Abstract
In this work, the performance evaluation and the optimization of dual-hop LoRa network are investigated. In particular, the coverage probability (Pcov) of edge end-devices (EDs) is computed in closed-form expressions under various fading channels, i.e., Nakagami- $m$ and Rayleigh fading. The Pcov under Nakagami- $m$ fading is computed in the approximated closed-form expressions; the Pcov under Rayleigh fading, on the other hand, is calculated in the exact closed-form expressions. In addition, we also investigate the impact of different kinds of interference on the performance of the Pcov, i.e., intra-SF interference, inter-SF interference (or capture effect) and both intra- and inter-SF interference. Our findings show that the impact of imperfect orthogonality is not non-negligible, along with the intra-SF interference. Moreover, based on the proposed mathematical framework, we formulate an optimization problem, which finds the optimal location of the relay to maximize the coverage probability. Since it is a mixed integer program with a non-convex objective function, we decompose the original problem with discrete optimization variables into sub-problems with a convex feasible set. After that, each sub-problem is effectively solved by utilizing the gradient descent approach. Monte Carlo simulations are supplied to verify the correctness of our mathematical framework. In addition, the results manifest that our proposed optimization algorithm converges rapidly, and the coverage probability is significantly improved when the location of relay is optimized.
Highlights
It is expected that there will be over 50 billion devices connecting to the Internet by the end of the year [1], making the Internet-of-Things (IoTs) a major component in the telecommunications industry
The performance metric is computed for each packet based on the signal-to-noise ratio (SNR) and signal-to-interference ratio (SIR) at the received nodes, i.e., relay and gateway
In this work, the coverage probability of the edge node is studied via the aid of one relay node which is randomly distributed throughout the networks
Summary
It is expected that there will be over 50 billion devices connecting to the Internet by the end of the year [1], making the Internet-of-Things (IoTs) a major component in the telecommunications industry. To maximize the performance of the entire networks, LoRa separates its coverage area into a set of non-overlapping regions, where each region will be assigned a unique value of SF and transmit power: in particular, the nearer the EDs is, the lower the SF and the smaller the transmit power The aim of this resource allocation is to reduce the inter-SF interference and to conserve power consumption by the EDs. smart resource allocation is yielded, the edge EDs still suffer from significant interference compared with end-devices around the gateway. In contrast with these above-mentioned works, we focus on the performance of edge-EDs in dual-hop decode-and-forward relaying in LoRa networks under different types of fading channels.
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