Downlink Logical Channel Multiplexing Design And Algorithm Research In LTE

With the development of mobile communication, the demand of high rate andwide bandwidth is more and more urgent. It needs to innovate. So LTE emerged. LTEcould provide much higer data rate than3G, because of its key technologies andreasonable structure design. Compared with3G standards, LTE simplifies thetransmission channel. It means that LTE modifies the transmission channel fromdedicated channels to shared channels. LTE introduces many key technologies, suchas Multiple Acess, MIMO, Link Adaptation and so on. The main contents include thedownlink logical channel multiplexing framework design and the improvement oflogical channel multiplexing algorthim of LTE base station in this paper.Firstly, it needs to design the downlink MAC layer of base station, because thereare only the requirements of indices, none of implementation recommends in3GPPstandard. So DL-SCH includes three main parts in the downlink MAC layer. They arelogical channel multiplexing, scheduling and HARQ. The working process is that datafrom upper layer through logical channel multiplexing can be queued and assembledto Protocol Data Unit (PDU), according to the transmission block size decided byscheduling. There are multiple processes in HARQ and the PDU is sent to Physicallayer though it.Scecondly, this paper designs logical channel multiplexing of Downling SharedChannel in detail, puts forward the Priority Queue and the Traffic Shapping in logicalchannel multiplexing, and simulates them. Compared with LTE frame without logicalchannel multiplexing structure, it allocates the Resource more effectively, canimprove the delay of real-time Traffic about4.8dB in good condition, and makes theaverage user satisfaction more than0.8. But the primitive structure strives to maintain0.6.At last, it is improved the algorithm in logical channel multiplexing structure.Thealgorithm is called logical channel multiplexing algorithm, including the PriorityQueue and the Traffic Shapping. Through analyzing the althorithm, one of the ogicalchannel multiplexing algorithm, the Priority Queue is improved. The QoS factors areconsidered in the improved algorithm. At the same time, the formula derivation isgiven. The simulation results show that the improved algorithm reduces the delay andimproves the data rate of the real-time traffic.