GSM SDCCH

Know More - SDCCHNov 17, 2003 S. Rajshekhar Deshraj Contents • Channel Concepts • Call Setup • Burst & Multi Frames • Mapping of Logical Channels • Definitions of SDCCH • Usage of SDCCH in the GSM network (BSC) • Possible SDCCH Configuration • SDCCH Holding Time Nov 17, 2003 S. Rajshekhar Deshraj Contents • SDCCH Traffic Estimations • SDCCH Congestion • Reasons for SDCCH congestion • How to detect SDCCH congestions • Preventive actions to avoid SDCCH congestions • SDCCH Dimensioning • Parameters for SDCCH Dimensioning • Counters & Report Analysis Nov 17, 2003 S. Rajshekhar Deshraj Logical Channels Nov 17, 2003 S. Rajshekhar Deshraj Broadcast Channels (BCH) Frequency Correction Channel (FCCH) •Downlink Channel •BTS: Transmits a carrier frequency (Pure sine wave of 67.7 KHz) This Solve 2 purpose : a> Make sure that this is BCCH Carrier b> To allow the MS to synchronize to the frequency •MS: After Switch on MS Scan for this channel, since it has no information to which frequency to use. FCCH carrier enables a mobile to tune its frequency to that being broadcast by the BTS. Nov 17, 2003 Broadcast Channels (BCH) Syncronization Channel (SCH) •Downlink Channels •BTS: Transmits TDMA Frame number + Base Station Identity Code (BSIC= NCC + BCC ) •MS: MS decodes the BSIC if the chosen BTS is GSM Base station within a cell Nov 17. 2003 . Broadcast Channels (BCH) •Broadcast Control Channel (BCCH) •Downlink Channels •BCCH contains the detailed Network and cell specific information such as : •Frequency used by Cell and its Neighboring cells. •Frequency HSN •Paging Groups •LAI •Max output power allowed in the cell Nov 17. 2003 . it will respond. If it identifies its own mobile subscriber identity number on the PCH.Common Control Channels (CCCH) Paging Channel (PCH) •Downlink Channels • BTS: Broadcast the paging message to indicate the Incoming Calls or Incoming SMS. Paging message also includes the MS’s identity number IMSI/TMSI • MS: MS listens to the PCH. 2003 . Nov 17. it replies on RACH requesting a signaling channel. 2003 .Common Control Channels (CCCH) Random Access Channel (RACH) •RACH is transmitted Uplink only •When mobile is paged . •RACH can also used if the MS wants to make a contact the NW/ Originating calls Nov 17. This assignment is performed on the AGCH Nov 17.Common Control Channels (CCCH) Access Grant Channel (AGCH) •Downlink channel •AGCH is answer to the RACH •NW assigns a signaling channel (SDCCH) to the MS. 2003 . 2003 .Dedicated Control Channels (DCCH) Stand Alone Dedicated Control Channel (SDCCH) •SDCCH is bi-directional Channel •System Signaling •Call Setup •Authentication •Location Update •Assignment of Traffic channels and •Transmission of Short messages Nov 17. 2003 .Dedicated Control Channels (DCCH) Slow Associated Control Channel (SACCH) •SACCH is transmitted in both Uplink and Downlink directions •SACCH is associated with each SDCCH and also with TCH •Uplink : MS Sends the averaged measurement on its own BTS and neighboring BTS’s •Downlink: MS receives information regarding information concerning •Transmit power to use •Instructions on Timing Advance Nov 17. Dedicated Control Channels (DCCH) Fast Associated Control Channel (FACCH) •While Calls in progress and HO is required FACCH is used •FACCH works in Stealing mode meaning that one 20ms segment of speech is exchanged for signaling information necessary for the HO Cell Broadcast Channel (CBCH) •CBCH is used in Downlink only •It is used to carry Short Message Service Cell Broadcast (SMSCB) and uses the same physical channel as the SDCCH Nov 17. 