WO2001019064A1

WO2001019064A1 - Method for disclosing a password of a selective call device

Info

Publication number: WO2001019064A1
Application number: PCT/US2000/023109
Authority: WO
Inventors: James A. Hymel
Original assignee: Motorola, Inc.
Priority date: 1999-09-10
Filing date: 2000-08-23
Publication date: 2001-03-15

Abstract

A selective call device (106) has a non-volatile memory (218) for storing a secured password and a countdown value representative of a period of time. A receiver (204) receives a timed input and a DSP (206) varies the countdown value in response to the timed input and determines when the countdown value reaches a threshold value which causes a display (208) to present or disclose the secured password when the countdown value reaches the threshold value.

Description

METHOD FOR DISCLOSING A PASSWORD OF A SELECTIVE CALL DEVICE

Field of the Invention This invention relates in general to communication systems, and more specifically to a method for disclosing a password of a selective call device.

Background of the Invention There are many communication systems in operation today (including selective call systems) that provides message, data, and voice information. The communication subscriber units, e.g., selective call devices, utilize sophisticated receiver /transmitter architectures and signaling formats that have been optimized to provide both high receiver sensitivities and excellent battery saving capabilities.

In many metropolitan areas, there are many independent selective call communication systems or service providers with selective call devices that are able to receive a plurality of frequencies. Several, if not most, service providers have various marketing schemes that discounts the initial cost of the subscriber unit in return for the user contracting for service for various predetermined time periods, e.g., one-year, two-year, or three-year periods. With this scheme, because the selective call device initial cost ranges from pennies to some other discounted value, the cost of the service during the contact period is higher to re-coupe the cost of the discounted subscriber unit over the contract period.

Unfortunately, numerous users break their contracts because they can obtain less expensive service from other carriers or service provides. The service providers are therefore left with the costly option of asserting their rights through the legal systems when the terms of the contracts are broken. As an alternative, some service providers encrypt the password to prevent the users from changing service during the contract period. However, after the contract period has expired, the user of the selective call device would have to request the original service provider to disclose or remove the password from the selective call device. Some service providers refuse or are unwilling to remove the password even though they have recovered their investment. Therefore, what is needed is a method to prevent users of discounted selective call devices from changing service providers during the contract period while providing users of the selective call device with the option or freedom to change services if they desire at the end of the contract period.

Brief Description of the Drawings FIG. 1 is an electrical block diagram of a communication system in accordance with the preferred embodiment of the present invention.

FIG. 2 is an electrical block diagram of a selective call device according to the preferred embodiment of the present invention.

FIG. 3 an electrical block diagram of the DSP according to FIG. 2. FIG. 4 is a flow diagram illustrating a method for disclosing a password of a selective call device in accordance with the preferred embodiment of the present invention.

Description of a Preferred Embodiment

Referring to FIG. 1, an electrical block diagram of a selective call or radio communication system 100 is shown in accordance with the preferred embodiment of the present invention. The selective call communication system 100 comprises a system controller 102 coupled or connected through a conventional public switched telephone network (PSTN) 108 by conventional telephone links. It can be appreciated that the communication system 100 can be coupled to other networks, e.g., satellites, microwaves or any other wireless or wireline communication system or protocol. Coupled to the PSTN 108 are message-input devices, e.g., conventional telephone 101, a facsimile machine 116 and/or a messaging terminal 112. The communication system 100 preferably operates according to the FLEX® family of protocol standards. The system controller 102 oversees the operation of at least one radio frequency (RF) transmitter /receivers 103, through one or more communication links which, e.g., are twisted-pair telephone wires, which additionally can include RF, microwave, or other high quality audio communication links. The system controller 102 encodes and decodes inbound and outbound addresses into formats that are compatible with landline message switch computers. The system controller 102 also functions to encode and schedule outbound messages, which can include such information as analog voice messages, digital alphanumeric messages, graphics type data, and response commands, for transmission by the radio frequency (RF) transmitter /receivers 103 to a plurality of selective call devices 106. As shown, the selective call devices 106 include one-way and/or two-way devices. The system controller 102 further functions to decode inbound messages, including unsolicited and response messages received by the radio frequency transmitter /receivers 103 from the plurality of two-way selective call devices 106. It can be appreciated by one of ordinary skill in the art that selective call devices 106 are able to operate on multiple frequencies and multiple protocols.

An example of an outbound alphanumeric message intended for a selective call device 106 is an alphanumeric selective call message entered from the messaging terminal 112. An example of an outbound analog message intended for a selective call device 106 is a voice message, numeric, or alphanumeric message entered from the telephone 101, messaging terminal 112, or FAX machine 116. Examples of response messages are acknowledgments or demand response messages. An acknowledgment, e.g., is an inbound message transmitted by or from a selective call device 106 that can indicate a successful reception of an outbound message or a request for information to the communication system. The inbound and outbound messages are included in outbound radio signals transmitted from, and inbound radio signals received by, a conventional antenna 104 coupled to the radio frequency transmitter /receiver 103.

