Discontinuous Transmission
DTX handling non-transparent data
To detect idle data transmission in the downlink direction, the E1-bits
of a complete RLP frame received from the RTC, are analysed /
GSM:08.20:4.2/. This frame is not transmitted on the air interface.
When idle data transmission is detected, an L2 (Layer 2 protocol) fill
frame /GSM:04.06:5.4.2.3/ is transmitted (on FACCH) in the SID
positions of the TDMA frame according to /GSM:05:08:8:3/.
The output power is turned off during periods of idle data transmission,
as described in the section DTX handling speech above.
11.2.2 DTX Uplink
The uplink DTX function is supported for Channel Modes:
• TCH speech, full rate
• TCH speech, half rate.
The RBS is always prepared to handle uplink DTX. Channel
combinations supported are the same as for DTX downlink, see section
DTX Downlink above.
The uplink DTX function for speech is initiated when a frame
containing comfort noise parameters, is received from the MS.
To detect if a speech frame (received from MS) contains speech or
comfort noise parameters, the RBS analyses the SID code word /
GSM:06.12:2.2/ or /GSM:06.22:2.2/. An indication of comfort noise
parameters, is sent in the speech frames to the RTC.
During periods of silence in speech (no frames received from MS), idle
speech frames with a silence indication are transmitted to the RTC.
If half rate is used, speech frames with a bad frame indication are
transmitted to the RTC.
Data frames (transparent and non-transparent) are passed transparently
from the MS to the RTC without consideration of DTX.
EN/LZT 123 2697 R5A
1998-08-13
107 (306)
© Ericsson Radio Systems AB
— All Rights Reserved —
To Next Page
Loading...
