Nordic Semiconductor Asa

Kjell Östman

Hannu Talvitie

Olli Närhi

Yrjö Kaipainen

Mika Salmi

Juha Heikkilä

Tommi Kangassuo

A radio receiver tunes a radio channel by generating a periodic signal, mixing the periodic signal with received radio signals and passing the mixed signal through a channel filter that has a passband that corresponds to the bandwidth of the tuned channel. The receiver receives allocation information identifying a set of subcarriers in the tuned channel on which to receive an OFDM data signal. It uses this information to receive the OFDM data, modulated on the allocated subcarriers. When the allocated subcarriers span an allocated frequency range that is less than the width of the tuned channel and that is offset from the centre of the tuned channel in an offset direction, the receiver offsets the channel filter from the centre of the tuned channel in the offset direction such that the channel filter passes i) said OFDM data signal, ii) an in-allocation reference signal, and iii) an out-of-channel reference signal. The receiver uses both reference signals to calculate a channel estimate for a subcarrier within the tuned channel.

OFDM channel estimation

A radio receiver of a radio communication system is configured to tune to a radio channel by generating a periodic signal, mixing the periodic signal with radio signals received from a radio transmission system and passing the mixed signal through a channel filter. The radio receiver receives, from the radio transmission system, an OFDM data signal modulated on a set of OFDM subcarriers within the tuned channel. The channel filter has a passband that is wider than the channel bandwidth of the tuned channel such that the filter passes i) said OFDM data signal, ii) an in-channel reference signal, and iii) an out-of-channel reference signal. The radio receiver comprises channel estimation logic configured to use both reference signals to calculate a channel estimate for an OFDM subcarrier within the tuned channel.

A method of operating a radio receiver arranged to receive a plurality of data symbols transmitted on one of a predetermined set of frequencies. The method comprises receiving a first set of data symbols at a first transmission frequency. The first set of data symbols comprises a message indicating a first frequency sub-set. A synthesiser is calibrated for the one or more frequencies in the first frequency sub-set. A second set of data symbols transmitted on at least one of said one or more frequencies from the first sub-set is received. It is determined from the second set of data symbols whether a network quality metric exceeds a threshold. The synthesiser is calibrated for one or more frequencies in a second frequency sub-set when the network quality metric exceeds the threshold. The second sub-set comprises frequencies that are not in the first sub-set.

Calibration of a synthesiser in a radio receiver

A radio transceiver comprises one or more hardware resources, e.g. a processor; memory; a peripheral device; an algorithmic hardware accelerator; and/or a radio frequency component. A cellular communication radio is operable in an active mode in which it has access to the one or more hardware resources for transmitting and/or receiving cellular communication signals, and an inactive mode in which it does not. A global navigation satellite systems radio, arranged to use the one or more hardware resources to receive positioning signals, has access to the one or more hardware resources only when the cellular communication radio is operated in the inactive mode.

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Trondheim, Norway

Kjell Östman