Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Modul 4 signalling dimensioning

1,809 views

Published on

Explain 2G signalling and dimensioning of it.

Published in: Education, Technology, Business
  • Be the first to comment

Modul 4 signalling dimensioning

  1. 1. GSM-GPRS Operation Signalling Dimensioning Module 4
  2. 2. kris.sujatmoko@gmail.com 2 Outline  Channel Configuration  SDCCH Capacity  Paging Capacity  LA Size
  3. 3. GSM-GPRS Operation Channel Configuration
  4. 4. 4 Hierarchy Of Channel kris.sujatmoko@gmail.com
  5. 5. 5 MS Mode Search for Frequency Correction Burst Search for Synchronisation sequence Read System Informations listen for Paging send Access burst wait for signalling channel allocation Call setup traffic channel is assigned Conversation Call release FCCH SCH BCCH PCH RACH AGCH SDCCH FACCH TCH FACCH idle mode “off” state dedicated mode idle mode kris.sujatmoko@gmail.com
  6. 6. 6 0 7 ts0=bcch/pch/agchts1=sdcch/8 0 7 ts0=bch/sdcch/4/pch/agch Combined Configuration Time slot 0 contains 1 BCCH, 3 CCCH and 4 SDCCH 0 7 ts0=bcch/pch/agch/sdcch/4 ts1=sdcch/8 Non-Combined Configuration Time slot 0 contains 1 BCCH, 9 CCCH Time Slot x (<>0 of BCCH TRX) contains 8 SDCCH Hybrid Configuration Time slot 0 contains 1 BCCH, 3 CCCH, and 4 SDCCH Time Slot x (<>0 of BCCH TRX) contains additional 8 SDCCH Configuration of Signalling Channels kris.sujatmoko@gmail.com
  7. 7. 7 Configuration Of Signalling Channels – CCH Downlink kris.sujatmoko@gmail.com
  8. 8. 8 Configuration Of Signalling Channels – CCH Downlink kris.sujatmoko@gmail.com
  9. 9. 9 Configuration Of Traffic Channel - TCH kris.sujatmoko@gmail.com
  10. 10. 10 r r rr r r r fr rr r r r r r rr r r rr fr r r r r rr r r r fr r r r rr r r rr fr r r r rr r rr Uplink f s bb bbc fc fc scccc cc ccfc fscccc cc cc f fcccc cc cc fs fcccc cc ccs Downlink 51 TDMA frames = 235ms r Time Slot 0 CHANNELS f = FCCH b = BCCH r = RACH s = SCH/SACCH c = CCCH t = SDCC Non-Combined Configuration BCCH/CCCH Multiframe kris.sujatmoko@gmail.com
  11. 11. 11 CHANNELS t = SDCCH/8 s = SACCH/8 t t tt t t t ft tt t t t t t tt t t tt ft t t t t tt t t t fssss ss s ss fssssss ss ss sss fs ss s t tt t t ts ft t t t t tt t t t ft t t t tt t t tt ft t t t tt t tt Downlink Uplink t t 51 TDMA frames = 235 ms s 1. 2. 3. 5. 6. 7. 8.4. Time Slot 1 Non-Combined SDCCH/8 Multiframe kris.sujatmoko@gmail.com
  12. 12. 12 Channel Combination  The following combinations of logical channel types are allowed for the radio timeslots and specified by GSM (Rec. 05.02):  TCH/F + FACCH/F + SACCH/TF  TCH/H + FACCH/H + SACCH/TH  SDCCH/8 + SACCH/C8  FCCH + SCH + BCCH + CCCH (TS 0)  FCCH + SCH + BCCH + CCCH + SDCCH/4 + SACCH/C4 (TS 0)  BCCH + CCCH  SDCCH/8 + SACCH/8 + CBCH  FCCH + SCH + BCCH + CCCH + SDCCH/4 + SACCH/C4 + CBCH (TS 0) kris.sujatmoko@gmail.com
  13. 13. 13 Channel Configuration - Combined kris.sujatmoko@gmail.com
  14. 14. 14 Channel Configuration - Separated kris.sujatmoko@gmail.com
  15. 15. 15 Channel Configuration - Hybrid kris.sujatmoko@gmail.com
  16. 16. 16 SDCCH Dimensioning  SDCCH used for:  Call setup signalling  Short message service (SMS)  Location update (LU)  IMSI attached/detached kris.sujatmoko@gmail.com
  17. 17. 17 SDCCH Dimensioning (2) kris.sujatmoko@gmail.com
  18. 18. 18 SDCCH Dimensoning (2)  TCH load per subscriber = [ # of call attempts per sub per hour* %MOC + # of call attempts per sub per call*%MTC*(1-%no response)*(1-% no answer)*%MTC success] * mean call duration / 3600 = [ 1.1 * 60% + 1.1 * 40% * (1-32.5%) * (1-13.5%) * 54%] * 115/3600 = 0.026 Erlang  SDCCH load per subscriber = [number of call attempts*setup signalling + #LU per sub per hour*duration for loc update] / 3600 = [1.1 * 3 + 2.2 * 5] / 3600 = 0.004 Erlang kris.sujatmoko@gmail.com
