User Manual

Demand Assignment
System Overview GSI 002
605-0000-450
Draft Issue 1.3dr Date 8/02/00
Page 4 of 16
high rate channels to be split into multiple lower rate channels. Downlink traffic is time
division multiplexed into radio channels of 160 kbit/s. On the uplink, overlay codes are
applied so that multiple lower rate traffic channels may be code division multiplexed
into a single 160 kbit/s radio channel.
The DA radio interface utilises protocols that allow efficient access to radio resources.
A Call Control Channel is reserved to manage a pool of typically up to 480 STs,
remaining channels will be dedicated for carrying traffic. When an ST is not being used
to make a call it will receive data from the Call Control Channel which is used to
broadcast management information, information on radio channel usage and incoming
call indications.
1.3. AS4000 DA Channel Structure
The AS4000-DA channel structure is flexible but comprises;
• At least one Link Acquisition Channel (LAC)
• At least one Call Control Channel (CCC)
• Typically one Priority Traffic Channels (PTC)
• 1 to 13 Traffic Channels (TC)
1.4. Services supported:
• Telephony, including the in-band support for G3 facsimile and data modems
operating at up to 56kbit/s.
• CLASS services as supported by the Local Switch.
• Leased Line data services supporting currently 2 x 64kbit/s per ST. Future
enhancement to 6 x 64kbit/s are planned.
• Basic Rate ISDN. All ISDN implementations fully support:
ETS 300 011 / 012
ETS 300 125 - Basic Call Layer 2 Data Link Layer I.440 & I.441 - Q.921
ETS 300 102 - Basic Call Layer 3 (Q.931)
Interfaces are generally defined by the ITU-T (CCITT) recommendations, I.420 (for
Basic Rate) and I.421 for Primary Rate.
Specification for Bearer Services is based on ITU-T recommendations I.230 and I.231.
Circuit Mode Bearer Service 64kbit/s unrestricted 8kHz structured (ETS 300 108)
Circuit Mode Bearer Service 64kbit/s 8kHz structured for 3.1kHz Audio (ETS 300
110)