scispace - formally typeset
Search or ask a question

Showing papers in "International Journal of Communication Systems in 2010"


Journal ArticleDOI
TL;DR: The paper surveys some of the most important work on Internet connectivity for wireless sensor networks, pointing to hardware and software resources to deploy an IP-based wireless sensor network, while motivating the use of node stack IP- based solutions, namely 6LoWPAN.
Abstract: Wireless sensor networks (WSNs) are composed of thousands of smart-sensing nodes, which capture environment data for a sink node. Such networks present new challenges when compared with traditional computer networks, namely in terms of smart node hardware constraints and very limited energy resources. Ubiquitous computing can benefit from WSNs from the perspective that sensed data can be used instead of the user without explicit intervention, turning ubiquitous computing into a reality. Internet connectivity in WSNs is highly desirable, featuring sensing services at a global scale. Two main approaches are considered: proxy based or sensor node stack based. This second approach turns sensors into data-producing hosts also known as ‘The Internet of Things’. For years, the TCP-IP (Transmission Control Protocol-Internet Protocol) suite was considered inappropriate for WSNs, mainly due to the inherent complexity and protocol overhead for such limited hardware. However, recent studies made connecting WSNs to the Internet possible, namely using sensor node stack based approaches, enabling integration into the future Internet. This paper surveys the current state-of-the-art on the connection of WSNs to the Internet, presents related achievements, and provides insights on how to develop IP-based communication solutions for WSNs today. Copyright © 2010 John Wiley & Sons, Ltd. Wireless sensor networks and Internet connectivity: Born on military applications, wireless sensor networks were not developed with Internet connectivity concerns. However, the added benefits of remote management and monitoring led to two basic approaches: proxy-based and node stack IP-based. The paper surveys some of the most important work on Internet connectivity for wireless sensor networks, pointing to hardware and software resources to deploy an IP-based wireless sensor network, while motivating the use of node stack IP-based solutions, namely 6LoWPAN. Copyright © 2010 John Wiley & Sons, Ltd.

128 citations


Journal ArticleDOI
TL;DR: The objective in this paper is to analyze the security issues of the main recent developments and architectures of cognitive radio networks, and present vulnerabilities inherent to those systems, identify novel types of abuse, classify attacks, and propose security solutions to mitigate such threats.
Abstract: Cognitive radio is a promising technology aiming to improve the utilization of the radio electromagnetic spectrum. A cognitive radio device uses general purpose computer processors that run radio applications software to perform signal processing. The use of this software enables the device to sense and understand its environment and actively change its mode of operation based on its observations. Unfortunately, this solution entails new security challenges. Our objective in this paper is to analyze the security issues of the main recent developments and architectures of cognitive radio networks. We present vulnerabilities inherent to those systems, identify novel types of abuse, classify attacks, and analyze their impact on the operation of cognitive radio-based systems. Moreover, we discuss and propose security solutions to mitigate such threats. Copyright © 2010 John Wiley & Sons, Ltd. Cognitive radio emerges as a promising technology to deal with the scarcity of radio electromagnetic spectrum. Cognitive radio devices run the radio applications software by means of which they are able to sense and understand their environment and change their mode of operation according to their observations. In this paper we present an analysis of the vulnerabilities inherent to these systems, identify the potential threats to cognitive radio networks and propose a set of countermeasures to mitigate them. Copyright © 2010 John Wiley & Sons, Ltd.

116 citations


Journal ArticleDOI
TL;DR: It is demonstrated that both of the proposed schemes cannot achieve the security requirement for user anonymity and resist an impersonation attack yet, and a new dynamic ID authentication scheme is proposed to overcome the above security weaknesses.
Abstract: Recently, Yoon et al. and Wang et al. independently proposed a dynamic ID authentication scheme and claimed that their schemes can withstand the risk of ID-theft, and several attacks. In this paper, we first demonstrate that both of the proposed schemes cannot achieve the security requirement for user anonymity and resist an impersonation attack yet. Then, we shall propose a new dynamic ID authentication scheme to overcome the above security weaknesses. We formally analyzed our proposed scheme with the BAN-logic and shown that it can withstand the several possible attacks. Copyright © 2010 John Wiley & Sons, Ltd.

80 citations


Journal IssueDOI
TL;DR: Two user authentication protocols are proposed that are variations of a recent strong-password-based solution that use one-way hash functions and XOR operations to achieve lower computational and communication overheads and provide mutual authentication and user anonymity.
Abstract: Owing to the ubiquitous nature, ease of deployment, and wide range of potential applications, wireless sensor networks (WSNs) have received a lot of attention recently. WSNs can be deployed in unattended environments; however, they have many challenges. It should be guaranteed that not only illegitimate users cannot login and access data in the network but also user privacy should be maintained. Since sensor nodes have limited computation power, storage, and energy, it is desirable for the authentication protocol to be simple and secure. In this paper, we propose two user authentication protocols that are variations of a recent strong-password-based solution. It uses one-way hash functions and XOR operations to achieve lower computational and communication overheads. We have analyzed the performance of both the proposed authentication schemes in terms of various metrics. We have also provided security evaluation of the proposed protocols. Comparing with the previous schemes, our proposed schemes are more robust and provide better security. Copyright © 2009 John Wiley & Sons, Ltd. This paper proposes two user authentication protocols for ubiquitous wireless sensor networks that are variations of a recent strong-password-based solution. The main aims of these schemes are to provide mutual authentication and user anonymity. They use one-way hash functions and XOR operations to achieve lower computational and communication overheads. In this paper, security evaluation of the proposed protocols was conducted. Comparing with the existing representative schemes, the proposed schemes are more robust and provide better security. Copyright © 2009 John Wiley & Sons, Ltd.

