Sunday, November 29, 2009

Service Flows and Classes

WiMAX services are the providing of information transfer to or between users. Information transfer services can have a variety of characteristics that can be selected and varied by the operator. The WiMAX system uses services flows to identify specific transmission characteristics for specific user services and a single user may have multiple service flows. Common sets of service characteristics may be defined by service classes.

Service Flows

Service flows are communication channels (e.g. a stream of packets) that have particular service characteristics associated with the transfer of data. For example, a communication link might have several service flows associated with it; a real time service flow for voice communication, a high-integrity service flow (low error rate) for data file transfer and a best effort service flow for Internet web browsing.

Each service provided on a WiMAX system is associated with a service flow. Service flows are requested, established and ended. When subscriber stations request services, the system can evaluate and negotiate the requested characteristics at any time.

A single WiMAX subscriber station may have multiple service flows for each connection (service flows can be different in different directions). Service flows can be dynamically added, changed and ended.

Service flows are uniquely identified by a service flow identifier (SFID). A SFID is associated with a specific connection identifier to determine the service characteristics a specific user will receive on that particular device

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