Full-duplex wireless communications using off-the-shelf radios: Feasibility and first results

Abstract

Abstract-We study full-duplex wireless communication systems where same band simultaneous bidirectional communication is achieved via cancellation of the self-interfering signal. Using offthe-shelf MIMO radios, we present experimental results that characterize the suppression performance of three self-interference cancellation mechanisms, which combine a different mix of analog and digital cancellation. Our experimental results show that while the amount of self-interference increases linearly with the transmitted power, the self-interference can be sufficiently cancelled to make full-duplex wireless communication feasible in many cases. Our experimental results further show that if the self-interference is cancelled in the analog domain before the interfering signal reaches the receiver front end, then the resulting full-duplex system can achieve rates higher than the rates achieved by a half-duplex system with identical analog resources.

Tunable Frequency-Division Duplex RF Front End Using Electrical Balance and Active Cancellation

“…The dominant limiting factor determining the amount of cancellation is the error vector magnitude (EVM) of the Tx chains. Low cost transceiver hardware has been shown to provide >30 dB of active SIC [9], [33], [34], which is sufficient to increase the isolation in the TX band from as low as 20 dB, to >50 dB, as required.…”

Superimposed signaling inspired channel estimation in full-duplex systems

“…This intuition is confirmed from (16), which indicates that higher values of β are needed at low E b /N 0 to reach a given estimation error. Furthermore, since the lower bound on the estimation error also decreases with N, the minimum value of β found for smaller N can also serve for larger N. Since the experimental results of [5,41] show that the FD communication channel is normally constant for more than N > 128 symbols, we propose to find the minimum β at N = 128 and E b /N 0 = 0 dB. Figure 3 shows the MSE performance of the proposed technique versus β for E b /N 0 = 0 dB, N = 128, and SIR = − 50 dB.…”

“…1 Note that the system model for FD communication in (1) is applicable to per subcarrier communication in orthogonal frequency division multiplexing (OFDM) FD communication [3,5,41]. 2 Note that it may be possible to achieve constellation asymmetry through other means, such as design of irregular modulation constellations.…”

On the Outage Performance of Full-Duplex Selective Decode-and-Forward Relaying

“…In practice, even with recent advances in prototyping full-duplex nodes, all known analog, digital and spatial isolation/cancellation techniques cannot guarantee perfect isolation [4], [5]. As a result, a level of residual self-interference (RSI) persists.…”