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It is important for sonar systems to distinguish the submerged source from the surface one. Current approaches based on matched field processing, mode scintillation and mode filtering require either precise knowledge of the ocean environment parameters or densely populated hydrophone arrays, and become problematic in practical use. Current waveguide invariant based method, deriving the distribution...
Future wireless systems face challenges in supporting high-rate multimedia streaming with wide coverage area and at low power. Cooperative relaying is investigated in the following context: a single base station with multiple antennas simultaneously transmits different data streams to single-antenna destinations through a set of single-antenna fixed relays, with no direct link transmission between...
To further increase the experienced data rate per user, and to overcome the poor indoor penetration and the presence of dead-spots, the network architectures with relays, picocells and femtocells underlaying the macrocell network which are commonly referred as heterogeneous networks have drawn more and more researching interests. One of the main challenges of heterogeneous networks is the severe inter-cell...
Future wireless systems face challenges in supporting high-rate multimedia streaming with wide coverage area and at low power. In this paper we study cooperative MIMO systems in the context of imperfect channel estimation with per-user quality-of-service constraints with the objective of minimizing the sum transmission power at the source and relays. Simulation results quantify the different performance...
Beamforming and relaying are two methods of improving wireless system performance. Until now, these techniques have been considered separately. In this paper, a single source (basestation) with multiple antennas broadcasts to multiple single-antenna destinations through a network of single-antenna relays. A transmit precoder is first proposed to optimize the system for a set of fixed relay gains and...
In this paper, we study the tradeoffs between basestation beamforming and distributed beamforming in the uplink. Here, multiple single-antenna sources access a multiple-antenna destination (basestation) through a network of single-antenna relays. In order to determine the solution, we decouple the problem into that of optimizing a linear decoder at the destination and that of optimizing relay beamforming...
Cognitive radio is viewed as a novel approach for improving the utilization of radio frequency spectrum greatly by intelligently search and utilize free spectrum not used by licensed user. Dynamic spectrum allocation technology is one of the key technologies in realization of cognitive radio. In this paper we propose a new algorithm for spectrum sharing which considering historical allocation information...
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