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Network resource reservation systems are being developed and deployed, driven by the demand and substantial benefits of providing performance predictability for modern distributed applications. However, existing systems suffer limitations: They either are inefficient in finding the optimal resource reservation, or cause private information (e.g., from the network infrastructure) to be exposed (e.g., to the user). In this paper, we design BoxOpt, a novel system that leverages efficient oracle construction techniques in optimization and learning theory to automatically, and swiftly learn the optimal resource reservations without exchanging any private information between the network and the user. In BoxOpt, we first model the simple reservation interface adopted in most reservation systems as a resource membership oracle. Second, we develop an efficient algorithm that constructs a resource separation oracle by a linear number of calls on resource membership oracle. Third, we develop a generic framework to construct a resource optimization oracle by iteratively calling the resource separation oracle, and then develop three novel, efficient algorithms under this generic framework, the best of which computes the optimal resource reservation by a linear number of calls on resource separation oracle. As such, BoxOpt can discover the optimal resource reservation with O(n2) calls on the resource membership oracle. We implement a prototype of BoxOpt with and demonstrate its efficiency and efficacy via extensive experiments using real network topology and a 7-day trace from a large operational federation network. Results show that (1) BoxOpt has a 100% correctness ratio by comparing with a state-of-the-art optimization solver, and (2) for 90% of requests, BoxOpt learns the optimal resource reservation within 10 seconds. [ABSTRACT FROM AUTHOR]

High-demanding transfers of extremely large amounts of data have been increasingly supported by the bandwidth reservation services in dedicated high-performance networks (HPNs). To use the bandwidth reservation service, a user needs to initialize a bandwidth reservation request (BRR) containing parameters and requirements of the bandwidth reservation or data transfer, such as the time interval. Upon receiving one BRR, existing researches and bandwidth reservation service providers return either the best-case bandwidth reservation (BR) or a reject message if not all the BRR requirements can be satisfied. In this paper, we study the intelligent and flexible bandwidth scheduling of two common types of BRRs: direct bandwidth reservation and indirect bandwidth reservation (data transfer). When not all the requirements of the first type can be satisfied, instead of a direct reject message, we identify and return two alternative BRs made within the closest time intervals before and after the user-specified time interval; for the second type, besides the above two alternative BRs, we also identify and return the alternative BR made within the closest time interval crossing the user-specified time interval. For each problem, we design a flexible bandwidth scheduling algorithm with rigorous optimality proofs to compute both the best-case and alternative BRs. For comparison, we also design two heuristic algorithms adapted from existing bandwidth scheduling algorithms. We then conduct extensive simulations to compare their overall performance, and the simulation results show that the proposed optimal algorithms have superior performance to those in comparison. To the best of our knowledge, our work in this paper is among the first to study intelligent and adaptive bandwidth scheduling with alternative BRs in HPNs. [ABSTRACT FROM AUTHOR]

The widespread deployment of scientific applications and business services of various types on clouds requires the transfer of big data with different priorities between geographically distributed cloud-based data centers. As a result, Cloud Service Providers (CSP) face a significant challenge to fully utilize the expensive bandwidth resources of the links connecting data centers while guaranteeing Quality of Experience (QoE) for users. Modern data centers are increasingly adopting Software-Defined Networking (SDN) technology, which provides the capability of advance bandwidth reservation. This paper focuses on the collaborative scheduling of multiple prioritized user requests, namely, advance bandwidth reservation with a lower priority and immediate bandwidth reservation with a higher priority, to maximize the total user satisfaction. We formulate this co-scheduling problem with preemption as a generic optimization problem, which is shown to be NP-complete. We design a heuristic algorithm to maximize the number of successfully scheduled requests and minimize the number of preempted advance reservation requests, while minimizing the completion time of each request. Extensive results from simulations with randomly generated networks and emulation-based experiments on an SDN testbed show that our scheduling scheme significantly outperforms greedy approaches in terms of user satisfaction degree, a normalized quantification parameter we define to measure users' QoE. [ABSTRACT FROM AUTHOR]

