Patent ID: 11936501
Assignee: NORDIC SEMICONDUCTOR ASA
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 12:
13. A non-transitory computer-readable medium having software stored thereon comprising instructions which, when executed by a processor of a radio receiver, cause the radio receiver to receive an OFDM data signal from a radio transmission system that transmits OFDM data signals over respective channels of a plurality of predetermined radio channels, each channel having a respective channel bandwidth and comprising a respective plurality of OFDM subcarriers, and that transmits predetermined reference signals at predetermined times on a reference-signal set of the respective plurality of OFDM subcarriers, wherein:
the radio receiver comprises said processor, a local oscillator and a channel filter;
the radio receiver is configured to tune a channel of the plurality of predetermined radio channels by:
controlling the local oscillator to generate a periodic signal;
receiving radio signals from the radio transmission system and mixing the radio signals with the periodic signal to generate a mixed signal; and
passing the mixed signal through the channel filter, wherein the channel filter has a passband that corresponds to the channel bandwidth of the tuned channel; and

the radio receiver is configured to receive, from the radio transmission system, allocation information identifying a set of allocated subcarriers, of the plurality of OFDM subcarriers in the tuned channel, on which to receive an OFDM data signal;
the radio receiver is configured to use the allocation information to receive the OFDM data signal, from the radio transmission system, modulated on the set of allocated subcarriers;, and wherein the software comprises instructions for controlling the radio receiver so that:
when the set of allocated subcarriers spans an allocated frequency range that is less than the channel bandwidth of the tuned channel and that is offset from a center of the tuned channel in an offset direction, the radio receiver offsets the channel filter from the centre of the tuned channel in said offset direction by a filter offset amount, such that the channel filter passes i) said OFDM data signal; ii) an in-allocation reference signal of the predetermined reference signals, received on a subcarrier of the set of allocated subcarriers; and iii) an out-of-channel reference signal of the predetermined reference signals, received on an out-of-channel subcarrier of the plurality of OFDM subcarriers that is located outside the tuned channel; and
the processor uses both i) the in-allocation reference signal, and ii) the out-of-channel reference signal, to calculate a channel estimate for a subcarrier of the set of allocated subcarriers within the tuned channel.