High robust broadcasting over DTMB-A with low-rate LDPC codes

As the 2nd generation digital terrestrial television broadcasting (DTTB) standard, digital terrestrial/television multimedia broadcasting — advanced (DTMB-A) can provide higher spectrum efficiency and transmission reliability by adopting flexible frame structure and advanced forward error correction coding compared with the 1st generation DTTB systems. In order to increase the flexibility and robustness of the DTTB network, the frequency reuse scheme of factor one (reuse-1) is proposed, where the same RF channel is used by different stations covering the adjacent service areas. However, it demands a very low carrier-to-noise ratio (C/N) threshold below 0dB at the DTTB physical layer. In this paper, a robust broadcasting technique is proposed based on DTMB-A with newly designed low-rate low density parity check (LDPC) codes. By adopting quasi-cyclic (QC) Raptor-like structure and progressive lifting method, the high performance low-rate LDPC codes are designed supporting multiple code lengths. Both density-evolution analyses and laboratory measurements demonstrate that DTMB-A with low-rate coding can complete the demodulation reliably with the C/N threshold below 0dB, which is one important necessary condition to support frequency reuse-1 scheme.