1. Second Generation Systems
Lectures 2 and 3
Second Generation Systems
Prof. Hamid Aghvami
Centre for Telecommunications Research - King’s College London

2. Digital Cellular Mobile Communications Technologies
(Second Generation)
Global System for Mobile Communications (GSM) specified by ETSI:
- to replace the first generation analogue systems
American TDMA System (IS-54) specified by TIA
- to enhance the existing analogue system
-Dual Mode
Japanese Personal Digital Cellular (PDC) specified by MPT
-to enhance the existing analogue system
CDMA Systems (IS-95)

3. Personal Communication Networks
Digital Cellular System at 900 and 1800 MHz (GSM-900 & GSM-1800)
- Europe
Personal Communication Systems at 1900 MHz (GSM-1900)
- North America
D-AMPS at 1900 MHz (IS-136)
CDMA Systems at 1900 MHz (cdma one)
Personal Handy-Phone System (PHS)
- Japan

4. Radio Local Area Networks Cordless Telecommunication Systems
IEEE Project
High Performance Radio LAN (HIPERLAN )
Cordless Telecommunication Systems
Digital Enhanced Cordless Telecommunications (DECT )
Other Systems
Trans-European Trunked Radio (TETRA)

5. GSM

6. Three phases of the GSM standard
GSM Phase 1 Completed in 1990
GSM Phase 2 Completed in 1994
GSM Phase 2+ Being Standardized

7. Global System for Mobile Communications (GSM )
GSM digital cellular mobile radio was introduced into Europe
in1992, the common European standard for a cellular radio
system.
Background:
Conference of European Post and Telecommunications
(CEPT ) administration set up the “Groupe Special Mobile” to
derive the specification of a common European cellular mobile
system.
A decision was reached to implement a digital
transmission system.

9. Basic Architecture of GSM
AUC
other VLRs
Base Station Subsystem (BSS) H G D
EIR
HLR
VLR
OMC C B F
BTS
other BSSs
A-bis
Mobile
Services
Switching
Centre
(MSC) A
BSC
BTS
PSTN
ISDN
CSPDN
PSPDN Um
BTS E
BTS – simple transceiver (transmitter + receiver) without any intelligent
BSC – responsible for radio resource allocation, terrestrial channel management, mapping of radio channels onto wired channels and execution of hand-over.
MSC – switching and routing
HLR – a data base holding general information about subscribers
VLR – a temporary data base holding visiting subscriber’s general information during their visit. It also holds location area identities of the roaming users.
EIR – a data base holding user equipment identities.
OMC – a data base holding relevant information about overall operation and maintenance of the network. MS
other MSCs
BTS: Base Transceiver Station
BSC: Base Station Controller
HLR: Home Location Register
VLR: Visited Location Register
OMC: Operation & Maintenance Centre
EIR: Equipment Identity Register
AUC: Authentication Centre
Basic Architecture of GSM

10. Frequency Bands and Bandwidth
Uplink 890 – 915 MHz 25 MHz
Downlink 935 – 960 MHz 25 MHz
……………. 1 2 3 4
124
100 KHz
200 KHz
100 KHz
A 200 KHz carrier spacing has been chosen. Excluding 2x100 KHz edges of
the band, this gives 124 possible carriers for the uplink and downlink. The
use of carrier 1 and 124 are optional for operators.
Multiple Access Technique
FDMA/TDMA. The total band is divided into 124x200 KHz bands (FDMA).
Each group of 8 users transmit through a 200 KHz band sharing
transmission time (TDMA).

11. Logical Channel Types Logical Traffic channels (TCHs)
The traffic channels are intended to carry encoded speech or
user data.
Logical Control Channels (CCHs)
The control channels are intended to carry signalling and
Synchronization data between the base station and the
Mobile station.

12. Logical Traffic Channels
Traffic channels are intended to carry encoded speech and
user data.
Full rate traffic channels at a net bit rate of 22.8 Kb/s (TCH/F)
Half rate traffic channels at a net bit rate of 11.4 Kb/s (TCH/H)
Data Channels
Speech Channels
Speech channels are defined for both full rate and half rate
traffic channels. The latter for the future system.
Data channels support a variety of data rates (2.4, 4.8 and
9.6 Kb/s) on both half and full rate traffic channels. The 9.6
Kb/s data rate is only defined for full rate application.

