Mobile communication apparatus with antenna array and mobile communication method therefor

• US 20030068983A1
• Filed: 05/16/2002
• Published: 04/10/2003
• Est. Priority Date: 05/17/2001
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Ju-ho, Lee, Hyeon-woo, Lee, Yong-suk, Kim, Sung-Jin, Kim, Ki-ho, Lee, Jong-hyeuk
• Granted Patent: US 7,079,514 B2
• Time in Patent Office: Days
• US Class Current: 455/69
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0647 Variable feedback rate
• CPC Class Codes: H04B 7/065 Variable contents, e.g. long-term or short-short

Abstract

A mobile communication apparatus with an antenna array and a mobile communication method therefore, wherein the apparatus includes a base station with an antenna array and a mobile station, wherein the mobile station determines a channel downlink characteristic for each antenna, determines long-term information and short-term information, converts the determined long-term information and short-term information to a feedback signal, and transmits the feedback signal to the base station. The base station receives the feedback signal, extracts a plurality of weights from the long-term information and short-term information, multiplies a multiplexed dedicated physical channel signal by the respective weights, adds respective pilot channel signals to the products, and transmits the results of the additions through the antenna array to the mobile station. The present invention allows more users to use the same bandwidth through efficient feedback bandwidth utilization and maximized diversity and beamforming effects.

Claims

1. A mobile communication apparatus comprising:

a base station with an antenna array; and

a mobile station,

wherein the mobile station determines a channel downlink characteristic for each antenna using a signal transmitted from the base station, determines long-term information and short-term information based on a correlation of characteristics between channels for each antenna using the channel downlink characteristic, converts the determined long-term information and short-term information to a feedback signal, and transmits the feedback signal to the base station; and

wherein the base station receives the feedback signal, extracts a plurality of weights from the long-term information and short-term information restored from the received feedback signal, multiplies a multiplexed dedicated physical channel signal by the respective weights, adds respective pilot channel signals to the products, and transmits the results of the additions through the antenna array to the mobile station.

2. The mobile communication apparatus as claimed in claim 1, wherein the mobile station comprises:

a mobile station channel characteristic determination unit which receives the signal transmitted from the base station, determines the channel downlink characteristic from the received signal, and outputs the determined channel downlink characteristic;

a mobile station long-term information determination unit which generates basis vectors and eigenvalues from the channel downlink characteristic, calculates a number of beams, which is equal to the number of effective basis vectors, from the eigenvalues, and outputs the effective basis vectors and the number of beams as the long-term information;

a first coefficient storage unit which predetermines and stores tables by the number of beams, each table having coefficients of the effective basis vector with indices, and outputs the coefficients of a table selected by the number of beams input from the mobile station long-term information determination unit;

a first short-term information determination unit which obtains weight vectors using the coefficients output from the first coefficient storage unit and the effective basis vectors, determines the index resulting in a maximum reception power using the weight vectors and the channel downlink characteristic, and outputs the determined index as the short-term information, wherein the weight vectors are expressed as combinations of the effective basis vectors and the coefficients, and the weight vector corresponding to the index determined as the short-term information consists of the weights; and

a mobile station signal conversion unit for converting the determined long-term information and short-term information to the feedback signal.

3. The mobile communication apparatus as claimed in claim 2, wherein the mobile station further comprises a first selection unit which selectively outputs the coefficients from the first coefficient storage unit according to a mode signal, the mobile station long-term information determination unit generates the mode signal representing a combination mode of the effective basis vectors using the channel downlink characteristic, incorporates the mode signal into the long-term information, the first coefficient storage unit predetermines and stores tables by the number of beams and the combination modes, and the first short-term information determination unit obtains the weights using the coefficients output from the first selection unit and the effective basis vectors.

4. The mobile communication apparatus as claimed in claim 3, wherein the mobile station long-term information determination unit incorporates the eigenvalues into the long-term information and outputs the long-term information to the mobile station signal conversion unit.

5. The mobile communication apparatus as claimed in claim 4, wherein the mobile station signal conversion unit comprises:

a mobile station long-term information formatting portion which formats the long-term information input from the mobile station long-term information determination unit and outputs the formatted result;

a mobile station short-term information formatting portion which formats the short-term information input from the first short-term information determination unit and outputs the formatted result; and

a time division multiplexing portion which time-division-multiplexes the formatted result input from the mobile station long-term information formatting portion and the formatted result input from the mobile station short-term information formatting portion and outputs the result of the time-division-multiplexing as the feedback signal.

6. The mobile communication apparatus of claim 4, wherein the base station comprises:

a first weight extraction unit which restores the long-term information and short-term information from the feedback signal received through the antenna array, extracts the weights from the restored long-term information and short-term information, and outputs the extracted weights;

a multiplexing unit which multiplexes a dedicated physical channel signal and outputs the result of the multiplexing;

a multiplication unit which multiplies the result of the multiplexing input from the multiplexing unit by the respective weights input from the first weight extraction unit, and outputs the products; and

an addition unit which adds the respective pilot channel signals to the products input from the multiplication unit and outputs the results of the additions,

wherein the results of the additions output from the addition unit are transmitted through the antenna array to the mobile station.

