1. Chapter 10
(E)GPRS protocols
10.1 GPRS Protocols
1. The RLC/MAC protocol
2. The Medium Access control (MAC) header DL
3. The GPRS Medium Access Control header UL
4. DL + UL control blocks
5. Control Messages
6. DL control header
7. GPRS Downlink RLC/MAC data block
8. DL RLC header
9. GPRS Uplink RLC/MAC data block
10. UL RLC header
10.2 Coding Schemes and Link Adaptation
1. GPRS Channel Coding
2. Differentiation of the Coding Schemes
3. GPRS Link Adaptation
4. Link Adaptation Algorithm
2. Chapter 10
(E)GPRS Protocols
10.3 Enhancements of EDGE versus GPRS
1. Enhancements of EDGE versus GPRS
2. 8PSK
3. 8-PSK phase transitions
4. Burst types
5. Detailed 8-PSK
6. GPRS and EDGE TS sharing
10.4 Protocol structures
1. EGPRS Channel Coding
2. EGPRS MCS Families
3. The padding option
4. Combined RLC/MAC Header for EDGE user data
5. Differences in the Headertypes
6. MAC part of combined RLC/MAC header
7. Other new fields in the RLC/MAC header
8. The RLC part of combined RLC/MAC Header
9. Channel coding in EGPRS
10. Coding and Interleaving
11. Coding Process Example: MCS-2 DL
12. Coding Process Example: MCS-8 DL
13. EGPRS Coding Parameters
14. EDGE coding compared with GPRS
10.5 RLC MAC enhancements
1. EDGE specific RLC/MAC modifications
2. Network access mechanism
3. EGPRS Packet Channel Request
4. other new RLC/MAC messages for EGPRS
3. The RLC/MAC protocol
Radio Link Control (RLC) and Medium Access Control (MAC) realize OSI layer 2 functions.
Both, RLC and MAC are described in GSM 04.60 (44.060).
The main functions of RLC are:
-The segmentation of LLC frames
-The provision of an acknowledged and unacknowledged operation mode
The main functions of MAC are:
-The control of the access to the network resources:
-The sharing of the network resources to several mobiles:
RLC
For the DL: Usage of the TFI
For the UL: Usage of the USF (and TFI)
-The control of the release of the network resources
MAC
-Release of Uplink TBF: Countdown Procedure
-Release of Downlink TBF: Final Block Indicator
Both, for data transfer and transfer of control messages different RLC/MAC blocks are
specified in UL and DL direction.
That means, that in total 4 different types of RLC/MAC blocks are used in GPRS:
-DL RLC/MAC control blocks (used for GPRS and E-GPRS)
-UL RLC/MAC control blocks (used for GPRS and E-GPRS)
-GPRS DL RLC/MAC data blocks
-GPRS UL RLC/MAC data blocks
4. Radio Block Structures
Radio Block for data transfer Radio blocks for data transfer may be encoded using CS-1 to CS-4.
MAC Header RLC Header RLC Data BCS
8 bits octets of one or several LLC PDUs
A GPRS radio block for data transmission holds following fields:
• MAC header; 8 bits, different content in UL and DL
• RLC header; This is a variable length field holding control data.
• RLC data; This field contains octets from one or several LLC PDUs.
• BCS field; Block Check Sequence is used for error detection.
Radio Block for control message
For Radio blocks carrying RLC/MAC control messages CS-1 has to be used
MAC Header RLC/MAC Control Message BCS
The GPRS radio block for control messages holds an 8 bit long MAC header, one RLC/MAC control
message in the RLC/MAC Control Message field, and a BCS field for error detection
5. The Medium Access control (MAC) header DL
8 7 6 5 4 3 2 1 Bit-No
USF
MAC Header In DL Payload Type RRBP S/P USF MAC header
USF The Uplink State Flag (USF) field is sent in all downlink RLC/MAC blocks and indicates who
is allowedto send in the next uplink radio block on the same timeslot (see
3GPP TS 45.002).
The USF field is three bits in length and eight different USF values can be assigned, except on PCCCH, where the
value '111' (USF=FREE) indicates that the corresponding uplink radio block contains PRACH.
S/P 0 RRBP field is not valid The Relative Reserved Block Period (RRBP)
1 RRBP field is valid field specifies a single uplink block in which the
RRBP mobile station shall transmit either a PACKET
00 (N+13) mod 2715648 CONTROL ACKNOWLEDGEMENT message or a
01 (N+17 or N+18) mod 2715648 PACCH block to the network
Supplementary/Polling (S/P) Bit is used to
10 (N+21 or N+22) mod 2715648 indicate whether the RRBP field is valid or not
11 (N+26) mod 2715648 valid
Payload Type 00 RLC/MAC block contains an RLC data block
01 RLC/MAC block contains an RLC/MAC control block that does not include the optional
octets of the RLC/MAC control header
10 In the downlink direction, the RLC/MAC block contains an RLC/MAC control block that
includes the optional first octet of the RLC/MAC control header.
