Microsoft PowerPoint - GSM1

1,337 views
1,227 views

Published on

Published in: Business, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
1,337
On SlideShare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
131
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Microsoft PowerPoint - GSM1

  1. 1. Overview of GSM Architecture GSM/ DCS1800 System • Some Histories & Some Background • GSM/DCS1800 System Architecture • High-Level View of Some Scenarios • GSM Time Slot Structure • GSM Logical Channels • GSM Frame Structure • Low-Level View of Some Scenarios • GSM System Diagram& Protocol Stack • Different Between GSM and DCS 1800 Page-2
  2. 2. Milestones of the GSM 1982 1984 1985 1987 1988/89~1991/92 1990 • CEPT decides to establish a Groupe Speciale • Discussion & adoption of a list of • GSM becomes a technical committee within Mobile (GSM) to develop a set of common recommendations to be generated by the group > ETSI & splits up into GSM group 1-4, later standards for a future pan-European cellular 100 recommendations in series of 12 volumes called Special Mobile Group (SMG) 1-4 mobile network • Establishment of 3 work parties to define & • Initial Memorandum of Understanding (MoU)• The GSM specifications for the 900 describe the services offered in a GSM (radio signed by telecommunication network operator MHz are also applied at 1800 MHz interface, signaling protocol, interfaces,…...) organizations band (DCS1800), a PCN applications initiated in the UK 1991 1992 1993 1995 1997 • July:: Planned GSM commercial launch of GSM • The GSM-MoU has 62 members (signatories) in •Over 64 million subscribers service in Europe (MoU plan) delayed to 1992 39 countries worldwide; in addtion 32 potential because of non-availability of type-approved member (observers/applicants) in 19 other terminals countries GSM • GSM networks operational or under Global System for Mobile • Official commercial launch of GSM service in development in 60 countries worldwide, Communication Europe with over 5.4 million subscribers GSM/DCS1800 System (1) Page-3 GSM Services Service Category Service Comments Tele-services O Telephony (Speech) O Full rate (13Kbps) O Emergency calls (speech) O Short Message services: point-to-point O Alphanumeric information: user & point-to-multi-point (cell broadcast) to user & network to all users O Tele-fax O Group 3 Bearer Services O Asynchronous data O 300-9600 bps O Synchronous data O 300-9600 bps O Asynchronous PAD (packet switched, O 300-9600 bps packet assembler/disassembler) access O Alternate speech & data O 300-9600 bps Phase 1 Services Supplementary O Call forwarding Services O Call barring GSM/DCS1800 System (2) Page-4
  3. 3. GSM Services Service Category Service Comments Tele-services O Telephony (Speech) O Half rate (6.5 Kbps) O Short Message services: O General Improvements Bearer Services O Synchronous dedicated packet data O 2400-9600 bps access Supplementary O Calling/connected line identity Services presentation O Calling/connected line identity restriction O Call waiting O Call hold O Multiparty communication closed user group Phase 2 Online charge information Services O Advice of charge GSM/DCS1800 System (3) Page-5 GSM/ DCS1800 System • Some Histories Some Background • GSM/DCS1800 System Architecture • High-Level View of Some Scenarios • GSM Time Slot Structure • GSM Logical Channels • GSM Frame Structure • Low-Level View of Some Scenarios • GSM System Diagram Protocol Stack • Different Between GSM and DCS 1800 Page-6
  4. 4. GSM System Architecture BTS HLR VLR AUC BTS BSC PSTN MS BTS MSC ISDN BTS Data Network BTS BSC OMC BTS Operation Maintenance Subsystem Base Station Subsystem Network Switching Subsystem Public Network MS GSM/DCS1800 System (4) Page-7 GSM System Architecture • Functional Entities of GSM AUC OMC D VLR B HLR C GMSC PSTN F E A EIR MSC BSC Abis (through ISDN protocol) BSC Um BTS MS š BTS š š š AUC Authentication Center HLR Home Location Register š š BTS Base Transceiver Station MSC Mobile Switching Center š š BSC Base Station Controller OMC Operation and Maintenance Center š EIR Equipment Identity Register VLR Visited Location Register GMSC Gateway Mobile Switching Center GSM/DCS1800 System (5) Page-8
  5. 5. Mobile Station • Mobile Station Types – Vehicle-mounted stations – portable stations – handheld stations • Mobile Station Power Classes – Vehicular portable units can be either class I or class II – Handheld units can be class III, IV, V Class Class Max. RF Power (W) Max. RF Power (W) II 20 20 IIII 88 III III 55 IVIV 22 V V 0.8 0.8 GSM/DCS1800 System (6) Page-9 Identities of Mobile Station • Mobile station has three identities – International Mobile Subscriber Identity (IMSI) – International Mobile Equipment Identity (IMEI) – Temporary Mobile Subscriber Identity (TMSI) GSM/DCS1800 System (7) Page-10
