Transcript Cable Modem
Developing Cable Telephony Solutions Ed Morgan , Executive Director, R&D Texas Instruments VoIP Group [email protected] August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com Agenda Packetcable Network Architecture Review Market Developments PacketCable Recent issues update Media Terminal Adapters Hardware and Software August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 2 Voice over Cable Architecture PC Embedded MTA Cable Modem PSTN TV Media Gateway Cable MSOs Comcast, Cox, TWC etc. IP Network Cable Head Equipment WLAN Phone Cable Modem IP Phone TA 3G Wireless TV PC Independent TSP AT&T, Qwest, Verizon, Vonage etc. August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 3 PacketCable Network Reference Diagram Record Keeping Billing system Server OSS/NMS CMTS HFC access network (DOCSIS) MTA PacketCable IP network (single zone) Cable Modem Call Management Server Embedded MTA Client (Call Agent) Media Gateway Managed IP Backbone Signaling Gateway MGCP PSTN August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 4 Market Developments Cable telephony services from Cable MSOs and Independent Telephony Service Providers are in widespread deployments Cable MSO Advantages Bundled product – common billing Better control over QOS through Packetcable Security implementation through Packetcable Independent Service Provider Advantages Mobility – take your telephone number with you when you go on vacation WLAN phones integration with cellular will increase mobility Low network infrastructure investment provides cost advantages August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 5 PacketCable Voice – Recent Topics Fax calls Modem calls Royalty free codecs August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 6 Fax and Modem Calls over Cable Problem Packet loss – without any error correction techniques, call success rates drop drastically with 1% packet loss. Clock offset at end-points will cause jitter buffer recentering, hence periodic modem retrains and potentially dropped calls Solution T.38 fax relay for fax calls RFC 2733 - Forward Error Correction (FEC) and RFC 2198 – Redundancy for modem calls August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 7 Fax Relay PSTN Fax Cable Modem with T.38 T.38 enabled Media Gateway IP Network Cable Head Equipment TV PC Demodulates incoming T.30 fax signals at the transmitting gateway Translates T.30 fax signals into T.38 Internet Fax Protocol (IFP) packets Exchanges IFP packets between transmitting and receiving T.38 gateways Translates T.38 IFP packets back into T.30 signals at the receiving gateway Modulates T.30 signals and transferring them to the receiving fax machine and vice versa August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 8 Key Elements of Fax Relay Fax relay provides: Delay Compensation Must compensate for the effects of the additional delay added by packet networks Packet Loss Compensation Must compensate for the effects of packet loss and packets received out of order Interoperability with a wide range of fax machines Must be compatible with mandatory and optional T.30 features Must be hardened through use in a variety of networks/environments Other value-added fax features: Ability to limit the high-speed data rate negotiated by the fax machines to less than available network bandwidth August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 9 Advantage of Fax Relay for Packet Loss Error hiding techniques improve fax call success rate in the presence of packet loss Call Success Rate vs. Network Packet Loss 100 Call Success Rate (%) 80 60 40 PCM (No Fax Relay) Telogy's R3 Software Telogy’s R8 Software 20 1 2 3 4 5 6 7 8 9 10 Random Packet Loss (%) August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 10 Modem Relay and VBD V.150.1 is an ITU standard defining an approach to supporting modem traffic over IP networks V.150.1 is a similar approach to fax relay but it has a very high memory and MIPs cost that will raise the cost of the cable telephony system An alternative approach is to use the VBD standard (V.150.2) where modem signals passed end-to-end through the VoIP gateway using G.711 and add forward error correction and redundancy using RFC 2733 and RFC 2198 The advantage of this approach is the relative simplicity and low cost of implementation The disadvantage is the added bandwidth required if redundancy is used August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 11 Royalty Free Codecs Objective is to introduce “royalty free” codecs into Packetcable spec to lower the BOM cost of cable modem and avoid royalty associated with ITU approved codecs (G.729E and G.728 are optional today) Two candidate have been identified – iLBC from Global IP sound and BV16 from Broadcom Current status is that codecs have incorporated into the Packetcable Spec 1.1 There are number of interop and IPR review gates to get through before acceptance Long term viability of these codecs is questionable without standardization because of need to interop with standard codecs in other VoIP and wireless systems Implementation of Wireless codecs like GSM-AMR and WBAMR are needed because of interop with wireless systems. August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 12 Media Terminal Adapters MTA Cable Modem Embedded MTA HFC access network (DOCSIS) MTA PacketCable IP network (single zone) Managed IP Backbone Cable Modem Standalone MTA Media Gateway Signaling Gateway PSTN Standalone vs Embedded August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 13 SRAM DOCSIS PHY 802.11 HPNA Eth MAC CPU Tuner XVR Ether FLASH SDRAM Embedded Media Terminal Adapter (EMTA) Cable Modem RAM ROM SLIC & CODEC DOCSIS MAC DSP August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 14 DOCSIS PHY RISC CPU Ether Mac Ether Xcvr RAM DSP ROM RISC CPU SLIC & CODEC USB Tuner FLASH MAC SDRAM DOCSIS Ether Mac Ether Xcvr 802.11 SRAM HPNA Standalone Media Terminal Adapter (SMTA) Cable Modem August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 15 Voice-Enabled Cable Modem Software Architecture Packet Cable mgmt. Voice Signaling DOCSIS mgmt. OS IP Stack Bridge Security DOCSIS L2 mgmt. Voice Processing Ethernet DOCSIS 1.1 Downstream BSP DSP DOCSIS 1.1 Upstream OS CPU Peripherals HAL Cable August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 16 Summary The evolution of today’s communication networks is driving changes in VoCable applications Cable telephony is adapting to provide integration with new communication technologies and services such as WiFi and 3G Wireless New developments in Packetcable are needed to address holes in the service offering like fax and modem support August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com 17