Multi-Carrier Cdma Transmitting Device and Method Using Block-Based Multi-Carrier Spreading

• US 20080298335A1
• Filed: 07/22/2005
• Published: 12/04/2008
• Est. Priority Date: 07/22/2004
• Status: Active Grant

• Current Assignee: Industry Academic Cooperation Foundation of Kyunghee University
• Original Assignee: Industry Academic Cooperation Foundation of Kyunghee University
• Inventors: Lee, Kye-San
• Granted Patent: US 8,385,296 B2
• Time in Patent Office: Days
• US Class Current: 370/342
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04J 11/005 of intercell interference
• CPC Class Codes: H04L 5/026 using code division

Abstract

A multi-carrier CDMA transfer device using block-based partial-carrier spreading uses block-based partial-carrier spreading in the multi-cell environment to be applied to MC-CDMA models (FH-MC/CDMA TDD) that are strong against multi-path fading. A transmitter of the transfer device spreads carriers per block in the frequency domain by using the block-based partial-carrier spreading, and a receiver despreads received signals by using the block-based partial-carrier and restore original data. Optionally, an array antenna having a plurality of antenna elements is applied to the transmitter and the receiver, and weights are adaptively applied depending on the channel quality when transmitting and receiving signals through the antenna elements. Therefore, frequency diversity is obtainable and inter-cell interference and inter-code interference is optimized in the MC-CDMA method. Also, changes of frequency hopping reduce temporal variations of channels and prevent a high SN ratio.

Claims

1. A transmitting device for the multi-carrier CDMA scheme, comprising:

a serial to parallel converter for converting input data into parallel data;

a plurality of copiers for copying each of the parallel data as many times as the number of spread factors;

a spreader for spreading the respective data output by the plurality of copiers with respect to the frequency axis using different spread codes, the spreader spreading a part of blocks composed of multi-carriers for multiplexing users; and

an IFFT unit for performing inverse fast Fourier transform (IFFT) on the data spread by the spreader and transmitting the IFFT-performed data through a transmit antenna.

2. The transmitting device of claim 1, further comprising:

an encoder/interleaver for encoding the input data, interleaving the encoded data, and outputting interleaved data;

a mapper for converting the data output by the encoder/interleaver into signals of a predetermined modulation method, and outputting the signals; and

a pilot inserter for multiplexing and inserting a pilot into the data output by the mapper, and outputting the data to the serial to parallel converter.

3. The transmitting device of claim 1, further comprising:

a parallel to serial converter for converting the parallel data output by the IFFT unit into serial data, and outputting the serial data; and

a guard interval inserter for inserting a guard interval into the data output by the parallel to serial converter, and outputting the executed data to the transmit antenna.

12. The transmitting device of claim 1, wherein the spreader spreads the data input for spreading by using carriers with less correlation in the frequency domain.

13. The transmitting device of claim 1, wherein the transmitting device is one of an orthogonal variable spreading factor (OVSF) system for varying a code spread factor and a Walsh code system, and transmitting the same depending on a multi-cell environment.

14. The transmitting device of claim 1, wherein the transmitting device is an adaptive modulation system for adaptively varying the modulation method and transmitting the same depending on the channel quality.

4. A receiving device for the multi-carrier CDMA, comprising:

an FFT unit for performing fast Fourier transform (FFT) on signals received through a receive antenna, and outputting data;

a despreader for despreading the data output by the FFT with different spread codes, the different spread codes being codes used when spreading a part of blocks composed of multi-carriers for multiplexing users;

a plurality of combiners for dividing the data despread by the despreader into a predetermined number of blocks, combining data of the respective blocks, and outputting the combined data; and

a parallel to serial converter for converting the data output by the plurality of combiners into serial data, and outputting the serial data.

5. The receiving device of claim 4, further comprising:

a guard interval eliminator for eliminating a guard interval from a signal received through the receive antenna, and outputting data; and

a serial to parallel converter for converting the output data into parallel data, and outputting the parallel data to the FFT unit.

