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USSD Standardization in cdma2000 Networks

USSD Standardization in cdma2000 Networks. Ravindra Patwardhan, Vikram Gupta, Roozbeh Atarius 10/10/10. Background in 3GPP. USSD is abbreviation for Unstructured Supplementary Service Data. Specifications in 3GPP are TS22.090 (stage 1), TS23.090 (stage 2), and TS24.090 (Stage3)

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USSD Standardization in cdma2000 Networks

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  1. USSD Standardization in cdma2000 Networks Ravindra Patwardhan, Vikram Gupta, Roozbeh Atarius 10/10/10

  2. Background in 3GPP • USSD is abbreviation for Unstructured Supplementary Service Data. • Specifications in 3GPP are TS22.090 (stage 1), TS23.090 (stage 2), and TS24.090 (Stage3) • Other related specifications are TS22.030 for MMI for USSD and TS23.038 for the alphabet indicator and data coding scheme. • USSD allows the UE to communicate with the applications in the the network entities e.g. HLR, or prepaid services transparently to the UE and the network entities. • Communication is done by the USSD handler independent of the applications. See the figure on the next slide.

  3. SCOPE in 3GPP Communication between the units is done by the USSD handlers independent of the applications. In this figure, the applications in the HLR is targeted.

  4. Benefits with USSD Handler • The supplementary service can be triggered in any unit e.g. MSC,VLR, or HLR. • UE can get access to USSD supplementary services in any state in which digits can be transmitted, e.g. Idle or on a Traffic Channel • Example: UE is on active Traffic channel and the user trigger the call forwarding supplementary service by: • Program forwarding **21*«destination number»# • Activate *21# • Deactivate #21# • Check Status*#21#

  5. USSD Design for c2k: Standards Support Needed • There are 3 key functionalities that need to be supported on the data path: • USSD Handler: • This is new CN component with interfaces • to MSC/VLR, SMSC, for sending receiving data to/from the c2k network • to USSD application gateway (GSM-SCF) for receiving USSD application data and sending user responses. • to HLR, Network Management, Billing, Provisioning, etc for signaling • Routing of USSD packets: • USSD handler(s) should be able to connect directly to the MSC. • MSC should be able to send the packets directly to the USSD handler. • Mobile should be able to identify incoming USSD packet. • Maintaining OTA connection for the duration of USSD session.

  6. Routing of USSD packets: new SMS Teleservice • Define a new SMS Teleservice type for USSD: • MSC uses new USSD teleservice type to route packets to USSD handler • Mobile uses USSD teleservice type to send data to the USSD application • Pros: • SMS header overhead may be reduced. • SMS message types applicable for USSD can be clearly defined. • Teleservice type is available in the transport layer header. • Roaming support is possible • unless the visiting MSC discards unknown SMS teleservice types • Cons: • Not sure how easy it is to introduce a new Network Teleservice.

  7. USSD session: OTA Connection Maintenance • Traffic Channel maintenance: • Mobile station requests a traffic channel after receiving a USSD message • USSD handler indicates the continuity of USSD session. • Mobile station should send a release order after receiving the last message in a USSD session. • USSD handler will indicate end of session in the USSD message header. • Base station will run a catch all timer to prevent mal-functioning mobile stations from keeping up a connection.

  8. USSD Handler: Data Plane Support • USSD Handler provides interworking function for GSM USSD gateway’s data and control requests. • Data plane • Takes incoming data packets from the USSD gateway and ensures reliable delivery of data to the mobile station. • A header within the SMS is needed to carry USSD session information. • Takes incoming data packets from the MSC and delivers it to the USSD Gateway • This entails unpacking the SMS to construct the appropriate USSD packet for USSD gateway. • USSD handler communicates with USSD Gateway according to the (USSD) - Stage 2 (GSM 03.90 version 7.0.0 Release 1998) standard.

  9. USSD Handler: Control Plane Support • Control Plane Support: USSD spec also includes functional requirements on • GSM SCF - HLR interface (J-Interface) • Any-time Interrogation function • USSD function • MSC-HLR interface (L-interface) • Call Deflection (CD) • Explicit Call Transfer (ECT) • Multi-Party call (MPTY) • Other interfaces such as gsmSSF, gsmSRF may also need to be supported. • Support for billing, provisioning, etc may be needed as well. • Registration and Deregistration support is needed to ensure network initiated USSD is not sent to legacy devices.

  10. Mobile Station Support Needed • AMSS MS software support is needed for • translation / transport of USSD on c2k network. • S&R of USSD data before sending it to network or the application. • ability to open and close traffic channel based on USSD session. • Provisioning support • Destination address for USSD handler may need to be provisioned. • USSD is currently supported on all GSM mobiles. • No new support is needed at the USSD application layer. • GSM USSD application software may be leveraged for c2k.

  11. Summary • USSD service can be implemented in c2k as a new SMS Teleservice. • QCT evaluation and support is needed before proceeding externally. • Validation from Tata’s MSC/CN vendors is needed: • New SMS Teleservice usage for USSD. • Can they implement the USSD handler functionality?

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