Method and Apparatus for Transmitting by Using Transmit Diversity at Dft Spread Ofdma

• US 20080316913A1
• Filed: 11/17/2006
• Published: 12/25/2008
• Est. Priority Date: 11/17/2005
• Status: Active Grant

• Current Assignee: KT Corporation, SK Telecom Co., Ltd.
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Park, Hyeong-Geun, Bang, Seung-Chan, Kim, Young-Hoon, Chang, Kap-Seok, Kim, Il-Gyu, Lee, Moon-Sik, Jwa, Hye-Kyung, Shin, Eun-Jeong
• Granted Patent: US 8,369,300 B2
• Time in Patent Office: Days
• US Class Current: 370/210
• CPC Class Codes: H04B 7/061 using feedback from receiving side
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/1893 Physical mapping arrangements physical resource mapping in general H04L5/00
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0044 allocation of payload

Abstract

The present invention relates to a packet data transmission method in an OFDMA system and an apparatus thereof. The present invention provides a user packet data transmission method including generating a RACH burst for channel information estimation, selecting a first antenna among a plurality of antennas, transmitting the RACH burst through the first antenna to a base station, receiving a data transmission acceptance signal from the base station, in response to the RACH burst, transmitting user packet data through the first antenna when receiving a signal indicating that the data transmission is allowed, and selecting a second antenna that is difference from the first antenna and transmitting a RACH burst through the second antenna when receiving a signal indicating that the data transmission is not allowed, and a transmitting apparatus of a mobile station having the plurality of antennas. According to the present invention, the RACH burst and user packet data are transmitted by using a mobile station having a plurality of antennas in an LTE-applied OFDMA system, and therefore data transmission can be performed with a wide bandwidth and high data rate and a deep fading period that may occur during the data transmission can be reduced, thereby preventing call dropping and improving data transmission performance.

Claims

1. A packet data transmission method of a mobile station including a plurality of antennas, in an orthogonal frequency division multiplex access (OFDMA) system, the packet data transmission method comprising:

(a) generating a random access channel (RACH) burst for channel information estimation;

(b) selecting a first antenna among the plurality of antennas and transmitting the RACH burst to a base station through the first antenna;

(c) receiving a signal including information on whether the base station allows data transmission, in response to the RACH burst; and

(d) when receiving a signal indicating that the data transmission is allowed, transmitting user packet data through the first antenna,

wherein when receiving a signal indicating that the data transmission is not allowed, selecting a second antenna that is different from the first antenna and transmitting the RACH burst through the second antenna.

2. The packet data transmission method of claim 1, wherein the transmission of the RACH burst through the second antenna comprises:

receiving a signal indicating whether the base station allows the data transmission, in response to the RACH burst; and

when receiving a signal indicating that the data transmission is allowed, transmitting the user packet data through the second antenna, and when receiving a signal indicating that the data transmission is not allowed, selecting a third antenna or the first antenna and transmitting through the selected antenna, the selected antenna being different from the second antenna.

3. The packet data transmission method of claim 1, wherein the second antenna transmits the RACH burst by using a sub-band that is different from the sub-band used for transmitting the RACH burst by the first antenna.

4. The packet data transmission method of claim 1, wherein in (d), when the signal indicating that the data transmission is allowed is received, transmitting the user packet data by using the sub-band which was used for transmitting the last RACH burst.

5. The packet data transmission method of claim 1, wherein, before (b), the packet transmission method further comprises setting a mode of the mobile station to a RACH burst transmission mode for transmitting the RACH burst.

6. The packet data transmission method of claim 5, wherein, when the signal indicating that the data transmission is allowed is received, the RACH burst transmission mode is changed to a user packet data transmission mode.

7. A packet data transmission method of a mobile station having a plurality of antennas in an orthogonal frequency division multiplex access (OFDMA) system, the packet data transmission method comprising:

(a) generating a random access channel (RACH) burst to be transmitted to a base station for channel information estimation;

(b) transmitting the RACH burst to the base station by sequentially using the plurality of antennas;

(c) receiving a signal transmitted from the base station, the signal indicating whether data transmission is allowed, in response to the RACH burst; and

(d) when receiving a signal indicating that the data transmission is allowed, transmitting user packet data through the antenna used for transmitting the RACH burst.

8. The packet data transmission method of claim 7, wherein, in (d), the above-stated processes are repeated from step (b) when the signal indicating that the data transmission is allowed is not received.

9. A transmitting apparatus of a mobile station having a plurality of antennas in an orthogonal frequency division multiple access (OFDMA) system, the transmitting apparatus comprising:

a symbol-subcarrier mapper for mapping a random access channel (RACH) burst to a subcarrier;

an inverse fast Fourier transform (IFFT) unit for converting the RACH burst mapped to the subcarrier to time domain data; and

a switching block for selecting an antenna for transmitting the RACH burst output from the IFFT unit from the plurality of antennas.

10. The transmitting apparatus of claim 9, further comprising a plurality of radio frequency converters for converting and filtering the RACH burst output from the IFFT unit to a radio frequency signal, and respectively corresponding to the plurality of antennas,

wherein each of radio frequency converters is connected between the switching block and the corresponding antenna among the plurality of antennas.

11. The transmitting apparatus of claim 10, wherein the switching block transmits the RACH burst output from the IFFT unit and user packet data to be transmitted through the transmitting apparatus to a radio frequency converter connected to the selected antenna.

12. The transmitting apparatus of claim 11, wherein the RACH burst and the user packet data are transmitted through a frequency and spectrum of a baseband.

13. The transmitting apparatus of claim 9, further comprising a radio frequency converter, connected between the IFFT unit and the switching block, for converting and filtering the RACH burst output from the IFFT to a radio frequency signal.

14. The transmitting apparatus of claim 9, wherein the switching block sequentially selects the plurality of antennas for each transmission of the RACH burst.

15. The transmitting apparatus of claim 9, further comprising a fast Fourier transform spreader for performing fast Fourier transform spreading on the RACH burst and transmitting the spread RACH burst to the symbol-subcarrier mapper.

16. The transmitting apparatus of claim 15, wherein the fast Fourier transform spreader performs a fast Fourier transform operation when the number of symbols of the RACH burst corresponds to 2ⁿ, and performs a discrete Fourier transform operation when the number of symbols of the RACH burst does not correspond to 2ⁿ.

17. The transmitting apparatus of claim 9, further comprising:

a cyclic prefix (CP) adder for adding a CP to the RACH burst converted to the time domain data through the IFFT unit; and

a parallel-to-serial (P/S) converter for converting the CP-added RACH burst in a parallel form to a serial signal.

18. The transmitting apparatus of claim 9, wherein, user packet data is transmitted through an antenna through which the RACH burst is transmitted when the RACH burst is transmitted to the base station and a data transmission acceptance signal for the RACH burst is received from the base station.

19. A recording medium installed in a mobile station including a plurality of antennas for transmission of user packet data in an orthogonal frequency division multiplex access (OFDMA) system, a program being written in the recording medium,

wherein the program executes functions, including:

generating a random access channel burst (RACH) for channel information estimation;

selecting a first antenna among the plurality of antennas and transmitting the RACH burst through the first antenna to a base station;

receiving a signal indicating whether the base station allows data transmission of the base station, in response to the RACH burst; and

transmitting the user packet data through the first antenna when a signal indicating that the data transmission is allowed is received, and selecting a second antenna that is different from the first antenna and transmitting the RACH burst through the second antenna when a signal indicating that the data transmission is not allowed is received.