Proposed Call Admission Control Scheme Research Articles

Performability analysis of multi-service call admission control schemes in LTE networks

Two important Quality-of-Service (QoS) measures for cellular networks are the fractions of New Calls (NCs) and Handoff Calls (HCs). These types of calls are usually blocked or dropped for two reasons: radio channels are occupied (performance reason) or failure of radio channels (availability reason). Call Admission Control (CAC) is a technique that accepts or rejects user requests in a network. This paper proposes two new CAC schemes for Long Term Evolution (LTE) networks supporting two classes of services (Real-Time (RT) and Non-Real-Time (NRT)). The proposed CAC schemes are composites, meaning that they consider performance changes associated with the failure and recovery of radio channels. We use the Probabilistic Model Checking (PMC) to perform a comparative analysis between the performability measures (combination of performance and availability measures) of the proposed composite CAC schemes and an existing pure performance model. First, we model the composite CAC schemes with multidimensional Continuous Time Markov Chain (CTMC). Then, we specify QoS requirements through the CTMC using the Continuous-time Stochastic Logic (CSL). Finally, we quantify the performability measures of the composite CAC schemes by checking CSL steady-state, transient, and path formulas using the PRISM model checker.

A call admission control scheme on the uplink of D2D communications underlaying cellular networks

AbstractIn device-to-device (D2D) communications, call admission control (CAC) scheme is a crucial problem. In D2D communications, the cellular user equipment (CUE) and D2D user equipment (DUE) pairs share the same channel resource. Hence additional interference is introduced. Meanwhile, the interference has an important impact on the system performance. In this paper, a CAC scheme based on interference analysis is proposed. First, the interference is modeled and analyzed in detail. Then based on the interference analysis, a CAC scheme is proposed. Simulation results show that D2D communications with the proposed CAC scheme can effectively improve system performance in terms of new call blocking probability and capacity. This proposed scheme can be applied to the design and optimization of D2D communications.

Mobility management schemes for real‐time traffic and resource allocation in IEEE 802.16e mobile network

SummaryIn this paper, our aim is to develop in IEEE802.16e Wireless Networks with link adaptation, in the presence of real‐time traffic call admission control (CAC) schemes. These CAC propose various scenarios of resource splitting and handling the intracell mobility. In particular, we consider two types of intracell mobility classes : low mobility class for mobiles moving usually with low speed between the neighboring regions of the cell and high mobility class for those moving with high speed and that can skip more than one region before changing their modulation. For this reason, we assume a time threshold Tth that determines the minimum time a call must remain in a region before the base station changes its modulation. And we compare it with the time that a call may spend in a region to decide whether the base station will change its modulation or not.In the beginning, we introduce two CAC schemes. In the first one, we reserve a portion of resources to mobiles in migration with both high and low mobility. And in the second one, we give the priority just to mobiles in migration with high mobility. Then, we calculate the impact in the blocking and dropping probabilities. We show by numerical results that by the proposed CAC schemes, we can find a resource management that outperforms well under different types of mobility. But, to find a good tradeoff between dropping the calls in migration and blocking the new calls, we introduce the optimization problem in the second part. So, we are faced to the necessity of optimizing the results found in the first part. Therefore, we define an objective function to optimize, in order to ensure the highest quality of service for users and to give a better stability state between the dropping and blocking probability. We show that the proposed objective function gives the optimal resources allocation between the migrating and new arriving calls in the cell. Copyright © 2015 John Wiley & Sons, Ltd.

