Utility Based Short-term Throughput Driven Scheduling Approach for Efficient Resource Allocation in CDMA Wireless Networks

In this paper, we address the problem of efficient recourse allocation in CDMA wireless networks supporting multimedia services with various and often diverse QoS prerequisites, placing special emphasis on real-time services’ essential requirements satisfaction. We first provide an analytical framework for studying real-time users’ short-term delay and throughput properties under fundamental opportunistic scheduling policies. The corresponding results demonstrate that probabilistic delay constraints are insufficient indicators of real-time services’ QoS prerequisites, while probabilistic short-term throughput requirements are more appropriate in asserting their performance expectations. Based on these observations and results, we propose and develop a scheduling policy for efficiently supporting heterogeneous services that include delay-tolerant non-real-time and delay-sensitive real-time services, over a wireless CDMA system under a common utility based framework. A user’s utility characterizes his degree of satisfaction for the received service as well as QoS expectations fulfillment, in a normalized way. Aiming at the maximization of users’ utilities, both non-real-time services’ long-term and real-time services’ short-term throughput QoS requirements are met, under the proposed opportunistic scheduler. Finally, via modeling and simulation it is demonstrated that significant performance improvements concerning both types of services’ QoS requirements satisfaction are achieved through the proposed scheduling approach.     

Improving QoS Performance in IEEE 802.11e Under Heavy Traffic Loads

IEEE 802.11e standard is a concrete attempt to QoS challenge, but when the volume of traffic flows increases, this approach is not sufficient. Several techniques have been developed to improve WLAN QoS performance, mainly introducing a trade-off between performance and standard compatibility. This work describes the techniques used to enhance EDCA efficiency by suitably regulating standard’s parameters and it introduces an innovative algorithm, named Dynamic TXOP (DTXOP), capable of enhancing fairness between upstream and downstream resource allocation in Wi-Fi networks. Finally, after a brief review of admission control algorithms for QoS support under heavy traffic loads, a suitable admission control scheme is integrated with DTXOP as a possible solution for facing QoS degradation of active sources due to an excessive network load. The benefits obtained by integrating DTXOP and the proposed admission control policy are shown in terms of QoS enhancement and efficiency in resource allocation.     

Managing end‐to‐end quality of service in multiple heterogeneous wireless networks

Supporting quality of service (QoS) in wireless networks has been a very rich and interesting area of research. Many significant advances have been made in supporting QoS in single wireless networks. However, the support for QoS across multiple heterogeneous wireless networks will be required in future wireless networks. In connections spanning multiple wireless networks, end‐to‐end QoS will depend on several factors such as mobility patterns, connection patterns, and the QoS policies in each of the networks. In this paper, we present an architecture for multiple heterogeneous wireless networks, several QoS schemes, a simulation model and several interesting results. The simulation model can evaluate the QoS performance under a variety of network configurations, user and mobility types, and network resources. Our results show that end‐to‐end QoS depends on several factors, including system utilization, mobility levels, and the individual QoS schemes implemented in individual networks. We also show how the QoS ideas presented in this paper can be used by wireless carriers for improved QoS support and management. Copyright © 2006 John Wiley & Sons, Ltd.     

CAC-RD: an UMTS call admission control

The third wireless network generation (3G) aims to provide fast Internet access with quality of service (QoS) guarantees, especially to multimedia applications. UMTS (Universal Mobile Telecommunication System) is a kind of 3G networks. To provide QoS, the network must use an efficient admission control mechanism. This mechanism needs to prioritize network access to critical classes of applications. This work proposes an UMTS admission control mechanism, called CAC-RD (Call Admission Control—based on Reservation and Diagnosis). It is based on network diagnosis and on channel reservation for handovers. These techniques are associated with new calls blocking when the network reaches utilization thresholds. CAC-RD is a tool that prioritises handovers and conversational applications. The main CAC-RD goals are the handovers blocking reduction and the acceptable performance levels guarantee. Simulation results show that the CAC-RD channel reservation and the diagnosis techniques associated with the intrinsic network signal power control effectively reduces blockings while guarantying performance levels. Due to computational resource limits, simulations cannot answer related to admission control in big networks with thousands of users. This work presents a method to extrapolate scientific questions like CAC’s behavior with thousands of users and many antennas. An artificial neural network approach for CAC-RD in UMTS 3G networks is presented as an extension of the work.     