13. Logical Control Channels
Downlink
Uplink
Broadcast Control Channels
Frequency Correction - FCCH
Synchronization – SCH
Broadcast - BCCH -
Common Control Channels
Access Grant - AGCH
Paging - PCH
Common Control Channels
Random Access - RACH
Dedicated Control Channels
Stand – alone Dedicated - SDCCH
Slow Associated – SACCH
Fast Associated - FACCH

14. Broadcast Control Channels (Downlink only Channels)
Broadcast Control Channels (BCCH) – Broadcasts to all mobiles
general information regarding their own cell as well as the
neighbouring (up to 16) cells, e.g. information used for cell
selection and for describing the current control channel structure.
Frequency Correction Channels (FCCH) – for mobiles for
frequency correction.
Synchronization Channels (SCH) – for frame synchronization of
mobiles and identification of the base station.

15. Common Control Channels
Access Grant Channels (AGCH) – for assignment of a dedicated
Channel after a successful random access.
Paging Channels (PCH) – for paging to mobiles.
For downlink
Random Access Channels (RACH) – used for random access
Attempts by mobiles.
For uplink
There are three downlink only channels and one uplink only channel.

16. Dedicated Control Channels
Stand-alone Dedicated Control Channels (SDCCH) – are major
signalling channels used for location updating, registration,
point-to-point SMS and handover preparation.
8 SDCCH sent through one physical channel each having a bit rate
of approximately 782 bits/s.
Slow Associated Control Channels (SACCH) – always associated
with TCH, SDCCH or FACH and carry timing advance and power
control measurement results and information.
The bit rate per channel is 391 bits/s.

17. Fast Associated Control Channels (FACCH) – carry the same
Signalling data as SDCCH. They are used in the case when a very
fast exchange of information is needed, e.g. , in the case of a
hand-over. It accesses to the physical resource by stealing frames
From the TCH.
The bit rate of this channel is 9.2 kbits/s.

18. One full-rate channel (multiframe)
1 TDMA frame = 8 timeslots (4.615 ms) 1 2 3 4 5 6 7
120ms
TC0
TC1
TC10
TC11
SACCH
TC12
TC13
TC23
Idle
One full-rate channel (multiframe)
GSM uses both FDMA and TDMA. The total band per operator is divided into 200 KHz sub-bands (FDMA). Each group of 8 users transmit through a 200 KHz band sharing transmission time (TDMA).
The transmission time is divided into multi-frame (120 ms period). Each multi-frame consists of consecutive 26 frames. 24 frames in each multi-frame are assigned to traffic channels (TC) and one frame (13th frame) to SACCH and one frame (26th frame) is not used (Idle frame).
Each frame, in turn, divided into 8 time slots (physical channels). Each time slot is assigned to a user during a call.

19. Burst types in GSM stealing flags (1) (1) normal burst
guard period(8.25)
data(57)
training sequence(26)
data(57)
start(3)
stop(3)
frequency correction
fixed bits(142)
burst
synchronisation
data(39)
extended training(64)
data(39)
burst
start(3)
stop(3)
mixed bits(58)
training(26)
mixed bits(58)
dummy burst
There are 5 burst structures defined in GSM. The most important one is the normal burst. The normal burst consists of two data fields, each containing 57 bits of data. A 26 bit training sequence is used to estimate the characteristic of radio channel (impulse response) in the receiver. A 3 bit start and a 3 bit stop are used to reset the adaptive equalizer at the receiver. 2 bits stealing flags are used to inform the receiver that the two data fields contain the actual traffic or replaced with FACCH signalling. In the guard period (8.25 bit duration) no signal is transmitted. The existence of the guard period is due to ramp-up and ramp-down of the power amplifier at the start and stop of a burst transmission.
extended start(8)
stop(3)
extended guard period
access burst
synch. seq.(41)
data(36)
(68.25)
Burst types in GSM

20. Channel Combinations The four most common channel combinations are:
Full rate traffic channel combination
TCH/F + FACCH + SACCH (any timeslot)
Broadcast channel combination
BCCH + CCCH (0,2,4,6-0 is used first)
Dedicated channel combination
SDCCH/8 + SACCH/C8 (any timeslot)
Combined channel combination
BCCH + CCCH + SDCCH/4 + SACCH/C4 (only 0)

21. Low capacity cell configuration
1 RF carrier: 8 physical channels
1 physical channel (timeslot 0) configured as:
BCCH + CCCH + SDCCH/4 + SACCH/C4
7 physical channels (timeslots 1, …., 7) configured as:
TCH/F + FACCH + SACCH

