Subject: [NEXTEL-1] DV/IP

From: Marcel <[email-masked]>
Date: Tue, 28 Jan 2003 21:05:37 -0500

United States Patent Application

20020111181
 Kind Code

A1
 Jaybush, Brent ;   et al.
                                                                                 August
15, 2002

Apparatus and method for large area radio dispatch communications

                                             Abstract

A radio dispatch system has a plurality of base stations covering a large geographic area.
The base stations are connected to the
Internet so voice messages can be sent between them. Each of a plurality of mobile
transceivers is adapted to send voice
messages to one of the base stations and receive voice messages from one of the base
stations. As a result, the mobile
transceivers can communicate with each other and the base stations over a wide geographic
area limited only by the reach of the
Internet.

 Inventors:
              Jaybush, Brent; (Los Angeles, CA) ; Lee, Han Ki; (Cypress, CA) ; Lim, Hong;
(Rosemead, CA)
 Correspondence
 Name and
 Address:
                  CHRISTIE, PARKER & HALE, LLP
                  350 WEST COLORADO BOULEVARD
                  SUITE 500
                  PASADENA
                  CA
                  91105
                  US

 Serial No.:
              076014
 Series Code:
              10
 Filed:
              February 12, 2002

 U.S. Current Class:
                                                                                  455/519;
455/517
 U.S. Class at Publication:
                                                                                  455/519;
455/517
 Intern'l Class:
                                                                                      H04B
007/00

                                             Claims

What is claimed is:

1. A radio dispatch system comprising: a plurality of base stations covering a large
geographic area; means for connecting the
base stations to the Internet to transmit voice messages there between; and a plurality of
mobile transceivers adapted to send
voice messages to one of the base stations and receive voice messages from one of the base
stations.

                                           Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of Application No. 09/953,341, filed Sep. 12,
2001, which claimed the priority of U.S.
provisional Application No. 60/232,021, filed Sep. 12, 2000, the disclosures of which are
incorporated fully herein by reference.

BACKGROUND OF THE INVENTION

[0002] This invention relates to radio communications, and more particularly, to a wide
area radio dispatch system and method
capable of operating over a large geographic area.

[0003] Radio dispatch technology is used to communicate between a mobile station and fixed
stations over short distances, e.g.,
fifty miles or less. Transmission takes place at low power and low frequency (e.g. below
520 MHz). Most radio dispatch systems
employ push-to-talk (PTT) transmission from the mobile stations on one or more channels
and continuous transmission on a
different frequency from the base station. Typical users for PTT radio dispatch systems
are taxis, delivery men, and government
workers.

SUMMARY OF THE INVENTION

[0004] According to the invention, a radio dispatch system has a plurality of base
stations covering a large geographic area. The
base stations are connected to the Internet so voice messages can be sent between them.
Each of a plurality of mobile
transceivers is adapted to send voice messages to one of the base stations and receive
voice messages from one of the base
stations. As a result, the mobile transceivers can communicate with each other and the
base stations over a wide geographic area
limited only by the reach of the Internet.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The features of specific embodiments of the best mode contemplated of carrying out
the invention are illustrated in the
drawings, in which:

[0006] FIG. 1 is a diagram of a radio dispatch system that illustrates the principles of
the invention;

[0007] FIG. 2 is a block diagram of a mobile transceiver constructed in accordance with
the principles of the invention; and

[0008] FIG. 3 is a block diagram of a base station constructed in accordance with the
principles of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0009] According to the invention, radio dispatch systems operating in different
geographic areas called "cells" are interconnected
by a wide area network, preferably the Internet. In FIG. 1a plurality of base stations
10a, 10b, 10c . . . , 10n, called repeaters in
the drawing because they relay the information being transmitted to another destination,
are distributed throughout a large
geographic area represented in the drawing by an outline of the United States 12.
Normally, there is one base station per cell,
unless the traffic load requires more. Base stations 10a to 10n are connected to each
other and a number of other accessories to
be described via the Internet 14. Hand-held mobile transceivers 16a, 16b, 16c, 16d, 16f .
. . , 16n send messages to one of base
stations 10a to 10n, depending upon their proximity to the base stations. Within a cell,
the mobile stations communicate with each
other vis their base station. In addition, mobile transceivers 18a, 18b, 18c, 18d . . . ,
18n, which are mounted in vehicles, also
communicate with base stations 10a to 10n in the same way as mobile transceivers 16a to
16n. All the mobile transceivers are
preferably provided will GPS receivers so the mobile stations can transmit positional
information with the voice messages. Mobile
transceivers 18c and 18d are preferably provided with displays that overlay positional
information about the mobile transceivers as
derived from the GPS receivers on a map of the region served by the mobile transceiver.

