Sylvie Perreau

Performance analysis of reactive shortest path and multipath routing mechanism with load balance

Research on multipath routing protocols to provide improved throughput and route resilience as compared with single-path routing has been explored in details in the context of wired networks. However, multipath routing mechanism has not been explored thoroughly in the domain of ad hoc networks. In this paper, we analyze and compare reactive single-path and multipath routing with load balance mechanisms in ad hoc networks, in terms of overhead, traffic distribution and connection throughput. The results reveals that in comparison with general single-path routing protocol, multipath routing mechanism creates more overheads but provides better performance in congestion and capacity provided that the route length is within a certain upper bound which is derivable. The analytical results are further confirmed by simulation.

Increasing the network performance using multi-path routing mechanism with load balance

Abstract Research on multi-path routing protocols to provide improved throughput and route resilience as compared with single-path routing has been explored in details in the context of wired networks. However, multi-path routing mechanisms have not been explored thoroughly in the domain of ad hoc networks. In this paper, we propose a new routing protocol which increases the network throughput. The protocol is a multi-path routing protocol with a load balance policy. The simulations show a significant improvement in terms of connection throughput and end-to-end delay, when compared to single-path routing. The second significant contribution of this paper is a theoretical analysis allowing to compare reactive single-path and multi-path routing with load balance mechanisms in ad hoc networks, in terms of overheads, traffic distribution and connection throughput. The results reveal that multi-path routing (using a load balance policy) provides better performance than reactive single-path routing in terms of congestion and connection throughput, provided that the average route length is smaller than certain upper bounds which are derived and depend on parameters specific to the network. These upper bounds are very crucial because they can be taken into account as constraints in the route discovery mechanism so that the multi-path routing protocol is guaranteed to lead to an increase performance than a simple single-path one. Also, our analysis provide some insight into choosing the right trade-off between increased overheads and better performance. We show in particular that for certain networks, a multi-path routing strategy is not worth considering.

Multi-path routing protocol with load balancing policy in mobile ad hoc network

Research on multi-path routing to provide improved throughput and route resilience as compared with single-path routing has been explored in detail in the context of wired networks. However, multi-path routing has not been explored thoroughly in the domain of ad hoc networks. We propose a multi-path routing protocol with a load balancing policy to improve the network throughput, decrease average end-to-end delay and reduce congestion in ad hoc networks. We apply our scheme as an extension on top of existing dynamic source routing (DSR) and study the performance of our scheme using simulations. The simulations show a 15-20% improvement in packet delivery ratio and average end-to-end delay.

A Flow Based Detection Mechanism against Flooding Attacks in Mobile Ad Hoc Networks

Mobile ad hoc network (MANET) is particularly vulnerable to flooding attacks. To evade being identified, attackers usually recruit multiple accomplices to dilute attack traffic density of each attack source, and use the address spoofing technique to challenge attack tracing. In this paper, we present a detailed investigation of the flooding attack in MANET. Further, we design two flow based detection features, and apply the cumulative sum algorithm on them to effectively and accurately detect such attack.

Reduced computation blind equalization for FIR channel input Markov models

The paper deals with adaptive blind equalization for the transmission of digital modulated signals on an unknown dispersive channel with additive white gaussian noise. The observed signal being modeled as a hidden Markov model(HMM), the expectation-maximization (EM) algorithm can be used to realize both the channel identification and the estimation of the emitted symbols. The paper proposes a new on-line algorithm with reduced complexity. This algorithm, obtained as an approximate solution of the maximum likelihood (ML) problem via the EM sequential algorithm, has strong connections with decision feedback equalizers (DFE) using the recursive least square (RLS) Algorithm.

Performance analysis of 802.11 CSMA/CA for infrastructure networks under finite load conditions

In this paper we investigate the performance of 802.11 carrier sense multiple access with collision avoidance algorithm for infrastructure networks under finite load conditions. An analytical model based on discrete time Markov chain is proposed to compute essential performance characteristics. The closed form solutions for the chains stationary distribution and system throughput are derived. We model each wireless station as an M/G/1/ queue. The model accounts for arbitrary packet arrival rate, wireless channel access delay, transmission retry limits and arbitrary packet size distribution. Analytical results are verified through extensive simulation

MMSE multiuser downlink multiple antenna transmission for CDMA systems

In this paper, we propose a new downlink transmit antenna processing (TAP) technique for code division multiple access (CDMA) equipped with multiple transmit antennas. In order to find the weight vectors for downlink signals, a minimum mean square error (MMSE) performance criterion is used. Since the multiuser interference is taken into account in the calculation of the weighting vectors for TAP, the proposed method is a multiuser downlink TAP method. It is assumed that the downlink channels are known by the downlink TAP. For given channel conditions, the optimal weight vectors are found with a closed-form expression under both flat and frequency-selective fading channel assumptions.

Sensor Networks Protocol Design Using Random Markov Field Theory

In this paper, we present a new general framework allowing sensor networks design using Random Markov Fields (MRF) theory. We explain how the principles underlying MRF theory naturally fit design requirements in sensor networks in particular the need to rely on decentralised and distributed methods to solve global optimisation problems. We illustrate the potential of this new general concept with the practical problems of power control and resource allocation. In addition, we present a new method to improve the convergence rate of the simulated annealing when the sensor network design problem is a constrained optimisation problem.

A New Contour Detection Approach in Mammogram Using Rational Wavelet Filtering and MRF Smoothing

This paper presents a new approach to detect breast contour in mammogram. Formed from a class of rational orthogonal wavelets (ROWs), a 2-D image filter is constructed for prefiltering of the mammogram. The filtered image facilitates a simple binarisation of the mammogram. An initial breast contour is then extracted from the binarised image with a simple boundary scan technique. Based on Markov Random Field (MRF) modelling and iterated conditional modes (ICM) relaxation, a smoothing algorithm is developed to further smooth the initial contour. The proposed smoothing algorithm has a unique advantage of smoothing the breast contour while the nipple is preserved with high fidelity. In comparison with contour detection techniques relying on the calculation of varying thresholds based on histgram analysis, a single fixed ROW image filter is sufficient for all mammograms being analysed. The ROW filter is adaptive to varying statistics of mammograms regarding the pixel intensity. Results prove the robustness of the proposed detection algorithm for 82 mammograms from the Mini-MIAS database.

Trace Flooding Attack in Mobile Ad Hoc Networks

Mobile ad hoc networks (MANETs) are particularly vulnerable to denial of service (DoS) attacks. Existing DoS attack traceback approaches are not suitable for tracing the flooding attacks in MANETs. The challenges root in several facts, such as the node mobility and the presence of address spoofing. In this work, we present a behavior-based traceback mechanism to identify flooding attack origins. In addition, we also propose an attack isolation scheme to alleviate the attack impact on the network. Simulations are conducted to evaluate the traceback and attack isolation performance.