Understand about the Logical and Physical Channel FDMA & TDMA. Evolution of Packet Data Speed Introduction.

1. Presented by : Mr. Che Sokunth
Date : 17.Sept.2012

2. Contents
I. GSM Basic Channel Type
 Logical Channel
 Physical Channel
- FDMA & TDMA
II. Evolution of Packet Data Speed Introduction
 CSD
 HSCSD
 GPRS (2.5G)
 EDGE (2.75G)
 UMTS (3G/WCDMA)
 HSPA
1-HSDPA (3.5G)
2-HSUPA (3.75G)
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3. Logical Channel
Logical channels
 Logical channels divided in to following two categories:
 Traffic Channels
 Signaling Channels
 Two types of traffic channels used:
1. Full Rate Speech TCH (TCHF) - 13 kbps
2. Half Rate Speech TCH (TCHH) - 5.6 kbps
 Three type of Signaling Channels
1. Broadcast Channel – BCH
2. Common Control Channel – CCCH
3. Dedicate Control Channel - DCCH
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4. Logical Channel
Logical Channel
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5. Traffic Channel (TCH)
 Traffic channels are Bi-directional logical channel that transfer the user
speech or data.
 Full Rate TCH ( TCH/F) :
 This channel carries information at a gross rate at 13Kbit/s
 Now it is 22.8 Kbit/s with latest R9.1
 Half Rate TCH (TCH/H) :
 This Channel carried information at a gross rate at 6.5Kbit/s
 Now it is 11.4 Kbit/s with latest R9.1
 Enhance Full Rate :
 The speech coding in EFR is still done at 13Kbit/s, but the coding
mechanism is different that is used for normal FR. EFR gives better speech
quality at the same bit rate than normal FR.
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6. Logical Channel
I- Broadcast Channel – BCH
 Frequency Correction Channel (FCCH)
 Synchronization Channel (SCH)
 Broadcast Control Channel (BCCH)
 Cell Broadcast Channel (CBCH)
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7. Logical Channel
1- Frequency Correction Channel (FCCH)
 Downlink Direction
 This channel contains frequency correction bursts, used by the mobiles
for frequency correction
 Help the mobile station find a frequency for downlink reception
 Adjust its frequency oscillator for the uplink transmission
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8. Logical Channel
2- Synchronization Channel (SCH)
 Downlink Direction
 This channel is used by the MS to decode the BSIC
 NCC: To identify the BTS for which measurement is made
 BCC: Used for a better transmission in case of interference
 TDMA Frame and Frame Number
 Lets the MS know what TDMA frame they are on within the hyperframe.
 SCH bursts are located at slot 0 of some specific carriers
 The 64 bit frame synchronization is put in the synchronization field in
synchronization burst
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9. Logical Channel
3- Broadcast Control Channel (BCCH)
 Broadcasts Network and Cell specific information required to identify:
 Mobile Network Code (MNC)
 Mobile Country Code (MCC)
 Location Area Code (LAC)
 Cell identity
 Frequencies of neighboring cells
 Minimum received signal strength
 Max output power allowed in the cell
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10. Logical Channel
4- CELL BROADCAST CONTROL CHANNEL (CBCH)
 Downlink Direction
 Broadcasting specific information to network subscribers, such as:
 Weather
 Traffic
 Sports
 stocks, etc.
 It is used to carry Short Message Service Cell Broadcast (SMSCB) and
uses the same physical channel as the SDCCH
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11. Logical Channel
II. Common Control Channels (CCCH)
 Paging Channel (PCH) – Downlink
 Random Access Channel (RACH) - Uplink
 Access Grant Channel (AGCH) - Downlink
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12. Logical Channel
1. Paging Channel (PCH)
 Broadcast in the downlink by all base stations within a Location Area
 Every MS in a cell periodically listen to this channel.
 Used for alerting to Mobile Subscribers for:
 Incoming calls
 SMS and other mobility services.