2003 . Traffic Channels (TCH) Traffic channels are Bi-directional logical channel that transfer the user speech or data.8 Kbit/s with latest R9. Nov 17. but the coding mechanism is different that is used for normal FR.4 Kbit/s with latest R9.1 •Enhance Full Rate : •The speech coding in EFR is still done at 13Kbit/s. EFR gives better speech quality at the same bit rate than normal FR. •Full Rate TCH ( TCH/F) : •This channel carries information at a gross rate at 13Kbit/s * * Now it is 22.5Kbit/s* * Now it is 11. 2003 .1 •Half Rate TCH (TCH/H) : •This Channel carried information at a gross rate at 6. Rajshekhar Deshraj .Call to an MS More. 2003 S.. Nov 17. which repeats itself in a time period of 3 HOURS 28 MINUTES 53 SECONDS 760 MILLISECONDS. This time period is referred to as Hyperframe.25 Bits.CCCH. Hyperframe: In GSM system every TDMA frame is assigned a fixed number. So. Rajshekhar Deshraj .There are 5 types of Bursts each having 15/26 ms duration and 156. 26 TDMA Frame Multiframe :Used to carry TCH. 2003 S. Duration =51 x 8 x 15/26 =235. SACCH and FACCH Duration =26 x 8 x 15/26 =120ms 51 TDMA Frame Multiframe : Used to carry BCCH.38ms Nov 17.SDCCH and SACCH. Superframe : =51x26 Multiframes. Duration =51x26x8x15/26=6Sec 120ms Multiframe :There are two types of multiframe.Relationship Between Burst & Frame Burst : Physical content of a TS is called Burst. TDMA frames with Common and Dedicated Channels Nov 17. 2003 . 577 ms ) TB Encrypted bits 3 57 F Training Sequence F 26 Encrypted bits TB 57 3 GP 8. 2003 .Bursts Normal Bursts: This burst is used to carry information on •Traffic channel •SDCCH Channel •Broadcast Control Channel •Paging Channel : •Access Grant Channel •SACCH & FACCH Channel 1 Time slot = 156.25 bits durations (15/26 = 0.25 F : One Stealing Bit:=0 Indicates 57bit packet contains user data or speech :=1 Indicates burst stolen for FACCH Signalling RxQual derived from the 26 bit midable from the TDMA frame Nov 17. Thus the MS on receiving this fixed frequency signal fine tunes to the BCCH frequency and waits for the Sync burst to arrive after 1 TDMA Frame .Bursts Frequency Bursts: All 148 bits(142+6) are coded with 0.7 Khz above the BCCH carrier frequency.i.25 Nov 17.25 bits durations (15/26 = 0.e =15/26*8=4. The output of GMSK Modulator is a fixed frequency signal exactly 67.577 ms ) TB 3 ALL ZERO 142 BITS TB 3 GP 8.615ms 1 Time slot = 156. 2003 . of 64 Bits are identical for all BTS Nov 17.BCC & TDMA FN 64 Bits : Long training seq.25 bits durations (15/26 = 0.Bursts Synchronization Bursts: This burst is used for time synchronization of the MS 1 Time slot = 156. 2003 .25 39Bit x 2=78 Bits :Are decoded to arrive 25-SCH control bits and that contains the information of the NCC .577 ms ) TB 3 SCH DATA 39 Bits Extended Training Sequence 64 Bits SCH DATA 39 Bits TB 3 GP 8. Bursts Access Bursts: This burst is used only for initial access by the MS to the BTS which applies 2 cases : •For connection setup when idle state where a CHAN_REQ message is sent using access burst •For HO when MS send HND_ACC message. 1 Time slot = 156.577 ms ) TB 8 SCH Sequence 41 Bits RACH Data 36 Bits TB 3 Guard Band 68.25 bits durations (15/26 = 0.25 bits GP: Long GP enables BTS to get Propagation delay information. 2003 .25 Bits 36Bit Contains : BSIC+CHAN_REQ or HND_ACC 41Bit Contains : Fixed bit sequence allow BTS to recognize it is Access Burst 86. Nov 17. 