5. ch-4 gsm channels_and interfaces lecture

8/9/2019 5. Ch-4 GSM Channels_and Interfaces Lecture

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GSM

lobal System for Mobileslobal System for Mobiles

M HANNEL

By: Mrs. Shweta Shah

1



Multiple access schemes WithGSM

The radio transmission in GSM networksis based on digital technology. Digital

using two methods known as Frequency

Time Division Multiple Access(TDMA).



Concept of TDMA and FDMA used in GSMalong with SDMA using cellular structure



r u y v u(FDMA) refers to the fact that each

different radio frequency channels.

Mobile phones in adjacent cells (or inthe same cell) can operate at the sametime, but are separated according to

requency.



Time Division Multiple Access (TDMA) divides

periods of time, each one called a "TDMA frame".

Each TDMA frame contains ei ht shorter eriods of

time known as "timeslots".



“timeslots”. The timeslots are arranged insequence and are conventionally numbered 0

.a “TDMA frame”.

The information carried in one timeslot is calleda urs .

Each MS telephone call occupies one timeslot(0–7) within the frame until the call is

terminated, or a handover occurs. For such a system to work correctly,

correctly.



- ca cu a ons: –

-Reverse link (Mobile to BS)- 915 MHz – 890 MHz = 25 MHz

-Total number of channels =

- ARFCN = 0 to 124

125kHz200 bandwidthchannelPer

==

-Per channel 8 time slots assigned and

-channel data rate is 270.833 kbps

- . .-In GSM with overhead user data is actually sent at 24.7 kbps

instead of 33.854 kbps

- gna ng ura on = . = . µs

8



Transmission through air interface

an example of an army which has to moved fromone place to another and a group of vehicles is setaside to do the ob.

Each vehicle has eight seats and therefore onlyofficer and seven soldiers are allocated to eachvehicle.

There are different types of people in army,soldiers and officers. This could be referred to as “lo ical” differences as their functions aredifferent.



another, a “physical” connection isemployed, that is, the vehicle and seats.

The physical channel is the medium over

which the information is carried, in thecase o a erres r a n er ace s woube a cable.

information carried over the physicalchannel.



Physical and Logical Channels

The TDMA frame can be com ared to the vehicle in ourexample.

Each TDMA frame contains eight shorter periods of timenown as t mes ots . T ese times ots can e compare

to the seats in the vehicle.

e mes o s are ca e p ys ca c anne s , asthey are used to physically move information from oneplace to another.

The radio carrier signal between the mobile station andthe BTS is divided into a continuous stream of timeslots,which in turn are transmitted in a continuous stream of TDMA frames - like a long line of vehicles with eight seats

in each.



The contents of the physical channels - that is, the

soldiers and officers traveling in the eight seats of theve c e, accor ng to t e r ro es, are ca e og cachannels".

or suc a sys em o wor correc y, e m ng o e

transmissions to and from the mobiles is critical. The MSor Base Station must transmit the information related toone call at exactl the ri ht moment or the timeslot willbe missed. The information carried in one timeslot iscalled a “burst”.

In t e examp e o t e army, t e so iers are one type ological channel and the officers are other types of logicalchannels, and they exercise some kind of control

. ,channels can be divided into two types: dedicated channels common channels.



Hierarchy of Logical channels



Logical channels

mapped into physical channels in the radio path.

Logical channels comprise of common channels anddedicated channels.

Common channels are those that are used forbroadcasting different information to MS and for setting upsignalling channels between the MSC/VLR and the mobiles a on.

Over the radio path, different types of signalling channels areused between the MS and the BTS, BSC and the MSC/VLR.

All these signalling channels are called dedicated controlchannels.

Traffic channels are also dedicated channels, as eachchannel is dedicated to only one user to carry speech ordata.



