GSM RADIO INTERFACE GSM RADIO INTERFACE IN THIS
![GSM - RADIO INTERFACE GSM - RADIO INTERFACE](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-1.jpg)
![GSM - RADIO INTERFACE IN THIS PRESENTATION • Radio Interface • Frequency Bands & GSM - RADIO INTERFACE IN THIS PRESENTATION • Radio Interface • Frequency Bands &](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-2.jpg)
![Communication - Mobile Subscriber Line (2 W) Inter-Exchange Junction BSC BTS Telephone Exchange Mobile Communication - Mobile Subscriber Line (2 W) Inter-Exchange Junction BSC BTS Telephone Exchange Mobile](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-3.jpg)
![GSM RADIO INTERFACE • Most Important Interface • Full Compatibility between mobile stations of GSM RADIO INTERFACE • Most Important Interface • Full Compatibility between mobile stations of](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-4.jpg)
![GSM Uplink & Downlink • Frequency Bands GSM 900 Mhz DCS 1800 MHz K GSM Uplink & Downlink • Frequency Bands GSM 900 Mhz DCS 1800 MHz K](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-5.jpg)
![GSM Specifications RF Spectrum : GSM 900 Mobile to BS BS to Mobile (UP-LINK) GSM Specifications RF Spectrum : GSM 900 Mobile to BS BS to Mobile (UP-LINK)](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-6.jpg)
![GSM Specifications Carrier Separation - 200 k. Hz Duplex Distance - 45 MHz No. GSM Specifications Carrier Separation - 200 k. Hz Duplex Distance - 45 MHz No.](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-7.jpg)
![GSM - MULTIPLE ACCESS • GSM uses both FDMA & TDMA • FDMA Access GSM - MULTIPLE ACCESS • GSM uses both FDMA & TDMA • FDMA Access](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-8.jpg)
![GSM - MULTIPLE ACCESS • Absolute Radio Freq Carrier Number (ARFCN) 1 and 124 GSM - MULTIPLE ACCESS • Absolute Radio Freq Carrier Number (ARFCN) 1 and 124](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-9.jpg)
![GSM FDMA 890 915 25 MHz 1 0 2 890. 4 200 k. Hz GSM FDMA 890 915 25 MHz 1 0 2 890. 4 200 k. Hz](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-10.jpg)
![GSM TDMA Amplitude 45 MHz 1 F 1 (Cell Rx) 2 3 4 5 GSM TDMA Amplitude 45 MHz 1 F 1 (Cell Rx) 2 3 4 5](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-11.jpg)
![GSM Digital Voice Transmission Speech Coding - In GSM speech coding a block of GSM Digital Voice Transmission Speech Coding - In GSM speech coding a block of](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-12.jpg)
![GSM Digital Voice Transmission Channel Coding - It uses 260 bits from speech coding GSM Digital Voice Transmission Channel Coding - It uses 260 bits from speech coding](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-13.jpg)
![GSM Digital Voice Transmission Burst Formatting To counteract the problems encountered in radio path: GSM Digital Voice Transmission Burst Formatting To counteract the problems encountered in radio path:](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-14.jpg)
![Interleaving & Burst Formating 1 st Sample of 20 ms speech 2 nd Sample Interleaving & Burst Formating 1 st Sample of 20 ms speech 2 nd Sample](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-15.jpg)
![GSM Speech to Radio waves Analog Speech Coding Speech Decoding Channel Coding Channel Decoding GSM Speech to Radio waves Analog Speech Coding Speech Decoding Channel Coding Channel Decoding](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-16.jpg)
![FDMA/TDMA Scheme TIME BP 2 BP 1 BP 8 BURST BP 7 BP 6 FDMA/TDMA Scheme TIME BP 2 BP 1 BP 8 BURST BP 7 BP 6](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-17.jpg)
![3 CC SMS T CM SS 142 3 8. 25 Fixed Bits T GP 3 CC SMS T CM SS 142 3 8. 25 Fixed Bits T GP](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-18.jpg)
![PHYSICAL CHANNELS 8 7 6 5 4 3 2 1 FRAME OF 8 TIME PHYSICAL CHANNELS 8 7 6 5 4 3 2 1 FRAME OF 8 TIME](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-19.jpg)
![GSM-- TDMA STRUCTURE • TDMA • Time slot duration • Frame • Multi Frame GSM-- TDMA STRUCTURE • TDMA • Time slot duration • Frame • Multi Frame](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-20.jpg)