Utility-Aware Cognitive Network Selections in Wireless Infrastructures

Operators of wireless infrastructures should maintain their users “always-best-connected”. This concept means that applications should be offered to users at the best possible Quality of Service (QoS) level, taking into account profile, context and policy information. The profiles provide the user requirements and preferences, the terminal capabilities, and the application requirements. The policies provide the objectives, constraints imposed by various stakeholders, for instance the network operator (NO). The context of operation designates relevant applications, available networks and their QoS capabilities. The “always-best-connectivity” concept can be achieved by directing user terminals to the most appropriate networks of the heterogeneous infrastructure of the NO. In this respect, advanced terminal management functionality is required. This paper presents management mechanisms for utility-based cognitive network selections. The utility is used for expressing the user desire for a QoS level. Cognition mechanisms are applied for learning the QoS capabilities of candidate networks, and therefore increasing the reliability and seamlessness of the network selections. Extensive results are provided, which show the behaviour of the scheme in terms of network selections made, and computational effort required for the acquisition of the knowledge.     

Cross-layer radio resource allocation in packet CDMA wireless mobile networks

An efficient radio resource allocation scheme is crucial for guaranteeing the quality of service (QoS) requirements and fully utilizing the scarce radio resources in wireless mobile networks. Most of previous studies of radio resource allocation in traditional wireless networks concentrates on network layer connection blocking probability QoS. In this paper, we show that physical layer techniques and QoS have significant impacts on network layer QoS. We use a concept of cross-layer effective bandwidth to measure the unified radio resource usage taking into account both physical layer linear minimum-mean square error (LMMSE) receivers and varying statistical characteristics of the packet traffic in code devision multiple access (CDMA) networks. We demonstrate the similarity between traditional circuit-switched networks and packet CDMA networks, which enables rich theories developed in traditional wireless mobile networks to be used in packet CDMA networks. Moreover, since both physical layer signal-to-interference ratio (SIR) QoS and network layer connection blocking probability QoS are considered simultaneously, we can explore the tradeoff between physical layer QoS and network layer QoS in packet CDMA networks. This work is supported by Natural Science and Engineering Research Council of Canada. Please address all correspondence to Professor Vikram Krishnamurthy at the above address. Fei Yu received the Ph.D. degree in electrical engineering from the University of British Columbia in 2003. From 2002 to 2004, he was with Ericsson (in Lund, Sweden), where he worked on the research and development of dual mode UMTS/GPRS handsets. From 2005, he has been working in Silicon Valley at a start-up, where he conducts research and development in the areas of advanced wireless communication technologies and new standards. After completing the PhD, he has been a research associate in the Department of Electrical and Computer Engineering at the University of British Columbia. His research interests include cross-layer optimization, QoS provisioning and security in wireless networks. Vikram Krishnamurthy (S’90-M’91-SM’99-F’05) was born in 1966. He received his bachelor’s degree from the University of Auckland, New Zealand in 1988, and Ph.D. from the Australian National University, Canberra, in 1992. Since 2002, he has been a professor and Canada Research Chair at the Department of Electrical Engineering, University of British Columbia, Vancouver, Canada. Prior to this he was a chaired professor at the Department of Electrical and Electronic Engineering, University of Melbourne, Australia. His research interests span several areas including ion channels and nanobiology, stochastic scheduling and control, statistical signal processing and wireless telecommunications. Dr. Krishnamurthy has served as associate editor for IEEE Transactions on Signal Processing, IEEE Transactions Aerospace and Electronic Systems, IEEE Transactions Nanobioscience, IEEE Transactions Circuits and Systems II, Systems and Control Letters and European Journal of Applied Signal Processing. He was guest editor of a special issue of IEEE Transactions on NanoBioScience, March 2005 on bio-nanotubes.     