LOGICAL CHANNELS

TRAFFIC SIGNALLING

FULL RATEBm 22.8 Kb/S

HALF RATELm 11.4 Kb/S

BROADCAST COMMON CONTROL DEDICATED CONTROL

FCCH SCH BCCH

PCHRACH

AGCH

FCCH -- FREQUENCY CORRECTION CHANNEL

SDCCH SACCH FACCH

SCH -- SYNCHRONISATION CHANNELBCCH -- BROADCAST CONTROL CHANNEL

PCH -- PAGING CHANNEL

RACH -- RANDOM ACCESS CHANNEL

AGCH -- ACCESS GRANTED CHANNEL

SDCCH -- STAND ALONE DEDICATED CONTROL CHANNEL

SACCH -- SLOW ASSOCIATED CONTROL CHANNEL

FACCH -- FAST ASSOCIATED CONTROL CHANNEL

DOWN LINK ONLY

UPLINK ONLY

BOTH UP &

DOWNLINKS



TDMA frames with common anddedicated channels



depending on whether they are common channels used byseveral MS (blue above) or if they are dedicated to a certainMS in connection with a call (yellow above).

The common and dedicated channels are grouped in differentmultiframes.

The common channels are grouped in a 51 TDMA frameorder, and

e e ca e c anne s are groupe n a rameorder. By multiplying 51 with 26, we can conclude that any TDMA

frame number will occur simultaneously in both multiframesevery 1326 TDMA frames (which corresponds to 6.12seconds). Such cycles are called superframes.



19



20



21

Relationship of All Time Segments



Control Channel Multiframe

Control Channel Multiframecomposed of 51 TDMA framesduration = 235.4 ms

22



Traffic Channel Multiframecomposed of 26 TDMA frames

ura on = ms

23



Traffic Channel and Control Channel Multiframes

24



Superframe

A Superframe is composed of multiple Multiframes.

Again, there is a superframe for Control Channels and one forTraffic Channels.

Control Channel Superframecomposed of 26 Control Channel (CCH) multiframes (each CCHmultiframe has 51 TDMA frames)

urat on = . secon s

Traffic Channel Su erframe composed of 51 Traffic Channel (TCH) multiframes (each TCH)multiframe has 26 TDMA frames)duration = 6.12 seconds

Each superframe, whether it is a CCH or TCH frame, consists of1326 TDMA frames (51 * 26)*Note: The CCH and TCH frame se uences will s nchronizeevery superframe.

25



Hyperframe

.

duration = 3h 28m 53s 76ms (12,533.76seconds) consists of 2,715,548 TDMA frames

26



GSM burst

,

functions. Some GSM bursts are used for carrying data while others

.

As a result of this a number of different types of GSM

burst are defined.

Normal burst u p l i n k a n d d o w n l i n k

Frequency correction burst d o w n l i n k

Random Access (Shortened Burst)u p l i n k

27



28



GSM normal burst

communications between the base stationand the mobile, and typically transfers thedigitised voice data.

The structure of the normal GSM burst is.

It contains data that provides a number of different functions:

29



3 t a i l b i t s : These tail bits at the start of the GSM burst givetime for the transmitter to ramp up its power

5 7 d a t a b i t s : used to carry information (contains thedigitised voice data) although on occasions it may be

replaced with signalling information in the form of the FastAssociated Control CHannel (FACCH). The type of data is indicated by the flag that follows the data field

1 b i t f l a g : This bit within the GSM burst indicates the type

of data in the previous field. 2 6 b i t s t r a i n i n g se q u e n ce : used as a timing reference and

for equalisation. There is a total of eight different bit sequences that may be used, each

.

The same sequence is used in each GSM slot, but nearby base stationsusing the same radio frequency channels will use different ones, andthis enables the mobile to differentiate between the various cells using

e same requency.

30



the data field. 5 7 d a t a b i t s Again, this block of data within the GSM

.

3 t a i l b i t s These final bits within the GSM burst are used

to enable the transmitter power to ramp down. They are, .