It should be noted that the system controllers 102 is capable of operating in a distributed transmission control environment that allows mixing conventional cellular, simulcast, satellite, or other coverage schemes involving a plurality of radio frequency transmitter /receivers, conventional antennas, for providing reliable radio signals within a geographic area as large as a worldwide network. Moreover, as one of ordinary skill in the art would recognize that the telephonic and selective call device communication system functions can reside in separate system controllers that operate either independently or in a network fashion. Each of the selective call devices 106 assigned for use in the radio communication system 100 has at least one address assigned to the communication system 100 which is a unique selective call address. The selective call address enables the transmission of a message from the system controller 102 only to the addressed selective call device 106. In addition, a Global Positioning System (GPS) time base 120 is shown to illustrate that the communication system 100 including the selective call device 106 can receive timed signals from the GPS 120.

Referring to FIG. 2, an electrical block diagram of a selective call device is shown in accordance with the preferred embodiment of the present. It will be appreciated that the selective call device 106 is one of several types of radios, including two-way selective call devices, conventional mobile radios, conventional or trunked mobile radios that have a data terminal attached thereto, or which optionally have data terminal capability designed in. Each of the selective call devices 106 assigned for use in the radio communication system 100 has an address assigned thereto which is unique to the selective call device 106. The address enables the transmission of a message from the system controller 102 to be received only by the addressed or designated selective call device 106, and identifies messages and responses received at the system controller 102 from the selective call device 106. Furthermore, each of one or more of the selective call devices 106 can have a unique telephone number assigned thereto, the telephone number being unique within the PSTN 108 (FIG. 1). When the system controller 102 receives an inbound message from a selective call device 106, the system controller 102 establishes communication and checks by well known techniques if the requesting selective call device 106 is a valid subscribing unit within the communication system 100.

The selective call device 106 (e.g., a two-way selective call device) can transmit an inbound signal in response to the receipt of a message from the communication system 100. The outbound signal from, e.g., the system controller can be received on any signaling protocol, preferably the FLEX® protocol. The selective call device 106 comprises an antenna 202 that provides a radio frequency (RF) carrier signal to a receiver 204. The receiver 204 generates a recovered signal suitable for processing by a digital signal processor ("DSP") 206 in a manner well known to one of ordinary skill in the art. The DSP 206 performs functions such as encoding and decoding messages and controlling the operation of the selective call device 106 well known to one of ordinary skill in the art. The DSP 206 processes the received signal to decode the address and compares the decoded address with one or more predetermined addresses contained in a memory, for example, a codeplug 218. When the addresses are substantially similar, the user is alerted that a signal has been received either by an audio alert (e.g., a speaker or transducer) 212 or a tactile alert (e.g., a vibrator) 214. The received signal may also include optional message data directed to some selective call device 106. Also, if the selective call device 106 includes an optional voice output, recovered audio components of the received RF signal may be presented. For a message selective call device, the recovered message is stored in a memory 220 for subsequent presentation by an output device which for example is a display 208. The output device will automatically, or when manually selected by switches 216, present the message, such as by displaying the message on the display 208. An external clock can be optionally coupled to the digital signal processor 206 that provides clock signals to determine a count down period. In conjunction with the external clock 224, e.g., a predetermined value can be stored in a non-volatile memory, e.g., the codeplug 218. The processor 206, upon the receipt of clock signals of a predetermined rate, decreases a countdown or predetermined value in the codeplug 218. When that value reaches zero or some predetermined threshold, the password, which is preferably stored in the codeplug 218, can be disclosed or presented to the user, the details of which will be disclosed below.

