SlideShare une entreprise Scribd logo
1  sur  46
NU TEK India Limited
NU TEK (I) LIMITED
1505-06, 15th
Floor,
Global Business Park, Tower – D,
M.G. Road, GURGAON, INDIA
TEL NO. 0124- 4171600
FAX NO. 0124-4011275
NU TEK India Limited
CHANNELS
NU TEK India Limited
NU TEK India Limited
NU TEK India Limited
NU TEK India Limited
Channels in GSM Air interface
 Logical Channels : ARFCN –x, Timeslot – y,
Frame Number - N
Logical Channels
Control Channels Traffic Channels
NU TEK India Limited
Logical channel
 One or more logical channel can be
transmitted on a physical channel.
Different types of logical channel are –
 Traffic Channels (Speech & Data)
 Broad cast channel (Signalling)
 Common control channel (Signalling)
 Dedicated control channel (Signalling)
NU TEK India Limited
NU TEK India Limited
NU TEK India Limited
TRAFFIC CHANNEL
NU TEK India Limited
Traffic Channels
Traffic Channels
TCH - F
TCH - H
NU TEK India Limited
NU TEK India Limited
 Traffic Channel carries the voice data
 Two blocks of 57 bits contain voice data
 One TCH is allocated for every active call. While call
is in progress if there is degradation in quality of
current channel, BTS may shift the communication
to another TCH on a different Carrier and/or
Timeslot
 A full rate TCH carries 13 kbps voice data, and Half
rate TCH carries a 6.5 kbps voice data
NU TEK India Limited
NU TEK India Limited
Traffic Channels (TCH)
One physical channel (1 timeslot) can support:
Traffic channels are used to send Speech or Data
services.
1 TCH/F or 2 TCH/H
• TCH/F: 13 kb/s voice or 9.6 kb/s data (22.8 Kbps after channel
coding)
• TCH/H: 6.5 kb/s voice or 4.8 kb/s data (11.4 kbps after channel
coding)
Both can be used to carry signalling information.
Uplink / Downlink Synchronisation
The MS transmit burst is delayed by 3 timeslots after
the BTS burst.. This delay allows enables: Use of the
same UL and DL timeslot number in TDMA frame
Avoids simultaneous Tx/Rx requirement
NU TEK India Limited
NU TEK India Limited
Speech channels are supported by two different
methods of coding known as Full Rate (FR) and
Enhanced Full Rate (EFR). Enhanced Full Rate
coding provides a speech service that has
improved voice quality from the original
Full Rate speech coding, whilst using the same air
interface bandwidth. EFR employs a new speech
coding algorithm and additions to the full rate
channel coding algorithm to accomplish this
improved speech service,
NU TEK India Limited
NU TEK India Limited
CONTROL CHANNEL
NU TEK India Limited
Channels in GSM Air interface
 Logical Channels : ARFCN –x, Timeslot – y,
Frame Number - N
Logical Channels
Control Channels Traffic Channels
NU TEK India Limited
Concepts of Channels in GSM
 A company vehicle is used for several purposes in
a day
 Similarly in GSM, the timeslots are used for
different purposes at different times
NU TEK India Limited
These control channels are used by the MS to
establish communication with
the network in the idle mode and also in initiating
calls to enter the dedicated
mode. Timeslot 0 is grouped into structures of 51
frames referred to as
Control Channel Multiframes
The control channels are grouped as Broadcast
Control Channels (BCCH) Common Control
Channels (CCCH) and Dedicated
Control Channel (DCCH).
NU TEK India Limited
Broadcast Channels
(BCCH)
NU TEK India Limited
NU TEK India Limited
BCH (Broadcast Channel)
 One ARFCN, On all the time, in every cell
 Uses Timeslot 0 on a channel, in Downlink
 FCH – Frequency correction channel (allows mobile to
tune to BTS frequency. This channel carries a 142 bit zero
sequence and repeats once in every 10 frames on BCH)
 SCH – Synchronization channel (carries the Frame
number and BSIC). A midamble of 64 bit helps mobiles to
synchronize. It also repeats once in 10 Frames
NU TEK India Limited
 BCCH – Broadcast Control Channel. It has
information encoded on it which identifies the
network (LAC). It also carries list of the
channels in use in the cell (CA tables)
BCH (Broadcast Channel)
NU TEK India Limited
The Broadcast Control Channel is transmitted by the BTS at all times. The RF carrier
used to transmit the BCCH is referred to as the BCCH carrier. The information carried
on the BCCH is monitored by the MS periodically (at least every 30 secs), when it is
switched on and not in a call.
Each cell has one carrier designated as a BCH carrier. The BCH carrier has all 8 timeslots
continuously on, either with traffic or dummy bursts. Timeslot 0 of the BCH carrier
contains logical control channels.
Broadcast Control Channel (BCCH) – Carries the following information (this is only a
partial list):
 Location Area Identity (LAI).
 List of neighbouring cells which should be monitored by the MS.
 List of frequencies used in the cell.
 Cell identity.
 Power control indicator.
 DTX permitted.
 Access control (for example, emergency calls, call barring).
NU TEK India Limited
NU TEK India Limited
Information distributed over Broadcast channel helps the MS to orient themselves
in the mobile radio N/W .BCH channels are all downlink Pt. to Multi pt. and are
allocated to timeslot zero.
FCCH: Frequency correction channel
This is transmitted frequently on the BCCH timeslot and 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 the BCCH carrier frequency and therefore it acts
as a flag to the mobile to identify Timeslot 0.
SCH: (Synchronisation channel )
The SCH carries the information to enable the MS to 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 MS will monitor BCCH information from surrounding cells and store the
information from the best six cells. The SCH information on these cells is also
