A performance evaluation approach for GSM-based information services

The ever increasing diffusion of mobile communications will lead to massive mobile access to the Internet. The paper focuses on the wireless application protocol (WAP) for providing mobile information services, as envisaged by the personalized access to local information and services for tourists (PALIO) project within the fifth research framework of the European Commission. In particular, we consider a global system for mobile communications (GSM) network where WAP traffic is transported by the short message service (SMS) on specific GSM signaling channels. We develop suitable traffic models for both the WAP downlink traffic and the signaling traffic. An analytical approach is described that allows evaluation of the mean transmission delay of a WAP page. Finally, a downlink traffic scheduling policy is proposed in order to reduce the delay variance so that users experience a more regular traffic behavior (service usability requirement). The theoretical derivations for the GSM-SMS scenario are general and can also be tailored for other mobile communication systems. The study allows dimensioning of both the service and the downlink signaling traffic capacity in order to fulfill quality-of-service requirements for users.     

基于WAP平台的图像采集浏览系统的研究

针对WAP平台业务发展的一些问题,特别是现阶段流媒体业务对移动终端的限制,本文依据WAP协议理论模型,采用图像采集、处理技术和网络通信技术,研究与实现了WAP平台下准实时图像采集浏览系统,从而基于WAP平台实现了支持任一WAP移动终端的实时图片浏览业务.这是一种新的WAP增值业务,较好地绕过了上述瓶颈.经测试证明,该图像采集浏览系统实现了良好的图像采集浏览效果.     

移动Web浏览业务及关键技术

移动浏览业务是移动增值业务中一类非常重要且应用率非常高的业务.随着移动通信及智能手机技术的不断发展,移动浏览业务经历了从WAP浏览到Web浏览的发展.本文分析和研究了Web浏览业务的概念以及关键技术.     

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.     

Expedited forwarding end‐to‐end delay and jitter in DiffServ

The scheduling disciplines and active buffer management represent the main components employed in the differentiated services (DiffServ) data plane, which provide qualitative per‐hop behaviors corresponding to the QoS required by supported traffic classes. In the first part of this paper, we compute the per‐hop delay bound that should be guaranteed by the different multiservice scheduling disciplines, so that the end‐to‐end (e2e) delay required by expedited forwarding (EF) traffic can be guaranteed. Consequently, we derive the e2e delay bound of EF traffic served by priority queuing–weighted fair queuing (PQ–WFQ) at every hop along its routing path. Although real‐time flows are principally offered EF service class, some simulations on DiffServ‐enabled network show that these flows suffer from delay jitter and they are negatively impacted by lower priority traffic. In the second part of this paper, we clarify the passive impact of delay jitter on EF traffic, where EF flows are represented by renewal periodic ON–OFF flows, and the background (BG) flows are characterized by the Poisson process. We analyze through different scenarios the jitter effects of these BG flows on EF flow patterns when they are served by a single class scheduling discipline, such as first‐input first‐output, and a multiclass or multiservice scheduling discipline, such as static priority service discipline. As a result, we have found out that the EF per‐hop behaviors (PHBs) configuration according to RFCs 2598 and 3246 (IETF RFC 2598, June 1999; RFC 3246, IETF, March 2002) cannot stand alone in guaranteeing the delay jitter required by EF flows. Therefore, playout buffers must be added to DiffServ‐enabled networks for handling delay jitter problem that suffers from EF flows. Copyright © 2008 John Wiley & Sons, Ltd.     

Radio resource management schemes for combined GSM/GPRS mobile systems

Data services like Web browsing, e‐mail and file transfer are becoming more and more popular in cellular systems. In contemporary systems like Global System for Mobile communications (GSM), data transfer has been circuit‐switched, that is, physical resources are allocated to a user for the entire call/session duration. However, this is inefficient in case of bursty traffic, where bursts are separated by long intervals of inactivity. This has been the main reason for the introduction of General Packet Radio Service (GPRS), which on the one hand acts as a mobile access network to the Internet, while on the other hand it enables the operator to offer a wide variety of value‐added services [Wireless Access Protocol (WAP) over GPRS, e/m‐banking, e/m‐commerce, push services, etc.] efficiently. However, in contemporary commercial implementations of GPRS the radio resource allocation algorithm does not take into account the Quality of Service (QoS)‐related service characteristics—although such information is exchanged between the terminal and the network—and consequently all service requests are treated the same way (‘best effort’). In this paper, we propose and evaluate via a simulation platform various Radio Resource Management (RRM) schemes capable of differentiating the handling of ‘service requests’ (in uplink and downlink), taking into account the GPRS‐related QoS parameters (precedence, reliability, delay, mean and peak throughput). The evaluation is performed for a range of voice (circuit‐switched) traffic loads, number of Transmit Receive eXchange (TRXs), offered data (packet‐switched) services characteristics, number of dedicated Packet Data Channels (PDCHs), and so on, taking into account the respective QoS requirements for both service types (circuit‐ and packet‐switched). Copyright © 2003 John Wiley & Sons, Ltd.     

