Blind Known Interference Cancellation Zhang Shengli (Shenzhen University) 2012. 1.12 Good morning every one, I am happy to have this opportunisty to share my latest research result. Blind known interference cancellation. This paper has been accpeted by JSAC with minor revision and it can be accessed on Arxiv.

Background Analog network coding Software defined radio help us find new research problems Most of us believed that Analog network coding is simple to implement. When we try to implement ANC, However, we found that it is not a easy task. The Qustion is how to cancel the known interference at the end node. We then decided to work on it.

Known Interference Successive interference cancellation Relay networks Over hearing Then we made a simple survey and found that known interference does exist in many wireless systems. The most famous example is the successive interference cancellation. In SIC, we fist detect one layer signal. Now, this layer signal becomes the known interference and need to be cancelled from the received signals. In one way relay channel, the signal transmitted by the relay is known, is interference to the source. In some Ad hoc networks, some node can overhear other link’s transmission and the overheared packet may help to change later interference to known interference. Our survey found that there is no satisfactory solutions for this problem.

Traditional Cancellation Two Steps: Interfering channel estimation Subtracting Interference Obstacle: channel estimation Cooperation design in ANC paper Cooperation cost Direct estimation with interference Bad performance Non-coherent detection 3dB performance loss

BKIC(1) We then proposed a new algorithm, Blind known interference cancellation. Consider a general receiver, the BKIC module may be inserted as in the figure.

BKIC(2) Step 1: Step 2 (critical step): For BKIC module, the processing includes two steps. In the first step, we cancel the interference based on the fact that the channel between adjacent symbols is almost the same. We use a weighted sum to cancel the interference. The first step looks simple. The most critical step in BKIC is the second step to recover the target signal from the interference-free signal.

Recovering Scheme1 Straightforward way Equivalent to traditional cancellation

Recovering Scheme2 Real-valued BP

Multipath Case Scheme 1: cancel all the paths of the interference with complex RBP in one cycle To be done Scheme2: cancel each path one by one

Performance Flat fading

Performance Flat fading

Performance Time selective fading

Performance Frequency selective fading

Performance Frequency selective fading

Conclusion and Future Work BKIC is a novel algorithm for a mature problem It’s of great practical interest and it also needs more theoretical study In the future, we may focus on its application in different areas and its implementation with SDR.