stored so that the MS may quickly resynchronize when it enters a new cell.
NU TEK India Limited
Common Control Channels
(CCCH)
NU TEK India Limited
NU TEK India Limited
Common Control Channel
 CCCH shares Timeslot 0 with BCH on a
Multiframe
 CCCH consists of PCH, RACH and AGCH
 PCH – Paging channel is used to alert mobiles on
incoming calls. PCH carries IMSI to page for
Mobiles in the cell. PCH is Downlink channel.
 RACH – Random Access Channel is a short burst
sent by mobile to BTS, to initiate a call request.
RACH uses timeslot 0 on reverse BCH channel on
uplink
NU TEK India Limited
Common Control Channels (CCCH)
CCCH contains all point to multi-point downlink channels (BTS to
several MSs) and the uplink Random Access Channel:
RACH: (UL) Random Access Channel is sent by the MS to request a
resources from the network e.g. an SDCCH channel for call setup.
• AGCH (DL) Access Grant Channel is used to allocate a dedicated
channel (SDCCH) to the mobile.
• PCH (DL) Paging Channel sends paging signal to inform mobile of a call.
Active MSs must frequently monitor both BCCH and CCCH. The CCCH will be
transmitted on the RF carrier with the BCCH.
NU TEK India Limited
NU TEK India Limited
NU TEK India Limited
Dedicated Control Channels (DCCH)
DCCH comprise the following bi-directional (uplink / downlink) point to
point control channels .Used for signalling between MS & BTS:
• SDCCH: Standalone Dedicated control Channel is used for call set
up, location updating and also SMS.It carries all signalling B/W BTS
& MS when no TCH is allocated. Which supports the transfer of Data to
and from the MS during call setup and validation.
Summary—Used for services request, SMS,Location update ,subscriber
Authentication,Equipment validation. (Afterwards TCH Comes into
picture)
• SACCH: Slow Associated Control Channel is used for link
measurements and signalling during a call .Used for non urgent
procedures.
Summary—transmission of Signalling Data ,Radio Link Supervision
measurement ,Transmit power control & Timing advance data
NU TEK India Limited
FACCH
• FACCH: Fast Associated Control CHannel is used
(when needed) for signalling during a call, mainly
for delivering handover messages and for
acknowledgement when a TCH is assigned.Used
mainly during handovers when SACCH Signalling
is not fast enough.FACCH data is transmitted over
TCH, this is marked by Flag called “Stealling Flag”
NU TEK India Limited
RACH – Random Access Channel
8
start
bits
41
Synchronization
bits
36
Encrypted
bits
3
stop
bits
68.25
Extended
Guard Period
88 bits
 Used by mobile to get attention from Base Station
 Several mobiles might originate RACH simultaneously
 Mobile doesn’t know path delay
 So RACH has to be a special short burst
 Mobile sends normal burst after getting timing advance on
downlink SACCH
NU TEK India Limited
DCCH – Dedicated Control Channels
 SDCCH – Standalone Dedicated Common Control
Channel. It is used as a interim channel before final
assignment of TCH. SDCCH is used for signaling and
Authentication message transfers.
It can be called the stepping stone between BSC and TCH
The SDCCH, by using less of the cells resource of
physical channels, improves efficiency, and provides a
useful holding channel for the mobile until speech data
needs to be exchanged.
NU TEK India Limited
Dedicated Control Channels (cont..)
 FACCH – Fast Associated Control Channel
Interrupts TCH on uplink and downlink
Rapid message exchange for handovers
Control bits on either side of midamble – 0 indicates
TCH and 1 indicates FACCH
Both ways – uplink and downlink
NU TEK India Limited
SACCH – Slow associated Control
Channel
 Downlink (BTS – MS)
 Mobile Tx Power Commands
 Mobile Timing Advance
 Cell’s Channel Configuration
 Uplink (MS - BTS)
 Received signal quality report (RXQual)
 Received signal level report (RXLev)
 Adjacent BCH power measurement
NU TEK India Limited
NU TEK India Limited
NU TEK India Limited
Dedicated Control Channels (DCCH)
The DCCH is a single timeslot on an RF carrier which is used to
convey eight
Stand-alone Dedicated Control Channels (SDCCH). A SDCCH is
used by a single MS for call setup, authentication, location
updating and SMS point to point.
As we will see later, SDCCH can also be found on a BCCH/CCCH
timeslot, this configuration only allows four SDCCHs.
Associated Control Channels (ACCH)
These channels can be associated with either an SDCCH or a
TCH. They are used for carrying information associated with the
process being carried out on either the SDCCH or the TCH.
NU TEK India Limited
CONTINUE
Slow Associated Control Channel (SACCH)
Conveys power control and timing information in the downlink direction
(towards the MS) and Receive Signal Strength Indicator (RSSI), and link
quality reports in the uplink direction.
Fast Associated Control Channel (FACCH)
The FACCH is transmitted instead of a TCH. The FACCH ‘‘steals” the TCH
burst and inserts its own information. The FACCH is used to carry out user
authentication, handovers and immediate assignment.
All of the control channels are required for system operation, however, in the
same way that we allow different users to share the radio channel by using
different timeslots to carry the conversation data, the control channels share
timeslots on the radio channel at different times. This allows efficient passing
of control information without wasting capacity which could be used for call
traffic. To do this we must organize the timeslots between those which will be
used for traffic and those which will carry control signalling.
NU TEK India Limited

