Showing papers by "Mohsen Guizani published in 2008"
TL;DR: This paper reviews several routing protocols proposed for possible deployment of mobile ad hoc networks in military, government and commercial applications with a particular focus on security aspects, and analyses of the secure versions of the proposed protocols are discussed.
Abstract: Several routing protocols have been proposed in recent years for possible deployment of mobile ad hoc networks (MANETs) in military, government and commercial applications. In this paper, we review these protocols with a particular focus on security aspects. The protocols differ in terms of routing methodologies and the information used to make routing decisions. Four representative routing protocols are chosen for analysis and evaluation including: Ad Hoc on demand Distance Vector routing (AODV), Dynamic Source Routing (DSR), Optimized Link State Routing (OLSR) and Temporally Ordered Routing Algorithm (TORA). Secure ad hoc networks have to meet five security requirements: confidentiality, integrity, authentication, non-repudiation and availability. The analyses of the secure versions of the proposed protocols are discussed with respect to the above security requirements.
329 citations
TL;DR: This paper proposes a framework of a 2-D CAC to accommodate various features of WiMAX networks and develops a utility- and fairness-constrained optimal revenue policy as well as its corresponding approximation algorithm.
Abstract: Worldwide interoperability for microwave access (WiMAX) is a promising technology for last-mile Internet access, particularly in the areas where wired infrastructures are not available. In a WiMAX network, call admission control (CAC) is deployed to effectively control different traffic loads and prevent the network from being overloaded. In this paper, we propose a framework of a 2-D CAC to accommodate various features of WiMAX networks. Specifically, we decompose the 2-D uplink and downlink WiMAX CAC problem into two independent 1-D CAC problems and formulate the 1-D CAC optimization, in which the demands of service providers and subscribers are jointly taken into account. To solve the optimization problem, we develop a utility- and fairness-constrained optimal revenue policy, as well as its corresponding approximation algorithm. Simulation results are presented to demonstrate the effectiveness of the proposed WiMAX CAC approach.
217 citations
TL;DR: Simulation results demonstrate that when cooperation takes place, users benefit from the proposed strategy in terms of utility, and those with longer distance to the AP should spend more bandwidth to cooperate with others.
Abstract: This paper proposes a cooperation strategy among rational nodes in a wireless cooperative relaying network as an effort to solve two basic problems, i.e., when to cooperate and how to cooperate. First, a symmetric system model comprising two users and an access point (AP) is presented. In this model, each user plays an equal role and acts as a source as well as a potential relay and has the right to decide the amount of bandwidth it should contribute for cooperation. Second, referring to the cooperative game theory, the above problems are formulated as a two-person bargaining problem. Then, a cooperation bandwidth allocation strategy based on the Nash bargaining solution is proposed, in which if a derived condition is satisfied, users will cooperatively work, and each will share a certain fraction of its bandwidth for relaying; otherwise, they will independently work. Simulation results demonstrate that when cooperation takes place, users benefit from the proposed strategy in terms of utility, and those with longer distance to the AP should spend more bandwidth to cooperate with others.
161 citations
TL;DR: A more accurate analytical expression of the PAPR distribution is derived with the help of Extreme Value Theory for Chi-squared-2 process in OFDM systems with unequal power distribution strategy.
Abstract: It has been widely known that one of the key design parameters in orthogonal frequency division multiplexing (OFDM) systems is the distribution of peak-to-average power ratio (PAPR). Recently some theoretical approaches to determine the PAPR distribution have been proposed based on the assumption that all subcarriers are allocated with equal power. However, this assumption may not be valid due to the following facts. First, in all realistic OFDM systems, usually only a subset: of subcarriers are used to carry information (active subcarriers) and the rest (inactive subcarriers) are set to zero. Second, due to the efficiency concerns transmission power should be allocated to active subcarriers. Third, power allocation may vary depending on different constellations used by different active subcarriers and their signal-to-noise-ratios. In this paper, we propose a general approach to identify PAPR distribution in OFDM systems. Specifically, a more accurate analytical expression of the PAPR distribution is derived with the help of Extreme Value Theory for Chi-squared-2 process in OFDM systems with unequal power distribution strategy. To validate the analytical results, extensive simulations have been conducted, showing a very good match between the identified PAPR distribution and that of real OFDM systems.
148 citations
TL;DR: This paper proposes a unified framework for distributed key management schemes in heterogeneous wireless sensor networks and shows that, even with a small number of heterogeneous nodes, the performance of a wireless sensor network can be improved substantially.
Abstract: Key management has become a challenging issue in the design and deployment of secure wireless sensor networks. A common assumption in most existing distributed key management schemes is that all sensor nodes have the same capability. However, recent research works have suggested that connectivity and lifetime of a sensor network can be substantially improved if some nodes are given greater power and transmission capability. Therefore, how to exploit those heterogeneity features in design of a good distributed key management scheme has become an important issue. This paper proposes a unified framework for distributed key management schemes in heterogeneous wireless sensor networks. Analytical models are developed to evaluate its performance in terms of connectivity, reliability, and resilience. Extensive simulation results show that, even with a small number of heterogeneous nodes, the performance of a wireless sensor network can be improved substantially. It is also shown that our analytical models can be used to accurately predict the performance of wireless sensor networks under varying conditions.
