Transmitter, receiver and transmitting method in multi-carrier transmission system

• US 7,006,429 B2
• Filed: 02/08/2002
• Issued: 02/28/2006
• Est. Priority Date: 09/30/1999
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yoshida, Makoto, Ishizu, Eizou
• Primary Examiner(s): Phan, Man U.
• Application Number:
  US10/072,065
• Publication Number:
  US 20020089923A1
• Time in Patent Office: 1,481 Days
• Field of Search: 370205-208, 370343-431, 370468-482, 370/510, 375260-295, 375298-364, 375259-285
• US Class Current: 370/208
• CPC Class Codes: H04L 27/2615 Reduction thereof using coding

Abstract

An object of the present invention is to provide a method for suppressing peak power at a high encoding rate in a multi-carrier transmission system.

The present invention provides a transmitter for transmitting a multi-carrier signal, in which when generating 128 patterns used to suppress the peak power of 8-bit sub-carrier mapping signals from 7-bit information bits in a encoding unit 9, a sub-carrier generation unit 11, for example, divides the signal point of QPSK modulation into orthogonal groups, generates a sub-carrier mapping signal in which a part of sub-carriers is dependent on the signal point of another sub-carrier and a receiver for receiving such a multi-carrier signal.

Claims

1. A transmitter in a multi-carrier transmission system for conducting communications using a modulation method for dividing a transmission band into a plurality of sub-carriers and mapping each sub-carrier using a complex signal point expressed by k bits, comprising:

an encoding unit converting transmitting data information, the number of bits of which is smaller than kn bits, which are data used to express n sub-carriers, into a signal point pattern, in which the peak power of a transmitting signal is small, of signal point patterns expressed by the kn bits, the encoding unit further comprising a sub-carrier generation unit generating sub-carriers composed of signal points in which the signal point pattern with a small peak power is divided into two orthogonal groups in four quadrants of an IQ plane and in which the signal point of the part of sub-carriers has a prescribed correlation with a signal point of another sub-carrier; and

a mapping unit generating transmitting signals of n sub-carriers using an output of the encoding unit.

2. The transmitter in a multi-carrier transmission system according to claim 1, wherein

said sub-carrier generation unit generates sub-carriers with a phase condition in which, of 2 k signal points of a modulation signal, a part of the signal points is dependent on another sub-carrier.

3. The transmitter in a multi-carrier transmission system according to claim 2, wherein

said sub-carrier generation unit generates sub-carriers in which, of four signal points of a QPSK signal, the signal point of the part of sub-carriers is dependent on the signal point of another sub-carrier.

4. The transmitter in a multi-carrier transmission system according to claim 3, wherein

said encoding unit suppresses the peak power to almost 2 dB at an encoding rate of ⅞

by generating eight sub-carrier mapping signals from seven information bits.

5. The transmitter in a multi-carrier transmission system according to claim 2, wherein

said sub-carrier generation unit comprises a logical circuit.

6. The transmitter in a multi-carrier transmission system according to claim 2, wherein

said sub-carrier generation unit comprises a ROM.

7. A four-sub-carrier transmitter for 4m sub-carriers providing m transmitters, each of which comprises both the said encoding unit and mapping unit according to claim 1, in parallel and independently.

8. A receiver in a multi-carrier transmission system for conducting communications using a modulation method for dividing a transmission band into a plurality of sub-carriers and mapping each sub-carrier using a complex signal point expressed by k bits, comprising:

a demapping unit converting receiving signals obtained by converting transmitting data information, the number of bits of which is smaller than kn bits, which are data used to express n sub-carriers, into a signal point pattern, in which the peak power of a transmitting signal is small, of signal point patterns expressed by the kn bits and transmitted from a transmitting side;

a mapping signal generation unit generating all signal point patterns that might be transmitted from the transmitting side; and

a hard-decision decoding unit further comprising a comparison unit comparing signal point patterns of an output of the demapping unit with signal point patterns of an output of the mapping signal generation unit and an output unit outputting data corresponding to one signal point pattern, in which the signal point pattern outputted from the demapping unit and the signal point pattern outputted from the mapping signal generation unit are matched.