![GSM Radio Interface - CYCLES Hyperframe = 2048 Superframes 3 Hours 28 Minutes 53 GSM Radio Interface - CYCLES Hyperframe = 2048 Superframes 3 Hours 28 Minutes 53](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-21.jpg)
![Organisation of Speech & Data Frames 0 -11 : TCH 0 1 2 3 Organisation of Speech & Data Frames 0 -11 : TCH 0 1 2 3](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-22.jpg)
![Logical Channels Traffic Channels Control Channels Full-Rate Broadcast Channels FCCH SCH BCCH Common Control Logical Channels Traffic Channels Control Channels Full-Rate Broadcast Channels FCCH SCH BCCH Common Control](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-23.jpg)
![GSM LOGICAL CHANNELS • USER INFORMATION( TRAFFIC) • SIGNALLING INFORMATION (CONTROL) GSM LOGICAL CHANNELS • USER INFORMATION( TRAFFIC) • SIGNALLING INFORMATION (CONTROL)](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-24.jpg)
![GSM CONTOL CHHANELS OVER LOGICAL CHANNELS • Intended to carry signalling and synchronisation THREE GSM CONTOL CHHANELS OVER LOGICAL CHANNELS • Intended to carry signalling and synchronisation THREE](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-25.jpg)
![OPERATIONAL CONCEPTS • Subscribers are not allocated dedicated channels • TCH • Hence IDLE OPERATIONAL CONCEPTS • Subscribers are not allocated dedicated channels • TCH • Hence IDLE](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-26.jpg)
![GSM THREE TYPES OF CONTROL CHANNELS Broadcast control channel BCCH P- MP For Freq GSM THREE TYPES OF CONTROL CHANNELS Broadcast control channel BCCH P- MP For Freq](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-27.jpg)
![OPERATIONAL CONCEPTS IDLE MODE ACCESS PROCDURE DEDICATED MODE • IDLE MODE ----FCCH ---- SCH OPERATIONAL CONCEPTS IDLE MODE ACCESS PROCDURE DEDICATED MODE • IDLE MODE ----FCCH ---- SCH](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-28.jpg)
![GSM – RF Interface Other Salient Features Of GSM RF I/F: - Control of GSM – RF Interface Other Salient Features Of GSM RF I/F: - Control of](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-29.jpg)
![Discontinuous Transmission (DTX) • Speech activity only 40% of time. • Needs Voice activity Discontinuous Transmission (DTX) • Speech activity only 40% of time. • Needs Voice activity](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-30.jpg)
![GSM – RF Interface Timing Alignment : - Large distance between BTS and MS GSM – RF Interface Timing Alignment : - Large distance between BTS and MS](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-31.jpg)
![GSM – RF Interface Timing Advance : ( To counteract problem of Time Alignment GSM – RF Interface Timing Advance : ( To counteract problem of Time Alignment](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-32.jpg)
![GSM – RF Interface Antenna Diversity : Space Diversity - Mounting two receiver antenna GSM – RF Interface Antenna Diversity : Space Diversity - Mounting two receiver antenna](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-33.jpg)
![FREQUENCY HOPPING • Change of frequency after every frame in a pre-determined manner • FREQUENCY HOPPING • Change of frequency after every frame in a pre-determined manner •](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-34.jpg)
![GSM - RADIO INTERFACE SUMMARY • Radio Interface • Frequency Bands & Specifications • GSM - RADIO INTERFACE SUMMARY • Radio Interface • Frequency Bands & Specifications •](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-35.jpg)
![MOBILE COMMUNICATION THANKS !! MOBILE COMMUNICATION THANKS !!](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-36.jpg)
- Slides: 36
![GSM RADIO INTERFACE GSM - RADIO INTERFACE](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-1.jpg)
GSM - RADIO INTERFACE
![GSM RADIO INTERFACE IN THIS PRESENTATION Radio Interface Frequency Bands GSM - RADIO INTERFACE IN THIS PRESENTATION • Radio Interface • Frequency Bands &](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-2.jpg)
GSM - RADIO INTERFACE IN THIS PRESENTATION • Radio Interface • Frequency Bands & Specifications • Multiple Access Method FDMA & TDMA • FDMA /TDMA Frame Representation • Logical Channels Traffic & Control • Operational Concepts • Other Salient Features of RF I/F- DTX, Time Alignment Diversity, Fr. Hopping, Power Control.
