Before revision:  Further, we develop another simple greedy policy called Delay-based Server-Side-Greedy (D-SSG) with an even lower complexity O(n^2), and show that D-SSG achieves the same performance as D-QSG. Thus, we are able to achieve a dramatic reduction in complexity (from O(n ^5) of DWM \log n) of the hybrid policies } to O(n^2)) with a minimal drop in the delay performance.
After revision:  Further, we develop another simple greedy policy called Delay-based Server-Side-Greedy (D-SSG) with an even lower complexity O(n^2), and show that D-SSG achieves the same performance as D-QSG. Thus, we are able to achieve a dramatic reduction in complexity (from O(n ^{2.5 \log n) of the hybrid policies } to O(n^2)) with a minimal drop in the delay performance.