Network-Supported TCP Rate Control for High-Speed Power Line Communications

The high-speed power line communications (PLC) technology has great potential to serve as an infrastructure for home networking because every home electric device must be connected to a power line network. However, various special environmental factors, such as power level attenuation, divergence between different voltage lines (100/200 V), and fluctuations of source impedance and noise by other equipment, often severely degrade the communication performance. In the present paper, we focus on the flow-level performance of end-to-end data transmission (i.e., TCP) over PLC line with various negative environmental factors, which has not been well investigated so far. We first develop a new module on the NS-2 network simulator, which is driven by the information on time-varying packet error rate over PLC line prepared beforehand, to simulate the High Definition (HD)-PLC´s data transmission including some dedicated mechanisms against degradation caused by the environmental factors. The simulator is validated by comparing the TCP performance obtained from experiments on a real HD-PLC network and that from simulations using the packet error rate information measured in the real environments. Next, we address a problem on co-existing multiple TCP flows over PLC line and then, as a solution, propose a new and practical network-supported TCP rate control scheme in which the sender-side PLC modem modifies the advertised window (awnd) in TCP ACK packets for controlling the TCP´s sending rate in response to the PLC line condition. The simulation results demonstrate the effectiveness of the proposed scheme.