The IEEE Audio Video Bridging (AVB) technology is nowadays under consideration in several automation domains, such as, automotive, avionics, and industrial communications. AVB offers several benefits, such as open specifications, the existence of multiple providers of electronic components, and the real-time support, as AVB provides bounded latency to real-time traffic classes. In addition to the above mentioned properties, in the automotive domain, comparing with the existing in-vehicle networks, AVB offers significant advantages in terms of high bandwidth, significant reduction of cabling costs, thickness and weight, while meeting the challenging EMC/EMI requirements. Recently, an improvement of the AVB protocol, called the AVB ST, was proposed in the literature, which allows for supporting scheduled traffic, i.e., a class of time-sensitive traffic that requires time-driven transmission and low latency. In this paper, we present a schedulability analysis for the real-time traffic crossing through the AVB ST network. In addition, we formally prove that, if the bandwidth in the network is allocated according to the AVB standard, the schedulability test based on response time analysis will fail for most cases even if, in reality, these cases are schedulable. In order to provide guarantees based on analysis test a bandwidth over-reservation is required. In this paper, we propose a solution to obtain a minimized bandwidth over-reservation. To the best of our knowledge, this is the first attempt to formally spot the limitation and to propose a solution for overcoming it. The proposed analysis is applied to both the AVB standard and the AVB ST. The analysis results are compared with the results of several simulative assessments, obtained using OMNeT++, on both automotive and industrial case studies. The comparison between the results of the analysis and the simulation ones shows the effectiveness of the analysis proposed in this work. [ABSTRACT FROM AUTHOR]

The Tactile Internet that will enable humans to remotely control objects in real time by tactile sense has recently drawn significant attention from both academic and industrial communities. Ensuring ultra-reliable and low-latency communications with limited bandwidth is crucial for Tactile Internet. Recent studies found that the packet arrival processes in Tactile Internet are very bursty. This observation enables us to design a spectrally efficient resource management protocol to meet the stringent delay and reliability requirements while minimizing the bandwidth usage. In this paper, both model-based and data-driven unsupervised learning methods are applied in classifying the packet arrival process of each user into high or low traffic states, so that we can design efficient bandwidth reservation schemes accordingly. However, when the traffic-state classification is inaccurate, it is very challenging to satisfy the ultra-high reliability requirement. To tackle this problem, we formulate an optimization problem to minimize the reserved bandwidth subject to the delay and reliability requirements by taking into account the classification errors. Simulation results show that the proposed methods can save 40%–70% bandwidth compared with the conventional method that is not aware of burstiness, while guaranteeing the delay and reliability requirements. Our results are further validated by the practical packet arrival processes acquired from experiments using a real tactile hardware device. [ABSTRACT FROM AUTHOR]

Telemedicine traffic carries critical information with regard to a patients' condition; hence, it requires the highest transmission priority compared with all other types of traffic in the cellular network. The need for expedited errorless transmission of multimedia telemedicine traffic calls for a guaranteed bandwidth to telemedicine users. This condition, however, creates a tradeoff between the satisfaction of the very strict quality-of-service (QoS) requirements of telemedicine traffic and the loss of this guaranteed bandwidth in the numerous cases when it is left unused due to the infrequent nature of telemedicine traffic. To resolve this complex problem, in this paper, we propose and combine the following two techniques: 1) an adaptive bandwidth reservation scheme based on road map information and on user mobility and 2) a fair scheduling scheme for telemedicine traffic transmission over wireless cellular networks. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a novel on-demand quality-of-service (QoS) routing protocol, SBR [signal-to-interference (SIR) and bandwidth routing], which explicitly fulfills both SIR and bandwidth requirements from different multimedia users in ad hoc mobile networks. With SBR, bandwidth reservation is made by allocating time slots and SIR reservation is ensured by assigning adequate powers at the intermediate nodes between a source and a destination. The power-assignment method used in SBR supports finding routes that satisfy the SIR requirements as well as reduces the level of prevailing interference that necessarily occurs in multiple-access wireless networks. SBR also has a new backup capability of establishing multiple paths, even for a single connection, when the route search cannot find a single path that supports the QoS requirements, which contributes to reducing the probability of call denials in constructing the route due to a lack of suitable paths. Extensive simulations show that SBR significantly reduces the ratio of unsuccessful calls with modest routing overhead. [ABSTRACT FROM AUTHOR]

