Magdi M. S. El-Soudani

Wireless Vehicle Communication for Traffic Control in Urban Areas

This paper introduces the idea of using the stigmergic approach to solve traffic problems in congested urban areas and focuses on the communications aspect of the problem. V2I and I2V are based on IEEE 802.11 standard. The urban area is equipped with access points that are wired to a central node. The number of packets lost is investigated at different vehicle speeds as well as different I2V broadcast rates. The best broadcast rate is found in order to reduce the packets lost irrespective of vehicle speed

Effect of hamming coding on WSN lifetime and throughput

Wireless Sensor Networks has become an attractive field of research due to its wide range of applications. This paper focuses on improving network throughput without affecting the lifetime. It shows that the use of the Hamming code has a negligible effect on network lifetime irrespective of the SNR. In contrast, the CRC with retransmissions reduces the lifetime by 37.3% compared to the uncoded system. It is also proven that using the Hamming code increases system throughput when compared to the use of CRC. High-rate Hamming codes have a higher throughput than low-rate Hamming codes over network lifetime. Both AWGN and Rayleigh fading channels are considered. If the Network Master is used as a repeater, it is found that this generally increases network lifetime. Furthermore, at low SNR, system throughput in the case of high-rate Hamming codes is increased. The above results are shown both for fixed data and fixed frame schemes.

Cascading wireless industrial workcells

With the ever expanding implementation of Wireless Networked Control Systems in industrial automation, there is a need to guarantee that several workcells utilizing such systems can coexist in the same vicinity. Cascading several cells in different orientations is studied in this paper, with the goal of achieving direct concatenation with zero meters between cells. Different channel allocations are studied and analyzed in order to achieve correct operation of cascaded cells. It is shown that sensors and actuators communicating using the standard and unmodified 802.11b protocol send and receive packets correctly, within sampling period deadlines. System performance is also studied in the existence of interference from the 2.4GHz range guaranteeing correct packet transmission/reception. All simulations are run on OPNET Network Modeler, and results are subjected to a 95% confidence analysis.

New hybrid frequency reuse method for packet loss minimization in LTE network

This paper investigates the problem of inter-cell interference (ICI) in Long Term Evolution (LTE) mobile systems, which is one of the main problems that causes loss of packets between the base station and the mobile station. Recently, different frequency reuse methods, such as soft and fractional frequency reuse, have been introduced in order to mitigate this type of interference. In this paper, minimizing the packet loss between the base station and the mobile station is the main concern. Soft Frequency Reuse (SFR), which is the most popular frequency reuse method, is examined and the amount of packet loss is measured. In order to reduce packet loss, a new hybrid frequency reuse method is implemented. In this method, each cell occupies the same bandwidth of the SFR, but the total system bandwidth is greater than in SFR. This will provide the new method with a lot of new sub-carriers from the neighboring cells to reduce the ICI which represents a big problem in many applications and causes a lot of packets loss. It is found that the new hybrid frequency reuse method has noticeable improvement in the amount of packet loss compared to SFR method in the different frequency bands. Traffic congestion management in Intelligent Transportation system (ITS) is one of the important applications that is affected by the packet loss due to the large amount of traffic that is exchanged between the base station and the mobile node. Therefore, it is used as a studied application for the proposed frequency reuse method and the improvement in the amount of packet loss reached 49.4% in some frequency bands using the new hybrid frequency reuse method.

Designing near Shannon limit LDPC codes using particle swarm optimization algorithm

This paper presents a new design methodology/process for low-density parity-check codes (LDPC). To minimize the gap to Shannon limit, the particle swarm optimizer is applied to optimize the variable and check node degree distribution lambda and p respectively in case of irregular LDPC codes. discrete fast density evolution (FDE) is used (as the analysis technique) to compute the threshold value of LDPC code and the Shannon limit is evaluated based on Butman and McEliece formula. The results conducted show that, our proposed distributions with low degrees of (lambda, p) outperform other comparable distributions.

Node Deployment and Mobile Sinks for Wireless Sensor Networks Lifetime Improvement

In the last two decades, and owing to advances in MEMS technologies, wireless communications and low-power electronics, the development of low-cost micro sensor nodes was possible. This enabled the deployment of Wireless Sensor Networks (WSN) comprising large numbers of nodes to monitor various physical phenomena in real-time. This can be of prime importance in several industrial, environmental, health, and military applications (Akyildiz et al., 2002; Tavares et al., 2008). A WSN may have up to hundreds or even thousands of sensor nodes densely deployed either inside or close to a monitored area. Nodes process data prior to transmission, to ensure acquisition of accurate and detailed information. Processed information is then passed on to a sink node, which transmits necessary data to some base station. Nodes may also be divided into clusters, with nodes in each cluster sending data to a particular sink node. Sensor nodes typically operate in an unattended environment, and are equipped with small, often irreplaceable batteries with limited power capacity. Thus a major consideration in WSN research is to ensure reliable transmission of data while prolonging network lifetime by making maximum use of the available energy in the nodes (Heinzelman et al., 2002). In this chapter, recent work by the authors in the area of WSN is presented with particular emphasis on maximizing the lifetime of the network. In Section 2, algorithms are described that build upon two well known WSN routing techniques, namely LEACH (Heinzelman et al., 2000) and LEACH-C (Heinzelman et al., 2002) to further optimize network lifetime through carefully planned selection of the sink nodes. Simulation results that illustrate the resulting improvement in network lifetime are presented. The position of sensor nodes need not be predetermined, which allows random deployment in inaccessible terrains. However, in some applications, the deployment of nodes at pre-specified positions is feasible. Taking advantage of this feature is thus considered to achieve further enhancement in network lifetime by considering the effect of various geometrical distributions of nodes and relative sink locations. Further reductions of the transmission energy requirements can be attained by making use of uncontrolled mobile sinks in addition to the distant fixed sinks. It is not possible to 16

