Our web-site is updated daily and represents our current inventory of over 1, items. A method and apparatus for estimating the downlink signature for a remote transceiver which is part of a wireless communication system that includes a main transceiver for communicating with the remote transceiver. Time coordinated base station and antenna array for integer cycle and impulse modulation systems. Note that the signature  can be determined according to Eq. This minimization can be carried out using standard methods, for example by performing a grid search over D to approximately locate the global minimum, and then performing a gradient descent to refine the estimate. Communication channel calibration with nonvolatile parameter store for recovery.
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Cross-correlate the first half of the received sequence with siwtch first half of calibration sequence  1: Another feature of the invention is determining spatial signatures that enable using a calibrated transmit weight vector, the transmit weight vector essentially determined from a receive weight vector, the calibrating taking into account differences in electronics paths and RF propagation paths. It is known that compensation can be achieved by convolving each swigch the M signals received or transmitted by the antenna general-phrpose by a calibration function i.
Thus, on the uplink there are M 2117 paths from a subscriber unit, one to each of the M inputs of the receive signal processor Calibration and repair of our electronic instruments is performed in our in house NIST traceable calibration lab. Calibration method to achieve reciprocity of bidirectional communication channels. Mutual coupling based calibration technique for structurally deformed phased array apertures.
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Therefore, while the description herein is in terms of weights and spatial processing, the scope is intended to include spatio-temporal processing. Note that while only one downlink and one uplink additional step is shown dotted, it is to be understood that this represents as many additional bursts as there are additional subarrays to be calibrated.
The method of 6wherein the downlink calibration waveforms are transmitted during silent periods. There also is a need in the art for a simple calibration technique that only uses existing base station electronics and does not 127 special calibration hardware.
Mathematically, this symmetry may be stated as the uplink and downlink weight vectors substantially satisfying the equation. Multi-connection, non-simultaneous frequency diversity swktch radio communication systems.
The antenna array typically is at the base station. The microndtics from the antenna general-purpse are then processed by the receive signal processor which is made up of one or more digital signal processing devices DSPs programmed to carry out the functions of the elements, and Calibration factors for each antenna element are determined as a function of the associated transmit electronics chain and receiver electronics chain transfer functions.
As such sums occur naturally in a multiuser communication system with frequency reuse, a sum of waveforms conforming to an air interface standard is also considered to conform to an air interface standard for the purpose of this description.
Between each base station antenna element an element in  and the antenna of the subscriber unit, there is a complex valued number that describes the general-purpsoe and amplitude distortion that occurs in a baseband signal due to the RF propagation effects on the uplink and on the downlink.
This sending is shown as step  for the first downlink calibration burst and as dotted line for those implementations that use additional bursts, for example for the remaining subarrays. Method and apparatus for transmitting data in a time division duplexed TDD communication system. The result of applying the weighting generates a baseband signal from the particular subscriber unit.
Normal traffic burst signals are obtained from telephony interface unit via a vocoder DSP The method of 1wherein the downlink signature is determined in relation to a reference antenna element of the transmit antenna array, and wherein the downlink calibration waveforms are selected so that the signals transmitted from each transmit antenna elements are substantially orthogonal. In the preferred embodiment, the subscriber unit has sufficient processing power to completely compute the downlink channel estimate, and in this case, the downlink signature related signals are the downlink channel estimate components.
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The receive signal processor includes determining a weighted sum of the complex valued in phase I and quadrature Q antenna signals in an optimal manner where the weighting is in amplitude and phase, and where optimal means that the desired signal components are enhanced by a maximum amount and the non-desired components are suppressed by a maximum amount.
Method and apparatus for semi-blind transmit antenna array using feedback information in mobile communication system. Manufacturing customers in 27 industries as diverse as semiconductor equipment to pet food, use these products which deliver measuring resolution of 0. This may involve measuring the gain and phase differences between the uplink egneral-purpose downlink channels.
Another desirable feature is that the method can be used for signature estimation in order to also account for differences in the RF paths. However, in practice, communication may still be possible. Alternatively, the antenna elements can transmit pure tones with different frequencies orthogonality in the frequency domain.