The problem of noise amplification in the multichannel blind separation of communication signals is researched. A new algorithm and its improved algorithm to seek the separation matrix is proposed based on the idea of maximizing the signal-to-interference-plus-noise power ratio (SINR). When the condition number of the separation matrix is large, the separation matrix sought by this algorithm and its improved algorithm can beautifully solve the problem of separation performance degradation caused by noise amplification. Simulation results show that this algorithm and its improved algorithm can reduce the bit error rate effectively and improve the performance of blind separation, exhibiting practical application value.

Research on the blind separation algorithm and its improved algorithm based on maximizing the SINR

The AIS communication system is a global positioning aided navigation system, which can improve the safety of ship operation and the reliability of navigation. A spaceborne AIS system can dynamically monitoring ships in the global area. But It has many challenges such as message collision and signal transmission loss. This paper first designed a LEO AIS constellation, analyzed the coverage of this constellation, and then carried out the design of the on board AIS receiving system, including an array antenna and a receiver. Finally, the method of multi-user signal separation and detection was expounded.

Design of Spaceborne AIS System

A synchronous demodulation algorithm based on energy operator for satellite-based AIS signals is proposed. Firstly, the baseband signal is obtained by differencing the intermediate frequency signal and estimating the envelope with energy operator. Bit synchronization and decision are achieved by applying the maximum measurement method which selects the best set of samples with the maximum energy. Simulation results show that when the SNR is low or there are interfering signals, the BER of the proposed method is obviously lower than non-coherent ones. The proposed method maintains almost the same efficiency as the incoherent demodulation and is significant for practical application.

Shouzhong Zhu

Papers

Synchronous demodulation algorithm based on energy operator for satellite-based AIS signals