Dynamic Time-Frequency Division Duplex

TL;DR

This paper introduces a novel dynamic duplexing scheme called D-TFDD that combines TDD and FDD, improving throughput, reducing outages, and doubling diversity gains without needing inter-cell interference knowledge.

Contribution

The paper proposes D-TFDD, a new duplexing scheme that enhances performance and practicality by combining TDD and FDD without requiring inter-cell interference information.

Findings

Increases throughput region between BS and users.

Decreases outage probabilities significantly.

Doubles the diversity gain on BS-U channels.

Abstract

In this paper, we introduce dynamic time-frequency-division duplex (D-TFDD), which is a novel duplexing scheme that combines time-division duplex (TDD) and frequency-division duplex (FDD). In D-TFDD, a user receives from the base station (BS) on the downlink in one frequency band and transmits to the BS on the uplink in another frequency band, as in FDD. Next, the user shares its uplink transmission (downlink reception) on the corresponding frequency band with the uplink transmission or the downlink reception of another user in a D-TDD fashion. Hence, in a given frequency band, the BS communicates with user 1 (U1) and user 2 (U2) in a D-TDD fashion. The proposed D-TFDD scheme does not require inter-cell interference (ICI) knowledge and only requires channel state information (CSI) of the local BS-U1 and BS-U2 channels. Thereby, it is practical for implementation. The proposed D-TFDD scheme increases the throughput region between the BS and the two users in a given frequency band, and significantly decreases the outage probabilities on the corresponding BS-U1 and BS-U2 channels. Most importantly, the proposed D-TFDD scheme doubles the diversity gain on both the corresponding BS-U1 and the BS-U2 channels compared to the diversity gain of existing duplexing schemes, which results in very large performance gains.