呼叫流程及信令

1、位置更新及呼叫流程位置更新操作(一_位置更新仅涉及本 VLR或MS 首次登录, 或相关网络数据丢失后,MS 都使用IMSI 来标识自己 内(一 中(二 切换控制流程_同MSC 内基站间切换 附：消息说明 DTAP 消息 移动管理MM 消息 DTAP 消息 呼叫控制(CC消息 BSSMAP 消息 无连接消息 BSSMAP 消息 面向连接消息 七号信令： GSM 信令分层： BSSAP BSS Application PartBSSMAP BSS Management Application Part DTAP D irect Transfer Application Part MM Mobili

2、ty Managemert CM Connection ManagementCall ControlShort Message ServicesM SCB SC BTSMS CC SMS SS SCCP Signalling Connection Control Part MTP Message Transfer Part RR Radio Resourses BTSM LapDBTS ManagementLink Access Protocol on the D channel LapDm Link Access Protocol on the D channel modified Laye

3、r 1 (Physical Layer The physical layer is responsible for the error free transfer of physical data units. This layer definesthe electrical and mechanical characteristics of the transmission path. Layer 2 (Link Layer The function of the link layer is to transfer frames, error free, between two statio

4、ns using the bittransfer connection created by the physical layer. The tasks of this layer include opening,maintaining, and closing a connection between two stations. In GSM, the data link layer is implemented with the standard LapD (Link Access Protocol on D channel protocol on the BTS-BSC link, an

5、d with a GSM specific LapDm protocol on the BTS-MS (radio interface link. Layer 3 (Network Layer The network layer isolates the higher levels from routing and connection tasks. It is responsible for getting the message to its destination through an arbitrary network topology. In GSM, this layer is h

6、ierarchically divided into three sublayers; CM (Connection Management,MM (Mobility Management, and RR (Radio Resource layers. The Radio Resource layer, RR, produces services for the Mobility Management layer. Thefunctions of this layer include establishing, maintaining, and releasing physical connec

7、tions (i.e. RF traffic and control channels. The main part of this function is located in the BSC, although some of the functions are performed by the BTS. The Mobility Management layer, MM, controls the registration of subscriber equipment in thenetwork and identification of users. This function is

8、 located in the MSC. The Connection Management layer, CM is the highest layer in the GSM implementation of the OSImodel. This is indicated by its location (top of the protocol stack in both MSC and MS. This layer is basically the interface to the user in the GSM system. The connection management lay

9、er is subdivided into three segments; Call Control segment, CC, which is responsible for establishing, maintaining and releasing calls, Suplementary Services segment, SS, and Short Message Service segment, SMS. 呼叫建立过程：V L R M SC B SC C h a n n el R e q u ired B T S 2 4 6 C M S e r v ic e R e q u e s

10、 t C h an n el R eq uest ( R A C H C h a n n e l A c tiv a tio n C h a n n e l A c tiv a tio n A c k . M S 1 R A D IO A C C E SS P A R T 3 5 Im m e d ia te A s s ig m e n t C o m m a n d . Im m e d ia te A s s ig m e n t ( A G C H . C M S e r v ic e R e q u e s t ( S D C C H P rocess A ccess R eq u

11、est 11 13 C R (C M S e r v ic e R e q u e s t 9 8 10 U A (S D C C H 7 E S T A B L IS H M E N T PA R T E s ta b lis h In d ic a tio n 12 A u th e n tic a te C C A u th e n tic a tio n R e q u e s t 14 D T 1 A u th e n tic a tio n R e s p o n s e A u th e n tic a tio n R e q u e s t ( S D C C H A u th

12、 e n tic a tio n R e s p o n s e ( S D C C H 16 15 A u th e n tic a tio n R e s p o n s e 17 19 D T 1 18 S et C ip h erin g M o d e C ip h e r in g M o d e C o m m a n d 20 C ip h erin g M o d e C om m a n d E n c r y p tio n C o m m a n d 21 C ip h erin g M o d e C o m m a n d ( S D C C H D T 1 C i

13、p h e r in g M o d e C 23 o m p le te C ip h e r in g M o d e C o m p le te ( S D C C H 22 24 25 A c c e s s R e q u e s t A c c e p te d F orw ard N ew T M S I 2 T6M S I R e a lloc a tion C om m a n d 27 T M SI A ck. T M S I R e a llo c a tio n C o m m a n d ( S D C C H T M S I R e a llo c a tio n

14、C o m p le te ( S D C C H 30 33 35 3 7D T M S I R e a llo c a tio n C o m p le te 29 28 31 C A A P IP H E R IN G , U T H E N T IC A T IO N D C A L L SE T U P A R T D T 1 S e tu p 32 S e tu p ( S D C C H S e n d In fo fo r O .G . C a ll C o m p lete C a ll 34 D T 1 T 1 C a ll P r o c e e d in g 36 A

