Communication method and radio transmitter

• US 8,325,838 B2
• Filed: 10/12/2011
• Issued: 12/04/2012
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Hamaguchi, Yasuhiro
• Primary Examiner(s): FILE, ERIN M
• Application Number:
  US13/271,936
• Publication Number:
  US 20120033753A1
• Time in Patent Office: 419 Days
• Field of Search: 375/260
• US Class Current: 375/260
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/2627 Modulators
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/26524 Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0039 Frequency-contiguous, i.e. with no allocation of frequencies for one user or terminal between the frequencies allocated to another
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/0473 the resource being transmission power
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Radio transmission is performed even to a communication party whose bandwidth that can be used for transmission and reception is limited without having an influence of an offset of a DC component. A radio transmitter applied to an OFDMA communication system in which a plurality of different terminals performs communication using OFDM signals at the same time that includes a mapping part that allocates transmission power to each subcarrier, and also selects a subcarrier to which minimum power of the transmission power to be allocated is allocated and modulates transmission data in units of communication slots to output the modulated data; and a transmission part for transmitting radio signals including the modulated data using each of the subcarriers.

Claims

1. A receiving apparatus operable in a wireless communication system, comprising:

a receiving circuit configured for receiving from a transmitting apparatus an orthogonal frequency division multiplexing (OFDM) signal having a plurality of subcarriers allocated among one or more frequency channels comprising all or a part of a frequency band used by the transmitting apparatus for transmitting signals, wherein the one or more frequency channels correspond to a usable bandwidth of the receiving circuit, and wherein the OFDM signal comprises a data portion in which data to be received by the receiving apparatus is allocated to each of a plurality of used subcarriers, but not to a plurality of unused subcarriers, the unused subcarriers having been determined by the transmitting apparatus based on the usable bandwidth of the receiving circuit;

wherein the OFDM signal further comprises a broadcast portion carrying broadcast information;

wherein the broadcast information comprises an indirect indication of the positions of the unused subcarriers within the data portion of the OFDM signal, whereby the positions of the unused subcarriers within the data portion are mutually known between the transmitting apparatus and the receiving apparatus in relation to the indirect indication;

signal processing components configured to demodulate the plurality of used subcarriers and to refrain from demodulating the plurality of unused subcarriers within the data portion; and

signal transmitting components configured to notify the transmitting apparatus of the usable bandwidth.

2. The receiving apparatus according to claim 1 wherein the indirect indication comprises an identification of the frequency channels used for transmission of the data portion of the OFDM signal.

3. The receiving apparatus according to claim 1 wherein in the broadcast portion the broadcast information is allocated to each of a second plurality of used subcarriers, but not to a second plurality of unused subcarriers, wherein the second plurality of unused subcarriers comprise one or more subcarriers positioned at a center of each of the one or more frequency channels within the broadcast portion of the OFDM signal;

wherein the signal processing components are configured to refrain from demodulating the second plurality of unused subcarriers; and

wherein the signal processing components are configured to refrain from demodulating one or more of the plurality of unused subcarriers positioned at a center of the data portion of the OFDM signal.

4. The receiving apparatus according to claim 3 wherein the indirect indication comprises an identification of the frequency channels used for transmission of the data portion of the OFDM signal.

5. The receiving apparatus of claim 1 wherein each of the one or more frequency channels comprises 64 subcarriers.

6. The receiving apparatus according to claim 1 wherein the signal processing components are further configured to convert radio frequency signals representing the plurality of subcarriers to analog signals according to a center frequency of the usable bandwidth and to convert the analog signals to digital signals.

7. A method for processing orthogonal frequency division multiplexing (OFDM) signals received by a receiving apparatus operable in a wireless communication system, the method comprising:

notifying a transmitting apparatus of a usable bandwidth of the receiving apparatus;

receiving an OFDM signal from the transmitting apparatus, the OFDM signal having a plurality of subcarriers allocated among one or more frequency channels comprising all or a part of a frequency band used by the transmitting apparatus for transmitting signals, wherein the one or more frequency channels correspond to the usable bandwidth, and wherein the OFDM signal comprises a data portion in which data to be received by the receiving apparatus is allocated to each of a plurality of used subcarriers, but not to a plurality of unused subcarriers, the unused subcarriers having been determined by the transmitting apparatus based on the usable bandwidth;

wherein the OFDM signal further comprises a broadcast portion carrying broadcast information;

wherein the broadcast information comprises an indirect indication of the positions of the unused subcarriers within the data portion of the OFDM signal, whereby the positions of the unused subcarriers within the data portion are mutually known between the transmitting apparatus and the receiving apparatus in relation to the indirect indication; and

demodulating the plurality of used subcarriers within the data portion and refraining from demodulating the unused subcarriers within the data portion.