A new CAC and packet scheduling scheme for mobile WiMAX networks

ABSTRACTAs the wireless network technology evolves, IEEE 802.16 standard, also known WiMAX (Worldwide Interoperability for Microwave Access) appears as a great competitor to GSM, 3G, even IEEE802.11 networks. The coverage of this technology is expanded up to 50 km. It is claimed to provide a transmission rate up to 70 Mbps while respecting the QoS (Quality of Service) mechanism. However, the call admission control (CAC), scheduling and bandwidth allocation mechanisms were not defined and left as an open issue. In this paper, we introduce a CAC scheme and a scheduling algorithm for IEEE802.16e Mobile WIMAX. An efficient token bucket based CAC and uplink packet scheduling scheme is introduced in order to satisfy bandwidth guarantees to all service flow and delay guarantees to real time service flows. The proposed solution is practical and compatible to the IEEE 802.16 standard as it provides the QoS of different traffic classes especially best effort traffic by avoiding its starvation as is specified in major previous works. An analytical model and simulation results are developed in order to validate the proposed CAC scheme and the scheduling algorithm. By numerical results, we show that our proposed scheme is compatible to the IEEE 802.16 standard as it performs significantly the best effort traffic without violating QoS performance of other service classes.Copyright © 2013 John Wiley & Sons, Ltd.

Heterogeneous voice flows-oriented call admission control in IEEE 802.11e WLANs

Considering the circumstance of heterogeneous voice flows, first, by applying Markov chain, this paper proposes an unsaturated analytical model for the IEEE 802.11e EDCA protocol, which considers the condition of non-ideal transmission channel and the character of the occurrence of backoff countdown at the beginning of time slot in EDCA protocol. Furthermore, according to the proposed model, the media access delay and throughput of a flow are analysed, and the flow-oriented call admission control (CAC) scheme is proposed. Finally, the simulation results are shown to confirm that the proposed CAC scheme can guarantee the requirements of throughput and delay of voice flows, and can admit more voice flows to improve the utilisation efficiency of network resources by choosing the appropriate values of the minimum contention window or the appropriate varieties of voice flows.

A Dynamical Hybrid CAC Scheme and Its Performance Analysis for Mobile Cellular Network with Multi-Service

Call admission control (CAC) plays an important role in mobile cellular network to guarantee the quality of service (QoS). In this paper, a dynamic hybrid CAC scheme with integrated cutoff priority and handoff queue for mobile cellular network is proposed and some performance metrics are derived. The unique characteristic of the proposed CAC scheme is that it can support any number of service types and that the cutoff thresholds for handoff calls are dynamically adjusted according to the number of service types and service priority index. Moreover, timeouts of handoff calls in queues are also considered in our scheme. By modeling the proposed CAC scheme with a one-dimensional Markov chain (1DMC), some performance metrics are derived, which include new call blocking probability ( P nb ) , forced termination probability (PF), average queue length, average waiting time in queue, offered traffic utilization, wireless channel utilization and system performance which is defined as the ratio of channel utilization to Grade of Service (GoS) cost function. In order to validate the correctness of the derived analytical performance metrics, simulation is performed. It is shown that simulation results match closely with the derived analytic results in terms of Pnb and PF. And then, to show the advantage of 1DMC modeling for the performance analysis of our proposed CAC scheme, the computing complexity of multi-dimensional Markov chain (MDMC) modeling in performance analysis is analyzed in detail. It is indicated that state-space cardinality, which reflects the computing complexity of MDMC, increases exponentially with the number of service types and total channels in a cell. However, the state-space cardinality of our 1DMC model for performance analysis is unrelated to the number of service types and is determined by total number of channels and queue capacity of the highest priority service in a cell. At last, the performance comparison between our CAC scheme and Mahmoud ASH’s scheme is carried out. The results show that our CAC scheme performs well to some extend.

Bandwidth borrowing-based QoS approach for adaptive call admission control in multiclass traffic wireless cellular networks

SUMMARY This paper proposes a QoS approach for an adaptive call admission control (CAC) scheme for multiclass service wireless cellular networks. The QoS of the proposed CAC scheme is achieved through call bandwidth borrowing and call preemption techniques according to the priorities of the traffic classes, using complete sharing of the available bandwidth. The CAC scheme maintains QoS in each class to avoid performance deterioration through mechanisms for call bandwidth degradation, and call bandwidth upgrading based on min–max and max–min policies for fair resource deallocation and reallocation, respectively. The proposed adaptive CAC scheme utilizes a measurement-based online monitoring approach of the system performance, and a prediction model to determine the amount of bandwidth to be borrowed from calls, or the amount of bandwidth to be returned to calls. The simulation-based performance evaluation of the proposed adaptive CAC scheme shows the strength and effectiveness of our proposed scheme. Copyright © 2011 John Wiley & Sons, Ltd.