Contenu connexe

Tendances

Hw lte rf-optimization-guide
Hw lte rf-optimization-guideHw lte rf-optimization-guide
Hw lte rf-optimization-guide
tharinduwije
 
Gsm Originating Call Flow
Gsm Originating Call FlowGsm Originating Call Flow
Gsm Originating Call Flow
Deepak Sharma
 
DT analysis how to analyze crossed feeder issue by dt
DT analysis  how to analyze crossed feeder issue by dtDT analysis  how to analyze crossed feeder issue by dt
DT analysis how to analyze crossed feeder issue by dt
Sandy Sandyy
 

Tendances (20)

08. DRIVE TEST Analysis
08. DRIVE TEST Analysis08. DRIVE TEST Analysis
08. DRIVE TEST Analysis
 
LTE KPI
LTE KPILTE KPI
LTE KPI
 
Hw lte rf-optimization-guide
Hw lte rf-optimization-guideHw lte rf-optimization-guide
Hw lte rf-optimization-guide
 
05 gsm bss network kpi (tch congestion rate) optimization manual
05 gsm bss network kpi (tch congestion rate) optimization manual05 gsm bss network kpi (tch congestion rate) optimization manual
05 gsm bss network kpi (tch congestion rate) optimization manual
 
Radio Measurements in LTE
Radio Measurements in LTERadio Measurements in LTE
Radio Measurements in LTE
 
Gsm Originating Call Flow
Gsm Originating Call FlowGsm Originating Call Flow
Gsm Originating Call Flow
 
2G optimization_with_optima
2G optimization_with_optima2G optimization_with_optima
2G optimization_with_optima
 
DT analysis how to analyze crossed feeder issue by dt
DT analysis  how to analyze crossed feeder issue by dtDT analysis  how to analyze crossed feeder issue by dt
DT analysis how to analyze crossed feeder issue by dt
 
Layer 3 messages (2G)
Layer 3 messages (2G)Layer 3 messages (2G)
Layer 3 messages (2G)
 
190937694 csfb-call-flows
190937694 csfb-call-flows190937694 csfb-call-flows
190937694 csfb-call-flows
 
Sdcch
SdcchSdcch
Sdcch
 
Gsm bss kpi analysis
Gsm bss kpi analysisGsm bss kpi analysis
Gsm bss kpi analysis
 
GSM fundamentals (Huawei)
GSM fundamentals (Huawei)GSM fundamentals (Huawei)
GSM fundamentals (Huawei)
 
Sdcch Blocking Analysis
Sdcch Blocking AnalysisSdcch Blocking Analysis
Sdcch Blocking Analysis
 
Gsm physical and-logical_channels
Gsm physical and-logical_channelsGsm physical and-logical_channels
Gsm physical and-logical_channels
 
GSM capacity planning
GSM capacity planningGSM capacity planning
GSM capacity planning
 