577 ms ) TB 3 Mixed Bits 58 Training Sequence 26 Mixed Bits 58 TB Guard Band 3 8.25 58Bits: Coded with pseudo random bit seq.25 bits durations (15/26 = 0. when there is no paging message to transmit.Bursts Dummy Bursts: To enable the BCCH frequency to be transmitted with a constant power level. This burst is transmitted on CHGR=0 when no other type of burst is to be sent. 2003 . to prevent confusion with Freq correction burst Nov 17. 1 Time slot = 156. dummy burst are inserted. Thus it makes possible for MS to perform the power measurement on the BTS in order to determine which BTS to use for initial access or which to use for HO CCCH is replaced by the dummy page. at Frame no 50. 2003 . Cycle=51TS TS=0 / CHGR=0 0 1 7 DOWNLINK 0 1 7 0 1 7 F0 F1 F2-F5 F6-9 TS-0 F S BCCH CCCH F10 F F11 F12-F15 F16-19 F20-23 F24 F25 F26-29 F30 F31 F32-F35 F36-F39 F40 F41 F42-F45 F46-49 F50 S BCCH CCCH CCCH F S CCCH F S CCCH CCCH F S CCCH CCCH I F: FCCH 1 TS ( Use 4 Slots in each 51 TDMA Frame) S: SCH 1 TS ( Use 4 Slots in each 51 TDMA Frame) I: IDLE 1 TS BCCH 4 TS CCCH 4 TS (PCH or AGCH) Paging Block 51 TDMA Frame = 9 Paging Blocks TS=0 / CHGR=0 F0 F1 TS-0 R R F3 R F3 R UPLINK F4 R F5 R F6 R F7 R F8 R F9 F10 R R F46 F47 R R F48 R F49 R F50 R R: RACH 1 TS Nov 17.B repeats after the Idle frame I.e.Mapping of Logical Channel Method of transmitting logical channels onto physical channel is called Mapping FCCH+SCH+BCCH+CCCH: An idle MS search for the FCH. When MS finds the frequency correction burst it knows that this is TS 0 on CHGR=0 The cycle means F.S. by giving MS time to calculate its answer to the request received on down link SDCCH TS=2 / CHGR=0 1 2 3 1 DOWNLINK 2 3 1 2 3 7 F0-F3 F4-F7 F8-F11 F12-F15 F16-F19 F20-F23 F24-F27 F28-F31 F32-F35 F36-F39 F40-F43 F44-F47 F48 F49 F50 I I I I I I SDCCH0 SDCCH1 SDCCH2 SDCCH3 SDCCH4 SDCCH5 SDCCH6 SDCCH7 SACCH0 SACCH1 SACCH2 SACCH3 SDCCH0 SDCCH1 SDCCH2 SDCCH3 SDCCH4 SDCCH5 SDCCH6 SDCCH7 SACCH4 SACCH5 SACCH6 SACCH7 TS=2 / CHGR=0 I: 1 2 3 IDLE 1 TS SDCCH 4 TS 1 2 SACCH 4 TS UPLINK 3 1 2 3 7 F0-F3 F4-F7 F8-F11 F12 F13 F14 F15-F18 F19-F22 F23-F26 F27-F30 F31-F34 F35-F38 F39-F42 F43-F46 F47-F50 I I I I I I SDCCH0 SDCCH1 SDCCH2 SDCCH3 SDCCH4 SDCCH5 SDCCH6 SDCCH7 SACCH0 SDCCH0 SDCCH1 SDCCH2 SDCCH3 SDCCH4 SDCCH5 SDCCH6 SDCCH7 SACCH4 SACCH5 SACCH6 SACCH7 SACCH1 SACCH2 SACCH3 I: IDLE 1 TS SDCCH 4 TS SACCH 4 TS Nov 17.Mapping of Logical Channel SDCCH+SACCH: Cycle=102 TS This sequence is repeated after last idle frame. The reason for this is to achieve efficient communication. The Uplink & Downlink pattern are time shifted. 2003 . so SDCCH sub channel is sent in frame 0-3 on downlink and in frame 15-18 on uplink. Repetition time (Cycle) =26 Frames .e. TS=1 / CHGR=0 DOWNLINK 0 1 2 7 0 1 0 1 2 7 F0 T F1 T F2 T F3 T F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 T T T T T T T T A T T T T T T T T T T T T T I T: TCH 1 TS A: SACCH Nov 17.i. =26*8*(15/26)=120ms Every 13th TS contains SACCH.Mapping of Logical Channel TCH+SACCH: 0&2 used by control channels. Downlink contains TA value and Uplink contains measuring report. This leaves TS-1and 3-7 free for the use by TCHs. 2003 . Usage of SDCCH The SDCCH are used in some different ways in the GSM network: • Registrations: Periodic Location Updates. MS<->Network. 