Call Admission Control Jointly with Resource Reservation in Cellular Wireless Networks

To efficiently utilize the total resources and to serve mobile users demanding for different types of service, system resource utilization of these services should be considered, and efficient resource management techniques should be developed. In this paper, we propose a new call admission control (CAC) scheme jointly with resource management by considering the two service types: prioritized calls and nonprioritized calls. Proposed scheme limits the new and handoff prioritized and non-prioritized call arrivals according to call-level quality of service (QoS) requirements. By searching algorithm, admission parameters are obtained optimally and required QoS are guaranteed. Due to high priority of the prioritized calls, the admittance of non-prioritized calls into channel is restricted, while prioritized calls are admitted as long as there is sufficient bandwidth. To evaluate the performance of the proposed CAC scheme, we have compared the numerical results from the analytical model with those of New Call Bounding scheme. It is shown that the proposed CAC scheme uses the resources effectively and improves all the upper-bound QoS requirements with respect to the New Call Bounding scheme for prioritized and non-prioritized users.

A Simple Critical-Load-Based CAC Scheme for IEEE 802.11 DCF Networks

This paper proposes a simple and practical call admission control (CAC) scheme for one-hop IEEE 802.11 distributed coordination function (DCF) networks in heterogeneous environments. The proposed scheme is the first CAC scheme derived from an asymptotic analysis of the critical traffic load, where the critical traffic load represents the threshold for queue stability. The salient feature of our CAC scheme is that it can be performed quickly and easily without the need for network performance measurements and complex calculations. Using the proposed scheme, we specifically investigate the voice capacity of 802.11 DCF networks with unbalanced traffic. Extensive simulations covering both ad hoc and infrastructure-based networks, and a variety of nonsaturated traffic types, show that the proposed CAC scheme is very effective.

Call admission control with heterogeneous mobile stations in cellular/WLAN interworking systems

Abstract Although different call admission control (CAC) schemes have been proposed for cellular-wireless local area network (WLAN) interworking systems, no studies consider mobile stations (MSs) only with a single interface (for either WLANs or cellular networks) and thus these MSs will experience higher call blocking and dropping probabilities. In this article, we propose a new CAC scheme that considers both the MSs with a single interface and with dual interfaces. By employing the concept of guard-bands, the proposed CAC scheme gives higher priority to MSs with a single interface than those with dual interfaces to accommodate more MSs. The call blocking and dropping probabilities are analyzed using Markov chains and how to determine appropriate guard bands for CAC is investigated through cost minimization problems. Analytical and simulation results demonstrate that the proposed scheme can achieve lower blocking probabilities compared with existing schemes that do not include single interface MSs.

A dynamic joint scheduling and call admission control scheme for IEEE 802.16 networks

We propose a dynamic joint scheduling and call admission control (CAC) scheme for service classes defined in IEEE 802.16 standard. Using priority functions, equipped with service weights and service arrival rates, the proposed scheduling scheme differentiates service classes from each other. Based on obtained priority values, we first allocate the achievable bandwidth proportionally. Within individual service classes, we then use appropriate local schedulers to transmit packets accordingly. Moreover, instead of immediate admitting or blocking a new connection request, the proposed CAC scheme computes the average transmission rate that can be allocated to that connection during a time interval. The connection is admitted if its required rate is satisfied while at the same time QoS requirements of ongoing connections are not violated. Our numerical results demonstrate the effectiveness of the proposed schemes compared to the other schemes in the literature.