Gsm architecture
Gsm architecture Gsm architecture
Gsm architecture
 
lte physical layer overview
 lte physical layer overview lte physical layer overview
lte physical layer overview
 
Pilot Pollution
Pilot PollutionPilot Pollution
Pilot Pollution
 
UMTS/LTE/EPC Call Flows for CSFB
UMTS/LTE/EPC Call Flows for CSFBUMTS/LTE/EPC Call Flows for CSFB
UMTS/LTE/EPC Call Flows for CSFB
 

En vedette

2008_Pugh-Kirch-Allstate-FINAL
2008_Pugh-Kirch-Allstate-FINAL 2008_Pugh-Kirch-Allstate-FINAL
2008_Pugh-Kirch-Allstate-FINAL
Cathy Kirch
 
2017_CFCC_AAS Degree_Diploma_Certificate_Copy.PDF
2017_CFCC_AAS Degree_Diploma_Certificate_Copy.PDF2017_CFCC_AAS Degree_Diploma_Certificate_Copy.PDF
2017_CFCC_AAS Degree_Diploma_Certificate_Copy.PDF
Jerald Washington
 

En vedette (13)

Gsm channels concept
Gsm channels conceptGsm channels concept
Gsm channels concept
 
Gsm channel
Gsm channelGsm channel
Gsm channel
 
Gsm air interface
Gsm air interface Gsm air interface
Gsm air interface
 
GSM channels
GSM channelsGSM channels
GSM channels
 
Bangkok
BangkokBangkok
Bangkok
 
Intel
IntelIntel
Intel
 
An Applied Information Economics Approach to Assessing Resilience in the Horn...
An Applied Information Economics Approach to Assessing Resilience in the Horn...An Applied Information Economics Approach to Assessing Resilience in the Horn...
An Applied Information Economics Approach to Assessing Resilience in the Horn...
 
Culture
CultureCulture
Culture
 
The legacy of Arlington’s Section 60
The legacy of Arlington’s Section 60The legacy of Arlington’s Section 60
The legacy of Arlington’s Section 60
 
2008_Pugh-Kirch-Allstate-FINAL
2008_Pugh-Kirch-Allstate-FINAL 2008_Pugh-Kirch-Allstate-FINAL
2008_Pugh-Kirch-Allstate-FINAL
 
2017_CFCC_AAS Degree_Diploma_Certificate_Copy.PDF
2017_CFCC_AAS Degree_Diploma_Certificate_Copy.PDF2017_CFCC_AAS Degree_Diploma_Certificate_Copy.PDF
2017_CFCC_AAS Degree_Diploma_Certificate_Copy.PDF
 
Gps tracking vehicle systems and devices
Gps tracking vehicle systems and devicesGps tracking vehicle systems and devices
Gps tracking vehicle systems and devices
 
Electric door openers linear telephone entry systems - fingerprint readers ...
Electric door openers   linear telephone entry systems - fingerprint readers ...Electric door openers   linear telephone entry systems - fingerprint readers ...
Electric door openers linear telephone entry systems - fingerprint readers ...
 

Similaire à Gsm channels

02 channel concept
02 channel concept02 channel concept
02 channel concept
Tempus Telcosys
 

Similaire à Gsm channels (20)

Gsm By Aziz
Gsm By AzizGsm By Aziz
Gsm By Aziz
 
3G architecture.pptx
3G architecture.pptx3G architecture.pptx
3G architecture.pptx
 
New rough
New roughNew rough
New rough
 
It802 d mobilecommunicationspart4
It802 d mobilecommunicationspart4It802 d mobilecommunicationspart4
It802 d mobilecommunicationspart4
 
Wcdma channels
Wcdma channelsWcdma channels
Wcdma channels
 
02 channel concept
02 channel concept02 channel concept
02 channel concept
 
GSM channels wireless
GSM channels  wirelessGSM channels  wireless
GSM channels wireless
 
GSM Channels
GSM ChannelsGSM Channels
GSM Channels
 
Definitions gsm
Definitions gsmDefinitions gsm
Definitions gsm
 
Gsm basics
Gsm basicsGsm basics
Gsm basics
 
GSM Channels Air Interface GSM Channels Air Interface
GSM Channels Air Interface GSM Channels Air InterfaceGSM Channels Air Interface GSM Channels Air Interface
GSM Channels Air Interface GSM Channels Air Interface
 
GSM Channel Concept
GSM Channel ConceptGSM Channel Concept
GSM Channel Concept
 
Logical channels
Logical channelsLogical channels
Logical channels
 
2 g
2 g2 g
2 g
 
39540950 gsm-ion-course-130814024028-phpapp01
39540950 gsm-ion-course-130814024028-phpapp0139540950 gsm-ion-course-130814024028-phpapp01
39540950 gsm-ion-course-130814024028-phpapp01
 
