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VOCODER PLACEMENT ISSUES

VOCODER PLACEMENT ISSUES. Ericsson CDMA Systems Roger Gustavsson Qiang Gao Ake Jansson. IS-95/2000 Signaling Msgs. Vocoder. IP Network. PTSN. PTSN. Proposed Architecture Evolution. RAN. A1. MS. A2. MSC. RAN. MSC Server. A1*. IS-95/2000 Signaling Msgs. A x. MS. Vocoder. MGW.

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VOCODER PLACEMENT ISSUES

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  1. VOCODER PLACEMENT ISSUES Ericsson CDMA Systems Roger Gustavsson Qiang Gao Ake Jansson

  2. IS-95/2000 Signaling Msgs Vocoder IP Network PTSN PTSN Proposed Architecture Evolution RAN A1 MS A2 MSC RAN MSC Server A1* IS-95/2000 Signaling Msgs Ax MS Vocoder MGW IP Transport for compressed voice CDMA SYSTEMS Vocoder Placement Issues

  3. Vocoder Placement Requirements • For support of Multimedia mobiles the vocoders shall be located in the Media Gateway (MGW) • For support of Legacy mobiles the vocoders can be located in the RAN or MGW • IP Transport for compressed voice • evolution to All-IP Architecture • Smooth migration towards an unified IP transport platform for both voice and data • Open Issues • header compression, e.g., RTP/UDP/IP header compression • Multiplexing at Link Layer e.g. PPP Mux • End to End Multiplexing at Application Layer

  4. Impact of Vocoder Placement in MGW • New Protocol Stack (A2*) for compressed voice: IOS Application RTP/UDP/IP Link Layer Physical Layer • QoS Requirements • current IP transport (IOS v4.1) supports best effort delivery. • need to provide guaranteed service • Evolved signaling interface (A1*) to MSC server (to allow for resource allocation and management) • New signaling interface between MSC server and MGW

  5. IS-95/2000 Signaling Issues related to Vocoder Placement • Blank-and-Burst and V2 mode not affected • Dim-and-burst • requires the vocoder to lower the coding rate upon request • Vocoder Rate Control • In-band • use the 8 encoder tail bits • Same as the voice transport latency • Out-of-band • Specify explicit signaling between BSC/MSC Server/MGW • signaling latency can be different than voice latency (additional complexity) • Latency requirements on IP transport imposed by air interface signaling delay requirements e.g. HHO to be completed within TBD msecs

  6. Roaming and Inter-operability Issues • Handoff between legacy/evolved architecture • Handoff from legacy to evolved architecture will require changes to existing signaling procedures (e.g. target to specify vocoder assignment) • Transcoding Issues • With support for EVRC/13K/SMV enhancements needed for TFO operation • Mobile to Mobile transcoding (selection of MGW i.e. edge of core network vs. interior to core network)

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