Chan, Vincent Wai-Sun

Lucky, R. W.

Prodromou, Elizabeth H.

English

MIT Libraries Dome

COMMUNICATIONSFORUM"The Changing World of Communications"May 7, 1992MIT COMMUNICATIONS FORUMROOM E40-242ACAMBRIDGE, MA 02139(617) 253-3144MASSACHUSETTS INSTITUTE OF TECHNOLOGYHE7601.S460ee,A I.T. LBuI5 wRMASSACHUSETTS INSTITUTE OF TECHNOLOGYCOMMUNICATIONS FORUM"The Changing World of Communications"May 7, 1992Seminar NotesDr. Robert Lucky, AT&T Bell LaboratoriesDr. Vincent Chan, MIT Lincoln Laboratories, ModeratorElizabeth H. Prodromou, MIT, RapporteurLDr. Chan introduced today's speaker, whose topic dealt with the complex interplay oftechnology, economics, sociology, and politics that is changing the rapidly emerging world ofcommunications.The speaker was Dr. Robert Lucky of AT&T Bell Laboratories. Lucky began by noting thathis talk would use a hodgepodge of overheads, collected from as far back as the Bell Systemdivestiture in 1984, all of which point to the fascinating array of changes that have characterizedand continue to shape the communications field. Lucky remarked that the panorama ofcommunications today is strikingly broad, and he noted that the engineers and other individualsinvolved at AT&T in broadening the communications field are actually making a reality out of ideasand technologies that, not long ago, were nothing more than dreams.According to Lucky, the technical issues in communications begin in the "basement" ofAT&T, because this is where the transmission engineers work. These are the people generating somuch band width that the rest of AT&T doesn't know what to do. People keep generatingbandwidth, or transmission capacity, but the applications uses can't keep up with the growth incapacity.We have reached a point of over-abundance on the curve for capacity of transmissionsystems. We have more capacity than we can use. And some people at AT&T feel that this isgoing to put us out of business, because the expansion of capacity is driving down the value ofbytes to such a point that they are almost free. Communications may become independent ofdistance, in terms of cost, or they may become independent of bandwidth. The lag betweenexperimental systems and commercial systems is about five years. For the people who make thetransmission systems, the keeper of the channel is the physicist. But the physicist has no realconcept of the communications system. And the communications engineer has no real concept ofwhat the physicist does.Lucky considered the capacity of optical fiber. We often talk about the capacity of a singleoptical fiber as being ten-to-the-minus-thirty terra, with a bandwidth of 25,000 gigabytes. We aretalking about up to 25 terra bytes per second, multiplied by some distance.We have been lying on the Moore Curve for some time, and this probably will continueunabated. But what really is the limit of the capacity of optical fiber? According too Lucky, theonly real answer to this question is that nobody knows. Serial systems are sending at onebandwidth. This is how most systems work. The new systems being developed send at 10gigabytes per second. With experimentation, we are finding some disagreeable things. Luckyremarked that, coming from a communications systems background, he has a simple view of whatbandwidth is. But the concept of bandwidth needs to be reconsidered. There are about a dozencomplex phenomena that intermodulate the different wavelengths, and we are now havingarguments about whether or not these are intrinsically connectable effects.In Lucky's view, there is a tremendous bandwidth capacity in the fibers already under theground. Recently, thought, there have been some very big breakthroughs on these long-haul lines.Almost everything that's happening is changing the dynamics of human communications,particularly in terms of the psychology of human communications. Technically, the problem withrepeaters is that they mute to a particular byte rate. The optical amplifier is a breakthrough that istoo simple and too good to be true - and it works underseas and terrestrially. This erbium-doped,optical fiber amplifier helps to amplify the input system regardless of the optical line it was on.What you create is like a hollow tube that takes light and transports it intercontinentally. If youwant to change the byte rate, you just change the modulation. This gives the network a verycurious attribute of physical transparency.Another fascinating possibility is the soliton. This is related to the transmission issues. Thesolitons have been studied for decades. All media are non-linear, as are optical fibers. The fiber isJalso linear dispersive. The soliton is a special pulse that has the property whereby non-lineardispersion compensates exactly for linear dispersion. The has soliton created a big flap. Peopledidn't believe the conclusion that the use of solitons meant that transmission has not significantlymodified the pulse. But eventually, those who did soliton research showed that their equationswere accurate and would work. It was a fascinating dialogue between an individual researcherwho through he was right versus the management that disbelieved in the conclusions of hisresearch. The