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This work presents joint iterative power allocation and interference suppression algorithms for DS-CDMA networks which employ multiple relays and the amplify and forward cooperation strategy. We propose a joint constrained optimization framework that considers the allocation of power levels across the relays subject to individual and global power constraints and the design of linear receivers for...
In time varying relay networks, imperfect channel estimation deteriorates the performance and must be accounted for system design. By doing this, this paper derives the achievable rate expressions first, and then studies the training optimization problem based on those rates for both Amplify-and-Forward (AF) and Decode-and-Forward (DF) relay networks. There are two kinds of training designs for relay...
Cooperative communication is a technique that can be employed to meet the increased throughput needs of next-generation WiMAX systems. In a cooperative scenario, multiple stations can jointly emulate the antenna elements of a multi-input multi-output (MIMO) system in a distributed fashion. Although distributed space-time coding (DSTC) is being considered by the IEEE 802.16j/16 m standards for spatial...
Cooperative diversity is a promising technology for future wireless networks. In this paper, we consider a cooperative communication system operating in an amplify-and-forward (AF) mode with an imperfectly-known relay fading channel. It is assumed that a pilot symbol assisted modulation (PSAM) scheme with linear minimum mean square estimator (LMMSE) is used for the channel estimation. A simple and...
The network planning aims to allow the maximum number of users and throughput in a network. This imposes a demanding performance requirement on the new relay-based architecture for mobile WiMAX, in which the capacity estimation is complex. In the network design process, where interference avoidance plays an important role, WiMAX supports reconfiguration of the subchannel usage with some frequency...
Cooperative communication techniques promise the advantages of MIMO (multi-input multi-output) communications for wireless scenarios with single-antenna terminals. A main assumption in majority of the existing literature on cooperative communications is the availability of channel state information at the receiver. In practice, knowledge of the channel is obtained by sending known training (pilot)...
This paper studies two-way multi-antenna amplify- and-forward relaying using physical layer network coding. So far, the design of the relay matrix for sum rate maximization has been based on the assumption of complete channel state information (CSI). Designs for the relay matrix based on covariance feedback are proposed in this paper. The optimal relay matrix is estimated using the Monte Carlo method,...
In this paper, transmission over time-selective, flat fading relay channels is studied. It is assumed that channel fading coefficients are not known a priori. Transmission takes place in two phases: network training phase and data transmission phase. In the training phase, pilot symbols are sent and the receivers employ single-pilot MMSE estimation or noncausal Wiener filter to learn the channel....
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