![Communication Mobile Subscriber Line 2 W InterExchange Junction BSC BTS Telephone Exchange Mobile Communication - Mobile Subscriber Line (2 W) Inter-Exchange Junction BSC BTS Telephone Exchange Mobile](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-3.jpg)
Communication - Mobile Subscriber Line (2 W) Inter-Exchange Junction BSC BTS Telephone Exchange Mobile Switching Centre (MSC) MS
![GSM RADIO INTERFACE Most Important Interface Full Compatibility between mobile stations of GSM RADIO INTERFACE • Most Important Interface • Full Compatibility between mobile stations of](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-4.jpg)
GSM RADIO INTERFACE • Most Important Interface • Full Compatibility between mobile stations of various Manufacturers & Networks of different vendors to help roaming • To increase spectral efficiency -- Large number of simultaneous calls in a given bandwidth -- Frequency Reuse -- Interference -- Use of Interference Reduction Techniques
![GSM Uplink Downlink Frequency Bands GSM 900 Mhz DCS 1800 MHz K GSM Uplink & Downlink • Frequency Bands GSM 900 Mhz DCS 1800 MHz K](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-5.jpg)
GSM Uplink & Downlink • Frequency Bands GSM 900 Mhz DCS 1800 MHz K N LI UP W O D K N I L N B T S
![GSM Specifications RF Spectrum GSM 900 Mobile to BS BS to Mobile UPLINK GSM Specifications RF Spectrum : GSM 900 Mobile to BS BS to Mobile (UP-LINK)](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-6.jpg)
GSM Specifications RF Spectrum : GSM 900 Mobile to BS BS to Mobile (UP-LINK) - 890 to 915 MHz (DOWN -LINK) 935 to 960 MHz Bandwidth - 25 MHz GSM 1800 ( DCS ) : Mobile to Cell (UP-LINK) 1710 to 1785 MHz Cell to Mobile (DOWN -LINK) 1805 to 1880 MHz Bandwidth - 75 MHz
![GSM Specifications Carrier Separation 200 k Hz Duplex Distance 45 MHz No GSM Specifications Carrier Separation - 200 k. Hz Duplex Distance - 45 MHz No.](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-7.jpg)
GSM Specifications Carrier Separation - 200 k. Hz Duplex Distance - 45 MHz No. of RF Carriers - 124 Access Method - TDMA/FDMA Modulation Method - GMSK Transmission Rate - 270. 833 Kbps Speech Coding - Full rate 13 Kbps Half rate 6. 5 Kbps
![GSM MULTIPLE ACCESS GSM uses both FDMA TDMA FDMA Access GSM - MULTIPLE ACCESS • GSM uses both FDMA & TDMA • FDMA Access](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-8.jpg)
GSM - MULTIPLE ACCESS • GSM uses both FDMA & TDMA • FDMA Access along Frequency axis • Each RF carrier 200 khz apart • Total 124 RF Channels available. One or more carrier assigned to each base station 1 2 3 4 5 6 124 ……. . . Freq 890. 2 890. 4 890. 6 890. 8 891. 0 914. 8 Mhz.
