Performance of UMTS/WLAN Integration at Hot-Spot Locations Using OPNET

Due to the many benefits provided by both the third-generation (3G) mobile networks and the IEEE 802.11 wireless local area networks (WLANs), it is desirable to integrate both types of networks. While studies specifying generic integration architectures are abundant, there are little or no studies that are dedicated for applications performance over such heterogeneous networks. Using simulations, this paper evaluates the performance of two 3G/WLAN integration schemes: loose and open coupling, together with two mobility management schemes: Mobile IP and mobile stream control transmission protocol (mSCTP) for an airport as a typical example of a hot-spot location. In addition, the evaluation is carried out for a wide range of application mixes consisting of FTP, HTTP and multimedia. Utilizing OPNET as the simulation platform and incorporating the required protocols to support our implementation of the Mobile IP and mSCTP, we generate a large matrix of performance figures for the 4 network configurations under all applications mixes considered. The results summarized in this paper indicate that integration methods considered have little impact on the application mixes studied in terms of delay but show that FTP and HTTP throughput is better with loose coupling scheme. Further, quantifying the handoff delay between the 3G and WLAN networks, the results indicate that a loose-couple integration solution together with Mobile IP provides the best performance

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

Disruption tolerance for SIP

The wireless networks have been built with versatile wireless network technology, including both wide area wireless networks and local area wireless networks. In such heterogeneous network environment, mobile users may experience either short or long interruption for different reasons while having a multimedia conversation. A lot of emphasis is concentrated on improving radio signal and enhancing seamless handover. However, recovery and backup multimedia conversation from a temporary network failure is also an interesting topic to be discussed. In this thesis, a SIP-based communication with enabling of disruption tolerance mechanism is introduced. We present the idea of media stream and SIP signaling based detection and recovery mechanisms, and come with an implementation of the prototype. The disruption tolerance functions include the ways of detecting network failure, storing the conversation during the meanwhile of the network disconnection, recover the previous broken multimedia session and replay the unheard voice. A brief experimental SIP network is built to evaluate the disruption tolerance functions of the software prototype. The result of the experimentation shows that the multimedia session can be recovered from the broken session in a short time, and the important conversation will not be lost during the short network disconnection. The replayed voice brings a delay to the recovered conversation which is not good experience for the users. However, the delayed conversation is much better than losing the conversation

Adaptive Vertical Handoff for Integrated UMTS and WLAN Networks

Next-generation wireless networks have been envisioned to be an integration of heterogeneous wireless access networks such as UMTS (Universal Mobile Telecommunication Networks) and the IEEE 802.11 based WLAN (Wireless Local Area Networks). It is an important and challenging issue to support seamless vertical handoff management in such an integrated architecture that provides the mobile users uninterrupted service continuity anywhere, any time. In such a networking environment, the signaling delay of the vertical handoff is not fixed due to the traffic load in the backbone Internet, wireless channel quality and the distance between a mobile node and its home network. However, the currently handoff solutions implicitly considers the signaling delay as a constant value. In this thesis, we study a typical link layer assisted handoff, identifying its deficiency due to the considerably large handoff delay. We propose an adaptive vertical handoff management scheme for integrated UMTS and WLAN networks. The proposed scheme incorporates the idea of pre-handoff with adaptive handoff threshold. We estimate the handoff signaling delay in advance, therefore, providing the delay information required for making an adaptive handoff decision. Instead of setting a fixed threshold, an adaptive handoff threshold value is determined for every single MN based on the estimated handoff signaling delay. The RSS and the RSS's rate of change are used to determine the estimated handoff time instant. Extensive simulation has been conducted to verify the performance of the proposed handoff scheme

Support infrastructures for multimedia services with guaranteed continuity and QoS

Advances in wireless networking and content delivery systems are enabling new challenging provisioning scenarios where a growing number of users access multimedia services, e.g., audio/video streaming, while moving among different points of attachment to the Internet, possibly with different connectivity technologies, e.g., Wi-Fi, Bluetooth, and cellular 3G. That calls for novel middlewares capable of dynamically personalizing service provisioning to the characteristics of client environments, in particular to discontinuities in wireless resource availability due to handoffs. This dissertation proposes a novel middleware solution, called MUM, that performs effective and context-aware handoff management to transparently avoid service interruptions during both horizontal and vertical handoffs. To achieve the goal, MUM exploits the full visibility of wireless connections available in client localities and their handoff implementations (handoff awareness), of service quality requirements and handoff-related quality degradations (QoS awareness), and of network topology and resources available in current/future localities (location awareness). The design and implementation of the all main MUM components along with extensive on the field trials of the realized middleware architecture confirmed the validity of the proposed full context-aware handoff management approach. In particular, the reported experimental results demonstrate that MUM can effectively maintain service continuity for a wide range of different multimedia services by exploiting handoff prediction mechanisms, adaptive buffering and pre-fetching techniques, and proactive re-addressing/re-binding