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TDMA Slot Structure

Every TDMA frame has 8 slots (defined as SLOTS_PER_FRAME). Slot duration is set as 577 microseconds. We transmit 50 bytes ie one (simulated) RLC PDU, in each slot. This models the transmission of one GPRS Radio Block (RB) (of size  200 bytes) over four slots in consecutive frames. For packets smaller than the size of an RLC PDU (ex rlc_acks or ll_acks), the packet transmission time is taken as packet_size/transmission_rate.

We use Up_Slot_Gprs_Timer and Down_Slot_Gprs_Timer to signal the start and end of each slot on the uplink and downlink respectively, and the processing is handled by the upslotHandler() and downslotHandler() respectively.

The upslotHandler() checks whether any MS has a packet to transmit in the current upslot. If it does, the packet is passed onto tx_onto_PHY() that starts the `transmission' of the packet. Similarly the downslotHandler() checks at the BS.





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