TELECOM Digest     Tue, 19 Jul 94 09:10:00 CDT    Volume 14 : Issue 327

Inside This Issue:                           Editor: Patrick A. Townson

    Call for Papers ICCC95 (yonsei@usenet.hana.nm.kr)
    Australian InfoCall Service Launched (John Hacking)
    Re: Recommendations For Lightning Protection (Fernando Lagrana)
    Re: Baud vs. bps (William H. Sohl)
    Re: Baud vs. bps (H. Peter Anvin)
    Re: Cellular Towers and Frequencies (Paul Robinson)
    Re: Cellular Towers and Frequencies (Bill Walker)
    Re: Bridge vs. Router Performance (Lars Poulsen)
    Re: IP Over Cable TV (Supak Lailert)

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----------------------------------------------------------------------

From: yonsei@usenet.hana.nm.kr (Yonsei News Adm)
Subject: Call For Papers ICCC95
Date: 19 Jul 1994 19:08:49 +1000
Organization: HANAnet Operating Centre(KTRC)


Following is the FIRST CALL FOR PAPER for ICCC'95 to be held in Seoul
Korea 1995.

                        CALL FOR PAPERS
                             ICCC '95 

       "Information Highways for a Smaller World & Better Living" 
     Seoul, Korea
                     August 21 - 24, 1995

The ICCC, the International Council for Computer Communication (ICCC),
founded in 1972, is an Affiliate Member of the International
Federation for Information Processing (IFIP).

Its purposes are to foster:   
  scientific research and the development of computer communication;
  progress in the evaluation of applications of computer communication 
  to educational, scientific, medical, economic, legal, cultural and 
  other peaceful purposes;
  study of the potential social and economic impacts of computer 
  communcation and of policies which influence those impacts. 

This 12th conference aims at providing a forum to exchange ideas,
discuss key issues and to present the late research results for
"Information Highways for a Smaller World & Better Living."  The main
program includes technical presentations, invited talks, tutorials,
and technical visits.

TOPICS :  Areas of interest include but are not limited to

  Strategies, Policies, and User      Wireless Communications
  Perspectives of Information         Intelligent Networks  
  Superhighways                       Personal Communications Systems
  Social and Economical Impacts       Broadband Communication
   of Information Superhighways       ATM Switching
  Computer Communication for          International Emergencies
   Developing Countries               Distance Learning
  Network Planning                    Optical Communications
  Security and Privacy in Computer    Multimedia Communication and its
   Communications                      Applications
  Evolution towards the High-Speed    High-Speed Protocols
   Networks including Frame Relay     Network Management  
   and SMDS                           Protocol Engineering     
  Packet Radio Technologies           Satellite Communications

SUBMISSION OF PAPERS  

Prospective authors should send five copies of a full paper to the
following address:

 ICCC'95
 Dr. Seon Jong Chung
 ICCC'95 Technical Program Chairman
 ETRI,  Yusong P.O.Box 106, Taejon, Korea, 305-606
 Tel: +82-42-860-8630
 Fax: +82-42-860-6465
 E-mail: iccc95@giant.etri.re.kr

The manuscript should not exceed 4000 words in length and should
include author's name, affiliation, and addresses(telephone, e-mail,
fax), and 150-200 words abstracts in the title page. Also, authors are
encouraged to send a Postscript version of their full paper to the
Technical Program Committee Chairman by e-mail iccc95@giant.etri.re.kr

                 |-------------------------------|
                 |  Important Dates              |
                 |    Submission of Paper        |
                 |      February 1st, 1995       |
                 |    Notification of Acceptance |
                 |      May 1st, 1995            |
                 |    Camera-ready Papers        |
                 |      June 15th, 1995          |
                 |-------------------------------|

Sponsored by
The International Council for Computer Communication

Hosted by
Electronics and Telecommunications Research Institute
Korea Information Science Society

Under the Patronage of
Ministry of Communication, The Republic of Korea

Conference Governor                          
Ronald P.Uhlig, Northern Telecom, U.S.A.
            
Conference Organizing Committee
Chair : Chongsun Hwang, KISS, Korea
Co-Chair : Seungtaik Yang, ETRI, Korea

Local Arrangement 
Dongho Lee, Kwangwoon Unvi., Korea

Publication 
Keosang Lee, Dacom, Korea
    
Publicity
Jaiyong Lee, Yon-Sei Univ., Korea

Registration 
Samyoung Suh, NCA, Korea

Treasurer 
Seungkyu Park, Ajou Univ., Korea

Tutorial 
Sunshin An, Korea Univ., Korea

Social Program 
Nosik Kim, KTRC, Korea

Secretariate 
Yanghee Choi, SNU, Korea
Jinpyo Hong, ETRI, Korea

Technical Program 
Chair : Seonjong Chung, ETRI, Korea
Co-Chairs : Serge Fdida, MASI, France
     Nicholas Georganas, Univ. of Otawa, Canada
     Roger Needham, Univ. of Cambridge, U.K.
     Otto Spaniol, Aachen Tech. Univ., Germany
     Hideyoshi Tominaga, Waseda Univ., Japan
     Pramode Verma, AT&T, U.S.A.