60 citations


Journal IssueDOI
TL;DR: An energy-efficient handover scheme with geographic mobility awareness (HGMA), which considers the historical handover patterns of mobile devices and can eliminate unnecessary handovers, reduce the number of network scanning, and avoid switching network interfaces too frequently is proposed.
Abstract: To provide wireless Internet access, WiFi networks have been deployed in many regions such as buildings and campuses. However, WiFi networks are still insufficient to support ubiquitous wireless service due to their narrow coverage. One possibility to resolve this deficiency is to integrate WiFi networks with the wide-range WiMAX networks. Under such an integrated WiMAX and WiFi network, how to conduct energy-efficient handovers is a critical issue. In this paper, we propose a handover scheme with geographic mobility awareness (HGMA), which considers the historical handover patterns of mobile devices. HGMA can conserve the energy of handovering devices from three aspects. First, it prevents mobile devices from triggering unnecessary handovers according to their received signal strength and moving speeds. Second, it contains a handover candidate selection method for mobile devices to intelligently select a subset of WiFi access points or WiMAX relay stations to be scanned. Therefore, mobile devices can reduce their network scanning and thus save their energy. Third, HGMA prefers mobile devices staying in their original WiMAX or WiFi networks. This can prevent mobile devices from consuming too much energy on interface switching. In addition, HGMA prefers the low-tier WiFi network over the WiMAX network and guarantees the bandwidth requirements of handovering devices. Simulation results show that HGMA can save about 59– 80p of energy consumption of a handover operation, make mobile devices to associate with WiFi networks with 16–62p more probabilities, and increase about 20–61p of QoS satisfaction ratio to handovering devices. Copyright © 2009 John Wiley & Sons, Ltd. In this paper, we identify the GM (Geographic Mobility) feature of mobile devices in an integrated WiMAX and WiFi network. By adopting the GM feature, we propose an energy-efficient handover scheme with geographic mobility awareness (HGMA). This scheme can eliminate unnecessary handovers, reduce the number of network scanning, and avoid switching network interfaces too frequently. In addition, HGMA prefers the low-tier WiFi network over the WiMax network, and guarantees the bandwidth requirements of handovering mobile devies. Copyright © 2009 John Wiley & Sons, Ltd.

44 citations


Journal ArticleDOI
TL;DR: A novel and one‐round distributed clustering scheme based on spatial correlation between sensor nodes, and a novel light‐weight compressing algorithm to effectively save the energy at each transmission from sensors to the base station based on temporal correlation of the sensed data are proposed.
Abstract: The development of large-scale wireless sensor networks engenders many challenging problems. Examples of such problems include how to dynamically organize the sensor nodes into clusters and how to compress and route the sensing information to a remote base station. Sensed data in sensor systems reflect the spatial and temporal correlations of physical attributes existing intrinsically in the environment. Noteworthy efficient clustering schemes and data compressing techniques proposed recently leverage the spatiotemporal correlation. These include the framework of Liu et al. and schemes introduced by Gedik et al. However, the previous clustering schemes are based on an impractical assumption of a single-hop network architecture and their cluster construction communication cost is relatively expensive. On the other hand, the computational overhead of recent compressing techniques (e.g. the work of Liu et al. and Douglas et al.) is quite significant; therefore, it is hard for sensor nodes with limited processing capability to perform these techniques. With such motivation, we propose a novel and one-round distributed clustering scheme based on spatial correlation between sensor nodes, and propose a novel light-weight compressing algorithm to effectively save the energy at each transmission from sensors to the base station based on temporal correlation of the sensed data. Besides, the aim of the proposed clustering scheme is not only to group the nodes with the highest similarity in observations into the same cluster, but also to construct and maintain a dynamic backbone for efficient data collection in the networks (with the consideration of sink mobility). Computer simulation shows that the proposed schemes significantly reduce the overall number of communications in the cluster construction phase and the energy consumed in each transmission, while maintaining a low variance between the readings of sensor nodes in the same clusters and high reliability of the compressed data. Copyright © 2010 John Wiley & Sons, Ltd.

39 citations


Journal IssueDOI
TL;DR: A hard decision combining-based cooperative spectrum sensing scheme in the presence of a feedback error caused by imperfect channel condition is proposed, which can maximize the detection probability while guaranteeing that the desired false alarm probability is maintained.
Abstract: The primary object of cognitive radio is to increase spectral efficiency, while causing limited interference to primary users who are using the spectrum. Hence, an essential part of cognitive radio is a spectrum sensing that determines whether a particular spectrum is occupied or not by a primary user. However, the sensing decision of a local secondary user alone may not be reliable enough due to shadowing and multipath fading of wireless channels. Recently, cooperative spectrum sensing has emerged as a remedy to the problems of local sensing. To sense the spectrum in a cooperative manner, secondary users report their local decisions to a cognitive base station through a feedback channel that is subject to fading and shadowing. Therefore, though the local sensing result is obtained accurately, it might not be suitable for making a cooperative decision due to feedback error. To alleviate this problem, we propose a hard decision combining-based cooperative spectrum sensing scheme in the presence of a feedback error caused by imperfect channel condition. In the proposed scheme, only the most favorable secondary users, those whose reporting channel conditions are peak, are allowed for cooperation. Through the proposed scheme, we can maximize the detection probability while guaranteeing that the desired false alarm probability is maintained. The simulation results show that the proposed scheme provides better spectrum sensing performance than the conventional scheme. Copyright © 2010 John Wiley & Sons, Ltd. In this paper, we propose a cooperative spectrum sensing scheme in the presence of reporting errors in cognitive radio networks. Accurate local sensing results may not directly be applied to cooperative sensing due to reporting errors. We consider the cooperative spectrum sensing that utilizes local sensing results in good reporting channel condition. Finally, simulation results show that the proposed scheme can maximize the detection probability while guaranteeing the desired false alarm probability. Copyright © 2010 John Wiley & Sons, Ltd.

