Research On Technology Of Joint Coding And Modulation

Reliability and efficiency are two’main factors of digital communication system. However, in digital communication system, they are often a contradiction. In the era with an increasing scarcity of band resource, how to guarantee the reliability and improve the efficiency of communication system is the hot spot in the communication field.In the optical communication system, we often use differential modulation (DQPSK) to overcome the problem of phase ambiguity at receiver. However, the differential modulation may make bit error rate doubled and generate additional SNR cost. This paper analyzes the scheme of iterative differential demodulation and decoding, which takes LDPC codes and differential modulation as a whole to be optimized. Simulation results show that the scheme not only can overcome the phase ambiguity but also compensate the differential cost, which greatly enhances the reliability of communication system. Meanwhile, this paper analyzes the degree optimization algorithm of LDPC codes for the scheme and the check matrix construction method that meets any degree distribution.In the wireless communication system, the fading characteristics of wireless channel cause a serious impact on the efficiency and reliability of communication system. Diversity technology is a typical anti-fading technology.This paper investigates the joint coding and modulation diversity technology.Two key factors of the technology: multi-dimensional rotation modulation and component interleaver are mainly discussed to make use of channel coding gain with time,frequency, space and modulation diversity. This technology both can achieve high spectral efficiency and effectively resist a variety of interferences under fading channel, and enhance the efficiency and reliability of communication system, especially suitable for future mobile communication system.For its application in communication system, we study the technology in MIMO system and MIMO-OFDM system for wireless local network with 802.11ac standards. Simulation results show that this technology could obtain about 2-7dB gain compared to traditional code and modulation technology. It is believed that the technology has broad application prospects...