  6. 6. Identities of Mobile Station • International Mobile Subscriber Identity – IMSI is assigned to an MS at subscription time – It uniquely identifies a given MS – It contains 15 digits • Mobile Country Code (MCC) – 3 digits (home country) • Mobile Network Code (MNC) – 2 digits (home GSM PLMN) • Mobile Subscriber Identification(MSIN) Mobile Subscriber • National Mobile Subscriber Identity(NMSI) Identification Number (MSIC) – 262 02 454 275 1010 MCC = Germany NMC = private operator D3 private GSM/DCS1800 System (8) Page-11 Identities of Mobile Station • International Mobile Equipment Identity (*#06#) – IMEI uniquely identifies the MS equipment – It is assigned by the equipment manufacturer – It contains 15 digits • Type Approval Code (ATC) – 6 digits • Final Assembly Code (FAC) – 2 digits • Serial Number (SNR) – 6 digits • Spare (SP) – 1 digit GSM/DCS1800 System (9) Page-12
  7. 7. Identities of Mobile Station • Temporary Mobile Subscriber Identity – TMSI is assigned to MS by the Visitor Location Register (VLR) – TMSI uniquely identifies an MS within the area controlled by a given VLR – A maximum of 32 bits can be used for TMSI GSM/DCS1800 System (10) Page-13 Identities of Mobile Station • Subscriber Identity Module Card (SIM card) – IMSI – Authentication Key – Subscriber information – Access control class – Cipher key – Additional GSM services – Location Area Identity – Forbidden PLMN GSM/DCS1800 System (11) Page-14
  8. 8. Base Station Subsystem • Base Station Subsystem (BSS) contains 2 Parts – Base Station Controller (BSC) – Base Transceiver System (BTS) • It contains the Transcoder Rate Adopter Unit (TRAU) – GSM-specific speed encoding decoding is carried out, as well as the rate adaptation function for data • Power class are also classified in a similar way to MS with 8 classes in 3 dB steps from 2.5 W to 320 W GSM/DCS1800 System (12) Page-15 Network and Switching Subsystem • Network and Switching Subsystem contains – Switching functions of the GSM • MSC GMSC – Database required for the subscriber – Mobility management GSM/DCS1800 System (13) Page-16
  9. 9. Operational Maintenance Subsystem • Operational and Maintenance Subsystem – Responsibility • The OMS is responsible for handling system security based on validation of identities of various telecommunication entities. – Performed by • Authentication Center (AUC): The AUC is accessed by HLR to determine whether an MS will be granted services • Equipment Identity Register (EIR): The EIR provides MS information used by the MSC. The EIR maintain a list of legitimate, fraudulent or faulty MSs. • In charge of remote operation and maintenance of PLMN. • Operational and Maintenance Center (OMC) – The functional entity through which the service provider monitors and controls the system. GSM/DCS1800 System (14) Page-17 GSM QoS Requirements • GSM Service Quality Requirements QoS QoS Required Time Required Time Time from switching to service ready Time from switching to service ready 44 sec in the home system and 10 sec in the visiting system sec in the home system and 10 sec in the visiting system Connect time to called network Connect time to called network 44 sec sec Release time to called network Release time to called network 22 sec sec Time to alert mobile of inbound call Time to alert mobile of inbound call 44 sec in firstattempt and 15 sec in final attempt sec in first attempt and 15 sec in final attempt Maximum gap due to handoff Maximum gap due to handoff 150 ms ifif intercell and 100 ms if itracell 150 ms intercell and 100 ms if itracell Maximum one-way speech delay Maximum one-way speech delay 90ms 90ms Intelligibility of speech Intelligibility of speech 90% 90% GSM/DCS1800 System (15) Page-18
  10. 10. GSM/ DCS1800 System • Some Histories Some Background • GSM/DCS1800 System Architecture • High-Level View of Some Scenarios • GSM Time Slot Structure • GSM Logical Channels • GSM Frame Structure • Low-Level View of Some Scenarios • GSM System Diagram Protocol Stack • Different Between GSM and DCS 1800 Page-19 High-Level View of Some Scenarios • GSM Registration Scenarios MS BTS BSC MSC VLR HLR Channel Request Channel activation command Channel activation acknowledge Channel Assignment Location Update Request Authentication Request Authentication Response Comparison of the Authentication parameters Assignment of the new area TMSI Acknowledgement of new area TMSI Entry of the new area identity into VLR HLR Channel Release GSM/DCS1800 System (16) Page-20
  11. 11. GSM Call Flow Scenarios • Call Setup with a Mobile to Land Call – Part I Um A B MS BSS MSC VLR SETUP_REQ Access Subscriber Data 1 2 3 Call Proceeding SUB_DATA_RESP 4 Assign Truck 5 Assign Radio Radio Channel 6 Channel 7 Radio Assignment Truck Radio 8 Complete Assignment complete GSM/DCS1800 System (17) Page-21 GSM Call Flow Scenarios • Call Setup with a Mobile to Land Call – Part II MS MSC PSTN NET_SETUP 1 NET_ALERT 2 Alerting 3 Connect (Answer) 4 Connect 5 6 Connect Acknowledgement GSM/DCS1800 System (18) Page-22
