SG
Uploaded bySaroj Kumar Gochhayat
PPT, PDF267 views

Skg gsm channel concept ; call processing

The document discusses various channels used in GSM networks. It describes physical channels that transfer bits between network elements and logical channels distinguished by the nature of carried information. It provides details on different types of logical channels including traffic, broadcast, common control and dedicated control channels. It also explains concepts like bursts, frames, multiframe structures and how they are used to organize speech and data on traffic channels.

Embed presentation

Downloaded 16 times
1 / 123
2 / 123
3 / 123
4 / 123
5 / 123
6 / 123
7 / 123
8 / 123
9 / 123
10 / 123
11 / 123
12 / 123
13 / 123
14 / 123
15 / 123
16 / 123
17 / 123
18 / 123
19 / 123
20 / 123
21 / 123
22 / 123
23 / 123
24 / 123
25 / 123
26 / 123
27 / 123
28 / 123
29 / 123
30 / 123
31 / 123
32 / 123
33 / 123
34 / 123
35 / 123
36 / 123
37 / 123
38 / 123
39 / 123
40 / 123
41 / 123
42 / 123
43 / 123
44 / 123
45 / 123
46 / 123
47 / 123
48 / 123
49 / 123
50 / 123
51 / 123
52 / 123
53 / 123
54 / 123
55 / 123
56 / 123
57 / 123
58 / 123
59 / 123
60 / 123
61 / 123
62 / 123
63 / 123
64 / 123
65 / 123
66 / 123
67 / 123
68 / 123
69 / 123
70 / 123
71 / 123
72 / 123
73 / 123
74 / 123
75 / 123
76 / 123
77 / 123
78 / 123
79 / 123
80 / 123
81 / 123
82 / 123
83 / 123
84 / 123
85 / 123
86 / 123
87 / 123
88 / 123
89 / 123
90 / 123
91 / 123
92 / 123
93 / 123
94 / 123
95 / 123
96 / 123
97 / 123
98 / 123
99 / 123
100 / 123
101 / 123
102 / 123
103 / 123
104 / 123
105 / 123
106 / 123
107 / 123
108 / 123
109 / 123
110 / 123
111 / 123
112 / 123
113 / 123
114 / 123
115 / 123
116 / 123
117 / 123
118 / 123
119 / 123
120 / 123
121 / 123
122 / 123
123 / 123
11/18/2021 1
Channels • Physical Channels – Associated with frequency bands, time slots, codes – Physical channels transfer bits from one network element to another • Logical Channels – Distinguished by the nature of carried information and the way to assemble bits into data units – Three types • one-to-one: traffic channels between a BTS and a MS • one-to-many: synchronization signals from BTS to MSs in a cell • many-to-one: from MSs to the same BTS 11/18/2021 2
Bursts and Frames 2047 3 2 1 0 Hyper frame = 2048 Super frames = 2,715,648 TDMA frames 3 Hours 28 Minutes 53 Seconds and 760 milliseconds 50 0 25 0 1 superframe = 1326 TDMA frames (6.12 seconds) = 51 (26-frame) multi frames or 26 (51-frame) multi frames 51 Multiframe Approx 235 mS 26 Multiframe 120 mS 25 24 2 1 0 50 49 48 1 0 7 6 5 4 3 2 1 0 TDMA frame 4.615 mS 11/18/2021 3
Organisation of Speech & Data 24 25 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 BP 7 BP 6 BP 5 BP 4 BP 3 BP 2 BP 1 BP 0 8.25 3 57 1 26 1 57 3 Frames 0-11 : TCH Frames 12 : SACCH Frames 13-24 : TCH Frames 25 : Unused 26 – frame multiframe Duration: 120 ms TDMA frame Duration: 60/13 ms =4.615 ms Tail bits Data bits Stealing bit Training sequence Stealing bit Data bits Tail bits Guard space Normal burst Duration 15/26 ms 11/18/2021 4
Bursts and Frames • There are two types of multiframe – 26 TDMA-frame multiframe is used to carry TCH, SACCH and FACCH – 51 TDMA-frame multiframe is used to carry BCCH, CCH, SDCCH and SACCH 11/18/2021 5
Burst • The information contained in one time slot is a burst • Five types of burst – Normal Burst (NB) • To carry information on traffic and control channels – Frequency Correction Burst (FB) • To synchronize the frequency of the mobile – Synchronization Burst (SB) • To synchronize the frames of the mobile – Access Burst (AB) • For random and handover access – Dummy Burst • For padding the frame 11/18/2021 6
Bursts and Frames 0 1 2 3 4 5 6 7 GP 8.25 TB 3 Encrypted bits 57 flag 1 Training sequence 26flag 1 Encrypted bits 57 TB 3 TB 3 Fixed bits 142 GP 8.25 TB 3 GP 8.25 TB 3 TB 3 Encrypted bits 39 Synchronization sequence 64 Encrypted bits 39 TB 3 Synchronization sequence 41 Encrypted bits 36 TB 3 GP 68.25 GP 8.25 TB 3 TB 3 Mixed bits 58 Training sequence 26 Mixed bits 58 Normal Burst (NB) Frequency correction burst (FB) Synchronization burst (SB) Access burst (AB) Dummy burst (DB) TB: Tail bits GP: Guard period 1 TDMA frame = 8 timeslots 1 timeslot = 156.25 bit durations (15/26 =~ 0.577 ms) (1 bit duration 48/13 =~ 3.69 micro sec) 11/18/2021 7
Normal Burst T3 Coded Data 57 Training Sequence 26 Coded Data 57 GP 8.25 S1 S1 T3 148 bits = 0.54612 msec This burst is used to carry information on TCH and on the control channelsBCCH, PCH, AGCH, SDCCH, ASCCH and FACCH. Note: GP (Guard Period) 11/18/2021 8
Random Access Burst T8 Synchronization sequence 41 Coded Data 36 Guard Period 68.25 T3 88 bits = 0.32472 msec 68.25 bits = 0.252 msec which is equivalent to 75.5 km propagation delay. That is, the max. allowed distance between mobile station and BTS is 37.75 km. Based on other system parameters, the max cell size is 35 km in GSM. 11/18/2021 9
Traffic channels (TCH) Signaling channel TCH/F: Full-rate Traffic Channel TCH/H: Half-rate Traffic Channel FCCH: Frequency correction SCH: Synchronization BCCH: Broadcast control PCH: Paging AGCH: Access grant RACH: Random access SDCCH: Stand-alone dedicated control SACCH: Slow associated control FACCH: Fast associated control Two-way Base-to- mobile Two-way Logical Channel List BCH CCCH DCCH 11/18/2021 10
20 higher GSM frame structures 935-960 MHz 124 channels (200 kHz) downlink 890-915 MHz 124 channels (200 kHz) uplink time 1 2 3 4 5 6 7 8 GSM TDMA frame 4.615 ms GSM - TDMA/FDMA GSM time-slot (normal burst) 546.5 µs 577 µs tail user data Training S guard space S user data tail guard space 3 bits 57 bits 26 bits 57 bits 1 1 3 S: indicates data or control ? 11/18/2021
21 11/18/2021
LOGICAL CHANNELS One or more logical channels can be transmitted on a physical channel. There are different types of logical channels. The type of logical channel is determined by the function of the information transmitted over it. The following types of logical channels exist: Traffic channels Broadcast channels Common control channels Dedicated control channels Note that the first channel type carries speech and data, and the other types control information (signaling). 11/18/2021 22
Traffic Channels Full Rate Traffic Channel (TCH/FS) Traffic Channel Multiframes are composed of only 26 TDMA frames. On each multiframe, there are 24 frames for Traffic Channels, 1 frame for a SACCH, and the last frame is Idle. Half Rate Traffic Channel (TCH/HS) When using Half-Rate Speech Encoding (TCH/HS), the speech encoding bit rate is 5.6 kb/s, so one time slot can handle two half-rate channels. In this case, one channel will transmit every other TDMA frame, and the other channel would be transmitted on the other frames. The final frame (25), which is normally used as an Idle frame, is now used as a SACCH for the second half-rate channel. 11/18/2021 23
GSM-Frame Structure 11/18/2021 24
Here is the math: As you remember from the Introduction to TDMA Tutorial. A single time slot has a data throughput of 24.7 kilobits per second (kb/s). 1. Calculate bits per TCH Multiframe: 114 bits per burst, 24 of the 26 frames used for voice/data. 114 bits × 24 frames = 2736 bits 2. Calculate bits per microsecond (ms): 2736 bits per TCH multiframe, multiframe duration = 120ms 2736 bits ÷ 120ms = 22.8 bits/msec 3. Convert microseconds (ms) to seconds: 22.8 bits/sec × 1000 = 22,800 bits per second (22.8 kb/s) 11/18/2021 25
11/18/2021 26
TRAFFIC CHANNELS The traffic channels are used to send speech or data services. There are two types of traffic channels. They are distinguished by their transmission rates. The following traffic channels are provided: TCH/F (Traffic CHannel Full rate) The TCH/F carries information at a gross bit rate of 22.8 kbit/s (after channel coding). The net (or effective) bit rate at the TCH/F is for speech 13 kbit/s and for data 12, 6 or 3.6 kbit/s (before channel coding). The transmission rates of the data services allow services which are compatible to the existing, respectively, 9.6, 4.8 and 2.4 kbit/s PSTN and ISDN services. TCH/H (Traffic Channel Half rate) The TCH/H carries information at a gross bit rate of 11.4 kbit/s. The net bit rate at the TCH/H is for speech 5.6 kbit/s and for data 6 or 3.6 kbit/s. 11/18/2021 27
TCH/EFR (Enhanced Full rate) The EFR provides a voice coding algorithm offering improved speech quality. The algorithm is fully compatible with a BSM speech quality. The algorithm is fully compatible with a GSM 13 kbit/s speech channel. The main benefit will be improved voice quality which offers prospects to compete with PSTN networks. A TCH/F or a TCH/H may also be used to send signaling information (for example call forwarding and short messages). 11/18/2021 28
Signaling Channels Signaling channel Broadcast Channels (BCH Cell Broadcast Channel (CBCH) Synchronization Channel (SCH) Frequency Correction Channel (FCCH) Broadcast Control Channel (BCCH) Common Control Channels (CCCH) Paging Channel (PCH) Random Access Channel (RACH) Access Grant Channel (AGCH) Standalone Dedicated Control Channel (SDCCH) Associated Control Channel (ACCH) Fast Associated Control Channel (FACCH) Slow Associated Control Channel (SACCH) 11/18/2021 29
11/18/2021 30
Broadcast Channels (BCH) • To help the MH (Mobile Handset) measures – to turn to a BTS – to listen for the cell information • to start roaming, waiting for calls to arrive, making calls – Because BTSs are not synchronized with each other, every time a MH decides to camp to another cell, its FCCH, SCH, and BCCH must be read. 11/18/2021 31
BROADCAST CHANNELS • The information distributed over the broadcast channels helps the mobile stations to orient themselves in the mobile radio network. • The broadcast channels are point-to- multipoint channels which are only defined for the downlink direction (BTS to the mobile station). 11/18/2021 32
BCCH (Broadcast Control Channel) • It inform the Mobile about system confirmation parameter • LAI Location Area Identity, • Cell -Identity • Neighboring Cell Identity. • MS select best cell to attach BCCH on full power, never Frequency hopped. The BCCH is also known as beacon. 11/18/2021 33
LAI = MCC + MNC + LAC MCC - Mobile Country Code. For India 404/405 USA 310/316 It is assigned by the ITU-T MNC - Mobile Network Code. . It is assigned by the government (DOT) of each country West bengal 74, Bihar-75,Orissa-76 LAC - Location Area Code . It is assigned by an operator • Maximum length of LAC is 16 bits. • Thus there can be maximum of 216 =65,536 Location Areas defined in one GSM PLMN. MCC MNC LAC 3 digits 2 digits 2 octets max LAI ( 16 bits ) Location Related Identities 11/18/2021 34
CELL GLOBAL IDENTITY (CGI) The CGI is used for cell identification within a location area. This is done by adding a Cell Identity (CI) to the components of a LAI. CI has a length of 16 bits. CGI consists of:CGI = MCC + MNC + LAC + CI 11/18/2021 35
BASE STATION IDENTITY CODE (BSIC) NCC = Network Color Code (3 bits 0-7), identifies the PLMN. Note that it does not uniquely identify the operator. NCC is primarily used to distinguish between operators on each side of a border. BCC = Base Station Color Code (3 bits 0-7), identifies the Base Station to help distinguish between BTS using the same BCCH frequencies. 113 77 76 79 66 63 FOR BSNL NCC=7 7-0 ,7-1,……..7-7. 12 NON HOPING FREQ X 7=96 NO OF COMBINATION . BCCH+BSIC COMBINATION SHOULD NOT BE SAME IN NEAR BY. 11/18/2021 36
Base Station Identification Code (BSIC). • BSIC allows for cell changes across cells that are not necessarily neighbors in a geographic sense. So an MS could do a cell reselection across cells with the same frequency but different BSIC. Such a possibility arises if the immediate neighbors are hidden (no line of sight) whereas a far away cell can provide better service due to clear LOS radio path. BSIC+ARFCN is unique in a particular area. 11/18/2021 37
11/18/2021 38
After the subscriber has switched on his mobile station and typed in his PIN code, the mobile station searches for a network •But how does it log on to the network the subscriber is registered with? •For this purpose, the BTS sends out the Frequency Correction Channel (FCCH) at short regular intervals, to help the mobile station find a frequency for downlink reception and adjust its frequency oscillator for the uplink transmission •To do so, it picks out the strongest received signal •The Synchronization Channel (SCH) then helps the mobile station to synchronize itself to timeslot 0 sent out by the BTS •This means the mobile station must adjust to the rhythm given bythe BTS •The SCH contains the TDMA frame number as well as the Base Station Identity Code, containing basic information about the network operator that canbe compared with the info stored on the SIM card •After this step, the mobile is able to decide whether it has chosen the proper network. If not, it starts the same procedure again trying with the second strongest FCCH received •While the mobile station uses the FCCH to adjust its frequency, and the SCH for synchronization and network identification, the Broadcast Control Channel (BCCH), which is also sent by the BTS, supplies the mobile station with additional information about the selected cell, for example for ciphering •For some Value Added Services, for example location-dependent services, additional information has to be transmitted from the BTS to the mobile •The Cell Broadcast Channel CBCH is used for this purpose to transmit geographical parameters, for example Gauss-Krueger-Coordinates of the BTS, to the mobile •The FCCH, SCH, BCCH and CBCH are Broadcast Channels, and exist only in the downlink •They are the first logical channels belonging to the Common Channels. 11/18/2021 39
Frequency Correction Channel (FCCH) • Provide MH with the frequency reference of the system – To enable the Mobile Handset (MH) to synchronize with the frequency • Transmission properties – Transmit on the down-link – Point to multi-point. 11/18/2021 40
HSN,MAIO,FREQ PLANNING. BSNL got 31 no of radio carrier. Fixed F1 to F15 Hopping Freq F16 to F31. CYCLIC HSN=0, MAIO=1,MAIO2 RANDOM HSN=1. HSN=63. MAIO Sequence (Mobile Allocation Index Offset) F16,F17,F18,F19..F31 MAIO=1 F17,F18,F19..F31,F16 MAIO=2 F18,F19..F31,F16, F17MAIO=3 41 F5 F9 F1 F16 F8 F12 F4/ F19 F6 F10 F2/ F17 F7 F11 F3/ F18 4/12 11/18/2021
FCCH (Frequency Correction Channel) To communicate with the BTS the mobile station must tune to the BTS. The FCCH transmits a constant frequency shift of the radio frequency carrier that can be used by the mobile station for frequency correction. 11/18/2021 42
Synchronization Channel (SCH) • MH synchronize with the structure within the locative cell – MH can receive information from the proper time slots on the TDMA structure • To ensure a GSM BTS is chose – The Base Station Identity Code (BSIC) can only be decoded by a GSM BTS • Transmission properties – Transmit on down-link – Point to multi-point. 11/18/2021 43