32 citations


Journal ArticleDOI
TL;DR: A comprehensive study on the performance of RF communication to-from a human body and low-power MAC protocols for a WBAN including a case study of IEEE 802.15.4, PB-TDMA, and SMAC protocols.
Abstract: Recent advances in micro-electro-mechanical systems, wireless communication, low-power intelligent sensors, and semiconductor technologies have allowed the realization of a wireless body area network (WBAN). A WBAN provides unobtrusive health monitoring for a long period of time with real-time updates to the physician. It is widely used for ubiquitous health care, entertainment, and military applications. The implantable and wearable medical devices have several critical requirements such as power consumption, data rate, size, and low-power medium access control (MAC) protocols. This article consists of two parts: body implant communication, which is concerned with the communication to and from a human body using radio frequency (RF) technology, and WBAN MAC protocols, which presents several low-power MAC protocols for a WBAN with useful guidelines including a case study of IEEE 802.15.4, PB-TDMA, and SMAC protocols. In body implant communication, the in-body RF performance is affected considerably by the implant's depth and different polarization combinations inside the human body as well as by the muscle and fat. We observe best performance at a depth of 3 to 5 cm and not close to the human skin. Furthermore, the study of low-power MAC protocols highlights the most important aspects of developing a novel low-power and reliable MAC protocol for a WBAN. Copyright © 2010 John Wiley & Sons, Ltd. This paper presents a comprehensive study on the performance of RF communication to-from a human body and low-power MAC protocols for a WBAN including a case study of IEEE 802.15.4, PB-TDMA, and SMAC protocols. It can be seen that in-body RF performance is considerably affected by the implant's depth and different polarization combinations. In addition, the study of low-power MAC protocols highlights the most important aspects of developing a novel and reliable MAC protocol for a WBAN. Copyright © 2010 John Wiley & Sons, Ltd.

31 citations


Journal IssueDOI
TL;DR: In this article, an inter-domain handover scheme for Proxy Mobile IPv6 (PMIPv6) with a new network entity, called intermediate-mobile access gateway (iMAG), is proposed.
Abstract: Current IP-level mobility management protocols are unable to satisfy the stringent handover latency requirements for supporting real-time multimedia services between different domains in a high-speed vehicular environment. This paper proposes an inter-domain handover scheme for Proxy Mobile IPv6 (PMIPv6) with a new network entity, called intermediate-mobile access gateway (iMAG). The iMAG is located between the home and the foreign domains and is connected to both domains. The proposed scheme is a proactive handover approach that performs the inter-domain L3 handover in advance before the inter-domain L2 handover while the Mobile Node (MN) is still connected to the iMAG in the home domain. Therefore, the proposed scheme enables the inter-domain handover latency to reduce as low as the intra-domain handover latency. Numerical analysis and simulation results demonstrate that the proposed scheme is able to support seamless service continuity in inter-domain handovers. Copyright © 2009 John Wiley & Sons, Ltd. This paper proposes an inter-domain handover scheme for Proxy Mobile IPv6 (PMIPv6) with a new network entity, called intermediate-mobile access gateway (iMAG) which is connected to both the home and the foreign domains. The proposed scheme is a proactive handover approach that performs the inter-domain L3 handover in advance before the inter-domain L2 handover while the Mobile Node (MN) is still connected to the iMAG in the home domain. Therefore, the proposed scheme enables the inter-domain handover latency to reduce as low as the intra-domain handover latency. Copyright © 2009 John Wiley & Sons, Ltd.

28 citations


Journal IssueDOI
TL;DR: Closed-form expressions for probability density function and cumulative distribution function of the signal-to-interference ratio at the output of the selection combining receiver present main contribution of this paper.
Abstract: In this paper, the performance of L-branch selection combining receiver over correlated Weibull fading channels in the presence of correlated Weibull-distributed cochannel interference is analyzed. Closed-form expressions for probability density function and cumulative distribution function of the signal-to-interference ratio at the output of the selection combining receiver present main contribution of this paper. Numerical results are also presented to show the effects of various parameters as the fading severity, correlation and number of branches on outage probability. Copyright © 2009 John Wiley & Sons, Ltd. This paper analyzes the outage performance of L-branch SC receiver over correlated Weibull fading channels in the presence of correlated Weibull-distributed co-channel interference. In order to carry out this analysis, closed-form expression for the outage probability of considered system is derived. Presented numerical results show the effects of various parameters as the fading severity, correlation and number of branch on the outage probability. Copyright © 2009 John Wiley & Sons, Ltd.