11 Reserved. In this version of the protocol, the mobile station shall ignore all fields of the
RLC/MAC block except for the USF field
6. The GPRS Medium Access Control header UL
8 7 6 5 4 3 2 1 Bit-No
MAC Header In UL
Payload Type spare R UL MAC header for control
Payload Type Countdown Value SI R UL MAC header for data
The Retry (R) bit shall indicate whether the mobile station transmitted the CHANNEL REQUEST
R
message (see 3GPP TS 44.018), PACKET CHANNEL REQUEST message, or EGPRS PACKET
CHANNEL REQUEST message one time or more than one time during its most recent channel
access
spare
Set to zero - bits are ignored
Payload Type 00 RLC/MAC block contains an RLC data block
01 RLC/MAC block contains an RLC/MAC control block
10 Reserved.
11 Reserved.
SI The Stall indicator (SI) bit indicates whether the mobile's RLC transmit window can advance (i.e.is not
stalled) or can not advance (i.e. is stalled). The mobile station shall set the SI bit in all uplink RLC data
blocks.
Countdown Value The Countdown Value (CV) field is sent by the mobile station to allow the network
to calculate the number of RLC data blocks remaining for the current uplink RLC
entity. The CV field is 4 bits in length and is encoded as a binary number with range 0 to 15
7. DL + UL control blocks
DL control block
8 7 6 5 4 3 2 1 Bit-No
Payload Type RRBP S/P USF MAC header
RBSN RTI FS AC octet 1 optional Control
PR TFI D
octet 2 octets header
octet M
Control Message Contents RLC/MAC
signaling
octet 21
octet 22
UL control block
Payload Type spare R
For the UL control block no optional control header is
preseen
Control Message Contents
8. Control Messages (Rel 97/98) I
Control Message Contents
(the basic set)
Uplink TBF establishment messages: Packet Access Reject
Packet Channel Request
Packet Queuing Notification
Packet Resource Request
Packet Uplink Assignment
Downlink TBF establishment messages: Packet Downlink Assignment
TBF release messages: Packet TBF Release
Paging messages: Packet Paging Request
RLC messages: Packet Downlink Ack/Nack
Packet Uplink Ack/Nack
System information messages: Packet System Information Type 1
Packet System Information Type 2
Packet System Information Type 3
Packet System Information Type 3 bis
Packet System Information Type 4
Packet System Information Type 5
Packet System Information Type 13
9. Control Messages (Rel 97/98) II
Packet Control Acknowledgement
Packet Cell Change Failure
Packet Cell Change Order
Packet Downlink Dummy Control Block
Packet Uplink Dummy Control Block
Packet Measurement Report
Packet Measurement Order
Miscellaneous messages: Packet Mobile TBF Status
Packet PDCH Release
Packet Polling Request
Packet Power Control/Timing Advance
Packet PRACH Parameters
Packet PSI Status
Packet Timeslot Reconfigure
Downlink RLC/MAC control messages and Uplink RLC/MAC control messages, except those using the access
burst formats, are received in the RLC/MAC control block format. The different types of messages are
distinguished by the MESSAGE_TYPE field
10. DL control header
RBSN RTI FS AC octet 1 optional Control
PR TFI D
octet 2 octets header
AC
The Address Control (AC) bit is used to indicate the presence of the optional TFI/D octet in the header of
downlink RLC/MAC control block.
FS
The Final Segment (FS) bit indicates that the downlink RLC/MAC control block contains the final segment
of an RLC/MAC control message .
RTI
The Radio Transaction Identifier (RTI) field is used to group the downlink
RLC/MAC control blocks that make up an RLC/MAC control message and identifies the segmented control message
sequence with which the downlink RLC/MAC control block is associated. The RTI field is five bits in length with range
0 to 31.
RBSN The Reduced Block Sequence Number (RBSN) bit carries the sequence number of the downlink
RLC/MAC control blocks. The RBSN bit is encoded as a binary number with range 0 to 1.
D The Direction (D) bit indicates the direction of the TBF identified by the TFI field in the downlink RLC/MAC
control block header.(0-UL, 1-DL).
TFI
In downlink RLC/MAC control blocks, the TFI identifies the Temporary Block Flow
(TBF) to which the RLC/MAC control message contained in the downlink RLC/MAC control block relates.
PR The Power Reduction (PR) field indicates the power level reduction of the current RLC block.
(important for DL PC).
11. GPRS Downlink RLC/MAC data block
8 7 6 5 4 3 2 1 Bit-No
Payload Type RRBP S/P USF MAC
header
PR TFI FBI octet 1
BSN E
octet 2
Length Indicator M E octet 3
RLC
optional header
octets
Length Indicator M E
octet M
octet M+1
RLC
RLC data
data
unit
octet N-1
octet N
Spare bits Spare bits (if present)
Optional octets: one octet may be present for each LLC (or part of LLC) contained. Length indicator
indicates the length of the LLC in octetts. Only the last segment of any Upper Layer PDU of a TBF
(either this segment carries the entire Upper Layer PDU or not) shall be identified with a Length
Indicator within the corresponding RLC data block.
12. DL RLC header
PR TFI FBI octet 1
BSN E of RLC header
octet 2
FBI The Final block indicator (FBI) bit indicates that the downlink RLC data block is the last RLC data block of
the downlink TBF. (0 - not the last block, 1 – the last block)
TFI
In RLC data blocks, the TFI (Temporary Floww Identity) identifies the Temporary
Block Flow (TBF) to which the RLC data block belongs. For the downlink and the uplink TFI the TFI field is 5 bits in
length.
