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Showing papers in "IEEE Transactions on Mobile Computing in 2002"


Journal ArticleDOI
TL;DR: This work proposes a new technique, called sparse topology and energy management (STEM), which efficiently wakes up nodes from a deep sleep state without the need for an ultra low-power radio, and shows that this scheme results in energy savings of over two orders of magnitude compared to sensor networks without topology management.
Abstract: In wireless sensor networks, energy efficiency is crucial to achieving satisfactory network lifetime. To reduce the energy consumption significantly, a node should turn off its radio most of the time, except when it has to participate in data forwarding. We propose a new technique, called sparse topology and energy management (STEM), which efficiently wakes up nodes from a deep sleep state without the need for an ultra low-power radio. The designer can trade the energy efficiency of this sleep state for the latency associated with waking up the node. In addition, we integrate STEM with approaches that also leverage excess network density. We show that our hybrid wakeup scheme results in energy savings of over two orders of magnitude compared to sensor networks without topology management. Furthermore, the network designer is offered full flexibility in exploiting the energy-latency-density design space by selecting the appropriate parameter settings of our protocol.

662 citations


Journal ArticleDOI
TL;DR: In-depth simulation shows that the proposed MPDU-based link adaptation scheme outperforms the single-mode schemes and the autorate fallback (ARF) scheme-which is used in Lucent Technologies' WaveLAN-II networking devices-significantly in terms of the average goodput, the frame drop rate, and the average number of transmission attempts per data frame delivery.
Abstract: Link adaptation to dynamically select the data transmission rate at a given time has been recognized as an effective way to improve the goodput performance of the IEEE 802.11 wireless local-area networks (WLANs). Recently, with the introduction of the new high-speed 802.11a physical layer (PHY), it is even more important to have a well-designed link adaptation scheme work with the 802.11a PHY such that its multiple transmission rates can be exploited. In this paper, we first present a generic method to analyze the goodput performance of an 802.11a system under the distributed coordination function (DCF) and express the expected effective goodput as a closed-form function of the data payload length, the frame retry count, the wireless channel condition, and the selected data transmission rate. Then, based on the theoretical analysis, we propose a novel MPDU (MAC protocol data unit)-based link adaptation scheme for the 802.11a systems. It is a simple table-driven approach and the basic idea is to preestablish a best PHY mode table by applying the dynamic programming technique. The best PHY mode table is indexed by the system status triplet that consists of the data payload length, the wireless channel condition, and the frame retry count. At runtime, a wireless station determines the most appropriate PHY mode for the next transmission attempt by a simple table lookup, using the most up-to-date system status as the index. Our in-depth simulation shows that the proposed MPDU-based link adaptation scheme outperforms the single-mode schemes and the autorate fallback (ARF) scheme-which is used in Lucent Technologies' WaveLAN-II networking devices-significantly in terms of the average goodput, the frame drop rate, and the average number of transmission attempts per data frame delivery.

619 citations


Journal ArticleDOI
TL;DR: In this article, a location estimation method based on a statistical signal power model is proposed. But this method requires nonstandard features either in the mobile terminal or the network, such as the cell-ID method in GSM/GPRS cellular networks, which is usually problematic due to their inadequate location estimation accuracy.
Abstract: Some location estimation methods, such as the GPS satellite navigation system, require nonstandard features either in the mobile terminal or the network. Solutions based on generic technologies not intended for location estimation purposes, such as the cell-ID method in GSM/GPRS cellular networks, are usually problematic due to their inadequate location estimation accuracy. In order to enable accurate location estimation when only inaccurate measurements are available, we present an approach to location estimation that is different from the prevailing geometric one. We call our approach the statistical modeling approach. As an example application of the proposed statistical modeling framework, we present a location estimation method based on a statistical signal power model. We also present encouraging empirical results from simulated experiments supported by real-world field tests.

