Wireless Communication Apparatus Dynamic Contention Window Adjustment
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Solution Overview
Problem
In wireless communication systems using the CSMA/CA scheme, the contention window (CW) increases with retransmissions due to collisions, leading to prolonged time delays, especially in environments with many terminals, where the existing methods fail to guarantee delay times for data transmission.
Innovation Solution
A wireless communication apparatus that dynamically sets the contention window (CW) and arbitration inter-frame space (AIFS) based on the remaining time until a request delay time-outs, allowing for preferential transmission access by adjusting these values according to the time remaining until the data time-out, thereby reducing backoff times and collision probabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contention window (CW) is expanded to reduce collision probability, then collision avoidance is improved, but the backoff time increases and time delay is prolonged
Solution Approach 1:
The patent applies dynamics by making the contention window (CW) and arbitration inter-frame space (AIFS) adjustable rather than fixed. The wireless communication apparatus dynamically changes these parameters based on the remaining time until data time-out, allowing the system to adapt to different time constraints. When remaining time is short, the apparatus reduces CW and AIFS to minimize delay; when remaining time is abundant, it increases these values to reduce collisions.
Solution Approach 2:
The patent implements parameter changes by modifying the CW and AIFS values based on the remaining time until data time-out. The apparatus changes these critical parameters dynamically during the transmission process, reducing them when time is critical and increasing them when time is abundant. This allows the system to optimize between collision avoidance and time delay reduction based on real-time conditions.
2Reliability
If the CW range is increased to prevent collisions, then transmission reliability is improved, but the backoff time increases causing prolonged delay
Solution Approach 1:
The patent makes the CW range dynamic by adjusting it based on the remaining time until data time-out. Instead of using a fixed large CW range that always prevents collisions but causes long backoff times, the system dynamically reduces the CW range when remaining time is short, thereby reducing backoff time while maintaining sufficient collision avoidance for the given time constraint.
Solution Approach 2:
The patent changes the CW parameter dynamically based on time constraints. When remaining time is abundant, the system uses a larger CW range for better collision avoidance. When remaining time is short, the system reduces the CW range to minimize backoff time, accepting that some collisions may occur but prioritizing time efficiency over maximum reliability.
3Ease of operation
If existing CSMA/CA scheme is used, then simple operation is maintained, but delay guarantee for data transmission cannot be ensured
Solution Approach 1:
The patent extends the basic CSMA/CA scheme by adding dynamic parameter adjustment based on remaining time until data time-out. The apparatus monitors this time parameter and adjusts CW and AIFS accordingly, thereby guaranteeing delay performance for time-sensitive data while maintaining the fundamental simplicity of the CSMA/CA operation.
Solution Approach 2:
The patent introduces feedback by continuously monitoring the remaining time until data time-out and using this information to adjust transmission parameters. This feedback mechanism ensures that the system responds to time constraints and guarantees delay performance for data that requires it, while not complicating the basic transmission operation.
Data Source
AI summary
A wireless communication apparatus performs access control which starts transmission after a backoff time passes since an available state of a channel is detected through carrier sense, the backoff time being set based on a random value selected within a contention window width. The wireless communication apparatus includes a remaining time calculating unit which calculates a remaining time until a request delay time time-outs after data is generated, and a setting unit which sets the contention window width according to the remaining time calculated by the remaining time calculating unit.