Integration of pricing with call admission control to meet QoS requirements in cellular networks

Call admission control (CAC) plays a significant role in providing the desired quality of service (QoS) in cellular networks. We investigate the role of pricing as an additional dimension of the call admission control process in order to efficiently and effectively control the use of wireless network resources. First, we prove that, for a given wireless network, there exists a new call arrival rate which can maximize the total utility of users while maintaining the required QoS. Based on this result and observation, we propose an integrated pricing and call admission control scheme where the price is adjusted dynamically based on the current network conditions in order to alleviate the problem of congestion. Our proposed integrated approach implicitly implements a distributed user-based prioritization mechanism by providing negative incentives according to the current network conditions and therefore shaping the aggregate traffic in the network. We compare the performance of our approach in terms of congestion prevention, achievable total user utility, and obtained revenue, with the corresponding results of conventional systems where pricing is not taken into consideration in the call admission control process. These performance results verify the considerable improvement that can be achieved by the integration of pricing in the call admission control process in cellular networks.     

An Admission Control Scheme Based on Online Measurement for VBR Video Streams Over Wireless Home Networks

This paper presents an online measurement-based admission control scheme on the basis that the aggregate VBR video traffic is lognormally distributed. The proposed scheme consists of two components: measurement process and admission decision. The measurement process applies a linear Kalman filter to estimate statistical parameters of aggregate VBR video traffic. The estimated statistical parameters are used to calculate the effective bandwidth for admission decision. Variable bit rate (VBR) video traffic with high data rate is expected to occupy a dominant proportion of bandwidth for future wireless broadband home networks. To guarantee quality-of-service (QoS) of such VBR video streams, while achieving a high level of channel utilization, an efficient admission control scheme is urgently required, especially for emerging wireless multimedia indoor services, such as HDTV, online video game, etc. The proposed scheme is computationally efficient and accurate without much prior traffic information. Simulation results verify its effectiveness and show that it performs well for both a small number of connections and a large number of connections.     

Above packet level admission control and bandwidth allocation for IEEE 802.16 wireless MAN

IEEE 802.16 wireless Metropolitan Area Network (MAN) is expected to revolutionize the broadband wireless access technology. Efficient resource management is essential in providing scalability in such large IEEE 802.16-based wireless network and Quality of Service (QoS) for multimedia applications (VoIP, MPEG, FTP, WWW) is usually achieved by appropriate classification of scheduling services and grant/request mechanism. In this paper, we firstly discuss the QoS issue in IEEE 802.16 wireless MANs and propose a dynamic admission control scheme for scheduling services defined in the 802.16 specification. The proposed scheme provides the highest priority for Unsolicited Grant Service (UGS) connections and maximizes the bandwidth utilization by employing bandwidth borrowing and degradation. We develop an approximate analytical model to evaluate the system performance by assuming that the traffic processes of all scheduling services are Poisson processes. In fact, the self-similarity of non-voice traffic makes its traffic process far from Poisson process and should be modeled by Poisson Pareto Burst Process (PPBP). Therefore, in the later part of the paper, we analyze upper bound blocking probabilities of all scheduling services above the packet level using PPBP model for fractal traffic and Gaussian model for aggregated traffic in large wireless network as well as using the Chernoff bound method. Based on the analytical results, we give another admission control and bandwidth allocation mechanism above the packet level so as to minimize the blocking probability of each type of service in IEEE 802.16 wireless MAN. Analytical and simulation results are obtained and compared to demonstrate the effectiveness of proposed schemes and validate our analytical models.     

Dynamic multiple-frame bandwidth provisioning with fairness and revenue considerations for Broadband Wireless Access Systems

The increasing demand for wireless heterogeneous multimedia services presents a real challenge to mobile network operators. Even with the substantial increase in the supported bandwidth in emerging Broadband Wireless Access Systems (BWASs) such as 3.5G High Speed Downlink Packet Access (HSDPA) and the Worldwide Interoperability for Microwave Access (WiMAX), satisfying the bandwidth requirements of mobile users while increasing the revenues of network operators is still one of the major issues in these systems. Therefore, bandwidth provisioning will certainly play a decisive role in the success of such BWASs. In this paper, we propose a novel dynamic multiple-frame bandwidth provisioning scheme for BWASs. The proposed scheme spans multiple time frames and optimally allocates them to the different classes of traffic depending on their weights, the real-time bandwidth requirements of their users’ connections, their channel quality conditions and the expected obtained revenues. To maximize fairness and still maintain service differentiation between classes, we provide a unique formulation for dynamically computing the class weights. Simulation results are provided to show the potential and effectiveness of our scheme.     