![GSM MULTIPLE ACCESS Absolute Radio Freq Carrier Number ARFCN 1 and 124 GSM - MULTIPLE ACCESS • Absolute Radio Freq Carrier Number (ARFCN) 1 and 124](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-9.jpg)
GSM - MULTIPLE ACCESS • Absolute Radio Freq Carrier Number (ARFCN) 1 and 124 not used until it is co-ordinated with Non -GSM operators in adjacent freq. bands. • Thus for practical purposes only 122 RF Carriers are available. • Frequency for any ARFCN ( n) can be calculated from : F up-link (n) = 890. 2 +0. 2* ( n-1 ) MHz F down-link (n) = 935. 2 +0. 2* ( n-1 ) MHz Here 124.
![GSM FDMA 890 915 25 MHz 1 0 2 890 4 200 k Hz GSM FDMA 890 915 25 MHz 1 0 2 890. 4 200 k. Hz](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-10.jpg)
GSM FDMA 890 915 25 MHz 1 0 2 890. 4 200 k. Hz 45 MHz 890. 6 960 25 MHz 1 0 Mobile to Base 890. 2 935 2 Base to Mobile (MHz) 935. 2 935. 4 935. 6 200 k. Hz Channel layout and frequency bands of operation
![GSM TDMA Amplitude 45 MHz 1 F 1 Cell Rx 2 3 4 5 GSM TDMA Amplitude 45 MHz 1 F 1 (Cell Rx) 2 3 4 5](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-11.jpg)
GSM TDMA Amplitude 45 MHz 1 F 1 (Cell Rx) 2 3 4 5 6 7 8 1 F 2 2 3 4 5 6 7 8 F 1’ F 2’ (Cell transmit) Typical TDMA/ FDMA frame structure Frequency
![GSM Digital Voice Transmission Speech Coding In GSM speech coding a block of GSM Digital Voice Transmission Speech Coding - In GSM speech coding a block of](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-12.jpg)
GSM Digital Voice Transmission Speech Coding - In GSM speech coding a block of 20 ms is encoded in one set of 260 bits. - This calculates as 50 X 260 = 13 kbps. Thus GSM speech coder produces a bit rate of 13 kbps per subscriber. - This provides speech quality which is acceptable for mobile telephony and comparable with wire-line PSTN phones.
![GSM Digital Voice Transmission Channel Coding It uses 260 bits from speech coding GSM Digital Voice Transmission Channel Coding - It uses 260 bits from speech coding](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-13.jpg)
GSM Digital Voice Transmission Channel Coding - It uses 260 bits from speech coding as input and outputs 456 encoded bits. Interleaving - These 456 bits for every 20 ms of speech are interleaved forming eight blocks of 57 bits each. - In one burst one block of 57 bits from one sample and another block from another sample are sent together.
![GSM Digital Voice Transmission Burst Formatting To counteract the problems encountered in radio path GSM Digital Voice Transmission Burst Formatting To counteract the problems encountered in radio path:](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-14.jpg)
GSM Digital Voice Transmission Burst Formatting To counteract the problems encountered in radio path: - Additional bits as training sequence added to basic speech/data. - Total of 136 bits added, bringing overall total to 592 bits. - Each TS of TDMA frame is 0. 577 ms long and during this time 156. 25 bits are transmitted. - One burst contains only 148 bits. Rest of the space, 8. 25 bits time, is empty and is called Guard Period ( GP ). - GP enables MS/BTS to “ramp up” and “ ramp down”.
