CN-122001488-A - Underwater wireless optical communication signal detection method based on multi-type detector array

CN122001488ACN 122001488 ACN122001488 ACN 122001488ACN-122001488-A

Abstract

The invention discloses an underwater wireless optical communication signal detection method based on a multi-type detector array, and belongs to the technical field of underwater wireless optical communication and signal detection. The method comprises the steps of receiving optical signals by a receiving end through a multi-type detector array comprising high-gain and low-gain photodetectors, converting the optical signals into M paths of electric signals, carrying out up-sampling on the signals, carrying out weighted combination on the M paths of signals through traversing weighting factors, calculating a projection vector, a judgment threshold and a pilot frequency error rate on each group of weighting factors, solving the optimal weighting factors and the corresponding optimal projection vectors by taking the minimum error rate as a criterion, carrying out projection on sampling point vectors of data symbols by utilizing the optimal projection vectors, and combining the optimal judgment threshold to recover 0 and 1 symbol. The invention combines the detection advantages of multiple types of detectors, can adaptively cope with the underwater large dynamic light intensity change, and remarkably improves the signal detection performance and the system reliability.

Inventors

HUANG NUO
LU JIANGXIN
LIU WEIJIE
GONG CHEN
XU ZHENGYUAN

Assignees

中国科学技术大学

Dates

Publication Date: 20260508
Application Date: 20260129

Claims (10)

1. The underwater wireless optical communication signal detection method based on the multi-type detector array is characterized by comprising the following steps of: The method comprises the steps that 1, a receiving end receives optical signals by adopting M multi-type photoelectric detectors comprising a high-gain photoelectric detector and a low-gain photoelectric detector and converts the received optical signals into M paths of electric signals, N times of up-sampling is carried out on the M paths of electric signals in each symbol period to obtain corresponding sampling point vectors, weighting and combining are carried out on the sampling point vectors in each path through weighting factors to obtain a combined signal, different weighting factor combinations are traversed, and corresponding projection vectors, decision threshold values and pilot frequency-based bit error rates are calculated for each group of weighting factors; and 2, determining an optimal weighting factor from the traversing result by taking the minimized bit error rate as a criterion, obtaining an optimal projection vector and an optimal judgment threshold value under the optimal weighting factor, carrying out inner product projection on a sampling point vector corresponding to the data symbol and the optimal projection vector, and recovering a 0 symbol sequence and a1 symbol sequence by comparing the sampling point vector and the optimal projection vector with the optimal judgment threshold value.
2. The method of claim 1, wherein the weighting factors satisfy the constraint that each component is non-negative and its sum is 1.
3. The method for detecting underwater wireless optical communication signals based on multi-type detector arrays according to claim 1, wherein the projection vector is calculated based on covariance matrix and mean value of weighted sampling point vectors corresponding to symbol 0 and symbol 1, and specifically, the projection vector is calculated by adopting a maximum ratio combining method.
4. The method of claim 1, wherein the decision threshold is determined by finding the intersection of probability distribution functions of the projected signals corresponding to pilot symbol 0 and symbol 1.
5. The method for detecting an underwater wireless optical communication signal based on a multi-type detector array according to claim 1, wherein the bit error rate is calculated by a decision result of a pilot sequence, specifically, a ratio of a correctly recovered pilot bit number to a total pilot bit number.
6. The method for detecting underwater wireless optical communication signals based on multi-type detector arrays according to claim 1, wherein the optimal weighting factors are obtained by solving a minimum bit error rate optimization problem.
7. The method for detecting underwater wireless optical communication signals based on multi-type detector arrays according to claim 1, wherein the recovery of the data symbols is achieved by performing inner product of the sampling point vector corresponding to the data symbols and the optimal projection vector and comparing with an optimal decision threshold.
8. The method for detecting underwater wireless optical communication signals based on multi-type detector arrays according to claim 1, wherein the M multi-type photodetectors are composed of at least one high-gain photodetector and at least one low-gain photodetector.
9. An electronic device, comprising: One or more processors; a memory for storing one or more programs; Wherein the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the multi-type detector array-based underwater wireless optical communication signal detection method of any of claims 1-8.
10. A computer readable storage medium having stored thereon executable instructions which when executed by a processor enable the processor to implement the method of detecting a multi-type detector array based underwater wireless optical communication signal as claimed in any of claims 1-8.

