Call Admission Control Mechanism Research Articles

Analytical Model of the Connection Handoff in 5G Mobile Networks with Call Admission Control Mechanisms.

Handoff mechanisms are very important in fifth-generation (5G) mobile networks because of the cellular architecture employed to maximize spectrum utilization. Together with call admission control (CAC) mechanisms, they enable better optimization of bandwidth use. The primary objective of the research presented in this article is to analyze traffic levels, aiming to optimize traffic management and handling. This article considers the two most popular CAC mechanisms: the resource reservation mechanism and the threshold mechanism. It presents an analytical approach to occupancy distribution and blocking probability calculation in 5G mobile networks, incorporating connection handoff and CAC mechanisms for managing multiple traffic streams generated by multi-service sources. Due to the fact that the developed analytical model is an approximate model, its accuracy was also examined. For this purpose, the results of analytical calculations of the blocking probability in a group of 5G cells are compared with the simulation data. This paper is an extended version of our paper published in 17th ConTEL 2023.

Advanced Considerations Concerning Impact of Applied Call Admission Control Mechanisms on Traffic Characteristics in Elastic Optical Network Nodes

Over the past few years, a significant increase in network traffic volumes has been observed. The ever growing bandwidth demands mean that a reliable and optimum service level needs to be ensured in communication systems for specific traffic categories. Optimal allocation and use of resources may be achieved through the use of call admission control (CAC) mechanisms implemented in network systems. The resource reservation mechanism and the threshold mechanism are two of the most popular CAC methods. In the reservation mechanisms, a certain number of resources is reserved for selected (predefined) services only. In the case of threshold mechanisms, the number of resources allocated to individual traffic classes depends on the network load. This article discusses the results of simulations verifying the impact of applied CAC mechanisms on the traffic characteristics in elastic optical network (EON) nodes with a Clos structure. Loss probability results obtained with the use of the simulator are presented as well.

CO-CAC: A new approach to Call Admission Control for VoIP in 5G/WiFi UAV-based relay networks

Voice over IP (VoIP) requires a Call Admission Control (CAC) mechanism in WiFi networks to preserve VoIP packet flows from excessive network delay or packet loss. Ideally, this mechanism should be integrated with the operational scenario, guarantee the quality of service of active calls, and maximize the number of concurrent calls. This paper presents a novel CAC scheme for VoIP in the context of a WiFi access network deployed with Unmanned Aerial Vehicles (UAVs) that relay to a backhaul 5G network. Our system, named Codec-Optimization CAC (CO-CAC), is integrated into each drone. It intercepts VoIP call control messages and decides on the admission of every new call based on a prediction of the WiFi network’s congestion level and the minimum quality of service desired for VoIP calls. To maximize the number of concurrent calls, CO-CAC proactively optimizes the codec settings of active calls by exchanging signaling with VoIP users.We have simulated CO-CAC in a 50m × 50m scenario with four UAVs providing VoIP service to up to 200 ground users with IEEE 802.11ac WiFi terminals. Our results show that without CAC, the number of calls that did not meet a minimum quality level during the simulation was 10% and 90%, for 50 and 200 users, respectively. However, when CO-CAC was in place, all calls achieved minimum quality for up to 90 users without rejecting any call. For 200 users, only 25% of call attempts were rejected by the admission control scheme. These results were narrowly worse when the ground users moved randomly in the scenario.

EMSC: a joint multicast routing, scheduling, and call admission control in multi-radio multi-channel WMNs

This paper deals with the problem of joint multicast routing, scheduling, and call admission control in multiradio multi-channel wireless mesh networks. To heuristically solve this problem, we propose a cross-layer algorithm named “extended MIMCR with scheduling and call admission control phases (EMSC)”. Our model relies on the on-demand quality of service (QoS) multicast sessions, where each admitted session creates a unique tree with a required bandwidth. The proposed scheme extends the MIMCR algorithm to fairly schedule multiple non-interfering transmissions in the same time slot. It also exploits a call admission control mechanism to protect the QoS requirements of the multicast traffics. EMSC reduces the number of occupied time slots, with consideration of spatial reuse, both Intra-flow and Inter-flow interferences, and selecting the minimum-interference minimum-cost paths. This subsequently leads to better radio resource utilization and increases the network throughput. Simulation results show that the proposed algorithm outperforms the other algorithms and improves the network performance.

