Reference Manual

Speech and Data Services
18.3 Functions
18.3.1 Idle Transmission over A-bis
Idle transmission over A-bis is initiated:
• When the Managed Object (MO) corresponding to an air timeslot
resource receives a start order via A-bis Operation and
Maintenance Link (OML)
• When a TCH ceases to exist because of a disable order to the MO
corresponding to an air timeslot resource, via A-bis OML
Idle transmission over A-bis is active for the following channels and
conditions:
•
Common Resource channels, idle transmission always active
•
SDCCH channels, idle transmission always active
•
TCH channels, idle transmission active when there is no channel.
A 16 kbit/s idle pattern, as specified in /GSM:08.54/, is continuously
sent to the RTC on the terrestrial traffic channel allocated to the air
timeslot resource.
Idle transmission over A-bis is terminated when a traffic channel is
enabled on the air timeslot resource.
18.3.2 Terrestrial Link Supervision
The function Terrestrial Link Supervision (TLS) supervises a terrestrial
link (16 kbps) for a traffic channel and decides when a connection is
considered lost.
The TLS function is set to On or Off for an idle or active subchannel.
TLS on idle subchannel is set On:
•
16 kbps resource in IDLE state:
Idle speech is transmitted.
Terrestrial link supervision is active.
•
8 kbps resource in IDLE state (this case only exists when the
other 8 kbps resource is in ACTIVE state):
Idle pattern is transmitted.
Terrestrial link supervision is not active.
TLS on idle subchannel is set Off:
For all these cases terrestrial link supervision is not active.
• 16 kbps resource in IDLE state:
Idle pattern is transmitted.
• 8 kbps resource in IDLE state (this case only exists when the
other 8 kbps resource is in ACTIVE state)
180 (421)
EN/LZT 720 0008 R1A
2001-06-26
© Ericsson Radio Systems AB
— All Rights Reserved —