User's Manual

User

AN-100U/UX Base Station

Manual

A wireless link is considered non LOS if natural or man-made structures block the visible

path between the base station and the subscriber. In this case, a wireless link can be

established only if a reflective path can be established between the base station and

subscriber.

Figure 6: System - Non-Line of Sight Deployment

2.7 Service Flows

Service flows are a key feature of the 802.16 standard. A service flow represents a

unidirectional data flow between the base station and subscriber. Downlink service flows

control traffic flow from the base station to the subscriber. Uplink service flows control

traffic flow from the subscriber to the base station. Bidirectional data flow requires that

two service flows be defined: one for the uplink, and another for the downlink. Each

service flow is assigned unique QoS settings.

The base station allows multiple service flows to be configured for each subscriber in a

sector. This allows service providers to offer different service levels and segregate traffic

flows having different QoS requirements.

A service flow is partially characterized by the following attributes:

1. A 32-bit Service Flow ID (SFID) is assigned to all existing service flows. The SFID

serves as the principal identifier for the Service Flow and has an associated

direction.

2. A 16-bit Connection ID (CID) is associated with each active SFID (connection

active).

3. A set of QoS parameters specifying the required resources. The principal resource

is bandwidth, but the specification may also include latency requirements.

4. A set of QoS parameters defining the level of service being provided.