一种改进的无线网络TCP拥塞控制算法

传统基于有线环境的传输控制协议(TCP)技术无法适应链路质量相对较差的无线环境。为此,提出一种改进的对数增加自适应减少(NewLIAD)算法。在慢启动阶段根据带宽确定最优拥塞窗口,在网络拥塞阶段动态减少拥塞窗口,以保证系统的整体吞吐量。仿真结果表明,该算法有较好的发送速率平滑性,能减少数据抖动,提升无线网络的TCP性能。     

WiMAX网络中信噪比与带宽结合的接纳控制算法

呼叫接纳控制（CAC）是宽带无线接入网络无线资源管理中一个重要的组成部分,其中策略设计的好坏直接影响着网络的性能和资源利用率。针对现有基于WiMAX的接纳控制算法仅考虑了带宽作为接纳控制的标准,提出一种结合带宽和信噪比的接纳控制算法,在考虑小区带宽因素的同时能兼顾考虑接纳后业务的信噪比情况。仿真结果表明,结合带宽和信噪比的接纳控制算法可以有效的降低系统中呼叫的掉线率,提高系统性能。     

无线多媒体网络中一种基于测量网络状态的动态呼叫接纳控制算法

提出了一种无线多媒体网络中基于测量网络状态的动态呼叫接纳控制算法.它区分了实时和非实时业务,在网络带宽资源不足时可通过降低非实时业务带宽确保实时业务呼叫连接的可靠性;还可根据当前网络状况调整预留带宽大小,使小区实时业务切换呼叫掉线率低于设定的门限值.大量仿真结果显示该算法具有低实时业务切换呼叫掉线率和与固定预留方案相当的带宽利用率,而只以略高的新呼叫阻塞率为代价,适合各种不同概率发生时实际应用的情况.     

Multimedia streaming gateway with jitter detection

This paper investigates a novel active buffer management scheme, "Jitter Detection" (JD) for gateway-based congestion control to stream multimedia traffics in packet-switched networks. The quality of multimedia presentation can be greatly degraded due to network delay variation or jitter when transported over a packet-switched network. Jitter degrades the timing relationship among packets in a single media stream and between packets from different media streams and, hence, creates multimedia synchronization problems. Moreover, too much jitter will also degrade the performance of the streaming buffer in the client. Packets received by the client will be rendered useless if they have accumulated enough jitter. The proposed active buffer management scheme will improve the quality of service in multimedia networking by detecting and discarding packets that accumulated enough jitter, such as to maintain a high bandwidth for packets within the multimedia stream's jitter tolerance. Simulation results have shown that the proposed scheme can effectively lower the average received packet jitter and increase the goodput of the received packets when compared to random early detection (RED) and DropTail used in gateway-based congestion control. Furthermore, simulation results have also revealed that the proposed scheme can maintain the same TCP friendliness when compared to that of RED and DropTail used for multimedia streams.     

一种适用于宽带无线多媒体网络的上行带宽分配方案

提出了一种适用于宽带无线多媒体网络的上行无线带宽分配方案。该方案将业务数据分为3种类型,即实时恒定速率业务、恒定变速率业务、非实时业务,针对不同业务对时延和带宽的不同需求,采取不同的方法获取上行带宽,较好地解决了多业务并发时的上行带宽分配问题,较传统技术提高了带宽利用率,减少了协议开销和传输时延。在详细描述算法的基础上,建立了对应的仿真系统对算法进行了验证。     

基于QPID-AVQ的组播拥塞控制机制

针对现有多媒体组播拥塞控制协议的不足,提出基于QPID虚拟队列管理的组播拥塞控制机制QPID-MCC。QPID-MCC在瓶颈路由器中采用QPID-AVQ队列管理策略,结合显式拥塞指示(ECN),按照一定的概率标记新到分组。接收端依据标记概率计算期望的TCP友好速率。发送端依据接收端的反馈信息并结合多媒体的最小带宽需求调整发送速率。仿真结果表明,QPID-MCC具有平滑稳定的发送速率、较好的公平性和较快的拥塞响应速度,并能满足最小带宽要求,保证多媒体业务的服务质量。     

Integrated Multimedia Personal Communications with Asymmetric Services for Mobile Users in Cellular Systems

Wireless personal communication networks are evolving to provide integrated multimedia services to mobile users. An important issue in their design is the accommodation of various services each having predefined Quality-of-Service (QoS) requirements. Efficient resource utilization can be achieved using a medium access scheme that allows various traffic components to be statistically multiplexed and a call admission control to prevent overload. Some multimedia services have asymmetric resource needs. For example, web browsing generally requires more downlink bandwidth than uplink bandwidth. We present a medium access scheme and a call admission control algorithm for guaranteed QoS provisioning in asymmetric integrated multimedia personal communication networks. An overall performance analysis model is developed. Performance characteristics are calculated and presented for an example system.     

