Research On Eicic Technique And Performance Simulation Of PDCCH In HetNet

Heterogeneous Network (HetNet) has been changing the traditional homogeneousnetwork which has a simple network topology. The introduction of Low Power Nodes(LPNs) which have low power and small physical size, not only provides moreflexibility in range decision, eliminates coverage holes of homogeneous network, butalso improves the capacity of the hotzones. HetNet has been chosen as a key techniquein the LTE-A.The gap of transmit power between the macro base stations and LPNs results inan unbalanced load. In order to compensate this disadvantage, a concept of Cell RangeExpansion (CRE) is introduced in the HetNet. The CRE allows more users to access toLPNs, offloading macro cell’s traffic. As a result, User Equipments (UEs) in the CREarea suffer severe interference from macro base stations. Enhanced Inter-cellInterference Coordination (eICIC) has been proposed to resolve this problem.The Physical Downlink Control Channel (PDCCH) carries the Downlink ControlInformation (DCI) which contains information about the resource allocation of UEs,and some other control information. One or more UEs’ DCIs can be transmitted on onePDCCH. And the performance of PDCCH directly affects the communication qualityof the entire system. So the requirement of performance for PDCCH is always rigorous.As the HetNets have changed the original topology of network, inter-cell interferencebecomes more serious, the control channel is also subjected to stronger interferencefrom the macro base station, and a serious loss in performance is brought about.Therefore, this dissertation studies the eICIC technique and evaluates theperformance of PDCCH in the HetNets. Specific studies are as follows:Chapter Ⅰ describes the research background and the two research points whichthis dissertation focuses on, introduces the concepts of HetNets and downlink physicallayer protocols of LTE, and defines the research content and the structure of thedissertation.Chapter Ⅱ outlines the system-level simulation platform of the eICIC techniquebased on3GPP LTE R10version, including the architecture of platform, the design rules of parameters and system modules. Then, the platform is calibrated.Chapter Ⅲ researches the eICIC technique in HetNets. Firstly, the importance ofthe eICIC technique in HetNets is illustrated, three technical methods of eICIC areintroduced, and the advantages and disadvantages of this three options are analyzed,Almost Blank Subframe (ABS) scheme is chosen as the object of research. Secondly,the ABS scheme is investigated and the research method of the dissertation is defined.Then the ABS scheme is implanted into the system-level simulation platform, and thethroughput of user in each cell and the system is evaluated. Simulation results provethat ABS can improve the performance of cell edge UEs.Chapter Ⅳ researches PDCCH in HetNets. Firstly, some relevant concepts ofPDCCH and the process of sending and receiving are introduced, a PDCCH systemmodel in HetNets is given, a link-level simulation is built, performance of four formatsof PDCCH in HetNets is evaluated. Then the link-level curve is combined with thesystem-level one to analyze capacity by using the probability theory. Secondly,combining the Reference Signal Received Power (RSRP) cell selection scheme withthe Path Loss (PL) one, a cell selection algorithm is proposed based on adaptivecoverage radius to improve the performance of location-based cell selection scheme.This algorithm can adaptively adjust the size of the coverage radius according to thelocation and the interference level of LPNs. And then performance of the proposedscheme is evaluated by analyzing capacity. Simulation results show that this algorithmcan improve the capacity of PDCCH. Finally, Enhanced-Physical Downlink ControlChannel (E-PDCCH) is introduced.The dissertation is summarized in Chapter Ⅴ, and the possible research directionsin the next stage will be indicated.