Abstract
The advent of the Internet-of-Things (IoT) and proliferation of wireless devices and systems have put stringent requirements on reliability and latency, in addition to the scarcity of energy and spectrum resources. More importantly, ultra-reliability and low-latency (URLL) combined with concepts of energy-harvesting (EH) and cognitive-radio (CR) make the analysis of IoT networks much more complex. This paper analyzes the performance of uplink EH-CR-IoT networks with URLL requirements. Analytical expressions for IoT network metrics, namely, average packet latency, reliability, and energy-efficiency are derived, while incorporating diversity transmissions under the finite blocklength (FBL) regime. The effect of network parameters, such as number of resource blocks allocated to each IoT user equipment (UE), blocklength, and number of packet replicas is examined on the network metrics, and their tradeoffs are discussed. Finally, the derived expressions are utilized to maximize the energy-efficiency of the IoT UEs subject to energy-causality and URLL constraints.
Highlights
The Internet-of-Things (IoT) has emerged as a promising networking paradigm for connecting massive numbers of smart systems and devices, which urgently call for spectrum- and energy-efficient transmission techniques to meet the diverse requirements of latency, reliability and energy-efficiency
The IoT user equipment (UE) energy-efficiency maximization problem subject to energy-causality and ultra-reliable and low-latency (URLL) constraints on the average packet latency and reliability is solved by utilizing the derived analytical expressions
NUMERICAL RESULTS the effect of the number of packet replicas K, blocklength nb, and the number of resource blocks (RBs) allocated to each IoT UE on the average packet latency, reliability, and energy-efficiency is evaluated
Summary
The Internet-of-Things (IoT) has emerged as a promising networking paradigm for connecting massive numbers of smart systems and devices, which urgently call for spectrum- and energy-efficient transmission techniques to meet the diverse requirements of latency, reliability and energy-efficiency. The effect of the number of RBs allocated to each IoT UE, blocklength, and transmission diversity on the average packet latency, reliability, and energy-efficiency is investigated. The IoT UEs energy-efficiency maximization problem subject to energy-causality and URLL constraints on the average packet latency and reliability is solved by utilizing the derived analytical expressions. The blocklength as well as the number of packet replicas and required RBs are optimized for energy-efficiency maximization It is worth-mentioning that this study is different from our URLLC-based previous works in [19], [20]. This work considers a different network model that brings dynamic spectrum access (i.e. cognitive radio) with energy-harvesting nodes into the IoT paradigm, while [19], [20] analyze network metrics in uplink RA-NOMA IoT networks with URLL requirements. Where fγ (θ ) is the probability density function (PDF) of γ
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