Research On The Technologies Of Interference Management In Wireless Heterogeneous Network

Nowadays, mobile data services are developing rapidly. Multi-mediabusiness and smart phones are increasing continuously. The current wirelessindustry is faced with a huge challenge. Wireless heterogeneous network isregarded as a most effective and inexpensive technology to solve theproblems. Based on physical layer cell structure, heterogeneous networkdeploys multiple transmitting nodes including macro and low-power basestation, for example relay, pico, femto and so on, which increases thespectrum reuse rates and network capacity. According to users’ location andservice type, different cells are accessed in, which ensures the service ofcentral users and cell-edge users. Therefore, heterogeneous network is apower technology that increases the network throughput and service coverage.The task of interference management is to maximize network capacity andtransmission reliability. Effective interference management can improve theutilization of radio resources and quality of service. With the development ofwireless communication, interference management technology has beenapplied for different networks and the evolution scenarios. For4G network,interference management contains precoding, inter cell interferencecancellation and so on.For a point-to-point communication, relay system is the base constructionof hete-net. Interference management in a relay system can improve thecapacity of a single link, the error rate and the spectrum efficiency.For a real cellular communication, small cell system is the baseconstruction of hete-net. For the reason that several small cells are deployedin a cellular, the blind spot problem in homo-net is solved, which increase thenetwork throughput and capacity. At the same time, inter cell interference is becoming more serious. Therefore, interference management is the key toensure service quality.In the research of multi-hop bidirectional relay system, this papercombines two-way relay and multi-hop relay system, solving the scenario ofexchanging data between a long distance user and a macro cell. In this paper,precoding technology is used to get the target of interference management.For the target of minimizing mean square error and ensuring relay transmitpower constraint, the precoding problem is modeled. Since the originalproblem is non-convex, we decouple it into three convex problems andpropose an iterative algorithm to get an optimal solution. Numericalsimulation verifies the outstanding bit-error-rate for the reason thatinterference caused by channel fading and noise has been effectivelyinhibited.In the research of cognitive two-way relay system, this paper extends thetraditional models, which enables the pair of primary users and secondaryusers exchange data at the same time. To solve the problem of the seriousinterference on macro cell and primary user caused by the pair of secondaryusers, this paper designs two interference management schemes. The first oneis to design the relay precoding matrix for target of minimizing the transmitpower. The optimal solution is obtained by using semi-definite relaxationtechnique and CVX package. Interference has been inhibited and the overallnetwork capacity is ensured. The second scheme is to design the relayprecoding matrix for target of maximizing the SINR on secondary users.Using binary search method, the optimal solution is obtained. This schemeconsiders the communication quality of secondary users when cancelling theinterference. Numerical simulation verifies the correctness and feasibility ofthese two schemes. The effect of interference management is verified and thenetwork capacity and communication reliability are ensured.In the research of dynamic TDD small cell system, this paper studies theopportunities and technical challenges of dynamic TDD small cell systems.Faced with serious interference situation, this paper proposes cell clustering and uplink power control schemes to eliminate interference. Through buildingTD-LTE system level simulator, these two schemes are verified effectively.The system interference is controlled and overall network capacity isincreased rapidly.