22. High capacity cell configuration
5 RF carrier: 40 physical channels
1 physical channel (timeslot 0) configured as:
BCCH + CCCH
2 physical channels (timeslots 2, 4) configured as:
CCCH
2 physical channels (timeslots 0, …., 7) configured as:
SDCCH/8 + SACCH/C8
35 physical channels (timeslots 0, …., 7) configured as:
TCH/F + FACCH + SACCH

23. Block Diagram of the Digital Mobile Radio System
Mobile Station (MS)
Base Station System (BSS)
FEC Encoder
De-
Burst-to
FEC Decoder
Speech
Burst
&
Modulator Tx Rx
modulator
-Continous
&
Encoder
Interleaving
Former
Rate
De-Interleaving
Transcoder
Converter
to MSC
Speech
FEC Decoder
Burst-to
Burst
De-
FEC Encoder
& Rx Tx
Modulator
Transcoder
Decoder
-Continous
modulator
Former
&
De-lnterleaving
Rate
Interleaving
Converter
from MSC
Block Diagram of the Digital Mobile Radio System

24. GSM system features Adaptive time alignment
BS is initially calculated the timing advance of MSs on the basis of
the received access burst on the RACH
The required timing advance for each MS is calculated in terms of
the number of bit periods and sent to the MS as a 6 bit number.
Timing advances from 0 to 63 bit periods can therefore be
accommodated, giving a maximum BS – MS separation of 35 Km

25. 2. Power control
RF power control will be used in the GSM MS and BS to reduce
the transmit power to the minimum required to achieve the
minimum quality objective and hence reduce the level of co-channel
interference
The MS will be capable of varying its transmit power form its
maximum output down to 20 mW in steps of nominally 2 dB
The BS calculates the RF Power level to be used by the MS and
sends a 4 bit number instruction to the corresponding MS

26. A GSM mobile is only active, i.e., either transmitting or receiving,
3. Handover
A GSM mobile is only active, i.e., either transmitting or receiving,
in 2 or the 8 timeslots in one frame
The MS scans transmissions from surrounding BSs in the spare
timeslots. It then reports the measured results, together with those
for the serving BS, back to the fixed network via the BS, where the
handover decision is made. This mechanism is referred to Mobile
Assisted HandOver (MAHO).
GSM uses the following Handover mechanisms:
Backward handover – The signalling related to handover, just before the handover, is exchanged between the MS and the network through the current BS (not through the target BS).
Hard handover – The MS disconnects from the current BS and connects immediately to the target BS (Break and make). The MS is always connected to one BS.
MAHO – The MS assists the network on handover decision by measuring the received powers from its serving and neighbouring BSs and reports them to the network. These results are used by the network in the handover algorithm. The handover decision and control are the sole responsibility of the network.

27. Inter-BSS Handover Procedure

28. GSM mandatory features
Discontinuous transmission and reception (with the aid of
Voice activity detector)
Advantages:
The level of co-channel interference is, on average, reduced
By about 3 dB
For a hand-held portable unit, the battery life can be significantly
extended

29. 2. Slow frequency hopping
Advantages:
The receive TDMA bursts with high error rates will be more
spread in time
The co-channel interference is more evenly spread between
all the MSs

30. GSM Network Protocol ArchitectureMS
BTS
BSC
MSC CM CM MM MM
Layer 3
BSSAP RR
BSSAP RR RR
BTSM
BTSM
SCCP
SCCP
Layer 2
LAPDm
LAPDm
LAPD
LAPD
MPT
MTP
physical
physical
physical
physical
Layer 1
layer
layer
layer
layer
Um Interface
A-bis interface
A interface
GSM Network Protocol Architecture

31. Layer 3 Functions are divided into 3 categories:
1. Radio Resource (RR) Management:
Function relating to the establishment of physical connections for
the purpose of transmitting call-related signalling information.
2. Mobility Management (MM):
Functions relating to location registration, paging,
attachment/detachment, handover, dynamic channel allocation
and management.
3. Connection Management (CM):
Call control related functions, SMS and service handling
functions.

32. The data link layer (layer 2) over the radio link is based on a
modified LAPD (Link Access Protocol for the D channel)
referred to as LAPDm.
On the A-bis interface, the layer 2 protocol is based on the LAPD
from ISDN.
The Message Transfer Part (MTP) level 2 of the SS& protocol is
used at the A interface.