358 citations


Journal ArticleDOI
TL;DR: This paper analyzes some deficiencies of the dominant pruning algorithm and proposes two better approximation algorithms: total dominant pruned and partial dominant prune, which utilize 2-hop neighborhood information more effectively to reduce redundant transmissions.
Abstract: Unlike in a wired network, a packet transmitted by a node in an ad hoc wireless network can reach all neighbors. Therefore, the total number of transmissions (forward nodes) is generally used as the cost criterion for broadcasting. The problem of finding the minimum number of forward nodes is NP-complete. Among various approximation approaches, dominant pruning (Lim and Kim 2001) utilizes 2-hop neighborhood information to reduce redundant transmissions. In this paper, we analyze some deficiencies of the dominant pruning algorithm and propose two better approximation algorithms: total dominant pruning and partial dominant pruning. Both algorithms utilize 2-hop neighborhood information more effectively to reduce redundant transmissions. Simulation results of applying these two algorithms show performance improvements compared with the original dominant pruning. In addition, two termination criteria are discussed and compared through simulation under both the static and dynamic environments.

352 citations


Journal ArticleDOI
TL;DR: The proposed SWAN architecture is designed to handle both real-time UDP traffic, and best effort UDP and TCP traffic without the need for the introduction and management of per-flow state information in the network.
Abstract: We propose SWAN, a stateless network model which uses distributed control algorithms to deliver service differentiation in mobile wireless ad hoc networks in a simple, scalable and robust manner. The proposed architecture is designed to handle both real-time UDP traffic, and best effort UDP and TCP traffic without the need for the introduction and management of per-flow state information in the network. SWAN supports per-hop and end-to-end control algorithms that primarily rely on the efficient operation of TC/IP protocols. In particular, SWAN uses local rate control for best-effort traffic, and sender-based admission control for real-time UDP traffic. Explicit congestion notification (ECN) is used to dynamically regulate admitted real-time sessions in the face of network dynamics brought on by mobility or traffic overload conditions. SWAN does not require the support of a QoS-capable MAC to deliver service differentiation. Rather, real-time services are built using existing best effort wireless MAC technology. Simulation, analysis, and results from an experimental wireless testbed show that real-time applications experience low and stable delays under various multihop, traffic, and mobility conditions.

329 citations


Journal ArticleDOI
TL;DR: A novel distributed and dynamic regional location management for Mobile IP where the signaling burden is evenly distributed and the regional network boundary is dynamically adjusted according to the up-to-date mobility and traffic load for each terminal.
Abstract: Mobile IP is a simple and scalable global mobility solution. However, it may cause excessive signaling traffic and long signaling delay. Mobile IP regional registration is proposed to reduce the number of location updates to the home network and to reduce the signaling delay. This paper introduces a novel distributed and dynamic regional location management for Mobile IP where the signaling burden is evenly distributed and the regional network boundary is dynamically adjusted according to the up-to-date mobility and traffic load for each terminal. In our distributed system, each user has its own optimized system configuration which results in the minimal signaling traffic. In order to determine the signaling cost function, a new discrete analytical model is developed which captures the mobility and packet arrival pattern of a mobile terminal. This model does not impose any restrictions on the shape and the geographic location of subnets in the Internet. Given the average total location update and packet delivery cost, an iterative algorithm is then used to determine the optimal regional network size. Analytical results show that our distributed dynamic scheme outperforms the IETF Mobile IP regional registration scheme for various scenarios in terms of reducing the overall signaling cost.

