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We present a link adaptation strategy for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) based wireless communications. Our objective is to choose the optimal mode that will maximize energy efficiency or data throughput subject to a given quality of service (QoS) constraint. We formulate the link adaptation problem as a convex optimization problem and expand...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
We propose a novel distributed cross-layer optimization approach for cognitive radio wireless networks. A cognitive radio is a wireless device that is capable of sensing the prevailing environmental conditions and automatically adapting its operating parameters in order to enhance the performance of both the system and potentially the whole network. Given the lack of a centralized intelligence to...
As channel conditions in wireless communications improve, the noise performance of the baseband DSP processor can be degraded to save power without compromising bit error rate. The degradation of baseband signal noise is achieved by degrading the noise performance (reducing the wordlength and supply voltage) of the various baseband signal processing modules in specific proportions defined by a locus,...
Modern wireless transceiver systems are often overdesigned to meet the requirements of low bit error rate values at high data rates under worst-case channel operating conditions (interference, noise, multi-path effects). This results in circuits being designed with ldquosufficientrdquo margins leading to lower efficiency and high power consumption. In this paper, we develop an adaptive power management...
This paper investigates effects of pilot assisted channel estimation on dynamic resource allocation in a multiuser orthogonal frequency division multiplexing (OFDM) system. The channel estimation is done in each OFDM symbol through least-squared error (LSE) or minimum mean-squared error (MMSE) algorithm. The performance of each of these algorithms is evaluated through computer simulations. The maximal...
Correlative minimum shift keying (MSK), a second order polynomial modulation scheme known as tamed frequency modulation (TFM), is a constant envelope type of modulation with a perfect peak to average power ratio (PAPR), besides the property of low out of band power. We apply the linearized TFM to the single carrier transmission with frequency domain equalization (SC/FDE) concept. We then obtain a...
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