Control channel-free underwater dynamic spectrum access method

Abstract

The invention provides a control channel-free underwater dynamic spectrum access method. Due to the utilization of the characteristic that an underwater acoustic channel has a narrow available band and is easy to monitor in full band, a transmitter and a receiver exchange control information by a current idle channel, and a channel used in communication is determined by adopting a full-band monitoring method. In addition, signal detection and channel estimation are performed by utilizing a method for rapidly identifying a signal transmitted to a local node and performing channel estimation, and the effective transmission of the signal is ensured by utilizing a random repeat method. In the underwater dynamic spectrum access method provided by the invention, underwater spectrum resources can be dynamically used without setting a special control channel for communication negotiation, so the utilization rates of the underwater spectrum resources can be effectively increased, the channel accessing time of the transmitter and the receiver can be shortened, system failures caused by interference to the control channel can be avoided, and the communication rate, user number and robustness of an underwater acoustic communication system can be further remarkably improved.

Description

technical field [0001] The invention relates to the technical field of underwater acoustic communication, in particular to an underwater dynamic frequency spectrum access method without a control channel. Background technique [0002] The ocean covers 70% of the earth and has extremely rich resources. Today, when the utilization of land resources is becoming saturated, the exploration, development and utilization of sea resources have increasingly become one of the major strategies of various coastal countries. With the development of technology and the increase of human underwater activities, the demand for underwater acoustic communication technology has shifted from the early point-to-point underwater acoustic communication to multi-user and networked underwater acoustic communication. To build an underwater acoustic communication network, in addition to solving the communication problem between two point-to-point users, it is also necessary to realize the information int...

AI Technical Summary

Problems solved by technology

[0005] However, compared with terrestrial radio channels, underwater acoustic channels have the characteristics of narrow frequency band, large interference and noise, and time extension. In many cases, it is difficult to directly apply terrestrial cognitive radio technology to underwater communication systems. In terrestrial wireless communication, the sender and receiver of cognitive users usually need to exchange control information such as the selected channel through a common channel in the process of accessing the channel, but in underwater acoustic communication, setting up a common control channel will bring The following shortcomings: (1) Since the frequency band available in the underwater acoustic channel is much narrower than that of the land wireless channel, the use of a dedicated control channel will occupy limited spectrum resources, making the spectrum resources of the underwater acoustic channel more (2) In the underwater acoustic communication system, the signal attenuation largely depends on the communication frequency. Therefore, if the control channel is used in underwater communication, the frequency must be low enough to meet the requirements of the farthest link in the network. Reliable connection, while the transmission rate of low-frequency channels is low, and control information is prone to conflicts during transmission; (3) Since the delay of underwater acoustic channels is much higher than that of land wireless channels, when control information errors or conflicts occur during transmission , the time required for retransmission is very long, which reduces the efficiency of spectrum access; (4) The underwater acoustic channel is an extremely complex time-space-frequency variation, limited frequency band, long delay, strong multi-path interference and high noise channel, the fixedly set control channel is easily affected by various interferences and fails, thus affecting the normal operation of the entire system

In addition, since the time delay of the underwater acoustic channel is much longer than that of the land wireless channel, the information exchanged between the sending and receiving parties should be as little as possible when the underwater acoustic channel is connected, and it is not suitable to directly use the more complicated communication negotiation mechanism in the land wireless communication. In order to enable the communication parties to access the channel as soon as possible

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