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Sorry, ARRL 6th Computer Networking Conference 1987 is no longer available
This proceeding is available on CD-ROM
- Location:
- Redondo Beach, California
- Coordinators:
- Harold Price, NK6K
Walter A. Linstruth, WA6JPR
Paul L. Rinaldo, W4RI - Hosted by:
- TRW ARC
Southern California Digital Communications Council
Abstracts:
6th Computer Networking Conference
August 19, 1987
- Estelle: A Formal Description Technique for Communication Protocols
by Michel Barbeau, VE2BPM - Introduction:
Estelle is a FDT developed by ISO (International
Standard Organization). It is based on an Extended Finite State Machine model (EFSM). A finite state machine is a simple abstract device which has states and transitions labelled by input and output symbols. A state transition table is one of the possible ways to represellt textually a FSM. FSM's are frequently used to model the control flow of systems. Communication software, such as data link protocols, have usually a compliment that can be represented by FSM's. As an example
see the state transition tables of the AX.25 link-layer
protocol in appendix D. Protocols have also data
flow aspects involving interaction parameters, different
kinds of variables and data operations. The data flow
aspects are hard to represent using only FSM's. Estelle
extend the idea of FSM in a sense that variables, actions and predicates, operating on those variables, are added to this basic model. The syntax of Estelle has
been defined from the syntax of the programming language Pascal. New elements have been added in order to make easier the definition of aspects particular to
comnlunication protocols. In Estelle can be expressed
both the control flow aspect, using FSM's, and the data
flou aspect, using Pascal's elements, of a comlllunication
protocol. Protocol specifications written in the formal
language Estelle are said formal with respect to informal specifications written in a natural language such as English.
- OSI: A Plan Comes Together
by J. Gordon Beattie, Jr., N2DSY, Thomas A. Moulton, W2VY - Abstract:
This paper will provlde an overvlew of
the current state of services avilable
on the Amateur Packet Radio and then
offer solutions to the problems and
limitations found. This will include
an outline of a communications
architecture for distributed computer
systems using the Open Systems
Interconnection Reference Model
(OSI-RM). We will also provlde a
description of systems required to
support the data transport and
application needs of the Amateur Packet
Network user. These OSI-based systems
have been designed to inter-operate
with each other and with other systems
not part of the Amateur Packet Network.
This architecturally consistent
approach addresses the operatlonal
Objectives of Services, Managibility,
and Performance. It has the further
advantage of world-wide acceptance.
- A High Performance Packet Switch
by Mike Brock, WB6HHV, Franklin Antonio, N6NKF, Tom Lafluer, KA6IQA - Abstract:
This paper describes the PS-186TM, a high-speed multiport packet switch designed to support data rates up to 1 Mbit/second. It can also be used as a local packet node, mail system, or a gateway to other networks. It operates on 2.1 Watts of power. The PS-186 was designed by members of the San Diego Packet Radio Association (SANDPAC).
- The KISS TNC: A Simple Host-to-TNC Communications Protocol
by Mike Chepponis, K3MC, Phil Karn, KA9Q - Abstract:
The KISS TNC provides direct computer to TNC communication using a simple
protocol described here. Many TNCs now implement it, including the TAPR TNC-1
and TNC-2 (and their clones), the venerable VADCG TNC, the AEA PK-232/PK-87
and all TNCs in the Kantronics line. KISS has quickly become the protocol of choice
for TCP/IP operation and multi-connect BBS software.
- Digital Signaling Processing and Amateur Radio
by Dr. Thomas A. Clark, W3IWI, Dr. Robert W. McGwier, N4HY - Introduction:
Tom calls the necessary ingredient magic, and Paul
Rinaldo, W4RI, calls the necessary ingredient an incubator[1][2]. Whatever you choose to call it, we have lacked the necessary ingredient in ham radio to broadly apply the collection of techniques known as digital signal processing (DSP). The magic in the amateur satellite service has been provided by AMSAT[3]. In the digital communications modes, the incubator was supplied by TAPR[4].