  12. 12. GSM Call Flow Scenarios • Call Release With Mobile to Land Call – Mobile Initiated Um A MS BSS MSC PSTN CALL_DISC 1 NET_REL 2 CALL_REL 3 REL_COMP 4 CLR_COMM 5 CHH_REL 6 CLR_COMP 7 GSM/DCS1800 System (19) Page-23 GSM Call Flow Scenarios • Land to Mobile Call – Part I – Assumption • MS is registered with the system has been assigned a TMSI • MS is in its home system C PSTN MSC HLR VLR INC_CALL 1 GET_ROUT 2 ROUT_INF 3 INCO_CALL 4 PERM_PAGE 5 GSM/DCS1800 System (20) Page-24
  13. 13. GSM Call Flow Scenarios • Land to Mobile Call (Paging) – Part II Um A B MS BSS MSC VLR PERM_PAGE 1 PAGE_MESS 2 CH_REQ 3 DSCH_ASS 4 PAGE_RESP 5 PAGE_RESP 6 PAGE_RESP 7 GSM/DCS1800 System (21) Page-25 GSM Call Flow Scenarios • Handoff – MS scans transmission from surrounding BSs in the spare timeslots • It then reports the measured results back to the fixed network via BS, where the handoff decision is made – Classifications • Internal Handoff – Inter-BSS Handoff • External – Intra-MSC Handoff – Inter-MSC Handoff GSM/DCS1800 System (22) Page-26
  14. 14. GSM Call Flow Scenarios • Handoff – Intra-MSC Handoff GSM/DCS1800 System (22) Page-27 GSM/ DCS1800 System • Some Histories Some Background • GSM/DCS1800 System Architecture • High-Level View of Some Scenarios • GSM Time Slot Structure • GSM Logical Channels • GSM Frame Structure • Low-Level View of Some Scenarios • GSM System Diagram Protocol Stack • Different Between GSM and DCS 1800 Page-28
  15. 15. GSM Time Slot Structure • Frequency Bands and Bandwidth GSM 900 Down-link (BS to MS) • 935 MHz ~ 960 MHz (25 MHz Bandwidth) Up-link (MS to BS) • 890 MHz ~ 915 MHz (25 MHz Bandwidth) Carriers or Channels • Each up-link or down-link has 124 Carriers with a bandwidth of 200 KHz, excluding 2×100 KHz edges of the band • The use of carrier 1 and 124 are optional for operators. 1 2 3 124 100 kHz 200 kHz F u = 890 . 2 + 0 . 2 × ( N − 1 ) MHz 100 kHz F d = 935 . 2 + 0 . 2 × ( N − 1 ) MHz N = 1, 2 , ,124 GSM/DCS1800 System (23) Page-29 Frequency Bands and Bandwidth Down-link (BS to MS) DCS-1800 • 1805 MHz ~ 1880 MHz (75 MHz Bandwidth) Up-link (MS to BS) • 1710 MHz ~ 1785 MHz (75 MHz Bandwidth) Carriers or Channels • Each up-link or down-link has 374 Carriers with a bandwidth of 200 KHz, excluding F u = 1710 + 0 . 2 × ( N − 1 ) MHz F d = 1805 + 0 . 2 × ( N − 1 ) MHz 512 ≤ N ≤ 885 GSM/DCS1800 System (24) Page-30
  16. 16. Frequency Bands and Bandwidth • FDMA/TDMA Structure • The total bandwidth is divided into 124×200 kHz bands (FDMA) • Each 200 kHz band can support maximum 8 users (TDMA) • The GSM can support up to 992 (124×8) simultaneous users with the full- rate speech coder. TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 Freq. #1 Channel #1 Channel #2 Channel #3 Channel #4 Channel #5 Channel #6 Channel #7 Channel #8 Freq. #2 Channel #1 Channel #2 Channel #3 Channel #4 Channel #5 Channel #6 Channel #7 Channel #8 Freq. #124 Channel #1 Channel #2 Channel #3 Channel #4 Channel #5 Channel #6 Channel #7 Channel #8 GSM/DCS1800 System (24) Page-31 Frequency Bands and Bandwidth Time-Division Duplex (TDD) • No need for a dedicated duplex stage (duplexer); the only requirements are to have a fast switching synthesizer, RF filter paths fast antenna switches available • Increased battery life or reduced battery weight 0 1 2 3 4 5 6 7 BS Transmits 5 6 7 0 1 2 3 4 MS Transmits GSM/DCS1800 System (25) Page-32
  17. 17. Frequency Bands and Bandwidth Pulsed Transmission • The tendency for a pulsed radio to disturb neighboring frequency channels is called AM splash. 4 dB -1 dB -6 dB -30 dB -70 dB 10µ s 8µ s 10µ s 542.8µ s (147 bits) 10µ s 8µ s 10µ s GSM/DCS1800 System (26) Page-33 GSM Time Slot Structure • Time Slot Structure or Burst types in GSM – Normal Bursts – Random Access Burst – Frequency Correction Bursts – Synchronization Bursts GSM/DCS1800 System (27) Page-34
  18. 18. GSM Time Slot Structure Tail Bits (TB) • Used as a guard time. this time covers the periods of uncertainty during the ramping up down of the power bursts form the MS in accordance with the power-versus-time template Stealing Flag • Used as an indication to the decoder of whether the incoming burst is carrying signaling data or user data Stealing Training Stealing TB Coded Data Coded Data TB Guard Time Flag Sequence Flag (3 bits) (57 bits) (57 bits) (3 bits) (8.25 bits) (1 bits) (26 bits) (1 bits) 148 bits = 546.12 µ s Normal Burst Training Sequence • Used to compensate for the effects of multi-path fading. There are 8 different sequences defined in GSM. GSM/DCS1800 System (28) Page-35 GSM Time Slot Structure TB Synchronization Sequence Coded Data TB Guard Time (8 bits) (41 bits) (36 bits) (3 bits) (68.25 bits) 88 bits = 324.72 µ s Random Access Burst GSM/DCS1800 System (29) Page-36
  19. 19. GSM Time Slot Structure TB Fixed bit Sequence TB Guard Time (8 bits) (142 bits) (3 bits) (8.25 bits) 148 bits = 546.12 µ s Frequency- Correction Burst GSM/DCS1800 System (30) Page-37 GSM Time Slot Structure Synchronization TB Coded Data Coded Data TB Guard Time Sequence (3 bits) (39 bits) (39 bits) (3 bits) (8.25 bits) (264bits) 148 bits = 546.12 µ s Synchronization Burst GSM/DCS1800 System (31) Page-38