SCH (Synchronization CHannel) The SCH is used to time synchronize the mobile stations. The data on this channel carries the TDMA frame number and the BSIC (Base Station Identity Code). 11/18/2021 44
1.The A-bisinterface connects the Base Transceiver Station (BTS) with the Base Station Controller (BSC) 2. In the PCM30 configuration, the data at this interface is transmitted via cable or via microwave transmission at a bit rate of 2 Mbit/s 3. A cable connection is more resistent to interference, but a network operator must lease it from a fixed network operator 4. The microwave links can be operated independently, and are easily configured by the network operator, but they are more sensitive to interference •4 types of information can be transmitted over the A- bis interface: –user information –synchronization data –signaling information –and data for the operation and maintenance of the BTS, known as O&M alarms 11/18/2021 45
Broadcast Control Channel (BCCH) • BTS broadcast cell information to MH – LAI ( Location Area Identity), to start roaming, waiting for calls to arrive, making calls – maximum output power allowed in the cell – information about BCCH carriers for the neighboring cells • MH will perform measurement to BTS • Transmission properties – Transmit on down-link – Point to multi-point 11/18/2021 46
CBCH (Cell Broadcast CHannel) • The CBCH is used for the transmission of generally accessible information (Short Message Service messages) in a cell, which can be polled by the mobile station. 11/18/2021 47
11/18/2021 48
• The mobile station has now adjusted its frequency and synchronized its TDMAs, and has picked out the best cell available•But before it can be reached by other subscribers, and before itcan initiate calls, a Location Update and authentication procedure are necessary•Only after that is the mobile station logged on to the network and has radio coverage•It can now be reached by other mobile stations, or initiate a call. For this purpose, Common Control Channels are required•Common Control Channels are "point-to-multipoint" channels, which exist either only in the uplink, or only in the downlink•When a subscriber is called, the Paging Channel (PCH) is broadcast in the downlink by all base stations within a Location Area, so that the mobile station concerned canreact•To initiate a call, the mobile station sends out a Random AccessChannel (RACH), which carries its identification and request, for example for registration, to thenetwork•This channel only exists in the uplink. In return, the network sends the Access Grant Channel (AGCH) in the downlink direction, to assign resources to the mobile station, by granting it a Stand-Alone Dedicated Control Channel, SDCCH. The PCH, RACH and AGCH form the group ofthe Common Control Channels belonging also to the Common Channels. 11/18/2021 49
COMMON CONTROL CHANNELS CONT.. PCH (Paging CHannel) The PCH is used in the downlink direction for paging the mobile stations. ----used for paging when Incoming call. AGCH (Access Grant CHannel) The AGCH is also used in the downlink direction. A logical channel for a connection is allocated via the AGCH if the mobile station has requested such a channel via the RACH. RACH (Random Access CHannel) The RACH is used in the uplink direction by the mobile stations for requesting a channel for a connection. It is an access channel that uses the slotted Aloha access scheme. The Following figure gives an overview of the different types of logical channels. 11/18/2021 50
Paging Channel (PCH) • Used by BTS to page particular MH in the cell – MH actively listen to PCH to check contact info within certain time – Contact could be incoming call or short message • Contact info on PCH include – IMSI (MH’s identity number), or – TMSI (temporary number) • Transmission properties – Transmit on down-link – point to point 11/18/2021 51
Random Access Channel (RACH) • Used by MH to request a dedicated channel for call setup – Shared by any MH attempts to access the network – Channel request message contains the reason for the access attempt • Transmission properties – Transmit on up-link – Point to pint. 11/18/2021 52
Access Grant Channel (AGCH) • The network assigns a signaling channel via AGCH – A Stand alone Dedicated Control Channel (SDCCH) is assigned • Transmission properties – Transmit on down-link – Point to point 11/18/2021 53
Dedicated Control Channels (DCCH) • DCCH are used for transferring nonuser information between the network and the MH – Messages on DCCH Including • channel maintenance • mobility management • radio resource management • Four kinds of DCCH – Stand alone Dedicated Control Channel (SDCCH) – Cell Broadcast Channel (CBCH) – Slow Associated Control Channel (SACCH) – Fast Associated Control Channel (FACCH) 11/18/2021 54
Dedicated control channels are full-duplex, point-to-point channels. They are used for signaling between the BTS and a certain mobile station 11/18/2021 55
Slow Associated Control Channel (SACCH) • Carries control and measurement parameters along with routine data necessary to maintain a radio link between the MH and the BTS, which is always allocated to a TCH or SDCCH. – On the uplink, MS sends averaged measurements (signal strength and quality) of current and neighboring BCCH – On downlink, MS receives information about transmitting power to use and an instruction with time advance/retard • Transmission properties – Bidirectional channel, transmit on both up and down link – Point to point In 26 Frame Traffic Multi frame 13th frame (frame no. 12) is used for SACCH. Note that the SACCH is only used for non-urgent procedures. 11/18/2021 56
FACCH (Fast Associated Control Channel) • The FACCH is used as a main signaling link for the transmission of signaling data (for example handover commands). • It is also required for every call set-up and release. • During the call the FACCH data is transmitted over the allocated TCH instead of traffic data; this is marked by a flag called a stealing flag. • The process of stealing a TCH for FACCH data is called pre-emption. - Used for Urgent Signalling; like handover during a call. Appears on demand. 11/18/2021 57
Stand alone Dedicated Control Channel (SDCCH) • Transfer signaling information between the BTS and the MH • Typically used for location updating prior to use of a traffic channel • Transmission properties – Bidirectional channel, transmit on both up and down-link – Point to point. 11/18/2021 58
Cell Broadcast Channel (CBCH) • To carry Short Message Service Cell Broadcast (SMSCB) • Use the same physical channel as SDCCH • Transmission properties – Transmit on down-link – Point to multi-point 11/18/2021 59
SDCCH (Stand-alone Dedicated Control Channel) • The SDCCH is a duplex, point-to-point channel which is used for signaling in higher layers. • It carries all signaling between the BTS and the mobile station when no TCH is allocated. • The SDCCHs are used for service requests (for example Short Message Service), location updates, subscriber authentication, ciphering initiation, equipment validation and assignment to a TCH. The net SDCCH bit rate is about 0.8 kbit/s.(160 x 5 =800bits) 11/18/2021 60
Control Channel UP LIN K DOWN LINK FUNCTION Broadcast Control Channel (BCCH) ▼ These parameters include the Location Area Code (LAC), the Mobile Network Code (MNC), the frequencies of neighboring cells, and access parameters Frequency Correction Channel (FCCH) ▼ This channel contains frequency correction bursts Synchronization Channel (SCH) ▼ This channel is used by the MS to learn the Base Station Information Code (BSIC) as well as the TDMA frame number (FN). This lets the MS know what TDMA frame they are on within the hyperframe. Cell Broadcast Channel (CBCH) ▼ Broadcast such as weather, traffic, sports, stocks, etc. Messages can be of any nature depending on what service is provided. The CBCH is nt allocated a slot for itself, it is assigned to an SDCCH Paging Channel (PCH) ▼ incoming traffic. voice call, SMS, or some other form of traffic. Random Access Channel (RACH) ▲ MS to request an initial dedicated channel from the BTS Access Grant Channel (AGCH) ▼ This channel is used by a BTS to notify the MS of the assignments of an initial SDCCH for initial signaling Standalone Dedicated Control Channel (SDDCH) ▲ ▼ This channel is used for signaling and call setup between the MS and the BTS. Fast Associated Control Channel (FACCH) ▲ ▼ This channel is used for control requirements such as handoffs. There is no TS and frame allocation dedicated to a FAACH. The FAACH is a burst-stealing channel, it steals a Timeslot from a Traffic Channel (TCH). Slow Associated Control Channel (SACCH) ▲ ▼ This channel is a continuous stream channel that is used for control and supervisory signals associated with the traffic channels. 11/18/2021 61
62 Channel Combination Type Several logic channels combine together in some way to form some specific types of channel to transmit user data or signaling information. They are called combined channels. One combined channel can be mapped to a physical channel. 11/18/2021
CHANNEL COMBINATIONS The channel combinations are: 1. TCH/F + FACCH/F + SACCH/F 2. TCH/H + FACCH/H + SACCH/H 3. (TCH/F + FACCH/F + SACCH/F) or (TCH/H + FACCH/H + SACCH/H) 4. FCCH + SCH + CCCH + BCCH 5. FCCH + SCH + CCCH + BCCH + SDCCH/4 + SACCH/4 6. BCCH + CCCH (CCCH = PCH + RACH + AGCH) 7. SDCCH/8 + SACCH/8 The extensions “/4” and “/8” in the above mentioned terms mean, respectively, that four and eight logical channels are mapped onto one physical channel (timeslot). 11/18/2021 63
Control Channel 4. FCCH + SCH + CCCH + BCCH UPLINK DOWNLINK 6. CCCH + BCCH 11/18/2021 64
Downlink The SACCH that is associated with each SDCCH is only transmitted every other Multiframe. Each SACCH only gets half of the transmit time as the SDCCH that it is associated with. So, in one Multiframe, SACCH0 and SACCH1 would be transmitted, and in the next Multiframe, SACCH2 and SACCH3 would be transmitted. Uplink FCCH + SCH + BCCH + CCCH + SDCCH/4(0..3) + SACCH/C4(0..3) The two sequential Multiframe would look like this: 11/18/2021 65
Downlink Uplink You will also notice that the downlink and uplink Multiframes do not align with each other. This is done so that if the BTS sends an information request to the MS, it does not have to wait an entire Multiframes to receive the needed information. The uplink is transmitted 15 TDMA frames behind the downlink. For example, the BTS might send an authentication request to the MS on SDCCH0 (downlink) which corresponds to TDMA frames 22-25. The MS then has enough time to process the request and reply on SDCCH0 (uplink) which immediately follows it on TDMA frames 37-40. 11/18/2021 66
SDCCH/8(0-7) + SACCH/C8(0 - 7) Once again, the SACCH that is associated with an SDCCH is only transmitted every other multiframe. Two consecutive Multiframes would look like this: Downlink Uplink SKGOCHHAYAT,SDE(COMP) 11/18/2021 67
68 • Small capacity cell with only 1 TRX TN0: FCCH+SCH+CCCH+BCCH+SDCCH/4(0,_,3)+SACCH /C4(0,_,3); TN1-7: TCH/F+FACCH/F+SACCH/TF • The medium-size cell with 4 TRXs 1TN0 group: FCCH+SCH+BCCH+CCCH; 2 SDCCH/8(0,_,7)+SACCH/C8(0,_,7); 29 TCH/F+FACCH/F+SACCH/TF Channel Assignment inside cells 11/18/2021
69 • Large-size cell with 12 TRXs 1 TN0 group: FCCH+SCH+BCCH+CCCH; 1 TN2 group, 1 TN4 group and 1 TN6 group: BCCH+CCCH; 5 SDCCH/8(0,_,7)+SACCH/C8(0,_,7); 87 TCH/F+FACCH/F+SACCH/TF Channel Assignment inside cells 11/18/2021
medium-sized cell might be set up with 4 TRX (ARFCNs) 11/18/2021 70
Modes Mobile Station ( MS ) • MS Switched Off - can not receive incoming paging messages. - can not make outgoing call. - No dedicated channel is associated with it. • MS Switched On - can receive incoming paging messages. And in Idle Mode - can make outgoing call. - No dedicated channel is associated with it. • MS in Dedicated Mode -MS is in conversation and a dedicated traffic channel TCH is associated with it. 11/18/2021 71
Technical Terms Used w.r.t. MM (Mobility Management ) • IMSI – International Mobile Subscriber Identity • IMSISDN – Mobile Subscriber ISDN number • IMEI – International Mobile Equipment Identity • TMSI – Temporary Mobile Subscriber Identity • MSRN – Mobile Subscriber Roaming Number • LAI – Location Area Identity • A3 – Authentication Algorithm • A5 – Ciphering Algorithm • A8 – Kc Generation Algorithm 11/18/2021 72
GSM Network Identities 1. MSISDN – Mobile Subscriber ISDN number Subscriber Related Identities - CC NDC SN Max. 15 digits CC – Country Code. NDC – Network Destination Code. SN – Subscriber Number. Eg 91-98100-12345 11/18/2021 73
2. IMSI – International Mobile Subscriber Identity. 3. TMSI – Temporary Mobile Subscriber Identity Subscriber Related Identities - MCC MNC MSIN Max. 15 digits MCC – Mobile Country Code. MNC – Mobile Network Code. MSIN – Mobile Subscriber Identification Number. GSM Network Identities Equipment Related Identities - 1. IMEI – International Mobile Equipment Identity 11/18/2021 74
1. MSRN – Mobile Subscriber Roaming Number It is a temporary number used for routing the call to MS. Format : MSRN = CC + NDC + SN CC = Country Code NDC = Network Destination Code For example for Patna MSC in IMPCS network MSRN looks like 91 98750 00100. SN = Subscriber Number Location Related Identities 11/18/2021 75
PSTN GMSC HLR MSC VLR MSISDN 1 MSISDN 2 IMSI 3 IMSI MSRN 4 MSRN 5 MSRN 6 MSRN 7 MSRN Location Related Identities 11/18/2021 76
MSISDN 11/18/2021 77
INTERNATIONAL MOBILE EQUIPMENT IDENTITY (IMEI) IMEI = TAC + FAC + SNR + spare TAC = Type Approval Code, determined by a central GSM body. FAC = Final Assembly Code, identifies the manufacturer. SNR = Serial Number, an individual serial number of six digits uniquely identifies all equipment within each TAC and FAC. Spare = A spare bit for future use. When transmitted by the MS this digit should always be zero. IMEI has the total length of 15 digits. 11/18/2021 78
MSRN MSRN = CC + NDC + SN CC = Country Code NDC = National Destination Code SN = Subscriber Number NOTE: In this case, SN should not be interpreted as the actual subscriber identity. It represents the address to the serving MSC. 11/18/2021 79
MS Initialization / Network Attachment 1. MS Powered on. - FCCH present in time slot T0 & has a fixed pattern of 142 0’s. - MS scans entire 124 carriers and monitors RF levels. - several readings are taken to get accurate estimate the channel power. - MS then searches for Frequency Correction burst (FCCH) on the channel with strongest RF level. 2. Frequency Synchronization - After tuning to FCCH MS synchronizes in time with SCH . 11/18/2021 80
