# LoRaWAN Base Station Improvement for Better Coverage and Capacity
## 1 Introduction  
In order to develop the Internet of Things (IoT), a network of devices that communicate with each other and other systems over the Internet, it is necessary to have communication technology that provides long-range and low power consumption. Technologies in which high data rate is traded for wide coverage and energy efficiency are known as Low Power Wide Area Networks (LPWAN). According to [1], over 90% of all connected devices use one of four most utilized LPWAN technologies: NB-IoT (Narrowband IoT), LoRaWAN (Long Range WAN), LTE-M (Long Term Evolution for Machines), and Sigfox. It is considered that LoRaWAN will, along with NB-IoT connect 86% of all LPWAN devices by the year 2023 [2]. The key difference between the two is linked to the frequency spectrum they use. LoRaWAN operates in unlicensed spectrum and can provide lower prices in terms of devices and services. On the other hand, since the spectrum it uses is shared with other technologies, interference problems with other systems are possible. To reduce it, LoRaWAN use Chirp Spread Spectrum (CSS) [3] modulation technology in which data is encoded with frequency-modulated signal--chirp, which enhances long-range communication and robustness to interference. Another advantage of LoRaWAN over other LPWAN technologies is its big community which can be seen through a number of published research and experimental evaluations. For instance in [4], results of field experiments in Paris with performance evaluation and network coverage are given. In [5], LoRaWAN testbeds are made for the comparison of indoor and outdoor measurements with the results of LoRaSim simulation implemented and described in [6]. Further evaluations focused on different environments and Authors in [7; 8; 9; 10; 11; 12; 13] conducted analysis and experiments for urban and suburban areas, while in [14; 15] maritimeand mountain areas were analyzed, respectively. In particular, in [7; 9] urban scenarios were thoroughly tested showing reasonable coverage with simple base stations highlighting the height of the base stations and topology as major factors affecting the deployment strategy. This conclusion was also confirmed in [10] who included indoor coverage in their measurements. In addition, in [13], urban, suburban and rural, stationary and mobile scenarios were considered, indicating that propagating conditions in the deployment scenario need to be carefully evaluated before actual implementation. As observed in these related works, network coverage and capacity in different terrains and for different configurations are generally acceptable, however, the network implementation should be done carefully to maximize the LoRaWAN potential. Additionally, as pointed out in [16; 17] in which different real-life tests of the LoRaWAN network were conducted, on average there was around 30% of packet loss, indicating that there is significant room for improvement. There were also various research activities regarding coverage enhancement, but their focus was either on end node improvement [18; 19] or constructing multi-hop network [20; 21], while the base station enhancements were generally not considered. The problem of packet loss and efficiency is not critical in situations where there are just a few sensors, however, it becomes an issue in more complex applications. For example, in applications where there are many sensors in a small area, there is large probability of message collisions and consequently packet loss, which will result in the need for unnecessary message retransmission. Also, it can be an issue in remote areas where battery efficiency is critical and frequent retransmissions could significantly reduce the lifetime of the node. In these scenarios we need to improve the reception of the base station and we propose a simple and cost-effective upgrade of the LoRaWAN base station using additional concentrators.