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Claims  |
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What is claimed is:
1. A selective call system having at least two base sites for communicating
with a plurality of selective call receivers wherein at least one of the
plurality of selective call receivers having acknowledge-back capability,
a base site comprising:
a base site transmitter for communicating with a selective call receiver;
a base site receiver for receiving an acknowledge-back signal from the
selective call receiver, the selective call receiver comprising:
a receiver for receiving a signal from the base site;
a decoder/controller, coupled to the receiver, for decoding the signal
received from the base site transmitter, the decoder/controller further
comprising a status indicator for indicating a predetermined status of a
power supply for the selective call receiver;
an acknowledge-back transmitter, coupled to the decoder/controller, for
transmitting acknowledge-back signals to the base site wherein said
acknowledge-back transmitter, in response to the status indicator
transmits a signal to inform the base site that no further
acknowledge-back signals will be transmitted; and
an acknowledge-back suspension circuit, coupled to the acknowledge-back
transmitter, for inhibiting transmissions of acknowledge-back signals in
response to the status indicator.
2. The selective call system according to claim 1 wherein the
decoder/controller comprising a level determinator for determining when
the power supply is depleted below a minimum threshold.
3. The selective call system according to claim 2 wherein the minimum
threshold indicates a power level of the power supply incapable of
providing sufficient power to the acknowledge-back transmitter for further
transmission of acknowledge-back signals.
4. The selective call system according to claim 1 wherein the
decoder/controller further comprising a delay circuit for delaying a
disconnection of the power supply of the selective call receiver until
said acknowledge-back transmitter transmits the signal for informing the
base site that the selective call receiver is being shut-down.
5. The selective call system according to claim 4 wherein the predetermined
status comprises a deactivation of a power switch.
6. A selective call system having at least two base sites for communicating
with a plurality of selective call receivers wherein at least one of the
plurality of selective call receivers having acknowledge-back capability,
a base site comprising:
a base site transmitter for transmitting a message to a selective call
receiver;
a base site receiver for receiving an acknowledge-back signal from the
selective call receiver receiving the message, the selective call receiver
comprising:
a receiver for receiving the message;
a decoder/controller, coupled to the receiver, for decoding the message
received from the base site, the decoder/controller further comprising a
status indicator for indicating a predetermined status of a power supply
of the selective call receiver;
an acknowledge-back transmitter, coupled to the decoder/controller, for
transmitting the acknowledge-back signal in response to the receiver
receiving the message wherein said acknowledge-back transmitter, in
response to the status indicator, transmits a signal to inform the base
site that no further acknowledge-back signal will be transmitted;
an acknowledge-back suspension circuit, coupled to the acknowledge-back
transmitter, for suspending transmissions of the acknowledge-back signal
in response to the status indicator.
7. The selective call system according to claim 6 wherein the
decoder/controller comprising a level determinator for determining when
the power supply is depleted below a minimum threshold.
8. The selective call system according to claim 7 wherein the minimum
threshold indicates a power level of the power supply incapable of
providing sufficient power to the acknowledge-back transmitter for
additional transmissions of acknowledge-back signals.
9. The selective call system according to claim 6 wherein the
decoder/controller further comprising a delay circuit for delaying a
disconnection of the power supply of the selective call receiver until
said acknowledge-back transmitter transmits the signal for informing the
base site that the selective call receiver is being shut-down.
10. The selective call system according to claim 9 wherein the
predetermined status comprises a deactivation of a power switch.
11. A selective call receiver having acknowledge-back capabilities,
comprising:
a receiver for receiving messages;
a decoder/controller, coupled to the receiver, for decoding the messages
being received, the decoder/controller comprising a status indicator for
indicating a predetermined status of a power supply;
an acknowledge-back transmitter, coupled to the decoder/controller, for
transmitting acknowledge-back signals wherein said acknowledge-back
transmitter, in response to the status indicator, transmits a signal to
inform a selective call system that no further acknowledge-back signals
will be transmitted; and
an acknowledge-back suspension circuit, coupled to the acknowledge-back
transmitter, for inhibiting transmissions of acknowledge-back signals in
response to the status indicator.
