CN111683034B - OFDM-based large Doppler wireless communication time-frequency synchronization method - Google Patents
OFDM-based large Doppler wireless communication time-frequency synchronization method Download PDFInfo
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Abstract
The invention discloses a large Doppler wireless communication time-frequency synchronization method based on OFDM, and belongs to the technical field of wireless communication. Which comprises the following steps: the method comprises the steps of utilizing a preamble symbol to achieve symbol coarse timing synchronization, utilizing the preamble symbol to achieve large Doppler frequency offset coarse estimation, utilizing a frequency offset estimation value to perform frequency offset preliminary compensation correction on a symbol, utilizing a PSS symbol after the frequency offset preliminary compensation to perform correlation operation with a local known PSS symbol, achieving symbol accurate timing synchronization, performing FFT operation on a data symbol, achieving signal time-frequency domain conversion, utilizing a received data symbol internal frequency domain pilot frequency and a local known pilot frequency, and achieving residual frequency offset estimation and real-time compensation through a first-order filtering frequency-locking loop. The invention can realize the time and frequency synchronization of the wireless communication system under the large Doppler scene based on OFDM under the condition that neither the user terminal nor the gateway station has ephemeris, and meets the synchronous demodulation requirements under the conditions of large Doppler and multipath of the broadband high-flux satellite in the future.
Description
Technical Field
The invention relates to the technical field of wireless communication, in particular to a large Doppler wireless communication time-frequency synchronization method based on OFDM.
Background
Orthogonal Frequency Division Multiplexing (OFDM) technology is widely used in terrestrial wireless cellular communication systems due to its strong multipath resistance and high spectrum efficiency, and in particular, the NR Release15 dependent Networking (NSA) and Release 16 independent networking (SA) standards of the fifth generation mobile communication system (5G) still use OFDM waveforms as core waveforms for physical layer transmission. However, the receiving end of the OFDM technology is sensitive to Carrier Frequency Offset (CFO) and symbol timing offset which lead to inter-carrier interference (ICI), which is one of the main problems that the OFDM technology is restricted to be implemented in a wireless communication system under a large dynamic doppler condition, especially in a satellite communication system.
At present, some researches have been made on the problem of large doppler frequency shift, for example, in the paper "estimation and compensation method of carrier frequency offset of upper (lower) link of low earth orbit satellite multi-carrier communication system" published by Zhang Yi, Liu Tian, etc., it is necessary to use the ephemeris of a gateway station to realize the frequency synchronization between the upper and lower links of the satellite-ground link; in a paper published by treble, tianding, etc. "a carrier Synchronization method for a 5G-based low-orbit satellite communication system", a Primary Synchronization Signal (PSS) Signal is used and a Kalman Filter is used to estimate the carrier frequency offset and the rate of change.
With the development demand of future air, space and ground integrated information networks, the mutual supplement and fusion of satellite communication and ground 5G and evolution technologies thereof are the development trend of future satellite communication systems. Meanwhile, with the requirement of information transmission rate and the increasing congestion of the L \ S frequency band, the frequency band of the broadband satellite communication system is gradually shifted to the Ku/Ka or even higher U, V frequency band in the future, so that the satellite communication system has larger CFO. Particularly in an LEO low-orbit satellite communication scene, the satellite has high moving speed, large-scale Doppler frequency shift and multipath channel fading exist between the satellite and the earth, and the Doppler frequency shift is far larger than the subcarrier spacing of an OFDM system generally, and exceeds the current frequency offset estimation capability of the ground 5G standard, so that the carrier synchronization and the symbol synchronization at the satellite-earth receiving and transmitting ends face a great problem. Therefore, time-frequency synchronization is the first problem to be solved by a wireless communication system, especially a satellite communication system fused with 5G under a large doppler shift condition, and restricts the effective application of the 5G OFDM technology in satellite communication.
Disclosure of Invention
In view of the above, the present invention provides a time-frequency synchronization method for large doppler wireless communication based on OFDM, which can achieve time and frequency synchronization of a wireless communication system under a large doppler condition, particularly can achieve precise symbol timing synchronization and estimation and real-time compensation of large doppler frequency shift for a satellite communication system, and meet the requirements of synchronous demodulation under the conditions of large doppler and multipath of a broadband high-throughput satellite in the future.