PR The Power Reduction (PR) field indicates the power level reduction of the current RLC block.
(important for DL PC).
E The Extension (E) bit is used to indicate the presence of an optional octet in the RLC data block
header.
M E bit in optional part Length Indicator M E Optional octets
0 0 if received by the mobile station it shall ignore all fields of the RLC/MAC block except for the fields of the
MAC header
0 1 no LLC data after the current LLC PDU, no more extension octets
1 0 a new LLC PDU starts after the current LLC PDU and there is another extension octet, which delimits the
new LLC PDU
1 1 a new LLC PDU starts after the current LLC PDU and continues until the end of the RLC information field,
no more extension octets
BSN The Block Sequence Number (BSN) field carries the sequence
absolute Block Sequence Number (BSN') modulo Sequence Number
Space (SNS) of each RLC data block within the TBF. In GPRS, the BSN is 7 bits in length and is encoded as a
binary number with range 0 to 127.
13. DL RLC header II
Optional octets Length Indicator M E
LLC 1 and 2 completely contained, LLC 3 starts, continues in next RLC Data block:
LLC 3 LLC 2 Y octets LLC 1 X octets Y 1 1 X 1 0 E=0 in RLC header MAC
Start of LLC 3 1 optional octet 1 optional octet
LLC 1 continued from previous block and LLC fits2 precisely into the RLC:
LLC 2 Y octets LLC 1 X octets Y 0 1 X 1 0 E=0 in RLC header MAC
Rest of LLC 1 1 optional octet 1 optional octet
LLC 1 continued from previous block and continues in next block, no optional octet needed:
X octets of LLC1 E=1 in RLC header MAC
Part of LLC 1 that started in a former RLC and continuous in next
Next radio LLC 2 Y octets Y octets of LLC1 Y 1 0 E=0 in RLC header MAC
block
Part of LLC 2 Rest of LLC 1 1 optional octet
Optional octets are always present, if there is a LLC border, inside the RLC, exceptions are defined for last blocks.
14. GPRS Uplink RLC/MAC data block
8 7 6 5 4 3 2 1 Bit-No
Payload Type Countdown Value SI R MAC
header
spare PI TFI TI octet 1
BSN E octet 2
Length Indicator M E octet 3
.
.
.
RLC
Length Indicator M E octet M header
Optional
octet M+1 octets
TLLI
octet M+4
PFI E
octet M+5
RLC data octet N-1 RLC
octet N data
Spare bits Spare bits (if present) unit
15. UL RLC header
spare PI TFI TI octet 1
BSN E of RLC header
octet 2
TI The TLLI Indicator (PI) bit indicates the presence of an optional PFI field within the RLC data block.
0- field not present
1- field present
TheTLLI field is present during one phase access in all UL datablocks until the
TLLI
first Acknowledgement is received in DL (Contention resolution procedure).
TFI Used as in DL.
PI The PFI Indicator (TI) bit indicates the presence of an optional PFI field within the RLC data block.
0- field not present PFI (Packet Flow Indication)
1- field present
If the network indicates that it supports packet flow procedures (Network support of packet flow
context (PFC) procedures is indicated by the PFC_FEATURE_MODE parameter that is broadcast on
either the BCCH or PBCCH) and a PFC exists for the LLC data to be transferred the packet flow
identifier has to be present
spare E
Remaining fields are used as in DL. Length Indicator M E
BSN
16. PFI field
PFI, if the network indicates that it supports packet flow procedures (Network support of packet flow context
(PFC) procedures is indicated by the PFC_FEATURE_MODE parameter that is broadcast on either the BCCH or
PBCCH) and a PFC exists for the LLC data to be transferred. PFI, if the network indicates that it supports packet
flow procedures (If the network indicates it supports multiple TBF (Rel 6) procedures then it shall also indicate
support for PFC procedures ) and a PFC exists for the LLC data to be transferred. In case no valid PFI value is
allocated for the LLC data to be transmitted, and the network indicates support for the PFC procedures, an MS
supporting PFC procedures shall associate and indicate the following PFI values for the LLC data:
PFI = 0 (Best Effort) for user data,
PFI = 1 (Signalling) for GMM/SM signalling (LLC SAPI 1), or
PFI = 2 (SMS) for Short Message Service (LLC SAPI 7), or
PFI = 3 (TOM8) for LLC SAPI 8 data.
BSS packet flow contexts describe QoS characteristics for the data transmission.