12. The selective call receiver according to claim 11 wherein the
decoder/controller comprising a level determinator for determining when
the power supply is depleted below a minimum threshold.
13. The selective call receiver according to claim 12 wherein the minimum
threshold indicates a power level of the power supply incapable of
providing sufficient power to the acknowledge-back transmitter for
additional transmissions of acknowledge-back signals.
14. The selective call receiver according to claim 13 wherein the
decoder/controller further comprising a delay circuit for delaying a
disconnection of the power supply until said acknowledge-back transmitter
transmits the signal for informing the selective call system that the
selective call receiver is being shut-down.
15. The selective call receiver according to claim 14 wherein the
predetermined status comprises a deactivation of a power switch.
16. A selective call receiver having acknowledge-back capabilities for
receiving messages from a plurality of base sites comprising:
a receiver for receiving the messages;
a decoder/controller, coupled to the receiver, for decoding the messages
being received the decoder/controller comprising a status indicator for
indicating a predetermined status of a power supply of the selective call
receiver;
an acknowledge-back transmitter, coupled to the decoder/controller, for
transmitting acknowledge-back signals in response to the receiver
receiving the messages wherein said acknowledge-back transmitter, in
response to the status indicator, transmits a signal to inform the
selective call system that no further acknowledge-back signals will be
transmitted; and
an acknowledge-back suspension circuit, coupled to the acknowledge-back
transmitter, for suspending transmissions of the acknowledge-back signals
in response to the status indicator.
17. The selective call receiver according to claim 16 wherein the
decoder/controller comprising a level determinator for determining when
the power supply is depleted below a minimum threshold.
18. The selective call receiver according to claim 17 wherein the minimum
threshold indicates a power level of the power supply incapable of
providing sufficient power to the acknowledge-back transmitter for further
transmission of acknowledge-back signal.
19. The selective call receiver according to claim 16 wherein the
decoder/controller further comprising a delay circuit for delaying a
disconnection of the power supply until said acknowledge-back transmitter
transmits the signal for informing a selective call system that the
selective call receiver is being shut-down.
20. The selective call receiver according to claim 19 wherein the
predetermined status comprises a deactivation by a power switch.
21. In a selective call receiver having acknowledge-back capabilities, a
method for suspending acknowledge-back signals comprising the steps of:
(a) receiving messages;
(b) decoding the messages being received;
(c) indicating when a predetermined status has been satisfied;
(d) transmitting acknowledge-back signals, said step of transmitting, in
response to the predetermined status being satisfied, transmits a signal
to inform a selective call system that no further acknowledge-back signals
will be transmitted; and
(e) inhibiting step (d) in response step (c) indicating that the
predetermined status has been satisfied.
22. The method according to claim 21 wherein the step (d) of indicating
indicates that the predetermined status is satisfied when a power supply
is discharged to a minimum threshold.
23. The method according to claim 21 further comprising a step of delaying
a disconnection to a power supply until the step (d) of transmitting
transmits an acknowledge-back signal for informing a selective call system
when the selective call receiver is being shut-down.
24. In a selective call receiver having acknowledge-back capabilities, a
method for suspending acknowledge-back signals comprising the steps of:
(a) receiving a signal;
(b) decoding the signal received;
(c) indicating when a predetermined status has been satisfied;
(d) transmitting acknowledge-back signals in response the signal received,
said step of transmitting, in response to the predetermined status being
satisfied, transmits a signal to inform a selective call system that no
further acknowledge-back signals will be transmitted; and
(e) suspending the step (c) of transmitting acknowledge-back signals in
response to the step (d) indicating that the predetermined status has been
satisfied.