AMSAT and TAPR have joined to support an incubator project to achieve the broad use of DSP in amateur radio.
- DSP is a field which has its roots in the mathematics of Newton, Gauss, and Fourier. These people lived hundreds of years ago. Why are we stessing these ancient techniques? Primarily because a much newer technological revolution has taken place which allows us to apply DSP techniques in increasingly complex combinations. Of course, we are talking about computers in general and microprocessors in particular. Until the very recent past, even microprocessor elements were primarily used in proprietary special purpose devices with specific tasks in mind. For example, there are DSP chip sets manufactured by several companies that are totally dedicated to being Bel-212 modems for phone line use. (...)
- DSP is a field which has its roots in the mathematics of Newton, Gauss, and Fourier. These people lived hundreds of years ago. Why are we stessing these ancient techniques? Primarily because a much newer technological revolution has taken place which allows us to apply DSP techniques in increasingly complex combinations. Of course, we are talking about computers in general and microprocessors in particular. Until the very recent past, even microprocessor elements were primarily used in proprietary special purpose devices with specific tasks in mind. For example, there are DSP chip sets manufactured by several companies that are totally dedicated to being Bel-212 modems for phone line use. (...)
- A Duplex Packet Radio Repeater Approach to Layer One Efficiency
by Robert Finch, N6CXB, Scott Avent, N6BGW - Purpose:
In January, 1984, South Coast Radio Relay, a
Southern California Amateur Radio group
specif ically chartered to experiment in state of
the art message handling techniques, modified its
two meter duplex voice repeater in Glendale,
California, for full time digital communications.
This operation has remained on the air since that
time, under both the original callsign; N6TD/R and
the since adopted call; N6GPP/R. This operation
has undergone some specif ic changes in the past
several years, but the basic user interface has
essentially remained the same. This paper will
examine the basic operational characteristics
employed at the repeater site, specific to the
repeater itself, and will aid the reader in
duplicating the methods used to achieve the
promise inherent in local area duplex packet
operation.
- Packet Radio Developments over the Last Year
by Terry Fox, WB4JFI - Abstract:
Over the last year AMRAD has been continuing
it's work on the deveiopment of packet switc
hardware and software. Our progress has been
slower than we had hoped, due to our interests in
other projects, such as spread spectrum. The
hardware portion of our packet switch has made
better progress than the software. Over the next
vear we hope to make more progress in software
development. What follows is a brief description
of what I think have been some significant
advances over the last year, along with some of my
current thinking in packet network development.
- Thoughts on the Issues of Address Resolution and Routing in
Amateur Packet Radio TCP/IP Networks
by Bdale Garbee, N3EUA - Abstract:
The current KA9Q software includes a technique for automatic address resolution,
but does not include automatic routing features. The difference between routing and
address resolution is explained, and several concerns for on-air automatic routing algo-
rithm implementations are mentioned.
- The Design of a Mail System for the KA9Q Internet Protocol
by Bdale Garbee, N3EUA, Gerard van der Grinten, PA0GRI - Abstract:
The current implementation of the mail manipulation system that has been built
by N3EUA and PA0GRl for the KA9Q Internet Protocol Package is described briefly. A
proposal for the next generation of network mail handling for the KA9Q Internet
environment is described. An important change in the way we can and should think
about electronic mail in the amateur packet radio world is discussed.
- A Bit Error Rate Tester for Testing Digital Links
by Steve Goode, K9NG - Abstract:
With the availability of several
link-level protocols such as TEXNET and
NETROM, many packet groups are installing
inter-city digital links. As AEh and GLB
begin shipping their digital radios and
the 56 kbps radio demonstrated at the
Dayton Hamfest becomes available, more
Amateurs will require a method of testing
the performance of these digital radios.
This paper presents a test circuit which
can be used during initial installation of
a digital link to enable the installers to
fine tune the radio on site. This circuit
temporarily replaces the TNC or control
computer and allows the installers to
listen to the data link to determine how
well it is performing. It can also be
used for bench testing digital radios and
modems.