Description

Underwater wireless optical communication signal detection method based on multi-type detector array Technical Field The invention belongs to the technical field of underwater wireless optical communication and signal detection, and particularly relates to an underwater wireless optical communication signal detection method based on a multi-type detector array. Background With the increasing frequency of activities such as ocean resource development and environmental monitoring, the underwater wireless communication technology is receiving a great deal of attention. At present, three modes of acoustic communication, radio frequency communication and wireless optical communication are mainly adopted for underwater wireless communication. The underwater wireless optical communication (UOWC) has important potential in medium-short distance high-speed transmission by virtue of the advantages of large bandwidth, low delay, strong anti-interference capability and the like. Researches prove that the attenuation of the optical signal in water is relatively small in a blue-green light window of 450nm to 550nm, and a physical foundation is laid for UOWC. However, the underwater optical channel environment is complex and dynamically varies drastically. On one hand, the absorption and scattering of light by a water body lead to rapid attenuation of signals along with the transmission distance, especially in long-distance communication, the received light power is always at an extremely weak level, and on the other hand, the uneven temperature and salinity distribution caused by the seawater flow can cause refractive index fluctuation, generate optical turbulence and further disturb the stable transmission of the light signals. This large dynamic, highly attenuated channel characteristic presents significant challenges to the receiver-side detector performance and signal detection methods. Currently, underwater UOWC systems often employ photomultiplier tubes (PMTs) as the receiving device, and most systems employ a single type of PMT to construct an array receiver, such as an all high gain PMT array or an all low gain PMT array. High gain PMTs are sensitive to weak light, but are prone to saturation under strong light, while low gain PMTs are not prone to saturation, but are not sufficiently sensitive to weak light. The single type of array is difficult to consider the light intensity change in a large dynamic range, and the applicability of the system in an actual underwater environment is limited. In addition, the existing signal detection method is mostly based on likelihood ratio detection or sampling point superposition detection of fixed distribution assumptions (such as Gaussian distribution or Poisson distribution), and is difficult to adapt to dynamic change of light intensity of an underwater channel, so that detection performance is reduced, and system reliability is insufficient. Therefore, a signal detection method which can adapt to the underwater large dynamic light intensity environment, integrate the advantages of multiple types of detectors and has lower complexity is needed, so that the overall performance and reliability of the underwater wireless optical communication system are improved. Disclosure of Invention In order to solve the technical problems, the invention provides the underwater wireless optical communication signal detection method based on the multi-type detector array, the detection scheme is simple in form, low in complexity, suitable for underwater large dynamic light intensity scenes, capable of improving the signal detection performance of an underwater wireless optical communication system and improving the reliability of the underwater wireless optical communication system. In order to achieve the above purpose, the invention adopts the following technical scheme: An underwater wireless optical communication signal detection method based on a multi-type detector array comprises the following steps: The method comprises the steps that 1, a receiving end receives optical signals by adopting M multi-type photoelectric detectors comprising a high-gain photoelectric detector and a low-gain photoelectric detector and converts the received optical signals into M paths of electric signals, N times of up-sampling is carried out on the M paths of electric signals in each symbol period to obtain corresponding sampling point vectors, weighting and combining are carried out on the sampling point vectors in each path through weighting factors to obtain a combined signal, different weighting factor combinations are traversed, and corresponding projection vectors, decision threshold values and pilot frequency-based bit error rates are calculated for each group of weighting factors; and 2, determining an optimal weighting factor from the traversing result by taking the minimized bit error rate as a criterion, obtaining an optimal projection vector and an optimal judgment threshold value under th