In order to achieve the purpose, the invention adopts the technical scheme that:
a big Doppler wireless communication time frequency synchronization method based on OFDM is applied to a receiving end of a wireless communication system, a main synchronization symbol and a data symbol frequency domain pilot frequency which are the same as those of the transmitting end are stored in the receiving end, and the method comprises the following steps:
(1) receiving OFDM transmission signals including a preamble symbol, a main synchronization symbol and a data symbol, performing sliding correlation operation by using the preamble symbol, detecting a correlation peak, and performing symbol coarse timing synchronization;
(2) performing coarse estimation of large Doppler frequency offset by using the preamble symbol to realize joint estimation of integer multiple frequency offset and decimal multiple frequency offset;
(3) performing frequency offset preliminary compensation correction on the preamble symbol, the main synchronization symbol and the data symbol by using the estimation result of the step (2);
(4) performing correlation operation on the primary synchronization symbol subjected to preliminary frequency offset compensation and correction and a locally stored primary synchronization symbol, searching for the maximum correlation time offset, and realizing accurate timing synchronization of the OFDM transmission signal;
(5) performing FFT operation on the data symbols after the accurate timing synchronization to realize the time-frequency domain conversion of the data symbols;
(6) and performing residual frequency offset estimation by using the frequency domain pilot frequency in the data symbol after time-frequency domain conversion and the locally stored frequency domain pilot frequency, realizing decimal residual frequency offset estimation and tracking by using a first-order filtering frequency-locking loop, and performing frequency offset real-time compensation in a periodic iteration mode.
Further, the preamble symbol has a time-domain periodicity, and is composed of I repeated preamble sequences, and the time-domain periodicity is L, I and L are integers, the length of the preamble symbol is N, and N/I ═ L, N × Δ f/(2 × L) > | fDop_maxWhere Δ f is the OFDM symbol subcarrier spacing, fDop_maxIs the maximum frequency offset of the communication system.
Further, in the step (6), each iteration cycle includes the following steps:
(601) and performing residual frequency offset compensation correction on the current data symbol, namely:
wherein, Yi(k) Is the ith data symbol, Yi' (k) is the corrected ith data symbol,
for the residual frequency offset value estimated by the frequency locked loop,
the initial iteration value of (a) is 0, e is a natural constant, and j is an imaginary unit;
(602) performing cross-correlation by using the frequency domain pilot frequency in the current data symbol and the locally stored frequency domain pilot frequency of the data symbol, wherein the phase of the correlation value is the residual frequency offset estimation value of the current data symbol
(603) The residual frequency offset of the next data symbol is predicted and estimated by using the frequency-locked loop to obtain the residual frequency offset of the next data symbol
Namely:
where F is the filter gain, ωnFor filter bandwidth, DLL _ Reg (i) stores a value for the current register, DLL _ Reg (i +1) stores a value for the register at the next time,
is an intermediate value.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention provides a time-frequency synchronization method of a wireless communication system based on an OFDM multi-carrier technology, which can realize accurate symbol timing synchronization, estimation and real-time compensation of large Doppler frequency shift of the wireless communication system under a large Doppler scene based on the OFDM technology, and meet the synchronous demodulation requirements of a future broadband high-flux satellite under large Doppler and multipath conditions.
(2) The invention can realize time-frequency synchronization under large dynamic condition only based on signal system without relying on ephemeris calculation of gateway station, satellite and terminal, thereby realizing flexible application of satellite and 5G fusion.
(3) The invention realizes real-time estimation and compensation of Doppler based on pilot frequency in data symbols transmitted in real time, effectively solves the problem of real-time Doppler change between satellites and grounds, and can meet the requirement of correct demodulation of a receiving end.
Drawings
Fig. 1 is a flowchart of a time-frequency synchronization method in an embodiment of the present invention.
Fig. 2 is a schematic diagram of a frequency offset estimation and compensation process in an embodiment of the invention.
Fig. 3 is a diagram illustrating the root mean square error performance of symbol synchronization deviation in gaussian channel (AWGN) according to an embodiment of the present invention.
