Note: Descriptions are shown in the official language in which they were submitted.
1;~,3 .'
This invention relates to digital communications systems and,rnore part-
ocularly, to a fully distributed, disposable, self-organizing, self-powered soys-
tent which can be deployed, activated, operated and maintained in a hostile en-
vironment without the need for human assistance.
As is well known and understood, a wide variety of problems come into
play in operating a radio-con~Lnicatic~s systent in a hostile environment. For
example, r,tessage traffic flow from user to user and from node to node or front
relay station to relay station is usually controlled by centralized units which
l are of far higher corrtplexity, value, weight and bulk than the relay or user stay
1 lion. In digital communications systems this centralized unit frequently is acornputer Lucia operates together with a large collection of peripheral equipment
This means that the whole system is hierarchically organized such that the open
atonal availability of the whole system depends on the availability of the
highest member in the hierarchy, the central control unit. ~orneone who is in-
terested in deactivating the system only has to concentrate his efforts on de-
activating the central control unit . Isles task is simplified by the fact that
these units are much easier to detect and easier to destroy than the lower and
more expendable members of tile hierarchy.
l Also contributing to problems in their usage, such conrnunications soys-
1 terms most often operate at UHF frequencies, where tall antenna structures arereouired for line-of-sight transntissions -- especially in wooded areas and in
localities where other obstructions such as buildings predominate. ugh antenna
structures increase system vulnerability to detection, electrical interference
I and physical destruction.
J
lath the tecttnolo~y frequently e cloyed in their construction, no will-
the manners of their implementation, such communications systems offer further
disadvantages in that their component parts have to be repaired, replaced and
maintained -- because of their expensive costs and non-disposability. This
leads to additional problems by requiring a dedicated supply, storage and no-
pair organization whose own limits in availability contribute to limits in soys-
them survivability.
In order to make a communications system less detectable one has to oh-
sure its appearance. While nothing can be done to reduce a given physical
size, one can try to hide system units, e.g., in natural or man-made cover and
one can give its electrical emissions a noise-like appearance, e.g., by spread-
in its electrical emissions over a large frequency range by so-called spread-
spectrum methods. However, physical hiding interferes with loneliest open-
anion and spectrum spreading increases the cost, complexity and, hence, the
physical bulk of the system units.
In order to make communications and communications systems less vulner-
able one usually tries to supply a sufficient number of back-up copies of soys-
them units and messages, i.e., one increases redundancy. This again can only
be bought at higher costs and complexity or one has to accept a decrease in
system performance by only partly utilizing the system, i.e., by slowing down
or reducing the message traffic.
Other disadvantages of such prior art communications systems will also
be readily recognized: a) The high cost involved because of limited product
lion runs; b) The continuing use of increasingly obsolete designs so as not to
incur the additional costs of new developments; c) The high degree of train-
in required in the utilization of the communication equipments; d) The Defoe-
gully in transporting about, because of weight, size and bull.
s will become clear hereinafter, the electronic communications and con-
trot system of the invention comprises a fully distributed, disposable, self-
organizing, self-powered communications system. when deployed, it will paraffin
its junctions by simultaneously maximizing the survival of the system under all
foreseeable threats during the time interval in which the system is needed. As
will be seen, the communications system operation entails the randomly seeding of
an area with system units.
ore specifically, as will become clear from the following description,
these system units are each small, disposable transceivers, which are
self-powered, and which include a defined amount of built-in digital processing
llcapability. Preferably contained on a monolithic semiconductor chip utilizing
livery low power technology, these transceiver units would be powered by a suitable
energy storage device such as a capacitor or a plastic-encased thick film or gel ¦
battery which could be made rec~rgeable by a battery of solar cells.
in a preferred embodiment, the entire transceiver unit is attached to a¦
piece of thin plastic material, which can then be deployed as easily as
anti radar "chaff", e.g., by airplane (drone), rocket, balloon or barreled
weapon. The plastic film is to be shaped in such a way that it will become
entangled in obstacles such as tree foliage and/or other ground cover. The
plastic film is additionally to serve as the base material for an appropriate
I printed antenna structure -- with the carrier frequency being such as to allow
llline-of-si8ht operation, even in wooded areas, and preferably outside the
established capabilities of a potential jammed, or at least in a range where an
attempted jamming would require a large investment in equipment usage and power
dedication. A suitable carrier frequency, according to the invention, would be
at, or above, 12 I and in the interest of power conservation a pulsed carries
is to be used, with modulation being combined with suitable spread-spectrum
schemes if needed.
In accordance with a preferred form of the invention, system operation
., ,
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77~
is initiated by random distribution of system elements over an area which
bridges the distance between two, or more, operating tenmm at stations. Such
terminal stations may be of the type including commutlicatiatls stateless, sensor
elements, remotely activated or operating electronic systems, or remotely anti-
voted or operated automata or robot systems, with the system elements being de-
plowable either before, or after, the terminal stations have been established.
