Mahmoud A. Khodeir

Network Survivability for Multiple Probabilistic Failures

Network service recovery from multiple correlated failures is a major concern given the increased level of infrastructure vulnerability to natural disasters, massive power failures, and malicious attacks. To properly address this problem, a novel path protection solution is proposed to jointly incorporate traffic engineering and risk minimization objectives. The framework assumes probabilistic link failures and is evaluated against some existing multi-failure recovery schemes using network simulation.

Incremental-Relaying Cooperative-Networks using Dual Transmit Diversity and Decode and Forward Relaying Scheme with Best Relay Selection.

A new incremental-relaying cooperative-diversity technique with a simple dual transmit diversity, decode-and-forward and best relay selection scheme is presented. Closed-form expressions for the the bit error rate, the signal to noise ratio outage probability, and average achievable rate are derived using binary phase shift keying modulation scheme over independent non-identical Rayleigh fading channels. The results show that the simple space time block coding scheme with the incremental-relaying cooperative diversity and best relay selection outperforms the regular incremental fixed cooperative diversity and saves resources.

Incremental-relaying cooperative networks using dual transmit diversity with AF technique

A new incremental-relaying cooperative-diversity technique with a simple dual transmit diversity and amplify-and-forward scheme is presented. Closed-form expressions for the the bit error rate and the signal to noise ratio outage probability are derived using binary phase shift keying modulation scheme over independent non-identical Rayleigh fading channels. The results show that the simple space time block coding scheme with the incremental-relaying cooperative diversity outperforms the regular incremental cooperative diversity when the same transmit power is used.

Overlay network scheduling design

Abstract Advance reservation services are being used by a range of applications to schedule connection bandwidth resources at future time intervals. To date many different algorithms have been developed to support various point-to-point reservation models. However, with expanding data distribution needs there is a need to schedule more complex service types to provide connectivity between multiple sites/locations. In particular, these offerings can help improve network resource utilization and help expand carrier service portfolios. Along these lines, this paper presents a novel, scalable optimization solution to schedule (virtual) overlay networks with fixed end-point nodes. An improved re-routing heuristic scheme is also proposed and analyzed for comparison purposes.

Modeling and design of an infrared-based identification (IRID) system-tag and reader design

Infrared based identification system is a promising alternative for radio frequency identification system in order to provide powerful solutions in many situations, i.e., to overcome radio frequency interference. In this work, an infrared-based identification system is modeled and designed. This model consists of a reader and a tag. The reader will perform particular functions in order to communicate with the tag via a wireless media, i.e., infrared channel. These functions include reading a tag identification number and write an identification number into a tag. The reader in the proposed model will display the received data using a liquid crystal display, allows the user to enter data as well as make control using a keypad, and can be connected to a computer to perform more complex functions. On the other hand, the proposed tag is designed to have some merits, i.e., small size, low power consumption, long lifetime, and low cost. Finally, the reader and the tag provide half-duplex communication using infrared transmitter and receiver.

Security enhancement using maximum ratio combining (MRC) diversity over nakagami-m fading channels

This paper presents a method of increasing the secrecy capactty utilizing the channel diversity technique in wireless communication. In general, a relatively higher secrecy capactty can be achieved at the intended receiver by deploying channel diversity to mitigate the effect of low signal to noise ratio. In this analysis, the legitimate receiver and the eavesdropper are assumed to employ maximal ratio combining diversity technique to combine the received signals coming from the transmitter. Considering Nakagami-m wireless fading channels, dosed-form expressions for the secrecy outage probability and the probability of secrecy capacity are derived, which can be used as quality of service metrics. The numerical result confirms that the security of any wireless network model or communication system at a common operating system can be improved by using maximal ratio combining diversity technique as expected.

Outage probability for end user mobile in cognitive relay networks over mixed fading channels

In this paper, an upper bound expression of the outage probability (OP) under interference power constraint is derived for cognitive amplify-and-forward (AF) relay network with best relay selection (BRS) scheme. In the proposed model, the destination moves at high speed, more than 100km/h and the channels that connected with destination are modeled as Nakagami-m fading channels, m < 1 whereas the other communication links are modeled by Rayleigh distribution. Analytical results are presented to evaluate the impact of the number of secondary relays, primary user (PU) location, and the severity parameter m on the performance of the cognitive relay network. Analytical results show that the Nakagami-m fading model can more accurately model conditions in vehicular environment.

On the outage probability in cognitive amplify-and-forward relaying systems over mixed fading channels for end user mobile

In this paper, closed form outage probability is derived for cognitive amplify-and-forward (AF) relaying system in a spectrum sharing environment for a moving end mobile users. The end users can move at high vehicular speeds which cause dynamic multipath fading and a high Doppler shift. The transmit power of the secondary network is governed by the maximum interference power that the primary networks receiver can tolerate. In the proposed model, the channel between relay to destination is modeled as Nakagami-m fading channel, m <; 1 that is most suitable for modeling channel fading at high mobility scenarios whereas the other communication links are modeled by Rayleigh distribution. The impact of the PU location on the OP performance is studied also.

Performance of multihop CDMA ad hoc networks with diversity combining techniques over fading environments

Abstract This study investigates the impact of the diversity combining techniques on the performance of wireless code division multiple access (CDMA) ad hoc networks operating over κ -μ fading channels, where the performance criterion in this study is in terms of the expected progress per hop. The probability density function (PDF) and the cumulative density function (CDF) of the interference power are obtained in κ -μ fading conditions. Furthermore, expression for the unconditional CDF of the signal-to-noise-and-interference ratio (SNIR) is derived, which is utilized to derive expressions for the expected progress per hop with selecting combining (SC) and maximal ratio combining (MRC) diversity. Corresponding expressions for Nakagami- m and Rician fading are presented in this paper as special cases of κ -μ fading. Numerical results are presented for illustration purposes.

On the outage probability in DF relay selection cooperative wireless networks over Nakagami-m fading channels

This paper proposes a method for transmitting data through a best relay selection technique in a cooperative network over Nakagami-m fading channels. The selection of the best relay among multiple decode and forward relays is based on the minimum outage probability criterion. Therefore, only the relay with the lowest outage probability will transfer the data to the destination. A closed-form expression is derived for the outage probability of the best relay selection with the decode and forward technique. Numerical examples are presented here for demonstration.