Fig. 4 shows the rms error performance of the symbol synchronization deviation in LOS multipath channel in the embodiment of the present invention.
Fig. 5 shows the error performance of the time-frequency synchronization method in different channels according to the embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the figures and examples.
A big Doppler wireless communication time frequency synchronization method based on OFDM is applied to a receiving end of a wireless communication system, a main synchronization symbol and a data symbol frequency domain pilot frequency which are the same as those of the transmitting end are stored in the receiving end, and the method comprises the following steps:
(1) receiving OFDM transmission signals including a preamble symbol, a main synchronization symbol and a data symbol, performing sliding correlation operation by using the preamble symbol, detecting a correlation peak, and performing symbol coarse timing synchronization;
(2) performing coarse estimation of large Doppler frequency offset by using the preamble symbol to realize joint estimation of integer multiple frequency offset and decimal multiple frequency offset;
(3) performing frequency offset preliminary compensation correction on the preamble symbol, the main synchronization symbol and the data symbol by using the estimation result of the step (2);
(4) performing correlation operation on the primary synchronization symbol subjected to preliminary frequency offset compensation and correction and a locally stored primary synchronization symbol, searching for the maximum correlation time offset, and realizing accurate timing synchronization of the OFDM transmission signal;
(5) performing FFT operation on the data symbols after the accurate timing synchronization to realize the time-frequency domain conversion of the data symbols;
(6) and performing residual frequency offset estimation by using the frequency domain pilot frequency in the data symbol after time-frequency domain conversion and the locally stored frequency domain pilot frequency, realizing decimal residual frequency offset estimation and tracking by using a first-order filtering frequency-locking loop, and performing frequency offset real-time compensation in a periodic iteration mode.
Further, the preamble symbol has a time-domain periodicity, and is composed of I repeated preamble sequences, and the time-domain periodicity is L, I and L are integers, the length of the preamble symbol is N, and N/I ═ L, N × Δ f/(2 × L) > | fDop_maxWhere Δ f is the OFDM symbol subcarrier spacing, fDop_maxIs the maximum frequency offset of the communication system.
Further, in the step (6), each iteration cycle includes the following steps:
(601) and performing residual frequency offset compensation correction on the current data symbol, namely:
wherein, Yi(k) Is the ith data symbol, Yi' (k) is the corrected ith data symbol,
for the residual frequency offset value estimated by the frequency locked loop,
the initial iteration value of (a) is 0, e is a natural constant, and j is an imaginary unit;
(602) performing cross-correlation by using the frequency domain pilot frequency in the current data symbol and the locally stored frequency domain pilot frequency of the data symbol, wherein the phase of the correlation value is the residual frequency offset estimation value of the current data symbol
(603) The residual frequency offset of the next data symbol is predicted and estimated by using the frequency-locked loop to obtain the residual frequency offset of the next data symbol
Namely:
where F is the filter gain, ωnFor filter bandwidth, DLL _ Reg (i) stores a value for the current register, DLL _ Reg (i +1) stores a value for the register at the next time,
is an intermediate value.
The following is a more specific example:
a large Doppler wireless communication time-frequency synchronization method based on OFDM can be applied to a satellite communication system based on an OFDM or DFT-S-OFDM discrete Fourier transform spread OFDM system and other large Doppler wireless communication systems.
In this embodiment, a satellite communication system based on an OFDM system is selected, where an OFDM transmission signal including a preamble symbol and a PSS synchronization symbol reaches a receiving end through a wireless channel, and the receiving end performs symbol frequency offset coarse synchronization and compensation, symbol precision synchronization, and residual frequency offset estimation and compensation to complete time-frequency synchronization of the satellite communication system. The data transmission frame length of the OFDM system is 10ms, the OFDM system comprises 10 1ms subframes, each subframe comprises 4 0.25ms time slots, and each time slot comprises 14 OFDM symbols; the FFT point number of each OFDM symbol is 2048, the length of a cyclic prefix is 144, the interval of subcarriers is 60kHz, and the communication bandwidth is 100 MHz; a frequency domain pilot frequency is inserted into the data symbol every 12 sub-carrier intervals, and 125 data pilot frequencies are inserted in total; the preamble symbol is a complete OFDM symbol and comprises 32 sections of repeated data with a period of 64 and a 144-point cyclic prefix; the channel counting model selects an AWGN channel and a multi-path channel containing an LOS path, the carrier frequency is 30GHz, the Doppler frequency shift variation range is +/-800 khz, and the Doppler frequency shift variation range changes according to a sine rule in a satellite overhead period.