B&W Call Admission Control for Multimedia Communication Networks

In the multimedia communication networks providing quality of service (QoS), an interface between the signal processing systems and the communication systems is the call admission control (CAC) mechanism. Owing to the heterogeneous traffic produced by diverse signal processing systems in a multimedia communication network, the traditional CAC mechanism that used only one CAC algorithm can no longer satisfy the aim of QoS CAC: Utilize the network resource to the most best and still satisfy the QoS requirements of all connections. For satisfying the aim of QoS CAC in the multimedia communication networks, this study proposed an innovative CAC mechanism called black and white CAC (B&W CAC), which uses two CAC algorithms. One of them is called black CAC controller and is used for the traffic with specifications more uncertain, which is called black traffic here. The other is call white CAC controller and is for the traffic with clearer specifications, which is call white traffic. Because white traffic is simple, an equivalent bandwidth CAC is taken as the white CAC. On the other hand, a neural network CAC (NNCAC) is employed to be the black CAC to overcome the uncertainty of black traffic. Furthermore, owing to more parameters needed in a QoS CAC mechanism, a hierarchical NNCAC is proposed instead of the common used NNCAC. Besides to accommodate more parameters, a hierarchical NNCAC can keep the complexity low. The simulation results show the B&W CAC can obtain higher utilization and still meet the QoS requirements of traffic sources.

An Improved Call Admission Control Mechanism with Prioritized Handoff Queuing Scheme for BWA Networks

Nowadays, due to increased demand for using the Broadband Wireless Access (BWA) networks in a satisfactory manner a promised Quality of Service (QoS) is required to manage the seamless transmission of the heterogeneous handoff calls. To this end, this paper proposes an improved Call Admission Control (CAC) mechanism with prioritized handoff queuing scheme that aims to reduce dropping probability of handoff calls. Handoff calls are queued when no bandwidth is available even after the allowable bandwidth degradation of the ongoing calls and get admitted into the network when an ongoing call is terminated with a higher priority than the newly originated call. An analytical Markov model for the proposed CAC mechanism is developed to analyze various performance parameters. Analytical results show that our proposed CAC with handoff queuing scheme prioritizes the handoff calls effectively and reduces dropping probability of the system by 78.57% for real-time traffic without degrading the number of failed new call attempts. This results in the increased bandwidth utilization of the network.

<sup></sup>Medium Access Control Layer Design and Simulation for 802.16 System

In order to analyze transmission performance of broad band wireless communication system based on 802.16 protocol, address the key issues of QoS scheduling algorithm, and network congestion, etc, we present our design of WiMAX medium access control (MAC) layer based on 802.16 protocol in this paper. The implemented design comprises the service-specific convergence sub-layer (CS), the MAC common part sub-layer (CPS), a call admission control mechanism, and a scheduler. In the next simulation experiment, we tested the throughput and average delay of the system which we designed under the conditions in different time or number of clients. The design and simulation had provided a platform and foundation for further to improve the efficiency of bandwidth management algorithm, scheduling algorithm, QoS management, and enhancing the performance of WiMAX systems.

QoS based Adaptive Admission Control Algorithm for Wireless Multimedia Networks

In wireless multimedia networks, the process of offering Quality of Service (QoS) guaranteed multimedia services becomes more challenging owing to the limited bandwidth, dynamic environment and mobility. This problem can be overcome by a call admission control mechanism that restricts the network access based on resource availability. In this paper QoS based Adaptive admission control algorithm for wireless multimedia networks is proposed. Initially the calls entering the network cell are categorized as real time handoff calls, non-real time handoff calls and new calls which are handled in the similar progression. In common, any call category entering the cell undergoes bandwidth test and when the bandwidth value is satisfied, the call is admitted. Otherwise cell performs different cell resizing technique for respective call categories. The proposed work is implemented in Network simulator (NS-2). It is shown that the proposed admission control algorithm achieves better bandwidth utilization, fairness with reduced call dropping rate, when compared with the existing technique. A mobile cellular architecture based on WCDMA is considered for implementation of this technique. Conclusion The proposed methodology prevents call rejection thereby avoid data losses.

Evaluation of wimax admission control algorithms in mobile voip scenarios with batch arrivals and nbldpc fec

Abstract This paper presents results of assessing quality of VoIP conversations in WiMAX networks using the nbLDPC (non-binary Low- Density Parity-Check) FEC in mobility scenarios that are based on the real world terrain charactristics around simulated BS. System under test (SUT) is instrumented with three Call Admission Control (CAC) mechanisms (namely EMAC, ARAC and nsc-ARAC). These algorithms are evaluated against controlling the VBR traffic that comes with burst arrivals. The first algorithm relies on calculating simple exponential weighted moving average (EWMA) of the overall resource consumption whereas the other two ARAC algorithms perform calculations discerning between the new, the ongoing and the finishing connections thus providing more accurate resource estimations (but the ARAC tracks the history of requests as well). In order to evaluate their performance authors rely on a cell-level based simulation environment that relies on the cooperative use of well known simulators - ns2 and Matlab. Previous work in the field is enhanced by improving the fidelity of proposed IEEE 802.16 simulator. Authors demonstrate the influence of increasing number of arrivals per one batch as well as testing the "zero hour" scenario (system saturation). In order to include nbLDPC codes in SUT’s mobile channels, a method called Link-To-System interface (L2S) has been implemented.