7. The mobile communication apparatus as claimed in claim 3, wherein the mobile station long-term information determination unit comprises:

an eigen analysis portion which generates the basis vectors and the eigenvalues from the channel downlink characteristic by eigen analysis;

a beam number calculation portion which counts the number of the eigenvalues which are greater than a first threshold value, and outputs the result of the counting as the number of beams;

a second selection portion which selects basis vectors in a quantity equal to the number of beams from among the basis vectors input from the eigen analysis portion as the effective basis vectors, and outputs the effective basis vectors; and

a first mode signal generation portion which generates the mode signal using the channel downlink characteristic.

8. The mobile communication apparatus as claimed in claim 7, wherein the first mode signal generation portion comprises:

a downlink short-term time-space covariance matrix calculation portion which calculates a downlink short-term time-space covariance matrix from the channel downlink characteristic;

an expectation value calculation portion which calculates expectation values E^SL and E^EG based on the downlink short-term time-space covariance matrix, the coefficients input from the first coefficient storage unit and the effective basis vectors using the following formulae;

$E^{S<br><br>\text{\hspace{1em}<br><br>}<br><br>L}=E<br><br>\left[w_s^H<br><br>R_{D<br><br>\text{\hspace{1em}<br><br>}<br><br>L}^{S<br><br>\text{\hspace{1em}<br><br>}<br><br>T}<br><br>w_s\right],a<br><br>\text{\hspace{1em}<br><br>}<br><br>n<br><br>\text{\hspace{1em}<br><br>}<br><br>d$$E^{E<br><br>\text{\hspace{1em}<br><br>}<br><br>G}=E<br><br>\left[w_e^H<br><br>R_{D<br><br>\text{\hspace{1em}<br><br>}<br><br>L}^{S<br><br>\text{\hspace{1em}<br><br>}<br><br>T}<br><br>w_e\right]$

 

where R_DL^ST denotes the downlink short-term time-space covariance matrix,

$w_s=\underset{i=0}{\overset{N_B-1}{\sum <br><br>}}<br><br>a_i^s<br><br>\left(b\right)<br><br>v_i,w_e=\underset{i=0}{\overset{N_B-1}{\sum <br><br>}}<br><br>a_i^e<br><br>\left(b\right)<br><br>v_i,w_s^H$

 

is a conjugate-transpose matrix of w_s, and w_e^H is a conjugate-transpose matrix of w_e, where v_i is the effective basis vector, b is the index, N_B denotes the number of beams, a_i^s(b) are coefficients which are determined for the selection combination mode with the index b from among coefficients input from the first coefficient storage portion, and a_i^e(b) are coefficients which are determined for the equal-gain combination mode with the index b from among coefficients input from the first coefficient storage portion; and

a first comparison portion which compares the expectation values and generates the mode signal in response to the result of the comparison.

9. The mobile communication apparatus as claimed in claim 7, wherein the first mode signal generation portion comprises:

a direction-of-arrival (DOA) calculation portion which calculates DOA'"'"'s at the mobile station from the channel downlink characteristic; and

a second comparison portion which compares a difference between adjacent DOA'"'"'s with a second threshold value and generates the mode signal in response to the result of the comparison.

10. The mobile communication apparatus as claimed in claim 7, wherein the first mode signal generation portion comprises:

an angular spread calculation portion which calculates the angular spread of directions-of-arrival (DOA'"'"'s) at the mobile station from the channel downlink characteristic; and

a third comparison portion which compares the mean angular spread with a third threshold value and generates the mode signal corresponding to the result of the comparison.

11. The mobile communication apparatus as claimed in claim 2, wherein the first short-term information determination unit comprises:

a first basis vector combination portion which combines the effective basis vectors with the coefficients output from the first coefficient storage unit and outputs the resulting combinations as the weight vectors;

a reception power calculation portion which multiplies the respective weight vectors input from the first basis vector combination portion by the channel downlink characteristic, calculates the norm square of the respective products, and outputs the results of the calculation as reception power values; and

a maximum power finding portion which finds as the maximum reception power the largest power reception value among the reception power values input from the reception power calculation portion and outputs as the short-term information the index in which the coefficients used to calculate the weight vector are positioned.

12. The mobile communication apparatus as claimed in claim 3, wherein the first short-term information determination unit comprises:

a first basis vector combination portion which combines the effective basis vectors with the coefficients input from the first selection unit and outputs the resulting combinations as the weight vectors;

a reception power calculation portion which multiplies the respective weight vectors input from the first basis vector combination portion by the channel downlink characteristic, calculates the norm square of the respective products, and outputs the results of the calculation as reception power values; and

a maximum power finding portion which finds as the maximum reception power the largest power reception value from among the reception power values input from the reception power calculation portion and outputs the index in which the coefficients used to calculate the weight vector are positioned,

wherein the weight vector corresponding to the index determined as the short-term information consists of the weights.

13. The mobile communication apparatus as claimed in claim 6, wherein the first weight extraction unit comprises:

a first information restoration portion which restores the long-term information and short-term information from the received feedback signal and outputs the restored long-term information and short-term information;

a second coefficient storage portion which predetermines and stores tables by the number of beams, each table having coefficients of the effective basis vectors with indices, and extracts coefficients from a table, which is selected in response to the number of beams incorporated into the long-term information, in response to the short-term information; and

a second basis vector combination portion which combines the effective basis vectors incorporated into the long-term information using the coefficients input from the second coefficient storage portion and outputs the resulting combinations as the weights to the multiplication unit.