267 citations


Journal ArticleDOI
TL;DR: This paper proposes and evaluates a simple but effective feedback-based distributed algorithm for tuning the p parameter to the optimal values, and shows that power saving and throughput maximization can be jointly achieved.
Abstract: Wireless technologies in the LAN environment are becoming increasingly important. The IEEE 802.11 is the most mature technology for wireless local area networks (WLANs). The limited bandwidth and the finite battery power of mobile computers represent one of the greatest limitations of current WLANs. In this paper, we deeply investigate the efficiency and the energy consumption of MAC protocols that can be described with a p-persistent CSMA model. As already shown in the literature, the IEEE 802.11 protocol performance can be studied using a p-persistent CSMA model (Cali et al. 2000). For this class of protocols, in the paper, we define an analytical framework to study the theoretical performance bounds from the throughput and the energy consumption standpoint. Specifically, we derive the p values (i.e., the average size of the contention window in the IEEE 802.11 protocol (Cali et al.)) that maximizes the throughput, p/sub opt//sup C/, and minimizes the energy consumption, p/sub opt//sup E/. By providing analytical closed formulas for the optimal p values, we discuss the trade-off between efficiency and energy consumption. Specifically, we show that power saving and throughput maximization can be jointly achieved. Our analytical formulas indicate that the optimal p values depend on the network configuration, i.e., number of active stations and length of the messages transmitted on the channel. As network configurations dynamically change, the optimal p values must be dynamically updated. In this paper, we propose and evaluate a simple but effective feedback-based distributed algorithm for tuning the p parameter to the optimal values, i.e., p/sub opt//sup E/ and p/sub opt//sup C/. The performance of the p-persistent IEEE 802.11 protocol, enhanced with our algorithm, is extensively investigated by simulation. Our results indicate that the enhanced p-persistent IEEE 802.11 protocol is very close to the theoretical bounds both in steady-state and in transient conditions.

167 citations


Journal ArticleDOI
TL;DR: This work introduces two protocols that exploit the use of directional antennas and evaluates their performance, observing significant improvement with respect to the omnidirectional case, in terms of both energy efficiency and network lifetime.
Abstract: We consider ad hoc wireless networks that use directional antennas and have limited energy resources. To explore quantitatively the advantage offered by the use of directional antennas over the case of omnidirectional antennas, we consider the case of connection-oriented multicast traffic. Building upon our prior work on multicasting algorithms, we introduce two protocols that exploit the use of directional antennas and evaluate their performance, We observe significant improvement with respect to the omnidirectional case, in terms of both energy efficiency and network lifetime. Additionally, we show that further substantial increase in the network's lifetime can be achieved by incorporating a simple measure of a node's residual energy into the node's cost function.

159 citations


Journal ArticleDOI
TL;DR: To reduce the call blocking probability and the code reassignment cost, this work proposes two simple yet efficient strategies that can be adopted by both code placement and code replacement: leftmost and crowded-first.
Abstract: The use of OVSF codes in WCDMA systems has offered opportunities to provide variable data rates to flexibly support applications with different bandwidth requirements. Two important issues in such an environment are the code placement problem and code replacement problem. The former may have significant impact on code utilization and, thus, code blocking probability, while the latter may affect the code reassignment cost if dynamic code assignment is to be conducted. The general objective is to make the OVSF code tree as compact as possible so as to support more new calls by incurring less blocking probability and less reassignment costs. Earlier studies about these two problems either do not consider the structure of the OVSF code tree or cannot utilize the OVSF codes efficiently. To reduce the call blocking probability and the code reassignment cost, we propose two simple yet efficient strategies that can be adopted by both code placement and code replacement: leftmost and crowded-first. Numerical analyses on call blocking probability and bandwidth utilization of OVSF code trees when code reassignment is supported are provided. Our simulation results show that the crowded-first strategy can significantly reduce, for example, the code blocking probability by 77 percent and the number of reassignments by 81 percent, as opposed to the random strategy when the system is 80 percent fully loaded and the max SF = 256.

