A long-distance high-precision integrated detection waveform design method

Abstract

The application discloses a long-distance high-precision sensing integrated detection waveform design method, which comprises the following steps: step 1, according to the sensing waveform number requirement supported by the system simultaneously, the transmission comb number N is determined comb ; step 2, according to the sensing distance requirement, the expandable long-distance sensing signal is generated, and the expandable long-distance sensing signal lasts L symbols; step 3, according to the speed detection requirement of the moving target and the typical communication time slot configuration, the short period T ps , the short period repetition emission times L p , the long period T pl , and the long period repetition emission times N p are determined; step 4, the frequency domain signal mapping of the pre-detection stage is completed, and the subcarrier mapping of adjacent L OFDM symbols is completed in a frequency domain continuous manner; step 5, the time domain signal mapping of the pre-detection stage is completed, the frequency domain mapping signal of the step 4 stage is repeatedly emitted L ps times according to the configured T p period; step 6, the frequency domain signal mapping of the detection stage is completed, and the subcarrier mapping of adjacent L OFDM symbols is completed in a selected comb division manner; step 7, the time domain signal mapping of the detection stage is completed, and the frequency domain mapping signal of the step 5 stage is repeatedly emitted N pl times according to the configured long period T p . The application can solve the problems of limited sensing distance and distance ambiguity when the communication waveform is used for sensing, and meet the high-precision sensing of the distance and speed of the near and far targets in a long-distance range.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to a long-distance high-precision integrated sensing and communication probe waveform design method. BACKGROUND

[0002] Integrated sensing and communication is one of the six application scenarios of 6G, aiming to realize two independent functions of wireless communication and wireless sensing in the same system. Probe waveform design is a key technology for integrated sensing and communication. There are three existing technical routes, namely integrated waveform based on communication waveform, integrated waveform based on radar waveform, and integrated waveform based on new integrated sensing and communication. Radar waveform has poor data carrying capacity, and needs to increase hardware units for processing frequency modulation waves. The new integrated sensing and communication waveform such as OTFS has a high peak-to-average ratio, and the long-distance sensing capability is limited, and the communication modulation and demodulation algorithm needs to be modified. Therefore, transforming the OFDM communication waveform to meet the sensing requirements has wide application prospects.

[0003] In the design of OFDM sensing waveform, multiplexing or enhancing existing reference signals can not only reduce the overhead but also provide sensing capability. The uplink probe reference signal uses a ZC sequence as the base sequence, which has low peak-to-average ratio characteristics and good autocorrelation characteristics, and can meet the performance indicators such as sensing distance and sensing accuracy. However, due to the limited length of the cyclic prefix of the OFDM symbol and the comb design of the probe signal, if the traditional probe signal is directly used for base station side sensing, there will be limited sensing distance and distance ambiguity. In addition, the single-beat probe signal cannot accurately sense the target motion speed, and a certain sensing frame structure needs to be designed to meet the motion target speed sensing requirement. Therefore, a sensing and communication integrated probe signal design scheme is needed to realize long-distance sensing and meet the high-precision distance and speed sensing requirements of long-distance targets. SUMMARY

[0004] The present application provides a long-distance high-precision integrated sensing and communication probe waveform design method, which can solve the problems of limited sensing distance and distance ambiguity when using communication waveform for sensing, and meet the high-precision distance and speed sensing requirements of long-distance targets in a wide range.

[0005] Technical scheme: The long-distance high-precision integrated sensing and communication probe waveform design method provided by the present application comprises the following steps:

[0006] Step 1, determine the transmission comb number N according to the number of sensing waveforms required to be supported by the system at the same time comb ;

[0007] Step 2, generate an expandable long-distance integrated sensing and communication signal according to the distance requirement of sensing, and the expandable long-distance integrated sensing and communication signal lasts for L symbols;

[0008] Step 3, according to the speed detection requirement of the moving target and the typical communication time slot configuration, determine the short period T ps , the number of short period repeated transmission L p , the long period T pl , the number of long period repeated transmission N p ;

[0009] Step 4, complete the frequency domain signal mapping of the pre-detection stage, complete the subcarrier mapping of adjacent L OFDM symbols in a frequency domain continuous manner;

[0010] Step 5, complete the time domain signal mapping of the pre-detection stage, map the frequency domain mapping signal of step 4 stage according to the configured T ps period repeated transmission L p times;

[0011] Step 6, complete the frequency domain signal mapping of the detection stage, complete the subcarrier mapping of adjacent L OFDM symbols in a selected comb manner;

[0012] Step 7, complete the time domain signal mapping of the detection stage, map the frequency domain mapping signal of step 5 stage according to the configured long period T pl repeated transmission N p times.