14. The mobile communication apparatus as claimed in claim 13, wherein the second basis vector combination portion combines the effective basis vectors incorporated into the long-term information using the coefficients input from the second coefficient storage portion and the eigenvalues incorporated into the long-term information and outputs the resulting combinations as the weights to the multiplication unit.

15. The mobile communication apparatus as claimed in claim 13, wherein the second basis vector combination portion combines the effective basis vectors incorporated into the long-term information using the coefficients input from the second coefficient storage portion and the eigenvalues incorporated into the long-term information, and outputs the resulting combinations as the weights to the multiplication unit.

65. The mobile communication apparatus as claimed in claim 6, wherein the multiplexing unit comprises a multiplier which multiplies the dedicated physical channel signal by a spread/scramble signal and outputs the product as the result of the multiplexing.

67. The mobile communication apparatus as claimed in claim 6, wherein the multiplexing unit comprises a time division multiplexing portion which time-division-multiplexes different dedicated physical channel signals for each user and outputs the result of the time-division-multiplexing as the result of the multiplexing.

69. The mobile communication apparatus as claimed in claim 1, wherein the pilot channel signals are common pilot channel (CPICH) signals, dedicated pilot channel (DPICH) signals, or secondary common pilot channel (SCPICH) signals.

16. A mobile communication method using an antenna array for a mobile communication apparatus including a base station with the antenna array and a mobile station, the method comprising:

(a) determining a channel downlink characteristic for each antenna using a signal transmitted from the base station, determining long-term information and short-term information based on a correlation of characteristics between channels for each antenna using the channel downlink characteristic, converting the determined long-term information and short-term information to a feedback signal, and transmitting the feedback signal to the base station; and

(b) receiving the feedback signal, extracting a plurality of weights from the long-term information and short-term information restored from the received feedback signal, multiplying a multiplexed dedicated physical channel signal by the respective weights, adding respective pilot signals to the products, and transmitting the results of the additions through the antenna array to the mobile station.

17. The mobile communication method as claimed in claim 16, wherein (a) comprises:

(a1) receiving the signal transmitted from the base station and determining the channel downlink characteristic from the received signal;

(a2) generating basis vectors and eigenvalues from the channel downlink characteristic, calculating the number of beams which is equal to the number of effective basis vectors, from the eigenvalues, and outputting the effective basis vectors and the number of beams as the long-term information;

(a3) determining as the short-term information an index resulting in a maximum reception power using weight vectors calculated from the effective basis vectors, the channel downlink characteristic, and coefficients of a table corresponding to the number of beams from among tables which are predetermined by the number of beams and each of which has coefficients of the effective basis vectors with indices and is stored in the mobile station.

(a4) converting the determined long-term information and short-term information to the feedback signal,

wherein the weight vectors are expressed as combinations of the effective basis vectors and the coefficients, and the weight vector corresponding to the index determined as the short-term information consists of the weights.

18. The mobile communication method as claimed in claim 17, wherein in (a2), a mode signal representing a combination mode of the effective basis vectors is generated from the channel downlink characteristic and the generated mode signal is incorporated into the long-term information, and in (a3), the index resulting in a maximum reception power is determined as the short-term information using the weight vectors calculated from the effective basis vectors, the channel downlink characteristic, and the coefficients of a table corresponding to the number of beams and the mode signal from among tables which are predetermined by the number of beams and the combination modes and each of which has the coefficients of the effective basis vectors with indices and is stored in the mobile station.

19. The mobile communication method as claimed in claim 18, wherein in (a2), the eigenvalues are incorporated into the long-term information.

20. The mobile communication method as claimed in claim 19, wherein (b) comprises:

(b1) restoring the long-term information and short-term information from the feedback signal received through the antenna array and extracting the weights from the restored long-term information and short-term information;

(b2) multiplexing the dedicated physical channel signal and multiplying the result of the multiplexing by the respective weights extracted in (b1); and

(b3) adding the respective pilot channel signals to the products obtained in (b2),

wherein the results of the additions in (b3) are transmitted through the antenna array to the mobile station.

21. The mobile communication method as claimed in claim 18, wherein (a2) comprises:

(a21) generating the basis vectors and the eigenvalues from the channel downlink characteristic by eigen analysis;

(a22) counting the number of the eigenvalues which are greater than a first threshold value to obtain the number of beams, and selecting basis vectors in a quantity equal to the number of beams from among the basis vectors generated in (a21) as the effective basis vectors; and

(a23) generating the mode signal using the channel downlink characteristic.

22. The mobile communication method as claimed in claim 21, wherein (a23) comprises:

(a231) calculating expectation values for the respective combination modes using the channel downlink characteristic, the effective basis vectors, and the coefficients of tables corresponding to the number of beams from among tables which are predetermined by the number of beams and the combination modes;

(a232) determining whether an expectation value for a selection combination mode is larger than an expectation value for an equal-gain combination mode;

(a233) if the expectation value for the selection combination mode is determined to be larger than the expectation value for the equal-gain combination mode, generating the mode signal representing the selection combination mode; and

(a234) if the expectation value for the selection combination mode is determined to be less than or equal to the expectation value for the equal-gain combination mode, generating the mode signal representing the equal-gain combination mode,

wherein (a231), (a232), (a233), and (a234) are performed at the same time as (a21) and (a22).

