Adaptive Contention Window for Wireless Client Devices
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Solution Overview
Problem
Current binary exponential backoff procedures in wireless local area networks (WLANs) result in inefficient backoff times, leading to excessive 'dead air' time and compromised network performance, especially in small or low-traffic networks.
Innovation Solution
Client devices in WLANs monitor network conditions to determine if the network is small or low-traffic, and adjust their contention window range accordingly, reducing backoff times and 'dead air' time by setting a constrained contention window range when conditions allow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If binary exponential backoff procedure is used to handle collisions, then collision resolution is improved, but network throughput deteriorates due to excessive dead air time
Solution Approach 1:
The patent implements dynamic adjustment of the contention window size based on real-time network conditions. The system transitions from a static binary exponential backoff to a dynamic mechanism where the contention window is continuously adapted: reduced when the network is idle or small (to decrease dead air time), and increased when collisions are detected (to maintain collision resolution). This dynamic approach resolves the contradiction by making the backoff procedure adaptive rather than fixed.
Solution Approach 2:
The patent changes the parameter of contention window size based on network state. Instead of using a fixed binary exponential backoff, the system modifies the contention window parameter dynamically: setting it to a minimum value when the network is idle or small to reduce wait times, and increasing it when collisions occur. This parameter change strategy allows the system to optimize both collision resolution and network throughput under different operating conditions.
2Reliability
If average contention window is 7.5 (binary exponential backoff), then collision avoidance is improved, but network efficiency deteriorates due to 67.5 ms average backoff time
Solution Approach 1:
The system dynamically adjusts the contention window size rather than using a fixed average of 7.5. When the network is small or idle, the contention window is reduced to minimum values, significantly decreasing the average backoff time from 67.5 ms to much lower values. When collisions are detected, the window is increased to maintain collision avoidance. This dynamic adaptation resolves the time loss issue while preserving collision avoidance when needed.
Solution Approach 2:
The patent changes the contention window parameter from a fixed average (7.5) to a variable parameter that adapts to network conditions. The system sets the contention window to minimum values during idle periods and small network conditions, and increases it when collisions occur. This parameter change eliminates the excessive 67.5 ms average backoff time while maintaining adequate collision avoidance through conditional adjustment.
3Reliability
If contention window is increased after collision, then retransmission success is improved, but network productivity deteriorates due to extended wait times
Solution Approach 1:
The system dynamically adjusts the contention window for retransmissions based on current network conditions rather than always using the traditional exponential increase. When the network remains idle or light after a collision, the system can reduce the contention window for the retransmission, minimizing the productivity impact. The dynamic mechanism ensures retransmission success while reducing unnecessary wait times that would otherwise extend indefinitely under fixed exponential backoff.
Solution Approach 2:
The patent changes the retransmission contention window parameter from a fixed exponential increase to a conditional adjustment. Instead of always doubling the window after collision, the system evaluates network conditions and may reduce the window if the network is still idle or small. This parameter change maintains retransmission success probability while reducing the productivity loss from extended wait times in favorable network conditions.
Data Source
AI summary
A method and apparatus for reducing a contention window range of a client device located in a wireless network is described. In one embodiment, network conditions present in the wireless network are monitored. The network conditions are subsequently utilized to determine if the wireless network is small or if traffic in the wireless network is low. Afterwards, the contention window range of the client device is reduced if either of the wireless network is small or if the traffic in the wireless network is low.