27 citations


Journal ArticleDOI
TL;DR: The channel capacity of multiple-input multiple-output ultra-wideband (MIMO-UWB) systems with single co-channel interference (CCI) is calculated using a ray-tracing approach, and the channel frequency response is further used to calculate the corresponding channel capacity.
Abstract: In this paper, the channel capacity of multiple-input multiple-output ultra-wideband (MIMO-UWB) systems with single co-channel interference (CCI) is calculated. A ray-tracing approach is used to calculate the wanted channel frequency response, and the channel frequency response is further used to calculate the corresponding channel capacity. By the ray-tracing approach, two different antenna arrays are applied to our simulation to observe whether MIMO can reduce CCI. Also the effects caused by the two antenna arrays for the desired system and CCI are quantified. Copyright © 2010 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: Exact expressions for outage probability and symbol error rate are presented for a decode-and-forward cooperative network with partial relay selection for an independent but not identically distributed Nakagami-m fading environment.
Abstract: Exact expressions for outage probability and symbol error rate are presented for a decode-and-forward cooperative network with partial relay selection. An independent but not identically distributed Nakagami-m fading environment is considered. Numerical and simulated results show the validity of the analytical results. Copyright © 2010 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: The real time evaluation of the layered-based architecture and the scheduling middleware equipped with the MICA2 sensors-MTS310 sensor boards shows that the overall performance of the system can be significantly affected and verifies the validity of the proposed scheme.
Abstract: Wireless infrastructureless networks demand high resource availability with respect to the progressively decreasing energy consumption. A variety of new applications with different service requirements demand fairness to the service provision and classification, and reliability in an end-to-end manner. High-priority packets are delivered within a hard time delay bound whereas improper power management in wireless networks can substantially degrade the throughput and increase the overall energy consumed. In this work a new scheme is being proposed and evaluated in real time using a state-based layered oriented architecture for energy conservation (EC). The proposed scheme uses the node's self-tuning scheme, where each node is assigned with a dissimilar sleep and wake time, based on traffic that is destined for each node. This approach is based on stream's characteristics with respect to different caching behavioral and storage-capacity characteristics, and considers a model concerning the layered connectivity characteristics for enabling the EC mechanism. EC characteristics are modeled and through the designed tiered architecture the estimated metrics of the scheme can be bounded and tuned into certain regulated values. The real-time evaluation results were extracted by using dynamically moving and statically located sensor nodes. A performance comparison is done with respect to different data traffic priority classifications following a real-time asymmetrical transmission channel. Results have shown the scheme's efficiency in conserving energy while the topology configuration changes with time. Copyright © 2009 John Wiley & Sons, Ltd. The proposed mechanism in the paper enables dissimilar schedules according to the traffic patterns using pareto distribution and considers channels' data rate measures and throughput measures associated with the interfaces' schedules. The real time evaluation using the layered-based architecture and the scheduling middleware equipped with the MICA2 sensors-MTS310 sensor boards shows that the overall performance of the system can be significantly affected and verifies the validity of the proposed scheme. Copyright © 2009 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: The network lifetime of a rectangular network model that achieves energy efficiency by optimizing the node radio range based on the geographical adaptive fidelity (GAF) topology management protocol is evaluated to achieve grid‐lifetime balance among all grids to optimize the entire network lifetime.
Abstract: Ad hoc wireless network nodes are typically battery-powered, therefore energy limit is one of the critical constraints of ad hoc wireless networks' development. This paper evaluates the network lifetime of a rectangular network model that achieves energy efficiency by optimizing the node radio range based on the geographical adaptive fidelity (GAF) topology management protocol (Proceedings of ACMMobil'01, July 2001; 70–84). We derive the optimal transmission range of nodes and analyze both static and dynamic traffic scenarios in both equal-grid and adjustable-grid rectangular GAF models, where the results show that the adjustable-grid model saves 78.1% energy in comparison with the minimum energy consumption of equal-grid model. The impact of node density on both equal-grid and adjustable-grid models is investigated to achieve grid-lifetime balance among all grids to optimize the entire network lifetime. The lifetime estimation results show that without node density control the adjustable-grid model prolongs the entire network lifetime by a factor of 4.2 compared with the equal-grid model. Furthermore, the adjustable-grid model with node density control is able to prolong the entire network lifetime by a factor of 6 compared with the equal-grid model. Copyright © 2010 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: An extensible RFID management framework called SIP-based RFIDs management system (SRMS), which can support various RFID applications and has advantages of service extensibility and reusability.
Abstract: Radio frequency identification (RFID) is an enabling technology for a variety of applications in next-generation network (NGN). Although several RFID management frameworks are proposed in the literature, they have limitations in terms of service extension. In this paper, we propose an extensible RFID management framework called SIP-based RFID management system (SRMS), which can support various RFID applications. SRMS employs session initiation protocol (SIP), which is an Internet standard protocol adopted in NGN for session management and mobility support. SRMS enhances the existing SIP architecture by introducing a surrogate user agent (SUA) and an SRMS name server (SNS). The SUA performs SIP signaling on behalf of RFID tags with limited capabilities, whereas the SNS provides name resolution services. To illustrate the extensibility of SRMS, we demonstrate two representative application scenarios. Compared with the existing RFID management frameworks, SRMS has advantages of service extensibility and reusability. Copyright © 2009 John Wiley & Sons, Ltd. A preliminary version of this paper was presented at the IEEE International Conference on Pervasive Services (ICPS) 2007, Istanbul, Turkey, July 2007. In this paper, we propose an extensible RFID management framework called SIP-based RFID management system (SRMS), which can support various RFID applications. To illustrate the extensibility of SRMS, we demonstrate two representative application scenarios: location management services and mobile RFID services. Compared with the existing RFID management frameworks, SRMS has advantages of service extensibility and reusability. Copyright © 2009 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: A power-efficient node placement scheme (PENPS) in linear wireless multimedia sensor networks, which can minimize the average energy consumption per node and maximize the network lifetime is investigated and developed.
