Downlink Multiplexing Module Design And Algorithm Research In LTE Base Station

In order to be in a better position to mobile communication technology in thefuture increasingly fierce competition, meet the increasing diversification of businessrequirements, the3rd Generation Partnership Project (3GPP) organization launchedthe advanced mobile communication technology development plan-LTE/SAE projectin2004. Compared with3G system, LTE abrogated the dedicated channels and was infavor of shared channel for data transmission. As one of the important modules ofdownlink shared channel, whether the function of multiplexing is good or not willdirectly affect the overall performance of the system. The protocol stack structure andfunctions in the protocol are described in detail, however the implementation of theprotocol stack on base station side is left. Therefore the research on the stack on basestation side becomes necessary.This article mainly aimed at the multiplexing of downlink shared channelmodule, designed and improved the function of multiplexing module framework andadded multiplexing algorithm. The multiplexing module on the MAC layer of thedownlink Shared channel has been designed detailedly, it was divided into twomodules, the queue management module and the traffic shaping function module. Theformer is responsible for the functions of users’priority computing and the cache datapacket processing, the latter is responsible for the allocation of resources in order tocontrol the flow’s output. The module firstly calculated the priority of the data flowsthat sent from high-level logical channel for business units to get the service sequencein the downlink data sending. Secondly the module considered limited buffer, eachdata flows will be assigned to a separate storage area, at the same time, the packet lossmechanism is adopted to prevent buffer overflow occurs. Finally，the allocation ofresource was finished by the processing of traffic shaping. After the above treatment,the same user’s data was ultimately multiplexed to the same MAC PDU.Finally this article put forward a method to calculate the priority to improve theexisting calculation method of the priority. The new algorithm considered therelationship between the initial allocation of resources and the data for transmission,through the secondary allocation for time-frequency resources, to improve theefficiency of resource utilization. Simulation results show that the new algorithmimproves the cell throughput, reduces the packet loss rate and the system time delay,and guarantees the fairness of the business at the same time.