Wireless Communication Networking for the Self-Powered Internet of Things Systems:
Comparison of Bluetooth and Wi-Fi
Nowadays, the internet of things (IoT) has grown so rapidly and it becomes necessary for every business and industry. The main purpose of the IoT systems is connecting wirelessly the electronic and mechanical devices each other, also object, animals, plants and people can interrelate in it with sensors such as; heart rate, temperature and moisture. The majority of the self-powered IoT applications send sensors data to the server using the Wi-Fi and Bluetooth and protocols. These systems have advantages and disadvantages for different areas so it would not be all right to say that one of them is better or worse. However, in the IoT application’s major attracting factors of communication protocols are the power consumption, installation cost and security. In these cases, we can examine which protocols should be used for the implemented project.
Another highly researched topic is Self-powered sensor modules what is harvesting energy and power itself from the environment or uses the only battery for supply. Energy and power harvesting systems generally use methods which are photovoltaic which generated power from solar power like a solar panel, piezo-electric which convert mechanical strain to electrical energy and thermal which is converted to human body heat to electrical energy. However, in today’s technology, these methods are insufficient when analyzing in the using unit area. In the IoT systems, communication protocol consumes most of the energy so it chooses should be wise.
If the two protocols are compared in terms of power consumption, Bluetooth and Wi-Fi technologies, as it can be concluded from Figure 1 Wi-Fi is much consume energy than Classic Bluetooth and Bluetooth Low Energy (LE) . Bluetooth LE (BLE) or named as Bluetooth Smart is the new version (Bluetooth 4.0) to reduce power consumption and cost with decrement range of communication. However, IoT systems do not require higher data rate and range because modules generally near each other and data are not large so it includes only specific sensor reads. Additionally, Wi-Fi peak current consumption shows when receiving a package of data to another devices consumption is near to 50mA (Read), and sending consumption is 200mA(Transmit), it almost 14 times of the BLE. In addition, Figure 2 shows Wi-Fi and Bluetooth are much more consume power than Bluetooth Smart when the connection is established but data flow is not happening but listen to pairs of the connections. More detail for the energy consumption is in Figure 3 shows Wi-Fi is consumed more energy for all operating condition.
Transmit and Sleep Power what is mentioned above is most important operating status because in the Self-Powered IoT system applications send data after that go into sleep mode for the battery saving. Figure 3 claim that Wi-Fi power consumption is ten times bigger than BLE when average power for 10 messages per day. When using 1cm^2 modules each of energy harvesting methods showing at Figure4 Wi-Fi can’t work except outdoor Photovoltaic. However, BLE can work except RF and Vibration methods. Finally, Wi-Fi can work at a longer distance and higher data rate makes Wi-Fi consuming power than Bluetooth and BLE. Therefore, BLE is perfect choose with photovoltaic energy harvesting methods for Self-Powered IoT systems.
In the industrial area giving critical decisions based on sensors outputs, if sensor calibration manipulated it can occur catastrophe. For example, when temperature sensors on nuclear plants give wrong value to computer explosion can happen so that security is important for the communication sensor in IoT applications. If two protocols are compared in terms of security, Bluetooth has 3 modes of the security and these are; non-secure, service level, link level . In the service level mode user give specific password when connection establishing. In the link level mode Bluetooth use end to end security type. It means that unique password created before the connection start so that this makes harder security protocol manipulations. In the Wi-Fi always open access connection protocol . In these protocol uses for waiting request of connection other devices so that, it is almost open for connection attack and also when sending data through Wi-Fi network, fully connection must occur. On the other hand, Bluetooth can share the data with using broadcast protocol what is only sending data through air and devices can reach data without full connection establishing so that devices cannot reach calibration of sensors. The topology of the connection is related to the security. Bluetooth have a server-client, broadcasting, peer-to-peer(p2p) connection types. Wi-Fi have Server – Client, p2p, machine-to-machine(m2m) Most security topology is a p2p connection because p2p connection act like both server and client so that, devices can reach data each other even connection bigger network areas. Another network topologies need to the main device to watch all connection (see Figure 5) so all connection way goes to the main device is attacking happens this main device all network system collapse. The P2P connection is found both Wi-Fi and Bluetooth but Bluetooth also has service and link layer also Bluetooth can use both of P2P topology and security layers together and it decreases the possibilities of the found unique password for the communication.
If two protocols are compared in terms of cost for setup wireless network in big areas with using server-based topology of course Wi-Fi cost less than Bluetooth because Wi-Fi range is larger than Bluetooth (see Figure 1) . However if using the P2P connection and choosing Bluetooth’s BLE version. It is much cheaper than Wi-Fi . Because implementation of the BLE is easier than Wi-Fi because Wi-Fi antenna and other components more expensive and required number of components are more than BLE antenna and required components because Wi-Fi’s working principle is more complex. Nordic nRF BLE chips are one of the BLE chips and it is also one of the ultra-low energy chips cost only pennies. A connection for two device via Bluetooth is simple because using end to end protocol the only user give input one password rest of connection protocol occur automatically. On the other hand, Making to ready to Wi-Fi connection protocol need to expertise so that it requires labour force and cost.
Finally, BLE is perfect choose for IoT application with a need to exchange small data between devices without full connection . Bluetooth Low Energy is working less power and cost than Wi-Fi and more security. It provides self-powered IoT systems needs.
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