[0010] A digital logging recorder 22 is connected to Internet 14 to receive from each of
base stations 10a to 10n a baseband data
stream that is raw in the sense that it is recorded in the same data format as it is
transmitted. If any of this data is to be recovered
later, it can be identified by scanning the headers in the formatted data.

[0011] A local desktop dispatch console 24 is connected to Internet 14 to communicate with
other resources unconnected to the
dispatch network by modem or telephone. For example, fire or police assistance could be
initiated from console 24. A centralized
dispatch console is also connected to Internet 14 to monitor and manage the traffic on the
system.

[0012] When a message is sent over Internet 14 to a particular base station, if all the
available channels there are in use, the
message is stored at the receiving base station so transmission from a base station is
never blocked. As soon as a channel
becomes available at the receiving base station, the channel is assigned to the stored
voice message, which is then sent to its
destination mobile transceiver.

[0013] One of the mobile transceivers is shown in FIG. 2. A microphone 30 is coupled by a
PTT switch 32 to an encoder (codec)
34a. that digitizes voice messages from microphone 30. Preferably, a four level code is
employed; accordingly a pulsed signal
having four amplitude levels, preferably at a spacing of 1/60 of a second, is generated by
encoder 34a. Encoder 34a is coupled to a
DV/IP processor 36. In processor 36, the encoded voice messages are packetized, preferably
according to a protocol called
digital voice/internet protocol (DV/IP) that is described in the appendix. A source of GPS
information 38 and a source or other
data 40a are also applied to the input of processor 36. The packetized baseband voice
messages, data, and GPS information are
coupled to a modulator 42a, where they control the frequency of a local oscillator (not
shown). The result is a frequency shift
keyed signal that moves among four slightly different frequencies, depending upon the
level of the baseband signal. An antenna
46a is driven by the output of transmitter 44a to broadcast the information containing
signal throughout the cell in which the mobile
transceiver is located. If trunked radio dispatch (multiple channels) is employed, the
frequency of a local oscillator 48a varies
depending upon the channel assigned to the mobile transceiver. Typically, the channel
separation is 10 KHz and the bandwidth of
each channel is 6 kHz. Local oscillator 48a is coupled to transmitter 44a to change the
frequency of transmission by mixing the
frequency shift keyed signal. Alternatively, a single oscillator could be used to perform
both the frequency shift keying function
and the channel selection function; in this case, programable frequency dividers are
disposed in a phase locked loop to change the
frequency of transmission to some multiple of a reference oscillator (i.e., a crystal) and
the four level baseband signal modulates a
varactor capacitor connected in parallel with the reference oscillator.