-
A 56 Kilobaud RF Modem
by Dale A. Heatherington, WA4DSY - Abstract:
This paper describes a 56 kilobaud
synchronous RF modem with a 70 kHz
bandwidth. The modulation is bandwidth
limited MSK generated by a digital state
machine driving two digital-to-analog
converters, and two double balanced
modulators. The carrier phase is shifted
plus or minus 90 degrees for each bit.
Demodulation is accomplished with a
standard quadrature detector chip but
various coherent methods can be used for
operation at lower signal to noise
ratios. The design is relatively simple
and easily reproduced.
- Reusable IP Addresses in a Dynamic Network
by Robert B. Hoffman, N3CVL - Abstract:
The topology of amateur packet radio networks changes rapidly due to the frequent addition of new stations, shutting down of old stations, and changing location of others. This paper presents a method for managing IP address assignments within such a network.
- Software Design Issues for the PS-186 Advanced Packet Network
Controller
by Brian Kantor, WB6CYT - Abstract:
A fast network for amateur radio requires sophisticated node controllers to work well. Key to the performance of advanced node controller hardware is the design of the on-board software. Issues of highly-efficient device drivers, protocol encapsulation, and process management must be addressed
to ensure acceptable pefformance with limited memory and affordable hardware. PS-186 hardware design issues are discussed in a companion paper by Michael Brock, Franklin Antonio, and Tom LaFleur.
- Another Look at Authentication
by Phil Karn, KA9Q - Abstract:
A simple and effective technique for packet authentication in a datagram network is described that is based on the Data Encryption Standard (DES). In accordance with FCC rules, the actual data is not encrypted; rather DES is used to compute a special "cipher checksum" that is appended to the unencrypted user data before transmission. The recipient recomputes the cipher checksum and compares it against the incoming value, thereby detecting bogus or altered packets. This technique is potentially useful in a wide variety of amateur radio applications in addition to packet radio; for example, it could provide a secure control link for a remote repeater site.
- A High Performance, Collision-Free Packet Radio Network
by Phil Karn, KA9Q - Abstract:
For the past several years, those discussing "level 3 networking" have made much of the performance gains to be had through hop-by-hop acknowledgements. In this paper I will show that, while sometimes helpful, hop-by-hop ACKing is not the panacea it is generally perceived to be. Only fundamental changes in the way we allocate and use frequencies will really fix the problem.
- The KA9Q Internet (TCP/IP) Package: A Progress Report
by Phil Karn, KA9Q - Abstract:
For over two years, the author has led the development of C-language software implementing the ARPA Internet protocol suite (commonly called "TCP/IP"). Intended for amateur radio use, the software was originally written on and for the IBM PC and its clones running MS-DOS. However, the use of a de-facto industry standard protocol set has resulted in considerable interest in and contributions to the effort by non-amateurs as well. The software has been "ported" to several different computers and is enjoying increasing use in both conventional Local Area Network (LAN) environments as well as amateur packet radio. This paper describes the considerable progress this effort has made, and reflects on the choice of TCP/IP now that significant on-air experience has been gained.
- Approach for Digital Transmission of Pictures
by Thomas Kieselbach, DL2MDE - Abstract:
"A picture 15 worth a 1000 words" is a saying
confirmed daily. It should be remembered
that transmission of picture signals began in
the early days of radio. The individual
techniques were adapted to the specific
needs at the time, thereby resulting in
diverse systems each being optimized in
accordance with the requirements and the
method of transmission used.
- RUDAK - The Packet Radio Experiment On-Board OSCAR P3C
by Hans peter Kuhlen, DKlYQ - Abstract:
Nearly two years ago, AMSAT-DL initially
published the outcome of its first RUDAK system
design meeting at the 4th ARRL Conference in San
Francisco [1]. At this time we wish to present the
current status of the flight ready hardware and the
completed and tested ground station equipment.
This paper will briefly present the objectives
of the RUDAK experiment and the performance
achieved by the RUDAK transponder on-board
OSCAR Phase 3 C. It will also include a description
of a recommended user terminal which can be
utilized for all satellite operating modes via OSCAR
Phase 3 C, FUJI OSCAR 12, as well as for terrestrial
packet radio.