The Dyadic Green’s Function in a loaded rectangular waveguide and its application

This paper presents a method to derive the Dyadic Green’s Function (DGF) of a loaded rectangular waveguide by using the image method. In the calculation of the DGF, we use the integral transformation and replace the multi-infinite summation by a single one; thus it greatly simplifies the calculation and saves computer time. As an example of the DGF’s application, we give the moment method’s scattering field calculation of a metal sphere resting on the broad wall of the loaded rectangular waveguide. Results of our calculations well agree with both data of experiments performed in our laboratory and those are published. It is easy to see that the method used in this paper can be expanded to other related waveguide problems.     

Subjective QoE analysis of VoIP applications in?a?wireless?campus?environment

The quality perceived by the user, a concept known as Quality of user Experience (QoE), is gaining momentum. Together with the efforts of providing appropriate architectures able to deliver the expected level of Quality of Service (QoS), users’ perception of the level of quality could play a key role in making a VoIP multimedia application to succeed or to fail. QoE can be measured from different approaches; subjective ones are based on polls while objective ones are mainly based on QoS network performance parameters. Although a subjective evaluation could be costly and time consuming, it gives the most accurate results. Moreover, wireless environments incorporate new challenges in terms of QoS and QoE because of inherent wireless communication characteristics. In this way, our contribution is twofold. First, we carry out a subjective QoE assessment for VoIP applications in a real wireless environment. Skype, Gizmo5, ooVoo, and Damaka are the selected VoIP applications under study. Next, we contrast QoE results with QoS evaluation from the captured video calls made during the poll. Results show that there is no precise match on both assessments, because of QoE parameters that cannot be inferred from QoS analysis, because of the different effect of some QoS parameters which prevail, or even because of the popularity of the VoIP application.     

DPS: An Architecture for VBR Scheduling in IEEE 802.11e HCCA Networks with Multiple Access Points

Recent advances in 802.11 Wireless Local Area Networks (WLANs) have been focused on introducing Quality of Service (QoS) in their performance through the adoption of 802.11e. The Hybrid Controlled Channel Access (HCCA) has been proposed as the mechanism to provide the means for guaranteed QoS in networks controlled by a single Access Point (AP). Moreover, scheduling algorithms have been developed allowing efficient scheduling of Variable Bit Rate (VBR) traffic flows. However, little research may be found regarding the problem of applying HCCA on networks with multiple APs. In this paper, various VBR scheduling mechanisms and methods for multi—AP HCCA are presented and evaluated. In addition, this paper introduces the Dynamic Parallel Scheduler (DPS), a novel HCCA scheduling algorithm for VBR traffic among multiple APs that takes advantage of the rate variability and spatial reuse. DPS’s performance evaluation shows that the proposed scheme achieves improved performance in terms of delay, throughput and packet loss.     

Application of cost models over traffic dimensioning with QoS restrictions

Network operators and Internet service providers are offering “Triple Play” products integrating services with different quality of service (QoS) requirements. The provision of QoS guarantees implies the revision of current dimensioning methods and consequences for costing and pricing. This paper proposes a cost model which considers QoS parameters, based on the Total Element Long Run Incremental Cost (TELRIC) model, calculating the cost of a network element and distributing it over the different services whose traffic uses it, taking into account the QoS requirements of each service. For this purpose, three traffic engineering methods are analyzed: complete traffic aggregation by “Over-engineering,” complete traffic segregation by separated virtual tunnels, and partial traffic aggregation by priority queuing. As an example, the cost model is applied to the connection in a Next Generation Network aggregation network for estimating the influence of QoS and traffic engineering on the cost estimation under the TELRIC model.     

基于无线Mesh网络的分布式协调功能的研究

随着无线mesh网络的迅速发展和实时多媒体业务的日益增长,要求无线网络不仅能提供简单的连通性,还需要提供非常有效的QoS保证机制,针对这一问题,以时分多址/时分双工(TDMA/TDD)技术为基础,提出一种基于无线mesh网络的分布式协调功能,信道存取与数据传输发生在不同的时隙中,能够为端到端数据流公平的分配带宽,并且保证了实时服务传输的QoS.仿真及分析表明该协调功能可提高系统吞吐量并降低端到端延迟,有着更好的QoS性能.     