Scheduling Algorithms for Packet-Oriented MAC Protocols in Wireless Multimedia Systems

Future generation wireless multimediacommunications will require efficient Medium AccessControl (MAC) protocols able to guarantee suitable Qualityof Service (QoS) levels for different traffic classes whileachieving a high utilization of radio resources. This paperproposes a new scheduling technique to be adopted at the MAClevel in wireless access systems, named Dynamic Scheduling-Time DivisionDuplexing (DS-TDD), that efficiently managesvideo, voice, Web and background traffics. A theoretical approachis proposed in this paper to evaluate the DS-TDD performance withvoice and Web traffics. Simulation results have permitted tohighlight the following promising characteristics of the DS-TDDscheme: (i) a high capacity of real-time traffics isattained with a QoS insensitive to Web and background trafficloads; (ii) a high throughput can be guaranteed whilepreserving the QoS levels of the different traffic classes;(iii) heavier downlink traffic loads do not modify the QoSof uplink traffics. Finally, extensive comparisons with differentscheduling schemes proposed in the literature have permitted tohighlight the better performanceof DS-TDD.     

Using GI‐G‐1 queuing model for rtPS performance evaluation in 802.16 networks

Among the scheduling services, rtPS (real‐time polling service) is designated for real‐time applications. Among three packet delay intervals, performance effect on polling interval has been widely studied, but less on the intervals of scheduling and delivery. To evaluate the performance of delay‐sensitive rtPS applications, instead of using continuous queueing model, a discrete‐time GI‐G‐1 model, which considers intervals of polling, scheduling, and delivery, is proposed. By taking VoIP as a typical rtPS application, the transmission latency under different QoS settings, polling probability, and traffic load are presented. The latency is also compared among various codec schemes. The results indicate that when the codec rate is either fulfilled or dissatisfied by the promised bandwidth of service levels, the performance is highly dependent upon the polling probability, no matter what the traffic condition is. However, if the codec rate is in between the promised bandwidth of various service levels, the polling probability is a dominant factor in light traffic environment, while the settings on QoS parameters will strongly determine the performance in heavy traffic situation. In addition to the verification using simulation, the bandwidth utilization derived from the GI‐G‐1 model can be applied to improve the serving capacity of base stations. Copyright © 2011 John Wiley & Sons, Ltd.     

A LP-based Admission Control Using Artificial Neural Networks for Integrated Services in Mobile Networks

In mobile networks the traffic fluctuation is unpredictable dueto mobility and varying resource requirements of multimedia applications.Henceit is essential to maintain the traffic within the network capacity to providethe service guarantees to running applications. Thispaper proposes an Admission Control (AC) scheme in a single mobile cellularenvironment supporting real-time and non-real-time application traffic. In thecase of a real-time and non-real-time multimedia applications, eachapplication has its own distinct range of acceptable Quality of Service (QoS)requirements(e.g., packet loss, delay, jitter, etc.). The network provides the service bymaintaining the application specified QoS range. We propose a LinearProgrammingResource Reduction (LP-RR) principle for admission control by maintainingQoSguarantees to existing applications and to increase the percentage ofadmissionto real-time and non-real-time applications. Artificial Neural Networks (ANNs)are used to solve linear programming problem, which facilitates an on-lineadmissioncontrol decision in the practical systems.The simulation results demonstrate that the proposed AC schemeperforms well in terms of admitted applications and maintains lower percentageof rejection to hand-off and new applications of different traffic classes.The suggested principle also shown that it is appropriate for the fairresourceallocation with improved resource utilization.     

