Principles of mobile communication (2nd ed.)
Principles of mobile communication (2nd ed.)
Information Theory and Reliable Communication
Information Theory and Reliable Communication
OFDM-Based Broadband Wireless Networks: Design and Optimization
OFDM-Based Broadband Wireless Networks: Design and Optimization
Ordered subcarrier selection algorithm for OFDM-based high-speed WLANs
IEEE Transactions on Wireless Communications
Low complexity adaptive power and subcarrier allocation for OFDMA
IEEE Transactions on Wireless Communications
Robustness maximization of parallel multichannel systems
Journal of Electrical and Computer Engineering - Special issue on Resource Allocation in Communications and Computing
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Whenever a communication system operates in a time-frequency dispersive radio channel, the link adaptation provides a benefit in terms of any system performance metric by employing time, frequency, and, in case of multiple users, multiuser diversities. With respect to an orthogonal frequency division multiplexing (OFDM) system, link adaptation includes bit, power, and subcarrier allocations. While the well-known water-filling principle provides the optimal solution for both margin-maximization and rate-maximization problems, implementation complexity often makes difficult its application in practical systems. This paper presents a few suboptimal (low-complexity) adaptive loading algorithms for both single- and multiuser OFDM systems. We show that the single-user system performance can be improved by suitable power loading and an algorithm based on the incomplete channel state information is derived. At the same time, the power loading in a multiuser system only slightly affects performance while the initial subcarrier allocation has a rather big impact. A number of subcarrier allocation algorithms are discussed and the best one is derived on the basis of the order statistics theory.