As will be seen, such system elements may even "wait" in a dormant state in
some potentially hostile territory, until being called into action.
The system is a homolog~te by virtue of the fact that all system units
are of exactly similar construction with similar operational capabilities.
There is no hierarchical organization whatsoever
s will be readily understood by those skilled in the art, the dispose
able transceiver system elements can be recruited into the cumm~nications net-
Turk by call signals issued by the terminal stations, requesting access to the
network. Those system elements nearest to a terminal station would then no-
spend to the call, and relay it to the system elements nearest to them, and so
on. When a call finally reaches its destination, all disposable transceiver
system elements which have contributed to the linlcing of the two stations to-
getter Toledo then became "members" of a particular data path; all other disk
potable transceiver system elements which have not yet achieved such a linking would "drop out", and return to the standby wait for reception of the recruit-
in call mode. In furtherance of the system network, different operating and
control modes -- as well as terminal stations and system element identifiers
-- will be seen to be represented by suitable codes established in accordance
with an operations protocol.
The way in which system elements contact each other can be thought of
as being similar to the way in which data-processing elements in living systems
nerve cells, contact each other through their synapses.
These and other features of the present inverttion will be more clearly
, 1,~.~,3'~.t~
understood from a consideration of the following description, taken in connect
lion with the accompanying drawings in itch:
FIGURE 1 is a functional block diagram of the electronic communications
and control system transceiver element according to the invention;
FIGURE 2 illustrates a suitable packaging for tile transceiver system
element as will permit easy deployment by airplane, rocket, balloon, barreled
weapon or other suitable deployment c~lveyance;
FIGURE 3 is a block diagram, in implied form, of a terminal station as
might be employed in the system operation;
¦ FIGURE 4 is a block diagram illustrating the addition of further terming
Sal station equipment for employing the disposable transceiver system elements
in a multi-channel operation, for example, and in a communications nitric to
be compatible with other, different communications formats and systems; and
FIGURES 5-10 are flow diagrams useful in an understanding of the present
invention.
As the communications and control system of the invention can be viewed
as a multiple electronically synapsing homology the system description and come
pennants will, for the sake of siinplicity, be hereinafter referred to by the
acronym MESH. Thus, referring to the block diagram of the MUSH unit of FIGURE
1, reference numeral 10 identifies the central processing unit, which, through
its inpu~/output circuit 12 controls all unit functions. The programs for all
its modes and, in the case of connected terminals all interfacing characters-
tics, are shown to be stored in a read-only memory 14. Temporary storage for
the processing functions and message buffering is available in a random access
n or 16 and in a stack of registers (not shown). All timing functions -- as
well as frequency synthesis -- are controlled by a master clock 18.
In the receiving mode, the antenna 20, through the antenna switch 22, is
connected to the receiver 24, which derives its local oscillator frequency prom
the frequency synthesizer 26. The received signal is demodulated in the
1~771~
demodulator 28, from where it is routed to the central processing unit 10
through the input/output circuit 12. In the transmitting mode, the transmitter
switch 30, under program control from the central processing unit lo (through
the input/output circuit 12), switches on the modulator 32 and the transmitter
34, and connects the antenna 20 to the transmitter output by means of the an-
henna switch 22. The processed base band signal from the central processing
unit lo is applied, also, to the modulator 32 by means of the input-output
circuit 12, with the modulator 32 then supplying a modulated intermediate ire-
quench to the transmitter 34 whose carrier frequency is supplied, or ccntrolledJ
lo by the frequency synthesizer 26. A temperature drift, affecting clock frequent
cry, would thl~sly have the same direction of deviation in the transmitter 34 as
well as in the local oscillator, and, hence, the receiver tuning frequencies
of all ASH units deployed in the same envirc~ment would have the same direct
tonal deviation It is, of course, possible to improve the basic clock stay
ability by bonding the substrate of the integrated circuit to a material whose
thermal expansion counteracts that of the substrate. The remaining temperature
instability can then be further compensated by a method of digital compensation
as known in the previous art.
¦ Operating power is supplied to the ASH unit by a rechargeable battery
20 l 36, which is initially charged and recharged by appropriate solar cells 38, an
whose charge condition is monitored by a charge sensor 40. As will be under-
stood, the MESH unit of FIGURE 1 drops in and out of operation, depending llpO~I
whether the available battery power does, or does not, exceed the threshold of
the charge sensor 40. Exceeding such threshold will be seen to result in the
activation of the ASH unit, and in the initialization of all its functions,
(As will also be understood, the clock lo activates scheduled frequency and/or
code cages for the unit, provided the power be continuously supplied for
such purpose All ASH unit clocks are to be synchronized prior to the deploy-
mint in the communications field, in any appropriate manner.)
prefer red eDoodi~.ent of the MESS omit is shown in FIGURE 2, Ike uric
--6--
If
If I
2;~7~80
is shown in deployed form. The body 54 of the unit would be one piece of pies
tic material which is prestressed in such a Jay that the depicted shape is
automatically assumed as soon as the Unlit is freed from the deployment package
In the packaged state the unit body 54 would be opened flat and lie in the
same plane as the legs 50, tightly packed in a stack with other MESH units.
