Method and apparatus for locating a remote unit within a communication system
First Claim
1. A method for locating a remote unit within a communication system, the method comprising the steps of:
- transmitting a first message to a base station;
determining a timing advance based on the first message;
advancing or retarding transmission circuitry;
transmitting a second message to the base station;
determining a second timing advance based on the second message;
determining a location based on advancing or retarding transmission circuitry by a fraction of a timing-advance bit;
wherein the step of determining a distance from the base station comprises the steps of determining a value for C, wherein C is approximately equal to;
DTA−
(N−
½
)DADV where,DTA=a distance to a timing-advance boundary;
DADV=distance attributed to advancing/retarding the transmission circuitry; and
N=a number of iterations in timing advance that causes a change in the timing advance.
2 Assignments
0 Petitions
Accused Products
Abstract
Timing Advance information is obtained from base stations (103–105), and is utilized by a remote unit (113) to approximate the Time of Arrival (TOA) of the signals from each base station. The remote unit (113) accesses a single base station to determine its timing advance. In order to increase accuracy, the remote unit (113) then repeats the process, but during the next iteration, the transmission timing is advanced or delayed by a fraction of a bit (e.g. ¼ bit). The base station responds with a new timing advance value. This process is repeated until it is determined how many fractions of bit increments the remote unit (113) is away from a known timing advance boundary of the base station. Once known, this information is utilized to determine the location of the remote unit (113).
178 Citations
10 Claims
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1. A method for locating a remote unit within a communication system, the method comprising the steps of:
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transmitting a first message to a base station; determining a timing advance based on the first message; advancing or retarding transmission circuitry; transmitting a second message to the base station; determining a second timing advance based on the second message; determining a location based on advancing or retarding transmission circuitry by a fraction of a timing-advance bit; wherein the step of determining a distance from the base station comprises the steps of determining a value for C, wherein C is approximately equal to;
DTA−
(N−
½
)DADV where,DTA=a distance to a timing-advance boundary; DADV=distance attributed to advancing/retarding the transmission circuitry; and N=a number of iterations in timing advance that causes a change in the timing advance. - View Dependent Claims (2, 3, 4, 5)
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6. A method for determining a distance (C) from a base station, the method comprising the steps of:
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determining a distance to a timing-advance boundary (DTA); determining a distance attributed to advancing or retarding transmission circuitry (DADV); determining a number of iterations (N) of advancing or retarding transmission that causes a change in a timing advance; and determining C based on DTA, DADV, and N. - View Dependent Claims (7)
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8. An apparatus for determining location, the apparatus comprising:
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a transceiver outputting a first message and a second message, wherein the second message is advanced or retarded in time by a fraction of a timing-advance bit; and logic circuitry determining a first and a second timing advance value based on the first and the second message and determining a distance from a first base station based on the first and the second timing advance values;
wherein the distance from the firm base station is calculated based on the formula;
DTA−
(N−
½
)DADV where,DTA=a distance to a timing-advance boundary DADV=a distance attributed to advancing/retarding the transmission circuitry; and N=a number of iterations in timing advance that causes a change in the timing advance. - View Dependent Claims (9, 10)
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Specification