EFFICIENCY OF THE LDPC CODES IN THE REDUCTION OF PAPR IN COMPARISON TO TURBO CODES AND CONCATENATED TURBO-REED SOLOMON CODES IN A MIMO-OFDM SYSTEM

Abstract

Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems are the potential candidate for fourth generation (4G) mobile radio communication systems. The MIMO OFDM systems further provide an increase in the data throughput without an increase in the bandwidth and also provide a reduction in the fading. However, the main drawback of OFDM systems is the high peak to average power ratio (PAPR). This disadvantage can be reduced by a number of methods but most of them cause an increase in the bit error rate (BER), data rate loss and an increase in the computational complexity. Thus, the coding methods have been used to reduce the PAPR. LDPC codes were one of the first codes to allow data transmission rates close to the theoretical maximum, the Shannon limit. Although LDPC codes were discovered before turbo codes, the latter was significant in the early years. They have grown to become the standard in the market for highly efficient data transmission methods. These codes show improved performance over an AWGN channel. The Reed Solomon codes, when concatenated with Turbo codes also have been found to improve the performance over wireless channel. However, a comparison of these coding techniques – LDPC, turbo and concatenated turbo-Reed Solomon codes shows that LDPC is most efficient in the reduction of PAPR in a MIMO-OFDM system.