In this paper, we address the problem of uplink multi-traffic sources scheduling in heterogeneous wireless networks (HWNs) under real time traffics that requires fairness constraint and strict per-packet delay bounds and under non-real time traffics as well. The wide spread of HWNs, such as integrated of WiMax-WiFi-Relay wireless networks, enforces networks operators to design an efficient radio resource management (RRM) in order to tradeoff between network resource utilizations and user satisfactions. RRM concerns with traffic scheduling and admission control amongst different traffic sources to guarantee the Quality of Service. This paper participates to RRM developments by proposing and analyzing an efficient packet scheduling scheme with two modes of operations for the uplink channel of WiMax-WiFi-Relay station HWNs. These two modes of operations are known as Fixed Shared Flow and Adaptive Sharing Flow (ASF). The main aim of this scheduling is to allocate shared WiMax resources in a fair manner and to balance between maximizing the bandwidth utilization and users satisfactions. The performance bounds in terms of delay and throughout are presented. Then, the performance figures of the two modes of operations of the proposed scheduling scheme are compared. The results show that bounded delay can be provisioned for direct WiMax users, users via WiF and users via Relay Stations sharing the same WiMax bandwidth using both operations. Moreover, the simulation results show that the ASF scheduling scheme improves both system utilization and average delays. [ABSTRACT FROM AUTHOR]

Because of the deployment of large-scale experimental and computational scientific applications, big data is being generated on a daily basis. Such large volumes of data usually need to be transferred from the data generating center to remotely located scientific sites for collaborative data analysis in a timely manner. Bandwidth reservation along paths provisioned by dedicated high-performance networks (HPNs) has proved to be a fast, reliable, and predictable way to satisfy the transfer requirements of massive time-sensitive data. In this paper, we study the problem of scheduling multiple bandwidth reservation requests (BRRs) concurrently within an HPN while achieving their best average transfer performance. Two common data transfer performance parameters are considered: the Earliest Completion Time (ECT) and the Shortest Duration (SD). Since not all BRRs in one batch can oftentimes be successfully scheduled, the problem of scheduling all BRRs in one batch while achieving their best average ECT and SD are converted into the problem of scheduling as many BRRs as possible while achieving the average ECT and SD of scheduled BRRs, respectively. The aforementioned two problems are proved to be NP-complete problems. Two fast and efficient heuristic algorithms with polynomial-time complexity are proposed. Extensive simulation experiments are conducted to compare their performance with two proposed naive algorithms in various performance metrics. Performance superiority of these two fast and efficient algorithms is verified. [ABSTRACT FROM PUBLISHER]

Recently, mobile ad-hoc networks have received much attention on account of the proliferation of mobile devices and their potential applications. In ad-hoc networks, node cooperation can play a significant role in determining the network performance. However, methods for stimulating cooperation among nodes have not been investigated sufficiently. In this paper, a new routing scheme is proposed for wireless ad-hoc networks. When the proposed incentive-based model is used, nodes can cooperate with each other for a global goal. To maximize implementation practicality, the proposed scheme is designed in an entirely distributed and online manner. A simulation shows that the proposed scheme can approximate an optimized solution while ensuring a well-balanced network performance under widely different network environments. [ABSTRACT FROM AUTHOR]

