EESM-Based Link Adaptation in Point-to-Point and Multi-Cell OFDM Systems: Modeling and Analysis

• Published in: IEEE transactions on wireless communications Vol. 13; no. 1; pp. 407 - 417
• Main Authors: Francis, Jobin, Mehta, Neelesh B.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-01-2014; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Accuracy; Adaptation models; adaptive modulation and coding; Applied sciences; Approximation methods; beta distribution; cell throughput; co-channel interference; Coding; Coding, codes; Exact sciences and technology; exponential effective SNR mapping (EESM); Information, signal and communications theory; Modulation, demodulation; Multiplexing; OFDM; Orthogonal frequency division multiplexing (OFDM); Random variables; scheduling; Signal and communications theory; Signal to noise ratio; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Throughput; Transmission and modulation (techniques and equipments); Vectors; Wireless networks; Wireless telecommunication; Diversity; Information rate; co-channel interference; Mapping; Subcarrier; Modeling; adaptive modulation and coding; Wide band; scheduling; System analysis; Adaptive modulation; Random variable; Modulation coding; Antenna; High rate transmission; Fading; Beta distribution; Information transmission; Adaptive coding; Orthogonal frequency division multiplexing (OFDM); exponential effective SNR mapping (EESM); cell throughput; Statistical model; Orthogonal frequency division multiplexing; Long distance transmission; Radio communication; Signal to noise ratio
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2013.112613.130716

In contemporary wideband orthogonal frequency division multiplexing (OFDM) systems, such as Long Term Evolution (LTE) and WiMAX, different subcarriers over which a codeword is transmitted may experience different signal-to-noise-ratios (SNRs). Thus, adaptive modulation and coding (AMC) in these systems is driven by a vector of subcarrier SNRs experienced by the codeword, and is more involved. Exponential effective SNR mapping (EESM) simplifies the problem by mapping this vector into a single equivalent flat-fading SNR. Analysis of AMC using EESM is challenging owing to its non-linear nature and its dependence on the modulation and coding scheme. We first propose a novel statistical model for the EESM, which is based on the Beta distribution. It is motivated by the central limit approximation for random variables with a finite support. It is simpler and as accurate as the more involved ad hoc models proposed earlier. Using it, we develop novel expressions for the throughput of a point-to-point OFDM link with multi-antenna diversity that uses EESM for AMC. We then analyze a general, multi-cell OFDM deployment with co-channel interference for various frequency-domain schedulers. Extensive results based on LTE and WiMAX are presented to verify the model and analysis, and gain new insights.