developing cable telephony solutions

August 3-4, 2004 • San Jose, CA • www.voipdeveloper.com

Developing Cable Telephony Solutions

Ed Morgan , Executive Director, R&DTexas Instruments

VoIP [email protected]

2August 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


IPNetwork

PC

Voice over Cable Architecture

TV

Embedded MTA Cable Modem

PSTN

Cable HeadEquipment

MediaGateway

PCTV

Cable Modem

TA

Cable MSOsComcast, Cox, TWC etc.

Independent TSPAT&T, Qwest, Verizon, Vonage etc.

IPPhone

3GWireless

WLANPhone


PacketCable Network Reference Diagram

Managed IPBackbone

HFC accessnetwork

(DOCSIS)

PSTN

PacketCableIP network

(single zone)

MediaGateway

SignalingGateway

CallManagement

Server

Record KeepingServer Billing system

OSS/NMS

CableModemMTA

Embedded MTAClient

CMTS

MGCP(Call Agent)


Market DevelopmentsCable 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


PacketCable Voice – Recent Topics

Fax calls Modem calls Royalty free codecs


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 re-

centering, 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


Fax Relay

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

IPNetwork

PCTV

Cable Modem with T.38

PSTNFax

Cable HeadEquipment

MediaGateway

T.38enabled


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


1 2 43

100

80

60

40

20

5

Random Packet Loss (%)

Cal

l Suc

cess

Rat

e (%

)

PCM (No Fax Relay)

Telogy’s R8 Software

6 7 8 9 10

Telogy's R3 Software

Call Success Rate vs. Network Packet Loss

Advantage of Fax Relay for Packet Loss Error hiding techniques improve fax call success rate

in the presence of packet loss


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


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 WB-AMR are needed because of interop with wireless systems.


Media Terminal Adapters

Managed IPBackbone

HFC accessnetwork

(DOCSIS)

PSTN

PacketCableIP network

(single zone)

MediaGateway

CableModemMTA

Embedded MTA

SignalingGateway

Cable Modem

Standalone MTA

MTA

Standalone vs Embedded


Embedded Media Terminal Adapter (EMTA) Cable Modem

RAM

DOCSISMAC

SRAM

DOCSISPHY

CPU

TunerSD

RA

M

FLA

SH

HPN

A

802.

11

Ethe

rXV

R

DSP

EthMAC

SLIC & CODECROM


Standalone Media Terminal Adapter (SMTA) Cable Modem

RAM

DOCSISMAC

SRAM

DOCSISPHY RISC

CPU

Tuner SDR

AM

FLA

SH

HPN

A

802.

11

DSP

SLIC & CODEC

ROMEthe

r Xcv

rEt

her M

acRISCCPUEt

her M

acEt

her X

cvr

USB


Voice-Enabled Cable Modem Software Architecture

DSP CPU Peripherals Cable

BSP OS HAL

DOCSIS L2

mgmt.

DOCSIS 1.1 Upstream

DOCSIS 1.1 Downstream

Voice Processing

Bridge

Voice Signaling

DOCSIS mgmt.

Packet Cable mgmt.

Ethernet

Security

OS IP Stack


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

developing cable telephony solutions

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