A Dual Mode Uplink and Downlink Scheme for WiMAX

Multipath delay spread is a major transmission problem, which affects the design of modulation and equalization. Anti-multipath alternative approaches are orthogonal frequency division multiplexing (OFDM), single carrier modulation, with receiver decision feedback equalization (DFE) in time as well as frequency domain. The purpose of this paper is to introduce the benefits and the implications of having a mixed mode of OFDM downlink and single carrier with frequency domain equalization (SC-FDE) Uplink. The higher frequency diversity exploitation of SC-FDE allows it to outperform OFDM in most cases especially in the uplink communications where lower PAPR greatly benefits the mobile terminal in terms of transmit power efficiency.