[0013] Further, in step 1, according to the requirement of the number of sensing waveforms simultaneously supported by the system, determine the number of transmission combs N comb ;

[0014]

[0015] Wherein, N max-sense is the maximum number of sensing waveforms that need to be supported simultaneously, |{α,u,v}| represents the number of parameter sets that can be used for sensing, each pair of u and v can determine a root sequence, u is the group number of the uplink sounding reference signal, v is the base sequence number in the group, and α is the cyclic shift.

[0016] Further, in step 2, according to the distance requirement of sensing, determine the expandable long-distance sensing signal lasting L symbols, and generate the expandable long-distance sensing signal;

[0017] Considering the uplink and downlink timing relationship of the TDD system, the maximum effective sensing distance is

[0018]

[0019] Wherein, c is the speed of light, is the signal length, is the signal cyclic prefix CP length, T c is the minimum time unit in 3GPP protocol, and T TAis the uplink and downlink timing offset, the table between the perceived distance and the duration symbol is generated according to the maximum effective perceived distance formula, and L is obtained by looking up the table according to the perceived distance requirement;

[0020] The expandable long-distance sensing signal takes the lth OFDM symbol in a subframe as the starting point and lasts for L symbols, and the sequence of the l'th OFDM symbol after that is:

[0021]

[0022] wherein, is the sensing base sequence, and δ is the logarithm of the number of transmission combs, is a ZC sequence, and L cp is the length of the cyclic prefix of the communication system, N FFT is the number of FFT points of the communication system, and the above formula indicates that the tail L cp signals of the l'th signal are copied as the cyclic prefix to ensure the continuity of splicing.

[0023] Further, for the RRU adopting the Option7-2 format, the RRU side has the functions of low-order physical layer processing, including FFT / IFFT, adding and removing the cyclic prefix, and phase compensation; at this time, the phase compensation in the 3GPP protocol will destroy the phase continuity of the splicing of the expandable long-distance communication signal, in order to ensure the transparent support to the RRU, the designed expandable long-distance signal needs to be phase anti-compensated,

[0024]

[0025] wherein, μ is a protocol parameter set, f0 is a carrier frequency, is the position index of the l'th sensing OFDM symbol in the subframe, T c is the minimum time unit in the 3GPP protocol, the calculation method of the position index is consistent with the protocol, for a specific parameter set, the phase compensation table is pre-generated in an iterative manner, and the position index is generated in the following manner:

[0026]

[0027] wherein, is the signal length, is the signal cyclic prefix CP length.

[0028] Further, in step 3, according to the speed detection requirement of the moving target and the typical communication time slot configuration, the short period T ps , the short period repetition transmission number L p , the long period T pl , and the long period repetition transmission number N p are determined.

[0029] Tps and L p The determination method is as follows:

[0030]

[0031] wherein, denotes rounding down, denotes rounding up, λ is wavelength, T ofdm is the length of OFDM symbol time including cyclic prefix, v max is the maximum expected detection speed, v sect is the length of the segmented interval speed of speed detection;

[0032] T pl and N p The determination method is as follows,

[0033] T pl =n pl T period

[0034]

[0035] wherein, Δv is the expected speed detection accuracy of the moving target, T period is the length of a commonly used typical communication time slot configuration on the base station side, n pl is a configurable integer.

[0036] Further, in step 4, the frequency domain signal mapping of the pre-detection stage is completed, and the subcarrier mapping of adjacent L OFDM symbols is completed in a subcarrier continuous manner;

[0037] The mapping formula of the subcarrier continuous mapping manner is as follows:

[0038]

[0039] wherein, s grid is the time-frequency domain grid of OFDM, n comb is the comb index corresponding to the sensing waveform, L OFDM signals are a sensing signal block in the pre-detection stage, and l' is the index of the OFDM symbol in the sensing signal block.

[0040] Further, in step 5, the time domain signal mapping of the pre-detection stage is completed, and the frequency domain mapping signal of step 4 is repeatedly transmitted in a periodic manner according to the configured T ps is the period; p L

[0041] The time domain mapping formula of the pre-detection stage is as follows,

[0042]

[0043] Among them, s pred is the time-frequency domain grid for the pre-detection phase, l' is the index of the OFDM symbol within the sensing signal block, and l” is the index of the sensing signal block.