story isn't over yet, though. Perhaps because the medium is non-linear, we canonly analyze certain pulses. They are now working on ways to pull the solitons away from thenoise generated by amplifiers. The non-linear signal can thus be persuaded to do certain thingsindependent of the noise.Transmission is the furnace that is heating up the entire field, but 99% of the peopleworking in communications don't care about transmission. Lucky remarked that they seetransmission as a commodity.According to Lucky, the big push in communications is to get fibers into the homes but thisstill is not happening on a widespread basis. There are all sorts of communications companies thatwant to invade the home (e.g. CATV, satellite, IATV, etc.). In terms of the research to support thispush, Lucky claimed that the research is limited because, basically, the problems associated withgetting fibers into the home are political and economic in nature. But there should be moreresearch done in the area of service - that is, concerning what people want if they do let fiber intotheir homes.Within the last year or two, a new philosophy has taken shape that, in Lucky's view, willtransform the network from circuit switch to packet switch. The idea is that of bandwidth ondemand, which will accommodate all sorts of uses and will cohabit the communicationsinfrastructure. The question is one of whether or not it is feasible that one single network will beable to do all of these things.Lucky hypothesized that we may not be able to integrate the network but he explained thatAT&T's answer to the network integration problem is ATM, or Asynchronous Transfer Mode. WithATM, all the information will be carried in the network in 48 byte packages and with 155megabytes per second as the basic data rate. This is a connection-oriented system. The virtualpacket and the virtual route will be prearranged. ATM represents a new kind of architecturalphilosophy for the network. While Lucky observed that there is a lot of debate about it -concerning whether the packets are too small or too big - AT&T is moving forward on ATMbecause it seems economical, and people are building the ATM switches. The ATM switch is asingle size cell and this is what makes it, potentially, so economical.The ATM switch transforms the network's problems from ones of signalling infrastructureand circuitry to ones of congestion, traffic control, pricing, etc. These are new problems for thecommunications system. Lucky also discussed the fact that, while the biggest single expense incommunications today is billing, billing may become an even greater problem with the ATMsystems. The cost of billing exceeds all the gains made by technological advances, so pricingclearly is a critical policy matter.In doing the processing-intensive switching of the future, many propose that doing it bymeans of an optical computer is the best path to choose. Lucky confirmed that the PublicRelations people at AT&T announced that AT&T would have an optical switch by 1995, but hestressed that the engineering people are unsure about his possibility. Currently, AT&T has noarchitecture to use the optical computer capability, and Lucky was not sanguine about the use ofoptics. In his view, the ATM switch is the prototype processing job of the future. AT&T tried tobuild an ATM switch using optics, but the electronics people argued that their method is cheaper.The economics argument won out. You can buy approximately one million electronic transistorsfor $1 and only one lazer for $1000. The optics people attempt to parallel everything. Theelectronics people, because they have cheap transistors, can afford to actually parallel everything.So, the electronics view is winning out thus far, despite the intrinsic abilities of optics.Lucky briefly discussed what he considers to be one of the major, yet under-studied, issuesin communications today: the sociological problems associated with steadily expandingcommunications capabilities. We are headed to a time in the not-too-distant future where we willhave wrist-watch telephones and other such technologies. But these sorts of communicationscapabilities will make the act of communications a very personal one, and access is a two-edgedsword. We all want to be in touch with everyone, but we want restricted access to us. It doesn'tnecessarily work that way - the network must go both ways - and, according to Lucky, not enoughthought has been given to the sociological dimensions of communications.Image communications will bring to the fore this whole issue of access and two-waynetworking. Lucky noted that AT&T is going to offer picture phones in the very near future.These picture phones will be cheap video-technology, with cheap bandwidth and powerfulcompression, and will contribute to the steady advancements being made in the are of imagecommunications. Despite the early failure of the PicturePhone (due to their high cost, poortechnology, and social and interface problems), these new picture phones are in demand.. AT&Tenvisions a small market for the new picture phones, but this new model is merely a stepping stoneto more sophisticated image communications.Lucky envisions