  20. 20. GSM/ DCS1800 System • Some Histories Some Background • GSM/DCS1800 System Architecture • High-Level View of Some Scenarios • GSM Time Slot Structure • GSM Logical Channels • GSM Frame Structure • Low-Level View of Some Scenarios • GSM System Diagram Protocol Stack • Different Between GSM and DCS 1800 Page-39 GSM Logical Channels • Classifications Logic Channel Traffic Channel Control Channel Cell Broadcast (TCH) (CCH) Channel (CBCH) TCH/Full TCH/Half Broadcast Channel Common Control Dedicated Control (TCH/F) (TCH/H) (BCH) Channel (CCCH) Channel (DCCH) Freq. Correction Paging Associated Control Stand-Alone Dedicated Channel (FCCH) Channel (PCH) Channel (ACCH) Control Channel (SDCCH) Synchronization Access Grant Slow Associated Fast Associated SDCCH/4 Channel (SCH) Channel (AGCH) Control Channel Control Channel (SACCH) (FACCH) SDCCH/8 Broadcast Control Random Access Channel (BCCH) Channel (RACH) FACCH/F FACCH/H SACCH/TF SACCH/TH SACCH/C4 SACCH/C8 GSM/DCS1800 System (32) Page-40
  21. 21. GSM Logical Channels • Traffic Channel – Are used to transmit user information (speech or data) – 2 categories • TCH/Full (TCH/F) – Allows the transmission of 13 Kbps of speech • TCH/Half (TCH/H) – Allows the speech coded at a half rate Logic Channel Traffic Channel Control Channel Cell Broadcast (TCH) (CCH) Channel (CBCH) TCH/Full TCH/Half (TCH/F) (TCH/H) GSM/DCS1800 System (33) Page-41 GSM Logical Channels • Control Channel (CCH) – Are used to transmit control and signaling information • Broadcast Channel (BCH) • Common Control Channel (CCH) • Dedicated Control Channel (DCCH) Logic Channel Control Channel Traffic Channel Cell Broadcast (CCH) (TCH) Channel (CBCH) Broadcast Channel Common Control Dedicated Control (BCH) Channel (CCCH) Channel (DCCH) GSM/DCS1800 System (34) Page-42
  22. 22. GSM Logical Channels • Control Channel (CCH) – Broadcast Channel (BCH) • Are point-to-multipoint, downlink-only channels • Classification – Broadcast Control Channel (BCCH) Logic Channel – Frequency Correction Channel (FCCH) – Synchronization Channel (SCH) Control Channel (CCH) Dedicated Control Broadcast Channel Common Control Channel (DCCH) (BCH) Channel (CCCH) Freq. Correction Synchronization Broadcast Control Channel (FCCH) Channel (SCH) Channel (BCCH) GSM/DCS1800 System (35) Page-43 GSM Logical Channels • Control Channel (CCH) – Common Control Channel (CCH) • Are point-to-multipoint, downlink-only channels that are used for paging access except for RACH. • Classifications – Paging Channel (PCH) Logic Channel – Access Grant Channel (AGCH) – Random Access Channel (RACH) Control Channel (CCH) Common Control Broadcast Channel Dedicated Control Channel (CCCH) (BCH) Channel (DCCH) Paging Access Grant Random Access Channel (PCH) Channel (AGCH) Channel (RACH) GSM/DCS1800 System (36) Page-44
  23. 23. GSM Logical Channels • Control Channel (CCH) – Dedicated Control Channel (DCCH) • Are bidirectional, point-to-point channels • Classifications – Stand-Alone Dedicated Control Channel (SDCH) – Associated Control Channel (ACCH) Logic Channel • Slow Associated Control Channel (SACCH) • Fast Associated Control Channel (FACCH) Control Channel (CCH) Dedicated Control Broadcast Channel Common Control Channel (DCCH) (BCH) Channel (CCCH) Associated Control Stand-Alone Dedicated Channel (ACCH) Control Channel (SDCCH) GSM/DCS1800 System (37) Page-45 GSM/ DCS1800 System • Some Histories Some Background • GSM/DCS1800 System Architecture • High-Level View of Some Scenarios • GSM Time Slot Structure • GSM Logical Channels • GSM Frame Structure • Low-Level View of Some Scenarios • GSM System Diagram Protocol Stack • Different Between GSM and DCS 1800 Page-46
  24. 24. GSM Frame Structure • I : TCH/FS + FACCH/FS + SACCH/FS • II : TCH/HS(0,1) + FACCH/HS(0,1) + SACCH/HS(0,1) • III: TCH/HS(0) + FACCH/HS(0) + SACCH/HS(0) + TCH/HS(1) + FACCH/HS(1) + SACCH/HS(1) Channel • IV: FCCH + SCH + CCCH + BCCH Combinations • V : FCCH + SCH + CCCH + BCCH + SDCCH/4 + SACCH/4 (I) • VI : CCCH + BCCH • VII: SDCCH/8 + SACCH/8 Each channel combination requires one single physical channel GSM/DCS1800 System (38) Page-47 GSM Frame Structure Traffic Channel Frame Structure (26-multi-frame) Channel Combinations (II) • I : TCH/FS + FACCH/FS + SACCH/FS T=TCH, S=SACCH, I=Idle T T S T T T T T T T T T T T T I T0 T1 T2 T3 T4 T5 T6 T7 T8 T9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Frames = 120 ms GSM/DCS1800 System (39) Page-48
  25. 25. GSM Frame Structure Traffic Channel Frame Structure (26-multi-frame) Channel Combinations (III) • II : TCH/HS(0,1) + FACCH/HS(0,1) + SACCH/HS(0,1) • III: TCH/HS(0) + FACCH/HS(0) + SACCH/HS(0) + TCH/HS(1) + FACCH/HS(1) + SACCH/HS(1) t t t t t T t S T t T t T t T t T t T t s T0 T2 T4 T6 T8 1 3 5 7 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Frames = 120 ms T=TCH1 , S=SACCH1 , t=TCH2, s=SACCH2 GSM/DCS1800 System (40) Page-49 GSM Frame Structure Signaling Channel Frame Structure (51-multi-frame) Channel Combinations (IV) • IV : FCCH + SCH + CCCH + BCCH BCCH CCCH F S CCCH F S CCCH F S CCCH F S CCCH I F0 S1 T2 2~5 6 ~ 9 10 11 12~19 20 21 22~29 30 31 32~39 40 41 42~49 50 Down-Link :: F=FCCH, S=SCH, B=BCCH, C=CCCH (PCH,AGCH), I=Idle R R R R R R R R R R0 R1 10 11 20 21 30 31 40 41 50 Up-Link :: R=RACH 51 Frames = 235.38 ms GSM/DCS1800 System (41) Page-50