- SCH occurs in next frame in same time slot as FCCH. - The occurrence of SCH is eight burst period ( BP’s ) later than FCCH. 3. Synchronization in Time - After successful synchronization the MS will read the TDMA frame number and Base Station Identity Code BSIC . - SCH contains precise timing information and current frame number to which MS is synchronized. - BSIC consists of - PLMN colour code ( 3 bits ) - BS colour code ( 3 bits ). MS Initialization / Network Attachment 11/18/2021 81
• MS decodes information on BCCH and gets Location Area Identity ( LAI ). • If the information stored on SIM does not match with the information MS thinks that it has moved to new location and sends LA update request to BSS. • MS location is determined by cell identification of strongest BCCH signal received by MS. • MS regularly measures the received signal strength of BCCH at least once every 6 sec ( Superframe Duration). • MS stores at least six strongest BCCH and their cell identification in SIM. MS Initialization / Network Attachment 11/18/2021 82
Network Attachment Process MS . Cell should be of selected PLMN. Switch -on Measure strongest BCCH channels PLMN Selection Cell Selection Location Update Idle-Mode . Cell should not be “ barred “. . Radio path loss between BTS and the MS must be below a threshold set by the operator. ( Register its presence to the network. ) Limited Service Mode 11/18/2021 83
MS BTS MSC BSC RIL3 - CM LAPD m Layer 1 RIL3 - MM RIL3 - RR Layer 1 LAPD m LAPD Um A bis A link BCDEFG MTP SCCP BSSMAP DTAP MM TCAP DTAP CM U P SCCP M A P Layer 1 Layer 1 GSM Signaling Protocols Overview LAPD MTP I S SCCP BSSMAP BTSM RIL 3- RR BTSM RR 11/18/2021 84
What is Mobility Management? • Subscriber Data management at MSC/VLR • Subscriber data from HLR are retrieved by MM at the time of first location up-dating of a subscriber. • Dynamic data changes by subscriber are also managed by MM at MSC/VLR. • Operator initiated data changes for a subscriber are also managed by MM. 11/18/2021 85
Security in GSM • Security services – access control/authentication • user  SIM (Subscriber Identity Module): secret PIN (personal identification number) • SIM  network: challenge response method – confidentiality • voice and signaling encrypted on the wireless link (after successful authentication) – anonymity • temporary identity TMSI (Temporary Mobile Subscriber Identity) • newly assigned at each new location update (LUP) • encrypted transmission • 3 algorithms specified in GSM – A3 for authentication (“secret”, open interface) – A5 for encryption (standardized) – A8 for key generation (“secret”, open interface) “secret”: • A3 and A8 available via the Internet • network providers can use stronger mechanisms 11/18/2021 86
GSM - authentication A3 RAND Ki 128 bit 128 bit SRES* 32 bit A3 RAND Ki 128 bit 128 bit SRES 32 bit SRES* =? SRES SRES RAND SRES 32 bit mobile network SIM AC MSC SIM Ki: individual subscriber authentication key SRES: signed response 11/18/2021 87
GSM - key generation and encryption A8 RAND Ki 128 bit 128 bit Kc 64 bit A8 RAND Ki 128 bit 128 bit SRES RAND encrypted data mobile network (BTS) MS with SIM AC BTS SIM A5 Kc 64 bit A5 MS data data cipher key 11/18/2021 88
Services Provided to Upper Layers • MM handover procedures provide smooth transition from one radio link to other. • MM sub-layer provides basic services to upper layer CM sub-layer. Subscriber Authentication and Confidentiality management • MM procedures ensure authenticity of a subscriber. • MM procedures ensure data confidentiality at radio interface. 11/18/2021 89
Subscriber Data at MSC/VLR • MS status data: • Data related to identification and numbering ( IMSI, MSISDN,LMSI and TMSI ). • Data related to MS type. • Hand-over data. • Authentication and Ciphering Data. • Data related to supplementary services. 11/18/2021 90
MM Procedures • TMSI Reallocation Procedure. • IMSI Detach Procedure. • Ciphering Procedure. • Abort Procedure. MM Common Procedures : • Authentication Procedure. • Identification Procedure. MM Specific Procedures : • Location Updating Procedure. • IMSI Attach Procedure. 11/18/2021 91
• During the lifetime of a MM specific procedure if a MM connection establishment is requested by a CM entity, the request will either be rejected or delayed until the running of MM specific procedure is terminated. • Any MM common procedure Procedure ( except IMSI detach) may be initiated during MM specific procedure. • A MM specific procedure can only be started if no other MM specific procedure is running. • The MS side should wait for release of RR connection used for a MM specific procedure before a new MM specific procedure or MM connection establishment is started. MM Procedures 11/18/2021 92
• Location area consist of one or more than one cell which may be served by one or more BSC s. • All the cells in a Location area are served by single VLR. 2. Location Area Identity (LAI ) - • Each location area in a GSM PLMN is identified by a Location Area Identity ( LAI ). Location Related Identities 11/18/2021 93
HLR SS 7 BSC MSC 2 VLR 1 VLR 2 BSC BSC BSC LA 1 LA 2 LA 3 BTS BTS BTS BTS BTS BTS Location Area MSC 1 11/18/2021 94
95 SDE RTTC BHUBANESWAR 11/18/2021 95
MSC Hand over 11/18/2021 96
TAX CA TAX ND GMSC MSC GMSC MSC/VLR ND Mobile moves to CA and Powers on MS CA ND HLR HLR ND MS 9810098111 CA ND ( Update Location/ Authentication ) De register Mobile to Old VLR ACK from old MSC/VLR VLR LOCATION UPDATION VLR VPLMN HPLMN Location Update ( TMSI, LAI ) LU Accept ( New TMSI) Update Location Update Location LU Accept (Subs data) LU Accept Update Location LU Accept LU Accept New VLR records subscriber data. • Listens BCCH/FCCH 11/18/2021 97
LOCATION UPDATE SCENARIO - I MS BSS Old MSC/ VLR HLR /AUC New MSC/ VLR 1 2 Channel Request RACH AGCH SDCCH Assignment Location Update Request ( TMSI , LAI 0 ) SDCCH 3 Request IMSI Send IMSI 4 Request For Service ( TMSI ) 11/18/2021 98
MS BSS Old MSC/ VLR HLR/ AUC New MSC/ VLR 5 6 Get Authentication Parameters Authentication Response ( SRES ) SDCCH 7 ( IMSI ) ( RAND,Kc,SRES ) Authentication Parameters SDCCH Authenticate MS ( RAND ) Cipher Radio Channel ( Kc ) Cipher Up Link Channel SDCCH Authentication and Ciphering LOCATION UPDATE SCENARIO - II 11/18/2021 99
8 9 BSS Ciphers Down link Channel . SDCCH Ciphering Complete MS BSS Old MSC/ VLR HLR/ AUC New MSC/ VLR LOCATION UPDATE SCENARIO - III Authentication and Ciphering Up Link Ciphered 11/18/2021 100
LOCATION UPDATE SCENARIO - IV 10 Update Location Update HLR/VLR & TMSI Reallocation De Register Mobile Mobile De-registered 11 MS BSS Old MSC/ VLR HLR/ AUC New MSC/ VLR Location Updated Location Updated Accept TMSI SDCCH 12 13 11/18/2021 101
SDCCH Location Updated Complete Clear Signaling Connection Clear Complete Release Radio Signaling Channel SDCCH 14 16 15 MS BSS Old MSC/ VLR HLR/ AUC New MSC/ VLR LOCATION UPDATE SCENARIO - V Update HLR/VLR & TMSI Reallocation 11/18/2021 102
Connection Management enables different CM sub-layer entities to communicate with their pier entity using different MM connections. Connection Management What is Connection Management ? Different CM sub-layer entities use different MM connections. Different MM connections are identified by Protocol Discriminator PD and, additionally by Transaction Identifier TI. 11/18/2021 103
MS BTS MSC BSC RIL3 - CM LAPD m Layer 1 RIL3 - MM RIL3 - RR Layer 1 LAPD m LAPD Um A bis A link BCDEFG MTP SCCP BSSMAP DTAP MM TCAP DTAP CM U P SCCP M A P Layer 1 Layer 1 GSM Signaling Protocols Overview LAPD MTP I S SCCP BSSMAP BTSM RIL 3- RR BTSM RR 11/18/2021 104
MS RIL3 - CM LAPD m Layer 1 RIL3 - RR CC SMS SS RIL3 - MM CC = Call Connection SMS = Short Message Service SS = Supplementary Services • There are different entities of CM sub- layer. • For each entity different MM connection will be established over same RR connection. Connection Management 11/18/2021 105
• Several MM connections may be active at same time. • All simultaneous MM connections from a given MS use the same RR connection. • An MM connection requires an RR connection. • Mobility Management ( MM) sub-layer provides connection management services to different entities of upper Connection Management ( CM ) sub-layer. • MM connection is established and released on request from a CM entity. Connection Management 11/18/2021 106
Phases Of Connection Management • MM connection establishment initiated by MS. MM Connection Establishment - • MM connection establishment initiated by n/w. MM Connection Information Transfer Phase - • Sending CM messages. • Receiving CM messages. MM Connection Release - • Release associated RR connection. 11/18/2021 107
TIME MS N/W CM Service Request CM Service Reject CM CONNECTION ESTABLISHMENT INITIATED BY MS CM Service Accept 1. IMSI unknown in VLR 2. Illegal ME 3. Network Failure 4. Congestion 5. Service Option not supported. 6. Requested service option not subscribed. 7. Service option temporarily out of order. CM Service Reject Causes : 11/18/2021 108
MS N/W CM MM RR MM CM RR CC SMS SS CC SMS SS CM connection establishment initiated by the Network ( In case no RR connection Exists ) CM Service Reject CM Service Reject 11/18/2021 109
Zone Codes • Zone codes provide mechanism for LAC based subscription. • A set of LACs form a Zone Code. • Subscribers can be given access to a set of Zone codes. • If a subscriber updates location in a Zone Code other than his subscribed ones, it is equivalent to sending IMSI Detach. • For the above event MM will mark Regional Barring flag for the subscriber. Example: • In a case where MSC covers several cities Zone Codes may be used to restrict the subscribers of one city from using n/w services in other cities.( Regional Service ) 11/18/2021 110
Mobile To Land Call Set-up Scenario Phases of Mobile To Land Call • SETUP PHASE ( Mobile Originated Call- MO Call ) • RINGING PHASE • CONVERSATION PHASE • RELEASE PHASE 11/18/2021 111
- REQUEST FOR SERVICE ( CHANNEL ) BY MS - CM SERVICE REQUEST - AUTHENTICATION - CIPHERING - SETUP MESSAGE - EQUIPMENT VALIDATION ( EIR CHECK ) - VALIDATION AT VLR - ASSIGNMENT Mobile To Land Call Set-up Scenario • SETUP PHASE 11/18/2021 112
MS MSC/ VLR BSS 1 2 3 Channel Request Request For Service MOBILE TO LAND CALL - I RACH SDCCH Assignment AGCH CM Service Accept SDCCH 4 CM Service Request 11/18/2021 113
Mobile To Land Call Set-up Scenario • CM SERVICE REQUEST - The Call Control (CC) entity of MS initiates the establishment of CC connection by requesting MM sub-layer of the mobile to establish MM sub-layer connection. - Upon establishment of MM connection CM SERVICE ACCEPT message is received from n/w. • SETUP MESSAGE - CC entity sends a setup message to its peer entity. 11/18/2021 114
MS MSC/ VLR BSS 5 6 Call Setup Request 7 SDCCH SDCCH Call Setup MOBILE TO LAND CALL - II Assign Trunk and radio Assign TCH Radio Assignment Complete Call Proceeding SDCCH SDCCH Trunk and Radio Assignment Complete 11/18/2021 115
Mobile To Land Call Set-up Scenario MSC/VLR Call Setup message Is the requested basic service provisioned for the subscriber ? Yes No Release Complete message to MS Preliminary Digit Analysis Is the number of digits less than the minimum expected? Yes Release Complete message to MS No 1. Check of ODB( BAOC/BOIC/ BOIC Ex HC ) 2. Subscriber call barring checks ( BAOC/BOIC et ASSIGNM ENT 11/18/2021 116
Mobile To Land Call Set-up Scenario • ASSIGNMENT - A BSSMAP message ‘Assignment Command ’ is sent by MSC to BSS. - The message contains a free CIC on A-Interface for terrestrial channel allocated by MSC. - A free TCH is allocated by the BSS and MS is informed to attach to this TCH. - On receiving a response from BSS MSC switches the speech path towards the calling MS. Note : Mobile has not connected user connection as yet. 11/18/2021 117
MS MSC/ VLR BSS 8 9 10 11 Call Setup MOBILE TO LAND CALL - III GMSC PSTN HLR Network Setup ( Dialed Digits ) FACCH Network Alerting Connect Connect Acknowledge FACCH Alerting Connect FACCH Start Billing 11/18/2021 118
MS MSC/ VLR BSS 12 13 14 15 Call Release MOBILE TO LAND CALL - IV GMSC PSTN HLR Disconnect FACCH Network Release Release Complete Release Complete FACCH Release FACCH Clear Command Channel Release 11/18/2021 119
Land To Mobile Call Set-up Scenario Phases of Land To Mobile Call • Routing Analysis • Paging • Authentication • Call-Setup • Ciphering • Call Release ( Mobile Terminating - MT Call ) 11/18/2021 120
Architecture For Mobile Terminated Call GMSC- B BSS-B MS VLR-B MSC-B VISITING PLMN A- Interface Air Interface HLR-B IAM ( ISUP ) 11/18/2021 121
LAND TO MOBILE CALL - I MSC/VLR GMSC PSTN HLR 1 2 Incoming Call 3 4 ( MSISDN ) Get Route ( MSISDN ) Get Route ( IMSI ) Routing Information ( MSRN ) Routing Information ( MSRN ) ( MSRN ) Incoming Call 5 Routing Analysis 11/18/2021 122
MS MSC BSS 6 7 8 Perform Page (TMSI) Page PCH Channel Request ( RACH ) SDCCH Paging Response ( TMSI, LAI ) 9 Access Granted ( AGCH ) Page Response Paging LAND TO MOBILE CALL - II 11/18/2021 123
MS MSC/ VLR BSS 13 14 15 Connect ( off-hook ) FACCH Call Setup LAND TO MOBILE CALL - IV GMSC PSTN HLR FACCH Network Alerting Mobile Alerting Connect Connect Acknowledge Start Billing 11/18/2021 124
MS MSC/ VLR BSS 16 17 18 Disconnect Release 19 FACCH FACCH Call Release LAND TO MOBILE CALL - V GMSC PSTN HLR Network Release FACCH Release Complete Release Complete Clear Command Clear Channel Clear Complete FACCH Stop Billing 11/18/2021 125
Mobile To Mobile Call Set-up Scenario Phases of Mobile To Mobile Call • Request for service. • Authentication • Call-Setup • Ciphering • Call Release • Routing Analysis • Paging • Authentication • Ciphering • Call-Setup Mobile Originating Mobile Terminating • Call-Release 11/18/2021 126
TAX ND GMSC MSC/VLR 1. ND PSTN Subscriber Dials ND Mobile Subscriber in ND. ND LE TANDEM HLR ND MS 9810098100 ND SRI PRN to MSC/VLR ND ACK from MSC/VLR ND (MSRN) MSRN MSISDN MSISDN MSISDN Page(TMSI) 11/18/2021 127
TAX ND TAX CA GMSC MSC/VLR GMSC MSC/VLR 2. ND PSTN Subscriber Dials CA Mobile Subscriber in CA. ND CA LE HLR HLR CA MS 9881098300 ND CA SRI PRN to MSC/VLR CA ACK from MSC/VLR CA (MSRN) MSRN MSISDN Page(TMSI) TANDEM MSISDN MSISDN MSISDN 11/18/2021 128
TAX CA TAX ND GMSC MSC/VLR GMSC MSC/VLR 3. ND PSTN Subscriber Dials ND Mobile Subscriber in CA. CA ND LE TANDEM HLR HLR ND MS 9810098200 CA ND SRI PRN to MSC/VLR CA ACK from MSC/VLR CA (MSRN) MSRN MSRN MSRN MSRN MSISDN MSISDN MSISDN Page(TMSI) 11/18/2021 129
TAX CA TAX ND GMSC MSC/VLR GMSC MSC/VLR 4. CA PSTN Subscriber Dials ND Mobile Subscriber in CA. CA ND LE HLR HLR ND MS 9810098400 CA ND SRI PRN to MSC/VLR CA ACK from MSC/VLR CA (MSRN) MSRN MSISDN Page(TMSI) TANDEM MSISDN MSISDN MSISDN MSRN MSRN MSRN 11/18/2021 130
TAX CA TAX ND GMSC MSC/VLR GMSC MSC/VLR 4.A CA PSTN Subscriber Dials ND Mobile Subscriber in CA CA ND LE HLR HLR ND MS 9810098410 CA ND PRN to MSC/VLR CA ACK from MSC/VLR CA (MSRN) MSRN Page(TMSI) TANDEM MSISDN MSISDN Roaming agreement with Optimal Routing SRI 11/18/2021 131
THANKS ! 11/18/2021 132

