Method for linearization of RF transmission electronics using baseband pre-distortion in T/R compensation pilot signals

Claim 2

A highly bandwidth-efficient communications method to minimize harmonic distortion imposed by RF equipment, comprising the steps of: generating pilot tones bearing a prearranged symbol pattern at a first station; pre-distorting said pilot tones with a pre-distortion processor at the first station while the pilot tones are in a baseband; said pre-distorting step including selecting one of a plurality of digital filtering algorithms to predistort the pilot tones in the baseband, each of the digital filtering algorithms applying a progressively greater amount of pre-distortion to the pilot tones in the baseband; initially applying a relatively small amount of pre-distortion to the pilot tones in the base band; transmitting the pre-distorted pilot tones in a first channel by an RF transmitter at the first station to a second, receiving station, the transmitted pilot tones including harmonic distortion imposed by the RF transmitter at the first station; receiving at the second receiving station the pilot tones with their harmonic distortion; comparing the received pilot tones with the prearranged symbol pattern, and generating an error signal indicating a degree of severity of the harmonic distortion in the pilot tone signals; sending the error signal from the second station to the first station; controlling the pre-distortion processor at the first station in response to the error signal, to select another one of the plurality of digital filtering algorithms that will apply a progressively greater amount of pre-distortion to pilot tones in the baseband; and continuing the above steps until the second station indicates that the harmonic distortion in the first channel pilot tones is no longer significant.

Claim 3

In the highly bandwidth-efficient communications method of claim 1, further comprising: said first station is a base station and said second station is a remote station.

Claim 4

In the highly bandwidth-efficient communications method of claim 1, further comprising: said first station is a remote station and said second station is a base station.

Claim 5

The highly bandwidth-efficient communications method of claim 1, wherein said first station and said second station are part of a wireless discrete multitone spread spectrum communications system.

Claim 6

A highly bandwidth-efficient communications method, comprising the steps of: receiving at a base station during a first time period a first spread signal comprising a first data signal spread over a plurality of discrete tones; adaptively despreading the signal received at the base station by using despreading codes that are based on the characteristics of the received spread signal; spreading a second data signal at the base station with spreading codes, that distributes the second data signal over a plurality of discrete tones, forming a second spread signal; pre-distorting the second spread signal in the baseband by a first amount using a first digital filtering algorithm to avoid producing harmonics when the resultant signal is transmitted; transmitting said second spread signal during a second time period; receiving at the base station during a third time period a third spread signal comprising an error signal derived from said pre-distorted second spread signal; pre-distorting a fourth spread signal in the baseband by a second amount using a second digital filtering algorithm in response to said error signal, to avoid producing harmonics when the resultant signal is transmitted; and transmitting said fourth spread signal during a fourth time period.

Claim 7

A highly bandwidth-efficient communications method, comprising the steps of: receiving at a base station during a first time period a first spread signal comprising a first data signal spread over a plurality of discrete tones; adaptively despreading the signal received at the base station by using despreading codes that are based on the characteristics of the received spread signal; spreading a second data signal at the base station with spreading codes, that distributes the second data signal over a plurality of discrete tones, forming a second spread signal; pre-distorting the second spread signal in the baseband by a first amount using a first digital filtering algorithm to avoid producing harmonics when the resultant signal is transmitted; transmitting said second spread signal during a second time period; receiving at the base station during a third time period a third spread signal comprising an error signal derived from said pre-distorted second spread signal; pre-distorting a fourth spread signal in the baseband by a second amount using a second digital filtering algorithm in response to said error signal, to avoid producing harmonics when the resultant signal is transmitted; and transmitting said fourth spread signal during a fourth time period.

Claim 8

The highly bandwidth-efficient communications method of claim 5, which further comprises: linearizing RF equipment in said base station using a compensation value derived from said pre-distorting steps.

