Energy-Efficient Resource Allotment for OFDM-Based Cognitive Radio Networks

Orthogonal frequency-division multiplexing (OFDM), is a frequency-division multiplexing (FDM) scheme used as a digital multi-carrier modulation method. Recently, some schemes have proposed to reduce the number of DFT blocks required. OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for vast carriers with high peak rates. Ultra-wideband characteristics are well-suited to short-distance applications, such as PC peripherals. Adaptive resource allocation (RA) for the OFDM systems has been studied extensively for more than a decade. A survey can be found in and references therein. For the arising OFDM-based CR, a system, adaptive RA has also attracted much attention starting from the surfacing of the CR and with the references therein provides a comprehensive survey. For single SU case, RA in an OFDM-based CR system degenerates into power distribution. Due to low emission levels permitted by regulatory agencies, UWB systems tend to be shortrange indoor applications. We studied the energyefficient resource allocation in an OFDM-based CR network, which is an urgent task for green communication design