The Distributed DawnThe emergence of versatile performance in theconferencing environment

Connect. Any Way You Want.

Author:Jeff RodmanFellow/CTO

June 2, 2004

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IntroductionSystems that allow remote groups to interact inreal time have dramatically grown in capabilityover the last thirty years. From the earliestinstances of people huddled around the earpieceof a "candlestick" phone to today's fully-featuredconference systems, the ability of people tocooperate over large distances has seen continualenhancement.

Along with the expanded capabilities of thesesystems, though, has been a growth in the numberof physical elements that comprise them, and thedifficulty of their operation. While the capabilitieshave increased, so has the subjective complexity,with the result that many fully-featured systemstoday are cluttered, difficult to understand,difficult to grow, and difficult to operate.

A new generation of systems has been introducedto alleviate this problem by coordinating theoperation of its elements, and by allowing forthe dynamic allocation of capabilities as meetingrequirements change moment to moment. Thisresults in a simpler and more unified control of thevarious functions in a meeting, more predictableand consistent behavior, less clutter on thetabletop, a more transparent presence overall,and a more versatile architecture that cansupport further growth.

The VSX™ Distributed Conference SystemArchitectureFrom the user's perspective, one of the mostimportant interfaces is the one where much ofthe conference occurs: on the tabletop. A new,versatile interface structure has been developedto provide versatility and high performance whilemaintaining a low physical profile. This is calledConferenceLink, and embodies both a physicaland data format structure that are particularlywell-suited to multimedia conferencing.

VSX Infrastructure: The ConferenceLink BusConferenceLink (Figure 1) is a robust and powerfuldigital communication bus that is optimized tosupport multiple media devices.

An increasing number of devices are compatiblewith the ConferenceLink format, including theVSX 7000 and VSX 8000 Videoconferencingsystems, the SoundStation VTX 1000™ voice

conferencing system, the Virtual Concert graphicsinterface system, and the VSX microphone module.ConferenceLink's independence of the nature ofthe media it carries, and its optimization forreliable high bandwidth, bring many potentialsto this growing ecology.

ConferenceLink contains independent clock anddata channels (Figure 2). The total data rate is36.768Mbps, divided into frames of 32kHz or48kHz. These can be partitioned, for example,to provide 46 audio channels (16-bit audio at48ksps for >20 kHz bandwidth) in an audio-onlysystem, 32 two-megabit H.263 or H.264 videochannels, 36 Mbps of raw high-availability databandwidth, or any other desired allocation.Peripherals can both send and receive data, and

the data format, which is pre-scheduled,assures no collisions or lost packets andextremely low latency. As seen, ConferenceLinkcan also support daisy-chaining, which minimizescabling while maximizing coverage.

This high data bandwidth is especially valuablebecause it allows the exchange of more thanjust microphone outputs: intermediate datastreams can be exchanged, which means sig-nificant processing resources can be distributedthrough the system, not just in a set-top or room

processing module. This is, in effect, a meshcomputing network: an immensely flexible systemarchitecture because processing can be scaledto match customer requirements, and a basicsystem does not need to be expensivelyover-designed to protect against possible futureneeds. Additional functions and additional pro-cessing can be added, when and where needed,as requirements develop.

Figure 1: A Simple ConferenceLink PhysicalConnection

Figure 2: ConferenceLink Physical Connection

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SoundStation VTX 1000 in a ConferenceLink-enabled System The SoundStation VTX 1000, introduced last year,has spawned a revolution in high-performancevoice conferencing. Beyond its precedent-settingability to carry high-fidelity 7kHz voice overconventional POTS telephone lines worldwide,it also provides an extraordinary 20-foot voicepickup range without additional microphones,versatile audio interface capabilities, noisereduction, software upgrades for feature andperformance upgrades in the field, and numerousother features. But this all stems from aground-up design that supports configurability,flexibility, and distributed processing.The

SoundStation VTX 1000 (Figure 3) serves a fullset of audio input and output functions with anextremely powerful signal processor, which canprovide up to 1 billion operations per second. Byway of comparison, this is more than 50% morepowerful than the processor used in Polycom'searlier ViewStation® 128 videoconferencingsystem. The VTX1000 is architected to treat thespeakerphone function as a modularized applica-tion that is executed by this processor, rather

than as a dedicated function. This allows muchmore versatility in adding new functions, inter-faces, applications, and in implementing dis-tributed processing.

The SoundStation VTX 1000 also contains a fullConferenceLink interface, and in its software versions1.4 and later, Is compatible with the VSX 7000 or VSX8000 video conferencing system version 7.0 or latervia this ConferenceLink connection.