  26. 26. GSM Frame Structure Signaling Channel Frame Structure (51-multi-frame) Channel Combinations (V) • V : FCCH + SCJ + CCCH + BCCH + SDCCH/4 + SACCH/4 GSM/DCS1800 System (42) Page-51 GSM Frame Structure Signaling Channel Frame Structure (51-multi-frame) Channel Combinations (VI) VI : CCCH + BCCH • Used as a BS has to manages a huge number of transceiver which means the number of CCCHs provided by combination IV is not enough to handle the network • Assign additional control channels in combination IV. While combination IV always occupies time slot 0, combination VI is assigned to time slot 2, 4, or 6. • The combination VI multi-frame structure is similar to combination IV. GSM/DCS1800 System (43) Page-52
  27. 27. GSM Frame Structure Signaling Channel Frame Structure (51-multi-frame) Channel Combinations (VII) • VII : SDCCH/8 + SACCH/8 GSM/DCS1800 System (44) Page-53 GSM Frame Structure • Frame Hierarchical Structure – Hyper-frame,super-frame,multi-frame,frame,time slot – A time slot carries 156.25 bits Stealing Stealing 156.25 bits Tail Data Bit Training Bit Data Tail Guard GSM Time-Slot 3 57 1 26 1 57 3 8.25 (Normal Burst) GSM Frame (4.615 ms) 0 1 2 3 4 5 6 7 1 Multi-frame=26 frame (120 ms) 0 1 2 …… 23 24 25 1 Multi-frame=51 frame 0 1 2 …… 47 48 49 50 (3060/13 ms) GSM Super-frame (26×51=1326 frame 0 1 2 …… 47 48 49 =6.12 sec) GSM hyper-frame (3.48 hours) 0 1 2 …… 2045 2046 2047 GSM/DCS1800 System (45) Page-54
  28. 28. GSM Frame Structure • T1, T2 T3 Counters – T1 counter counts the super-frames • Whenever a super-frame is completed, T1 is incremented by 1 0 ≤ T1 ≤ 2047 – T2 counter counts the speech frames, which only occur in 26 multi-frame structure 0 ≤ T2 ≤ 25 – .T3 counter counts the signaling frames, which are 51-multi-frame structure 0 ≤ T3 ≤ 50 GSM/DCS1800 System (46) Page-55 GSM Frame Structure B T S TDMA Frame 0 1 2 3 21 22 23 24 25 0 1 2 3 46 47 48 49 50 0 1 2 3 46 47 48 49 50 0 1 2 3 21 22 23 24 25 T T T T T Example of How a 26 MS Behaves multi-frame 51 multi-frame B S B S B S B S B S GSM/DCS1800 System (47) Page-56
  29. 29. GSM Frame Structure When a MS is turned on, it has to orient itself within the network 1. It synchronizes itself in frequency 2. It synchronizes itself in time 3. It reads the system cell data from base channel or more specifically from BCCH To find the frequency where the FCCH, SCH BCCH are being transmitted The MS uses the SCH for this purpose. Since it has found the Synchronization FCCH, so it already knows that SCH will be follow in the next With the Network TDMA frame GSM/DCS1800 System (48) Page-57 GSM/ DCS1800 System • Some Histories Some Background • GSM/DCS1800 System Architecture • High-Level View of Some Scenarios • GSM Time Slot Structure • GSM Logical Channels • GSM Frame Structure • Low-Level View of Some Scenarios • GSM System Diagram Protocol Stack • Different Between GSM and DCS 1800 Page-58
  30. 30. GSM Location Updating Scenarios Logical Channel MS BS RACH Channel Request AGCH Channel Assignment Request for location updating. This is already SDCCH transmitted on the assigned channel SDCCH Authentication Request from the network SDCCH Authentication Response from the MS SDCCH Request to transmit in the ciphered mode Acknowledgement of the ciphered mode SDCCH Confirmation of the location updating SDCCH including the optional assignment TMSI SDCCH Acknowledgement of the new location the temporary identity SDCCH Channel Release from the network GSM/DCS1800 System (49) Page-59 GSM Call Establishment Scenarios Mobile Terminated Call Logical Channel MS BS PCH Paging of the MS RACH Channel Request AGCH Channel Assignment SDCCH Answer to the paging from the network SDCCH Authentication Request from the network SDCCH Authentication Response from the MS SDCCH Request to transmit in the ciphered mode SDCCH Acknowledgement of the ciphered mode SDCCH Set up message for the incoming call SDCCH Confirmation SDCCH Assignment of a traffic channel FACCH Acknowledgement of the traffic channel FACCH Alerting (now the caller gets the ringing sound) FACCH Connect message when the MS is off-hook FACCH Acceptance of the connect message TCH Exchange of user data (speech) GSM/DCS1800 System (50) Page-60
  31. 31. GSM Logical Channels • Logic Control Channel Structure BCCH – Classify by call setup BCH FCCH (Broadcast Channel) (Before Call Set-up) SCH CAC (Common Access Channel) CCCH PCH CCH (Common Control Channel) (During Call Set-up) RACH SDCCH AGCH USC SACCH (User Specific Channel) (After call set-up) FACCH GSM/DCS1800 System (51) Page-61 GSM/ DCS1800 System • Some Histories Some Background • GSM/DCS1800 System Architecture • High-Level View of Some Scenarios • GSM Time Slot Structure • GSM Logical Channels • GSM Frame Structure • Low-Level View of Some Scenarios • GSM System Diagram Protocol Stack • Different Between GSM and DCS 1800 Page-62
