Non-Coherent Multi-Symbol Detection of PR-CPM for Deep Space Relay Satellites with Physical-Layer Network Coding

The demand for wireless spectrum and data transmission has increased dramatically with the rapid growth of deep-space exploration and communication. The satellite relay communication is an essential technique to solve the issues above. The method of combining Physical-layer Network Coding (PNC) with Continuous Phase Modulation (CPM) on relay satellites can improve communication efficiency and perform the collection and transmission of space data effectively. Partial-Response CPM (PR-CPM) signals possess excellent spectrum and power characteristics and are suitable for deep-space communications with limited bandwidth and massive data transmission. In this paper, a partial response non-coherent multi-symbol detection algorithm is proposed based on the Maximum-Likelihood principle. The proposed algorithm fully utilizes the memory properties of PR-CPM signals and makes decisions on specified symbols by observing a number of symbols each time. Simulation results indicate that the performance gain under the Bit Error Rate of 10(-4) is about 2 dB when 5 symbols are inspected, compared with the case where the observation length is 3.