Flat Cellular (UMTS) Networks

Traditionally, cellular systems have been built in a hierarchical manner: many specialized cellular access network elements that collectively form a hierarchical cellular system. When 2G and later 3G systems were designed there was a good reason to make system hierarchical: from a cost-perspective it was better to concentrate traffic and to share the cost of processing equipment over a large set of users while keeping the base stations relatively cheap. However, we believe the economic reasons for designing cellular systems in a hierarchical manner have disappeared: in fact, hierarchical architectures hinder future efficient deployments. In this paper, we argue for completely flat cellular wireless systems, which need just one type of specialized network element to provide radio access network (RAN) functionality, supplemented by standard IP-based network elements to form a cellular network. While the reason for building a cellular system in a hierarchical fashion has disappeared, there are other good reasons to make the system architecture flat: (1) as wireless transmission techniques evolve into hybrid ARQ systems, there is less need for a hierarchical cellular system to support spatial diversity; (2) we foresee that future cellular networks are part of the Internet, while hierarchical systems typically use interfaces between network elements that are specific to cellular standards or proprietary. At best such systems use IP as a transport medium, not as a core component; (3) a flat cellular system can be self scaling while a hierarchical system has inherent scaling issues; (4) moving all access technologies to the edge of the network enables ease of converging access technologies into a common packet core; and (5) using an IP common core makes the cellular network part of the Internet

Vertical Handoff Characterization for SIP and mSCTP Based UMTS-WLAN Integration Solutions

It is desirable to integrate 3G Universal Mobile Telecommunication System (UMTS) and 802.11 wireless local area networks, especially at hot-spot locations such as hotels and airports. The efficiency of wireless data services can be maximized if the integration provides users with seamless roaming across the two types of networks. Seamless handoff between these two networks to maintain session continuity is a major challenge in WLAN-3G integration. To achieve this goal, integration architectures together with mobility solutions such mobile stream control transmission protocol (mSCTP) and session initiation protocol (SIP) have been proposed in the literature. In this paper, we implement through simulations an integration architecture and characterize the vertical handoff delay for both mobility solutions mSCTP and SIP as a function of network parameters. This study finds that mSCTP perform better in terms of handoff delay compared to SIP for the assumptions specified in this paper

Analysis of the effect of mobile terminal speed on WLAN/3G vertical handovers

Proceedings of IEEE Global Telecommunications Conference, GLOBECOM '06, San Francisco, California, 27 november - 1 december, 2006.WLAN hot-spots are becoming widely spread. This, combined with the availability of new multi-mode terminals integrating heterogeneous technologies, opens new business opportunities for mobile operators. Scenarios in which 3G coverage is complemented by WLAN deployments are becoming available. Thus, true all-IP based networks are ready to offer a new variety of services across heterogeneous access. However, to achieve this, some aspects still need to be analyzed. In particular, the effect of the terminal speed on the detection and selection process of the preferred access network is not yet well understood. In fact, efficiency of vertical handovers depends on the appropriate configuration of mobile devices. In this paper we present a simulation study of handover performance between 3G and WLAN access networks showing the impact of mobile users’ speed. The mobile devices are based on the IEEE 802.21 cross layer architecture and use WLAN signal level thresholds as handover criteria. A novel algorithm to dynamically adjust terminals’ configuration is presented.Publicad

Efficient Handoff for QoS Enhancement in Heterogeneous Wireless Networks (UMTS/WLAN Interworking)

Today’s Wireless Communications technologies prove us that wireless communications will in the long run be composed of different communication networks as a way to benefit from each other. This can however be achieved from cellular networks and wireless local area networks that show some compatible characteristics that enable them be integrated. Scenarios typically behind these integrations is the UMTS and WLAN interworking where UMTS network is known for its wide area of coverage and nearly roaming however, known for lack of enough data rate. This is contrary with WLAN which is known for high data rate and cheaper compared to UMTS. WLAN however has a small area of coverage and lacks roaming. This in regard brings the idea that the two different networks being integrated could provide the means for mobile users to be gratified with a supported coverage and quality at anywhere and anytime with seamless access to internet

Secure 3G user authentication in ad-hoc serving networks

The convergence of cellular and IP technologies has pushed the integration of 3G and WLAN networks to the forefront. With 3G networks\u27 failure to deliver feasible bandwidth to the customer and the emerging popularity, ease of use and high throughput of 802.11 WLANs, integrating secure access to 3G services from WLANs has become a primary focus. 3G user authentication initiated from WLANs has been defined by an enhancement to the extensible authentication protocol, EAP, used to transport user authentication requests over WLANs. The EAP-AKA protocol executes the 3G USIM user challenge and response authentication process over the IP backbone for WLAN serving networks. To improve the degree of control of 3G subscribers, spatial control has been proposed for 3G-WLAN user authentication. Successful execution of 3G security algorithms can be limited to a specified area by encrypting a user\u27s authentication challenge with spatial data defining his/her visited WLAN. With 3G networks\u27 limited capacity to determine a user\u27s location to the granularity of a small WLAN area and restricted access to users\u27 location due to privacy, 3G operators must rely on spatial data sent from visited WLANs to implement control for authentication. The risks of implementing EAP-AKA spatial control by 3G operators with no prior relationship or trust for serving WLAN networks are presented in this paper. An ad-hoc architecture is proposed for serving networks in 3G-WLAN integration and the advantages of this architecture that facilitate secure 3G user authentication are identified. Algorithms are proposed to define robust trust relationships between the parties in 3G-WLAN networks. The security of 3G user authentication is further protected by new mechanisms defined that are based on the quality of trust established between parties

Interworking in heterogeneous wireless networks: comprehensive framework and future trends

Interworking mechanisms are of prime importance to achieve ubiquitous access and seamless mobility in heterogeneous wireless networks. In this article we develop a comprehensive framework to categorize interworking solutions by defining a generic set of interworking levels and its related key interworking mechanisms. The proposed framework is used to analyze some of the most relevant interworking solutions being considered in different standardization bodies. More specifically, I-WLAN and GAN approaches for WLAN and cellular integration, solutions for WiMAX and 3GPP LTE/SAE interworking, and the forthcoming IEEE 802.21 standard are discussed from the common point of view provided by the elaborated framework.Postprint (published version

Mobility and Handoff Management in Wireless Networks

With the increasing demands for new data and real-time services, wireless networks should support calls with different traffic characteristics and different Quality of Service (QoS)guarantees. In addition, various wireless technologies and networks exist currently that can satisfy different needs and requirements of mobile users. Since these different wireless networks act as complementary to each other in terms of their capabilities and suitability for different applications, integration of these networks will enable the mobile users to be always connected to the best available access network depending on their requirements. This integration of heterogeneous networks will, however, lead to heterogeneities in access technologies and network protocols. To meet the requirements of mobile users under this heterogeneous environment, a common infrastructure to interconnect multiple access networks will be needed. In this chapter, the design issues of a number of mobility management schemes have been presented. Each of these schemes utilizes IP-based technologies to enable efficient roaming in heterogeneous network. Efficient handoff mechanisms are essential for ensuring seamless connectivity and uninterrupted service delivery. A number of handoff schemes in a heterogeneous networking environment are also presented in this chapter.Comment: 28 pages, 11 figure