ABSTRACT
Future broadband wireless networks should meet stringent requirements such as high data rate services over the dispersive channel with high transmission reliability. Since the wireless resources such as the bandwidth and power are very scarce, they cannot cope with the increasing demand for higher data rates. Furthermore, the wireless channel suffers from many impairments such as fading, shadowing, and multiuser interference that may degrade the system performance. In order to achieve such high bit rates and at the same time meet the quality of service (QoS) requirements, orthogonal frequency division multiple access (OFDMA) is considered as a mature technique to mitigate the problem of frequency selectivity and ISI among other well-known advantages [137,138]. However, OFDMA, as a multicarrier technique, suffers from two main drawbacks. One is the high peak-to-average power ratio (PAPR) which is a critical problem especially in the uplink direction. It is required for the mobile terminal to be of low cost and high power efficiency which is difficult to achieve with the earlier constraints. In addition, OFDMA suffers from CFOs. Alternatively, SC-FDMA is a promising solution which is adopted as an uplink multiple access scheme in 3GPP-LTE [14,139,140]. Due to its single-carrier nature, it has a lower PAPR while keeping most of the advantages of OFDMA such as assigning different numbers of subcarriers to different users and applying adaptive modulation and coding.
