# Unmanned Aerial System-Based Data Ferrying over a Sensor Node Station Network in Maize
## 2 Materials and Methods
### Proposed UAS Data Ferrying Designs
#### 2.1.3 Design Parameters and Proposed UAS Data Ferrying Designs  
Considering the described design objective, criteria, and constraints, various wireless communication system data ferrying designs were explored based on capabilities, adaptability, and cost of the following factors: (1) wireless technology protocol, (2) UAS, (3) system power source, and (4) data storages.  
1. Three wireless technologies designed for industrial/commercial applications that are mostly used for agricultural farm operations were explored for this study: long-range radio (LoRa), ZigBee, and general packet radio service (GPRS). The LoRa protocol was introduced by the LoRa Alliance for the low power and wide-area Internet of Things (IoT) communication associated with the indoor transmission, [PERSON] et al. [24]. The LoRa gateway can collect data from LoRa nodes to construct the topology of a star network and may communicate with a cloud server over a long communication for high scalability. The LoRa protocol has a wide range of applicability in precision agriculture [6; 25; 26]. Sensor nodes based on the ZigBee wireless protocol in the agricultural field can communicate with a router up to 100 m. Recent studies have employed ZigBee for precision agriculture [27; 28; 29] because of its low power consumption, low cost, self-forming characteristics, and suitable communication range. General packet radio service (GPRS)/3G/4G employs packet data (a bit of data that is packaged for transmission) service for GSM-based cellular phones. The GPRS technology communication rates depend on consumer volume where consumers share common communication channels and resources and frequently experience variable delays and throughputs. The sensors could be interfaced to the GPRS system sensor board to obtain and transmit information to the remote server through the GPRS board, which depends on a GSM/GPRS mobile network. Some studies have deployed a GSM/GPRS mobile network for applications in precision agriculture [30; 31; 32].
2. Fixed-wing and multi-rotor UAS designs were considered as these are mostly used for agricultural operations. Fixed-wing UAS has a longer flight endurance capacity while multi-rotors can provide for stable and easy vertical take-off and landing [33].
3. The power supply to the wireless communication setup on the UAS could be tethered from the UAS or be powered from an external battery source mounted on the UAS.  
4 Transmitted data could be stored on the memory storage of the UAS or transmitted to the cloud. It is essential for the system to be cost-effective and adoptable. Based on these design parameters, six data ferrying communication systems designs (i.e., a combination of wireless technology protocol, UAS, a power source for the system, and data storages) were assessed: Design A: ZigBee wireless protocol, fixed-wing UAS, power tethered from UAS, cloud memory storage. Design B: LoRa wireless protocol, multi-rotor UAS, external power source, memory storage over the UAS. Design C: GPRS wireless protocol, fixed-wing UAS, external power source, memory storage over the UAS. Design D: ZigBee wireless protocol, multi-rotor UAS, power tethered from UAS, cloud memory storage. Design E: LoRa wireless protocol, fixed-wing UAS, power tethered from UAS, cloud memory storage. Design F: GPRS wireless protocol, multi-rotor, external power source, memory storage over the UAS. The cost-effectiveness and design adoptability of each design was also evaluated.