Transmit antenna diversity apparatus and method for a base station in a CDMA mobile communication system

• US 20020115473A1
• Filed: 12/21/2001
• Published: 08/22/2002
• Est. Priority Date: 12/21/2000
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Sung Jin, Lee, Ju Ho, Lee, Yong Suk, Hwang, Jong Yoon
• Granted Patent: US 6,798,847 B2
• Time in Patent Office: Days
• US Class Current: 455/562.1
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04J 13/004 Orthogonal

Abstract

Disclosed is a base station transmission apparatus in a mobile communication system using transmit antenna diversity between a base station with a plurality of antennas and a mobile station. A modulator generates a complex symbol in response to a coded symbol. A first spreader generates a plurality of different complex symbols in response to the complex symbol, and generates a plurality of first spread complex symbols by spreading the generated complex symbols with a first orthogonal code assigned to the mobile station. A second spreader generates a plurality of same complex symbols in response to the complex symbol from the modulator, spreads the same complex symbols with a second orthogonal code, and generates a plurality of second spread complex symbols by multiplying the spread complex symbols by weights for the antennas, determined based on feedback information indicating reception status of a base station signal. A summer sums up the first complex symbols and the second complex symbols. Finally, a transmitter complex-spreads an output of the summer, shifts the complex-spread signals to a radio frequency band, and transmits the shifted signals through the antennas.

Claims

1. A base station transmission apparatus in a mobile communication system using transmit antenna diversity between a base station with a plurality of antennas and a mobile station, comprising:

a modulator for generating a complex symbol in response to a coded symbol;

a first spreader for generating a plurality of different complex symbols in response to the complex symbol from the modulator, and generating a plurality of first orthogonal spreading symbols by spreading the plurality of the generated complex symbols with a first orthogonal code assigned to the mobile station;

a second spreader for generating a plurality of same complex symbols in response to the complex symbol from the modulator, spreading the plurality of same complex symbols with a second orthogonal code, which is assigned to the mobile station, being different from the first orthogonal code and generating a plurality of second orthogonal spreading symbols, by multiplying the orthogonal spreading symbols by weights for the antennas, determined based on feedback information, received from the mobile station, indicating reception status of a base station signal;

a plurality of summers for summing up the first orthogonal spreading symbols from the first spreader and the second orthogonal spreading symbols from the second spreader; and

a transmitter for, shifting the orthogonal spreading symbols to a radio frequency band, and transmitting the shifted symbols through the antennas.

2. The base station transmission apparatus as claimed in claim 1, wherein the first spreader comprises;

a diversity modulator for generating the plurality of different complex symbols in response to the complex symbol from the modulator; and

a plurality of Walsh cover parts for generating the plurality of the first orthogonal spreading symbols by spreading the plurality of different complex symbols from the diversity modulator with the first orthogonal code.

3. The base station transmission apparatus as claimed in claim 2, wherein the diversity modulator is one of an STTD (Space-Time Transmit Diversity) modulator and an STS (Space Time Spreader) modulator.

4. The base station transmission apparatus as claimed in claim 1, wherein the second spreader comprises:

a plurality of Walsh cover parts for generating the plurality of the orthogonal spreading symbols by spreading the plurality of complex symbols from the modulator with the second orthogonal code; and

a complex multiplier for generating the plurality of the second orthogonal spreading symbols by multiplying the plurality of the orthogonal spreading symbols from the Walsh cover parts by the associated weights.

5. The base station transmission apparatus as claimed in claim 1, wherein the feedback information indicates a reception phase of a base station signal at the mobile station.