In multi-service wireless networks, asymmetric bandwidth allocation has been proposed to satisfy the requirements of asymmetric traffic load introduced by some data applications. However, it is difficult to promptly adjust bandwidth allocation on uplink and downlink according to the dynamics of traffic load. Inappropriate call admission control (CAC) policies in this environment may admit superfluous real-time (RT) calls or non real-time (NRT) calls and thus lead to low bandwidth utilization. In this paper, we propose and evaluate two new CAC schemes to address the problems caused by the mismatch of bandwidth allocation and traffic changing in multi-service wireless networks with bandwidth asymmetry between uplink and downlink. By determining the admissible regions for the RT calls and the NRT calls, the proposed schemes prevent the calls of a specific class from overusing the bandwidth resources. Mathematical analysis and simulation experiments are employed to study and compare the performance of the proposed schemes and the existing schemes. The numerical results show that the proposed schemes can achieve better performances in terms of call blocking probability and bandwidth utilization compared to some existing schemes, even those performing well in bandwidth asymmetry wireless networks. [ABSTRACT FROM AUTHOR]

This paper presents two scheduling algorithms, MWF2Q+ and MDRR, for multiple classes of service over the same spectrum in the forward link of the UMTS network. These scheduling algorithms can allocate bandwidth in proportion to weights of flows sharing the channel, and assign OVSF code to backlogged flows on a frame-by-frame basis. The MWF2Q+ algorithm has better fairness properties while the MDRR algorithm requires less computational complexity and space complexity. The fairness properties of these scheduling algorithms are analysed in this paper. Our simulation results show that these two algorithms support multiple traffic sources with heterogeneous rate guarantees while fully utilizing the system bandwidth. The impact of self-similar traffic is also addressed in our simulations. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Bandwidth is an extremely valuable and scarce resource in a wireless network. Therefore, efficient bandwidth management is necessary in order to provide high-quality service to users in a multimedia wireless/mobile network. In this paper, we propose new online bandwidth-management algorithms for bandwidth reservation, call admission, bandwidth migration, and call-preemption strategies. These techniques are combined in an integrated framework that is able to balance the traffic load among cells accommodating heterogeneous multimedia services while ensuring efficient bandwidth utilization. In addition, our online framework to adaptively control bandwidth is a cell-oriented approach that has low complexity, which makes it practical for real cellular networks. Simulation results indicate the superior performance of our bandwidth-management framework to strike the appropriate performance balance between contradictory quality-of-service requirements. [ABSTRACT FROM AUTHOR]

In this paper, a QoS multipath source routing protocol (QoS-MSR) is proposed for ad hoc networks. It can collect QoS information through route discovery mechanism of multipath source routing (MSR) and establish QoS route with reserved bandwidth. In order to reserve bandwidth efficiently, a bandwidth reservation approach called the multipath bandwidth splitting reservation (MBSR) is presented, under which the overall bandwidth request is split into several smaller bandwidth requests among multiple paths. In simulations, the anthors introduce Insignia, an in-bind signaling system that supports QoS in ad hoc networks, and extend it to multipath Insignia (M-Insignia) with QoS-MSR and MBSR. The results show that QoS-MSR routing protocol with the MBSR algorithm can improve the call admission ratio of QoS traffic, the packet delivery ratio, and the end-to-end delay of both best-effort traffic and QoS traffic. Therefore, QoS-MSR with MBSR is an efficient mechanism that supports QoS for ad hoc networks. [ABSTRACT FROM AUTHOR]

Multimedia traffic is expected to be included in the next generation of wireless networks. As in wireline networks, the wireless network must also be capable of providing guaranteed quality-of-service (QoS) over the lifetime of mobile connections. In this paper, a bandwidth reservation scheme incorporating a user mobility prediction is proposed to manage the QoS of the networks. The mobility prediction scheme is developed based on the aggregate history of mobile users. Based on the mobility prediction, bandwidth is reserved to guarantee the uninterrupted handoff process. Simulation results demonstrate that the proposed scheme can guarantee the required QoS requirements in terms of handoff call dropping probability and new call blocking probability while maintaining efficient bandwidth utilization. [ABSTRACT FROM AUTHOR]