The flow of the method is shown in fig. 1, and specifically comprises the following steps:
step 1, performing sliding cross-correlation operation by using the received preamble symbol y (n), and realizing coarse timing synchronization of the symbol by detecting a correlation peak, wherein the timing time falls in a plurality of sampling points before and after the starting time of the preamble symbol:
in the above formula, p (n) is the detection value at the sampling point n, L is the preamble symbol period, 64 in this embodiment, D is the length of the sliding correlation window, 128 in this embodiment, the numerator is the autocorrelation coefficient of the received signal in the sliding window and the delay of L sampling points, and the denominator is the energy of the received signal in the sliding window.
wherein x (k) is a preamble symbol of a transmitting end which is not affected by the Doppler frequency offset channel, N is the length of the preamble symbol, Δ f is the subcarrier spacing, TsIs the sampling interval. E ═ N ═ Δ f ═ TsIs the normalized frequency offset relative to the subcarrier spacing.
The variables R are defined as:
where the superscript indicates taking the conjugate, Q is the length of the leader sequence, and in this embodiment, L ═ Q ═ 64.
Then, the normalized coarse doppler shift estimate can be obtained as:
wherein, angle (r) represents angle calculation, and the angle range is (-pi, pi), then the estimation range of the normalized coarse frequency offset is
Involving integer frequency shiftsAnd a fractional frequency offset.
Step 3, performing frequency offset preliminary compensation correction on all symbols by using the rough frequency offset estimation value, namely:
where y' (k) is the received time domain signal after frequency offset compensation, and at this time, each OFDM symbol only includes a residual fractional frequency shift, and the final effect of the OFDM symbol is represented by the phase rotation of each frequency domain subcarrier signal.
And 4, performing cross-correlation operation on the PSS primary synchronization symbol subjected to the initial frequency offset compensation and a locally known PSS primary synchronization symbol, and realizing accurate timing synchronization of the symbols by searching for the maximum correlation time offset, namely:
wherein argmax (·) represents finding the maximum modulus, | · | represents calculating the modulus, NpC is the length of the PSS primary synchronization symbol, 63 in this embodiment, N + L, for the maximum search radius of the symbol timingcpFor the length of preamble symbol plus cyclic prefix, 2192 in this embodiment, s (k) is a locally known synchronization symbol without various kinds of synchronization deviation effects. Maximum offset m by finding maximum correlation value using maximum likelihood detectorOFDMI.e. the exact symbol timing position.
Y(k)＝FFT(y′OFDM(k))
where FFT () represents a fast fourier transform.
(1) and performing frequency offset compensation on the ith data OFDM symbol according to the residual frequency offset estimation value of the first i-1 OFDM symbols, namely:
wherein, Yi(k) For the ith frequency domain OFDM data symbol, Yi' (k) is the compensated ith frequency domain OFDM data symbol,
the value of the residual frequency offset estimated by the frequency-locked loop is, i is greater than or equal to 2, and the frequency offset compensation value of the 1 st OFDM symbol is 0, i.e. the 1 st OFDM symbol does not perform residual frequency offset compensation.
(2) And performing residual frequency offset estimation by using the frequency domain pilot frequency in the ith data symbol and the locally known frequency domain pilot frequency of the data symbol.
Since the residual frequency offset mainly causes a phase rotation of the data symbol frequency domain subcarrier signal, denoted by ψ, the pilot subcarriers within the data symbol can be expressed as:
Y′i,pilot(k)＝Si,pilot(k)*ejψ
wherein, Y'i,pilot(k) Representing the frequency domain value, S, of the pilot sub-carrier of a data symboli,pilot(k) The frequency domain values of the locally known data symbol pilot subcarriers without the influence of various types of synchronization deviation are shown.