The legs 50 are distributed in such a way that the unit's landing on three
legs is always assured. The legs 50 will also serve as substrates for the
solar cells and reasonably omnidirectional antenna conductors. A sensing air-
cult in the transmitter can be made to detect which of the legs are closest to
a solid surface, e.g., by a rough measurement of the reflected wave as crown
from previous art. An into m at switching circuit would then make the antenna
structures on these legs the ground plane and the antenna conductors on the rev
mining legs the radiators. The leg tips 52 would be covered by an allusive
¦ which would be activated upon contact with air and kept inactive by a suitable
gas in the deployment container. The adhesive would be iced with, or duster-
butted on top of, a similarly air-activated foaming agent which would keep the
device afloat should it land on water. If the foaming reaction is exothermic,
the adhesive could as well be of a heat-activated variety. Lyle adhesive will
l make the first leg that contacts a surface briefly or permanently adhere to
¦ the surface whereupon two more legs will contact and adhere to the surface. If
the adhesive strength is insufficient, the process will repeat until terminated
by curing of the adhesive. Thus, if a MESS unit hits a vertical surface, e.g.,
of a building, it will actually "walk" down the wall of the building until it
has found a stable position where it will stick out from the Hall, ready to act
as a radio-relay station. In wooded areas some ASH units will adhere to loll-
age in tree tops, other will fall to the ground or establish themselves scone-
where in-between. ASH units that land on other objects, such as vehicles,
could be used as ving-target indicators. ale inside and/or outside of the
body I would preferably be used to hold the other components and circuit eye-
newts of F JOE 1.
-7-
I
1,
if 1;~377~
he MESH unit would be a mass-produced device which by virtue of its
production in extremely large numbers would always justify its redesign as to
reflect the latest state of the art. presently, it could be expected that the
arrangements of FIGURES 1 and 2 would use ribbon-grown or amorphous technology
for the solar cells 38. All the elements of the SO unit are printed or
rolled cmto, or produced simultaneously with, the carrier as shown in FIG UP 2.
The rechargeable battery 35 utilizes a weight-and-volume efficient process,
preferably employing a Lithium couple. All the remaining linear and digital
circuitry is integrated on a single semiccmductor chip of extremely-low-po~er,
very-high-speed, and very-high-density technology, probably utilizing cycle
rnentary-metal-oxide-semiconductor tec~mology on one of the III-V or II-IV semi-
conducting compounds, such as Gallium Arsenide. Interconnections will utilize
leafless chip-carrier and tape-autc~ted-bonding techniques, kowtowing all con-
ventional encapsulation. If the unit elements of FIGURE 1 are not embedded in
the body 54, a thin plastic covering will contain the battery materials and
protect the electronics, thereby providing equal life expectancies for all the
components of the ASH unit under given environmental cloddishness. the whole
MESH unit will weigh at most a few grams and iII deployed foreign only be approxl-
l mutely between 2 and 3 centimeters long.
20 ¦ loath the arrangement as thus described, it will be appreciated that the
EYE system is based on small, cheap, extremely light weight system elements,
which can be deployed extremely simply and in very large numbers. because of
this, field maintenance is no longer really necessary, except to store the
SUE units and to monitor their shelf life by expiration date only. Because
the logistics is then similar to that of the storage of soap, ~Dn~ulition or
other disposable items, the corrrnunications system of the invention will be seen
to obviate the need for, and updating of, extensive field documentation, main-
tenancy and test facilities, and the spew training of user and maintenance
personnel. it the same time, the introduction and updating of technical dock-
mutation testing and personnel training will be seen to be required only at
1 :lZ3778~
the manufacturing facility. The most expensive operation in conventional
electronics manufacturing, that of testing, will be reduced to the testing of
random samples during any production run. As such, the user only needs to know
the expected value of the yield of operational devices avid its distributiorl in any
given manufacture.
The MESS user and interfacing units shown in FIGURES 3 and 4 include
essentially similar elements as shown in FIGURE however, the hardware
illustrated in these two drawings differ in the requirement of exhibiting a high
Reliability characteristic -- such that for example, the chip containing the
illuminates of FIGURE 1, in the constructions of FIGURES 3 and 4, would be
conventionally encapsulated and fully tested. Additional testing expenses
associated with these constructions, however, can still be largely eliminated to¦
the extent that the MESH units employed are available from the random sampling
testings carried out in the original MESH production. reference numeral 60.)
