Dynamic Bandwidth Reservation Research Articles

A QoS-Aware CAC with Bandwidth Reservation and Degradation Scheme in IEEE 802.16e Networks

Call admission control (CAC) schemes play a critical role in providing quality-of-service (QoS) guarantees for various classes of traffic with diverse QoS requirements in IEEE 802.16e networks. The dynamic CAC and bandwidth reservation scheme is one of the current schemes that simultaneously provides efficient utilization of network resources and guarantees QoS for admitted connections. However, its admission criteria starved high and low service classes due to its linear adaptation policy to accommodate more users into the network under moderate-to-heavy traffic load conditions. Its adaptive threshold for handoff connections is adjusted based on the arrival of new and handoff connections, that results in a waste of resources when the new and handoff connection arrival rate occurs frequently. In this paper, a new CAC scheme for Mobile WiMAX networks is proposed to prevent starvation of service classes and enhance the efficient utilization of network resources. The scheme determines a new admission criteria based on a scheduling service class. In the admission criteria, bandwidth degradation policy is used to admit more users when there is no available bandwidth to admit a more users. The adaptive threshold has been introduced dynamically to adjust the quantity of reserved bandwidth for handoff connections based on the traffic intensity of handoff requests. In addition, an analytical model for the proposed scheme is also developed. Extensive simulation experiments have been conducted to evaluate the performance of our proposed approach. The simulation results illustrate that the proposed scheme significantly improves the network efficiency compared to other schemes in terms of accepting more connections into the network and assuring QoS for all service classes. The numerical results have shown similar performance to the simulation results.

An Optimal Vertical Handoff Decision Algorithm for Multiple Services with Different Priorities in Heterogeneous Wireless Networks

Heterogeneous wireless networks (HWNs) have aroused numerous interest in the past few years in which efficient vertical handoff algorithms are currently attracting much attention. This paper takes into account the vertical handoff decision algorithm in HWNs where multiple types of services with different priorities are supported. By modeling the vertical handoff process as a Markov decision process, a new reward function is introduced which consists of both quality of service profit and handoff cost. Meanwhile in the proposed reward function, multiple network parameters are included for a comprehensive evaluation of the network utilization. Moreover, considering multiple services with different priorities, an online dynamic bandwidth reservation scheme is proposed based on large deviation principle. This scheme, by estimating possible bandwidth request in future time slots, reserves the bandwidth resource adaptively in advance such that the call blocking probability as well as handoff dropping probability can be guaranteed to be within an admissible range. Simulation results show that the proposed vertical handoff decision algorithm can decrease the expected handoff number by about 15---22 % and significantly increase the expected total reward compared with existing results.

The Cross-Layer per-Flow Admission Control with Adaptive Reservation of Bandwidth and Multiple QoS Guarantee in EDCA of IEEE 802.11e for Internet of Things

The static bandwidth’s reservation and resource allocation in 802.11e results in bad supporting to the Internet of things. The cross-layer per-flow distributed admission control with dynamic reservation of bandwidth and multiple OoS guarantee of EDCA in IEEE802.11e is presented in this paper. The adaptive bits allocation of OFDM in the station is presented to obtain the maximum Shannon’s capacity subjected to the maximum power at first and this information is crossed layer to the MAC. Then the dynamic bandwidth reservation is suggested based on it and the distributed measurement, which adapts to the requirement of the service and maximizes the efficiency of spectrum simultaneously. Meanwhile, the surplus factor’s central estimation based on model is presented to overcome the measurement’s inaccuracy. On the other hand, the relationship between the QoS and the probability of the collision is analyzed and the double criterion with collision probability and bandwidth is used to ensure multiple QoS such as bandwidth and delay. The simulation under MATLAB show that the mechanism presented in this paper outperforms the formers in the utilization of resource and the ability to track the network and service as well as admission of the service.

Dynamic admission control and bandwidth reservation for IEEE 802.16e mobile WiMAX networks

The article presents a dynamic connection admission control (CAC) and bandwidth reservation (BR) scheme for IEEE 802.16e Broadband Wireless Access networks to simultaneously improve the utilization efficiency of network resources and guarantee QoS for admitted connections. The proposed CAC algorithm dynamically determines the admission criteria according to network loads and adopts an adaptive QoS strategy to improve the utilization efficiency of network resources. After new or handoff connections enter the networks based on current admission criteria, the proposed adaptive BR scheme adjusts the amount of reserved bandwidth for handoffs according to the arrival distributions of new and handoff connections in order to increase the admission opportunities of new connections and provide handoff QoS as well. We conduct simulations to compare the performance of our proposed CAC algorithm and BR scheme with that of other approaches. The results illustrate that our approach can effectively improve the network efficiency in terms of granting more connections by as large as about 22% in comparison with other schemes, and can also guarantee adaptive QoS for admitted new and handoff connections.

