Latency Reduction in High-Jitter Networks

Executive Summary

As part of Vector Space's ongoing initiative to optimize global content delivery, we conducted a comprehensive study on transport layer performance. This paper outlines our transition from standard TCP Cubic to a hybrid model utilizing BBRv3 and Multipath TCP (MPTCP). The goal is to mitigate the impact of "bufferbloat" in last-mile cellular connections.

1. The Problem: Packet Loss vs. Congestion

Legacy algorithms interpret packet loss as a signal of network congestion, triggering an aggressive reduction in transmission windows. However, in modern fiber and 5G networks, random packet loss is often physical, not congestive. Our telemetry data indicates that 45% of throughput degradation is caused by false-positive congestion avoidance triggers.

2. Experimental Data

We simulated a 200ms RTT link with 1% random packet loss. The chart below illustrates the "Time to First Byte" (TTFB) and sustained throughput recovery speed for different protocols.

3. Implementation Strategy

Based on these findings, we are deploying a "Smart Handover" mechanism. The client first attempts a 0-RTT QUIC handshake. If UDP blocking is detected (common in strict enterprise firewalls), the connection seamlessly falls back to TLS 1.3 over TCP with BBR enabled.

This hybrid approach ensures maximum compatibility while prioritizing performance for 90% of our user base.