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行動通訊簡訊及多媒體訊息

行動通訊簡訊及多媒體訊息. 溫志宏 博士 吳承崧 博士 蘇暉凱 博士 國立中正大學電信研究中心. Outlines. 課程內容： GSM Introduction (3 hrs) GPRS Introduction (3 hrs) SMS & EMS (3 hrs) (Ref: 3GPP TS 23.040_MMS.pdf) MMS (9 hrs) (Ref: 3GPP TS 23.140_MMSFD.pdf) MMS Application (Java 2 Micro Edition) Programming (9 hrs) 實習：

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行動通訊簡訊及多媒體訊息

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  1. 行動通訊簡訊及多媒體訊息 溫志宏 博士吳承崧 博士蘇暉凱 博士國立中正大學電信研究中心

  2. Outlines • 課程內容： • GSM Introduction (3 hrs) • GPRS Introduction (3 hrs) • SMS & EMS (3 hrs) (Ref: 3GPP TS 23.040_MMS.pdf) • MMS (9 hrs) (Ref: 3GPP TS 23.140_MMSFD.pdf) • MMS Application (Java 2 Micro Edition) Programming (9 hrs) • 實習： • MMS Application (Java 2 Micro Edition) Programming (9 hrs)

  3. GPRS networkLogical network elements BSS External packet networks GPRS Core network Value added services (WAP)

  4. NMS Billing Center BSC BTS SGSN CG FW GGSN Corporate Server BG GGSN Router Internet GPRS Backbone InterPLMN Network LAN FW LIG Operator Services GGSN Intranet DNS LAN GPRS networkLogical network elements SGSN = Serving GPRS Support Node GGSN = Gateway GPRS Support Node NMS = Network Management System BG = Border Gateway CG = Charging Gateway FW = Firewall LIG = Lawful Interception Gateway

  5. GPRS Backbone IP Network Internet SS7 SGSN & GGSN functionalities HLR MSC/ VLR BSC BTS GGSN • GTP tunneling to SGSN • Interfaces to external IP networks • Charging & statistics • NMS interfaces SGSN SGSN • Authentication • GTP tunneling to GGSN • Ciphering & compression • Mobility management • Interaction with HLR, MSC/VLR • Charging & statistics • NMS interfaces GGSN FW

  6. Serving GPRS Support Node (SGSN) Functions………. • Mobility management • Authentication • Ciphering & compression • Protocol conversion • GTP tunneling to GGSN • Interaction with HLR, MSC/VLR • Charging & statistics • NMS interfaces

  7. Gateway GPRS Support Node (GGSN) Functions………. • Essentially a router • Interfaces to external IP networks • GTP tunneling to SGSN • Charging & statistics • NMS interfaces

  8. Border Gateway (BG) Functions………. • Essentially a router similar to GGSN • Provides a secure 'tunnel' for • transferring data on the inter-PLMN • backbone between different • operators • Supports protocols like BGP-4

  9. Domain Name Server (DNS) Functions………. • Standard IP device • Converts domain names into IP addresses • Based on a hierarchical & distributed • model

  10. Firewall (FW) Functions………. • Standard IP device • Protects against unauthorized access (hackers)

  11. Charging Gateway (CG) Functions………. • Collects charging data from SGSN & GGSN • Processes the charging data & forwards it • to the Billing System

  12. Lawful Interception Gateway (LIG) Functions………. • Intercepts user data, MM information, • subscriber information etc. • Forwards it to Law Enforcement Agency (LEA)

  13. Signalling and data Signalling Gd Gr Gf Gs Gc Ga Ga Gi Gb Gn Air (Um) Gn Gp GPRS Interfaces SMS- GMSC MSC/ VLR HLR EIR CG SGSN BSC External packet network GGSN Abis Inter-PLMN GPRS Backbone BG

  14. HLR MSC/ VLR BSC BTS SGSN Server GGSN Application Layer Transport layer APP GPRS Core Network USER PAYLOAD Tunnelled payload TCP/UDP Network layer IP Public Data Network Layers 1 & 2 GTP SS7 Internet UDP GPRS tunnel L2 IP L1 Transport layer L2 L1 GGSN functionalities GPRS Backbone Layers 1 & 2 Network layer

  15. GPRS architecture key points (1) The Gateway GPRS Support Node (GGSN): • acts as the interface between the GPRS network and external networks • collects charging data and traffic statistics • can allocate IP-addresses for users • routes packets coming from external networks towards the correct SGSN and vice versa Serving GPRS Support Node (SGSN): • converts protocols used in the IP backbone to protocols used in the BSS and the MS • takes care of authentication and mobility management • routes data to the relevant GGSN when connection to an external network is required • collects charging data and traffic statistics.

