Table 2.

Comparison of the main features of the most relevant academic HAS and the proposed system (part 1).

System	Main Objective	Messaging Protocol	Actuation Capabilities	Open-Source Code	Conceived for Fog Computing	Cost	Relevant Features/Challenges
ZiWi	MQTT-based HAS	MQTT	Yes	OpenHAB (Node source code available on GitHub)	Yes	180 (whole demonstrator)	High flexibility, interoperability and scalability
[19]	Intelligent building monitoring	Ad hoc	Yes	No	No	Low cost	Delays due to SMS-based commands
[20]	Indoor ambient intelligence monitoring	Ad hoc	Yes	No	No	Cost-effective	Alarm control center, several scenarios
[21]	Energy efficiency	Ad hoc	Yes	No	No	Low-cost	Heuristic scheduling algorithm
[22]	ZigBee-based HAS	Ad hoc	No	No	No	Not specified	Software designed of the coordinator and terminal node
[23]	Gateway for assisted living applications	Ad hoc, dependent on the assisted living device	Yes	No	No	Not specified	Biometrics and actimetry for assisted living
[24]	HAS for heterogeneous networking	Ad hoc	Open API	No	Cloud capabilities	Not specified	Integrated home appliances with prediction algorithms
[25]	Enabling IoT services in HAS	Ad hoc	Yes	No	No	Not specified	Basic GUI with sensor readings
[41]	Power outlet control and monitoring	Ad hoc	Yes	No	No	45 (one smart socket)	Experimental analysis with theoretical and empirical measurements
[43]	Smart building energy efficiency monitoring	Ad hoc messages routed with CTP (Collection Tree Protocol)	Yes	No	Decentralized architecture	Not specified	Decision-making manager and integration of different applications
[44]	HAS	XMPP	Yes	Openfire	No	Low-cost	Android app for control units
[45]	HAS	MQTT	Yes	OpenHAB	No	Cost-effective (less than $60 for a Raspberry Pi 2, an SD card and four ESP8266 modules)	Overall delay from UI to Node is less than 600 ms
[46]	MQTT-based HAS	MQTT	Yes	No	No	Not specified	It makes use of ESP8266 WiFi modules