Introduction to wireless multi-carrier schemes
(2012) Advances on processing for multiple carrier schemes OFDM and OFDMA — ISBN: [978-1-61470-634-2], p. 1-41, published
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- Multi-carrier schemes have long been known to be an efficient solution for dealing with frequency selective channels, and have become a key component for modern wireless communication systems. In fact, in order to achieve high data rates, current and future wireless systems are forced to operate on broad bandwidth, in which the channel typically features frequency selectivity. This chapter gives an introduction to multi-carrier systems, and pursues four main objectives. Firstly, the multipath propagation effect is described, and the equivalent discrete-time multi-tap channel is derived. Secondly, the concept of cyclic prefix is introduced, and from there the orthogonal frequency division multiplexing (OFDM) modulation is thoroughly derived. Thirdly, the main features of the OFDM modulation are analyzed and compared to its single-carrier counterpart, known as single-carrier with frequency domain equalization (SC-FDE). In fact, OFDM and SC-FDE share the nice property of the one-tap frequency domain equalization. However, on top of this, the OFDM modulation has the two following advantages: (i) high data rates can be achieved by adaptively allocating the resources among the subcarriers, (ii) OFDM intrinsically offers a multiple access in the frequency domain with fine granularity in the bandwidth allocation among users, known as orthogonal frequency division multiple access (OFDMA). Finally, an introduction to filter banks multi-carrier (FBMC) systems is given. At the expense of an increased complexity, it is shown how FBMC provides several advantages of robustness and flexibility with respect to OFDM, by replacing the discrete Fourier transform with a filter bank with better spectral selectivity.
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Devillers, B., & Louveaux, J. (2012). Introduction to wireless multi-carrier schemes. In Faouzi Bader; Nizar Zorba (ed.), Advances on processing for multiple carrier schemes OFDM and OFDMA (p. p. 1-41). Nova Science Publishers. https://hdl.handle.net/2078.5/159744