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1.
Always best connected 总被引:17,自引:0,他引:17
2.
Network selection mechanisms play a vital role in ensuring quality of service in the heterogeneous multi-access environment. In this article we develop a network selection scheme for an integrated cellular/wireless local area network (WLAN) system to guarantee mobile users being always best connected (ABC). The proposed scheme comprises three parts, with the first detecting the availability of WLAN, while the second applying an analytic hierarchy process (AHP) to decide the relative weights of evaluative criteria set according to user preferences, network condition and service applications, the third normalizing parameters and calculating decision-making index. Simulations conducted in a heterogeneous system with UMTS and wireless LAN reveal that the proposed network selection technique can effectively decide the optimum network through making trade-offs among network condition, user preference, and service application, while avoiding frequent handoffs. 相似文献
3.
Chen Yiping Yang Yuhang 《Wireless Communications, IEEE》2007,14(2):36-41
In recent years, wireless communication technology has undergone a tremendous change. Various radio access technologies have been deployed all over the world. The 4G mobile system was proposed to integrate all of these radio access technologies into a common network called the open wireless architecture (OWA) platform. As one of the main features of a 4G mobile system, always best connected (ABC) services enable users to choose the best available access networks in a way that best suits their needs. A new architecture capable of supporting ABC service is proposed in this study. There are three parts to the proposed architecture. First, a novel access discovery mechanism that integrates service location protocol and location-based service is presented. Second, a new personalized network selection scheme is put forward. Users can select their personalized "best" network by changing weight factors and constraints in a single objective optimization problem. Third, a seamless handover mechanism based on Mobile IPv6 is proposed. The mechanism supports end-to-end quality of service. Through analysis, this architecture demonstrates that it has benefits not only for network operators, but also for users 相似文献
4.
Seamless continuity of real-time video across UMTS and WLAN networks: challenges and performance evaluation 总被引:1,自引:0,他引:1
《Wireless Communications, IEEE》2005,12(3):8-18
This article addresses several challenges related to the evolution toward seamless interworking of wireless LAN and 3G cellular networks. The main objective is to evaluate the conditions and restrictions under which seamless continuity of video sessions across the two networks is feasible. For this purpose, we formulate a number of practical interworking scenarios, where UMTS subscribers with ongoing real-time video sessions hand over to WLAN, and we study the feasibility of seamless continuity by means of simulation. We particularly quantify the maximum number of UMTS subscribers that can be admitted to the WLAN, subject to maintaining the same level of UMTS QoS and respecting the WLAN policies. Our results indicate that the WLAN can support seamless continuity of video sessions for only a limited number of UMTS subscribers, which depends on the applied WLAN policy, access parameters, and QoS requirements. In addition to this study, we do address several other issues that are equally important to seamless session continuity, such as the QoS discrepancies across UMTS and WLAN, the vertical handover details, and various means of access control and differentiation between regular WLAN data users and UMTS subscribers. The framework for discussing these issues is created by considering a practical UMTS/WLAN interworking architecture. 相似文献
5.
Wei Zhuang Yung-Sze Gan Kok-Jeng Loh Kee-Chaing Chua 《Communications Magazine, IEEE》2003,41(11):118-125
Strong demands for public wireless broadband services will require more capacity than even that can be,supplied by advanced mobile cellular systems like the Universal Mobile Telecommunication System. The increasing popularity of WLANs has prompted mobile network operators to consider their deployment in high-density usage areas like indoor/outdoor public hotspots to provide complementary broadband access to their UMTS networks. In order to provide consistent QoS control over an integrated UMTS and WLAN system, a policy-based multidomain QoS management architecture is proposed in this article. Different UMTS-WLAN interworking scenarios are discussed to illustrate the feasibility of the proposed architecture. 相似文献
6.