Call admission control with active link protection for opportunistic wireless networks

In this paper we suggest a call admission control (CAC) algorithm for high speed downlink packet access HSDPA UMTS systems. In this algorithm the user requesting admission is gradually admitted into the system. This is done by setting a back-off factor limiting the new user’s throughput. The back-off factor is gradually decreased leading to a gradual increase in the new user’s throughput until it is fully integrated into the system. The back-off factor works on protecting the active links in a way that their rates do not drop below a guaranteed quality of service (QoS) level.     

Rate control-based framework and algorithm for optimal provisioning

Ideally, networks should be designed to accommodate a variety of different traffic types, while at the same time maximizing its efficiency and utility. Network utility maximization (NUM) serves as an effective approach for solving the problem of network resource allocation (NRA) in network analysis and design. In existing literature, the NUM model has been used to achieve optimal network resource allocation such that the network utility is maximized. This is important, since network resources are at premium with the exponential increase in Internet traffic. However, most research work considering network resource allocation does not take into consideration key issues, such as routing and delay. A good routing policy is the key to efficient network utility, and without considering the delay requirements of the different traffic, the network will fail to meet the user’s quality of service (QoS) constraints. In this paper, we propose a new NUM framework that achieves improved network utility while taking into routing and delay requirements of the traffic. Then, we propose a decomposition technique-based algorithm, D-NUM, for solving this model efficiently. We compare our approach with existing approaches via simulations and show that our approach performs well.     

An Autonomic QoS-centric Architecture for Integrated Heterogeneous Wireless Networks

In this paper the problem of seamless mobility and proficient joint radio resource management over an all-IP internetworked wireless heterogeneous environment is addressed. Nodes’ autonomicity is envisioned as the enabler to devise a Quality of Service (QoS) aware architecture for supporting a variety of services, founded on a common utility based framework that provides enhanced flexibility in reflecting different access networks’ type of resources and diverse QoS prerequisites, under a unified QoS-aware resource allocation optimization problem. This allows a more in-depth intrinsic wireless network convergence, beyond All-IP, driven by QoS-oriented resource management. This vision is demonstrated and instantiated for integrated WLAN and cellular (both CDMA and OFDMA) networks, providing a viable path towards the evolution and realization of the future wireless networking paradigm. Initial numerical results demonstrate the effectiveness of the proposed architecture and reveal the benefits of such a service oriented paradigm against other existing access oriented autonomic designs.     

Case analysis of a Cost-Optimal QoS aggregation policy for network mobility

The network mobility reservation protocol was proposed to increase the scalability of QoS provision in moving networks. However, its scalability is undermined when sessions are bursty and short-lived. QoS aggregation addresses this by holding requests at the mobile router for a time before sending a single aggregated reservation to the access network. This letter analyses a cost-optimal QoS aggregation policy under the case of bursty requests, and compares its expected cost efficiency and user waiting time with that of other previously proposed policies. It is shown that the C-policy reduces operator costs compared to other policies, whilst also reducing expected queueing times.     

Evaluation of Interoperability Criteria and Mechanisms for Seamless Inter-Working Between UMTS-HSDPA and WLAN Networks Enhanced with MIMO Techniques

This article proposes criteria and mechanisms that achieve seamless inter-working between the multi-radio access technologies that will compose the fourth-generation (4G) wireless mobile environment. We address the problem of incorporating system interoperability in order to provide the user with seamless mobility across different radio access technologies; namely we focus on inter-working UMTS-High Speed Downlink Packet Access (HSDPA) and WLAN networks, as these two networks are believed to be major components of the 4G wireless network. Interoperability results in providing the user with a rich range of services across a wide range of propagation environment and mobility conditions, using a single terminal. Specifically, the article aims at defining the criteria and mechanisms for interoperability between the two networks. Our approach considers the use of Cost functions to monitor the essential parameters at the system level in order to trigger an interoperability procedure. Initial user assignment and inter-system handover are considered the incidents that initiate the interoperability algorithm execution. The overall objective of this work is to assess the performance of our developed interoperability platform and to optimize system performance by guarantying a minimum QoS requirement and maximizing network capacity.     