25. The method according to claim 24 wherein the step (d) of indicating
indicates that the predetermined status is satisfied when a power supply
is discharged to a minimum threshold.
26. The method according to claim 24 further comprising a step of delaying
a disconnection to a power supply until the step (d) of transmitting
transmits an acknowledge-back signal for informing a selective call system
when the selective call receiver is being shut-down.
27. A selective call receiver having acknowledge-back capabilities,
comprising:
a receiver for receiving messages;
a decoder/controller, coupled to the receiver, for decoding the messages
being received, the decoder controller comprising a status indicator for
indicating when a level of a power supply is depleted below a minimum
threshold;
an acknowledge-back transmitter, coupled to the decoder/controller, for
transmitting acknowledge-back signals wherein said acknowledge-back
transmitter, in response to the status indicator, transmits a signal to
inform a selective call system that no further acknowledge-back signals
will be transmitted; and
an acknowledge-back suspension circuit, coupled to the acknowledge-back
transmitter, for inhibiting transmissions of acknowledge-back signals in
response to the status indicator.
28. A selective call system having at least two base sites for
communicating with a plurality of selective call receivers wherein at
least one of the plurality of selective call receivers having
acknowledge-back capability, a base site comprising:
a transmitter for communicating with a selective call receiver;
a base site receiver for receiving an acknowledge-back signal from the
selective call receiver, the selective call receiver comprising:
a receiver for receiving a signal from the base site;
a decoder/controller, coupled to the receiver, for decoding the signal
received from the base site, the decoder/controller comprising a status
indicator indicating when a level of a power supply is depleted below a
minimum threshold;
an acknowledge-back transmitter, coupled to the decoder/controller, for
transmitting acknowledge-back signals to the base site wherein said
acknowledge-back transmitter, in response to the status indicator,
transmits a signal to inform the base site that no further
acknowledge-back signals will be transmitted; and
an acknowledge-back suspension circuit, coupled to the acknowledge-back
transmitter, for inhibiting transmissions of acknowledge-back signals in
response to the status indicator indicating when the level of the power
supply is depleted below the minimum threshold. |
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Claims |
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Description |
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FIELD OF THE INVENTION
This invention relates in general to selective call systems, and in
particular to a selective call receiver capable of suspending
acknowledge-back responses.
BACKGROUND OF THE INVENTION
In conventional selective call systems, when a selective call receiver is
paged, a message is delivered to the selective call receiver by
transmitting the message during a predefined time period identifying the
selective call receiver to which the message is intended. The selective
call receiver, as is well known, battery saves during the other time
period until its predetermined time period occurs, during which, the
selective call receiver turns-on and checks if a message is addressed to
it. If not, the selective call receiver continue its battery save routine.
When a message is addressed to the selective call receiver, the selective
call systems have no way of telling if or when the message was received.
Therefore, the selective call system can retransmit the same message for a
predetermine number of times to ensure that the selective call receiver
has every opportunity to receive the message. Unfortunately, the
retransmission of messages waste valuable air-time.
Acknowledge-back selective call receivers, however, upon receipt of a
message, are able to transmit an acknowledge-back response to the
selective call system informing it that the message was received.
Therefore, with acknowledge-back selective call receivers, the selective
call system does not need to continue retransmitting the same message
because the acknowledge back response verifies, among other things, that
the message was received. Unfortunately, because the selective call
receiver is portable and has a limited energy content battery, the
transmission of the acknowledge back responses deplete the battery much
quicker. As is well known, transmitting require more energy that
receiving, therefore, the selective call receiver may receive pages but is
unable to transmit the acknowledge-back responses because the battery is
so depleted that it is unable to power-up the transmitter even thought the
selective call receiver is still able to receive pages. Under these
conditions, the selective call system may choose to continue
retransmitting the same message although the message was received.
