Contention Window Adjustment for Priority Data Streams
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Solution Overview
Problem
Current wireless industrial automation systems face inefficiencies in resource utilization and reliability guarantees, particularly in contention-based systems, where unpredictable traffic patterns and varying network sizes lead to bandwidth wastage and packet collisions, especially affecting real-time traffic with strict timing deadlines.
Innovation Solution
A method for accessing a shared communication channel using contention-based access, where communication devices select non-overlapping time intervals for data streams based on priority, with shorter intervals for higher-priority streams to ensure earlier access and adapt transmission windows based on real-time traffic requirements, thereby prioritizing real-time traffic and optimizing resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contention-based access is used to adapt to dynamic traffic patterns, then resource utilization improves, but packet collisions increase and reliability guarantees are lost
Solution Approach 1:
The patent segments the communication channel access into different time intervals (first time interval for first data stream, second time interval for second data stream) to separate high-priority and low-priority traffic. This temporal segmentation reduces packet collisions by ensuring that high-priority data streams get access during their designated intervals without interfering with low-priority traffic, thus maintaining reliability while allowing contention-based access for resource efficiency.
2Device complexity
If same access priority is given to all traffic, then system simplicity is maintained, but real-time traffic with strict timing deadlines cannot be guaranteed
Solution Approach 1:
The patent applies local quality by assigning different access priorities to different data streams based on their characteristics. High-priority data streams (real-time traffic) are granted access during first time intervals with shorter durations, while low-priority data streams (non-real-time traffic) access during second time intervals. This differentiated quality of service ensures real-time guarantees for critical traffic without overly complicating the overall access control mechanism.
3Ease of operation
If longer time intervals are used for low-priority traffic, then channel access fairness is improved, but latency for high-priority real-time traffic increases
Solution Approach 1:
The patent implements periodic action by establishing regular alternation between first time intervals for high-priority data streams and second time intervals for low-priority data streams. This periodic scheduling ensures that high-priority traffic receives consistent, timely access to maintain low latency, while low-priority traffic still gets periodic opportunities for fair channel access. The periodic structure prevents starvation of either traffic type while prioritizing real-time requirements.
Data Source
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AI summary
Method for accessing, by a communication device (200), a shared communication channel in which contention based access to the communication channel is used, by multiple devices with traffic of different priority. The communication device is configured to transmit data streams with different transmission priorities via the shared communication channel with a first data type stream having a higher transmission priority than a second data type stream. For each type of traffic, a different set of parameters are specified and applied during the contention access (clear channel assessment), this being related to the contention window (minimum ad maximum values), which allows to determine the waiting time before accessing the shared medium, as well as to the duration of the transmission time eventually granted. The method identifies various adjustments of these parameters. In principle, the time range for the first data type traffic is lower than the time range for the second data type traffic. In case second data transmissions takes place but a packet has only being transmitted partially, the maximum value of the corresponding time range is reduced. In other scenarios, in case of congestion of the shared medium, maximum time range values are increased. Further, parameters such as the minimum value of the time range or else the granted transmission window for the second data type traffic are adjusted according to the load and requirements associated to the first data type traffic.