A compensation scheme to allow full duplex operation in the presence of highly nonlinear microwave components for 4 G systems

Current and future generation radio transceivers have to share spectrum in increasingly tight frequency space. Front end nonlinearities create spectral expansion which leads to radio interference in adjacent bands. The problem is greatly exacerbated for full duplex receivers with closely spaced Tx/Rx channels. This work proposes a novel radio architecture that can take care of out of band (OOB) emissions and allow interference free full duplex radio operation using appropriate nonlinear interference cancellation schemes. We propose that nonlinear operation and the resulting spectral re-growth can be handled without incurring any extra analog hardware in the RF front-end. This is accomplished at the cost of extra base band DSP workload. We then demonstrate that such an operation is indeed possible by setting up an experiment with a commercial RF front end chipset. This can possibly lead to a wide range of applications where interference cancellation can either facilitate or enable radio co-existence in upcoming multi-radio transceivers.