A Review of Wireless Sensor Technologies and Applications in Agriculture and Food Industry: State of the Art and Current Trends

Luis Ruiz-Garcia, Loredana Lunadei, Pilar Barreiro, Ignacio Robla
2009 Sensors  
The aim of the present paper is to review the technical and scientific state of the art of wireless sensor technologies and standards for wireless communications in the Agri-Food sector. These technologies are very promising in several fields such as environmental monitoring, precision agriculture, cold chain control or traceability. The paper focuses on WSN (Wireless Sensor Networks) and RFID (Radio Frequency Identification), presenting the different systems available, recent developments and
more » ... xamples of applications, including ZigBee based WSN and passive, semi-passive and active RFID. Future trends of wireless communications in agriculture and food industry are also discussed. WSN can operate in a wide range of environments and provide advantages in cost, size, power, flexibility and distributed intelligence, compared to wired ones. In a network, when a node cannot directly contact the base station, the message may be forwarded over multiple hops. By auto configuration set up, the network could continue to operate as nodes are moved, introduced or removed. Monitoring applications have been developed in medicine, agriculture, environment, military, machine/building, toys, motion tracking and many other fields. Architectures for sensor networks have been changing greatly over the last 50 years, from the analogue 4-20 mA designs to the bus and network topology of today. Bus architectures reduce wiring and required communication bandwidth. Wireless sensors further decrease wiring needs, providing new opportunities for distributedintelligence architectures [2, 10, 20] . For fieldbus architecture, the risk of cutting the bus that connects all the sensors persists. WSN eliminates all the problems arising from wires in the system. This is the most important advantage of using such technology for monitoring. Wireless sensor technology allows Micro-Electro-Mechanical Systems Sensors (MEMS) to be integrated with signal conditioning and radio units to form "motes" -all for a low cost, a small size, and with low power requirements. Available MEMS include inertial, pressure, temperature, humidity, Sensors 2009, 9 4730 strain-gage, and various piezo and capacitive transducers for proximity, position, velocity, acceleration and vibration measurements [20] ; and according to several research works, connecting wires to these devices can be more problematic than doing it by means of wireless designs [21, 22] . Motes can form networks and co-operate according to various models and architectures. They came with miniaturized sensors mounted, that allow, in a small space (2.5 × 5 × 5cm), the gathering of data not only just about temperature, but also relative humidity, acceleration, shock and light [23] . Another advantage for wireless sensor devices is the feasibility of installation in places where cabling is impossible, such as large concrete structures [24] or embedded within the cargo, which brings their readings closer to the true in situ properties of perishable products [25] . Wired networks are very reliable and stable communication systems for instruments and controls. However, wireless technology promises lower installation costs than wired devices, because required cabling engineering is very costly [26] . Wireless Sensor Networks A WSN is a system comprised of radio frequency (RF) transceivers, sensors, microcontrollers and power sources [10] . Recent advances in wireless sensor networking technology have led to the development of low cost, low power, multifunctional sensor nodes. Sensor nodes enable environment sensing together with data processing. Instrumented with a variety of sensors, such as temperature, humidity and volatile compound detection, allow monitoring of different environments. They are able to network with other sensor systems and exchange data with external users [27] . Sensor networks are used for a variety of applications, including wireless data acquisition, machine monitoring and maintenance, smart buildings and highways, environmental monitoring, site security, automated on-site tracking of expensive materials, safety management, and in many other areas [10] . A general WSN protocol consists of the application layer, transport layer, network layer, data link layer, physical layer, power management plane, mobility management plane and the task management plane [10] . Currently two there standard technologies are available for WSN: ZigBee and Bluetooth. Both operate within the Industrial Scientific and Medical (ISM) band of 2.4 GHz, which provides licensefree operations, huge spectrum allocation and worldwide compatibility. In general, as frequency increases, bandwidth increases allowing for higher data rates but power requirements are also higher and transmission distance is considerably shorter [27, 28] . Multi-hop communication over the ISM band might well be possible in WSN since it consumes less power than traditional single hop communication [28] . It is also possible to create a WSN using Wi-Fi (IEEE 802.11), but this protocol is usually utilized in PC-based systems because it was developed to extend or substitute for a wired LAN [29]. Its power consumption is rather high, and the short autonomy of a battery power supply still remains an important disadvantage [30] .
doi:10.3390/s90604728 pmid:22408551 pmcid:PMC3291936 fatcat:2saxerk4uvdwnnq25abdpghjfm