Endpoint-Based Call Admission Control and Resource Management for VoWLAN

This paper examines two specific aspects of resource management in Wireless Local Area Networks (WLANs)-Call Admission Control (CAC) and handling of Link Adaptation (LA) events. A self-consistent system to manage these for Voice over Internet Protocol (VoIP) over an IEEE 802.11 WLAN is presented. The proposed CAC scheme is based on the Endpoint Admission Control (EAC) paradigm, where the endpoints probe the network to determine if the call can be supported with acceptable Quality of Service (QoS). The proposed scheme was evaluated on an experimental testbed and test results show that correct admission decisions were made under various network configurations. The scheme also determines if LA has resulted in the system becoming congested and, if so, the voice codec of the handset which has undergone LA is adapted so as to restore the system to its earlier state, thereby alleviating the congestion. The proposed scheme was evaluated on the experimental testbed and test results show that the codec adaptation scheme was very effective at overcoming the effects of LA for VoIP over WLAN.

A Bandwidth Efficient Adaptive Call Admission Control Scheme for QoS Provisioning in IEEE 802.16e Mobile Networks

In wireless environment the bandwidth resource is limited and therefore judicious use of the available resources is needed. A bandwidth efficient Call Admission Control (CAC) is proposed in this paper for quality of service (QoS) provisioning for the services defined in IEEE 802.16e mobile WiMAX standards to satisfy both bandwidth and delay guarantees to the admitted connections. The concept of adaptive bandwidth degradation is introduced to improve the bandwidth utilization (BU) of the system. The proposed CAC scheme is analyzed by Markov Chain model and performance evaluation is made in comparison with fixed step size degradation. Results show that the proposed adaptive CAC scheme has excellent BU under stressed network condition. Also the long term average revenue is calculated for different service flows and for the overall system to see the efficiency of the adaptive CAC scheme.

A Novel Call Admission Control Policy Using Mobility Prediction and Throttle Mechanism for Supporting QoS in Wireless Cellular Networks

The decision of call admission becomes an important work owing to the scarce wireless spectrum for wireless cellular networks. If there exists adequate information for call admission control (CAC) schemes, the terms of quality of service (QoS), such as call dropping probability (CDP), call blocking probability (CBP), and system utilization, will be kept in a certain acceptable level. Therefore, a prediction system which can predict most information, such as system utilization and CDP, in advance with a novel data mining technique and a distributed CAC scheme is presented in this paper. Based on the prediction results and the bandwidth consumption of adjacent cells, the proposed CAC scheme is able to decide to admit a new call. The throttle flag that can indicate the usage of current cell is proposed to prevent the newly admitted call request from being blocked in adjacent cells if handoff is needed. The simulation results show that the proposed CAC scheme can maintain the CDP below a predefined threshold, and the CBP is also lower than the cluster prediction and traditional guard channel policies.

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.

A probabilistic approach for fair-efficient call admission control in wireless multiservice networks

The efficiency of call admission control (CAC) schemes in multiclass wireless networks should be evaluated not only with regard to the call blocking probability (CBP) achieved for every service class (SC) supported but also with regard to quality of service (QoS) and network efficiency criteria. In this article, four CAC schemes offering priority to SCs of advanced QoS requirements, based on guard channel policy, are studied and evaluated taking into account fairness and throughput criteria in addition to CBP. For the performance evaluation of the proposed CAC schemes and to examine fairness issues, two fairness indices are introduced along with a throughput metric. The analytical results, validated through extensive simulations, indicate that by appropriate selection of the CAC parameters satisfactory fairness and throughput are achieved while achieving low CBP.

Probabilistic framework and performance evaluation for prioritized call admission control in next generation networks

Next generation networks (NGN) are designed to support a wide range of applications with various service classes (SCs) guaranteeing the respective quality of service (QoS) levels. Since such networks are resource constrained, call admission control (CAC) is imperative to achieve the required QoS levels. In this paper, a new probabilistic framework for CAC schemes is proposed based on controlling each SC independently by admitting low priority SC calls with a variable imposed probability. The incorporation of such a probabilistic framework is considered under a bandwidth-centric approach named probabilistic bandwidth reservation scheme (PBRS). Though equal service times are usually assumed in the literature, the present analysis considers SCs of different service times. By employing Markov chain analysis to treat the independent SCs that correspond to different call specifications, analytical expressions for the call blocking probabilities (CBPs) are derived. The performance of the proposed CAC scheme is studied not only with regard to CBP but, also, taking into account the priorities assigned to different SCs as well as fairness among various SCs and total network throughput. The proposed probabilistic framework allows the dynamic control of network resources considering also priority assignment, fairness and throughput. Analytical results concerning delay tolerant (DT) and delay-non-tolerant (DNT) traffic have been obtained applying the proposed scheme. Moreover, the relevant simulations have verified the accuracy of the proposed analysis.

