An AQM based Congestion Control for eNB RLC in 4G/LTE Network

In the context of a heterogeneous mobile environment, we analyze the eNodeB (eNB) Radio Link Control (RLC) buffer overflow problem for the 4G/LTE network, and show the benefits of deploying Active Queue Management (AQM) strategies at wireless access links. In order to satisfy the increasing demands of wireless mobile communications, LTE has been proposed as an all-IP-based network to bring higher peak data rates and better spectral efficiency. One of the LTE system performance optimization points is the RLC buffer management mainly at the downlink. RLC buffers at the eNB hold user data before it is selected by a MAC scheduler for transmission over the radio interface. A buffer management scheme is required to keep the RLC buffer occupancy to a minimal level without a noticeable degradation in user application performance. This is a challenging issue for the mobile network operator and has to be thoroughly investigated. When the traffic load is low, the available bandwidth is underutilized and when the traffic load is high, the end-to-end delay becomes large. This paper presents a minimal adjustment to RED called Smart RED (SmRED) in which the packet dropping probability is adjusted based on the traffic load to achieve optimal end-to-end performance. Additionally, the migration from RED to SmRED in a real network needs very little work because of its simplicity. Finally, for a delay sensitive data stream, a cross layer approach based on SmRED is proposed to make it more practical.