Patent US4992783A successfully refreshed from Google Patents.

US4992783A Expired / Lapsed US ⏱️ 0.0 years remaining

Method and apparatus for controlling access to a communication system

Assignee: Motorola Solutions Inc

•

Filing: 1988-04-04

•

Granted: 1991-02-12

•

Expires: 2008-04-04

📄 Original PDF 🌐 Google Patents 🔄 Sync Now

Abstract

Abstract All subscribers operating within a communication system initially generate and transmit a random password and their ID code to the operation (control) center of a communication system. Thereafter, in a first embodiment, subscribers are commanded to modify (in a predetermined manner) and re-transmit their password and ID code either periodically or upon requesting access to the communication system. The modified password is retained as the current (authorized) password by both the subscriber and the system. In a second embodiment, subscribers are commanded to generate and transmit a new random password and their ID code to the system, which maintains a history of each subscriber's current and previous passwords. According to the invention, some of the subscribers having an unauthorized (duplicated) ID code may be inactive (off) when the subscriber is commanded to modify or generate a password. In this way, one of the subscribers having an unauthorized (duplicated) ID code will become out-of-sync with the system, and eventually transmit an unauthorized password. When the system receives an incorrect password for an out-of-sync subscriber, access to the communication system may be denied, and the subscribers that duplicate (or permit others to duplicate) ID codes may be identified.

Inventors

👤 Kenneth J. Zdunek
👤 Philip A. Bieri
👤 Eric R. Schorman

Bibliographic Details

Application Number —

Jurisdiction US

Data Source google_patents

Last Synchronized 2026-11-02 23:20

CPC Classifications

H; H04; H04W; H04W12/00; H04W12/06; H04L; H04L63/00; H04L63/08; H04L63/083; H04W12/08; H04L63/10; H04L63/108

Claims Analysis

Total Claims: 24

Claim 1

Independent Claim 102 words

In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code stored therein, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units: (a) generating a first random number as a first password code; (b) transmitting at least said first password code and said identification code; (c) receiving a command code and generating a second random number as a second password code in response thereto; (d) transmitting at least said second password code and said identification code.

Claim 2

Dependent Claim 102 words

Claim 3

Dependent Claim 88 words

In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code and a first password code stored therein, a method of controlling access to the two-way communication system comprising the steps of: (a) transmitting at least a call request code; (b) receiving a command code and generating a random number as a second password code in response thereto; (c) transmitting at least said second password code and said identification code; and (d) receiving a channel grant code.

Claim 4

Dependent Claim 88 words

Claim 5

Dependent Claim 83 words

In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code and a first password code stored therein, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units: (a) receiving a command code and generating a random number as a second password code in response thereto; (b) transmitting at least said second password code and said identification code.

Claim 6

Dependent Claim 83 words

In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code and a first password code stored therein, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units: (a) receiving a command code and generating a random number as a second password code in response thereto; (b) transmitting at least said second password code and said identification code.

Claim 7

Dependent Claim 123 words

Claim 8

Dependent Claim 123 words

Claim 9

Dependent Claim 166 words

In a two-way communication system having a plurality of subscriber units each having at least an identification code and a first password code stored therein and at least one central unit designating said first password code as a current password code, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units; (a) transmitting at least a call request code; (b) receiving a command code and generating a random number as a second password code in response thereto; (c) transmitting at least said second password code and said identification code; and (d) receiving a channel grant code, at said at least one central unit: (a) receiving at least said call request code; (b) transmitting said command code; (c) receiving at least said second password code; (d) determining whether said second password correlates to a current password; (e) granting access to said two-way communication system if said second password correlates to said current password.

Claim 10

Dependent Claim 166 words

Claim 11

Dependent Claim 100 words

In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code and a first password code stored therein, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units: (a) receiving a command code and generating a random number and a second password code in response thereto; (b) transmitting at least said second password code and said identification code; at said central unit; (a) transmitting said command code; (b) receiving at least said second password code.

Claim 12

Dependent Claim 100 words

In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code and a first password code stored therein, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units: (a) receiving a command code and generating a random number and a second password code in response thereto; (b) transmitting at least said second password code and said identification code; at said central unit; (a) transmitting said command code; (b) receiving at least said second password code.

Claim 13

Dependent Claim 107 words

In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code stored therein, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units: (a) generating a first random number as a first password code; (b) transmitting at least said first password code and said identification code; (c) generating a second random number as a second password code in response to a control signal; (d) transmitting at least said second password code and said identification code; and, (e) receiving a channel grant code.

Claim 14

Dependent Claim 107 words

In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code stored therein, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units: (a) generating a first random number as a first password code; (b) transmitting at least said first password code and said identification code; (c) generating a second random number as a second password code in response to a control signal; (d) transmitting at least said second password code and said identification code; and, (e) receiving a channel grant code.

