The common RRM approach to admission control for converged heterogeneous wireless networks

As the wireless environment becomes ever more populated and complex, individual networks offering single or restricted services will become ever more uncompetitive. Common radio resource management algorithms and strategies are used in heterogeneous or converged wireless networks to integrate multiple physical radio interfaces to support different levels of data rates, mobility, and traffic. Admission control in a common RRM environment is used to select the most appropriate wireless access based on service type, user preference, and network load. This is used to provide a balance between real-time and non-real-time traffic across the available access technologies. The development of common radio resource management strategies requires a suitable platform of coupled access networks and is the motivation behind the development of a converged wireless test platform. The tightly coupled platform supports voice and data call setup and delivery over UMTS and WLAN     

An optimization framework for balancing throughput and fairness in wireless networks with QoS support

Quality-of-service (QoS) provisioning, high system throughput, and fairness assurance are indispensable for heterogeneous traffic in future wireless broadband networks. With limited radio resources, increasing system throughput and maintaining fairness are conflicting performance metrics, leading to a natural tradeoff between these two measures. Balancing system throughput and fairness is desired. In this paper, we consider an interference-limited wireless network, and derive a generic optimization framework to obtain an optimal relationship of system throughput and fairness with QoS support and efficient resource utilization, by introducing the bargaining floor. From the relationship curve, different degrees of performance tradeoff between throughput and fairness can be obtained by choosing different bargaining floors. In addition, our framework facilitates call admission control to effectively guarantee QoS of. multimedia traffic. The solutions of resource allocation obtained from the optimization framework achieve the pareto optimality, demonstrating efficient use of network resources.     

Proactive load balancing with admission control for heterogeneous overlay networks

The next generation wireless networks will be the coexistence of heterogeneous wireless technologies. Balancing the traffic load among different networks can effectively utilize the overall radio resources in the system. In this paper, we propose an efficient load balancing scheme for the heterogeneous overlay systems, which is applied in the call admission control process. If the available network(s) cannot provide enough resource for the request call without degrading the quality‐of‐service (QoS) obtained by the ongoing calls, the system will perform load balancing operations first by initiating vertical handoffs among networks in order to create more rooms for the request call. The load balancing algorithm is to minimize the variance between the network utilizations of the entire system, which can be formulated as a quadratic binary programming problem. Simulation results show that the proposed scheme can admit more calls into the system compared with the other three reference schemes and then improve the overall throughput. Meanwhile, the scheme can keep the networks working in effective states and provide a better QoS support for users. Copyright © 2011 John Wiley & Sons, Ltd.     

Performance Analysis of an Improved Common Radio Resource Management Algorithm Based on Load Balance and Service Characteristics

In order to provide users with satisfactory quality of service and reduce service cost as much as possible, a key issue is how to manage radio resources reasonably and effectively in heterogeneous wireless networks (HWNs). Based on load balance and service characteristics, a common radio resource management (CRRM) algorithm for HWNs consisting of CDMA2000 and IEEE802.11 is proposed. The proposed algorithm selects appropriate access and handoff networks for new and handoff calls respectively, according to users’ mobility characteristic, location information, service type and network load. The performance of the proposed algorithm is analyzed based on a three-dimensional Markov chain model. Based on the HWNs model and handoff rate analysis, the model’s parameters are determined. In order to resolve the steady-state distribution of the three-dimensional Markov model, successive over-relaxation iteration method is adopted to work out steady state equations. According to the steady state probabilities of the Markov model, the closed formulas of HWNs performance metrics are given to evaluate the proposed CRRM algorithm, e.g. call blocking probability, handoff blocking probability, throughput, and service cost. For the purpose of illustrating advantages of the proposed algorithm, two other CRRM algorithms are employed for comparison. The simulation results show that the proposed algorithm can effectively reduce call blocking probability, and improve HWNs throughput.     

