Radio communication method, radio communication system, and radio transmission apparatus

• US 8,681,688 B2
• Filed: 09/12/2008
• Issued: 03/25/2014
• Est. Priority Date: 09/12/2007
• 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, Kubota, Minoru, Namba, Hideo, Toh, Shimpei, Yokomakura, Kazunari
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): FARAHMAND, ASHIL S
• Application Number:
  US12/677,742
• Publication Number:
  US 20100215080A1
• Time in Patent Office: 2,020 Days
• Field of Search: 370208-215, 370/318, 375/260, 455/522
• US Class Current: 370/318
• CPC Class Codes: H04B 1/692 Hybrid techniques using combinations of two or more spread spectrum techniques
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2201/70706 with means for reducing the peak-to-average power ratio
• CPC Class Codes: H04B 7/15 Active relay systems
• CPC Class Codes: H04J 13/0044 OVSF [orthogonal variable spreading factor]
• CPC Class Codes: H04J 13/20 having an orthogonal variable spreading factor [OVSF]
• CPC Class Codes: H04L 27/2615 Reduction thereof using coding
• CPC Class Codes: H04L 27/2636 with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 5/0021 in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA
• CPC Class Codes: H04L 5/026 using code division
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames

Abstract

A transmission apparatus according to the present invention includes: an encoding section; a modulation section; a variable-SF spreading section that performs spreading with variable SF according to control information A from a control section; an IDFT section that performs IDFT on output from the spreading section; a GI inserting section; a parallel/serial conversion section that converts output from the GI inserting section into a serial data sequence; a digital/analog conversion section; and an RF section that transmits a signal from an antenna after converting the signal to a frequency band for analog signal transmission and controlling it to an appropriate transmission power. The control section is configured to generate control information A for determining the variable SF and input the information A to the variable-SF spreading section and the RF section. In control information A, SF is varied depending on transmission power required.

Claims

1. An OFDM transmission apparatus comprising:

a variable-spreading-factor spreading section configured to perform discrete Fourier transform on data signals to generate n sets of spread signals, n being a value equal to or greater than 1;

a sub-carrier allocation section configured to allocate said n sets of spread signals to a plurality of sub-carriers;

an inverse discrete Fourier transform section configured to perform inverse discrete Fourier transform on said n sets of spread signals allocated; and

a control section configured to control, according to the value of n, a limit of a power for transmitting IDFT transformed said n sets of spread signals, wherein

the control section is further configured to control the limit of the power in a case that the value of n is equal to or greater than a value of 2 to be smaller than the limit of the power in a case that the value of n is equal to 1.

2. The OFDM transmission apparatus according to claim 1, wherein the limit of the power is modified by a modification value.

3. The OFDM transmission apparatus according to claim 1, wherein in a case that the value of n is equal to or greater than a value of 2, the sub-carrier allocation section is further configured to allocate each of two or more sets of spreading signals of said n sets of spread signals to the plurality of sub-carriers, respectively.

4. The OFDM transmission apparatus according to claim 1,

wherein the control section is configured to control the limit of the power so that the limit of the power for transmitting IDFT transformed said n sets of spread signals is a first limit based on the value of n being equal to or greater than a value of 2 and a second limit based on the value of n being equal to 1, and

wherein the first limit is a limit less than the second limit.

5. An OFDM transmission method comprising:

performing discrete Fourier transform on data signals to generate n sets of spread signals, n being a value equal to or greater than 1;

allocating said n sets of spread signals to a plurality of sub-carriers;

performing inverse discrete Fourier transform on said n sets of spread signals allocated;

controlling, according to the value of n, a limit of a power for transmitting IDFT transformed said n sets of spread signals, in order that the limit of the power in a case that the value of n is equal to or greater than a value of 2 to be smaller than the limit of the power in a case that the value of n is equal to 1.

6. A wireless communication system comprising:

a reception apparatus; and

an OFDM transmission apparatus,

wherein the OFDM transmission apparatus comprises;

a variable-spreading-factor spreading section configured to perform discrete Fourier transform on data signals to generate n sets of spread signals, n being a value equal to or greater than 1;

a sub-carrier allocation section configured to allocate said n sets of spread signals to a plurality of sub-carriers;

an inverse discrete Fourier transform section configured to perform inverse discrete Fourier transform on said n sets of spread signals allocated; and

a control section configured to control, according to the value of n, a limit of a power for transmitting IDFT transformed said n sets of spread signals, wherein

the control section is further configured to control the limit of the power in a case that the value of n is equal to or greater than a value of 2 to be smaller than the limit of the power in a case that the value of n is equal to 1, and

the reception apparatus comprises;

an RF unit configured to receive IDFT transformed said n sets of spread signals transmitted from the OFDM transmission apparatus.

7. A non-transitory computer-readable medium having instructions stored thereon, such that when the instructions are read and executed by processor, the processor is configured to:

perform a discrete Fourier transform on data signals to generate n sets of spread signals, n being a value equal to or greater than 1;

allocate said n sets of spread signals to a plurality of sub-carriers;

perform an inverse discrete Fourier transform on said n sets of spread signals allocated;

control, according to the value of n, a limit of a power for transmitting IDFT transformed said n sets of spread signals in order that the limit of the power in a case that the value of n is equal to or greater than a value of 2 to be smaller than the limit of the power in a case that the value of n is equal to 1.