Module 4 Mobile comm GSM 3 G 4 G
Module 4 Mobile comm GSM 3 G 4 G Module 4 Mobile comm GSM 3 G 4 G
Module 4 Mobile comm GSM 3 G 4 G
 
Introduction to packet service evolution & new technologies
Introduction to packet service evolution & new technologiesIntroduction to packet service evolution & new technologies
Introduction to packet service evolution & new technologies
 
WCDMA Air Interface
WCDMA Air InterfaceWCDMA Air Interface
WCDMA Air Interface
 
Lte mac
Lte macLte mac
Lte mac
 
GSM Air Interface
GSM Air Interface GSM Air Interface
GSM Air Interface
 

Dernier

Easier, Faster, and More Powerful – Alles Neu macht der Mai -Wir durchleuchte...
Easier, Faster, and More Powerful – Alles Neu macht der Mai -Wir durchleuchte...Easier, Faster, and More Powerful – Alles Neu macht der Mai -Wir durchleuchte...
Easier, Faster, and More Powerful – Alles Neu macht der Mai -Wir durchleuchte...
panagenda
 
Hyatt driving innovation and exceptional customer experiences with FIDO passw...
Hyatt driving innovation and exceptional customer experiences with FIDO passw...Hyatt driving innovation and exceptional customer experiences with FIDO passw...
Hyatt driving innovation and exceptional customer experiences with FIDO passw...
FIDO Alliance
 
Tales from a Passkey Provider Progress from Awareness to Implementation.pptx
Tales from a Passkey Provider  Progress from Awareness to Implementation.pptxTales from a Passkey Provider  Progress from Awareness to Implementation.pptx
Tales from a Passkey Provider Progress from Awareness to Implementation.pptx
FIDO Alliance
 

Dernier (20)

Human Expert Website Manual WCAG 2.0 2.1 2.2 Audit - Digital Accessibility Au...
Human Expert Website Manual WCAG 2.0 2.1 2.2 Audit - Digital Accessibility Au...Human Expert Website Manual WCAG 2.0 2.1 2.2 Audit - Digital Accessibility Au...
Human Expert Website Manual WCAG 2.0 2.1 2.2 Audit - Digital Accessibility Au...
 
Working together SRE & Platform Engineering
Working together SRE & Platform EngineeringWorking together SRE & Platform Engineering
Working together SRE & Platform Engineering
 
2024 May Patch Tuesday
2024 May Patch Tuesday2024 May Patch Tuesday
2024 May Patch Tuesday
 
(Explainable) Data-Centric AI: what are you explaininhg, and to whom?
(Explainable) Data-Centric AI: what are you explaininhg, and to whom?(Explainable) Data-Centric AI: what are you explaininhg, and to whom?
(Explainable) Data-Centric AI: what are you explaininhg, and to whom?
 
Using IESVE for Room Loads Analysis - UK & Ireland
Using IESVE for Room Loads Analysis - UK & IrelandUsing IESVE for Room Loads Analysis - UK & Ireland
Using IESVE for Room Loads Analysis - UK & Ireland
 
Easier, Faster, and More Powerful – Notes Document Properties Reimagined
Easier, Faster, and More Powerful – Notes Document Properties ReimaginedEasier, Faster, and More Powerful – Notes Document Properties Reimagined
Easier, Faster, and More Powerful – Notes Document Properties Reimagined
 
State of the Smart Building Startup Landscape 2024!
State of the Smart Building Startup Landscape 2024!State of the Smart Building Startup Landscape 2024!
State of the Smart Building Startup Landscape 2024!
 
The Value of Certifying Products for FDO _ Paul at FIDO Alliance.pdf
The Value of Certifying Products for FDO _ Paul at FIDO Alliance.pdfThe Value of Certifying Products for FDO _ Paul at FIDO Alliance.pdf
The Value of Certifying Products for FDO _ Paul at FIDO Alliance.pdf
 
Intro in Product Management - Коротко про професію продакт менеджера
Intro in Product Management - Коротко про професію продакт менеджераIntro in Product Management - Коротко про професію продакт менеджера
Intro in Product Management - Коротко про професію продакт менеджера
 
ADP Passwordless Journey Case Study.pptx
ADP Passwordless Journey Case Study.pptxADP Passwordless Journey Case Study.pptx
ADP Passwordless Journey Case Study.pptx
 
Where to Learn More About FDO _ Richard at FIDO Alliance.pdf
Where to Learn More About FDO _ Richard at FIDO Alliance.pdfWhere to Learn More About FDO _ Richard at FIDO Alliance.pdf
Where to Learn More About FDO _ Richard at FIDO Alliance.pdf
 
Easier, Faster, and More Powerful – Alles Neu macht der Mai -Wir durchleuchte...
Easier, Faster, and More Powerful – Alles Neu macht der Mai -Wir durchleuchte...Easier, Faster, and More Powerful – Alles Neu macht der Mai -Wir durchleuchte...
Easier, Faster, and More Powerful – Alles Neu macht der Mai -Wir durchleuchte...
 
