ABSTRACT
This chapter presents a brief description of orthogonal frequency division multiplexing (OFDM) transmission concept, summarizing its advantages and disadvantages. It discusses current and future deployment scenarios for OFDM, including the standardized 802.16j networks, as well as propositions for the next generation WWAN networks. The chapter describes the relay stations subcarrier permutation concept, including its possible impacts on the performance improvement of the OFDM based relay systems. The capacity of OFDM relay systems is higher than the capacity of single-carrier systems, due to data transmission on parallel orthogonal subcarriers. OFDM modulation and transmission technique has drawn considerable attention in the last decade and it has already become widely applied in new communication systems for high speed data transmission. The concept of OFDM technique, which has brought many benefits, is also characterized with some drawbacks. This is related to the sensitivity of OFDM systems to frequency offset and phase noise, as well as to high peak-to-average power ratio.