106 citations
TL;DR: A new double proportional fair (D-PF) algorithm is proposed for user pairing of the uplink V-MIMO systems, which uses the PF criterion to decide the first user, and a modified PF criterion is suggested to choose the pairing user.
Abstract: In this letter, we study the user pairing algorithms for uplink virtual multiple-input multiple-output (V-MIMO) systems, and propose a new double proportional fair (D-PF) algorithm for user pairing of the uplink V-MIMO systems. The proposed D-PF algorithm uses the PF criterion to decide the first user, and a modified PF criterion is suggested to choose the pairing user. Simulation results show that the proposed D- PF algorithm outperforms the conventional determinant formula (DF) algorithm in terms of both throughput and fairness performances. Moreover, if compared with the conventional single PF (S-PF) algorithm, the proposed D-PF algorithm achieves a fairly good trade-off between the throughput and fairness, being able to trade with 5% throughput loss for 15% fairness enhancement.
86 citations
TL;DR: Both theoretical analysis and simulation results show that an IGC-CDMA system is interference-resistant and capable to offer a high spectral efficiency if compared with the ones based on other spreading codes.
Abstract: Spreading code plays an extremely important role on the overall performance of a CDMA system. The correlation properties and available number of spreading codes determine the interference-resist capability as well as system capacity. In this paper, we analyze the characteristics and limitations of traditional and recently reported spreading codes. Based on the analysis, we propose a new code design approach which will be used to generate inter-group complementary (IGC) codes. The correlation functions of the IGC codes possess definite and bi-valued interference-free windows. In addition, a corresponding code assignment algorithm and spreading scheme will be introduced to take advantage of the desirable properties of the IGC codes for their applications in CDMA systems. Both theoretical analysis and simulation results show that an IGC-CDMA system is interference-resistant and capable to offer a high spectral efficiency if compared with the ones based on other spreading codes.
76 citations
TL;DR: In this article, it has been investigated both the unique merits and the challenging tasks of combining policy-based management philosophy with cognitive radio technologies.
Abstract: The regulatory agencies have been pushed by the increasing demand for wireless ubiquitous connectivity to be ever more aggressive in providing innovative ways to use spectra efficiently. Driven by these new opportunities, the future radio systems should look for the optimized architecture, circuit, and algorithm as a whole. In this article, it has been investigated both the unique merits and the challenging tasks of combining policy-based management philosophy with cognitive radio technologies. Some example analysis have also been discussed. It is highly expected that the appropriate combination of policy-based management and CR will lead future wireless communications.
68 citations
TL;DR: This paper addresses the issues on spreading code generation that is suitable for next-generation CDMA systems and concludes that implementation of an interference-free CDMA will not be possible unless using complementary codes, such as the POC codes.
Abstract: All currently available code-division multiple-access (CDMA) technologies used in second-generation and third-generation mobile cellular systems are interference limited and can be appropriately called first-generation CDMA, whereas next-generation CDMA should provide a nearly interference-free performance. This paper addresses the issues on spreading code generation that is suitable for next-generation CDMA systems. The real environment adaptation linearization (REAL) approach is proposed to generate perfectly orthogonal complementary (POC) codes characterized by multiple access interference (MAI)-free and multipath interference (MI)-free operation. The REAL approach takes into account almost all major impairing factors in real applications, such as multipath propagation, asynchronous transmission, random data signs, and burst traffic, such that a CDMA system using them can offer an interference-resist operation. Two important conclusions are drawn in this paper: First, implementation of an interference-free CDMA will not be possible unless using complementary codes, such as the POC codes. Second, to enable interference-free CDMA, the flock size of the signature codes should preferably be equal to the set size of the codes. A fast algorithm to generate supercomplementary codes (a subset of POC codes) is also presented, and their ideal orthogonality is explicitly proven.
49 citations
TL;DR: This work presents a new formal model for MANETs consisting of cognitive radio capable nodes that are willing to be moved (at a cost), and develops an effective decentralized algorithm for mobility planning, and powerful new Altering and fuzzy based techniques for both channel estimation and channel selection.
Abstract: Mission-oriented MANETs are characterized by implicit common group objectives which make inter-node cooperation both logical and feasible. We propose new techniques to leverage two optimizations for cognitive radio networks that are specific to such contexts: opportunistic channel selection and cooperative mobility. We present a new formal model for MANETs consisting of cognitive radio capable nodes that are willing to be moved (at a cost). We develop an effective decentralized algorithm for mobility planning, and powerful new Altering and fuzzy based techniques for both channel estimation and channel selection. Our experiments are compelling and demonstrate that the communications infrastructure-specifically, connection bit error rates-can be significantly improved by leveraging our proposed techniques. In addition, we find that these cooperative/opportunistic optimization spaces do not trade-off significantly with one another, and thus can be used simultaneously to build superior hybrid schemes. Our results have significant applications in high-performance mission-oriented MANETs, such as battlefield communications and domestic response & rescue missions.
