation in the present application is shown in the figure;

[0027] Figure 7 The method of frequency offset compensation by resource grid offset in the present application is shown in the figure; DETAILED DESCRIPTION

[0028] The embodiments of the present application are described in further detail below with reference to the accompanying drawings.

[0029] REFERENCE Figure 2 The application scenario of the present application is shown in the figure, including a base station, a satellite and a terminal. The base station duplex mode adopts FDD mode, and the terminal directly connects the satellite in the regenerative repeating mode, i.e. the satellite can perform part or all functions of the base station, and can perform coding and decoding operations on the transmission signal, and directly communicates with the mobile phone.

[0030] The first step of the mobile phone to establish connection with the base station is the downlink synchronization process. The present application assumes that the existing mobile phone adopts the direct sliding cross-correlation algorithm with the worst anti-frequency offset capability when decoding the downlink synchronization signal, and when the frequency offset is not greater than 1 / 2Δf, the bit error rate is relatively low, and the decoding can be correct. Therefore, 1 / 2Δf is regarded as the upper limit of the anti-frequency offset capability of the existing mobile phone, and when the Doppler shift of the transmission signal between the low-orbit satellite and the mobile phone exceeds 1 / 2Δf, the existing mobile phone cannot complete the downlink synchronization.

[0031] Based on the above scenario, the present application proposes an uplink and downlink frequency synchronization method suitable for the existing mobile phone, which enables all users in the beam to complete the downlink synchronization and random access, and perform service transmission under the condition that the beam range is only limited by the beam gain.

[0032] REFERENCE Figure 1 The implementation steps of the present example are as follows:

[0033] Step 1, when the base station sends the synchronization signal in the downlink direction, the Doppler shift is divided into integer multiple frequency offset and fractional frequency offset, and different integer multiple frequency offset pre-compensation is performed on the SSBs in the SSB burst set and the corresponding SIB1 respectively.

[0034] 1.1) The base station divides the maximum Doppler shift f d of the beam according to the system subcarrier spacing Δf SSB :

[0035] n SSB = 2m+1, where

[0036] 1.2) Calculate the frequency offset value of each of the n SSB SSBs

[0037] Where i = 1, 2, …, n SSB ;

[0038] 1.3) The base station pre-compensates the i-th SSB and the corresponding SIB1 with a frequency offset of .

[0039] In this example, when f d = ±56KHz, Δf = 30KHz, Using these parameters in the prior art, the satellite-based base station performs -2Δf, -Δf, 0, Δf, and 2Δf frequency offset compensation on the five SSBs in the burst set before transmission in the downlink, and the user frequency offset range in the downlink transmission is as shown in Table 1.

[0040] Table 1 User frequency offset range table in downlink transmission

[0041]

[0042] Referring to Figure 3 , the prior art performs frequency offset compensation with the beam center point as the reference point, which causes the residual frequency offset of UE2 to be outside the terminal acceptance range, so the downlink synchronization cannot be correctly decoded.

[0043] Referring to Figure 4 , after the frequency offset compensation of the five SSB signals in the burst set in this step, at least one SSB in the terminal groups 1-5 has a downlink residual frequency offset within the acceptance range, so the SSB and the corresponding SIB1 can be correctly decoded.

[0044] Step 2, after the downlink signal reaches the terminal, the terminal estimates and compensates the residual fractional frequency offset of the downlink signal, correctly decodes the SSB to complete the downlink synchronization, and then demodulates the system message block SIB1 to obtain the preamble occasion.

[0045] 2.1) The terminal performs frequency offset estimation on the downlink signal:

[0046] The existing methods include PN-based autocorrelation method, OFDM pilot sequence-based autocorrelation method, PSS-based direct cross-correlation method, PSS-based segmented cross-correlation method, and PSS and CP-based joint estimation method. In the present example, the PSS-based direct cross-correlation method is used for frequency offset estimation, but not limited thereto, and the specific implementation is as follows:

[0047] 2.1.1) Multiply the signal y(n) received by the terminal with the conjugate s * (n) of the local PSS sequence to obtain the sequence c(n):

[0048]

[0049] wherein s(n) is the time-domain PSS signal, f ε is the residual fractional multiple frequency offset, and N is the number of sampling points.

[0050] 2.1.2) Cross-correlate the front and rear two sequences of c(n) to obtain the sequence

[0051]

[0052] wherein c * (n) is the conjugate sequence of c(n);

[0053] 2.1.3) Calculate the residual fractional multiple frequency offset f ε according to the sequence :

[0054]

[0055] 2.2) The terminal performs phase rotation on the received signal y(n) through the baseband processor to compensate for the frequency offset, so that the residual fractional multiple frequency offset f ε is 0.

