Abstract:
Long Range (LoRa) is a popular low power wide area network (LPWAN) technology which operates in the Industrial, Scientific and Medical (ISM) frequency band transmitting information over ranges in excess of 20 km and 5 km in rural and urban landscapes respectively. This is of significance in applications where LoRa may be used as a terrestrial navigation system, or in any wireless sensor network (WSN) applications. A key system performance parameter for network planning and coverage prediction in ranging applications is the horizontal dilution of precision (HDOP). HDOP, is dependent on transmitter geometry and can amplify the position errors depending on how the transmitters are placed with respect to one another. Despite the importance of HDOP, there is no prescribed transmitter or gateway placement technique in the literature that has been combined with HDOP to obtain good position fixes within the coverage area. We propose a gateway placement technique called imaginary triangular tessellation technique to be used in conjunction with HDOP. The HDOP performance of our proposed technique is compared against three other placement techniques, namely naive, Deluany and random placement for the same number of gateways using the total average HDOP score of the area where a method has been deployed, as well as statistical significance and effect size as tests. The goal of our experiment is to find a placement technique that results in a better HDOP score (values between 0 and 1) in most parts of the coverage area. The HDOP scores for the random, Delauny, naive and our proposed technique are 30%, 50% 47% and 70% respectively for 8 gateways. The results also suggest that at least 8 LoRa gateways are needed to service our chosen geographical area of 2500 hectares or 6175 federation football fields. The results demonstrate that our proposed method can be used to set up and plan a LoRa network for use in scenarios such as tracking of animals, vehicles and navigation.