BSS
Um
SGSN
Buffer 1
PFC
1
TBF BSS
Context
Buffer 2
PFC
2
Gb
17. Chapter 10.2
The Air Interface
10.2 Coding Schemes and Link Adaptation
1. GPRS Channel Coding
2. Differentiation of the Coding Schemes
3. GPRS Link Adaptation
4. Link Adaptation Algorithm
18. GPRS Channel Coding
Channel coding for Radio Block
CS-1, CS-2, CS-3 USF BCS
convolutionary coding: rate 1/2
Puncturing for CS 2 and 3
Coding Parameters Radio Blocks for
code USF BCS radio block excl. coded punctured data rate control messages
rate bits bits USF and BCS bits bits kbps
CS-1 1/2 3 40 181 456 0 9.05 CS-1
CS-2 ≈2/3 3 16 268 588 132 13.4 data transfer
CS-3 ≈3/4 3 16 312 676 220 15.6 CS-1 CS-2
CS-4 1 3 16 428 456 - 21.4 CS-4 CS-3
19. Differentiation of the Coding Schemes
Encoded and punctured bits (456)
USF Header + Data + BCS
The Radio block is now interleaved onto 4 normal bursts in the same way as for SACCH
The 11 11 00 00
Stealing
bits in 11 00 10 01
the
normal
11 10 00 01
bursts
indicate
the CS. 11 00 01 10
CS 1 CS 2 CS 3 CS 4
In GPRS existing coding techniques are used. In DL blocks the USF is treated separately (stronger
encoded) but the same type of encoding is used in UL and DL (That means the first 3 bits of the
UL Mac header are unnecessarily strong protected. CS 1 is the same as that used for SACCH
coding (1/2 rate encoding). CS 2 and 3 is a punctured version (some doubled bits are deleted,
more for CS 3). CS 4 has no redundancy. The used CS is indicated by the Stealing Bits. This
allows blind detection. GPRS MS have to support all CSs, the network may support only a subset.
21. Link Adaptation Algorithm
The coding scheme will change based on defined
BLER Thresholds
The BLER thresholds are a result of simulations
CS1
Different thresholds for hopping and non hopping
CS2
networks CS3
Net Throughput (kbit/s)
14 CS4
The PCU defines which CS to use in UL and DL
Example !!!!! 12
Max CS 2: 12 Kbit/s (no header)
From CS1 to CS2 10 CS1 & CS2
Retransmissionrate Crosspoint
5.2Kbit/s 8
CS1 FH 14%
CS1 NFH 69% 6
Crosspoint FH 4
From CS2 to CS1 6.8 Kbit/s
2
CS2 FH 43% =(5.2/12) x 100 % 0
CS2 NFH 79% 9 18 8 7 6 5
Carrier / Interference C/I (dB)
22. LA operation
MS BTS BSC
UL – LLC data in MS
CHNREQ (Uplink TBF)
CHNRD (UplinkTBF)
RACH
IACMD (IMASS)
Packet UL Ass.: TFI; USF; CS
I (IMASS)
IACMD (IMASS) Packet UL Ass.: TFI; USF; CS
Initial CS is told to MS
AGCH
PCU - DL (PDDCB) USF
RMAC- DL (PDDCB)USF
( ... )
PDTCH ( ... )
RMAC- UL (PUDCB)
PCU - UL (PUDCB)
PDTCH
RMAC- UL (DATA) TLLI; BSN=0; CV=15
PCU - UL (DATA) TLLI; BSN=0; CV=15
PDTCH
( ... ) ( ... )
RMAC- UL (DATA) TLLI; BSN=x; CV=15
PCU - UL (DATA) TLLI; BSN=x; CV=15
PDTCH
PCU - DL (PUAN) TLLI:Cont.R.; Ack BSN=0; USF PCU may command
RMAC- DL (PUAN) TLLI: Cont. R.; ...
PACCH a new CS
RMAC- UL (DATA) TLLI; BSN=x+1; CV=15
PCU - UL (DATA) TLLI; BSN=x+1; CV=15
PDTCH
PDDCB Packet Downlink... )
( Dummy Control Block ( ... )
PUDCB Packet Uplink Dummy Control Block
PUAN Packet Uplink Ack/Nack
PDAN Packet Downlink Ack/Nack
Cont R contention Resolution
24. EGPRS enhancements
EGPRS is mainly an BSS internal enhancement of existing GPRS protocols.
-modified RLC/MAC protocol
RLC RLC -Option to use 8PSK on the air
-Requires the support of MS
MAC MAC
-Requires new transport solution on Abis
GSM RF GSM RF
MS Um BSS
RLC RLC
New control messages
New data block formats
MAC MAC
PCU Dynamic Abis PCU Frames
GSM RF Option to GSM RF Frames
use 8PSK PCM PCM
MS Um BTS Abis PCU
25. 8PSK
GSM RF enhancement The assignment of the different symbols to the
coordinates in the I/Q diagram seems to be
Q random. But it follows a GRAY code. If a
(0,1,0) symbol is falsely interpreted as one of its
neighbours, only one bit is wrong.
(0,0,0) (0,1,1)
Q0
(0,0,1) (1,1,1)
I1
,1)
,1)
(1,1
(0,1
(0,1,0)
I (0,0,0) (0,1,1)
,0)
,0)
1
Q
(0,1
(1,1
(1,0,1) (1,1,0)
(1,0,0) (0,0,1) (1,1,1) I
0
,0)
(1,0
With every symbol duration
,0)
(0,0
(which is equal to the bit duration (1,1,0)
(1,0,1)
in standard GSM, 3.7 µs), it rotates by 3p/8
,1)
,1)
(1,0,0)
(0,0
(1,0
corresponding to 67.5° to avoid zero crossings.