  16. Mobility Management States • The tracking of the location of an MS depends on the mobilitymanagement state. GPRS has three mobility management states. • IDLE • READY • STANDBY • Each state describes a certain level of functionality & information allocated. • The change between the states happens upon activity or when a timer expires.

  17. HLR IMSI 244... IMSI VLR VLR-1 LAI SGSN ? IMSI ? RA ? BSC SGSN-1 Cell ? RA-1 LA-1 Mobility Management States • Idle State • Subscriber is not attached to the GPRS network • No valid MM context of the subscriber e.g. MS switched off

  18. Mobility Management States • Ready State • After successful GPRS Attach • Location tracked to the cell level • Activation & deactivation of PDP context possible • Sending and receiving of SMS is possible • MS can receive paging for circuit switched services (optional) • Data can not be transferred until a PDP context is activated. After the PDP context activation, the SGSN can send data to the MS without paging at any time. • Ready timer expiry moves MS to the STANDBY state

  19. Mobility Management States • Standby State • Subscriber is attached to the MM context • Location tracked at RA level • If SGSN receives a packet for the MS, it pages in the RA. A PDP context must be active. • Activation of PDP context possible. If the MS sends data, it moves to the ready state. • MS can receive paging for CS services (optional) • The MS Reachable Timer starts ticking when the MS enters the Standby state & the MS is detached (IDLE state) upon its expiry (Implicit detach).

  20. HLR SGSN-1 2a 2b 1 1 BSC RA-1 LA-1 Mobility Management - GPRS Attach (1) (1) MS requests GPRS attach • (2a) The MS is not known in the PLMN so the SGSN requests • subscriber identity (first time) (2b) The MS sends its IMSI.

  21. HLR 3b 3a SGSN-1 3c 3d BSC RA-1 LA-1 GPRS Attach (2) -Authentication (3a) SGSN requests triplets from HLR (3b) The AC generates the triplets and hands them to the SGSN (3c) The SGSN sends an Authentication Request to the MS (3d) MS sends back the Authentication Response The SGSN performs the authentication

  22. EIR 4d 4c SGSN-1 4a 4b BSC RA-1 LA-1 GPRS Attach (3) - IMEI check (4a) SGSN asks for the MS IMEI (4b) MS sends the IMEI (4c) SGSN sends a Check IMEI message to the EIR (4d) EIR replies with a Check IMEI ack that will include the list type

  23. HLR 5d 5b 5a SGSN-1 5c 6a 6b BSC RA-1 LA-1 Mobility Management - GPRS Attach (4) (5a) SGSN sends an Update location message to the HLR with the IMSI (5b) The HLR responds by giving subscriber data to the SGSN (5c) The SGSN acknowledges that it has received the subscriber data ok (5d) The HLR ends the transaction with an Update Location acknowledge (6a) The SGSN accepts the GPRS attach and sends the MS a new P-TMSI (6b) The MS acknowledges that it has received the new P-TMSI

  24. Process of assigning an IP address for becoming a part of the IP network Session Management - PDP Context Activation • One or more addresses can be assigned to an IMSI (MS). • Contains mapping and routing information for transferring PDUs between MS and GGSN. • Information includes: IP address, Access Point Name, QoS, Radio Priority, NSAPI, and LLC SAPI. • Static addresses: address allocated by operator to an MS permanently and this address is stored in the HLR. • Dynamic addresses: GGSN dynamically allocates and releases addresses as PDP contexts are activated and deactivated.

