However, during this computation the transmit weight generator must take into account the gain and phase differences between the uplink and downlink propagation channels where the channels include both the air path from and to a subscriber unit and the variation among the different signal parts within the receive RF electronics and also within the transmit RF electronics. The use of antenna arrays in such a communication station provides for antenna performance improvements over the use of a single element antenna. For example, the downlink calibration burst may consist of pure tones. It is known that compensation can be achieved by convolving each of the M signals received or transmitted by the antenna elements by a calibration function i. In step , it is determined whether or not the demodulated bits are for a standard TCH burst.
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As a compact representation, in this description, the uplink and downlink channels thus are mathematically described by M-dimensional complex valued vectors denoted a rx and a txrespectively, where M is the number of elements in the base-station antenna arrayand sswitch each element in the vector represents the path associated with one of the antenna elements in array A typical subscriber unit usually has at most a few antennas one antenna  in the WLL system on which the invention preferably is implementedwhich limits the information that is available for downlink signature estimation.
In the preferred embodiment, the subscriber unit transmits standard TCH bursts, and therefore the default TCH demodulation method of the base station can be used for this purpose. Similarly, on the downlink, there are M signal paths, one from each of the M inputs of transmit signal processor to the subscriber unit.
Calibration calls can be initiated on any carrier and any time slot while the base station is servicing standard traffic channel TCH calls on other carriers and time slots. Wireless communication device and wireless communication method, and computer program.
The call termination  preferably includes a disconnect command from the base station followed by a release message from the subscriber unit. In an FDD system the relation between the uplink and downlink propagation factors may be more complicated, and can still be determined.
In alternate embodiments, other sequences can be used, and how to modify the method to use other sequences would be clear to one of ordinary skill in the art. Wide inventory, custom solutions, flexible rental terms.
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The accuracy of the downlink channel estimate for the two-tone method improved implementation including timing alignment correction was measured by performing experiments using the PHS base station and a subscriber unit from the WLL system used in the preferred embodiment. Multipath channel emulator formed by building rotary reflector in metal closed space.
For transmit calibration, an input transmit signal is inputted into each antenna element one antenna at a time. The DSP program implementing channel identification processor may be summarized as follows:.
A WLL base station into which some aspects of the present invention are incorporated is described in U. Note that in the description below, the phase and magnitude distortions that occur in the various signal paths are described by the amplitude and phase, respectively, of a single complex valued number, so that a calibration for a one-to-M or M-to-one system is described by a M-dimensional complex valued vector.
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In an alternate embodiment, a local sense antenna at the satellite’s communication station is used to sample outputs of the transmit antenna elements.
In addition, there are RF propagation effects that take place on the micrometics between the subscriber unit and a particular receiving antenna, such effects including without limitation the path loss, fading and shading effects, multipath, and near-field scattering, and these effects may be different from antenna element to antenna element. Different pre-defined calibration signals may be used.
Estimate the uplink channel spatial signature a  rx. Vincent Electronics Livonia, MI Provides test equipment repair, product design, and prototype services. Several features of Wachs’ system are of 27.
The 21 of 2wherein the uplink calibration signals are idle traffic waveforms. Radio equipment, transmission reception directivity control method, and transmission reception directivity control program.
Method and apparatus for semi-blind transmit antenna array using feedback information in mobile communication system. One also may generalize the method to deal with more than two antennas at a time.
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The required correction coefficients for each chain are determined from the measured amplitude and phase data, and each individual element chain is individually compensated to remedy the amplitude and phase errors.
It would be clear to those of ordinary skill in the art that the adaptive smart antenna processing, including any weighting in amplitude and phase, may alternatively be carried out in some other band, for example, in intermediate frequency or in the passband. Thus, in the preferred embodiment, the uplink and downlink factors are measured over consecutive receive and transmit slots that are separated by a relatively short time interval.
In the first experiment, the data bus indicates to the remote terminal to send a known signal to the base station. The error and variance when using these two tones were larger that when using the frequencies used for FIG. Channel identification unit uses the transmitted signal estimate and received signalswhich are the input and output signals respectively, of the uplink channel, to estimate the underlying spatial signature Thus, communication from the remote terminal to the base station is called the uplink, and communication from the base station to the remote terminal is called the downlink.
The internal structure of the transmit weight generator  is depicted in FIG. The relative downlink signature for one of the antenna elements, say the second antenna element, with the first antenna element as the reference, is computed as the second cross correlation divided by the first cross correlation. If you’re looking for manuals, you’ve come to the right place.
Known methods for determining array calibrations each have one or more associated drawbacks.