A Novel Mapped Network Coded Modulation Codec

Along with the rapid development of the modern communication technologies, multi-mode communication operations require a full range of diversity in signal transmission rate, bandwidth and information anti-interference capability, which poses a great challenge to both the transceiver devices and the receiver devices.The early communication system was established by separate channel coding and modulation. In 1976, Ungerboeck creatively proposed the TCM which combines convolution coding and modulation as a unity. TCM helps obtain extra gain with the same date rate, and greatly expand the application of digital communication system in power-limited channels. In recent decades, including last two years, researchers have been trying to improve its anti-interference capability and frequency efficiency through computer search, optimization and multidimensional expansion of constellation, asymmetrical coding, bit-interleaved and iterative decoding.This paper elaborates the basic principles of TCM coding and further proposes a brand-new code mapping scheme with examples of 8PSK and 16QAM, which modifies the traditional signal set partition and can improve the coding performance by 0.3dB without changing the bit rate and the computational complexity. Meanwhile, through software modeling and algorithm simulation, it compares the influences of different mapping on system error correction in Gaussian channel. Last but not least, with fundamental calculation unit reuse and timing control, it maps TCM to RTL circuit with FPGA verification and works out a general encoder and decoder design which applies to various bit rate and code mapping.