![Interleaving Burst Formating 1 st Sample of 20 ms speech 2 nd Sample Interleaving & Burst Formating 1 st Sample of 20 ms speech 2 nd Sample](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-15.jpg)
Interleaving & Burst Formating 1 st Sample of 20 ms speech 2 nd Sample of 20 ms speech 456 bits Sample 1 456 bits Sample 2 D D D 1 2 3 D D 4 5 D 6 7 8 1 2 3 4 5 D D 1 4 5 2 3 D D 6 7 8 Stream of Time Slots 3 57 1 26 1 Normal Burst 57 3 8. 25
![GSM Speech to Radio waves Analog Speech Coding Speech Decoding Channel Coding Channel Decoding GSM Speech to Radio waves Analog Speech Coding Speech Decoding Channel Coding Channel Decoding](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-16.jpg)
GSM Speech to Radio waves Analog Speech Coding Speech Decoding Channel Coding Channel Decoding Interleaving De-interleaving Burst formatting Ciphering Deciphering Modulation Demodulation 200 k. Hz BW
![FDMATDMA Scheme TIME BP 2 BP 1 BP 8 BURST BP 7 BP 6 FDMA/TDMA Scheme TIME BP 2 BP 1 BP 8 BURST BP 7 BP 6](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-17.jpg)
FDMA/TDMA Scheme TIME BP 2 BP 1 BP 8 BURST BP 7 BP 6 F BP 5 R BP 4 A BP 3 M BP 2 E BP 1 FREQ 890. 0 890. 2 890. 4 890. 6 890. 8 891. 0 891. 2 915. 8 MHz
![3 CC SMS T CM SS 142 3 8 25 Fixed Bits T GP 3 CC SMS T CM SS 142 3 8. 25 Fixed Bits T GP](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-18.jpg)
3 CC SMS T CM SS 142 3 8. 25 Fixed Bits T GP FCCH Burst 3 CC SMS 57 SS T CM Encrypted 1 S 26 1 57 3 8. 25 Training S Encrypted T GP Normal Burst
![PHYSICAL CHANNELS 8 7 6 5 4 3 2 1 FRAME OF 8 TIME PHYSICAL CHANNELS 8 7 6 5 4 3 2 1 FRAME OF 8 TIME](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-19.jpg)
PHYSICAL CHANNELS 8 7 6 5 4 3 2 1 FRAME OF 8 TIME SLOTS 8 7 6 5 4 3 2 1 FRAME REPETITION 8 7 6 5 4 3 2 1 8 1 2 3 4 5 6 7 8 7 6 1 2 3 4 5 6 7 8 5 1 2 3 4 5 6 74 8 1 2 3 4 5 6 7 8 3 2 1 2 3 4 5 6 7 8 1 PHYSICAL CHANNELS 1
![GSM TDMA STRUCTURE TDMA Time slot duration Frame Multi Frame GSM-- TDMA STRUCTURE • TDMA • Time slot duration • Frame • Multi Frame](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-20.jpg)
GSM-- TDMA STRUCTURE • TDMA • Time slot duration • Frame • Multi Frame 8 Time Slots / RF Channel 0. 577 m sec or 15 / 26 m sec 8 Burst Periods ( Time Slots) = 8 15/26 = 4. 615 m sec Traffic 26 4. 615 = 120 msec Control • Super Frame 51 4. 615 = 235. 365 m sec 51 Traffic Multi frames 26 Control Multi frames • Hyper Frame 2048 Super Frames = 3 28 52. 76 hr min sec
![GSM Radio Interface CYCLES Hyperframe 2048 Superframes 3 Hours 28 Minutes 53 GSM Radio Interface - CYCLES Hyperframe = 2048 Superframes 3 Hours 28 Minutes 53](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-21.jpg)
GSM Radio Interface - CYCLES Hyperframe = 2048 Superframes 3 Hours 28 Minutes 53 Seconds and 760 milliseconds 0 2047 Superframe = 26× 51 multiframes 6. 12 Seconds 0 50 0 0 1 25 26 Multiframe 51 Multiframe 120 m. S Approx 235 m. S 2 24 25 0 1 48 TDMA frame 4. 615 m. S 0 1 2 3 4 5 6 7 49 50
![Organisation of Speech Data Frames 0 11 TCH 0 1 2 3 Organisation of Speech & Data Frames 0 -11 : TCH 0 1 2 3](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-22.jpg)
Organisation of Speech & Data Frames 0 -11 : TCH 0 1 2 3 4 Frames 12 : SACCH 5 6 7 8 9 10 11 Frames 13 -24 : TCH 12 13 14 15 16 17 18 Frames 25 : Unused 19 20 21 22 23 24 25 26 – frame multiframe Duration: 120 ms BP 0 3 BP 1 57 Tail Data bits BP 2 1 BP 3 BP 4 26 BP 5 1 BP 6 BP 7 57 Stealing Training Stealing Data bits sequence bit TDMA frame Duration: 60/13 ms =4. 615 ms 3 8. 25 Tail Guard bits Normal burst Duration 15/26 ms