! According to user requirements in the communications mode of operation
the input/output circuit of the individual MESH unit 60 might be required to
interface with external equipment and/or circuitry -- such as analog-to-digital
and digital-to-analog converters, crypt devices, sensors and analyzers of
biological parameters (for user authentication, for example), special-purpose
sensors, processors, actuators, transmitters, interfaces to other systems, etc. !
As an example (and referring to FIGURE 3), the chip can be interfaced with user
peripherals such as an authentication unit 62, analog/digital conversion
circuitry 64 for voice in/output, data terminal equipment 66 such as a keyboard i
I
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! ¦
lZ3~7~7~
I to or wit trout do splay or a graphics digitizing pad, and a it me do splay 68. (As
indicated, the unit is also powered with its own high reliability battery 70.) If
user requirements exceeding the normal MISS capability, but not exceeding the
MESH specification, are to be accommodated, additional external equipment can beadded, as shown in FIGURE 4 -- such as a multiplexer-demultiplexer I for
multi-channel operation, crypt equipment 74 to provide for data security, a
coder/decoder 76 to improve error rate and, if needed, an interface 78 to make
non-MESH hardware compatible with the ASH input/output circuit.
In operation, and referring to thy flow diagrams of PHARISEE 5-10 --,
when sufficient battery charge is sensed by the charge sensor 40 of FIGURE 1,
appropriate power is supplied to the processing circuitry there shown and the
functions are initialized, switching "on" the central processing unit 10, its
peripherals and the receiver indicated, also actuating the system monitor and
clearing the various counters and buffers. The central processing Kit then
checks the receiver output for incoming Calls (KIWI?). If a call is received !
(500) the central processing unit then checks whether the call came from a validsource (OLD SAC?), i.e., whether the authentication code in the header of the
unit is correct. If that is not the case, the central processing slit then
I, returns to label 400, to await an authentic incoming code signal. Upon reception
20 11 of a valid incoming Cole the central processing unit checks for mode
,1 1
,, .
If ,
,
',
!
.
- 1 o -
If ~.Z3~
information in the header (M), and in the event of rode branches, couples
it to label 3000 (see FIGURE 9). The some sequence occurs if the next check
(carried out in the unit BUY MTY?)shows that there are untransmitted message
units or packets (P) in the R3-mode buffer, indicating that the buffer is not
empty.
However, if the buffer is indeed empty, the next question in the flow
diagram is whether the message units have been handled before and its header
(H) is therefore stored in memory I. If is found in I (label 700) and the
incoming H does not have an acknowledge request code (NO 2) in its network
function field, the program then branches back to the label 400 to check again
-- otherwise, it will check if the old H in I already contained the acknowledge
request OF 2) function. If an H is found in M, and an acknowledge request
NO 2) is located, a branch to label 400 occurs (NO 2 being able to override
"H in I only- once). If no 2 was in the stored H, the present H containing
NO 2 will override the stored H (H -if M), and the program then continues at
label 1000 (FIGURE 6). With a negative "I in M" test (label 900 in EI~JRF. 5),
a further test (H in V) reveals whether the message header (H) is held in a
temporary register (V). In the negative case, the incoming is written into
V, and a counter is set to a maximum allowed for incoming Koalas (SO CUR).
This leads to label 950, which is followed by decrementing the COWAN in counter
once, and a return to label 400.
If, on the other hand, H was already in the register V, the OAKEN count
or is tested (KIWI CUR = 0?). If it is 0, a branch to label 1000 occurs, other
wise label 950 is reached. If the CQI-test was negative (label 600), a test
would have been made whether the message header (H) was held in the temporary
register V (H in V?). If the test turned out negative, branching back to 400
occurs. In the affirmative case, H was received before, and an additional
test determines whether too much time (MOE?) elapsed since the last KIWI, then
label 650 is reached, but if not, return to label 400 occurs.
At label 650, it still nut be tested whether the mode required in the
lZ3`778
header (H), as held in the register (V), is the wide-path random walk (R2?~.
In the affirmative case, label 800 is reached after storing the V-content in
an appropriate location in memory My=); in the negative case, label 800
is reached immediately. After that, V is cleared (CUR V), and the program
returns to label 400.
Lo Flume 6, at 1000, the present reading of the real-time clock (RTC)
is written into the appropriate H-field in the V-register. Then the V-cantent
with an acknowledge CQ-NF3 functional code inserted is transmitted (CQ-acknowl-
edgement). The next decision point is reached (in practice after a suitable
time delay), when a test is made whether H, as transmitted between labels 1000
and 1100, together with P and a send-P function NO 5 have been received (P/NF 5
LO?). If this is not the case, the program tests for a request for random time
delay CON 4 LO?). East of such a request causes a random wait beginning
at the present RTC-time (Eureka + DEL), followed by a return to label 1000. If
no NF-4 "delay request" was received test is made whether the present PUG
time minus the time at which OF 3 was sent exceeds a ~ximum (RTC-TV IVY.
