Since traditional congestion control algorithm cannot fulfill the requirements of current complex networks

Google provides a new way named bottleneck bandwidth and round-trip (BBR) for congestion control. The purpose of BBR is to maximize throughput and minimize delay on a bottleneck link with packet loss

but it has some disadvantages: First

when the delay of wireless network is severely jittered

even if there is no packet loss or congestion

the delivery rate of BBR is very low. This issue has not been raised in previous studies. Second

BBR is not sensitive enough to the bandwidth drop. This paper analyzes the causes of the above problems in detail and proposes an optimized BBR

which can judge the jitter degree of network by comparing the mean and standard deviation of RTT. When the jitter of delay was severe

the mean RTT was used instead of minimum RTT to calculate congestion window. When the network was unstable

the length of stationary phase in PROBE_BW was reduced. Experiments in the real network showed that the optimized BBR was almost unaffected by delay fluctuations

and could maintain high bandwidth utilization when BBR could hardly work. Besides

it could detect bandwidth degradation and converge faster than BBR when the network was unstable.