Define intermediate variable R' (i):
wherein E is a set of pilot subcarrier index values. Then, the estimated value of the phase deviation caused by the residual frequency offset can be obtained as follows:
angle (·) represents the angle.
(3) Implementing next data symbol by frequency-locked loopThe prediction estimation of the signal residual frequency offset obtains the residual frequency offset of the next data symbol
Namely:
where F is the filter gain, ωnFor filter bandwidth, DLL _ Reg (i) stores a value for the current register, and DLL _ Reg (i +1) stores a value for the register at the next time.
And (4) the estimation and compensation of the residual frequency offset can be realized by repeating the steps (1) to (3).
Fig. 3 and fig. 4 show the root mean square error performance of the symbol synchronization deviation obtained by the method of the above embodiment under gaussian channel (AWGN) and LOS multipath channel, respectively. It can be seen from the figure that under both channel conditions, the performance of symbol synchronization is degraded as the frequency deviation CFO increases; secondly, under the influence of multipath characteristics, under the condition of the same frequency offset, the synchronization performance under an LOS multipath channel is lower than that of an AWGN channel; meanwhile, with the increase of the signal-to-noise ratio, the symbol synchronization method can obtain good performance under different CFO and channel conditions so as to meet the initial synchronization requirement of a satellite communication system under a large dynamic condition.
Fig. 5 shows the error performance of different channels obtained by the method of the above embodiment. As can be seen from the figure, under the condition that the same large frequency deviation CFO is 900khz, the time-frequency synchronization method of the embodiment has a lower error rate under different channel conditions and a high signal-to-noise ratio condition; meanwhile, under the condition of low signal-to-noise ratio, the error code performance under the LOS multipath channel is about 1dB worse than that of the AWGN channel. This is because under the condition of LOS channel, the bit error rate is not only affected by noise and frequency offset, but also interfered by multipath channel.
As can be seen from fig. 3 to fig. 5, under the AWGN and LOS multipath channel conditions, the time-frequency synchronization method of the present embodiment has good performance under the condition of high signal-to-noise ratio, is hardly affected by large doppler shift, and has better robustness.
The embodiment described above is only one specific embodiment of the present invention, and not all embodiments. Other embodiments, which can be obtained by those skilled in the art without any inventive step, are within the scope of the present invention.
Claims (3)
1. A big Doppler wireless communication time frequency synchronization method based on OFDM is characterized in that the method is applied to a receiving end of a wireless communication system, a main synchronization symbol and a data symbol frequency domain pilot frequency which are the same as those of the transmitting end are stored in the receiving end, and the method comprises the following steps:
(1) receiving OFDM transmission signals including a preamble symbol, a main synchronization symbol and a data symbol, performing sliding correlation operation by using the preamble symbol, detecting a correlation peak, and performing symbol coarse timing synchronization;
(2) performing coarse estimation of large Doppler frequency offset by using the preamble symbol to realize joint estimation of integer multiple frequency offset and decimal multiple frequency offset;
(3) performing frequency offset preliminary compensation correction on the preamble symbol, the main synchronization symbol and the data symbol by using the estimation result of the step (2);
(4) performing correlation operation on the primary synchronization symbol subjected to preliminary frequency offset compensation and correction and a locally stored primary synchronization symbol, searching for the maximum correlation time offset, and realizing accurate timing synchronization of the OFDM transmission signal;
(5) performing FFT operation on the data symbols after the accurate timing synchronization to realize the time-frequency domain conversion of the data symbols;
(6) and performing residual frequency offset estimation by using the frequency domain pilot frequency in the data symbol after time-frequency domain conversion and the locally stored frequency domain pilot frequency, realizing decimal residual frequency offset estimation and tracking by using a first-order filtering frequency-locking loop, and performing frequency offset real-time compensation in a periodic iteration mode.
2. The OFDM-based time-frequency synchronization method for large Doppler wireless communication, wherein the preamble symbol has a time-domain periodicity, and is composed of I repeated preamble sequences, and the time-domain periodicity is L, both I and L are integers, the length of the preamble symbol is N, and N/I ═ L, N ═ Δ f/(2 ═ L) > | fDop_maxWhere Δ f is the OFDM symbol subcarrier spacing, fDop_maxIs the maximum frequency offset of the communication system.