If this is affirmative, it is assumed that the service-requesting SUE
unit selected another MISS unit to handle its message packet and the program
returns to 800; otherwise, the V/N~F 3 - transmission, etc. is repeated by no-
turrlin~ to label 1100.
If the (P/NF 5 IN?) test result was affirmative, i.e., that the message
packet (P) is then in this 'ASH units P-buffer, label 1200 was reached Lowry
the hop count (I) in the header (H) is incremented by 1 (I = I + 1). If the
new I then equals the m~cu~im (I = MY.?) specified for this Misfiled, fur-
then P-travel will be prevented. As will be understood, it is only necessary
to test whether D2-service was requested (Do?) -- where user units, i.e., data
terminals (D) have assigned, e.g., alpha-numerical identifiers which can be
changed as required, and which are needed to identify source (Do) and destine-
lien (Do) of a message message omit or packet UP) in the n~ssage header (H).
he pr~gr~n coos into the batcery-che rut m e (2600) if this was not the gas
i
1~3'7~
-- otherwise into (1250) --, where it will notify the previous MISS unit of
a lost packet (P) by transmitting V/NF 8 first, and then run the battery check
According to the program, a battery check is always performed at the end of a
program loop, if that program segment contained steps involving high battery
drain, i.e., operation of the transmitter.
IJithout an affirmative DMAX-test result (1300), it is still necessary
to test for D2-service. If no (Do) message destination is requested, Precept
lion can then be acknowledged TV 6), otherwise this is postponed. The next
steps store the V-content in M, inserting the NO 1 "sending CQ function" into
the register (V)(1400) and setting the transmit-CQ counter (SEC CUT prior to
reaching label 1500.
At label 1500 (FIGURE 7), the ASH unit begins its attempt to transfer
the packet (P) to the next MISS unit (designated Us, with its V-register design
noted as V2). The first MISS unit (U) transmit a Cole (VNF 1) once, decree
vents the Kowtow counter DO OKAY CUR), waits pharaoh a signal-round-trip time
(not shown) and then tests for reception of a CQ-ackncwledg~ment (V2/NF 3 r1?)
which could come in after the first Call provided Us was identical with
I the addressee (label inn FIGURE 7). Usually, this will not be the case
all the program will branch to label 1600 (FIGVR~ 8). If, however, label 2000
was reached, the V2 (the if with Use RTC-time) is stored in V and toe transmit-
P counter is set (SUP CUR). At label 2100, P with the V-ccntent and NO 5
"send P" function is transmitted (P + V/~JF 5) and the P-out decrement Ed once
(DEW PO CUR) to reach label 2200 where a test is made for P-acknowledge~ent
(V2/NF 6 I If this is affirmative (label 2500), I must be checked again.
If it was requested, P had not been acknowledged between labels 1300 and 1400
and must be acknowledged now (V/NF 6), followed by a WriteNow to the battery-
check routine 2600.
A negative V2/MF 6-test result (label 2300), an the other hand, require
a test whether repeat of P-transmission was required by Us (V2/NF 7 IN?), in-
dilative of a repeat of the packet (P) requested. The affirmative case simply
Aye
results in a return to label 2100, but in the negative case (lube]. 2400), the Pout counter is checked (PO CUR = 0?). If it is not zero yet, then return
to label 2100 occurs. If the noisomely permissible number of P-transmissions
has been exhausted, then the program will either return to the battery check
routine 2600 or, in the D2-case, notify the previous ASH unit of a lost packet
(P) (label 1220, FIGURE 6).
The case of the negative V2/~ 3 - test result (label 1600) is shown
in FIGURE 8. A test is made whether a V2, garbled by another carrier, has
been received ((V2)/CS run?). This would require a delay request (NO 4) in the
register TV an a return to label 1400 (FIGURE 6). If nothing has come in
(label Thea O?O-counter is checked -- and if it has not yet Len down to
zero, return to label 1500 is indicated. If it is zero (label 1300), it is
necessary to test for the NO 2 "acknowledge request", i.e., whether an ac~lowl-
edge-request series has been transmitted previously. If this is the case, the
program returns to label 1220; and, if not, then the NO 2-request is inserted
into the register (V), the Kowtow counter is set to a n~ber adequate for 2
-transmissions, and the program returns to label 1400.
An R3 service request or unfinished R3 business diverts the progrc~n to
label 3000 (FIGURE 5), continuing it from there, as shown in FIGURE 9, where
first the memory is searched to determine whether it contains .'~ of the in-
coming call (!~ DUN I?). If this is the case, the program returns to label 400
of FIGURE 5. A negative test result (label 3100, however) requires a check
whether the padcet (P) is held in the P-buffer. If P is fund in the buffer,
it was not errOrfree and the incoming copy of P is used to correct errors in
the previous copy. If the message packet (P) was not yet in the buffer (3200)
on the other hand, and there is still space in the buffer, P is read into the
buffer (3300). If, however, the buffer were full (BUY FUR?), then the inks-
in message packet (P) cannot be handled at this time, c1nd the buffer address
of the P that has been in the buffer the longest is pointed at by a transmit-
flag (XFL) register AL TAX) ion idiot ire stussicn, by label 3600
~23''77~)
, I .