More Related Content

PPT
2 g training optimization
byAhmed Gad
 
PPT
Nokia gsm-kpi-analysis-based-on-daily-monitoring-basis-presentation
bymohammed khairy
 
PPT
Part 3 optimization 3G
byHenry Chikwendu
 
DOCX
Layer 3 messages
byJohn Samir
 
PPTX
LTE optimization
byجامعة تعز كلية الهندسة وتقنية المعلومات Taiz University Engineering
 
PDF
Ericsson important optimization parameters
byPagla Knight
 
PDF
LTE Call Processing and Handover
bySitha Sok
 
PDF
2 g and 3g kpi improvement by parameter optimization (nsn, ericsson, huawei) ...
byJean de la Sagesse
 
2 g training optimization
byAhmed Gad
 
Nokia gsm-kpi-analysis-based-on-daily-monitoring-basis-presentation
bymohammed khairy
 
Part 3 optimization 3G
byHenry Chikwendu
 
Layer 3 messages
byJohn Samir
 
LTE optimization
byجامعة تعز كلية الهندسة وتقنية المعلومات Taiz University Engineering
 
Ericsson important optimization parameters
byPagla Knight
 
LTE Call Processing and Handover
bySitha Sok
 
2 g and 3g kpi improvement by parameter optimization (nsn, ericsson, huawei) ...
byJean de la Sagesse
 

What's hot

PPT
GSM Channel concept and SDCCH
byDeepak Joshi
 
PPT
08. DRIVE TEST Analysis
byAmit vishwakarma
 
PPT
Ericsson 2 g ran optimization complete training
bysekit123
 
PPT
Kpi analysis
byavneesh7
 
PDF
2G Handover Details (Huawei)
byMd Mustafizur Rahman
 
DOCX
Cs fall back
byMuhammad Shehzad Ashraf
 
PDF
Cs fallback feature
byAchmad Salsabil
 
PPTX
Gsm frequency-planning-issue2
byswatisabnis87
 
PPT
GSM fundamentals (Huawei)
byShopnomoy Prantor
 
PDF
Irat handover basics
byBamidele Odediya
 
PDF
Best practices-lte-call-flow-guide
byMorg
 
PDF
LTE KPI and PI Formula_NOKIA.pdf
byVahidZibakalam3
 
PDF
gsm-kpi-optimization
byRakesh Solanki
 
PDF
Hw lte rf-optimization-guide
bytharinduwije
 
PDF
Huawei - Access failures troubleshooting work shop
bynavaidkhan
 
PPT
279934373-6-GSM-Paging-Affecting-Factors-Check-Methods-and-Tools-and-Delivera...
byssuser38e5dc1
 
PDF
Optimization guidelines accessibility-ericsson-rev01
byZIZI Yahia
 
PDF
Zte umts-handover-description
byQuyết Nguyễn Hồng
 
DOCX
Tti bundling in fdd and tdd
byLaxman Mewari
 
PPTX
LTE RESOURCE Scheduling (HUAWEI) .pptx
bymahmoudsafaei1987
 
GSM Channel concept and SDCCH
byDeepak Joshi
 
08. DRIVE TEST Analysis
byAmit vishwakarma
 
Ericsson 2 g ran optimization complete training
bysekit123
 
Kpi analysis
byavneesh7
 
2G Handover Details (Huawei)
byMd Mustafizur Rahman
 
Cs fall back
byMuhammad Shehzad Ashraf
 
Cs fallback feature
byAchmad Salsabil
 
Gsm frequency-planning-issue2
byswatisabnis87
 
GSM fundamentals (Huawei)
byShopnomoy Prantor
 
Irat handover basics
byBamidele Odediya
 
Best practices-lte-call-flow-guide
byMorg
 
LTE KPI and PI Formula_NOKIA.pdf
byVahidZibakalam3
 
gsm-kpi-optimization
byRakesh Solanki
 
Hw lte rf-optimization-guide
bytharinduwije
 
Huawei - Access failures troubleshooting work shop
bynavaidkhan
 
279934373-6-GSM-Paging-Affecting-Factors-Check-Methods-and-Tools-and-Delivera...
byssuser38e5dc1
 
