Transmission delay control for single frequency OFDM multi-base-station in a cell using position information

In this paper, a system with "multi-base-station in a cell" using single frequency network (SFN) orthogonal frequency division multiplex (OFDM) is proposed as a basic concept of the 4th generation mobile system (4G). The proposed system image consists of several cells in a larger cell and it works as follows: first, a sub-base station (S-BS) is set to transmit partially at the place where the received signal power is below the desired one, because of increase of path loss while operating at high frequency, and under shadowing; secondly, base stations (BSs) and S-BSs transmit the same information at the same time by SFN-OFDM, so paths having in good condition may exist. However, at a receiver the timing offset in arrival between paths of BSs and S-BSs leads to inter-symbol interference (ISI) which is the largest considerable problem. So a "transmission delay control" scheme using position information from the Global Positioning System (GPS) is also proposed. We discuss the usefulness of the proposed system against path loss increase and shadowing, and furthermore confirm that the proposed scheme is effective in operation at high speed rate.