Wireless Internet Telephony

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