147 citations


Journal ArticleDOI
TL;DR: The experimental results show that the UMP scheme outperforms the time-based and movement-based location update schemes as well as the blanket, selective, and velocity paging schemes.
Abstract: The user mobility pattern (UMP) scheme is introduced for location update and paging in wireless systems where mobile terminals (MTs) maintain their history data in a database called user mobility history (UMH). During a location update, a UMP is derived from UMH and registered to the network. Unless the MT detects that it has moved out of the registered UMP, it does not perform any other location update. On the other hand, cells are paged selectively according to the cell entry times in the registered UMP upon a call arrival for the MT. The related data structures and the protocols for the UMP scheme are presented in the paper. The experimental results show that the UMP scheme outperforms the time-based and movement-based location update schemes as well as the blanket, selective, and velocity paging schemes.

121 citations


Journal ArticleDOI
TL;DR: A new location management scheme is presented which intends to mitigate the signaling traffic as well as reduce the tracking delay in the PCS systems and can significantly reduce the network signaling traffic for users with low CMR without increasing much of the call setup delay.
Abstract: For a IPCS network to effectively deliver services to its mobile users, it must have an efficient way to keep track of the mobile users. The location management fulfills this task through location registration and paging. To reduce the signaling traffic, many schemes such as a local anchor (LA) scheme, per-user caching scheme and pointer forwarding scheme have been proposed in the past. In this paper, we present a new location management scheme which intends to mitigate the signaling traffic as well as reduce the tracking delay in the PCS systems. In this strategy, we choose a set of visitor location registers (VLRs) traversed by users as the mobility agents (MA), which form another level of management in order to make some registration signaling traffic localized. The idea is as follows: instead of always updating to the home location register (HLR), which would become the bottleneck otherwise, many location updates are carried out in the mobility agents. Thus, the two-level pointer forwarding scheme is designed to reduce the signaling traffic: pointers can be set up between VLRs as the traditional pointer forwarding scheme and can also be set up between MAs. The numerical results show that this strategy can significantly reduce the network signaling traffic for users with low CMR without increasing much of the call setup delay.

Journal ArticleDOI
TL;DR: The use of position-assisted and mobility predictive advanced bandwidth reservation with a call admission control and bandwidth reconfiguration strategy to support flexible QoS management and a mobile agent based framework is introduced to carry out the functions of geolocation and of the proposed resource management in wireless networks.
Abstract: We propose an integrated resource management approach that can be implemented in next generation wireless networks that support multimedia services (data, voice, video, etc.). Specifically, we combine the use of position-assisted and mobility predictive advanced bandwidth reservation with a call admission control and bandwidth reconfiguration strategy to support flexible QoS management. We also introduce a mobile agent based framework that can be used to carry out the functions of geolocation and of the proposed resource management in wireless networks. A model is also developed to obtain the optimal location information update interval in order to minimize the total cost of the system operation. The comparison of the achievable performance results of our proposed scheme with the corresponding results of a conventional system that supports advanced bandwidth reservation only, as means of supporting the QoS requirements, demonstrate that our integrated scheme can alleviate the problem of overreservation, support seamless operation throughout the wireless network, and increase significantly the system capacity.

Journal ArticleDOI
TL;DR: An efficient scheme to implement optimistic logging for the mobile computing environment with a small failure-free overhead and the cost of unnecessary rollback caused by the imprecise dependency is adjustable by properly selecting the logging frequency.
Abstract: A number of checkpointing and message logging algorithms have been proposed to support fault tolerance of mobile computing systems. However, little attention has been paid to the optimistic message logging scheme. Optimistic logging has a lower failure-free operation cost compared to other logging schemes. It also has a lower failure recovery cost compared to the checkpointing schemes. This paper presents an efficient scheme to implement optimistic logging for the mobile computing environment. In the proposed scheme, the task of logging is assigned to the mobile support station so that volatile logging can be utilized. In addition, to reduce the message overhead, the mobile support station takes care of dependency tracking and the potential dependency between mobile hosts is inferred from the dependency between mobile support stations. The performance of the proposed scheme is evaluated by an extensive simulation study. The results show that the proposed scheme requires a small failure-free overhead and the cost of unnecessary rollback caused by the imprecise dependency is adjustable by properly selecting the logging frequency.