Claim 9

A highly bandwidth-efficient communications system to minimize harmonic distortion imposed by RF equipment, comprising: means for generating pilot tones bearing a prearranged symbol pattern at a first station; means for pre-distorting said pilot tones with a pre-distortion processor at the first station while the pilot tones are in a baseband; means for selecting one of a plurality of digital filtering algorithms to pre-distort the pilot tones in the baseband, each of the digital filtering algorithms applying a progressively greater amount of pre-distortion to the pilot tones in the baseband; means for initially applying a relatively small amount of pre-distortion to the pilot tones in the base band; means for transmitting the pre-distorted pilot tones in a first channel by an RF transmitter at the first station to a second, receiving station, the transmitted pilot tones including harmonic distortion imposed by the RF transmitter at the first station; means for receiving at the second receiving station the pilot tones with their harmonic distortion; means for comparing the received pilot tones with the prearranged symbol pattern, and generating an error signal indicating a degree of severity of the harmonic distortion in the pilot tone signals; means for sending the error signal from the second station to the first station; means for controlling the pre-distortion processor at the first station in response to the error signal, to select another one of the plurality of digital filtering algorithms that will apply a progressively greater amount of pre-distortion to pilot tones in the baseband; and means at the second station for indicating that the harmonic distortion in the first channel pilot tones is no longer significant.

Claim 10

A highly bandwidth-efficient communications system to minimize harmonic distortion imposed by RF equipment, comprising: means for generating pilot tones bearing a prearranged symbol pattern at a first station; means for pre-distorting said pilot tones with a pre-distortion processor at the first station while the pilot tones are in a baseband; means for selecting one of a plurality of digital filtering algorithms to pre-distort the pilot tones in the baseband, each of the digital filtering algorithms applying a progressively greater amount of pre-distortion to the pilot tones in the baseband; means for initially applying a relatively small amount of pre-distortion to the pilot tones in the base band; means for transmitting the pre-distorted pilot tones in a first channel by an RF transmitter at the first station to a second, receiving station, the transmitted pilot tones including harmonic distortion imposed by the RF transmitter at the first station; means for receiving at the second receiving station the pilot tones with their harmonic distortion; means for comparing the received pilot tones with the prearranged symbol pattern, and generating an error signal indicating a degree of severity of the harmonic distortion in the pilot tone signals; means for sending the error signal from the second station to the first station; means for controlling the pre-distortion processor at the first station in response to the error signal, to select another one of the plurality of digital filtering algorithms that will apply a progressively greater amount of pre-distortion to pilot tones in the baseband; and means at the second station for indicating that the harmonic distortion in the first channel pilot tones is no longer significant.

Claim 11

In the highly bandwidth-efficient communications system of claim 7, further comprising: said first station is a base station and said second station is a remote station.

Claim 12

In the highly bandwidth-efficient communications system of claim 7, further comprising: said first station is a remote station and said second station is a base station.

Claim 13

The highly bandwidth-efficient communications system of claim 7, wherein said first station and said second station are part of a wireless discrete mutilation spread spectrum communications system.

Claim 14

A highly bandwidth-efficient communications system, comprising: means for receiving at a base station during a first time period a first spread signal comprising a first data signal spread over a plurality of discrete tones; means for adaptively despreading the signal received at the base station by using despreading codes that are based on the characteristics of the received spread signal; means for spreading a second data signal at the base station with spreading codes, that distributes the second data signal over a plurality of discrete tones, forming a second spread signal; means for pre-distorting the second spread signal in the baseband by a first amount using a first digital filtering algorithm to avoid producing harmonics when the resultant signal is transmitted; means for transmitting said second spread signal during a second time period; means for receiving at the base station during a third time period a third spread signal comprising an error signal derived from said pre-distorted second spread signal; means for pre-distorting a fourth spread signal in the baseband by a second amount using a second digital filtering algorithm in response to said error signal. to avoid producing harmonics when the resultant signal is transmitted; and means for transmitting said fourth spread signal during a fourth time period.

Claim 15

A highly bandwidth-efficient communications system, comprising: means for receiving at a base station during a first time period a first spread signal comprising a first data signal spread over a plurality of discrete tones; means for adaptively despreading the signal received at the base station by using despreading codes that are based on the characteristics of the received spread signal; means for spreading a second data signal at the base station with spreading codes, that distributes the second data signal over a plurality of discrete tones, forming a second spread signal; means for pre-distorting the second spread signal in the baseband by a first amount using a first digital filtering algorithm to avoid producing harmonics when the resultant signal is transmitted; means for transmitting said second spread signal during a second time period; means for receiving at the base station during a third time period a third spread signal comprising an error signal derived from said pre-distorted second spread signal; means for pre-distorting a fourth spread signal in the baseband by a second amount using a second digital filtering algorithm in response to said error signal. to avoid producing harmonics when the resultant signal is transmitted; and means for transmitting said fourth spread signal during a fourth time period.

Claim 16

The highly bandwidth-efficient communications system of claim 11, which further comprises: means for linearizing RF equipment in said base station using a compensation value derived from said pre-distorting means.