8 .2 5 b i t s g u a r d t im e At the end of the GSM burst thereis a guard period. This is introduced to prevent

.

As a result of their differing distances from the basestation.

31



GSM synchronisation burst

synchronisation for the mobiles on the network.

3 t a i l b i t s : Again, these tail bits at the start of the GSM burstgive time for the transmitter to ramp up its power

3 9 b i t s o f i n f o r m a t i o n :

6 4 b i t s o f a Lo n g T r a i n i n g Se q u e n ce :

3 9 b i t s I n f o r m a t i o n :

3 t a i l b i t s Again these are to enable the transmitter power toramp down.

8 .2 5 b i t s g u a r d t im e : to act as a guard interval.

32



GSM frequency correction

burst

,

burst essentially consists of a constant frequency carrierwith no phase alteration.

,burst give time for the transmitter to ramp up its power.

1 4 2 b i t s a l l s e t t o z e r o :

a s ga n ese are o ena e e ransm erpower to ramp down.

8 .2 5 b i t s g u a r d t im e : to act as a guard interval.

33



GSM random access burst

the network and it is shortened in terms of thedata carried, having a much longer guardperiod.

This GSM burst structure is used to ensure that

timing problems that may exist.

Once the mobile has accessed the network and

timing has been aligned, then there is norequirement for the long guard period.

34



to provide additional margin when accessing thenetwork.

3 6 d a t a b i t s :

3 t a i l b i t s Again these are to enable the transmitterpower o ramp own.

6 9 .2 5 b i t s g u a r d t im e : The additional guard time,filling the remaining time of the GSM burst provides forarge m ng erences.

35



and an SB (Stealing Bit). The trainin se uence is known which makes

it possible to correct bit errors by applyingViterbi Equalisation.

r r r u r ,and the one to be used is determined at thetime of call set-up. The stealing bits indicate if

the burst contains FACCH (handover)information.

36



Traffic Channels (TCH)

.

The different types of traffic channel are listed below:Full rate

TCH/FS: Speech (13 kbit/s net, 22.8 kbit/s gross)

TCH/EFR: Speech (12.2 kbit/s net, 22.8 kbit/s gross)

TCH/F9.6: 9.6 kbit/s – dataTCH/F4.8: 4.8 kbit/s – data

TCH/F2.4 2.4 kbit/s – data

Half rate

TCH/HS: speech (6.5 kbit/s net, 11.4 kbit/s gross)TCH/H4.8 4.8 kbit/s – data

TCH/H2.4 2.4 kbit/s – data

37



38



TCH Full Rate/Half Rate

ser a a s con a ne w n one

per frame

a a e : amp e a a ra e athan Full Rate,Mapped onto the same

frames

, . , . ,2.4

peec c anne g ze

After channel coding 22.8 KBPS



Traffic Channel (TCH)

speech or data, which can be either in the form of half rate traffic (5.6 Kbits/s) or full rate traffic (13.

Enhanced Full Rate (EFR) traffic channel.

The speech coding in EFR is still done at 13 Kbits/s, butthe coding mechanism is different than that used fornormal full rate traffic.

EFR codin ives better s eech ualit at the same bit

rate than normal full rate. Traffic channels can transmit both speech and data and

.

40



,

frequency is shared by, at the most, eight users. Consider the example of a 2 Mbit/s PCM signal that

can carry 30 speech channels, with each channeloccupying 64 Kbits/s.

The s eech si nals from the mobile stations must beplaced into a 2 Mbit/s signal that connects the BTSand the BSC.

same cell send the digital information at the correcttime to enable the BTS to place this information into

.

41



,

interval of approximately 576.9 µs (~ 0.577 ms),which corresponds to the duration of 156.25 bit.

All bursts occupy this period of time, but the actual

arrangement of bits in the burst depends on theburst type.

42



43



44



45



Broadcast group

,only one TX that can carry common channels.

