Mayank Jain, Jung Il Choi Tae Min Kim, Dinesh Bharadia, Siddharth Seth, Kannan Srinivasan, Philip Levis, Sachin Katti, Prasn Sinha MobiCom 2011

Single channel full-duplex

Antenna Cancellation Achieving Single Channel, Full Duplex Wireless Communication [Mobicom’10]

Contributions New full-duplex radio design: signal inversion cancellation Wideband, frequency independent One transmit antenna design Real-time full-duplex MAC layer implementation

Signal Inversion vs. Phase Offset

Phase Offset

Signal Inversion

Signal Inversion vs. Phase Offset

Balun passive cancellation

Balun active cancellation

Digital cancellation Three novel achievements: - Real-time cancellation implementation that runs in hardware - Cancellation implementation can operate on 10MHz signals - Digital cancellation that operates on OFDM signals Digital cancellation has two components: - Channel Estimation >> least squares algorithm - Applying Digital Cancellation >>

Balun + Digital cancellation

Implications to Wireless Networks Breaks basic assumption in wireless Can solve some fundamental problems with wireless networks today: - Hidden terminals - Network congestion and WLAN fairness

Hidden Terminals

Network Congestion and WLAN Fairness

Performance Balun Passive/Active Cancellation

Performance 1 AP with 4 stations without any hidden terminals

Summary Design for real-time full-duplex wireless - Makes full-duplex WiFi possible Made practical using adaptive techniques Rethinking of wireless networks - WiFi: hidden terminals and fairness