Computer Science Laboratory
UCB-SU-Slides.tioga, Title November 9, 1983
Acknowledgements
Voice Project
Dan Swinehart
Severo Ornstein
Cedar Project
. . .
Dorado Project
. . .
UCB-SU-Slides.tioga, Acknowledgements November 9, 1983
OVERVIEW
Main points:
Voice and the office, not technology
but . . . Ethernet Voice Works
Motivation
Architecture
Ethernet Transmission
System Components
Etherphone
Slide Show
UCB-SU-Slides.tioga, Overview November 9, 1983
Show color transparency here
(I Hate Phone)
UCB-SU-Slides.tioga, Hate telephone pix November 9, 1983
Issues -- Caller
Addressing
Responsiveness
Annoying or Unnerving Treatment
Issues -- Callee
Missed Calls
Intrusion
Value Added: Broadcasts
Value Added: Background Calls
UCB-SU-Slides.tioga, Issues -- Caller November 9, 1983
Issues -- Transcription
Messages
Editing
Annotation
Synthesized Voice
(Speech recognition)
Issues -- Noises
Attention
Progress
Games
UCB-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 as Data
Voice annotated documents
Interactive integrated voice
Better human assisted call handling
Voice messages
UCB-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
Fill in subject/addresses
Speak/type message body
Edit voice (using visual clues)
Deliver as usual
UCB-SU-Slides.tioga, User Functions November 9, 1983
Show cartoons here
Advanced call placement
Advanced call forwarding
UCB-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
UCB-SU-Slides.tioga, User Model November 9, 1983
Basic Capabilities
Terminal equipment
Voice input/output
Buttons, lights, etc.
Transmission
Real-time requirements
Control & status
Management of connections
Voice composition and editing
Structuring and handling voice
Voice filing
Real-time requirements
Data bases
White pages etc.
UCB-SU-Slides.tioga, Basic Capabilities November 9, 1983
Architecture
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.
Components:
1. Etherphone -- Voice I/O
2. Etherphone Server -- System control
3. Voice File Server -- real-time requirements
4. POTS gateway -- to outside telephones
UCB-SU-Slides.tioga, Architecture November 9, 1983
Show system block diagram here
UCB-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
Conservative design!
64 Kbps voice encoding, industry standard
50% net utilization for ~0 collisions -- 5 Mbps
50 packets/second for low delay
50% control overhead -- 90 Kbps per voice stream
55 one-way voice streams or 28 "trunks"
TASI advantage = 1.6 -- 45 conversations
20% of telephones in use -- 225 subscribers
UCB-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 inexpensive -- 300 Mb = 9.5 hours
Echos
Outside and speakerphone calls may need echo suppression or cancellation
One-chip digital echo cancellers exist
Capacity limits
Scaling to multiple networks with very fast gateways?
Traffic engineering
Sharing with data traffic has problems
Economics
Ethernet voice is within range of PBX costs.
UCB-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 switching system
Access to voice data
UCB-SU-Slides.tioga, Reminder November 9, 1983
Telephone Server Responsibilities
Voice connections
Telephone user interface
Coordination
Data base services
Etherphone assignments
Directory assistance
UCB-SU-Slides.tioga, Server responsibilities November 9, 1983
Voice File Server Responsibilities
Record voice files
Play them back
Directory services
Backup
Houskeeping
UCB-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 . . .
UCB-SU-Slides.tioga, Workstation responsibilities November 9, 1983
Etherphone
Simple, until you look at the details!
Responsibilities
Voice I/O
Ethernet
Hardware
"Digital" Board -- two 8088 microprocessors
"Analog" board -- crossbar switch plus interfaces
Software
Small operating system
Communications
Applications
Real-time
UCB-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, process scheduling, other "glue"
UCB-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
UCB-SU-Slides.tioga, Slave CPU software November 9, 1983
Digital Hardware
Main Processor
8 MHz 8088
8 K bytes EPROM
DES Encryption
Ethernet
6 Timer channels
2 RS-232 channels
Parallel IO
Shared Memory -- 64 K bytes
Slave CPU
8 MHz 8088
8 K bytes EPROM
2 K bytes local RAM
UCB-SU-Slides.tioga, Digital hardware November 9, 1983
Analog Hardware
8 by 8 Analog crossbar switch
Interfaces
Two Codec / Filter chip sets (D/A and A/D)
Speaker amplifier
Microphone preamp
Telephone set interface
Telephone line interface (with 2-4 wire conversion)
Two line level inputs and outputs
DTMF (touch tone) decoder
Relays for power fail line transfer
UCB-SU-Slides.tioga, Analog hardware November 9, 1983
Status
8 Users in place
~50 Etherphones in production
to be installed by December
Control Server running
Voice File Server running
Some workstation software
Personal directory
Whitepages access to company phone book
Voice recording and playback
Preliminary interface to mail system
UCB-SU-Slides.tioga, Status November 9, 1983