If label 3300 was reached, and there is a message packet (P) in the
Buffer for which the error detection is zero (ED = 0?), the "XFL" flag is set topoint at that packet (P) (3400), followed by the label 3600.
If all P in the buffer contain at least one error (at unit 3500), a
test is then made according to the program, whether one of the P has reached themaximally pennissible storage time (TAX ?). In the affirmative case, the header(H) of that packet (P) is then marked with an error flag (ELF - H) and "XFL" flag¦
set to point to its address, followed by the label 3600. A negative Attest
Returns the program to the point 400 of FIGURE 5.
I The Retransmission sequence begins at point 3600 in Flyer 10, with a
single transmission of the header (H) us pointed to by the "XFL" flag. After
that, the transmit counter (XMr CUR) is set (SEX CUR) and the buffer content
indicated by "XFL" is transmitted US (XFL)). Then, the transmit counter is
checked -- and, if it is zero, H is stored in memory (~) and the progr~n
continues to label 2600. If the counter is not yet zero, it is decrement Ed once
(DEW CUR) and the transmission repeats itself again.
As will thus be seen, and as will be understood by those skilled in the
art, the MESH system elements thus perform the following functions:
a. In the recruiting mode, the elements receive incoming signals and
validate them according to their identifying and control code (the latter
indicating a recruiting signal). Depending Oil the quality of the cleanly (e.g.noise, attenuation, multi-path distortion, etc.) between the signal source and
the receiving unit, a certain number of calls would be required before enough
error-free signals would match the count in the preset counter of the unit.
''
! I
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-15- 1
,,"
~3`7'~
rho system element wall then issue an acknowledgement to the calling station,
thereby silencing it, and will start transmitting call signals of its own.
b. In the communicating mode, on the other hand, the system
element will relay only messages from terminal stations which were the
originators of the original calling chain. However, it will accept and
acknowledge recruiting calls from the other terminal stations involved, provided
their call is addressed to one of the terminal stations of the Issue unit in
question. The system element will thus store addresses of all terminal stations
l with which it communicates.
if On the other hand, the So unit operates upon the receipt of a proper
command, and in response, will switch its code generator to any other code and/or
change its preset counter number as the case may be. In such instance, if the
system element in the communicating mode then attempts to relay a message to the
next system element in the network, and that unit does not acknowledge the
address, the transmitting system element will notify the message originator of a
break in the chain, and then switch to its recruiting mode.
Message routing in the ESSAY system is thus determined by the operating
mode of its individual unit. Such mode can be selected from a menu, according id
tithe invention, in firmware by the appropriate code in the header (H). Two basic
20 Al code schemes according to the invention can be identified as the "random walk"
(Al) and the broadcast mode (K3~ -- but can be modified further by a "wide-path"
random walk (R2) and a form of end-to-end control for Al and R2 by an automatic
message acknowledgement according to message destination and source
llidentification (DO, Do, respectively), resulting in routing schemes Al, Do and
;~R2, DO, for example.
Al The user's data terminal equipment, D, allows for the selection of one
.,
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_ 1~3' i''7~0
¦ operating de from a series available to that particular user, thereby giving¦ a greater choice of operating modes to a higher-priority user than to a lower-
¦ priority user. The terminal equipment (D) will then place an operating code,
¦ OPT, into the designated field which identifies the routing scheme correspond-in to the operating mode under which the message (P) was issued. Such code
¦ can be appended by a sufficient number of bits to identify various network
management functions (NO) such as pa) Send CQ; (b) Acknowledge Pickiest; (c)
Acknowledge CQ; (d) Delay Request; (e) Send P; (f) Acknowledge P; (g) Pickiest
l Repeat of P; and oh) Loss-of-P Notification in D2-Mode.
¦ In this manner, the Al and R2 modes support P-travel within a ASHfield from one originating data terminal (D), i.e., Do, to one destination (Do)
via a random walk that links Do to a succession of MESH units terminating in
Do. P-transfer is initiated by Do by means of repetitive Koalas which con-
sit of H with the appropriate operating code (OPT). Any neighboring IFS
unit that is not busy with other tasks will then receive the CQ and compare
incoming H-fields with its own stored validation and authentication codes.
