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A cognitive Multiple Access Channel with a Wire-tapper (cMAC-WT) is studied, where one of the two encoders is cognitive, in the sense that it knows a priori the message of the other encoder. Both the discrete and Gaussian models are considered. General achievable rates and outer bounds to the secrecy capacity region are derived, and the secrecy capacity region is identified for the special cases of...
Simple variations on rate-compatible channel codes are shown to achieve cooperative coding gains for the half-duplex relay channel without the complexity of capacity approaching codes. The simulated performance of an optimized irregular low density parity check code is provided.
This paper addresses the optimization of quantization at local sensors under strict energy constraint and imperfect transmission to improve the reconstruction performance at the fusion center in the wireless sensor networks (WSNs). We present optimized quantization scheme including the optimal quantization bit rate and the optimal transmission power allocation among quantization bits for BPSK signal...
In this paper, we investigate optimal power allocation to achieve perfect secrecy capacity in Gaussian MIMO wire-tap channels. The number of antennas in the MIMO wire-tap channel is arbitrary at the transmitter, the intended receiver, and the eavesdropper. For this challenging non-convex optimization problem, we design a novel global optimization algorithm called branch-and-bound with reformulation...
We consider a two-user symmetric gaussian interference channel (IC), in which one encoder is connected to the other by a unidirectional orthogonal cooperative link with specific capacity. In this setup, we employ a simplified Han-Kobayashi scheme along with cooperative communication. We characterize the generalized degrees of freedom of the channel for interference-limited regimes by comparing the...
Cooperative networking as a means of creating spatial diversity is used in order to mitigate the adverse effect of fading in a wireless channel and increase reliability of communications. We investigate signal-to-noise ratio (SNR) gain in wireless cooperative networks. We show that the differential SNR gain in the high data rate regime, which we refer to as SNR gain exponent zetainfin, is independent...
Imagine the vector y = Xbeta + epsi where beta isin Ropfm has only k non zero entries and epsi isin Rn is a Gaussian noise. This can be viewed as a linear system with sparsity constraints corrupted with noise. We find a non-asymptotic upper bound on the error probability of exact recovery of the sparsity pattern given any generic measurement matrix X. By drawing X from a Gaussian ensemble, as an example,...
In this work, a new upper bound for average error probability of a two-user discrete memoryless (DM) multiple-access channel (MAC) is derived. This bound can be universally obtained for all discrete memoryless MACs with given input and output alphabets. This is the first bound of this type that explicitly uses the method of expurgation. It is shown that the exponent of this bound is greater than or...
Resource allocation for half-duplex bidirectional relaying networks using partial channel state information (CSI) at the transmitters is considered, with an emphasis on the diversity-multiplexing tradeoff (DMT). It is assumed that there is a direct link between the sources. It is shown that decode-and-forward (DF) two-way relaying does not suffer from a diversity loss when the multiplexing gain is...
In this work, we derive new outer bounds for the two-user interference channel with confidential messages. An upper bound is found for the sum rate. When the interfering link of the first user is greater than 1, a new upper bound on 2R1 + R2 is obtained by studying a special form of the three-user interference channel. The bounds are then compared with known bounds for the symmetric interference channel...
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