Seamless roaming between UMTS and IEEE 802.11 networks

Mobile Internet access is currently available mainly using 2G/3G cellular telecommunication networks and wireless local area networks. WLANs are perceived as a local complement to slower, but widely available cellular networks, such as existing GSM/GPRS or future UMTS networks. To benefit from the advantages offered by both radio access networks, a mobile user should be able to seamlessly roam between them without the need to terminate already established Internet connections. The goal of this paper is to present an overview of the profitability of performing vertical handovers between UMTS and IEEE 802.11b using Mobile IP. Several simulations have been carried out using NS-2, which prove that handovers from IEEE 802.11b to UMTS can, under certain circumstances, be profitable not only when there is no more IEEE 802.11b coverage. Simulation results show that a mobile user should be able to roam between these networks depending on the current available channel bandwidth and quality, generated traffic type and number of users in both of them

A Network-Driven Multi-Access-Point Load-Balancing Algorithm for Large-Scale Public Hotspots

Part 1: Autonomic and Decentralized ManagementInternational audienceWireless networks are getting more and more popular and are a basic part of our life with the daily use of smartphones. Users expect high quality connectivity even in public spaces where a high number of clients connect to a limited spectrum on a geographically small area. Therefore, large-scale, high density wireless networks, like they are present at events, are getting more common, but provide a serious resource allocation challenge. Thousands of clients want to connect to a network consisting of multiple APs and a limited spectrum, while all of them should receive a decent connection quality, throughput and delay. Therefore, none of the APs should be overloaded, so that they can provide service for each connected client. The IEEE 802.11 standard stipulates that the client makes the decision to which AP to connect to. In high-density networks, the individual decision of the client can lead to an AP overload and oscillations in AP association as a client typically has limited information about the network performance and does not collaborate with other clients in taking its decision. This provides unwanted behaviour for load-balancing, as there is no control over the clients. Therefore, we present a method where the APs get control over the client and realise load balancing in such a network. The AP evaluates through a score if the client can connect and, if the client is connected, checks regularly if it is the best option for the client

Measurements of QoS/QoE Parameters for Media Streaming in a PMIPv6 Testbed with 802.11 b/g/n WLANs

The growing number of mobile devices and the increasing popularity of multimedia services result in a new challenge of providing mobility in access networks. The paper describes experimental research on media (audio and video) streaming in a mobile IEEE 802.11 b/g/n environment realizing network-based mobility. It is an approach to mobility that requires little or no modification of the mobile terminal. Assessment of relevant parameters has been conducted in an IPv6 testbed. During the tests, both Quality of Service (QoS) and Quality of Experience (QoE) parameters have been considered. Against the background of standard L3 and L2 handovers, an emerging mobility solution named Proxy Mobile IPv6 (PMIPv6) has been examined. Its advantages (L3 connectivity maintenance) and disadvantages (packet loss during handover) are emphasized based on the obtained results. Moreover, a new solution for handover optimization has been proposed. A handoff influence upon audio/video generation and transfer imperfections has been studied and found to be an interesting direction of future work