33. LAPD frame structure 0 1 1 1 1 1 1 0 Address octet 1 Address octet 2
Address octet 1
Address octet 2
Control octet 1
Control octet 2
Layer 3 information
FCS octet 1
FCS octet 2
Octet 1
Opening flag
Octet 2
Octet 3
Octet 4
The structure of the control
filed depends on the frame type
Octet 5
Octet 6
Layer 3 information is only
presented in Layer in Layer 2
‘information frame’
Octet N-3
Octet N-2
Frame check sequence
Octet N-1
Frame check sequence
Octet N
Closing flag
LAPD frame structure

34. A – bis interface
CM and MM messages are not interpreted by the BSC or the BTS.
they are transferred over the A-bis interface as transparent messages
and over the A interface using the Direct Transfer Application Part
(DTAP).
RR messages are mapped to the BSS Application Part (BSSAP) in
the BSC. In the BTS, most of them are handled as transparent by
the BTS (e.g. random access, start ciphering, paging).
BTS Management (BTSM) is used to transfer all OAM related
information to the BTS.

35. A interface
The Message Transfer Part (MPT) and the SCCP (Signalling
connection Control Point) are used to support the transfer of
signalling messages between the MSC and the BSS.
The SCCP part is used to provide a referencing mechanism to
Identify a particular transaction relating to, for instant, a particular
call. The SCCP can also be used to enhance message routing,
operation and maintenance information.

36. The MTP part provides a mechanism for providing the reliable
transfer of signalling messages. A subset of MTP is used between
the BSS and the MSC.
The BSSAP provides the channel switching and aerial functions, it
performs RR management, and the interworking functions between
the data link protocols used on the radio and the BSS-MSC side for
transporting signalling related messages.

37. MSISDN is the ‘directory number’ used to call GSM subscribers.
IMSI is the main subscriber number used internally within GSM.
MSRN is the routing number used on the second leg of an incoming
call between GMSC and serving MSC. It is not known to GSM users.
Both MSISDN and IMSI contain a country identity and a network
identity Within the country.
MSRN can be contained in the HLR record if the serving MSC/VLR
has provided it when updating the location information.

38. HLR
(1) MSISDN
(2) IMSI
(4) MSRN
(3) MSRN
Incoming Call
MSRN
GMSC
MSC / VLR
MSISDN
An example of a call routing (to route an incoming call towards serving MSC)
The HLR stores within each subscriber record an address of the visited MSC/VLR. The HLR record may also store an MSRN, if the visited MSC/VLR has provided such a roaming number when updating the visited MSC/VLR address. If such a roaming number is not stored in the HLR record, the HLR will interrogate the MSC/VLR using the subscriber IMSI to get an MSRN. The MSRN is then used to route the call from GMSC to the MSC/VLR (second leg of the call).
The visited MSC/VLR chooses the MSRN from a pool of free numbers, and associates it temporarily with the called Subscriber’s IMSI.
MSISDN
Mobile Station ISDN Number
IMSI
International Mobile Subscriber Identity
MSRN
Mobile Station Roaming Number

39. Protocols in the call control producers
MAP/D
HLR
RIL3-CC
MAP/C MS
MSC/VLR
GMSC
Protocols in the call control producers
RIL3-CC
Radio Interface Layer 3 - Call Control
MAP
Mobile Application Part

40. Service
Telephony
Emergency Call
Messaging
Data up to 9.6Kb/s
Fax

41. Supplementary Services
Number Identification
Call Barring
Call Forwarding
Call Waiting
Advice of Charge
Group Multi-party Service
Closed User Group

42. GSM phase 2 Correction of error and limitations
Introducing half-rate speech coding standard (optional)
Implementation of new data services and supplementary services
-Call waiting -call hold -multi party
-closed user group -advice of charge -line identification
Fax (G3)
Merging of GSM and DCS-1800 standards and extended frequency bands (+10 MHz)
GSM phase 2 recommendations were published in December 1994

43. GSM phase 2 + General Packet Radio Services (GPRS)
High Speed Circuit Switched Data (HSCSD)
Enhanced Data rates for GSM Evolution (EDGE)
Customised Applications for Mobile network Enhanced
Logic (CAMEL)

44. General Packet Radio Service (GPRS)
GPRS is a packet switched transmission mode currently being standardized by SMG2 within GSM phase 2+ framework.
Intended to support frequent transmission of small volumes and infrequent transmission of medium volumes (but not packetized speech).
Support point-to-pint (ptp) Connectionless (CL), ptp Connection-oriented (CO) and point-to-multipoint (ptm) services.
A GPRS traffic channel may occupy one or more TDMA time slots within a GSM carrier frame.
It is possible to increase or decrease the number of physical channels allocated to GPRS on a dynamic basis.

