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Wireless Internet Telephony

Wireless Internet Telephony. Tom La Porta Director, Networking Techniques Research Department Bell Labs, Lucent Technologies. Outline. Background and Overview Transport mobility management and QoS wireless specific services Signaling and Control mobility management

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Wireless Internet Telephony

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  1. Wireless Internet Telephony Tom La Porta Director, Networking Techniques Research Department Bell Labs, Lucent Technologies

  2. Outline • Background and Overview • Transport • mobility management and QoS • wireless specific services • Signaling and Control • mobility management • call control and interworking

  3. Mobile Internet Telephony - All IP • Goal: migrate wireless mobile access networks to IP • Support the anticipated explosive growth of the wireless Internet • merging of services for wireline and wireless networks • merging of wireless voice and data networks • Reduced product and operational costs of IP infrastructure • increased efficiency of packet-based networks for combining voice and data • Technical Challenges: • Transport: • quality of service • real-time mobility management • wireless specific services • Signaling and Control: • personal and device mobility • call control • interworking with existing telephony systems

  4. HLR BS BS BS MSC/VLR BSC BSC PSTN & SS7 Current Cellular Networks: Circuit Switched BS: base station BSC: BS controller MSC: Mobile Switching Center VLR: Visitor Location Register HLR: Home Location Register 1. Air 2. Backhaul 3. Full Rate 4. Full Rate • Link 1: Air Interface • compressed voice (8Kbps) on “dedicated” channel • Link 2: Backhaul • compressed voice multiplexed on sub-rate circuits • BSC performs voice coding to 64 Kbps (one option) • BSC performs soft handoff or frame selection function (one option) • Link 3-4: Full rate • full rate voice switched at MSC to the PSTN • MSC may perform voice coding and soft handoff

  5. HLR Access PVG Access PVG Egress PVG BS BS BS PSTN & SS7 Migration to All-IP: Packet Core Software Controller Intranet BS: base station PVG: Packet-Voice Gateway HLR: Home Location Register 4. Full Rate 3. Packet Voice 1. Air 2. Backhaul • Link 1: Air Interface • compressed voice (8Kbps) on “dedicated” channel • Link 2: Backhaul • compressed voice multiplexed on sub-rate circuits • Access PVG performs soft handoff or frame selection function • Access PVG may perform voice coding • Link 3: Packet Voice • RTP session between Access and Egress PVGs • Egress PVG may perform voice coding • Link 4 • full rate voice switched at Egress PVG to the PSTN

  6. HLR IP-BS IP-BS IP-BS Egress PVG IP-BSC IP-BSC PSTN & SS7 All-IP Software Controller Intranet Internet 5. Packet Voice 4. Full Rate 3. Packet Voice 1. Air 2. Backhaul • Link 1: Air Interface • compressed voice (8Kbps) on “dedicated” channel • Link 2: Backhaul • aggregated, compressed IP voice • IP-BSC performs soft handoff or frame selection function • Link 3: Packet Voice • RTP session between Access and Egress PVGs • Egress PVC performs voice coding • Link 4 • full rate voice switched at Egress PVG to the PSTN • Link 5: Packet voice to Internet

  7. Outline • Background and Overview • Transport • mobility management and QoS • wireless specific services: Soft Handoff and Paging • Signaling and Control • mobility management • call control and interworking

  8. SGSN SGSN Radio Access Networks MD Internet Current Telecom-Based Mobile Packet Networks: GPRSGeneral Packet Radio Service Regular routing Tunneled packets using special methods GGSN Host Intranet • Compatible with cellular telecom networks • may be deployed using existing infrastructure • requires separate advances from the Internet • Specialized nodes manage mobility and forward packets • requires no changes to fixed hosts or intermediate routers • results in triangular routing • special failure recovery mechanisms needed • Packets are tunneled through the Intranet • intermediate routers are not mobile-aware • difficult to perform QoS • Inter-SGSN handoffs always managed by GGSN • high update overhead • slow handoffs

  9. FA FA Current Internet-Based Mobile Packet Networks: Mobile IP Tunneled packets using IP HA Regular routing Radio Access Networks MD Host Internet • Compatible with regular IP networks and hosts • most Internet advances apply • Specialized agents manage mobility and forward packets • requires no changes to fixed hosts or routers • results in triangular routing • special failure recovery mechanisms needed • Packets are tunneled through the Internet • Internet routers are not mobile-aware • difficult to perform QoS • Handoffs always managed by Home Agent • high update overhead • slow handoffs • No paging • high update overhead

  10. Internet Domain Router Domain Router MD Local mobility Local mobility Mobile IP R R R R R R R R R R R R HAWAII: A Domain Based Approach to IP Mobility • Distributed control: Enhanced reliability • host-based routing entries in routers on path to mobile • Localized mobility management: Lower overhead, fast handoffs • updates only reach routers affected by a movement • Minimized or Eliminated Tunneling: no triangular routing, easy QoS • dynamic, public address assignment to mobile devices • Supportspaging • Compatible with Mobile IP

  11. Internet Domain Router R1 R R R R2 R3 MD HAWAII: Local Mobility • Initial host-based routing entries in routers shaded in yellow (DR, R1, R2) • minimizes number of host-based entries • Update host-based routing entries in routers shaded in green (R3, R1) • minimizes number of routers processing updates • reduces handoff time • Address of mobile device remains constant • allows uninterrupted communication • allows QoS entries in unaffected routers (yellow) to remain unchanged

