Call Set up Signaling In GSM

Traffic&Redesign LCC Pakistan Objective • Call setup,Mobility&Integrity is a Key of Optimization Traffic&Redesign 2 LCC Pakistan Outline • GSM Protocol Architecture for Signaling • International Signaling relation via ISDN • GSM Interface & Layer’s Function • Call setup Overview • Key points in Call Setup. • Explanation of each point with layer 3&2 message & logical channels. • Question &Answers Traffic&Redesign 3 LCC Pakistan GSM Protocol Architecture for Signaling Traffic&Redesign 4 LCC Pakistan GSM Signaling Network Continue… Traffic&Redesign 5 LCC Pakistan International Signaling relation via ISDN Traffic&Redesign 6 LCC Pakistan SS7 Signaling Architecture Traffic&Redesign 7 LCC Pakistan SS7 Layer in GSM Network Traffic&Redesign 8 LCC Pakistan SS7 Layers in GSM Network Traffic&Redesign 9 LCC Pakistan SS7 Layers in GSM Network… Traffic&Redesign 10 LCC Pakistan SS7 Layers in GSM Network…  Mobile Application Part (MAP)   Mobile-specific extension of C7 standard. All messages exchanged between NSS Elements (MSC,HLR,VLR)  Transaction Capabilities Application Part (TCAP)    A connectionless transport service provided by the SCCP Provides core functionality to support roaming Allows its users to access other users via worldwide C7/SS7 network  Signalling Connection Control Part (SCCP)    Logical signalling connection between MSC and MS to support Layer 3 (MM/CM) message transfers Uses reduced set of C7 signalling instructions Routes messages via STPs  Message Transfer Part (MTP)  C7 protocols responsible for routing and transport of signalling messages Traffic&Redesign 11 LCC Pakistan SS7 Layers in GSM Network… Traffic&Redesign 12 LCC Pakistan GSM Protocol Summery Traffic&Redesign 13 LCC Pakistan GSM Interfaces & Layers Um Interface Abis Interface Other Interfaces GSM A Interface E Interface B,C Interface Traffic&Redesign 14 LCC Pakistan A Interface Traffic&Redesign 15 LCC Pakistan A Interface… BSSMAP - deals with procedures that take place logically between the BSS and MSC, examples : Trunk Maintenance, Ciphering, Handover, Voice/Data Trunk Assignment DTAP - deals with procedures that take place logically between the MS and MSC. The BSS does not interpret the DTAP information, it simply repackages it and sends it to the MS over the Um Interface. examples: Location Update, MS originated and terminated Calls, Short Message Service, User Supplementary Service registration, activation, deactivation and erasure Traffic&Redesign 16 LCC Pakistan A Interface… Traffic&Redesign 17 LCC Pakistan A Interface Traffic&Redesign 18 LCC Pakistan Abis Interface Traffic&Redesign 19 LCC Pakistan Abis Interface…  Messages exchanges between the BTS and BSC. Traffic exchanges  Signaling exchanges  Physical access between BTS and BSC is PCM digital links of E1(32) or T1(24) TS at 64kbit/s.  Speech:  Conveyed in timeslots at 4X16 kbit/s  Data:  Conveyed in timeslots of 4X16 kbit/s. The initial user rate, which may be 300, 1200, … is adjusted to 16 kbit/s  Traffic&Redesign 20 LCC Pakistan Abis Interface… Level 1-PCM transmission (E1 or T1) Speech encoded at 16kbit/s and sub multiplexed in 64kbit/s time slots. Data which rate is adapted and synchronized. Level 2-LAPD protocol Radio Signaling Link (RSL) Operation and Maintenance Link (OML). Level 3-Application Protocol Radio Subsystem Management (RSM) Operation and Maintenance procedure (OAM) Traffic&Redesign 21 LCC Pakistan Abis Interface… Traffic&Redesign 22 LCC Pakistan LAPD Message Traffic&Redesign 23 LCC Pakistan LAPD Message…..  The length is limited to 260 octets of information.  LAPD has the address of the destination terminal, to identify the TRX, since this is a point to multipoint interface.  Each TRX in a BTS corresponds to one or several signaling links. These links are distinguished by TEI (Terminal Equipment Identities).  