  32. 32. GSM System Diagram • GSM System Block Diagram – Information Processing – RF Baseband Processing Digitizing Source deconding Speech source coding D/A Speech Channel coding Channel decoding Interleaving De-interleaving Encryption Decryption Burst formatting Burst deformatting MS Modulation Demodulation MSC GSM/DCS1800 System (52) Page-63 GSM System Diagram • Source (Speech) Coding – Mobile Station (Analog Signal) • Low-pass filter, then A/D converter, then RPE-LTP speech encoder – MSC (Base Station) (Digital Signal) • 8-bit A-law to 13-bit Uniform converter, then RPE-LTP speech encoder Mobile Station 13×8000=104 kbps 13 kbps Low-Pass Filter A/D Converter RPE-LTP Encoder Analog Signal To Channel Encoder 13 kbps MSC 8bit A-law to 13bit 13 ×8000=104 kbps RPE-LTP Encoder Digital Signal Uniform Converter To Channel Encoder GSM/DCS1800 System (53) Page-64
  33. 33. GSM System Diagram • Source (Speech) Coding – Regular Pulse Excited Long-Term Prediction (RPE-LTP) Encoder • Input has bit rate of 104 kbps • Has net bit rate of 13 kbps • Output from RPE-LTP 260 bits every 20 ms bits per 55ms bits per ms Bits per 20 ms Bits per 20 ms Linear Prediction Coding (LPC) filter Linear Prediction Coding (LPC) filter 36 36 Long Term Prediction (LTP) filter Long Term Prediction (LTP) filter 99 36 36 Excitation Signal Excitation Signal 47 47 188 188 Total Total 260 260 Class I I Class 182 182 (class Ia=50, class Ib=132) (class Ia=50, class Ib=132) Class II Class II 78 78 GSM/DCS1800 System (54) Page-65 GSM System Diagram RPE-LTP Speech Encoder 260 bits 50 bits 53 bits 20 ms Cyclic Redundancy Encoder Class I: 182 bits 132 bits 4 tail bits all equal to zero 185 bits 189 bits 1/2 Convolutional Encoder 20 ms Speech Class II: 78 bits 378 bits Channel 456 bits Coding GSM/DCS1800 System (55) Page-66
  34. 34. GSM System Diagram • Structure of Interleaver – interleaving speech frames onto TDMA frame GSM/DCS1800 System (56) Page-67 GSM System Diagram TCH/F9.6 • 9.6 Kbps refers to the user’s transmission rate, the actual rate is brought up to 12 Kbps through channel coding in the terminal equipment; that is, 12 Kbps is the rate delivered to the MS. User Information 240 bits Add 4 “0” bits 20 ms 1/2 Convolutional Encoder 488 coded bits Data Channel Coding (I) Puncturing of 32 coded bits 20 ms 456 bits GSM/DCS1800 System (57) Page-68
  35. 35. GSM System Diagram Structure of Interleaver • The blocks are spread over 22 bursts. Even though the interleaving covers 22 bursts, it is referred to as a 19-bursts interleaving plan. • 456 bits = 16 parts of 24 bits each (16× 24= 384) + 2 parts of 18 bits each (2× 18=36) + 2 parts of 12 bits each (2× 12=24) + 2 parts of 6 bits each (2× 6=12) • A burst (time slots) contains information from either 5 or 6 consecutive data blocks; ? @ that is, 4 parts of 24 bits each and 1 part of 18 bits (96 + 18 = 114) or 4 parts of 24 bits each and 1 part of 12 bits each and 1 part of6 bits each (96+12+6=114) • 1st 22nd burst contains 6 bits each (12 bits); 2nd 21st burst contain 12 bits each (24 bits); 3rd 20th carry 18 bits each (36 bits) we have 6 bursts. We need another 16-burst. We then put 24 bits in each of the 4th~19the bursts (384 bits). Data Channel Coding (II) GSM/DCS1800 System (58) Page-69 GSM System Diagram Channel Coding of Signaling Channels • Signaling information contains a maximum of 184 bits. It does NOT make a difference whether the type of signaling information to be transmitted is mapped onto a BCCH, PCH, SDCCH or SACCH. The format always stays the same. • Special format are reserved for the SCH RACH • FCCH requires no coding at all Signaling Information 184 bits Block Encoder (Fire Code) Signaling Channel Fire coded adds 40 parity bits to the 184 bit Coding (I) = 224 fire-coded bits, then adds 4 “0” bits 1/2 Convoluational Encoder 456 bits GSM/DCS1800 System (59) Page-70
  36. 36. GSM System Diagram Structure of Interleaver Bit Number of the Coded Bits Bit Number of the Coded Bits Position within the frame structure Position within the frame structure 00 8……448 8……448 Even bits of burst N Even bits of burst N 11 9……449 9……449 Even bit of burst N+1 Even bit of burst N+1 22 10……450 10……450 Even bit of burst N+2 Even bit of burst N+2 33 11……451 11……451 Even bit of burst N+3 Even bit of burst N+3 Signaling 44 12……452 Odd bits of burst N+4 Channel 12……452 Odd bits of burst N+4 Coding (II) 55 13……453 13……453 Odd bits of burst N+5 Odd bits of burst N+5 66 14……454 14……454 Odd bits of burst N+6 Odd bits of burst N+6 77 15……455 15……455 Odd bits of burst N+7 Odd bits of burst N+7 GSM/DCS1800 System (60) Page-71 GSM System Diagram GMSK • is a constant-envelop variety of modulation it lacks of AM in the carrier with a consequent limiting of the occupied bandwidth. • The constant amplitude of the GMSK signal makes it suitable for use with high-efficiency amplifiers. Modulation (I) GSM/DCS1800 System (61) Page-72