Members :   Byungchul Shin, KAIST, Korea
      Yongjin Park, Hanyang Univ., Korea
     Donggyoo Kim, Ajou Univ., Korea
     Kwangsue Chung, Kwangwoon Univ., Korea
     Daeyoung Kim, Cheoungnam National Univ., Korea
     Ilyoung Chung, ETRI, Korea
     Chimoon Han, ETRI, Korea
     Woojik Chon, ETRI, Korea
     Hoon Choi, ETRI, Korea
     Tadao Saito, Tokyo Univ., Japan
            Tahahiko Kamae, HP Lab., Japan
     Reigo Yatsuboshi, Fujitsu Lab., Japan
     Kinji Ono, NCIS, Japan
     Michael Diaz, LAAS, France
     Christophie Diot, INRIA, France
     Georgio Ventre, Univ. di Napoli, France
     David Hutchison, Lonchaster Univ., U.K.
     Augusto Casaca, IST-INESC, Spain
            Martina Zitterbart, Univ. of Karlsiuhe, Germany
     Ulf Koerner, Lund Univ., Sweden
     Albert Kuendig, Swiss Federal Inst. of Tech., Swiss

------------------------------

Date: Tue, 12 Jul 1994 12:29:00 +1000
From: JOHN.HACKING@telecom.telememo.au
Subject: Australian InfoCall Service Launched


People seeking fast, expert advice on subjects ranging from the state
of their health to the state of the nation now have access to it over
the telephone.

InfoCall is a telephone information service featuring "live" advice.
InfoCall, which uses a 190 prefix, is available to all customers in
Australia who currently receive itemised bills from Telecom for STD
and international calls.

Callers will be able to speak to an increasing number of experts
including doctors, lawyers, gardening gurus, veterinarians and various
tradespeople.

They can also access recorded voice information services, receive
information via a fax or have information downloaded to a desktop
computer.

InfoCall was today launched nationally following a pilot program in
Victoria which confirmed the service's technical functionality and its
acceptability in the marketplace.

"This is the sort of service which only an advanced telecommunications
network can provide," said Martin Turner, Telecom National Portfolio
Manager for Telemedia.

"Telecom's network enables service providers to tailor services more
and more to meet individual needs and the clear message from our
customer research is that customers want access to information on
their own terms.

"The telephone allows them that access, and the InfoCall service
brings it to them in the privacy of their homes and offices."

Telecom has provided over 150 InfoCall lines and service providers
have indicated their strong intention to provide a wide range of
services over the coming weeks.

These services will include information on the stock market, weather
reports, study tips, computer software support, ticket bookings, state
industrial awards, average real estate prices, racing, gardening and
wedding and legal advice.

Service providers' charges will range from a flat rate of 35cents to
$30 or at a timed rate, ranging from an average of 35 cents to $5 per
minute.

Telecom has worked with consumer groups and service providers to
ensure that customer safeguards are in place.  At the start of every
service, customers receive an introductory message explaining exactly
what the service is and the charge rate.

The message introduction costs 15 cents and no further charges can be
applied until the caller dials a number to activate the chosen
InfoCall service.

Callers hear a pip tone every five minutes on timed-fee live advice
services and are asked to dial a number if they want to proceed beyond
ten minutes on timed-fee recorded voice services.  The caller can
terminate the service at any time by hanging up.

Households and businesses can have InfoCall barred so access cannot be
gained from their telephone. Details about barring the service can be
obtained by calling the InfoCall Helpline on Freecall 1800 035 055.

A test call to 1900 909 000 will indicate to customers whether they
can access InfoCall.  They can also obtain more information on the
InfoCall Helpline.


MELBOURNE  Australia

------------------------------

Date: Tue, 19 Jul 1994 08:39:51 CET
Subject: Re: Recommendations For Lightning Protection
From: lagrana@itu.ch (Fernando Lagrana)
Organization: International Telecommunication Union


The Telecommunication Standardization Sector of the ITU (ITU-T)
developed a whole set of Recommendations relative to Protection
against interference (K-Series).

