Analysis of adaptive modulation and coding schemes in DVB-T2 broadcasting systems to improve signal stability, transmission efficiency and overall quality of service

Abstract

The performance of adaptive modulation and coding in second-generation digital broadcasting systems (DVB-T2) is investigated in terms of the reliability of the transmitted signal, the efficiency of channel bandwidth utilization, and the quality of the supported service. The performance of quadrature phase-shift keying (QPSK) modulation schemes (16QAM, 64QAM, 256QAM) using low-density parity-check (LDPC) codes with rates of 1/2–9/10 is assessed in the context of their application to provide high-quality digital terrestrial television broad casting based on adaptive modulation and coding methods. The simulation results yielded bit error cha racteristics for various modulation schemes using LDPC codes at different rates in channels with additive white Gaussian noise and multipath fading simultaneously. It was found that simpler modulation schemes, such as 1/2 rate QPSK, can provide a bit error rate of less than 10–5 at a signal-to-noise ratio of 5 dB, while more complex ones, such as 9/10 rate 256QAM, require a signal-to-noise ratio of 25 dB to provide a bit error rate of less than 10–6. An imp rovement in channel throughput was noted from 1.0 bps/Hz for QPSK modulation to 6.7 bps/Hz for 256QAM under high signal-to-noise ratio conditions.