Frame Transmission Efficiency-Based Cross-Layer Congestion Notification Scheme in Wireless Ad Hoc Networks

Area of Science:

• Computer Science
• Networking
• Wireless Communication

Background:

• Wireless ad hoc networks experience transmission congestion primarily due to medium contention, unlike wired networks.
• Effective transport protocol design requires utilizing MAC layer congestion states to adjust transmission rates.
• Existing cross-layer congestion detection methods are often too complex or inaccurate for practical deployment.

Purpose of the Study:

• To propose a novel, accurate, and deployable congestion metric for wireless ad hoc networks.
• To design and implement a transport protocol support scheme that leverages this new metric for congestion control.
• To improve network goodput in wireless ad hoc networks by efficiently managing transmission rates.

Main Methods:

• Introduced 'frame transmission efficiency' as a new metric, defined as the ratio of successful transmission delay to frame service delay, to characterize medium contention.
• Developed RECN (Explicit Congestion Notification and frame transmission efficiency), a scheme adjusting transport sending rates via standard ECN signaling.
• Integrated RECN transparently with TCP in NS2 simulations without modifying end hosts or requiring complex switch firmware updates.

Main Results:

• The proposed frame transmission efficiency metric accurately and rapidly reflects medium contention.
• RECN effectively adjusts transport sending rates based on detected congestion.
• Experimental results demonstrated a remarkable improvement in network goodput across multiple concurrent TCP flows using RECN.

Conclusions:

• RECN provides an efficient and accurate solution for congestion control in wireless ad hoc networks.
• The scheme is deployable on commodity switches with minimal updates and no end-host modifications.
• RECN significantly enhances network performance, particularly goodput, in environments with concurrent TCP flows.