  37. 37. GSM Protocol Stack Signaling Architecture MS BTS BSC MSC CM CM Layer MM MM 3 RR BSSMAP/ RR BSSMAP DTAP DTAP RR BTSM BTSM SCCP SCCP LAPDm LAPDm LAPD LAPD General View of GSM protocol Layer 1 Layer 1 Layer 1 Layer 1 MTP MTP Um Abis A GSM/DCS1800 System (62) Page-73 GSM Protocol Stack Responsibilities of LAPD/LAPDm • Organization of Layer 3 information into frames • Peer-to-peer transmission of signaling data in defined frame formats • Recognition of frame formats • Establishment, maintenance termination of one or more data links on signaling channels • (Un)Acknowledgement of transmission reception of numbered information frames (I- frames) • Unacknowledge transmission reception of unnumbered information frames (UI-frames) GSM protocol (I) Layer 2 (Data Link Layer) GSM/DCS1800 System (63) Page-74
  38. 38. GSM Protocol Stack Layer 2 (Data Link Layer) Address Field Control Field Length Indication Fill Field Format A (variable length) (8 bits) (variable length) (variable length) Address Field Control Field Length Indication Information Field Fill Field Format B (variable length) (8 bits) (variable length) (variable length) (variable length) GSM protocol (II) Frames Format • 4 types of formats: A, B, Abis, Bbis • The bis designation is sometimes written as a prime mark (Abis = A’) GSM/DCS1800 System (64) Page-75 GSM Protocol Stack Layer 2 (Data Link Layer) Format Abis Length Indication (variable length) Fill Field (variable length) Length Indication Information Field Fill Field Format Bbis (variable length) (variable length) (variable length) GSM protocol (III) Frames Format • 4 types of formats: A, B, Abis, Bbis • The bis designation is sometimes written as a prime mark (Abis = A’) GSM/DCS1800 System (65) Page-76
  39. 39. GSM Protocol Stack Network Layer • Also referred to as the “signaling layer” • Use a protocol that contains all the functions details necessary to establish, maintain then terminate mobile connections for all the services offered within a GSM.. The network layer also provides control functions to support additional services such as supplementary services short message services 3 sub-layers • Radio Resource Management (RR) • Mobility Management (MM) • Connection Management (CM) GSM protocol (IV) Layer 3 (Network Layer) GSM/DCS1800 System (66) Page-77 GSM Protocol Stack Radio Resource Management sub-layer (RR sub-layer) is responsible for • The management of the frequency spectrum • The GSM’s reactions to the changing radio environment • Everything related to maintaining a clear channel between the system and the MS • Handoff from one cell to another Procedures for the RR sub-layer used to cover these tasks • Channel assignment • Channel release • Channel change handoff procedure • Change of channel frequencies, hopping sequences (hopping algorithms) and frequency tables • Measurement reports from the MS GSM protocol • Power control and timing advance (V) • Cipher mode setting Layer 3 (Network Layer) GSM/DCS1800 System (67) Page-78
  40. 40. GSM Protocol Stack Mobility Management sub-layer (MM sub-layer) is responsible for • cope with all the effects of handling a mobile user that are not directly related to the radio function such as • Support of user mobility, registration, and management of mobility data • Checking the user and equipment identity • Checking if the user is allowed to use the services and what kind of extra services are allowed • Support of user confidentiality (registering the user under a TMSI) • Provision of user security • Provision of an MM connection to the CM sublayer Procedures for the MM sub-layer used to cover these tasks • Location Update procedure GSM protocol • Periodic updating (VI) • authentication procedure • IMSI attach detach procedure. • TMSI reallocation procedure Layer 3 (Network Layer) • Identification procedure GSM/DCS1800 System (68) Page-79 GSM Protocol Stack Connection Management sub-layer (CM sub-layer) is responsible for • It manages all the functions necessary for circuit-switched call control there are other entities within the CM sub-layer to cope with providing supplementary services SMS Procedures for the CM sub-layer used to cover these tasks • Call establishment procedures for mobile-originated calls • Call establishment procedure for mobile-terminated call • Changes of transmission mode during an ongoing call (incall modification) • Call reestablishment after interruption of an MM connection • Dual-tone Multi-frequency (DTMF) control procedure for DTMF GSM protocol transmission. (VII) Layer 3 (Network Layer) GSM/DCS1800 System (69) Page-80