The process then repeats until a MESH unit achieves a predetermined number of
matches, which could either be part of the header information or stored in
firmware. The number of required matches serves as a threshold for ~4-ackn~l-
edgement from the ASH unit. Since that unit which receives the Calls with
the least interference, attenuation and delay will acknowledge them first, the
message will be made to travel over the best available channel, from the oft-
jointing unit (Do) to its so-linked neighbor. Acknowledgement then consists
simply in a retransmission of the header by that neighboring unit, along with
the network function indicating ackncwledp,ement plus the neighboring unit localtime of retransmission. Reception of an acknowledgement thus causes the
originating ASH unit to terminate its Killing sequence, King it impost-
isle for most other neighboring MUSH units to reach their thresholds for in-
coming Koalas If, however, more than one Masonite has reached the C?
threshold, they will then compete for the same message packet by acknowledgit~
l 1~3'^~
the CQ.
But, in accordance with the present invention, there exists three lea-
lures in the N and R2 modes to help break such a contention case between
neighboring So units -- (l) Carrier Sense Multiple Access (COMA); (2) Local-
Time Tag; and (3) Random Acknowledgement Delay.
KIWI is used in the MESH units of the invention, and operate in such a
way that a transmitter at an originating location or at a neighboring location
can be switched on only after the receiver of that particular unit was unable
to detect any other carrier on the air. Depending upon propagation delays be-
tweet the originating unit and contending SUE units, SHIM may be sufficient
to break acknowledgement contention. however, if neither of the contenders
did detect the other's carrier in the time required to block their own trays-
mission, they may acknowledge about the same time. Since each acknowledgment
will be supplemented by the local time of the acknowledging SHEA unit, and
these times are highly unlikely to be the same, the received acknowledgements
can be ascribed to particular MESH units by the originating system element,
providing the original unit's processing time is less than the difference in
arrival times between acknowledgements. In this case, the message would be
addressed to that MESH unit whose acknowledgement arrived first, i.e., the
message would be transmitted with the header supplemented by the local time of
the addressee. Any contending So unit would then refuse to handle the mess-
age packet by simply ignoring it.
If acknowledgements arrive at the originating unit so close within each
other that there is not enough processing time to read and separate the local
times, the acknowledgements will then tend to destroy each other. In this case,
the originating unit will send a repeat CQ according to the invention, this
time with the management function NO indicating a random delay request. Con-
tending message units receiving this CQ will then wait a rundown time interval
before attempting acknowledgement. The entire process then repeats until con-
tenders are separated either by COMA, or by local-time differentiation. After
; -18-
I 3 7 To
that, the originating unit will send its message packet to the first ISSUE unit
in time, which then can be assigned a designation (Us), the originating unit
having the designation (Do).
(In the R2 mode, all MESH units use) which received a copy of the I
but did not become Us would store I and from then on, Rufus handling a P be-
longing to the header (~) .)
After Do has transmitted its message packet to Us, it has completed its
task, and Us would then attempt to dispose of that message packet by repeating
all of the previously described Dl-functions, i.e., the message packet (P)
would be handed to another Ho unit (U) become Us. At that time, Us would
have stored H which prevents it from reaccepting that particular packet (P).
The packet (P) tlould then travel from Us to Us, and so on, ctlong a path which
resembles a "random walk". As will be appreciated, the loop cannot come back
on itself, because no previous handler of the message packet (P) will handle
it again, with one exception -- which may arise when P travels towards the
edge of the SHEA field in such a way that it wiped out all return possibilities
behind it: in that case, the Koalas of the ?IEShT unit nearest to the field
edge will not elicit an acknowledgement, and only then will the MOE unit place
an acknowledge request into the NO field and reissue Koalas Such "acknowl-
edge requests" will override the rehandling refusal in any previous Ml~:S~I unit,
with the packet (P) then traveling from Us to fin I whereupon Us 1 removes
the "acknowledge request" and tries to pass on the packet (P) in the usual way.
If this fails, an attempt will be made to reinstate the acknor.Tledge request,
etc. According to the construction of the units in the block diagram strikeout
any I unit that has handled a packet twice will be prevented from handling
it a third lime under any circumstances, so that the packet (P) us forced away
from the edge of the flesh field.
wherever a Cole is received by a data terminal for which it is desk
lined (Do), then that terminal will acknowledge the I irlmediately in order to
l terminate the message packet -travel.)
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SUE
According to the invention, the message header (~) also has a field for
the accumulative hop count. This is a number which is incremented every time the
message packet (P) is received by a MY unit (U). Another field in the header
(H) contains a number which determines a maximal hop count. whenever the
accumulative equals the maximal hop count, no further I will be issued by the
receiving hush unit, so as to assure that the packet which does not reach the
desired destination after a number of trials will be deemed unreasonable for the ¦
size of the MESH field, and will be abandoned. If the packet priority warrants
Kit, a Deporting mode can be included to notify the originating unit of the
lost packet, which could then be retransmitted, and in a R3-mode.