Admission control by dynamic bandwidth reservation using road layout and bidirectional navigator in wireless multimedia networks

In this paper, we propose a Call Admission Control (CAC) scheme by dynamic bandwidth reservation where a new call is admitted only when both the remaining resource units at the serving Base Station (BS) excluding the resource units of ongoing calls in the BS and the reserved resource units of anticipated incoming handoff calls from direct neighbor cell is enough to accommodate the new call, and when the next cell for this call to visit has enough resource units to accommodate the new call. The proposed call admission control incorporates both mobile information such as position, speed, and next cell to visit by using bidirectional navigator and road layout information. Simulation results show that the handoff call dropping probability and new call blocking probability of our proposed CAC scheme are lower than an existing similar CAC scheme, respectively. To show the practicality of the assumption of having bidirectional navigator for each Mobile Station (MS), we give a simulation where some MSs have bidirectional navigators and some MSs don't have. The simulation results show that more MSs with bidirectional navigators, less the new call blocking probability, while keeping handoff call dropping probability at the same level.

Performance Analysis for QoS Provisioning at Connection-Level in Cellular WCDMA Networks

In this paper we propose a new connection admission control (CAC) scheme namely dynamic bandwidth reservation (DBR) algorithm at the network layer in order to provision connection-level QoS in cellular WCDMA network. DBR scheme supports Multirate services for new and handover (HO) connections traffic by employing orthogonal variable spreading factor (OVSF). However, to exploit the wireless time-varying channel, we employed a prediction criterion of wireless channel for each mobile connection. Therefore, we impact the wireless channel characteristics in the new/HO traffic distribution. The teletraffic analysis of the proposed scheme is analyzed using a novel multistep Markov chain model. We compare our proposed scheme with multiple leaf code reservation (MLCR) schemes without code reassignment [4]. The performance of the proposed scheme is measured in terms of handover connection dropping probability (HCDP), new connection blocking probability (NCBP), forced termination probability (FTP) and channel utilization.

A Dynamic CAC Scheme for the Evaluation of Channel Utilisation of 3.5G Cellular Networks

A dynamic Tri-Threshold Bandwidth Reservation (TTBR) Call Admission Control scheme has been developed to support 3.5G mobile cellular networks. In compliance with the UMTS, this scheme provides three kinds of services namely conversational calls, streaming data calls and interactive/ background calls. By adapting to the changing operation environment, the scheme supports the specific quality of service for each kind of service by dynamically adjusting three threshold values. A comparison to a formerly developed DTBR scheme has been made. It is concluded that the TTBR scheme has a superior performance than the DTBR counterpart. Being one of the most important QoS aspects in mobile communications, the channel utilisation of a 3.5G network based on the developed TTBR scheme is studied. Related important aspects including the handover rate, the traffic load, the threshold value and the performance on multimedia data calls are investigated. While the DTBR cannot fulfil the UMTS requirement, it is found that th...

A Predictive Bandwidth Reservation Scheme Using Mobile Positioning and Road Topology Information

In cellular networks, an important practical issue is how to limit the handoff dropping probability efficiently. One possible approach is to perform dynamic bandwidth reservation based on mobility predictions. With the rapid advances in mobile positioning technology, and the widespread availability of digital road maps previously designed for navigational devices, we propose a predictive bandwidth reservation scheme built upon these timely opportunities. In contrast to the common practice of utilizing only incoming handoff predictions at each cell to compute the reservations, our scheme is more efficient as it innovatively utilizes both incoming and outgoing handoff predictions; it can meet the same target handoff dropping probability by blocking fewer new calls. The individual base stations are responsible for the computations, which are shown to be simple enough to be performed in real-time. We evaluate the scheme via simulation, along with five other schemes for comparison. Simulation results show that those schemes that rely on positioning information are significantly more efficient than those that do not. Our scheme's additional use of the road topology information further improves upon this advantage, bringing the efficiency closer to the bound set by a benchmark scheme that assumes perfect knowledge about future handoffs

