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| Remote control holder |
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| Non-telephonic, wireless information presentation device |
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| Electronic equipment control system and control method |
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Statistical calibration of wireless base stations
| Details |
Inventors: Da Torre, Serge Barbosa; Parish, David M.; Kasapi, Athos; Lindskog, Erik D.; Trott, Mitchell D.; Kerr, Adam B.;
Assignee: ArrayComm, Inc. (San Jose, CA)
Primary Examiner: Trinh; Sonny
Assistant Examiner:
Attorney, Agent or Firm: Blakely, Sokoloff, Taylor & Zafman LLP
The present invention allows a radio receiver or a transmitter, with a plurality of antennas configured into an array, to be calibrated. In one embodiment, the method includes receiving a plurality of signals from a plurality of remote transmitters at the antenna array, sampling the signals received at at least two antennas of the array, computing a relative phase and amplitude of the sampled signals for each antenna, and computing calibration coefficients based on the relative phase and amplitude for the plurality of sampled signals from the plurality of remote transmitters for each antenna. |
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DETAILED DESCRIPTION OF THE INVENTION Introduction In one embodiment, the present invention is implemented in a Spatial Division Multiple Access (SDMA) radio data communications system as shown and described further with respect to the FIG.
1.
In such an SDMA system, each terminal is associated with a set of spatial parameters that relate to the radio communications channel between, for example, the base station and a user terminal.
The spatial parameters comprise a spatial signature for each terminal.
Using the spatial signature and arrayed antennas, data can be sent to several different user terminals at the same time using the same radio frequency band.
Conversely, data can be received from several different user terminals at the same time on the same radio frequency band.
In a CDMA system, SDMA can lower the noise floor for subscribers that are spatially separated from one another.
The spatial signatures allow the otherwise colliding or interfering signals to be resolved.
The spatial signatures can include such things as the spatial location of the transmitters, the directions-of-arrival (DOAs), times-of-arrival (TOAs) and the distance from the base station.
Estimates of parameters such as signal power levels, DOAs, and TOAs can be determined using known training sequences placed in digital data streams for the purpose of channel equalization in conjunction with sensor (antenna) array information.
This information is then used to calculate appropriate weights for spatial de-multiplexers, multiplexers, and combiners.
Extended Kalman filters or other types of linear filters, well-known in the art, can be used to exploit the properties of the training sequences in determining spatial parameters.
Further details regarding the use of SDMA systems are described, for example, in U.
S.
Pat.
No.
5,828,658, issued Oct.
27, 1998 to Ottersten et al.
and U.
S.
Pat.
No.
5,642,353, issued Jun.
24, 1997 to Roy, III et al.
The present invention provides for the calibration of multiple antenna base stations by exploiting the signals or the feedback provided by actual remote terminal units (or handsets) of the system being calibrated
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