Android vs. IOS: a comparative analysis over mobile operator infrastructures based on crowdsourced mobile dataset

User equipment (UE)’s operating system (OS) and category types are important factors that are affecting the end-user performance in a given mobile network operator (MNO)’s infrastructure. For this reason, fair and statistically accurate observed network performance differences of UE’s OSs based on category types, MNOs or locations can be of interest for mobile telecommunication ecosystem players. This paper’s focus is on performance comparisons of UE OSs (including Android, IOS (iPhone Operating System) and Windows phones) over different UE categories, MNOs and locations based on previously collected end-to-end nationwide crowd-sourced data measurements in Turkey. The analysis results performed in this paper uses statistical comparisons of unpaired observations due to imbalance between number of observations between all OSs and yield insight on how the mobile OS types’ network performances differ using some important Key Performance Indicators (KPIs) such as downlink (DL) speed, latency, jitter and packet loss (PL). The outcome of the analysis indicate that Android devices perform better in terms of DL speed among all MNOs, whereas IOS devices are better in terms of latency values. On the other hand depending on the UE category, the performances of MNOs may vary when IOS and Android OSs are compared based on different KPIs. Additionally, IOS has shown better performance than Android in large geographical areas of Turkey. Finally, the business aspects of performing the proposed statistical OS comparisons from the perspectives of OS developers, MNOs, device manufacturers, and end-users are highlighted.

     

A hybrid CAC algorithm for maximizing downlink capacity of M-WiMAX systems

Due to the implementation of an Adaptive Modulation-Coding (AMC) mechanism in the 802.16e physical layer, each connection’s bandwidth requirements cannot be statically computed, but they derive as a function of the terminals’ instantaneous Signal-to-Noise Ratio (SNR). Therefore, the Connection Admission Control (CAC) mechanism fails to establish an efficient policy that would optimally exploit the system’s resources. In this respect, the present paper formulates initially an adequate method for statistically calculating the average capacity of a Mobile-WiMAX system, according to the distribution of the several attenuation factors that affect the signal along the propagation path. In parallel, based on the processing of the terminal’s SNR samples, a sophisticated algorithm for filtering out any misleading measurements is developed. This second method aims at predicting the upcoming Modulation-Coding state of every connection, so as to acquire a short-term view of its spectrum demands. Finally, all the above info collected from both the estimation methods is utilized by the CAC procedure in order to perform an as accurate as possible computation of the resource availability. As a result, this hybrid approach succeeds in maximizing the network revenue through significantly increasing the number of concurrently serviced connections while guaranteeing their Quality of Service (QoS) standards.     

TD-SCDMA网络用户感知评估体系的实施

移动运营商现行的网络质量评估方法主要是基于关键性能指标KPI,具体包括网管设备的统计数据和DT/CQT路测统计数据,这种评估方法是站在网络和设备的角度来感知网络的质量,在当前运营商逐渐转变为以客户为中心的趋势下,这种传统的评估方法也将过渡到以用户感知为中心的体系上来.近3年来各个运营商及设备厂家已经在用户感知评估体系方...     

A Multi-Hop Resource Reservation Scheme for Seamless Real-Time QoS Guarantee in WiMedia Distributed MAC Protocol

In this paper, a multi-hop range conflict-free resource reservation scheme for UWB (Ultra Wide Band) WPAN (Wireless Personal Area Network) with D-MAC (Distributed Medium Access Control) is proposed. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia Alliance supports DRP (Distributed Reservation Protocol) mechanism which makes all devices be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However, since each device’s mobility perspective in multi-hop environment has not been taken into account in the current WiMedia D-MAC, it may cause a “mobile” hidden node problem. In addition, once a DRP conflict occurs due to the mobile hidden node problem, only one of the DRP reservations involved in that DRP conflict maintains the reserved MASs, while the other DRP reservations must be terminated and DRP negotiations for them have to be re-started although only a few MASs are overlapped. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a mechanism to prevent and resolve multi-hop range DRP conflicts due to each device’s mobility in D-MAC environment and demonstrate its guaranteed Seamless QoS and prioritized real-time QoS performances via numerical analyses.