Interference Analysis For M2M Communications On Unlicensed Band

With the rapid social development, people’s requirements for communic ations increase accordingly. 5G is supposed to meet the communication requirements. The mobile network and the Internet of Things(Io T) are the two main driven elements for 5G. The development of e-Health, VNet, smart home, smart industry and smart environment has put forward the usage of Io T, with billions of devices connected to the Internet. The realization of Io T depends on an efficient communication architecture that covers all types of human and machine involved communications, human-to-human, human-to-machine and machine-to machine(M2M).M2M communications, which are also referred to as machine-type communications(MTC) make the world more efficiently connected. M2 M communications can work both on licensed band and unlicensed band. However, only using cellular network is inefficient for M2 M communications. The reason is that the number of M2 M communication devices is large. Non-cellular methods should serve as the supplement and extension for cellular networks. Obviously, the main challenge for M2 M communications on unlicensed band is the interference from other networks operating on the same band. Thus, the main purpose of this paper is to analyze the interference of M2 M communications on unlicensed band, based on which, a channel allocation mechanism is proposed to minimize the interference of the whole network for M2 M communications on unlicensed band.Bit error rate(BER) and packet error rate(PER) are two important indicators when we are analyzing the network performance of interferer-existing systems. BER is the base to analyze PER. Thus, firstly the BER analysis model is constructed to calculate the BER of desired network when interfering transmitters exist. Based on the BER model, the PER value of the interfere-existing systems is analyzed, from the aspects of homogeneous and heterogeneous networks, respectively. Based on these two scenarios, different models are constructed to analyze the PER value. Then, simulations of these two models are constructed to prove the effectiveness of the proposed models.There is severe interference of M2 M communications on unlicensed band, which occurs not only within the same network but also between different networks. With the increasing of user number, the influence of the interference will increase accordingly. Thus, it is an important research topic to design interference avoidance mechanism, so that the interference both from the same and the other networks can be mitigated. In this paper, the optimization problem for channel allocation is established based on the graph theory. Two scenarios, i.e., high-density users and low-density users, are discussed, respectively. Then, graph traversal algorithm and Tabu searching algorithm are used to solve this problem, so that the optimal channel allocation method is obtained.