《Communications Magazine, IEEE》2006,44(2):73-84
To offer wireless data access services that are more efficient than GPRS or UMTS networks, public WLANs are in a predominant position to embrace the wireless broadband era. Reusing the existing mechanisms for user authentication, access control, billing, and roaming handling procedures in mobile territory to construct a complementary network, public WLAN (PWLAN) has drawn the attention of cellular operators such as Vodafone and T-Mobile. In this article we aim to investigate a practical end-to-end PWLAN architecture capable of using GPRS/UMTS SIM-based authentication for current mobile users and carrying out Web-based authentication for occasional users without SIM modules simultaneously. Additionally, we consider a confederation of various PWLAN service providers by a RADIUS-based roaming mechanism to leverage the existing resources of cellular operators. The proposed considerations and guidelines provide a baseline skeleton to build an extendable environment and successfully construct a flexible cellular/PWLAN hotspot in mobeeLAN service. 相似文献
7.
随着3G移动通信应用业务不断丰富,通信网络的承载能力与大流量高宽带的业务需求之间的矛盾日益增加。3G技术难以支撑大量的数据用户的多媒体应用的需求。WLAN作为具有高性价比和大规模部署能力的无线数据技术,可以很好地卸载3G的压力。所以3G+WLAN互为补充的发展战略成为运营商的共同选择。本文回顾了多种3G和WLAN相结合... 相似文献
8.
The third generation partner project (3GPP) has standardized general packet radio service (GPRS) and the universal mobile
telecommunications system (UMTS) to provide cell phone communications and wireless Internet services. Although the data transmission
rate is lower than that of wireless local area networks (WLANs), GPRS/UMTS covers larger areas. Hence, to achieve higher speed
ubiquitous access, we propose a lightweight secure roaming mechanism (LSRM) that integrates GPRS/UMTS and WLAN. Taking advantage
of these two technologies, LSRM offers anonymous roaming and friendly subscriber management. Besides, we give a formal security
analysis to LSRM based on BAN authentication logic. 相似文献
9.
Home agent placement and IP address management for integrating WLANs with cellular networks 总被引:1,自引:0,他引:1
Behcet Sarikaya 《Wireless Communications, IEEE》2006,13(6):77-86
Seamless roaming between cellular networks (3G or upcoming 4G) and wireless local area networks can be provided using Mobile IP. However, GPRS/UMTS and 802.11-based WLAN networks have no native support for mobile IP. Mobile IP requires the deployment of home agents and a protocol between the mobile nodes, home agent, and corresponding nodes. We address the home agent placement and home address assignment issues for supporting mobile IP for heterogeneous roaming. Placement techniques for mobile IP home agents are presented including dynamic HA assignment in either WLAN or cellular network domains using the diameter mobile IP application. Next, we present several IPv4 home address assignment schemes for mobile nodes visiting in the WLAN domain such as NAT/NAPT traversal, reverse tunneling, and mobile VPNs. It is shown that HA placement and address management are orthogonal, and any combination is possible. Various architectures for both issues are evaluated against the optimal solutions 相似文献
10.
Interworking issues between Universal Mobile Telecommunication System (UMTS) and Wireless Local Area Network (WLAN) have become
a great matter of interest as an increasing number of mobile internet users require broadband wireless access to IP services
in the wide area. In this paper, we present a practical UMTS–WLAN interworking architecture based on 3GPP standards and propose
a seamless handoff scheme that guarantees low delay and low packet loss during UMTS–WLAN handoff. For low handoff delay, the
proposed handoff scheme performs pre-registration and pre-authentication processes before layer 2 handoff. Moreover, it uses
packet buffering and forwarding functions in order to reduce packet loss during the handoff period. On the above basis, detailed
signaling procedures are presented, together with system requirements when a mobile terminal moves from UMTS to WLAN and vice-versa.
Numerical results show that the proposed scheme performs well with respect to signaling cost, handoff delay, and packet loss
compared with conventional schemes. 相似文献
11.
