U.S. patent application number 10/449455 was filed with the patent office on 2004-12-02 for non-interfering multipath communications systems.
Invention is credited to Neilson, Paul Christian.
Application Number | 20040242249 10/449455 |
Document ID | / |
Family ID | 33451790 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040242249 |
Kind Code |
A1 |
Neilson, Paul Christian |
December 2, 2004 |
Non-interfering multipath communications systems
Abstract
A non-interfering multipath communication technique establishes
a base transmit and receive period for a variety of spaced apart
transceiver devices of a base station and communicates between at
least one field station and the base station through those
transceiver devices; a period of the base station is allocated
amongst the transceiver devices to maintain the non-interfering
multipath communication between the at least one field station and
the base station.
Inventors: |
Neilson, Paul Christian;
(Salem, MA) |
Correspondence
Address: |
Iandiorio & Teska
260 Bear Hill Road
Waltham
MA
02451-1018
US
|
Family ID: |
33451790 |
Appl. No.: |
10/449455 |
Filed: |
May 30, 2003 |
Current U.S.
Class: |
455/502 |
Current CPC
Class: |
H04W 88/08 20130101;
H04W 72/082 20130101; H04W 16/14 20130101; H04L 1/188 20130101;
H04W 72/0446 20130101; H04W 56/00 20130101 |
Class at
Publication: |
455/502 |
International
Class: |
H04B 015/00 |
Claims
What is claimed is:
1. A non-interfering multipath communication system comprising: a
base station having base transmit and receive periods and including
a plurality of spaced apart transceiver devices; at least one field
station for communicating with said base station through a said
transceiver device during said periods; said base station including
a controller device for allocating said periods amongst said
transceiver devices to maintain non-interfering multipath
communication between said at least one field station and said base
station.
2. The non-interfering multipath communication system of claim 1 in
which said base station includes a base clock circuit for defining
said base transmit and receive periods and said field station
includes a field clock circuit for defining field transmit and
receive periods and at least one of said clock circuits generates a
sync clock pulse to synchronize the clock circuits with each
other.
3. The non-interfering multipath communication system of claim 1 in
which said field station and said transceiver devices communicate
via conductors.
4. The non-interfering multipath communication system of claim 1 in
which said field station and said transceiver devices communication
via electromagnetic radiation.
5. The non-interfering multipath communication system of claim 1 in
which said field stations include at least one of a sensor
transducer and an actuator transducer.
6. The non-interfering multipath communication system of claim 1 in
which said controller device includes means for allocating said
transmit periods to said transceiver devices randomly.
7. The non-interfering multipath communication system of claim 1 in
which said controller device includes means for allocating said
transceiver periods to said transceiver devices in a predetermined
order.
8. A non-interfering multipath communication method comprising:
establishing base transmit and receive periods for a plurality of
spaced apart transceiver devices of a base station; communicating
between at least one field station and said base station through
said transceiver devices; and allocating at least a said transmit
period of said base station amongst said transceiver devices to
maintain non-interfering multipath communication between said at
least one field station and said base station.
9. The non-interfering multipath communication method of claim 8
including establishing field transmit and receive periods for said
field station and generating a sync clock pulse to synchronize the
clock circuits with each other.
10. The non-interfering multipath communication method of claim 8
in which said transmit periods are allocated to said transceiver
devices randomly.
11. The non-interfering multipath communication method of claim 8
in which said transmit periods are allocated to said transceiver
devices in a predetermined order.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a non-interfering multipath
communication system.
BACKGROUND OF THE INVENTION
[0002] Monitoring and control systems such as used to supervise
processing plants and manufacturing processes and machines have
become a critical part of operations. A report of an unsafe or
hazardous condition can shut down an entire facility operation
resulting in huge costs and delays. Wired systems often use
redundant conductor paths from the field station sensor/actuators
to the base station to avoid incorrect signals or total loss of
signals due to accident or failure. Wireless systems have become
much more appealing due to their lower installation cost and ease
of installation and redeployment. One problem with wireless and
even wired systems is that if anything interferes with the delivery
of the signal from the sensor/actuator transducer at a field
station faulty reports or even worse no reports can precipitate a
variety of unnecessary effort before the true situation can be
determined. Redundancy is always a solution but often it adds to
the complexity and power required as well as to the cost.
BRIEF SUMMARY OF THE INVENTION
[0003] It is therefore an object of this invention to provide
improved non-interfering multipath communication system.