23. The mobile communication method as claimed in claim 22, wherein (a231) comprises:

calculating a downlink short-term time-space covariance matrix from the channel downlink characteristic; and

calculating the expectation values based on the downlink short-term time-space covariance matrix, the coefficients of the tables corresponding to the number of beams, and the effective basis vectors using the following formulae;

$E^{S<br><br>\text{\hspace{1em}<br><br>}<br><br>L}=E<br><br>\left[w_s^H<br><br>R_{D<br><br>\text{\hspace{1em}<br><br>}<br><br>L}^{S<br><br>\text{\hspace{1em}<br><br>}<br><br>T}<br><br>w_s\right],a<br><br>\text{\hspace{1em}<br><br>}<br><br>n<br><br>\text{\hspace{1em}<br><br>}<br><br>d$$E^{E<br><br>\text{\hspace{1em}<br><br>}<br><br>G}=E<br><br>\left[w_e^H<br><br>R_{D<br><br>\text{\hspace{1em}<br><br>}<br><br>L}^{S<br><br>\text{\hspace{1em}<br><br>}<br><br>T}<br><br>w_e\right]$

 

where E^SL denotes the expectation value for the selection combination mode, E^EG denotes the expectation value for the equal-gain combination mode, R_DL^ST denotes the downlink short-term time-space covariance matrix,

$w_s=\underset{i=0}{\overset{N_B-1}{\sum <br><br>}}<br><br>a_i^s<br><br>\left(b\right)<br><br>v_i,w_e=\underset{i=0}{\overset{N_B-1}{\sum <br><br>}}<br><br>a_i^e<br><br>\left(b\right)<br><br>v_i,w_s^H$

 

is a conjugate-transpose matrix of w_s, and w_e^H is a conjugate-transpose matrix of w_e, where v_i is the effective basis vector, b is the index, N_B denotes the number of beams, a_i^s(b) are coefficients determined for the selection combination mode with the index b from among coefficients which are stored in a table corresponding to the number of beams, and a_i^e(b) are coefficients determined for the equal-gain combination mode with the index b among coefficients which are stored in tables corresponding to the number of beams.

24. The mobile communication method as claimed in claim 21, wherein (a23) comprises:

(a241) calculating directions-of-arrival (DOA'"'"'s) at the mobile station from the channel downlink characteristic;

(a242) determining whether a difference between adjacent DOA'"'"'s is larger than a second threshold value;

(a243) if the difference between adjacent DOA'"'"'s is determined to be larger than the second threshold value, generating the mode signal representing the equal-gain combination mode; and

(a244) if the difference between adjacent DOA'"'"'s is determined to be less than or equal to the second threshold value, generating the mode signal representing the selection combination mode,

wherein (a241), (a242), (a243), and (a244) are performed at the same time as (a21) and (a22).

25. The mobile communication method as claimed in claim 21, wherein (a23) comprises:

(a251) calculating angular spread of directions-of-arrival (DOA'"'"'s) at the mobile station from the channel downlink characteristic; and

(a252) determining whether the mean angular spread is larger than a third threshold value;

(a253) if the mean angular spread is determined to be larger than the third threshold value, generating the mode signal representing the equal-gain combination mode; and

(a254) if the mean angular spread is determined to be less than or equal to the third threshold value, generating the mode signal representing the selection combination mode,

wherein (a251), (a252), (a253), and (a254) are performed at the same time as (a21) and (a22).

26. The mobile communication method as claimed in claim 17, wherein (a3) comprises:

(a311) calculating the weight vectors by combining the effective basis vectors with the coefficients of the tables corresponding to the number of beams;

(a312) multiplying the respective weight vectors obtained in (a311) by the channel downlink characteristic and calculating the norm square of the respective products to obtain reception power values; and

(a313) fining as the maximum reception power the largest power reception value among the reception power values and determining as the short-term information the index in which the coefficients used to calculate the weight vector are positioned.

27. The mobile communication method as claimed in claim 18, wherein (a3) comprises:

(a321) calculating the weight vectors by combining the effective basis vectors with the coefficients of the tables corresponding to the number of beams and the mode signal;

(a322) multiplying the respective weight vectors obtained in (a321) by the channel downlink characteristic and calculating the norm square of the respective products to obtain reception power values; and

(a323) fining as the maximum reception power the largest power reception value among the reception power values and determining as the short-term information the index in which the coefficients used to calculate the weight vector are positioned.

28. The mobile communication method as claimed in claim 20, wherein (b1) comprises:

(b11) restoring the long-term information and short-term information from the feedback signal;

(b12) selecting a table corresponding to the number of beams incorporated into the long-term information from among tables which are predetermined by the number of beams and each of which has the coefficients of the effective basis vectors with indices and is stored in the base station, and extracting coefficients corresponding to the short-term information among coefficients of the selected table;

(b13) obtaining the weights by combining the effective basis vectors incorporated into the long-term information using the coefficients extracted in (b12).

