Tamer Elbatt - Academia.edu (original) (raw)

Papers by Tamer Elbatt

2001 MILCOM Proceedings Communications for Network-Centric Operations: Creating the Information Force (Cat. No.01CH37277), 2001

In this paper we investigate the problem of dynamic bandwidth reservation over the uplink of TDMA... more In this paper we investigate the problem of dynamic bandwidth reservation over the uplink of TDMA-based wireless networks providing prioritized services. The proposed multiple access protocol has the following salient features. First, it supports multiple levels of priorities. Second, it optimizes a unique cost function, that consists of a weighted sum of allocation "Deviation" functions, on a frame-by-frame basis. This, in turn, reduces the computational complexity signi cantly and hence makes it more suitable to real-time operation. Furthermore, the proposed cost function is amenable to analytical optimization techniques. Third, it supports wide variety of tra c classes, namely multimedia, short message bursts and call hand-o requests. The simulation results show the performance improvement achieved by this protocol compared to a heuristic policy based on Weighted Fair Queuing.

IEEE International Conference on Mobile Adhoc and Sensor Systems Conference, 2005., 2005

Abstract In this paper we explore the design of multi-modal MAC for wireless ad hoc and sensor ne... more Abstract In this paper we explore the design of multi-modal MAC for wireless ad hoc and sensor networks that dynamically adapt its behavior in order to minimize the energy to delivery ratio under a wide variety of network loads. The prime motivation is to balance the ...

2003 IEEE 58th Vehicular Technology Conference. VTC 2003-Fall (IEEE Cat. No.03CH37484), 2003

ABSTRACT We present a new approach for routing in multi-tier heterogeneous wireless mobile ad hoc... more ABSTRACT We present a new approach for routing in multi-tier heterogeneous wireless mobile ad hoc networks. This protocol, namely multi-virtual backbone protocol (MVP), naturally addresses key challenges arising from multi-tier wireless networks such as the coverage asymmetry and node heterogeneity. It also supports various QoS needs by constructing and maintaining QoS-specific virtual backbone infrastructure. A detailed algorithm is presented and preliminary simulation results are discussed.

2012 IEEE Wireless Communications and Networking Conference Workshops (WCNCW), 2012

In this paper, we analyze the performance of cooperative content caching in vehicular ad hoc netw... more In this paper, we analyze the performance of cooperative content caching in vehicular ad hoc networks (VANETs). In particular, we characterize, using analysis and simulations, the behavior of the probability of outage (i.e. not finding a requested data chunk at a neighbor) under freeway vehicular mobility. First, we introduce a formal definition for the probability of outage in the context of cooperative content caching. Second, we characterize, analytically, the outage probability under vehicular and random mobility scenarios. Next, we verify the analytical results using simulations and compare the performance under a number of plausible mobility scenarios. This provides key insights into the problem and the involved trade-offs and enable us to assess the potential opportunity offered by the, somewhat structured, vehicular mobility that can be exploited by cooperative content caching schemes. The presented numerical results exhibit complete agreement between the analytical and simulation studies. Finally, we observe that vehicular mobility creates opportunities for enhanced outage performance under practically relevant scenarios.

We present the new simulation and visualization tools tailored for 3-dimensional mobile ad hoc ne... more We present the new simulation and visualization tools tailored for 3-dimensional mobile ad hoc networking (MANET) research based on ns2 and nam.

We study a cellular setting in which an introduced multiple-antenna relay station (RS) can possib... more We study a cellular setting in which an introduced multiple-antenna relay station (RS) can possibly assist the bidi-rectional communication between a multiple-antenna base station (BS) and a set of single-antenna mobile stations (MSs). Through a proposed six-phase communication protocol with arbitrary number of antennas and MSs, we characterize the maximum number of degrees of freedom (DoF) that can be attained when the BS-MSs direct link is active or down. When the direct link is available, we show that the introduction of a multiple-antenna RS cannot increase the maximum DoF regardless of the number of antennas it is equipped with. In the absence of a BS-MSs direct link, the maximum DoF can be limited by the number of RS antennas since all ongoing communication takes place through the RS. It is also shown that the characterized maximum DoF is achieved via recently proposed network-coding based two-way relaying techniques. Finally, we conclude that a widely used two-phase multiple ...

