FOR CANCELLING CO-CHANNEL INTERFERENCE AND IMAGE-BAND INTERFERENCE

We propose an architecture which reduce the circuit size to concurrently cancel co-channel interference and image- band interference. We adopt analogue Hilbert transformers to cancel image-band interference and adaptive array antennas to cancel co-channel interference. Furthermore, we can miniaturize the receiver by mixing all signals at the IF stage. We also show performance of the proposed system by computer simulation. As a result, image-band interference caused by some imperfection of Hilbert transformer can be completely canceled. Moreover, co-channel interference can be simultaneously canceled. I. INTRODUCTION Various radio transmission systems have recently been com- mercialized. Basically, each of these systems uses different frequency band. Hence, frequency bands for new radio systems become limited. Therefore, it is necessary to increase the frequency utilization efficiency of radio systems as much as possible. For this purpose, mobile transmission systems adopt cellular concepts. In cellular systems, a signal transmitted from a cell can be propagated to another cell. If the two cells use the same frequency, the transmitted signal turn out to interfere with signals from the other cell and transmission performance is impaired. Moreover, when several radio systems are allowed to share the same frequency band such as ISM (Industrial,