In future fifth-generation (5G) cellular networks, distributed multiple-input multiple-output (MIMO) technology will be applied such that much more challenges on efficient resource allocation to user equipment (UE) of high access density are raised in order to support their high mobility among different micro-/pico-cells. In this chapter, we propose a framework to enable an optical back-haul cooperation among different optical network units (ONUs) with distributed MIMO technology in wireless front-haul for next-generation optical-wireless cellular networks. Specifically, our proposal is featured by a downlink resource multi-cell sharing scheme for OFDMA-based passive optical network (PON) supporting radio-over-fiber (RoF). We first consider system architecture with the investigation of related works, and then we propose a co-channel interference mitigation and delay-aware sharing scheme for real-time services allowing each subcarrier to be multi-cell shared by different ONUs corresponding to different micro-/pico-cells. Furthermore, a heuristic algorithm to mitigate co-channel interference, maximize sharing capacity, and minimize network latency is given by employing the graph theory to solve such sharing problems for future 5G. Moreover, simulations are performed to evaluate our proposal.