Abstract: A method of, and receiver for minimising the effects of carrier phase rotation to received Orthogonal Frequency Division Multiplex (OFDM) signals, comprises frequency down converting received signals to baseband, digitising the down converted signals (x(t)), correcting for the frequency offset in the digitised baseband signals by multiplying the digitised signals with a correction signal (c(t)) which is applied symmetrically about the symbol in order to minimise the phase rotation error. The corrected signal (xadj(t)) is transformed in a FFT (26) from the time domain into the frequency domain in order to avoid inter-carrier interference and applied to a demodulator (28) for recovering the symbol values.

Abstract: A receiver comprises an adaptive filter (22) having an input for a digitized input signal, means (30) for storing a pre-designed filter characteristic, means (26) for analyzing a digital representation of the input signal to determine a desired position of the filter characteristic to match the system requirements, and means (28) for adapting the stored pre-designed filter characteristic in the frequency domain and/or the time domain to match the system requirements and for transforming the adapted filter characteristic to the time domain to update coefficients for the adaptive filter and for loading updated coefficients into adaptive filter. The updating of the coefficients may be done periodically. The adaptation may be one or more of adjusting bandwidth, frequency shift and, in the case of a bandpass characteristic, superimposing characteristics.

Abstract: A method of operating a wireless network comprising a plurality of wireless terminals and optionally a base station uses a transmission frame (300) including an association section (310) for use by wireless terminals wishing to join the network. A variable number of association sections (310) is scheduled in response to operating characteristics such as the load on the network or the presence of a high security application on the network.

Abstract: A frequency offset diversity receiver comprises a first RF receiver branch (10) and a second RF receiver branch (12), an RF signal combiner (14) having first and second inputs (11,13) and an output, the first and second receiver branches being coupled to the first and second inputs (11,13), respectively, frequency shifting means (26) in the second receiver branch (12) for shifting a received signal frequency by at least one channel bandwidth, an intermediate frequency (IF) stage (28,30) coupled to the output of the signal combining means (14) for converting the combined RF signal to baseband, frequency demultiplexing means (36) for recovering the baseband signals corresponding to the RF signals received by the first and second receiver branches (10,12) and a baseband signal combiner (42) for combining the demultiplexed signals to provide an output signal (44).

Abstract: A method whereby a mobile terminal (MT) operating in a wireless local area network (WLAN), for example HiperLAN2, can effect antenna diversity. The mobile terminal which has at least two antennas (24, 26) monitors downlink fields in successive time frames in a time division radio transmission for indications of when downlink message signals are to be sent to mobile terminals other than the one effecting the monitoring and determines from the indications when there will be in the time frame a time period of sufficient duration for the mobile terminal to effect antenna diversity measurements. The mobile terminal measures in the selected time period the quality of signal reception by each of the at least two antennas and selects the one of the said at least two antennas providing the better (or best) quality of signal reception.

Abstract: In a radio communication system comprising a plurality of stations (100a,100b,100c) operating in a peer-to-peer mode, each station stores information relating to the transmission parameters of other stations. Such information may include the frequency offset and received signal strength of signals from the other stations. One station acts as central controller and allocates time slots for transmission from a first station (100a) to a second station (100b). Before the first station (100a) receives a signal from the second station (100b) it makes initial adjustments to its receiver circuitry depending on the stored information about previous signals received from that station (100b). This simplifies the task of adjusting the receiver circuitry during the preamble of the signal transmitted by the second station (100b).

Abstract: A method of operating a wireless network comprising a plurality of public wireless terminals and private wireless terminals, and optionally a base station uses a transmission frame including a control section which may schedule encrypted communication between private wireless terminals and unencrypted communication between public wireless terminals and between public and private wireless terminals. Wireless terminals may join the network as private or public terminals.