The digital signal processor 206 of FIG. 2 can be implemented utilizing a microcomputer or processor as shown in FIG. 3. FIG. 3 is an electrical block diagram of a microcomputer-based decoder /controller suitable for use in the selective call device 106 of FIG. 2. As shown, the microcomputer 206 preferably comprises a series microcomputers, such as manufactured by Motorola, Inc., which includes an on-board display driver 314. The microcomputer 206 includes an oscillator 318 that generates timing signals utilized in the operation of the microcomputer 206 and for varying the countdown or predetermined value, preferably on a daily basis until it is time to present or disclose the password to the user of the selective call device 106. A crystal, or crystal oscillator (not shown) is coupled to the inputs of the oscillator 318 to provide a reference signal for establishing the microcomputer timing. A timer/counter 302 couples to the oscillator 318 and provides programmable timing functions that are utilized in controlling the operation of the receiver or the processor. The crystal, the oscillator 318, and timer/counter 302 are used to set the clock cycles to enable the DSP to, e.g., decrement the count value on a daily basis. For example, a one-year subscription contract would preferably cause the DSP to produce 365 (or 366 for a leap year) clock cycles. A RAM (random access memory) 304 is utilized to store variables derived during processing, as well as to provide storage of message information and the new location identifier which are received during operation of the selective call device 106. A ROM (read only memory) 306 stores the subroutines that control the operation of the receiver or the processor and stores a count down value, the details of which will be discussed further. The ROM 306 preferably stores the countdown or the predetermined value which is reduced preferably on a daily basis by the daily clock cycles that are produced in the DSP by the crystal, the oscillator 318, and the timer/counter 302. 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) which stores the count down value. The oscillator 318, timer/counter 302, RAM 304, and ROM 306 are coupled through an address /data /control bus 308 to a central processing unit (CPU) 310 that performs the instructions and controls the operations of the microcomputer 206. According to the preferred embodiment of the present invention, the oscillator 318, the timer /counter 302, and ROM 306 which via the bus 308 coupled to the CPU 310 comprises one example of the hardware necessary for storing a predetermined value in ROM 306, and providing count down values from the timer counter 302. The CPU retrieves the predetermined value from ROM 306, and varies (e.g., decreases) it according to the count values. When the predetermined value reaches zero or some predetermined value, the CPU 310 enables the password which is stored in ROM 306 or code plug 218 (FIG. 2) to be presented to the user or to be able to be accessed from a menu of the selective call device 106. It is understood by one of ordinary skill in the art that instead of count down, the value could be a count-up value. It is well know and understood by those skilled in the art that the password is stored in non-volatile memory and can only be retrieved with, e.g., an automatic password generator (APG) which uses, e.g., a hash algorithm to encrypt and decrypt passwords. Accordingly, without a key, the password cannot be disclosed to the user and certain functions of the selective call device are restricted, e.g., reprogramming the selective call device to receive signals from a different service provider.

The demodulated data generated by the selective call device 106 is coupled into the microcomputer 206 through an input/output (I/O) port 312. The demodulated data is processed by the CPU 310, 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 313, the message, if any, is received and stored in RAM 304. Recovery of the stored message and selection of the predetermined destination address are provided by the switches that are coupled to the I/O port 312. The microcomputer 206 then recovers the stored message and directs the information over the data bus 308 to the display driver 314 which processes the information and formats the information for presentation by a display 208 (FIG. 2) such as an LCD (liquid crystal display). At the time a selective call device's address is received, the alert signal is generated which can be routed through the data bus 308 to an alert generator 316 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 206 generates an alert enable signal which is coupled through data bus 308 to the I/O port 312 to enable generation of a vibratory, or silent alert. Switch inputs are received by the I/O port 312 via the data bus 308. The switch inputs are processed by the CPU 310. Specifically, the CPU 310 retrieves the address of the selective call base station from RAM 304 and in conjunction with the timer counter 302 and the oscillator 318, the CPU 310 generates the ack-back signal which is passed via the data bus 308 to the transmitter.

The battery saver operation is controlled by the CPU 310 with battery saving signals which are directed over the data bus 308 to the I/O port 312 which couples to the power switch 210. Power is periodically supplied to the receiver to enable decoding of the received selective call device address signals and any message information, which is directed to the selective call device 106. Specifically, when the selective call device 106 begins decoding the selective call signal, the receiver is powered by the power switch 210. When the selective call information is received and stored, the microcomputer or DSP 206 sends a signal to the power switch 210 to disable power to the receiver 204 and enable power to the transmitter for transmitting the ack-back signal.

As is well known to one skilled in the art, the selective call device 106, in an alternative embodiment, can receive an over-the-air (OTA) command from the system controller 102 which causes the selective call device to disclose or present the password to the user of the selective call device 106. With the OTA command, the system clock cycles could be generated by the system controller 102 and sent to the selective call device as an OTA which is used to decreased the countdown or predetermined value in the selective call device 106. With this method, if the user of a particular selective call device is delinquent in his/her payment, the system can stop sending OTA to prevent the decrease in the countdown or predetermined value thereby delaying the disclosure of the password. It would be further desirable to prevent the system from delaying the presentation of the password for a no longer than a predetermined period of time, e.g., six (6) months for a one- year contract. In another alternative embodiment, the selective call device 106 can be coordinated with a common time base, e.g., Global Positioning System (GPS), to facilitate the receipt of clock signals once per day, for example at 12 mid-night, to cause the DSP 206 to decrease the countdown or predetermined value in ROM. When the countdown or predetermined value reaches zero or some other predetermined threshold, the DSP 206 is able to retrieve the password from ROM and present or make it accessible to the user. At the end of the day, e.g., the selective call device 106 reads the countdown value from the non-volatile memory and decreases the value and writes the value back into the non-volatile memory. For added security, the DSP could use a secondary counter to count each hour for twenty-four hours and at twenty-four, a main counter is reduced to cause the update of the countdown value in memory. This approach frustrates any effort in attempting to change the time manually to deceive the selective call device 106 in thinking that the subscribing period has expired.

