A Hybrid Statistical and Prioritised Unequal Error Protection Scheme for IEEE 802.11n LDPC Codes

The combination of powerful error correcting codes such as (LDPC) codes and Quadrature Amplitude Modulation (QAM) has been widely deployed in wireless communication standards such as the IEEE 802.11n and DVB-T2. Recently, several Unequal Error Protection schemes which exploit non-uniform degree distribution of bit nodes in irregular LDPC codes have been proposed. In parallel, schemes that exploit the inherent UEP characteristics of the QAM constellation have also been developed. In this paper, a hybrid UEP scheme is proposed for LDPC codes with QAM. The scheme uses statistical distribution of source symbols to map the systematic bits of the LDPC encoded symbols to the QAM constellation. Essentially, systematic symbols having highest probabilities of occurrence are mapped onto the low power region of the QAM constellation and those with a low probability of occurrence are mapped onto the high power region. The decrease in overall transmission power allows for an increased spacing between the QAM constellation points. Additionally, the scheme uses the distribution of the bit node degree of the LDPC code-word to map the parity bits having the highest degree onto prioritised QAM constellation points. Simulations with the IEEE 802.11n LDPC codes revealed that the proposed scheme can provide gains of up to 0.91 dB in Eb/No compared with other UEP schemes for a range of Bit Error Rate (BER) values

An unequal error protection scheme for non-binary LDPC using statistical QAM and prioritized mapping

Low Density Parity Check (LDPC) codes are among the most popular channel codes used nowadays because of their ability to achieve near channel capacity performances. However, with the ever-increasing demand for reliable transmission of data at higher data rates, there is a need to narrow down the gap between the performance of LDPC codes and the channel capacity. LDPC codes and Quadrature Amplitude Modulation (QAM) have been widely deployed in wireless communication standards such as the IEEE 802.11n and Digital Video Broadcasting-Second Generation Terrestrial (DVB-T2). Recently, several Unequal Error Protection (UEP) schemes have been used to enhance the performance of LDPC codes. In this paper an UEP scheme is proposed for Non- Binary LDPC codes with QAM. The scheme uses the statistical distribution of the source symbols to obtain a more efficient statistical QAM constellation. Additionally, it uses the degree distribution of the nodes of the LDPC codeword to achieve prioritized QAM mapping. Simulations revealed that the proposed scheme can provide Eb/N0 gains of up to 0.78 dB and 1.24 dB with 16-QAM and 64-QAM respectively in the range BER≤10-2