Short Message Service
• Interpretation of SMS_BROADCAST_REQUEST messages
• Transmission of SMSCB messages
• Transmission of CBCH Fill-frame
Description
Configuration parameter CBCH Ind must be set to 1, to indicate the
usage of SDCCH sub-channel 2, for SMSCB messages.
Transmission of SMSCB messages on channel combination (vii)
requires that configuration parameter BS_AG_BLKS_RES is set to a
value greater than zero, /GSM:05.02:6.5.4/ /GSM:05.02:3.3.2.3/. The
function is initiated when the first (out of four)
SMS_BROADCAST_REQUEST message is received from the BSC.
Four SMS_BROADCAST_REQUEST messages together make a
complete SMSCB message. All four blocks must be available before
any transmission on the CBCH channel can take place.
Each SMS_BROADCAST_REQUEST message contains a complete
frame (including a Message type field = Layer 2 header) /GSM:04.12:3/
, to be transmitted on the CBCH channel.
The Message Type field contains a sequence number, used to check the
order of arrival. The correct order of arrival is defined as: 0,1,2,3.
The SMSCB messages are transmitted in four consecutive multiframes /
GSM:05.02:6.5.4/ during periods when TB = 0, 1, 2 and 3.
CBCH Fill-frames are transmitted on the CBCH channel when TB=0, 1,
2 and 3, and no SMSCB message is available for transmission. Nothing
is transmitted for TB = 4, 5, 6 and 7. TB = (FN DIV 51) MOD 8
(where FN = Frame Number).
A CBCH fill-frame consists of:
• 1 octet, Message Type /GSM:04.12:3.3.1/ with Sequence Number
= F (hex)
• 22 octets=2B (hex)
16.3 Operational Conditions
16.3.1 SMS MT/MO P-P
The maximum length of a message can be 140 octets or 160 SMS
characters.
16.3.2 SMS Cell Broadcast
The transmission time over the air interface for one SMSCB message (4
blocks, 23 octets each) is:
• 4 * 51 * 120/26 milliseconds = 0.941 seconds.
The maximum sending intensity is one message per 1.88 seconds (4
blocks of data and 4 empty frames).
RBS provides storage capacity for two complete SMSCB messages.
EN/LZT 123 2697 R5A
1998-08-13
119 (306)
© Ericsson Radio Systems AB
— All Rights Reserved —
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