Medium access control protocols for improving data communication reliability in PLC systems

Abstract

The present thesis provides a comprehensive survey regarding the state of the art of medium access control (MAC) protocols for power line communication (PLC) systems, including an overview of existing PLC MAC research results and an organization of current PLC MAC protocols in terms of type of protocols, applications, and main research focus. Moreover, the survey presents modern PLC technologies and standards, highlighting their MAC sublayer characteristics and providing a detailed comparative analysis of PLC MAC protocols in the context of current and emerging PLC applications. Then, future trends are identified within the scope of the MAC sublayer for PLC systems with a view to stimulating additional research efforts on PLC MAC design. In addition, the present thesis proposes a generic approach that may improve the data communication reliability through packet corrections at the link layer level. Based on this generic approach, the present thesis also proposes EPLC-CMAC, an enhanced cooperative MAC protocol for in-home broadband PLC systems. More specifically, the cooperative protocol performs relayed retransmissions according to the relay availability, for assisting data communication between source and destination nodes. In case a packet retransmission fails, the destination node uses corrupted copies from the transmitted and the retransmitted packets, which are stored in its buffer, to detect and correct the erroneous bits. Numeric results show that the use of the EPLC-CMAC protocol is capable of reducing the packet loss ratio even during impulsive noises, improving the data communication reliability of the considered scenarios. Finally, but not the least, the present thesis propose EHCMAC, an enhanced cooperative MAC protocol for in-home broadband hybrid PLC-wireless systems. After unsuccessful transmissions, the EHCMAC protocol tries to correct corrupted packets, at the link layer, before performing the retransmission request. In case this correction fails, the EHCMAC protocol exploits relay availability for retransmitting packets and, when the relay assistance is not enough to ensure successful retransmission, a second packet correction attempt is applied at the link layer. The performance evaluation of the EHCMAC protocol is accomplished by comparing in-home broadband hybrid power line communication-wireless systems that consider the use of the proposed protocol with in-home broadband hybrid power line communication-wireless systems in which the proposed protocol is not considered. Numerical and theoretical results show that the use of the proposed protocol is capable of remarkably reducing the need for packet retransmissions and the packet loss ratio. More specifically, as the bit error ratio at the link layer decreases, these results tend to zero faster when the EHCMAC protocol is considered.