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Um Interface andRadio Channels
7/30/2019 2G Um Interface and Radio Channels ISSUE2.1
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Contents
1. Overview
2. Processing of Voice Signal
3. Radio Channel
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Radio Interface
Another MSC
HLR/AUC
SMC
PSTN
ISDN
OMC
MS
Um
MS
A-bis
BSC
A
BTS
MSC/VLR
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Communication management (CM)
Radio resources management (RR)
Mobility and security management
(MM)
Integrated management
TCH0 TCH1 TCH2。。SACCH。。TCH23 IDL
Multiframe
Physical link layer (L1)
Data link layer (L2)
Network application layer (L3)
Hierarchical Structure of Um Interface
RACH BCCH AGCH/PCH SDCCH SACCH TCH FACCH
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Radio Access Technology
Power
Power
Power
FDMA
TDMA
CDMA
TimeFDMA
Frequency
TDMATime
Frequency
CDMA
Frequency
Time
Code
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Contents
1. Overview
2. Processing of Voice Signal
3. Radio Channel
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Voice Signal Processing
(A/D)
20 ms
22.8kbit/s
13kbit/s 8KHz,13bi
t
33.8kbit/s
Segmentation Speech coding Channel coding
Interleaving Encryption) Burst formatting Modulation
Transmission
Voice
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Analog-Digital Conversion
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Speech Coding
The Enhance Full Rate coding mode is called CELP (Code Excited Linear Predictive Coding )
The Full Rate coding mode is called RPE-LTP (Regular Pulse Excited-Long
Term Prediction).
The Half Rate coding mode is called VCELP (Vector-Sum Excited Linear
Prediction)
13kbit/s260 bits(FR)
112 bits(HR)
244 bits(EFR) 12.2kbit/s
5.6kbit/s
(A/D)
20 ms
8KHz,13bi
t
Segmentation Speech coding
Voice
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Channel Coding
13kbit/s260 bits(FR)
112 bits(HR)
244 bits(EFR) 12.2kbit/s
5.6kbit/s
(A/D)
20 ms
8KHz,13bit
Segmentation Speech coding
Voice
Channel coding
22.8kbit/s456bits(FR/EFR)
228bits(HR) 11.4kbit/s
BlockCoder
1:2
Convolutional
Coder
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1 2 3 4 5 6 7 8 ... ... 452 453 454 455 456
B
8
16.
.
.
456
2
10.
.
.
450
6
14.
.
.
454
1
9.
.
.
449
4
12.
.
.
452
7
15.
.
.
455
3
11.
.
.
451
5
13.
.
.
453
.... ....
B0 B1 B2 B3 B4 B5 B6 B7
{A4,B0} {A5,B1} {A6,B2} {A7,B3} {B4,C0} {B5,C1} {B6,C2} {B7,C3}
First interleaving:
Second interleaving:
Interleaving
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Voice Burst
Tailbit
Tailbit
Guard
periodData
Data Training sequence
57 encrypted bits 3
bits 8.25 bits 26 bits 1
3
bits57 encrypted bits 1
(A/D)
20 ms
22.8kbit/s
13kbit/
s 8KHz,13bit
33.8kbit/
s
Segmentation Speech coding Channel coding
Interleaving Encryption) Burst formatting Modulation
Transmission
Voice
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Voice Signal Processing
33.8 kbit/s
22.8 kbit/s 13 kbit/s
8 kHz
13 bits
Transmitting part Receiving part
Speaker
Receiver Demodulator
AdaptiveEqualization De-ciphering
De-interleaving Channel decoding Speech decoding D/A-conversion
Transmitter Modulator
Burst formatting Ciphering
Interleaving Channel coding Speech coding Segmentation
A/D-conversion Microphone
13 kbit/s
Transmitting part
Receiving part
Transmitter Modulator
Burst formatting Ciphering
Interleaving Channel coding D/D-conversion 8 kHz 8 bits 64 kbit/s PCM
Receiver Demodulator
AdaptiveEqualization De-ciphering
De-interleaving Channel Decoding
GSM Network Mobile equipment
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Transmission delay t
Transmission delay t
TA
The mobile phone should
send the signal in advance!!
Timing Advance (TA)
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Frequency Hopping
Frequency
f 0
Frame
f 1
f 2
f 3
f 4
Time
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Prolong battery life andreduce interference
DTX
DTX: Discontinuous Transmission
Shut off the transmission at voice intervals;
Only transmit SID frames’
The transcoder at the RX terminal produces comfortable noise.