Claim 15

Dependent Claim 123 words

In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code stored therein, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units: (a) generating a first random number as a first password code; (b) transmitting at least said first password code and said identification code; (c) generating a second random number as a second password code in response to a control signal; (d) transmitting at lest said second password code and said identification code; and (e) receiving a channel grant code; at said central unit: (a) receiving said first password code; (b) receiving said second password code.

Claim 16

Dependent Claim 123 words

In a two-way communication system having a central unit and a plurality of subscriber units each having at least an identification code stored therein, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units: (a) generating a first random number as a first password code; (b) transmitting at least said first password code and said identification code; (c) generating a second random number as a second password code in response to a control signal; (d) transmitting at lest said second password code and said identification code; and (e) receiving a channel grant code; at said central unit: (a) receiving said first password code; (b) receiving said second password code.

Claim 17

Dependent Claim 68 words

The method of claim 4 or 8, which includes the central unit steps of: (a1) storing said first received password code, and operating thereafter using said first received password code as a current password code; (c) storing said second received password code, and operating thereafter using said first received password code as a previous password code, and using said second received password code as said current password code.

Claim 18

Independent Claim 47 words

The method of claims 5 or 6, which includes the central unit step of: (c1) storing said second received password code, and operating thereafter using said first received password code as a previous password code, and using said second received password code as a current password code.

Claim 19

Dependent Claim 20 words

The method of claim 5 or 8, which includes the central unit step of: (c) transmitting a channel grant code.

Claim 20

Dependent Claim 44 words

The method of claim 4 or 8, which includes the central unit steps of: (a1) storing said first password code as a current password; (c) storing said first password code as a prior password; and, storing said second password code as said current password.

Claim 21

Dependent Claim 190 words

In a two-way communication system having a plurality of subscriber units each having at least an identification code and a first password code stored therein and at least one central unit designating said first password code as a current password code, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units; (a) transmitting at least said call request code; (b) receiving a command code and generating a second password code in response thereto; (c) transmitting at least said second password code and said identification code; at said at least one central unit; (a) receiving at least said call request code; (b) transmitting said command code; (c) receiving at least said second password code; (d) determining whether said second password correlates to a current password; (e) determining whether said second password correlates to a prior password; (f) granting access to said two-way communication system when said second password correlates with said current password or does not correlate to said prior password and does not correlate to said current password, else denying access to said two-way communication system.

Claim 22

Dependent Claim 190 words

In a two-way communication system having a plurality of subscriber units each having at least an identification code and a first password code stored therein and at least one central unit designating said first password code as a current password code, a method of controlling access to the two-way communication system comprising the steps of: in at least one of said plurality of subscriber units; (a) transmitting at least said call request code; (b) receiving a command code and generating a second password code in response thereto; (c) transmitting at least said second password code and said identification code; at said at least one central unit; (a) receiving at least said call request code; (b) transmitting said command code; (c) receiving at least said second password code; (d) determining whether said second password correlates to a current password; (e) determining whether said second password correlates to a prior password; (f) granting access to said two-way communication system when said second password correlates with said current password or does not correlate to said prior password and does not correlate to said current password, else denying access to said two-way communication system.

Claim 23

Dependent Claim 155 words

In a two-way communication system having a plurality of subscriber units each having at least an identification code and a first password code stored therein and at least one central unit having stored therein at least one current password and at least one prior cross-referenced to said identification codes of said plurality of subscriber units, a method of controlling access to the two-way communication system comprising the steps of: at said at least one central unit: (a) receiving at least a password code and an identification code to provide a received password; (b) determining whether said received password correlates to a current password; (c) determining whether said received password correlates to a prior password; (d) granting access to said two-way communication system if said received password correlates to said current password or does not correlate to said prior password and does not correlate to said current password, else denying access to said two-way communication system.

Claim 24

Dependent Claim 155 words

In a two-way communication system having a plurality of subscriber units each having at least an identification code and a first password code stored therein and at least one central unit having stored therein at least one current password and at least one prior cross-referenced to said identification codes of said plurality of subscriber units, a method of controlling access to the two-way communication system comprising the steps of: at said at least one central unit: (a) receiving at least a password code and an identification code to provide a received password; (b) determining whether said received password correlates to a current password; (c) determining whether said received password correlates to a prior password; (d) granting access to said two-way communication system if said received password correlates to said current password or does not correlate to said prior password and does not correlate to said current password, else denying access to said two-way communication system.

References Cited (Backward Citations)

GB1478372A Cited

US4310720A Cited

US4268715A Cited

US4218738A Cited

US4602129A Cited

US4581486A Cited

US4295039A Cited

US4445712A Cited

US4348696A Cited

US4481384A Cited

GB2120821A Cited

US4596985A Cited

US4626845A Cited

US4590470A Cited

US4623919A Cited

US4654481A Cited

US4630201A Cited

US4672533A Cited

US4802217A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-02-11	1994-08-13	1995-02-12	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-02-11	1998-08-13	1999-02-12	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-02-11	2002-08-13	2003-02-12	$7700.00	Window Closed / Lapsed

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag

Select Category

Notes (Optional)