Abstract: A next-generation network (NGN) is an advanced network that exploits multiple broadband and QoS-enabled transport technologies to provide telecommunication services. The principles and requirements of convergence of wireless sensor networks are likely to deliver all the desired benefits of NGN and should be carefully studied. In this paper, we focus on the power consumption topic, which is a fundamental concern in wireless multimedia sensor networks (WMSNs). Node placement in WMSNs has considerable impact on network lifetime. In this paper, we have investigated and developed a power-efficient node placement scheme (PENPS) in linear WMSNs, which can minimize the average energy consumption per node and maximize the network lifetime. The analysis of PENPS and the comparison of performance with the equal-spaced placement scheme (EPS) show that PENPS scheme can significantly decrease the average energy consumption per node, which can prolong the lifetime of sensor nodes and sensor networks effectively. Copyright © 2010 John Wiley & Sons, Ltd. This paper investigates and develops a power-efficient node placement scheme (PENPS) in linear wireless multimedia sensor networks, which can minimize the average energy consumption per node and maximize the network lifetime. The analysis of PENPS and the comparison of performance with the equal-spaced placement scheme (EPS) show that PENPS scheme can significantly decrease the average energy consumption per node, which can prolong the lifetime of sensor nodes and sensor networks effectively. Copyright © 2010 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: Simulation results show that the Virtual Router approach can achieve several times better performance than the traditional approach based on physical routers (i.e. relay nodes) in handling high mobility.
Abstract: Next-generation ad hoc networks need to be able to handle high mobility in order to support a wide range of emerging applications such as vehicular networks. Maintaining communication links of an established communication path that extends between source and destination nodes is a significant challenge in mobile ad hoc networks due to the movement of the mobile nodes. In particular, such communication links are often broken under a high mobility environment. Although a new communication route can be established when a break in the communication path occurs, repeatedly reestablishing new routes incurs delay and substantial overhead. To address this limitation, we introduce the Virtual Router abstraction in this paper. A virtual router is a dynamically created logical router that is associated with a particular geographical area. Its routing functionality is provided by the physical nodes (i.e. mobile devices) currently within the geographical region served by the virtual router. These physical nodes take turns in forwarding data packets for the virtual router. In this environment, data packets are transmitted from a source node to a destination node over a series of virtual routers. Since virtual routers do not move, this scheme is much less susceptible to node mobility. We give simulation results to demonstrate the effectiveness of this technique in handling high mobility. They show that the Virtual Router approach can achieve several times better performance than the traditional approach based on physical routers (i.e. relay nodes). Copyright © 2009 John Wiley & Sons, Ltd. In this paper, we introduce the Virtual Router abstraction to maintain communication links in a high mobility environment. A virtual router is a dynamically-created logical router that is associated with a particular geographical area and its routing functionality is provided by the physical nodes (i.e. mobile devices) currently within the geographical region served by the virtual router. In this environment, data packets are transmitted from a source node to a destination node over a series of virtual routers. Copyright © 2009 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: CDMA is utilized as the underlying multiple access technique, due to its resilience to multi-path and Doppler's effects prevalent in underwater environments, and a head-to-head comparison with other protocols is provided through extensive simulations focusing on the performance in terms of latency, throughput, and energy consumption.
Abstract: As over 70p of the earth's surface is covered by water, it is desirable to deploy underwater sensor networks (UWSNs) to support oceanic research. UWSNs use acoustic waves and are characterized by long and variable propagation delays, intermittent connectivity, limited bandwidth and low bit rates. Energy savings have always been the primary concern in wireless sensor network protocols; however, there are applications where the latency and throughput are prioritized over energy efficiency and are so significant that the application would not be able to satisfy its requirements without them. Although existing duty-cycle MAC protocols are power efficient, they introduce significant end-to-end delivery latency, provide poor throughput and are not suitable for the challenging environment of a UWSN. In this paper, we utilize CDMA as the underlying multiple access technique, due to its resilience to multi-path and Doppler's effects prevalent in underwater environments. We propose UW-MAC, a CDMA-based power-controlled medium access protocol that uses both transmitter-based and receiver-based CDMA inside a formed cluster, and uses a TDMA schedule to make the cluster heads communicate with the base station. Our MAC algorithm targets the latency and throughput needs in addition to its ability to increase the overall network lifetime. We discuss the design of UW-MAC, and provide a head-to-head comparison with other protocols through extensive simulations focusing on the performance in terms of latency, throughput, and energy consumption. Copyright © 2009 John Wiley & Sons, Ltd. Under water sensor networks (UWSNs) use acoustic waves and are characterized by long and variable propagation delays, intermittent connectivity, limited bandwidth and low bit rates. Although existing duty-cycle MAC protocols are power efficient, they introduce significant end-to-end delivery latency, provide poor throughput and are not suitable for the challenging environment of an UWSN. In this paper, we propose UW-MAC, a CDMA-based power controlled medium access protocol that uses both transmitter-based and receiver-based CDMA inside a formed cluster, and uses a TDMA schedule to make the cluster heads communicate with the base station. Our MAC algorithm targets the latency and throughput needs in addition to its ability to increase the overall network lifetime. Copyright © 2009 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: An IPTV service architecture for the IMS that combines a centralized control layer and a distributed, P2P-like, media layer that relies on the I MS devices or peers located in the customers' premises to act as streaming forwarding nodes is proposed and foster peers that have inactive multimedia sessions are introduced.
Abstract: During these last years the Internet Protocol Television (IPTV) service and the different peer-to-peer (P2P) technologies have generated an increasing interest for the developers and the research community that find in them the solution to deal with the scalability problem of media streaming and reducing costs at the same time. However, despite of the benefits obtained in Internet-based applications and the growing deployment of commercial IPTV systems, there has been a little effort in combining them both. With the advent of the next-generation-network platforms such as the IP Multimedia Subsystem (IMS), which advocates for an open and inter-operable service infrastructure, P2P emerges as a possible solution in situations where the traditional streaming mechanisms are not possible or not economically feasible. In this paper, we propose an IPTV service architecture for the IMS that combines a centralized control layer and a distributed, P2P-like, media layer that relies on the IMS devices or peers located in the customers' premises to act as streaming forwarding nodes. We extend the existing IMS IPTV standardization work that has already been done in 3GPP and ETSI TISPAN in order to require a minimum number of architectural changes. The objective is to obtain a system with a similar performance to the one in currently deployed systems and with the flexibility of P2P. One of the main challenges is to achieve comparable response times to user actions such as changing and tuning into channels, as well as providing a fast recovery mechanism when streaming nodes leave. To accomplish this we introduce the idea of foster peers as peers having inactive multimedia sessions and reserved resources. These peers are on stand-by until their functionality is required and at that moment, they are able to accept downstream peers at short notice for events requiring urgent treatment like channel changing and recovery. Copyright © 2009 John Wiley & Sons, Ltd. This paper proposes an IPTV service architecture for the IMS combining centralized control and peer-to-peer-like streaming, where the UEs from the customers' premises act as forwarding nodes. In order to achieve response times comparable to currently deployed systems, we introduce the idea of foster peers that have inactive multimedia sessions. These peers are on stand-by until their functionality is required, at which moment they can accept downstream peers for events requiring urgent treatment like channel change and recovery. Copyright © 2009 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this paper, the authors discuss the adaptation of multiple description coding (MDC) for the loopback buffering mechanism to address the issue of peer heterogeneity on content distribution network-peer to peer (CDN-P2P) video-on-demand systems.
