Method and apparatus for transmitting data in a time division duplexed (TDD) communication system
First Claim
1. In a time division duplexed (TDD) communication system, a method for transmitting data from a transmitter unit over a wireless communication link to a receiver unit, the method comprising:
- deriving a calibration function indicative of a difference between a first transfer function for a data transmission from the transmitter unit to the receiver unit and a second transfer function for a data transmission from the receiver unit to the transmitter unit;
receiving via the communication link a first transmission from the receiver unit;
estimating characteristics of the communication link based on the received first transmission;
coding and modulating the data based on one or more coding and modulation schemes to provide modulation symbols;
preconditioning the modulation symbols based on weights derived from the estimated characteristics of the communication link and the calibration function; and
transmmitting the preconditioned modulation symbols from the transmitter unit via the communication link to the receiver unit.
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Accused Products
Abstract
Techniques to process data for transmission in a time division duplexed (TDD) communication system. In one aspect, the frequency response of a forward link is estimated at a base station based on reverse link transmissions (e.g., pilots) from a terminal. Prior to a data transmission on the forward link, the base station determines a reverse transfer function based on the pilots transmitted by the terminal, “calibrates” the reverse transfer function with a calibration function to derive an estimate of a forward transfer function, and preconditions modulation symbols based on weights derived from the forward transfer function. In another aspect, the terminal estimates the “quality” of the forward link and provides this information to the base station. The base station then uses the information to properly code and modulate data prior to transmission such that the transmitted data can be received by the terminal at the desired level of performance.
152 Citations
51 Claims
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1. In a time division duplexed (TDD) communication system, a method for transmitting data from a transmitter unit over a wireless communication link to a receiver unit, the method comprising:
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deriving a calibration function indicative of a difference between a first transfer function for a data transmission from the transmitter unit to the receiver unit and a second transfer function for a data transmission from the receiver unit to the transmitter unit; receiving via the communication link a first transmission from the receiver unit;
estimating characteristics of the communication link based on the received first transmission;coding and modulating the data based on one or more coding and modulation schemes to provide modulation symbols; preconditioning the modulation symbols based on weights derived from the estimated characteristics of the communication link and the calibration function; and transmmitting the preconditioned modulation symbols from the transmitter unit via the communication link to the receiver unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A transmitter unit in a time division duplexed (TDD) communication system, comprising:
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a receiver processor operative to receive via a communication link a first transmission from a receiver unit and to estimate characteristics of the communication link based on the received first transmission; a transmit data processor operative to code and modulate data based on one or more coding and modulation schemes to provide modulation symbols; a controller operative to derive a calibration function indicative of a difference between a first transfer function for a data transmission from the transmitter unit to the receiver unit and a second transfer function for a data transmission from the receiver unit to the transmitter unit; a transmit channel processor operative to receive and precondition the modulation symbols based on weights derived at least in part from the estimated characteristics of the communication link and on the calibration function; and a modulator operative to receive, condition, and transmit the preconditioned modulation symbols via the communication link to the receiver unit. - View Dependent Claims (24, 25)
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26. A receiver unit in a time division duplexed (TDD) communication system, comprising:
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one or more antennas, each antenna configured to receive via a communication link one or more modulated signals transmitted from a transmitter unit; one or more front-end units, each front-end unit operative to process a signal from an associated antenna to provide a respective stream of received modulation symbols; a spatial processor operative to receive and process the one or more streams of received modulation symbols to provide estimated characteristics of the communication link and to further process the received modulation symbols based at least in part on the estimated characteristics of the communication link to provide one or more streams of recovered modulation symbols an further operative to match filter the received modulation symbols based on a channel response matrix indicative of the estimated characteristics of the communication link and to multiply the filtered modulation symbols with a eigenvector matrix to provide the recovered modulation symbols; and a receive data processor operative to receive and decode the one or more streams of recovered modulation symbols to provide one or more decoded data streams. - View Dependent Claims (27, 28, 29, 30)
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31. A method for transmitting data from a transmitter unit over a wireless connaunication link to a receiver unit, the method comprising:
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deriving a calibration function indicative of a difference between a data transmission from the transmitter unit to the receiver u-nit and a data transmission from the receiver unit to the transmitter unit; receiving via the communication link a first transmission from the receiver unit; estimating characteristics of the communication link based on the received first transmission; generating modulation symbols for transmission to the receiver unit; applying weights to the modulation symbols, the weights being derived from the estimated characteristics of the communication link and the calibration function; and transmitting the modulation symbols with weights applied from the transmitter unit via the communication link to the receiver unit. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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48. A transmitter unit in a time division duplexed (TDD) communication system, comprising:
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a receiver processor operative to receive via a communication link a first transmission from a receiver unit and to estimate characteristics of the communication link based on the received first transmission; a transmit data processor operative to code and modulate data based on one or more coding and modulation schemes to provide modulation symbols; a controller operative to derive a calibration function indicative of a difference between a data transmission from the transmitter unit to the receiver unit and a data transmission from the receiver unit to the transmitter unit; a transmit channel processor operative to receive and precondition the modulation symbols based on weights derived at least in part from the estimated characteristics of the communication link and on the calibration function; and a modulator operative to receive, condition, and transmit the preconditioned modulation symbols via the communication link to the receiver unit. - View Dependent Claims (49, 50, 51)
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Specification