RLC Layer AM Mode Research And Design In LTE

With the emergence and popularity of wireless terminal etc. smartphone, the demand for mobile service was unprecedented big. The fusion of broadband access and mobile telecommunication became an inevitable trend. In order to take the leading position in competitive telecommunication field, the 3rd Generation Partnership Project(3GPP) proposed long term evolution(LTE) in 2004. Several new releases were proposed after and Release 12 already frozen. Radio Link Control(RLC) layer belonged to Layer 2 of LTE protocol stack, mainly delivering signaling and data from Packet Data Convergence Protocol(PDCP) layer to Media Access Control(MAC) layer, or from MAC to PDCP. Error data could be retransmitted in Acknowledge Mode(AM). With the increase of data process load, processing of transmitting, receiving and retransmitting should be more reasonable and effective. If so, service waiting delay and packet loss would be reduced significantly, while system throughput would be improved. Therefore, the study of RLC layer was still of great value.In this paper, basic concept, development history, system architecture and protocol stack architecture were introduced. Key technology of Physical layer was analyzed. Scheduling and multiplexing in MAC layer were studied, and logical channel between MAC layer and RLC layer was anatomized.The main function, data formats and implementation process of RLC layer were researched. Aiming at Un-acknowledgement Mode(UM), an improved method of reordering window was proposed. Based on the reason that retransmission of Protocol Data Unit(PDU) could not be concatenated, this paper put forward to a scheme which can make full use of resource by combining scheduling and multiplexing in MAC layer. Simulation and analysis were done, which shows that comparing with traditional scheme, resources utilization achieves the optimal state, servive throughput increases and packet loss rate reduces. The scheme is suitable for the scenario with bad channel state. Finally, program design and implement of data packet and reassembly was done, improving practical value of this paper. Test result indicates that the program is correct.