Optimization guidelines accessibility-ericsson-rev01
byZIZI Yahia
 
Zte umts-handover-description
byQuyết Nguyễn Hồng
 
Tti bundling in fdd and tdd
byLaxman Mewari
 
LTE RESOURCE Scheduling (HUAWEI) .pptx
bymahmoudsafaei1987
 

Similar to Skg gsm channel concept ; call processing

PDF
GSM Air Interface
byNaveen Jakhar, I.T.S
 
PDF
Gsmdocument 131119095413-phpapp01
byHoang Giang
 
PPT
Sdcch
byDeepak Sharma
 
PPT
GSM CHANNEL CONCEPT & CALL PROCESSING.ppt
byINMYFEELINGS
 
PPT
Gsm air interface
byRizwan Pasha M
 
PDF
Gsm physical and-logical_channels
byTushar Saxena
 
PPT
SDCCH channel.ppt
byVahidZibakalam3
 
PPTX
GSM FRAME STRUCTURE.pptx
byRasufsd
 
PPT
Logical channels
byUthsoNandy
 
PDF
GSM network_wireless networks course.pdf
byliekeb00
 
PPT
UNIT 5 new -Handoff technique in cellular communication
byblessinapreethiece
 
PPTX
Dr. Tanuja Patgar-GSM History and TDMA pptx
bytanujaharish2
 
PDF
Sdcch 121130233301-phpapp02
byRasim Levashov
 
PPTX
GSM lectures_1, giving details about architecture.pptx
byatul397017
 
DOCX
Telecom Interview
bySajal Das
 
PPT
Sdcch 12704657711474-phpapp02
byTapiwa Munetsi
 
PPTX
It802 d mobilecommunicationspart4
byDebasis Das
 
TXT
New rough
bybibhucharan13
 
PDF
39540950 gsm-ion-course-130814024028-phpapp01
byAhlem DRIRA
 
PPTX
6 Weeks Industrial Training In Telecom In Chandigarh
byArcadian Learning
 
GSM Air Interface
byNaveen Jakhar, I.T.S
 
Gsmdocument 131119095413-phpapp01
byHoang Giang
 
Sdcch
byDeepak Sharma
 
GSM CHANNEL CONCEPT & CALL PROCESSING.ppt
byINMYFEELINGS
 
Gsm air interface
byRizwan Pasha M
 
Gsm physical and-logical_channels
byTushar Saxena
 
SDCCH channel.ppt
byVahidZibakalam3
 
GSM FRAME STRUCTURE.pptx
byRasufsd
 
Logical channels
byUthsoNandy
 
GSM network_wireless networks course.pdf
byliekeb00
 
UNIT 5 new -Handoff technique in cellular communication
byblessinapreethiece
 
Dr. Tanuja Patgar-GSM History and TDMA pptx
bytanujaharish2
 
Sdcch 121130233301-phpapp02
byRasim Levashov
 
GSM lectures_1, giving details about architecture.pptx
byatul397017
 
Telecom Interview
bySajal Das
 
Sdcch 12704657711474-phpapp02
byTapiwa Munetsi
 
It802 d mobilecommunicationspart4
byDebasis Das
 
New rough
bybibhucharan13
 
39540950 gsm-ion-course-130814024028-phpapp01
byAhlem DRIRA
 
6 Weeks Industrial Training In Telecom In Chandigarh
byArcadian Learning
 

More from Saroj Kumar Gochhayat

PPTX
GPRS EDGE 3G 4G
bySaroj Kumar Gochhayat
 
PDF
30 CHL PCM PDH SDH BY SKG
bySaroj Kumar Gochhayat
 
PDF
Antenna
bySaroj Kumar Gochhayat
 
PPT
Ngn
bySaroj Kumar Gochhayat
 
PDF
Digital multiplexing and transmission concept
bySaroj Kumar Gochhayat
 
PDF
Optical fibre cable
bySaroj Kumar Gochhayat
 
PDF
Ae
bySaroj Kumar Gochhayat
 
PDF
Ae
bySaroj Kumar Gochhayat
 
GPRS EDGE 3G 4G
bySaroj Kumar Gochhayat
 
30 CHL PCM PDH SDH BY SKG
bySaroj Kumar Gochhayat
 
Antenna
bySaroj Kumar Gochhayat
 
Ngn
bySaroj Kumar Gochhayat
 
Digital multiplexing and transmission concept
bySaroj Kumar Gochhayat
 
Optical fibre cable
bySaroj Kumar Gochhayat
 
Ae
bySaroj Kumar Gochhayat
 
Ae
bySaroj Kumar Gochhayat
 

Skg gsm channel concept ; call processing

  • 1.
  • 2.
    Channels • Physical Channels –Associated with frequency bands, time slots, codes – Physical channels transfer bits from one network element to another • Logical Channels – Distinguished by the nature of carried information and the way to assemble bits into data units – Three types • one-to-one: traffic channels between a BTS and a MS • one-to-many: synchronization signals from BTS to MSs in a cell • many-to-one: from MSs to the same BTS 11/18/2021 2
  • 3.
    Bursts and Frames 2047 3 2 1 0 Hyperframe = 2048 Super frames = 2,715,648 TDMA frames 3 Hours 28 Minutes 53 Seconds and 760 milliseconds 50 0 25 0 1 superframe = 1326 TDMA frames (6.12 seconds) = 51 (26-frame) multi frames or 26 (51-frame) multi frames 51 Multiframe Approx 235 mS 26 Multiframe 120 mS 25 24 2 1 0 50 49 48 1 0 7 6 5 4 3 2 1 0 TDMA frame 4.615 mS 11/18/2021 3
  • 4.
    Organisation of Speech& Data 24 25 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 BP 7 BP 6 BP 5 BP 4 BP 3 BP 2 BP 1 BP 0 8.25 3 57 1 26 1 57 3 Frames 0-11 : TCH Frames 12 : SACCH Frames 13-24 : TCH Frames 25 : Unused 26 – frame multiframe Duration: 120 ms TDMA frame Duration: 60/13 ms =4.615 ms Tail bits Data bits Stealing bit Training sequence Stealing bit Data bits Tail bits Guard space Normal burst Duration 15/26 ms 11/18/2021 4
  • 5.
    Bursts and Frames •There are two types of multiframe – 26 TDMA-frame multiframe is used to carry TCH, SACCH and FACCH – 51 TDMA-frame multiframe is used to carry BCCH, CCH, SDCCH and SACCH 11/18/2021 5
  • 6.
    Burst • The informationcontained in one time slot is a burst • Five types of burst – Normal Burst (NB) • To carry information on traffic and control channels – Frequency Correction Burst (FB) • To synchronize the frequency of the mobile – Synchronization Burst (SB) • To synchronize the frames of the mobile – Access Burst (AB) • For random and handover access – Dummy Burst • For padding the frame 11/18/2021 6
  • 7.
    Bursts and Frames 01 2 3 4 5 6 7 GP 8.25 TB 3 Encrypted bits 57 flag 1 Training sequence 26flag 1 Encrypted bits 57 TB 3 TB 3 Fixed bits 142 GP 8.25 TB 3 GP 8.25 TB 3 TB 3 Encrypted bits 39 Synchronization sequence 64 Encrypted bits 39 TB 3 Synchronization sequence 41 Encrypted bits 36 TB 3 GP 68.25 GP 8.25 TB 3 TB 3 Mixed bits 58 Training sequence 26 Mixed bits 58 Normal Burst (NB) Frequency correction burst (FB) Synchronization burst (SB) Access burst (AB) Dummy burst (DB) TB: Tail bits GP: Guard period 1 TDMA frame = 8 timeslots 1 timeslot = 156.25 bit durations (15/26 =~ 0.577 ms) (1 bit duration 48/13 =~ 3.69 micro sec) 11/18/2021 7
  • 8.
    Normal Burst T3 CodedData 57 Training Sequence 26 Coded Data 57 GP 8.25 S1 S1 T3 148 bits = 0.54612 msec This burst is used to carry information on TCH and on the control channelsBCCH, PCH, AGCH, SDCCH, ASCCH and FACCH. Note: GP (Guard Period) 11/18/2021 8
  • 9.
    Random Access Burst T8Synchronization sequence 41 Coded Data 36 Guard Period 68.25 T3 88 bits = 0.32472 msec 68.25 bits = 0.252 msec which is equivalent to 75.5 km propagation delay. That is, the max. allowed distance between mobile station and BTS is 37.75 km. Based on other system parameters, the max cell size is 35 km in GSM. 11/18/2021 9
  • 10.
    Traffic channels (TCH) Signaling channel TCH/F: Full-rate TrafficChannel TCH/H: Half-rate Traffic Channel FCCH: Frequency correction SCH: Synchronization BCCH: Broadcast control PCH: Paging AGCH: Access grant RACH: Random access SDCCH: Stand-alone dedicated control SACCH: Slow associated control FACCH: Fast associated control Two-way Base-to- mobile Two-way Logical Channel List BCH CCCH DCCH 11/18/2021 10
  • 11.
    20 higher GSM framestructures 935-960 MHz 124 channels (200 kHz) downlink 890-915 MHz 124 channels (200 kHz) uplink time 1 2 3 4 5 6 7 8 GSM TDMA frame 4.615 ms GSM - TDMA/FDMA GSM time-slot (normal burst) 546.5 µs 577 µs tail user data Training S guard space S user data tail guard space 3 bits 57 bits 26 bits 57 bits 1 1 3 S: indicates data or control ? 11/18/2021
  • 12.
  • 13.
    LOGICAL CHANNELS One ormore logical channels can be transmitted on a physical channel. There are different types of logical channels. The type of logical channel is determined by the function of the information transmitted over it. The following types of logical channels exist: Traffic channels Broadcast channels Common control channels Dedicated control channels Note that the first channel type carries speech and data, and the other types control information (signaling). 11/18/2021 22
  • 14.
    Traffic Channels Full RateTraffic Channel (TCH/FS) Traffic Channel Multiframes are composed of only 26 TDMA frames. On each multiframe, there are 24 frames for Traffic Channels, 1 frame for a SACCH, and the last frame is Idle. Half Rate Traffic Channel (TCH/HS) When using Half-Rate Speech Encoding (TCH/HS), the speech encoding bit rate is 5.6 kb/s, so one time slot can handle two half-rate channels. In this case, one channel will transmit every other TDMA frame, and the other channel would be transmitted on the other frames. The final frame (25), which is normally used as an Idle frame, is now used as a SACCH for the second half-rate channel. 11/18/2021 23
  • 15.
  • 16.
    Here is themath: As you remember from the Introduction to TDMA Tutorial. A single time slot has a data throughput of 24.7 kilobits per second (kb/s). 1. Calculate bits per TCH Multiframe: 114 bits per burst, 24 of the 26 frames used for voice/data. 114 bits × 24 frames = 2736 bits 2. Calculate bits per microsecond (ms): 2736 bits per TCH multiframe, multiframe duration = 120ms 2736 bits ÷ 120ms = 22.8 bits/msec 3. Convert microseconds (ms) to seconds: 22.8 bits/sec × 1000 = 22,800 bits per second (22.8 kb/s) 11/18/2021 25
  • 17.
  • 18.
    TRAFFIC CHANNELS The trafficchannels are used to send speech or data services. There are two types of traffic channels. They are distinguished by their transmission rates. The following traffic channels are provided: TCH/F (Traffic CHannel Full rate) The TCH/F carries information at a gross bit rate of 22.8 kbit/s (after channel coding). The net (or effective) bit rate at the TCH/F is for speech 13 kbit/s and for data 12, 6 or 3.6 kbit/s (before channel coding). The transmission rates of the data services allow services which are compatible to the existing, respectively, 9.6, 4.8 and 2.4 kbit/s PSTN and ISDN services. TCH/H (Traffic Channel Half rate) The TCH/H carries information at a gross bit rate of 11.4 kbit/s. The net bit rate at the TCH/H is for speech 5.6 kbit/s and for data 6 or 3.6 kbit/s. 11/18/2021 27
  • 19.
    TCH/EFR (Enhanced Fullrate) The EFR provides a voice coding algorithm offering improved speech quality. The algorithm is fully compatible with a BSM speech quality. The algorithm is fully compatible with a GSM 13 kbit/s speech channel. The main benefit will be improved voice quality which offers prospects to compete with PSTN networks. A TCH/F or a TCH/H may also be used to send signaling information (for example call forwarding and short messages). 11/18/2021 28
  • 20.
    Signaling Channels Signaling channel Broadcast Channels(BCH Cell Broadcast Channel (CBCH) Synchronization Channel (SCH) Frequency Correction Channel (FCCH) Broadcast Control Channel (BCCH) Common Control Channels (CCCH) Paging Channel (PCH) Random Access Channel (RACH) Access Grant Channel (AGCH) Standalone Dedicated Control Channel (SDCCH) Associated Control Channel (ACCH) Fast Associated Control Channel (FACCH) Slow Associated Control Channel (SACCH) 11/18/2021 29
  • 21.
  • 22.
    Broadcast Channels (BCH) •To help the MH (Mobile Handset) measures – to turn to a BTS – to listen for the cell information • to start roaming, waiting for calls to arrive, making calls – Because BTSs are not synchronized with each other, every time a MH decides to camp to another cell, its FCCH, SCH, and BCCH must be read. 11/18/2021 31
  • 23.
    BROADCAST CHANNELS • Theinformation distributed over the broadcast channels helps the mobile stations to orient themselves in the mobile radio network. • The broadcast channels are point-to- multipoint channels which are only defined for the downlink direction (BTS to the mobile station). 11/18/2021 32
  • 24.
    BCCH (Broadcast Control Channel) •It inform the Mobile about system confirmation parameter • LAI Location Area Identity, • Cell -Identity • Neighboring Cell Identity. • MS select best cell to attach BCCH on full power, never Frequency hopped. The BCCH is also known as beacon. 11/18/2021 33
  • 25.
