Performance analysis of multi-service wireless network: An approach integrating CAC, scheduling, and buffer management

Next-generation wireless networks have been designed to transport integrated multimedia services based on a cellular extension of a packet-switched architecture using variants of the Internet protocol (IP). Each call, arriving to or active within the network, carries demand for one or more services in parallel, where each service type has a guaranteed quality of service (QoS). Admission of new calls to the wireless IP network (WIN) from the gateway of a wired network or from a mobile subscriber (MS) is allowed by call admission control (CAC) procedures. MS roaming among the nodes of the WIN is controlled by handoff procedures between base stations (BSs), or BS controllers (BSCs), and the MSs. Both handoff and CAC procedures are typically embedded in the media access control (MAC) and logical link control (LLC) layers of the WIN protocol stack. Performance metrics, such as, probabilities of call blocking and handoff, control procedures within the WIN protocol. Earlier published results by the author present a method for the performance analysis of wireless multimedia networks based on multivariate point-process (MVPP) models and their semi-martingale representations. The models describe the finite-horizon, transient behavior of the packet flows in integrated multimedia traffic. This paper extends the earlier work to focus on the optimization of real-time control procedures embedded in the WIN protocol stack. The point processes corresponding to the packet flow of each service type and to collateral random network events are decomposed into right-continuous, pure jump processes and predictable, integrated random rate processes. Control of the set of point processes describing WIN behavior is implemented through the construction of an absolutely continuous change of a reference probability measure on network events to a controlled measure. With respect to the constructed controlled measure, the integrated random rates in the semi-martingale representations of the network point processes explicitly depend on the parameters of the protocol mechanisms for packet access, routing, switching, handoff, power control, and other resource allocations. The MVPP control approach via constructed probability measure also supports predictive models of packet flows that incorporate measurement-based estimates of the probability distributions for voice, video, data, and other Internet traffic as well as radio path distortions. Optimization of the performance metrics, represented in terms of the MVPPs and the control parameters of candidate WIN protocols for multimedia services, are discussed for both partial and complete observations of network events. The models are further used to develop optimal, recursive stochastic filters of network state, based on partial or incomplete observations of packet flow dynamics.

This study presents models for management of voice and data traffic and new algorithms, which use call admission control as well as buffer management to optimise the performance of single channel systems such as wireless local area networks in the presence of mobile stations. Unlike existing studies, the new approach queues incoming voice packets as well as data packets, and uses a new pre-emption algorithm in order to keep the response time of voice requests at certain levels while the blocking of data requests is minimised. A new performance metric is introduced to provide uncorrelated handling of integrated services. Queueing related issues such as overall queue capacity, individual capacities for voice and data requests, the probability of blocking, and effects of waiting time on overall quality of service are considered in detail. Analytical models are presented and the results obtained from the analytical models were validated using discrete event simulations.

The design of packet radio networks involves a large number of issues which interact in a very complex fashion. Many of these pertain to the RF channel and its use, others pertain to the operational protocols. Clearly, no single model can be formulated which incorporates all the necessary parameters and leads to the optimum solution. The one essential element which complicates matters is that, contrary to point-to-point networks in which each channel is utilized by a single pair of nodes, the radio channel in packet radio networks is a multiaccess broadcast resource: i) in a given locality determined by radio connectivity, the channel is shared by many contending users, hence the need for channel access protocols; ii) radio is a broadcast medium and thus the action taken by a node has an effect on the actions taken by neighboring nodes and their outcome. Despite the complexity of the problem, there has been significant progress worth reporting on. The work accomplished so far has been either the analysis of specific examples of networks or an attempt to create models that would be useful in the design of general networks. The purpose of this paper is to survey the various modeling techniques that have been used for the performance analysis of packet radio networks, and to discuss the assumptions underlying these models, their scope of applicability, and some of the results obtained.

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.

