Efficient Two-Stage Discrete Bit-Loading Algorithms for OFDM Systems

• Published in: IEEE transactions on vehicular technology Vol. 59; no. 7; pp. 3407 - 3416
• Main Authors: Wang, Deqiang, Cao, Yewen, Zheng, Laibo
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.09.2010; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithm design and analysis; Algorithms; Allocations; Applied sciences; Bandwidth; Bit error rate; Bit loading; Complexity; Computation; Computational complexity; Constellations; Constraint optimization; Exact sciences and technology; Fading; Frequency division multiplexing; Information, signal and communications theory; Mathematical analysis; Mobile communication; multicarrier communications; Multiplexing; OFDM modulation; Optimization; Orthogonal Frequency Division Multiplexing; orthogonal frequency-division multiplexing (OFDM); Permission; Signal and communications theory; Studies; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Teletraffic; Transmission and modulation (techniques and equipments); Performance evaluation; Multistage method; Optimal algorithm; Bit error rate; Flow rate regulation; Multicarrier; Bit loading; Information rate; Teletraffic; Subcarrier; Computational complexity; Information transmission; Bit allocation; multicarrier communications; Algorithm performance; Optimal allocation; Traffic management; Analytical method; Orthogonal frequency division multiplexing; Traffic control; Numerical simulation; Multistage circuit; orthogonal frequency-division multiplexing (OFDM)
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2010.2052937

Aiming at minimizing the transmit power of orthogonal frequency-division multiplexing (OFDM) systems subject to the target data rate, the target bit error rate (BER), the maximum allowable power per subcarrier, and the maximum allowable size of constellations, we present a couple of new discrete bit-loading algorithms, named efficient bit filling (EBF) and efficient bit removal (EBR), which are based on our new idea of group-by-group bit filling. Both EBF and EBR perform bit loading in two stages and are able to converge to the optimal bit-allocation profile. In the first stage, an intermediate bit-allocation profile, which is tightly close to the final bit-allocation profile, is obtained by using our proposed group-by-group bit filling (for EBF) or group-by-group bit removal (for EBR). In the second stage, the well-known greedy bit filling (for EBF) or greedy bit removal (for EBR) is performed for the remaining bits (usually of a small size). Analytical and numerical results reveal that the proposed algorithms converge to the optimal bit allocation with much lower computational complexities than existing optimal algorithms. It is also shown that the proposed algorithms outperform typical suboptimal algorithms in power efficiency with relatively higher computational complexities.