• 3Π/8-8-PSK which is used for EDGE
26. 8-PSK phase transitions
Q0
Minimum Amplitude -15 dB
‚usefull‘ Amplitude 0 dB
I0
maximum Amplitude +4 dB
Possible phase transitions in I-Q-diagram
(for EDGE several successive symbols
define the phase transitions)
27. Burst types
• Frequency Correction Burst,
• Synchronisation Burst,
Normal Burst: • Access Burst,
• Dummy Burst GMSK
training only
tail sequence tail
bits bits bits
000 58 encrypted bits 26 58 encrypted bits 000 8.25
½ bit ½ bit
active part
useful part
½ symbol ½ symbol
0 ... 0 174 encrypted bits 78 174 encrypted bits 0 ... 0 24.75
tail training tail
bits sequence bits
bits
1 Timeslot = 0.577 msec
8PSK burst may be used in UL and Downlink for the transfer of user data. The lower
shows the 8PSK burst where 1 Symbol=3bits. So it carries 3 times more bits as the
GMSK burst.
28. Detailed 8-PSK burst
3 Tail Symbols 1 Symbol Stealing Flag
Power/dB
1.5
0
-10
-20
-30
-40
-50
26 Training sequence Time
Guard period Symbols/8PSK but not
8.25 Symbols for reduced subset
Ramping
57 Payload Symbols/8-PSK
The payload is 116*3 = 348 bits (minus stealing symbols). Tail bits and training sequence
are also 8PSK modulated, however, they take only advantage of a subset of 8PSK
symbols, which reduces the dynamic range enormously. The training sequence in the
mid-amble consists of 26 symbols.
29. GPRS and EDGE TS sharing
1 radio block (20 msec)
For synchronisation reasons every MS with an active TBF
on that TS has to get a readable block in DL every 360 ms.
It is possible to send an USF to a GPRS This means if there was no CS 1-4 block in DL, and there is
√ √
MS in a EDGE Radio block. a GPRS MS in UL, the network has to schedule a control
GMSK has to be used (MCS 1-4) block every 18 th block (propably this will be dummy block).
CS 1
EDGE GPRS EDGE GPRS Control
DL
block
UL Time
GPRS EDGE EDGE GPRS
+GPRS
√ √
It is possible to send an USF to an EDGE and GPRS users can share a TS. 8-
EDGE MS in a GPRS Radio block. PSK is allowed in DL (if no GPRS user shall
The EDGE user can use any MCS send in the next UL block) and UL
Timeslot sharing is possible. The potential throughput for the EDGE user will be degraded. As a consequence
there is the possibility to have separate EDGE and non EDGE resources in one cell or one may enable EDGE in
one cell and disable EDGE in the neighbour (with advanced features it is possible to move EDGE MSs to EDGE
cells and GPRS MSs to GPRS cells). Additionally the PCU (being responsible for resource allocation) tries to avoid
these situations.
30. Chapter 10
EGPRS Protocols
10.4 Protocol structures
1. EGPRS Channel Coding
2. EGPRS MCS Families
3. The padding option
4. Combined RLC/MAC Header for EDGE user data
5. Differences in the Headertypes
6. MAC part of combined RLC/MAC header
7. Other new fields in the RLC/MAC header
8. The RLC part of combined RLC/MAC Header
9. Channel coding in EGPRS
10. Coding and Interleaving
11. Coding Process Example: MCS-2 DL
12. Coding Process Example: MCS-8 DL
13. EGPRS Coding Parameters
14. EDGE coding compared with GPRS
31. EGPRS Channel Coding
In total 4 different types of RLC/MAC blocks are used:
DL RLC/MAC control blocks (CS 1, used for GPRS and E-GPRS, content may be different)
UL RLC/MAC control blocks (CS 1, used for GPRS and E-GPRS, content may be different)
E-GPRS DL RLC/MAC data blocks (MCS 1-9)
E-GPRS UL RLC/MAC data blocks (MCS 1-9)
For the transfer of user data, nine Modulation and Coding Schemes (MCS) have been specified.
Four MCSs use GMSK, the remaining 5 MCSs use 8PSK.
The transmission of information is again organised in radio blocks. After the use of a MCS,
The resulting bits have to be transmitted on four normal burst on four consecutive
TDMA frames In other words, after adding redundancy and performing the modulation scheme, 456
symbols have to be transmitted.
EGPRS Modulation and Coding Scheme E-GPRS RLC data unit size (in octets)
MCS-1 22
MCS-2 28
GMSK
MCS-3 37
MCS-4 44 For
MCS-5 56 user
MCS-6 74 data
8PSK MCS-7 2x56
MCS-8 2x68
MCS-9 2x74
32. EGPRS MCS Families
The modulation and coding schemes are organised in families. Each family is characterised by a
basic unit of payload resp. RLC data length:
In EDGE basic unit of payload MCS-3
are defined.