Therefore, what is needed is a selective call receiver that is able to
eliminate or reduce the need for the selective call system to continue
retransmitting the same messages when no acknowledge-back response will be
transmitted.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an electrical block diagram of a selective call system in
accordance with the preferred embodiment of the present invention.
FIG. 2 is an electrical block diagram of a selective call base station in
accordance with the preferred embodiment of the present invention.
FIG. 3 is an electrical block diagram of a selective call receiver in
accordance with the preferred embodiment of the present invention.
FIG. 4 is an electrical block diagram of a microcomputer based
decoder/controller suitable for use in the selective call receiver of FIG.
3.
FIG. 5 illustrates an ack-back response in accordance with the preferred
embodiment of the present invention.
FIG. 6 is a flow diagram illustrating the operation of the selective call
system in accordance with the preferred embodiment of the present
invention.
FIG. 7 is a flow diagram illustrating the operation of the selective call
receiver in accordance with the preferred embodiment of the present
invention.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to FIG. 1, a selective call system 100 in accordance with a
preferred embodiment of the present invention is shown. The selective call
system 100 comprise a terminal/controller 104 coupled to a computer (not
shown) via a modem 101 and a telephone 116 via a conventional public or
private telephone network 102 known to one of ordinary skill in the art.
The telephone network 102 through the base site terminal/controller 104 is
coupled to a plurality of selective call base stations (or sites) 120-124.
The plurality of selective call base stations 120-124 transmit and receive
signals via its respective transmitters/receivers 110-114. The details of
the operation of the selective call base stations 110-114 will be
discussed below. The plurality of selective call base sites 120-124 have
an associated coverage area (for example, 105 and 106) into which signals
from the terminal/controller 104 are broadcast and received by at least
one of a plurality of selective call receivers 108.
Referring to FIG. 2, a more detailed block diagram of the selective call
base sites 120-124 are shown in accordance with the preferred embodiment
of the present invention. The selective call base stations 120-124
comprise a telephone interconnect 201 which allows messages to enter into
the selective call system 100 through a public or private telephone
network using, for example, a telephone 116, a computer 102, or an
alphanumeric entry device (not shown). A communication terminal 202, for
example the Motorola's MODEN PLUS Encoder, processes the information
received through the telephone interconnect 201. A generated address and
message decoded from the received information are stored in a memory 204
until the next transmission cycle.
As shown, the communication terminal 202 is coupled to a controller 206,
which controls the operation of a link transmitter 208, a base site
transmitter 210, a base site receiver 212, and a receiver 214. An example
of a controller suitable for use in the present invention is Motorola's
MC6809 controller. A timing generator 216, coupled to the controller 206,
provides a high accuracy clock to maintain system timing for communication
and synchronization of the selective call system 100 including all the
selective call base sites 120-124 and the plurality of selective call
receiver 108 by techniques known to one skilled in the arts.
Operationally, the base site transmitter 210 transmits, to the plurality
of selective call receivers 108, at least one of which has
acknowledge-back capabilities, a signal which comprises a paging
(selective call) type message preferably on a first frequency at the
transmission cycle. Preferably, a group of selective call receivers are
intended (addressed) by the base site transmitter 210 to receive the
paging message. As is known, the paging message, before it is transmitted,
is encoded with the appropriate address for addressing the group of
selective call receivers of the plurality of selective call receivers 108.
For example, and according to the preferred embodiment of the present
invention, when a group of the plurality of the selective call receivers
108 have been paged, the selective call receivers of the group that
received the message will substantially simultaneously transmit a
response, the acknowledge back signals. Preferably, the acknowledge back
(acknowledgment or ack-back) response is transmitted on a second frequency
preferably substantially lower than the first frequency. The receiver 214
of the selective call base sites 120-124 receives the acknowledge back
response (ack signal or ack-back signal) which is stored in a memory 204.