6. A base station transmission apparatus in a mobile communication system using transmit antenna diversity between a base station with a plurality of antennas and a mobile station, comprising:

a modulator for generating a complex symbol in response to a coded symbol;

a serial-to-parallel converter for outputting two complex symbols with a reduced symbol rate by demultiplexing the complex symbol from the modulator;

a first spreader for generating a plurality of different complex symbols in response to one complex symbol from the serial-to-parallel converter, and generating a plurality of first sub-orthogonal spreading symbols by spreading the plurality of complex symbols with a first sub-orthogonal code created from one orthogonal code assigned to the mobile station;

a second spreader for generating a plurality of same complex symbols in response to another complex symbol from the serial-to-parallel converter, spreading the plurality of same complex symbols with a second sub-orthogonal code being different from the first sub-orthogonal code, and generating a plurality of second sub-orthogonal spreading symbols by multiplying the sub-orthogonal spreading symbols by weights for the antennas, determined based on feedback information, received from the mobile station, indicating reception status of a base station signal;

a plurality of summers for summing up the first sub-orthogonal spreading symbols from the first spreader and the second sub-orthogonal spreading symbols from the second spreader; and

a transmitter for shifting the summed sub-orthogonal spreading symbols to a radio frequency band, and transmitting the shifted symbols through the antennas.

7. The base station transmission apparatus as claimed in claim 6, wherein the first spreader comprises;

a diversity modulator for generating the plurality of different complex symbols in response to said one complex symbol from the serial-to-parallel converter; and

a plurality of Walsh cover parts for generating the plurality of first sub-orthogonal spreading symbols by spreading the plurality of the complex symbols from the diversity modulator with the first sub-orthogonal code.

8. The base station transmission apparatus as claimed in claim 7, wherein the diversity modulator is one of an STTD (Space-Time Transmit Diversity) modulator and an STS (Space Time Spreader) modulator.

9. The base station transmission apparatus as claimed in claim 6, wherein the second spreader comprises:

a plurality of Walsh cover parts for generating orthogonal spreading symbols by spreading said another complex symbol from the serial-to-parallel converter with the second sub-orthogonal code; and

a complex multiplier for generating the plurality of second sub- orthogonal spreading symbols by multiplying the plurality of the orthogonal spreading symbols from the Walsh cover parts by the associated weight.

10. A base station transmission apparatus in a mobile communication system using transmit antenna diversity between a base station with a plurality of antennas and a mobile station, comprising:

a modulator for generating a complex symbol in response to a coded symbol;

a diversity modulator for generating a plurality of different complex symbols in response to the complex symbol from the modulator;

a plurality of Walsh cover parts for generating a plurality of orthogonal spreading symbols by spreading the plurality of complex symbols with an orthogonal code assigned to the mobile station; and

a plurality of transmitters, a number of the transmitters being equal to a number of the orthogonal spreading symbols output from the Walsh cover parts, for generating a plurality of weighted orthogonal spreading symbols by multiplying one complex symbol from the Walsh cover part by weights for the antennas, determined based on feedback information, received from the mobile station, indicating reception status of a base station signal, shifting the weighted orthogonal spreading symbols to a radio frequency band, and transmitting the shifted symbols through the antennas associated with the weights.

11. The base station transmission apparatus as claimed in claim 10, wherein the diversity modulator is one of an STTD (Space-Time Transmit Diversity) modulator and an STS (Space Time Spreader) modulator.

12. The base station transmission apparatus as claimed in claim 10, wherein the transmitter comprises:

a plurality of complex multipliers for generating a plurality of weighted orthogonal spreading symbols by multiplying said one orthogonal spreading symbol from the Walsh cover part by the weights; and

an RF (Radio Frequency) part for shifting the weighted orthogonal spreading symbols to a radio frequency band, and transmitting the shifted symbols through the antennas.

14. The base station transmission apparatus as claimed in claim 13, wherein the diversity modulator is one of an STTD (Space-Time Transmit Diversity) modulator and an STS (Space Time Spreader) modulator.

15. The base station transmission apparatus as claimed in claim 13, wherein the feedback information indicates a reception phase of a base station signal at the mobile station.

13. A base station transmission apparatus in a mobile communication system using transmit antenna diversity between a base station with a plurality of antennas and a mobile station, comprising:

a modulator for generating a complex symbol in response to a coded symbol;

a diversity modulator for generating a plurality of different complex symbols in response to the complex symbol from the modulator;

a plurality of Walsh cover parts for generating a plurality of orthogonal spreading symbols by spreading the plurality of complex symbols from the diversity modulator with an orthogonal code assigned to the mobile station;

a switch for sequentially selecting the plurality of orthogonal spreading symbols from the spreader in a given period;

a complex multiplier for generating a plurality of weighted orthogonal spreading symbols by multiplying the orthogonal spreading symbol output from the switch by weights for the antennas, determined based on feedback information, received from the mobile station, indicating reception status of a base station signal; and

a RF part for shifting the weighted orthogonal spreading symbols to a radio frequency band, and transmitting the shifted symbols through the antennas.

