Method and system for code reuse and capacity enhancement using null steering
First Claim
1. A null beam technique wherein only one of at least two remote users, all of whom employ a same or a correlated spreading code within a given cell or sector, is enabled to receive a communication from a base station transmitting to the at least two remote users, said base station transmitting to said remote users over an antenna array having a plurality of antennas, comprising:
- a) said base station modulating data di, for i=1, . . . , N, intended for one of N (N>
1) remote users with N+1 complex weights wi (for i=1, . . . , N, each is a N+1 complex vector), each modulated signal being directed to one of said N+1 antennas;
wherein each element of the vectors w1 and w2 is a function of the channel impulse responses from the antenna array to locations of the remote users;
b) summing the modulated data signals d1, d2, . . . dN and c) transmitting the summed signals.
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Accused Products
Abstract
The number of users and data capacity of wireless systems are increased by employing apparatus and method for increasing the number of spreading codes available in the system by providing a mechanism to reuse the already allocated spreading code or use the codes that may correlate to those already being used within the same sector/cell. This, in return, provides capacity improvement proportional to the number of added base station (BS) antennas for each cell. An antenna null steering technique for code allocation maintains the cross correlation properties of the codes only for the desired user and to obtain a gain in capacity improvement.
14 Citations
15 Claims
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1. A null beam technique wherein only one of at least two remote users, all of whom employ a same or a correlated spreading code within a given cell or sector, is enabled to receive a communication from a base station transmitting to the at least two remote users, said base station transmitting to said remote users over an antenna array having a plurality of antennas, comprising:
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a) said base station modulating data di, for i=1, . . . , N, intended for one of N (N>
1) remote users with N+1 complex weights wi (for i=1, . . . , N, each is a N+1 complex vector), each modulated signal being directed to one of said N+1 antennas;
wherein each element of the vectors w1 and w2 is a function of the channel impulse responses from the antenna array to locations of the remote users;
b) summing the modulated data signals d1, d2, . . . dN and c) transmitting the summed signals. - View Dependent Claims (2, 3, 4, 5)
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6. A null beam technique wherein only one of at least two remote users, all of whom employ different spreading code within a given cell or sector, is enabled to receive a communication from a base station transmitting to the at least two remote users, said base station transmitting to said remote users over an antenna array having a plurality of antennas, comprising:
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a) said base station modulating data di, for i=1, . . . , N, intended for one of N (N>
1) remote users with N+1 complex weights wi (for i=1, . . . , N, each is a N+1 complex vector), each modulated signal being directed to one of said N+1 antennas;
whereas each of the element of the vectors w1 and w2 is a function of the channel impulse responses from the antenna array to the location of all remote users;
b) summing the modulated data signals d1, d2, . . . dN and c) transmitting the summed signals. - View Dependent Claims (7, 8, 9, 10)
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11. A base station employing a null beam technique wherein only one of at least two remote users, all of whom employ a same or a correlated spreading code within a given cell or sector, is enabled to receive a communication from a base station transmitting to the at least two remote users, said base station transmitting to said remote users over an antenna array having a plurality of antennas, comprising:
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said base station having means for modulating data di, for i=1, . . . , N, intended for one of N (N>
1) remote users with N+1 complex weights wi (for i=1, . . . , N, each is a N+1 complex vector), each modulated signal being directed to one of said N+1 antennas;
wherein each element of the vectors w1 and w2 is a function of the channel impulse responses from the antenna array to locations of the remote users;
means for summing the modulated data signals d1, d2, . . . dN; and
means for transferring the summed signals to the antenna array for transmission. - View Dependent Claims (12, 13, 14, 15)
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Specification