As is well known, the receiver 214 demodulates the ack-back signal to
produce preferably a baseband signal. The baseband signal is converted
(digitized) from an analog signal to a digital signal by an
analog-to-digital (A/D) converter 220 known to one of ordinary skill in
the art. The conversion by the A/D converter 220 are received and stored
by a digital Signal Processor (DSP) 218. The DSP 218, for example, can
include a Motorola's DSP56100 or a Texas Instrument's TMS3000 series
digital signal processors. According to the preferred embodiment of the
present invention, the DSP 218 stores the digitized samples as digitized
bits and continuously receives and stores the digitized samples until all
bits of the ack-back signal have been received and stored. The digitized
samples are retrieved and each bit decoded. Upon the completion of the
decoding of the ack-back signal, the DSP determines whether the selective
call receiver has transmitted a status indicator which indicates the
suspension, deactivation or disabling the ack-back transmitter or that the
selective call receiver is being turned-off or shut off. The DSP also has
a timer 402 which is used as a delay circuit for delay the shutting down
of the selective call receiver until the selective call system has
acknowledges the ack back signal indicating that the selective call
receiver 108 will be taken out of service. The operation of the DSP 218
will be discussed in detail below.
Referring to FIG. 3, an electrical block diagram of a selective call
receiver is shown in accordance with the preferred embodiment of the
present invention. The selective call receiver 108 comprises an antenna
302 for intercepting transmitted radio frequency (RF) signals which are
coupled to the input of a receiver 304. The RF signals are preferably
selective call (paging) message signals which provide, for example, a
receiver address and an associated message, such as voice message.
However, it will be appreciated that other well known paging signaling
formats, such as tone only signaling or tone, numeric or alphanumeric
signaling, would be suitable for use as well. The receiver 304 processes
the RF signal and produces at the output a data stream representative of a
demodulated data information. The demodulated data information is coupled
into the input of a decoder/controller 306 which processes the information
in a manner well known in the art. A ack-back transmitter 334 is coupled
to the antenna 302 and the decoder/controller 306. A power switch (or
ack-back suspension circuit) 310, coupled to the decoder/controller 306,
is used to control the supply of power to the receiver 304, thereby
providing a battery saving function, and to the transmitter 334 for
transmitting the ack-back response subsequent to the receipt of a paging
message or to suspend, inhibit or disable the transmission of ack-back
responses.
For purposes of this illustration, it will be assumed that the FLEX.TM.
signaling format although other signaling formats could be utilized as
well. When the address is received by the decoder/controller 306, the
received address is compared with one or more addresses stored in a code
plug (memory) 322, and when a match is detected, an alert signal is
generated to alert a user that a selective call message, or page, has been
received. The alert signal is directed to an audible alerting device 314
for generating an audible alert or to a tactile alerting device 316 for
generating a silent vibrating alert. Switches 320 allow the user of the
selective call receiver to, among other things, select between the audible
alert 314 and the tactile alert 316 in a manner well known in the art.
The message information which is subsequently received is stored in memory
404 (FIG. 4) and can be accessed by the user for display using one or more
of the switches 320 which provide such additional functions as reset,
read, and delete, etc. Specifically, by the use of appropriate functions
provided by the switches 320, the stored message is recovered from memory
and processed by the decoder/controller 306 for displaying by a display
308 which enables the user to view the message. The receipt of the message
by the selective call receiver 108 can automatically generate the ack-back
response to the selective call base station to inform it that the message
was successfully received. Preferably, the user will have the opportunity
to input a message by using switches 320 or some other input devices well
known to one of ordinary skilled in the arts. When the message is entered,
the decoder/controller 306 processes the message by encoding an addressed
derived from the received message to generate the ack-back response. The
encoded ack-back response is then transmitted to the selective call base
station that originated the paging message by techniques well known to one
of ordinary skill in the art.