6. The receiving device of claim 4, further comprising:

a channel estimator for using the data despread by the despreader to estimate a channel, and outputting an estimate to the combiner; and

a decoder/de-interleaver for decoding and de-interleaving the data output by the parallel to serial converter to output restored data.

15. The receiving device of claim 4, wherein the despreader despreads the FFT-performed data by using carriers with less correlation in the frequency domain.

16. The receiving device of claim 4, wherein the receiving device uses the same code while moving to another cell, thereby enabling a soft handoff.

17. The receiving device of claim 4, wherein the combiners use an equalizer to reduce inter-code interference, by using the equal gain combining (EGC) method, the minimum mean-square error (MMSE) method, and the maximal likelihood detection (MLD) method.

7. A transmitting device for the multi-carrier CDMA, comprising:

an array antenna having a plurality of antenna elements;

a spreader for copying the data output by the array antenna as many times as a predetermined number of blocks, and spreading the data with different spread codes according to the copied data blocks, the spreader spreading a part of the copied data blocks composed of multi-carriers for multiplexing users;

N adaptive transmission controllers for applying weights to the respective data spread by the spreader, performing IFFT on the weighted data, and outputting the executed data to a corresponding antenna element of the antenna elements wherein N corresponds to the number of the antenna elements of the array antenna; and

a weight controller for controlling the weights of the adaptive transmission controllers according to a channel quality.

8. The transmitting device of claim 7, wherein the adaptive transmission controllers comprises:

a plurality of multipliers for multiplying the data output by the spreader by a weight controlled by the weight controller; and

an IFFT unit for performing IFFT on the data output by the multipliers, and outputting IFFT-performed data to the antenna elements.

9. The transmitting device of claim 8, wherein the weight controller uses the same weight as the weight to which the channel quality measured by the receiving device is reflected, and controls the adaptive transmission controllers.

24. The transmitting device of claim 7, wherein the spreader spreads the data input for spreading by using carriers with less correlation in the frequency domain.

25. The transmitting device of claim 7, wherein the transmitting device is one of an orthogonal variable spreading factor (OVSF) system for varying a code spread factor and a Walsh code system, and transmitting the same depending on a multi-cell environment.

26. The transmitting device of claim 7, wherein the transmitting device is an adaptive modulation system for adaptively varying the modulation method and transmitting the same depending on the channel quality.

10. A receiving device for the multi-carrier CDMA, comprising:

an array antenna having a plurality of antenna elements;

N adaptive receiving controllers for performing FFT on the signals output by the array antenna, applying corresponding weights to the executed signals, and outputting weighted signals wherein N corresponds to the number of antenna elements of the array antenna;

a weight controller for controlling the weight of the adaptive receiving controllers according to a channel quality;

a despreader for despreading the data output by the adaptive receiving controller with different spread codes, the different spread codes being codes used when spreading a part of blocks composed of multi-carriers for multiplexing users; and

a plurality of combiners for dividing the data despread by the despreader into a predetermined number of blocks, combining the data of the respective divided blocks, and outputting data.

11. The receiving device of claim 10, wherein the adaptive receiving controllers comprises:

an FFT unit for performing fast Fourier transform (FFT) on the data output by the array antennas; and

a plurality of multipliers for multiplying the data output by the FFT unit by a weight controlled by the weight controller, and outputting weighted data to the despreader.

27. The receiving device of claim 10, wherein the despreader despreads the FFT-performed data by using carriers with less correlation in the frequency domain.

28. The receiving device of claim 10, wherein the receiving device uses the same code while moving to another cell, thereby enabling a soft handoff.

29. The receiving device of claim 10, wherein the combiners use an equalizer to reduce inter-code interference, by using the equal gain combining (EGC) method, the minimum mean-square error (MMSE) method, and the maximal likelihood detection (MLD) method.