that society will continue to move towards increasing use of messagingsystems, including electronic mail, facsimile, and other messaging services. We will have to learnto use messaging more pervasively because the real time possibility of talking to a live person in alive call is steadily diminishing. AT&T is encouraging multi-media conferencing - it offers ashared visual space and will offer shared computer applications, shared pictures of the participants,shared documents, etc. Multi-media is an important concept in that it represents the model ofcommunications for the future: an electronic room paradigm whose unique properties must beemulated. This paradigm offers a gathering place for people and for resources, it offers a sharedspace with entry and exit, it implies notions of conductivity and of what the object ofcommunications should be, and it has persistence. Building-in such properties to the infrastructureand the software will determine what the phone call of the future will be, as well as what themodel for communications will be.In conclusion, Lucky stressed that we are witnessing the emergence of a rich, newcommunications infrastructure supporting high bandwidth with fast-speed switching anddistribution capabilities. This infrastructure is itself in the process of changing very rapidly, asevidenced by the fact that AT&T has built an entirely new network since its divestiture in 1984.All sorts of new transmission capabilities and services are upon us, including wirelesscommunications and message servicing, to recall just a couple of the examples mentioned in thetalk. Lucky also noted that Internet is growing extraordinarily rapidly and is totally out of thecontrol over either corporate or government regulators. Internet is growing at a monthly rate of15%, versus the AT&T voice system which is growing at a yearly rate of 6%.Question and AnswerThe first questioner asked Lucky to elaborate on the potential growth in use of ISDN.Lucky explained that ISND is 64 kilobyte per second service. What is happening is that theworld may sweep past 64 kbs ISDN and towards broad band ISDN and ATM. ISDN is happeningtoo slowly. ISDN doesn't have a single application that carries it, and that's its problem. This isthe case with most of the new technologies - they work very well, but it will be an economic fight,determined by regulatory and political constraints, that decides what catches on in the market.__The second questioner asked when videophones will become available.Lucky said that AT&T has planned a very small market (approximately 50,000 unites) forthe videophone. There are a lot of orders already made, but some people claim that these ordersare mainly from the catalog companies. AT&T sees these videophone orders as a sort of toymarket, for the rich and as "grandparents' presents," with the real market yet to come. The bigmarket for video phones will use wide bandwidth of every quality (from HDTV to bad quality).Lucky noted his skepticism concerning how the current videophone will take off. The videophoneraises the issue of the nature of human communications and of where the impact derives from inthe communications process (is it in the speech or in the picture). A wealth of psychologicalstudies has yet to resolve to this question of where the information lies. Lucky argued that thebulk of the information is in the speech. He predicted that business use of the videophoneprobably will be quite slim. He emphasized that the pace of understanding human communicationsis slow. But he noted that we are rapidly changing the way we communicate and the way that wework. Seventy percent of the communications across the ocean occur by fax. People aren'ttalking by phone anymore.The next questioner asked why we don't see more flat rate services.Lucky responded that we will soon see a rapid growth in flat rate services. That is one ofthe interesting things about Internet. You can use as much as you want, but access come bypaying for a given bandwidth.The next questioner asked why Lucky claimed that applications of the various newtechnologies will depend on economic battles, if most of the cost in communications services liesin the billing rather than in the technologies.Lucky emphasized that the battles will not be economic in the market sense of the word,but will be regulatory and political. This is more than economics, which doesn't necessarily implythe costs of the system, but also implies a concern for how deep your pockets are. And today,you have co-existing but different forms of technology that cost the same thing in terms of service.This implies that the cost of technology is not the determining factor but that the people costs arewhat determine the price of the communications service.The next questioner asked why Lucky does not think that fiber will get into the home on abroader level.Lucky responded that the world is ruled by rational economic and technological argumentsand, on these bases, fiber can not win._ -- ~----

The changing world of communications

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The changing world of communications

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