29. The mobile communication method as claimed in claim 28, wherein in (b12), a table corresponding to the number of beams and the mode signal incorporated into the long-term information is selected among tables which are predetermined by the number of beams and the combination modes and each of which has the coefficients of the effective basis vectors with indices and is stored in the base station, and coefficients corresponding to the short-term information from among coefficients of the selected table are extracted.

30. The mobile communication method as claimed in claim 28, wherein in (b13), the weights are obtained by combining the effective basis vectors incorporated into the long-term information using the coefficients extracted in (b12) and the eigenvalues incorporated into the long-term information.

31. The mobile communication method as claimed in claim 29, wherein in (b13), the weights are obtained by combining the effective basis vectors incorporated into the long-term information using the coefficients extracted in (b12) and the eigenvalues incorporated into the long-term information.

32. The mobile communication method as claimed in claim 22, wherein the coefficients a_i(b) of the table corresponding to the selection combination mode are previously obtained according to the following formula:

33. The mobile communication method as claimed in claim 22, wherein the coefficients a_i(b) of the table corresponding to the equal-gain combination mode are previously obtained according to the following formula:

34. The mobile communication method as claimed in claim 17, wherein the table of the coefficients used in (a3) is for the selection combination mode.

35. The mobile communication method as claimed in claim 17, wherein the table of the coefficients used in (a3) is for the equal-gain combination mode.

66. The mobile communication method as claimed in claim 16, wherein the multiplexed dedicated physical channel signal is obtained by multiplying a spread/scramble signal by a dedicated physical channel signal.

68. The mobile communication method as claimed in claim 16, wherein the multiplexed dedicated physical channel signal is obtained by time-division-multiplexing different dedicated physical channel signals for each user.

70. The mobile communication method as claimed in claim 16, wherein the pilot channel signals are common pilot channel (CPICH) signals, dedicated pilot channel (DPICH) signals, or secondary common pilot channel (SCPICH) signals.

36. A mobile communication apparatus including a base station with an antenna array and a mobile station,

wherein the mobile station determines a channel downlink characteristic for each antenna using a signal transmitted from the base station, determines short-term information based on a correlation of characteristics between channels for each antenna using the channel downlink characteristic, converts the determined short-term information to a feedback signal, and transmits the feedback signal to the base station;

and

wherein the base station determines a channel uplink characteristic for each antenna from a signal transmitted from the mobile station, extracts a plurality of weights based on long-term information determined using the channel uplink characteristic and the short-term information restored from the received feedback signal, multiplies a multiplexed dedicated physical channel signal by the respective weights, adds respective basis pilot signals, which are obtained using at least one pilot channel signal and the long-term information, to the products, and transmits the results of the additions through the antenna array to the mobile station.

37. The mobile communication apparatus as claimed in claim 36, wherein the mobile station determines the short-term information using the long-term information restored from the signal transmitted from the base station and the channel downlink characteristic, and the base station converts the determined long-term information to a radio signal and transmits the radio signal to the mobile station.

38. The mobile communication apparatus as claimed in claim 36, wherein the mobile station comprises:

a mobile station channel characteristic determination unit which receives the signal transmitted from the base station, determines the channel downlink characteristic for each antenna from the received signal in a spatial-temporal manner, and outputs the determined channel downlink characteristic;

a third coefficient storage unit which predetermines and stores a table which has coefficients of effective basis vectors to be combined with indices;

a second short-term information determination unit which obtains weight vectors by combining given identity basis vectors with the coefficients output from the third coefficient storage unit, determines the index resulting in a maximum reception power using the weight vectors and the channel downlink characteristic, and outputs the determined index as the short-term information; and

a mobile station signal conversion unit for converting the determined short-term information to the feedback signal;

wherein the weight vector corresponding to the index determined as the short-term information by the second short-term information determination unit consists of the weights, and the converted feedback signal is transmitted to the base station.

39. The mobile communication apparatus as claimed in claim 37, wherein the mobile station comprises:

a mobile station channel characteristic determination unit which receives the signal transmitted from the base station, determines the channel downlink characteristic for each antenna from the received signal in a spatial-temporal manner, and outputs the determined channel downlink characteristic;

a second information restoration unit which receives the signal transmitted from the base station, restores the long-term information from the received signal, and outputs the restored long-term information;

a fourth coefficient storage unit which predetermines and stores tables for the long-term information, each of which has coefficients of effective basis vectors to be combined with indices, and outputs the coefficients of a table corresponding to the long-term information input from the second information restoration unit, which is selected from the stored tables;

a second short-term information determination unit which obtains weight vectors by combining given identity basis vectors with the coefficients output from the fourth coefficient storage unit, determines the index resulting in a maximum reception power using the weight vectors and the channel downlink characteristic, and outputs the determined index as the short-term information; and

a mobile station signal conversion unit for converting the determined short-term information to the feedback signal,

wherein the weight vector corresponding to the index determined as the short-term information by the second short-term information determination unit consists of the weights, and the converted feedback signal is transmitted to the base station.

40. The mobile communication apparatus as claimed in claim 38, wherein the second short-term information determination unit comprises:

a third basis vector combination portion which combines the identity basis vectors using the coefficients input from the third coefficient storage unit and outputs the resulting combinations as the weight vectors;

a reception power calculation portion which multiplies the respective weight vectors input from the third basis vector combination portion by the channel downlink characteristic, calculates the norm square of the respective products, and outputs the calculated results as reception power values; and

a maximum power finding portion which finds as the maximum reception power the largest power reception value among the reception power values input from the reception power calculation portion and outputs as the short-term information the index in which the coefficients used to calculate the weight vector are positioned.