The following Recommendations are of particular relevance for lightning 
protection:

K.1 Connection to earth of an audio-frequency line in cable
K.11 Principles of protection against overvoltages and overcurrents
K.21 Resistibility of subscribers' terminals to overvoltages and
overcurrents
K.22 Overvoltage resistibility of equipment connected to an ISDN T/S bus
K.25 Lightning protection of optical fibre cables
K.31 Bonding configurations and earthing of telecommunication
installations inside a subscriber's building

Fernando Lagrana

International Telecommunication Union
Telecommunication Standardization Bureau

Editor, Catalogue of Recommmendations

Internet: lagrana@itu.ch
Voice:    + 41 22 730 58 94
Fax:      + 41 22 730 58 53
X.400:    SURNAME=3Dlagrana, PRIVATE_DOMAIN=3Ditu, ADMIN_DOMAIN=3Darc=
om,=20  COUNTRY=3Dch

------------------------------

From: whs70@cc.bellcore.com (sohl,william h)
Subject: Re: Baud vs. bps
Date: 19 Jul 1994 01:01:14 -0400
Organization: Bell Communications Research (Bellcore)


In article <telecom14.320.12@eecs.nwu.edu>, Hugh Pritchard
<hpritcha@snm.com> wrote:

> Now, I'm willing to accept that the copper phone wires will only
> handle 2400 baud, and that the modem makers have come up with ways to
> signify 6 bits (14,400 is 6 times 2400) for each different state
> change.  The modem makers have come up with 2 to the 6th = 64
> different states (some combination of frequencies, phases, and phase
> changes) to fit into the 2400 baud limit.

Actually the copper wires will pass much higher rates.  The limitation
is the design of the network facilities (especially the inter-office
trunking) which will only pass an analog signal within the 300 to 3000
KHz range.  Modem makers must design their analog modems to operate
within that 300-3000KHz range.

So, with those analog limitations, modem manufacturers have been able
to develope modems that go up to 28.8KHz while still having the entire
signal within the 300-3000KHz range.


Bill Sohl (K2UNK) BELLCORE (Bell Communications Research, Inc.)
Morristown, NJ             email via UUCP      bcr!cc!whs70
201-829-2879 Weekdays      email via Internet  whs70@cc.bellcore.com

------------------------------

From: hpa@eecs.nwu.edu (H. Peter Anvin)
Subject: Re: Baud vs. bps
Reply-To: hpa@nwu.edu (H. Peter Anvin)
Organization: United Federation of Planets
Date: Mon, 18 Jul 1994 17:35:03 GMT


In <telecom14.320.12@eecs.nwu.edu>, Hugh Pritchard <hpritcha@snm.com>
wrote:

> Now, I'm willing to accept that the copper phone wires will only
> handle 2400 baud, and that the modem makers have come up with ways to
> signify 6 bits (14,400 is 6 times 2400) for each different state
> change.  The modem makers have come up with 2 to the 6th = 64
> different states (some combination of frequencies, phases, and phase
> changes) to fit into the 2400 baud limit.

That's basically the idea.  However, in order to obtain even further
noise resistance, they actually use 128 states, only 64 of which are
valid at any one time.  This is called "trellis coding", because the
amplitude/phase plots(*) of the valid states look somewhat like a
flower trellis.

I would presume that V.34 (28,800 bps) would use 8192 states at the
minimum, 4096 of which would be valid at any one time (whew!).

The Nyquist limit of an analog phone line is somewhere in the
vincinity of 32 kbps.  If not otherwise it would be dictated by the
fact that it will be digitized to 64 kbps in the switch, and I would
presume trying to obtain more than 50% of that data rate would depend
on some pretty strange factors such as the (in)ability to synchronize
with the ADC clock, as well as on any intermediate D-A-D conversions
that may be done.  Not to mention bit robbing...

(*) = The standard state diagram are amplitude/phase plots when read
as a polar diagram.  They can also be read as an XY plot of the
0-degree and 90-degree components that make up the signal.


INTERNET: hpa@nwu.edu             FINGER/TALK: hpa@ahab.eecs.nwu.edu
IBM MAIL: I0050052 at IBMMAIL     HAM RADIO:   N9ITP or SM4TKN
FIDONET:  1:115/511 or 1:115/512  STORMNET:    181:294/101    Allah-u-abha

------------------------------

Date: Mon, 18 Jul 1994 21:15:56 EDT
From: Paul Robinson <PAUL@TDR.COM>
Reply-To: Paul Robinson <PAUL@TDR.COM>
Subject: Re: Cellular Towers and Frequencies
Organization: Tansin A. Darcos & Company, Silver Spring, MD USA


Shawn Gordhamer <shawnlg@netcom.com>, writes:

> I understand that cellular towers with small cell radius allow the
> cellular frequencies to be used over and over ... [and] no two 
> adjacent towers can use the same frequencies because there will be 
> interference... However, as cellular (hopefully) becomes cheaper
> even 333 channels for a small town may not be enough.