[0014] A receiving antenna 50a, which intercepts the signal transmitted from the base
station of the cell in which the mobile
transceiver is located, couples the intercepted signal to a receiver 52a. The frequency of
receiver 52a is heterodyned down in
frequency (e.g., to 12.5 KHz) by a local oscillator 54a. A demodulator 54 couples receiver
52a to a DV/IP processor 56a.
Demodulator, which could be a conventional frequency discriminator of the type used in
commercial FM receivers, converts the
four frequency signal at the output of receiver 52a to a four level baseband signal.
Processor 56a de-packetizes, i.e., parses, the
four level baseband signal according to the DV/IP protocol described in the appendix. As a
result, the signal at the output from
processor 56a is the same as the signal at the input to a processor 36b at the base
station, as discussed below in connection with
FIG. 3. In other words, processor 56a performs the reverse operation on the transmitted
information from processor 36b. Control
data from processor 62a is coupled to the input of a channel selection processor 62a. One
output from processor 62a controls the
frequency of local oscillator 48a to set the frequency of transmission from the mobile
transceiver. The other output from processor
62a controls the frequency of local oscillator 54a to set the frequency of reception by
the mobile transceiver. The control data for
effecting channel assignment for transmission and reception at the mobile transceiver is
sent to the mobile transceiver by the base
station. The output of processor 56a is coupled through the normally closed contact of a
switch 64 to a decoder (codec) 58a.
Although switch 64 is shown schematically in the drawing, it would preferably be an
electronic switch, so operations are not
unduly delayed. Decoder 58a creates strobe pulses from the incoming signal to detect the
four levels, convert them into binary
words depending on the level of the incoming signal, and then convert the binary words to
an analog signal that replicates the
signal applied to the input of an encoder 34b at the base station, as discussed below in
connection with FIG. 3. This analog signal
from decoder 58a drives a loud speaker 60 to reproduce the voice message sent by the base
station. The input to a memory 66,
such as a CD ROM, is also connected to the input of decoder 58a and its output is
connected to the normally open contact of
switch 64. Switch 64 is actuated by depressing a replay button 68. If the user of the
mobile transceiver wants to replay a message
for any reason, s/he can press replay button 68 and the message is read out of memory 66
and sent to decoder 58a for processing
in the described manner. It should be noted that the voice messages are stored in memory
66 in "raw" form, i.e., as four level
baseline signals, and are continuously overwritten by new voice messages so the replay
capability is temporary.

[0015] One of the base stations is shown in FIG. 3. The components in FIG. 3 that bear
reference numerals including the letter "b"
are functionally the same as the components in FIG. 2 that bear the same reference
numerals including the letter "a". The Internet
14 delivers data in a binary stream to DV/IP processor 36b. Processor 36b is connected to
a modulator 42b. A data source 40b is
also connected to processor 36b. Part of the data from source 40b is a channel selection
schedule. Modulator 42b is coupled to a
transmitter 44b, which drives a transmitting antenna 46b. A receiving antenna 50b is
coupled by a receiver 52b to a demodulator
54b. Demodulator 54b is coupled to a DV/IP processor 56b. The output of processor 56b is
coupled to the Internet to distribute
the voice messages to other base stations. Header information from the signal emanating
from processor 56b determines the
destination of the voice messages being routed to Internet 14. In Internet 14 the data
outputted from processor 56b is converted to
TCP/IP format. The GPS information at the output of processor 56b is routed to a GPS
processor 70, which drives a display 72.
Display 72 shows the position of the mobile transceiver that sent the message being
processed, preferably overlaid on a map of the
region being served by the radio dispatch system or one or more cells thereof.

[0016] A feature of the invention is controlling the channel, i.e., frequency, of
transmission to and from the base stations so each
channel assigned to the radio dispatch system is only used for part of the time.
Specifically, a control channel transmitted from
each base station is dedicated to the function of sending upstream channel assignments to
the mobile transceivers. If there is a lot
of traffic on the system, different groups of mobile transceivers maybe assigned to
different upstream channels. The control
channel typically would change the channel assignment from time to time, even in the
middle of the transmission of a message.
Similarly, the assigned control channel also changes from time to time. When a control
channel change is made, the frequency of
the new control channel is transmitted over the control channel about to be taken out of
service. The traffic on the various
channels is monitored so that the channels bearing the least traffic can be assigned first
to the mobile transceivers so as to even
out the traffic flow.

[0017] The attached appendix describes in further detail the operation of the invention.

[0018] The described embodiment of the invention is only considered to be preferred and
illustrative of the inventive concept; the
scope of the invention is not to be restricted to such embodiment. Various and numerous
other arrangements may be devised by
one skilled in the art without departing from the spirit and scope of this invention.

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---

From: Rick Parrish <[email-masked]>
Date: Tue, 28 Jan 2003 20:17:28 -0600

>United States Patent Application
Random thought: would IRLP or similar qualify as "prior art" ?
-rick

---

From: Rick Parrish <[email-masked]>
Date: Tue, 28 Jan 2003 21:15:32 -0600

Thanks Marcel!

I just looked up some old patents. Portions of the DV/IP overlap *at 
least* two others. Trouble is those two other patents were issued five 
years ago.

