Key Techniques And Performance Of Pdcch Channel For Broadband Wireless Trunking System

The project "Broadband Wireless Trunking System based on Time-Division Long-Term Evolution(TD-LTE)" (hereafter called "Broadband Wireless Trunking System") was proposed to meet the requirements in areas such as administrative management, public safety and large industry. The unique technical advantages of TD-LTE make it can meet the following demands of Broadband Wireless Trunking System:system response speed, coverage, anti-interference ability, safety performance, flexibility, and the adaptive capacity under different scenarios.The function of Physical Downlink Control Channel(PDCCH) in TD-LTE system is carrying the Downlink Control Information(DCI), including scheduling decisions of uplink or downlink, and power-control commands of User Equipment(UE), from eNode B to UE. Only the receiver detects DCIs accurately, can it demodulate other received information, then complete the process of scheduling of resource block, controlling of power and so on.At first, this paper introduces that DCI is categorized into different formats based on the contents it carries. In order to reduce the complexity of receiver, Control Channel Element(CCE) and four formats of PDCCH are introduced. Diagrams and tables are used to illustrate how PDCCH distributes in time-frequency resource blocks in Time-Division Duplex(TDD) frame format. Providing convenience for the blind detection at the receiving end, we divide available CCE resources into common search space and UE-specific search space according to Hash formula. Then, introducing how to process data in the level of bit and symbol at the transmitter and receiver. Combining with problems found during program simulation, we explain difficult points of each step. Finally, We focus on the research of blind detection schemes.The schemes of blind detection we have researched include the traditional scheme, the scheme using sliding correlation method only and the scheme combining energy detection method with sliding correlation method. Sliding correlation method can break the limit of different aggregation levels and search space categories in traditional method. It helps choose the first CCE by sorting positive correlation values. Therefore, this method can improve detecting efficiency. By eliminating<NIL> elements, energy detection method can narrow down the detecting field. By combining with sliding correlation method, it can improve detecting efficiency further. In this paper, we simulate the program of PDCCH link py using different blind detection schemes. Then we get the simulation results that Frame Error Ratio(FER) versus Signal-to-Noise Ratio(SNR), and average detecting number versus SNR. The results can verify that the scheme combining energy detection method with sliding correlation method can reduce the complexity of blind detection efficiently.