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This work proposes a three-dimensional (3D) reference model for multiple-input multiple-output (MIMO) base station to relay station (BS2RS) Rician fading channels. First, the new stochastic reference model, based on the geometrical one-sphere model, is obtained under the assumption that both base station and relay station are stationary while an infinite number of local scatterers around the RS move...
Joint channel-aware and buffer-aware scheduling along with rate/power adaptation is a promising solution to assure Quality of Service (QoS) and improve energy efficiency. In this paper, an analytical delay-power tradeoff and optimal threshold-based scheduling are proposed. In particular, we are interested in the scheduling policies where the scheduler only needs to decide transmitting or not. More...
This paper advocates the use of the emerging distributed compressive sensing (DCS) paradigm in order to deploy energy harvesting (EH) wireless sensor networks (WSN) with practical network lifetime and data gathering rates that are substantially higher than the state-of-the-art. In particular, we argue that there are two fundamental mechanisms in an EH WSN: i) the energy diversity associated with the...
As the energy consumption in information and communication (ICT) systems becomes a more and more important problem, the ICT systems have been being equipped with energy harvesting devices and redesigned from the perspective of energy efficiency. In this paper, a point-to-point communication system with energy harvesting transmitter will be considered in the Rayleigh block-fading channel. In contrast...
DF-AF selection MIMO relaying, where the relay equipped with multiple antennas can adaptively switch between decode-and-forward (DF) protocol and amplify-and-forward (AF) protocol according to its decoding state of the source message, is investigated in cooperative networks. We consider orthogonal space-time block coded transmission for a DF-AF selection MIMO relaying system in Rayleigh fading environment,...
An opportunistic DF-AF selection relaying scheme with maximal received signal-to-noise ratio (SNR) at the destination is investigated in this paper. The outage probability of the opportunistic DF-AF selection relaying scheme over Nakagami-m fading channels is analyzed, and a closed-form solution is obtained. We perform asymptotic analysis of the outage probability in high SNR domain. The coding gain...
In this paper, we propose a new geometrical two-erose-ring scattering model for the multiple-input multiple-output (MIMO) mobile-to-mobile (M2M) fading channels. In this model, the line-of-sight (LOS) and non-line-of-sight (NLOS) components are all considered. Based on the geometrical model, a reference model and the corresponding simulation model are derived. Their statistical properties such as...
The conventional rateless coded cooperation (RCC) operates in full-duplex and non-orthogonal multiples access channel (MAC) aiming to enlarge outage capacity with multiplexed Raptor code of high complexity. In this paper, we develop a new RCC scheme using rateless code, which operates in the practical half-duplex or orthogonal channel aiming to achieves coding gain in high SNR region with only one...
Spectrum sensing is one of the major elements of cognitive radio applications. A single secondary user (SU) usually cannot provide robust sensing capability due to channel effects. In order to overcome this problem, cooperative spectrum sensing techniques have been proposed. Because conventional cooperative spectrum sensing schemes assumed that all sensing nodes have the same sensing reliability,...
Recent work has shown that distributed (or cooperative) beamforming can achieve cooperative gain, such as throughput gain and diversity gain, with no need for extra spectral holes in Cognitive Wireless Networks (CWNs). However, how to efficiently schedule cooperative beamforming to improve the quality of service of unlicensed secondary users has not been well addressed. In this paper, a simple opportunistic...
OFDM is playing a more and more important role in wireless communication systems. Unfortunately, it is not trivial to conduct a performance analysis of OFDM systems. Therefore, it is highly desired to develop an analytical design and performance analysis framework for OFDM channels. In this paper, we consider a unified performance metric for OFDM channels, which we shall refer to as outage exponent...
Rateless coding ensures reliability for time-varying channels by providing ever-increasing redundancy at the packet level. However, the optimal packet length for rateless codes has not been carefully studied from the application layer and the physical layer. In this paper, we present a practical wireless communication system consisting of an LT coding module, a channel coding module, and error detection...
The diversity-multiplexing tradeoff, which relates the transmission reliability and efficiency, is an important performance metric in wireless communications. So far only an asymptotic tradeoff result has been obtained for OFDM channels, and such result is only valid for high SNRs. To characterize the outage performance of OFDM systems in realistic SNRs, a finite-SNR framework that analyzes and describes...
Cognitive radio (CR) is a powerful solution that can significantly improve the utilization of the precious limited radio spectrum. It allows secondary users (SUs) to opportunistically access spectral holes of the licensed spectrum without causing harmful interference to primary users (PUs). However, waiting for idle timeslots may induce very poor quality of service (QoS) for SUs. To alleviate this,...
A time-varying channel estimation method for orthogonal frequency division multiplexing (OFDM) systems is presented. The proposed method makes use of two asymmetric pilot symbols to improve channel estimation performance and meanwhile obtain a reasonable pilot overhead. Complete simulations illustrate that the proposed method can have precise estimation result even under very large normalized Doppler...
Cognitive radio is a powerful solution that can significantly improve the utilization of the precious limited radio spectrum. It allows secondary users (SUs) to opportunistically access spectral holes in the licensed spectrum without causing harmful interference to primary users (PUs). However, the secondary communication opportunity becomes extremely poor when primary systems are heavily loaded....
OFDMA is a potential technology that can flexibly allocate subcarriers while providing diversity gain to multiple users. In our recent work, we showed a surprising result that the maximum frequency diversity gain in OFDMA systems is equal to the number of independent subcarriers, i.e., the same as that in point-to-point OFDM systems despite of the fact that multiple users will share a common set of...
Decision fusion rules for wireless sensor networks in fading channel are investigated in this paper. Optimal Likelihood ratio rule has been presented under the assumption of single-sideband Gaussian channel model. However, acquiring channel information may be too costly for resource constrained sensor networks. Suboptimal likelihood ratio fusion rule is proposed which requires only the knowledge of...
With the proliferation of wireless multimedia applications, multicast/broadcast has been recognized as an efficient technique to transmit a large volume of data to multiple mobile stations at the same time. In most multicast systems, the transmitter (e.g. base station) adapts its data rate to the furthest located users, so as to guarantee service quality to as many users as possible. Predictably,...
With the proliferation of wireless multimedia applications, multicast/broadcast has been recognized as an efficient technique to transmit a large volume of data to multiple mobile stations at the same time. In most multicast systems, the transmitter (e.g., base station) adapts its data rate to the worst channel among all users in the multicast group, so as to guarantee service quality to each user...
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