Reference Manual

Call Control
26.9 Link Establishment Request
Purpose
To establish a signal link between MS and network.
Precondition and Initiation
Channel combinations supported are defined in section Channel
Activation above.
This function is applicable for:
•
SAPI-3 links on SDCCH, SACCH/T and SACCH/M
The function is initiated when the RBS receives an ESTablish REQuest
from BSC.
Description
The following procedure is used by BSC to request the establishment of
a link layer connection in multiframe mode on the air interface /
GSM 08.58:3.2/.
The procedure starts when the RBS receives an ESTablish REQuest
message from BSC. RBS then establishes the link by sending an SABM
frame. Upon reception of the acknowledgment (UA-frame) from MS,
RBS sends an ESTablish CONFirm message to BSC. It is the network
(BSC) that takes initiative for the establishment. Measurement reports
are one type of message which can be sent on the signal link.
P003018A
RBS
BSC
EST CONF
MS
SABM
UA
EST REQ
Figure 128 Link establishment request
Messages queued for transmissions are lost if the link is re-established.
When the link is established, an ESTablish CONFirm /GSM 08.58:3.5/
is to be sent to the BSC.
• The Link Establishment procedure is in accordance with /
GSM 08.58:3.2/ and /GSM 04.06:4.1/.
• Fault Handling related to the link establishment procedure is in
accordance with /GSM 04.06:5.4.1/.
26.10 Link Release Request
Purpose
To release a signal link between MS and network.
EN/LZT 720 0008 P2A
2001-11-28
263 (485)
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