[0044] Furthermore, if the design of T ps If the length is equal to the OFDM symbol length, a continuous wave design is adopted. First, the scalable wide-range inductive signal generation length in step 2 is extended from L symbol to L+L. p -1, then use the frequency domain continuous mapping method in step 4, and then map the time domain to the adjacent L+L. p -1 OFDM symbol, to obtain L p For the second OFDM channel, the time-domain mapping formula for the pre-detection phase is as follows:

[0045]

[0046] Furthermore, in step 6, the frequency domain signal mapping of the detection phase is completed, and the subcarrier mapping of adjacent L OFDM symbols is completed according to the selected combing method.

[0047] The mapping formula for subcarrier combing is as follows:

[0048]

[0049] Among them, s grid It is the time-frequency domain grid of OFDM, n comb is the comb index corresponding to the sensing waveform, L OFDM signals constitute a sensing signal block in the detection phase, and l' is the index of the OFDM symbol within the sensing signal block.

[0050] Furthermore, in step 7, the time-domain signal mapping of the detection phase is completed, and the frequency-domain mapped signal of phase S05 is mapped according to the configured long period T. pl Repeated emission N p Second-rate;

[0051] The time-domain mapping formula for the detection phase is as follows:

[0052]

[0053] Among them, s detect is the time-frequency domain grid for the detection phase, l' is the index of the OFDM symbol within the sensing signal block, and l” is the index of the sensing signal block.

[0054] Beneficial effects: compared with the prior art, the present application has the following remarkable advantages: high-precision distance and speed sensing of far and near targets in a wide range can be realized; the detection signal design method includes expandable wide-range sensing signal design, distance ambiguity elimination scheme and high-speed resolution frame structure design; the expandable wide-range sensing signal design realizes simultaneous sensing of far and near targets; the distance ambiguity elimination scheme eliminates distance ambiguity within and between OFDM symbols; the high-speed resolution frame structure design improves the speed sensing accuracy of moving targets; high-precision distance and speed sensing of far targets can be realized with small resource overhead. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 The present application is an expandable wide-range sensing signal design schematic diagram.

[0056] Figure 2 The present application is a symbol distance ambiguity elimination scheme design schematic diagram.

[0057] Figure 3 The present application is a symbol distance ambiguity solution schematic diagram.

[0058] Figure 4 The present application is a high-speed resolution frame structure design schematic diagram.

[0059] Figure 5 The present application is a sensing signal time-frequency domain configuration schematic diagram. DETAILED DESCRIPTION

[0060] A long-range high-precision sensing integrated detection waveform design method, comprising the following steps:

[0061] Step 1, according to the number of sensing waveforms required to be supported by the system simultaneously, determine the number of transmission combs N comb ;

[0062] Step 2, according to the distance requirement of sensing, generate an expandable wide-range sensing signal, and the expandable wide-range sensing signal lasts for L symbols;

[0063] Step 3, according to the speed detection requirement of moving targets and the typical communication time slot configuration, determine the short period T ps , the number of short period repeated transmissions L p , the long period T pl , and the number of long period repeated transmissions N p ;

[0064] Step 4, complete the frequency domain signal mapping of the pre-detection stage, and complete the subcarrier mapping of adjacent L OFDM symbols in a frequency domain continuous manner;

[0065] Step 5, complete the time domain signal mapping of the pre-probing stage, map the frequency domain mapping signal of the step 4 stage according to the configured T ps L p is transmitted periodically.

[0066] Step 6, complete the frequency domain signal mapping of the probing stage, complete the subcarrier mapping of the adjacent L OFDM symbols according to the selected combing mode.

[0067] Step 7, complete the time domain signal mapping of the probing stage, map the frequency domain mapping signal of the step 5 stage according to the configured long period T pl N p is transmitted periodically.

[0068] The ZC sequence has constant modulus, low peak-to-average characteristics and good autocorrelation characteristics, is commonly used as a communication uplink probing signal base sequence, and can also be used as a sensing base sequence. The multiplexing uplink probing signal generation process generates a sensing base sequence

[0069]

[0070] Wherein, α is the cyclic shift, u is the group number, v is the base sequence number in the group, and δ is the logarithm of the transmission comb number, is the ZC sequence, and M ZC is the sequence length. In order to avoid interference with the uplink probing signal, the group number and the base sequence number of the sensing base sequence should be different from the group number and the base sequence number of the communication uplink probing signal.

