Radio-over-Radio: I/Q-stream backhauling for cloud-based networks via millimeter wave links

Cloud-based centralized processing is one approach to improve mobile networks in terms of capacity, energy consumption, utilization, and cost. However, some joint processing techniques envisioned for such cloud-based networks require the backhauling of received symbols, usually in the form of an I/Q-stream, which requires a drastically higher data rate on the backhaul link than the backhauling of decoded user data. Until recently, the required data rate could only be provided by fiber and not by wireless links, which could be deployed easier and at lower cost. In this paper, we propose the concept of Radio-over-Radio by extending the popular Radio-over-Fiber approach to wireless millimeter wave links. We analyze the characteristics of the new concept and give first results on a joint optimization of the wireless access and backhaul links by means of joint coding under a data rate constraint on the backhaul.