Optimal Centralized Dynamic-Time-Division-Duplex

In this paper, we derive the optimal centralized dynamic-time-division-duplex (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 provide the optimal centralized D-TDD scheme when the nodes are half-duplex as well as when the wireless network is comprised of both half-duplex and full-duplex nodes. 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

Dynamic Time-Frequency Division Duplex

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.Comment: Content presented in this article is subjected to Australian Provisional Patent Application 2019903224, filing date 2/Sep/2019, see http://pericles.ipaustralia.gov.au/ols/auspat/applicationDetails.do?applicationNo=2019903224. arXiv admin note: text overlap with arXiv:1701.0527

Supporting Asymmetric Traffic in a TDD/CDMA Cellular Network via Interference-Aware Dynamic Channel Allocation and Space-Time LMMSE Joint Detection

In a TDD/CDMA cellular network with asymmetric data traffic, dynamic channel allocation (DCA) enhances the resource utilization compared to fixed channel allocation (FCA). However, it also induces base-to-base and mobile-to-mobile crossed-slot intercell interference, which can severely degrade the system performance. To deal with this problem, a decentralized scheme is proposed, that combines an interference-aware DCA algorithm with space-time linear MMSE joint detection at the base and mobile stations. The former assigns active links to timeslots in a way that crossed-slot interference is mitigated, while the latter suppresses the remaining intercell interference (along with intersymbol and intracell interference) exploiting its spatio-temporal autocorrelation statistics. The performance of this scheme is evaluated in terms of downlink and uplink SINR outage and average throughput via analytical approximations and Monte Carlo simulations, and it is compared to that of benchmark random DCA and FCA schemes. The cases of singleand dual-antenna reception with perfect and imperfect channel state information are examined. It is shown that the proposed scheme achieves higher average throughput than FCA (especially for dual-antenna reception) as well as random DCA (for heavy traffic loads). These throughput gains are more significant in uplink than in downlink