Long journey of Ruby Standard library at RubyKaigi 2024
Long journey of Ruby Standard library at RubyKaigi 2024Long journey of Ruby Standard library at RubyKaigi 2024
Long journey of Ruby Standard library at RubyKaigi 2024
 
Microsoft CSP Briefing Pre-Engagement - Questionnaire
Microsoft CSP Briefing Pre-Engagement - QuestionnaireMicrosoft CSP Briefing Pre-Engagement - Questionnaire
Microsoft CSP Briefing Pre-Engagement - Questionnaire
 
Hyatt driving innovation and exceptional customer experiences with FIDO passw...
Hyatt driving innovation and exceptional customer experiences with FIDO passw...Hyatt driving innovation and exceptional customer experiences with FIDO passw...
Hyatt driving innovation and exceptional customer experiences with FIDO passw...
 
TEST BANK For, Information Technology Project Management 9th Edition Kathy Sc...
TEST BANK For, Information Technology Project Management 9th Edition Kathy Sc...TEST BANK For, Information Technology Project Management 9th Edition Kathy Sc...
TEST BANK For, Information Technology Project Management 9th Edition Kathy Sc...
 
Tales from a Passkey Provider Progress from Awareness to Implementation.pptx
Tales from a Passkey Provider  Progress from Awareness to Implementation.pptxTales from a Passkey Provider  Progress from Awareness to Implementation.pptx
Tales from a Passkey Provider Progress from Awareness to Implementation.pptx
 
ASRock Industrial FDO Solutions in Action for Industrial Edge AI _ Kenny at A...
ASRock Industrial FDO Solutions in Action for Industrial Edge AI _ Kenny at A...ASRock Industrial FDO Solutions in Action for Industrial Edge AI _ Kenny at A...
ASRock Industrial FDO Solutions in Action for Industrial Edge AI _ Kenny at A...
 
The Metaverse: Are We There Yet?
The  Metaverse:    Are   We  There  Yet?The  Metaverse:    Are   We  There  Yet?
The Metaverse: Are We There Yet?
 
How we scaled to 80K users by doing nothing!.pdf
How we scaled to 80K users by doing nothing!.pdfHow we scaled to 80K users by doing nothing!.pdf
How we scaled to 80K users by doing nothing!.pdf
 

