L2Relay Wi-Fi Packet Relay Protocol for Range Extension
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Solution Overview
Problem
Wi-Fi network range extension solutions, such as commercial range extenders and academic research prototypes, often degrade network performance or require complex modifications to nodes and access points, limiting their applicability and effectiveness.
Innovation Solution
The L2Relay protocol, which selectively repeats packets only when necessary, operates within the Layer 2 data link layer to monitor channel conditions and adapt rates, allowing for seamless integration into existing Wi-Fi networks without modifying access points or nodes, thereby enhancing network range without performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If commercial range extenders repeat all packets to extend network range, then network coverage is improved, but network throughput is degraded due to unnecessary rebroadcasting and poor channel conditions
Solution Approach 1:
The relayer performs partial action by selectively repeating only those packets that were not successfully received by the destination node. The relayer monitors for missing ACKs and only rebroadcasts packets when necessary, avoiding unnecessary repetitions that would degrade throughput while still providing coverage extension where needed.
Solution Approach 2:
The relayer uses feedback mechanisms by monitoring for ACK packets from destination nodes to determine whether packets were successfully received. When an ACK is not detected within a timeout period, the relayer infers packet loss and triggers retransmission. This feedback-driven approach ensures efficient use of network resources while maintaining throughput.
2Productivity
If academic research prototypes implement intelligent relay algorithms to improve network performance, then network throughput is improved, but device complexity and installation difficulty increase due to required modifications to nodes and access points
Solution Approach 1:
The relayer operates as a self-service device that autonomously monitors packet transmissions, detects missing ACKs, and triggers appropriate retransmissions without requiring configuration or modification of existing network nodes. The relayer independently manages its own relay decisions based on observed channel conditions, eliminating the need for complex centralized control or node modifications.
Solution Approach 2:
The relayer acts as an intermediary device between the access point and destination nodes, absorbing the complexity of intelligent relay algorithms in itself rather than requiring modifications to the access point or client nodes. This intermediary approach allows sophisticated packet management functionality to be added to the network without increasing the complexity of existing components.
3Reliability
If relayers repeat packets at low rates due to poor channel conditions to ensure delivery, then packet delivery reliability is improved, but network throughput is degraded
Solution Approach 1:
The relayer dynamically adapts its transmission rate based on observed channel conditions and packet delivery success. When channel conditions are poor and packet loss is detected, the relayer lowers its transmission rate to improve reliability. When conditions improve, the relayer increases the rate to maximize throughput. This dynamic rate adjustment resolves the contradiction between reliability and productivity.
Solution Approach 2:
The relayer changes operational parameters (transmission rate, retransmission timing) based on feedback from packet delivery observations. By adjusting these parameters in response to channel conditions, the relayer optimizes both packet delivery reliability and network throughput, avoiding the need to operate at consistently low rates even when channel conditions deteriorate.
Data Source
AI summary
L2Relay is a novel packet relay protocol for Wi-Fi networks that can improve the performance and extend the range of the network. A device running L2Relay is referred to as a relayer, which overhears the packet transmissions and retransmits a packet on behalf of the Access Point (AP) or the node if no acknowledgement is overheard. L2Relay is ubiquitously compatible with all Wi-Fi devices. L2Relay is designed to be a layer 2 solution that has direct control over many layer 2 functionalities such as carrier sense. Unique problems are solved in the design of L2Relay including link measurement, rate adaptation, and relayer selection. L2Relay was implemented in the OpenFWWF platform and compared against the baseline without a relayer as well as a commercial Wi-Fi range extender. The results show that L2Relay outperforms both compared schemes.