[0071] The communication signal supports the target echo in the probing cyclic prefix CP range, in order to support the target outside the CP range, while being compatible with commercial terminals, an extended CP scheme is adopted to generate an expandable long-distance communication and sensing signal. The expandable long-distance communication and sensing signal needs to splice the signals of adjacent OFDM symbols, and needs to do two special designs of cyclic shift and phase compensation to ensure the integrity of splicing.

[0072] Assuming that the expandable long-distance communication and sensing signal starts at the lth OFDM symbol in a subframe and lasts for L symbols, then the sequence of the l'th OFDM symbol is:

[0073]

[0074] Wherein, L cp is the length of the communication system cyclic prefix, N FFT is the number of FFT points of the communication system, and the above formula indicates that the tail L cp signals of the l' signal are copied as a cyclic prefix to ensure the continuity of splicing, as shown in Figure 1 .

[0075] For the RRU using Option7-2 format, the RRU side has the function of low-order physical layer processing, including FFT / IFFT, add and remove cyclic prefix, phase compensation and other functions. At this time, the phase compensation in the 3GPP protocol will destroy the phase continuity of the expandable long-distance communication signal splicing. In order to ensure the transparent support to the RRU, the phase anti-compensation needs to be done to the designed expandable long-distance signal,

[0076]

[0077] Wherein, μ is the protocol parameter set, f0 is the carrier frequency, is the position index of the l'th sensing OFDM symbol in the subframe, T c is the minimum time unit in the 5G protocol, the calculation method of the position index is consistent with the protocol, for a specific parameter set, the phase compensation table can be pre-generated in an iterative manner, and the position index is generated in the following manner:

[0078]

[0079] Wherein, is the signal length, is the signal cyclic prefix CP length.

[0080] The detection distance of the expandable long-distance sensing signal depends on the splicing duration L, considering the uplink and downlink timing relationship of the TDD system, the effective sensing distance is

[0081]

[0082] Wherein, c is the speed of light, is the signal cyclic prefix CP length.

[0083] When the sensing signal is used to complete the channel estimation / environment sensing, the equalization algorithm needs to be used to estimate the air interface channel. In order to guarantee that the base sequence can obtain accurate air interface channel, TA compensation, anti-cyclic shift and phase compensation need to be done to the received long-distance sensing signal, and the frequency domain signal of the RRU front-end to the BBU is denoted as The received signal should be processed as

[0084]

[0085] Wherein, T D represents the OFDM symbol time length excluding the cyclic prefix.

[0086] The sensing signal processed by compensation can be directly equalized with the base sequence to obtain the air interface channel, which further supports the implementation of subsequent sensing algorithms.

[0087] When the comb-structure frequency-division is used to form orthogonal pilots from multiplexed uplink probe signals, the equal-interval sampling in frequency domain will cause the periodic repetition of time-domain signals, resulting in the aliasing of time delay estimation within OFDM symbols, and causing the distance ambiguity problem within OFDM symbols.

[0088] The pre-probe scheme is used to eliminate the ambiguity within OFDM symbols, i.e., first occupying continuous bandwidth to pre-probe to determine the distance interval, solve the ambiguity problem within OFDM symbols, and then use the comb-structure to improve the distance resolution and increase the number of orthogonal pilots, as shown in Figure 2 .

[0089] Suppose the FFT point number of the system is N FFT , the subcarrier spacing is Δf, and the number of subcarriers occupied by each pilot is The number of transmission combs is N comb , and in the pre-probe stage, the continuous occupied subcarriers are used to determine the distance belonging interval of the echo by using the equalized channel distance estimation,

[0090]

[0091] After confirming the distance interval in the probe stage, the expandable long-range sensing signal of the comb-structure is used to complete the subsequent sensing task.