[0004] It is a further object of this invention to provide such an
improved non-interfering multipath communication system which is
simpler and more power efficient.
[0005] It is a further object of this invention to provide such an
improved non-interfering multipath communication system which is
more reliable, faster and more robust.
[0006] If it s a further object of this invention to provide such
an improved non-interfering multipath communication system which
continues communications between a field station and base station
even when some paths are blocked.
[0007] If it s a further object of this invention to provide such
an improved non-interfering multipath communication system which
provides redundancy at little cost compared to wired systems.
[0008] If it s a further object of this invention to provide such
an improved non-interfering multipath communication system which
simplifies the identification of the point of failure.
[0009] The invention results from the realization that a truly
effective non-interfering multipath communication system can be
achieved by establishing base transmit and receive periods for a
plurality of spaced apart transceiver devices of a base station,
communicating between at least one field station and the base
station through the transceiver devices and allocating at least a
transmit period of the base station amongst the transceiver devices
to maintain non-interfering multipath communication between the at
least one field station and the base station even when some paths
are blocked.
[0010] This invention features a non-interfering multipath
communication system including a base station having base transmit
and receive periods and including a plurality of spaced apart
transceiver devices. There is at least one field station for
communicating with the base station through the transceiver devices
during the periods. The base station includes a controller device
for allocating the periods amongst the transceiver devices to
maintain non-interfering multipath communication between the at
least one field station and the base station.
[0011] In a preferred embodiment the base station may include a
base clock circuit for defining the base transmit and receive
periods, and the field station may include a field clock circuit
for defining field transmit and receive periods and at least one of
the clock circuits may generate a sync clock pulse to synchronize
the clock circuits with each other. The field station and the
transceiver devices may communicate by conductors or via
electromagnetic radiation, such as rf. The field stations may
include at least one of a sensor transducer and an actuator
transducer. The controller device may include means for allocating
the periods to the transceiver devices randomly or in a
predetermined order.
[0012] The invention also features a non-interfering multipath
communication method including establishing base transmit and
receive periods for a plurality of spaced apart transceiver devices
of a base station and communicating between at least one field
station and the base station through the transceiver devices. A
period of the base station is allocated amongst the transceiver
devices to maintain non-interfering multipath communication between
the at least one field station and the base station.
[0013] In a preferred embodiment there are established field
transmit and receive periods for the field station and a sync pulse
is generated to synchronize the clock circuits with each other. The
transmit periods may be allocated to the transceiver devices
randomly or in a predetermined order. There may be established
field transmit and receive periods for the field station and there
may generated a sync clock pulse to synchronize the clock circuits
with each other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Other objects, features and advantages will occur to those
skilled in the art from the following description of a preferred
embodiment and the accompanying drawings, in which:
[0015] FIG. 1 is a schematic block diagram of a non-interfering
multipath communication system including a base station with a
number of remote spaced apart transceiver devices including a base
station and a plurality of field stations;
[0016] FIG. 2 is a more detailed schematic block diagram of the
base station of FIG. 1;
[0017] FIG. 3 is a more detailed schematic block diagram of the
field station of FIG. 1;
[0018] FIG. 4 is an illustration of the sequence of signals between
base station transceiver devices and a field station;
[0019] FIGS. 5 and 6 are a flowchart showing the method of
operation of a field station according to this invention; and
[0020] FIGS. 7 and 8 are a flowchart showing the method of
operation of the base station transceiver device according to this
invention.
DISCLOSURE OF THE PREFERRED EMBODIMENT
[0021] Aside from the preferred embodiment or embodiments disclosed
below, this invention is capable of other embodiments and of being
practiced or being carried out in various ways. Thus, it is to be
understood that the invention is not limited in its application to
the details of construction and the arrangements of components set
forth in the following description or illustrated in the
drawings.
[0022] There is shown in FIG. 1 a non-interfering multipath
communication system, 10, according to this invention, including
the base station, 12, having a controller, 14, and plurality of
remote transceiver devices, 16a, 16b, 16c, 16d, 16n, which
communicate with a plurality of field stations, 18a, 18b, 18c, 18n,
the communication between transceiver devices, 16a-16n and field
stations 18a-18n may be rf as indicated by the antennas 17a-n and
19a-n, respectively, in FIG. 1 or it may be by solid conductors
such as coaxial cable not shown for clarity.
