阅读说明：本技术 一种基于串行干扰消除的vdes上行接收信号检测方法 (VDES uplink received signal detection method based on serial interference elimination ) 是由 李洪星 丁晓光 于 2020-11-11 设计创作，主要内容包括：本发明属于无线通信技术领域,具体涉及一种基于串行干扰消除的VDES上行接收信号检测方法,该方法包括以下步骤：系统初始化；按照信道估计值的二范数对船舶进行排序；根据排序结果,利用串行干扰消除检测算法,依次对各船舶的发送信号进行检测,得到上行接收信号检测结果。与现有的ZF、MMSE检测方法相比,本发明采用串行干扰消除在接收信号中逐级消去干扰信号带来的影响,并且在传统串行干扰消除的基础上进行了改进,在每一级信号检测时采用最小均方误差检测。因此本发明所公开的方法与现有的ZF、MMSE检测方法相比可以有效提高检测准确度、提高通信质量,而且硬件上易于实现。(The invention belongs to the technical field of wireless communication, and particularly relates to a VDES uplink received signal detection method based on serial interference elimination, which comprises the following steps: initializing a system; sequencing the ships according to the two norms of the channel estimation values; and according to the sequencing result, detecting the sending signals of each ship in sequence by using a serial interference elimination detection algorithm to obtain an uplink receiving signal detection result. Compared with the existing ZF and MMSE detection methods, the method adopts serial interference elimination to eliminate the influence caused by interference signals step by step in the received signals, improves the traditional serial interference elimination, and adopts minimum mean square error detection during each stage of signal detection. Therefore, compared with the existing ZF and MMSE detection methods, the method disclosed by the invention can effectively improve the detection accuracy and the communication quality, and is easy to realize on hardware.)

1. A VDES uplink received signal detection method based on serial interference cancellation comprises the following steps:

the method comprises the following steps: initializing a system:

assuming that N ships belonging to different self-organized cells simultaneously transmit signals to a satellite at the same frequency, the sum of the N ship signals received by the satellite is y, and if the satellite antenna has M wave beams, y is a complex column vector of M orders and is recorded as y belonging to C^M×1Obtaining an uplink channel estimation value from each ship to the satellite by using pilot signals sent by N ships;

step two: sequencing the N ships according to the two norms of the channel estimation values:

calculating the two norms of the uplink channel estimation value of each ship, sequencing and arranging the serial numbers of the N ships according to the two norms from large to small, namely the serial number of the ship with the largest two norms is 1, and the corresponding uplink channel estimation value is recorded asThe estimated value of the uplink channel with the ship serial number i is recorded asThe ship serial number with the minimum two-norm value is N, and the corresponding uplink channel estimation value is recorded asWhere i e 1,2, …,n }, then the satellite received signal sumsWherein x_i∈C^1×1For the transmission of the ith ship, h_i∈C^M×1Is the true value of the uplink channel from the ith ship to the satellite, the uplink transmission power of all ships is p, n belongs to C^M×1Representing equivalent additive white Gaussian noise, each element in the column vector is independent, and the variance of each element is sigma²；

Step three: according to the sequencing result, the sending signals of all ships are sequentially detected by using a serial interference elimination detection algorithm to obtain an uplink receiving signal detection result, wherein the algorithm process is as follows:

1) initialization: the number i is 1, i is equal to 1,y⁽ⁱ⁾＝y；

2) sending signal x of ith ship by using minimum mean square error detection method_iDetecting to obtain x_iResult of detection of

The filter matrix of the minimum mean square error isI_NIs an NxN identity matrix, W⁽ⁱ⁾Ith action ofThe ith ship sends a signal x_iThe detection result isWhereinRepresents a hard decision;

3) cancelling signal x_iInfluence on the signal to be detected:

using the up channel estimation and signal x of the ith ship_iIs multiplied by the detection result of (b), in the received signal y⁽ⁱ⁾Subtracting the result of the multiplication to obtain a residual signal, i.e.

