Mamoun F. Al-Mistarihi

Performance evaluation of selective and adaptive heads clustering algorithms over wireless sensor networks

Target tracking in wireless sensor networks can be considered as a milestone of a wide range of applications to permanently report, through network sensors, the positions of a mobile target to the base station during its move across a certain path. While tracking a mobile target, a lot of open challenges arise and need to be investigated and maintained which mainly include energy efficiency and tracking accuracy. In this paper, we propose three algorithms for tracking a mobile target in wireless sensor network utilizing cluster-based architecture, namely adaptive head, static head, and selective static head. Our goal is to achieve a promising tracking accuracy and energy efficiency by choosing the candidate sensor nodes nearby the target to participate in the tracking process while preserving the others in sleep state. Through Matlab simulation, we investigate the performance of the proposed algorithms in terms of energy consumption, tracking error, sensor density, as well as target speed. The results show that the adaptive head is the most efficient algorithm in terms of energy consumption while static and selective static heads algorithms are preferred as far as the tracking error is concerned especially when the target moves rapidly. Furthermore, the effectiveness of our proposed algorithms is verified through comparing their results with those obtained from previous algorithms.

Tree based dynamic address autoconfiguration in mobile ad hoc networks

In this paper, a dynamic address allocation protocol for mobile ad hoc networks (MANETs) has been proposed. The protocol is capable of assigning an address to the network nodes with low latency and communication overhead. It divides the network nodes into root, leaders and normal nodes according to the functions they perform. Address space is distributed between leaders in disjoint address blocks. The leaders are responsible for assigning the addresses to unconfigured nodes. The leaked addresses, lost by the nodes that leaving the network abruptly, are reclaimed in an efficient way so as to preserve the addresses. Network partitioning and merging problem was solved in the protocol with low cost. The proposed protocol proves effective in terms of time delay and communication overhead. It is shown that the protocol is applicable for large networks with high number of nodes and large areas. The proposed scheme works well in the contention environment without significant changes in performance or effects on other applications by wasting the bandwidth, it also overcomes the presence of packet loss, mainly by increasing the control packet in the networks to keep the address allocation protocol operational.

Performance evaluation of multiuser diversity in multiuser two-hop cooperative multi-relay wireless networks using maximal ratio combining over Rayleigh fading channels

Multiuser diversity MUD cooperative wireless networks combine the features of the MIMO systems without confronting the physical layer constraints by providing multiple copies of the transmitted signal from the source to the destination with the help of the relay node. Cooperative wireless networks have attracted the full attention in the last few years and are implemented widely in many wireless communication systems to adapt for the fading impairments, provide higher data rates, and improve the performance of the wireless communication systems. In this paper, we present an informative study for the reason of evaluating the performance of the MUD in the multiuser two-hop cooperative multi-relay networks using maximal ratio combining. Furthermore, we derive tight closed-form expressions of outage probability and symbol error probability for the amplify-and-forward and fixed decode-and-forward protocols with the MUD. Additionally, we conduct a simulation study to show to what extent our analytical and simulation results agree with each other. It is worthy to mention that our analytical and simulation results agree fairly with each other under high average signal-to-noise ratio, whereas they show that our proposed system with multiple relays provides significant improvements over those previously proposed systems having only one relay. Copyright

LEACH enhancements for wireless sensor networks based on energy model

The low-energy adaptive clustering hierarchy (LEACH) protocol is one of the most adaptive protocols used in the wireless sensor networks (WSNs). LEACH is a hierarchical model that provides a powerful strategy for energy balancing, using head rotations. However, the original LEACH protocol suffers from many drawbacks and many researchers proposed new methods to mitigate them. In this paper, we propose two approaches based on an energy model to enhance cluster heads (CHs) selection method through not only minimizing the power consumption of network nodes, but also minimizing the number of CHs. The first proposed approach effectively selects a cluster head that has the lowest power consumption when communicating with other nodes. In addition to what is proposed in the first approach, the idea of incorporating the shortest distance has been considered in the second proposed approach. This significantly decreases the energy consumption and increases the lifetime of associated nodes.