At which point, they ramp down the power level on the tower and add
another one some distance away.  With the way things are going,
cellular towers are getting cheaper, enough so that if a place gets
more volume of calls, the amount of usage means that it becomes
economically viable to add more cells, since if people can't get
through they will stop their service or switch carriers.  Or move to
PCS which isn't going to be too far away.

> A one-tower town cannot just put up another tower, because the towers
> will be adjacent, and they cannot use the same frequencies.

I'm not a cellular engineer, but I do know something about the way the
system works.

It's not quite as bad as you see it.  Let's say that in a particular
area, the tower handles a ten-square mile area, five miles in each
direction.  If a small town, let's say two miles away, is getting so
much calls that it is overloading the cell, then what you do is that
you do a traffic analysis to see where most of the calls are being
taken at; perhaps most of the calls are in the central business
district.

So you have a pattern like this:

 Tower1-----!-----Tower2-----!-----Tower3--x---!-----Tower4-----!-----Tower5

When a call gets to a ! it's going to hand off to the next tower
because that one is giving a stronger signal.  The 'x' is where the
small town is that is overloading Tower 3.  So you put in another
tower, perhaps near the break point, like this

!-----Tower3--x--Tower3a---!---Tower4

Tower3a will pick up about 1/2 of the calls in the Tower3 area, and
part of Tower4's service.  By making it an equal distance from the
town, you can thus split about 1/2 the traffic to each tower, since at
some point one of them is a stronger signal than the other, or is
available because one of them is overloaded.  Thus each tower only has
to handle 1/2 of the area of the prior one.  Or you go even further:
you put one very small, inexpensive lower powered cell right in the
center of town where most of the calls originate from (many people in
vehicles passing through a congested area, perhaps because it's the
only gas station for several miles).  This cell would be the strongest
one for perhaps 1/2 mile or so, then as they move on they revert back
to one of the towers handling the much sparser traffic areas.

> In fact, for a large town with dozens of towers, each tower would have to 
> use at most 1/4 of the channels, making a grid pattern
> A B A B A
> C D C D C
> A B A B A
> C D C D C 

Actually, the term "cells" as used in cellular is more similar to a
honeycomb or hexogonal pattern, which each cell using a block
frequencies not used by any of the cells that is next to it, so we
more often have something similar to the following:
    _   _   _       
  _/A\_/C\_/A\_    A cell frequency cannot be used by a cell that is
 /D\_/B\_/D\_/B\   touching any other, so they break up the available
 \_/C\_/A\_/C\_/   cells such that in each area only some of the 
 /B\_/D\_/B\_/     frequencies can be used.  But in each area, each cell
 \_/ \_/ \_/       in group "A" can use all of the available group "a"
                   frequencies.

In short, if a cell gets too many calls, the cell can be made to cover
a smaller area and another cell inserted into the matrix to change the
size of the coverage area.


Paul Robinson - Paul@TDR.COM

------------------------------

From: wwalker@qualcomm.com (Bill Walker)
Subject: Re: Cellular Towers and Frequencies
Date: Tue, 19 Jul 1994 06:04:51 -0700
Organization: Qualcomm, Inc.


In article <telecom14.316.4@eecs.nwu.edu>, shawnlg@netcom.com (Shawn
Gordhamer) wrote:

> I understand that cellular towers with small cell radius allow the
> cellular frequencies to be used over and over, allowing thousands of
> simultanious cellular conversations.  I also understand that no two
> adjacent towers can use the same frequencies because there will be
> interference.

> Where I live, there are lots of small towns that have only one
> cellular tower.  

[which is plenty for now, but may not be in the future when everybody in
town has a wireless phone.  And you can't just put up more towers because
the population is not geographically dispersed]

> In fact, for a large town with dozens of towers, each tower would
> have to use at most 1/4 of the channels, making a grid pattern like
> the following:

[...]

> Am I correct in this assumption?

Yes.  The most common reuse pattern, to my knowledge, is called K=7,
which basically means that you have to get seven cells away before you
can reuse the same frequency.

To some extent, you _can_ put in more cells (probably not "towers")
even in a small town.  You just have to limit the coverage and
interference of each cell, by doing things like using lower antennae,
lower power, directional antennae (all of which come under the general
label of "microcells").

