Call Admission Control in Wireless Networks: Probabilistic Approach and Efficiency Evaluation

Call admission control (CAC) is a significant component in wireless networks to guarantee quality-of-service (QoS) requirements and also to enhance the network resilience. In the literature, CAC is normally evaluated by considering the limited bandwidth in the radio interface while the physical fading wireless channel is not considered. This work proposes a cross-layer analytical technique to study a CAC mechanism in wireless networks over Rayleigh fading channel. The tele-traffic parameters are relaxed to follow general distributions in stead of exponential variables for the sake of general applicability in various scenarios. The explicit relationship is derived between the performance metrics and the Rayleigh fading channel characteristics. Numerical investigation demonstrates that the fading channel has a substantial impact on the network performance.

Traditional traffic rate regulation/degradation schemes in call admission control (CAC) seldom take rate degradation optimization into consideration, thus can not obtain the perfect grade of service (GoS) in session layer. In this paper, we propose an enhanced rate degradation CAC (ERDCAC) scheme in multimedia wireless networks, which is an extension and optimization of the rate regulation CAC scheme. We introduce a variable which is a degradation threshold for wide-band traffic (WB) when new narrow-band (NB) connection arrives, and can be adjusted at the start of every monitor period. We develop a Markov model to analyze the ERDCAC, and design a cost function to evaluate its performance. From the result of Markov model analysis, along with the measurements of call arrival rates of all traffics, the threshold variable to acquire the best GoS is obtained. Extensive numeric results illustrate the effectiveness of the ERDCAC compared with traditional rate regulation CAC scheme which is a non-optimization rate degradation scheme.

Elastic threshold-based admission control for QoS satisfaction with reward optimization for servicing multiple priority classes in wireless networks

SUMMARYResource reservation or the other prioritization strategies adopted by Call Admission Control (CAC) schemes in wireless networks lead to unfair resource allocation to users belonging to different service classes (SCs) due to high divergence among the respective call blocking probabilities (CBPs). In this paper, we propose dynamic optimization of probabilistic CAC (P‐CAC) schemes to assure CAC fairness among users of different SCs in wireless networks. The approach is based on users utility combined with fairness optimization, aiming at dynamically determining the probability value in the P‐CAC scheme. This optimal probability is adjusted to network ongoing traffic, CBPs of each SC, prioritization levels characterizing the SCs supported, and the users risk aversion, which reflects their behavior toward the perceived QoS. The existence and uniqueness of the optimal probability that leads to absolute fairness among the users of a wireless network are proven. Copyright © 2012 John Wiley & Sons, Ltd.

The evolution of cellular networks from one generation to another has led to the deployment of multiple radio access technologies (such as 2G/2.5G/3G/4G) in the same geographical area. This scenario is termed heterogeneous cellular networks. In heterogeneous cellular networks, radio resources can be jointly or independently managed. When radio resources are jointly managed, joint call admission control algorithms are needed for making radio access technology selection decisions. This chapter gives an overview of joint call admission control in heterogeneous cellular networks. It then presents a model of load-based joint call admission control algorithm. Four different scenarios of call admission control in heterogeneous cellular networks are analyzed and compared. Simulations results are given to show the effectiveness of call admission control in the different scenarios. The coexistence of different cellular networks in the same geographical area necessitates joint radio resource management (JRRM) for enhanced QoS provisioning and efficient radio resource utilization. The concept of JRRM arises in order to efficiently manage the common pool of radio resources that are available in each of the existing radio access technologies (RATs) (Perez-Romero et al, 2005). In heterogeneous cellular networks, the radio resource pool consists of resources that are available in a set of cells, typically under the control of a radio network controller or a base station controller. There are a number of motivations for heterogeneous wireless networks. These motivations are (1) limitation of a single radio access technology (RAT), (2) users’ demand for advanced services and complementary features of different RATs, and (3) evolution of wireless technology. Every RAT is limited in one or more of the following: data rate, coverage, security-level, type of services, and quality of service it can provide, etc. (Vidales et al, 2005). A motivation for heterogeneous cellular networks arises from the fact that no single RAT can provide ubiquitous coverage and continuous high QoS levels across multiple smart spaces, e.g. home, office, public smart spaces, etc. Moreover, increasing users’ demand for advanced services that consume a lot of network resources has made network researchers developed more and more spectrally efficient multiple access and modulation schemes to support these services. Consequently, wireless networks have evolved from one generation to another. However, due to huge investment in existing RATs, operators do not readily discard their existing RATs when they acquire new ones. This situation has led to coexistence of multiple RATs in the same geographical area.

