High-Confidence Gateway Planning and Performance Evaluation of a Hybrid LoRa Network

Hybrid long-range (LoRa) network is a promising approach to overcome the half-duplex issue in traditional LoRa networks, increasing the network efficiency and confidence for today's fast-developing smart city services. Gateways (GWs) in hybrid LoRa networks link the end devices (EDs) and the Netserver and have a great impact on the system performance. Previous results on GW planning cannot be directly applied to hybrid LoRa networks since the heterogeneous EDs require different redundancy of coverage. Furthermore, the spreading factors (SFs) which determine the system performance should be considered concurrently. In this article, in order to find the optimal planning scheme, i.e., deciding the number and locations of GWs in the hybrid LoRa network, we propose a heterogeneous redundant coverage solution to meet the requirements of the heterogeneous EDs using the same or different frequencies for uplink and downlink. Specifically, we formulate this problem as a point coverage problem that meets the requirements of EDs. The deleted greedy algorithm (DGA) and the nondeleted greedy algorithm (NDGA) are designed to solve this problem, in which the DGA shows better performance when compared to NDGA. Furthermore, we build models of system performance and analyze the system throughput and energy efficiency based on SFs. The simulation results show that our solution gains more system throughput and energy efficiency than a one-coverage solution.