They are downlink point-to-multipoint channels.

network and the broadcasting cell.

There are three types of broadcast channels:

1. Broadcast Control Channel (BCCH)

2. Frequency Correction Channel (FCCH)

.



Broadcast Control Channel

(BCCH)

,

the network, e.g. for describing the current control channelstructure.

The surrounding cells.

It is transmitted continuously as its signal strength is.

The information carried on the BCCH is monitored by theMS periodically (at least every 30 secs), when it is

.

The BCCH is a point-to-multipoint channel (BS-to-MS). It also broadcasts a list of channels that are currently in

.



,

and its signal strength is measured by all MS which mayseek to use it. “Dummy” bursts are transmitted to ensure.

Broadcast Control Channel (BCCH) – Carries the followinginformation:

. .

2. List of neighboring cells which should be monitored by the MS.

3. List of frequencies used in the cell.

. .

5. Power control indicator.6. DTX permitted.

. , , .

8. CBCH description.



Frequency Correction Channel

(FCCH)

allows the mobile to synchronize its own frequency to

that of the transmitting base site.

The FCCH may only be sent during timeslot 0 on theBCCH carrier frequency and therefore it acts as a flag to

the mobile to identify Timeslot 0.

The MS scans for this signal after it has been switchedon, since it has no information as to which frequency to

.



Synchronisation Channel (SCH)

synchronize to the TDMA frame structure and know the timing

of the individual timeslots. The following parameters are sent:– Frame number.

– Base Site Identity Code (BSIC).

The BSIC is needed to identif that the fre uencstrength being measured by the mobile station is comingfrom a particular base station.

and store the information from the best six cells. The SCHinformation on these cells is also stored so that the MS mayuickl res nchronize when it enters a new cell.



51

Common cont ol channels



Common control channels

(CCCH) group

logical channels.

They are used to set up a point to point connection.

e s are o wo ma n ypes: The f o r w a r d common channels are used for paging to inform a

mobile of an incoming call, responding to channel requests, and

broadcasting bulletin board information. The r e t u r n common channel is a random access channel used

by the mobile to request channel resources before timing informationis conveyed by the BSs.

control information between all mobiles and the BTS. Thisis necessary for the implementation of “call origination” and

“ ” .

52



1. Paging Channel (PCH)

2. Random Access Channel (RACH)

3. Access Grant Channel (AGCH)

4. Cell Broadcast Channel CBCH

53



Paging Channel (PCH)

broadcast by all the BTSs of a location area in the case of a mobile terminated call.

The PCH transmits IMSI of the target subscriberwhich is with a request for acknowledgement form the

mobile on RACH. used for “cell broadcast” (ASCII text messages to all

MSs in form of SMS)

,

performed by an IMSI, TMSI or IMEI).

54

Random Access Channel



Random Access Channel

(RACH)

the common control channels. It is used by the mobile station in order to initiate

a transaction, or as a response to a PCH.

RACH is used by MSs to gain access to the system.

,response to call announcement, locationupdate, etc.

It is used by subscriber unit to acknowledge apage form the PCH and also to originate a call

55



Access Grant Channel (AGCH)

.

It is used to assign a mobile Stand-alone DedicatedControl Channel (SDCCH).

It is a downlink, point to point channel.

It is the final CCCH message sent by the BS before a

move to the dedicated channel in order to proceed witheither a call setup, response to a paging message,

.

The PCH and AGCH are never used at the same time.

56

Cell Broadcast Channel



Cell Broadcast Channel

(CBCH)

s c anne s use o ransm

messages to be broadcast to all MSs.

T e B H uses a e cate controchannel to send its messages,

w v r rchannel because the messages can be

.57



c ve s mus requen y mon or

both BCCH and CCCH. The CCCH will

the BCCH.

58



59

Dedicated control channels




(DCCH)

those used for signaling, and

The signaling channels are used for

maintenance of the call and for enabling call set up,

providing facilities such as handover when the call is inprogress, and finally terminating the call.

