Journal of Engineering Science and Technology (Jun 2015)
A MODIFIED UNEQUAL POWER ALLOCATION (UPA) SCHEME FOR PERFORMANCE ENHANCEMENT IN BIT REPETITION TURBO CODES IN HIGH SPEED DOWNLINK PACKET ACCESS (HSDPA) SYSTEM
Abstract
In this paper, a modified optimal power allocation scheme for different bits in turbo encoder has been proposed to improve the performance of Turbo Codes system in High Speed Downlink Packet Access (HSDPA) service. In a typical turbo code in HSDPA system, an encoder with code rate of 1/3 was used with bit repetition scheme or puncturing system to achieve code rate of 1/4. In this study, the author has proposed a modified unequal power allocation (UPA) scheme to improve the performance of Turbo Codes in HSDPA system. The simulation and performance bound results for the proposed UPA scheme for the frame length of N = 400, code rate = 1/4 with Log-MAP decoder over Additive White Gaussian Noise (AWGN) channel were obtained and compared with the typical Turbo Codes systems, which used bit repetition scheme and puncturing method without UPA. From the results, the proposed bit repetition turbo codes system with modified UPA scheme showed better performance than the typical turbo codes system without UPA using bit repetition and puncturing approaches with coding gain of 0.35 dB to 0.56 dB.