[0056] 2.3) The terminal demodulates the primary synchronization signal PSS, secondary synchronization signal SSS, and demodulation reference signal DMRS in the SSB to obtain the wireless frame boundary and physical cell ID, so as to complete the downlink synchronization.

[0057] 2.4) The terminal monitors the system information wireless network temporary identifier SI-RNTI through the downlink physical control channel PDCCH to demodulate SIB1 on the physical downlink shared channel PDSCH, so that the terminal obtains the preamble occasion.

[0058] Step 3, the terminal initiates a random access request to establish a connection with the satellite, and performs frequency pre-compensation on the transmitted preamble sequence Msg1.

[0059] 3.1) The terminal initiates a random access request attempt to establish a connection with the satellite according to the indication of radio resource control (RRC) signaling;

[0060] 3.2) After the terminal initiates random access, the transmitted preamble sequence Msg1 is pre-compensated for frequency offset, and the calculation formula is:

[0061]

[0062] wherein f UEU is the pre-compensation amount of the terminal, f ε represents the downlink frequency offset estimation value, f DC represents the downlink carrier frequency, and f UC represents the uplink carrier frequency.

[0063] Step 4, the base station creates different preamble detection windows according to the preamble occasions in the SIB1 information, and compensates the received preamble signals for different frequency offset values in different windows.

[0064] With reference to Figure 5 , the specific implementation of this step is as follows:

[0065] 4.1) The base station creates different preamble detection windows according to the preamble occasions in the SIB1 information:

[0066] 4.1.1) After the base station provides the configuration of the random access channel (PRACH) to the terminal through the broadcast channel, the terminal acquires the position of the start of the preamble time slot according to the SIB1 corresponding to the i-th SSB to determine the preamble occasion τ i ;

[0067] 4.1.2) The base station determines the minimum round-trip delay and the maximum round-trip delay

[0068] 4.1.3) The base station determines the preamble detection window #i according to and the preamble occasion τ i , the window start point is , and the window length is

[0069] 4.2) The base station calculates the residual frequency offset of the preamble sequence of each window and compensates for different frequency offset values:

[0070] 4.2.1) The base station receives the preamble sequence sent by the corresponding user in each preamble detection window, and calculates the residual frequency offset f Uleft in the preamble sequence:

[0071]

[0072] wherein f UEU represents the preamble sequence frequency offset compensation amount of the mobile phone, f U denotes the Doppler shift experienced by the uplink channel of the UE, f Dcom represents the frequency offset compensation value of the base station to the SSB, f DC represents the downlink carrier frequency, f UC represents the uplink carrier frequency;

[0073] 4.2.2) Residual frequency offset of the received signal by the base station in window #i is divided into an integer multiple frequency offset n i Δf and a fractional multiple frequency offset ε i Δf(-0.5<ε<0.5);

[0074] 4.2.3) The base station compensates for the integer multiple frequency offset n i Δf using the resource grid offset frequency compensation method, that is, the base station shifts the preamble sequence frequency domain extraction position by-n i resource grids when performing resource demapping at the base station end;

[0075] 4.2.4) The base station further performs phase rotation on the preamble sequence to compensate for the remaining fractional multiple frequency offset ε i Δf.

[0076] Referring to Figure 5 , the base station performs-54KHz frequency offset compensation on the preamble sequence sent by the terminal in preamble detection window #1 according to the SIB1 information corresponding to the first SSB in the SSB burst set; performs-27KHz frequency offset compensation on the preamble sequence sent by the terminal in preamble detection window #2 according to the SIB1 information corresponding to the second SSB. In this way, the uplink and downlink frequency offset compensation size relationship after each terminal group completes the above process is shown in Table 2.

[0077] Table 2: Uplink and downlink frequency offset compensation relationship table

[0078]

[0079] Step 5, the base station performs preamble detection on the frequency offset compensated signal, obtains the preamble sequence ID and TA of the identified terminal, and stores the corresponding downlink integer multiple pre-compensation size and the integer multiple frequency offset n i Δf of the uplink residual frequency offset of window #i at the base station side;

[0080] Step 6: Based on its stored integer multiple frequency offset and satellite scheduling algorithm, the base station performs integer multiple frequency offset compensation on the randomly accessed Msg2, Msg3, Msg4 and the uplink and downlink signals of service transmission in the form of resource grid offset, and combines the mobile phone's own frequency offset compensation capability to make the uplink and downlink signals as unbiased as possible.