8. The method according to claim 7 wherein the indirect indication comprises an identification of the frequency channels used in transmission of the data portion of the OFDM signal.

9. The method according to claim 7 wherein in the broadcast portion the broadcast information is allocated to each of a second plurality of used subcarriers, but not to a second plurality of unused subcarriers;

and

wherein the receiving circuit is configured to refrain from demodulating one or more of the second plurality of unused subcarriers positioned at a center of each of the one or more frequency channels within the broadcast portion of the OFDM signal and to refrain from demodulating one or more of the plurality of unused subcarriers positioned at a center of the data portion of the OFDM signal.

10. The method according to claim 7 further comprising:

converting radio frequency signals representing the plurality of subcarriers to analog signals according to a center frequency of the usable bandwidth; and

converting the analog signals to digital signals.

11. The method of claim 7 wherein each of the one or more frequency channels comprises 64 subcarriers.

12. A receiving apparatus operable in a wireless communication system, comprising:

a receiving circuit configured for receiving from a transmitting apparatus an orthogonal frequency division multiplexing (OFDM) signal having a plurality of subcarriers allocated among one or more frequency channels comprising all or a part of a frequency band used by the transmitting apparatus for transmitting signals, wherein the one or more frequency channels correspond to usable bandwidth of the receiving circuit, wherein each of the one or more frequency channels comprises 64 subcarriers, and wherein the OFDM signal comprises a a data portion in which data to be received by the receiving apparatus is allocated to each of a first plurality of used subcarriers, but not to a first plurality of unused subcarriers, the first plurality of unused subcarriers having been determined by the transmitting apparatus based on the usable bandwidth, and wherein the OFDM signal further comprises a broadcast portion in which broadcast information is allocated to each of a second plurality of used subcarriers, but not to a second plurality of unused subcarriers;

wherein the broadcast information comprises an indirect indication of the positions of the first plurality of unused subcarriers within the data portion of the OFDM signal, whereby the positions of the first plurality of unused subcarriers within the data portion are mutually known between the transmitting apparatus and the receiving apparatus in relation to the indirect indication;

signal processing components configured to refrain from demodulating one or more of the second plurality of unused subcarriers positioned at a center of each of the one or more frequency channels within the broadcast portion of the OFDM signal and to refrain from demodulating one or more of the first plurality of unused subcarriers positioned at a center of the data portion of the OFDM signal; and

signal transmitting components configured to notify the transmitting apparatus of the usable bandwidth.

13. The receiving apparatus according to claim 12 wherein the indirect indication comprises an identification of the frequency channels used for transmission of the data portion of the OFDM signal.

14. The receiving apparatus of claim 12 wherein the signal processing components are further configured to convert radio frequency signals representing the plurality of subcarriers to analog signals according to a center frequency of the usable frequency bandwidth and to convert the analog signals to digital signals.

15. A method for processing orthogonal frequency division multiplexing (OFDM) signals received by a receiving apparatus operable in a wireless communication system, the method comprising:

receiving from a transmitting apparatus an OFDM signal having a plurality of subcarriers allocated among a plurality of frequency channels comprising all or a part of a frequency band used by the transmitting apparatus for transmitting signals, wherein the one or more frequency channels correspond to a usable bandwidth of the receiving circuit, wherein each of the frequency channels comprises 64 subcarriers, and wherein the OFDM signal comprises a data portion in which data to be received by the receiving apparatus is allocated to each of a first plurality of used subcarriers, but not to a first plurality of unused subcarriers, the first plurality of unused subcarriers having been determined by the transmitting apparatus based on the usable bandwidth of the receiving circuit, and wherein the OFDM signal further comprises a broadcast portion in which broadcast information is allocated to each of a second plurality of used subcarriers, but not to a second plurality of unused subcarriers;

wherein the broadcast information comprises an indirect indication of the positions of the first plurality of unused subcarriers within the data portion of the OFDM signal, whereby the positions of the first plurality of unused subcarriers within the data portion are mutually known between the transmitting apparatus and the receiving apparatus in relation to the indirect indication; and

refraining from demodulating one or more of the second plurality of unused subcarriers positioned at a center of each of the one or more frequency channels within the broadcast portion of the OFDM signal, and refraining from demodulating one or more of the first plurality of unused subcarriers positioned at a center of the data portion of the OFDM signal.

16. The method according to claim 15 further comprising the step of notifying the transmitting apparatus of the usable bandwidth.

17. The method according to claim 15 wherein the indirect indication comprises an identification of the frequency channels used for transmission of the data portion of the OFDM signal.

18. The method according to claim 15 further comprising the steps of:

converting radio frequency signals representing the plurality of subcarriers to analog signals according to a center frequency of the usable bandwidth; and

converting the analog signals to digital signals.