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13. Logical Channel
2. Random Access Channel (RACH)
 Uplink direction only
 MS send request to the network for a dedicated resource
 MS sends an Access Burst on this channel (FN and TA)
 Random number and an establishment cause
 68.25-bit time is used as guard time. This guard time corresponds to a
propagation distance of 75 km, or a maximum cell radius of 37.5km
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14. Logical Channel
3. Access Grant Channel (AGCH)
 Downlink direction
 Initiate Immediate assignment procedure
 Network allocates a specific dedicated signaling channel
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15. Logical Channel
III. Dedicated Control Channels (DCCH)
 Standalone Dedicated Control Channel (SDCCH)
 Fast Associated Control Channel (FACCH)
 Slow Associated Control Channel (SACCH)
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16. Logical Channel
1. Standalone Dedicated Control Channel (SDCCH)
 Assigned to the mobile station to exchange the requested signaling
with the network:
 Authentication
 Ciphering
 Call set-up
 Location Update
 Assignment of Traffic Channel
 SMS
 Established by using RACH and before the allocation of a TCH (traffic
channel).
 Uses 4 slots within the 51-frame control multiframe
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17. Logical Channel
2. Slow Associated Control Channel (SACCH)
 transmitted in both Uplink and Downlink directions
 Associated with a TCH or an SDCCH for control and supervision of
signals associated with the traffic channels.
 Uplink : MS Sends the averaged measurement on its own BTS and
neighboring BTS’s
• Downlink: MS receives information regarding information concerning
• Transmit power to use
• Instructions on Timing Advance
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18. Logical Channel
3. Fast Associated Control Channel (FACCH)
 Both Uplink and Downlink Direction
 While Calls in progress and HO is required FACCH is used
 It ‘‘steals- 2 bits flag” to convert the TCH or SDCCH burst and inserts
its own information.
 It used to send urgent signaling control messages such as:
 User authentication
 Handover
 Call release
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19. Physical Channel
FDMA : Frequency Division Multiple Access
 Different frequency channels are assigned to each BTS
 ARFCN Carrier separation: 200kHz
 Carrier Frequency
 GSM 900 : 124
 GSM 1800 : 374
 GSM 1900 : 299
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20. Physical Channel
TDMA: Times Division Multiple Access
 A method where several subscribers share one frequency
 Each Timeslots are used to transmit voice data, or information on signaling
and synchronization
 There are four main types of bursts and 4 multiframes Structure in TDMA:
I. TDMA Burst
1. Normal Burst (NB)
2. Frequency Correction Burst (FB)
3. Synchronization Burst (SB)
4. Access Burst (AB)
II. TDMA Frame
1. Control Channel Multiframes
2.Traffic Channel Multiframes
3. Superframe
4. Hyperframe
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21. Physical Channel
Normal Burst (NB)
 Tail Bits: (3-Bits) Compensate the power to Increase and Decrease
 Data Bits: (57 Bits) Data Payload
 Stealing Flags: 0 for Voice/Data, 1 For signaling (Stolen By FACCH)
 Training Sequence: used to overcome multi-path fading and
propagation effects through a method called equalization.
TDMA Bust
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22. Physical Channel
Frequency Correction Burst (FB)
 Frequency synchronization
 The same guard time as a normal bit (8.25 bits)
 Broadcasting on the logical channel FCCH.
TDMA Bust
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23. Physical Channel
Synchronization Burst
 Timing for synchronization of the mobile
 Data payload carries the TDMA Frame Number (FN) and (BSIC)
 Broadcasting with the frequency correction burst
 Broadcasting on the Synchronization Channel (SCH).
