Timeslots on the Ater Interface

This describes the timeslot assignment on the OMLs and signaling links on the Ater interface.

OM Timeslots and Signaling Timeslots on the Ater Interface

When the BM and the TC are configured in different subracks, you need to configure the data related to the Ater interface.

When the GTCS is configured on the BSC side, the timeslots and bandwidth occupied by the SS7 signaling on the Ater interface are the same as those occupied by the SS7 signaling on the A interface

When the GTCS is configured on the MSC side, the Ater OMLs, the Ater signaling links, and the transparently transmitted SS7 occupy the Ater interface timeslots. The SS7 signaling on the Ater interface occupies the same bandwidth of timeslots as that on the A interface. The bandwidth of the interface timeslots occupied by the Ater OMLs and Ater signaling links is subject to the BSC configuration, as shown in Table 1.

**Table 1** Bandwidth of OM timeslots and signaling timeslots on the Ater interface
BSC Configuration	Bandwidth of Ater OMLs	Bandwidth of Ater Signaling Links
GMPS + GTCS	16 timeslots of 64 kbit/s	The GMPS is configured with four timeslots of 64 kbit/s.
GMPS + GEPS + 2 GTCSs	16 timeslots of 64 kbit/s	Each BM subrack is configured with four timeslots of 64 kbit/s
GMPS + 2 GEPSs + 3 GTCSs	31 timeslots of 64 kbit/s	Each BM subrack is configured with four timeslots of 64 kbit/s.
GMPS + 3 GEPSs + 4 GTCSs	31 timeslots of 64 kbit/s	Each BM subrack is configured with four timeslots of 64 kbit/s
GMPS + GEPS + GTCS	16 timeslots of 64 kbit/s	Each BM subrack is configured with four timeslots of 64 kbit/s
GMPS + 3 GEPS + 2 GTCS	31 timeslots of 64 kbit/s	Each BM subrack is configured with eight timeslots of 64 kbit/s

NOTE:

The GMPS and the GEPS are collectively known as the BM subrack.

Traffic Timeslots on the Ater Interface

The traffic timeslots on the Ater interface are assigned dynamically.

Except for the timeslots occupied by the Ater OMLs and Ater signaling links, all the other timeslots on the Ater interface are traffic timeslots that form a resource pool. The units of the resource pool are 16 kbit/s sub-timeslots. All the idle sub-timeslots form a FIFO queue. If required, the sub-timeslots will be taken out of the queue.

For example, to establish a call, the GEIUT in the GTCS selects a 16 kbit/s sub-timeslot (head element of the FIFO queue) that is idle for the longest time from the resource pool and takes it as the Ater path for the call. When the call is terminated, the sub-timeslot is released to the resource pool and used as the tail of the FIFO queue.