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Mobility and Differentiated Services in a Future IP Network

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Closing the gaps in the mobile Internet

While mobile services try to provide constant connectivity, there are times, when switching from one network to another, when connections can be dropped. However temporary the network loss may be, it proves annoying for users, and threatens QoS standards. The EU-funded 'Moby Dick' project set out to build and evaluate a mobile network architecture based on the next-generation Internet protocol (IPv6) that addresses this problem.

Digital Economy

The developing standard for mobile IP-based networks, MIPv6, includes a procedure for the "handover" of connections from one access point to another. Since the current practice waits for a connection to break before it establishes a new one, (break before make), devices can remain unconnected for up to ten seconds. The project consortium developed a solution that establishes a new connection in the background before the current one is broken (make before break). Methods similar to this Fast Handover procedure have so far only been used in circuit-switched networks. One example is High Speed Circuit Switched Data (HSCSD), the original data transfer method for the GSM standard used in most mobile phones today. Its application to a packet-switched standard like MIPv6 creates a nearly seamless network, which will also reduce data loss to nearly zero. A user interface allows the user to register on a network and to define their preferences concerning which access technology to use and which strategy to follow for managing handovers. It even permits the user to trigger a handover manually if they want to choose a different network. It also provides information on conditions like signal levels on the network. The 802.11 standard for wireless LAN defines two working modes: infrastructure mode for networks with multiple access points, and ad-hoc mode for peer-to-peer communication between mobile devices. However, wireless LAN cards for portable computers currently do not support the fast discovery of new access points while connected in infrastructure mode. For testing purposes, therefore, these cards had to be used in ad-hoc mode, with modifications of the driver to simulate infrastructure mode. At a later date, vendors could be convinced by Fast Handover’s success to code fast discovery in infrastructure mode into the cards’ drivers.

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