System and method for reducing peak-to-average power ratio for multi-carrier communication systems
The present disclosure presents a predictive signal producing method that effectively levels transmitter output power in a multi-carrier communication system and results in approaching amplifier performance normally associated with constant carrier waveforms. Embodiments of the disclosed solution offers >10 dB reduction in the peak-to-average power required to support the transmission of, for example, orthogonal frequency division modulation (“OFDM”) modulation techniques. Embodiments of the novel system and method maximize peak-to-average power ratio (“PAPR”) reduction with selective mapping and soft clipping, which may include filtering, combined. This novel approach also minimizes overhead, bit error rate, retransmissions, and increases latency as well as implementing processing cycles with a number of iterations. The disclosed system and method improves the total system DC power efficiency and provides an optimal solution for PAPR reduction in multi-carrier communication systems such as, for example, OFDM.
1. In a multi-carrier communication system, a method of transmitting data comprising the steps of:
(a) sequencing the data according to one or more unique sequences;
(b) modulating one or more of the unique sequences of data to create a modulated signal;
(c) selecting one of the modulated sequences of data based on a comparison of the peak-to-average power ratio (PAPR) of that sequence to a first threshold value;
(d) appending a data map signal associated with the selected sequence to create an appended signal;
(e) filtering said appended signal to remove amplitude peaks outside a second threshold band to thereby create a filtered signal; and,
(f) transmitting the filtered signal over the multi carrier communication system.
2. The method according to claim 1 , wherein the step of filtering includes the step of comparing samples of the selected one to a threshold and reducing the amplitude of samples exceeding the threshold.
3. The method according to claim 2 , further comprising the step of reducing the amplitude of samples adjacent to the samples exceeding the threshold.
4. In a multi-carrier communication system with a linear amplifier, a method of preventing limiting of the amplifier comprising the steps of:
(a) sequencing data to be transmitted based upon a resultant comparison of the peak-to-average power ratio (PAPR) of the modulated sequence to a first threshold value;
(b) modulating the sequenced data;
(c) appending a data map signal associated with the sequenced data to create an appended signal;
(d) sampling the appended signal;
(e) reducing the amplitude of samples which are outside a predetermined threshold; and,
(f) transmitting the resultant signal with a reduced PAPR to thereby prevent limiting of the amplifier.
5. The method according to claim 4 , further comprising the step of reducing the amplitude of samples adjacent to the samples outside a predetermined threshold.
6. In a multi-carrier communication system for transmitting data, a method for forming a data signal that reduces the required power of a transmitter comprising the steps of:
(a) providing the data to be transmitted in one or more unique sequences;
(b) modulating the one or more unique sequences thereby creating one or more unique modulated sequences;
(c) selecting for transmission one of the one or more unique modulated sequences based on a comparison of the peak-to-average power ratio of the unique modulated sequences to a first threshold value;
(d) appending a data map signal associated with the selected sequence to create an appended signal; and
(e) reducing amplitudes of the appended signal which are outside a predetermined range to thereby form a data signal that reduces power required to transmit the signal.
7. The method according to claim 6 , wherein the step of reducing amplitudes includes the step of comparing samples of the selected one to a threshold and reducing the amplitude of samples exceeding the threshold.
8. The method according to claim 7 , further comprising the step of reducing the amplitude of samples adjacent to the samples exceeding the threshold.