PAR reduction for EDGE clipper
View Patent ↗A method of reducing the peak-to-mean ratio of a multi-carrier signal includes the steps of: generating a residual signal from the multicarrier signal, the residual signal representing the difference between the multicarrier signal and a hard-clipped multicarrier signal. The method also includes the steps of applying a least squares function to the residual signal for each carrier of the multi-carrier signal, thereby generating a minimized residual signal for each carrier and combining the minimized residual signals and the multicarrier signal.
1. A method comprising:
generating a residual signal from a multicarrier signal, the residual signal representing a difference between the multicarrier signal and a hard-clipped multicarrier signal;
applying a least squares function to the residual signal for at least one carrier of the multicarrier signal, thereby generating a minimized residual signal for each of the at least one carrier;
filtering the minimized residual signals; and
combining the filtered minimized residual signals and the multicarrier signal.
2. A method according to claim 1 further comprising delaying the multicarrier signal, wherein combining the filtered minimized residual signals and the multicarrier signal comprises combining the filtered minimized residual signals and the delayed multicarrier signal.
3. A method according to claim 1 , wherein the generating the residual signal includes clipping the multicarrier signal to a predetermined level to thereby generate the hard-clipped multicarrier signal.
4. A method according to claim 1 , wherein the filtering comprises complex filtering.
5. The method according to claim 4 , wherein the complex filtering comprises applying at least one of a matrix function, a sampling function, a filter, or an interpolation function to the at least one minimized residual signal.
6. The method according to claim 1 , wherein combining the filtered minimized residual signals and the multicarrier signal comprises adding the filtered minimized residual signals to the multicarrier signal.
7. The method according to claim 1 , wherein generating a minimized residual signal for each of the at least one carrier comprises generating a set of impulse vectors, the number of impulse vectors in the set corresponding to the number of carriers in the multicarrier signal.
8. An apparatus comprising:
a generator configured to generate a residual signal from a multicarrier signal, the residual signal representing a difference between the multicarrier signal and a hard-clipped multicarrier signal;
an applying unit configured to apply a least squares function to the residual signal for at least one carrier of the multicarrier signal, thereby generating a minimized residual signal for each of the at least one carrier;
at least one filter, the at least one filter configured to filter the minimized residual signals; and
a combining unit configured to combine the filtered minimized residual signals and the multicarrier signal.
9. Apparatus according to claim 8 , further comprising a delaying unit configured to delay the multicarrier signal, wherein the combining unit is configured to combine the filtered minimized residual signals and the multicarrier signal by combining the filtered minimized residual signals and the delayed multicarrier signal.
10. Apparatus according to claim 8 , wherein the generator includes a clipper configured to clip the multicarrier signal to a predetermined level to thereby generate the hard-clipped multicarrier signal.
11. Apparatus according to claim 8 , wherein the at least one filter comprises a complex filter.
12. The apparatus according to claim 11 , wherein the complex filter comprises at least one of a matrix function, a sampling function, a filter, or an interpolation function.
13. A system comprising:
a transmitter apparatus configured to reduce a peak-to-mean ratio of a multicarrier signal;
a generating unit configured to generate a residual signal from a multicarrier signal, the residual signal representing a difference between the multicarrier signal and a hard-clipped multicarrier signal;
an applying unit configured to apply a least squares function to the residual signal for at least one carrier of the multicarrier signal, thereby generating a minimized residual signal for each of the at least one carrier;
at least one filter, the at least one filter configured to filter the minimized residual signals; and
a combining unit configured to combine the filtered minimized residual signals and the multicarrier signal.
14. The system according to claim 13 , wherein said generating unit, said applying unit and said combining unit are implemented in a Global System for Mobile communications (GSM) Enhanced Data rates for GSM Evolution (EDGE) mobile communication system.
15. An apparatus comprising:
generating means for generating a residual signal from a multicarrier signal, the residual signal representing a difference between the multicarrier signal and a hard-clipped multicarrier signal;
applying means for applying a least squares function to the residual signal for at least one carrier of the multicarrier signal, thereby generating a minimized residual signal for each of the at least one carrier;
filtering means for filtering the minimized residual signals; and
combining means for combining the filtered minimized residual signals and the multicarrier signal.
16. A system comprising:
transmitting means for reducing a peak-to-mean ratio of a multicarrier signal;
generating means for generating a residual signal from the multicarrier signal, the residual signal representing a difference between the multicarrier signal and a hard-clipped multicarrier signal;
applying means for applying a least squares function to the residual signal for at least one carrier of the multicarrier signal, thereby generating a minimized residual signal for each of the at least one carrier;
filtering means for filtering the minimized residual signals; and
combining means for combining the filtered minimized residual signals and the multicarrier signal.
17. An apparatus comprising:
a generator configured to generate a residual signal from a multicarrier signal, the residual signal representing a difference between the multicarrier signal and a hard-clipped multicarrier signal;
a least squares fitter configured to apply a least squares function to the residual signal for at least one carrier of the multi-carrier signal, thereby generating a minimized residual signal for each of the at least one carrier;
at least one filter, the at least one filter configured to filter the minimized residual signals; and
a summer configured to combine the filtered minimized residual signals and the multicarrier signal.
18. The apparatus according to claim 17 , wherein the generator comprises:
a hard-clipper configured to generate a hard-clipped signal from the multicarrier signal; and
a subtractor configured to generate the residual signal by subtracting the hard-clipped signal from the multicarrier signal.
19. The apparatus according to claim 17 , further comprising:
a delay element configured to delay the multicarrier signal, wherein the mixer is configured to combine the filtered minimized residual signals and the multicarrier signal by combining the filtered minimized residual signals and the delayed multicarrier signal.
20. The apparatus according to claim 17 , wherein the least squares fitter is configured to apply a least squares function to the residual signal for each carrier of the multi-carrier signal, thereby generating a set of impulse vectors, the number of impulse vectors in the set corresponding to the number of carriers in the multicarrier signal.