VAD: Voice Activity Detection
Implemented by the transcoder.
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Power Control
Prolong battery life
Reduce network interference
Include both uplink power control and downlink power control
Level and quality are taken into account
BSC or BTS is the final adjudicator
BCCH Carrier is notinvolved in power control.
Time
Signal level
Target level value:e.g. -85 dm
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Contents
1. Overview
2. Processing of Voice Signal
3. Radio Channel
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Frequency
200kHz
15/26ms
BP
Slit
Time
Frame and Channel
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32107654321
Physical Channel of Logical Channel
0
different
message
types
Logical channel
Physical Channel
Logical channel
Logical channel
Logical channel
Logical channel
TDMA FRAME
200K
577 ms
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8bit 41 synchronous
bits
36 encrypted
bits3bit 68.25bit
Tail bit Tail bit Guard intervalData
Guard interval
3bit 142bit 3bit 8.25bit
Tail bit Tail bitData
3bit 39 encrypted
bits
39 encrypted
bits3bit 8.25bit
Tail bit Tail bit Guard intervalDataData
Burst
64 synchronous bits
• Access burst (AB): Used in MS initial access
• Frequency correction burst (FB): Used in frequency synchronizationbetween MS and BTS
• Synchronous burst (SB): Used in timing synchronization between
MS and BTS
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3bit 142 modulation bits 3bit 8.25bit
Tail bit Tail bit Guard interval
Burst
3bit57 encrypted bits
57 encrypted bits 3bit 8.25bit
Tail bit Tail bit Guard intervalDataData
26bit1 1
Training sequence
Frame stealing flag
Normal burst (NB)
Used to carry the information of the traffic channel and the control channel
except for RACH
Dummy burst (DB)
Used in transmission of filling frames by BTS at timeslots when there is noinformation delivered
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Broadcast control channel
(BCH)Control channelCommon control channel
(CCCH)
Voice channel
(TCH)
FCCH SCH BCCH TCH/FAGCH RACH SDCCH FACCH
SACCH
TCH/HPCH
Common channel
(CCH)
Dedicated channel
(DCH)
Logical channel
Logical Channel Type
GSM900 and DCS1800 have the same logical channel category
(system information)
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FCCH
SCH
BCCH
PCH
AGCH
BCCH
CCCH
Common
Channel
SDCCH
SACCH
FACCH
TCH/F
TCH/H
DCCH
TCH
Dedicated
Channel
Downlink Logical Channel
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Use of Logical Channels
FCCH
Allocate signaling channel
Power-on Search for frequency correction burst
Search for synchronous burst
Listen to the system information
Monitor paging message
Send access burst
Set up the call
Allocate voice channel
Conversation
Release the call
Idle mode
SCH
BCCH
PCH
RACH
AGCH
SDCCH
SDCCH
TCH
FACCH
Dedicated mode
Idle mode
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26-frame multi-frame
TCH/F+FACCH/F+SACCH/F (full-rate TCH)
TCH/H+FACCH/H+SACCH/H (half-rate TCH)
51-frames multi-frame
FCCH+SCH+BCCH+CCCH (main BCCH)
FCCH+SCH+BCCH+CCCH+SDCCH/4+SACCH/4 (combined BCCH)
BCCH+CCCH (extended BCCH)
SDCCH/8+SACCH/8 (main SDCCH)
Physical Combination of Logical Channel
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Structure of Main BCCH1 multi-frame (51TDMA Frames) 235.38ms Downlink
Group Group1 Group2
Group3,4
(same as
Group2)
Grpup5
Channel F S BX4 CX4 F S CX4 CX4 …… F S CX4 CX4 I
Frame
Number 0 1 2-5 6-9 10 11 12-15 16-19 20-39 40 41 42-45 46-49 50