- Improving Shared Channel Access Techniques for Amateur Packet
Radio
by Brian Lloyd, WB6RQN - Abstract:
Amateur Packet Radio has come of age.
There are now many packet radio users in the
Amateur community, well over 20,000 at this
point. In the "olden days" when there were
few users on a channel at any one time the
need for effective channel access techniques
was much less than it is now. The problems all
result in the same symptoms: poor throughput
and lost connections.
- The Noise Performance of Several Data Demodulators
by Hugo Lorente, LU4DXT - Abstract:
This paper shows the noise performance of several data demodulators currently being used in pac~et radio. The bit error rate (BER) in presence of white Gaussian noise was measured on the followlng demodulators: 1) JAS-l PSg demodulator 2) Discriminator 3) AMD 7910 modem 4) Differential detector 5) G3RUH PSK demodulator 6) EXAR 2211 demodulator. The noise performance of this
demodulators is graphically presented here and a brief description of the test gear
used in these measurements is given in appendixes A and B.
- Overview of the TEXNET datagram protocol
by T.C. McDermott, N5EG - Abstract:
This article is an overview of the
TEXNET datagram network protocol. It is
not intended as a specification. It deals
i with the protocol within the network
(intra-network). It does not deal with
layer 3 protocol issues between the user
and the network (inter-network).
- CSMA Multihop Networks: Throughput Analysis by Dr. Bob W. McGwier, N4HY
- Abstract:
Amateur Radio uses packet radio in a broadcast mode and typically uses omnidirectional antennas for transmission. If the two ends of the data transfer are not within communication range, we will use a digipeater. The protocol we use for medium access control is carrier sensed
multiple access (CSMA) protocol. Under CSMA, a terminal will not transmit if it hears a transmission in its neighborhood. In a multihop environment (digipeater) such as ours, CSMA is subject to "hidden transmitter" interference. This is w hen two or more transmitters outside hearing range of each other key up at the same time and interfere with one or more recipients of the two or more packets being simultaneously transmitted. We call this a collision. We could almost completely eliminate this problem with busy tone multiple access (BTMA) protocol. The "almost completely" in the previous sentence is caused by the finite speed of light and the response time of the receiver bringing up the busy tone. BTMA has implicit in its nature seperate transmit and receive operation. Several papers have appeared analyzing throughput in CSMA packet radio networks. The best papers and the most useful (not always the same) are by Boorstyn and Kershenbaum and we include one of their papers as our only reference as it contains the most complete set of references and is the basis for the work described here. They have introduced a
continuous time Markov Chain model which lends itself to numerical techniques for finding the steady state response of moderate sized (100-200 nodes) networks. This type of model allows for dependencies between non-adjacent nodes to be modeled and analyzed. The primary purpose of this
paper is to introduce these ideas to the amateur radio literature, to supply some rigor to Clark's "But Wait There's More" treatise, and hopefully give one more nudge to do something about the problem.
- DSP Modems: It's Only Software
by Dr. Robert W. McGwier, N4HY - Abstract:
Are you as tired of buying new modems as I am ? There is an alternative and I think a superior one in several regards. From the title, and the joint paper with Tom W3IWI, it should be obvious that we are talking about doing modems on DSP engines. Using a single chip processor as the basic building block, a low cost, high speed modem can be programmed to operate through unconditioned radios. If you want a different modem ten minutes later, you just change the software driving the chip. The primary advantages stated more explicitly are (1) a single piece of hardware can make and demodulate the phase or frequency modulated synchronous signal of your choice, and (2) the software can do very effective adaptive equalization to ameliorate the bad things the radio (filtering) is doing to your data signal.
- HF Packet: Where do we go from here?
by Barry D. McLarnon, VE3JF - Introduction:
Packet radio on the HF bands is alive
and well, and is steadily gaining in
popularity. The HF links which have been
established between widespread packet
bulletin board systems have become a
workhorse in moving error-free traffic
beyond the limits of the VHF/UHF packet
networks. These links will, of course,
never be capable of handling huge volumes
of traffic, like megabyte files: the
bandwidth simply isn't sufficient.
