## 1 Introduction
The possible solution to allow all of these functionalities is to deploy a static multi-hop wireless network that connects a large number of electric smart meters to a gateway node, which in turn is directly connected to a control center which is responsible for all management kinds. AMI applications required a proper routing protocol to ensure the low-latency and the high reliability delivery for inward and outward traffic from meters to gateway and from the gateway to meters. However, smart meters' are static and fixed networks but its wireless connections still suffering from signal degradation due to the fading effects and signal interference. RPL is defined to be a Link-Layer protocol that is supposed to work within a wide of different technologies such as PLC or wireless network. RPL is part of the effort made by the Internet Engineering Task Force (IETF) to design the IPv6 architecture for low power networks (LLN), it is based on Distance Vector routing algorithms, which is designed to react and detect routing loops. RPL is originally designed for typical sensor networks such as the Advanced Metering Infrastructure (AMI) based WSN. In order to satisfy the AMI low-latency and high-reliability requirements, the deployed routing protocol must cope with the frequent link changes by proposing effective and fast routing path selection with low routing control traffic overhead. In this paper, we proposed experimental and simulated RPL implementations with a uniform and random network topology using IoT-LAB testbed and Java-based Cooja simulator. We proposed different scenarios with various packet sizes and different routing metrics. This study based on two hardware platform M3 Cortex nodes and Tmote Sky nodes with different experimental configuration scenarios to represent AMI network based on WSN architecture. We proposed a new RPL performance evaluation using the objective functions Hop Count and ETX, in terms of Packet Delivery Ratio, Network Latency, Control Traffic Overhead, and Power Consumption. Extensive simulations were carried out, and a detailed analysis of the proposed Objective Function ETX and OF0 to choose the best appropriate RPL configuration for the AMI applications based WSN. Adopting RPL protocol in AMI applications based PLC communication is out of this paper scope. We are interested in evaluating RPL performance and metrics to propose the most efficient objective function to choose the best path to destination. We investigated the objective functions and the most influential parameters on RPL performance using Contiki as the wireless sensors operating system, IOT-LAB testbed, and a Java-based Cooja emulator to provide an insight into different RPL settings. The rest of this paper is organized as follows: Section 2 provides the previous related RPL implementations for the AMI networks. In Section 3, we proposed the RPL process, RPL control messages under the consideration of AMI and RPL objective function. Section 4 presents the experimental materials and network configuration steps. In Section 5, the measured RPL metrics and the deployed scenarios are investigated. In Section 6, the results of the practical implementation and simulated implementation are conducted followed by the future work and final conclusions in Section 7.