Journal ArticleDOI
TL;DR: This paper analyzed algorithms for supporting disconnected write operations for wireless Web access and developed a performance model to identify the optimal length of the disconnection period under which the cost of update propagation is minimized, particularly applicable to Web applications which allow wireless mobile users to modify Web contents while on the move.
Abstract: In a wireless mobile client-server environment, a mobile user may voluntarily disconnect itself from the Web server to save its battery life and avoid high communication prices. To allow Web pages to be updated while the mobile user is disconnected from the Web server, updates can be staged in the mobile host and propagated back to the Web server upon reconnection. In this paper, we analyze algorithms for supporting disconnected write operations for wireless Web access and develop a performance model to identify the optimal length of the disconnection period under which the cost of update propagation is minimized. The analysis result is particularly applicable to Web applications which allow wireless mobile users to modify Web contents while on the move. We show how the result can be applied to real-time Web applications such that the mobile user can determine the longest disconnection period such that it can still propagate updates to the server before the deadline so that a minimum communication cost is incurred.

Journal ArticleDOI
TL;DR: Simulation results are presented to demonstrate the performance of the proposed scheme and the throughput improvement achieved by combining resource allocation with base station assignment, and approximations can be made to make the resource-management scheme less computationally complex and allow its partial decentralization.
Abstract: This paper proposes a scheme of optimal resource management for reverse-link transmissions in multimedia wideband code-division multiple-access (WCDMA) communications. It is to guarantee quality-of-service (QoS) by resource (transmit power and rate) allocation and to achieve high spectral efficiency by base-station assignment. This approach takes the form of a nonlinear-programming large-scale optimization problem: maximizing an abstraction for the profit of a service provider subject to QoS satisfaction. Solutions for both single-cell and multicell systems are investigated. The single-cell solution has the advantage of low complexity and global convergence in comparison with the previous work. Maximum achievable throughput (capacity) of a single cell is mathematically evaluated and used as the benchmark for performance measure of multicell systems. For multicell systems, due to its max-max structure, solving the optimization problem directly entails a high-computational complexity. Instead, the problem is reformulated to a mixed integer nonlinear-programming (MINLP) problem. Then, binary variables indicating base-station assignments are relaxed to their continuous analogs to make a computer solution feasible. Furthermore, approximations can be made to make the resource-management scheme less computationally complex and allow its partial decentralization. The sensitivity of the proposed scheme to path-gain estimation error is studied. Simulation results are presented to demonstrate the performance of the proposed scheme and the throughput improvement achieved by combining resource allocation with base station assignment.

Journal ArticleDOI
TL;DR: This paper proposes to enhance the precoded OFDM system with adaptive vector channel allocation to provide stronger protection against errors to more important layers in the layered bit stream structure of scalable video.
Abstract: Orthogonal frequency division multiplexing (OFDM) has been applied in broadband wireline and wireless systems for high data rate transmission where severe intersymbol interference (ISI) always occurs. The conventional OFDM system provides advantages through conversion of an ISI channel into ISI-free subchannels at multiple frequency bands. However, it may suffer from channel spectral nulls and heavy data rate overhead due to cyclic prefix insertion. Previously, a new OFDM framework, the precoded OFDM, has been proposed to mitigate the above two problems through precoding and conversion of an ISI channel into ISI-free vector channels. In this paper, we consider the application of the precoded OFDM system to efficient scalable video transmission. We propose to enhance the precoded OFDM system with adaptive vector channel allocation to provide stronger protection against errors to more important layers in the layered bit stream structure of scalable video. The more critical layers, or equivalently, the lower layers, are allocated vector channels of higher transmission quality. The channel quality is characterized by Frobenius norm metrics; based on channel estimation at the receiver. The channel allocation information is fed back periodically to the transmitter through a control channel. Simulation results have demonstrated the robustness of the proposed scheme to noise and fading inherent in wireless channels.