    LAI = MCC+ MNC + LAC MCC - Mobile Country Code. For India 404/405 USA 310/316 It is assigned by the ITU-T MNC - Mobile Network Code. . It is assigned by the government (DOT) of each country West bengal 74, Bihar-75,Orissa-76 LAC - Location Area Code . It is assigned by an operator • Maximum length of LAC is 16 bits. • Thus there can be maximum of 216 =65,536 Location Areas defined in one GSM PLMN. MCC MNC LAC 3 digits 2 digits 2 octets max LAI ( 16 bits ) Location Related Identities 11/18/2021 34
  • 26.
    CELL GLOBAL IDENTITY(CGI) The CGI is used for cell identification within a location area. This is done by adding a Cell Identity (CI) to the components of a LAI. CI has a length of 16 bits. CGI consists of:CGI = MCC + MNC + LAC + CI 11/18/2021 35
  • 27.
    BASE STATION IDENTITY CODE(BSIC) NCC = Network Color Code (3 bits 0-7), identifies the PLMN. Note that it does not uniquely identify the operator. NCC is primarily used to distinguish between operators on each side of a border. BCC = Base Station Color Code (3 bits 0-7), identifies the Base Station to help distinguish between BTS using the same BCCH frequencies. 113 77 76 79 66 63 FOR BSNL NCC=7 7-0 ,7-1,……..7-7. 12 NON HOPING FREQ X 7=96 NO OF COMBINATION . BCCH+BSIC COMBINATION SHOULD NOT BE SAME IN NEAR BY. 11/18/2021 36
  • 28.
    Base Station IdentificationCode (BSIC). • BSIC allows for cell changes across cells that are not necessarily neighbors in a geographic sense. So an MS could do a cell reselection across cells with the same frequency but different BSIC. Such a possibility arises if the immediate neighbors are hidden (no line of sight) whereas a far away cell can provide better service due to clear LOS radio path. BSIC+ARFCN is unique in a particular area. 11/18/2021 37
  • 29.
  • 30.
    After the subscriberhas switched on his mobile station and typed in his PIN code, the mobile station searches for a network •But how does it log on to the network the subscriber is registered with? •For this purpose, the BTS sends out the Frequency Correction Channel (FCCH) at short regular intervals, to help the mobile station find a frequency for downlink reception and adjust its frequency oscillator for the uplink transmission •To do so, it picks out the strongest received signal •The Synchronization Channel (SCH) then helps the mobile station to synchronize itself to timeslot 0 sent out by the BTS •This means the mobile station must adjust to the rhythm given bythe BTS •The SCH contains the TDMA frame number as well as the Base Station Identity Code, containing basic information about the network operator that canbe compared with the info stored on the SIM card •After this step, the mobile is able to decide whether it has chosen the proper network. If not, it starts the same procedure again trying with the second strongest FCCH received •While the mobile station uses the FCCH to adjust its frequency, and the SCH for synchronization and network identification, the Broadcast Control Channel (BCCH), which is also sent by the BTS, supplies the mobile station with additional information about the selected cell, for example for ciphering •For some Value Added Services, for example location-dependent services, additional information has to be transmitted from the BTS to the mobile •The Cell Broadcast Channel CBCH is used for this purpose to transmit geographical parameters, for example Gauss-Krueger-Coordinates of the BTS, to the mobile •The FCCH, SCH, BCCH and CBCH are Broadcast Channels, and exist only in the downlink •They are the first logical channels belonging to the Common Channels. 11/18/2021 39
  • 31.
    Frequency Correction Channel (FCCH) •Provide MH with the frequency reference of the system – To enable the Mobile Handset (MH) to synchronize with the frequency • Transmission properties – Transmit on the down-link – Point to multi-point. 11/18/2021 40
  • 32.
    HSN,MAIO,FREQ PLANNING. BSNL got31 no of radio carrier. Fixed F1 to F15 Hopping Freq F16 to F31. CYCLIC HSN=0, MAIO=1,MAIO2 RANDOM HSN=1. HSN=63. MAIO Sequence (Mobile Allocation Index Offset) F16,F17,F18,F19..F31 MAIO=1 F17,F18,F19..F31,F16 MAIO=2 F18,F19..F31,F16, F17MAIO=3 41 F5 F9 F1 F16 F8 F12 F4/ F19 F6 F10 F2/ F17 F7 F11 F3/ F18 4/12 11/18/2021
  • 33.
    FCCH (Frequency Correction Channel) Tocommunicate with the BTS the mobile station must tune to the BTS. The FCCH transmits a constant frequency shift of the radio frequency carrier that can be used by the mobile station for frequency correction. 11/18/2021 42
  • 34.
    Synchronization Channel (SCH) • MHsynchronize with the structure within the locative cell – MH can receive information from the proper time slots on the TDMA structure • To ensure a GSM BTS is chose – The Base Station Identity Code (BSIC) can only be decoded by a GSM BTS • Transmission properties – Transmit on down-link – Point to multi-point. 11/18/2021 43
  • 35.
    SCH (Synchronization CHannel) The SCHis used to time synchronize the mobile stations. The data on this channel carries the TDMA frame number and the BSIC (Base Station Identity Code). 11/18/2021 44
  • 36.
    1.The A-bisinterface connectsthe Base Transceiver Station (BTS) with the Base Station Controller (BSC) 2. In the PCM30 configuration, the data at this interface is transmitted via cable or via microwave transmission at a bit rate of 2 Mbit/s 3. A cable connection is more resistent to interference, but a network operator must lease it from a fixed network operator 4. The microwave links can be operated independently, and are easily configured by the network operator, but they are more sensitive to interference •4 types of information can be transmitted over the A- bis interface: –user information –synchronization data –signaling information –and data for the operation and maintenance of the BTS, known as O&M alarms 11/18/2021 45
  • 37.
    Broadcast Control Channel (BCCH) •BTS broadcast cell information to MH – LAI ( Location Area Identity), to start roaming, waiting for calls to arrive, making calls – maximum output power allowed in the cell – information about BCCH carriers for the neighboring cells • MH will perform measurement to BTS • Transmission properties – Transmit on down-link – Point to multi-point 11/18/2021 46
  • 38.
    CBCH (Cell Broadcast CHannel) •The CBCH is used for the transmission of generally accessible information (Short Message Service messages) in a cell, which can be polled by the mobile station. 11/18/2021 47
  • 39.
  • 40.
    • The mobilestation has now adjusted its frequency and synchronized its TDMAs, and has picked out the best cell available•But before it can be reached by other subscribers, and before itcan initiate calls, a Location Update and authentication procedure are necessary•Only after that is the mobile station logged on to the network and has radio coverage•It can now be reached by other mobile stations, or initiate a call. For this purpose, Common Control Channels are required•Common Control Channels are "point-to-multipoint" channels, which exist either only in the uplink, or only in the downlink•When a subscriber is called, the Paging Channel (PCH) is broadcast in the downlink by all base stations within a Location Area, so that the mobile station concerned canreact•To initiate a call, the mobile station sends out a Random AccessChannel (RACH), which carries its identification and request, for example for registration, to thenetwork•This channel only exists in the uplink. In return, the network sends the Access Grant Channel (AGCH) in the downlink direction, to assign resources to the mobile station, by granting it a Stand-Alone Dedicated Control Channel, SDCCH. The PCH, RACH and AGCH form the group ofthe Common Control Channels belonging also to the Common Channels. 11/18/2021 49
  • 41.
    COMMON CONTROL CHANNELSCONT.. PCH (Paging CHannel) The PCH is used in the downlink direction for paging the mobile stations. ----used for paging when Incoming call. AGCH (Access Grant CHannel) The AGCH is also used in the downlink direction. A logical channel for a connection is allocated via the AGCH if the mobile station has requested such a channel via the RACH. RACH (Random Access CHannel) The RACH is used in the uplink direction by the mobile stations for requesting a channel for a connection. It is an access channel that uses the slotted Aloha access scheme. The Following figure gives an overview of the different types of logical channels. 11/18/2021 50
  • 42.
    Paging Channel (PCH) •Used by BTS to page particular MH in the cell – MH actively listen to PCH to check contact info within certain time – Contact could be incoming call or short message • Contact info on PCH include – IMSI (MH’s identity number), or – TMSI (temporary number) • Transmission properties – Transmit on down-link – point to point 11/18/2021 51
  • 43.
    Random Access Channel (RACH) •Used by MH to request a dedicated channel for call setup – Shared by any MH attempts to access the network – Channel request message contains the reason for the access attempt • Transmission properties – Transmit on up-link – Point to pint. 11/18/2021 52
  • 44.
    Access Grant Channel(AGCH) • The network assigns a signaling channel via AGCH – A Stand alone Dedicated Control Channel (SDCCH) is assigned • Transmission properties – Transmit on down-link – Point to point 11/18/2021 53
  • 45.
    Dedicated Control Channels(DCCH) • DCCH are used for transferring nonuser information between the network and the MH – Messages on DCCH Including • channel maintenance • mobility management • radio resource management • Four kinds of DCCH – Stand alone Dedicated Control Channel (SDCCH) – Cell Broadcast Channel (CBCH) – Slow Associated Control Channel (SACCH) – Fast Associated Control Channel (FACCH) 11/18/2021 54
  • 46.
    Dedicated control channels are full-duplex, point-to-point channels.They are used for signaling between the BTS and a certain mobile station 11/18/2021 55
  • 47.
    Slow Associated Control Channel(SACCH) • Carries control and measurement parameters along with routine data necessary to maintain a radio link between the MH and the BTS, which is always allocated to a TCH or SDCCH. – On the uplink, MS sends averaged measurements (signal strength and quality) of current and neighboring BCCH – On downlink, MS receives information about transmitting power to use and an instruction with time advance/retard • Transmission properties – Bidirectional channel, transmit on both up and down link – Point to point In 26 Frame Traffic Multi frame 13th frame (frame no. 12) is used for SACCH. Note that the SACCH is only used for non-urgent procedures. 11/18/2021 56
  • 48.
    FACCH (Fast AssociatedControl Channel) • The FACCH is used as a main signaling link for the transmission of signaling data (for example handover commands). • It is also required for every call set-up and release. • During the call the FACCH data is transmitted over the allocated TCH instead of traffic data; this is marked by a flag called a stealing flag. • The process of stealing a TCH for FACCH data is called pre-emption. - Used for Urgent Signalling; like handover during a call. Appears on demand. 11/18/2021 57
  • 49.
    Stand alone Dedicated ControlChannel (SDCCH) • Transfer signaling information between the BTS and the MH • Typically used for location updating prior to use of a traffic channel • Transmission properties – Bidirectional channel, transmit on both up and down-link – Point to point. 11/18/2021 58
  • 50.
    Cell Broadcast Channel (CBCH) •To carry Short Message Service Cell Broadcast (SMSCB) • Use the same physical channel as SDCCH • Transmission properties – Transmit on down-link – Point to multi-point 11/18/2021 59
  • 51.