LTE-Advanced 시스템에서 M2M 통신의 최대 지연시간을 고려한 호 수락 방법

에너지 소비의 효율화를 위한 그린 기술로서 스마트 그리드와 지능형 교통 시스템 등이 주목받고 있다. 이러한 기술의 구현에는 다수의 센서, 액츄에이터 (actuator), 그리고 컨트롤러들이 필요하다. 이러한 구성요소들 간의 machine-to-machine (M2M)통신의 중요성은 높아지고 있다. M2M 통신의 특징은 다수의 machine-type-communication(MTC) 디바이스들이 참여하고, 통신 트래픽 패턴과 QoS 요구조건이 다양하다는 것이다. 이러한 M2M 통신을 효율적으로 지원하기 위한 호 수락 방법들에서는 동일한 시간관련 QoS 조건을 갖는 MTC 디바이스들을 클러스터 단위로 그룹핑하고, QoS 조건 만족여부에 따라 호 수락을 결정하는 방법을 제안하였다. 하지만 이 방법은 데이터 전송주기와 최대 전송지연 시간이 같을 경우에만 적용 가능하다. 본 논문에서는 이러한 제한 없이 사용할 수 있는 방법을 제안한다. 또한 전송 주기와 최대 전송지연 시간이 특별한 관계에 있을 때 최적화할 수 있는 호 수락 제어방법을 제안한다. 제안방법의 QoS 만족 적합성에 대한 증명을 제시하였고, 시뮬레이션을 통해 실제 동작 가능하고, 기존 방법들보다 호 수락 확률에서 우수함을 보였다. Smart grid and intelligent transportation system draw significant interest since they are considered as one of the green technologies. These systems require a large number of sensors, actuators, and controllers. Also, machine-to-machine (M2M) communications is important because of the automatic control. The LTE-Advanced networks is preparing a set of functions that facilitate the M2M communications, and particularly the development of an efficient call admission control mechanism is critical. A method that groups MTC devices according to QoS constraints and determines the admission depending on the QoS satisfaction is limitedly applied only if the data transmission period and the maximum delay are identical. This paper proposed a call admission control that is free from such limitation and also optimizes the admission process under the certain condition of the transmission period and maximum delay. The theorems regarding the proposed method are presented with the proofs. The simulations confirms its validity and shows it is better in call admission probability than existing works.

Adaptive Quality of Service Provisioning in IEEE 802.11 Wireless Local Access Network

–This paper provides a cross-layer Quality of Service (QoS) provisioning scheme for IEEE 802.11 Wireless Local Area Network (WLAN). Specifically, we develop a new scheduling algorithm in link layer and a call admission control mechanism in network layer to support multimedia services. Instead of using a single coordination function in link layer, we adopt polling scheme to support real-time (RT) services while using EDCF contention-based function for nonreal- time (NRT) services, based on wireless channel condition and service fairness. The proposed polling algorithms search idle system time and use it to reduce average packet loss of RT variable-bit-rate (VBR) services, as well as satisfying transmission delay and bandwidth requirements of all RT services. The admission control mechanism provides long-term quality for both RT and NRT services by ensuring low average packet loss ratio for RT services and acceptable minimum throughput for NRT services. Service priority and fairness are achieved by assigning VBR bursts higher priority for resource allocation based on their weighting values. Fairness is also implemented by reserving resource for NRT to avoid possible starvation. Rate allocation for VBR connections are adaptively adjusted with sliding window measurement. Detailed analysis is given by taking into account several key statistical factors, such as service traffic model, the ratio between the polling period and the contention period (CP), burst generation probabilities, and wireless propagation model. Performance is evaluated through OPNET simulation. Both numerical and simulation results demonstrate that our proposed joint scheme is effective in terms of both system resource utilization and QoS provisioning.

