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Physical unclonable functions (PUF) is a promising technique in the field of hardware security with the main principle based on the random variations of inherent semiconductor devices during the fabrication process to provide the secret keys for cryptography or IC identification/authentication. In this paper, we present a new, efficient design of CMOS PUF based on ring oscillators and a time-to-digital converter (TDC). The proposed PUF design provides higher number of respond bits for each challenge, better reliability and uniqueness compared with conventional RO PUF designs. The proposed PUF design is implemented with TSMC 180 nm CMOS process using Cadence Virtuoso tool. The detailed design, simulation and evaluation results are also presented and discussed. The experimental results have clarified the efficiency of the proposed PUF design.

In this paper, we propose and analyze a downlink multiple-user MIMO-NOMA relay system where all users are grouped into several clusters. To mitigate the inter-cluster interference, the superposition signals at the base station are beamed at the relay nodes. Then, the relays communicate with the users through superposition coding in power domain. We derive the exact closed-form expressions of the outage probability of each user in every cluster for the cases of perfect successive-interference cancellation (SIC) and imperfect SIC. The outage performance is analyzed the over Nakagami-m fading channels, taking into account the imperfection of channel state information (CSI). All analysis results are compared with Monte-Carlo simulation result to verify the correctness of the derived mathematical expressions. The results show that the channel fading severity, channel estimation error, and the quality of SIC structure have strong influences on the outage performance of the proposed MIMO-NOMA relay system.

In this paper, we investigate performance of a decode-and-forward Non-Orthogonal Multiple Access (NOMA) relay system using Simultaneous Information and Power Transfer (SWIPT). In the considered system a source node transmits data in the downlink simultaneously to two destination nodes via an energy-harvesting relay node. In order to cope with fading channels the relay is assumed to have an infinite capacity buffer to store data if the transmission link is in outage. We analyze outage performance of the system and obtain the closed-form expressions for the system outage probability for two cases, i.e. the relay is equipped and not equipped with the buffer. Numerical results are provided to demonstrate the merit of using the buffer-aided relay.