Abstract: Owing to the wide deployment of broadband networks, information can now be rapidly disseminated all over the world. Only the content of static texts and pictures has not yet met users' demands. Along with the rapid advance of computer-related technologies, how to efficiently provide multimedia content for a large number of heterogeneous users on the Internet, especially videos, has become a noticeable issue. In this paper, we discuss the adaptation of multiple description coding (MDC) for the loopback buffering mechanism to address the issue of peer heterogeneity on content distribution network–peer to peer (CDN-P2P) video-on-demand systems. Three description selection policies, Ordered, Round-Robin, and Open-Loop-First (OLF), are studied. In addition, we propose the intra-description recovery and inter-description recovery to deal with failed peers. The simulation results show that the OLF with loopback-MDC can significantly reduce the amount of uploading bandwidth of a proxy on CDN-P2P video-on-demand systems, and the inter-description recovery, sewing, can further effectively recover missing blocks and restore the continuity of a breaking sharing loop among peers. Copyright © 2009 John Wiley & Sons, Ltd. In this paper, we discuss the adaptation of multiple description coding for the loopback buffering mechanism to address the issue of peer heterogeneity on CDN-P2P video-on-demand systems. In addition, we also proposed the intra-description recovery and inter-description recovery to deal with failed peers. The simulation results show that the Open-Loop-First algorithm can significantly reduce the amount of uploading bandwidth of a proxy on CDN-P2P video-on-demand systems, and the inter-description recovery can further effectively recover missing blocks and restore the continuity of a breaking sharing loop among peers. Copyright © 2009 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: A ZigBee-compatible adaptive joining mechanism with connection shifting schemes to improve the connectivity of ZigBee networks, allowing them to operate at the expected efficiency.
Abstract: Wireless sensor networks (WSNs) are well suited to many applications, including environment surveillance and target tracking. ZigBee is an IEEE 802.15.4-based standard that is considered suitable for WSNs. The functional operations of a ZigBee network rely on self-organized network connections and the proper deployment of sensor devices. However, the devices comprising a ZigBee network may become isolated from the network after the joining phase due to the configuration constraints of the ZigBee standard. This means that some deployed devices cannot join the network even though they can communicate with other joined nodes. These isolated devices reduce the efficiency of network operation and increase deployment costs. This paper proposes a ZigBee-compatible adaptive joining mechanism with connection shifting schemes to improve the connectivity of ZigBee networks, allowing them to operate at the expected efficiency. Simulation results show that the proposed mechanism significantly improves the join ratio of deployed sensor devices in ZigBee WSNs. Copyright © 2009 John Wiley & Sons, Ltd. The functional operations of a ZigBee network rely on self-organized network connections and the proper deployment of sensor devices. However, the devices comprising a ZigBee network may become isolated from the network after the joining phase due to the configuration constraints of the ZigBee standard. This paper proposes a ZigBee-compatible adaptive joining mechanism to improve the connectivity of ZigBee networks. Simulation results show that the proposed mechanism significantly improves the join ratio of deployed sensor devices in ZigBee WSNs. Copyright © 2009 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: A new technique called Smart Caching is introduced, which is able to mitigate variations in the performance of wireless networks for non-real-time and non-interactive services, even in the case of patchy wireless broadband network coverage and intermittent connectivity.
Abstract: Future mobile radio networks will aim at achieving ‘broadband access for all’, anywhere. The performance of a radio network vitally depends on the characteristics of the transmission path between the user terminal and the access point and the degree of network coverage. In urban areas, full broadband radio coverage is difficult to provide, causing a high variation in the link quality and making broadband services hard to realize. In rural regions, massive deployment costs prevent a full broadband coverage. Most of the time users have to settle for UMTS-like wide area networks. For mobile users accessing services, such as video streaming, which require continuous broadband connectivity, it virtually results in intermittent network connectivity. The frequent disruption of the broadband link and its replacement with no or only low-performance connections is a problem that should be addressed. This article introduces a new technique called Smart Caching (SC), which is able to mitigate variations in the network performance so that non-real-time and non-interactive services' quality is substantially improved. SC supports pre-fetching from a server and buffering data at the edge of the core network, in the so-called Smart Cache. It transmits data with extremely high speed to be buffered in the mobile terminal when it is in the service range of an access point. This allows for the provisioning of data-intensive services even in the case of patchy wireless broadband network coverage and intermittent connectivity. The performance of the SC service is evaluated with two different sophisticated queuing models, both based on the Markov arrival process. The benefit of the new technique is discussed and dimensioning issues are outlined. Furthermore, a comparison with legacy network setups is given. Copyright © 2009 John Wiley & Sons, Ltd. The article introduces a new technique called Smart Caching, which is able to mitigate variations in the performance of wireless networks for non-real-time and non-interactive services. Smart Caching supports pre-fetching from a server, buffering data at the edge of the core network, and fast data transfer in periods of good link conditions. This allows for the provisioning of data-intensive services even in the case of patchy wireless broadband network coverage and intermittent connectivity. Copyright © 2009 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: A dynamic energy-efficient clustering algorithm that prolongs the network lifetime by electing cluster-heads taking into consideration, in addition to other parameters such as mobility, their residual energies and making them dynamically monitor their energy consumption to either diminish the number of their cluster-members or relinquish their roles is proposed.
Abstract: Nodes in mobile ad hoc Networks (MANETs) are characterized by their limited resources. Hence, the concept of clustering was introduced to allow spacial reuse of bandwidth and to minimize routing overhead. However, node mobility perturbs the stability of the network and affects the performance of other protocols such as scheduling, routing, and resource allocation, which makes re-clustering the network to maintain up-to-date information at each node unavoidable. Consequently, clustering models for MANETS should be carefully designed while taking into consideration the fact that mobile nodes are energy constrained. In this paper, we propose a dynamic energy-efficient clustering algorithm that prolongs the network lifetime by electing cluster-heads taking into consideration, in addition to other parameters such as mobility, their residual energies and making them dynamically monitor their energy consumption to either diminish the number of their cluster-members or relinquish their roles. We have evaluated the performance of the proposed clustering model and compared it with other related clustering approaches found in the literature. Obtained results show the efficiency of the proposed algorithm. Copyright © 2010 John Wiley & Sons, Ltd. The proposed dynamic energy efficient clustering algorithm (DEECA) prolongs the network lifetime by electing cluster-heads taking into consideration their residual energies and making them dynamically monitor their energy consumption to either diminish the number of their cluster members or relinquish their roles. We have compared the proposed model to other related clustering approaches. The Figure shows that after 6000 seconds 48 nodes ran out of energy in other approaches while only 14 nodes ran out of energy in the proposed DEECA. Copyright © 2010 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: Both the theoretical analysis and simulation results show that the proposed scheduling scheme can achieve the key performance objectives such as complete QoS requirements, high channel transmission efficiency and optimal throughput over the whole OFDMA WiMax system.