  19. 19. 19 SDCCH Dimensioning (3)  A cell with 2 TRXs  Combined SDCCH  1 comb. CCCH/SDCCH →4 SDCCH  15 TCH  Offered TCH load at 2% blocking  9.01 Erlangs  9.01/0.026=346 subscribers  Offered SDCCH load at 1% blocking  4 SDCCH blocks for combined configuration  Thus from Erlang B table, lookup 4 channels at 1% blocking  0.87 Erlangs  0.87/0.004=217 subs  SDCCH limited: 217 subscribers kris.sujatmoko@gmail.com
  20. 20. 20 SDCCH Dimensioning (4)  Non-combined SDCCH  1 SDCCH/8 →8 SDCCH  14 TCH  Offered TCH load at 2% blocking  8.20 Erlangs  8.20/0.026=315 subscribers  Offered SDCCH load at 1% blocking  8 SDCCH blocks for non-combined configuration  Thus from Erlang B table, lookup 8 channels at 1% blocking  3.13 Erlangs  3.13/0.004=782 subs  TCH limited: 315 subscribers  This configuration is preferred as it is TCH limited kris.sujatmoko@gmail.com
  21. 21. GSM-GPRS Operation Parameters Related To Channel
  22. 22. 22 Common Control Channel Load kris.sujatmoko@gmail.com
  23. 23. 23 Common Control Channel Load (2) kris.sujatmoko@gmail.com
  24. 24. 24 Common Control Channel Load (3)  CCCH Capacity  Calculation (non-combined):  Uplink : 51*3600/(51*0.004615) = 780000 RACH slots per hour  downlink : 36*3600/(51*0.004615) = 137658 CCH blocks per hour kris.sujatmoko@gmail.com
  25. 25. 25 Common Control Channel Load (4)  CCCH Capacity  Calculation (combined):  Uplink : 27*3600/(51*0.004615) = 413000 RACH slots per hour  downlink : 12*3600/(51*0.004615) = 45886 CCH blocks per hour kris.sujatmoko@gmail.com
  26. 26. 26 Common Control Channel Load (5)  CCCH Capacity  1 RACH slot : a channel message for 1 subscriber  1 CCCH block (4 slots): 1 paging message for 1..4 subscribers* or  1 access grant message for 1..2 subscribers * Depends on IMSI(2) or TMSI(4) paging kris.sujatmoko@gmail.com
  27. 27. 27 Common Control Channel Load (6) - RACH  Used by MS to request a dedicated channel (SDCCH)  The causes for the channel request can be:  A paging response in MTC  An emergency call  A MOC  LU or  IMSI attach/detach  Parameters related to RACH  maxNumberOfRetransmission (1, 2, 4 or 7)  numberOfSlotsSpreadTrans (3 ... 12, 14, 16, 20, 25, 32, 50) kris.sujatmoko@gmail.com
  28. 28. 28 Common Control Channel Load (7) - RACH  The combination of maxNumberOfRetransmission and numberOfSlotsSpreadTrans values determine the time period between sending of two channels requests.  This period is measured in RACH slots and is the sum of a deterministic part S and a random part tr. (refer to GSM 04.08)  RACH can be configured in combined and non-combined case  Combined: all 27 timeslot0 out of 51 timeslots  Non-combined: all timeslot0,2,4,6 kris.sujatmoko@gmail.com
  29. 29. 29 Common Control Channel Load (8) - RACH  values for 50000 RACH activities per hour kris.sujatmoko@gmail.com
  30. 30. 30 Common Control Channel Load (9) - RACH  The minimum blocking is achieved by the following setting of parameters: maxNumberOfRetransmission = 7, numberOfSlotsSpreadTrans = 50  The configuration of CCCH is mainly determined by the capacity needed by the downlink channels, the RACH configuration is uncritical kris.sujatmoko@gmail.com
  31. 31. 31 Common Control Channel Load (10) - PCH  PCH may be used as AGCH but not vice-versa  MOC requires AGCH and MTC requires PCH  Typical network will have MOC higher than MTC  Strategy: to dimension the AGCH to a smaller value and let the system organise the use of channels  Parameter related to PCH:  noOfMultiframesBetweenPaging (2 ... 9)  It indicates the number of TDMA multiframes between transmission of paging message to the same paging sub- group  It impacts on the MS battery life and MTC setup time  Higher value will save battery life but longer call setup time and vice versa  Recommended value is 5 kris.sujatmoko@gmail.com
  32. 32. 32 Common Control Channel Load (11) - AGCH  Parameter related to AGCH:  NumberOfBlocksForAccessGrant (0 ... 7)  It defines the number of blocks reserved for access grant messages from the CCCH during the 51 TDMA frame (a multiframe)  Recommended value is 1 for combined and 2 for non-combined configuration  Note that if the AGCH is insufficient, PCH can be used as AGCH kris.sujatmoko@gmail.com
