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We propose a cooperative signal-forwarding scheme for wireless sensor and mesh networks using semidefinite constraints. We consider a multiple source-destination scenario where a set of relays assists forwarding signals from sources to destinations. This paper assumes cooperation between relays so that the signals received from source nodes are passed between the relays. A semidefinite programming...
A cooperative relaying scheme is proposed for an underlay cognitive radio network where relays use their beam steering capability to impose target SINRs at the secondary user terminals whilst keeping the interference and noise leakage to the primary users below a threshold. The scheme is developed to incorporate per relay antenna power constraint that limits the power emitted by the relays. The scheme...
We propose a cooperative relaying strategy for wireless mesh networks where a set of relay nodes assists forwarding signals from multiple sources to multiple destinations. A semi- definite programming framework is used to ensure target SINRs at the destination are achieved with minimum possible transmit power at the relay layers. The proposed algorithm also considers various level of quantization...
The problem of multiuser multiplexing with a MIMO sub system for each individual user is considered. We demonstrate that the capacity performance of the null space based spatial multiplexing schemes can be improved with iterative power allocation within the iterative design process. We considered water-filling based local and global power allocation and demonstrate that both schemes outperform the...
Cognitive radio networks opportunistically operate in frequency bands that have been licensed to other networks. Therefore, communication between unlicensed users should ensure the interference leaked to the licensed users is kept below an acceptable level while achieving the required quality of services. In this paper, we extend SINR balancing technique to serve multiple cognitive users in the downlink...
In order to obtain a good balance of bit error rate (BER) across channels, the geometric mean decomposition (GMD) is introduced to replace the singular value decomposition (SVD) for precoding in the downlink of a multiuser multistream multiple-input multiple-output (MIMO) system. By combining GMD with a block diagonalization method, we obtain two kinds of precoding schemes: iterative nullspace-directed...
Cognitive radio networks have the ability to efficiently utilize the scarce radio spectrum by allowing unlicensed users to access the licensed frequency bands in the absence of licensed users. Transmit beamformers can be designed by setting constraints on the interference temperature of the licensed users and signal to interference and noise ratios (SINRs) of the cognitive users. This design is however...
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