45. Overview of the GPRS Logical Architecture
SGSN
BSS
GGSN
SMS-GMSC
SMS-IWMSC A Gc Gn Gb MT Um
HLR Gi Gd D
SM-SC
Other PLMN Gp R TE
MSC / VLR Gr Gs C E
PDN
EIR Gf
SGSN: Serving GPRS Support Node
GGSN: Gate GPRS Support Node
PDN: Packet Data Network
Signalling and Data Transfer Interface
Signalling Interface
Overview of the GPRS Logical Architecture

46. GPRS Network Elements MS : Both software and hardware upgrade needed
BTS : Software upgrade needed – No change in hardware
BSC : Software upgrade needed –The only hardware change is PCU
interface
TRAU : No change
HLR and VLR : Software upgrade needed – No change in hardware
SGSN : New
GGSN : New

47. GPRS Mobile Station Operation Modes
Class A : Circuit-switched and packet-switched simultaneous services.
Class B : Automatic selection of circuit-switched or packet-switched
service but not simultaneously.
Class C : Packet-switched service only.

48. (Uplink / Downlink and uni-directional)
Logical channel
Traffic channels
Control Channels
Packet Data Traffic Channel /
Full rate (PDTCH / F)
Packet Data Traffic Channel /
Half rate (PDTCH / H)
(Uplink / Downlink and uni-directional)
Packet Broadcast Control
Channel (PBCCH)
(Downlink)
Packet Timing advance
Control Channel Downlink
(PTCCH / D)
Packet Paging
Channel (PPCH)
(Downlink)
Packet Access Grant
Channel (PAGCH)
(Downlink)
Packet Notification
Channel (PNCH)
(Downlink)
Packet Associated Control
Channel (PACCH)
(bi-directional)
Packet Random Access
Channel (PRACH)
(Uplink)
Packet Timing advance
Control Channel Uplink
(PTCCH / U)

49. Multiframe Structure for PDCH
52 TDMA Frames B0 B1 B2 I I B9 B
B10
B11 I
I: Idle frames
B: Radio blocks
Multiframe Structure for PDCH BH
Information field
BCS
Normal Burst
Normal Burst
Normal Burst
Normal Burst
BH: Block Header
BCH: Block Check Sequence
Block Structure

50. Coding parameters for the coding schemes

51. GPRS Layered Protocol Structure (User Plane)
MAC
GSM RF
SNDCP
LLC
RLC
Application
IP / X.25
IP / X.25
Relay
GTP
SNDCP
GTP
LLC
UDP/
TCP
UDP/
TCP
Relay
RLC
BSSGP
BSSGP IP IP
Network
Service
Network
Service L2
MAC L2
GSM RF
L1bis
L1bis L1 L1 MS Um
BSS Gb
SGSN Gn
GGSN Gi
PLL : Physical Link Layer
RFL : Radio Physical Layer
FR : Frame Relay
TCP : Transmission Control Protocol
UDP : User Datagram Protocol
GTP : GPRS Tunnelling Protocol
RLC : Radio Link Control
NS : Network Service
MAC : Medium Access Control
LLC : Logical Link Protocol
SNDCP : SubNetwork Dependent Convergence Protocol
BSSGP : BSS GPRS Protocol

52. GPRS Layered Protocol Structure (Control Plane)
Interworking
Relay
GMM SM
MAP
MAP
GMM SM
GTP
GTP
TCAP
TCAP
LLC
LLC
UDP
UDP
SCCP
SCCP
Relay
RLC
BSSGP
RLC
BSSGP IP IP
MTP3
MTP3
MAC
MAC
NS(FR)
NS(FR) L2 L2
MTP2
MTP2
PLL
PLL
Phy-
sical
Phy-
sical
Phy-
sical
Phy-
sical
MTP1
MTP1
RFL
RFL MS
BSS
SGSN
GGSN
HLR Um Gb Gn Gc
SM : Session Management
GMM : GPRS Mobility Management
MAP : Mobile Application Part
MTP : Message Transfer Part
TCAP : Transaction Capabilities Application Part
SCCP : Signaling Connection Control Part
BSSAP+ : Base Station System Application Part+