4) Channel estimation matrixIs set to 0 to obtain

5) Judging whether i is equal to N:

if i is not equal to N, making i equal to i +1, returning to substep 2) and continuously detecting a next ship sending signal;

and if the i is equal to N, the detection of all ship sending signals is finished, and the algorithm is ended.

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a VDES uplink received signal detection method based on serial interference elimination.

Background

A VDES (VHF Data Exchange System) is a System for marine satellite communication proposed by international navigation organization in 2013, and the System upgrades an existing AIS (Automatic Identification System) from different aspects, so as to solve various problems of the existing System and provide high-quality marine service for ships passing through the sea.

In the VDES system, self-organizing cells are formed between ships in close proximity to meet the requirement of data exchange in a self-organizing mode. When the ships in the self-organizing cell use the wireless channel, the Time-division Multiple Access (TDMA) mode is adopted for Time slot Access, and the conflict of Time slot use can be avoided by utilizing the frame mapping table and Time slot reservation. However, there is no direct communication between ships in different ad hoc cells, and it is difficult to coordinate time slot collision of uplink transmission, and a satellite covers a plurality of ad hoc cells at the same time, so that it is inevitable that a plurality of different ad hoc cells allocate transmission signals of ships in the same time slot. Therefore, in the same time slot and frequency, superposition of uplink received signals of multiple ships occurs at the satellite receiving end, the receiving end cannot distinguish the signals of the ships due to the superposition, and interference among the multiple ship signals exists during receiving detection.

For the above problems, the existing proposals (for example, "IALA G1139 standard") recommend using the existing zf (zero forcing) and mmse (minimum mean square error probability) received signal detection methods, and these signal detection methods do not consider the mutual interference between the signals of multiple vessels, so that the signal detection accuracy is limited, the communication quality index is not high, and the bit error rate is high.

Serial Interference Cancellation (SIC) is a method for eliminating interference between signals of multiple users and improving signal detection accuracy. The method firstly judges a single transmission signal in a receiving signal through a Matched Filtering (MF) detection algorithm, and once a transmission signal is detected, the interference of the signal is subtracted from the original receiving signal. Interference between signals can be substantially eliminated by a loop of multi-stage detection. Since interference between ship uplink received signals of different ad hoc cells is not considered in current maritime satellite communication, serial interference cancellation is not applied to the VDES system. In addition, the matched filtering algorithm in the successive interference cancellation also has the problem of low detection accuracy.

In summary, in the VDES system, the conventional uplink received signal detection method does not consider interference between uplink signals received by the satellite from vessels in different ad hoc cells. With the development of the marine transportation industry, ships are more and more on the sea, and if the interference between uplink signals received by a satellite end cannot be eliminated, the communication quality is worse and worse.

At present, the requirement of maritime satellite communication on communication quality is continuously improved, so that serial interference elimination needs to be introduced into a VDES system for improvement, and a receiving signal detection method with high detection accuracy and capable of eliminating the interference among multiple ship signals is researched to improve the VDES communication quality, which is an important problem to be solved at present.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a VDES uplink received signal detection method based on serial interference elimination, which can effectively eliminate the interference between multiple ship uplink signals received by a satellite terminal and improve the communication quality.

The scheme for solving the technical problems is as follows:

a VDES uplink received signal detection method based on serial interference cancellation comprises the following steps:

the method comprises the following steps: initializing a system:

assuming that N ships belonging to different self-organized cells simultaneously transmit signals to a satellite at the same frequency, the sum of the N ship signals received by the satellite is y, and if the satellite antenna has M wave beams, y is a complex column vector of M orders and is recorded as y belonging to C^M×1Obtaining an uplink channel estimation value from each ship to the satellite by using pilot signals sent by N ships;

step two: sequencing the N ships according to the two norms of the channel estimation values:

calculating two norms of uplink channel estimation values of each ship, and performing large-to-small operation on N ships according to the two normsSequencing and arranging serial numbers, namely the serial number of the ship with the maximum two-norm value is 1, and the corresponding uplink channel estimation value is recorded asThe estimated value of the uplink channel with the ship serial number i is recorded asThe ship serial number with the minimum two-norm value is N, and the corresponding uplink channel estimation value is recorded asWhere i ∈ {1,2, …, N }, the satellite received signal sumsWherein x_i∈C^1×1For the transmission of the ith ship, h_i∈C^M×1Is the true value of the uplink channel from the ith ship to the satellite, the uplink transmission power of all ships is p, n belongs to C^M×1Representing equivalent additive white Gaussian noise, each element in the column vector is independent, and the variance of each element is sigma²；