Next generation wireless networks will support a diverse set of access technologies. And the demanding breed of multimedia applications will even more considerably require Quality of Service (QoS) support. This paper proposes an optimal prority-based Call Admission Control (CAC) scheme in heterogeneous wireless networks, i.e., the generalized semi-Markov Decision Process based CAC (GCAC). Considering the limitations of the traditional Markov decision process for optimal CAC policy, we characterize the CAC problem through a GSMDP formulation that characterize s the network behaviors in the heterogeneous system more exactly. And the proposed scheme can guarantee the QoS constrains both in the physical and network layer. Numerical examples illustrate that the performance in the GCAC scheme is significantly better than that in the conventioinal GC scheme and an optimal CAC schme based on MDP.

Parametric survey on cross-layer designs for wireless sensor networks

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

CDMA systems have a trade-off relationship between the frame error rate (FER) and the number of accepted users. Therefore, the call admission control (CAC) scheme is essential for guaranteeing the FER below the required value, which is the measure of the quality of service (QoS) in the frame level. In cellular networks, the dropping probability of handoff calls is another critical measure for QoS in the call level. There has been, nevertheless, little concern for CAC schemes guaranteeing these QoS requirements simultaneously in the CDMA cellular networks. In this paper, we propose CAC that track the time-varying capacity of CDMA systems by estimating the distribution of the total received power at a base station, thereby realizing the bandwidth reservation scheme to meet the QoS requirement for handoff calls in the call level.

The wide-band code division multiple access (WCDMA) based 3G and beyond cellular mobile wireless networks are expected to provide a diverse range of multimedia services to mobile users with guaranteed quality of service (QoS). Soft capacity is one of the main characteristics of these networks and it necessitates new radio resource management strategies to serve diverse quality of service requirements. In this paper, resource sharing methods known as complete sharing (CS) based call admission controls and complete partitioning (CP) based call admission control are extended for operation in 3G WCDMA network. The extension includes devising call admission control with the deployment of buffering and threshold concepts. Two CS based call admission controls, referred to herein as queuing priority call admission control (QP-CAC) and hybrid priority call admission control (HP-CAC), and one CP based call admission control referred to herein as complete partitioning call admission control (CP-CAC) are presented. All proposed schemes support multiple admission priority classes based on request types (newly originating calls and handoff requests) and the traffic class (real-time and non real-time). CS based algorithms achieve the best system utilization at the expense of unfairness for the traffic classes with diverse QoS requirements while the CP-CAC ensure the fairness and service diferentiation.

Wireless communications have been widely deployed to collect and disseminate data for industrial applications. However, to date the mostly accepted technologies for information collection and dissemination in power grid are still based on wired communications instead of wireless. To leverage the advantages of wireless communications for smart grid, proper wireless networks need to be designed to satisfy the specific service requirements of power grid. Considering the diverse service requirements in different applications of power grid, the design of a wireless network is usually application-specific. So far no systematic approach is available to guide the design of smart grid wireless networks. To this end, a systematic approach is developed in this paper to provide guidelines for smart grid wireless communications. It is based on the framework of cyber-physical system (CPS). Under this framework, a smart grid wireless communication system is categorized into either a loosely-coupled or closely-coupled CPS, considering different mechanisms of interaction between a wireless network and power grid. For either CPS, general procedures of wireless network design are proposed by considering the service requirements and unique features of such a CPS. To illustrate how these design procedures are applied in reality, two application scenarios are presented to demonstrate smart grid wireless communications based on loosely-coupled CPS and closely-coupled CPS, respectively.

Soft handoff and call admission control (CAC) in a packet switching CDMA wireless cellular system are studied. A normal cell area is divided into an inner cell area and a handoff area, based on which a cell capacity vector and a call admission region are derived for uplink transmission to satisfy user quality of service (QoS) requirements and to minimize the grade of service (GoS) function. The QoS parameters under consideration arc the transmission bit error rate (BER) and packet loss rate (PLR). The BER requirement is guaranteed by properly arranging simultaneous packet transmissions, whereas the PLR requirement is satisfied by proper packet scheduling for calls in the inner cell and handoff areas. The GoS function is minimized by considering both new call blocking and handoff call dropping probabilities. By taking traffic characteristics and dynamic scheduling of nonhandoff and handoff calls into account, the proposed packet scheduling scheme achieves fair packet transmissions and greatly enlarges the call admission region.