Quality-of-Service in IP Services over Bluetooth Ad-Hoc Networks

Along with the development of multimedia and wireless networking technologies, mobile multimedia applications are playing more important roles in information access. Quality of Service (QoS) is a critical issue in providing guaranteed service in a low bandwidth wireless environment. To provide Bluetooth-IP services with differentiated quality requirements, a QoS-centric cascading mechanism is proposed in this paper. This innovative mechanism, composed of intra-piconet resource allocation, inter-piconet handoff and Bluetooth-IP access modules, is based on the Bluetooth Network Encapsulation Protocol (BNEP) operation scenario. From our simulations the handoff connection time for a Bluetooth device is up to 11.84 s and the maximum average transmission delay is up to 4e-05 s when seven devices join a piconet simultaneously. Increasing the queue length for the Bluetooth-IP access system will decrease the traffic loss rate by 0.02 per 1000 IP packets at the expense of a small delay performance.     

A distributed MAC scheme supporting voice services in mobile ad hoc networks

Future mobile ad hoc networks are expected to support voice traffic. The requirement for small delay and jitter of voice traffic poses a significant challenge for medium access control (MAC) in such networks. User mobility presents unique difficulties in this context due to the associated dynamic path attenuation. In this paper, a MAC scheme for mobile ad hoc networks supporting voice traffic is proposed. With the aid of a low‐power probe prior to DATA transmissions, resource reservation is achieved in a distributed manner, thus leading to small packet transmission delay and jitter. The proposed scheme can automatically adapt to dynamic path attenuation in a mobile environment. Statistical multiplexing of on/off voice traffic can also be achieved by partial resource reservation for off voice flows. Simulation results demonstrate the effectiveness of the proposed scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

WAP--移动用户与Internet连接的纽带

介绍了WAP出现的背景、WAP概念及用于网内的模型、功能、分层结构及所能进行的网上业务等等,并以网络浏览业务为例,介绍了应用WAP上网接续的过程,说明WAP起到了移动用户与Internet／Intranet连接的纽带作用。     

新一代移动通信综合业务信息服务系统

无线应用协议 (WAP)融合了因特网技术与移动通信技术的优势 ,成为事实上的业界标准。基于WAP技术提供无线信息服务已成为目前移动通信与信息行业新的业务增长点。文章通过对WAP技术及其应用现状的分析 ,提出新一代移动通信综合业务信息服务系统解决方案。该系统将运营商优势与WAP技术充分结合 ,实现符合当前无线应用需求的运营模式和体系结构。     

移动互联网在全球的发展和应用前景

移动与互联网的结合是历史的必然，目前基于第二代移动网解决高速接入的途径主要是ＧＰＲＳ，以后视不同情况直接过渡到第三代或转而采用ＥＤＧＥ；解决手机上网浏览的技术目前最看好的是ＷＡＰ。对于移动互联网和ＷＡＰ，尽管市场预测大多很乐观，但仍有一些亟等解决的问题，主要有移动网带宽受限、各方面协调、ＷＡＰ有待进一步成熟、信息内容缺乏、手机屏幕面积小以及朵上操作不方便等问题。     

Performance analysis of the IEEE 802.16e sleep mode for correlated downlink traffic

In this paper, we evaluate the performance of the IEEE 802.16e sleep mode mechanism in wireless access networks. This mechanism reduces the energy consumption of a mobile station (MS) by allowing it to turn off its radio interface (sleep mode) when there is no traffic present at its serving base station (BS). After a sleep period expires, the MS briefly checks the BS for data packets and switches off for the duration of another sleep period if none are available. Specifically for IEEE 802.16e, each additional sleep period doubles in length, up to a certain maximum. Clearly, the sleep mode mechanism can extend the battery life of the MS considerably, but also increases the delay at the BS buffer. For the performance analysis, we use a discrete-time queueing model with general service times and multiple server vacations. The vacations represent the sleep periods and have a length depending on the number of preceding vacations. Unlike previous studies, we take the (short-range) traffic correlation into account by assuming a D-BMAP arrival process, i.e. the distribution of the number of packet arrivals per slot is modulated by the transitions in a Markov chain with N background states. As results, we obtain the distribution of the number of packets in the queue at various sets of time epochs, the distribution of the packet delay and the antenna activity rate. We apply these results to the IEEE 802.16e sleep mode mechanism with correlated downlink traffic. By means of some examples, we show the influence of both the configuration parameters and the traffic correlation on the delay and the energy consumption.     

