Orthogonal Frequency Division Multiplexing (OFDM) is a special case of multicarrier transmission where the non-frequency-selective narrowband subchannels, into which the frequency-selective wideband channel is divided. A high-rate data stream typically faces the problem of having a symbol period Ts much smaller than the channel delay spread Td if it is transmitted serially. This generates Inter-Symbol Interference (ISI) which can only be undone by means of a complex equalization procedure. Orthogonal Frequency Division Multiple Access (OFDMA) is an extension of OFDM to the implementation of a multiuser communication system. This chapter assumes that a single user receives data on all the subcarriers at any given time. OFDMA distributes subcarriers to different users at the same time, so that multiple users can be scheduled to receive data simultaneously. The chapter highlight certain key parameters determine the performance of OFDM and OFDMA systems.
Orthogonal frequency division multiple access (OFDMA)
Book chapter N°5 in "LTE, The UMTS Long Term Evolution : From theory to practice", 2nd ed., Wiley, July 2011, Sesia, Stefania;Toufik, Issam; Baker, Matthew (Ed.), ISBN: 9780470660256
© Wiley. Personal use of this material is permitted. The definitive version of this paper was published in Book chapter N°5 in "LTE, The UMTS Long Term Evolution : From theory to practice", 2nd ed., Wiley, July 2011, Sesia, Stefania;Toufik, Issam; Baker, Matthew (Ed.), ISBN: 9780470660256 and is available at : http://dx.doi.org/10.1002/9780470978504.ch5
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