We consider a multitone multiple access wireless system where users are multiplexed by the assignment of sub-sets of the available tones. The information signals of distinct users are multicarrier modulated and propagate through asynchronous frequency selective fading channels, i.e., uplink. In this scenario inter-symbol, inter-carrier, and multiple access interference arise. We consider simple...

In recent years, we have witnessed a huge interest in the study of channel allocation and handoff strategies for cellu lar systems to ensure continuous services that guarantee QoS to mobile users. In this paper, we have a detailed d iscussion of different categories of wireless channel allocation schemes. The basic purpose of the study is to provide a comprehensive review of d ifferent categori...

In this paper, the resource allocation problem is considered for energy efficient spectrum access in a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and has limited battery energy. The network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the entire spectrum and locate the available subcarrier s...

This paper investigates the adaptive subcarrier and bit allocation algorithm for OFDMA systems. To minimize overall transmitted power, we propose a novel adaptive subcarrier and bit allocation algorithm based on channel state information (CSI) and quality state information (QSI). A suboptimal approach that separately performs subcarrier allocation and bit loading is proposed. It is shown that a...

Over the last decade, the scope of cellular networks has been shifted from low bit rate voice delivery to high bit rate multimedia services. Consequently, cellular systems have evolved from the circuit switched to the packet oriented system architecture, and an integration with the Internet has taken place. The perpetual need for higher data rates in such systems has caused the development of e...

In the present study, we analyze the multi-channel service system with ordered entryfrom finite-source and finite-storage at each channel. The arrival and service rates are assumedto be state dependent. The steady state probabilities of the system are obtained by usingChapmann-Kolmogorov equations. Some other performance indices viz. utilization of servers,expected number of units in the system...

In this work, we introduce the idea of adaptive sub-channel allocation based unequal error protection (ASCA-UEP) to a space-time block coded orthogonal frequency division multiplexing (STBC-OFDM) system. In such a system, UEP is realized by adaptively allocating and transmitting high-priority and low-priority video data over high-quality and low-quality sub-channels, respectively. Further, we p...

This paper will focus on improving the performance of orthogonal frequency division multiplexing (OFDM) in Rayleigh fading environments. The proposed technique will use a previously published method that has been shown to improve OFDM performance in independent fading, based on ordered sub-carrier selection. Then, a simple non-iterative method for finding the optimal bit-loading allocation was ...

In mobile millimeter wave (mmWave) systems, energy is a scarce resource due to the large losses in the channel and high energy usage by analog-to-digital converters (ADC), which scales with bandwidth. In this paper, we consider a communication architecture that integrates the sub-6 GHz and mmWave technologies in 5G cellular systems. In order to mitigate the energy scarcity in mmWave systems, we...