Gsm channels

  • 1. NU TEK India Limited NU TEK (I) LIMITED 1505-06, 15th Floor, Global Business Park, Tower – D, M.G. Road, GURGAON, INDIA TEL NO. 0124- 4171600 FAX NO. 0124-4011275
  • 2. NU TEK India Limited CHANNELS
  • 3. NU TEK India Limited
  • 4. NU TEK India Limited
  • 5. NU TEK India Limited
  • 6. NU TEK India Limited Channels in GSM Air interface  Logical Channels : ARFCN –x, Timeslot – y, Frame Number - N Logical Channels Control Channels Traffic Channels
  • 7. NU TEK India Limited Logical channel  One or more logical channel can be transmitted on a physical channel. Different types of logical channel are –  Traffic Channels (Speech & Data)  Broad cast channel (Signalling)  Common control channel (Signalling)  Dedicated control channel (Signalling)
  • 8. NU TEK India Limited
  • 9. NU TEK India Limited
  • 10. NU TEK India Limited TRAFFIC CHANNEL
  • 11. NU TEK India Limited Traffic Channels Traffic Channels TCH - F TCH - H
  • 12. NU TEK India Limited
  • 13. NU TEK India Limited  Traffic Channel carries the voice data  Two blocks of 57 bits contain voice data  One TCH is allocated for every active call. While call is in progress if there is degradation in quality of current channel, BTS may shift the communication to another TCH on a different Carrier and/or Timeslot  A full rate TCH carries 13 kbps voice data, and Half rate TCH carries a 6.5 kbps voice data
  • 14. NU TEK India Limited
  • 15. NU TEK India Limited Traffic Channels (TCH) One physical channel (1 timeslot) can support: Traffic channels are used to send Speech or Data services. 1 TCH/F or 2 TCH/H • TCH/F: 13 kb/s voice or 9.6 kb/s data (22.8 Kbps after channel coding) • TCH/H: 6.5 kb/s voice or 4.8 kb/s data (11.4 kbps after channel coding) Both can be used to carry signalling information. Uplink / Downlink Synchronisation The MS transmit burst is delayed by 3 timeslots after the BTS burst.. This delay allows enables: Use of the same UL and DL timeslot number in TDMA frame Avoids simultaneous Tx/Rx requirement
  • 16. NU TEK India Limited
  • 17. NU TEK India Limited Speech channels are supported by two different methods of coding known as Full Rate (FR) and Enhanced Full Rate (EFR). Enhanced Full Rate coding provides a speech service that has improved voice quality from the original Full Rate speech coding, whilst using the same air interface bandwidth. EFR employs a new speech coding algorithm and additions to the full rate channel coding algorithm to accomplish this improved speech service,
  • 18. NU TEK India Limited
  • 19. NU TEK India Limited CONTROL CHANNEL
  • 20. NU TEK India Limited Channels in GSM Air interface  Logical Channels : ARFCN –x, Timeslot – y, Frame Number - N Logical Channels Control Channels Traffic Channels
  • 21. NU TEK India Limited Concepts of Channels in GSM  A company vehicle is used for several purposes in a day  Similarly in GSM, the timeslots are used for different purposes at different times
  • 22. NU TEK India Limited These control channels are used by the MS to establish communication with the network in the idle mode and also in initiating calls to enter the dedicated mode. Timeslot 0 is grouped into structures of 51 frames referred to as Control Channel Multiframes The control channels are grouped as Broadcast Control Channels (BCCH) Common Control Channels (CCCH) and Dedicated Control Channel (DCCH).
  • 23. NU TEK India Limited Broadcast Channels (BCCH)
  • 24. NU TEK India Limited
  • 25. NU TEK India Limited BCH (Broadcast Channel)  One ARFCN, On all the time, in every cell  Uses Timeslot 0 on a channel, in Downlink  FCH – Frequency correction channel (allows mobile to tune to BTS frequency. This channel carries a 142 bit zero sequence and repeats once in every 10 frames on BCH)  SCH – Synchronization channel (carries the Frame number and BSIC). A midamble of 64 bit helps mobiles to synchronize. It also repeats once in 10 Frames
  • 26. NU TEK India Limited  BCCH – Broadcast Control Channel. It has information encoded on it which identifies the network (LAC). It also carries list of the channels in use in the cell (CA tables) BCH (Broadcast Channel)
  • 27. NU TEK India Limited The Broadcast Control Channel is transmitted by the BTS at all times. The RF carrier used to transmit the BCCH is referred to as the BCCH carrier. The information carried on the BCCH is monitored by the MS periodically (at least every 30 secs), when it is switched on and not in a call. Each cell has one carrier designated as a BCH carrier. The BCH carrier has all 8 timeslots continuously on, either with traffic or dummy bursts. Timeslot 0 of the BCH carrier contains logical control channels. Broadcast Control Channel (BCCH) – Carries the following information (this is only a partial list):  Location Area Identity (LAI).  List of neighbouring cells which should be monitored by the MS.  List of frequencies used in the cell.  Cell identity.  Power control indicator.  DTX permitted.  Access control (for example, emergency calls, call barring).
  • 28. NU TEK India Limited
  • 29. NU TEK India Limited Information distributed over Broadcast channel helps the MS to orient themselves in the mobile radio N/W .BCH channels are all downlink Pt. to Multi pt. and are allocated to timeslot zero. FCCH: Frequency correction channel This is transmitted frequently on the BCCH timeslot and 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 the BCCH carrier frequency and therefore it acts as a flag to the mobile to identify Timeslot 0. SCH: (Synchronisation channel ) The SCH carries the information to enable the MS to 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 MS will monitor BCCH information from surrounding cells and store the information from the best six cells. The SCH information on these cells is also stored so that the MS may quickly resynchronize when it enters a new cell.
