Abstract: A controlled receive device is disclosed having an amplifier circuit, which receives an input signal, and a control circuit which receives the input signal and outputs a controlled signal to a receiver. The receiver outputs an output signal. A controller varies the gain of the amplifier circuit in response to levels of the controlled signal and the output signal. The control circuit outputs a controlled indicator signal indicative of a level of the controlled signal and the receiver outputs an output indicator signal indicative of the output signal level. The controlled indicator signal and the output indicator signal are compared using comparators, to respective reference or threshold levels for producing control signals used by the controller for varying the amplifier gain.

Abstract: Multiple field units in a CDMA system are synchronized for communication with a base station using a shared forward and reverse link channel. Each field unit is assigned a time slot in a forward link channel to receive messages from the base station. Likewise, each field unit is assigned a time slot on a common reverse link channel for transmitting messages to the base station. Timing alignment among each of many field units and the base station is achieved by analyzing messages received at the base station in a corresponding time slot from each field unit. Thereafter, a message is transmitted in a corresponding time slot to a particular field unit from the base station for adjusting its timing so that future messages transmitted from the field unit are received in the appropriate time slot at the base station.

Abstract: In an illustrative embodiment of the present invention, a first channel is allocated for transmitting sporadically generated messages from multiple field units to a base station. The first channel is preferably divided into time slots in which a field unit transmits an access request message to the base station for establishing a communication link. In response to an access request message, feedback information is provided from the base station to multiple field units indicating whether a collision was detected on the first channel for a message transmitted in a previous time slot. In an instance when a collision is detected, the field unit will re-transmit an access request message at a previous power level setting based on a random back off time.

Abstract: A single, common correlation filter (CF) core is provided in a wireless system using CDMA. A plurality of channels with different data rates are provided in the wireless system. The channels provided in the wireless system include the access channel, the maintenance channel, and the traffic channel in which information (e.g., pilot or data symbols or both) is transmitted at the tier 1, tier 2 and tier 3 rates. The data rate for transmitting the information is programmable by digital signal processor (DSP). A user-unique code, such as a PN code, is applied to the information being transmitted in the channels of the wireless system. The information is QPSK modulated and transmitted in any one of the channels at any data rate. The transmitted information is correlated at the smallest data rate (i.e., the tier 1 rate) in the correlation filter (CF) of the wireless system by time multiplexing delayed versions of the PN code to the correlation filter core.

Abstract: A transmitter which includes a quadrature phase shift keying (QPSK) modulator, and a receiver which includes a pilot correlation filter (PCF), a data matching filter (DMF), a timing recovery mechanism, a sampler, and a QPSK demodulator are provided in a wireless communication system. The transmitter transmits a frame of data symbols and pilot symbols to a receiver in a wireless system. The pilot symbols are inserted in the frame at known time intervals. The QPSK modulator modulates the frame of data and pilot symbols. As the receiver receives the frame of data and pilot symbols from the transmitter, the PCF recovers the pilot symbols sent by the transmitter, whereas the timing recovery mechanism tracks the timing of the pilot symbols in the frame. The DMF enhances the multipath response of the frame of data and pilot symbols at the known time intervals of the pilot symbols, and outputs a plurality of enhanced peaks.

Abstract: A technique for efficient implementation of pilot signals on a reverse link in a wireless communication system. An access channel is defined for the reverse link such that within each frame, or epoch, a portion is dedicated to sending only pilot symbols. Another portion of the frame is reserved for sending mostly data symbols; however, within this second portion of the frame, additional pilot symbols are interleaved among the data symbols. The pilot symbol or preamble portion of the access channel frame allows for efficient acquisition of the access signal at the base station, while providing a timing reference for determining the effects of multipath fading. In particular, a pilot correlation filter provides a phase estimate from the pilot symbols in the preamble portion, which is then used to decode the data symbols in the payload portion. An access acquisition portion of the receiver uses the phase estimates provided by the pilot correlation filter to process the output of a data symbol correlation filter.

Abstract: An antenna apparatus for increasing the capacity in a cellular communication system. The antenna operates in conjunction with a mobile subscriber unit and provides a plurality of antenna elements, each coupled to a respective signal control component to provide a weight to the signal transmitted from each element. The weight for each antenna element is adjusted to achieve optimum reception during, for example, an idle mode when a pilot signal is received. The weight values cause the antenna array to create a beam former for signals to be transmitted from the mobile subscriber unit, and a directional receiving array to more optimally detect and receive signals transmitted from the base station. By directionally receiving and transmitting signals, multipath fading and intercell interference are greatly reduced. The weights are adjusted at the transmitting site in accord with signal quality metric information determined at the receiving site.

Abstract: A Rake receiver having fingers is disclosed. The Rake receiver includes frequency discriminators for automatic frequency control and a combiner. Each finger includes a frequency discriminator. The combiner combines outputs from the frequency discriminators to output an average error signal which is fed back to the frequency discriminators for removing frequency offsets from all the fingers. The combiner includes an adder which adds the outputs of the frequency discriminators, and a divide circuit which divides the combined adder output by the number of the outputs which were added together to form the average error signal. The combiner further includes a filter connected between the adder and the divide circuit. In addition, further adders are provided where each of theses adders receives the average error signal and a respective one of the outputs from the frequency discriminators in order to provide an estimate of one of the frequency offsets.