《IEEE transactions on circuits and systems. I, Regular papers》2006,53(10):2125-2131
This paper presents a reconfigurable universal mobile telecommunication systems [(UMTS) and wireless local area network (WLAN) mode)] analog baseband transmitter channel composed of a current steering digital–analog converter (DAC), a transimpedance stage, and a low-pass reconstruction filter. The device operates from a single 1.2-V supply voltage while guaranteeing the high-linearity UMTS/WLAN standard requirements. It can be digitally programmed to process WLAN 802.11a/b/g and UMTS signals, by adjusting the DAC conversion frequency and the low-pass filter cutoff frequency. For the WLAN mode, the DAC operating frequency and the filter bandwidth are set to 100 and 11MHz, respectively, while for the UMTS mode, they are equal to 50 and 2.11MHz. The device is realized in a 1.2-V 0.13-$muhbox m$ standard CMOS technology. The die area occupation, equal to 0.9$hbox mm^2$ , has been minimized by optimizing the component sharing for the two operation modes. The proposed circuit achieves a 30.4 dBm third-order output referred intermodulation intercept point (OIP3) for the WLAN mode, and a 31.5 dBm-OIP3 when configured for the UMTS mode, while the spurious-free dynamic range is 58 dB for WLAN mode, and 60 dB for UMTS mode. The power consumption is optimized according to the operation mode and is 19.44 mW in WLAN mode and 16.8 mW in UMTS mode. 相似文献
12.
Sheng-Tzong Cheng Jian-Liang Lin 《Selected Areas in Communications, IEEE Journal on》2005,23(11):2093-2103
Many wireless access systems have been developed recently to support users mobility and ubiquitous communication. Nevertheless, these systems always work independently and cannot simultaneously serve users properly. In this paper, we aim to integrate IPv6-based wireless access systems and propose a coordinated call admission control mechanism to utilize the total bandwidth of these systems to minimize the call blocking probabilities, especially the handoff call dropping probabilities. First, we propose an integrated hierarchical wireless architecture over IPv6-based networks to combine the wireless access systems including cellular systems (second-generation, General Packet Radio Service, or third-generation), IEEE 802.11 a/b/g WLAN, and Bluetooth. In the proposed architecture, mobile user can request a call with quality-of-service (QoS) requirements by any wireless network interfaces that can be accessed. When the proposed coordinated call admission control (CCAC) mechanism receives a request, it takes the QoS requirements of the incoming call and the available and reserved bandwidth of this wireless system into consideration to accept or reject this request. Besides, the mechanism can coordinate with other wireless systems dynamically to adjust the bandwidth reserved for handoff calls at each wireless system in this architecture so as to reduce the call blocking probabilities. Once the call is admitted, the mobile user is able to access heterogeneous wireless access networks via multiple interfaces simultaneously. Finally, we evaluate this system to show that the CCAC on the proposed architecture outperforms other mechanisms proposed before. 相似文献
13.
Apostolis K. Salkintzis Nikos Passas Dimitris Skyrianoglou 《Wireless Communications and Mobile Computing》2008,8(7):857-869
In this paper, we address the architecture and the procedures that can enable voice call handover from UMTS to WLAN and we also study how efficiently the WLAN can support the voice calls transferred from UMTS. Our study is based on a practical simulation model that lets us quantify the maximum number of voice calls that can be handed over from UMTS to WLAN, subject to maintaining the same level of UMTS QoS and respecting some WLAN policies. In addition, several other voice call performance metrics are derived. Our results indicate that an IEEE 802.11e access point can support a limited number of voice calls handed over from UMTS, which depends primarily on the applied WLAN bandwidth sharing policy (i.e., how the bandwidth is shared between WLAN voice and data users) and the QoS requirements. The performance of the WLAN scheduling algorithm is also of paramount importance and in our study we consider the so‐called ARROW scheduler. Although the simulation results are derived for a specific bandwidth sharing policy, they can readily be scaled and provide practical upper bounds for the number of UMTS voice calls that can be seamlessly admitted to a WLAN access point. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
14.