Capabilities in Integrated ModeWhen a SoundStation VTX 1000 is connected tothe VSX 7000 or VSX 8000 via ConferenceLink,it expands the capability of the VSX 7000

because the video system is now presentedwith additional sets of resources: acousticresources, common user interface resources,and processing engine resources.

SoundStation VTX 1000 Acoustic ResourcesThe SoundStation VTX 1000 operates at aninternal sampling rate of 32kHz, which is highenough to support audio performance up to14kHz. In SoundStation VTX 1000 standalone

mode, audio bandwidth is 3kHz (during normalnarrowband analog calls) or 7kHz (in VTX wide-band analog connections over POTS). However,the SoundStation VTX 1000 operates as a 14kHzperipheral when connected to the VSX7000 viaConferenceLink (Figure 4).

All of the acoustic resources of the SoundStationVTX 1000 are available to the VSX 7000 at fullbandwidth: the three internal microphones, theinternal loudspeaker, the EX microphones, theAuxiliary input, the Auxiliary output, and thetelephone interface, both narrowband andwideband. Note from this figure that while theSoundStation VTX 1000 may be supporting anarrowband POTS call, it can simultaneouslysupport 14kHz audio to the VSX 7000. In a mixedcall like this, then, it will seem to everyone as ifthey all have a great 14kHz wideband connection,except that one person's phone (the one on theconventional POTS call) will sound muffled.

SoundStation VTX 1000 User Interface ResourcesBecause the SoundStation VTX 1000 naturallyresides on a conference table and contains agraphic backlit LCD, keypad, and several LEDs, itcan provide convenient access to some of the most common user interface functions. Theseelements are all available to the VSX 7000 via the ConferenceLink, either as button presses andbitmapped pixel images, or as interpreted data.

SoundStation VTX 1000 Processing EngineResourcesThe SoundStation VTX 1000 processor containsan additional 1000 million instructions persecond (MIPS) of processing power that isavailable to the VSX 7000 when needed, andthe ConferenceLink bus provides high-availability,high-speed access that is the data bus equivalentof an eight-lane superhighway. While the 36Mbpsdata rate seems one-third that of a 100BaseTconnection, the achieved bandwidth is severaltimes what can be reliably achieved over most100BaseT networks because ConferenceLinkis a fully time-scheduled protocol: Packetcollisions, backoff, and resends never occur, sothe data bandwidth is almost entirely availablefor payload.

Figure 3: SoundStation VTX 1000 Resources accessi-ble via ConferenceLink

Interestingly, the fact that the SoundStationVTX 1000's media processor is co-located withthe microphones does not mandate that it beused for microphone processing; if the systemarchitect desired, it could equally well be usedfor some video processing task, as long as it fitwithin the overall constraints of the system. Itis this kind of flexibility that makes theConferenceLink and VTX-VSX architectureparticularly powerful and versatile.

The Potential of Distributed IntegrationWith all of these capabilities, the questionmoves from "can we do it" to "what shall we do?"Expanding the availability of high-performanceresources such as microphones, processing,displays, and controls offers the potential ofsimpler, better, and more compact conferencingconfigurations. Some possible advantagesinclude the elimination of multiple microphonesfor multiple independent systems in the sameenvironment, the harmonization of user interfacesand system control, implementation of acommon dialing structure, a lower rate of obso-lescence due to more flexible expandability, andleveraging the addition of new features into allsystem uses, not just one. The Polycom whitepaper "The Power of Shared Resources" discussesa pioneering implementation of such a system,using the VSX 7000 and SoundStation VTX 1000products as available today. Polycom believesthat this is the tip of the iceberg, and that the userbenefits of this radical architectural approachwill continue to make very substantial improve-ments in the way systems, and users, operate.

The Polycom Office™With integrated video, audio, data, and Webcapabilities, The Polycom Office is the onlysolution that offers an easy way to connect,conference, and collaborate any way you want.Work faster, smarter, and better with ThePolycom Office.

Polycom, Inc. develops, manufactures andmarkets a full range of high-quality, easy-to-useand affordable voice and video communicationendpoints, video management software, webcollaboration software, multi-network gateways,and multi-point conferencing and networkaccess solutions. Its fully integrated end-to-endsolution, The Polycom Office, is supported by thePolycom accelerated communications architec-ture and enables business users to immediatelyrealize the benefits of integrated video, voicedata and web collaboration over rapidly growingconverged networks.

Figure 4: SoundStation VTX 1000 Internal Bandwidth Domains

Rev 7/04

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