Dynamic bandwidth reservation for label switched paths: An on-line predictive approach

Managing the bandwidth allocated to a Label Switched Path in MPLS networks plays a major role for provisioning of Quality of Service and efficient use of resources. In doing so, two main contrasting factors have to be considered: not only the bandwidth should be adapted to the traffic profile but also the effort for bandwidth renegotiation associated with a variation of the allocated bandwidth should be kept at low levels. In this context, we formulate a problem of optimal LSP bandwidth reservation as the one of minimizing a convex combination of the difference between the assigned bandwidth and the estimated future traffic, and of a measure of the frequency of bandwidth variations. The contribution of this paper is to propose a new method to reserve optimally the bandwidth of an LSP, avoiding an excess of bandwidth renegotiations on the basis of prediction of future traffic, assuming a simple birth-and-death model to describe the traffic dynamics. Whenever the prediction is inaccurate due to unpredictable variations in the characteristics of real traffic, a suitable “emergency procedure” is proposed, which performs a new traffic prediction and a consequent modified bandwidth reservation. Numerical results are presented which show the effectiveness of the method and the achieved performance, both for simulated and real data traffic.

SLA brokering and bandwidth reservation negotiation schemes for QoS-aware internet

We present a novel Service Level Agreement (SLA)-driven service provisioning architecture, which enables dynamic and flexible bandwidth reservation schemes on a per-user or per-application basis. Various session level SLA negotiation schemes involving bandwidth allocation, service start time and service duration parameters are introduced and analyzed. The results show that these negotiation schemes can be utilized for the benefit of both end users and network providers in achieving the highest individual SLA optimization in terms of key Quality of Service (QoS) metrics and price. The inherent characteristics of software agents such as autonomy, adaptability and social abilities offer many advantages in this dynamic, complex, and distributed network environment especially when performing Service Level Agreements (SLA) definition negotiations and brokering tasks. This article also presents a service broker prototype based on Fujitsu's Phoenix Open Agent Mediator (OAM) agent technology, which was used to demonstrate a range of SLA brokering scenarios.

A dynamic multiple-threshold bandwidth reservation (DMTBR) scheme for QoS provisioning in multimedia wireless networks

Next-generation wireless networks target to provide quality of service (QoS) for multimedia applications. We study the wireless systems that support two QoS requirements: keeping the handoff dropping probability less than a predefined QoS threshold while maintaining relative priorities for different traffic classes based on blocking probability. To achieve this goal, a dynamic multiple-threshold bandwidth reservation (DMTBR) scheme, which is capable of granting differential priorities to different traffic classes and to new and handoff traffic for each class by dynamically adjusting bandwidth reservation thresholds, is proposed. In this scheme, the thresholds are obtained in two steps. The initial values are estimated based on instantaneous network traffic situation, then the thresholds will be further adapted according to the instantaneous network QoS status. In times of network congestion, a preventive measure is taken to throttle the new connections. Another contribution of this paper is to generalize the concept of relative priority and hence give the network operator more flexibility to adjust admission control policy by taking into account some dynamic factors such as offered load. The extensive simulations are conducted for two purposes. First, we verify the performance of the proposed scheme and show our scheme performs well under various traffic loads. Second, we demonstrate that the DMTBR scheme gains more advantages when taking the offered load into consideration.

Evaluating the performance of the dynamic bandwidth reservation method using link utilization information in automatic transfer mode local area networks

AbstractWith the improvement of the speed of computers in recent years, there is required a local area network (LAN) that can realize a high‐speed broadband communication. For this purpose, asynchronous transfer mode (ATM) LANs based on ATM technique is considered important.This paper considers the bandwidth reservation control as a means of traffic control in ATM LAN and evaluates the performance by simulation. The evaluation is made for the following methods of congestion control: ACK/NACK method, based on the ACK/NACK signal which is returned when the bandwidth reservation succeeds/fails; the dynamic ACK/NACK method, which is an improvement so that the control can be adapted to the traffic load; and control method based on the link information from the switch.It is shown for the single‐stage switching network that the dynamic ACK/NACK method has a better performance when the traffic is low but the control method based on the link information has the highest performance when the traffic is high. It also is shown for the three‐stage switching network that the control method based on the link information has the highest performance.