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Resource Reply

The BS allots a channel (slot-frequency) to an MS either on the receipt of a resource_request from the MS or on the receipt of a packet from its own IFQ for the MS (slot allocation is described in the next section). Information about the slot-frequency channel is written onto the MAC header of the resource_reply packet and it is transmitted on slot 0 of downlink frequency 0, to the appropriate MS.

On receipt of a resource_reply, an MS checks the slot-frequency channel alloted to it and stores it in tx_chan[] and rx_chan[] for future reference. It then kills the wait timer; schedules the old buffered packet to be transmited on the appropriate slot-frequency and unblocks the IFQ. Other waiting packets can now be passed down from the IFQ to the MAC and transmitted.

In case the BS has a second resource_reply message to be transmitted in slot 0 of the upcoming frame (this situation can arise when the BS receives a resource_request (from an MS) and a packet destined to a new MS (from its IFQ) in the same TDMA frame), the second reply is stored in a temporary buffer and transmitted on the next free downlink slot0.



Richa Jain (96D07007)
Tue Jul 24 22:29:53 IST 2001