    SDCCH (Stand-alone Dedicated ControlChannel) • The SDCCH is a duplex, point-to-point channel which is used for signaling in higher layers. • It carries all signaling between the BTS and the mobile station when no TCH is allocated. • The SDCCHs are used for service requests (for example Short Message Service), location updates, subscriber authentication, ciphering initiation, equipment validation and assignment to a TCH. The net SDCCH bit rate is about 0.8 kbit/s.(160 x 5 =800bits) 11/18/2021 60
  • 52.
    Control Channel UP LIN K DOWN LINK FUNCTION BroadcastControl Channel (BCCH) ▼ These parameters include the Location Area Code (LAC), the Mobile Network Code (MNC), the frequencies of neighboring cells, and access parameters Frequency Correction Channel (FCCH) ▼ This channel contains frequency correction bursts Synchronization Channel (SCH) ▼ This channel is used by the MS to learn the Base Station Information Code (BSIC) as well as the TDMA frame number (FN). This lets the MS know what TDMA frame they are on within the hyperframe. Cell Broadcast Channel (CBCH) ▼ Broadcast such as weather, traffic, sports, stocks, etc. Messages can be of any nature depending on what service is provided. The CBCH is nt allocated a slot for itself, it is assigned to an SDCCH Paging Channel (PCH) ▼ incoming traffic. voice call, SMS, or some other form of traffic. Random Access Channel (RACH) ▲ MS to request an initial dedicated channel from the BTS Access Grant Channel (AGCH) ▼ This channel is used by a BTS to notify the MS of the assignments of an initial SDCCH for initial signaling Standalone Dedicated Control Channel (SDDCH) ▲ ▼ This channel is used for signaling and call setup between the MS and the BTS. Fast Associated Control Channel (FACCH) ▲ ▼ This channel is used for control requirements such as handoffs. There is no TS and frame allocation dedicated to a FAACH. The FAACH is a burst-stealing channel, it steals a Timeslot from a Traffic Channel (TCH). Slow Associated Control Channel (SACCH) ▲ ▼ This channel is a continuous stream channel that is used for control and supervisory signals associated with the traffic channels. 11/18/2021 61
  • 53.
    62 Channel Combination Type Severallogic channels combine together in some way to form some specific types of channel to transmit user data or signaling information. They are called combined channels. One combined channel can be mapped to a physical channel. 11/18/2021
  • 54.
    CHANNEL COMBINATIONS The channelcombinations are: 1. TCH/F + FACCH/F + SACCH/F 2. TCH/H + FACCH/H + SACCH/H 3. (TCH/F + FACCH/F + SACCH/F) or (TCH/H + FACCH/H + SACCH/H) 4. FCCH + SCH + CCCH + BCCH 5. FCCH + SCH + CCCH + BCCH + SDCCH/4 + SACCH/4 6. BCCH + CCCH (CCCH = PCH + RACH + AGCH) 7. SDCCH/8 + SACCH/8 The extensions “/4” and “/8” in the above mentioned terms mean, respectively, that four and eight logical channels are mapped onto one physical channel (timeslot). 11/18/2021 63
  • 55.
    Control Channel 4. FCCH+ SCH + CCCH + BCCH UPLINK DOWNLINK 6. CCCH + BCCH 11/18/2021 64
  • 56.
    Downlink The SACCH thatis associated with each SDCCH is only transmitted every other Multiframe. Each SACCH only gets half of the transmit time as the SDCCH that it is associated with. So, in one Multiframe, SACCH0 and SACCH1 would be transmitted, and in the next Multiframe, SACCH2 and SACCH3 would be transmitted. Uplink FCCH + SCH + BCCH + CCCH + SDCCH/4(0..3) + SACCH/C4(0..3) The two sequential Multiframe would look like this: 11/18/2021 65
  • 57.
    Downlink Uplink You will alsonotice that the downlink and uplink Multiframes do not align with each other. This is done so that if the BTS sends an information request to the MS, it does not have to wait an entire Multiframes to receive the needed information. The uplink is transmitted 15 TDMA frames behind the downlink. For example, the BTS might send an authentication request to the MS on SDCCH0 (downlink) which corresponds to TDMA frames 22-25. The MS then has enough time to process the request and reply on SDCCH0 (uplink) which immediately follows it on TDMA frames 37-40. 11/18/2021 66
  • 58.
    SDCCH/8(0-7) + SACCH/C8(0- 7) Once again, the SACCH that is associated with an SDCCH is only transmitted every other multiframe. Two consecutive Multiframes would look like this: Downlink Uplink SKGOCHHAYAT,SDE(COMP) 11/18/2021 67
  • 59.
    68 • Small capacitycell with only 1 TRX TN0: FCCH+SCH+CCCH+BCCH+SDCCH/4(0,_,3)+SACCH /C4(0,_,3); TN1-7: TCH/F+FACCH/F+SACCH/TF • The medium-size cell with 4 TRXs 1TN0 group: FCCH+SCH+BCCH+CCCH; 2 SDCCH/8(0,_,7)+SACCH/C8(0,_,7); 29 TCH/F+FACCH/F+SACCH/TF Channel Assignment inside cells 11/18/2021
  • 60.
    69 • Large-size cellwith 12 TRXs 1 TN0 group: FCCH+SCH+BCCH+CCCH; 1 TN2 group, 1 TN4 group and 1 TN6 group: BCCH+CCCH; 5 SDCCH/8(0,_,7)+SACCH/C8(0,_,7); 87 TCH/F+FACCH/F+SACCH/TF Channel Assignment inside cells 11/18/2021
  • 61.
    medium-sized cell mightbe set up with 4 TRX (ARFCNs) 11/18/2021 70
  • 62.
    Modes Mobile Station( MS ) • MS Switched Off - can not receive incoming paging messages. - can not make outgoing call. - No dedicated channel is associated with it. • MS Switched On - can receive incoming paging messages. And in Idle Mode - can make outgoing call. - No dedicated channel is associated with it. • MS in Dedicated Mode -MS is in conversation and a dedicated traffic channel TCH is associated with it. 11/18/2021 71
  • 63.
    Technical Terms Usedw.r.t. MM (Mobility Management ) • IMSI – International Mobile Subscriber Identity • IMSISDN – Mobile Subscriber ISDN number • IMEI – International Mobile Equipment Identity • TMSI – Temporary Mobile Subscriber Identity • MSRN – Mobile Subscriber Roaming Number • LAI – Location Area Identity • A3 – Authentication Algorithm • A5 – Ciphering Algorithm • A8 – Kc Generation Algorithm 11/18/2021 72
  • 64.
    GSM Network Identities 1.MSISDN – Mobile Subscriber ISDN number Subscriber Related Identities - CC NDC SN Max. 15 digits CC – Country Code. NDC – Network Destination Code. SN – Subscriber Number. Eg 91-98100-12345 11/18/2021 73
  • 65.
    2. IMSI –International Mobile Subscriber Identity. 3. TMSI – Temporary Mobile Subscriber Identity Subscriber Related Identities - MCC MNC MSIN Max. 15 digits MCC – Mobile Country Code. MNC – Mobile Network Code. MSIN – Mobile Subscriber Identification Number. GSM Network Identities Equipment Related Identities - 1. IMEI – International Mobile Equipment Identity 11/18/2021 74
  • 66.
    1. MSRN –Mobile Subscriber Roaming Number It is a temporary number used for routing the call to MS. Format : MSRN = CC + NDC + SN CC = Country Code NDC = Network Destination Code For example for Patna MSC in IMPCS network MSRN looks like 91 98750 00100. SN = Subscriber Number Location Related Identities 11/18/2021 75
  • 67.
    PSTN GMSC HLR MSC VLR MSISDN 1 MSISDN 2 IMSI 3 IMSI MSRN 4 MSRN 5 MSRN6 MSRN 7 MSRN Location Related Identities 11/18/2021 76
  • 68.
  • 69.
    INTERNATIONAL MOBILE EQUIPMENT IDENTITY(IMEI) IMEI = TAC + FAC + SNR + spare TAC = Type Approval Code, determined by a central GSM body. FAC = Final Assembly Code, identifies the manufacturer. SNR = Serial Number, an individual serial number of six digits uniquely identifies all equipment within each TAC and FAC. Spare = A spare bit for future use. When transmitted by the MS this digit should always be zero. IMEI has the total length of 15 digits. 11/18/2021 78
  • 70.
    MSRN MSRN = CC+ NDC + SN CC = Country Code NDC = National Destination Code SN = Subscriber Number NOTE: In this case, SN should not be interpreted as the actual subscriber identity. It represents the address to the serving MSC. 11/18/2021 79
  • 71.
    MS Initialization /Network Attachment 1. MS Powered on. - FCCH present in time slot T0 & has a fixed pattern of 142 0’s. - MS scans entire 124 carriers and monitors RF levels. - several readings are taken to get accurate estimate the channel power. - MS then searches for Frequency Correction burst (FCCH) on the channel with strongest RF level. 2. Frequency Synchronization - After tuning to FCCH MS synchronizes in time with SCH . 11/18/2021 80
  • 72.
    - SCH occursin next frame in same time slot as FCCH. - The occurrence of SCH is eight burst period ( BP’s ) later than FCCH. 3. Synchronization in Time - After successful synchronization the MS will read the TDMA frame number and Base Station Identity Code BSIC . - SCH contains precise timing information and current frame number to which MS is synchronized. - BSIC consists of - PLMN colour code ( 3 bits ) - BS colour code ( 3 bits ). MS Initialization / Network Attachment 11/18/2021 81
  • 73.
    • MS decodesinformation on BCCH and gets Location Area Identity ( LAI ). • If the information stored on SIM does not match with the information MS thinks that it has moved to new location and sends LA update request to BSS. • MS location is determined by cell identification of strongest BCCH signal received by MS. • MS regularly measures the received signal strength of BCCH at least once every 6 sec ( Superframe Duration). • MS stores at least six strongest BCCH and their cell identification in SIM. MS Initialization / Network Attachment 11/18/2021 82
  • 74.
    Network Attachment Process MS .Cell should be of selected PLMN. Switch -on Measure strongest BCCH channels PLMN Selection Cell Selection Location Update Idle-Mode . Cell should not be “ barred “. . Radio path loss between BTS and the MS must be below a threshold set by the operator. ( Register its presence to the network. ) Limited Service Mode 11/18/2021 83
  • 75.
    MS BTS MSC BSC RIL3- CM LAPD m Layer 1 RIL3 - MM RIL3 - RR Layer 1 LAPD m LAPD Um A bis A link BCDEFG MTP SCCP BSSMAP DTAP MM TCAP DTAP CM U P SCCP M A P Layer 1 Layer 1 GSM Signaling Protocols Overview LAPD MTP I S SCCP BSSMAP BTSM RIL 3- RR BTSM RR 11/18/2021 84
  • 76.
    What is MobilityManagement? • Subscriber Data management at MSC/VLR • Subscriber data from HLR are retrieved by MM at the time of first location up-dating of a subscriber. • Dynamic data changes by subscriber are also managed by MM at MSC/VLR. • Operator initiated data changes for a subscriber are also managed by MM. 11/18/2021 85
  • 77.
    Security in GSM •Security services – access control/authentication • user  SIM (Subscriber Identity Module): secret PIN (personal identification number) • SIM  network: challenge response method – confidentiality • voice and signaling encrypted on the wireless link (after successful authentication) – anonymity • temporary identity TMSI (Temporary Mobile Subscriber Identity) • newly assigned at each new location update (LUP) • encrypted transmission • 3 algorithms specified in GSM – A3 for authentication (“secret”, open interface) – A5 for encryption (standardized) – A8 for key generation (“secret”, open interface) “secret”: • A3 and A8 available via the Internet • network providers can use stronger mechanisms 11/18/2021 86
  • 78.
    GSM - authentication A3 RAND Ki 128bit 128 bit SRES* 32 bit A3 RAND Ki 128 bit 128 bit SRES 32 bit SRES* =? SRES SRES RAND SRES 32 bit mobile network SIM AC MSC SIM Ki: individual subscriber authentication key SRES: signed response 11/18/2021 87
  • 79.
    GSM - keygeneration and encryption A8 RAND Ki 128 bit 128 bit Kc 64 bit A8 RAND Ki 128 bit 128 bit SRES RAND encrypted data mobile network (BTS) MS with SIM AC BTS SIM A5 Kc 64 bit A5 MS data data cipher key 11/18/2021 88
  • 80.
    Services Provided toUpper Layers • MM handover procedures provide smooth transition from one radio link to other. • MM sub-layer provides basic services to upper layer CM sub-layer. Subscriber Authentication and Confidentiality management • MM procedures ensure authenticity of a subscriber. • MM procedures ensure data confidentiality at radio interface. 11/18/2021 89
  • 81.
