| Applications over PLC networks have drawn much interest in the academic community as well as in the communication industry, not only because of inherent convenience (connecting PLC-capable devices requires no new wires), but also because almost all electrical devices have to connect to a power outlet eventually. This technology makes implementing a digital home entertainment center more realistic than ever. HDTVs in different rooms are now able to share digital content from one set-top box without rewiring, or setting up wireless access points. MP3 players can access music data through PLC networks from different rooms playing different music. PLC networks provide enabling technologies for the smart home.; However, PLC technology is still evolving and many problems remain unsolved. The hostile environment of PLC channels makes reliable data transmission difficult. The PLC channel is known for its hostile nature in transmitting electrical signals. Protocols designed for other media may not be suitable for PLC. In some ways, PLC channels are similar to wireless channels: both of them face hidden node problems, near-far effects and other channel imperfections. However, PLC network nodes tend not to move. It is unlikely that simply applying protocols designed for another medium would result in good performance in the PLC environment; the overhead may be too high or the assumptions about noise may be too optimistic for PLC networks.; In light of PLC's unique characteristics, we developed a new protocol called: Periodic Contention-Free Multiple Access (PCF/MA). PCF/MA is an explicit R-ALOHA-like protocol specifically designed for the PLC network. We propose an RTS/CTS-like scheme in the reservation stage to mitigate hidden-node problems, and a delayed NACK mechanism to conquer the near-far effect.; Performance of the proposed protocol is evaluated by event-driven computer simulations and by mathematical analysis. Simulation results show that 85 Mbps MAC throughput with a 100 Mbps channel data rate can be obtained, even when there are hidden nodes in the network. To provide smooth video delivery, we propose a mathematical estimation of the required delay in playback time and the amount of playback buffer with tight bandwidth reservation. Our simulation shows that a 100 Mbps channel can deliver up to 9 MPEG-2 video streams simultaneously without dropping any video frames. A visual protocol analyzer was also developed as a tool to study network protocol. |
