Mosa Ali Abu-Rgheff

An Efficient and Lightweight Intrusion Detection Mechanism for Service-Oriented Vehicular Networks

Vehicular ad hoc networks (VANETs) are wireless networks that provide high-rate data communication among moving vehicles and between the vehicles and the road-side units. VANETs are considered as the main wireless communication platforms for the intelligent transportation systems (ITS). Service-oriented vehicular networks are special categories for VANETs that support diverse infrastructure-based commercial infotainment services including, for instance, Internet access, real-time traffic monitoring and management, video streaming. Security is a fundamental issue for these service networks due to the relevant business information handled in these networks. In this paper, we design and implement an efficient and light-weight intrusion detection mechanism, called efficient and light-weight intrusion detection mechanism for vehicular network (ELIDV) that aims to protect the network against three kinds of attacks: denial of service (DoS), integrity target, and false alerts generation. ELIDV is based on a set of rules that detects malicious vehicles promptly and with high accuracy. We present the performance analysis of our detection mechanism using NS-3 simulator. Our simulation results show that ELIDV exhibits a high-level security in terms of highly accurate detection rate (detection rate more than 97%), low false positive rate (close to 1%), and exhibits a lower overhead compared to contemporary frameworks.

Space-Orthogonal Frequency-Time medium access control (SOFT MAC) for VANET

The IEEE is working on a MAC standard (802.11p) for VANET based on 802.11e. Although the access function of 802.11e supports QoS by using different backoff counters and interframe spaces for different QoS requirements, this reduces to a best effort service and low performance when the number of vehicles increases. Some applications of VANET, particularly safety related, have strict QoS requirements that cannot be guaranteed by 802.11p especially in heavy traffic conditions. To resolve these issues, we propose Space-Orthogonal Frequency-Time medium access control (SOFT MAC) protocol that can support QoS requirements and is compatible with 802.11 standard. The proposed MAC allocates guaranteed transmission slots via reservation and also has a random access period for best effort service. Reservations are allocated in a distributed manner without the need for a basestation or a cluster head. In this paper we analyse and discuss in details the rules and algorithms that govern SOFT MAC protocol and also explain its implementation using 802.11. The analysis of SOFT MAC proves it achieves higher saturation throughput than 802.11.

Signalling analysis of cost-efficient mobility support by integrating mobile IP and SIP in all IP wireless networks

Next-generation wireless systems are expected to support efficient IP-based terminal and personal mobility. Novel mobility-support architecture called integrated MIP–SIP is designed based on the integration of mobile IP (MIP) and session initiation protocol (SIP), which dynamically combines and leverages the advantages of both protocols in a cost-effective way. The design motivation and methodology is to make full use of standardized work from both protocols, select composite processes that are more efficient for common functions, integrate similar entities and procedures to reduce redundancies, and avoid further duplicate standardization. By these means, the system efficiency can be greatly improved. The essential mobility procedures presented are applicable to both MIPv4 and MIPv6, though IPv6 is focused on. Both analytical and simulation results show that the proposed architecture outperforms existing hybrid MIP–SIP and pure SIP mobility approaches in terms of a clear-cut reduction in mobility signalling loads, which is crucial to the resource management in wireless networks. Copyright

Performance evaluation of cognitive radio spectrum sensing using multitaper-singular value decomposition

Cognitive Radio (CR) is a promising technology for the efficient use of available spectrum. Reliable detection of Primary User (PR) signals and spectrum sensing are the most important challenges which meet the implementation of the CR. In CRs communications, the PR user must be protected from the interference from the CR users. This can be achieved only by using an optimal spectrum sensing. In this paper we apply the Multitaper Method with Singular Value Decomposition (MTMSVD) in the estimation of the power spectrum density and the decision about the presence or the absence of PR transmission. Our system model consists of a licensed PR user transmits QPSK-OFDM signal in a specific band, and a number of CRs sensors that detect the PR users signal and this information is used by a CR base station to facilitate the CR users communications through AWGN channel. We will compare the MTM-SVD technique with the conventional method of power spectrum density estimation (periodogram). Our results show that the MTM-SVD has a better performance in low SNR compared with the energy detection method. Furthermore, MTM-SVD is a powerful method that combines the mutual information using a number of sensors and different tapers. The decision process has a large threshold margin, which increases the probability of the correct decision. Increasing the sensors improves the performance of the spectral sensing in a low SNR environment.

