A Roadside Downlink Wireless Transmission Scheme Using OFDM and Virtual MIMO

In this paper, a downlink wireless transmission scheme is proposed for roadside deployment. The scheme is based on orthogonal frequency-division multiplexing (OFDM) technology, and it also employs virtual multiple input multiple output (MIMO) to further improve system capacity. In the "virtual" MIMO scheme proposed in this paper, signals can be sent from two base stations (BS) to one user, which creates a virtual MIMO system that may offer additional capacity gains in fading channels. This scheme is especially fit for the bi-sectional BSs with zonal coverage along roadside. Simulation results show that the proposed scheme can support both high and low speed users on road, and achieve a high system capacity gain especially in the cell edge. Within this scheme, the OFDM symbols are characterized into two groups: localized resource group (LRG), which is continuous in time-frequency (TF) domain; and distributed resource group (DRG) which is TF discrete. As LRG is fit for low-speed users to utilize the slowly varying channel while DRG is fit for high-speed users with rapid varying channels, the combination of them makes the allocation of OFDM subchannel more elastic to support users with different speed