Journal ArticleDOI
TL;DR: A novel two-dimensional Markov walk model with six states is proposed to characterize the dynamic behavior of the intercell movements for a mobile station, finding a broad class of isotropic processes having an identical uniform steady-state distribution of the six directions, but distinct circulant transition probability matrices.
Abstract: This paper presents a new analytic framework for dynamic location management of PCS networks. Based on the theory of hexagonal cellular patterns, a novel two-dimensional Markov walk model with six states is proposed to characterize the dynamic behavior of the intercell movements for a mobile station. We discover a broad class of isotropic processes having an identical uniform steady-state distribution of the six directions, but distinct circulant transition probability matrices. Six special isotropic processes exhibiting IID, directional, turning, ping-pong, h-spin, and t-spin mobility patterns are identified for performance comparison. We also generalize the selective paging strategy by introducing the concept of probabilistic selective paging (PSP) to reduce the paging cost. A unified analysis using recursive computations is carried out to compute the exact probability distribution for the number of per-call location updates. We calculate the location profile with respect to an incoming call and derive an exact expression of the average paging cost for PSP. With its ability to distinguish subtle performance variations and unveil new features of various dynamic location management schemes, our analytic framework is demonstrated to provide more precise and insightful results than conventional analysis.

Journal ArticleDOI
S. Baey1, M. Dumas1, M.-C. Dumas1
TL;DR: The impact of the rate matching mechanism on the transmission performances at link level for transport channels multiplexed in the uplink is shown and the power index notion useful at the system level is refines as an indicator of resource consumption and transmission quality of the physical data and control channels.
Abstract: This paper studies the uplink of the Universal Mobile Telecommunications System flexible physical layer. It recalls the semistatic approach of transport highlighting key parameters of its control and proposes an external analytic model of the mobile physical layer. This approach is adapted to radio resource management in a multiservice environment, accounting for the relationships between the link and the system levels. This paper clearly shows the impact of the rate matching mechanism on the transmission performances at link level for transport channels multiplexed in the uplink. It refines the power index notion useful at the system level as an indicator of resource consumption and transmission quality of the physical data and control channels. Integrating inter- and intramobile multiservice features with performance tables (considering environment influence, channel coding type, etc.) leads to a cost function of the transport format combinations; a valuable toot for the evaluation of the uplink multiservice cellular capacity. Several multiplexing cases are then studied under the joint aspects of quality tuning and resource consumption.

Journal ArticleDOI
TL;DR: Under the existing GSM/UMTS mobility management and call setup procedures, it is shown how quickly the fraudulent usage can be detected and a simple solution to speed up the detection of potential fraudulent usage is proposed.
Abstract: This paper investigates the fraudulent usage of mobile telecommunications services due to cloned subscriber identity modules (SIMs). In GSM or the Universal Mobile Telecommunication System (UMTS), a mobile phone or mobile station uses its SIM to gain network access through authentication. If the SIM of a legal user is cloned, then the cloned SIM can be used for GSM/UMTS authentication and fraudulent usage may occur. Under the existing GSM/UMTS mobility management and call setup procedures, we show how quickly the fraudulent usage can be detected. We also propose a simple solution to speed up the detection of potential fraudulent usage.

Journal ArticleDOI
TL;DR: With the help of the intelligent management system, the original contents of HTML Web sites can be automatically translated to proper WAP content in an efficient way and the costs associated with maintaining WAP sites could be significantly reduced.
Abstract: The popularity regarding wireless communications is such that more and more WAP sites have been developed with wireless markup language (WML). Meanwhile, to translate hypertext markup language (HTML) pages into proper WML ones becomes imperative since it is difficult for WAP users to read most contents designed for PC users via their mobile phone screens. However, for those sites that have been maintained with hypertext markup language (HTML), considerable time and manpower costs will be incurred to rebuild them with WML. In this paper, we propose an intelligent WAP site management system to cope with these problems. With the help of the intelligent management system, the original contents of HTML Web sites can be automatically translated to proper WAP content in an efficient way. As a consequence, the costs associated with maintaining WAP sites could be significantly reduced. The management system also allows the system manager to define the relevance of numerals and keywords for removing unimportant or meaningless contents. The original contents will be reduced and reorganized to fit the size of mobile phone screens, thus reducing the communication cost and enhancing readability. Numerical results gained through various experiments have evinced the effective performance of the WAP management system.