41. The mobile communication apparatus as claimed in claim 38, wherein the base station comprises:

a base station long-term information determination unit which determines the channel uplink characteristic using the signal transmitted from the mobile station and determines the long-term information using the determined channel uplink characteristic;

a second weight extraction unit which restores the short-term information from the feedback signal received through the antenna array and extracts the weights using the restored short-term information and the long-term information determined by the base station long-term information determination unit;

a multiplexing unit which multiplexes a dedicated physical channel signal and outputs the result of the multiplexing;

a multiplication unit which multiplies the result of the multiplexing input from the multiplexing unit by the respective weights input from the second weight extraction unit, and outputs the products; and

a basis pilot signal generation unit which generates the basis pilot signals using the at least one pilot channel signal and the long-term information determined by the base station long-term information determination unit;

an addition unit which adds the respective basis pilot signals to the products input from the multiplication unit and outputs the results of the additions, wherein the results of the additions output from the addition unit are transmitted through the antenna array to the mobile station.

42. The mobile communication apparatus as claimed in claim 39, wherein the base station comprises:

a base station long-term information determination unit which determines the channel uplink characteristic using the signal transmitted from the mobile station and determines the long-term information using the determined channel uplink characteristic;

a third weight extraction unit which restores the short-term information from the feedback signal received through the antenna array and extracts the weights using the restored short-term information and the long-term information determined by the base station long-term information determination unit;

a multiplexing unit which multiplexes a dedicated physical channel signal and outputs the result of the multiplexing;

a multiplication unit which multiplies the result of the multiplexing input from the multiplexing unit by the respective weights input from the third weight extraction unit, and outputs the products;

a basis pilot signal generation unit which generates the basis pilot signals using at least one pilot channel signal and the long-term information determined by the base station long-term information determination unit;

a base station signal conversion unit which converts the long-term information determined by the long-term information determination unit to a radio signal; and

an addition unit which adds the respective basis pilot signals to the products input from the multiplication unit and outputs the results of the additions,

wherein the radio signals output from the base station signal conversion unit are transmitted through the antenna array to the mobile station.

43. The mobile communication apparatus as claimed in claim 41, wherein the second weight extraction unit comprises:

a third information restoration portion which restores the short-term information from the received feedback signal and outputs the restored short-term information;

a fifth coefficient storage portion which predetermines and stores a table which has coefficients of the effective basis vectors to be combined with indices, and outputs coefficients corresponding to the short-term information input from the third information restoration portion; and

a fourth basis vector combination portion which combines the coefficients input from the fifth coefficient storage portion and the effective basis vectors incorporated into the long-term information input from the base station long-term information determination unit, and outputs the resulting combinations as the weights to the multiplication unit.

44. The mobile communication apparatus as claimed in claim 43, wherein the fifth coefficient storage portion predetermines and stores tables for the long-term information, each of which has the coefficients of the effective basis vectors, and outputs to the fourth basis vector combination portion coefficients corresponding to the long-term information determined by the base long-term information determination unit and the short-term information input from the third information restoration portion.

45. The mobile communication apparatus as claimed in claim 43, wherein the base station long-term information determination unit comprises:

a base station channel characteristic determination portion which determines the channel uplink characteristic for each antenna using the signal transmitted from the mobile station;

an uplink long-term time-space covariance matrix generation portion which generates an uplink long-term time-space covariance matrix from the channel uplink characteristic determined by the base station channel characteristic determination portion;

a channel information conversion portion which converts the uplink long-term time-space covariance matrix to a downlink long-term time-space covariance matrix; and

a long-term information generation portion which generates the long-term information from the downlink long-term time-space covariance matrix input from the channel information conversion portion by an eigen analysis method.

46. The mobile communication apparatus as claimed in claim 45, wherein the long-term information generation portion comprises a second mode signal generation portion which generates a mode signal from the long-term information generated using the eigen analysis method and the channel uplink characteristic.

47. The mobile communication apparatus as claimed in claim 46, wherein the second mode signal generation portion comprises:

an uplink short-term time-space covariance matrix calculation portion which calculates an uplink short-term time-space covariance matrix from the uplink long-term time-space covariance matrix;

an expectation value calculation portion which calculates expectation values E^SL and E^EG based on the uplink short-term time-space covariance matrix, the coefficients input from the fifth coefficient storage portion and the effective basis vectors incorporated into the long-term information input from the long-term information determination unit using the following formulae;

$E^{S<br><br>\text{\hspace{1em}<br><br>}<br><br>L}=E<br><br>\left[w_s^H<br><br>R_{U<br><br>\text{\hspace{1em}<br><br>}<br><br>L}^{S<br><br>\text{\hspace{1em}<br><br>}<br><br>T}<br><br>w_s\right],a<br><br>\text{\hspace{1em}<br><br>}<br><br>n<br><br>\text{\hspace{1em}<br><br>}<br><br>d$$E^{E<br><br>\text{\hspace{1em}<br><br>}<br><br>G}=E<br><br>\left[w_e^H<br><br>R_{U<br><br>\text{\hspace{1em}<br><br>}<br><br>L}^{S<br><br>\text{\hspace{1em}<br><br>}<br><br>T}<br><br>w_e\right]$