  12. Network Model Domain Router ... • 39 users/sq. miles • users moves at 112 Km/hr. • base stations cover 7 Km2 Router 1 Router 7 ... BS-R20 BS-R20 BS-R1 BS-R1 HAWAII Overhead • Comparison of most heavily loaded entities in each network: • HAWAII DR processes 34% number of messages as M-IP HA • HAWAII DR is utilization is 11% of M-IP HA

  13. HAWAII Handoff Delay: Packet Loss Audio (160B/20msec) Video (4KB/33msec)

  14. HAWAII Performance: Handoff Delay • Voice (or other real-time applications): less disruption • packets dropped due to late arrival: Local Mobile IP IP network delay Roaming Mobile IP HAWAII Acceptable for voice

  15. Domain Router Domain Router MD R R R R R R R R R R R R Wireless Services: IP-Paging Paging entry Internet Multicast entries • Hierarchical scheme • scaleable • allows load balancing between levels of routers • Uses IP Multicast • no new protocols • Alternatives • paging from Home Agent • paging from Foreign Agent • Result: • Domain paging supports ~10% higher load than FA-Paging

  16. Domain Router Domain Router MD R R R R R R R R R R R R Wireless Services: IP Soft Handoff Internet IP Soft Handoff • Goals • true end-to-end IP networking • leverage IP protocols (e.g., multicasting) • support efficient routing • Challenges • traffic aggregation • processing overhead • QoS

  17. Outline • Background and Overview • Transport • mobility management and QoS • wireless specific services • Signaling and Control • mobility management • call control and interworking

  18. User/mobile location management Integrate HLR/VoIP server Security control (authentication center, IP security server) functions Service profile DB management IP security server Integrated SIP Registrar and HLR • Provide enhanced HLR functionality for Internet and wireless network users Current HLR Cellular VoIP server Internet (VoIP) MAP / SS7 User location manager Cellular • Integrate 3 key functions of HLR & IP (VoIP) servers • mobility management • security • profile management • Support multiple standard interfaces • Wireless: ANSI 41, GSM / UMTS MAP • Internet: VoIP (SIP, H.323), AAA (RADIUS) Protocol Gateways Integrated User Profile Database VoIP / IP AAA / IP Internet Security manager Super HLR Next-Generation

  19. Registration and locally assigned number Information from registrar Mobile Phone # SIP URL Current Location Area Current Location Area Home Switch SIP Server Calling party Calling party Terminal Terminal Mobility Management: Terminal and User Mobility • Current telephone network • mobile phone number points to home network of device • home network points to current location based on registration information and locally assigned temporary phone numbers • SIP • personal URL defines a server • registrars and proxies point to devices • extra level of indirection of interworking with cellular phone

  20. User PSTN networks Tel #2 AMPS / PCS Wireless access networks Mobility Management • User mobilityacross networks (wireless, Internet)in addition to terminal mobility • Manage profile information for a ‘user’, not a ‘wireless terminal’ • Call delivery to the current user terminal Unified user location DB • Global roaming between network types • Receive the same service anywhere Unified service profile  Super HLR SIP user name (URL) Tel # 1 (MSISDN) BS User location manager   Internet SIP terminal  GSM phone PSTN phone Security manager User location DB

  21. Modified registration HLR PSTN/MAP + SIP registrar SIP proxy Dual registration Serving MSC Call delivery (SIP )    BS SIP terminal SIP terminal SIP terminal IP stream up to BS Internet Super HLR SIP registrar + SIP call proxy HLR PSTN GW Preliminary Analysis: Internetworking with Super HLR • Call delivery from a SIP terminal to a GSM phone • No dual registration or routing number lookup with super HLR • 15~30% less signaling message load • Modified call setup • Super HLR MAP mobile registration Routing info. lookup  HLR + PSTN/MAP Home MSC SIP proxy Mobile registration IP Wireless Access Serving MSC Call delivery (SIP ) Call delivery (SIP ) BS BS IP stream up to BS IP up to BS Serving MSC Internet Internet

  22. Use called party’s protocol User Use calling party’s protocol Call Control: Internetworking among wireless, VoIP, and PSTN networks Develop general internetworking models and procedures  To avoid different procedures for each internetworking scenario Call delivery to home/gateway MSC or SIP proxy Location query to super HLR Routing information if delivered to wireless mobile terminal Call delivery to a mobile terminal  Extend the procedures for supplementary services Super HLR (2) LOCREQ/SRI SIP location lookup SIP user name DN1 (MSISDN) (1) IAM / SIP INVITE (3) Request Location hMSC /gMSC SIP proxy PG 1 (10) locreq/SRI Ack SIP loc. Lookup rsp sHLR User Location Server (9) Request Location RSP user profile (11) IAM / SIP INVITE (4) DB lookup (5) Request Route Info DN2 (6) ROUTEREQ / PRN Serving MSC SIP UA PG 2 (7) routereq / PRN Ack (8) Request Route Info RSP SIP terminal GSM phone PSTN phone (12) Call delivery Core s-HLR operations User location DB

  23. AAA / IP MAP / SS7 VoIP / IP DB manager Security manager Super HLR : Architecture • Super HLR core servers • Common functions across protocols • Multiple server instances on a cluster of processors for system scalability • Interworking function between protocols: O(n) versus O(n2) complexity • Super HLR common operations • Protocol independent • Protocol gateways • Performs protocol specific control • Facilitates new protocol introduction • Integrated user profile DB • Common database for a ‘user’ PG MAP Super HLR User location manger PG VoIP Super HLR Common operations Integrated user profile Database PG AAA       s-HLR core servers

  24. Summary • Mobile Internet Telephony requires: • Transport advancements • efficient mobility management • QoS • wireless services • Signaling advancements • additional levels of mobility • interworking with cellular telephony • Other Issues • efficiency of Internet signaling over the air

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