53. GPRS Protocols GPRS special protocols
SNDCP, LLC, RLC, MAC, BSSGP, BSSAP+, GTP
GSM protocols
PLL, RFL, GMM / SM, MAP
SS7 protocols
TCAP, SCCP and MTP
Internet protocols
IP, UDP / TCP

54. Medium Access Control (MAC) Sublayer
MAC sublayer maneges and controls access to shared medium between a multiple of MSs and the network. It’s functionalities include scheduling, queueing, contention resolution, PDCH multiplexing and power control.
Radio Link Control (RLC) Sublayer
The RLC sublayer is responsible for segmentation and reassemble of higher layer PDUs into RLC / MAC blocks, buffering and the selective re-transmission of unsuccessfully delievered RLC / MAC blocks with backward error correction.
Logical Link Control (LLC) Sublayer
The purpose of LLC is to transfer information between layer 3 entities in the MS
and SGSN independent of the underlying radio interface protocols. It’s functions
include sequence control, detection and recovery of format and operational errors
on a logical link connection, notification of unrecoverable errors, flow control and
ciphering.

55. Subnetwork Dependent Convergence (SNDC) Sublayer
The SNDC sublayer provides protocol transparency of network layer protocol data
units from a wide variety of subnetworks and data links through the underlying
radio interface.
Base Station System GPRS Protocol (BSSGP) Layer
The main function of BSSGP is to provide the radio related QoS and routing
information required to transmit user data between a BSS and SGSN. It’s
secondary function is to enable two physically distinct nodes (BSS and SGSN) to
operate node management control Functions.
Network Service (NS) Layer
The NS layer transfers upper layer protocol data units (NS SDUs) between a BSS
and SGSN that are connected by a direct point-to-point frame relay link or through
an intermediate frame relay network.

56. High Speed Circuit Switched Data (HSCSD)
HSCSD is a high speed circuit switched transmission mode currently being standardised by SMG2 committee of ETSI.
HSCSD is a GSM bearer service intended to use multiple time-slots for increased data rate over the GSM air interface.
HSCSD may be used for a wide variety of transparent and non-transparent tele-services.
For two timeslots allocated to one MS no need for simultaneous reception and transmission.

57. In both symmetric and asymmetric HSCSD configurations, one bi-directional channel (the main channel) carries a FACCH used for all the signalling not carried on the SACCH.
The same frequency hopping sequence and training sequence are used for all the channels in the HSCSD.
The same channel coding schemes as specified for TCH/F9.6 and TCH/F4.8 data channels are used.
A different channel coding may be considered at the later stage.

58. An example of HSCSD Configuration

59. Enhanced Data rates for GSM Evolution (EDGE)
The aim of EDGE is to use new modulation and channel coding techniques to evolve data services in GSM reusing as much of the physical layer as possible.
The EDGE concept has been considered for both GPRS (EGPRS) and Circuit Switched Data (ECSD).
8 PSK is the preferred modulation technique to provide high data rates.
It supports data rates from 22.8 Kb/s to 69.2 Kb/s depending on the channel coding.
Different coding proposals have been made, but no decision has been taken yet.

60. Coding parameters for the EGPRS coding schemes
MCS-9
MCS-8
MCS-7
MCS-6
MCS-5
MCS-4
MCS-3
MCS-2
MCS-1
Code rate
1.0
0.92
0.76
0.49
0.37
0.80
0.66
0.53
Header
Code rate
0.36
1/3
0.53
Modulation
RLC blocks
Per Radio
Block
(20ms) 2 1
Raw Data
Within one
Radio
Block
2x592
2x544
2x448
592
544+48
448
352 29
272+24
224
176
Family A B C
BCS
Tail
payload
HCS
Data rate
Kb/s
59.2
54.4
44.8
29.6
27.2
22.4
17.6
14.8
13.6
11.2
8.8
2x12
2x6
8PSK 8 12 6
GMSK
Note: The italic captions indicate the padding.

61. For more information about GPRS
Yi-Bing Lin, Herman C-H Rao and Imrich Chlamtac, “ General packet radio service (GPRS): architecture,
interfaces, and deployment “, Wireless Communications & Mobile Computing, Vol.1, No.1, Jan-Mar 2001,
ISSN