Frequency-division multiplexing transceive apparatus and method

• US 20070070968A1
• Filed: 12/29/2005
• Published: 03/29/2007
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kawasaki, Toshio
• Granted Patent: US 7,474,609 B2
• Time in Patent Office: Days
• US Class Current: 370/344
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 5/06 the signals being represented by different frequencies combined with time-division multiplexing H04L5/26

Abstract

In a frequency-division multiplexing transmitting apparatus for transmitting data at a frequency specific to a mobile station, a symbol compression and repetition unit compresses the time domain of each symbol of a transmit symbol sequence, repeats the symbol a prescribed number of times (L times) and rearranges the symbols of the obtained repetitive symbol sequence in such a manner that the symbols will have an arrangement identical with the arrangement of the transmit symbol sequence; a phase rotating unit applies phase rotation, which varies at a speed specific to the mobile station, to each symbol of the repetitive symbol sequence after the rearrangement thereof; and a transmitting unit transmits the-symbols that have undergone the phase rotation. The phase rotating unit varies the amount of phase rotation, which is applied to each symbol of the repetitive symbols, in increments of k·2π/L (where k represents an integer specific to the mobile station) at the period of the repetitive symbol sequence.

Claims

1. A frequency-division multiplexing transmitting apparatus for-sending and receiving data by a frequency spectrum specific to a mobile station, comprising:

symbol compression and repetition unit for compressing a time domain of each symbol of a transmit symbol sequence, repeating the symbol a prescribed number of times (L times) and rearranging the symbols of the obtained repetitive symbol sequence in such a manner that the symbols will have an arrangement identical with the arrangement of the transmit symbol sequence;

a phase rotating unit for subjecting each symbol of the repetitive symbol sequence after the rearrangement thereof to phase rotation that varies at a speed specific to the mobile station; and

a transmitting unit for transmitting the symbols that have undergone the phase rotation;

wherein said phase rotating unit varies the amount of phase rotation, which is applied to each symbol of the repetitive symbols, in increments of k·

2π

/L (where k represents an integer specific to the mobile station) at the period of the repetitive symbol sequence.

2. The apparatus according to claim 1, wherein said phase rotating unit adopts Tc×

Q as the period of the repetitive symbol sequence, where Q represents the number of symbols transmitted in one frame and Tc represents the symbol repetition period.

3. The apparatus according to claim 1, wherein said phase rotating unit includes:

a rotation phase generator for generating phase that increases in increments of k·

2π

/L at the period of the repetitive symbol sequence; and

a complex multiplier for subjecting each symbol of the repetitive symbol sequence to phase rotation that conforms to the phase generated.

4. A frequency-division multiplexing receiving apparatus according to claim 1, comprising:

a receiving unit for receiving each symbol of a repetitive symbol sequence that has been transmitted from said transmitting apparatus;

a phase rotating unit for subjecting, on a per-mobile-station basis, the receive symbols to phase rotation that varies in increments of k·

2π

/L at the period of the repetitive symbol sequence; and

a demodulator for demodulating transmit symbols by combining identical symbol components that are output from said phase rotating unit at the period of the repetitive symbol sequence.

5. A frequency-division multiplexing transmitting apparatus for transmitting data by a frequency spectrum specific to a mobile station, comprising:

a spreading unit for multiplying transmit symbols by spreading codes to thereby generate a chip sequence;

a chip compression and repetition unit for compressing a time domain of each chip of the chip sequence, repeating the chip a prescribed number (=CRF) of times and rearranging the chips of the repetitive chip sequence in such a manner that the chips will have an arrangement identical with the original chip arrangement;

a phase rotating unit for subjecting each chip of the repetitive chip sequence after the rearrangement thereof to phase rotation that varies at a speed specific to the mobile station; and

a transmitting unit for transmitting the output of said phase rotating unit;

wherein said phase rotating unit varies the amount of phase rotation, which is applied to each chip of the repetitive chip sequence, in increments of k·

2π

/CRF (where k represents an integer specific to the mobile station) at the period of the repetitive chip sequence.

6. The apparatus according to claim 5, wherein said phase rotating unit calculates the period of the repetitive chip sequence according to Tc×

SF×

Q, where Q represents the number of symbols transmitted in one frame, SF the spreading factor and Tc the chip repetition period.