  25. 3b 3a 4 2 1 PDP context activationOverview GGSN SGSN 1. Activate PDP context request BSC 2. Auth. /IMEI check (optional) 3a. Create PDP context request RA-1 LA-1 3b. Create PDP context response 4. Activate PDP context accept

  26. 1. MS sends "Activate PDP Context Request" to SGSN Access Point Name PDP Type (IP) PDP Address (empty = dynamic) QoS & other options 2 1 GPRS Core Network Internet Intranet SS7 PDP Context Activation - 1 HLR BSC BTS APN= "Intranet.Ltd.com" SGSN DNS Access Point GGSN • 2. SGSN checks Subscription data • Access Point Name • Dynamic / static IP address

  27. 3. SGSN gets the GGSN IP address from DNS APN maps to the GGSN IP address 3 GPRS Core Network 4 Intranet Internet PDP Context Activation - 2: Finding the GGSN • 4. SGSN sends "Create PDP Context Request" • to GGSN • PDP Type (e.g. IP) • PDP Address (if empty=> dynamic address) • Access Point Name • QoS & other options BSC BTS SGSN DNS Access Point GGSN

  28. GPRS Core Network Intranet Internet PDP Context Activation - 3Access Point Selection • Access Point Name refers to the external network the subscriber wants to use • Physical/logical interface in GGSN • Access Point configuration in GGSN defines where to connect the user BSC BTS SGSN DNS APN= "Intranet.Ltd.com" GGSN

  29. PDP Context Deactivation • The MS or the network can deactivate a PDP context. • Every address can be deactivated separately, but performing a • GPRS Detach will automatically remove all the PDP contexts.

  30. 2) 4a) 3a) 1) SMS 3b) 4b) SMS data transfer a) MSC address b) SGSN address HLR MSC SMSC G-MSC 2). Send routing info. for Short Message (GMSC-HLR) Send routing info. for Short Message result (HLR-GMSC) SGSN

  31. User authenticated OK (non-transparent case) User dynamic IP address allocated by RADIUS server, or DHCP server, or GGSN internal pool 5. GGSN sends "Create PDP Context Response" back to SGSN 6 GPRS Core Network 5 Intranet Internet PDP Context Activation - 4Context Activated BSC BTS • 6. SGSN sends "Activate PDP Context Accept" • to the MS • SGSN now ready to route user traffic between • MS and GGSN SGSN GGSN

  32. GPRS Attach v/s PDP Context Activation • GPRS Attach • MOBILITY MANAGEMENT PROCEDURE • Establishes a logical link between the MS and the SGSN. • Makes the MS available for SMS over GPRS, paging via SGSN, and notification of incoming GPRS data. • Transmission of user data is not possible • PDP Context Activation • IP address is assigned to the MS. • Makes the MS known in the corresponding GGSN. • SESSION MANAGEMENT PROCEDURE

  33. HOME Operator GPRS Inter-PLMN GPRS Backbone Context Activation for a Roaming User (0) DNS Visited Operator .GPRS DNS SGSN BG BG DNS HOME GGSN

  34. 3 2 HOME Operator GPRS Singapore GPRS Backbone Inter-PLMN GPRS Backbone Embassy Intranet Context Activation for a Roaming User (1) Visited Operator, Singapore DNS .GPRS DNS SGSN BG 1 BG DNS HOME GGSN GSM OPERATOR, Finland

  35. 5 4 Singapore GPRS Backbone HOME Operator GPRS Embassy Intranet Inter-PLMN GPRS Backbone Context Activation for a Roaming User (2) Visited Operator, Singapore DNS .GPRS DNS SGSN BG BG DNS HOME GGSN GSMOPERATOR, Finland

  36. 7 6 Singapore GPRS Backbone HOME Operator GPRS Embassy Intranet Inter-PLMN GPRS Backbone Context Activation for a Roaming User (3) Visited Operator, Singapore DNS .GPRS DNS SGSN BG BG DNS HOME GGSN GSMOPERATOR, Finland

  37. 8 9 Singapore GPRS Backbone HOME Operator GPRS Embassy Intranet Inter-PLMN GPRS Backbone Context Activation for a Roaming User (4) Visited Operator, Singapore DNS .GPRS DNS SGSN BG BG DNS HOME GGSN GSMOPERATOR, Finland