2003 . Nov 17. Controlled by the MSC. • SMS point-to-point: SMS messages to/from MS in Idle mode. • Fax Setup • Optional: USSD (Unstructured Supplementary Service Data) data transfer. IMSI Attach/Detach • Call Setup: Immediate Assignment -> Assignment. Similar to SMS. Limitations : SDCCH/8 in a cell = Number of TRX’s CONFIGURATIONS HYD007A 1 TRX SDCCH TCH 4 7 3 7 8 6 7 6 12 6 11 6 X X X X HYD006A 2 TRX SDCCH TCH 4 15 3 15 8 14 7 14 12 14 11 14 20 13 19 13 SDCCH/4 SDCCH/4+CBCH SDCCH/8 SDCCH/8+CBCH SDCCH/4+SDCCH/8 SDCCH/4+SDCCH/8+CBCH SDCCH/4+SDCCH/8+SDCCH/8 SDCCH/4+SDCCH/8+SDCCH/8+CBCH Nov 17. CBCH : If CBCH is active 1 sub channel of SDCCH is replaced by 1 CBCH channel.Possible Configurations SDCCH/8 : 8 Sub channels for signaling are mapped on 1 TS. SDCCH/4 (Combining BCCH and SDCCH) :4 Sub channels for signaling are mapped on BCCH TS. As a result Paging capacity on BCCH is reduced by 1/3. 2003 . this results 1 less TCH for the cell. Possible Configurations -BCCH COMBC+CBCH CELL HYD007A BCCH 1 CBCH 1 SDCCH 3 NOOFTCH 7 CHGR CHBAND 0 BPC CHANNEL CHRATE SPV STATE ICMBAND BUSY IDLE BUSY IDLE BUSY 1.2 1.2 1.2 1. 2003 .2 1.2 1.2 1.2 IDLE IDLE IDLE IDLE IDLE IDLE IDLE 4590 SDCCH-28646 SDCCH-28645 CBCH-34305 SDCCH-28644 BCCH-34797 4496 TCH-4629 4497 TCH-4630 4499 TCH-4631 4505 TCH-4654 4506 TCH-4655 4509 TCH-4661 4575 TCH-4670 FR FR FR FR FR FR FR Nov 17. 2 IDLE 1.2 BUSY 1.Possible Configurations -BCCH NCOMB+CBCH CELL HYD006A CHGR 0 BCCH 1 CBCH 1 SDCCH 7 NOOFTCH 14 BPC CHANNEL 6899 SDCCH-27810 SDCCH-27809 CBCH-34619 SDCCH-27808 SDCCH-27807 SDCCH-27806 SDCCH-27805 SDCCH-27804 6900 BCCH-34804 6887 TCH-1242 6888 TCH-1243 6891 TCH-1246 6893 TCH-1248 6895 TCH-1250 6897 TCH-1252 CHGR 1 BPC CHANNEL FR FR FR FR FR FR CHRATE SPV STATE ICMBAND CHBAND 64K IDLE IDLE BUSY IDLE IDLE IDLE IDLE IDLE BUSY 1.2 BUSY 1.2 IDLE NONE NONE NONE NONE NONE NONE NONE NONE 6885 TCH-1240 6886 TCH-1241 6889 TCH-1244 6890 TCH-1245 6892 TCH-1247 6894 TCH-1249 6896 TCH-1251 6898 TCH-1253 Nov 17.2 IDLE 1.2 IDLE 1.2 IDLE 1.2 IDLE 1.2 IDLE 1.2 IDLE NONE NONE NONE NONE NONE NONE CHRATE SPV STATE ICMBAND CHBAND 64K FR FR FR FR FR FR FR FR 1.2 IDLE 1. 2003 .2 IDLE 1.2 IDLE 1.2 BUSY 1. 2003 . Nov 17.SDCCH Congestion SDCCH congestion: All SDCCH in a cell are at the same time busy for a period of time which leads to rejection for new MS. festivals or celebrations. It may cause due to : > Extreme end-user behaviors: Sport event ending. Hanging SDCCH are generally caused by SW faults. > Increased mean hold time of the SDCCH: Mean hold time increase from 2 to 10 seconds can give SDCCH congestion. • Heavily used SDCCH: SDCCH seen as continuously busy even though they are used by different MS and thus carries traffic. Reasons : • Hanging SDCCH: Are SDCCH that are hanging busy and unusable for a long time (many minutes or indefinite). and the system waits a certain time before performing disconnection.) Call Setup = 2.5 Sec = 2.5 Sec Periodic Registration IMSI Attach IMSI Detach = 3.9 Sec (MTC) = 1. 2003 .as SDCCH is allocated by sending Imm Ass message.SDCCH Holding Time Normal Location Updating = 3.7 Sec (MOC) = 2.2 Sec (Vary depending the length of SMS) Fax Transmission False Access = 2.) Nov 17.5 Sec = 3.9 Sec (IMSI detach Indication message sent to NW.7 Sec (MOC) = 2.6Sec) & no ack is sent to MS.8 Sec (when Channel req is rec’d by system .9 Sec (MTC) Short Message Service(SMS) = 6. no authentication is performed (which normally takes 0. 4 X 2. 