Abstract: This paper proposes an optimized scheduling scheme in OFDMA-based WiMax networks to achieve both optimized system throughput and a complete QoS implementation for various types of traffic flows. Our scheduling scheme includes two components, one is the resource allocation for each user; the other is the QoS scheduling for various traffic sessions. Specifically an optimization problem is formulated to distribute all OFDMA channel resource among different competing users by exploiting the transmission adaption and multiuser diversity on each traffic channel. The optimized resource allocation can also be processed under different constraints to achieve different performance metrics. To ensure the WiMax QoS performance, we perform the resource allocation in a priority manner with respect to the different types of QoS requirements and get a desired transmission bandwidth for each user. Based on it we further schedule different traffic sessions at each user with respect to a proper admission control mechanism. The relevant solution and algorithms for our proposed scheduling scheme are presented in detail. Both the theoretical analysis and simulation results show that our scheme can achieve the key performance objectives such as complete QoS requirements, high channel transmission efficiency and optimal throughput over the whole OFDMA WiMax system. Copyright © 2009 John Wiley & Sons, Ltd. (1) Formulate and solve an optimized framework for radio channel usage with respect to link adaption and multiuser diversity. (2) Propose both an adaptive resource allocation scheme and admission control mechanism to meet the QoS requirements of various types of traffic sessions. (3) Make a comparison between our scheme and the other current schemes via theoretical analysis and experiment simulations to justify the outperformance of our proposed scheme. Copyright © 2009 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: A number of data productivity-based scheduling algorithms designed for data broadcast systems are extended and their performance in scheduling multi-item requests in multi-channel broadcast environments is evaluated.
Abstract: Nowadays querying multiple-dependent data items in a request is common in many advanced mobile applications, such as traffic information enquiry services. In addition, multi-channel architectures are widely deployed in many data dissemination systems. In this paper, we extend a number of data productivity-based scheduling algorithms and evaluate their performance in scheduling multi-item requests in multi-channel broadcast environments. We observe from the experimental results two performance problems that render these algorithms ineffective. Lastly, we discuss possible causes of these problems to give insights in the design of a better solution. Copyright © 2009 John Wiley & Sons, Ltd. Querying multiple-dependent data items is common in many advanced mobile applications, such as traffic information enquiry services. In this paper, we extend a number of representative scheduling algorithms designed for data broadcast systems and evaluate their performance in scheduling multi-item requests in multi-channel broadcast environments. We observe from the experimental results two performance problems that render these algorithms ineffective. Lastly, we discuss possible causes of these problems to give insights in the design of a better solution. Copyright © 2009 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: The objective is to provide a novel service differentiation scheme based on distributed scheduling in the IEEE 802.16-based mesh mode, thereby offering QoS guarantees and proposing a new fairness model among different traffic flows traversing the same node.
Abstract: In this paper, we address the problem of heterogeneous quality-of-service (QoS) provisioning in IEEE 802.16-based wireless mesh networks. Our objective is to provide a novel service differentiation scheme based on distributed scheduling in the IEEE 802.16-based mesh mode, thereby offering QoS guarantees. We first devise a novel scheme for the traffic class differentiation, which can be implemented at the medium access control layer. We then present a QoS-aware fair packet scheduling (QFPS) algorithm to fulfill the QoS provisioning. With QFPS, a traffic flow with urgent QoS demand is guaranteed to be given priority in wireless resource allocation over those ones with mild QoS requirements. A shorter end-to-end delay is therefore expected to be offered for the traffic flows with time-urgent requirements. Moreover, we propose a new fairness model among different traffic flows traversing the same node. All traffic flows passing through a node are served by the Deficit Round-Robin scheduling algorithm to achieve fairness within the same priority group. The experimental results of the QFPS demonstrate that various traffic flows are provided with a differentiated service that offers QoS guarantees. Copyright © 2009 John Wiley & Sons, Ltd. We present a QoS-aware fair packet scheduling (QFPS) algorithm to fulfill the QoS provisioning for distributed IEEE 802.16 mesh network. We take advantage of the distributed scheduling mechanism dictated in the standard and design a hierarchical QoS scheduling structure to guarantee the end-to-end delay of the traffic flows with time-urgent requirements. Moreover, a new fairness model among different traffic flows is also implemented in QFPS to schedule traffic flows fairly. Copyright © 2009 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: This work considers the challenge of organizing densely deployed sensor nodes into the form of clusters, using the distribution of network residual energy (NRE), which is defined as the sum of node residual energy, and proves to approximate the Gaussian distribution.
Abstract: We consider the challenge of organizing densely deployed sensor nodes into the form of clusters, using the distribution of network residual energy (NRE), which is defined as the sum of node residual energy. Irrespective of network topology, the distribution of NRE is proven to approach Gaussian in dense node deployment. A decentralized clustering algorithm is present, using timers and a recursively updated probability to select nodes with more residual energy to become Cluster Head (CH) nodes and organize other nodes in the form of clusters over slotted time intervals. Embracing the dense node deployment, each node initializes its probability of becoming a CH node using the distribution of NRE defined in its neighborhood area. Each of the selected CH nodes resides in the center of its cluster area, which has a radius that can be arbitrarily chosen. The performances of the new clustering algorithm are analyzed and then validated via extensive simulations, taking into account variable cluster radius and variable network density. The new clustering algorithm significantly prolongs the network lifetime, in comparison to several representative and competing clustering algorithms reported in the literature. Copyright © 2010 John Wiley & Sons, Ltd. A decentralized clustering algorithm uses timers and a recursively updated probability to select nodes with more residual energy to become Cluster Head (CH) nodes and organize other nodes in the form of clusters over slotted time intervals. Each node initializes its probability of becoming a CH node using the distribution of Network Residual Energy (NRE) defined in its neighborhood area, which is proven to approximate the Gaussian distribution. The new clustering algorithm selects energy-rich CH nodes that reside in the center of every cluster area, and thus significantly prolongs the network lifetime. Copyright © 2010 John Wiley & Sons, Ltd.