9. The receiver in a multi-carrier transmission system according to claim 8, wherein said mapping signal generation unit further comprises:

a timing control unit, including a counter sequentially generating information bits of less than 2 k when decoding n sub-carrier signals;

an encoding unit inputting information bits outputted from a timing control unit and converting the information bits into a signal point pattern, in which the peak power of a transmitting signal is small, of signal point patterns expressed by 2 k bits, the encoding unit further comprising a sub-carrier generation unit generating sub-carriers composed of signal points in which the signal point pattern with small peak power is divided into two orthogonal groups in four quadrants of an IQ plane and in which a signal point of a part of sub-carriers has a prescribed correlation with a signal point of another sub-carrier.

10. The receiver in a multi-carrier transmission system according to claim 9, further comprising:

a transmission error detection unit detecting a transmission error when detecting a receiving signal that does not belong to any of the signal point patterns that might be transmitted from a transmitting side, of outputs of said demapping unit; and

a decoding operation stoppage control unit stopping a decoding operation by said hard-decision decoding unit when said transmission error detection unit detects a transmission error.

11. A receiver in a multi-carrier transmission system for conducting communications using a modulation method for dividing a transmission band into a plurality of sub-carriers and mapping each sub-carrier using a complex signal point expressed by k bits, comprising:

a demapping unit converting a receiving signal obtained by converting transmitting data information, the number of bits of which is smaller than kn bits, which are data used to express n sub-carriers, into a signal point pattern, in which the peak power of a transmitting signal is small, of signal point patterns expressed by the kn bits and transmitted from a transmitting side by a sub-carrier composed of signal points in which the signal point pattern with small peak power is divided into two orthogonal groups in four quadrants of an IQ plane and in which a signal point of a part of sub-carriers has a prescribed correlation with a signal point of another sub-carrier, into a demapping signal used to be compared with all signal point patterns that might be transmitted from the transmitting side;

a transmission error detection unit detecting a transmission error when detecting a receiving signal that does not belong to any of the signal point patterns that might be transmitted from the transmitting side, of outputs of the demapping unit.

12. The receiver in a multi-carrier transmission system according to claim 11, wherein said error detection unit comprises a logical circuit.

13. The receiver in a multi-carrier transmission system according to claim 11, wherein said error detection unit comprises a ROM.

16. The receiver in a multi-carrier transmission system according to claim 11, further comprising

an error correction decoding unit performing error correction decoding of a receiving data signal using code distances between the receiving signal and all the transmission availability signals.

14. A receiver in a multi-carrier transmission system for conducting communications using a modulation method for dividing a transmission band into a plurality of sub-carriers and mapping each sub-carrier using a complex signal point expressed by k bits, comprising:

a mapping unit mapping all signal point patterns that can be expressed by kn bits in relation to n sub-carriers and that might be transmitted from a transmitting side in order to convert the signal point patterns into respective transmitting signals of n sub-carriers, as in the transmitting side and outputting a transmission availability signal; and

a soft-decision decoding unit further comprising an output unit outputting a signal point pattern before the mapping of a transmission availability signal with the shortest code distance of code distances between a receiving signal obtained by converting transmitting data information, the number of bits of which is smaller than kn bits, which are data used to express n sub-carriers, into a signal point pattern, in which the peak power of a transmitting signal is small, of signal point patterns expressed by the kn bits and transmitted from a transmitting side by a sub-carrier composed of signal points in which the signal point pattern with small peak power can be divided into two orthogonal groups in four quadrants of an IQ plane and having a sub-carrier generation unit generating sub-carriers in which a signal point of a part of sub-carriers has a prescribed correlation with a signal point of another sub-carrier, and all the transmission availability signals as a decoding signal.

15. The receiver in a multi-carrier transmission system according to claim 14, wherein said output unit further comprising:

a code distance calculation unit calculating a distance between a receiving data signal and an output of said mapping unit;

a minimum distance memory unit storing a minimum code distance;

a code distance comparison unit comparing an output of the minimum distance memory unit and an output of the code distance calculation unit and updating said minimum distance memory unit when a code distance is shorter than the distance stored in the minimum distance memory unit; and

a memory unit outputting data corresponding to the minimum distance as decoding data.

