Just as Dickens wrote,it is the best of times,it is the worst of times.Ever increasing traffic demands will bring us into the era of 5G.Vast of unprecedented or even unanticipated fancy wireless applications will definitely change our life.Regarding the beautiful visions promised by 5G,meanwhile the wireless engineers are faced with unprecedented challenges and pressures for realizing much higher spectrum efficiency and energy Just as Dickens wrote, it is the best of times, it is the worst times. Ever rising traffic demands will bring us into the era of of 5G. Last of the unprecedented or even unanticipated fancy wireless applications will definitely change our life. Regarding the beautiful visions promised by 5G, meanwhile the wireless engineers are faced with unprecedented challenges and pressures for realizing much higher spectrum efficiency and energy