47 citations
19 May 2008
TL;DR: Simulation results indicate that COM-MAC can achieve increased network throughput at the cost of a small control and energy overhead.
Abstract: A Wireless Multimedia Sensor Network (WMSN) is an emerging networking paradigm that allows retrieving video and audio streams, still images, and generic sensing data. Different from conventional wireless sensor networks, a WMSN requires higher network bandwidth and throughput to deliver multimedia contents effectively using energy-constrained devices. In this paper, we propose a clustered on-demand multi-channel MAC protocol (COM-MAQ) to support energy-efficient, high- throughput, and reliable data transmission in WMSNs. The operation of proposed protocol consists of three sessions: request session, scheduling session, and data transmission session. For COM-MAC to achieve high energy efficiency, first, a scheduled multi-channel medium access is used within each cluster so that cluster members can operate in a contention-free manner within both time and frequency domains to avoid collision, idle listening and overhearing. Second, to maximize the network throughput, a traffic-adaptive and QoS-aware scheduling algorithm is executed to dynamically allocate time slots and channels for sensor nodes based on the current data traffic information and QoS requirements. Finally, to enhance transmission reliability, a spectrum-aware ARQ is incorporated to better exploit the unused spectrum for a balance between the reliability and retransmission. Simulation results indicate that COM-MAC can achieve increased network throughput at the cost of a small control and energy overhead.
TL;DR: An analytical model is proposed and simulation experiments are conducted to investigate the performance of the CDC-series schemes with the RR and Greedy algorithms in terms of the acceptance rate of both external and internal packet data.
Abstract: The IEEE 802.16 Standard defines the mesh mode for media access control for external and internal packet transmission. In the IEEE 802.16 mesh mode, the allocation of minislots is handled by centralized scheduling and distributed scheduling, which are independently exercised. This paper proposes the Combined Distributed and Centralized (CDC) and Combined Distributed and Centralized with Queue capability (CDCQ) schemes to combine distributed scheduling and centralized scheduling so that the minislot allocation can be more flexible and the utilization is increased. Two scheduling algorithms, i.e., the Round-Robin (RR) and Greedy algorithms, are used as the baseline algorithms for centralized scheduling. This paper proposes an analytical model and conducts simulation experiments to investigate the performance of the CDC-series schemes with the RR and Greedy algorithms in terms of the acceptance rate of both external and internal packet data. Our study indicates that the CDC-series schemes outperform the scheme proposed in the IEEE standard.
TL;DR: New energy-aware techniques to lower the packet-level error rates of application-layer connections in wireless ad hoc networks are presented and the relationship between packet error rate, the extent of duplication and the path lengths are described.
Abstract: In this paper, we present new energy-aware techniques to lower the packet-level error rates of application-layer connections in wireless ad hoc networks. We consider a model in which each connection is allocated a fixed power budget, and ask: Is it better to use this power budget to send many duplicate packets (at lower power) or fewer packets (at high power)? We consider a scheme in which each application-layer connection is implemented at the physical level by an overlay network consisting of multiple parallel multi-hop paths. Data packets submitted at the connection source are checksummed and replicated. The destination delivers the first error-free copy of each packet, in order, dropping packets that are corrupt or duplicate. We compare our scheme with the traditional scheme in which the source transmits precisely one packet to the destination along a single minimum-hop path. We show that even when both schemes are constrained by identical power consumption bounds, our scheme can use duplication to attain significantly lower packet-level error rates in many common situations. We describe the relationship between packet error rate, the extent of duplication and the path lengths and show that the qualitative nature of the relationships change significantly, depending on available power budget.
08 Dec 2008
TL;DR: A new cooperative mobility model is presented, developing a cost- benefit framework which enables the impact of cooperation in MANETs where nodes are, to varying extents, willing to move for the common good, and the design of CoopSim, a platform for conducting simulation experiments to evaluate theimpact of parameter, policy and algorithm choices on any system based on the proposed model.
Abstract: Modern mobile ad-hoc networks (MANETs) frequently consist of nodes which exhibit a wide range of autonomy needs. This is particularly true in the settings where MANETs are most compelling, i.e. battlefield, response & rescue, and contexts requiring rapid deployment of mobile users. The time-critical nature of the underlying circumstances frequently requires deployment of both manned and unmanned nodes, and a coordination structure which provides prioritized tasking to them. Unlike consumer MANETs, these settings bring with them a common group purpose, making inter-node cooperation plausible. In this paper, we focus on how cooperation can improve MANET communications. We begin by taxonomizing all prior approaches and noting that no existing approach adequately captures networks where nodes exhibit a wide range of autonomy with respect to their mobility. To this end we present a new cooperative mobility model, developing a cost- benefit framework which enables us to explore the impact of cooperation in MANETs where nodes are, to varying extents, willing to move for the common good. In the second half of the paper, we describe the design of CoopSim, a platform for conducting simulation experiments to evaluate the impact of parameter, policy and algorithm choices on any system based on the proposed model. Finally, we present a small but illustrative case study and use the experimental evidence derived from it to give an initial evaluation of the merits of the proposed model and the efficacy of the CoopSim software.