18. A transfer device comprising:

an array antenna having a plurality of antenna elements;

a transmitter for applying a weight to the respective transmission data and transmitting the weighted transmission data through the array antenna according to the multi-carrier CDMA method based on block-based partial-carrier spreading, the weight allowing adaptive control; and

a receiver for receiving the data through the array antenna and respectively applying a weight to the received data according to the multi-carrier CDMA method based on the block-based partial-carrier spreading, the weight allowing adaptive control.

19. The transfer device of claim 18, wherein the weights determined to be applicable to the receiver are used for the weights applicable to the transmitter.

20. The transfer device of claim 18, wherein the transmitter comprises:

a spreader for copying transmission data as many times as a predetermined number of blocks, and spreading the copied data with different spread codes according to the copied data blocks, the spreader spreading a part of the copied data blocks composed of multi-carriers for multiplexing users;

N adaptive transmission controllers for applying weights to the respective data spread by the spreader, performing IFFT on the weighted data, and outputting the executed data to a corresponding antenna element of the antenna elements wherein N corresponds to the number of antenna elements of the array antenna; and

a weight controller for controlling the weights of the adaptive transmission controllers.

21. The transfer device of claim 18, wherein the receiver comprises:

N adaptive receiving controllers for performing FFT on the signals output by the array antenna, applying corresponding weights to the executed signals, and outputting weighted signals, wherein N corresponds to the number of antenna elements of the array antenna;

a received weight controller for controlling the weight of the adaptive receiving controllers according to a channel quality.

a despreader for despreading the data output by the adaptive receiving controller with different spread codes, the different spread codes being codes used when spreading a part of blocks composed of multi-carriers for multiplexing users; and

a plurality of combiners for dividing the data despread by the despreader into a predetermined number of blocks, combining the data of the respective blocks, and outputting data.

30. The transfer device of claim 19, wherein the transmitter comprises:

a spreader for copying transmission data as many times as a predetermined number of blocks, and spreading the copied data with different spread codes according to the copied data blocks, the spreader spreading a part of the copied data blocks composed of multi-carriers for multiplexing users;

N adaptive transmission controllers for applying weights to the respective data spread by the spreader, performing IFFT on the weighted data, and outputting the executed data to a corresponding antenna element of the antenna elements wherein N corresponds to the number of antenna elements of the array antenna; and

a weight controller for controlling the weights of the adaptive transmission controllers.

31. The transfer device of claim 19, wherein the receiver comprises:

N adaptive receiving controllers for performing FFT on the signals output by the array antenna, applying corresponding weights to the executed signals, and outputting weighted signals, wherein N corresponds to the number of antenna elements of the array antenna;

a received weight controller for controlling the weight of the adaptive receiving controllers according to a channel quality.

a despreader for despreading the data output by the adaptive receiving controller with different spread codes, the different spread codes being codes used when spreading a part of blocks composed of multi-carriers for multiplexing users; and

a plurality of combiners for dividing the data despread by the despreader into a predetermined number of blocks, combining the data of the respective blocks, and outputting data.

22. A transmission method for the multi-carrier CDMA, comprising:

(a) converting input data into parallel data;

(b) copying the converted parallel data as many times as a predetermined number of blocks, and spreading the data with different spread codes according to the copied data blocks, the spreading being performed for a part of the copied data blocks composed of multi-carriers for multiplexing users; and

(c) performing IFFT on the spread data and transmitting the executed data through a transmit antenna.

23. A receiving method for a multi-carrier CDMA, comprising:

(a) performing FFT on a signal received through a receive antenna, and outputting FFT-performed data;

(b) despreading the FFT-performed data with different spread codes, dividing the despread data into a predetermined number of blocks, combining the data, and outputting combined data, the different spread codes being codes used when spreading a part of blocks composed of multi-carriers for multiplexing users; and

(c) converting the combined and output data into serial data, and outputting the serial data.