Table 1.

Comparison of Access Control Approach and Considered Requirements.

	AC Approach	LI	FL	CA	SC	IN	Remakes
Sciancalepore et al. [5]	ABAC	-	✔	✔	✔	✔	Consideration of the federation between heterogeneous IoT platforms
Sciancalepore et al. [15]	OAuth 2.0	✔	✔	-	✔	✔	Consideration of multiple token standards (i.e., Bearer, JWT, and PoP)
Fernandez et al. [18]	OAuth 2.0 and Role-based	✔	✔	-	✔	✔	Access control service is completely delegated to the server
Pal el al. [22]	Attribute-, Capability-, and Role-based	✔	✔	✔	✔	-	Access decision based on three features (i.e., attribute, capability, role)
Neto et al. [25]	ABAC	✔	✔	✔	✔	✔	Authentication and access control considering the entire life-cycle of IoT device
Ouechtati et al. [26]	ABAC	-	✔	✔	✔	-	Consideration of the subject behavior and the trust value
Proposed framework	Extended OAuth 2.0 and Role-based	✔	✔	✔	✔	✔	All requirements and interoperability between heterogenous IoT platforms are fully considered in the proposed access control framework

* AC: Access Control, LI: Lightweight, FL: Flexibility, CA: Context-awareness, SC: Scalability, IN: Interoperability.