PFCS: Pre-buffering-aware Flow Control Scheme for LTE-Advanced Relay Networks

Abstract

Relay technology is one of the techniques proposed to enhance the capacity of Long Term Evolution-Advanced (LTE-A) networks. In an LTE-A relay network, each serving relay node has to store packets for its mobile users and forward the remaining packets to another node during handover. However, increasing the number of forwarded packets will result in the degradation of the users throughput. Flow control and prebuffering schemes are the two main schemes proposed to reduce the number of forwarded packets in LTE-A relay networks. Existing studies assumes the two schemes are independently operated. However, ignoring the effect of buffer overflow at the pre-buffering queue in a flow control scheme may result in ineffective operation. This paper presents a pre-bufferingaware flow control scheme (PFCS) for an LTE-A relay network that jointly considers the effects of both flow control and prebuffering schemes. The proposed PFCS can significantly improve user's throughput by preventing both buffer overflow and buffer underflow of the local queue at the serving relay node and minimizing the number of forwarded packets. Simulation results show that the PFCS can provide a better throughput than the traditional flow control schemes because the effect of the prebuffering scheme can minimize the number of forwarded packets.

Adaptive Receiver-Window Adjustment for Delay Reduction in LTE Networks

“…In order to boost the traffic level in the network, the receiver has to intimate the sender to immediately increase the data traffic generation rate in the network based on the rwnd value. e rwnd value is in the range of 101 to 120, and once the sender receives the rwnd value, it does further computation to increase (19) if ((current_time − last_time) > targetperiod) or (counter > targetcounter) then (20) datarate � totaldata/totaldelay (21) currentpercentage � (datarate/datarate max ) × 100% 22Diffpercentage � 100% − currentpercentage (23) if Diffpercentage ≥ limit high then (24) rwnd � (Diffpercentage − limit low ) (25) else if (Diffpercentage ≥ limit low ) then (26) rwnd � (Diffpercentage − limit low ) × (Diffpercentage − limit low /limit high − limit low ) (27) else if (Diffpercentage ≤ lowest) then (28) rwnd � (lowest − Diffpercentage) + 100 (29) end if (30) Avoiding aggressive reduction in congestion window size (31) if ((current_time − last_time) < targetperiod) and (rwnd < 100) then (32) if rwnd > oldrwnd then (33) rwnd � rwnd − oldrwnd (34) oldrwnd � rwnd (35) else (36) oldrwnd � rwnd (37) end if (38) else (39) oldrwnd � 0 (40) end if (41) last_time � current_time (42) totaldata � totaldelay � counter � 0 (43) end if (44) end procedure ALGORITHM 1: Network congestion estimation at the receiver side.…”

“…To avoid queue overflow problem, the service providers have installed large capacity buffers (queue) in the eNodeB owing to the reduction in memory price [14]. During congestion in the network, the enormous amount of packets start accumulating in the large queue space at eNodeB and wait for the resources to be allotted [29,30]. is leads to increase in packet delivery time which adversely affects the delay sensitive applications known as bufferbloat problem [13].…”