2003 .SDCCH Traffic Estimations Normal Location Update: Mean Holding time No of Location update =3.2 Sec =1.0 per sub and BH AC: Avg No of Location updates =1000X(1 X 3.5 Sec =1.5)/3600=0.0 per Sub and BH Traffic : 1000 X (1.9)} / 3600 =0.5)/3600=2.9 mE/sub Nov 17.2) / 3600 =1.972 mE/Sub IC : No Location updating at all =1000X(0 X 3.7 mE/sub Call Setup: Mean Holding time =2.916mE/Sub SMS: Mean Holding time No of SMS submitted =6.8 BHCA Mob Terminating Traffic (Incl B Ans) =0.5)/3600=0 mE/Sub BC: 3 times the Avg no of Location updates =1000X(3 X 3.7 Sec(MOC) & 2.4 BHCA Traffic : 1000 X {(0.8 X 2.9 Sec(MTC) Mob Originating Traffic (Incl B Ans) =0.7)+(0.0 X 6. • Handover on SDCCH Handover on SDCCH will in itself increase mean hold time on SDCCH. Nov 17. • C7 problems to MSC (or TRC) In case of C7 signalling problems (SCCP) towards MSC (and/or TRC) can lead to timeout on SCCP connection setup. 2003 . and thus the SDCCH is used until timeout.Reasons for SDCCH congestion Increased mean hold time of SDCCH can be caused by: • Too low signal strength at access to the system Due to LSS MS will be lost communication with the system. Minor increase in mean hold time expected. • Congestion of TCH/TRA/RALT Will increase CP execution time before rejecting Imm Ass. However minor increase is expected. This will lead to timeout in the BSC (RLINKT ). This will lead to more than 2 minutes hold time for SDCCH. Increase ACCMIN. Reasons for SDCCH congestion • Congestion on Air-interface Congestion on Air-interface leads to delay in communication to the MS. • Congestion on A-interface Congestion on the A-interface will lead to increased mean hold time on SDCCH. • High load in MSC/VLR or HLR High load in MSC/VLR and/or HLR will lead to increased mean hold time on SDCCH.Increases SDCCH mean hold time with more than 2 seconds. Increase is unknown. Increase is unknown. 2003 . Increase SDCCH mean hold time with more than 5 seconds. • Congestion on Abis (LAPD link) Congestion on Abis leads to delay in communication with BTS and MS. Can give timeout in BSC during Imm Ass. Nov 17. Can give timeout in BSC during channel activation (TCHACTIVE).. • Decreased usage of TRA devices. • Location Updates fails => Mobile terminating calls does not reach the subscriber.How to detect SDCCH congestion in the BSC There is no good way to detect SDCCH congestion in real time in the BSC! A number of symptoms to look for: • Increased CP Load. Can not access the system. Object type: CLSDCCH and CLSDCCHO. • Subscriber complaints. 2003 . • Seizure Supervision of LCHs (but only for Hanging SDCCHs!) Nov 17. • STS counters . • Use recommended values for Periodic Location Updates Avoid unnecessary Periodic Location Updates : BSC: T3212 (RLSBC) = 40 (4 hours) MSC: BTDM (MGIDI) = 240 (4 hours) MSC: GTDM (MGIDI) = 6 (6 minutes) • Use Immediate Assignment on TCH. 2003 . can cause long meanhold time on SDCCH. • Avoid Handover on SDCCH • Proper Dimensioning of the TCHs and TRA devices in the BSC.Preventive actions to avoid SDCCH congestion • Avoid combined BCCH in cells with many SDCCHs • Use the optional feature Adaptive Configuration of SDCCHs (ACLC) • Use USSD (Unstructured Supplementary Service data) with care. • Increases the no of SDCCH in a Cell where SDCCH load is high Nov 17. If LA> 2100 Erlang (500 TRX) 1 SDCCH/4 as the basic configuration for all the cells.SDCCH Dimensioning SDCCH Dimensioning is a compromise between SDCCH blocking rate and TCH Capacity. If LA< 2100 Erlang (500 TRX) Nov 17. Basic SDCCH configuration: It is recommended to choose 1 SDCCH/8 as the basic configuration for all the cells. In order to have a successful call setup there has to be an available SDCCH as well as available TCH. 2003 . SDCCH GOS =1/4 * 2= 0. 