  • 30. NU TEK India Limited Common Control Channels (CCCH)
  • 31. NU TEK India Limited
  • 32. NU TEK India Limited Common Control Channel  CCCH shares Timeslot 0 with BCH on a Multiframe  CCCH consists of PCH, RACH and AGCH  PCH – Paging channel is used to alert mobiles on incoming calls. PCH carries IMSI to page for Mobiles in the cell. PCH is Downlink channel.  RACH – Random Access Channel is a short burst sent by mobile to BTS, to initiate a call request. RACH uses timeslot 0 on reverse BCH channel on uplink
  • 33. NU TEK India Limited Common Control Channels (CCCH) CCCH contains all point to multi-point downlink channels (BTS to several MSs) and the uplink Random Access Channel: RACH: (UL) Random Access Channel is sent by the MS to request a resources from the network e.g. an SDCCH channel for call setup. • AGCH (DL) Access Grant Channel is used to allocate a dedicated channel (SDCCH) to the mobile. • PCH (DL) Paging Channel sends paging signal to inform mobile of a call. Active MSs must frequently monitor both BCCH and CCCH. The CCCH will be transmitted on the RF carrier with the BCCH.
  • 34. NU TEK India Limited
  • 35. NU TEK India Limited
  • 36. NU TEK India Limited Dedicated Control Channels (DCCH) DCCH comprise the following bi-directional (uplink / downlink) point to point control channels .Used for signalling between MS & BTS: • SDCCH: Standalone Dedicated control Channel is used for call set up, location updating and also SMS.It carries all signalling B/W BTS & MS when no TCH is allocated. Which supports the transfer of Data to and from the MS during call setup and validation. Summary—Used for services request, SMS,Location update ,subscriber Authentication,Equipment validation. (Afterwards TCH Comes into picture) • SACCH: Slow Associated Control Channel is used for link measurements and signalling during a call .Used for non urgent procedures. Summary—transmission of Signalling Data ,Radio Link Supervision measurement ,Transmit power control & Timing advance data
  • 37. NU TEK India Limited FACCH • FACCH: Fast Associated Control CHannel is used (when needed) for signalling during a call, mainly for delivering handover messages and for acknowledgement when a TCH is assigned.Used mainly during handovers when SACCH Signalling is not fast enough.FACCH data is transmitted over TCH, this is marked by Flag called “Stealling Flag”
  • 38. NU TEK India Limited RACH – Random Access Channel 8 start bits 41 Synchronization bits 36 Encrypted bits 3 stop bits 68.25 Extended Guard Period 88 bits  Used by mobile to get attention from Base Station  Several mobiles might originate RACH simultaneously  Mobile doesn’t know path delay  So RACH has to be a special short burst  Mobile sends normal burst after getting timing advance on downlink SACCH
  • 39. NU TEK India Limited DCCH – Dedicated Control Channels  SDCCH – Standalone Dedicated Common Control Channel. It is used as a interim channel before final assignment of TCH. SDCCH is used for signaling and Authentication message transfers. It can be called the stepping stone between BSC and TCH The SDCCH, by using less of the cells resource of physical channels, improves efficiency, and provides a useful holding channel for the mobile until speech data needs to be exchanged.
  • 40. NU TEK India Limited Dedicated Control Channels (cont..)  FACCH – Fast Associated Control Channel Interrupts TCH on uplink and downlink Rapid message exchange for handovers Control bits on either side of midamble – 0 indicates TCH and 1 indicates FACCH Both ways – uplink and downlink
  • 41. NU TEK India Limited SACCH – Slow associated Control Channel  Downlink (BTS – MS)  Mobile Tx Power Commands  Mobile Timing Advance  Cell’s Channel Configuration  Uplink (MS - BTS)  Received signal quality report (RXQual)  Received signal level report (RXLev)  Adjacent BCH power measurement
  • 42. NU TEK India Limited
  • 43. NU TEK India Limited
  • 44. NU TEK India Limited Dedicated Control Channels (DCCH) The DCCH is a single timeslot on an RF carrier which is used to convey eight Stand-alone Dedicated Control Channels (SDCCH). A SDCCH is used by a single MS for call setup, authentication, location updating and SMS point to point. As we will see later, SDCCH can also be found on a BCCH/CCCH timeslot, this configuration only allows four SDCCHs. Associated Control Channels (ACCH) These channels can be associated with either an SDCCH or a TCH. They are used for carrying information associated with the process being carried out on either the SDCCH or the TCH.
  • 45. NU TEK India Limited CONTINUE Slow Associated Control Channel (SACCH) Conveys power control and timing information in the downlink direction (towards the MS) and Receive Signal Strength Indicator (RSSI), and link quality reports in the uplink direction. Fast Associated Control Channel (FACCH) The FACCH is transmitted instead of a TCH. The FACCH ‘‘steals” the TCH burst and inserts its own information. The FACCH is used to carry out user authentication, handovers and immediate assignment. All of the control channels are required for system operation, however, in the same way that we allow different users to share the radio channel by using different timeslots to carry the conversation data, the control channels share timeslots on the radio channel at different times. This allows efficient passing of control information without wasting capacity which could be used for call traffic. To do this we must organize the timeslots between those which will be used for traffic and those which will carry control signalling.
  • 46. NU TEK India Limited