Such R3-mode is a broadcast one in which the message packet exhausts
all the resources of the ASH field once. In this mode, it is virtually
impossible for an existing intended destination not to be reached by the packet,
and is very useful for reaching classes of destinations, i.e., all binary digits
within the field so as to sub-divide the class. In this mode, the originating
unit only issues a single Call to initiate all neighborir~, unoccupied MUSH
units to the R3-mode. This is followed by repeated transmissions of 11-P
sequences, which are to be accepted by each Howe unit in the mud, putting it
lint a buffer. Each unit would continue accepting the packet (P) until all
terrors are corrected, or no further packets (P's) are received. it that time,
the MESH unit would store the header to bar rehandling of the packet (P), and
proceed as Do, the originating station, did before. In this fashion, the message
, packet will travel as a single expanding ring around the originating station, an
will even travel backwards if a MY unit has been missed, either due to an
obstacle or because of temporary non-availability. Such feature makes it
possible, therefore, for two or more, P-rings to penetrate without annihilating
teach other. Only at the boundaries of the ESSAY field, would such P-ring be
destroyed
As thus described, certain advantages will be definitely seen to exist
I Jo
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if l
~L'Z3~77~
- I utilizing the cwn~unicaticns system of the present invention. First, the soys-
tern will be seen to be a totally probabilistic one in every respect, consisting
of a set of system elements of which only a subset, c~eterrnined by the product
lion yield in that particular set, would be operational at any given time. A
still smaller subset, determined by battery-charge conditions and message-
traffic loading, would be taking part in system functions. ~11 system elements
temporarily or permanently not engaged in system activities, would still act as
decoys to foil search and collect operations.
Secondly, direction finding, or tracing, of cc~nunication paths will be
seen virtually impossible due to the random and continually changing disturb-
lion of active system elements. terminal stations will be seen not to have
any specific signature which could allow one of them to be distinguished from
the system elements being used.
Also, the line-of-sight operation introduces no detrimental effect
since all line-of-sight obstacles simply act as supports for the system eye-
mints, thereby proving a disadvantage to a potential jammed. ~ltipath effects
will be seen to result in negligible multi path spread, as well, due to the
short average distance between system elements in operation. In because the
transmitter power of active system elen~nts is so low as to be nearly India-
tinguishable from a widely dispersed low-power-random-noise source, convention-
at systems that operate in the same geographical area will experience only a
slight raise in background noise which is not likely to interfere with their
normal function. Conversely, a strong conventional emitter within the ASH
field, operating in the same frequency band, would incapacitate only a relative
lye small number of SUE units. message traffic jollied simply route itself crane
the disturbance.
s will be apparent, the ASH construction is eminently suitable for
communications and control in geological and jungle exploration, mining opera-
lions, explosives removal, nuclear and toxic removal and clean-up operations,
fir ghting, etc. It it a desirable system for disaster preparedness em d
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for establishing c~nmunications during an emergency and after a disaster has
occurred that wiped out all conventional means of communications. Necessary
terminal stations, not larger than a wrist watch, can easily be airdropped
together with the ISSUE units, e.g., by dangling them from small marker pane-
chutes or long, brightly colored ribbons on which could be printed the open-
a tying instructions. SUE terminals could be dispensed as part of survival
packages for sea and air travel and transport crews, forest and park rangers,
etc. ILSH is also particularly suitable for all purposes where the user must
not be encumbered by clumsy equipment or restricted in his movements by line-
lo of-sight requirements. It is an ideal system for the communication Thea, and
control of, autonomous or semiautonomous robots.
Intelligence and reconnaissance operations in hostile territory could
similarly benefit according to the system of the invention -- as an operator
in enemy territory is only called upon to use a transmitter with extremely
low output power, just sufficient to enter the nearest neigliboring So unit.
Interception of such ITCH communication, however, would give no clue as to the
location of the terminal station, as previously indicated. And, to prevent
"spoofing" -- i.e. an unauthorized entry into the system --, the terminal stay
lions can be linked to vital functions of their carriers in use in the commune
cations network -- such as to a biological-electrical signature, in the nay
lure of electrocardiogram, electroencephalogram, or other available identify-
in indicia, so as to grant access to the system only to authorized users.
Cryptosecurity can be introduced rather easily either by storing enough crypt
tokens in a read-only memory of each unit, where, e.g., the message n~ber
could determine the key selection, or by conventional means eta m at to the
ASH system. Code brealcing attempts would take longer than the life time of
a particular SUE field.
initial charging of the batteries could be accomplished inductively
through the deployment container by replacing the connection to the solar
battery with a connection to an inductive antenna loop via a rectifier diode.
.1
I -22-
I 1~3'7~U
Upon deployment this connection could be broken, erg., by an air-triggered
exothermic chemical reaction which would also fuse the battery terminals to
the solar battery. This same action could be used to initialize the system
units and synchronize their clocks.
While there has been described what is considered to be a preferred em-
bodiment of the present invention, it will be readily appreciated by those
skilled in the art that modifications may be made without departing from the
scope of the teachings herein. For at least such reason, therefore, resort
should be had to the claims appended hereto for a correct understanding of the
'I in
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