Point-to-point FDD microwave can be a fastto- install and cost-effective backhaul solution for mobile small cells. However, its applications have been held back, because the state-of-the-art static backhaul deployment fails to capture drastically fluctuating small cell traffic. To address this issue we introduce a new adaptive backhaul architecture that is able to adapt to changing small cell traffic. Extended from a graph theoretic clique idea, the architecture allows changes to the overall backhaul topology, and it also allows each individual backhaul link to vary its frequency to meet traffic demand. Guard bands are adaptively reserved between some of the links to suppress adjacent-frequency interference, while being efficiently used by other links for data transmission. Our case study of 10 small cells confirms that the adaptive architecture is able to increase the small cell throughput by 75 percent compared to the static backhaul architecture. It can also reduce the backhaul bandwidth requirement by 57 percent, and enhance small cells¿ satisfaction by 158.4 percent with respect to their allocated bandwidths.