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Adaptive relaying schemes significantly improve the performance of relay networks by switching the forwarding technique according to the reliability of the received signal. Moreover, efficient resource allocation is vital for meliorating the relay network performance. In this paper, the minimization of the number of active relays in conjunction with power optimization for adaptive relay networks is...
We consider a wireless relay network in a Rayleigh fading scenario where transmission power as well as transmission time per user are optimized. The criterion of optimization is the capacity. We apply an optimization algorithm based on Brent's method. Hence, we employ parabolic interpolation for finding the optimum whenever possible in order to achieve a faster convergence. If parabolic interpolation...
A two-hop relaying system where a source communicates with its destination through multiple relay nodes is studied for capacity maximization. Amplify-and-forward (AF) relaying is adopted for its simplicity. Taking the independent channel transfer function of different subcarriers and links into consideration, we formulate a resource allocation optimization problem for joint subcarrier assignment,...
In this paper, we consider the downlink scenario of a cellular cooperative OFDM network, in which the vacant user in the cell could serve as relay for the base station and forward the downlink data streams. With the channel information of the users in the cell, the base station not only allocates the power and subchannels to the users, but also decides the relay strategy for each subchannel. We derive...
The half-duplex multiple relay-assisted channel is investigated, where the relays work under decode-and-forward (DF) in time/frequency orthogonal resources. Achievable rates are optimized with respect to the transmitted powers and with respect to the fraction of time/bandwidth allocated to the relay-receive and the relay-transmit phases. Different transmission strategies associated to different complexities...
Optimum resource allocation is essential for wireless cooperative networks. Instead of limiting to energy optimization, we recently investigated the two-dimensional energy and location optimization with arbitrary number of relays, and in the presence of possible direct source-destination link. In this paper, we consider several practical issues in such a 2-D optimization. These issues include the...
In this paper, resource allocation problems in a downlink relay-assistant OFDMA cellular system are studied. Amplify-and-forward relaying strategy is utilized at each relay station to assist signal transmission while half-duplex transmission protocol is adopted. A joint optimization of subcarrier-pairing in two consecutive time slots and power allocation on each subcarrier in each time slot is investigated...
We propose a compress-and-forward (CF) strategy for relaying over parallel Gaussian channels. The proposed CF strategy compresses received signals at the relay under a constraint on the product of their allowable distortions and forwards them to the destination over all subchannels. Then, power allocation over all subchannels at both the source and the relay and bit allocation for compressing received...
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