Effect of mobile terminal heterogeneity on call blocking/dropping probability in cooperative heterogeneous cellular networks

It is envisaged that next generation wireless networks (NGWN) will be heterogeneous, consisting of multiple radio access technologies (RATs) coexisting in the same geographical area. In these heterogeneous wireless networks, mobile terminals of different capabilities (heterogeneous terminals) will be used by subscribers to access network services. We investigate the effect of using heterogeneous mobile terminals (e.g. single-mode, dual-mode, triple-mode, etc.) on call blocking and call dropping probabilities in cooperative heterogeneous wireless networks. We develop analytical models for heterogeneous mobile terminals and joint radio resource management in heterogeneous wireless networks. Using a two-class three-RAT heterogeneous wireless network as an example, the effect of using heterogeneous terminals in the network is evaluated. Results show the overall call blocking/dropping probability experienced by subscribers in heterogeneous wireless networks depends on the capabilities of mobile terminals used by the subscribers. In the worst case scenario, when all subscribers use single-mode mobile terminals, each subscriber is confined to a single RAT and consequently, joint radio resource management in heterogeneous wireless network has no improvement on new call blocking and handoff call dropping probabilities. However, in the best case scenario, when all subscribers use three-mode terminals, new class-1 call blocking probability decreases from 0.37 (for 100% single-mode terminals) to 0.05, at the arrival rate of 6 calls per minute. New class-2 call blocking probability also decreases from 0.8 to 0.52. Similarly, handoff class-1 call dropping probability decreases from 0.14 to 0.003, and handoff class-2 call dropping probability decreases from 0.44 to 0.09.     

基于QoS保证的负载均衡频谱决策算法

针对不同无线网络间频谱资源利用率不均衡的问题,在IEEE 1900.4标准的框架下提出了基于服务质量(QoS)保证的负载均衡算法,使得认知终端可以通过频谱决策动态地接入不同的无线接入网频段,从而提高频谱利用效率。该算法以网络吞吐量的优化为目标,在资源约束和QoS保证的条件下,通过简化算法而减少开销。仿真结果表明,基于QoS保证的负载均衡频谱决策算法较之传统的基于信噪比(SNR)的频谱接入算法能够使网络的吞吐量得到大幅的提升。     

Dynamic pricing for load‐balancing in user‐centric joint call admission control of next‐generation wireless networks

Next‐generation wireless networks (NGWN) will be heterogeneous, comprising of a number of radio access technologies (RATs) co‐existing in the same geographical area. In NGWN, joint call admission control (JCAC) algorithms are required to select the most appropriate RAT for each incoming call. It is envisaged that these JCAC algorithms will be user‐centric (i.e. will consider users' preferences in making RAT selection decisions) in order to enhance user satisfaction. However, user‐centric JCAC algorithms can lead to highly unbalanced traffic load among the available RATs in NGWN because users act independently, and most of them may prefer to be connected through a particular RAT. Highly unbalanced traffic load in NGWN will result in high overall call blocking/dropping probability and poor radio result utilization. To address this problem, we propose dynamic pricing for balancing traffic load among available RATs in heterogeneous wireless networks where users' preferences are considered in making RAT selection decisions. By dynamically adjusting the service price in each of the available RATs, the proposed user‐centric JCAC scheme evens out the unbalanced traffic load caused by independent users' preferences. The JCAC scheme uses fuzzy multiple attribute decision‐making (MADM) technique to select the most appropriate RAT for each incoming call. We develop a Markov model to evaluate the overall call blocking/dropping probability and percentage load in each RAT in heterogeneous wireless networks. Performance of the proposed JCAC scheme is compared with that of a scheme that does not use dynamic pricing. Simulation results are given to show the effectiveness of the proposed JCAC scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

Radio Network Aggregation for 5G Mobile Terminals in Heterogeneous Wireless and Mobile Networks

This paper provides a novel design concept for advanced mobile multi interface terminals with radio network aggregation capability and enhanced quality of service (QoS) provisioning for multimedia services (voice, video and data) in heterogeneous wireless and mobile networks. A new module is established which provides the best QoS and lowest cost for any given multimedia service by using simultaneously all available wireless and mobile access networks for a given traffic flow. This novel adaptive QoS module with adaptive QoS routing algorithm is called advanced QoS routing algorithm (AQoSRA), which is defined independently from any existing and future radio access technology. The performance of our proposal is evaluated using simulations and analysis with multi-interface mobile stations with AQoSRA within, carrying multimedia traffic in heterogeneous mobile and wireless environment with coexistence of multiple Radio Access Technologies, such as 3G, 4G as well as future 5G radio access networks. The analysis of the proposed framework for radio networks aggregation in advanced mobile terminals has shown overall better performances regarding the achievable throughput and multimedia access probability in heterogeneous wireless and mobile environment.     