According to the preferred embodiment of the present invention, when a
message is received, a power level of a battery (not shown) is checked by
a level determinator to determine if the power supply is sufficient to
transmit an ack-back signal in response to the message received. When the
power supply is below a minimum threshold, the decoder/controller 306 sets
a status indicator which indicates that no ack back signal will be
transmitted to the selective call system and the power switch 310 is used
to deactivate or disconnect power to the ack back transmitter 334.
Similarly, when the switches 320 are used to turn-off the selective call
receiver 108, the ack-back transmitter 334 sets the status indicator and
transmit an ack-back signal informing the selective call system that it is
being turned off. In this way, the selective call system will not need to
waste air time re-transmitting the same message because it will know when
the selective call receiver 108 is out of service or when the battery is
too discharged to transmit ack-back response.
The controller/decoder 306 of FIG. 3 can be implemented utilizing a
microcomputer as shown in FIG. 4. FIG. 4 is an electrical block diagram of
a microcomputer based decoder/controller suitable for use in the selective
call receiver of FIG. 3. As shown, the microcomputer 306 is preferably of
the series microcomputers, such as manufactured by Motorola, Inc., which
includes an on-board display driver 414. The microcomputer 306 includes an
oscillator 418 which generates the timing signals utilized in the
operation of the microcomputer 306. A crystal, or crystal oscillator (not
shown) is coupled to the inputs of the oscillator 418 to provide a
reference signal for establishing the microcomputer timing. A
timer/counter 402 couples to the oscillator 418 and provides programmable
timing functions which are utilized in controlling the operation of the
receiver or the processor. A RAM (random access memory) 404 is utilized to
store variables derived during processing, as well as to provide storage
of message information which are received during operation as a selective
call receiver. A ROM (read only memory) 406 stores the subroutines which
control the operation of the receiver or the processor which will be
discussed further. It will be appreciated that in many microcomputer
implementations, the programmable-ROM (PROM) memory area can be provided
either by a programmable read only memory (PROM) or an EEPROM
(electrically erasable programmable read only memory). The oscillator 418,
timer/counter 402, RAM 404, and ROM 406 are coupled through an
address/data/control bus 408 to a central processing unit (CPU) 410 which
performs the instructions and controls the operations of the microcomputer
306.
The demodulated data generated by the receiver is coupled into the
microcomputer 306 through an input/output (I/O) port 412. The demodulated
data is processed by the CPU 410, and when the received address is the
same as stored within the code-plug memory which couples into the
microcomputer through, for example an I/O port 413, the message, if any,
is received and stored in RAM 404. Recovery of the stored message, and
selection of the predetermined destination address, is provided by the
switches which are coupled to the I/O port 412. The microcomputer 306 then
recovers the stored message and directs the information over the data bus
408 to the display driver 414 which processes the information and formats
the information for presentation by a display 308 (FIG. 3) such as an LCD
(liquid crystal display). At the time a selective call receiver's address
is received, the alert signal is generated which can be routed through the
data bus 408 to an alert generator 416 that generates the alert enable
signal which is coupled to the audible alert device that was described
above. Alternatively, when the vibrator alert is selected, as described
above, the microcomputer generates an alert enable signal which is coupled
through data bus 408 to the I/O port 412 to enable generation of a
vibratory, or silent alert. Switch inputs are received by the I/O port 412
via the data bus 408. The switch inputs are processed by the CPU 410.
Specifically, the CPU 410 retrieves the address of the selective call base
station from RAM 404 and in conjunction with the timer counter 402 and the
oscillator 418, the CPU 410 generates the ack-back signal which is passed
via the data bus 408 to the transmitter.
The battery saver operation is controlled by the CPU 410 with battery
saving signals which are directed over the data bus 408 to the I/O port
412 which couples to the power switch 310. Power is periodically supplied
to the receiver to enable decoding of the received selective call receiver
address signals and any message information which is directed to the
selective call receiver. Specifically, when the selective call receiver
108 begins decoding the paging signal, the receiver is powered by the
power switch. When the paging message is received and stored, the
microcomputer 306 sends a signal to the power switch 310 to disable power
to the receiver 304 and enable power to the transmitter for transmitting
the ack-back signal if the status indicator is not set.