[0081] Reference Figure 6 and Figure 7 The specific implementation of this step is as follows:

[0082] 6.1) After completing the first step of random access, Msg1, the base station, when sending DCI scheduling information to the terminal using RA-RNTI on the Physical Downlink Control Channel (PDCCH), offsets the frequency domain resource location of the Msg2 to be sent by im-1 resource cells, i.e., performs... Frequency offset pre-compensation of magnitude;

[0083] 6.2) When generating the uplink grant (UL Grant) in the Msg2 information during the second step of random access, the base station offsets the Msg3 frequency domain resource location by -n. i One resource cell, i.e., perform -n i Compensation for frequency offset by integer multiples of Δf;

[0084] 6.3) After receiving the UL Grant in Msg2, the terminal sends Msg3 on the Physical Uplink Shared Channel (PUSCH) through the specified uplink resources to complete the third step of random access and identifies it with a temporary C-RNTI.

[0085] 6.4) After receiving the Msg3 confirmation of the terminal's access request, the base station sends a DCI notification on the PDCCH to inform the terminal of the resource allocation of the Physical Downlink Shared Channel (PDSCH), and offsets the frequency domain resource position of the Msg4 to be transmitted by im-1 resource cells, i.e., performs... Frequency offset precompensation of magnitude;

[0086] 6.5) After receiving Msg4, the terminal completes random access with the satellite base station, enters the RRC connection state, and performs permanent C-RNTI allocation for subsequent service transmission identifiers;

[0087] 6.6) Before downlink data transmission, the base station sends a DCI notification to the terminal's PDSCH via PDCCH to allocate resources, shifting the downlink signal frequency domain resource position by im-1 resource cells, i.e., performing... Frequency offset precompensation of magnitude;

[0088] 6.7) When the terminal sends uplink data, the base station sends a UL Grant to the terminal via PDCCH to indicate the resource allocation of the uplink PDSCH, offsetting the frequency domain resource position of the uplink signal by -n. i One resource cell, i.e., perform -ni Post-compensation of integer multiple of the size of delta f frequency offset;

[0089] The application can realize the frequency synchronization of the mobile phone with the satellite signal transmission process without modifying the existing mobile phone, ensure the correct decoding of the signal during the transmission, and complete the normal communication process of the mobile phone and the satellite.

[0090] The above description is only one specific example of the application and does not constitute any limitation on the application. Obviously, for those skilled in the art, after understanding the content and principles of the application, various modifications and changes in form and details can be made without departing from the principles and structures of the application. However, these modifications and changes based on the idea of the application are still within the protection scope of the claims of the application.

[0091] It should be noted that the step numbers in the specification and claims of the application are only for the clear description of the embodiments of the application for the purpose of understanding, and the sequence of the numbers is not limited.

Claims

1. A frequency synchronization method for direct satellite connection of existing 5G FDD mobile phones, characterized in that, Includes the following steps: (1) In the downlink direction, the satellite base station periodically sends synchronization signals in the form of synchronization signal block (SSB) burst sets and divides the Doppler frequency shift into integer multiples of frequency offset and fractional multiples of frequency offset. The integer multiples of frequency offset are compensated by the satellite base station, and the fractional multiples of frequency offset are compensated by the existing mobile phones themselves. (2) The satellite base station performs different integer multiple frequency offset pre-compensation on each SSB and its corresponding system message block SIB1 of the SSB burst set; (3) After the signal arrives at the terminal, the terminal will at least solve one of the SSBs and then continue to compensate for the remaining fractional frequency offset. (4) All terminals within the beam correctly decode SSB and SIB1 to complete downlink synchronization and obtain the preamble timing; (5) The terminal initiates a random access request to attempt to establish a connection with the satellite, and performs frequency offset pre-compensation on the transmitted preamble sequence Msg1 according to the carrier frequency and fractional frequency offset; (6) The base station indicates different SSB signals corresponding to different preamble timings through SIB1, and creates different preamble detection windows according to the preamble timings. The base station performs uplink frequency offset compensation according to the downlink integer multiple frequency offset corresponding to each window, so that the received preamble sequence in each preamble detection window is as unbiased as possible. (7) The base station performs preamble detection on the frequency offset compensated signal, obtains the preamble sequence ID and TA of the identification terminal, and stores the corresponding downlink direction integer multiple frequency offset on the base station side. (8) The base station adjusts the frequency domain resource allocation of Msg2, Msg3 and Msg4 during the random access process of each user based on the integer multiple frequency offset and satellite scheduling algorithm stored in it, and compensates for the integer multiple frequency offset by means of resource grid offset; (9) The base station adjusts the frequency domain resource allocation of uplink and downlink signals for each user's subsequent service transmission, uses the same compensation method as in (8) to perform integer multiple frequency offset compensation, and combines the frequency offset compensation capability of the existing mobile phones to achieve frequency synchronization in the process of connecting 5G mobile phones with satellites.