This paper presents call admission control issues for an ATM-based wireless network with mobile hosts. Such wireless ATM networks are motivated by both an increasing demand for mobile capability for future broadband networks and broadband multimedia services for mobile systems. An ATM compatible wireless network capable of supporting a mix of broadband ISDN services is discussed. We present a conceptual view of a wireless ATM architecture with distributed call admission functions. Related issues of call admission control caused by these characteristics are discussed, and new trends toward call admission control in future wireless ATM network are identified.

We investigate the performance of distributed admission control with quality of service (QoS) provisioning and dynamical channel allocation for mobile/wireless networks where the co-channel reuse distance is considered as the only limiting factor to channel sharing. We first provide a QoS metric feasible for admission control with dynamically allocated channels. We then derive a criterion analytically using the QoS measure for distributed call admission control with dynamic channel allocation (DCA). When maximum packing is used as the DCA scheme, the results obtained are independent of any particular algorithm that implements dynamic channel assignments. Our results, thereby, provide the optimal performance achievable for the distributed admission control with the QoS provisioning by the best DCA scheme in the given setting.

In a heterogeneous wireless network, where many different wireless networks interwork together, call admission control is an important issue to distribute user traffic among different access networks in order to provide quality of service (QoS). In this paper, we present and analyze the performance of a call admission control (CAC) policy for voice and data calls, which is based on one-hop cooperation among the mobile nodes, in a cellular-WLAN interworking scenario. For call-level queueing analysis of the CAC scheme, we use a more general phase-type distribution to model the characteristics of the system. Based on the analytical model, we illustrate the effect of one-hop cooperation on call-level QoS performance (e.g., call blocking probability, call dropping probability).

Decision making is the hot topic in business management. Recently, there have been investigations in Call Admission Control (CAC) to handle the handover events in wireless network environments. Wireless networks have been seen to support different handoff mechanisms, in which the user can switch from one wireless network to another such as from IEEE 802.11 to IEEE 802.16. Many wireless standards, such as IEEE 802.16e and IEEE 802.11, have been proposed to satisfy diverse requirements for mobile users.. Several strategies have been proposed to realize seamless handoff in the heterogeneous networks; in this paper, we analyze the performance of some novel intelligent handoff mechanisms with multiple attributes. The mobile set dynamically selects the optimal network and provides the user with high throughput of Quality of Service (QoS) as to minimize the blocking probability of the system in heterogeneous networks. We evaluate some intelligent handoff mechanisms such as Technique for Order Preference by Similarity to Ideal Solutions (TOPOSIS), Simple Additive Weight (SAW), Analytic Hierarchy Process (AHP) and Fuzzy Logic and Grey Relational Analysis (GRA). From the results, blocking probability and dropping rate can be referenced to support better QoS.

Over the past decade, wireless communications has experienced tremendous growth, and this growth is likely to multiply in the near future. The proliferation of mobile users and an ever increasing demand for multimedia services has resulted in greater capacity requirements. Radio frequency spectrum is scarce and cannot meet this ever increasing demand and the required Quality of Service (QoS) will no longer be achieved if efficient Radio Resource Management (RRM) solutions are not found. Conventional Radio Access Networks (RAN) have standalone Base Stations (BS) with capacity preconfigured for peak loads. These RANs have high call blocking and dropping rates since BSs resources cannot be shared. Cloud based RANs (C-RAN) have been proposed as a cost and energy efficient way of meeting high capacity demand of future wireless access networks by consolidating BSs to the cloud. Instead of relying on rejection of new call requests due to limited BS resources, C-RAN takes benefit of the cloud elasticity, which allows dynamic provisioning of cloud BS resources. This paper presents a novel C-RAN Call Admission Control (C-RAN CAC) to ensure Grade of Service (GoS) by improving blocking probability and improvement of call waiting times. Call blocking probability, call average waiting time and system utilization are used to evaluate the performance of the proposed CAC algorithm.