The traffic channels handle the actual payload.

60





(DCCH)

logical channels.

The dedicated channels are:

1. Stand Alone Dedicated Control Channel(SDCCH)

1. Slow Associated Control Channel (SACCH)

2. Fast Associated Control Channel (FACCH)

ey are use or ca se -up, sen ng measuremen

reports and handover.

They are all bi-directional and point to point channels.

61

Stand-alone Dedicated



Stand alone Dedicated

Control Channel (SDCCH), . . ,

registration / location updates.

The SDCCH carries signaling data following the connection

issued by the BS.

It ensures that the mobile and BS remain connected while the

allocates resources for the mobile.

It can be considered as an intermediate temporary.

It holds the traffic while waiting for the base station toallocate a TCH channel. The SDCCH is used to send

.

62

Slow Associated Control



Slow Associated Control

Channel (SACCH).

It transmits measurement reports and is also used forpower control, time alignment and in some cases for

.

On the forward link, SACCH is used to send slow butregularly changing control information to the mobile e.g.

,instructions for each user on the ARFCN.

On the reverse link, SACCH carries information about the

the BCH measurement resulting from neighboring cells. TheSACCH is transmitted in 13th frame (also in 26th frame when

channel multiframe.63

Fast Associated Control



Fast Associated Control

Channel (FACCH)

.

FACCH ‘‘steals” the TCH burst and inserts its owninformation.

The FACCH is used to carry out userauthentication, handovers and immediate

.

64

Power On Scan Channels,

monitor RF levels

Select the channel with

highest RF level among

the control channels



the control channels

Scan the channel for the

FCCH

YES

Is

FCCH detected?

e ec e c anne w

next highest Rf level from

the control list.

NO

Scan channel for SCH

Is

YES etecte

Read data from BCCH

and determine is it BCCH?

NO

YES

Is

the current BCCH

channel included?

From the channel data

update the control channel

list

Camp on BCCH and

start decoding

Example: Incoming Call Setup



MS ↓ BSS MSC ------ Pa in re uest PCH

MS ↑ BSS/MSC------ Channel request (RACH)

MS ↓ BSS/MSC ------ Immediate Assignment (AGCH)MS ↑ BSS/MSC ------ Paging Response (SDCCH)

MS ↓ BSS/MSC ------ Authentication Request (SDCCH)

MS ↑ BSS/MSC ------ Authentication Response (SDCCH)

MS ↓ BSS/MSC ------ Cipher Mode Command (SDCCH)

------ p er o e omp .

MS ↓ BSS/MSC ------ Setup (SDCCH)

MS ↑ BSS/MSC ------ Call Confirmation (SDCCH)

------

MS ↑ BSS/MSC ------ Assignment Compl. (FACCH)MS ↑ BSS/MSC ------ Alert (FACCH)

MS ↑ BSS MSC ------ Connect FACCH

MS ↓ BSS/MSC ------ Connect Acknowledge (FACCH)

MS ⌦BSS/MSC ------ Data (TCH)



Channel combinations

into what are called channel combinations.

Full Rate Traffic Channel Combination – TCH/FACCH +

Broadcast Channel Combination – BCCH + CCCH Dedicated Channel Combination – SDCCH + SACCH

BCCH+CCCH+SDCCH+SACCH



69

1 Hyper frame = 2048 Super frames =2715648 TDMA frames (3h 28 min 53 sec 760 ms

0 1 2 3 2045 2046 2047



1 Super frame = 1326 TDMA frames (6.12s

= 51(26 frames) Multi frame

50

30 1 2 23 24 25

1 Super frame = 1326 TDMA frames (6.12s)

= 26(51 frames) Multi frame

1(26 frames) Multi frame = 26 TDMA frames (120 ms 1(51 frames) Multi frame = 51 TDMA frames (3060/13 ms)

