Communication system employing transmit macro-diversity
First Claim
1. A method of employing coherent transmit diversity in a wireless communication network, the method comprising:
- forming a plurality of transmit signals, each comprising a combination of information signals intended for different ones of a plurality of wireless receivers, such that, at each one of said wireless receivers, the intended information signals in the plurality of transmit signals tend to add in free space while the other information signals tend to cancel in free space; and
coherently transmitting said transmit signals from said plurality of transmitters over different propagation channels to said plurality of receivers.
1 Assignment
0 Petitions
Accused Products
Abstract
Coherent transmit macro-diversity involves transmitting simultaneous signals from one or more transmitters to one or more wireless receivers. Transmit signals are formed as weighted combinations of the individual information signals for each of the wireless receivers. By properly weighting these receiver-specific signals, the combined signals combine at each receiver to cancel all but the desired information signal for that receiver. This improves reception performance and allows multiple receivers to operate on the same communication channel in the same area if desired. The weighting factors used to form the combined signals are based on propagation path characteristics between each of the transmit antennas and each of the receivers. This information is generally referred organized as a channel estimate matrix and is used to filter the information signals such that they may be combined in the required weighted combinations.
97 Citations
63 Claims
-
1. A method of employing coherent transmit diversity in a wireless communication network, the method comprising:
-
forming a plurality of transmit signals, each comprising a combination of information signals intended for different ones of a plurality of wireless receivers, such that, at each one of said wireless receivers, the intended information signals in the plurality of transmit signals tend to add in free space while the other information signals tend to cancel in free space; and
coherently transmitting said transmit signals from said plurality of transmitters over different propagation channels to said plurality of receivers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A method of transmitting signals in a wireless communication network from one or more transmitters to a plurality of receivers, the method comprising:
-
receiving a plurality of information signals at a transmit processor, each information signal intended for a different receiver;
generating a plurality of transmit signals by forming weighted combinations of said information signals based on channel estimates for propagation paths between said one or more transmitters and said plurality of receivers, wherein said weighted combinations are formed in consideration of the propagation paths such that, at each receiver, the information signals not intended for the receiver tend to cancel in free space, and the information signals intended for the receiver tend to add in free space; and
coherently transmitting said transmit signals from said one or more transmitters to said plurality of receivers. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
-
-
41. A method of reducing interference at one or more receivers, the method comprising:
-
pre-filtering information signals for one or more receivers using channel estimates representing propagation channels between two or more transmitters and said one or more receivers to form two or more transmit signals, such that said transmit signals combine in free space at said one or more receivers to reduce interference between information signals; and
transmitting a different one of said transmit signals from each one of said two or more transmitters. - View Dependent Claims (42, 43, 44, 45)
-
-
46. A method of transmitting signals in a wireless communication network from a plurality of transmitting stations to a plurality of receivers, the method comprising:
-
forming a matrix of elements, each element being a multi-valued element describing the propagation path from one of said transmitting stations to one said receivers;
forming an inverse of said matrix comprising an adjoint matrix and a determinant;
determining the frequency response from a signal input in said communications network to a receiver for which the signal applied to said signal input is intended, assuming said inverse matrix is used far filtering end combining said applied signals to obtain signals for transmission from respective transmitting stations;
forming said applied signal based on information to be transmitted to said intended receiver and said frequency response so that the information is coded in said applied signal to produce a spectrum of the applied signal that has low energy at frequencies where said frequency response is indicative of high net transmitted signal power attenuation of the total power transmitted from said transmitting stations in reaching said intended receiver and high energy at frequencies where said power attenuation is low. - View Dependent Claims (47, 48, 49)
-
-
50. A wireless communication network comprising:
-
a transmitter operative to transmit a plurality of transmit signals to a plurality of receivers; and
a transmit processor operative to form said transmit signals as weighted combinations of individual information signals intended for respective ones of said plurality of receivers by weighting said information signals using channel estimates representing propagation channels between said transmitter and said receivers;
wherein said weighted combinations are formed in consideration of the propagation channels such that, at each receiver, the information signals not intended for the receiver tend to cancel in free space, and the information signals intended for the receiver tend to add in free space. - View Dependent Claims (51, 52, 53)
-
-
54. A wireless communication network comprising:
-
a plurality of transmitters operative to transmit a plurality of transmit signals over different propagation channels to one or more receivers; and
a transmit processor operative to form said plurality of transmit signals by pre-filtering one or more information signals intended for said one or more receivers using channel estimates representing propagation channels between said transmitters and said one or more receivers;
wherein said transmit signals are formed by pre-filtering in consideration of the propagation paths such that, at each receiver, the information signals not intended for the receiver tend to cancel in free space, and the information signals intended for the receiver tend to add in free space. - View Dependent Claims (55, 56, 57, 58, 59, 60, 61, 62, 63)
-
Specification