Journal IssueDOI
TL;DR: The analytical and simulation results show that the numbers of HCRNs and DSs play identical roles in the performance improvement, while the antenna number of DS provides a more significant diversity gain than the MUD gain or the cooperative diversity gain.
Abstract: In this paper, we present a hierarchical convergence scheme for multi-radio access networks via heterogeneous cooperative relaying technique, where heterogeneous cooperative relay node (HCRN) acts as the convergence gateway and provides cooperative diversity and antenna array gains. The multiple antennas are configured on base station (BS), HCRN, and destination node (DS) to achieve the antenna array gain. Considering the power consumption and implementing complexity at HCRN, only a single antenna is configured at HCRN to transmit decoded packages to the destination node (DS). A joint heterogeneous cooperative relay selection and maximal-ratio combining scheme is proposed to maximize both cooperative and multi-user diversity (MUD) gains. Tight closed-form expressions for the outage probability and average symbol error rate are derived to evaluate performances, which are related strictly to the cooperative relay selection scheme, multiple antenna configurations, and fading channels. The analytical and simulation results show that the numbers of HCRNs and DSs play identical roles in the performance improvement, while the antenna number of DS provides a more significant diversity gain. Thus, in a practical application, we should aim to achieve a high MUD gain, instead of approaching the cooperative diversity gain via deploying too many HCRNs. In addition, the antenna array gain via configuring multiple antennas in DSs is preferred because it is bigger than the MUD gain or the cooperative diversity gain. Copyright © 2009 John Wiley & Sons, Ltd. A hierarchical convergence mechanism for the heterogeneous RANs is presented, where the heterogeneous cooperative relay selection, maximal-ratio combining, multi-user diversity schemes are designed jointed. A closed-form outage probability and symbol error rate expressions and their approximated formulas are derived, and they shows that a full diversity order approximately equals to (KJND–KJ+1) can be achieved, where ND is the antenna number of destination nodes, K and J are the number of destination nodes and relay nodes, respectively. Copyright © 2009 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this article, an online-battery aware geographic routing algorithm for WSNs is proposed to guarantee QOS and minimize energy consumption by calculating the remaining battery capacity of nodes and taking advantage of the battery recovery process.
Abstract: Wireless sensor networks (WSNs) are being used in a wide variety of critical applications such as military and health-care applications. Such networks, which are composed of sensor nodes with limited memory capacity, limited processing capabilities, and most importantly limited energy supply, require routing protocols that take into consideration these constraints. The aim of this paper is to provide an efficient power aware routing algorithm for WSNs that guarantees QOS and at the same time minimizes energy consumption by calculating the remaining battery capacity of nodes and taking advantage of the battery recovery process. We present an online-battery aware geographic routing algorithm. To show the effectiveness of our approach, we simulated our algorithm in ns2 and compared it with greedy perimeter stateless routing for wireless networks and battery-aware routing for streaming data transmissions in WSNs. Copyright © 2009 John Wiley & Sons, Ltd. Wireless Sensor Networks (WSNs) are composed of sensor nodes with limited memory capacity, limited processing capabilities, and most importantly limited energy supply. This paper provides an efficient power aware online-battery aware geographic routing algorithm for WSNs that guarantees QOS and at the same time minimizes energy consumption by taking advantage of the battery recovery process. Copyright © 2009 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this article, a user-centric joint call admission control (JCAC) algorithm is proposed to select the most appropriate RAT for each incoming call in heterogeneous wireless networks, where users' preferences are considered in making RAT selection decisions.
Abstract: Next-generation wireless networks (NGWN) will be heterogeneous, comprising of a number of radio access technologies (RATs) co-existing in the same geographical area. In NGWN, joint call admission control (JCAC) algorithms are required to select the most appropriate RAT for each incoming call. It is envisaged that these JCAC algorithms will be user-centric (i.e. will consider users' preferences in making RAT selection decisions) in order to enhance user satisfaction. However, user-centric JCAC algorithms can lead to highly unbalanced traffic load among the available RATs in NGWN because users act independently, and most of them may prefer to be connected through a particular RAT. Highly unbalanced traffic load in NGWN will result in high overall call blocking-dropping probability and poor radio result utilization. To address this problem, we propose dynamic pricing for balancing traffic load among available RATs in heterogeneous wireless networks where users' preferences are considered in making RAT selection decisions. By dynamically adjusting the service price in each of the available RATs, the proposed user-centric JCAC scheme evens out the unbalanced traffic load caused by independent users' preferences. The JCAC scheme uses fuzzy multiple attribute decision-making (MADM) technique to select the most appropriate RAT for each incoming call. We develop a Markov model to evaluate the overall call blocking-dropping probability and percentage load in each RAT in heterogeneous wireless networks. Performance of the proposed JCAC scheme is compared with that of a scheme that does not use dynamic pricing. Simulation results are given to show the effectiveness of the proposed JCAC scheme. Copyright © 2009 John Wiley & Sons, Ltd. This paper proposes dynamic pricing for balancing traffic load among available RATs in heterogeneous wireless networks where users' preferences are considered in making RAT selection decisions. By dynamically adjusting the service price in each of the available RATs, the proposed user-centric JCAC scheme evens out the unbalanced traffic load caused by independent users' preferences. Simulation results show that the proposed scheme reduces call blocking-dropping probability in heterogeneous wireless networks. Copyright © 2009 John Wiley & Sons, Ltd.