Quadratic pulse inversion ultrasonic imaging (QPI): detection of low-level harmonic activity of microbubble contrast agents [biomedical applications]

We present an ultrasonic imaging approach that combines harmonic-sensitive pulse sequences with a post-beamforming quadratic kernel derived from a 2nd-order Volterra filter (SOVF). This approach is designed to produce images with high sensitivity to nonlinear oscillations (20-30 dB below the fundamental) from microbubble ultrasound contrast agents (UCA) while maintaining high levels of noise rejection. In this paper, we demonstrate the performance of this approach with a pulse-inversion imaging sequence consisting of two transmit pulses with opposite polarity whose echoes are summed to enhance the even harmonics and suppress the fundamental. This is followed by an optimally designed SOVF-based quadratic kernel for further enhancing the harmonic signals, while maximizing the noise rejection. The approach is demonstrated experimentally using images from in vivo kidney after bolus injection with UCA. Imaging results, as well as the spectral contents of QPI data, show a significant increase in harmonic sensitivity and reduction in noise levels. Implications of this approach on new forms of functional ultrasound imaging are discussed.

Post-beamforming third-order Volterra filter (ThOVF) for pulse-echo ultrasonic imaging

A ThOVF is applied to separate linear, quadratic, and cubic components from beamformed ultrasonic pulse-echo imaging data from nonlinear media. In the context of imaging ultrasound contrast agents (UCAs) infused in tissue media, the ThOVF offers the advantage of essentially complete separation of the nonlinear responses of the UCAs and tissues (since the latter rarely produces higher than a quadratic nonlinear response). We describe an SVD-based robust algorithm for estimating the coefficients of the ThOVF from beamformed data. In addition, experimental results from imaging of UCA in flow channels through tissue-mimicking phantoms demonstrate the advantage of this approach. We show imaging results with computed contrast-to-tissue ratio (CTR), histograms of UCA and tissue regions, and average spectra from UCA and tissue region. These results individually and collectively support the hypothesis that ThOVF is the appropriate model for complete separation of the nonlinear echoes from UCA and tissue.

Closed-form expression of bit error rate in dual-hop dual-branch mixed relaying cooperative networks with best-path selection over Rayleigh fading channels

In this paper, a new cooperative-diversity network with simple dual hop virtual diversity with mixed decode-and-forward and amplify-and-forward with best path selection is proposed. A closed-form expression for the average bit error rate of the communication system, assuming phase shift keying modulation scheme over independent non-identical Rayleigh fading channels, is derived. The results show that the proposed model outperforms the regular cooperative network models with a sub-optimal allocation for the relay relative distance.

Network Address Assignment In Mobile Ad-Hoc networks

In this paper a dynamic address allocation protocol for mobile Ad Hoc networks (MANETs) capable of assigning an address to network nodes with low latency and communication overhead has been proposed. The protocol divides the network nodes into root, leaders and normal nodes based on their functions within the protocol. Address space are distributed between leaders in disjoint address tables. The leaders are responsible for assigning the addresses to unconfigured nodes. The leaked addresses which lost by the nodes that left the network abruptly, are reclaimed in an efficient way in order to preserve the addresses. Network partitioning and merging problem was solved in the protocol with low cost. The proposed protocol is scalable and proves its effectiveness in terms of time delay and communication overhead.

A collaborative reputation approach to avoid misbehaving nodes in MANETs

Ad-hoc networks carry out routing and forwarding functions through available nodes. These nodes act as base stations and also are involved in route discovery and maintenance, forwarding traffic, and network management functions. Nodes expend most of their energy to forward packets to others without receiving any direct gain from doing so. A misbehaving and greedy node only considers its own short-term utility, and it may not choose to participate within the network. A reputation approach (RAP) is proposed in this paper, based on the reputation model that is used to detect and isolate misbehaving nodes which do not cooperate in forwarding packets of other nodes. Promising results are found through extensive simulation using GloMoSim in identifying selfish nodes.

Closed-form expression for bit error rate in relay-based cooperative diversity systems over multipath fading channels with interference

Incremental relaying has been recently introduced to overcome the problem with the restricted resources utilization associated with fixed relaying schemes in a pre-determined manner. Only when the direct path is not usable, the incremental relaying exploits the feedback from the destination to inform the relay about the necessity to send the source signal. In this paper, the performance analysis in terms of the bit error rate (BER) of the decode-and-forward (DF) incremental relaying over mixed fading channels is provided. The effects of the Co-channel interference near the destination caused by the multiple L interferers are presented. Numerical results are provided to prove the solidity of our assumptions.