An adaptive channel model for VBLAST in vehicular networks

The wireless transmission environment in vehicular ad hoc systems varies from line of sight with few surroundings to rich Rayleigh fading. An efficient communication system must adapt itself to these diverse conditions. Multiple antenna systems are known to provide superior performance compared to single antenna systems in terms of capacity and reliability. The correlation between the antennas has a great effect on the performance of MIMO systems. In this paper we introduce a novel adaptive channel model for MIMO-VBLAST systems in vehicular ad hoc networks. Using the proposed model, the correlation between the antennas was investigated. Although the line of sight is ideal for single antenna systems, it severely degrades the performance of VBLAST systems since it increases the correlation between the antennas. A channel update algorithm using single tap Kalman filters for VBLAST in flat fading channels has also been derived and evaluated. At 12 dB , the new algorithm showed 50% reduction in the mean square error (MSE) between the actual channel and the corresponding updated estimate compared to the MSE without update. The computational requirement of the proposed algorithm for a VBLAST is 6 real multiplications and 4 real additions.

Local MTM-SVD based spectrum sensing in SIMO OFDM cognitive radio under bandwidth constraint

In this paper, we propose using local multitaper-singular value decomposition (Local-MTM-SVD) for spectrum sensing in OFDM-based cognitive radio (CR) systems. The spectrum sensing locality in this technique is enhanced by using single input at the primary (PR) transmitter and multi output antenna system (SIMO) at the different CR nodes (sensors). The global decision is declared using the OR rule at the CR basestation based on hard cooperation. This technique reduces the bandwidth of the feedback channel, and for powerful spectrum sensing technique; the MTM-SVD is used. Our proposed technique is examined using software simulation and theoretical analysis. The results show that there is a significant improvement in the probability of detection compared to using MTM only, or using the periodogram with single antenna in both AWGN and Rayleigh flat fading environments. We found the number of singular value squares that are useful in the technique is equal to or smaller than 2 when the total number of generated singular values is 4, and the MTM only technique tends to offer same performance as the Local-MTM-SVD technique using single antenna in the same conditions. The choice of the decision threshold level depends on the number of singular value squares which we used in the decision statistic.

Efficient subcarrier allocation in downlink multiuser MIMO-OFDM systems

This paper proposes a unit power based subcarrier allocation algorithm with the aim of minimizing the total transmit power in the downlink multiuser MIMO-OFDM systems, and compares its performance and complexity with Zhangs algorithm and extended Correlation-based algorithm (ECBA). By applying Singular Value Decomposition (SVD), the inter-antenna interference (IAI) and multiple user interference (MUI) can be minimized. Our proposal is combined with the single user optimal bit allocation (OBA) algorithm to achieve the aim. We verify the proposal by simulation of the performance of total transmit power and calculating the computation complexity. The simulation results show our modification has significant improvement compared with Zhangs algorithm and the ECBA.

An Efficient Sub-optimal Subcarrier Allocation Algorithm for Multiuser OFDM System

This paper investigates the allocation of subcarriers and power in the downlink channels of multiuser OFDM systems. The goal is to minimize the total transmit power under the constraints of user data rates and bit error rate (BER). We propose a sub-optimal algorithm to achieve the goal in this paper. We introduce a new factor which is the gain difference between the maximum and the next maximum users’ channel gains for each subcarrier. Then the subcarriers are allocated to different users according to this factor. The simulation results show this algorithm outperforms the multiuser OFDM systems with static Frequency Division Multiple Access (FDMA) technique, also it outperforms the sub-optimal method proposed by Wong. We quantify the improvement in terms of total required transmit power and BER.

A channel update algorithm for VBLAST architecture in VANET

In this article, we introduce an algorithm to update the channel estimation in a flat fading channel. We assume an initial estimate of the channel is available, possibly from a training sequence, and the algorithm enhances this estimation so that longer packets and/or better BER can be achieved. The algorithm can work with any MIMO system but, when combined with VBLAST, can be implemented with a minor increase in hardware complexity. We assume flat fading with known maximum Doppler shift and SNR.

FFT-based frequency offset estimation in OFDM systems

In this paper, two fast and accurate FFT-based frequency offset estimation methods for OFDM systems are proposed. We analyze and simulate proposed methods in both Gaussian and multipath fading channels, and compare the results with those obtained using well known Schmidls method. The simulation results are presented in terms of Error Variance (EV). Both proposed FFT-based methods have significantly smaller EV than Schmidls method in AWGN and Multipath static fading channel and the proposed FFT method-II also has smaller EV than Schmidls method in multipath time-varying fading channel.