Wireless multimedia services have to rely on strict quality of service (QoS) requirements to reach the feasibility, including guaranteed available bandwidth, tight delay constraint, and hard jitter tolerance. WiMAX has emerged as one of the most promising broadband wireless access technologies to support these types of services. To guarantee the QoS of connections, CAC (Call Admission Control) can grant a new call only while the required bandwidth is available. With concern about connection capacity, the CAC seems rigid and turns into an obstacle instead while the bandwidth of some connections could be stolen temporarily. Thus, adaptive admission control, differing from the conventional CAC, can flexibly increase connection capacity by stealing bandwidth based on user streaming buffer (USB). A connection in sufficient USB state implies that the undergoing streaming application can perform smoothly even if its bandwidth is stolen temporarily. Therefore, how to determine the USB state of each connection is the most important topic in this study. In order to effectively decrease the risk of system overuse arising from stealing bandwidth, the adaptive admission control is extended by means of an intelligent mechanism to decide the USB states. The simulation results show the proposed intelligent mechanism utilizing fuzzy neural network (FNN) really outperforms than the adaptive admission control in terms of controlling the probability of poor application performance. With approximate connection capacity (or call blocking probability), the intelligent resource management indeed decreases the risk of system overuse.

MPI-QMULInformation Systems Research Centre, Macau Polytechnic InstituteMacau SAR,P. R. ChinaDepartment of Electronic Engineering, Queen MaryUniversity of LondonE-mail: xuy@mpi-gmul.org/john.bigham@elec.gmul.ac.ukAbstract: In this paper, we solve the call admission control(CAC) problem in a cellular network via a form ofNeuroEvolution algorithm. The results are compared withComplete Sharing scheme, which allows all types of traffic toaccess all available channels at all time, and show that ourproposed CAC scheme CN can reduce the handoff failuresubject to several predefined Quality of Service (QoS)constraints: the handoff dropping probability (CDR) andintra-class fairness are all guaranteed within the predefinedconstraints. Additionally, the numerical results shows thatunder the same handoff failure constraint, better fairnesscauses higher new setup calls blocking probabilities (CBR) andlower CDR, therefore the fairness and maximizing revenue aretwo opposite goals, and the fairness and CDR do not conflictwith each other.Keywords: CAC,NEAT, QoS, Fairness.

Mobile opportunistic networks are characterized by intermittent connectivity and practically no end-to-end connection. In these kinds of network, network capacity and throughput largely depends packet replication. As a result buffer space tends to quickly deplete which may result in severe data loss due to packet drop. To the best of our knowledge, the two important phenomenon of traffic management viz., jitter and packet loss have evaded the minds of researchers in this field and hence we study the problem of buffer management and packet scheduling in such networks. We propose a fair queue scheduling policy where packets are sorted based on total waiting time, i.e. sum of waiting times over all the previous hops, before being transferred over a network link. We analytically prove that scheduling packet transmission as above reduces overall waiting time which leads to lower delay. We also propose a source initiated congestion aware buffer management scheme which helps in reducing number of packet loss significantly. The proposed scheduling and buffer management policy is simulated using real world (Cambridge iMote traces) datasets and compared with other existing scheduling policies. Results show that that proposed scheme has lower delay and lower packet drop compared to other scheduling schemes.

A radio communications network design supporting airport surface traffic automation (ASTA) using global positioning system (GPS) data is considered. The emphasis is on spectrally efficient channel access schemes taking into account traffic characteristics. The bandwidth requirements of two time-domain-based multiple access schemes and code division multiple access (CDMA) are analyzed. In the case of CDMA, both a single base station and multiple base stations are considered. It is shown that the use of multiple base stations can significantly improve the total system capacity for a fixed bandwidth. To obtain specific results, it is assumed that the CDMA system employs convolutional forward error correction and operates in a Rayleigh fading channel.