Research and design of wap service system based on MISC platform

1 Introduction With the introduction of high mobile handsets with increasingly powerful functions and the applications of WAP2.0 with considerably novel technologies, a series of diverse hot WAP services have come into being and have been successfully lau…     

Two-level pointer forwarding strategy for location management in PCS networks

For a IPCS network to effectively deliver services to its mobile users, it must have an efficient way to keep track of the mobile users. The location management fulfills this task through location registration and paging. To reduce the signaling traffic, many schemes such as a local anchor (LA) scheme, per-user caching scheme and pointer forwarding scheme have been proposed in the past. In this paper, we present a new location management scheme which intends to mitigate the signaling traffic as well as reduce the tracking delay in the PCS systems. In this strategy, we choose a set of visitor location registers (VLRs) traversed by users as the mobility agents (MA), which form another level of management in order to make some registration signaling traffic localized. The idea is as follows: instead of always updating to the home location register (HLR), which would become the bottleneck otherwise, many location updates are carried out in the mobility agents. Thus, the two-level pointer forwarding scheme is designed to reduce the signaling traffic: pointers can be set up between VLRs as the traditional pointer forwarding scheme and can also be set up between MAs. The numerical results show that this strategy can significantly reduce the network signaling traffic for users with low CMR without increasing much of the call setup delay.     

Adaptive Inter Vehicle Communications

Inter Vehicle Communications (IVC) have the potential to significatively increase the safety in our highways. In such communications, the quality and reliability of service becomes a very critical issue. In particular, it is important that in case of emergencies, when the inter vehicle traffic increases exponentially, the message delay should be kept low. We present a reliable hierarchical routing protocol that uses load balancing to keep message delay low even in presence of high level of traffic. Our protocol is based on geographical routing. The protocol is designed for highway travelers but can be used in other mobile ad-hoc scenarios. The highway is divided in virtual cells, which moves as the vehicles moves. The cell members might choose one or more Cell_Leaders that will behave for a certain time interval as Base Stations. We assume that every node knows its geographical position, given by Global Positioning System (GPS) or some other method. Cell_Leaders form a virtual backbone that is used to forward messages among nodes on different cells. The traffic is distributed among Cell_Leaders in order to optimize the communication delay. We study the effect of load balancing in minimizing delay. Our simulation results show that our proposed protocol improves the delay and the network utilization compared to existing inter vehicles protocols.     

Wireless Internet Access Using IS-2000 Third Generation System: A Performance and Capacity Study

The Internet has been growing tremendously in the recent years and applications like web browsing are becoming increasingly popular. In a collective effort to provide seamless access to the Internet, wireless equipment manufacturers and service providers are developing 3G wireless systems that efficiently support current and future Internet applications. In this paper, we evaluate the performance and capacity of a 3G wireless data system based on IS-2000 standard. We consider web browsing as the common application for all users and evaluate the system performance for single and parallel web browsing sessions. We perform this study through a detailed simulation of web traffic model described by distributions of number of objects per page, object size, page request size and page reading time. The simulation includes HTTP and TCP/IP protocols, link level recovery, radio resource management, mobility, channel model and, delays in the Internet and the radio access network. We quantify important system attributes like average page download times and system throughput (Kb/s per carrier per sector). We also evaluate normalized object download time, normalized page download time, penalty in performance due to link errors, link layer buffer sizes needed, channel holding time, average power used and distribution of the power used in the system.     

Quality of Service Schemes for IEEE 802.11 Wireless LANs – An Evaluation

This paper evaluates four mechanisms for providing service differentiation in IEEE 802.11 wireless LANs. The evaluated schemes are the Point Coordinator Function (PCF) of IEEE 802.11, the Enhanced Distributed Coordinator Function (EDCF) of the proposed IEEE 802.11e extension to IEEE 802.11, Distributed Fair Scheduling (DFS), and Blackburst. The evaluation was done using the ns-2 simulator. Furthermore, the impact of some parameter settings on performance has also been investigated. The metrics used in the evaluation are throughput, medium utilization, collision rate, average access delay, and delay distribution for a variable load of real time and background traffic. The simulations show that the best performance is achieved by Blackburst. PCF and EDCF are also able to provide pretty good service differentiation. DFS can give a relative differentiation and consequently avoids starvation of low priority traffic.