基于IEEE802．16Mesh网络的拥塞控制方法

随着网络服务类型的增加和用户对带宽需求的增长,宽带无线接入技术受到关注。该文介绍IEEE802．16的Mesh结构,阐述在Mesh结构下的拥塞控制,提出一种动态改变传输等待时间指针和动态分配微时隙的拥塞控制方法。仿真结果证明,该方法可有效控制拥塞,增加吞吐量,降低丢包率和端到端时延。     

An efficient bandwidth allocation algorithm for real-time VBR stream transmission under IEEE 802.16 wireless networks

This paper investigates variable rate control strategies for real-time multimedia variable bit rate (VBR) services over IEEE 802.16 broadband wireless networks. A data rate control mechanism is derived for the case where the uplink channel provides real-time services and the traffic rate parameter remains constant. This paper shows that the common queuing scheduling algorithms have some bandwidth allocation fairness problems for the real-time polling service (rtPS) in the MAC layer. In other words, the use of a VBR for the rtPS by a WiMAX system results in additional access latency jitter and bandwidth allocation disorder in the transmitted multimedia streams during the regular time interval polling of subscribe stations (SSs) for the contention bandwidth request period. However, the proposed scheduling algorithm solves these SSs contending with bandwidth resource allocation problems based on an extended rtPS (ertPS) of quality-of-service (QoS) pre-programming for a ranging response non-contention polling period. The adopted bandwidth allocation of max–min fairness queue scheduling uses a time constraint condition to transmit real-time multimedia VBR streaming in an IEEE 802.16 broadband wireless environment. In addition, we use the ns-2 simulation tool to compare the capacity of multimedia VBR stream and show that the proposed ertPS scheduling algorithm outperforms other rtPS scheduling algorithms.     

Social-connectivity-aware vertical handover for heterogeneous wireless networks

Vertical handover mechanism for a WLAN-cellular heterogeneous network could be made efficient with the use of context aware admission control strategy. Existing admission control methods aim to provide satisfactory quality of service, but rely solely on the availability of wireless resources in the target network. We propose that the admission control in WLAN should make use of social connectivity context of users in its coverage area to classify local and global traffic. In this paper, we introduce a novel Social-Connectivity-aware Vertical Handover (SCVH) scheme, which performs admission control using connectivity graph data from the online social networking services. A higher importance of visiting node for users resident in WLAN, advocates a higher priority for granting admission. We employ graph-theoretic concept of centrality to calculate the social importance of potential handing-over nodes. By giving handover precedence to higher-centrality nodes, we achieve an optimal allocation of wireless resources in addition to improved quality of service. The proposed handover strategy offers an additional advantage of reducing global social network traffic.     

Improving Throughput of Transmission Control Protocol Using Cross Layer Approach

Most of the internet users connect through wireless networks. Major part of internet traffic is carried by Transmission Control Protocol (TCP). It has some design constraints while operated across wireless networks. TCP is the traditional predominant protocol designed for wired networks. To control congestion in the network, TCP used acknowledgment to delivery of packets by the end host. In wired network, packet loss signals congestion in the network. But rather in wireless networks, loss is mainly because of the wireless characteristics such as fading, signal strength etc. When a packet travels across wired and wireless networks, TCP congestion control theory faces problem during handshake between them. This paper focuses on finding this misinterpretation of the losses using cross layer approach. This paper focuses on increasing bandwidth usage by improving TCP throughput in wireless environments using cross layer approach and hence named the proposed system as CRLTCP. TCP misinterprets wireless loss as congestion loss and unnecessarily reduces congestion window size. Using the signal strength and frame error rate, the type of loss is identified and accordingly the response of TCP is modified. The results show that there is a significant improvement in the throughput of proposed TCP upon which bandwidth usage is increased.     

Implementation of call admission control scheme in next generation mobile communication networks using particle swarm optimization and fuzzy logic systems

In the present and next generation wireless networks, cellular system remains the major method of telecommunication infrastructure. Since the characteristic of the resource constraint, call admission control is required to address the limited resource problem in wireless network. The call dropping probability and call blocking probability are the major performance metrics for quality of service (QoS) in wireless network. Many call admission control mechanisms have been proposed in the literature to decrease connection dropping probability for handoffs and new call blocking probability in cellular communications. In this paper, we proposed an adaptive call admission control and bandwidth reservation scheme using fuzzy logic control concept to reduce the forced termination probability of multimedia handoffs. Meanwhile, we adopt particle swarm optimization (PSO) technique to adjust the parameters of the membership functions in the proposed fuzzy logic systems. The simulation results show that the proposed scheme can achieve satisfactory performance when performance metrics are measured in terms of the forced termination probability for the handoffs, the call blocking probability for the new connections and bandwidth utilization.     