Ensuring quality of service (QoS) for the mobile users during vertical handover between IEEE 802.11 wireless local area networks (WLAN) and data network provided by Ultramodern Telecommunication Systems (UMTS) is one of the key requirements for seamless mobility and transfer of existing connections from one network to another. QoS fulfillment is a complex problem and requires participation of both the mobile users as well as the connection networks. The QoS assurance criteria for existing connections can be affected by fluctuations of data rates when a user moves from the high speed WLAN network to the low speed UMTS network, even in the presence of another WLAN network in its vicinity. This can happen if the alternate WLAN network is highly loaded. Therefore handover from a high speed network to a low speed network should be avoided, whenever possible. This paper proposes a QoS based handover procedure that prioritizes the existing connection over the new connections so that rate fluctuations due to handover can be avoided if there exist another WLAN network in the range of the mobile user. Whenever the possibility of handover is detected, a pre-handover bandwidth reservation technique is used to reserve bandwidth at the alternate WLAN networks to avoid QoS degradation. The proposed scheme is implemented in Qualnet network simulator and the performance is analyzed and compared with traditional handover techniques. [ABSTRACT FROM AUTHOR]

Reduction-of-Quality (RoQ) attack is a type of Distributed Denial-of-Service (DDoS) attack that is difficult to detect in current computing systems and networks. These RoQ attacks throttle the throughput heavily and reduce the Quality of Service (QoS) to end systems gradually rather than refusing the clients from the services completely. In this paper, we propose to develop a flow monitoring scheme to defend against such attacks in mobile Ad-hoc networks. Our proposed defense mechanism consists of a flow monitoring table (FMT) at each node to identify the attackers. If the channel continues to be congested because some sender nodes do not reduce their sending rate, it can be found by the destination using the updated FMT. Once the attackers are identified, all packets from those nodes will be blocked. By simulation results, we show that our proposed scheme achieves higher throughput and packet delivery ratio with reduced packet drop for legitimate users. [ABSTRACT FROM AUTHOR]

It is important to provide quality of service (QoS) guarantees if we want to support multimedia applications over wireless networks. In this paper, considering the features of tiering in sectored cellular networks, we propose a novel scheme for bandwidth reservation to approach QoS provisioning. By predicting the movement of each connection, the reserving of bandwidth is only required in needful neighboring cells instead of in all neighboring cells. In addition, an admission control mechanism incorporated with bandwidth borrowing assists in distributing scarce wireless bandwidth in more adaptive way. Through mathematical analysis, we proof the advantages of tier-based approach and the bound for the selection of tiered boundary. The simulation results also verify that our scheme can achieve superior performance than traditional schemes regarding no bandwidth reserving, fixed bandwidth reserving, and bandwidth borrowing in sectored cellular networks when performance metrics are measured in terms of the connection dropping probability (CDP), connection blocking probability (CBP), and bandwidth utilization (BU). Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents a simple approximate calculation methodology of the occupancy distribution and the blocking probability in state-dependent systems with multirate Binomial–Poisson–Pascal traffic. The particular traffic streams are generated by an infinite, as well as by a finite, population of traffic sources. The proposed methodology is based on the generalized Kaufman–Roberts recursion. The model enables calculations to be carried out for the systems in which accepting a new call depends on an admission control algorithm (e.g., a model of a full-availability group with bandwidth reservation) as well as for those systems in which accepting a new call depends on the structure of a system (e.g., a model of a limited-availability group). The results of the analytical calculations have been compared with the simulation results of exemplary state-dependent systems. [ABSTRACT FROM AUTHOR]

In the third generation cellular networks and beyond, a wide variety of different services are! will be provided by the operators. Out of QoS reasons, it is preferable to assign priority to certain connection types. These include calls carrying delay-sensitive services and already ongoing calls. In this paper, a prioritization method combining bandwidth borrowing and reservation, called BBR, will be presented. BBR monitors the rate-adaptiveness of the ongoing calls in a cell. Simultaneously, advanced movement predictions are applied to estimate the arrival rate to each cell. If it is determined that the use of bandwidth borrowing (temporarily reducing the data rate of other connections in the same cell) is not sufficient to support the high priority calls that are expected to arrive, a portion of the assigned bandwidth to the cell is exclusively reserved for these calls to prevent call dropping. The scheme enables the operator to increase the average user satisfaction in the network. This is achieved by defining appropriate penalty functions for the events of blocking, dropping and bandwidth reduction of a call. [ABSTRACT FROM AUTHOR]