Admission control scheme of extended rtPS algorithm for VoIP service in IEEE 802.16e with adaptive modulation and coding

The extended real time polling service (ertPS) algorithm is added toIEEE 802.16e-2005 standards so that voice over internet protocol(VoIP) service could use resources efficiently by considering on/offcharacteristic of voice source. The IEEE 802.16e standard employsadaptive modulation and coding (AMC) to maximize transmission rateby assigning variable rate in accordance with the user'stime-varying channel conditions determined mainly by distance frombase station (BS) to mobile subscriber station (MSS). In order toapply AMC, we divide a cell into two zones with different averagesignal-to-noise ratio (SNR) where each zone uses its own onetransmission mode. In this paper, we construct 3-dimensional Markovprocess of M/G/1 type whose steady state probability is obtainedby the matrix analytic method. By using the steady state probabilityof Markov process, we obtain the probability distribution ofqueueing delay and find the admissible region of VoIP users with therequired constraint on delay bound. Next, we propose a calladmission control (CAC) scheme by considering two admissible regionsfor handoff calls and new calls satisfying constraints on delaybound and dropping probability of handoff call. In order to finddropping probability of handoff call and blocking probability of newcall, we construct Markov chain model of proposed CAC scheme atcall-level. By the mathematical results of packet-level andcall-level, we obtain admissible region to admit new call andadmissible region to admit handoff call satisfying the requiredconstraints on delay bound and dropping probability of handoff call.

Mobile-Agent-Based Handoff in Wireless Mesh Networks: Architecture and Call Admission Control

The wireless mesh network (WMN) has recently emerged as a promising technology for next-generation wireless networking. In the WMN, it is crucial to support mobile users roaming around the network without service interruption. This consideration motivates us to develop an efficient fast handoff approach using distributed computing technology. Particularly, we propose a mobile agent (MA)-based handoff architecture for the WMN, where each mesh client has an MA residing on its registered mesh router to handle the handoff signaling process. To guarantee quality of service (QoS) and achieve differentiated priorities during the handoff, we develop a proportional threshold structured optimal effective bandwidth (PTOEB) policy for call admission control (CAC) on the mesh router, as well as a genetic algorithm (GA)-based approximation approach for the heuristic solution. The simulation study shows that the proposed CAC scheme can obtain a satisfying tradeoff between differentiated priorities and the statistical effective bandwidth in a WMN handoff environment.

Providing absolute QoS in an OBS/WR architecture

By employing optical burst switching (OBS) in its metropolitan portion and wavelength routing (WR) in the backbone portion, the hybrid OBS/WR architecture provides end-to-end all-optical connections to end users while inheriting the fine granularity of OBS and the low loss probability of WR. However, the original OBS/WR architecture can provide only relative quality of service (QoS). That is, the burst loss possibilities of high-priority traffic flows are guaranteed to be lower than those of low-priority traffic flows, but the upper burst loss bound cannot be guaranteed with this model. We propose a call admission control (CAC) scheme to provide absolute QoS in an OBS/WR architecture and a dynamical priority allocation algorithm (DPAA) to enhance the blocking probability performance of the proposed CAC scheme. We first analyze the burst loss performance of traffic flows in the OBS/WR architecture. Based on the analytical results, a CAC scheme is proposed to provide absolute burst loss guarantee. Besides the CAC scheme, we also design a DPAA that assigns priorities to incoming traffic flows according to their QoS requirements to further improve the performance. The analysis and simulation results show that the proposed CAC scheme guarantees upper burst loss bound to different traffic flows while achieving significantly higher bandwidth utilization than other existing absolute QoS schemes in conventional OBS networks, and the proposed DPAA can achieve lower blocking probability than the original CAC scheme while maintaining the absolute QoS.