Cooperative Defense Firewall Protocol

Most of today’s firewalls are standalone systems. This fact leads to some limitations in defending organized multi-point attacks. Therefore, communicating firewalls were introduced. This opens the door for a cooperative defending technique, capable of pushing and isolating attacks far from the targets. In this work, we propose a new firewall communication protocol that fulfills the cooperative defense model. In this protocol, a firewall node broadcasts its security policy to the surrounding firewall nodes. The security policy travels in the path towards the point of attack, so the firewall nodes enforce the security policy and cooperate in defending the targets and isolating the attack to the closest possible point to the source of attack. The security of the communication protocol is studied to ensure its strength against some network threats and to protect the network from using the protocol itself in denial of service attacks. The behavior of the protocol is studied using a protocol simulator. Using this simulator, we execute different experiments to observe the protocol behavior.

Turbo coding scheme for GPRS system

In wireless communication systems, error control coding (ECC) is a necessity to provide reliable communications over unreliable channels. The ever evolving applications of 3G mobile systems are so demanding that the most efficient techniques for channel coding should be employed. Turbo codes have been shown to yield an outstanding coding gain close to theoretical limits in the additive white Gaussian noise (AWGN) channel. They have been studied over a Rayleigh fading channel as well and showed a remarkable performance. We propose a turbo coding scheme to replace the convolutional coding already in use in the General Packet Radio Service (GPRS) system (known as 2.5G). Evaluation of the proposed encoder by means of computer simulation has shown performance improvements over the two channel models considered.

A NOVEL Design Technique for LDPC Codes

New designing technique for different rates of Low-Density Parity-Check codes (LDPC) in Binary-Input AWGN channel is presented. To minimize the gap to Shannon bound, constrained particle swarm optimization (CPSO) algorithm is applied on the variable and check node degree distribution λ(x) and ρ(x) respectively in case of irregular LDPC codes. Adapted Discrete Fast Density Evolution (FDE) is used to calculate the threshold value of LDPC code. The obtained results show that, our proposed distributions with low upper bound on the maximum degrees of (λ, ρ) to satisfy simple decoding process have 0.1529 dB, 0.0127dB, 0.1220 dB, 0.0171 dB, and 0.1227dB gap to Shannon bound values for code rates 0.1, 0.3, 0.5, 0.7, and 0.9 respectively. This paper also introduces different construction techniques of parity-check H matrix for code rate equals to half. The first one is the proposed Accurate Random Construction Technique (ARCT) which is a modification of the traditional Random Construction Technique (RCT) to satisfy an accurate profile. The second technique, Speed Up Technique (SUT), improves the performance of irregular LDPC codes by creating H matrix from proposed initial construction ensures no cycles not from empty matrix as usual. The third and fourth techniques are further improvements of the SUT that insure simpler decoding process by using smaller decoder size. In Double Speed Up Technique (DSUT), SUT matrix of size M×N is used to construct H matrix with double size, i.e. block length = 2N but the decoder size is still M×N. In Partitioned Speed Up Technique (PSUT), the H matrix size is fixed to M×N and small SUT submatrix is used to grow it. Therefore the decoder size is the size of the SUT submatrix. Simulations show that the performance of LDPC codes formed using SUT outperforms ARCT at block length N = 1000 with 0.342dB at BER = 10 and LDPC codes created by DSUT outperforms SUT with 0.194dB at BER = 10. Simulations illustrate that the partitioning of H matrix to small SUT submatrices not only simplifies the decoding process, it also simplifies the implementation and improves the performance. The improvement, in case of half, is 0.139dB at BER=10 however as partitioning increases the performance degrades. It is about 0.322dB at BER=10 in case of one-fourth. Index Terms :– Fast Density Evolution (FDE), Low-Density Parity-Check Codes (LDPC), Constrained Particle Swarm Optimization (CPSO) Algorithm, Shannon bound, Threshold value, Profile, Random Construction Technique (RCT), Accurate Random Construction Technique (ARCT), Speed Up Technique (SUT).

Link Adaptation Based on Explicit Channel Estimation for Throughput Maximization Over Rayleigh Fading Channels

Link Adaptation (LA) has been proposed in the literature as a means of increasing the throughput obtained by each user in wireless communication systems. Due to its significant simplicity, LA has even been adopted as the standard adaptive coding technique for the next generation mobile communication system known as EDGE. In this paper, we present a novel link adaptation technique, valid for use in the case of Rayleigh fading wireless channels. The new technique is based on the blind channel estimation algorithm usually used for combating inter-symbol interference (ISI). The algorithm is presented and its efficiency in providing the maximum available throughput is illustrated by means of computer simulations.