## 1 Introduction
The authors then evaluated seven principal criteria, required by multicast authentications for resource-constrained applications. Next, [PERSON] et al. [3] presented a location based authentication scheme embedded with an effective data collection mechanism for IoT networks. In the proposed system, the parameters related to network control can be adjusted dynamically to satisfy the real-time requirements of the system and the corresponding network environments. This property improves the authentication accuracy of the proposed system. In addition, the optimization of the authentication accuracy is investigated. Furthermore, [PERSON] et al. [4] developed lightweight authentication and authorization procedures, which are compliant with the Architectural Reference Model (ARM) from the EU FP7 IoT-A project, for constrained IoT-based sensors. The proposed schemes can also be combined with other standard technologies and can be utilized to form security plans for the life cycle of IoT device development. In 2014, [PERSON] et al. [5] introduced a healthcare system architecture, which is fit for wireless sensor networks. The authors proposed a communication protocol stack for WSN (wireless sensor networks)-based pervasive healthcare applications in which four layers embedded with various technologies, such as IEEE 802.15.4 MAC (medium access control) layer, network layer, middleware services and application layer, are introduced. Implementations including network coding and distributed localization scheme are demonstrated on a WSN testbed as a proof of concept of their proposed architecture. Next, [PERSON] et al. [6] presented a cloud-assisted MAC protocol, called CLNC-MAC (cloud-assisted RLNC-based MAC protocol), which exploits random linear network coding (RLNC) techniques to guarantee the completeness of the data transmission in healthcare applications regardless of the channel conditions of the relay network. Analyses on CLNC-MAC are then performed via queuing theory in which essential metrics, i.e., data throughput, data delay and energy efficiency, are examined through Monte Carlo simulations. With the performance assessment, the authors demonstrated that their proposed protocol is superior to existing methods in the presence of channel errors for a two-hop relay network. In the following year, [PERSON] et al. [7] further presented a framework for cloud-assisted ambient assisted living (AAL) applications. The proposed framework provides two planes for control operation and data operation and thus delegates network coordinationtasks to the cloud. An efficient MAC protocol is developed in which the RLNC technique is adopted in a cooperative relay network to pursue better performance efficiency. Later, [PERSON] et al. [8] discussed the opportunity and challenge for Machine-to-Machine (M2M) mHealth systems in terms of a wireless communications perspective. Eight major challenges, such as heterogeneous devices and traffic, wireless propagation characteristics, energy efficiency, quality of service, reliability, interference and coexistence, topology, security and technology integration, must be thoroughly considered for the development of M2M mHealth systems. Recently, [PERSON] and [PERSON] [9; 10] presented two authentication schemes, i.e., BSN-Care [9] and USM-IoT [10], for IoT networks. These two schemes are designed to fit the architecture (and its specific security requirements) of body sensor networks and distributed wireless sensor networks (WSN), respectively. Both of these two schemes have a similar concept in the design of the proposed authentication mechanisms. That is, lightweight crypto-modules, such as one-way hash function, random number generator operation and bitwise exclusive-or operation, are adopted for providing system efficiency and security robustness at the same time.