SAPI=0, SAPI=3, SAPI=62 for OAM. Traffic&Redesign 24 LCC Pakistan Um Interface  Level 1-Physical TDMA frame  Logical channels multiplexing  Level 2-LAPDm(modified from LAPD)  No flag  No error retransmission mechanism due to real time constraints  Level 3-Radio Interface Layer (RIL3) involves three sub layers  RR: paging, power control, ciphering execution, handover  MM: security, location IMSI attach/detach  CM: Call Control(CC), Supplementary Services(SS), Short Message Services(SMS),  Traffic&Redesign 25 LCC Pakistan Layer1 Signaling Traffic&Redesign 26 LCC Pakistan Layer 2 Signaling Traffic&Redesign 27 LCC Pakistan LAPDm Message • • In LAPDm the use of flags is avoided. LAPDm maximum length is 21 octets of information. It makes use of “more” bit to distinguish last frame of a message. • No frame check sequence for LAPDm, it uses the error detecting performance of the transmission coding scheme offered by the physical layer Traffic&Redesign 28 LCC Pakistan LAPDm Message….  The acknowledgement for the next expected frame in the indicator N(R ).  On radio interface two independent flows(one for signaling, and one for     SMS) can exist simultaneously. These two flows are distinguished by a link identifier called the SAPI(service access point identifier). LAPDm SAPI=0 for signaling and SAPI=3 for SMS. SAP1=0 for radio signaling, SAPI=62 for OAM and SAPI=63 for layer 2 management on the Abis interface. There is no need of a TEI, because there is no need to distinguish the different mobile stations, which is done by distinguishing the different radio channels. Traffic&Redesign 29 LCC Pakistan Layer 3 Signaling Traffic&Redesign 30 LCC Pakistan Layer3 Signaling Message Format at air Interface Traffic&Redesign 31 LCC Pakistan Protocol Discriminator Traffic&Redesign 32 LCC Pakistan Transaction Identifier Traffic&Redesign 33 LCC Pakistan Message Type Traffic&Redesign 34 LCC Pakistan Traffic&Redesign 35 LCC Pakistan Traffic&Redesign 36 LCC Pakistan Information Element Traffic&Redesign 37 LCC Pakistan Measurement Report Traffic&Redesign 38 LCC Pakistan Layer 3 Function Traffic&Redesign 39 LCC Pakistan RR Management Traffic&Redesign 40 LCC Pakistan Mobility Management Traffic&Redesign 41 LCC Pakistan Connection Management Traffic&Redesign 42 LCC Pakistan RR Massage, Channel & MT Code Traffic&Redesign 43 LCC Pakistan MM Massage Traffic&Redesign 44 LCC Pakistan CM Message Traffic&Redesign 45 LCC Pakistan Call Setup Overview • • • • MS Idle Mode Behavior Call setup signaling flow with Layer2&Layer3 explanation Handover signaling flow Location updated signaling Flow Traffic&Redesign 46 LCC Pakistan MS Idle Mode Behavior Traffic&Redesign 47 LCC Pakistan Idle Mode Measurements..explain in call Setup Traffic&Redesign 48 LCC Pakistan Call Setup Signaling Flow Traffic&Redesign 49 LCC Pakistan Call Setup Signaling Flow … Traffic&Redesign 50 LCC Pakistan Call Setup With Counters Traffic&Redesign 51 LCC Pakistan Paging Types  Paging locates MS to cell Level for call routing  Three paging message types: Type 1 - 2 MSs using IMSI/TMSI Type 2 - 3 MSs (1xIMSI, 2xTMSI) Type 3 - 4 MSs using TMSI only  Paging message requires 4 bursts (1 CCCH block)  Paging messages may be stored at BSS  Transmitted on PCH  If DRX is implemented MS listens only to allocated paging group Traffic&Redesign 52 LCC Pakistan Timers involved in Call Process Traffic&Redesign 53 LCC Pakistan Traffic&Redesign 54 LCC Pakistan Traffic&Redesign 55 LCC Pakistan Layer2&3 involved in Call setup Traffic&Redesign 56 LCC Pakistan Call Setup Measurements Layer3 • RR Management Message • MM Management Message • CM Management Message Layer2 • • • • • • • • RR-RSP I-CMD SABM-CMD UA-RSP DISC-CMD Call Setup Call Establishment Call End Traffic&Redesign 57 LCC Pakistan Layer3 Message…. RR Management Message Traffic&Redesign 58 LCC Pakistan RR …Paging Message Structure Protocol Discriminator The Channel Field (bits 1-2 of octet 2) indicates the further combination of channel which will be needed. It is coded as follows Traffic&Redesign 59 LCC Pakistan Channel Needed To indicate what type of channel is required for the transaction linked to the paging procedure. First Channel 00 Any channel 01 SDCCH 10 TCH/F 11 TCH/H or TCH/F Second Channel Same as first channel RR-Paging Message • Paging Request Type1 Page mode • To control the action of MS belonging to the paging subgroup corresponding to the paging subchannel. Page Mode 00 Normal Paging 01 Extended Paging 10 Paging Re organisation 11 Same as before Mobile Identity • To provide either the IMSI, the (P) TMSI but not the IMEI bases paging. IMSI [...]