  33. 33. 33 Common Control Channel Load (12) - Example kris.sujatmoko@gmail.com
  34. 34. 34 Common Control Channel Load (12) – Example Cont..  Analysis:  DL CCCH (PCH and AGCH) is the limiting factor  The usage for PCH and AGCH is almost equal For MOC, response to paging in MTC, LU and IMSI attached/detached, thus 4 RACH activities per sub per hour kris.sujatmoko@gmail.com
  35. 35. 35 Common Control Channel Load (12) – Paging Capacity  Paging demand is a function of:  Number of MTC  Number of subscribers in the LAC  Paging repetition  PCH can be configured as combined or non-combined :  Combined: both BCCH and SDCCH occupy the TS0  12 out of 51 slots per multiframe form 3 PCH/AGCH, each block consists of 4 slots kris.sujatmoko@gmail.com
  36. 36. 36 Common Control Channel Load (12) – Paging Capacity  PCH can be configured as combined or non-combined:  Non-combined: BCCH occupies TS0 and SDCCH occupies TS1  36 out of 51 slots per multiframe form 9 PCH/AGCH, each block consists of 4 slots  Split of blocks between PCH and AGCH: the available blocks in 51 multiframe is splitted between PCH and AGCH and it is set by parameter NumberOfBlocksForAccessGrant kris.sujatmoko@gmail.com
  37. 37. 37 Common Control Channel Load (13) – Paging Capacity  IMSI/TMSI paging:  IMSI: 2 mobiles can be paged with each page message occupying 4 slots  TMSI: 4 mobiles can be paged with each page message occupying 4 slots  Paging capacity calculation:  PCH per second kris.sujatmoko@gmail.com
  38. 38. 38 Common Control Channel Load (14) – Paging Capacity  What does the table mean?  CCCH can be used for both AGCH and PCH  Example for combined configuration, 3 CCCH blocks are available  If u reserve 0 blocks for AGCH, all 3 CCCH blocks will be used for PCH  If u reserve 2 blocks for AGCH, only 1 CCCH blocks will be used for PCH kris.sujatmoko@gmail.com
  39. 39. 39 Common Control Channel Load (15) – Paging Capacity  For combined BCCH:  Making sense out of the table:  Number of MS that can be paged in a second:  Depends on IMSI or TMSI paging and  Number of blocks reserved for AG kris.sujatmoko@gmail.com
  40. 40. 40 Common Control Channel Load (16) – Paging Capacity  For Combined BCCH  Example: if u reserved 1 block for AG, then u have 2 blocks for PCH  If u decide TMSI paging, I.e. 4 MS can be paged with 1 block of PCH  Thus; (number of PCH blocks*number of pages per block)/(51*one TDMA frame period);  =(2*4) / (51*0.004615) = 34  34 MS can be paged in a second (using TMSI paging) kris.sujatmoko@gmail.com
  41. 41. 41 Common Control Channel Load (17) – Paging Capacity  For Combined BCCH kris.sujatmoko@gmail.com
  42. 42. 42 Common Control Channel Load (18) – Paging Capacity  For Non Combined BCCH  Making sense out of the table:  3 blocks reserved for AG, remaining 6 blocks used for PCH  Number of MS can be paged in a second (TMSI paging)  = (6*3)/(51*0.004615) = 76 MS/second kris.sujatmoko@gmail.com
  43. 43. 43 Common Control Channel Load (19) – Paging Capacity  For Non Combined BCCH kris.sujatmoko@gmail.com
  44. 44. GSM-GPRS Operation Location Area Design
  45. 45. 45 Location Area Design  What is Location Area?  A location area is an area in which MSs may roam without updating the location registers  A location area consists of one or more cells  What information you need?  Traffic model  • What is next?  Calculate SDCCH traffic  Determine paging capacity  Calculate LA size (in term of number of cells) kris.sujatmoko@gmail.com
  46. 46. 46 LA Size – SDCCH Traffic calculation kris.sujatmoko@gmail.com
  47. 47. 47 LA Size – SDCCH Traffic calculation (2) kris.sujatmoko@gmail.com
  48. 48. 48 LA Size – Paging Capacity kris.sujatmoko@gmail.com
  49. 49. 49 LA Size – Paging And AG Traffic Demand kris.sujatmoko@gmail.com
  50. 50. GSM-GPRS Operation End of Section 4 Signalling Dimensioning

×