17. A transmitting method in a multi-carrier transmission system for conducting communications using a modulation method for dividing a transmission band into a plurality of sub-carriers and mapping each sub-carrier using a complex signal point expressed by k bits, comprising:

generating a sub-carrier composed of signal points in which the signal point pattern with small peak power can be divided into two orthogonal groups in four quadrants of an IQ plane and has a sub-carrier generation unit generating sub-carriers in which a signal point of a part of sub-carriers has a prescribed correlation with a signal point of another sub-carrier when converting receiving signals obtained by converting transmitting data information, the number of bits of which is smaller than kn bits, which are data used to express n sub-carriers, into a signal point pattern, in which the peak power of a transmitting signal is small, of signal point patterns expressed by the kn bits; and

generating transmitting signals by mapping the encoding result.

18. A receiving method in a multi-carrier transmission system for conducting communications using a modulation method for dividing a transmission band into a plurality of sub-carriers and mapping each sub-carrier using a complex signal point expressed by k bits, comprising:

converting a receiving signal obtained by converting transmitting data information, the number of bits of which is smaller than kn bits, which are data used to express n sub-carriers, into a signal point pattern, in which the peak power of a transmitting signal is small, of signal point patterns expressed by the kn bits and transmitted from a transmitting side by a sub-carrier composed of signal points in which the signal point pattern with small peak power can be divided into two orthogonal groups in four quadrants of an IQ plane and having a sub-carrier generation unit generating sub-carriers in which a signal point of a part of sub-carriers has a prescribed correlation with a signal point of another sub-carrier, into demapping signals (demapping step);

generating all signal point patterns that might be transmitted from the transmitting side (mapping signal generation step); and

comparing signal point patterns of an output of the demapping step and signal point patterns of an output of the mapping signal generation step (comparison step) and outputting the transmitting data information corresponding to one signal point pattern, in which the signal point pattern outputted from the demapping unit and the signal point pattern outputted from the mapping signal generation unit are matched, as a decoding data signal.

19. A receiving method in a multi-carrier transmission system for conducting communications using a modulation method for dividing a transmission band into a plurality of sub-carriers and mapping each sub-carrier using a complex signal point expressed by k bits, comprising:

mapping all signal point patterns that can be expressed by kn bits in relation to n sub-carriers and that might be transmitted from a transmitting side in order to convert the signal point patterns into respective transmitting signals of n sub-carriers, as in the transmitting side and outputting a transmission availability signal (mapping step); and

outputting the signal point pattern before mapping of the transmission availability signal with the shortest code distance of code distances between a receiving signal obtained by converting transmitting data information, the number of bits of which is smaller than kn bits, which are data used to express n sub-carriers, into the signal point pattern, in which the peak power of a transmitting signal is small, of signal point patterns expressed by the kn bits and transmitted from a transmitting side by a sub-carrier composed of signal points in which the signal point pattern with small peak power can be divided into two orthogonal groups in four quadrants of an IQ plane and having a sub-carrier generation sub-unit generating sub-carriers in which the signal point of a part of sub-carriers has a prescribed correlation with the signal point of another sub-carrier, and all the transmission availability signals as a decoding signal (output step) (soft-decision decoding step).

20. A transmitter in a multi-carrier transmission system for conducting communications using a modulation method for dividing a transmission band into a plurality of sub-carriers and mapping each sub-carrier using a complex signal point expressed by k bits, comprising:

an encoding unit converting transmitting data information, the number of bits of which is smaller than kn bits, which are data used to express n sub-carriers, into a signal point pattern, in which the peak power of a transmitting signal is small, of signal point patterns expressed by the 2 k bits, the encoding unit further comprising a sub-carrier generation unit generating the sub-carrier in which the signal point with small peak power can be divided into two orthogonal groups in four quadrants of an IQ plane and in which the signal point of a part of sub-carriers has a prescribed correlation with the signal point of another sub-carrier.