2. The method according to claim 1, characterized in that, In step (2), the base station performs different integer multiple frequency offset pre-compensation on each SSB in the SSB burst set and its corresponding system message block SIB1. The implementation steps include the following: (2a) Based on the system subcarrier spacing and beam maximum Doppler frequency shift Calculate the number of SSBs in each SSB burst set. : ； in = ; (2b) Compensate different frequency offset values ​​for different SSBs in each SSB burst set. The formula for calculating the pre-compensation frequency offset value of the i-th SSB is as follows: ； in For the first .

3. The method according to claim 1, characterized in that, In step (4), all terminals within the beam correctly decode SSB and SIB1 by detecting the primary synchronization signal PSS, secondary synchronization signal SSS, and demodulation reference signal DMRS to obtain the radio frame boundary and physical cell ID, thereby completing downlink synchronization; then the terminal receives the information carried by SIB1 on the downlink shared physical channel PDSCH, enabling the terminal to obtain the preamble opportunity.

4. The method according to claim 1, characterized in that, In step (5), the terminal performs pre-compensation based on the carrier frequency and fractional frequency offset, as shown in the following formula: ； in This represents the estimated downlink frequency offset. Indicates the downlink carrier frequency. This indicates the uplink carrier frequency.

5. The method according to claim 2, characterized in that, Step (6) The base station creates different preamble detection windows according to the preamble timing, and performs uplink frequency offset compensation according to the downlink integer multiple frequency offset corresponding to each window. The steps include the following: (5a) After the base station provides the terminal with the configuration of the random access channel PRACH through the broadcast channel, the terminal, according to the... The SIB1 corresponding to each SSB obtains the start position of the preamble time slot to determine... ; (5b) The base station determines the minimum round-trip time between the user and the satellite base station within the frequency offset range using the satellite's ephemeris information. and maximum round-trip delay ; (5c) Base station according to and leading timing Sure window# Its window starts at Window length is ; (5d) The base station receives the preamble sequence sent by the corresponding user in each preamble detection window and calculates the uplink residual frequency offset in the preamble sequence. : = ； in, Indicates the base station at the Frequency offset compensation value for each SSB, Indicates the downlink carrier frequency. Indicates the uplink carrier frequency; (5e) Base station in window # Receive signal Divided into integer multiples of frequency offset and fractional frequency offset Then compensate separately, where the integer multiples of the frequency offset Compensation is achieved by offsetting resource grids.

6. The method according to claim 5, characterized in that, In step (8), the base station adjusts the frequency domain resource allocation of Msg2, Msg3, and Msg4 during each user's random access process based on its stored integer multiple frequency offset and satellite scheduling algorithm, and compensates for the integer multiple frequency offset by means of resource grid offset. The implementation steps include the following: (6a) The base station adjusts the Msg2 resource allocation strategy in the second step of random access, that is, when sending DCI to the terminal through PDCCH, it shifts the location of the specified Msg2 frequency domain resource. Each resource cell, that is, to conduct Frequency offset precompensation of magnitude; (6b) When the base station allocates an uplink grant (UL Grant) to the terminal via Msg2 in the second step of random access, it adjusts the resource allocation strategy of Msg3 and shifts the specified Msg3 frequency domain resource location. Each resource cell, that is, to conduct Compensation for frequency offset at integer multiples of the magnitude; (6c) When the base station adjusts the Msg4 resource allocation strategy in the fourth step of random access, it shifts the frequency domain resource position of the Msg4 to be sent when sending the DCI notification to the terminal on the PDCCH to allocate resources for the downlink PDSCH. Each resource cell, that is, to conduct Frequency offset pre-compensation of magnitude.

7. The method according to claim 5, characterized in that, In step (9), the base station adjusts the uplink and downlink signal frequency domain resource allocation for each user's subsequent service transmission, using the same compensation method as in (8) to perform integer multiple frequency offset compensation. The steps include the following: (7a) After the terminal and the base station complete random access, a permanent C-RNTI is assigned for subsequent service transmission identification; (7b) Before transmitting downlink data, the base station sends a DCI notification to the terminal via PDCCH to offset the downlink signal frequency domain resource location when allocating downlink PDSCH resources. Each resource cell, that is, to conduct Frequency offset precompensation of magnitude; (7c) Before uplink data transmission, the base station sends a UL Grant to the terminal via PDCCH to indicate that the uplink PDSCH resource allocation will offset the frequency domain resource location of the uplink signal. Each resource cell, that is, to conduct Compensation for frequency offset by integer multiples of the magnitude.

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