2003 . Manual SDCCH Dimensioning : •Monitoring SDCCH / TCH Traffic in a cell •SDCCH/TCH load ratio •SDCCH Grade of Service:.SDCCH Dimensioning Automatic SDCCH dimensioning: This can be done with optional Adaptive Configuration of Logical Channel feature.Max allowed TCH GOS % = 2 % The rule of Thumb says: SDCCH/4 : Max. SDCCH GOS =1/2 * 2= 1 % SDCCH/8 : Max.5% Nov 17. and revert back to TCH if SDCCH load goes down. This feature will add extra SDCCH/8 by reconfiguring idle TCH when SDCCH load is high. SDCCH Dimensioning Immediate Assignment on TCH: In case of this feature on the channel administration assigns TCH for signaling instead of an SDCCH. Nov 17. based on 7 different channels allocation strategies (CHAPs) TCH first strategy : Decreases the SDCCH load and enable to use SDCCH/4 in all the cells Traffic load on TCH will in this case increases substantially so this strategy is not recommended. 2003 . SDCCH first strategy : SDCCH is always allocated first if available. otherwise signaling is performed on TCH. No CBCH GOS: SDCCH/4 = 1%.9 Erlang Actual TCH Capacity=14.9 – 0.5% & TCH % =2% 1> When Immediate Assignment on TCH not used Erlang B Table :To maintain 0.7 Erlang TCH Capacity in the cell is increased with 0.7 Erlang Nov 17.5 % GOS & 4 Erlang min 13 Subchannels reqd 2SDCCH/8 => TCH=(3TRX*8TS) –(1BCCH)-(2SDCCH/8)=21TCH’s 21TCH’s with 2 % GOS => 14.04 Erlang 2> When Immediate Assignment on TCH used If we use 1SDCCH/8 only than 4 Erlangs with 8 sub channels GOS=>3 % Congested Erlang will be =4 Erlang x 3 %=0.12Erlang 1SDCCH/8 => TCH=(3TRX*8TS) –(1BCCH)-(1SDCH/8)=22TCH’s 22TCH’s with 2 % GOS => 14. Bcchtype=NCOMB. 2003 .12 = 14. SDCCH/8 =0.SDCCH Dimensioning Example : ASSUME: CELL=3TRX .SDCCH Traffic =4 Erlang. SDCCH Dimensioning Immediate Assignment on TCH not used Nov 17. 2003 . 2003 .SDCCH Dimensioning Recommended SDCCH Configurations Nov 17. SDCCH Dimensioning HALF RATE CAPACITY CALCULATION Half rate will affect SDCCH dimensioning since more signaling will be req’d when no of TCH is increased. 1 SDCCH/8 TCH/F =14 support 14 Subscriber Penetration 10% of 14 is 1.i.the % of Half rate mobile in a NW. 2003 . Example: 2 TRX Cell.4 = 2 Subscribers (Req’d 2 Half Rate TCH/H) Total 13 TCH/F+2TCH/H = 15 TCH required Capacity : Erlang B Table: 15 TCH @ 2% GOS => 9. Important dimensioning factor is therefore the Half rate penetration .0096 Erlang Nov 17. Half Rate Penetration =10 %.e. 2003 .SDCCH Dimensioning Max Allowed SDCCH/TCH Load Ratio (Half Rate) AC : Average Cells BC : Border Cells IC : Inner Cells Nov 17. SDCCH Dimensioning Dimensioning based on STS data More accurate dimensioning is achieved by using cell statistics .e. STS counters •SDCCH Traffic •TCH Traffic •SDCCH/TCH Load Ratio % •SDCCH Congestion •TCH Congestion •SDCCH Mean Holding Time •Availability of SDCCH Channels •Availability of TCH Channels Nov 17.i. 2003 . SLEVEL: The attempt to increase the number of SDCCH/8 will take place when allocation of an SDCCH has failed due to congestion. The parameter is given as number of SACCH periods (480ms). Nov 17. STIME :Parameter STIME determines how long the system waits before the number of SDCCH/8 added by this function is decreased when the demand for signalling channels has returned to a low level BTDM :Implicit detach supervision should be equal or longer than T3212 in BSC.Parameters MFRMS :This parameter defines period of transmission for PAGING REQUEST messages to the same paging subgroup. 