Downlink capacity optimization in a heterogeneous home area network with application to smart grid

This paper studies the optimization problem of total downlink capacity in heterogeneous multiuser Home Area Network (HAN) for Smart Grid application, where beamforming technique is employed at the smart meter. Based on the proposed system model, an optimal downlink power allocation scheme is proposed under the constraints that 1) each user should satisfy individual signal to interference noise ratio (SINR) requirement for successful heterogeneous communication; 2) the sum of transmit power allocated to each user is equal to the permissible total transmit power at the smart meter; 3) allocated transmit power to each user is feasible. By employing the theorem that the sum of independent exponentially distributed random variables follows Erlang distribution, the probability distribution function (PDF) of the smallest allocated transmit power is mathematically obtained from the properties of downlink indoor Saleh-Valenzuela (S-V) channels. Numerical results show that the total downlink capacity is greatly enhanced by the proposed power allocation scheme. Furthermore, numerical results validate the contribution of beamforming technique at the smart meter on capacity optimization.