1 multi-frame (51TDMA Frames) 235.38ms Uplink
Channel R R R R R R R R R R R R R R……R R R R R
Frame
Number 0 1 2 3 4 5 6 7 8 9 10 11 12 13-46 47 48 49 50
F:FCCH; S:SCH; B:BCCH; C:CCCH; R:RACH; I:IDLE
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Structure of Combined BCCH1 multi-frame (51TDMA Frames) 235.38ms Downlink
Group Group1 Group2 Group3 Group4 Grpup5
Channel F S
B
×4
C
×4
F S
C
×4
C
×4
F S
D0
×4
D1
×4
F S
D2
×4
D3
×4
F S
A0
×4
A1
×4
I
Channel F S
B
×4
C
×4
F S
C
×4
C
×4
F S
D0
×4
D1
×4
F S
D2
×4
D3
×4
F S
A2
×4
A3
×4
I
Frame
Number 0 1 2-5 6-9 10 11
12-
15
16-
1920 21
22-
25
26-
2930 31
32-
35
36-
3940 41
42-
45
46-
4950
1 multi-frame (51TDMA Frames) 235.38ms Uplink
Channel D3×4 R R A2×4 A3×4 R……R D0×4 D1×4 R R D2×4
Channel D0×4 R R A0×4 A1×4 R……R D0×4 D1×4 R R D2×4
Frame
Number 0-3 4 5 6-9 10-13 14-36 37-40 41-44 45 46 47-50
F:FCCH; S:SCH; B:BCCH; C:CCCH; D:SDCCH ;A:SACCH; R:RACH; I:IDLE
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Structure of Logical Channel
Combination Frame-Main SDCCH1 multi-frame (51TDMA Frames) 235.38ms Downlink
ChannelD0
×4
D1
×4
D2
×4
D3
×4
D4
×4
D5
×4
D6
×4
D7
×4
A0
×4
A1
×4
A2
×4
A3
×4I I I
ChannelD0
×4
D1
×4
D2
×4
D3
×4
D4
×4
D5
×4
D6
×4
D7
×4
A4
×4
A5
×4
A6
×4
A7
×4I I I
Frame
Number 0-3 4-7 8-11
12-
15
16-
19
20-
23
24-
27
28-
31
32-
35
36-
39
40-
43
44-
47 48 49 50
1 multi-frame (51TDMA Frames) 235.38ms Uplink
ChannelA5
×4
A6
×4
A7
×4I I I
D0
×4
D1
×4
D2
×4
D3
×4
D4
×4
D5
×4
D6
×4
D7
×4
A0
×4
Channel A1×4
A2×4
A3×4
I I I D0×4
D1×4
D2×4
D3×4
D4×4
D5×4
D6×4
D7×4
A4×4
Frame
Number 0-3 4-7 8-11 12 13 14
15-
18
19-
22
23-
26
27-
30
31-
34
35-
38
39-
42
43-
46
47-
50
D:SDCCH; A:SACCH; I:IDLE
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Structure of Logical Channel
Combination Frame-TCH
T:TCH;A:SACCH; I:IDLE
1 multi-frame (26TDMA Frames) 120ms
Channel T T T T T T T…T A T,,,T T T T T T T I
Frame
Number 0 1 2 3 4 5 6…11 12 13…18 19 20 21 22 23 24 25
1 multi-frame (26TDMA Frames) 120ms
Channel T t T t T t T…t A T,,,t T t T t T t a
Frame
Number 0 1 2 3 4 5 6…11 12 13…18 19 20 21 22 23 24 25
Case of one full rate TCH
Case of two half rate TCHs
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0 1 2 32044
2045 2046 2047
0 1 2 3 48 49 5047
0 1 24 25
0 1 24 25 1 49 500
0 1 4 5 762 3
TB
3
TB
3
GP
8.25TB: Tail bitTB
3TB3
GP8.25
GP: Guard periodTB3
TB3
GP8.25
TB3
TB3
GP 68.25
58 information bits26 training
sequences58 information bits
Constant bit 142
Information bit 39 Extended training sequence 64 Information bit 39
Synchronous sequence 41 Information bit 36
Normal burst (NB)
Frequency correction burst (FB) Synchronous burst (SB)
Access burst (AB)
1 hyper frame=2048 super-frames=2715648TDMA frames (3 hours, 28 minutes, 53 seconds and 760 milliseconds)
1 super-frame=1326TDMA frames (6.12 seconds)
1 multiframe=26TDMA frames (120ms) 1 multiframe=51TDMA frames (3060/13ms)
1TDMA frame=8 timeslots (120/26=4.615ms)
1 timeslot=156.25 bit duration (15/26=0.577ms)(1 bit duration: 48/13=3.68us)
BCCHCCCHSDCCH
TCHSACCH/TFACCH
Frame
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PCH RACHAGCH
Downlink CCCH Uplink CCCH
How to determine the total CCCH resources of the cell? How to
allocate AGCH and PCH reasonably?
Configuration of Common Control Channel
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Summary
In this course, we have learned:
Processing of Voice Signal
Radio Channel in Um Interface
Key Technical in Um Interface
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