Interference Coordination Technology In LTE System

long term evolution (LTE), which is the evolution of 3G technology,is one of the current wireless communication technologies. In the physical layer, LTE system uses Orthogonal Frequency Division Multiplexing(OFDM) and Multiple Input and Multiple Output(MIMO) technologies; In additional, LTE system has a new network architecture instead of Radio Network Controller (RNC) node. This "revolution" makes LTE system lose most backward compatibility with 3G systems. Therefore, the existing interference cancellation technologies no longer apply to it, which makes the study of interference in LTE system becomes a hot issue, including the interference in data channels and control channels.In data channels, the interference mainly comes from neighboring cells in LTE system. So inter-cell interference coordination (ICIC) technologies are adopted to reduce the interference, including overload indicator (OI) and high interference indicator (HII) methods. Using OI or HII separately will incur inevitable shortcomings. In this paper, an OI&HII hybrid scheme is proposed for ICIC uplink through signaling interaction between the two schemes. The simulation results show that this new scheme can get a better system performance through effectively enhancing the uplink throughput and reducing the signaling overhead on the X2 interface at the same time.In control channels, TD-LTE system can support various special sub-frame configurations. In some scenarios, due to the transmission delay, interference between the pilot time slots of different cells exists, affecting the system performance. In this paper, we separately analyze this kind of interference when normal CP or extend CP is adopted. To avoid this interference, we propose three methods which can avoid the interference adaptively through adjusting the length of GP instead of shifting UpPTS to data time slots. The numerical results show that the proposed scheme can effectively avoid the recurrence of this interference and make the uplink receiving more accurately.