![Logical Channels Traffic Channels Control Channels FullRate Broadcast Channels FCCH SCH BCCH Common Control Logical Channels Traffic Channels Control Channels Full-Rate Broadcast Channels FCCH SCH BCCH Common Control](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-23.jpg)
Logical Channels Traffic Channels Control Channels Full-Rate Broadcast Channels FCCH SCH BCCH Common Control Channels Dedicated Control Channels RACH PCH AGCH SDCCH SACCH FACCH Half-Rate
![GSM LOGICAL CHANNELS USER INFORMATION TRAFFIC SIGNALLING INFORMATION CONTROL GSM LOGICAL CHANNELS • USER INFORMATION( TRAFFIC) • SIGNALLING INFORMATION (CONTROL)](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-24.jpg)
GSM LOGICAL CHANNELS • USER INFORMATION( TRAFFIC) • SIGNALLING INFORMATION (CONTROL)
![GSM CONTOL CHHANELS OVER LOGICAL CHANNELS Intended to carry signalling and synchronisation THREE GSM CONTOL CHHANELS OVER LOGICAL CHANNELS • Intended to carry signalling and synchronisation THREE](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-25.jpg)
GSM CONTOL CHHANELS OVER LOGICAL CHANNELS • Intended to carry signalling and synchronisation THREE TYPES OF CONTROL CHANNELS • Broadcast control channel BCCH • Common control channel CCCH • Dedicated control channel DCCH
![OPERATIONAL CONCEPTS Subscribers are not allocated dedicated channels TCH Hence IDLE OPERATIONAL CONCEPTS • Subscribers are not allocated dedicated channels • TCH • Hence IDLE](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-26.jpg)
OPERATIONAL CONCEPTS • Subscribers are not allocated dedicated channels • TCH • Hence IDLE MODE & DEDICATED MODE Allocated to users only when needed • DEDICATED MODE -- When a full Bi -directional P to P CHL has been allocated during an established call • IDLE MODE -- When MS is powered on (active) without being in dedicated mode
![GSM THREE TYPES OF CONTROL CHANNELS Broadcast control channel BCCH P MP For Freq GSM THREE TYPES OF CONTROL CHANNELS Broadcast control channel BCCH P- MP For Freq](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-27.jpg)
GSM THREE TYPES OF CONTROL CHANNELS Broadcast control channel BCCH P- MP For Freq Correction For Syncronisation Common control channel CCCH For ACCESS Management Dedicated control channel DCCH P- P For Registration , authentication & Handover FCCH SCH BCCH PCH RACH AGCH SDCCH SACCH FACCH
![OPERATIONAL CONCEPTS IDLE MODE ACCESS PROCDURE DEDICATED MODE IDLE MODE FCCH SCH OPERATIONAL CONCEPTS IDLE MODE ACCESS PROCDURE DEDICATED MODE • IDLE MODE ----FCCH ---- SCH](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-28.jpg)
OPERATIONAL CONCEPTS IDLE MODE ACCESS PROCDURE DEDICATED MODE • IDLE MODE ----FCCH ---- SCH ----BCCH • MS O/G Call ----RACH ----AGCH ----SDCCH ----TCH • MS I/C Call ----PCH ----RACH ----AGCH ----SDCCH ----TCH
![GSM RF Interface Other Salient Features Of GSM RF IF Control of GSM – RF Interface Other Salient Features Of GSM RF I/F: - Control of](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-29.jpg)
GSM – RF Interface Other Salient Features Of GSM RF I/F: - Control of Transmitted Power. - Discontinuous Transmission. - Timing Advance. - Diversity. - Frequency Hopping.