Family A 37 octets 37 octets 37 octets 37 octets
This allows retransmissions
with another MCS within the MCS-6
same family. E.g. one of the 2 MCS-9
RLC blocks of MCS 8 may be MCS-3
retransmitted using MCS 3
34 +3 octets 34 +3 octets
(requires 2 Radio blocks) or
Family A
MCS 6 (within one padding MCS-6
Radioblock). 34 octets 34 octets 34 octets 34 octets
MCS-8
37 octets MCS-2
Family B 28 octets 28 octets 28 octets 28 octets
34 octets
MCS-5
28 octets MCS-7
MCS-1
22 octets 22 octets 22 octets
Family C
MCS-4
33. The padding option
MCS 7: 44.8 kbit/s MCS 8: 54.4 kbit/s MCS 9: 59.2 kbit/s
When switching to MCS-3 or MCS-6 from MCS-8, 6 padding octets are added to the data octets.
RLC-1 RLC-2
First transmission with MCS-8 in 1 Radio block
34 octets 34 octets 34 octets 34 octets
Retransmission in case of RLC ack with:
Either MCS-8 in 1 Radio block 34 octets 34 octets 34 octets 34 octets
Or MCS-6 in 2 Radio blocks 34 +3 octets 34 +3 octets
Each RLC within one radio block
34 +3 octets 34 +3 octets
Or MCS-3 in 4 Radio blocks
34 +3 octets
34 +3 octets
Each RLC within 2 radio blocks
34 +3 octets
34 +3 octets
1 half RLC
34. Combined RLC/MAC Header for EDGE user data
Downlink Stealing Bits in Uplink
Normal burst indicate 3GPP
the Header type 4.60
8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1
TFI RRBP ES/P USF TFI Countdown value SI R
BSN1 PR TFI BSN1 TFI
Header type BSN2 BSN1
BSN1 1
BSN2
BSN2 BSN1 for MCS 7,8,9
sp. PI RSB CPS
CPS BSN2
spare
TFI RRBP ES/P USF TFI Countdown value SI R
BSN1 PR TFI Header type BSN1 TFI
BSN1 2 CPS BSN1
for MCS 5,6 spare PI RSB CPS
CPS BSN1
spare
TFI RRBP ES/P USF
TFI Countdown value SI R
BSN1 PR TFI Header type
BSN1 TFI
3
BSN1 CPS BSN1
for MCS 1,2,3,4
SPB CPS BSN1 sp. PI RSB SPB CPS
35. Differences in the Headertypes
Header type 1 RLC-1 RLC-2
for MCS 7,8,9
Contains 2 RLC blocks, 2 Block sequence numbers are required. BSN 2 (10
bits) provides the BSN of the second block relative to the first one (11 bits).
BSN1 11 bit BSN2 10 bit
Header type 2 RLC
for MCS 5,6
Contains 1 RLC block, 1 Block sequence numbers is required.
BSN1 11 bit
Header type 2 ½ RLC 1 RLC
for MCS 1,2,3,4 or
Contains 1 or ½ RLC block, 1 Block sequence numbers is required. The case of retransmitted
half blocks is indicated by the Split Block Indicator field bits SPB
00 No retransmission
BSN1 11 bit SPB 01 Reserved
10 Retransmission – first part of block
11 Retransmission – second part of block
36. MAC part of combined RLC/MAC header
6 5 4 3 2 1
Uplink
Countdown value SI R Countdown value, Stall Indication, Retransmission bit, used as for GPRS
7 6 5 4 3 2 1
Downlink
RRBP ES/P USF
USF is exactly defined as for GPRS. Within EDGE it will be encoded separatly in exactly the same
way as for GPRS. This allows sending EDGE blocks (of course GMSK blocks) to EDGE users,
while addressing GPRS MSs in Uplink.
EGPRS Supplementary/Polling (ES/P) Field
ES/P Feedback Request (Poll) Description
00 Nothing (RRBP field invalid)
01 EGPRS PACKET DOWNLINK ACK/NACK message containing FPB (First Partial Bitmap), drop channel
quality report
10 EGPRS PACKET DOWNLINK ACK/NACK message containing NPB (Next Partial Bitmap), drop channel
quality report
11 EGPRS PACKET DOWNLINK ACK/NACK message containing NPB and Channel Quality Report
RRBP value specifies a single uplink block in which the mobile station shall transmit either a
PACKET CONTROL ACKNOWLEDGEMENT message or a PACCH block to the network in the
same way as for GPRS.
37. Other new fields in the RLC/MAC header
CPS MCS Puncturing Schemens
MCS-1 PS 1, 2
Coding and Puncturing Scheme indicator field (CPS) MCS-2 PS 1, 2
In EGPRS header, the Coding and Puncturing
MCS-3 PS 1, 2, 3
Scheme indicator field is used to indicate the kind of
channel coding (MCS) and puncturing (PS) used for MCS-4 PS 1, 2, 3
data blocks. MCS-5 PS 1, 2
5 bits - header type 1 CPS MCS-6 PS 1, 2
3 bits - header type 2 CPS
MCS-7 PS 1, 2, 3
4 bits - header type 3 CPS
MCS-8 PS 1, 2, 3
RSB Uplink only MCS-9 PS 1, 2, 3
The Resent Block Bit (RSB) indicates whether any of the RLC data blocks contained within the EGPRS
radio block have been sent previously.
bit
0 All of the RLC data blocks contained within the EGPRS radio
block are being transmitted for the first time
1 At least one RLC data block contained within the EGPRS radio
block has been transmitted before.