Predictive QoS-based admission control for multiclass traffic incellular wireless networks

We develop the notion of quality of service (QoS) for multimedia traffic in terms of maximum call dropping probabilities independent of system load and a predefined call blocking probability profile for the different traffic classes for wireless networks of arbitrary shape and dimension. We describe two distributed predictive admission control algorithms, independent multiclass one-step prediction (IMOSP-CS and IMOSP-RES), which provide each traffic class with a given call dropping probability and a desired call blocking probability profile. Both algorithms may be seen as extensions of the multimedia one-step prediction (MMOSPRED) algorithm previously reported, which uses prediction of the overload probability in the home and neighbor cells in deciding whether to admit new users into a multiclass cellular system. The two algorithms differ in their approach to handoff call admission. The first algorithm completely shares the bandwidth among the entering handoff users while the second implements a partition-based reservation scheme. In this paper, we additionally impose a call blocking criterion that ensures a system-imposed call priority independent of the traffic in the system and which adapts to changes in the offered load. In comparing these algorithms to each other, we focus on system throughput and class independence. Both algorithms provide appropriate throughput under both homogeneous and heterogeneous traffic loading conditions while maintaining steady call dropping probabilities for each traffic class     

Call admission control strategy for system throughput maximization considering both call- and packet-level QoSs

This letter presents a call admission control (CAC) strategy for system throughput maximization in wireless uplink systems. This strategy considers not only the call-level quality of service (QoS) (i.e., blocking probability) but also the packet-level QoS (i.e., outage probability). Using the statistical co-channel interference (CCI) model and state diagram, the outage probability and the blocking probability are investigated as a function of the relative traffic load. We formulate the CAC strategy problem based on relative traffic load, and suggest a solution. The numerical results show that maximum system throughput can be achieved by controlling the relative traffic load. In addition, we illustrate the region where system throughput is constrained by call- and packet-level QoSs. This examination shows that the call and packet-level QoSs must be considered together to achieve maximum system throughput.     

5G mobile terminals with advanced QoS-based user-centric aggregation (AQUA) for heterogeneous wireless and mobile networks

In this paper we present an advanced QoS provisioning module with vertical multi-homing framework for future fifth generation (5G) mobile terminals with radio network aggregation capability and traffic load sharing in heterogeneous mobile and wireless environments. The proposed 5G mobile terminal framework is leading to high performance utility networks with high QoS provisioning for any given multimedia service, higher bandwidth utilization and multi-RAT capabilities. It is using vertical multi-homing and virtual QoS routing algorithms within the mobile terminal, that is able to handle simultaneously multiple radio network connections via multiple wireless and mobile network interfaces. Our 5G proposal is user-centric, targeted to always-on connectivity, maximal network utilization, maximal throughput, seamless handovers and performances improvement by using vertical multi-homing, as well as session continuity. The performance of our proposed mobile terminal framework for 5G is evaluated using simulations and analysis with multimedia traffic in heterogeneous mobile and wireless scenarios with coexistence of multiple radio access technologies, such as 3G, 4G as well as future 5G radio access networks.     

基于多门限预留机制的自适应带宽分配算法

针对异构无线网络融合环境提出了一种基于多门限预留机制的自适应带宽分配算法,从而为多业务提供QoS保证。该算法采用多宿主传输机制,通过预设各个网络中不同业务的带宽分配门限,并基于各个网络中不同业务和用户的带宽分配矩阵,根据业务k支持的传输速率等级需求和网络状态的变化,将自适应带宽分配问题转化为一个动态优化问题并采用迭代方法来求解,在得到各个网络中不同业务和用户优化的带宽分配矩阵的同时,在带宽预留门限和网络容量的约束条件下实现网络实时吞吐量的最大化,以提高整个异构网络带宽的利用效率。数值仿真结果显示,所提算法能够支持满足QoS需求的传输速率等级,减小了新用户接入异构网络的阻塞概率,提高了平均用户接入率并将网络吞吐量最大提高40%。     