15、ssig n m e n t R e q u e st C a ll P ro ce ed in g ( S D C C H P h y s ic a l C o n te x t R e q u e s t 38 40 42 P h y s ic a l C o n te x t C o n fir m e d C h a n n e l A c tiv a tio n C h a n n e l A c tiv a tio n A c k . 39 41 SA B M ( FA C C H A s s ig n m e n t C o m m a n d ( S D C C H E s t

16、a b lis h In d ic a tio n 44 45 43 46 T C H S E IZ E D U A ( FA C C H D T 1 A ssig n m en t C o m p lete 47 48 A ssig n m en t C o m p lete ( F A C C H C h a n n e l R e le a s e C h a n n el R ele a se A c k . 50 52 D T 1 D T 1 A le r tin g C on n ect 49 51 53 A le r tin g ( F A C C H C on n ect (

17、F A C C H C o n n e c t A c k .( F A C C H D T 1 C on n ect A ck. 55 54 56 58 C O N V E R S A T IO N P A R T M e a s u r e m e n t R e p o r t/R e s u lt 57 M easu rem en t R ep ort ( S A C C H D is c o n n e c t ( F A C C H D T 1 ( D is c o n n e c t ( R e le a s e 59 61 R ele a se ( F A C C H R e

18、le a s e C o m p le te ( F A C C H 60 D T 1 D T 1 ( R e le a s e C o m p le te ( C lea r C om m and 63 65 66 C h a n n el R elea se ( F A C C H D e a c tiv a te S A C C H D IS C ( F A C C H R e le a s e In d ic a tio n 62 R E L E A SE B Y M S 64 D T 1 67 69 71 68 U A ( FA C C H 70 D T 1 ( C lea r C

19、o m p lete ( S C C P R elea se d ( S C C P R e le a s e d A c k . R F C h a n n e l R e le a s e R F C h a n n el R elea se A c k . 72 74 73 R LSD R L C 呼叫建立过程说明： 呼叫建立过程说明： 1. CHANNEL_REQUEST The MS requests a channel by sending a random access burst on a RACH channel via one BTS. Channel request -m

20、essage contains the establishment cause. This can be 'Answer for paging', 'emergency call', 'other services (Mobile Originated Call, Short Message Service' or 'Other', like location update. In addition to, this message contains Random Reference. This is 5 bits randoml

21、y selected by MS. The usage of random reference is: when two MSs are accessing to the network exactly the same time, the network can separate these Mobile Stations by using this random reference. 2. IMMEDIATE_ASSIGNMENT The BSS informs the MS on AGCH channel about the SDCCH channel to be used. In pr

22、actice, this message is an order from the network to the MS to move to the SDCCH -channel defined before. Page mode, SDCCH channel description, associated SACCH and hopping frequency are included as parameters. In addition, request reference (same as establishment cause, initial timing advance and f

23、requency allocation if frequency hopping applies are also included. 3. AUTHENTICATION_RESPONSE The MS responds to the Authentication Request with the Signed Response SRES. The Authentication Response is sent to the BSC via the BTS. In the MS Authentication procedure, two algorithms, A3 and A8 are us

24、ed. In the SIM -card (In MS, both of these algorithms and 32 -digit key are stored and the very same information can be found in Authentication Centre (AuC also. When MS Authentication is requested by the network, AuC/VLR sends 32 -digit RANDom Number to the MS. MS calculates then Signed Response (S

25、RES and returns that back to the VLR. VLR makes a comparison if received SRES is same than it has received inside of the Authentication triplet from the AuC before. If these two SRESs are the same, authentication went OK and MS can continue the call setup. Should you notice, the first 8 digits of th

26、e KI are used for Authentication and SRES calculation, the rest 24 are reserved for Ciphering Key calculation. 4. SETUP After authentication, Identification and Ciphering, the MS is in the SDCCH channel and ready to start real call setup signaling. The MS sends a Setup message to the BSC to be forwa

27、rded to the MSC. 5. ASSIGNMENT_COMMAND The BTS delivers received information further on towards the MS. Contents: channel description, power levels, cell channel description, channel mode (Full / Half and mobile allocation. 位置更新 VLR M SC BSC Channel Required BTS 2 4 Channel Activation Channel Activa

28、tion Ack. MS Channel Request ( RACH 1 RADIO ACCESS PART 3 6 Immediate Assigment ( AGCH . 5 Immediate Assigment Command. Process Access Request CR Location Update Req. 9 Request Request Location Update Request 8 Request Request Establish Indication Location Update Request 7 SABM (SDCCH 10 UA ( SDCCH LOCATION UPDATE REQ UEST Identity Request 11 CC Identi