Enable In-Band Full-Duplex Communication: a) Backscatter Modulation, b) Self-Interference Cancellation

One key limit to spectrum utilization efficiency involves the current practice of half-duplex com- munication, in which a node either transmits or receives a signal in a single channel usage. Frequency Division Duplex (FDD) and Time Division Duplex (TDD) are the two most commonly used techniques. Contrary to FDD and TDD, in in-band full-duplex (IBFD) communication systems, we can transmit and receive at the same frequency bandwidth, simultaneously. IBFD communication systems are one of the most promising ideas for the next-generations of wireless networks. IBFD communications have the potential of doubling the spectrum efficiency of communication systems as well as eliminating hidden terminals and the need of duplex filters, improving fairness, and network latency. However, the major challenge of IBFD systems is reducing self interference signals, that are imposed on the received (Rx) signals by the transmitted (Tx) signals. In this matter, I proposed a new IBFD at end-user, which use backscatter modulation concept to prevents from having any self-interference signals, called ReflectFX. ReflectFX offers a new concept for two-way wireless communication: rather than avoiding self inter- ference as in half-duplex, or combating self interference as in conventional IBFD, nodes will re-use the received radio-carrier waves to transfer information. The electromagnetic waves are modulated and reflected by the same antenna that receives them. Since the backscattered electromagnetic waves ex- perience the free path loss twice, the communication range will be limited to short rang applications. However, the transmission range of ReflectFX can be improved by adding negative resistance to the end-user load. By deriving an expression for the overall achievable throughput and ergodic capacity of ReflectFX, it can be shown that ReflectFX outperforms both conventional full-duplex and half-duplex.