Milestone-Proposal:First Real-Time Speech Communication on Packet Networks
This Proposal has been approved, and is now a Milestone Nomination
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Is the achievement you are proposing more than 25 years old?
Is the achievement you are proposing within IEEE’s fields of interest? (e.g. “the theory and practice of electrical, electronics, communications and computer engineering, as well as computer science, the allied branches of engineering and the related arts and sciences” – from the IEEE Constitution)
Did the achievement provide a meaningful benefit for humanity?
Was it of at least regional importance?
Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)?
Has an IEEE Organizational Unit agreed to arrange the dedication ceremony?
Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated?
Has the owner of the site agreed to have it designated as an Electrical Engineering Milestone? Yes
Year or range of years in which the achievement occurred:
- 1974: First real-time two-way packet speech, on ARPAnet – MITLL (Lexington, MA) and USC/ISI (Marina del Rey, CA) in August with 9.6 kbps CVSD (Continuously Variable Slope Delta Modulation); MITLL and Culler-Harrison (Goleta, CA) in December with 3.5 kbps LPC (Linear Predictive Coding) * 1976: First packet speech conferencing with 3.5 kbps LPC on ARPAnet among MITLL, CHI, USC/ISI * 1979: Real-time 2.4 kbps LPC conferencing using ARPAnet and Atlantic SATNET, among MITLL, USC/ISI, UCL (London), NDRE (Norway), BBN (Cambridge, MA) * 1982: Internet packet speech and conferencing including Wideband SATNET, Packet Radio Net. Local Area Ethernets, and telephone network interfaces – participants were MITLL, USC/ISI, and SRI
Title of the proposed milestone:
First Real-Time Speech Communication on Packet Networks
Plaque citation summarizing the achievement and its significance:
In what IEEE section(s) does it reside?
IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:
IEEE Organizational Unit(s) paying for milestone plaque(s):
IEEE Organizational Unit(s) arranging the dedication ceremony:
IEEE section(s) monitoring the plaque(s):
Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.
Street address(es) and GPS coordinates of the intended milestone plaque site(s):
MIT Lincoln Laboratory, Lexington, MA
Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.
Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need.
MIT Lincoln Laboratory conducted pioneering R&D and experiments in packet speech, collaborating with the other organizations noted above, including USC/ISI, SRI, CHI, BBN, and others. Lincoln was a direct participant in all the milestone packet speech experiments cited above, spanning 1974-1982. In addition, in 1971, Lincoln conducted the earliest packet speech related experiments on the ARPAnet; those experiments showed the feasibility of packet speech transmission; real-time 2-way communication over the ARPAnet between Lincoln and CHI and between Lincoln and USC/ISI followed in 1974.
Are the original buildings extant?
Details of the plaque mounting:
How is the site protected/secured, and in what ways is it accessible to the public?
MIT Lincoln Laboratory is a secure facility. The main entrance and lobby area is open to the public, and the Laboratory often opens its auditorium to outside events including Boston Section IEEE meetings, IEEE Life Fellow meetings, Science on Saturdays for K-12, and concerts. (Note: The Lincoln Laboratory auditorium hosts many IEEE meetings, and would be the site for a m ilestone ceremony should this proposal be accepted).
Who is the present owner of the site(s)?
Massachusetts Institute of Technology
A letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property:
A letter or email from the appropriate Section Chair supporting the Milestone application:
What is the historical significance of the work (its technological, scientific, or social importance)?
This pioneering work on speech in packet networks developed and demonstrated systems which were forerunners of the voice-over internet protocol (VoIP) systems that are now so widely in use. The real-time voice work included development of a new Network Voice Protocol (NVP), because the packet and reliability constraints of the available Transmission Control Protocol (TCP) implementation made it unsuitable for real-time communication. This protocol development was an immediate forerunner of the separation of TCP and IP, so that the real-time packet speech work played a large role in the development of the protocols, which are still in wide use today. The technology and protocols for real-time speech over packet networks also enabled other real-time internet applications such as packet video, so that now systems like Skype enable real-time voice and video at home and in offices for extremely large number of people; this is a capability of significant social impact. References Clifford J. Weinstein and James W. Forgie, “Experience with speech communication in packet networks,” IEEE Journal on Selected Areas in Communications, Vol. 1, No. 6, December 1983. Dan Cohen, “RFC0741: Specifications for the Network Voice Protocol,” 22 Nov 1977. Available at http://www.ietf.org/rfc/rfc741.txt. Robert M. Gray, "The 1974 origins of VoIP," IEEE Signal Processing Magazine, Vol. 22, July 2005, pp. 87-90.
Robert M. Gray, Linear Predictive Coding and the Internet Protocol, NOW Publishers, 2010
What obstacles (technical, political, geographic) needed to be overcome?
The network protocols did not support real-time speech, so new protocols had to be developed. The narrowband (2 – 5 kbps) digital vocoder algorithms were needed due to the limited ARPAnet link rates; these algorithms did not run in real time, so they had to be modified and adapted to run on the new DSP systems which were just emerging.
Interoperability needed to be established among separate implementations of speech algorithms and protocols running at different sites, on different host computers and DSPs, over different types of networks, and with geographic separation across the US and between US and Europe.
What features set this work apart from similar achievements?
This work combined major developments in multiple areas, including the first real-time implementations of narrowband LPC speech coding on digital signal processors, network protocols to enable real-time packet delivery, strategies for reconstituting speech, techniques for reconstitution of speech from packets arriving at non-uniform intervals, packet speech conferencing techniques, and interoperation over different types of packet networks (landline, Ethernet, satellite, radio). Another feature was the outstanding collaboration among organizations and across technology areas. Finally, the long-term impact is a major feature which sets this work apart, as evidenced by the wide use of VoIP and related application such as packet video.
References to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or citations to pages in scholarly books. At least one of the references must be from a scholarly book or journal article.
Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to firstname.lastname@example.org. Please see the Milestone Program Guidelines for more information.