Hybrid Adaptive Call Admission Control Mechanism for Ensuring QoS in 3GPP: LTE Networks

Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) system is targeted to efficiently guarantee the quality of service (QoS) of services such as audio/video streaming, gaming and Voice over IP (VoIP). So the system resource allocation should obtain the multiuser diversity gain making full use of the channel condition, and take the quality of service (QoS) of different services into account. Due to the heavy user’s space and limited Resource Block (RBs), it is infeasible to guarantee all ongoing users' QoS. Then, some call are blocked and lost. The proposed method reduces the handoff blocking probability in LTE wireless networks. Hybrid Adaptive call admission control scheme performs the QoS operation based on the priority at the time of call admission. This method reduces new call blocking probability.

A dynamic QoS provisioning call admission control in cellular mobile using fuzzy logic

Call Admission Control (CAC) is a fundamental mechanism used for Quality of Service (QoS) provisioning in cellular mobile networks. An effective CAC scheme needs to be adaptive to the changing traffic patterns and thus dynamic approach is preferred. Unlike the conventional CAC schemes, the present paper proposes a scheme that does not use complicated analytical models. Instead it is based on the fuzzy logic control and supports heterogeneous traffic applications like voice, data, etc. In the proposed mechanism, the amount of guard channels to reserve are controlled dynamically on the basis of varying network parameters like call dropping probability, network load, etc. and also takes into account of diverse classes of traffic applications. Analysis showed that the proposed fuzzy logic-based mechanism demonstrated better performance compared to the fixed channel reservation scheme. The results also revealed that fuzzy logic-based CAC mechanism achieved higher channel utilisation while maintaining the required QoS for different classes of applications.

Improving quality of experience in wireless VoIP through novel call scheduling

In the last few years we have experienced a dramatic increase in the use of IP networks for voice applications (VoIP) over wireless networks due to increased bandwidth availability and enhanced device capabilities. Since demand often exceeds available capacity, Call Admission Control mechanisms are in place to prevent the uncontrolled usage of bandwidth. Through the use of an intermediary gateway, VoIP calls are in many cases terminated to a normal landline or cellphone; the capacity of such a gateway is also a finite resource since the number of users can vary significantly as many are mobile. In this article we propose an enhanced scheme that aims to manage access to the lines available so that they are used in a fair manner and utilized to the highest degree possible. This management is facilitated by enhancing a proxy implementation with a number of call scheduling policies. The ability to satisfy pending call requests as soon as lines become available, results in increased user service satisfaction. Moreover, it increases line utilization which is crucial from an economic viewpoint. The ultimate goal is to improve Quality of Experience which is deemed as highly important especially considering that wireless network users experience opportunistic and intermittent connectivity.

Dynamic Preemption Call Admission Control Scheme Based on Markov Decision Process in Traffic Groomed Optical Networks

In optical grooming networks, the capacity fairness issue can be resolved by utilizing a call admission control (CAC) mechanism. Existing CAC schemes are generally based on one of four different techniques, namely, static bandwidth reservation, static threshold setting, mathematical statistics, and Markov decision processing without buffer implementation (NB). However, irrespective of the technique used, a trade-off exists between the network fairness and the network throughput. In our previous work, a conditional-preemption CAC (CP-CAC) mechanism was proposed to increase the network throughput while simultaneously maintaining the fairness. However, a CP-CAC mechanism considers only the blocking probability at particular instants of preemption. This paper proposes the use of a dynamic-preemption call admission control scheme (DP-CAC) to decide whether or not to preempt existing requests based on the optimal policy derived from a Markov decision process. Similar to CP-CAC, the DP-CAC method is also based on a dynamic threshold setting concept and is implemented using a single connection buffer and an associated set of virtual indicators. The simulation results show that compared to the CP-CAC mechanism, the proposed DP-CAC further improves the network throughput without sacrificing the fairness. Additionally, the average waiting time induced by the buffer implementation for DP-CAC is just 0.23 time units shorter compared to 0.25 for CP-CAC. Finally, it is shown that the proposed method also ensures fairness in a variety of common network topologies including 6 × 6mesh-torus, NSF, and Cost239.

IPv6-Based Dynamic Quality of Service Control Strategy for Wireless Network

On the basis of the architecture for fast handover of hierarchical IPv6, a coordinated call admission control mechanism was presented, providing an end-to-end RSVP context transfer for real-time applications to overcome t he weakness of the context transfer protocol which cannot meet the need of end-to-end QoS mechanisms because the contexts were only transferred between the previous and new access routers. The mechanism decreased the delay caused by re-initiate QoS signaling from scratch to reestablish QoS forwarding process, and minimized the handover service disruption. The signaling overhead and handover latencies could be reduced by adopting t he fast handover for hierarchical IPv6 architecture. The approach was compared with the re-initiating RSVP signaling to reestablish QoS states using network simulator ns2. The numerical results showed that the scheme has the less latency and packet loss than that of the re-initiating approach.