Load balancing for cellular/WLAN integrated networks

The interworking between heterogeneous third-generation cellular networks and wireless local area networks is one promising evolution approach to fourth-generation wireless networks, which can exploit the complementary advantages of the cellular network and WLANs. Resource management for the 4G-oriented cellular/WLAN integrated network is an important open issue that deserves more research efforts. In this article we present a policy framework for resource management in a loosely coupled cellular/WLAN integrated network, where load balancing policies are designed to efficiently utilize the pooled resources of the network. A two-phase control strategy is adopted in the load balancing policies, in which call assignment is used to provide a statistical quality of service guarantee during the admission phase, and dynamic vertical handoff during the traffic service phase is used to minimize the performance variations. Numerical results are presented to demonstrate that the proposed load balancing solution achieves significant performance improvement over two other reference schemes     

I3E: A Novel Call Admission Control Scheme for W-CDMA Systems

Efficient Call Admission Control (CAC) techniques are of paramount importance to achieve a flexible radio resource utilization with W-CDMA systems like UMTS. In order to accept or reject a call, the CAC scheme should be able to estimate if the system can provide a Signal-to-Interference Ratio (SIR) high enough to the new call and to all the others. With symmetric traffic the more critical direction for the system capacity is the uplink and the CAC can consider this direction only. Received-Power based CAC (RP-CAC) are practical CAC schemes proposed for the uplink that estimate the system load measuring the total power received at the base stations (BSs). Simple RP-CAC schemes just compare the measured power at the BS where the call is initiated with a threshold (Single Cell RP-CAC) or also measure the power received by neighboring BSs (Multi Cell RP-CAC). More complex RP-CAC schemes try also to estimate the load increase due to the new call (Predictive RP-CAC). In this paper we compare the performance of these schemes and propose a new Predictive scheme, named Iterative Interference Increase Estimation (I³E). We show that the advantage of using multi-cell strategy with respect to the single-cell one is negligible and that previously proposed Predictive RP-CAC techniques are not able to improve the performance in a remarkable way. On the contrary, I³E CAC increases the accepted traffic while keeping the call dropping probability very low, and its performance approaches the upper bound obtained considering an ideal CAC.Preliminary results have been presented in WCNC2003. Antonio Capone received the Laurea degree (MS degree equivalent) and the PhD degree in telecommunication engineering from the Politecnico di Milano in July 1994 and June 1998, respectively. In 2000, he was a visiting scientist at the University of California, Los Angeles. He is now an associate professor in the Department of Electronics and Information at the Politecnico di Milano. His current research activities include packet access in wireless cellular networks, routing and MAC for multihop wireless networks, congestion control and QoS issues of IP networks, network planning and optimization. He is a member of the IEEE and the IEEE Communications and Vehicular Technology Societies. Simone Redana received the degree in Telecommunication Engineering (Master Degree included) and the doctorate degree in Information Engineering from the Politecnico di Milano in June 2001 and October 2005, respectively. In 2000, he was a visiting research scientist at Siemens Information and Communication Mobile, Munich. He is now a research scientist in the Department of Electronics and Information at the Politecnico di Milano. His current research activities include resource management in wireless cellular networks and multi-hop wireless networks. He is a member of the IEEE.     

基于强化学习的异构无线网络资源管理算法

为了充分利用各种无线网络的资源,需要实现异构网络的融合,而异构网络的融合又面临接入控制与资源分配的问题。为此,提出一种基于强化学习的异构无线网络资源管理算法,该算法引入 D2D （device-to-device）通信模式,并可以根据终端不同的业务类型、终端移动性及网络负载条件等状态,选择合适的网络接入方式。同时,为降低存储需求,采用神经网络技术解决连续状态空间问题。仿真结果表明,该算法具有高效的在线学习能力,能够有效地提升网络的频谱效用,降低阻塞率,从而实现自主的无线资源管理。     

基于不同策略的联合接纳控制算法综述

无线通信网络中多种接入技术将长期并存且协同工作,传统的接纳控制方法无法满足现有用户与网络需求.联合接纳控制是联合无线资源管理的重要组成部分,接纳控制策略的好坏直接影响到用户的服务质量.通过对不同接纳控制策略进行分类并建立相应策略库,设定策略选择机制,以提高阻塞率、中断率、用户满意率及网络资源利用率等指标.以此为指导,分别讨论了不同策略的联合接纳控制算法的性能,并对现有的联合接纳控制算法进行了总结.最后,给出了联合接纳控制下一步需要解决的问题及研究发展方向.     

