Computer Science Laboratory
SU-Slides.tioga, Title November 9, 1983
Acknowledgements
Voice Project
Dan Swinehart
Severo Ornstein
Consultants
Students
Cedar Project
Dorado Project
SU-Slides.tioga, Acknowledgements November 9, 1983
OVERVIEW
Main points:
Voice and the office, not technology
but . . . Ethernet Voice Works
Motivation
Architecture
Ethernet Transmission
Etherphone
Slide Show
SU-Slides.tioga, Overview November 9, 1983
Issues -- Caller
Addressing
Responsiveness
Annoying or Unnerving Treatment
Issues -- Callee
Missed Calls
Intrusion
Value Added: Broadcasts
Value Added: Background Calls
SU-Slides.tioga, Issues -- Caller November 9, 1983
Issues -- Transcription
Messages
Editing
Annotation
Synthesized Voice
(Speech recognition)
Issues -- Noises
Attention, Progress, Games
SU-Slides.tioga, Issues -- Transcription November 9, 1983
Two Areas of Exploration
Taming the Telephone
Better placement and receipt of calls
Better handling of special features
Better human assisted call handling
Voice messages
Voice annotated documents
Interactive integrated voice
Voice as Data
SU-Slides.tioga, Areas to Explore November 9, 1983
User Functions
Conventional Telephone
Call placement using Workstation
Mouse and directory
Intercom, Phone Call, Recorded message
Leaving Messages
Electronic Message Form
Speak/type message body
Edit voice (using visual clues)
SU-Slides.tioga, User Functions November 9, 1983
Show cartoons here
Advanced call placement
Advanced call forwarding
SU-Slides.tioga, Cartoons November 9, 1983
User Model
Workstation with control software
Handset, speakerphone
Instant Connections to:
Other voice-workstation terminals
Voice recording-playback facilities
Outside phone lines
Database access
Phone directory
User profiles
SU-Slides.tioga, User Model November 9, 1983
Basic Capabilities
Terminal equipment
Transmission
Control & status
Voice composition and editing
Voice filing
Data bases
SU-Slides.tioga, Basic Capabilities November 9, 1983
Architectural Principles
1. Ethernet for both control and data
2. Keep Etherphone simple
3. High availability and reliability
4. Use workstation when available for
wonderful user interface.
SU-Slides.tioga, Architectural Principles November 9, 1983
Architecture
Components:
1. Etherphone
2. Etherphone Server
3. Voice File Server
4. POTS gateway
SU-Slides.tioga, Architecture November 9, 1983
Show system block diagram here
SU-Slides.tioga, Block Diagram November 9, 1983
Ethernet Telephony
Bottom Line
10 Mbps Ethernet -- ~ 225 telephones
3 Mbps Ethernet -- ~ 100 telephones
1.5 Mbps Ethernet -- ~ 60 telephones
SU-Slides.tioga, Block Diagram November 9, 1983
More Ethernet Telephony
Conservative design!
64 Kbps voice encoding
50% net utilization for ~0 collisions
50 packets/second for low delay
50% overhead -- 90 Kbps
55 one-way voice streams or 28 "trunks"
TASI = 1.6 -- 45 conversations
20% in use -- 225 subscribers
SU-Slides.tioga, Ethernet telephony November 9, 1983
Transmission Issues
Compression
Silence detection a good idea?
State of the art ~ 8 Kbps, but . . .
Doesn't help Ethernet much, short packets are mostly overhead
Disks are cheap -- 300 Mb = 9.5 hours
Echos
Outside and speakerphone calls may need echo suppression or cancellation
One-chip digital echo cancellers exist
SU-Slides.tioga, Ethernet telephony November 9, 1983
More Transmission Issues
Capacity limits
Scaling to multiple networks with very fast gateways?
Traffic engineering
Sharing with data traffic has problems
Economics
Ethernet is within range of PBX costs.
SU-Slides.tioga, Transmission Issues November 9, 1983
Reminder
Our goals are:
Taming the telephone
Better integration of voice
Necessary capabilities are:
Fast control of telephone switching
Access to state of the telephone system
Access to voice data
SU-Slides.tioga, Reminder November 9, 1983
Telephone Server Responsibilities
Voice connections
Telephone user interface
Coordination
Data base services
Etherphone assignments
Directory assistance
SU-Slides.tioga, Server responsibilities November 9, 1983
Voice File Server Responsibilities
Record voice files
Play them back
Directory services
Backup
Houskeeping
SU-Slides.tioga, VFS responsibilities November 9, 1983
Workstation Responsibilities
User interface for telephony
Call status
White pages
User interface for voice filing
Mail system
User interface for . . .
SU-Slides.tioga, Workstation responsibilities November 9, 1983
Etherphone
Responsibilities: Voice and Ethernet I/O
Hardware
Digital - two 8088 microprocessors
Analog - crossbar switch plus interfaces
Software
Small operating system
Communications
Applications
Real-time
SU-Slides.tioga, Etherphone November 9, 1983
Main Processor Software
Remote Procedure Call (control)
Voice Protocol
Event Reporter
off hook, ringing, speakerphone switch,
touch tone buttons
Command interpreter
set up connection
generate dial tone, busy signal, . . .
Remote debugging, processes, "glue"
SU-Slides.tioga, Main CPU software November 9, 1983
Slave Processor Software
Voice IO driver
Silence detection
Echo suppression
Conference calls
Shared memory: "smart" DMA
Main loop runs in 125 microseconds
SU-Slides.tioga, Slave CPU software November 9, 1983
Digital Hardware
Main Processor
8 MHz 8088
8 K bytes EPROM
DES Encryption, Ethernet, Parallel IO
6 Timer channels, 2 RS-232 channels,
Shared Memory -- 64 K bytes
Slave CPU
8 MHz 8088
8 K bytes EPROM, 2 K bytes local RAM
SU-Slides.tioga, Digital hardware November 9, 1983
Analog Hardware
8 by 8 Analog crossbar switch
Interfaces
Two Codec / Filter chip sets
Microphone and Speaker amplifiers
Telephone set, Telephone line
Two line level inputs and outputs
DTMF (touch tone) decoder
Relays for power-fail line-transfer
SU-Slides.tioga, Analog hardware November 9, 1983
Status
12 Users in place
~60 Etherphones built
Control Server running
Voice File Server running
Some workstation software
Personal directory
Whitepages access to phone book
Voice recording and playback
Preliminary interface to mail system
SU-Slides.tioga, Status November 9, 1983