Step three: according to the sequencing result, the sending signals of all ships are sequentially detected by using a serial interference elimination detection algorithm to obtain an uplink receiving signal detection result, wherein the algorithm process is as follows:

1) initialization: the number i is 1, i is equal to 1,y⁽ⁱ⁾＝y；

2) sending signal x of ith ship by using minimum mean square error detection method_iDetecting to obtain x_iResult of detection of

The filter matrix of the minimum mean square error isI_NIs an NxN unit matrix, W⁽ⁱ⁾Ith action of The ith ship sends a signal x_iThe detection result isWhereinRepresents a hard decision;

3) cancelling signal x_iInfluence on the signal to be detected:

using the up channel estimation and signal x of the ith ship_iIs multiplied by the detection result of (b), in the received signal y⁽ⁱ⁾Subtracting the result of the multiplication to obtain a residual signal, i.e.

4) Channel estimation matrixIs set to 0 to obtain

5) Judging whether i is equal to N:

if i is not equal to N, making i equal to i +1, returning to substep 2) and continuously detecting a next ship sending signal;

and if the i is equal to N, the detection of all ship sending signals is finished, and the algorithm is ended.

Interference among uplink signals of ships in different self-organization cells is not considered in the existing maritime satellite communication, so that the communication quality is not high. Therefore, the application discloses a method for detecting a VDES uplink received signal based on successive interference cancellation, which introduces the successive interference cancellation into a VDES system. Compared with the existing ZF and MMSE detection methods of VDES, the method not only eliminates the interference between the uplink signals of multiple ships by using serial interference elimination, but also improves the method on the basis of the traditional serial interference elimination, namely, in a single cycle of the cycle iteration of the serial interference elimination, each level of signal is detected by adopting the minimum mean square error instead of the traditional matched filtering algorithm. As can be seen from practical use, the detection performance of the minimum mean square error is superior to that of matched filtering, so that by using the method disclosed by the application, better maritime satellite communication quality can be provided.

In addition, compared with the existing ZF and MMSE detection methods, the VDES uplink received signal detection method based on serial interference elimination disclosed by the invention has the advantages that the hardware change is not large, and the implementation is easy.

Compared with the prior art, the invention has the following beneficial effects:

the invention discloses a VDES uplink received signal detection method based on serial interference elimination. Compared with the existing ZF and MMSE detection methods, the method can effectively improve the detection accuracy and the maritime satellite communication quality, is easy to realize in hardware, and is favorable for low-cost popularization and implementation.

Drawings

Fig. 1 is a general flow chart of a method for detecting a VDES uplink received signal based on successive interference cancellation according to the present invention;

fig. 2 is a schematic diagram of uplink data transmission in a method for detecting a VDES uplink received signal based on successive interference cancellation disclosed in the present invention;

FIG. 3 is a block diagram of a serial interference cancellation detection algorithm in a method for detecting a VDES uplink received signal based on serial interference cancellation disclosed in the present invention;

FIG. 4 is a simulation result diagram of the average bit error rate of the received signal in the method for detecting the VDES uplink received signal based on the successive interference cancellation disclosed in the present invention;

Detailed Description

The invention will be further explained with reference to the drawings.

