Modeling MAC Layer for Powerline Communications Networks

The usage of electrical power distribution networks for voice and data transmission, called Powerline Communications, becomes nowadays more and more attractive, particularly in the telecommunication access area. The most important reasons for that are the deregulation of the telecommunication market and a fact that the access networks are still property of former monopolistic companies. In this work, first we analyze a PLC network and system structure as well as a disturbance scenario in powerline networks. After that, we define a logical structure of the powerline MAC layer and propose the reservation MAC protocols for the usage in the PLC network which provides collision free data transmission. This makes possible better network utilization and realization of QoS guarantees which can make PLC networks competitive to other access technologies. The protocol proposals are considered to make possible both data and voice transmission with a higher priority for the voice connections. The remaining network capacity is used for data transmission which is expected to be internet traffic as a typical service applied to the PLC access networks. A simulation model is developed for the investigation of the PLC MAC layer which includes also modeling of different disturbance scenarios. We choose two variants of MAC protocols which can be applied to the signaling part of a reservation MAC protocol and implement them in the simulation model. An ALOHA protocol, which allows collisions in the signaling channel, and a fixed access method, realized by a collision-free polling access schema, are compared as two opposite protocol solutions. We compare a PLC network without disturbance influence and a network affected by the disturbances for both implemented MAC protocols. Network utilization, access delays and throughput are observed during the simulations for various sizes of transmitted packets.