49 50T0 T1 I 1 2T2 3T12

(SACCH)T23 0

1 TDMA frame

= 8 time slots (120/26 or 4.615ms)

0 1 2 3 4 5 76

1 time slot = 156.25 bit d uration (15/26 or 0.577 ms)

(1 bit duration = 48/13 or 3.69s)



A practical approach:

phone and receives a call. This simple actof switching on the phone involves the

1. The mobile scans all the radio frequenciesan measures em.

2. It selects the frequency with the best qualityand tunes to it.

3. With the help of a synchronization signal in aTDMA frame, the mobile synchronizes itself to the network.



e sync ron za on n orma on requ re y s process sbroadcast by the network and analyzed by the mobile.

Registration and authentication are the next steps and

1. A point to point connection must be set up. The mobile

connection.

2. The network acknowledges the request and allocates a. .

3. The mobile then moves to the allocated (dedicated)channel for further transactions with the network. Thenext ste s are re istration and authentication.



Initiation of a call



the authentication is successful, calls can be set up.

In the case of a mobile terminated call, the subscriberhas to be paged. This process is like this:

1. The network sends a paging message to all the BTSwithin the Location Area (LA) where the subscriber

.2. The mobile station answers the paging message by

sending a service/channel request.3. The network acknowled es this re uest and a ain an

authentication is needed.4. A dedicated signalling channel is assigned in order to

transmit the data related to the call. A traffic channel.



,signal strength of adjacent carriers and sends

measurement reports to the Base Station ControllerBSC .

A channel must be dedicated also for thisfunction.

This is a sim lified descri tion of the rocess but itconveys the idea that there are many functionsinvolved in the air interface to enable a mobile user tohave conversation.

Each one of these functions requires a separate

"logical channel", as the data contents are different.Some of them are uplink, others are downlink and

.



Land to Mobile Sequence



Call completion from the called side

Mobility Management Messages



Message name Transmitted by

AUTHENTICATION REQUEST

AUTHENTICATION RESPONSE

AUTHENTICATION REJECT

Base

Mobile

Base

IDENTITY RESPONSE

TSMI REALLOCATION COMMAND

LOCATION UPDATING REQUET

Mobile

Base

Mobile

LOCATION UPDATING REJECT

IMSI DETACH REQUEST

CM SERVICE REQUEST

Base

Mobile

Mobile

CM RE-ESTABLISHMENT REQUEST

MM-STATUS

Mo i e

Mobile/Base

Call mana ement messa es



Message name

Starting a call

Transmitted by

EMERGENCY SETUP

CALL PROCEEDING

PROGRESSCALL CONFIRMED

mobile

base

basemobile

ALERTING

CONNECT

mobile/base

mobile/baseDuring a call

START DTMF Mobile

MODIFY

USER INFORMATION

mobile/base

mobile/baseEnding a call

DISCONNECT Mobile/base

RELEASE

RELEASE COMPLET

mobile/base

mobile/base Abnormal conditions

STATUS Mobile/base

CONGESTION CONROL mobile/base

Message name Logical channel Transmitted by

Radio Resources Management Messages

SYNC CHANNEL INFORMATION SCH Base



SYNC CHANNEL INFORMATIONSYSTEM INFORMATION (TYPE 1,2,3,4,5)SYSTEM INFORMATION (TYPE 6)

CHANNEL REQUEST

SCHBCCHSACCH

RACH

BaseBaseBase

Mobile , .