TDMA Bust
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24. Physical Channel
Access Burst
 Use for random access
 It has a much longer guard period (delay for Unknown Distance)
 It takes 252 µs for expectation distance without interfere
 Single bit equal to 3.69 µs
TDMA Bust
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25. Physical Channel
Control Channel Multiframes
 Composed of 51 TDMA frames within duration 235.4 ms
 The beacon frequency in TS0 and it may also occur within TS2, 4 and 6
logical channels as below function: BCCH, FCCH, SCH, CCCH (RACH, PCH,
AGCH), SDCCH, SACCH, FACCH
TDMA Frame
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26. Physical Channel
Traffic Channel Multiframe
 Composed of 26 TDMA frames within duration = 120 ms
 24 bursts are used for traffic channel (TCH)
 2 Burst are used for measurement report (SACCH)
TDMA Frame
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27. Physical Channel
Superframe & Hyperframe
I. Superframe
 Combines the period of a 51 multiframe with 26 multiframes (6.12 sec)
 Allows all mobile devices to scan all the different time frame types
II. Hyperframe
 Composed of 2048 superframes (3 hours, 28 minutes, 53 seconds)
 The unique sequential number comprising the FN and TN
 Synchronize frequency hopping
 Encryption processes for voice privacy of subscribers' conversations
TDMA Frame
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28. Physical Channel
GSM Frame Structure Summary
TDMA Frame
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29. II. Evolution of Packet Data Speed Introduction
 CSD
 HSCSD
 GPRS (2.5G)
 EDGE (2.75G)
 3G/UMTS (WCDMA)
 HSPA
1-HSDPA (3.5G)
2-HSUPA (3.75G)
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30. CSD- Circuit Switched Data
 Developed in 1980, deployment in 1990
 Data transmission developed for TDMA-based mobile phone systems
like GSM.
 Data Rate 9.6kbps as a single time slot
 IS-136 added a number of features to the original IS-54 specification to
improved compression protocol.
 It takes up to 30 sec for connection to the network
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31. HSCSD – High Speed Circuit Switched Data
 Enhancement to Circuit Switched Data (CSD)
 Full allocated bandwidth of the connection is available
 Use multiple time slots to increase data throughput
 Quality of the radio link archived data rate 14.4Kbps
 Achieved speed up to 57.6Kbps
 Charged by period of time, just a short time, now dead !
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32. GPRS- General Packet Radio Service
 It use packet-switched instead of circuit-switched (CSD or HSCSD)
 In theory, GPRS data transfer speeds can reach up to 115.2kbps
 Practical high speeds: typically 32 - 48 kbps
 Use the same TDMA Frame, modulation, channel coding and time slot
structure like GSM (GMSK)
 It is considered as ”2.5G”, between the 2nd and 3rd generation
 The data rate can achieved up to 171.2 kbps
 New network elements in Core network (SGSN and GGSN)
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33. GPRS Channel Encoding and Devices Support
Coding Scheme Speed (kbit/s) 8 time-slots
CS-1 9.05 72.4 kb/s
CS-2 13.4 107.2 kb/s
CS-3 15.6 124.8 kb/s
CS-4 21.4 171.2 kb/s
Devices supporting GPRS
Class A The MS is attached to both GSM and GPRS simultaneously
Class B The MS is attached to both but can operate in only one at a time
Class C The MS is attached to GPRS or other GSM services
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34. The multi-slot classes are as follows:
Multi-slot Class Downlink TS Uplink TS Max. Slot
1 1 1 2
2 2 1 3
3 2 2 3
4 3 1 4
5 2 2 4
6 3 2 4
7 3 3 5
8 4 1 5
9 3 2 5
10 4 2 5
11 4 3 5
12 4 4 5
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35. EDGE- Enhance Data for Global Evolution
 Provides data transfer rates significantly than GPRS
 Throughput per timeslot from 8.8kbps–59.2 kbps
 Data Rate achieved up to 474kbps
 EDGE… almost 3G as part of Release 7
 It meets the requirements for a 3G network but is usually classified as
2.75G.
