VoIP over 1xEv-DO Revision A CDG VoIP Summit. Robert Kerr Nortel Sr. Manager Access Product Evolution San Diego, Feb 8 05

Transcription

1 VoIP over 1xEv-DO Revision A CDG VoIP Summit Robert Kerr Nortel Sr. Manager Access Product Evolution San Diego, Feb 8 05

2 Presentation Topics 1. Why VoIP 2. Elements of a successful VoIP offering 3. VoIP capacity over DO Rev A 4. Voice Quality considerations 5. Signaling Analysis 6. Optimizing for VoIP deployment 2

3 Added value of VoIP over 1xEv-DO RevA > VoIP is just one practical application solving the VoIP challenge allows support of other revenue generating real time applications/services Rich Services (gaming, video conferencing, etc.) > Following the trends from the wireline industry Ability to offer seamlessly integrated and easy to use real time data services such as VoIP Strengthens competitive position among wireless operators > Enables a standalone 1xEv-DO RevA network with both broadband data and voice. Reduced Complexity in the network by duplication of functions > Enables a single carrier to support voice & data versus a dedicated voice & dedicated data carrier. > Simplified Network maintenance, seamless services integration & a richer end user experience 3 VoIP is a leading practical real time data application Paving the way for other new revenue generating services

4 Key Challenges in Commercializing VoIP > End to End QoS and Policy Enforcement between access and core Must be able to correlate billing records with QoS and service authorization > Network Performance Capacity User experience: Call setup times, voice quality In network vs. out of network performance > Security Management Firewall Traversals, Denial of Service attacks, Virus Protection, VPN Management > Regulatory Issues CALEA, E911, WPS, etc 4 VoIP over DO 1xEv-DO RevA requires an End-to-End solution extending all the way through the network

5 1xEv-DO RevA VoIP Enablers > Key enablers are low E-2-E network latency and FL/RL capacity > DORA network enhancements well suited to support VoIP > Forward Link Enhancements Improved FL packing efficiency (Short physical layer packets, multiuser packets) > Reverse Link Enhancements Increased reverse link throughput / capacity Support of reverse link hybrid ARQ, Support of sub-frames Reverse link MAC enhancements to reduce latency Flow specific MAC layer attributes > Flow specific attributes / QoS: Scheduler in BTS > Call set up enhancements Increased capacity and reduced latency supporting VoIP 5

6 VoIP requires End-2-End Network analysis Nortel Analysis A. VoIP Capacity End-2-End capacity analysis Packet Data network capacity, congestion, bottlenecks analysis 6 D. Network Latency Identify existing Network nodal bottlenecks, provide latency guidelines for leased or home network resources B. VoIP Quality E. Handoffs Assess impact on VoIP Voice quality Analyze / document required Recommend optimizations, acceptable handoff mechanisms tradeoffs C. Signaling assessment Messaging obstacles (# mess., length) Standards based optimization Call set up delay too long F. Core interactions Billing considerations Security (Net. Addr. translation, Firewall traversal) G. Quality of Service Define E-2-E network QoS flow, QoS negotiation mechanisms Nortel has completed VoIP analysis and is focusing on required standards based optimizations

7 Overall Capacity Summary 2% per-user outage in FL, No PPP overhead FL (Land-to-Mobile) Single receive antenna Dual receive antenna 1/8-rate frame blanking No Yes No Yes Airlink delay (ms) Capacity < < ~ RL (Mobile-to-Land) 8-slot Termination 12-Slot Termination 16-Slot Termination 1/8-rate frame blanking No Yes No Yes No Yes Airlink delay (ms) Capacity VoIP capacity is Reverse link limited Projected capacity of ~40 Users per Carrier-sector

8 Call Quality / Delay Analysis Delay Tolerable delay threshold DO Rev A 1xRTT Voice quality impact of delay Acceptable optimize delay DO to landline DO-DO calls: In a closed DO network DO to Land DO to DO DO to 1x Mobile call model DO to 1X trfo* Need to optimize delay DO to 1x: Requires TrFO* to mitigate delay. 2 wireless links + vocoding DO to Land 1x to Land DO to DO 1x to 1x DO to 1x without TrFO 61 DO to 1x with TrFO > Delay is not only parameter to consider in Voice quality analysis > ITU-T G.107 incrementally looks at MOS score to understand user experience Network delay ranges from acceptable to Needs optimization for the various call models. Delay critical to voice quality 8

9 Signaling Assessment Overview > The assessment examines the call setup delays that can be anticipated for VoIP calls in a 1xEv-DO Rev A based Multimedia Domain (MMD) network. > Our analysis is focused on 3 particular end to end call types 1. AT Handset to AT handset (i.e. Mobile to Mobile) AT implies DORA handset with a VoIP client 2. AT Handset to Landline (PSTN) 3. At Handset to 1xRTT phone (inter-technology Mobile to Mobile scenario) > Two 1xRTT based call types are included for comparative purposes. 1. 1xRTT MS to 1xRTT MS (i.e. Mobile to Mobile) 2. 1xRTT MS to Landline (PSTN) > In looking at call setup delays, the focus is on the time from the caller pressing Send to the caller hearing ring-back. This ringing provides assurance that the call is working and effectively restarts their mental timer. 9