Referring to FIG. 5, a signal diagram is shown illustrating the ack-back
signal or response according the preferred embodiment of the present
invention. The ack back signal comprises an address portion 502 indicating
the selective call receiver 108 that is transmitting the ack back
response, and a status indicator 504 which encodes preferably two bits to
indicate the status the selective call receiver. The ack signal also
includes a message 506 which is transmitted to the selective call system
in response to the paging message received.
Referring to FIG. 6, a flow diagram illustrating the operation of the
selective call system according to the preferred embodiment of the present
invention. The selective call system comprises a plurality of base sites
(or base stations) capable of communicating with at least one of a
plurality of selective call receiver having acknowledge back (ack or
ack-back) capabilities. The selective call receivers via its ack-back
transmitters can send a signal to a base site to register with the
selective call systems. When this registration signal is received, the
selective call systems determine if the selective call receiver requesting
registration is assigned to the selective call system, step 602. If the
selective call receiver is assigned to the selective call system, the
selective call receiver will recognize the registration by logging or
storing the registration information, step 604. Thereafter, the selective
call receiver will update its data base to include the registration
information of the selective call receiver, step 606. When the
registration information is received, the selective call system can
determine where the selective call receiver requesting registration is
located because the information received also includes the location of the
base site that received the information.
When a message designated for a particular selective call receiver or group
of selective call receivers, the message is encoded and sent to the
selective call receiver or group of selective call receiver targeted at
the base site(s) where the selective call receiver(s) is (are) located,
step 608. To efficiently use air time, the selective call system may send
a "where-are-you" signal to the selective call receiver. The base site
that received the ack-back signal of the responding selective call
receiver marks (specifies) the location of the selective call receiver.
The selective call system thereafter will target further communication
with the selective call receiver at the base site of the location
identified by the response to the "where-are-you" signal. After a message
is sent to the selective call receiver, the selective call system checks
if the selective call receiver has informed the selective call system that
its ack-back transmitter has been disabled or suspended the transmission
of ack-back signals or responses, step 610. If the ack-back signal or
response capabilities have been suspended or disabled, the selective call
system will not wait for the ack-back response and will log the page sent
as received by the selective call receiver when sent, step 626.
Alternatively, when the ack-back capability has not been suspended, step
610, the selective call system waits for the ack-back response or signal,
step 612. Step 614 checks if the ack-back signal is received. If not, a
time-out period is checked, step 616. If the time-out period has expired,
the page may be re-sent to the pager to ensure that it was received, step
608. Alternatively, when the time-out period has not expired, step 614,
the selective call system continues to wait until the ack-back signal is
received or the time-out period has expired, step 612. At step 614, After,
for example, the ack-back signal is received, the selective call receiver
checks if an "out of service" signal had been received, step 618. The "out
of service" signal indicates that the selective call receiver has been
turned-off or shut down. If yes, the selective call system de-registers
the selective call receiver from the active list of selective call
receiver, step 620. If no, the selective call system checks if the ack
suspension signal has been received (if ack-back responses disabled). If
disabled, the selective call system updates the data base to indicate that
when a selective call receiver or page is sent to that selective call
receiver no ack back signal or response will be received, step 624. If the
ack back suspension signal was not received or after the selective call
system updates the data base to indicate no additional ack will be
received, the selective call system indicates that the selective call
message sent has been received, step 626.
In this way, a selective call system can determine and store the location
of the selective call receiver(s) assigned to the system. The stored
location is retrieved to determine the geographic area in which to send
the message to a designated selective call receiver instead of
simulcasting the information over the entire selective call (paging)
network thereby saving airtime. Additionally, the ack-back selective call
receivers are capable of informing the selective call system when they are
being turned-off and when | | |
