BIT INTERLEAVED LDPC CODED MODULATION AND PHYSICAL LAYER SIGNALING

摘要

A proposal for a DVB-C2 baseline system, mainly focused on the channel coding and bit interleaving modules for spectrally efficient modulation is described. Due to the implementation simplicity of the low density parity check (LDPC) codes standardized in the DVB-S2 specification, it is proposed to extend their application to cable channels and choose the subset with long block length ( L = 64800 ) and medium to high rates ( 2/5 ≤ R ≤ 9/10 ) as the forward error correction (FEC) codes of DVB-C2 systems. Due to the non-uniform bitwise error protection inherent to high-order modulations (e.g. 256-QAM, 1024-QAM) and irregular LDPC codes (e.g. DVB-S2 codes), there exists a mismatch between the modulation and the channel coding in general if the two modules are developed independently but concatenated directly. To match the error resilience of a finite-length channel code and a given constellation, the principles described herein design a bit interleaver and insert it between the channel encoder and the modulator. As a result, a better tradeoff between bandwidth-efficiency and power-efficiency can be achieved with a minor increase of hardware complexity.