Full-Duplex Relay with Delayed CSI Elevates the SDoF of the MIMO X Channel

In this article, the sum secure degrees-of-freedom (SDoF) of the multiple-input multiple-output (MIMO) X channel with confidential messages (XCCM) and arbitrary antenna configurations is studied, where there is no channel state information (CSI) at two transmitters and only delayed CSI at a multiple-antenna, full-duplex, and decode-and-forward relay. We aim at establishing the sum-SDoF lower and upper bounds. For the sum-SDoF lower bound, we design three relay-aided transmission schemes, namely, the relay-aided jamming scheme, the relay-aided jamming and one-receiver interference alignment scheme, and the relay-aided jamming and two-receiver interference alignment scheme, each corresponding to one case of antenna configurations. Moreover, the security and decoding of each scheme are analyzed. The sum-SDoF upper bound is proposed by means of the existing SDoF region of two-user MIMO broadcast channel with confidential messages (BCCM) and delayed channel state information at the transmitter (CSIT). As a result, the sum-SDoF lower and upper bounds are derived, and the sum-SDoF is characterized when the relay has sufficiently large antennas. Furthermore, even assuming no CSI at two transmitters, our results show that a multiple-antenna full-duplex relay with delayed CSI can elevate the sum-SDoF of the MIMO XCCM. This is corroborated by the fact that the derived sum-SDoF lower bound can be greater than the sum-SDoF of the MIMO XCCM with output feedback and delayed CSIT.

Outage Performance of Full-Duplex Relay Networks Powered by RF Power Station in Ubiquitous Electric Internet of Things

This paper investigates a full-duplex relay network assisted by radio frequency (RF) power station in ubiquitous electric Internet of Things (UEIoT), where a wireless sensor on high voltage transmission line collects electric data and then transmits data to a destination via a full-duplex decode-and-forward relay. The destination receives and processes the data to inspect the state of high voltage transmission line. Both the sensor and relay do not have fixed energy source; so, they first have to harvest energy from a RF power station and then complete information transmission by using the harvested energy. As the line-of-sight (LOS) propagations often exist in outdoor application scenarios of UEIoT, the Rician fading channel is adopted in the network. To explore the system outage performance, the explicit expressions of the outage probability and throughput of the system are derived by using mathematical analysis. Simulation results validate the correctness of our theoretical analysis and also evaluate the effects of system parameters and deployment position of power station on the outage performance.