Comparison between Turbo Code and Convolutional Product Code (CPC) for Mobile WiMAX

Comparison between Turbo Code and Convolutional Product Code (CPC) for Mobile WiMAX

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Abstract— Mobile WiMAX is a broadband wireless solution that enables convergence of mobile and fixed broadband networks through a common wide area broadband radio access technology and flexible network architecture. It adopts Orthogonal Frequency Division Multiple Access (OFDMA) for improved multi-path performance in Non-Line-Of-Sight (NLOS) environments. Scalable OFDMA (SOFDMA) is introduced in the IEEE 802e[1]. WIMAX system uses one of different types of channel coding but The mandatory channel coding scheme is based on binary nonrecursive Convolutional Coding (CC). There are other several optional channel coding schemes such as block turbo codes, convolutional turbo codes, and low density parity check (LDPC). In this paper a comparison between the performance of WIMAX using turbo code and using convolutional product code (CPC) [2] is made. Also a combination between them had been done. The CPC gives good results at different SNR values compared to both the turbo system, and the combination between them. For example, at BER equal to 10-2 for 128 subcarriers, the amount of improvement in SNR equals approximately 3 dB higher than turbo code and equals approximately 2dB higher than the combination respectively. Several results are obtained at different modulating schemes (16QAM and 64QAM) and different numbers of sub-carriers (128 and 512). Keywords— Turbo Code, Convolutional Product Code (CPC), Convolutional Product Code (CPC). I. INTRODUCTION IMAX [3] is a new wireless technology that provides high throughput broadband connection over long distances based on IEEE.802.16 wireless MAN air interface standard. It is designed to accommodate both fixed and mobile broadband applications. It can be used for many applications, including "last mile" broadband connections, hotspots and cellular backhaul, and high-speed enterprise connectivity for business, due to its high spectrum efficiency and robustness in multi path propagation. Comparing WIMAX to Wi-Fi and 3G, the wimax has an improved important characteristic, the throughput capabilities of wimax depends on the channel bandwidth used [4]. Unlike the 3G systems which have fixed channel bandwidth, WIMAX defines a selectable channel bandwidth from 1.25MHz to 20MHz. In WIMAX systems, there are many researches had been made for the different stages such as coding stage [5-9]. Our investigations are focused on studying the performance of wimax using convolutional product code (CPC) compared to turbo code.In the CPC coding method, a stream of bits, forming the message, is converted into a matrix (nxm). First each row will be coded by recursive systematic convolutional encoder. After interleaver, each column will be coded by another recursive systematic convolutional encoder. The same or different generator polynomials are used to code both rows and columns. CPC will be described in more details in section III. In this paper, CPC method is studied for improving BER at
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This note was uploaded on 01/25/2011 for the course SCE 5441 taught by Professor Lung during the Spring '10 term at Carleton CA.

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Comparison between Turbo Code and Convolutional Product Code (CPC) for Mobile WiMAX

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