Or [WARNING!  BIASED STATEMENT COMING!] you could replace your analog
cellular system with a CDMA digital cellular system, which will
provide about 10 times as many calls in the same frequency allocation
[QUALCOMM, my employer, is the chief proponent of CDMA digital
cellular].  No new towers, no new antennae, but everybody who wants to
use the new system has to get a new phone (but the new and old systems
can coexist).

Disclaimer:  I'm a software guy with a rusty, old digital-oriented EE
degree, so I've probably over-generalized the RF stuff about propagation
and microcells.


Bill Walker - WWalker@qualcomm.com - QUALCOMM, Inc., San Diego, CA USA

------------------------------

From: lars@Eskimo.CPH.RNS.COM (Lars Poulsen)
Subject: Re: Bridge vs. Router Performance
Organization: Rockwell Network Systems, Copenhagen DENMARK
Date: Tue, 19 Jul 94 09:05:09 GMT


In article <telecom14.317.1@eecs.nwu.edu> sthomas@mitchell.hac.com
(Scott D. Thomas) writes:

> I have a puzzling (at least to me) situation.  We have a simple
> network with a satellite link included.  Orginally, we bridged three
> ethernet segments ...  ... ... ... ... ... and got poorer that expected
> results.  We decided to replace the bridges with routers, one per
> segment.  The throughput was tripled!

> I was under the impression that bridges were more efficient because of
> lower overhead, less complexity, etc.  and therefore would offer the
> better performance.

The most likely reason for your poor performance, is that one of the
sites in question is a LARGE network (maybe several hundred stations
or more ?) and the amount of broadcast/multicast traffic floating
around in the network is eating up all the bandwidth of the DS-1 link.

When connecting multiple LANs into one extended network, the
connection can be implemented with different logical models.

Bridging is the lowest level model; it takes to similar networks (such
as two Ethernets or two Token-Rings) and joins them intpo one logical
network. A bridge device on each end of the link:

- goes into promiscuous mode (snooping on all traffic)
- keeps track of which devices (identified by their Ethernet addresses)
  are on each end, and
- forwards traffic for any device not know to be on the same LAN as
  the sender, as well as all broadcast/multicast messages across the link.

Because this is done at Media Attachment Control (MAC) level, it is
protocol independent, and requires very little setup.

The downside is that all broadcast/multicast traffic is forwarded, as
well as traffic from protocols that are entirely unsuited for wide
area traffic. The larger the combined network, the larger the amount
of background "slosh" og broadcasts, even as a percentage of total
traffic. (For instance, every ARP request will be sent everywhere,
theough almost all of them are for stations local to the sender.)
When you have a couple hundred workstations, you are likely to have
about 32 Kbps worth of "slosh". (Meaning you need a T1 to get any WORK
done.)

To overcome the deficiencies of bridging, you need a router. Routers
must understand each protocol and must be configured appropriately for
each protocol. This means that somewhere in the organization there has
to be a person who understands each protocol that is being routed, and
who can set up an addressing plan and troubleshoot when problems
arise.

For a good textbook in this area, I recommend Radia Perlman's book
"Interconnections: Bridges and Routers". Addison-Wesley, 1992.  ISBN
0-201-56332-0. I think I paid $53.26 (incl CA tax).


Lars Poulsen   Internet E-mail: lars@RNS.COM
Rockwell Network Systems Internets: designed and built while you wait
Hvidovre Strandvej 72 B  Phone: (011-) +45-31 49 81 08
DK-2650 Hvidovre, DENMARK Telefax:      +45-31 49 83 08

------------------------------

From: lailert@ucssun1.sdsu.edu (Supak Lailert "spk")
Subject: Re: IP Over Cable TV
Date: 18 Jul 1994 18:15:14 GMT
Organization: San Diego State University Computing Services


Lubos Elias (Lubos.Elias@uakom.sk) wrote:

> I am looking for information about possibility to provide IP service
> over cable TV wires. Are there any products?

In San Diego, our local cable company, Cox Cable, has successfully
tested the system that allow access to Prodigy via the cable TV
network. I think it acts like a very fast modem so I think we could
use SLIP or PPP over it, too.

Regarding their TV commercial, Cox claims over 50 times higher
throughput over modem access. Is it 9600BPS times 50? (I don't know
what the highest modem speed at Prodigy.) As I heard from local
computer magazine, the service has not been ready yet.


Regards,

Supak Lailert -- MBA (Information System) Program, San Diego State University
lailert@ucssun1.sdsu.edu   lailert@aol.com

------------------------------

End of TELECOM Digest V14 #327
******************************

