Abstract: A high fidelity current dumping audio amplifier in which for achieving the best performance are combined the feedforward error correction and the negative feedback. The principle of feedforward error correction in a balanced bridge in A.C. is used, including the whole audio frequency amplifier, combined with a classical negative feedback that includes the items of the amplification chain likely to introduce distortions. The amplifier can be built in a current amplifier structure or in a voltage amplifier structure. The current amplifier structure contains an operational amplifier used as a voltage-current converter and signal de-phasing, two low power symmetrical current amplifiers operating in “A” class with a current mirror structure and a power stage in “B” class, with no quiescent current. The voltage structure of the amplifier contains an operational voltage amplifier, a low power amplifier operating in “A” class, and a power stage operating in “B” class.

Abstract: Schemes for combining channel-estimates from different OFDM frames after compensating for changes in receiver-transmitter characteristics.

Abstract: A station for accessing the resources of an access point in a wireless network, the station including a transmitter that is arranged to formulate probe requests and a transmit chain that is arranged to transmit probe requests on multiple channels of the access point simultaneously, wherein the probe requests are configured to elicit responses from the access point.

Abstract: A signal quality estimator for estimating the quality of signal reception in a signal receiver, the signal quality estimator comprising: a first filter for filtering a signal received by the receiver to isolate a frequency band therein; and a signal analyzer for forming an indication of the degree to which the amplitude of the signal in that frequency band varies over time, to serve as an estimate of the quality of signal reception in the receiver.

Abstract: A high fidelity current dumping audio amplifier in which for achieving the best performance are combined the feedforward error correction and the negative feedback. The principle of feedforward error correction in a balanced bridge in A.C. is used, including the whole audio frequency amplifier, combined with a classical negative feedback that includes the items of the amplification chain likely to introduce distortions. The amplifier can be built in a symmetrical or in a asymmetrical structure. The symmetrical structure of the amplifier contains an operational amplifier used as a voltage-current converter and signal de-phasing, two low power symmetrical amplifiers in “A” class with a current mirror structure with local feedback and a power stage in “B” class, with no quiescent current. The asymmetrical structure of the amplifier contains an operational amplifier, a low power amplifier in “A” class, and a power stage in “B” class.

Abstract: Improved power control methods and power control systems are described wherein received RSSI values are processed to generate a power control signal which may be used by a link manager, or other element in a receiving station, to determine whether to send a power control message to the transmitting station. The method used to process the received RSSI values is dependent upon a value of the power measurement, for example, the method may involve a comparison between the value of the power measurement and a value of the power control signal. In another embodiment, the received RSSI values may be converted to power values and then smoothed using a filter.

Abstract: A method for transmitting data over a network in which multiple transmission conditions can be used for transmitting data, the method comprising selecting a transmission condition to be used when transmitting data over the network, said selection being made in dependence on a predetermined preference distribution that for each of the multiple transmission conditions defines a probability of that transmission condition being selected, using the selected transmission condition when transmitting data over the network and determining the success of the transmission and updating the preference distribution in dependence on the success of the transmission and thereafter selecting a transmission condition for transmitting data over the network in dependence on the updated preference distribution.

Abstract: A method for transmitting data over a network in which multiple transmission conditions can be used for transmitting data, each transmission condition being associated with a rating indicative of how successful previous data transmissions using that transmission condition have been, the method comprising using a selected transmission condition when transmitting data over the network and updating the rating associated with the selected transmission condition in dependence on the success of that transmission, updating the ratings associated with the transmission conditions other than the selected transmission condition by adjusting each of those ratings by a predetermined amount and selecting a transmission condition in dependence on the updated ratings.

Abstract: An interference rejection unit for at least partially rejecting a narrowband interferer from an input signal, the unit comprising: an interferer detector for detecting the phase of an interferer in the input signal; a signal generator for generating a cancellation signal in dependence on the phase detected by the interferer detector; and a signal combiner for combining the input signal with the tone cancellation signal to generate an output signal in which the interferer is at least partially cancelled from the input signal.

Abstract: An interference rejection unit for at least partially rejecting a narrowband interferer from an input signal, the unit comprising: an interferer detector for detecting the phase of an interferer in the input signal; a signal generator for generating a cancellation signal in dependence on the phase detected by the interferer detector; and a signal combiner for combining the input signal with the tone cancellation signal to generate an output signal in which the interferer is at least partially cancelled from the input signal.

Abstract: A signal quality estimator for estimating the quality of signal reception in a signal receiver, the signal quality estimator comprising: a first filter for filtering a signal received by the receiver to isolate a frequency band therein; and a signal analyzer for forming an indication of the degree to which the amplitude of the signal in that frequency band varies over time, to serve as an estimate of the quality of signal reception in the receiver.

Abstract: Improved power control methods and power control systems are described wherein received RSSI values are processed to generate a power control signal which may be used by a link manager, or other element in a receiving station, to determine whether to send a power control message to the transmitting station. The method used to process the received RSSI values is dependent upon a value of the power measurement, for example, the method may involve a comparison between the value of the power measurement and a value of the power control signal. In another embodiment, the received RSSI values may be converted to power values and then smoothed using a filter.

Abstract: A method for transmitting data over a network in which multiple transmission conditions can be used for transmitting data, the method comprising selecting a transmission condition to be used when transmitting data over the network, said selection being made in dependence on a predetermined preference distribution that for each of the multiple transmission conditions defines a probability of that transmission condition being selected, using the selected transmission condition when transmitting data over the network and determining the success of the transmission and updating the preference distribution in dependence on the success of the transmission and thereafter selecting a transmission condition for transmitting data over the network in dependence on the updated preference distribution.

Abstract: A method for transmitting data over a network in which multiple transmission conditions can be used for transmitting data, each transmission condition being associated with a rating indicative of how successful previous data transmissions using that transmission condition have been, the method comprising using a selected transmission condition when transmitting data over the network and updating the rating associated with the selected transmission condition in dependence on the success of that transmission, updating the ratings associated with the transmission conditions other than the selected transmission condition by adjusting each of those ratings by a predetermined amount and selecting a transmission condition in dependence on the updated ratings.