Novel technique for scaling down LDPC code lengths in DVB-T2 standard

The paper proposes an approach to scale-down the LDPC code length, thus saving memory and processing power, without significantly sacrificing the code robustness. the paper describes how to use specific Low Density Parity Check (LDPC) codes for Digital Video Broadcasting Terrestrial Second Generation DVB-T2. While the original LDPC codes are rather long 16200 bits and 64800 bits, we propose to reduce their size (about 3k instead of 16k). To reduce the encoder/decoder complexity, the scaled down LDPC codes based on DVB-T2 of length 16200 are proposed in this paper. Scaling the codes may lead to the problems of girth-4 and low weight codes. This paper analyzed the possible reasons leading to the problems, and proposed the optimum scaled down LDPC codes of DVB-T2 that avoid girth-4 and low weight codes. The simulation results in the AWGN channel show that for code rate ½ at BER = 10^-5, LDPC DVB-T2_3240 requires only additional 0.5dB above that required by DVB-T2_16200 and the proposed scaled down code by 5 still has no error floor as well as the former codes in [10]. The impact of the paper is not restricted to DVB-T2 systems, but also to DVB-S2 and all future technologies which are to adopt LDPC.