 

where R_UL^ST denotes the uplink short-term time-space covariance matrix,

$\begin{array}{c}{w}_s=\underset{i=0}{\overset{N_B-1}{\sum <br><br>}}<br><br>a_i^s<br><br>\left(b\right)<br><br>v_i,\\ w_e=\underset{i=0}{\overset{N_B-1}{\sum <br><br>}}<br><br>a_i^e<br><br>\left(b\right)<br><br>v_i,w_s^H\end{array}$

 

is a conjugate-transpose matrix of w_s, and w_e^H is a conjugate-transpose matrix of w_e, where v_i is the effective basis vector, b is the index, N_B denotes the number of beams which is equal to the number of the effective basis vectors, a_i^s(b) are coefficients which are determined for the selection combination mode with the index b from among coefficients input from the fifth coefficient storage portion, and a_i^e(b) are coefficients which are determined for the equal-gain combination mode with the index b from among coefficients input from the fifth coefficient storage portion; and

a first comparison portion which compares the expectation values and generates the mode signal in response to the result of the comparison.

48. The mobile communication apparatus as claimed in claim 46, wherein the second mode signal generation portion comprises:

a direction-of-arrival (DOA) calculation portion which calculates DOA'"'"'s at the mobile station from the channel uplink characteristic; and

a second comparison portion which compares a difference between adjacent DOA'"'"'s with a second threshold value and generates the mode signal in response to the result of the comparison.

49. The mobile communication apparatus as claimed in claim 46, wherein the second mode signal generation portion comprises:

an angular spread calculation portion which calculates the angular spread of directions-of-arrival (DOA'"'"'s) at the mobile station from the channel uplink characteristic; and

a third comparison portion which compares the mean angular spread with a third threshold value and generates the mode signal in response to the result of the comparison.

50. The mobile communication apparatus as claimed in claim 46, wherein the second mode signal generation portion comprises a fourth comparison portion which compares a difference between the first largest eigenvalue and the second largest eigenvalue from among eigenvalues with a fourth threshold value and outputs the mode signal in response to the result of the comparison, and the eigenvalues are generated from the downlink long-term time-space covariance matrix using the eigen analysis method in the long-term information generation portion and are incorporated into the long-term information.

51. The mobile communication apparatus as claimed in claim 41, wherein the basis pilot signal generation unit multiplies the pilot channel signals in a quantity equal to the number of beams, which is the same as the number of the effective basis vectors, by the respective effective basis vectors, adds the products, and outputs the results of the additions as the basis pilot signals to the addition unit.

52. The mobile communication apparatus as claimed in claim 41, wherein the basis pilot signal generation unit adjusts amplitudes of the effective basis vectors, multiplies the pilot channel signals in a quantity equal to the number of beams, which is the same as the number of the effective basis vectors, by respective amplitude-adjusted effective basis vectors, adds the products, and outputs the results of the additions as the basis pilot signals to the addition unit.

53. A mobile communication method using an antenna array in a mobile communication apparatus including a base station with the antenna array and a mobile station, the method comprising:

(a) determining a channel downlink characteristic for each antenna using a signal transmitted from the base station, determining short-term information based on a correlation of characteristics between channels for each antenna, using the channel downlink characteristic, converting the determined short-term information to a feedback signal, and transmitting the feedback signal to the base station; and

(b) determining a channel uplink characteristic for each antenna from a signal transmitted from the mobile station, extracting a plurality of weights based on long-term information, which is determined using the channel uplink characteristic, and the short-term information restored from the received feedback signal, multiplying a multiplexed dedicated physical channel signal by the respective weights, adding respective basis pilot signals, which are obtained using at least one pilot channel signal and the long-term information, to the products, and transmitting the results of the additions through the antenna array to the mobile station.

54. The mobile communication method as claimed in claim 53, wherein in (a), the short-term information is determined using the long-term information, which is restored from the signal transmitted from the base station, and the channel downlink characteristic, and in (b), the determined long-term information is converted to a radio signal and transmitted to the mobile station.

55. The mobile communication method as claimed in claim 53, wherein (a) comprises:

(a1) receiving the signal transmitted from the base station and determining the channel downlink characteristic for each antenna from the received signal in a spatial-temporal manner;

(a2) calculating weight vectors by combining identity basis vectors with corresponding coefficients from among coefficients of a table which is predetermined and stored and has coefficients of the effective basis vectors with indices, and determining as the short-term information the index resulting in a maximum reception power using the weight vectors and the channel downlink characteristic; and

(a3) converting the determining short-term information to the feedback signal,

wherein the weight vector corresponding to the index determined in (a2) consists of the weights, and the converted result from (a3) is transmitted to the base station.