  38. Singapore GPRS Backbone HOME Operator GPRS Embassy Intranet Inter-PLMN Backbone The Data Flow in a Roaming Case Visited Operator, Singapore SGSN BG BG GGSN GSMOPERATOR, Finland

  39. Singapore GPRS Backbone HOME Operator GPRS Internet Embassy Intranet Inter-PLMN Backbone Connection options SGSN GGSN Gi Gp BG GGSN Gi Gp BG

  40. HOME Operator GPRS Inter-PLMN GPRS Backbone Roaming, Dynamic IP-address from Home Network, APN Always the Same Visited Operator GGSN Visited-PLMN GPRS Backbone SGSN BG BG Internet/ Intranet IP address changes GGSN Access Point

  41. HOME Operator GPRS Inter-PLMN GPRS Backbone Roaming, Dynamic IP-address from a Visited Network Visited Operator Internet GGSN Visited-PLMN GPRS Backbone SGSN Access Point BG BG x.x.x.x GGSN

  42. Charging of GPRS services Billing System GTP' Charging gateway • Nokia GPRS Charging Gateway: • * receives CDRs generated by • SGSN and GGSN • consolidates and merges • CDRs to a suitable format for • BS SGSN Operator IP backbone GTP' Border Gateway GGSN Inter operator IP network Internet

  43. CG SGSN Operator IP backbone G-CDRs GGSN Internet GGSN Charging Functions • GGSN CDR (PDP context data) : G-CDR • Start collection: • - PDP context activation • Stop collection: • - PDP context deactivation • Collected information e.g. • - Traffic volumes uplink/downlink • - QoS negotiated • - Duration • - SGSN & GGSN address • - Access Point Name

  44. S-CDRs M-CDRs SMS-CDRs CG SGSN Operator IP backbone GGSN Internet SGSN Charging Functions • SGSN CDR (PDP context data) : S-CDR • Start collection: • - PDP context activation • Stop collection: • - PDP context deactivation • Collected information e.g. • - Traffic volumes uplink/downlink • - QoS requested/negotiated • - Duration • - SGSN & GGSN address • - Access Point Name • Mobility Management CDR : M-CDR • Start collection: • - GPRS activation / Incoming SGSN RA update • Stop collection: • - GPRS deactivation / Outgoing SGSN RA update • Collected information • - Location changes

  45. CG Functionality Main tasks of CG are: • CDR collection from GSNs (CG receives the CDRs with GTP') • intermediate storage for CDRs • CDR validation • CDR consolidation • CDR formatting • adaptation to different CCB System interfaces • to reduce the CDR processing load of the CCB System

  46. Rating based on: Dialled digits Access Point Name IP Address Allocation Usage based on: Call duration SMS transaction Data Volume Context duration SMS transaction Intermediate records: Not needed Necessary GPRS Charging introduces new billing concepts GSM traffic GPRS traffic

  47. Visitor CLEARING CCB CCB CG CG SGSN SGSN Operator A IP backbone HOME NETWORK VISITING NETWORK Border Gateway Operator B IP backbone GGSN APN GGSN APN Internet Roaming case 1

  48. Visitor CLEARING CCB CCB CG CG SGSN SGSN Operator A IP backbone HOME NETWORK VISITING NETWORK Border Gateway Operator B IP backbone GGSN APN GGSN APN Internet Roaming case 2

  49. APN (Access Point Name) • APN=Network ID+Operator ID • Example: • internet201.kgt.com,tw.mnc088.mcc466.gprs • Selection Mode • *SentByMS: MS-provided APN, subscription not verified. • *Subscribed: MS or Network-provided APN, subscription verified. • *ChosenBySGSN: Network-provided APN, subscription not verified. • The SGSN select the APN to be used to derive the GGSN address • Wild Card APN: The user can select whichever APN he wants

  50. Selection Algorithm Y MS Request ? N Y N Wild Card ? Wild Card ? N Y N Single PDP in HLR? SentByMS Subscribed ChosenBySGSN Y PDP Context Activate Reject Subscribed

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