Dynamic spectrum sharing has drawn intensive attention in cognitive radio networks. The secondary users are allowed to use the available spectrum to transmit data if the interference to the primary users is maintained at a low level. Cooperative transmission for secondary users can reduce the transmission power and thus improve the performance further. We study the joint subchannel pairing and ...

Random medium access control (MAC) plays a critical role in OFDMA wireless networks to support services with bursty traffic. However, the existing OFDMA random access protocols suffer from low efficiency due to the constraints in half-duplex communications. In this paper, the capability of full-duplex communications is leveraged to propose novel mechanisms such as full duplex carrier sensing, c...

MC-CDMA systems transmit data over several orthogonal subcarriers. The capacity of MC-CDMA cellular system is mainly limited [I081 by the mutual interference generated by the mobile stations and the fading radio channel. A reduction in interference will obviously increase the system capacity. Interference is caused predominantly by the effects of near-far problem, co-channel interference and fa...

In this paper, a reduced complexity algorithm is proposed for grouped-subcarriers and power allocation in the downlink of OFDMA packet access wireless systems. The available subcarriers for data communication are grouped into partitions (groups) where each group is defined as a subchannel. The scheduler located at the base station allocates subchannels to users based on the variance of subchann...

We propose an adaptive modulation scheme for wireless MIMO systems. The main goal of this scheme is to maximize the bit rate for a fixed target BER. The MIMO channel is split up into several independent channels (subspaces) by a singular value decomposition. On each of these independent channels the modulation format is adapted to the subchannel SNR. The proposed algorithm allocates appropriate...

This paper is concerned with a wireless system operating in MIMO fading channels with channel state information being known at both transmitter and receiver. By spatiotemporal subchannel selection and power control, it aims to minimize the average transmit power (ATP) of the MIMO system while achieving an exponential type of average bit error rate (BER) for each data stream. Under the constrain...

A distributed wireless network with K links is considered, where the links are partitioned into M clusters each operating in a subchannel with bandwidth W/M. The subchannels are assumed to be orthogonal to each other. A general shadow-fading model described by the probability of shadowing α and the average cross-link gains ≤ 1 is considered. The main goal is to find the maximum network throughp...