  41. 41. GSM Protocol Stack Layer 3 (Network Layer) Message Structure Double Check the frame format ??? Protocol Information Elements Information Elements TI flag TI 0 Message Type Discriminator “Mandatory” “Optional” (1 bit) (3 bits) (1 bit) (7 bits) (4 bits) (variable bytes) (variable bytes) TI:: Transaction Identifier GSM protocol (VIII) GSM/DCS1800 System (70) Page-81 GSM Protocol Stack Layer 3 (Network Layer) Message Structure Protocol Information Elements Information Elements TI flag TI 0 Message Type Discriminator “Mandatory” “Optional” (1 bit) (3 bits) (1 bit) (7 bits) (4 bits) (variable bytes) (variable bytes) It is used to distinguish between (possible) multiple parallel CM connections and between the various transactions taking place over these simultaneous CM connections GSM protocol (IX) GSM/DCS1800 System (71) Page-82
  42. 42. GSM Protocol Stack Layer 3 (Network Layer) Message Structure Protocol Information Elements Information Elements TI flag TI 0 Message Type Discriminator “Mandatory” “Optional” (1 bit) (3 bits) (1 bit) (7 bits) (4 bits) (variable bytes) (variable bytes) PP ro to c o l ro to c o l PP ro to c o lD is cc rim in a to r ro to c o l D is rim in a to r R aa d ioR ee s o u rc eM gg m t R d io R s o u rc e M m t 00 11 0 11 0 M oo b ilityM gg m t M b ility M m t 00 1 0 1 101 C aa llC oo n tro l C ll C n tro l 00 0 11 0 11 SS h o rtM ee s s a g eSS erv ic e h o rt M s s a g e erv ic e 11 0 0 1 001 GSM protocol SS u p p le m e n ta rySS e rv ic e u p p le m e n ta ry e rv ic e 11 0 11 0 11 (X) Te s s tPP ro c e d u re Te t ro c e d u re 1111 1111 A lllloo th e rvv a lu eaa reres ee rv ed A th e r a lu e re res rv ed GSM/DCS1800 System (72) Page-83 GSM Protocol Stack Layer 3 (Network Layer) Message Structure Protocol Information Elements Information Elements TI flag TI 0 Message Type Discriminator “Mandatory” “Optional” (1 bit) (3 bits) (1 bit) (7 bits) (4 bits) (variable bytes) (variable bytes) • It indicates the function of the Layer 3 message • Uses only low 6 bits for addressing 64 different message in a protocol, another bit is used a send sequence variable may be used for MM and CM GSM protocol messages (XI) GSM/DCS1800 System (73) Page-84
  43. 43. GSM Protocol Stack Layer 3 (Network Layer) Message Structure Protocol Information Elements Information Elements TI flag TI 0 Message Type Discriminator “Mandatory” “Optional” (1 bit) (3 bits) (1 bit) (7 bits) (4 bits) (variable bytes) (variable bytes) There are 4 possible combination of Information Element • Mandatory fixed length • Mandatory variable length • Optional fixed length • Optional variable length GSM protocol (XII) GSM/DCS1800 System (74) Page-85 GSM Protocol Stack Layer 3 (Network Layer) Example of a Call Establishment Sequence M S Transm its N etw ork Transm its C hannel R equest Ö Õ Im m ed iate Assignm ent C onnectio n M ana ge m ent Ö Service R eq uest Õ A uthentication R eq uest A uthentication R esponse Ö Õ C ip he ring M ode C o m ma nd C ip he ring M ode C o m plete Ö Setup Ö Õ C all proceed ing GSM protocol Õ Assignm ent com ma nd (XIII) Assignm ent C om plete Ö Õ A lerting Õ C onnect C onnect A cknow led ge Ö GSM/DCS1800 System (75) Page-86
  44. 44. Digital Cellular System (DCS)-1800 • General Description – As a European ETSI standard for PCN – Based on GSM technology but configured around a hand-portable • Based on GSM technology to overcomes the development problems • Lower power mobile station smaller cell size – cell radius ≤ 1 km in a dense urban environment – cell radius ≤ 5 km in the rural environment GSM/DCS1800 System (76) Page-87 Digital Cellular System (DCS)-1800 • Technical Description – The allocated bandwidth • 1710~1880 MHz providing 75 MHz duplex bands with a 20 MHz spacing • The BTS links to the BSC may use 38 GHz radio to avoid laying costly underground cable links – Mobile and Base Station Power Class Class Max. RF Power (W) CC a a s s l l ss M a a x .RR F PP o w e r( W ) ) M x . F o w e r (W Class Max. RF Power (W) II 11 II 22 0 ~ ( ≤ 44 0 ) 0~ ( 0) ≤ II 0.25 II I I 11 0 ~ ( ≤≤ 2 0 ) 0~ ( 20) II 0.25 III I II 55 ~ ( ≤≤ 1 0 ) ~ ( 10) IV 22 .5 ~ ( ≤ 55 ) .5 ~ ( ) IV ≤ Mobile Station Base Station GSM/DCS1800 System (77) Page-88
  45. 45. Digital Cellular System (DCS)-1800 • DCS1800 vs. GSM – DCS-1800 provides a maximum of 375 radio channels compared to 124 for GSM-900 – DCS-1800 is designed to support hand-portable terminal with a transmit power not exceeding 1 W GSM/DCS1800 System (78) Page-89 GSM/ DCS 1800 in Taiwan (F^(gš (F^(gš í!Kh í!Kh ݋*„ ݋*„ Çï Çï Äe^Õ Äe^Õ »K »K AMPS 090, 091 »K AMPS 090, 091 »K GSM 900 0932, 0933 »K GSM 900 0932, 0933 »K DCS 1800 0937 ój æ‹^ò »K DCS 1800 0937 ój æ‹^ò »K DCS 1800 0935 òñ^Õ »K DCS 1800 0935 òñ^Õ »K DCS 1800 0936  Õ^ò K DCS 1800 0936  Õ^ò K DCS 1800 09380 ~~09383 6!^Õ ÄK DCS 1800 09380 09383 6!^Õ ÄK DCS 1800 09384 ~~09386 6!^Õ ûK DCS 1800 09384 09386 6!^Õ ûK DCS 1800 09387 ~~90389 òñ^Õ K DCS 1800 09387 90389 òñ^Õ K GSM 900 09310 ~~09313 6Õ^ò ÄK GSM 900 09310 09313 6Õ^ò ÄK GSM 900 09314 ~~09316 h^Õ ûK GSM 900 09314 09316 h^Õ ûK GSM 900 GSM 900 09317 ~~09319 09317 09319 GSM/DCS1800 System (79) Page-90

×