3. The OFDM-based time-frequency synchronization method for large Doppler wireless communication, according to claim 1, wherein in the step (6), each iteration cycle comprises the following steps:
(601) and performing residual frequency offset compensation correction on the current data symbol, namely:
wherein, Yi(k) Is the ith data symbol, Y'i(k) For the corrected ith data symbol,
for the residual frequency offset value estimated by the frequency locked loop,
the initial iteration value of (a) is 0, e is a natural constant, and j is an imaginary unit;
(602) performing cross-correlation by using the frequency domain pilot frequency in the current data symbol and the locally stored frequency domain pilot frequency of the data symbol, wherein the phase of the correlation value is the residual frequency offset estimation value of the current data symbol
(603) The residual frequency offset of the next data symbol is predicted and estimated by using the frequency-locked loop to obtain the residual frequency offset of the next data symbol
Namely:
where F is the filter gain, ωnFor filter bandwidth, DLL _ Reg (i) stores a value for the current register, DLL _ Reg (i +1) stores a value for the register at the next time,
is an intermediate value.
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| CN116546615B (en) * | 2023-07-07 | 2023-09-12 | 芯迈微半导体(上海)有限公司 | Resynchronization method and device for long term evolution terminal in connection state |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103581100A (en) * | 2013-09-22 | 2014-02-12 | 复旦大学 | Coarse synchronization method for restraining multipath time delay and Doppler effect in LTE-FDD system |
| CN107086974A (en) * | 2017-03-27 | 2017-08-22 | 西安电子科技大学 | A kind of OFDM synchronous method under high dynamic environment |
| CN107241286A (en) * | 2017-04-20 | 2017-10-10 | 西安电子科技大学 | A kind of combination frequency domain and the carrier synchronization method of time domain estimation |
| CN110113285A (en) * | 2019-05-05 | 2019-08-09 | 东南大学 | A kind of ofdm system closed loop time-frequency synchronization method and device |
| CN110266623A (en) * | 2019-06-05 | 2019-09-20 | 北京邮电大学 | A kind of LEO satellite communication systems carrier synchronization method based on 5G |
| CN110932770A (en) * | 2019-11-13 | 2020-03-27 | 北京邮电大学 | Low earth orbit satellite-earth link synchronization sequence design and frequency offset estimation method |
| CN111147123A (en) * | 2019-12-23 | 2020-05-12 | 东方红卫星移动通信有限公司 | Carrier synchronization method of low-orbit satellite broadband OFDM communication system |
-
2020
- 2020-06-09 CN CN202010520081.3A patent/CN111683034B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103581100A (en) * | 2013-09-22 | 2014-02-12 | 复旦大学 | Coarse synchronization method for restraining multipath time delay and Doppler effect in LTE-FDD system |
| CN107086974A (en) * | 2017-03-27 | 2017-08-22 | 西安电子科技大学 | A kind of OFDM synchronous method under high dynamic environment |
| CN107241286A (en) * | 2017-04-20 | 2017-10-10 | 西安电子科技大学 | A kind of combination frequency domain and the carrier synchronization method of time domain estimation |
| CN110113285A (en) * | 2019-05-05 | 2019-08-09 | 东南大学 | A kind of ofdm system closed loop time-frequency synchronization method and device |
| CN110266623A (en) * | 2019-06-05 | 2019-09-20 | 北京邮电大学 | A kind of LEO satellite communication systems carrier synchronization method based on 5G |
| CN110932770A (en) * | 2019-11-13 | 2020-03-27 | 北京邮电大学 | Low earth orbit satellite-earth link synchronization sequence design and frequency offset estimation method |
| CN111147123A (en) * | 2019-12-23 | 2020-05-12 | 东方红卫星移动通信有限公司 | Carrier synchronization method of low-orbit satellite broadband OFDM communication system |
Non-Patent Citations (2)
| Title |
|---|
| 5G低轨卫星移动通信系统多普勒频偏估计算法;李耀晨等;《计算机测量与控制》;20181023;第26卷(第10期);第226-230页 * |
| 利用训练序列的OFDM时频同步算法;谭晓衡等;《重庆大学学报》;20090815;第32卷(第08期);第955-959页 * |
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