Papers by Duong Bui Hoang
2006 40th Annual Conference on Information Sciences and Systems, 2006
We introduce a new noncooperative eigencoding algorithm for MIMO Ad hoc networks. The algorithm p... more We introduce a new noncooperative eigencoding algorithm for MIMO Ad hoc networks. The algorithm performs generalized waterfilling with respect to its transmit covariance matrix and the receiving node covariance matrix, both of which can be estimated locally. The algorithm is first developed for narrow band MIMO networks, and then extended to frequency selective fading applications. A cooperative algorithm is also developed as a benchmark in simulations. Simulation results show that our noncooperative algorithm performance is close to that of the cooperative method and is much better than greedy optimization.
MILCOM 2005 - 2005 IEEE Military Communications Conference
The performance of multi-hop CSMA/CA networks has in most cases been evaluated via simulations, o... more The performance of multi-hop CSMA/CA networks has in most cases been evaluated via simulations, or analytically using a perfect collision channel model. Using such methods, one can neither have access to the capture nature of the terminals nor evaluate the performance of the network in a fading environment. In this paper a new analytical framework that takes into account these capture and fading effects is presented. The network investigated in this paper has an infinite number of nodes which is assumed to be spatially Poisson distributed. The approach is to develop analytical expressions for the transition probabilities in a Markov chain model of the network. A fast algorithm to solve these equations is also given. Numerical results show that the model agrees with simulation results for both omni-directional networks and networks employing beamforming. The framework can easily be extended and implemented for networks with different access protocols, routing strategies, and forward error correcting mechanisms. Therefore it provides a useful tool for cross-layer network design.
MILCOM 2005 - 2005 IEEE Military Communications Conference
The application of beamforming to mobile Ad hoc networks has been studied extensively. It has bee... more The application of beamforming to mobile Ad hoc networks has been studied extensively. It has been shown that a simple transmit beamforming protocol may yield better performance than a traditional four-way handshake protocol. However, for a data packet of moderate size (around 10 4 bits), obtaining a reasonable packet error rate in fast fading requires an average uncoded bit error rate of 10 −5. This is impractical in most radio networks and especially in the Ad hoc case. Therefore the use of error correcting codes is required. Furthermore, to fully take advantage of the channel capacity, an adaptation coding scheme with variable code rate is usually required. The choice of the variable rate coding scheme and MAC protocol has been addressed recently as a cross-layer design problem. However, most variable rate coding methods choose the rate in a heuristic manner. In this paper we introduce a procedure to calculate an appropriate code rate for an Ad hoc network employing both transmit and receive beamforming under a Basic Access(CSMA/CA) protocol. The method can easily be extended to RTS-CTS handshaking. Simulation results show that the new combination of variable-rate coding and beamforming improves network throughput significantly.
IEEE Transactions on Signal Processing, 2008
A new noncooperative eigencoding algorithm is introduced for multiple-input multiple-output (MIMO... more A new noncooperative eigencoding algorithm is introduced for multiple-input multiple-output (MIMO) ad hoc networks. The algorithm performs generalized waterfilling with respect to its transmit covariance matrix and the receive node covariance matrix, both of which can be estimated locally. A cooperative algorithm is also developed as a benchmark in simulations. Simulation results show that the noncooperative algorithm performance is close to that of the cooperative method and is much better than greedy optimization. A game theoretic interpretation of the algorithm is also provided.
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Papers by Duong Bui Hoang