Multiuser power and bit allocation over power line channels

In this paper the power lines are studied as a multi-user environment for data transmission. The aim of the multi-user optimization problem is the minimization of the aggregate transmitting power when several constraints are fulfilled. The optimum but computationally not efficient system is simulated and analyzed. A FDMA system, which is a typical multiuser system, is also applied over the same power line channels. Then several suboptimal schemes but with reduced complexity are simulated and analyzed in detail. A new suboptimal multiuser system is proposed and compared to the others in terms of normalized transmission power per bit for several data loads and constant BER. The proposed system outperforms the suboptimal competitors, increasing slightly the system's complexity. The main gist of the new algorithm is that the weak users are delayed whereas the strong users are accelerated. That means that the weak users have to store their data for short periods of time in buffers and transmit them later when the strong users have achieved to transmit their own bits and thus liberate their own subchannels.