Combined Unequal Error Protection and Optimized Scaling for IEEE 802.11n Low Density Parity Check Codes

Tulsi Pawan Fowdur, Madhavsingh Indoonundon


Low Density Parity Check codes are among the most successful forward error correction codes which are capable of providing near channel capacity
performance. However, several new schemes are still being developed to improve their performance and reduce their complexity. In this paper, the performances of the IEEE 802.11n Low Density Parity Check codes are evaluated by combining three techniques: Unequal Error Protection, Optimized Scaling Factor and Failed Check Node. Unequal Error Protection is employed by mapping systematic bits onto prioritized constellation
points in 16-QAM and 64-QAM constellations. Optimized Scaling Factor is performed by obtaining scaling factors for each Eb/N0 values which are then used in both the check node and bit node update steps in the
Min-Sum decoding algorithm. Finally, Failed Check Node is incorporated to select the best decoded sequence among the different sequences obtained at each iterations. Simulation results showed that maximum
gains of 0.9 dB and 1.35 dB could be achieved as compared to conventional Low Density Parity Check codes decoding with 16-QAM and 64-QAM respectively in the range BER≤10-2.

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