[0092] When L = 2, the effective sensing distance of the expandable long-range sensing signal is

[0093]

[0094] When the effective sensing distance of the designed expandable long-range sensing signal exceeds d thd , and the number of continuous splicing L ≥ 3, the inter-symbol distance ambiguity problem needs to be solved, i.e., the real time delay value experienced by each OFDM time delay peak value needs to be determined. For the echo signal in the long-range range, the channel within the l'th OFDM symbol obtained by using the equalization algorithm can be modeled as:

[0095]

[0096] Where τ i is the real time delay corresponding to the i'th path, is the time delay of the i'th path observed by the channel within the OFDM symbol, T D represents the OFDM symbol time length excluding the cyclic prefix, T CP is the cyclic prefix time length, T ofdm is the OFDM symbol time length including the cyclic prefix, and Γ i,l' represents the existence of a scalar, which is defined as follows:

[0097]

[0098] The channel estimation within L OFDM symbols can be used to eliminate the ambiguity of the distance between symbols, i.e. using Γ i,l' There is a property of the scalar, and the similarity matching of the time delay peak of the observation within L OFDM symbols forms a time delay group, and the first time delay corresponding to each time delay group appears at the OFDM position, i.e. the time delay actually experienced by the time delay, and the time delay appearing on the subsequent OFDM is the ambiguous solution, thereby eliminating the ambiguity of the distance between OFDM symbols, and the real time delay corresponding to each time delay observation can be determined, so as to obtain the real distance.

[0099]

[0100] Taking a millimeter wave system as an example, the uplink and downlink advance of the system T TA = 13792T c = 7.015 μs, the subcarrier spacing is 120 kHz, the system FFT point number is 2048, the maximum detection distance is designed to be 3.4 km, according to the effective sensing distance formula of the long-distance sensing signal, L = 3 is configured, and it is assumed that there are two echo paths in the echo, which are 50 m and 3.2 km, as shown in Figure 3 Because of the influence of the uplink and downlink advance of the system, the first l' = 0 OFDM symbol exists symbol truncation, which causes ISI and leads to unavailable channel, so the channel needs to be discarded when similarity matching. Two time delay groups are obtained by using similarity matching on the remaining two channels, which are marked with circles and triangles respectively. The echo distances can be calculated as:

[0101]

[0102] It can be seen that the similarity matching algorithm can determine the path real time delay position and eliminate the ambiguity of the distance between OFDM symbols.

[0103] The single-beat expandable long-distance sensing signal can be used to detect the distance, and the periodic T p transmission can further detect the speed. The maximum unambiguous speed and the speed resolution depend on the repetition period and the observation time of the expandable long-distance sensing signal. Lengthening the observation time is the key to improving the speed resolution, but it occupies a large amount of time for communication signals. Therefore, a pre-detection scheme can be used to eliminate the speed ambiguity, i.e. a short period T ps continuous signal is transmitted to determine the speed interval, and then a long period T pl is used to improve the speed resolution, as shown in Figure 4 .

[0104] It is assumed that the system FFT point number is NFFT , subcarrier spacing is Δf, L ps is transmitted repeatedly with T p as the period in the pre-probing stage, the velocity attribution interval of the echo can be determined by the peak of the OFDM symbol dimension Fourier transform as:

[0105]

[0106] Then the periodic T pl is configured by using the TDD system frame structure, and the coherent observation time N p periods, the velocity resolution of the perceived target can be calculated as:

[0107]

[0108] Combined with the velocity attribution interval of the perceived target determined in the pre-probing stage, the real velocity of the perceived target can be obtained. Combined with the design of the scalable long-range sensing signal, the distance ambiguity elimination scheme and the high-resolution frame structure design, the sensing integrated waveform time-frequency domain configuration is completed.

[0109] If the length of the designed T ps is equal to the length of the OFDM symbol, the continuous wave design is adopted, the length of the scalable long-range sensing signal generated in step 2 is expanded from L symbols to L+L p -1, and then the step 4 stage frequency domain mapping method is used, followed by time domain mapping to adjacent L+L p -1 OFDM symbols, L p OFDM channels can be obtained, thereby reducing the overhead, as shown in Figure 5 .

