Research On Downlink And Uplink Decoupling In Heterogeneous Cellular Networks

Mobile communication has been going through a huge revolution in last decades. From 2G to 3G, from LTE to the next generation cellular network (5G), network structure is changing and new technology is emerging. Today's cellular network is a heterogenous and complicated one, with various Base Stations and intelligent devices in it. We need to not only meet the requirement of high quality service, but also reduce energy consumption. Downlink and Uplink Decoupling (DUDe), the stragety that we research on, is proposed under such background. DUDe can improve service quality as well as reduce energy comsumption by reasonably allocating users.We first introduce and compare several popular cell association schemes that in use, including Signal to Interference and Noise Ratio based scheme, Reference Signal Received Power based scheme, Reference Signal Received Quality based scheme, Biased-based Cell Range Expansion and Associaton based on Almost Blank Sub-frame.The main part of the paper focuses on the performance DUDe has in heterogenous cellular network. We first introduce DUDe's principle. Then basing on stochastic geometry, we derive the rate and energy efficiency coverage probobality formulas in heterogenous cellular network with DUDe and show their correctness by simulations. The results also show that DUDe can improve network's uplink rate and energy efficiency coverage while leaving downlink unchaged.Then we do some further research on DUDe by changing network parameters, including density of Base Stations and users, power control of user's transmit power and distribution of Base Stations and users. We analize the reasons of DUDe's performance change with the parameters' change and draw the conclusion that DUDe can be inplenment to cellular network no matter what the canditios are.At last, we make a summary about our research and point out some potential derections for future work.