Enabling algorithms and RF circuitry for full duplex communication over arbitrary spectrum fragments

The wireless spectrum is increasingly fragmented due to the growing proliferation of unlicensed wireless devices and piecemeal licensed spectrum allocations. Current radios are ill-equipped to exploit such fragmented spectrum since they expect large contiguous chunks of spectrum to operate on. Stanford researchers have addressed this limitation by designing a new system architecture which provides radios with a general full duplex signal shaping capability, allowing them to exploit the fragmented spectrum. The system has two novel components: a programmable filter engine and a self- interference cancellation technique that enables a radio to simultaneously send and receive over different spectrum fragments. This single cancellation system can cancel the transmitted signal no matter what frequency ranges it is operating on. Thus, a single cancellation system could replace several discrete filtering components and allow for more flexible operations.

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Figure 1 Architecture: This invention exposes a signal shaping API to the PHY/MAC

Stage of Research:
Designed and implemented this system on a Virtex- 6 FPGA based software radio and show via empirical evaluation that it provides seamless signal shaping over fragmented spectrum without any loss of throughput to the higher layers.

On-going Research:
Continuing to evaluate methods to implement this design with a single antenna as well as extend it to MIMO.