异构无线网络中动态优先级接纳控制算法研究

针对在应急情况下的异构网络环境中不同类型业务在群组切换时出现的网络拥塞问题,以及现有研究中较少考虑不同类型用户所进行的业务的重要性和紧急性不同,从而不能合理分配有限的网络资源的情况,提出了一种异构无线网络中动态优先级接纳控制算法。首先,根据用户类型和业务类型对业务设定初始优先级;然后,根据业务的执行紧迫性和业务的剩余价值密度对业务优先级进行动态调整,并提出了一种基于业务优先级的抢占调度算法;最后为避免在业务优先级进行动态调整过程中出现颠簸调度现象,给出了避免颠簸调度的条件。所提算法考虑了实际情况中不同用户类型所进行的业务重要程度的不同,对业务进行了优先级设定,使初始优先级高的业务能够优先得到服务,在此基础上为尽量满足整体用户的用网需求,对业务的优先级进行了动态调整。为验证所提方法的有效性,将基于优先级队列调度算法和基于阻塞率约束的群组切换方法作为对比算法,在MATLAB软件环境下进行仿真分析。结果表明,所提方法相较于对比算法能够在减少业务切换的阻塞率的同时,使总体业务的完成率提高10%左右,证明了该算法在使初始优先级高的业务能够优先得到服务的同时,为初始优先级低的业务提供了网络切换的条件,从而提高了网络资源分配的合理性和公平性。     

基于蓝牙的连续媒体实时传输技术的研究

由于蓝牙无线信道带宽较窄且动态变化，在其上实时传输连续媒体数据是一个巨大挑战．本文研究了其中若干关键技术．包括蓝牙通信技术、视频／音频压缩技术和自适应服务质量控制技术等．文中提出了一种基于简单网络管理协议(SNMP)的自适应服务质量控制方案．设计了蓝牙多媒体传输管理信息库(简称BMT—MIB)，通过动态监测当前蓝牙无线信道和终端系统状态，有效利用带宽等资源．文中还给出了基于蓝牙的远程监控系统原型的设计和实现。     

Bandwidth Aggregation-Aware Dynamic QoS Negotiation for Real-Time Video Streaming in Next-Generation Wireless Networks

In next generation wireless networks, Internet service providers (ISPs) are expected to offer services through several wireless technologies (e.g., WLAN, 3G, WiFi, and WiMAX). Thus, mobile computers equipped with multiple interfaces will be able to maintain simultaneous connections with different networks and increase their data communication rates by aggregating the bandwidth available at these networks. To guarantee quality-of-service (QoS) for these applications, this paper proposes a dynamic QoS negotiation scheme that allows users to dynamically negotiate the service levels required for their traffic and to reach them through one or more wireless interfaces. Such bandwidth aggregation (BAG) scheme implies transmission of data belonging to a single application via multiple paths with different characteristics, which may result in an out-of-order delivery of data packets to the receiver and introduce additional delays for packets reordering. The proposed QoS negotiation system aims to ensure the continuity of QoS perceived by mobile users while they are on the move between different access points, and also, a fair use of the network resources. The performance of the proposed dynamic QoS negotiation system is investigated and compared against other schemes. The obtained results demonstrate the outstanding performance of the proposed scheme as it enhances the scalability of the system and minimizes the reordering delay and the associated packet loss rate.     

An Efficient Resource Allocation Mechanism for LTE–GEPON Converged Networks

Optical–wireless convergence is becoming popular as one of the most efficient access network designs that provides quality of service (QoS) guaranteed, uninterrupted, and ubiquitous access to end users. The integration of passive optical networks (PONs) with next-generation wireless access networks is not only a promising integration option but also a cost-effective way of backhauling the next generation wireless access networks. The QoS performance of the PON–wireless converged network can be improved by taking the advantages of the features in both network segments for bandwidth resources management. In this paper, we propose a novel resource allocation mechanism for long term evolution–Gigabit Ethernet PON (LTE–GEPON) converged networks that improves the QoS performance of the converged network. The proposed resource allocation mechanism takes the advantage of the ability to forecast near future packet arrivals in the converged networks. Moreover, it also strategically leverages the inherited features and the frame structures of both the LTE network and GEPON, to manage the available bandwidth resources more efficiently. Using extensive simulations, we show that our proposed resource allocation mechanism improves the delay and jitter performance in the converged network while guarantying the QoS for various next generation broadband services provisioned for both wireless and wired end users. Moreover, we also analyze the dependency between different parameters and the performance of our proposed resource allocations scheme.