Presented by : Mr. Che Sokunth

Date : 17.Sept.2012

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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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

Logical Channel

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Logical Channel

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Logical Channel

4

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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I- Broadcast Channel – BCH Logical Channel

Frequency Correction Channel (FCCH)

Synchronization Channel (SCH)

Broadcast Control Channel (BCCH)

Cell Broadcast Channel (CBCH)

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1- Frequency Correction Channel (FCCH) Logical Channel

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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2- Synchronization Channel (SCH) Logical Channel

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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3- Broadcast Control Channel (BCCH) Logical Channel

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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4- CELL BROADCAST CONTROL CHANNEL (CBCH) Logical Channel

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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II. Common Control Channels (CCCH) Logical Channel

Paging Channel (PCH) – Downlink

Random Access Channel (RACH) - Uplink

Access Grant Channel (AGCH) - Downlink

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1. Paging Channel (PCH) Logical Channel

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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2. Random Access Channel (RACH) Logical Channel

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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3. Access Grant Channel (AGCH) Logical Channel

Downlink direction

Initiate Immediate assignment procedure

Network allocates a specific dedicated signaling channel

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III. Dedicated Control Channels (DCCH) Logical Channel

Standalone Dedicated Control Channel (SDCCH)

Fast Associated Control Channel (FACCH)

Slow Associated Control Channel (SACCH)

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1. Standalone Dedicated Control Channel (SDCCH) Logical Channel

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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2. Slow Associated Control Channel (SACCH) Logical Channel

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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3. Fast Associated Control Channel (FACCH) Logical Channel

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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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

Physical Channel

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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

Physical Channel

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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.

Physical Channel

TDMA Bust

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Frequency Correction Burst (FB)

Frequency synchronization

The same guard time as a normal bit (8.25 bits)

Broadcasting on the logical channel FCCH.

Physical Channel

TDMA Bust

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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).

Physical Channel

TDMA Bust

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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

Physical Channel

TDMA Bust

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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

Physical Channel

TDMA Frame

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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)

Physical Channel

TDMA Frame

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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

Physical Channel

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GSM Frame Structure Summary

Physical Channel

TDMA Frame

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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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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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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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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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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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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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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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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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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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GSM Development Evolution

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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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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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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

GSM Frequency Band & Measurement Scale

41

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

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Thanks

Q & A

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