Satellites and expanded UHF/microwave
links must be developed to meet these
requirements; but it is probably safe to
say that HF will always have a role to
play in amateur data communications, both
as a back-up to these higher-capacity (but
more vulnerable to failure) systems, and
for extending the network into remote
areas where setting up a satellite station
may not be feasible.
- FINDER--The Family Information Database for Emergency Responses
by W.E. Moerner, WN6I, Sharon Moerner, N6MWD, David Palmer, N6KL - Abstract:
FINDER is a new packet radio database application
utilizing multiple connect and a specific syntax to allow
emergency response personnel to ascertain the status of
their family members during a disaster. This paper
describes the history, scope, operation, and design
philosophy of the FINDER system.
- Dial "0"; for Operator: Message Routing in the Amateur Packet Network
by Thomas A. Moulton, W2VY - Abstract:
Over the past several years a variety
of message routing systems have been
used. The tendency has been to not
step back from the problems and address
fundamental lssues. This pager will
attempt to achieve that elusive goal
and outline a routing system which will
allow the Amateur community to operate
with efficiency and ease.
- Packet Radio and IP for the Unix Operating System
by Clifford Neuman, NlDMM - Abstract:
Many services are currently available on the ARPA Internet that would be of
interest to amateur packet radio users. The ARPA Internet connects universities and
other organizations around the world that speak TCP/IP. One advantage of running
TCP/IP on packet radio is the ability to access these services, and to interconnect with
other systems that are part of the internet This paper describes the implementation of
AX.25 as a link layer protocol for the Unix operating system and the use of this system as
an IP gateway between our local amateur packet radio network and our department's
ethernet at the University of Washington, which in turn provides access to the entire
Internet The potential role of such a system for amateur packet radio is discussed, and a
mechanism to allow users that don't have the resources to run TCP/IP themselves to
access such services is described.
- Pacgram Messaging Protocol for Packet Networks
by Jay Nugent, WB8TKL - Abstract:
In the 5th Computer Networking Conference
papers David Cheek, WA5MWD, included in his
submission an attatchment containing the Pacgram
Protocol Definition. In this paper you will find
the latest revision of that Pacgram Protocol
Definition with a synopsis of Pacgram's creation,
where it is at now, and where I hope it will go in
the amateur packet radio community.
- Performance Monitoring or I Wanna Fix it, Is it Broke?
by Skip Hansen, WB6YMH, Harold Price, NK6K - Abstract:
Much of the performance information on Amateur Packet Radio is anecdotal and
ephemeral; a subjective and non-detailed account usually limited to a gross statement of
"goodness" or "badness", which is neither well documented nor long remembered. While
there are several papers which describe the expected performance of CSMA-type systems,
there is little actual data about the live amateur packet system. The authors discuss the need for accumulating performance data and describe work in progress to supply performance measurement software using a C program and a TNC with KISS software.
- ASC X12.A-1985: Draft Proposed American National Standard for
Electronic Business Data Interchange Amateur Radio Message Transaction
Set
by Jack Sanders, NC4E - Abstract:
This standard contains the format and data content
of the Amateur Radio Message Transaction Set for
use within an Electronic Business Data Interchange
(EBDI) environment. The ASC X12 family of Electronic Business Data
Interchange standards are based on
interdependency. Several of the ASC X12 standards
define the data elements, data segments, control
structures and acknowledgments that relate to
transaction set standards. Availability of the
following standards is required in order to
interpret, understand, and use the ASC X12 family
of standards.
- Design Abstractions for Protocol Software
by Paul Taylor, VK3BLY - Abstract:
As amateur packet radio software becomes more complicated and software development environments improve, the use of high-level languages will become more favourable. A design approach for protocol software based on modules and Finite State Machines is described, which formalises the interface to IO devices, and extends the use of the protocol's State Machine model into the implementation stage. Its adoption should make implementations of Level 2 and 3 protocols quicker, easier, and more understandable.
