Improve WFQ to implement PDS and its performance analysis

After analyzing the disadvantage of the WFQ (weighted fair queueing), an algorithm to implement the PDS (proportional differentiated service), a new algorithm, called measurement-based WFQ to overcome standard WFQ's shortage is proposed. Compared with two available algorithms to implementing PDS, BPR (backlog-proportional rate) and WTP (waiting-time priority), the simulation result shows that M-WFQ can provides better QoS than BPR, WTP and WFQ in the normal situation, and can overcome the high class service burst.