38. The RLC part of combined RLC/MAC Header
EGPRS RLC Data block Extension and length Indication used
Length Indicator E almost in the same way as in GPRS
(no ‘more’ bit in EGPRS)
Downlink Uplink
E FBI EGPRS RLC data unit E TI EGPRS RLC data unit
FBI
Final Block Indication and
TITLLI Indication and
E Extension bit give the RLC header E Extension bit give the RLC header
8 7 6 5 4 3 2 1 Bit-No
8 7 6 5 4 3 2 1 Bit-No Length Indicator E octet 1
Length Indicator E octet 1
. octet 2 Optional
.
octet 2 Optional . octets
octets Length Indicator E octet M
Length Indicator E octet M+1 UL
octet M DL RLC
octet M+1 RLC TLLI
Data
data block
block octet M+4
RLC data PFI E octet M+5
octet N2-1
RLC data octet N2-1
octet N2 octet N2
39. Channel coding in EGPRS
Downlink
RLC/MAC
USF Header RLC Data Block RLC Data Block
Uplink Two RLC blocks for MCS 7,8,and 9, each block is treated separately.
RLC/MAC
Header RLC Data Block RLC Data Block
Within EDGE the channel coding process is different for USF (only DL), RLC/MAC Header
and RLC Data Block.
USF Precoding to 12 bits is performed to get the same type of encoding as in GPRS.
RLC/MAC Parity bits are calculated and added to the end (For DL RLC/MAC part without USF).
Header An 1/3 rate convolutional encoder is used to get 3 times the bits, then some bits are
deleted again (punctured)
RLC Data Block
Parity bits are calculated and added to the end of an RLC data block. Additional tailbits are added. An 1/3
rate convolutional encoder is used to get 3 times the bits, then some bits are deleted again (punctured). For
one MCS different Puncturing Schemes (2 or 3) are applied.
40. Coding and Interleaving
RLC/MAC
USF Header RLC Data Block
The number of bits in header or
data part and the number of
Header with parity bits RLC with parity and tail bits punctured bits depends on the MCS
and direction (UL or DL).
GSM rec 3.64
x4 x3 x3
puncturing puncturing
Bits sent over the air:
For MCS 1-6: 1 RLC block for MCS 7-9: 2 RLC blocks
Next step is interleaving. The bits are distributed on 4 bursts of one radio block.
USF (only UL) part is interleaved on four bursts
Header part is interleaved on four bursts.
RLC blocks are interleaved on 4 bursts except for MCS 8 and 9 where each RLC is on
interleaved on 2 bursts .
41. Coding Process Example: MCS-2 DL
3 bits 36 bits 244 bits
RLC/MAC
USF Header HCS E FBI RLC Data = 22 octets BCS TB
convolutionary coding: rate 1/3
12 bits 108 bits 732 bits
Puncturing (P1, P2)
SB= 68 bits
12 bits 12 bits 372 bits
normal burst normal burst normal burst normal burst
42. Coding Process Example: MCS-8 DL
3 bits 45 bits 564 bits 564 bits
RLC/MAC RLC Data RLC Data
USF Header HCS E FBI = 2 x 34 octets BCSTBE FBI = 2 x 34 octets BCSTB
convolutionary coding: convolutionary coding:
rate 1/3 rate 1/3
36 bits 135 bits 1692 bits 1692 bits
Puncturing Puncturing Puncturing
(P1, P2, P3) (P1, P2, P3)
SB= 124 bits
8 bits 36 bits 612 bits 612 bits
normal burst normal burst normal burst normal burst
43. EGPRS Coding Parameters
RLC RLC blocks header data
modu- code BCS HCS
block per radio code family rate
lation rate length length
length block rate (kbps)
MCS-1 0.53 176 1 0.53 C 8.8
MCS-2 0.66 224 1 0.53 B 11.2
GMSK 296 A 14.8
MCS-3 0.85 1 0.53
48+248 A (p) 13.6
12
MCS-4 1.0 352 1 0.53 C 17.6
MCS-5 0.37 448 1 1/3 8 B 22.4
592 A 29.6
MCS-6 0.49 1 1/3
48+544 A (p) 27.2
8PSK
MCS-7 0.76 448 2 0.36 B 44.8
MCS-8 0.92 544 2 2x12 0.36 A (p) 54.4
MCS-9 1.0 592 2 0.36 A 59.2
Please note, different Code Rates for header and data!
A (p) = family A padding
44. EDGE coding compared with GPRS
9 Channel coding schemes (MCS) are defined.
The MCS is indicated in the RLC/MAC header (blind detection).
EDGE MSs have to support all GPRS CS and all MCS in DL, the usage of 8 PSK in UL is optional.
Networks may only support a subset of all MCS.
9 MCSs
EDGE introduces a new 1/3 rate convolutional coder, which alllows a very strong encoding.
Different types of coding are used for the USF (DL only), header- and datapart.
Encoding rules are slightly different for UL and DL. Channel coding
EDGE introduces introduces for each MCS 2 or 3 different Puncturing Schemes. Puncturing
Puncturing is done differently for header- and data-part.
Interleaving
EDGE defines new interleaving rules. Header- and data-part are treated differently.