10 User A Message Flow example AT to AT Visited1 BTS DOM + RN PDSN HA Home1 Home2 I-CSCF P-CSCF S-CSCF I-CSCF S-CSCF P-CSCF HA PDSN Visited2 RN+ BTS DOM User B HSS AS (A) Dormant To Active TCP** Connection 1 SIP INVITE Connection Request (ACH) Route Update (ACH) AC Ack (CC) Traffic Channel Assignment (CC) Pilot + DRC (RTC) RTC Ack (FTC) Traffic Channel Complete (RTC) TCP:SYNC (port 5060) TCP:SYNC+ACK (port 5060) TCP:ACK (port 5060) verification of session ownership * S-CSCF determines correct Home2 I- CSCF from HSS(1) Preconditions: Both User A and User B terminals have been powered on, and have registered with the DO & Packet Data Core Networks and the SIP Server. Neither terminal has an RF link at the time of the call. AS access for A would occur here if included in timings. TCP** Connection 2 (B) D to A TCP** Connection 2 (Cont d) SIP INVITE (Cont d) 10 Example of extensive invite messaging from terminal A to terminal B I-CSCF gets S-CSCF from HSS(2) AS access for B would occur here if included in timings. If UDP is used, the SIP Invite reaching the RNC triggers the Traffic Channel setup.** The Invite then proceeds to the AT. * For clarity, reverse direction 100 Trying messages, in response to Invites, are not shown. ** TCP signaling shown. If UDP is chosen, there is no equivalent UDP messaging. TCP:SYNC (port 5060) Page Route Update (ACH) AC Ack (CC) Traffic Channel Assignment (CC) Pilot + DRC (RTC) RTC Ack (FTC) Traffic Channel Complete (RTC) TCP:SYNC (port 5060) TCP:SYNC+ACK (port 5060) TCP:ACK (port 5060)

11 User A Message Flow - AT to AT - continued Visited1 BTS DOM + RN PDSN HA Home1 I-CSCF P-CSCF S-CSCF I-CSCF S-CSCF P-CSCF HA HSS AS Home2 PDSN Visited2 RN+ BTS DOM User B SIP 183 SIP PRACK SIP 200 OK SIP UPDATE SIP 200 OK Authorize QoS Resources UE Resource Reservation. Messaging between UE and P-CSCF. Authorize QoS Resources UE Resource Reservation Alerting SIP 180 Ringing Ring-back SIP PRACK SIP 200 OK Answer SIP 200 OK (to INVITE) Media Flow P-CSCF enables Media flow at PDSN. Media Flow SIP ACK P-CSCF enables Media flow at PDSN. 11 Example: Messaging leads to 8.5 sec call set up delay

12 Example Result for Post Dial Delay Local/National IPv4/v6 TCP/UDP ROHC SIP Compression National 4 UDP Yes Yes (PAD) Post Answer Delay (PDD) Post Dial Delay Target ITU PDD for National call. Seconds Targeted interval Industry Benchmark 1x CS voice today AT to 1x AT to AT AT to Land 1x to 1x 1x to Land Call Types Post Dial delay currently excessive due to signaling

13 Contributions to Post Dial Delay > In most cases, transport of the SIP messages over the air link is the single largest contributor to PDD. Local / National National IPv4/v6 4 TCP/UDP UDP ROHC Yes SIP Compression Yes Seconds Post Dial Delay Breakdown Core Network Signaling over RF Link Traffic Channel Setup AT to 1x AT to AT AT to Land Call Type ITU reference Target Post Dial delay optimization opportunities are understood 13 and being worked for future standards contributions

14 MMD based Signaling assessment Conclusions > Post dial delays for VoIP calls using SIP based signaling are projected to be from 3 to 6.5 seconds longer than the accepted targets > Expected call set up target of 3 seconds increases required optimization to between 5 and 8.5 seconds > The actual call set up delay will vary depending on the call type and network assumptions. > Of the AT originated call types, no network options achieved PDD targets for VoIP over DOrA calls with the exception of AT to Land calls. > Nortel is making good progress internally on proposals to optimize the signaling and reduce the signaling delay. Optimization of signaling should target maximum optimization while preserving SIP extensibility. How Signaling is optimized/implemented has yet to be resolved. 14

15 Conclusions > Nortel VoIP Capacity simulations demonstrate VoIP over 1xEv-DO RevA can provide 1X or greater capacity, and continued industry focus is justified. > Voice quality is challenged by network delay Additional bearer path delay optimization would further enhance Voice Quality, specifically for DO to 1x and DO to DO call models. Nortel has identified Key areas for delay improvement > Signaling analysis: Problem areas requiring industry effort to resolve Post dial delays for VoIP calls using MMD SIP based signaling are projected to be from 0.1 to 8 seconds longer than the accepted targets None of the call types (e.g. AT to AT, AT to Land) or network options (e.g. IPv4 vs. IPv6) achieved Post Dial Delay targets for VoIP over DO RevA calls. Nortel is committed to defining Standards changes, or additions to the MMD SIP signaling architecture to support VoIP over DO RevA using an MMD architecture 15 VoIP over DO Rev A is a valid evolution path, meriting further industry focus to support over 1xEv-DO RevA

16 Thank you