7月23日下午，在新主会议中心第三会议室举行了本学期第二次WorkShop，本次WorkShop的主题是UDN，刘婷婷老师和苏立焱师兄为我们做了报告。

报告人：刘婷婷
题目：超密集网络中干扰协调:方法及性能分析
摘要：
在超密集网络中，全频复用能够提升网络的平均吞吐量，但严重的小区间干扰限制了边缘用户数据率的提升。如何有效地管理超密集网络中的干扰、提升边缘用户数据率是重要的研究问题。本文研究超密集网络中两种有代表性的干扰协调方法，随机干扰协调和以用户为中心的干扰协调方法，推导了两种方法边缘用户数据率和最优复用因子，分析了基站用户密度、天线个数等系统参数对性能的影响。  

报告人：苏立焱
题目：On Energy Efficiency and Spectral Efficiency Joint Optimization of Ultra Dense Networks
摘要：
Deploying ultra dense networks is a major trend in the evolution of cellular networks, where the number of base stations (BSs) may exceed the number of users. In this paper, we investigate energy and spectral efficient frequency reuse strategies in PPP cells, where BS sleeping is allowed for a cell without active users. Toward this goal, we derive the closed form expression of the energy efficiency (EE) and spectral efficiency (SE), and find the optimal frequency reuse strategies that maximize the EE and SE, respectively. Our analyses show that full frequency reuse is SE-optimal for cellular networks with all ratios of BS to user density, but is EE-optimal only for some BS-user density ratios. Simulation results validate our analysis and illustrate the EE gain with typical BS-user density ratios.