    Subscriber Data atMSC/VLR • MS status data: • Data related to identification and numbering ( IMSI, MSISDN,LMSI and TMSI ). • Data related to MS type. • Hand-over data. • Authentication and Ciphering Data. • Data related to supplementary services. 11/18/2021 90
  • 82.
    MM Procedures • TMSIReallocation Procedure. • IMSI Detach Procedure. • Ciphering Procedure. • Abort Procedure. MM Common Procedures : • Authentication Procedure. • Identification Procedure. MM Specific Procedures : • Location Updating Procedure. • IMSI Attach Procedure. 11/18/2021 91
  • 83.
    • During thelifetime of a MM specific procedure if a MM connection establishment is requested by a CM entity, the request will either be rejected or delayed until the running of MM specific procedure is terminated. • Any MM common procedure Procedure ( except IMSI detach) may be initiated during MM specific procedure. • A MM specific procedure can only be started if no other MM specific procedure is running. • The MS side should wait for release of RR connection used for a MM specific procedure before a new MM specific procedure or MM connection establishment is started. MM Procedures 11/18/2021 92
  • 84.
    • Location areaconsist of one or more than one cell which may be served by one or more BSC s. • All the cells in a Location area are served by single VLR. 2. Location Area Identity (LAI ) - • Each location area in a GSM PLMN is identified by a Location Area Identity ( LAI ). Location Related Identities 11/18/2021 93
  • 85.
    HLR SS 7 BSC MSC 2 VLR1 VLR 2 BSC BSC BSC LA 1 LA 2 LA 3 BTS BTS BTS BTS BTS BTS Location Area MSC 1 11/18/2021 94
  • 86.
  • 87.
  • 88.
    TAX CA TAX ND GMSC MSC GMSC MSC/VLR ND Mobile movesto CA and Powers on MS CA ND HLR HLR ND MS 9810098111 CA ND ( Update Location/ Authentication ) De register Mobile to Old VLR ACK from old MSC/VLR VLR LOCATION UPDATION VLR VPLMN HPLMN Location Update ( TMSI, LAI ) LU Accept ( New TMSI) Update Location Update Location LU Accept (Subs data) LU Accept Update Location LU Accept LU Accept New VLR records subscriber data. • Listens BCCH/FCCH 11/18/2021 97
  • 89.
    LOCATION UPDATE SCENARIO- I MS BSS Old MSC/ VLR HLR /AUC New MSC/ VLR 1 2 Channel Request RACH AGCH SDCCH Assignment Location Update Request ( TMSI , LAI 0 ) SDCCH 3 Request IMSI Send IMSI 4 Request For Service ( TMSI ) 11/18/2021 98
  • 90.
    MS BSS Old MSC/ VLR HLR/ AUC New MSC/ VLR 5 6 Get AuthenticationParameters Authentication Response ( SRES ) SDCCH 7 ( IMSI ) ( RAND,Kc,SRES ) Authentication Parameters SDCCH Authenticate MS ( RAND ) Cipher Radio Channel ( Kc ) Cipher Up Link Channel SDCCH Authentication and Ciphering LOCATION UPDATE SCENARIO - II 11/18/2021 99
  • 91.
    8 9 BSS Ciphers Downlink Channel . SDCCH Ciphering Complete MS BSS Old MSC/ VLR HLR/ AUC New MSC/ VLR LOCATION UPDATE SCENARIO - III Authentication and Ciphering Up Link Ciphered 11/18/2021 100
  • 92.
    LOCATION UPDATE SCENARIO- IV 10 Update Location Update HLR/VLR & TMSI Reallocation De Register Mobile Mobile De-registered 11 MS BSS Old MSC/ VLR HLR/ AUC New MSC/ VLR Location Updated Location Updated Accept TMSI SDCCH 12 13 11/18/2021 101
  • 93.
    SDCCH Location Updated Complete ClearSignaling Connection Clear Complete Release Radio Signaling Channel SDCCH 14 16 15 MS BSS Old MSC/ VLR HLR/ AUC New MSC/ VLR LOCATION UPDATE SCENARIO - V Update HLR/VLR & TMSI Reallocation 11/18/2021 102
  • 94.
    Connection Management enablesdifferent CM sub-layer entities to communicate with their pier entity using different MM connections. Connection Management What is Connection Management ? Different CM sub-layer entities use different MM connections. Different MM connections are identified by Protocol Discriminator PD and, additionally by Transaction Identifier TI. 11/18/2021 103
  • 95.
    MS BTS MSC BSC RIL3- CM LAPD m Layer 1 RIL3 - MM RIL3 - RR Layer 1 LAPD m LAPD Um A bis A link BCDEFG MTP SCCP BSSMAP DTAP MM TCAP DTAP CM U P SCCP M A P Layer 1 Layer 1 GSM Signaling Protocols Overview LAPD MTP I S SCCP BSSMAP BTSM RIL 3- RR BTSM RR 11/18/2021 104
  • 96.
    MS RIL3 - CM LAPDm Layer 1 RIL3 - RR CC SMS SS RIL3 - MM CC = Call Connection SMS = Short Message Service SS = Supplementary Services • There are different entities of CM sub- layer. • For each entity different MM connection will be established over same RR connection. Connection Management 11/18/2021 105
  • 97.
    • Several MMconnections may be active at same time. • All simultaneous MM connections from a given MS use the same RR connection. • An MM connection requires an RR connection. • Mobility Management ( MM) sub-layer provides connection management services to different entities of upper Connection Management ( CM ) sub-layer. • MM connection is established and released on request from a CM entity. Connection Management 11/18/2021 106
  • 98.
    Phases Of ConnectionManagement • MM connection establishment initiated by MS. MM Connection Establishment - • MM connection establishment initiated by n/w. MM Connection Information Transfer Phase - • Sending CM messages. • Receiving CM messages. MM Connection Release - • Release associated RR connection. 11/18/2021 107
  • 99.
    TIME MS N/W CM ServiceRequest CM Service Reject CM CONNECTION ESTABLISHMENT INITIATED BY MS CM Service Accept 1. IMSI unknown in VLR 2. Illegal ME 3. Network Failure 4. Congestion 5. Service Option not supported. 6. Requested service option not subscribed. 7. Service option temporarily out of order. CM Service Reject Causes : 11/18/2021 108
  • 100.
    MS N/W CM MM RR MM CM RR CC SMSSS CC SMS SS CM connection establishment initiated by the Network ( In case no RR connection Exists ) CM Service Reject CM Service Reject 11/18/2021 109
  • 101.
    Zone Codes • Zonecodes provide mechanism for LAC based subscription. • A set of LACs form a Zone Code. • Subscribers can be given access to a set of Zone codes. • If a subscriber updates location in a Zone Code other than his subscribed ones, it is equivalent to sending IMSI Detach. • For the above event MM will mark Regional Barring flag for the subscriber. Example: • In a case where MSC covers several cities Zone Codes may be used to restrict the subscribers of one city from using n/w services in other cities.( Regional Service ) 11/18/2021 110
  • 102.
    Mobile To LandCall Set-up Scenario Phases of Mobile To Land Call • SETUP PHASE ( Mobile Originated Call- MO Call ) • RINGING PHASE • CONVERSATION PHASE • RELEASE PHASE 11/18/2021 111
  • 103.
    - REQUEST FORSERVICE ( CHANNEL ) BY MS - CM SERVICE REQUEST - AUTHENTICATION - CIPHERING - SETUP MESSAGE - EQUIPMENT VALIDATION ( EIR CHECK ) - VALIDATION AT VLR - ASSIGNMENT Mobile To Land Call Set-up Scenario • SETUP PHASE 11/18/2021 112
  • 104.
    MS MSC/ VLR BSS 1 2 3 Channel Request Request ForService MOBILE TO LAND CALL - I RACH SDCCH Assignment AGCH CM Service Accept SDCCH 4 CM Service Request 11/18/2021 113
  • 105.
    Mobile To LandCall Set-up Scenario • CM SERVICE REQUEST - The Call Control (CC) entity of MS initiates the establishment of CC connection by requesting MM sub-layer of the mobile to establish MM sub-layer connection. - Upon establishment of MM connection CM SERVICE ACCEPT message is received from n/w. • SETUP MESSAGE - CC entity sends a setup message to its peer entity. 11/18/2021 114
  • 106.
    MS MSC/ VLR BSS 5 6 Call Setup Request 7 SDCCH SDCCH CallSetup MOBILE TO LAND CALL - II Assign Trunk and radio Assign TCH Radio Assignment Complete Call Proceeding SDCCH SDCCH Trunk and Radio Assignment Complete 11/18/2021 115
  • 107.
    Mobile To LandCall Set-up Scenario MSC/VLR Call Setup message Is the requested basic service provisioned for the subscriber ? Yes No Release Complete message to MS Preliminary Digit Analysis Is the number of digits less than the minimum expected? Yes Release Complete message to MS No 1. Check of ODB( BAOC/BOIC/ BOIC Ex HC ) 2. Subscriber call barring checks ( BAOC/BOIC et ASSIGNM ENT 11/18/2021 116
  • 108.
    Mobile To LandCall Set-up Scenario • ASSIGNMENT - A BSSMAP message ‘Assignment Command ’ is sent by MSC to BSS. - The message contains a free CIC on A-Interface for terrestrial channel allocated by MSC. - A free TCH is allocated by the BSS and MS is informed to attach to this TCH. - On receiving a response from BSS MSC switches the speech path towards the calling MS. Note : Mobile has not connected user connection as yet. 11/18/2021 117
  • 109.
    MS MSC/ VLR BSS 8 9 10 11 Call Setup MOBILE TOLAND CALL - III GMSC PSTN HLR Network Setup ( Dialed Digits ) FACCH Network Alerting Connect Connect Acknowledge FACCH Alerting Connect FACCH Start Billing 11/18/2021 118
  • 110.
    MS MSC/ VLR BSS 12 13 14 15 Call Release MOBILE TOLAND CALL - IV GMSC PSTN HLR Disconnect FACCH Network Release Release Complete Release Complete FACCH Release FACCH Clear Command Channel Release 11/18/2021 119
  • 111.
    Land To MobileCall Set-up Scenario Phases of Land To Mobile Call • Routing Analysis • Paging • Authentication • Call-Setup • Ciphering • Call Release ( Mobile Terminating - MT Call ) 11/18/2021 120
  • 112.
    Architecture For MobileTerminated Call GMSC- B BSS-B MS VLR-B MSC-B VISITING PLMN A- Interface Air Interface HLR-B IAM ( ISUP ) 11/18/2021 121
  • 113.
    LAND TO MOBILECALL - I MSC/VLR GMSC PSTN HLR 1 2 Incoming Call 3 4 ( MSISDN ) Get Route ( MSISDN ) Get Route ( IMSI ) Routing Information ( MSRN ) Routing Information ( MSRN ) ( MSRN ) Incoming Call 5 Routing Analysis 11/18/2021 122
  • 114.
    MS MSC BSS 6 7 8 Perform Page (TMSI) Page PCH ChannelRequest ( RACH ) SDCCH Paging Response ( TMSI, LAI ) 9 Access Granted ( AGCH ) Page Response Paging LAND TO MOBILE CALL - II 11/18/2021 123
  • 115.
    MS MSC/ VLR BSS 13 14 15 Connect ( off-hook) FACCH Call Setup LAND TO MOBILE CALL - IV GMSC PSTN HLR FACCH Network Alerting Mobile Alerting Connect Connect Acknowledge Start Billing 11/18/2021 124
  • 116.
    MS MSC/ VLR BSS 16 17 18 Disconnect Release 19 FACCH FACCH Call Release LAND TOMOBILE CALL - V GMSC PSTN HLR Network Release FACCH Release Complete Release Complete Clear Command Clear Channel Clear Complete FACCH Stop Billing 11/18/2021 125
  • 117.
    Mobile To MobileCall Set-up Scenario Phases of Mobile To Mobile Call • Request for service. • Authentication • Call-Setup • Ciphering • Call Release • Routing Analysis • Paging • Authentication • Ciphering • Call-Setup Mobile Originating Mobile Terminating • Call-Release 11/18/2021 126
  • 118.
    TAX ND GMSC MSC/VLR 1. ND PSTNSubscriber Dials ND Mobile Subscriber in ND. ND LE TANDEM HLR ND MS 9810098100 ND SRI PRN to MSC/VLR ND ACK from MSC/VLR ND (MSRN) MSRN MSISDN MSISDN MSISDN Page(TMSI) 11/18/2021 127
  • 119.
    TAX ND TAX CA GMSC MSC/VLR GMSC MSC/VLR 2. ND PSTNSubscriber Dials CA Mobile Subscriber in CA. ND CA LE HLR HLR CA MS 9881098300 ND CA SRI PRN to MSC/VLR CA ACK from MSC/VLR CA (MSRN) MSRN MSISDN Page(TMSI) TANDEM MSISDN MSISDN MSISDN 11/18/2021 128
  • 120.
    TAX CA TAX ND GMSC MSC/VLR GMSC MSC/VLR 3. ND PSTNSubscriber Dials ND Mobile Subscriber in CA. CA ND LE TANDEM HLR HLR ND MS 9810098200 CA ND SRI PRN to MSC/VLR CA ACK from MSC/VLR CA (MSRN) MSRN MSRN MSRN MSRN MSISDN MSISDN MSISDN Page(TMSI) 11/18/2021 129
  • 121.
    TAX CA TAX ND GMSC MSC/VLR GMSC MSC/VLR 4. CA PSTNSubscriber Dials ND Mobile Subscriber in CA. CA ND LE HLR HLR ND MS 9810098400 CA ND SRI PRN to MSC/VLR CA ACK from MSC/VLR CA (MSRN) MSRN MSISDN Page(TMSI) TANDEM MSISDN MSISDN MSISDN MSRN MSRN MSRN 11/18/2021 130
  • 122.
    TAX CA TAX ND GMSC MSC/VLR GMSC MSC/VLR 4.A CA PSTNSubscriber Dials ND Mobile Subscriber in CA CA ND LE HLR HLR ND MS 9810098410 CA ND PRN to MSC/VLR CA ACK from MSC/VLR CA (MSRN) MSRN Page(TMSI) TANDEM MSISDN MSISDN Roaming agreement with Optimal Routing SRI 11/18/2021 131
  • 123.