A Novel Adaptive Fuzzy Logic Controller (A-FLC) to Reduce Retransmission and Service Roundtrip Time for Logical TCP Channels over the Internet

The novel Adaptive Fuzzy Logic Controller (A-FLC) proposed in this paper is created from the extant FLC model by adding the capability that allows it to auto-tune the range-thresholds of its “don’t care” fuzzy regions. The aim is to “squeeze” the range-threshold to achieve two purposes: a) to make the controller more responsive, and b) to reduce overshoot/undershoot to yield a less oscillatory control process. The range-threshold reduction process works with two parameters: “gradient threshold” and “given percentage”. The former decides when to begin the reduction process and the latter decides by how much. The preliminary results with the Java-based A-FLC prototype over the Internet indicate that the auto-tuning capability in the novel controller indeed makes the buffer overflow management more responsive, less oscillatory, and more accurate than the FLC predecessor.