Power control and scheduling in an OFDM system
First Claim
1. A method of scheduling sub-carriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, the method comprising:
- determining a signal to noise ratio for allocated sub-carriers; and
determining a total received power at a receiver;
determining a number of currently allocated sub-carriers; and
adjusting a number of allocated sub-carriers based, at least in part, on the signal to noise ratio, the total received power and the number of currently allocated sub-carriers.
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Accused Products
Abstract
A system and method for power control and scheduling of sub-carriers in an OFDM communication system. The receiver dynamic range can be minimized by a power control loop that attempts to maintain received power over a noise floor in a predetermined range. If the received power relative to a noise floor in allocated sub-carriers exceeds the predetermined range and the total received power is at the minimum, the scheduling system allocates an additional sub-carrier to the communication link. Additionally, if the received power relative to the noise floor is less than the predetermined range minimum, and the total received power is at a maximum, the scheduling system de-allocates a sub-carrier from the communication link. The scheduling system may also adjust an encoding rate to maintain a relatively constant symbol rate in each sub-carrier.
97 Citations
37 Claims
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1. A method of scheduling sub-carriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, the method comprising:
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determining a signal to noise ratio for allocated sub-carriers; and determining a total received power at a receiver; determining a number of currently allocated sub-carriers; and adjusting a number of allocated sub-carriers based, at least in part, on the signal to noise ratio, the total received power and the number of currently allocated sub-carriers. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of scheduling sub-carriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, the method comprising:
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determining a total received power; determining whether the total received power is less than or equal to a minimum total received power; determining a number of currently allocated sub-carriers; determining whether the number of currently allocated sub-carriers is less than a maximum number of sub-carriers in a link; determining whether a signal to noise ratio for the currently allocated sub-carriers is greater than a predetermined maximum signal to noise ratio; and incrementing the number of currently allocated sub-carriers if the total received power is less than the minimum total received power, the number of currently allocated sub-carriers is less than the maximum number of sub-carriers in the link, and the signal to noise ratio is greater than the predetermined maximum signal to noise ratio. - View Dependent Claims (9, 10, 11, 12)
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13. A method of scheduling sub-carriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, the method comprising:
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determining a total received power; determining whether the total received power is greater than or equal to a maximum total received power; determining a number of currently allocated sub-carriers; determining whether the number of currently allocated sub-carriers is greater than one; determining whether a signal to noise ratio for the currently allocated sub-carriers is less than a predetermined minimum signal to noise ratio; and decrementing the number of currently allocated sub-carriers if the total received power is greater than the maximum total received power, the number of currently allocated sub-carriers is greater than one, and the signal to noise ratio is less than the predetermined minimum signal to noise ratio. - View Dependent Claims (14, 15, 16, 17)
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18. A method of scheduling sub-carriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, the method comprising:
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determining a signal to noise ratio for allocated sub-carriers in a received OFDM signal; determining if the signal to noise ratio is within a predetermined range; determining a total received power at a receiver; determining a number of currently allocated sub-carriers; and scheduling a number of sub-carriers for a communication link from a terminal to a base station based, at least in part, on whether the signal to noise is within the predetermined range, the total received power and the number of currently allocated sub-carriers. - View Dependent Claims (19, 20)
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21. An apparatus for scheduling sub-carriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, the apparatus comprising:
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a noise estimator configured to estimate a noise level in a sub-carrier frequency band; a signal to noise ratio determination module coupled to the noise estimator and configured to determine a signal to noise ratio in the sub-carrier frequency band and a total received power at a receiver; and a sub-carrier scheduler coupled to the signal to noise ratio determination module, the sub-carrier scheduler configured to schedule a number of sub-carriers based, at least in part, on whether the signal to noise is within a predetermined range and the total received power at the receiver. - View Dependent Claims (22, 23)
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24. An apparatus for scheduling sub-carriers in an Orthogonal Frequency Division Multiplexing (QFDM) system, the apparatus comprising:
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a noise estimator configured to estimate a noise level in a sub-carrier frequency band; a signal to noise ratio determination module coupled to the noise estimator and configured to determine a signal to noise ratio in the sub-carrier frequency band and a total received power at a receiver; and a sub-carrier scheduler coupled to the signal to noise ratio determination module, wherein the sub-carrier scheduler increments a number of sub-carriers if the total received power is less than a minimum total received power, a number of currently allocated sub-carriers is less than a maximum number of sub-carriers, and the signal to noise ratio is greater than a predetermined maximum signal to noise ratio. - View Dependent Claims (25, 26)
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27. An apparatus for scheduling sub-carriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, the apparatus comprising:
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a noise estimator configured to estimate a noise level in a sub-carrier frequency band; a signal to noise ratio determination module coupled to the noise estimator and configured to determine a signal to noise ratio in the sub-carrier frequency band and a total received power at a receiver; and a sub-carrier scheduler coupled to the signal to noise ratio determination module, wherein the sub-carrier scheduler decrements a number of allocated sub-carriers if the total received power is greater than a maximum total received power, a number of currently allocated sub-carriers is greater than one, and the signal to noise ratio is less than a predetermined minimum signal to noise ratio. - View Dependent Claims (28, 29)
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30. An apparatus for scheduling sub-carriers in an Orthogonal Frequency Division Multiplexing (OEDM) system, the apparatus comprising:
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a detector configured to determine a total received power; and a processor coupled with the detector and configured to determine a signal to noise ratio in a sub-carrier frequency band and to increment a number of sub-carriers if the total received power is less than a minimum total received power, a number of currently allocated sub-carriers is less than a maximum number of sub-carriers, and the signal to noise ratio is greater than a predetermined maximum signal to noise ratio. - View Dependent Claims (31, 32, 33)
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34. An apparatus for scheduling sub-carriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, the apparatus comprising:
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a detector configured to determine a total received power; and a processor coupled with the detector and configured to determine a signal to noise ratio in a sub-carrier frequency band and to decrement a number of allocated sub-carriers if the total received power is greater than a maximum total received power, a number of currently allocated sub-carriers is greater than one, and the signal to noise ratio is less than a predetermined minimum signal to noise ratio. - View Dependent Claims (35, 36, 37)
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Specification