Rawya Rizk

A hybrid multi-path ant QoS routing algorithm for MANETs

Supporting multimedia for Mobile ad hoc networks (MANETs) is an important issue. This paper presents two routing algorithms in MANETs inspired by the ant colony optimization routing algorithms. The first algorithm is a Hybrid Multi-Ant (HMAnt) routing algorithm. It is a hybrid since it combines reactive path establishment with proactive path maintenance. It supports multi-path while maintaining an acceptable level of routing control overhead. The second algorithm is a HMAnt with QoS provision (HMAnt-QoS), which satisfies QoS requirements of the incoming traffic. Simulation results show that HMAnt outperforms AODV, AntNet, and AntHocNet in terms of end-to-end delay and packet delivery ratio, while having a moderate routing control overhead. HMAnt-QoS achieves its goal by providing paths that guarantee the QoS constraints for real time applications.

A hybrid rotation-invariant face recognition system using Log-Polar Transform

The recognition of human faces, especially those with different orientations is a challenging and important problem in image analysis and classification. This paper proposes an effective schema for rotation invariant face recognition using Log-Polar Transform and Discrete Cosine Transform combined features. The rotation invariant feature extraction for a given face image involves applying the log-polar transform to eliminate the rotation effect and to produce a row shifted log-polar image. The discrete cosine transform is then applied to eliminate the row shift effect and to generate the low-dimensional feature vector. A particle swarm optimization based feature selection algorithm is utilized to search the feature vector space for the optimal feature subset. Evolution is driven by a fitness function defined in terms of maximizing the between-class separation (scatter index). Experimental results based on the ORL face database using testing data sets for face images with different orientations show that the proposed system outperforms other face recognition methods. The overall recognition rate for the rotated test images being 97%, demonstrating that the extracted feature vector is an effective rotation invariant feature set with minimal set of selected features.

Spatio-temporal scalability based on motion-compensated DCT temporal filters

In this paper, a motion compensated temporal filtering (MCTF) framework based on the discrete cosine transform (DCT) is proposed and named MCDCT-TF. It is able to employ filters of any length with particular emphasis on 5/3 DCT and 7/4 DCT. The proposed MCDCT-TF and the two-dimensional (2-D) DCT decimation technique are incorporated into H.264/AVC to provide spatio-temporal scalability. Compared with the current MCTF schemes such as Haar, and 5/3 wavelet filters, simulation results show that the proposed MCDCT-TF utilizing longer tap DCT filters achieves a significant improvement in coding gain. Moreover, the performance gap between the presented scalable video coding and the single layer H.264/AVC is small. However, the presented spatio-temporal coding scheme outperforms the spatio-temporal supported in JSVM.

Motion-compensated DCT temporal filters for efficient spatio-temporal scalable video coding

Although most of the proposals for implementing motion-compensated temporal filtering (MCTF) schemes are based on the wavelet transform, in this paper, we propose an MCTF framework based on the discrete cosine transform (DCT). Using DCT decimation and interpolation, several temporal decomposition structures named motion-compensated DCT temporal filters (MCDCT-TF) are introduced. These structures are able to employ filters of any length with particular emphasis on 5/3 DCT and 7/4 DCT. The proposed MCDCT-TF and the two-dimensional (2D) DCT decimation technique are incorporated into H.264/AVC to provide spatio-temporal scalability. Compared with the current MCTF-based lifting schemes such as Haar, and 5/3 wavelet filters, simulation results show that the proposed MCDCT-TF utilizing longer tap DCT filters achieves a significant improvement in coding gain. The impact of odd/even group of frames, the decimation/interpolation ratios, and motion-compensated connectivity on the MCDCT-TF performance are also analyzed. Moreover, simulation results show that the performance of the presented scalable video coding is close to the single layer H.264/AVC and is slightly inferior to the temporal scalability supported in JSVM, the state-of-the-art scalable video coding standard, that gets its gain from Hierarchical B-pictures. However, our spatio-temporal coding scheme outperforms the spatio-temporal supported in JSVM even if it uses hierarchical B-pictures to improve its gain.

Protection Optimization for MPLS Networks

A crucial aspect in the development of a fault management system is the selection of backup paths. The main issue in this selection is a tradeoff between the resource consumption and the minimization of failure recovery time, link failure, and packet loss. In this paper, a general QoS backup protection optimization policy applicable to a wide range of network situations and traffic types is proposed. A comparison between the proposed policy and the conventional protection backup methods is performed. The numerical results show a significant improvement of the QoS protection over conventional protection backup methods at variable protection parameters, network constraints and traffic types.

A two-phase handoff policy for mobility management in wireless ATM

In the two-phase handoff protocol, although Phase II gives an optimal path, it may result an additional cost. A tradeoff between achieving optimal path and reducing the cost is an important issue. In this paper, the effect of network conditions on the expected cost at the conventional path optimization policies is studied. We show that none of the existing conventional path optimization policies is optimal at all network situations. A general cost optimization policy that is applicable to a wide range of network conditions is proposed. The numerical results show that the proposed cost optimization policy always achieves the minimum expected cost.

A cost optimisation policy for handoff rerouting

A two-phase handoff protocol has been proposed to support interswitch handoff in Wireless Asynchronous Transfer Mode (WATM) networks. An important issue is the determination of the best time to perform Phase 2. In this paper, it is shown that none of the existing conventional path optimisation policies is optimal at all network situations; hence, a general Cost Optimisation Policy (COP) applicable to a wide range of network conditions is proposed. It is based on the decision whether to exclude Phase 2 or select among the best path optimisation policies for this phase. The proposed policy avoids unnecessary path optimisations and achieves the lowest total expected cost at variable mobility factors and network conditions. A comparison between the proposed policy and conventional path optimisation policies is performed. The numerical results show a significant improvement of the total expected cost over conventional path optimisation policies at all network situations.