<title>Performance comparison of reservation MAC protocols for broadband powerline communications networks</title>

Efficient scheduling for PLC networks

“…Channel selection: We use and compare two mechanisms for channel selection in our study. The first mechanism is similar to that used in [4,5] and is named uniform channel selection in this Letter. With the use of this mechanism, each terminal which needs to access the medium selects uniformly one of the 15 channels (one for signalling and 14 for data transmissions); the only constraint is that selection is made among channels which have at least one idle slot in the current channel frame (no transmission is scheduled in that slot from previous channel frames).…”

“…Relevant research on the MAC layer for PLC has focused more on in-home networking [2,3]. The work presented in this Letter focuses on the 'last mile' problem, and introduces scheduling ideas which lead to significant improvements in network performance and user Quality of Service (QoS) compared to the Extended ALOHA [4,5] protocol, for powerline communication networks.…”

“…However, we do not use the adaptive backoff mechanism proposed in [4,5] for users to select the slot in which they will transmit=retransmit their requests; instead, we propose three new ideas, two regarding the slot selection mechanism and one regarding the channel selection mechanism for a PLC access network.…”

“…We consider an OFDM transmission system which uses a number of subcarriers distributed in a frequency spectrum. The work presented in [4,5] proposed three extensions of the basic ALOHA protocol in order to improve its performance on the PLC network: (a) piggybacking, which leads to a decrease in the signalling delay; this is defined as the time needed for the realisation of the requesting procedure for the transmission of a packet and includes the transmission of a request message to the base station and the reception of its response regarding the access rights; (b) use of data channels for signalling (from [7]); (c) application of an adaptive backoff mechanism for user access to the signalling channel, as well as for user access to the data channels for signalling purposes.…”

“…Proposed scheduling scheme: Orthogonal frequency division modulation (OFDM) has been outlined as one of the best candidates for application in PLC systems with higher data rates, because of its excellent bandwidth efficiency [4][5][6]. We consider an OFDM transmission system which uses a number of subcarriers distributed in a frequency spectrum.…”