A method of, and receiver for, cancelling interfering signals

Abstract

A method of, and receiver for, cancelling an unwanted first signal having a bandwidth at least a part of which overlies the bandwidth of a wanted second signal, the bandwidth of one of the first and second signals being greater than that of the other. The method comprises receiving the first and second signals(10, 12) and respectively frequency down converting(18,22,26 and 20,24,28) the first and second signals to provide first and second low frequency signals. The first and second low frequency signals are digitised using synchronised ADCs(30,32) to provide respective first and second digitised signals, the wider bandwidth signal being digitised at a higher sampling rate and the lower bandwidth signal being digitised at a lower sampling rate. The sampling rate of one of the first and second digitised signals is adjusted(44) to be the same as the other of the first and second digitised signals. Thereafter the frequency of the unwanted signal is shifted(46) to be in the same relative position with respect to the wanted signal as it appeared in the received signal. An output signal is derived by obtaining the difference(40) between the wanted and unwanted signals. In a refinement of the basic method the unwanted signal from the respective ADC is cleaned-up by demodulating it(52) and modulating it(54) which gives the benefit that when subtracting one signal from the other, the section of the wanted signal under the interferer is left intact.

Description

technical field [0001] The invention relates to a method and a receiver for canceling interfering signals. The present invention applies particularly, but not exclusively, to the cancellation of received narrowband interfering signals (such as Bluetooth, registered trademark ( RTM ) signal and vice versa. The present invention can be applied to multi-mode operation and can support Multiple Input Multiple Output (MIMO). Background technique [0002] The prior art discloses many methods for canceling unwanted interfering signals present in the bandwidth of the wanted signal. As an example, EP-A1 1 176 731 discloses a method for detecting narrowband interfering signals (such as Bluetooth RTM ) method for interference cancellation, the broadband communication device is used to receive signals transmitted according to IEEE 802.11, IEEE802.11 or IEEE 802.15.3. The architecture of the device includes Bluetooth RTM A receiver and a broadband receiver having an input coupled to ...

AI Technical Summary

Problems solved by technology

[0004] The disadvantage of the cited interference cancellation technique is that it requires two separate radio receivers to be able to receive a desired wideband signal and an unwanted narrowband signal

Using two separate receivers is relatively expensive and requires a relatively large amount of power, which is a disadvantage in battery-operated devices

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