Example 1

As shown in fig. 1, a method for detecting a VDES uplink received signal based on successive interference cancellation includes the following steps:

the method comprises the following steps: initializing a system:

assuming that N ships belonging to different self-organizing cells simultaneously transmit signals to a satellite at the same frequency, as shown in fig. 2, the sum of the N ship signals received by the satellite is y, and if the satellite antenna has M beams, y is a complex column vector of M order, and is recorded as y ∈ C^M×1Pilot signals sent by N ships obtain an uplink channel estimation value from each ship to the satellite;

step two: sequencing the N ships according to the two norms of the channel estimation values:

calculating the two norms of the uplink channel estimation value of each ship, sequencing and arranging the serial numbers of the N ships according to the two norms from large to small, namely the serial number of the ship with the largest two norms is 1, and the corresponding uplink channel estimation value is recorded asThe estimated value of the uplink channel with the ship serial number i is recorded asThe ship serial number with the minimum two-norm value is N, and the corresponding uplink channel estimation value is recorded asWhere i ∈ {1,2, …, N }, the satellite received signal sumsWherein x_i∈C^1×1For the transmission of the ith ship, h_i∈C^M×1Is the true value of the uplink channel from the ith ship to the satellite, the uplink transmission power of all ships is p, n belongs to C^M×1Representing equivalent additive white gaussian noise, each element in the column vector is independent,the variance of each element is σ²；

Step three: according to the sequencing result, the serial interference cancellation detection algorithm is used for sequentially detecting the sending signals of all ships to obtain an uplink receiving signal detection result, and as shown in fig. 3, the algorithm process is as follows:

1) initialization: the number i is 1, i is equal to 1,y⁽ⁱ⁾＝y；

2) sending signal x of ith ship by using minimum mean square error detection method_iDetecting to obtain x_iResult of detection of

The filter matrix of the minimum mean square error isI_NIs an NxN unit matrix, W⁽ⁱ⁾Ith action of The ith ship sends a signal x_iThe detection result isWhereinRepresents a hard decision;

3) cancelling signal x_iInfluence on the signal to be detected:

using the up channel estimation and signal x of the ith ship_iIs multiplied by the detection result of (b), in the received signal y⁽ⁱ⁾Subtracting the result of the multiplication to obtain a residual signal, i.e.

4) Channel estimation matrixIs set to 0 to obtain

5) Judging whether i is equal to N:

if i is not equal to N, making i equal to i +1, returning to substep 2) and continuously detecting a next ship sending signal;

and if the i is equal to N, the detection of all ship sending signals is finished, and the algorithm is ended.

Example 2 (Experimental example)

The following is a simulation experiment of MATLAB software performed according to the method for detecting a VDES uplink received signal based on successive interference cancellation disclosed in the present invention, so as to illustrate the feasibility and effectiveness of the method of the present invention.

The simulation parameters are set as the beam number M of the satellite antenna is 10, the number N of the ships is 5, and the channel h_i∈C^M×1Each element in the channel is independently distributed according to a circularly symmetric complex Gaussian with the mean value of 0 and the variance of 1, different channels are mutually independent, and additive white Gaussian noise n belongs to C^M×1Each element in (1) is independently subject to a mean of 0 and a variance of σ²Is circularly symmetric and has a complex gaussian distribution.

The simulation experiment result is shown in fig. 4, the abscissa is the signal-to-noise ratio, and the signal-to-noise ratio is p/sigma²The ordinate is the average error rate of the received signals, which means the average error rate of the received signals of N ships, and the simulation result is the statistical average of the Monte Carlo (Monte Carlo) method. In the figure, "ZF" and "MMSE" refer to the traditional zero-forcing and minimum mean square error detection methods, respectively, and "SIC" is the successive interference cancellation detection method disclosed by the present invention.

Fig. 4 reflects the relationship between the average bit error rate of the received signal and the signal-to-noise ratio, and it can be seen from the figure that the serial interference cancellation detection method provided by the present invention has the error rate lower than the ZF and MMSE detection methods because of the addition of the successive interference cancellation of the serial interference cancellation and the use of the minimum mean square error detection in the signal detection of each stage, and the corresponding communication quality is high if the error rate is low. And the advantage becomes more and more obvious as the signal-to-noise ratio increases.

In summary, the present invention discloses a method for detecting a VDES uplink received signal based on serial interference cancellation. Compared with the existing ZF and MMSE detection methods, the method can effectively reduce the detection error rate and improve the communication quality, and is easy to realize on hardware.