Transmitter and transmitting method in multiple transmitting antenna communication system

• US 20070082625A1
• Filed: 10/02/2006
• Published: 04/12/2007
• Est. Priority Date: 10/08/2005
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Yang, Jang-Hoon, Hwang, In-Seok, Yoon, Soon-Young, Jeong, Joong-Ho
• Application Number:
  US11/540,581
• Publication Number:
  US 20070082625A1
• Time in Patent Office: Days
• US Class Current: 455/101
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0671 using different delays between antennas

Abstract

A transmitter and a transmitting method for forming a pseudo common beam using a plurality of antennas in a smart antenna communication system are provided, in which beams for tones of Orthogonal Frequency Division Multiplexing (OFDM) signals transmitted through a plurality of antennas are rotated at different phases around a frequency axis, such that a combined beam of the transmitted beams is equivalent to a pseudo common beam. Accordingly, a peak to average power ratio (PAPR) of the preamble signal is prevented from changing.

Claims

1. A transmitter of a multiple transmitting antenna communication system, comprising a beam factor generator for generating beam factors for tones of a transmit (TX) signal such that beams rotate at different phases around a frequency axis, wherein the phase-rotated beams are transmitted through a plurality of antennas.

2. The transmitter of claim 1, wherein the phase rotation comprises a linear phase rotation.

3. The transmitter of claim 2, wherein the linear phase rotation comprises assigning different cyclic delay offsets (τ

), in time domain, to the beams transmitted to respective antennas.

4. An Orthogonal Frequency Division Multiple Access (OFDMA) system comprising the transmitter as claimed in claim 1.

5. A transmitter of a multiple transmitting antenna communication system, comprising:

a channel encoder for encoding a transmit (TX) signal;

a beam factor generator for generating beam factors for tones of the encoded transmit signal such that beams rotate at different phases around a frequency axis; and

a plurality of antennas for transmitting the differently phase-rotated beams comprising the beam factors, such that a synthesized beam of the respective beams becomes a pseudo common beam.

6. The transmitter of claim 5, wherein the phase rotation comprises a linear phase rotation.

7. The transmitter of claim 6, wherein the linear phase rotation comprises assigning different cyclic delay offsets (τ

), in time domain, to the beams transmitted to respective antennas.

8. An Orthogonal Frequency Division Multiple Access (OFDMA) system comprising the transmitter as claimed in claim 5.

9. The transmitter of claim 5, wherein the synthesized beam is expressed as:

$S<br><br>\left(f_k;<br><br>\mathrm{\theta <br><br>}\right)=A<br><br>\left(\mathrm{\theta <br><br>}\right)+\underset{m=1}{\overset{3}{\sum <br><br>}}<br><br>A<br><br>\left(\mathrm{\theta <br><br>}\right)<br><br>{\mathrm{e<br><br>}}^{j<br><br>\text{\hspace{1em}<br><br>}<br><br>m<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\pi <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\sin <br><br>\left(\mathrm{\theta <br><br>}\right)}·<br><br>{\mathrm{e<br><br>}}^{j<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\phi <br><br>}}_m<br><br>\left(f_k\right)},{\mathrm{\phi <br><br>}}_m<br><br>\left(f_k\right)={\mathrm{\phi <br><br>}}_{m,0}-2<br><br>\mathrm{\pi <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>f_k<br><br>{\mathrm{\tau <br><br>}}_m/N_{\mathrm{FFT}}$

where S(f_k;

θ

) is a beam pattern of an f_k-th sub-carrier synthesized by the phase w_m,k, f_k is a sub-carrier index, m is an antenna index, θ

is signal transmitting direction from the base station, d is an interval of the antennas, A(θ

) is an antenna element characteristic value, φ

_m(f_k)=φ

_m,0−

2π

f_kτ

_m/N_FFT is an antenna phase shift value when the antenna is installed, and N_FFT represents a magnitude of FFT.

10. A transmitting method of a multiple transmitting antenna communication system, the method comprising:

generating beam factors for rotating tones of a transmit (TX) signal at different phases around a frequency axis; and

transmitting the beams for each tone, to which the beam factors are applied, through a plurality of antennas.

11. The transmitting method of claim 10, wherein the phase rotation comprises a linear phase rotation.

12. The transmitting method of claim 11, wherein the linear phase rotation comprises assigning different cyclic delay offsets (τ

), in time domain, to the beams transmitted to respective antennas.

13. A transmitting method in an Orthogonal Frequency Division Multiple Access (OFDMA) system, the method comprising steps of claim 10.

23. The transmitting method of claim 11, wherein the linear phase rotation comprises assigning different cycle delay offsets (τ

), in time domain, to the beams transmitted to respective antennas.

14. A transmitting method of a multiple transmitting antenna communication system, the method comprising:

channel-encoding a transmit (TX) signal;

generating beam factors for rotating tones of the encoded transmit (TX) signal at different phases around a frequency axis;

transmitting the differently phase-rotated beams comprising the beam factors through a plurality of antennas; and

combining the transmitted beams into a pseudo common beam.

15. The transmitting method of claim 14, wherein the phase rotation comprises a linear phase rotation.

16. The transmitting method of claim 15, wherein the linear phase rotation comprises assigning different cyclic delay offsets (τ

), in time domain, to the beams transmitted to respective antennas.

17. A transmitting method in an Orthogonal Frequency Division Multiple Access (OFDMA) system, the method comprising steps of claim 14.

26. The transmitting method of claim 15, wherein the linear phase rotation comprises assigning different cyclic delay offsets (τ

), in time domain, to the beams transmitted to respective antennas.

18. A transmitting method of a multiple antenna communication system, the method comprising:

determining if a transmit (TX) signal period is a common beam period;

if the TX signal period is the common beam period, applying a beam factor of w_m,k=e<sup>−

j2π

fkτ

/NFFT</sup> for each tone of the TX signal, where f_k is a sub-carrier index, m is an antenna index, τ

_m is a cyclic delay offset of a m-th antenna in time axis, and N_FFT represents a magnitude of FFT; and

transmitting the tones, to which the beam factors are applied, through a plurality of antennas, such that a combined beam of the beams for each tone becomes a pseudo common beam.

19. The transmitting method of claim 18, further comprising forming an adaptive beam using a corresponding antenna channel matrix according to a receiver, when the TX signal period is not the common beam period.

20. The transmitting method of claim 18, wherein the transmitting comprises an Orthogonal Frequency Division Multiple Access (OFDMA) system.

21. A computer-readable recording medium storing computer program code for a transmitting method of a multiple transmitting antenna communications system where beans for tones, to which beam factors are applied, are transmitted through a plurality of antennas, the code comprising executable instructions for generating beam factors for rotating tones of a transmit (TX) signal at different phases around a frequency axis.

22. The transmitting method of claim 21, wherein the phase rotation comprises a linear phase rotation.

24. A computer-readable recording medium storing computer program code for a transmitting method of a multiple transmitting antenna communications system where beans for tones, to which beam factors are applied, are transmitted through a plurality of antennas, the code comprising executable instructions for:

channel-encoding a transmit (TX) signal;

generating beam factors for rotating tones of the encoded transmit (TX) signal at different phases around a frequency axis; and

combining the transmitted beams into a pseudo common beam.

25. The transmitting method of claim 24, wherein the phase rotation comprises a linear phase rotation.