In this paper, a multiuser cellular two-way relaying scenario is considered where multiple single... more In this paper, a multiuser cellular two-way relaying scenario is considered where multiple single-antenna mobile stations (MSs) and one multiple-antenna base station (BS) com-municate, bidirectionally, via one half-duplex multiple-antenna relay station (RS). Furthermore, the case when the number of antennas at the RS is not sufficient to decode the individual messages is addressed. For this case, a two-phase two-way relaying scenario is considered. In the first phase, the multiple access, a minimum Mean Square Error (MSE) optimization problem is formulated which is found to be non-convex. Thus, an iterative scheme is proposed to compute the MS transmit powers, the BS beamforming vectors, and the corresponding RS linear receivers to minimize the maximum MSE for multiple pairs subject to power constraints on the transmitting terminals. In the second phase, the broadcast phase, the beamforming vectors at the RS are designed to minimize the maximum MSE at the MSs subject to relay power ...

In this paper, we propose a new optimization-based access strategy of multipacket reception (MPR)... more In this paper, we propose a new optimization-based access strategy of multipacket reception (MPR) channel for multiple secondary users (SUs) accessing the primary user (PU) spectrum opportunistically. We devise an analytical model that realizes the multipacket access strategy of SUs that maximizes the throughput of individual backlogged SUs subject to queue stability of the PU. All the network receiving nodes have MPR capability. We aim at maximizing the throughput of the individual SUs such that the PU's queue is maintained stable. Moreover, we are interested in providing an energy efficient cognitive scheme. Therefore, we include energy constraints on the PU and SU average transmitted energy to the optimization problem. Each SU accesses the medium with certain probability that depends on the PU's activity, i.e., active or inactive. The results show a significant gain of the proposed scheme relative to other well-known access schemes up to $ 44 \% $ in terms of SU throughput.

2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communication (PIMRC), 2014

In this paper, we analyze the performance of a secondary link in a cognitive radio (CR) system op... more In this paper, we analyze the performance of a secondary link in a cognitive radio (CR) system operating under statistical quality of service (QoS) delay constraints. In particular, we quantify analytically the performance improvement for the secondary user (SU) when applying a feedback based sensing scheme under the “SINR Interference” model. We leverage the concept of effective capacity (EC) introduced earlier in the literature to quantify the wireless link performance under delay constraints, in an attempt to opportunistically support real-time applications. Towards this objective, we study a two-link network, a single secondary link and a primary network abstracted to a single primary link, with and without primary feedback exploitation. We analytically prove that exploiting primary feedback at the secondary transmitter improves the EC of the secondary user and decreases the secondary user average transmitted power. Finally, we present numerical results that support our analytic...

In this paper, we study the problem of cooperative communications in cognitive radio systems wher... more In this paper, we study the problem of cooperative communications in cognitive radio systems where the secondary user has limited relaying room for the overheard primary packets. More specifically, we characterize the stable throughput region of a cognitive radio network with a finite relaying buffer at the secondary user. Towards this objective, we formulate a constrained optimization problem for maximizing the secondary user throughput while guaranteeing the stability of the primary user queue. We consider a general cooperation policy where the packet admission and queue selection probabilities, at the secondary user, are both dependent on the state (length) of the finite relaying buffer. Despite the sheer complexity of the optimization problem, attributed to its non-convexity, we transform it to a linear program. Our numerical results reveal a number of valuable insights, e.g., it is always mutually beneficial to cooperate in delivering the primary packets in terms of expanding t...

2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communication (PIMRC), 2014

2015 International Conference on Computing, Networking and Communications (ICNC), 2015

In this paper, we propose a new optimization-based access strategy of multi-packet reception (MPR... more In this paper, we propose a new optimization-based access strategy of multi-packet reception (MPR) channel for multiple secondary users (SUs) accessing the primary user (PU) spectrum. We devise an analytical model that realizes the multipacket access strategy of the SUs. All the network receiving nodes have MPR capability. We aim at maximizing the throughput of the individual SUs subject to the PU's queue stability. Moreover, we are interested in providing an energy-efficient cognitive scheme. Therefore, we include energy constraints on the PU and SU average transmitted energy to the optimization problem. Each SU accesses the medium with certain probability that depends on the PU's activity, i.e., active or inactive. The numerical results show the advantage in terms of SU throughput of the proposed scheme over the conventional access scheme, where the SUs access the channel randomly with fixed power when the PU is sensed to be idle.

