Abstract: A method for combining a reference signal with a data signal is disclosed. A multiplexed data signal is received. A demultiplexer is applied to the data signal. The data signal is encoded. A linear transformation is applied to the data signal which projects the data signal into a null-space of a plurality of reference signals. The encoded data signal is summed with the reference signal. The summation of the data signal and the reference signal is orthogonally modulated. The combined reference signal and data signal is transmitted to a receiver.

Abstract: Embodiments of the present invention comprise systems and methods for providing transmission priority to stations in a wireless LAN system.

Abstract: A scheduler for providing quality of service in a local area network, wherein the local area network includes a plurality of stations, and wherein data flow moves over the network in superframes, includes a mechanism for governing channel resources in the local area network, including a transmit specification controller for granting a transmit specification to a data flow from one station on the network to another station on the network; and a TXOP mechanism for terminating transmits opportunities for stations which have successfully completed data transmission, thereby changing the length of a superframe.

Abstract: In a direct sequence spread spectrum data communication system an information bit is mixed with a pseudorandom noise or spreading code to produce modulated codeword for transmission. A method of bandwidth efficient M-ary phase shift key modulation encoding at least 16 bits of data to a single codeword is disclosed for extending the data rate of a spread spectrum system. Interoperability with legacy devices is maximized by maintaining structural similarity between the modulated waveforms of the extended data rate and legacy systems.

Abstract: An apparatus and method of automatic gain control (AGC) useful for a detector of a digital radio providing rapid settling and minimal distortion is described. The automatic gain control includes a plurality of modular AGC elements each having a unique bias. The AGC elements may also be switched from an open loop operating mode with a unique initial gain voltage to a closed loop operating mode. A matched filter is applied to the output of each of the AGC elements to filter out all but the signal constituents that match the reference symbol. The output of the matched filters having the greatest signal to noise ratio is the selected as the detector output. The output with the greatest signal to noise ratio corresponds to the output of the AGC element that has settled with the least distortion.

Abstract: A scheduler for use in an LAN for allocating transmission opportunities includes a scheduling policy mechanism for assigning flow-to-transmit opportunities to the stations based on network constraints; and an optimization mechanism for looking ahead a number of superframes, NL, to determine an optimal time to assign a transmit opportunity to a station. A method of allocating transmission opportunities includes assigning flow-to-transmit opportunities to the stations based on network constraints; and looking ahead a number of superframes, NL, to determine an optimal time to assign a transmit opportunity to a station.

Abstract: A scheduler for providing quality of service in a local area network, wherein the local area network includes a plurality of stations, and wherein data flow moves over the network in superframes, includes a mechanism for governing channel resources in the local area network, including a transmit specification controller for granting a transmit specification to a data flow from one station on the network to another station on the network; and a TXOP mechanism for terminating transmits opportunities for stations which have successfully completed data transmission, thereby changing the length of a superframe.

Abstract: A receiver has been provided, with a pre-whitening filter, to improve the probability of recovering a received signal in the presence of colored noise. Colored noise can be multipath or transmission signals to other receivers in the same spectral bandpass. The receiver system uses colored noise statistics to provide an optimal estimation in the despreading of the transmitted information. Auxiliary systems in the receiver cancel the pilot, or system acquisition symbols, improving even further the probability or recovering information in the despreading of transmitted signal. A method of pre-whitening a signal received in the presence of colored noise is also provided.

Abstract: In a direct sequence spread spectrum data communication system an information bit is mixed with a pseudorandom noise or spreading code to produce modulated codeword for transmission. A method of bandwidth efficient M-ary phase shift key modulation encoding at least 16 bits of data to a single codeword is disclosed for extending the data rate of a spread spectrum system. Interoperability with legacy devices is maximized by maintaining structural similarity between the modulated waveforms of the extended data rate and legacy systems.

Abstract: A wideband receiver automatic frequency control (AFC) system which combines multipath or diverse antenna signals, before the carrier frequency error is determined, is provided herein. Rather than independently calculating the frequency error of each transmission path, frequency error is calculated after the multipath signals are summed together. Thus, only a single frequency detector circuit is required. The resulting automatic frequency control system has the accuracy of a system which combines the independently calculated frequency errors, with fewer steps of computation required. A method for combining multipath signals to calculate an average AFC frequency error is also provided.

Abstract: A wideband CDMA receiver system to accept messages from asynchronously transmitting base stations is provided. The base station transmission to each receiver includes a perch channel and at least one traffic channel. Although all the channels typically include pilot symbols for the purpose of demodulating the information symbols of the channel, the pilot channel includes a higher proportion of pilot symbols to information symbols. Therefore, a perch channel based timing and estimation system is inherently more accurate. In addition, the perch channel is generally transmitted at higher power levels than a traffic channel, and the resulting, higher, signal to noise ratio signal also improves the accuracy of the timing and channel estimation. Based on the timing derived from the perch channel of a first base station, the receiver can set the timing of the traffic channel transmissions from a second base station, to more closely match the timing of traffic channel transmissions from the first base station.

Abstract: A wideband receiver, including a time-varying finite impulse response (FIR) filter, has been provided to combine multipath communications of data in response to pilot channel timing information. The time-varying FIR processes the multipath communications through independent signal paths. Each signal path includes a variable delay circuit and a variable gain circuit. The delay of each separate signal path is adjusted and made equal in response to the pilot channel timing information. Likewise, the gain of each signal path is adjusted in response to pilot channel gain information to maximize the signal to noise ratio of the combined signal paths. The separate signal paths are then summed in a combiner circuit. The time-varying FIR permits the data communication to be summed either before, or after demodulation. A method of combining multipath communications using a time-varying FIR is also provided.

Abstract: An arrangement for detecting quadrature phase errors introduced by a synchronous demodulator between the two quadrature channels, in-phase (I) and quadrature-phase (Q), of a synchronous demodulator, and for correcting for such detected quadrature phase errors without the need for high data sampling rates. During an initial test period, a periodic symmetrical test signal of known frequency is introduced into the synchronous demodulator. During the test period, the output of the synchronous demodulator is integrated over an integer multiple of periods to detect the quadrature phase error introduced by the synchronous demodulator, and an error signal is generated representative of the detected quadrature phase error. During a following period of operation of the synchronous demodulator, the in-phase (I) and quadrature-phase (Q) signals produced by the synchronous demodulator are applied to a quadrature phase error correction network, along with the generated quadrature phase error signal.

Abstract: A method and apparatus that uses heat to bond a polyethylene sleeve (having pockets that contain negative strips) to the back non-light sensitive surface of a photographic paper coated with polyethylene. A positive image or index print of the information stored on the negative appears on the front light sensitive, image bearing surface of the photographic paper.