《Latin America Transactions, IEEE (Revista IEEE America Latina)》2008,6(2):194-200
Next generation of mobile communications will be based on a heterogeneous infrastructure comprising different wireless access systems in a complementary manner. This paper proposes a network selection algorithm based on user activity, user preferences, service requirements, and networks conditions which provides users a prospect of being always best connected within an environment of heterogeneous mobile networks. This is achieved by a learning process which allows user to select an access network based in previous connections and a cost function that helps the user to select the best network that adapts to the needs. 相似文献
15.
WLAN作为一种无线接入技术,以其灵活性、移动性的特点越来越为广大公众所接受,已经成为运营商无线宽带业务中不可或缺的组成部分。但随着3G移动通信的日益普及,WLAN的经营策略及市场定位成为各大运营商亟待解决的问题。由于对WLAN认识的不同,运营商对WLAN的发展策略也不尽相同,但不可否认的是,WLAN对于分流无线数据流量起到的重要作用,随着智能终端的不断普及以及运营商的大力推动,WLAN业务必将会有广阔的发展空间。 相似文献
16.
Packet scheduling in 3.5G high-speed downlink packet access networks: breadth and depth 总被引:1,自引:0,他引:1
Bader Al-Manthari Hossam Hassanein Nidal Nasser 《IEEE network》2007,21(1):41-46
Forecasts for emerging mobile device markets anticipate that bandwidth will be squeezed by demanding applications like multimedia on demand. This will spur the need for data rates beyond what the upcoming 3G wireless cellular systems such as UMTS can offer. To boost the support for such high data rates, HSDPA, labeled as a 3.5G wireless system, has been introduced in Release 5 of UMTS technical specifications. HSDPA is a definite step toward meeting the "anywhere, anytime, and in any form" 4G communication concept. HSDPA promises a peak data rate of up to 10 Mb/s, five times larger than the data rate offered by 3G systems. In order to support such high data rates, HSDPA relies on many new technologies, among which is packet scheduling. In this article we provide breadth and depth related issues of packet scheduling in HSDPA, discuss state-of-the-art HSDPA scheduling algorithms in terms of their objectives, advantages, and limitations, and suggest further research issues that need to be addressed. In addition, we propose a packet scheduling algorithm for data traffic in HSDPA. Simulation results demonstrate the effectiveness of the proposed algorithm 相似文献
17.
18.
In the recent years, wireless communication systems have received increased interest in commercial applications. Different
kind of wireless public access have become increasingly available in various areas like airports, stations and shopping centers
as well as at office or at home. Mobile terminals, such as phones or laptops, are often equipped with several network interfaces
and may use simultaneously several access networks. For instance it is nowadays common to have UMTS, WiFi, BlueTooth, and
even WiMAX interfaces on a single mobile device. Each of them can be attached to different Internet providers offering seamless
connectivity, high-speed multimedia services with different billing models and security levels. In this paper, we focus on
an advanced middleware that allows, through a comprehensive profile management, the support of automatic interface configuration
and per-flow interface selection.The system takes into account preferences given by the terminals owner, the users and the
applications. This middleware makes the terminal to be always “best” connected and provides service continuity in case of
vertical handover. As illustration, we show how the proposed middleware allows cost-effective management of a fleet of terminals. 相似文献
19.
Wireless LAN access network architecture for mobile operators 总被引:16,自引:0,他引:16
The evolution of IP-based office applications has created a strong demand for public wireless broadband access technology offering capacity far beyond current cellular systems. Wireless LAN access technology provides a perfect broadband complement for the operators' existing GSM and GPRS services in an indoor environment. Most commercial public wireless LAN solutions have only modest authentication and roaming capability compared to traditional cellular networks. This article describes a new wireless LAN system architecture that combines the WLAN radio access technology with mobile operators' SIM-based subscriber management functions and roaming infrastructure. In the defined system the WLAN access is authenticated and charged using GSM SIM. This solution supports roaming between cellular and WLAN access networks and is the first step toward an all-IP network architecture. The proto-type has been implemented and publicly verified in a real mobile operator network 相似文献