Fair admission control scheme based on conditional preemption in traffic-groomed optical networks

In optical-grooming networks, the capacity fairness issue can be resolved by utilizing a call admission control mechanism. Existing call admission control schemes are generally based on one of the four different techniques, namely static bandwidth reservation (SBR), static threshold setting (STS), mathematical statistics (MS), and Markov decision processing without buffer implementation (NB). However, irrespective of the technique used, a tradeoff exists between the network fairness and the network throughput. Accordingly, this article presents a conditional-preemption call admission control (CP-CAC) scheme designed to increase the network throughput while simultaneously maintaining the fairness. The CP-CAC method is based on a dynamic threshold setting concept and is implemented using a single connection buffer (C-Buf) and a set of virtual buffers (V-Bufs). In general CAC mechanisms, if the residual bandwidth is sufficient to satisfy a new request but some requests are already buffered, the new request can be treated in two different modes, i.e. with-preemption (WP) or without-preemption (NP). In contrast, in the CP-CAC scheme proposed in this study, a conditional-preemption (CP) mode is proposed in which statistical information about the blocking probability is used to determine the preempt (or not) decision. The simulation results show that compared to the NB call admission control mechanism, the proposed CP-CAC scheme improves the network throughput without sacrificing the fairness. In addition, the average waiting time induced by the buffer implementation is just 0.25 time units. Finally, it is shown that the proposed method ensures fairness in a variety of common network topologies, including 6 × 6 mesh-torus, NSF, and Cost 239.

Quality of Service Aware Call Admission Control in Cell Based Multi-Service Photonic Network

The article tackles the problem of quality of service assurance in photonic networks. The idea of multi-servicephotonic network model with the coexistence of optical circuit and packet switching mechanisms and cell communication is used as a basis for service differentiation in the optical domain. Cell loss ratio as a key performance indicator determines the required optical switching mechanism. Service provisioning is performed using call admission control mechanism with real-time cell loss ratio estimation procedure. Service blocking probability calculation utilizes discrete event simulation of service provision and teardown requests applied to core network topology from COST 266 project. Three simulation scenarios are included in the analysis – pure optical packet switching network, and coexistence of optical packet and circuit switching with and without possibility of communication redirection between the switching mechanisms. Simulation scenarios are additionally altered with the cell loss ratio constraint and number of delay lines.

Call Admission Control for Next Generation Wireless Networks Using Higher Order Markov Model

The Next generation wireless networks (NGWN) will be heterogeneous which will have different radio access technologies (RATs) operating together. The Radio Resource Management (RRM) is one of the key challenges in NGWN. The Call admission control (CAC) mechanism is one of the Radio Resource Management technique plays instrumental role in ensuring the desired QoS to the users working on different applications which are having the diversified nature of QoS requirements to be fulfilled by the wireless networks. One of the key challenges to be addressed in this prevailing scenario is the distribution of the available channel capacity amongst the multiple traffic with different bandwidth requirements so as to guarantee the QoS requirements of the traffic .The call blocking probability is one such QoS parameter for the wireless network and for better QoS it is desirable to reduce the call blocking probability. In this customary scenario it is highly advantageous to bring about an analytic Performance model. In this paper we propose a call admission control framework based on higher order Markov chains to effectively handle the call blocking probability in NGWN and to provide optimal QoS for the mobile users. In the proposed algorithm we have considered three classes of traffic having different QoS requirements. The results obtained from the Performance model are encouraging and optimistic and indicates the need of an intelligent decision making system for CAC.

Pricing-based call admission control for wireless MPEG-4 traffic

Next generation wireless technologies will need to incorporate new sets of traffic control procedures in order to cope with the challenges related to supporting both the existing and the ever-increasing new multimedia services. The work presented in this paper focuses on traffic control for MPEG-4 videoconference over cellular networks, and is twofold. We first introduce a traffic model for medium quality MPEG-4 videoconference traffic. We then proceed to use this model, as well as a previously developed model for high quality MPEG-4 traffic, in the implementation of a new Call Admission Control (CAC) mechanism. Providers need to use efficient resource management mechanisms in order to keep existing clients satisfied and attract new customers, so that they can increase their revenue. Towards this goal, our CAC mechanism makes decisions on the acceptance/rejection of a new video call not only based on the predicted capacity that users will consume, but also on the possible revenue gained for the provider when degrading current users in order to accommodate new ones. Our mechanism is implemented with both a static and a dynamic pricing policy and is shown, via an extensive simulation study, to provide excellent Quality of Service (QoS) to wireless videoconference users.