 EDGE supported 384kbps theoretically (The delay of delivery of
3G/UMTS network)
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36. GSM EDGE evolution specification overview
PARAMETER DETAILS
Multiple Access Technology FDMA / TDMA
Duplex Technique FDD
Channel Spacing 200 kHz
Modulation GMSK, 8PSK
Slots per channel 8
Frame duration 4.615 ms
Overall symbol rate 270 k symbols / s
Radio data rate per time slot 69.2 kbps
Max user data rate per time slot 59.2 kbps (MCS-9)
Max user data rate when using 8 time slots 473.6 kbps **
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37. UMTS/3G
 First commercial deployments in 2002
 UMTS is a component of the International Telecommunications
Union IMT-2000 standard set
 RF channel bandwidth5 MHz
 High data rates expected:
 2 Mbps for indoor
 384 kbps for pedestrians
 144 kbps for vehicles
 Used wideband CDMA, time division CDMA
 The radio access specifications provide: FDD and TDD
 It supports Circuit and Packet Service
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38. GSM Development Evolution
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39. HSPA - High Speed Packet Access
 Extends and improves the performance of existing 3rd generation
mobile telecommunication networks
 Release 5 and Release 6 is commercially deployed.
 Adaptive modulation: : QPSK, 16-QAM and 64-QAM
 WCDMA Technology
 The theoretical data rate:
 HSDPA : Release 5 “E-DL” - 14.4 Mbps
 HSUPA : Release 6 “E-UL”- 5.76Mbps
Note:
About HSPA will held with next session training or​ self-study
through the attached handout !
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40. Acronyms and Terms
 FDMA : Frequency Division Multiple Access
 TDMA : Times Division Multiple Access
 CSD : Circuit Switched Data
 HSCSD : High Speed Circuit Switched Data
 GPRS : General Packet Radio Service
 EDGE : Enhance Data for Global Evolution
 UMTS : Universal Mobile Telecommunications System
 WCDMA : Wideband Code Division Multiple Access
 HSPA : High Speed Packet Access
 HSDPA : High-Speed Downlink Packet Access
 HSUPA : High-Speed Uplink Packet Access
 GGSN : Gateway GPRS Service Node
 SGSN : Serving GPRS Service Node
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41. GSM Frequency Band & Measurement Scale
System Band Uplink (MHz) Downlink (MHz) Channel number
T-GSM-380 380 380.2–389.8 390.2–399.8 dynamic
T-GSM-410 410 410.2–419.8 420.2–429.8 dynamic
GSM-450 450 450.6–457.6 460.6–467.6 259–293
GSM-480 480 479.0–486.0 489.0–496.0 306–340
GSM-710 710 698.2–716.2 728.2–746.2 dynamic
GSM-750 750 747.2–762.2 777.2–792.2 438–511
T-GSM-810 810 806.2–821.2 851.2–866.2 dynamic
GSM-850 850 824.2–849.2 869.2–894.2 128–251
P-GSM-900 900 890.0–915.0 935.0–960.0 1–124
E-GSM-900 900 880.0–915.0 925.0–960.0 975–1023, 0-124
R-GSM-900 900 876.0–915.0 921.0–960.0 955–1023, 0-124
T-GSM-900 900 870.4–876.0 915.4–921.0 dynamic
DCS-1800 1800 1,710.2–1,784.8 1,805.2–1,879.8 512–885
PCS-1900 1900 1,850.2–1,909.8 1,930.2–1,989.8 512–810
Tims Scale Capacity Scale Speed Scale
1h = 60min 1 TBite = 1000 GBite 1 Gbps = 1000 Mbps
1min = 60s 1 GBite = 1000 MBite 1 Mbps = 1000 Kbps
1s = 1000 ms 1 MBite = 1000 KBite 1 kbps = 1000 bps
1ms = 1000 us 1 KBite = 1000 Bite
1us = 1000 ns 1 Bite = 8 bit
1ns = 1000 ps
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42. Thanks
Q&A
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