16. A base station transmission method in a mobile communication system using transmit antenna diversity between a base station with a plurality of antennas and a mobile station, comprising the steps of:

determining weights for the plurality of antennas based on feedback information, received from the mobile station, indicating reception status of a base station signal;

generating a complex symbol in response to a coded symbol;

generating a plurality of different complex symbols in response to the complex symbol, and generating a plurality of first orthogonal spreading symbols by spreading the plurality of generated complex symbols with a first orthogonal code assigned to the mobile station;

generating a plurality of same complex symbols in response to the complex symbol, spreading the plurality of same complex symbols with a second orthogonal code being different from the first orthogonal code, and generating a plurality of second orthogonal spreading symbols by multiplying orthogonal spreading symbols by the determined weights;

summing up the first orthogonal spreading symbols and the second orthogonal spreading symbols; and

shifting the summed orthogonal spreading symbols to a radio frequency band, and transmitting the shifted symbols through the antennas.

17. A base station transmission method in a mobile communication system using transmit antenna diversity between a base station with a plurality of antennas and a mobile station, comprising the steps of:

determining weights for the plurality of antennas based on feedback information, received from the mobile station, indicating reception status of a base station signal;

generating a complex symbol in response to a coded symbol;

generating two complex symbols with a symbol rate reduced by demultiplexing the complex symbol;

generating a plurality of different complex symbols in response to one complex symbol out of the two complex symbols, and generating a plurality of first sub-orthogonal spreading symbols by spreading the plurality of different complex symbols with a first sub-orthogonal code created from one orthogonal code assigned to the mobile station;

generating a plurality of same complex symbols in response to another complex symbol out of the two complex symbols, spreading the plurality of same complex symbols with a second sub-orthogonal code being different from the first sub-orthogonal code, and generating a plurality of second sub-orthogonal spreading symbols by multiplying orthogonal spreading symbols by the determined weights;

summing up the first sub-orthogonal spreading symbols and the second sub-orthogonal spreading symbols; and

shifting the summed sub-orthogonal spreading symbols to a radio frequency band, and transmitting the shifted symbols through the antennas.

18. A base station transmission method in a mobile communication system using transmit antenna diversity between a base station with a plurality of antennas and a mobile station, comprising the steps of:

determining weights for the plurality of antennas based on feedback information, received from the mobile station, indicating reception status of a base station signal;

generating a complex symbol in response to a coded symbol;

generating a plurality of two different complex symbols in response to the complex symbol;

generating first and second orthogonal spreading symbols by spreading the two different complex symbols with an orthogonal code assigned to the mobile station;

generating a plurality of weighted orthogonal spreading symbols by multiplying the first orthogonal spreading symbol by first weights out of the determined weights, shifting the weighted orthogonal spreading symbols to a radio frequency band, and transmitting the shifted symbols through the antennas associated with the first weights; and

generating a plurality of weighted orthogonal spreading symbols by multiplying the second orthogonal spreading symbol by second weights out of the determined weights, shifting the weighted orthogonal spreading symbols to a radio frequency band, and transmitting the shifted symbols through the antennas associated with the second weights.

19. A base station transmission method in a mobile communication system using transmit antenna diversity between a base station with a plurality of antennas and a mobile station, comprising the steps of:

determining weights for the plurality of antennas based on feedback information, received from the mobile station, indicating reception status of a base station signal;

generating a complex symbol in response to a coded symbol;

generating a plurality of different complex symbols in response to the complex symbol;

generating a plurality of orthogonal spreading symbols by spreading the plurality of complex symbols with an orthogonal code assigned to the mobile station;

alternately selecting the plurality of orthogonal spreading symbols in a given period;

generating a plurality of weighted orthogonal spreading symbols by multiplying the selected orthogonal spreading symbol by the determined weights; and

shifting the weighted orthogonal spreading symbols to a radio frequency band, and transmitting the shifted symbols through the antennas.