## 2 Background
### Smart Home Device
#### 2.1.2 Communication Patterns and Smart Device Connectivity  
Traditional computers are typically connected to a local network directly over Ethernet or WLAN and are able to communicate with other devices in the network over a switch, which is typically incorporated into the home router, which often also contains an access point for the WLAN. In contrast, the Smart Home domain incorporates a broader spectrum of communication methods. While there are many products that follow the \"traditional\" model, there are also devices that use different communication ways either additionally or exclusively. Even for the same use case, different approaches can be applied. While, for example, Yeelight bulbs are directly connected to the WLAN (\"Yeelight smart LED products support remote control through WiFi\"; see specification found at [[https://www.yeelight.com/download/Yeelight_Inter-Operation_Spec.pdf](https://www.yeelight.com/download/Yeelight_Inter-Operation_Spec.pdf)]([https://www.yeelight.com/download/Yeelight_Inter-Operation_Spec.pdf](https://www.yeelight.com/download/Yeelight_Inter-Operation_Spec.pdf)) (last accessed: 19 December 2024)), Philips Hue light bulbs are not connected to the local network directly but through an additional bridge (\"anything \"smart\" needs to be able to receive instructions. Hue smart lights use Zigbee or Bluetooth to communicate, depending on whether you have a Bridge,\" as stated on the explanation found at [[https://www.philips-hue.com/en-us/explore-hue/how-it-works](https://www.philips-hue.com/en-us/explore-hue/how-it-works)]([https://www.philips-hue.com/en-us/explore-hue/how-it-works](https://www.philips-hue.com/en-us/explore-hue/how-it-works)) (last accessed: 19 December 2024)). The ZigBee protocol is used for communication between the bridge and the actual lamp [25]. As traffic on other communication technologies behind such a bridge cannot, however, be observed by a firewall operating on the IP traffic in the WLAN or Ethernet of the home network, it is out of the scope of this paper. Also excluded is any other form of communication that does not involve the local area network (LAN)--be it wireless (WLAN) or cabled--such as Bluetooth connections between a Smartphone and smart device, direct WLAN communication between a Smartphone and the WLAN access point of the smart device, or communication completely outside of the home, e.g., among several servers on the Internet.  
Even when focusing on such communication that is visible in the local network, there exist generalisable and fundamentally different communication patterns in a Smart Home. Table 1 gives an overview of patterns, which involve only two communicating parties, in order to illustrate the diversity of control or information flow in the Smart Home domain. In addition, there exist control flows or information flows that involve multiple of the above patterns. Examples of such indirect control communication patterns involving three parties are given in Table 2. Of course, even more arbitrary complex patterns could arise. Finally, it should be noticed that those patterns are not mutually exclusive but one device can use multiple of them.