In this paper, we consider an optimal power allocation scheme for Rayleigh fading channels in cognitive relay networks considering both total transmit power and average interference power constraints. We derive the optimal power allocation scheme between the cognitive source and relay aiming at minimizing the bit error rate of cognitive system by applying convex optimization method. Simulation ...

In this paper, an optimal wireless resources allocation scheme is put forward to improve the performance for both cellular and Device-to-Device (D2D) users in a hybrid network. The resource unit and power allocation can be modeled into a sum-rate optimization problem with the constraint of power limitation and rate ratio. The rate ratio is used to measure the data rate requirements from both ce...

This paper examines the bit and power allocation problem for orthogonal frequency division multiplexing systems in which the overall transmission power is minimized by constraining the fixed data rate and bit error rate. To provide the optimal allocation with less computational complexity, we propose new bit and power allocation schemes based on the Lagrangian method. Firstly, we propose an ini...

Secured communications in the presence of eavesdropper node is grave for the successful operations in the wireless relay networks. In the proposed work, choose two hop wireless relay networks to enhance security against the eavesdropper node. This paper considers four node networks, they are one source, and three decode and forward relay, one destination and one eavesdropper node. To transmit t...

In this paper, we investigate the relay placement and power allocation for decode-and-forward (DF) cooperative relaying over correlated lognormal shadowed Rayleigh fading channels. Assuming that maximum-ratio combining is performed at the destination, we first derive an upper bound of symbol error rate (SER) withM-phase-shift keying (PSK) modulation. Then, three optimization problems are formul...

© 2015 Rugui Yao et al. 11 http://dx.doi.org/10.4218/etrij.15.0114.0758 This paper deals with optimal power allocation for channel estimation of orthogonal frequency-division multiplexing uplinks in time-varying channels. In the existing literature, the estimation of time-varying channel response in an uplink environment can be accomplished by estimating the corresponding channel parameters. Ac...

This paper studies the power allocation problem in energy harvesting systems with finite battery. We adopt the discretized energy arrival and power allocation model. Hence, the service process can be modeled as a finite state Markov chain. Based on the discretized model, we analyze the stationary distribution of the Markov chain and formulate the utility maximization problem, which is then refo...

Flexible AC Transmission Systems (FACTS) devices have shown satisfactory performance in alleviating the problems of electrical transmission systems. Optimal FACTS allocation problem, which includes finding optimal type and location of these devices, have been widely studied by researchers for improving variety of power system technical parameters. In this paper, a DIgSILENT-based Discrete Parti...

We propose combining channel estimation and optimal power allocation approaches for a multiple-antenna orthogonal frequency division multiplexing (OFDM) system in high-speed transmission applications. We develop a least-square channel estimation approach, derive the performance bound of the estimator, and investigate the optimal training sequences for initial channel acquisition. Based on the c...

In this letter, power allocation methods are devised for Amplify-and-Forward (AF) opportunistic relaying systems aiming at minimizing the outage probability. First, we extend the result on outage probability in [8] and develop an approximate expression to simplify the power allocation problem. A corresponding optimization problem is constructed and proved to be convex. Then an iterative numeric...