Journal ArticleDOI
TL;DR: This paper investigates metropolitan services to support mobile virtual groups, i.e., groups of mobile users who have some kind of logical association with each other, but who are distributed throughout the city and are mobile, meaning they might be constantly on the move.
Abstract: More and more cities and municipal organizations start to offer services restricted to their metropolitan area. Today, many of these service are located in the field of e-government, allowing citizens to perform many of their administrative duties online. However, with wireless networks and mobile devices becoming more powerful and much less expensive, a broad variety of new mobile services can be envisioned. In this paper, we investigate metropolitan services to support mobile virtual groups, i.e., groups of mobile users who have some kind of logical association with each other, but who are distributed throughout the city and are mobile, meaning they might be constantly on the move. As two major services that such groups would like to make use of, we identified voice group communication and localization of group members. In mobile environments, both services pose a number of problems. Based on a typical metropolitan area network infrastructure, we develop solutions for these problems. We also show how these solutions can be integrated into a mobile group application, namely, the communication and localization component of a virtual tourist guide for the city of Heidelberg using members of a tourist group which can move independently but still keep in touch. We also describe measurements and experiences to argue for the feasibility of our approach.

Journal ArticleDOI
TL;DR: A model that can express previous paradigms as special cases for distributed computing and mobile code, using cellular automata abstractions to study relations between local node behavior and global system behavior is derived.
Abstract: The Internet supports migration of code from node to node. A number of paradigms exist for distributed computing and mobile code, including client/server, remote evaluation, code-on-demand, and mobile agents. We find them overly-restrictive views of reality. We propose a model that can express previous paradigms as special cases. We derive a model using cellular automata (CA) abstractions to study relations between local node behavior and global system behavior. Example mobile code systems are provided and existing paradigms are expressed in terms of the model. These examples include network attacks such as viruses, worms, and distributed denial of service (DDoS). A distributed system simulation tool based on the model is described. Simulation results provide insights gained from this work.

Journal ArticleDOI
TL;DR: The idea of true ubiquitous mobile computing, including anywhere, anytime access to a subscriber's data, computing environment, and communications network, has captured the imagination of service providers, equipment vendors, and researchers, as well as the Internet-savvy public.
Abstract: The idea of true ubiquitous mobile computing, including anywhere, anytime access to a subscriber's data, computing environment, and communications network, has captured the imagination of service providers, equipment vendors, and researchers, as well as the Internet-savvy public. Mobile computing is a confluence of communication technologies (particularly the Internet), computing devices and their components, and access technologies such as wireless. A mobile computing environment will include not only real-time mobility of devices, but also mobility of people across devices. Therefore, the environment includes a wide range of devices, applications, and networks.

Journal ArticleDOI
TL;DR: Three optimization models for component mobility are presented, seeking the optimal allocation of components to network nodes and the optimal component routes that will minimize the network traffic that is incurred in the course of component communication.
Abstract: Code mobility and mobile agents have received a lot of attention as a paradigm based on which distributed applications can be built. There has been little work however on the mathematical modeling of component mobility. In this direction, we present and analyze three optimization models for component mobility. We are seeking the optimal allocation of components to network nodes and the optimal component routes that will minimize the network traffic that is incurred in the course of component communication. Optimal solutions are found either through a mixed binary integer programming formulation or by employing max flow computations. Complexity results are also reported.