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Transcript of 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
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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).
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Concept of TDMA and FDMA used in GSMalong with SDMA using cellular structure
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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.
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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".
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“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.
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- 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
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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.
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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.
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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.
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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.
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Hierarchy of Logical channels
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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.
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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
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TDMA frames with common anddedicated channels
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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.
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Relationship of All Time Segments
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Control Channel Multiframe
Control Channel Multiframecomposed of 51 TDMA framesduration = 235.4 ms
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Traffic Channel Multiframecomposed of 26 TDMA frames
ura on = ms
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Traffic Channel and Control Channel Multiframes
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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.
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Hyperframe
.
duration = 3h 28m 53s 76ms (12,533.76seconds) consists of 2,715,548 TDMA frames
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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
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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:
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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
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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
.
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,
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
.
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,
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.
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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)
.
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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
.
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,
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.
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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
.
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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.
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Common cont ol channels
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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
“ ” .
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1. Paging Channel (PCH)
2. Random Access Channel (RACH)
3. Access Grant Channel (AGCH)
4. Cell Broadcast Channel CBCH
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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).
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Random Access Channel
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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
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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.
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Cell Broadcast Channel
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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
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c ve s mus requen y mon or
both BCCH and CCCH. The CCCH will
the BCCH.
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Dedicated control channels
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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.
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Dedicated control channels
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Dedicated control channels
(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.
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Stand-alone Dedicated
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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
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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
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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
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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
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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)
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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
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69
1 Hyper frame = 2048 Super frames =2715648 TDMA frames (3h 28 min 53 sec 760 ms
0 1 2 3 2045 2046 2047
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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)
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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.
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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.
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Initiation of a call
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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.
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,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
.
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Land to Mobile Sequence
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Call completion from the called side
Mobility Management Messages
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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
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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
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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
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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
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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
AUTHENTICATION REQUEST
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
Category LogicalChannel
Call Deliver to MH
FCCHCarrier sine waveSYNC CHANNEL INFORMATION
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RRM
RRM
RRM
FCCHSCH
BCCH
Carrier sine waveSYNC CHANNEL INFORMATION
SYSTEM INFORMATION
PAGING REQUEST
RRM
RRM
RRMMM
RACH
AGCH
SDCCHSDCCH
CHANNEL REQUEST
IMMEDIATE ASSIGNMENT
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
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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
AUTHENTICATION REQUEST
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
Category LogicalChannel
Call Deliver to MH
FCCHCarrier sine waveSYNC CHANNEL INFORMATION
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RRM
RRM
RRM
FCCHSCH
BCCH
Carrier sine waveSYNC CHANNEL INFORMATION
SYSTEM INFORMATION
PAGING REQUEST
RRM
RRM
RRMMM
RACH
AGCH
SDCCHSDCCH
CHANNEL REQUEST
IMMEDIATE ASSIGNMENT
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
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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
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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
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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)
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By: Mrs. Shweta Shah
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•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.
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• It com rise all the connections between the GSMsystem entities, while the Um, or air – interface isnot included since it belongs to radio interface
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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.