2003 . RLINKT: Radio link time-out This parameter defines the time before an MS disconnects a call due to failure in decoding SACCH messages. T3212 : Is the periodic registration timer ACCSTATE : Activate/Deactivate the Adaptive config of logical channel feature per cell basis CHAP :Selecting Channel Allocation profile per cell. GTDM : is an extra Gurad time in minutes before the subscriber is set to detach. Parameters for SDCCH Dimensioning Nov 17. 2003 . 2003 : SDCCH congestion time ( Sec) .STS Counters CCALLS CCONGS : Call attempt counter : Congestion counter CTRALACC : Traffic level accumulator. CNUCHCNT : Number of defined channels. CAVAACC : Available channels accumulator. CNDROP : Dropped connections due to Failure. CTCONGS Nov 17. CMSESTAB : Successful MS channel establishment on SDCCHs. CNSCAN : Number of accumulations of SDCCH traffic level counter. of SDCCH Attempts SDCCH Congestion (%) No. of SDCCH Connections SDCCH Establishments No Congestion (%) SDCCH Time Congestion (%) SDCCH Drop (%) SDCCH Mean Holding Time (Sec.CCONGS)} 100 X { CTCONGS / (RPL * 60)} 100 X { CNDROP / CMSESTAB } RPL X 60 X {(CTRALACC/CNSCAN) / CMSESTAB } CTRALACC / CNSCAN (CTRALACC/CNSCAN) / ((TFTRALACC/TFNSCAN)+(THTRALACC/THNSCAN)) Nov 17. 2003 .) SDCCH Traffic (Erlang) SDCCH/TCH Ratio CCALLS 100 X { CCONGS / CCALLS } CMSESTAB 100 X {CMSESTAB / (CCALLS .Formulas No. 47 80.52 1.7 1.99 84 86.08 1.91 1.07 73.78 81.19 2862 2.99 191 CT (S) 1952 8177 4397 3095 1423 656 2465 403 262 993 1654 375 1219 320 346 791 701 496 147 541 SDRP NOD SCSR CONR LEGENDS SDCCH Drop Rate % Week Total Dropped SDCCH's SDCCH Call Success Rate % SDCCH Congestion rate % NOC CT(S) ALL SDCCH Congestion Counter Cong.3 257 1.33 1.23 323 1.85 87.3 942 1.77 83.02 1.28 386 1.75 207 1.64 1.98 1695 2.5 % 72Cells 116Cells 97Cells 81Cells 60Cells CT Worst Cells (S) 326 NIZ001A 1989 NIZ001B 2410 CHL001A 638 BHI001A 1702 MAH002B 664 KHA001B 1084 TEN002C 1434 TIR008A 1127 AKI001A 790 BPL001B 860 TVR001C 1099 DHA001C 169 MAH002A 390 HIN001B 1865 BPL001C 270 TAD001C 1542 CHL002C 924 MAC001A 65 DHA001B 318 ADO001B 109 174 135 109 78 CELL HIN002C KAD001B GUN009B VIZ027C KAD001C HIN001B ANA001B TEN002C KAD001A VIZ023C ADO001C GOD001B SUL001A MAH002A STP001B VSP001C STP001A TVR001C RJM008B SAN001B Cells Cells Cells Cells Cells >0.81 77.22 68 98 71 55 59 CELL HYD201A HYD176A HYD176C HYD176B HYD137C HYD168A HYD005B HYD155A HYD161B HYD137B HYD054B HYD170B HYD171B HYD168C HYD137A HYD177B HYD142A HYD053C HYD161C HYD153C Cells Cells Cells Cells Cells >0.6 725 1.49 88.54 2.01 73.42 1.23 1.08 2.52 86.09.01 CELL ADO001B ADO002B AKI001A AKI001B AKI001C AMA001A AMA001A AMA001B AMA001C AMA001C ANK001B ANN001A ANN001B ANN001C ANP001A ANP001B ANP001C AVA001A AVA001B BHI001A 275 295 309 154 295 NOD 109 54 29 21 37 3 82 37 5 72 144 14 30 96 18 29 20 49 26 258 Cells Cells Cells Cells Cells >1% 1.7 1.01 88.22 82 1.06 2.34 6.23 88.71 357 378 400 382 372 CELL KOL001B JGP001C HIN002C RAJ001B VIZ020C JGP001A VJA018B CHI001C EMG001C RAZ001B NID001C CHL004C RJM007B VJA020A ONG004B ANN001A CHI003B VSP001B ANN001C VJA019B Cells Cells Cells Cells Cells < 96 % 65. Time in Secs (Week Tot) SDCCH Drop Rate % SDCCH Estab Success Rate % SDCCH Congestion rate % Nov 17.29 87.06 73.41 86.04 1.03 1.15 1.31 1.66 1.92 82.01 161 1 95 0.67 75.35 1.59 1.37 2.27 139 1.28 1.15 5.32 1.07 1.45 175 192 187 178 206 