Design of Joint Sparse Graph for OFDM System

作者：Wen Lei^*; Razavi Razieh; Imran Muhammad Ali; Xiao Pei

来源：IEEE Transactions on Wireless Communications, 2015, 14(4): 1823-1836.

DOI：10.1109/TWC.2014.2373379

• Multi access communication
• joint sparse graph
• joint multiuser detection and FEC decoding
• code division multiple access
• multiuser channels.

Low density signature orthogonal frequency division multiplexing (LDS-OFDM) and low density parity-check (LDPC) codes are multiple access and forward error correction (FEC) techniques, respectively. Both of them can be expressed by a bipartite graph. In this paper, we construct a joint sparse graph combining the single graphs of LDS-OFDM and LDPC codes, namely joint sparse graph for OFDM (JSG-OFDM). Based on the graph model, a low complexity approach for joint multiuser detection and FEC decoding (JMUDD) is presented. The iterative structure of JSG-OFDM receiver is illustrated and its extrinsic information transfer (EXIT) chart is researched. Furthermore, design guidelines for the joint sparse graph are derived through the EXIT chart analysis. By offline optimization of the joint sparse graph, numerical results show that the JSG-OFDM brings about 1.5-1.8 dB performance improvement at bit error rate (BER) of 10(-5) over similar well-known systems such as group-orthogonal multi-carrier code division multiple access (GO-MC-CDMA), LDS-OFDM, and turbo structured LDS-OFDM.

• 出版日期2015-4