We discusse PLC efficiency when multiple users contend for the medium. To resolve contention conflicts, PLC uses carrier sense multi- ple access with collision avoidance (CSMA/CA) on the MAC layer. The stations have to sense the medium before they transmit, and to wait for a random interval of idle-medium time slots before they transmit. The PLC CSMA/CA protocol is similar but more complex than that of Wi-Fi. We present the IEEE 1901 CSMA/CA protocol and certain MAC-layer processes, such as the priority resolution for QoS classes, inter-frame spaces, and frame aggregation. We discuss the new features of HomePlug AV2 compared to IEEE 1901 and the differences between Wi-Fi and PLC MAC layers.

We introduce an experimental framework for PLC.We explain how to configure PLC devices and how to measure certain statistics, such as the capacity of the links, packet errors, modulation information, and collision statistics. We rely on PLC management messages and on open-source tools. We give examples of these messages and guidelines on employing the tools. We also explain how to develop new custom PLC tools.