7. The apparatus according to claim 5, wherein said phase rotating unit includes:

a rotation phase generator for generating phase that increases in increments of k·

2π

/CRF at the period of the repetitive chip sequence; and

a complex multiplier for subjecting each chip of the repetitive chip sequence to phase rotation that conforms to the phase generated.

8. A frequency-division multiplexing receiving apparatus according to claim 5, comprising:

a receiving unit for receiving each chip of a repetitive chip sequence that has been transmitted from said transmitting apparatus;

a phase rotating unit for subjecting, on a per-mobile-station basis, the receive chips to phase rotation that varies in increments of k·

2π

/CRF at the period of the repetitive chip sequence;

a despreading unit for compressing time domains of despreading codes, thereby repeatedly generating the despreading codes the prescribed number (=CRF) of times, and applying the repeatedly generated despreading codes to the output of said phase rotating unit; and

a demodulator for demodulating transmit symbols by combining identical symbol components that have been obtained by the despreading.

9. A frequency-division multiplexing transmitting apparatus for transmitting data by a frequency spectrum specific to a mobile station, comprising:

a phase rotating unit for subjecting transmit symbols to phase rotation that varies at a speed specific to the mobile station;

a spreading unit for compressing time domains of spreading codes, thereby repeatedly generating the spreading codes a prescribed number (=CRF) of times, and multiplying the output of said phase rotating unit by the repeatedly generated spreading codes; and

a transmitting unit for transmitting the results of multiplication by the spreading codes;

wherein said phase rotating unit varies the amount of phase rotation, which is applied to the transmit symbols, in increments of k·

2π

/CRF (where k represents an integer specific to the mobile station) at the period of the repetitive spreading code sequence.

10. The apparatus according to claim 9, wherein said phase rotating unit includes:

a rotation phase generator for generating phase that increases in increments of k·

2π

/CRF at the period of the repetitive spreading code sequence; and

a complex multiplier for subjecting the transmit symbols to phase rotation that conforms to the phase generated.

11. A frequency-division multiplexing receiving apparatus according to claim 9, comprising:

a receiving unit for receiving the signal that has been transmitted from said transmitting apparatus;

a despreading unit for compressing time domains of despreading codes, thereby repeatedly generating the despreading codes the prescribed number (=CRF) of times, and multiplying the receive signal by the repetitive despreading codes;

a phase rotating unit for subjecting, on a per-mobile-station basis, the output of said despreading unit to phase rotation that varies in increments of k·

2π

/CRF at the period of the repetitive spreading code sequence; and

a demodulator for demodulating transmit symbols by combining identical symbol components from among the outputs of said phase rotating unit.

12. A frequency-division multiplexing transmitting method for transmitting data by a frequency spectrum specific to a mobile station, comprising:

a symbol repeating/rearranging step of compressing a time domain of each symbol of a transmit symbol sequence, repeating the symbol a prescribed number of times (L times) and rearranging the symbols of the obtained repetitive symbol sequence in such a manner that the symbols will have an arrangement identical with the arrangement of the transmit symbol sequence;

a phase rotating step of subjecting each symbol of the repetitive symbol sequence after the rearrangement thereof to phase rotation that varies at a speed specific to the mobile station; and

a transmitting step of transmitting the symbols that have undergone the phase rotation;

wherein the amount of phase rotation, which is applied to each symbol of the repetitive symbols, is varied at said phase rotating step in increments of k·

2π

/L (where k represents an integer specific to the mobile station) at the period of the repetitive symbol sequence.

13. The method according to claim 12, wherein said phase rotating step includes the steps of:

generating phase that increases in increments of k·

2π

/L at the period of the repetitive symbol sequence; and

subjecting each symbol of the repetitive symbol sequence to phase rotation that conforms to the phase generated.

14. A frequency-division multiplexing receiving method according to claim 12, comprising:

a receiving step of receiving each symbol of a repetitive symbol sequence that has been transmitted by said transmitting method;

a phase rotating step of subjecting, on a per-mobile-station basis, the receive symbols to phase rotation that varies in increments of k·

2π

/L at the period of the repetitive symbol sequence; and

a demodulating step of demodulating transmit symbols by combining identical symbol components that have undergone phase rotation at the period of the repetitive symbol sequence.