Research On The Key Technologies Of Cellular Controlled D2D Communication System

With the development of science and technology, the wireless communication system has been developed from the first generation to the third generation (3G), and the long term evolution of UMTS (LTE) has been developed and the fourth (4G) is in study, too. Especially, in the past several years, LTE has been developed to compete with WiMAX (Worldwide Interoperability for Microwave Access) for customers, LTE changes a lot to conventional 3G structure, aim to bring wireless mobile communication towards broadband access.More and more users are attracted to wireless communication area, and the customer's request for the communication service is higher and higher, business opportunities is brought with the pressure of limited spectrum and the longing for new service. At the same time, with more and more services in terminal machine, the energy content of battery is used up quickly, while the energy growth rate can't keep up with that of depletion rate, so low energy consumption service is expected. Based on the instruction of wireless cellular communication system, Device-to-Device(D2D) communication system is introduced, which is a local short range communication technology, and it can make data transmitted between terminals directly without eNodeB (eNB) while only control signaling existed between eNB and users. Thus combine cellular communication and D2D system can get higher total capacity, better time latency, and lower energy consumption and save cellular spectrum, etc.This paper aims to study LTE based cellular controlled D2D communication system, and according to the content, the article is divided as follows.(1) First and the basic work is to introduce the research benchmark, it is the development of cellular communication, especially introduced LTE and its related core technologies and requirements and so on.(2) Analysis the concept of D2D communication system and its work model, introduce the key technology such as the setup procedure, the interference between D2D and cellular system, the adaptive TDD uplink downlink slots allocation, the retransmission in D2D cluster, etc.(3) Lastly, the author gives some simulator results and analysis, which prove that the proposed retransmission method can reduce the retransmission times and improve system improvement.