2000 IEEE International Conference on Communications. ICC 2000. Global Convergence Through Communications. Conference Record, 2000

In this paper we introduce the notion of power management within the context of wireless ad-hoc n... more In this paper we introduce the notion of power management within the context of wireless ad-hoc networks. More specifically, we investigate the effects of using different transmit powers on the average power consumption and end-to-end network throughput in a wireless ad-hoc environment. This power management approach would help in reducing the system power consumption and hence prolonging the battery life of mobile nodes. Furthermore, it improves the end-to-end network throughput as compared to other ad-hoc networks in which all mobile nodes use the same transmit power. The improvement is due to the achievement of a tradeoff between minimizing interference ranges, reduction in the average number of hops to reach a destination, the probability of having isolated clusters, and the average number of transmissions (including retransmissions due to collisions). The protocols would first dynamically determine an optimal connectivity range wherein they adapt their transmit powers so as to only reach a subset of the nodes in the network. The connectivity range would then be dynamically changed in a distributed manner so as to achieve the near optimal throughput. Minimal power routing is used to further enhance performance. Simulation studies are carried out in order to investigate these design approaches. It is seen a network with such a power managed scheme would achieve a better throughput performance and lower transmit power than a network without such a scheme.

Proceedings of GLOBECOM'96. 1996 IEEE Global Telecommunications Conference, 1996

2014 IEEE International Conference on Communications (ICC), 2014

ABSTRACT The global adoption of smart phones has raised major concerns about a potential surge in... more ABSTRACT The global adoption of smart phones has raised major concerns about a potential surge in the wireless traffic due to the excessive demand on multimedia services. This ever increasing demand is projected to cause significant congestions and degrade the quality of service for network users. In this paper, we develop a proactive caching framework that utilizes the predictability of the mobile user behavior to offload predictable traffic through the WiFi networks ahead of time. First, we formulate the proactive scheduling problem with the objective of maximizing the user-content hit ratio subject to constrains stemming from the user behavioral models. Second, we propose a quadratic-complexity (in the number of slots per day) greedy, yet, high performance heuristic algorithm that pinpoints the best download slot for each content item to attain maximal hit ratio. We confirm the merits of the proposed scheme based on the traces of a real dataset leveraging a large number of smart phone users who consistently utilized our framework for two months.

2006 First International Conference on Communications and Networking in China, 2006

Vehicle-to-vehicle communication research has gained tremendous interest in recent years due to i... more Vehicle-to-vehicle communication research has gained tremendous interest in recent years due to its importance in facilitating future active safety and telematics applications. However, with limited literature available, there is lack of understanding for modeling mobile-to-mobile channels in vehicular environments. In this paper, we conduct preliminary channel fading statistical analysis of empirical measurement data from devices compatible with the emerging Dedicated Short Range Communications (DSRC) standard. In particular, we use the Nakagami distribution to analyze the received signal strength (i.e., RSSI) from empirical measurement, and characterize the fading statistics as a function of distance for vehicular operating environment. Our analysis reveals that fading can be approximated by Rician distribution within 100m while it seems to follow Rayleigh distribution beyond 100m. The outcome of the study could be used for vehicular network simulation.

2013 IEEE Symposium on Computers and Communications (ISCC), 2013

Cognitive radio technology would enable a set of secondary users (SU) to opportunistically use th... more Cognitive radio technology would enable a set of secondary users (SU) to opportunistically use the spectrum licensed to a primary user (PU). On the appearance of this PU on a specific frequency band, any SU occupying this band should free it for PUs. Typically, SUs may collaborate to reduce the impact of cognitive users on the primary network and to improve the performance of the SUs. In this paper, we propose and analyze the performance of virtual reservation in collaborative cognitive networks. Virtual reservation is a novel link maintenance strategy that aims to maximize the throughput of the cognitive network through full spectrum utilization. Our performance evaluation shows significant improvements not only in the SUs blocking and forced termination probabilities but also in the throughput of cognitive users.

2014 IEEE Global Conference on Signal and Information Processing (GlobalSIP), 2014