IMMEDIATE ASSIGNMENTIMMEDIATE ASSIGNMENT EXTENDED

IMMEDIATE ASSIGNMENT REJECTASSIGNMENT COMMAND

AGCHAGCH

AGCHFACCH

ase

BaseBase

BaseBase

ADDITIONAL ASSIGNMENT

PAGING RESPONSEMERSUREMENT REPORT

HANDOVER COMMAND

HANDOVER ACCESS

FACCH

SDCCHSACCH

FACCH

TCH

Base

MobileMobile

Base

MobilePHYSICAL INFORMATIONHANDOVER COMPLETE

CIPHERING MODECHANNEL RELEASE

FACCHFACCH

FACCHFACCH

BaseMobile

BaseBase

FREQUENCY REDEFINITION

CLASSMARK CHANGE

SACCH

FACCHSACCHFACCH

Base

Mobile

RR STATUS FACCH

SACCH

aseMobile/base

Message sequence and system operations for registration

of a terminal in a visited service area

Prior Prior Serving Serving Serving



Prior MSC

Prior VLR HLR

ServingVLR

ServingMSC

ServingBase

Registration info

REGISTRATION NOTIFICATION INVOKE

Store info

Change infoREGISTRATION NOTIFICATION INVOKE

remove info

REGISTRATION NOTIFICATION RESULT

REGISTRATION NOTIFICATION RESULT

REGISTRATION CANCELLATION INVOKE

remove info

REGISTRATION CANCELLATION RESULT

REGISTRATION CANCELLATION INVOKEQUALIFICATION REQUEST INVOKE

REGISTRATION CANCELLATION RESULT

QUALIFICATION REQUEST RESULT

PROFILE REQUEST INVOKE

Store info

PROFILE REQUEST RESULT

Location-Updating Procedure



Mobilestation

Basestation

Category LogicalChannel

SYNC CHANNEL INFORMATION

Carrier sine wave

SYSTEM INFORMATION TYPE3RRM

FCCH

SCHBCCH

CHANNEL REQUEST

IMMEDIATE ASSIGNMENT

LOCATION UPDATING REQUEST

RRM

RRM

RACH

AGCH


CIPHERING MODE COMMAND

AUTHENTICATION RESPONSEMM

MM

RRM

SDCCHSDCCH

SDCCHCIPHERING MODE ACK

LOCATION UPDATING ACCEPT

TMSI ALLOCATION COMPLETEMM

MM

RRM SDCCH

SDCCH

SDCCHCHANNEL RELEASE

RRM SDCCH

Mobilestation

Basestation


Call Deliver to MH

FCCHCarrier sine waveSYNC CHANNEL INFORMATION



RRM

RRM

RRM

FCCHSCH

BCCH

Carrier sine waveSYNC CHANNEL INFORMATION

SYSTEM INFORMATION

PAGING REQUEST

RRM

RRM

RRMMM

RACH

AGCH

SDCCHSDCCH

CHANNEL REQUEST


PAGING RESPONSE AUTHENTICATION REQUEST

MM

RRM

RRM

CMCM

SDCCH

SDCCH

SDCCH

SDCCH

CIPHERING MODE

CIPHERING MODE ACK

SETUP

CM

RRM

RRM

SDCCH

SDCCH

SDCCH

ALERTING

CONNECT

ASSIGNMENT COMMAND

ASSIGNMENT ACK

CM

FACCH

TCHTCH

FACCH

CONNECT ACK

conversationconversation

conversation

CM

CM

RRM

FACCH

FACCH

FACCH

RELEASE

RELEASE COMPLETE

CHANNEL RELEASE

Location-Updating Procedure



Mobilestation

Basestation


SYNC CHANNEL INFORMATION

Carrier sine wave

SYSTEM INFORMATION TYPE3RRM

FCCH

SCHBCCH

CHANNEL REQUEST


LOCATION UPDATING REQUEST

RRM

RRM

RACH

AGCH


CIPHERING MODE COMMAND

AUTHENTICATION RESPONSEMM

MM

RRM

SDCCHSDCCH

SDCCHCIPHERING MODE ACK

LOCATION UPDATING ACCEPT

TMSI ALLOCATION COMPLETEMM

MM

RRM SDCCH

SDCCH

SDCCHCHANNEL RELEASE

RRM SDCCH

Mobilestation

Basestation


Call Deliver to MH

FCCHCarrier sine waveSYNC CHANNEL INFORMATION



RRM

RRM

RRM

FCCHSCH

