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In this paper, we propose optimal distributed dynamictime-division-duplex (D-TDD) schemes for half-duplex (HD) base stations (BSs) with decoupled uplink-downlink transmissions. In particular, for a BS with decoupled access, we propose optimal adaptive scheduling of its uplink-receptions from user 1 and downlink-transmissions to user 2 by taking into account inter-cell interference. The proposed schemes increase the uplink-downlink rate/throughput region and decrease the outage probabilities on both the uplink and downlink channels. In fact, the proposed D-TDD scheme doubles the diversity gain on both the uplink and downlink channels compared to the diversity gain of the static-TDD scheme and to the state-of-the-art D-TDD schemes for a BS with coupled uplink-downlink transmission, which results in significant performance gains.

In this paper, we investigate the fading two-hop full-duplex (FD) relay channel with self-interference, which is comprised of a source, an FD relay impaired by self-interference, and a destination, where a direct source-destination link does not exist. For this channel, we propose three buffer-aided relaying schemes with adaptive reception-transmission at the FD relay for the cases when the source and the relay both perform adaptive-rate transmission with adaptive-power allocation, adaptive-rate transmission with fixed-power allocation, and fixed-rate transmission, respectively. The proposed buffer-aided relaying schemes enable the FD relay to adaptively select to either receive, transmit, or simultaneously receive and transmit in a given time slot based on the qualities of the receiving, transmitting, and self-interference channels; a degree-of-freedom unavailable without buffer-aided relaying. Our numerical results show that significant performance gains are achieved using the proposed buffer-aided relaying schemes compared to conventional FD relaying, where the FD relay is forced to always simultaneously receive and transmit, and to buffer-aided half-duplex relaying, where the half-duplex relay cannot simultaneously receive and transmit. The main implication of this work is that FD relaying systems without buffer-aided relaying miss-out on significant performance gains.

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The study of optimal properties of centralized dynamic-time-division-duplex (D-TDD) employed at a wireless network consisting of multiple nodes is a highly challenging and partially understood problem in the literature. In this paper, we develop an optimal centralized D-TDD scheme for a wireless network comprised of K full-duplex nodes impaired by self-interference and additive white Gaussian noise. As a special case, we also propose the optimal centralized D-TDD scheme when part or all nodes in the wireless network are half-duplex. Thereby, we derive the optimal adaptive scheduling of the reception, transmission, simultaneous reception and transmission, and silence at every node in the network in each time slot such that the rate region of the network is maximized. The performance of the optimal centralized D-TDD can serve as an upper-bound to any other TDD scheme, which is useful in qualifying the relative performance of TDD schemes. The numerical results show that the proposed centralized D-TDD scheme achieves significant rate gains over existing centralized D-TDD schemes.