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

1 Outline Background and Overview Transport – mobility management and QoS – wireless specific services Signaling and Control – mobility management – call control and interworking

2 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

3 Current Cellular Networks: Circuit Switched BS BSC MSC/VLR PSTN & SS7 HLR BS BSC BS: base station BSC: BS controller MSC: Mobile Switching Center VLR: Visitor Location Register HLR: Home Location Register 1. Air2. Backhaul3. Full Rate4. 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

4 Migration to All-IP: Packet Core BS Access PVG Software Controller PSTN & SS7 HLR BS BS: base station PVG: Packet-Voice Gateway HLR: Home Location Register 1. Air2. Backhaul 3. Packet Voice 4. Full Rate 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 Access PVG Egress PVG Intranet

5 All-IP IP-BSC Software Controller PSTN & SS7 HLR IP-BS 1. Air2. Backhaul 3. Packet Voice 4. Full Rate 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 Egress PVG Intranet IP-BS IP-BSC Internet 5. Packet Voice

6 Outline Background and Overview è Transport – mobility management and QoS – wireless specific services: Soft Handoff and Paging Signaling and Control – mobility management – call control and interworking

7 Current Telecom-Based Mobile Packet Networks: GPRS General Packet Radio Service 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 Intranet MD SGSN GGSN Host Regular routing Tunneled packets using special methods Internet SGSN Radio Access Networks

8 Current Internet-Based Mobile Packet Networks: Mobile IP 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 MD FA HA Host Internet Regular routing Tunneled packets using IP FA Radio Access Networks

9 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 Supports paging è Compatible with Mobile IP Domain Router RR RRRR Domain Router RR RRRR Local mobility Mobile IP Internet MD

10 HAWAII: Local Mobility Internet Domain Router R2R3RR RR1 MD 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

11 HAWAII Overhead Domain Router Router 1 Router 7... BS-R1 BS-R20... BS-R1 BS-R20 39 users/sq. miles users moves at 112 Km/hr. base stations cover 7 Km 2 Network Model Comparison of most heavily loaded entities in each network: è HAWAII DR processes 34% number of messages as M-IP HA è HAWAII DR is utilization is 11% of M-IP HA

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

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

14 Wireless Services: IP-Paging 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 Domain Router RR RRRR Domain Router RR RRRR Internet MD Paging entry Multicast entries

15 Wireless Services: 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 Domain Router RR RRRR Domain Router RR RRRR Internet MD IP Soft Handoff

16 Outline Background and Overview Transport – mobility management and QoS – wireless specific services è Signaling and Control – mobility management – call control and interworking

17 Integrated SIP Registrar and HLR  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) Provide enhanced HLR functionality for Internet and wireless network users Current Integrate HLR/VoIP server functions MAP / SS7 Integrated User Profile Database Security manager Protocol Gateways User location manager Cellular Internet VoIP / IP AAA / IP Next-Generation Internet (VoIP) VoIP server IP security server Cellular HLR User/mobile location management Security control (authentication center, IP security server) Service profile DB management

18 Mobility Management: Terminal and User Mobility Current Location Area Terminal Home Switch Calling party Mobile Phone # Registration and locally assigned number 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 Current Location Area Terminal SIP Server Calling party SIP URL Information from registrar SIP – personal URL defines a server – registrars and proxies point to devices – extra level of indirection of interworking with cellular phone

19 Mobility Management User mobility across 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 PSTN networks Internet  Security manager User location manager User location DB GSM phone SIP terminal PSTN phone User SIP user name (URL) Tel # 1 (MSISDN) Tel #2 AMPS / PCS Wireless access networks BS   

20 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 PSTN/MAP BS Internet Serving MSC HLR + Call delivery (SIP ) Mobile registration IP stream up to BS SIP proxy Home MSC Routing info. lookup Modified registration PSTN/MAP BS Internet Serving MSC HLR + Call delivery (SIP ) Dual registration IP stream up to BS SIP registrar SIP proxy  SIP terminal Super HLR IPWirelessAccess BS Internet Call delivery (SIP ) MAP mobile registration IP up to BS HLR SIP registrar + SIP call proxy GW PSTN  Serving MSC  SIP terminal  SIP terminal

21 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 Use calling party’s protocolUse called party’s protocol sHLR User Location Server user profile hMSC /gMSC SIP proxy PG 1 (2) LOCREQ/SRI SIP location lookup (10) locreq/SRI Ack SIP loc. Lookup rsp Serving MSC SIP UA PG 2 (6) ROUTEREQ / PRN (7) routereq / PRN Ack (3) Request Location (1) IAM / SIP INVITE (12) Call delivery (11) IAM / SIP INVITE (4) DB lookup (9) Request Location RSP (5) Request Route Info (8) Request Route Info RSP Core s-HLR operations GSM phone SIP terminal PSTN phone User User location DB SIP user name DN1 (MSISDN) DN2 Super HLR

22 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(n 2 ) 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’ Super HLR Common operations MAP / SS7 VoIP / IP AAA / IP PG MAP PG VoIP PG AAA Integrated user profile Database DB manager User location manger Security manager s-HLR core servers

23 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