56. The mobile communication method as claimed in claim 54, wherein (a) comprises:

(a1) receiving the signal transmitted from the base station, determining the channel downlink characteristic for each antenna from the received signal in a spatial-temporal manner, and restoring the long-term information from the received signal;

(a2) calculating weight vectors by combining identity basis vectors with the coefficients of a table which is selected according to the long-term information restored in (a1) from tables which are predetermined and each of which has coefficients of effective basis vectors to be combined with indices, and determining as the short-term information the index resulting in a maximum reception power using the weight vectors and the channel downlink characteristic; and

(a3) converting the determining short-term information to the feedback signal,

wherein the weight vector corresponding to the index determined in (a2) consists of the weights, and the converted result from (a3) is transmitted to the base station.

57. The mobile communication method as claimed in claim 55, wherein (a2) comprises:

(a21) calculating the weight vectors by combining the identity basis vectors using the coefficients of the table;

(a22) multiplying the respective weight vectors calculated in (a21) by the channel downlink characteristic and calculating the norm square of the respective products as reception power values; and

(a23) finding as the maximum reception power the largest power reception value among the reception power values and determining as the short-term information the index in which the coefficients used to calculate the weight vector are positioned.

58. The mobile communication method as claimed in claim 55, wherein (b) comprises:

(b1) determining the channel uplink characteristic using the signal transmitted from the mobile station and determining the long-term information using the determined channel uplink characteristic;

(b2) restoring the short-term information from the feedback signal received through the antenna array and extracting the weights using the restored short-term information and the long-term information determined in (b1);

(b3) multiplexing a dedicated physical channel signal;

(b4) multiplying the result of the multiplexing from (b3) by the respective weights extracted in (b2);

(b5) generating the basis pilot signals using the at least one pilot channel signal and the long-term information determined in (b1); and

(b6) adding the respective basis pilot signals to the products from (b4),

wherein (b2) comprises;

(b21) restoring the short-term information from the received feedback signal;

(b22) extracting coefficients corresponding to the short-term information from among coefficients of tables which are predetermined and each of which has the coefficients of the effective basis vectors to be combined with indices; and

(b23) obtaining the weights using the extracted coefficients and the long-term information determined in (b1),

wherein the results of the additions from (b6) are transmitted through the antenna array to the mobile station.

59. The mobile communication method as claimed in claim 56, wherein (b) comprises:

(b1) determining the channel uplink characteristic using the signal transmitted from the mobile station and determining the long-term information using the determined channel uplink characteristic;

(b2) restoring the short-term information from the feedback signal received through the antenna array and extracting the weights using the restored short-term information and the long-term information determined in (b1);

(b3) multiplexing a dedicated physical channel signal;

(b4) multiplying the result of the multiplexing from (b3) by the respective weights;

(b5) generating the basis pilot signals using the at least one pilot channel signal and the long-term information determined in (b1);

(b6) adding the respective basis pilot signals to the products from (b4); and

(b7) converting the long-term information determined in (b1) to a radio signal,

wherein (b2) comprises;

(b21) restoring the short-term information from the received feedback signal;

(b22) extracting coefficients corresponding to the short-term information and the long-term information determined in (b1) from among coefficients of the tables which are predetermined by long-term information and each of which has the coefficients of the effective basis vectors to be combined with indices, and

(b23) obtaining the weights using the extracted coefficients and the long-term information determined in (b1),

wherein the results of the additions from (b6) and the converted result from (b7) are transmitted through the antenna array to the mobile station.

60. The mobile communication method as claimed in claim 58, wherein (b1) comprises:

(b11) determining the channel uplink characteristic for each antenna using the signal transmitted from the mobile station;

(b12) generating an uplink long-term time-space covariance matrix from the channel uplink characteristic determined in (b11);

(b13) converting the uplink long-term time-space covariance matrix to a downlink long-term time-space covariance matrix; and

(b14) generating the long-term information by an eigen analysis method from the downlink long-term time-space covariance matrix obtained in (b13).

61. The mobile communication method as claimed in claim 60, wherein (b14) comprises (b141) generating a mode signal from the long-term information generated using the eigen analysis method and the channel uplink characteristic.

62. The mobile communication method as claimed in claim 61, wherein (b141) comprises:

calculating a difference between the first largest eigenvalue and the second largest eigenvalue from among eigenvalues;

determining whether the difference between the first largest eigenvalue and the second largest eigenvalue is smaller than a fourth threshold value;

if the difference between the first largest eigenvalue and the second largest eigenvalue is determined to be smaller than the fourth threshold value, generating the mode signal representing a selection combination mode; and

if the difference between the first largest eigenvalue and the second largest eigenvalue is determined to be greater than or equal to the fourth threshold value, generating the mode signal representing an equal-gain combination mode,

wherein the eigenvalues are generated from the downlink long-term time-space covariance matrix using the eigen analysis method and incorporated into the long-term information.

63. The mobile communication method as claimed in claim 58, wherein in (b5), the pilot channel signals in a quantity equal to the number of beams, which is the same as the number of the effective basis vectors, are multiplied by the respective effective basis vectors, the products are added, and the results of the additions are determined as the basis pilot signals, and then (b6) is performed.

64. The mobile communication method as claimed in claim 58, wherein in (b5), the amplitudes of the effective basis vectors are adjusted, the pilot channel signals in a quantity equal to the number of beams, which is the same as the number of the effective basis vectors, are multiplied by the respective amplitude-adjusted effective basis vectors, the products are added, and the results of the additions are determined as the basis pilot signals, and then (b6) is performed.