TCP stands for Transmission Control Protocol and is a standard that defines how to establish a network conversation than can be used to exchange data between different applications. TCP works together with the Internet Protocol (IP), which defines how computers send data to each other. TCP and IP together are the most important protocols of the internet protocol suite that will be described in detail later (see INTERNET PROTOCOL STACK).

Communication with the protocol at the same level in the stack at the other end is called a peer connection and is possible if the peers use the same protocol. To send the data from the sensor node to the sink we established a TCP link between the Arduino and our Smartphones. This was achieved by using an Arduino WiFi shield with an UART WiFi module and downloading a TCP/IP communication app on our phones (“TCP Client”). The TCP Client app allows the phone to connect to a specific TCP in order to deliver data between applications that are located on the same network. The network in this case is the WiFi network HI-LINK created by the WiFi module on the Arduino. In the case of the project setup, the Arduino is of course wired to its router, and the connection with the Raspberry Pi is wireless. This connection was very challenging to make, and after figuring out how to do it, there was no time left to try it out (see RASPBERRY PI).