Perfect SI Cancellation Based on Mode-Switching for Differential Channel-Unaware TWRNs

We consider channel-unaware two-way relay networks (TWRNs) in which two single-antenna nodes exchange information through multiple single-antenna half-duplex relays. For these networks, we develop a novel self-interference (SI) cancellation scheme that does not invoke channel information neither at the relays nor at the nodes. Unlike its previous counterparts, the scheme proposed herein enables perfect SI cancellation even when the relays have a single antenna each. In the first phase of the proposed scheme, the network is operated in a one-way relaying mode, whereas in the second phase it is operated in a two-way relaying mode. In the latter mode, the vectors received by the nodes at the end of the first phase are used to completely eliminate SI, without estimating the channel as in existing methodologies. To show the effectiveness of the proposed scheme, we compare the block error rate of this scheme with that of two recently proposed schemes, one of which uses multiple antennas at the relays to cancel SI in channel-unaware TWRNs. This comparison shows that the proposed scheme outperforms the previously proposed schemes for all data rates.