Claims

1. A long-distance high-precision integrated detection waveform design method, characterized in that, Comprising the following steps: Step 1, determine the number of transmission combs N according to the number of sensing waveforms supported by the system at the same time comb ; Step 2, according to the perceived distance requirement, generate scalable long-distance communication signal, scalable long-distance communication signal lasts L symbol; considering the uplink and downlink timing relationship of TDD system, the maximum effective sensing distance is Wherein, c is the speed of light, is the signal length, is the signal cyclic prefix CP length, T c is the minimum time unit in 3GPP protocol, T TA is the uplink-downlink timing offset, the table between the perception distance and the duration symbol is generated according to the maximum effective perception distance formula, and L is obtained according to the perception distance requirement. The scalable long-distance communication signal takes the lth OFDM symbol as the starting point in a subframe and lasts L symbols, so the sequence of the l'th OFDM symbol is: wherein, is the number of transmitted combs, and is a ZC sequence, and cp is the length of the cyclic prefix of the communication system, and FFT is the number of FFT points of the communication system, and ZC is the length of the sequence, and the above equation indicates that the tail L cp of the signal is copied as a cyclic prefix to guarantee the continuity of the splice. Step 3, according to the speed detection requirement of the moving target and the typical communication time slot configuration, determine the short period T ps , the number of short period repeated transmission L p , the long period T pl , the number of long period repeated transmission N p ; T ps and L p The determination is as follows: wherein, denotes a floor function, denotes a ceiling function, λ is a wavelength, T ofdm is an OFDM symbol time length including a cyclic prefix, v max is a maximum expected probe speed, v sect is a segment interval speed length for speed probing; T pl and N p The determination is as follows: T pl = n pl T period Wherein, Δv is the expected speed detection accuracy of the moving target, T period is the time length of a commonly used typical communication time slot configuration on the base station side, n pl is a configurable integer; Step 4, complete the frequency domain signal mapping of the pre-probing stage, complete the subcarrier mapping of adjacent L OFDM symbols in a frequency domain continuous manner; The mapping formula of the subcarrier continuous mapping mode is as follows: where s grid is the time-frequency grid of OFDM, n comb is the comb index corresponding to the sensing waveform, L is a sensing signal block in the pre-sounding phase, and l' is the index of OFDM symbols within the sensing signal block. Step 5, Time domain signal mapping for the completion of the pre-detection phase, the frequency domain mapped signal at Step 4 phase is mapped according to the configured T ps L p is transmitted periodically; The time domain mapping formula of the pre-probing stage is as follows, where s pred is the time-frequency grid of the pre-detection phase, l' is the index of the OFDM symbol within the sensing signal block, and l" is the index of the sensing signal block; if the designed T ps length is equal to the OFDM symbol length, a continuous wave design is adopted, the expandable long-range sensing signal generated in step 2 is first expanded from L symbols to L+L p -1, and then the frequency domain mapping method in step 4 is adopted, followed by time domain mapping to adjacent L+L p -1 OFDM symbols, to obtain L p OFDM channels, and the time domain mapping formula of the pre-detection phase is as follows: n comb to perceive the comb index corresponding to the waveform; Step 6, complete the frequency domain signal mapping of the probing stage, complete the subcarrier mapping of adjacent L OFDM symbols in a selected comb manner; the mapping formula of the subcarrier comb manner is as follows: where s grid is the time-frequency domain grid of OFDM, n comb is the comb index corresponding to the sensing waveform, L OFDM signals are a sensing signal block in the probing phase, and l' is the index of OFDM symbols within the sensing signal block. Step 7, time domain signal mapping of the completion of the detection phase, the frequency domain mapping signal of step 5 phase, according to the configuration of the long period T pl Repeat transmission N p times; the time domain mapping formula of the detection phase is as follows: where s detect is the time-frequency grid of the probing phase, l' is the index of the OFDM symbol within the sensing signal block, and l" is the index of the sensing signal block.

2. The method of claim 1, wherein the method is characterized by: In step 1, the number of transmission combs N is determined according to the number of sensing waveforms that the system needs to support simultaneously comb ; where N max-sense is the maximum number of perceived waveforms that need to be supported simultaneously, |{a,u,v}| represents the number of parameter sets used for perception, each pair u and v determines one root sequence, u is the group number of the uplink sounding reference signal, v is the base sequence number within the group, and a is the cyclic shift.

3. The method of claim 1, wherein the method is characterized by: For the RRU using the Option7-2 format, the RRU side has the function of low-order physical layer processing, including FFT / IFFT, adding and removing cyclic prefix, phase compensation function; at this time, the phase compensation in the 3GPP protocol will destroy the phase continuity of the scalable long-distance communication signal splicing, in order to ensure the transparent support to the RRU, the designed scalable long-distance signal needs to be phase anti-compensated, wherein μ is a protocol numerology, f0 is a carrier frequency, is a position index of the l'th common OFDM symbol in a subframe, T c is a minimum time unit in 3GPP protocol, the calculation of the position index is consistent with the protocol, for a specific numerology, a phase compensation table is pre-generated in an iterative manner, and the position index is generated in the following manner, wherein is the OFDM signal length, is the OFDM signal cyclic prefix CP length.

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