![Discontinuous Transmission DTX Speech activity only 40 of time Needs Voice activity Discontinuous Transmission (DTX) • Speech activity only 40% of time. • Needs Voice activity](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-30.jpg)
Discontinuous Transmission (DTX) • Speech activity only 40% of time. • Needs Voice activity detection. • Determination of voice threshold vis-à-vis noise. • Annoying clicks/inefficient DTX. • Generation of Comfort Noise at receiver to avoid the feeling of the set being dead.
![GSM RF Interface Timing Alignment Large distance between BTS and MS GSM – RF Interface Timing Alignment : - Large distance between BTS and MS](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-31.jpg)
GSM – RF Interface Timing Alignment : - Large distance between BTS and MS causes the problem. - Each MS on call is allocated a timeslot on TDMA frame. - The problem occurs when the information transmitted by MS does not reach BTS on allocated timeslot. TDMA Frame 0 1 2 3 4 5 6 7 B –on TS 2 TS 3 TS 2 A –on TS 3 BTS
![GSM RF Interface Timing Advance To counteract problem of Time Alignment GSM – RF Interface Timing Advance : ( To counteract problem of Time Alignment](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-32.jpg)
GSM – RF Interface Timing Advance : ( To counteract problem of Time Alignment ) - MS instructed to do its transmission certain bit-times earlier or later – to reach its timeslot at BTS in right time. - In GSM systems maximum 63 bit-times can be used. - This limits the GSM cell size to 35 Km radius. 0 1 2 3 4 5 6 7 Time Start Sending 0 1 2 3 4 5 6 7
![GSM RF Interface Antenna Diversity Space Diversity Mounting two receiver antenna GSM – RF Interface Antenna Diversity : Space Diversity - Mounting two receiver antenna](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-33.jpg)
GSM – RF Interface Antenna Diversity : Space Diversity - Mounting two receiver antenna physically separated a distance. - Probability of both of them being affected by a deep fading dip at same time is low. - At 900 MHz with antenna spacing of 5 -6 m we get 3 db gain. Polarization Diversity - - Dual polarized antenna – vertical and horizontal arrays. Tx Rx No Diversity Rx (A) Tx Rx ( B) Antenna Diversity
![FREQUENCY HOPPING Change of frequency after every frame in a predetermined manner FREQUENCY HOPPING • Change of frequency after every frame in a pre-determined manner •](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-34.jpg)
FREQUENCY HOPPING • Change of frequency after every frame in a pre-determined manner • SFH improves performance in multi-path fading • Provides interference diversity • Decreases required C/I • Mandatory for MS when requested by BS • FCCH , SCH , BCCH are not hopped • Algorithm : Cyclic or pseudorandom
![GSM RADIO INTERFACE SUMMARY Radio Interface Frequency Bands Specifications GSM - RADIO INTERFACE SUMMARY • Radio Interface • Frequency Bands & Specifications •](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-35.jpg)
GSM - RADIO INTERFACE SUMMARY • Radio Interface • Frequency Bands & Specifications • Multiple Access Method FDMA & TDMA • FDMA /TDMA Frame Representation • Logical Channels Traffic & Control • Operational Concepts • Other Salient Features of RF I/F- DTX, Time Alignment Diversity, Fr. Hopping, Power Control.
![MOBILE COMMUNICATION THANKS MOBILE COMMUNICATION THANKS !!](https://slidetodoc.com/presentation_image_h/05161c696c23e2674b22498fdb9ae34d/image-36.jpg)
MOBILE COMMUNICATION THANKS !!
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