Conference Paper

A genetic algorithm based finger selection scheme for UWB MMSE rake receivers

Department of Electrical Engineering, Princeton University, Princeton, New Jersey, United States
DOI: 10.1109/ICU.2005.1569977 Conference: Ultra-Wideband, 2005. ICU 2005. 2005 IEEE International Conference on
Source: IEEE Xplore

ABSTRACT Due to a large number of multipath components in a typical ultra wideband (UWB) system, selective rake (SRake) receivers, which combine energy from a subset of multipath components, are commonly employed. In order to optimize system performance, an optimal selection of multipath components to be employed at fingers of an SRake receiver needs to be considered. In this paper, this finger selection problem is investigated for a minimum mean square error (MMSE) UWB SRake receiver. Since the optimal solution is NP hard, a genetic algorithm (GA) based iterative scheme is proposed, which can achieve near-optimal performance after a reasonable number of iterations. Simulation results are presented to compare the performance of the proposed finger selection algorithm with those of the conventional and optimal schemes.

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    ABSTRACT: This paper proposes a new pulse design method to improve spectrum utilization rate and reduce the outage probability in Ultra Wide Band (UWB) system. Several third derivative Gaussian waveforms are employed to generate the pulse based on the bandwidth constraint set by the US Federal Communications Commission (FCC) mask. The genetic algorithm (GA) is used to find the optimal pulse parameter. This method is an easy way to achieve in practical circuit implementation compared to one pulse generator, since COMS circuit is hard to produce one pulse with short duration and complex pulse shape. Comparisons with the traditional Gaussian pulse, the synthesis pulse by GA not only satisfy the FCC emission mask but also have high spectrum utilization rate. Simulation results show that the performances in indoor UWB system using the synthesis pulse by GA is better than that using traditional Gaussian pulse. Numerical results show that the synthesis pulse by GA is higher 30 percent of spectrum utilization rate and lower 65 percent of outage probability for the same transmission power, as well as lower 21 percent of outage probability for fixed Signal-to-noise ratio (SNR)at the receiver comparing with traditional Gaussian pulse. This proposed method not only use in indoor UWB system but also can extend to different communication system just changing the system object function.
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    ABSTRACT: The problem of choosing the multipath components to be employed at a selective Rake receiver, the finger selection problem, is considered for an impulse radio ultra-wideband system. First, the finger selection problem for MRC-Rake receivers is considered and the suboptimality of the conven-tional scheme is shown by formulating the optimal solution according to the SINR maximization criterion. Due to the complexity of the optimal solution, a convex formulation is obtained by means of integer relaxation techniques. Then, the finger selection for MMSE-Rake receivers is studied and optimal and suboptimal schemes are presented. Finally, a genetic algorithm based solution is proposed for the finger selection problem, which works for various multipath com-bining schemes. Simulation studies are presented to compare the performance of different algorithms. Index Terms— Ultra-wideband (UWB), impulse radio (IR), Rake receiver, convex optimization, integer program-ming, genetic algorithm (GA).
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    ABSTRACT: We propose a genetic algorithm (GA) based equalization approach for direct sequence Ultra-wideband (DS-UWB) wireless communications, where GA is combined with a RAKE receiver to combat the inter-symbol interference (ISI) due to the frequency selective nature of UWB channels for high data rate transmission. Simulation results show that the proposed GA based structure significantly outperforms the RAKE receiver. It also provides a close bit error rate (BER) performance to the optimal maximum likelihood detection (MLD) approach, while requiring a much lower computational complexity.
    Proceedings of the 2009 IEEE conference on Wireless Communications & Networking Conference; 04/2009

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