[0023] Controller 14, includes CPU 20, FIG. 2, and memory 22, which
includes stored program data. Also included in controller 14 is
clock circuit 24 which operates in conjunction with the similar
clock circuit in each of the field stations to synchronize the
operation of the system. An external interface 26 is provided to
enable the CPU 20 of controller 14, to transmit to and receive
information from the world outside of system 10. Each field station
as indicated by field station 18a, FIG. 3, also includes a CPU 30
and a memory 32 which includes stored program data and a clock
circuit 34. A transceiver 36 with antenna 19a is provided to
broadcast the information from CPU 30 and to receive information
from the base station for CPU 30. Field station 18a also includes a
transducer 38 which may include an actuator: for example, for
operating a valve, switch, or a sensor for monitoring temperature,
pressure, weight, ambient light, or any other parameter.
[0024] In operation CPU 20 in controller 14 provides a succession
of acknowledge sync signals from transceiver device 16a-16n which
is delivered to the one or more field stations 18-18n. As shown in
FIG. 4, the base station sends out an acknowledge sync signal at
time slot 50 to the first field station 18a, at time slot 52 to the
second field station 18b, and so on. For this example the
acknowledge sync signal explanation of base station operation is
just with respect to two field stations in order to simplify the
description. After the acknowledge sync signal has been sent out
from remote transceiver device A at times 50 and 52 to field
stations 18a and 18b there is provided two corresponding time slots
54 and 56 during which field station 18a and 18b respectively, can
respond with their status. Following this an acknowledgement sync
signal will be sent out from remote transceiver device B, 16b to
field station 18a in slot 58 and to field station 18b in slot 60.
Following this the base station provides two time slots, 62 and 64
for field stations, 18a and 18b to respond with their status.
Following this controller 14 enables remote transceiver device C,
16c to send an acknowledged synchronized signal in time slot 66 to
field station 18a, and in time slot 68 to field station 18b.
Following this, two time slots, 70 and 72, are provided for field
station 18a and 18b, respectively, to respond with their status.
Assuming there are only three remote transceiver devices A, B, and
C, 16a, 16b, and 16c, the base station would then return to slots
50 and 52 where it would cause remote transceiver device A, 16a,
again to send out acknowledge sync signals to field station 18a and
18b, respectively. Although the description is limited to just
three transceiver devices A, B, C, namely, 16a, 16b, and 16c, and
two field stations, field station 1 and field station 2, 18a, and
18b, this is not a necessary limitation of the invention, as any
number of remote transceiver devices and field stations may be
employed. In addition, although the acknowledge sync signals are
sent out in order A, B, and C, this is not a limitation of the
invention, as any order, including random order may be imposed by
CPU 20 on the issuance of the acknowledge synchronize signals and
the time slots for replies.
[0025] During the aforementioned operation of the base station,
each field station as exemplified by the following description of
field station 1, 18a, is going through one or more of the following
operations. Assuming for purposes of discussion that we are
discussing field station 1, 18a, it might be in a standby condition
where it is monitoring the condition of the sensor for example. If
during that monitoring period the field station determines that the
synchronism of its clock 34 with the clock of the base station 24
is slipping, it will turn on and seek to find an acknowledge sync
signal. Since it turns on at point 80, well after the acknowledge
sync signal has been sent at 50 and 52, it awaits the next
acknowledge sync signal at 58, 60, at which time it once again
synchronizes its clock, 82, with the base station and returns to
the monitoring state 84.
[0026] Alternatively, while the field station is in a monitoring
condition, 86, it may be triggered by either a sensor event or a
so-called "watch dog" event. A watch dog event occurs simply
because the timer has been set to force the field station to
communicate after a certain period of time, even if it has nothing
to say, just to ensure that it is still operative. Thus, either a
sensor event or a watch dog event triggers the field station at 88.
Assuming at this point that it has synchronism between its clock
circuit and that of the base station, it waits until its slot 62
becomes available, and transmits and then waits 92. Then turns its
receiver on at 94 and receives an acknowledgement 96 that its
transmission 90 has been properly received. It then returns to the
monitor state 98.
