Q13Mobile Computing
Question
What are the challenges faced by Mobile Transport Layer? Explain Snooping TCP.
Answer
Mobile Transport Layer faces high error rates, frequent disconnections, and varying delays. Snooping TCP buffers packets at the base station to retransmit locally without notifying the sender.
Traditional TCP assumes packet loss is due to network congestion and reduces its transmission window. In mobile networks, packet loss is often due to high bit error rates and frequent handoffs, causing standard TCP to unnecessarily throttle throughput. Snooping TCP addresses this by introducing a 'snooping' agent at the base station. The agent buffers data packets sent to the mobile host and monitors acknowledgments (ACKs). If it detects a missing ACK or duplicate ACKs indicating a lost packet, it retransmits the buffered packet locally to the mobile node and drops the duplicate ACKs to prevent the fixed sender from reducing its congestion window.