Referring to FIG. 4, a flow diagram illustrating a method for disclosing a password of a selective call device is shown in accordance with the preferred embodiment of the present invention. The selective call device is programmed with a password for restricting access to certain functional operation of the selective call device including reprogramming the selective call device on another service provider channel, step 402. The password is programmed in a non-volatile memory, preferably a ROM or the codeplug. A program counter is also programmed with a countdown value or predetermined value. The program counter is similarly stored in ROM or codeplug, step 404. The selective call device receives timed inputs (clock cycles on preferable a 24 hour basis) from preferably an internal clock and counter circuits, an external communication system, or a GPS system, step 406. In response to the timed inputs, the DSP retrieves the countdown value from ROM, step 408, and varies (preferably by decreasing) the countdown value by the timed input, step 410.

The countdown value is then rewritten back to ROM or codeplug memory, step 412. The selective call device 106 can optionally receive a delay signal which causes the DSP to delay the presentation of the password or access to the password upon certain events not occurring, e.g., when the user fails to make subscription payments, step 414. The DSP checks if the countdown value reaches a threshold value, e.g., zero, step 416, and if not, flow continues to step 406 to wait for other timed inputs. When the countdown value reaches zero, step 416, the DSP checks if a delay signal is received, step 418, and if so the selective call device will delay access or the presentation of the password for a predetermined time, e.g., six (6) months on a 1-year contract, step 420. At step 424, a checked is performed to determine if a delay is to be canceled or removed otherwise the password will not be presented to the user nor will access will be provided thereto. If the delay is not to be removed, the process returns to step 420. If yes or when or there has been no delay signal or the condition for delay has been removed, the DSP will display, present or enable access to the password, step 422.

In this way, service providers can continue with their program of discounting selective call devices and recoup payments over a predetermined contract period by password protecting the selective call device to prevent the user for changing the service provider. The users are also able to receive the password to the selective call device when they have faithfully preformed under the contact and need not requests the password from the service provider because it will be automatically presented, disclosed or access will be provided thereto at the end of the contract period.

In summary, a selective call device comprises a non-volatile memory for storing a secured password and a countdown value representative of a period of time, a receiver for receiving a timed input, a DSP for varying the countdown value in response to the timed input and for determining when the countdown value reaches a threshold value causing a display, in response to the DSP, to present the secured password when the countdown value reaches the threshold value. The receiver can receive the timed inputs from global positioning system, an internal timing system, or an external communication system. The timed inputs are received on a daily basis preferably at midnight. The selective call device can also receives a delay signal for delaying presenting the secured password when the subscriber has defaulted under the terms of the subscription agreement.

What is claimed is:

Claims

1. A method in a selective call device for disclosing a password, comprising the steps of: storing a secured password and a predetermined value representative of a period of time; receiving a timed input; varying the predetermined value in response to the timed input; determining when the predetermined value reaches a threshold value; and presenting the secured password in response to the predetermined value reaching the threshold value.

2. The method according to claim 1 wherein the step of receiving receives the timed input from global positioning system.

3. The method according to claim 1 wherein the step of receiving receives the timed input from an internal timing system.

4. The method according to claim 1 wherein the step of receiving receives the timed input from an external communication system.

5. The method according to claim 1 wherein the step of receiving receives the timed input on a daily basis.

6. The method according to claim 1 wherein the step of receiving receives an external signal comprising a delay signal for delaying a presentation of the secured password.

7. A selective call device comprising: a non- volatile memory for storing a secured password and a countdown value representative of a period of time; a receiver for receiving a timed input; a DSP for varying the countdown value in response to the timed input and determining when the countdown value reaches a threshold value; and a display, response to the DSP, for disclosing the secured password when the countdown value reaches the threshold value.

8. The selective call device according to claim 7 wherein the receiver receives the timed input from global positioning system.

9. The selective call device according to claim 7 wherein the receiver receives the timed input from an internal timing system.

10. The selective call device according to claim 7 wherein the receiver receives the timed input from an external communication system.

11. The selective call device according to claim 7 wherein the receiver receives the timed input on a daily basis.

12. The selective call device according to claim 7 wherein the receiver receives a delay signal for delaying a disclosure of the secured password.