Transmitter with adaptive back-off

摘要

A transmitter for transmitting data symbols using an orthogonal frequency division multiplexing (OFDM) scheme, the transmitter comprising: a modulator for generating a plurality of mutually orthogonal sub-carriers, each of the plurality of sub-carriers being modulated with a stream of data symbols to be transmitted; an amplifier for amplifying a signal containing the plurality of modulated sub-carriers for transmission of the signal; and a symbol processor for processing the data symbols of the plurality of sub-carriers, the symbol processor being configured to compute a plurality of EVM values for each data symbol to be transmitted, each of the plurality of EVM values being computed based on a different one of a plurality of candidate back-off values for the amplifier, and to select one of the plurality of candidate back-off values to apply to the transmitter for the data symbol based on the computed EVM values.

主权项

1. A transmitter for transmitting data symbols using an orthogonal frequency division multiplexing (OFDM) scheme, the transmitter comprising:
a modulator for generating a plurality of mutually orthogonal sub-carriers, each of the plurality of sub-carriers being modulated with a stream of data symbols to be transmitted; an amplifier for amplifying a signal containing the plurality of modulated sub-carriers for transmission of the signal; and a symbol processor for processing the data symbols of the plurality of sub-carriers, the symbol processor being configured to compute a plurality of error vector magnitude (EVM) values for each data symbol to be transmitted, each of the plurality of EVM values being computed based on a different one of a plurality of candidate back-off values for the amplifier, and to select one of the plurality of candidate back-off values to apply to the transmitter for the data symbol based on the computed EVM values, wherein the symbol processor is configured to select one of the plurality of candidate back-off values for which the computed EVM value meets a constant target EVM value that must be achieved by all of the transmitted symbols, wherein the constant target EVM value is based on a minimum required signal to noise ratio (SNR) that must be achieved at a receiver to permit good reception of the transmitted symbol, and wherein the constant target EVM value is dependent upon the data rate of the transmitted symbol.