PS. Patents are evil!

-rick

---

From: "Todd Ellis" <[email-masked]>
Date: Wed, 29 Jan 2003 07:43:11 -0500

Well, further investigations are turning up next to nothing.  This stuff
must be fairly hush-hush, as I can't find nary a thing about it on the
Internet, except one of their sales guys cold-called one of my clients
yesterday to introduce himself and their products.

One interesting aspect "The radio has no internal adjustments, so there is
no alignment whatsoever, and no trimmers to vibrate out of alignment in
harsh, mobile environments. The radio's revolutionary UltraLoc synthesizer
allows it to change channels from one end of the band to the other and come
up to full power in less than 200 nanoseconds."

To me, this would make it a frequency-hopper candidate.  Transcrypt, using
the Bendix/King portable platform, used to manufacture the "Phantom 27"
hopper, and I sold a bunch of them a long time ago.  Look it up in a Jane's
Defence Communications book, circa 1988-1990.

A couple of other interesting notes...the radio looks a lot like the old
Teletec radios as far as features and layout.  I also notice in one picture
the radio display says "SAUDI TEL".  This makes me think of some of the guys
I know that came up with the Teletec product in the first place, and have
been living in exile in Saudi Arabia since Aerotron fell apart in '93.
Teletec radios were (under)priced at $4,500 a copy, and typically had 13
circuit boards crammed into each RF/trunk mount package.  The keypad was on
the right, had pushbuttons below the EL panel display, RJ-11 mic connection,
etc.  Teletec also held the patent for an all-pushbutton controlled two-way
radio.  Makes me shiver!

Looking at their info, I see that they are in Los Angeles.  They list jobs
for:

  a.. Senior DSP Programmer
If you know your way around DSP coding for wireless products, we need a team
leader to develop next generation high feature wireless products.

  a.. RF Engineers
DWC has openings for RF engineers with experience in the design of land
mobile communications products.

  a.. Mechanical Designer
We need an experienced Mechanical Engineer with Pro E 3D experience. You
must be familiar with the design of plastic molded parts as well as thin
wall die cast aluminum parts.

  a.. Software Engineers
Develop real time applications, device drivers, and utilities in C/C++,
Unix, QNX, and TCP/IP.

  a.. Applications Designers
Develop end-user application/interface code, common database
infrastructures, in visual languages (C/C++, VB, VFoxpro, Power Builder),
ODBC connectivity, SQL, amd ActiveX controls.

  a.. PC Board Designer
Experience with PADS board layout and ORCAD schematic capture is a must. You
will be designing multi-layer boards, some including RF striplines.

Then they say:

Digital Wireless Corporation™ is a wireless technology company, the inventor
of dispatch radio over IP. The company is well funded by a blue chip family
of investors, has a multi- million order backlog, and offers unique and
potentially highly rewarding opportunities to its employees. The company has
three Fortune 500 shareholders yet is controlled by management and
employees. That translates into stable management and direction, competitive
salaries and benefits, employee profit sharing, IP authoring bonuses for
engineers and programmers, along with a unique work environment and
participation in a highly motivated and successful team. DWC is a company
focused on customer satisfaction, products and profits!

Hmm.  TE say "need more info..."  Now if I could get the end of my finger to
glow like ET !

Todd Ellis

 -----Original Message-----

 Subject: Re: DV/IP

August

---

From: "Paul J Zawada <[email-masked]>" <[email-masked]>
Date: Wed, 29 Jan 2003 14:48:52 -0000

--- In [email-masked], Rick Parrish <rfmobile@s...> wrote:
> >         August 15, 2002

Rick.. I had exactly the same random thought.

From what I saw in the Patent info Marcel posted, these guys filed 
their first provisional patent application in September of 2000.   
The IRLP home page says that work on IRLP started in 1997 and their 
first node was on the air in November of 1998.  The Internet Wayback 
machine ( http://www.archive.org ) has pages for www.irlp.net going 
back to January of 2000. 

IANAL, but I would think IRLP would be considered prior art...  You'd 
think the folks at the Patent Office would do few searches on the web 
before they rubber-stamped these things...

--zawada