For the USF the SACCH encoding and interleaving is emulated.
For MCS 1-7 the RLC block is interleaved on all 4 bursts of one block, for MCS 8 and 9 one
RLC block is found only on two bursts. The idea is to offer better performance of
these MCSs in a hopping network.
45. Chapter 10
EGPRS Protocols
10.5 RLC MAC enhancements
1. EDGE specific RLC/MAC modifications
2. Network access mechanism
3. EGPRS Packet Channel Request
4. other new RLC/MAC messages for EGPRS
47. Network access mechanism
The message used by an EDGE capable
MS to gain access to the network depends Sys info 13 on BCCH
on some conditions . A new
EDGE PACKET CHANNEL REQUEST PSI 13 on PBCCH
control message is defined MS
Sys info 13: support of PBCCH EGPRS PACKET CHANNEL REQUEST
or
yes no
PACKET CHANNEL REQUEST
EDGE support? or
CHANNEL REQUEST
yes no
Use CHANNEL REQUEST on CCCH GPRS only
Support of EGPRS PACKET CHANNEL REQUEST? Whether 8 or 11 bit burst is used is
indicated in Sys info or PSI
yes no
Switch to PBCCH: EDGE support?
Use CHANNEL REQUEST on RACH
yes no
Use EGPRS_PACKET_CHANNEL_REQUEST on RACH
Use PACKET CHANNEL REQUEST on PRACH (8 or 11 bits) GPRS only
Support of EGPRS
no Use PACKET CHANNEL REQUEST on PRACH (8 or 11
PACKET CHANNEL
bits)
REQUEST?
yes Use EGPRS_PACKET_CHANNEL_REQUEST on
PRACH
48. EGPRS Packet Channel Request
EGPRS PACKET CHANNEL REQUEST
11 Bits of Information
when used for:
One-Phase Packet Access Request 0 Multislot class Radio Random
Priority reference
Short Access Request 1 0 0 Number of Radio Random
slots Priority reference
Two-Phase Packet Access Request 1 1 0 0 0 0 Radio Random
Priority reference
Signalling (GMM/MM) 1 1 0 0 1 1 Random
reference
There are different Training Sequences defined. By choosing one the MS indicates whether it supports 8-PSK
in UL or not.
Format of access burst:
Tail Encoded data Training Sequence tail
3 36 41 8
Number of Bits
49. other new RLC/MAC control messages (3GPP 4.60)
Global TFI Additional MS Radio capability IE in some messages
This information element contains the TFI of the mobile station's uplink TBF, if available, or the TFI of the mobile
station's downlink TBF. If no TFI is available, this field is omitted.
TLLI IE (32 bit field)
MS Radio Access Capability 2
This information element is sent during one phase and two phase access procedures on CCCH or PCCCH .
< EGPRS Packet Downlink Ack/Nack message content > ::= EGPRS Packet DL ACK/NACK
< DOWNLINK_TFI : bit (5) >
< MS OUT OF MEMORY : bit(1)>
{0|1 < EGPRS Channel Quality Report : < EGPRS Channel Quality Report IE > >}
{0|1 < Channel Request Description : >Channel Request Description IE > >}
{0|1 < PFI : bit(7) > }
{0|1 < Extension Bits : Extension Bits IE > }
< EGPRS Ack/Nack Description : < EGPRS Ack/Nack Description IE >>
<padding bits > ;
< Packet Downlink Ack/Nack message content > ::= Packet DL ACK/NACK used for GPRS
< DOWNLINK_TFI : bit (5) >
< Ack/Nack Description : < Ack/Nack Description IE > >
{ 0 | 1 < Channel Request Description : < Channel Request Description IE > > }
< Channel Quality Report : < Channel Quality Report struct > >
{ null | 0 bit** = <no string> -- Receiver backward compatible with earlier version
|1
-- Additional contents for Release 1999 8
{ 0 | 1 < PFI : bit(7) > }
< padding bits > };
Hinweis der Redaktion
TS 45.002 V5, chap. 3 (darstellung wurde stark vereinfacht!)
TS 43.064, chap. 6.5.4
TS 43.064, chap. 6.5.5.1.1. Beachte, daß die oberen Layers die radio blocks ohne USF und BCS in der richtigen groesse liefern muessen. Aber das geht ohne probleme, da der RLC, der für segmentation verantwortlich ist, den verwendeten CS kennt.
TS 43.064, chap. 6.5.5.1.1. Beachte, daß die oberen Layers die radio blocks ohne USF und BCS in der richtigen groesse liefern muessen. Aber das geht ohne probleme, da der RLC, der für segmentation verantwortlich ist, den verwendeten CS kennt.
Aus dem TC UMTS Rel 4, 5, 6 Kurs entnommen TC 1105 chap. 5
TS 45.002 V5, chap. 3 (darstellung wurde stark vereinfacht!)
TS 45.002 V5, chap. 3 (darstellung wurde stark vereinfacht!)
TS 45.002 V5, chap. 3 (darstellung wurde stark vereinfacht!)
TS 45.002 V5, chap. 3 (darstellung wurde stark vereinfacht!)
TS 45.002 V5, chap. 3 (darstellung wurde stark vereinfacht!)