BCCH

Carrier sine waveSYNC CHANNEL INFORMATION

SYSTEM INFORMATION

PAGING REQUEST

RRM

RRM

RRMMM

RACH

AGCH

SDCCHSDCCH

CHANNEL REQUEST


PAGING RESPONSE AUTHENTICATION REQUEST

MM

RRM

RRM

CMCM

SDCCH

SDCCH

SDCCH

SDCCH

CIPHERING MODE

CIPHERING MODE ACK

SETUP

CM

RRM

RRM

SDCCH

SDCCH

SDCCH

ALERTING

CONNECT

ASSIGNMENT COMMAND

ASSIGNMENT ACK

CM

FACCH

TCHTCH

FACCH

CONNECT ACK

conversationconversation

conversation

CM

CM

RRM

FACCH

FACCH

FACCH

RELEASE

RELEASE COMPLETE

CHANNEL RELEASE

Mobile-Assisted Handover

station station

Channel



station station ChannelTCHTCH

conversation

conversation

SACCHTCHTCHTCH

conversation

conversation

conversation

TCHFACCHnew TCHTCH

conversation

HANDOVER COMMAND

HANDOVER ACCESS

HANDOVER ACCESS

TCH

FACCH

HANDOVER ACCESS

PHYSICAL INFORMATION

HANDOVER COMPLETE

conversation

TCH

SACCHTCHTCH

conversa on

MEASUREMENT REPORT

conversation

conversation

SACCHTCH

MEASUREMENT REPORT

conversation

Mobile-Assisted Handover

station station

Channel



station station ChannelTCHTCH

conversation

conversation

SACCHTCHTCHTCH

conversation

conversation

conversation

TCHFACCHnew TCHTCH

conversation

HANDOVER COMMAND

HANDOVER ACCESS

HANDOVER ACCESS

TCH

FACCH

HANDOVER ACCESS

PHYSICAL INFORMATION

HANDOVER COMPLETE

conversation

TCH

SACCHTCHTCH

conversa on

MEASUREMENT REPORT

conversation

conversation

SACCHTCH

MEASUREMENT REPORT

conversation

urs s an rames



urs s an rames0 1 2 3 4 5 6 71 TDMA frame = 8 timeslots

1 timeslot = 156.25 bit durations (15/26 =~ 0.577 ms)

(1 bit duration 48/13 =~ 3.69 micro sec)

GP

8.25

TB

3Encrypted bits 57

flag

1Training sequence 26flag

1Encrypted bits 57TB

3

TB

3Fixed bits 142

GP

8.25

TB

3

Normal Burst (NB)

Frequency correction

burst (FB)

TB: Tail bits

GP: Guard period

GP

8.25

TB

3

TB

3Encrypted bits 39 Synchronization sequence 64 Encrypted bits 39

TB Encr ted bits 36

Synchronization

burst (SB)

3

41

3 .

GP

8.25

TB

3TB

3Mixed bits 58 Training sequence 26 Mixed bits 58

Dummy burst (DB)



By: Mrs. Shweta Shah



•communicate over an interface specified by

the GSM standards.

system operator to adopt systemcomponents from different manufacturers.

• or examp e o oro a equ pmen maybe coupled with a Nokia NSS.

• Each interface within the GSM system has aspeci ie name associate wit it.

• This table illustrates the names of all theinterfaces s ecified b GSM.



• It com rise all the connections between the GSMsystem entities, while the Um, or air – interface isnot included since it belongs to radio interface



s agram s ows e sys em

with the 2Mbps interfaces, which are.

These interfaces carry traffic from the

, ,from an MSC to a BSC and from a

.

These links are also used between the.

5. ch-4 gsm channels_and interfaces lecture

Documents