[0027] Alternatively with the field station once again in a
monitoring mode 100 waiting for a sensor event or a watch dog
event, a trigger occurs at 102 after which the system waits for its
slot to transmit at 104, and then waits again at 106. But now it
receives nothing back at 108 because the path between this
particular field station and the transceiver device, C, 16c, is
blocked. At this point the field station waits again 110, then
transmits once again in its own slot 112 and waits again 114. Now
it receives an acknowledge sync from transceiver device, B, 16b,
instead of C, 16c and since the message has been received at 118
the system goes back to the monitoring state at 120. Thus, any time
the path between a field station and a particular one of the
operative transceiver devices, 16a-16n is blocked, the field
station will simply recycle and attempt to retransmit until it
finds a path to at least one of the transceiver devices, 16a-16n,
so it can communicate fully with the base station. Although the
explanation of field station 1, 18a in FIG. 4, has been made with
respect to it containing a sensor only, it may contain a sensor and
an actuator or just an actuator. If the actuator is the active
component, at the moment, then during those time slots such as 54,
56, 62, 64, 70, 72 when the station is sending back the sensor
information, the converse would occur. That is, the base station,
during those time slots would be sending information to cause the
operation of the actuator.
[0028] The operation and method of this invention is shown with
respect to field stations in FIGS. 5 and 6 and with respect to the
base station in FIGS. 7 and 8. Initially, the field station
monitors the sensors, its watch dog clock and its own synchronous
clock, 150, FIG. 5. If the field station synchronous clock has
expired, 152, the field station will wait until the base
acknowledge sync signal is expected 154 and then turn on the field
transceiver 156. It then listens until the base acknowledge sync is
received 158, where upon it re-syncs the field station sync clock,
160 and then returns to the monitoring of the field station sensor,
watch dog clock and sync clock in step 150. If in step 152, the
field station sync clock is ok, the system goes directly to step
162, where it queries whether the sensor has been triggered or the
watch dog clock has expired. If it has, then the system waits till
the field station slot is available, 164, transmits its status 166,
waits until the acknowledge sync time occurs 168 and then receives
the acknowledge sync 170. If the sensor trigger has not occurred
and the watch dog clock is not expired in step 162, the system
simply returns to monitoring the field station sensors, watch dog
clock and sync clocks in step 150. After the acknowledge sync has
been received in step 170 the query is made as to whether the
acknowledge sync was received in good form, in step 172. If it was,
the synchronous clock is resynchronized 174 and the system waits
until the acknowledge sync status time occurs 176 and then it
receives the acknowledge sync status in step 178. If then the
acknowledge status is bad in step 180, or if the acknowledge
receipt failed in step 172, the system increments the count of
failed messages, 182. If in step 184 the failed message count
equals the maximum, the sensor trigger is cleared 186 and the watch
dog clock is reset 188. If in step 180 the acknowledge status is
ok, then the failed message count is cleared in step 190. If in
step 184 the failed message count is less than the maximum, the
system returns to wait until the field station slot is available in
step 164. After the watch dog clock is set in step 188 the system
once again returns to monitor the field station sensors, watch dog
clock and sync clock in step 150.
[0029] The method and operation of the base station begins with
selecting the active base station remote transceiver via a random
or pre-selected sequence method, 200 FIG. 7 and then sending an
acknowledgement on the selected remote transceiver 202. The base
station then listens on all remote transceivers for incoming field
station status, 204. Each field station status is then parsed as
received by each remote transceiver using error checking codes 206.
Then for each field station 208 there is selected all the field
station statuses received by each remote transceiver for each field
station 210. If any particular field station status is error free,
then an acknowledgement is marked ok, otherwise the acknowledgement
is marked failed 212. Then all of the statuses received for that
particular field station are compared and if they are identical to
the error free status, the path is indicated as ok, otherwise this
path may be identified as one which is blocked or in which there is
some sort interference that needs to be addressed 214. The system
then returns in step 216 to step 208 to perform this loop for the
next field station, after first incrementing, in step 218, the
number of the field station. If in step 216 the maximum number of
field stations has been reached the system returns to step 200
where the base station selects a remote transceiver according to
some random or pre-selected sequence method.
[0030] Although specific features of the invention are shown in
some drawings and not in others, this is for convenience only as
each feature may be combined with any or all of the other features
in accordance with the invention. The words "including",
"comprising", "having", and "with" as used herein are to be
interpreted broadly and comprehensively and are not limited to any
physical interconnection. Moreover, any embodiments disclosed in
the subject application are not to be taken as the only possible
embodiments.
[0031] Other embodiments will occur to those skilled in the art and
are within the following claims:
* * * * *