A conventional IP network is a connectionless, best effort network, but has difficulty guaranteeing the Quality of Service (QoS). To guarantee end-to-end QoS, the Internet Engineering Task Force (IETF) has proposed bandwidth reservation protocols such as the Resource ReSerVation Protocol (RSVP), but a protocol that guarantees all bandwidth reservation requests has not been realized. To address this, with the objective of implementing bandwidth reservation capable of reliably accepting the bandwidth reservation requests regardless of the size of the requested bandwidth, the authors proposed Waiting Bandwidth Reservation Communication, which is an extension of RSVP. By using this method, we verified that excellent results compared to conventional RSVP are obtained when all bandwidth reservation communications pass over a special path and the bandwidth reservation requests exceed the bandwidth available for reservation along that path. On the other hand, in a wide-area network such as the Internet, the problems are that all of the bandwidth reservation communications are not along special paths and unnecessary waits are generated when waiting for bandwidth reservations. With the objective of solving these problems, in this paper, we propose RSVP that considers the waiting time until the start of bandwidth reservation and demonstrate through simulations how the proposed method solves these problems. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(8): 71–81, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10103 [ABSTRACT FROM AUTHOR]

In wireless networks carrying multimedia traffic (voice, video, data, and image), it becomes necessary to provide a quality-of-service(QoS) guarantee for multimedia traffic connections supported by the network. In order to provide mobile hosts with high QoS in the next-generation wireless networks, efficient and better bandwidth reservation schemes must be designed. This paper presents a novel dynamic-grouping bandwidth reservation scheme as a solution to support QoS guarantees in the next-generation wireless networks. The proposed scheme is based on the probabilistic resource estimation to provide QoS guarantees for multimedia traffic in wireless cellular networks. We establish several reservation time sections, called groups, according to the mobility information of mobile hosts of each base station. The amount of reserved bandwidth for each base station is dynamically adjusted for each reservation group. We use the dynamic-grouping bandwidth reservation scheme to reduce the connection blocking rate and connection dropping rate, while increasing the bandwidth utilization. The simulation results show that the dynamic-grouping bandwidth reservation scheme provides less connection-blocking rate and less connection-dropping rate and achieves high bandwidth utilization. [ABSTRACT FROM AUTHOR]

Some types of multimedia streams, like compressed video, transmit frames of various sizes at fixed periodic instants. For such variable bit-rate streams, there is a trade-off between the transmission bandwidth reserved (and potentially unused) and the queueing delays observed. Moreover, the calculation of quality-of-service (QOS) guarantees is not trivial. The purpose of this paper is twofold. First, we present a QOS management scheme that maps variable bit-rate streams to a simple, periodic traffic model and thus allows for the estimation of delay bounds. The approach also includes a tuning parameter that explicitly controls the trade-off between reserved bandwidth and delay. Second, the scheme is applied to some real-world scenarios. Its validity is proven and hints for the practical control of the trade-off are derived. [ABSTRACT FROM AUTHOR]

In this paper, a multirate loss model for the calculation of time and call congestion probabilities in a Wideband Code Division Multiple Access (W-CDMA) cell is considered. It utilizes the Bandwidth Reservation (BR) policy and supports calls generated by an infinite or finite number of users. The BR policy achieves QoS equalization by equalizing congestion probabilities among calls of different service-classes. In the proposed models a multiple access interference is considered, and the notion of local blocking, user's activity and interference cancelation. Although the analysis of the proposed models reveals that the steady state probabilities do not have a product form solution, the authors show that the calculation of time and call congestion probabilities can be based on approximate but recursive formulas, whose accuracy is verified through simulation and found to be quite satisfactory. [ABSTRACT FROM AUTHOR]

