Inter-cell Control Channel Interference Rejection For Downlink TD-LTE Systems

In order to satisfy people’s increasing demand for High Speed in wireless network,3GPPproposed HSPA and LTE. Many researches show that50%of voice and70%of data servicesare indoors in the wireless communication. The building penetration loss at2GHz in indoorenvironment is about20dB for concrete material. In consinderation of penetration loss, themacrocell providing indoor coverage is very bad. Especially in complex urban environment,the cost of macrocell coveraging indoor is very high as the buildings block desired signal.Enhancing the macrocell transmitter power for improving indoor user performance will resultin more serious inter-cell interference and more power consumption. Home NodeB hasintroduced into the3rd generation mobile system and Home eNodeB has also introduced intothe LTE system to realize the Indoor coverage. Home NodeB and Home eNodeB are alsoknown as femtocell.Heterogeneous network is a trend of network deployment in the future, using macrocelloutside and using femtocell inside. One of the most important problems in HetNet is inter-cellinterference. PDCCH is the control channel in LTE to transmit DCI, such as schedulinginformation of PDSCH and PUSCH, TPC, acknowledgement messages, et al. The conventionalalgorithms to restrain the inter-cell interference such as FFR can not be used in control channeldirectly. So we focus on how to restrain the control channel interference between cells.This paper first introduces physical layer structure, the time-frequency resources andnetwork deployment in LTE system. On the basis of3GPP protocol and related literatures, thispaper researches the sending and receiving process of PDCCH, analyzes the main cause ofPDCCH interference between cells, and studies possible method to restrain PDCCHinterference between cells. Based on summary of existing methods of restraining PDCCHinterference between cells, this paper brings forward a new algorithm to suppress controlchannel interference between cells, and gives an implementation scheme based on the algorithm.Finally, verify the performance of the algorithm and scheme with MATLAB simulationexperiment.