CELL HYD012C HYD117C HYD155B HYD161B HYD168A HYD058A HYD124B HYD146B HYD012A HYD093B HYD170B HYD155A HYD161C HYD089B HYD011B HYD121B HYD146C HYD145B HYD108C HYD101C Cells Cells Cells Cells Cells < 96 % 73.05 206 1.94 1.31 3081 3.86 87 87.3 1.13 81.33 1.1 129 1.51 1.82 87.21 81.57 83.28 1.98 90 602 641 267 392 183 275 372 268 183 190 372 71 104 374 135 329 258 15 134 15Sep-21Sep 22Sep-29Sep 29Sep-5Oct 06Oct-12Oct 03Nov-09Nov Sr No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 CELL HYD001B HYD004B HYD005A HYD007B HYD012C HYD018A HYD018B HYD020B HYD025C HYD026C HYD028A HYD028C HYD030C HYD031C HYD038A HYD040A HYD040B HYD042A HYD045B HYD051C 134 127 112 25 89 NOD 633 305 359 79 432 433 653 298 481 653 413 601 373 581 327 279 522 505 1632 229 Cells Cells Cells Cells Cells >1% 1.19 1.23 1.54 1.98 0.19 1.59 87.01 78.95 1.32 1.57 82.68 78.35 2.11 1.01 0.72 1.39 152 1.2 75.02 147 1.03 1.19 83.4 1.14 1.13 1.13 1.01 1.26 1.95 72.5% NOC 2.97 88.94 559 1. 2003 .03 ALL SDRP>1% SER <96% CONR >0.41 79.55 82.35 78.3 1.94 2.05 1.Quality Report : Call Setup Analysis Report Measuring Period : 03 Nov 2003 to 09 Nov 2003 (7Days) (Weekly Avg Stats) QUALITY REPORT :Call Setup Analysis Report ( W-6) S DRP(HYD) S DRP (ROAP) SCSR %(HYD) SCSR % (ROAP) CONR% (HYD) CONR% (ROAP) W-6 23.11 3.45 81.18 1.36 138 1.5% NOC 3.98 79.29 2.8 83.04 2.03 1. SDCCH Thank you Nov 17.Know More . 2003 S. Rajshekhar Deshraj . 2003 . Nov 17.TA) 7>Channel Activation Ack AGCH 8>Immediate Assign SABM (Paging Resp:IMSI/MS Class) UA(Paging Resp) Unnumbered Ack Frame which confirms only 1 MS is using Sig Channel 10>Auth Req (128 bit RAND+3bitCKSN) SDCCH 11>Auth Response (MS Calculate SRES & Kc with its own Ki stored in SIM by appling algorithm A3&A8) 9>Estblish Ind (Paging Resp) IMSI+MS Class 10>Auth Req (128 bit RAND+3bitCKSN) 9>Conn Req (Paging Resp: BSC add CGI) 10>Auth Req (128 bit RAND+ 3bit CKSN) 8>Imm Assign Cmd(On AGCH . Freq +TS+ SDCCH SubChannel No+TA BTS 2>Paging Command Imsi/Tmsi+PG+TRX+CG+TN BSC 1>Paging(LAI+IMSI/TMSI) MSC SDCCH 11>Auth Response (SRES) 11>Auth Response (SRES) Next.BSPwr.Call Setup-Mobile Terminating Call MS PCH 3>Paging Req(Imsi on PCH) RACH 4>Channel Req(On RACH) 5>Channel Reqd (Access Delay) 6>Channel Actn (MSPwr.. Speech/Data/Fax etc) 15>Call Confirmed 16>Assignment Req (MSC send CIC to BSC) SDCCH 19>Assignment Cmnd (BSC send message on SDCCH to MS telling to go TCH) 18>Channel Activation Ack 19>Assignment Cmnd (BSC send message on SDCCH to MS telling to go TCH) TCH 20>Assign Comp (MS tune to TCH and send Ind that Chan is Seized) 20>Assign Comp (MS tune to TCH and send Ind that Chan is Seized) 21>RF Chann Realease 21>RF Chann Realease Ack 22>Alert (MS Send Alert to MSC as soon as the ringing is started in MS) 23>Connect (When MS Sub Answer the Conn message sent to MSC) 24>Connect Ack 20>Assign Comp (MS tune to TCH and send Ind that Chan is Seized) TCH 22>Alert (MS Send Alert to MSC as soon as the ringing is started in MS) TCH 23>Connect (When MS Sub Answer the Conn message sent to MSC) 24>Connect Ack 22>Alert (MS Send Alert to MSC as soon as the ringing is started in MS) 23>Connect (When MS Sub Answer the Conn message sent to MSC) 24>Connect Ack TCH Exit.e. Nov 17. 2003 ..Call Setup-Mobile Terminating Call MS SDCCH SDCCH 14>Setup 15>Call Confirmed BTS 14>Setup 15>Call Confirmed 17>Channel Activation (BSC Allocated Idle TS for Traffic) BSC MSC 14>Setup (Req for Services I. 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