Voice over IP (VoIP) is a widely recognized killer application of the Internet and it has been integrated within many services (for instance to enrich the on-line gaming experience). In addition, such feature is often natively supported by mobile devices equipped with IEEE 802.11-based communications, or by standard UMTS (Universal Mobile Telecommunication System) cellular phones. Nevertheless, Beyond 3rd Generation (B3G) telephony is expected to fully support IP-based communications. In this perspective, this paper analyzes the feasibility of adopting a simple framework, based on neural networks, to reserve bandwidth, when in presence of VoIP communications. The framework has been designed to be simply embeddable within a wide range of cost-effective consumer devices (e.g., xDSL modems, cellular phones and network appliances). [ABSTRACT FROM PUBLISHER]

Abstract: The dynamic topologies of mobile and wireless ad hoc networks affect voice communication applications. Difficult issues are wireless links with time-varying capacity and large loss rates, available bandwidth undergoing fast time-scale variations due to channel fading and physical obstacles, absence of centralized components assisting session set up and management, and instability of routes. The purpose of this paper is to survey research works that have been conducted to address these difficulties with an emphasis on the support of point-to-point voice sessions. The survey covers six complementary aspects: voice over ad hoc network architecture, route selection, bandwidth reservation and admission control, adaptive applications and security. [Copyright &y& Elsevier]

Abstract: Many mechanisms based on bandwidth reservation have been proposed in the literature to decrease connection dropping probability for handoffs in cellular communications. The handoff events occur at a much higher rate in packet-switched fourth generation mobile communication networks than in traditional cellular systems. An efficient bandwidth reservation mechanism for the neighboring cells is therefore critical in the process of handoff during the connection of multimedia calls to avoid the unwillingly forced termination and waste of limited bandwidth in fourth generation mobile communication networks, particularly when the handoff traffic is heavy. In this paper, an adaptive two-tier scheme, which employs grey prediction theory and swarm intelligence techniques, is proposed to reduce the forced termination probability of multimedia handoffs. The simulation results show that the proposed scheme can achieve superior performance than the representative bandwidth-reserving schemes in the literature when performance metrics are measured in terms of the forced termination probability for the handoffs, the call blocking probability for the new connections and bandwidth utilization. [Copyright &y& Elsevier]

Abstract: In the present and next generation wireless networks, cellular system remains the major method of telecommunication infrastructure. Since the characteristic of the resource constraint, call admission control is required to address the limited resource problem in wireless network. The call dropping probability and call blocking probability are the major performance metrics for quality of service (QoS) in wireless network. Many call admission control mechanisms have been proposed in the literature to decrease connection dropping probability for handoffs and new call blocking probability in cellular communications. In this paper, we proposed an adaptive call admission control and bandwidth reservation scheme using fuzzy logic control concept to reduce the forced termination probability of multimedia handoffs. Meanwhile, we adopt particle swarm optimization (PSO) technique to adjust the parameters of the membership functions in the proposed fuzzy logic systems. The simulation results show that the proposed scheme can achieve satisfactory performance when performance metrics are measured in terms of the forced termination probability for the handoffs, the call blocking probability for the new connections and bandwidth utilization. [Copyright &y& Elsevier]

Abstract: The provisioning of QoS in wireless networks carrying multimedia traffic imposes a big challenge to network designers and traffic engineers. Guaranteeing QoS in wireless networks is a complicated task due to the unique characteristics of wireless networks such as user mobility, limited link capacity, frequent link failure, scarcity of bandwidth, channel fading, and inability to predict the availability of resources in the network. In this paper, we investigate multiple QoS schemes in multimedia wireless networks. A modification to an existing scheme, rate-based borrowing scheme, where the concept of borrowing bandwidth from existing connections to accept both new and handoffs connections is proposed. Unlike Rate-Based Borrowing Scheme (RBBS) and Statistical Scheme (SBS), Dynamic Rate-Based Borrowing Scheme (DRBBS) exploits the positive feature of fair borrowing bandwidth and avoids pre-allocation of resources. This is based on the concept of borrowing from existing connections. Extensive simulation experiments have been performed using a simulation package designed for the purpose of this research. Using the call dropping/blocking probabilities and bandwidth utilization as a performance metrics, the proposed scheme, DRBBS outperforms the previously known schemes in terms of the aforementioned performance metrics. Fair borrowing from ongoing connections shows a decrease in the rate of calls dropping probabilities and a decrease in the calls blocking probabilities, while avoiding pre-allocation of resources offers a significant improvement in the bandwidth utilization. [Copyright &y& Elsevier]