Radio resource management in multiple-chip-rate DS/CDMA systemssupporting multiclass services

This paper is concerned with radio resource management in multiple-chip-rate (MCR) DS/CDMA systems accommodating multiclass services with different information rates and quality requirements. Considering both power spectral density (PSD) over a radio frequency (RF) link and the effect of RF input filtering on the receiver in MCR-DS/CDMA systems, criteria for call admission are presented and the system performance is derived. The system performance in MCR-DS/CDMA systems is strongly affected by radio resource management. A minimum total-power-increment-based resource management scheme for an efficient resource management is proposed. The performance of this scheme is compared with that of a random-based resource management scheme in terms of the new call blocking probability, handoff call dropping probability, and normalized throughput. In addition, in order to reduce the handoff call dropping rate, reallocating subsystems assigned for communicating calls is proposed. The minimum total-power-increment-based resource management scheme yields better performance than the random-based resource management scheme for multiclass services     

A new handoff management system for heterogeneous wireless access networks

In heterogeneous wireless access networks, each mobile terminal may frequently need to change its base station (BS); this change is called a ‘handoff’. BSs have static parameters, which are related to their radio access technologies (RATs); however, they also contain dynamic parameters such as load and signal quality. Therefore, the problem of handoff decision includes two subproblems of RAT selection and BS selection. In this paper, first a ‘heterogeneous handoff management system’ for gathering all different required parameters is proposed. Second, a RAT Selection algorithm based on analytic hierarchy process and a BS Selection algorithm based on data envelopment analysis are designed. Finally, by means of ‘weight restriction’ technique, we develop a method for studying the impact of RAT Selection parameters on the performance of the network. Simulation results indicate that RAT Selection parameters have significant impact on the bandwidth utilization, energy consumption and the whole satisfaction of the users in heterogeneous wireless access networks.Copyright © 2012 John Wiley & Sons, Ltd.     

Performance analysis of hierarchical cellular networks with queueing and user retrials

How to efficiently utilize the scarce radio channel resource while maintaining the desired user‐perceived quality level and improved network performance is a major challenge to a wireless network designer. As one solution to meet this challenge in cellular mobile networks, a network architecture with hierarchical layers of cells has been widely considered. In this paper, we study the performance of a hierarchical cellular network that allows the queueing of both overflow slow‐mobility calls (from the lower layer microcells) and macrocell handover fast‐mobility calls that are blocked due to lack of free resources at the macrocell. Further, to accurately represent the wireless user behaviour, the impact of call repeat phenomenon is considered in the analysis of new call blocking probability. Performance analysis of the hierarchical cellular structure with queueing and call repeat phenomenon is performed using both analytical and simulation techniques. Numerical results show that queueing of calls reduces forced call termination probability and increases resource utilization with minimal call queueing delay. It is also shown that ignoring repeat calls leads to optimistic estimates of new call blocking probability especially at high offered traffic. Copyright © 2005 John Wiley & Sons, Ltd.     

异构无线网络中基于业务转移和接入控制的混合负载均衡

 针对现有异构无线网络负载均衡方法未能综合考虑重载网络业务转移和新业务接入控制的问题,提出了一种混合负载均衡算法.该算法首先根据各小区负载水平和终端移动性,将重载小区的适量业务向重叠覆盖的轻载小区转移;其次通过资源预留和强占优先的接入控制策略,为不同优先级的新到业务提供有差别的服务.仿真结果表明,本文算法在保证系统资源利用率的同时,保障了实时与非实时业务的QoS,并相对于参考算法有效降低了系统阻塞率和业务切换概率.