... length is limited to 260 octets of information  LAPD has the address of the destination terminal, to identify the TRX, since this is a point to multipoint interface  Each TRX in a BTS corresponds to one or several signaling links These links are distinguished by TEI (Terminal Equipment Identities)  SAPI=0, SAPI=3, SAPI=62 for OAM Traffic&Redesign 24 LCC Pakistan Um Interface  Level 1-Physical TDMA... expected frame in the indicator N(R )  On radio interface two independent flows(one for signaling, and one for     SMS) can exist simultaneously These two flows are distinguished by a link identifier called the SAPI(service access point identifier) LAPDm SAPI=0 for signaling and SAPI=3 for SMS SAP1=0 for radio signaling, SAPI=62 for OAM and SAPI=63 for layer 2 management on the Abis interface There... Summery Traffic&Redesign 13 LCC Pakistan GSM Interfaces & Layers Um Interface Abis Interface Other Interfaces GSM A Interface E Interface B,C Interface Traffic&Redesign 14 LCC Pakistan A Interface Traffic&Redesign 15 LCC Pakistan A Interface… BSSMAP - deals with procedures that take place logically between the BSS and MSC, examples : Trunk Maintenance, Ciphering, Handover, Voice/Data Trunk Assignment... logically between the MS and MSC The BSS does not interpret the DTAP information, it simply repackages it and sends it to the MS over the Um Interface examples: Location Update, MS originated and terminated Calls, Short Message Service, User Supplementary Service registration, activation, deactivation and erasure Traffic&Redesign 16 LCC Pakistan A Interface… Traffic&Redesign 17 LCC Pakistan A Interface... (SCCP)    Logical signalling connection between MSC and MS to support Layer 3 (MM/CM) message transfers Uses reduced set of C7 signalling instructions Routes messages via STPs  Message Transfer Part (MTP)  C7 protocols responsible for routing and transport of signalling messages Traffic&Redesign 11 LCC Pakistan SS7 Layers in GSM Network… Traffic&Redesign 12 LCC Pakistan GSM Protocol Summery Traffic&Redesign... LCC Pakistan Layer1 Signaling Traffic&Redesign 26 LCC Pakistan Layer 2 Signaling Traffic&Redesign 27 LCC Pakistan LAPDm Message • • In LAPDm the use of flags is avoided LAPDm maximum length is 21 octets of information It makes use of “more” bit to distinguish last frame of a message • No frame check sequence for LAPDm, it uses the error detecting performance of the transmission coding scheme offered... Pakistan Abis Interface… Level 1-PCM transmission (E1 or T1) Speech encoded at 16kbit/s and sub multiplexed in 64kbit/s time slots Data which rate is adapted and synchronized Level 2-LAPD protocol Radio Signaling Link (RSL) Operation and Maintenance Link (OML) Level 3-Application Protocol Radio Subsystem Management (RSM) Operation and Maintenance procedure (OAM) Traffic&Redesign 21 LCC Pakistan Abis Interface…... There is no need of a TEI, because there is no need to distinguish the different mobile stations, which is done by distinguishing the different radio channels Traffic&Redesign 29 LCC Pakistan Layer 3 Signaling Traffic&Redesign 30 LCC Pakistan Layer3 Signaling Message Format at air Interface Traffic&Redesign 31 LCC Pakistan Protocol Discriminator Traffic&Redesign 32 LCC Pakistan Transaction Identifier... 1-Physical TDMA frame  Logical channels multiplexing  Level 2-LAPDm(modified from LAPD)  No flag  No error retransmission mechanism due to real time constraints  Level 3-Radio Interface Layer (RIL3) involves three sub layers  RR: paging, power control, ciphering execution, handover  MM: security, location IMSI attach/detach  CM: Call Control(CC), Supplementary Services(SS), Short Message Services(SMS),... Traffic&Redesign 18 LCC Pakistan Abis Interface Traffic&Redesign 19 LCC Pakistan Abis Interface…  Messages exchanges between the BTS and BSC Traffic exchanges  Signaling exchanges  Physical access between BTS and BSC is PCM digital links of E1(32) or T1(24) TS at 64kbit/s  Speech:  Conveyed in timeslots at 4X16 kbit/s  Data:  Conveyed in timeslots of 4X16 kbit/s The initial user rate, which may be