Abstract: To ensure uninterrupted communication in a mobile ad hoc network, efficient route discovery is crucial when nodes move and/or fail. Hence, protocols such as Dynamic Source Routing (DSR) precompute alternate routes before a node moves and/or fails. In this paper, we modify the way these alternate routes are maintained and used in DSR, and show that these modifications permit more efficient route discovery when nodes move and/or fail. Our routing protocol also does load balancing among the number of alternate routes that are available. Our simulation results show that maintenance of these alternate routes (without affecting the route cache size at each router) increases the packet delivery ratio. We also show that our approach enables us to provide QoS guarantees by ensuring that appropriate bandwidth will be available for a flow even when nodes move. Towards this end, we show how reservations can be made on the alternate routes while maximizing the bandwidth usage in situations where nodes do not move. We also show how the load of the traffic generated due to node movement is shared among several alternate routes. In addition, we adaptively use Forward Error Correction techniques with our protocol and show how it can improve the packet delivery ratio. [Copyright &y& Elsevier]

Abstract: This paper first studied the timeslot assignment problem in time division multiple access/code division multiple access (TDMA/CDMA) wireless ad hoc networks. Given a path P, we prove that a timeslot assignment providing one unit of bandwidth on P can be found in O(∣P∣) time if such an assignment exists. The results have been extended to the case that P can provide two units of bandwidth. Based on the timeslot assignment for the special cases, an efficient slot assignment algorithm with O(∣P∣2 k) is proposed for general cases, where k is the number of slots in a TDMA frame. Then, the timeslot assignment algorithm is integrated into a quality of service (QoS) call admission scheme for QoS call requests. Extensive simulations are conducted and the results have demonstrated the superior performance of our method. [Copyright &y& Elsevier]

Abstract: Many mechanisms based on bandwidth reservation have been proposed in the literature to decrease connection dropping probability for handoffs in cellular communications. The handoff events occur at a much higher rate in sectored cellular networks than in traditional cellular systems. An efficient bandwidth reservation mechanism for the neighboring cells is therefore critical in the process of handoff during the connection of multimedia calls to avoid the unwillingly forced termination and waste of limited bandwidth in the sectored cellular communications, particularly when the handoff traffic is heavy. In this paper, a self-adaptive bandwidth reservation scheme, which adopts support vector machines technique, is proposed to reduce the forced termination probability. Meanwhile, a channel-borrowing technique is used to decrease the new call-blocking probability of real-time traffic. The simulation results show that the proposed scheme can achieve superior performance than the representative bandwidth-reserving schemes in sectored cellular networks in the literature when performance metrics are measured in terms of the forced termination probability and the new call- blocking probability. [Copyright &y& Elsevier]

In an enterprise network, it is common to have hundreds of video conferences held simultaneously such that a large number of video streams need to be transmitted between participants in different geographical locations. For such a large transmission demand, an advance reservation (AR) system deployed for the video conferencing system can provide quality-of-service (QoS) guarantees to users and improve the resource utilization of the network. However, the effective resource reservation strategies for a heavy traffic case still remains open. In this paper, we propose an algorithm called the elastic timeslot-based advance reservation algorithm (ETARA), which aims at improving the resource utilization and reducing the computational complexity. A new time processing method, elastic timeslot, is proposed for the time domain management. Moreover, ETARA takes not only the processing time but also the resource usage into account. Comparative simulations with the existing two popular approaches, the dynamic timeslot-based approach and timeslot-based flexible approach, have been performed in terms of the acceptance ratio and runtime. The results show that with the same acceptance ratio, the runtime of ETARA can be up to 57 times lower than that of the flexible timeslot-based approach. Though ETARA has a slightly longer runtime than the dynamic approach, the acceptance ratio of ETARA can be twice as high as that of the dynamic timeslot-based approach.