Power control in wireless networks is useful for minimizing channel congestion (hence increasing network capacity). In this work, we show how the distributed power control algorithm with active link protection (DCP-ALP) can be used as a channel probing tool that allows a new link trying to access a channel to quickly and autonomously determine whether it can be admitted to it (i.e. whether there is a feasible power configuration for the transmitters such that the link quality requirements on all links are met), which significantly improves the capacity and access time of the network.

Due to the fast evolution of mobile devices, a high penetration of notebooks and smart-phones, and the growing demand for high rate services, e.g. mobile video and P2P services, modern radio access networks require efficient means for call admission control and radio resource management. In particular, network operators, managing co-deployed, heterogeneous access technologies, are interested in an optimized utilization of their infrastructure while maximizing their revenue. For ensuring maximum operator gain and optimized system performance, we propose to handle diverse user service requests, ranging from voice only to bandwidth-consuming streaming services, collaboratively by a combined, heuristic Joint Call Admission Control (JCAC) and Dynamic Bandwidth Adaptation (DBA) approach. This approach aims at maximizing overall system utilization and, hence, the mobile network operator's revenues, while keeping the blocking and dropping rates at acceptably low levels, and ensuring that Quality of Service (QoS) demands of the diverse services are met. Therefore, we introduce a novel utility definition of services which is used in the proposed algorithms. It represents a generic measurement of the profit that is gained by the mobile network operator. The JCAC and DBA algorithms are realized tightly coupled and ensure that a maximum number of requested services can be supported by the cooperatively managed, wireless systems in the considered service area. Further, system utilization is optimized by improving the QoS characteristics of the already granted elastic services. In order to evaluate the algorithms for a given scenario of co-deployed Long Term Evolution (LTE) and High Speed Packet Access (HSPA) network nodes, an event-driven simulation platform based on OMNeT++ has been developed, including all relevant entities of 3GPP's SAE. The results show an improvement in the overall gained utility of the mobile network operator compared to standard approaches, and optimized system performance w.r.t. utilization as well as acceptable low blocking and dropping rates.

In the present paper, a call admission control scheme that can learn from the network environment and user behavior is developed for code division multiple access (CDMA) cellular networks that handle both voice and data services. The idea is built upon a novel learning control architecture with only a single module instead of two or three modules in adaptive critic designs (ACDs). The use of adaptive critic approach for call admission control in wireless cellular networks is new. The call admission controller can perform learning in real-time as well as in offline environments and the controller improves its performance as it gains more experience. Another important contribution in the present work is the choice of utility function for the present self-learning control approach which makes the present learning process much more efficient than existing learning control methods. The performance of our algorithm will be shown through computer simulation and compared with existing algorithms.

In this paper, we propose a call admission control mechanism for wireless ad hoc networks called interference-based call admission control (iCAC). iCAC is unique in that it does not treat interference uniformly instead classifies interference based on estimates of the position of the interfering nodes. iCAC relies on two novel techniques: (1) estimation of position of the interfering nodes (2) fair allocation using bandwidth acquisition and rate control. By incorporating these techniques, iCAC is able to increase the estimated available bandwidth substantially without overloading the network. We compare iCAC with perceptive admission control (PAC) and IEEE 802.11 without admission control. Simulation results show that iCAC is able to admit substantially more requests than PAC, achieves more than 80% of the throughput of IEEE 802.11 and at the same time maintains very low packet loss rate and average delay comparable to PAC

Cross-layer radio resource management in integrated WWAN and WLAN networks