Wireless Channel Access for Low-Power Sensor Stations
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wireless communication systems, such as IEEE 802.11ah, face challenges in reducing power consumption for low-power stations like sensor devices due to long channel access delays and high power consumption when competing with devices having higher traffic loads, especially in sub 1 GHz bandwidth operations.
Innovation Solution
The EDCA access categories are redefined to prioritize low-power consumption stations by assigning them a new access category (SS) with an earlier contention window, limiting PPDU transmission time, and removing or reassigning voice and video categories to reduce power consumption and increase channel access efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low-power stations compete for channel access using standard EDCA categories, then channel access fairness is maintained, but power consumption increases and access delay lengthens
Solution Approach 1:
The patent introduces a new Access Category (AC_SS) specifically for low-power stations with modified EDCA parameters. The AIFSN value for AC_SS is set to 0, creating an earlier contention window that opens before other access categories. This parameter change allows low-power stations to access the channel with higher priority, reducing both their access delay and the time they need to monitor the channel, thereby reducing power consumption.
Solution Approach 2:
The patent segments the EDCA parameter set by creating separate parameter records for different station types. Specifically, it introduces AC_SS (Access Category for Sensor/Stations) as a distinct category from traditional voice, video, and best-effort categories. This segmentation allows low-power stations to use optimized parameters tailored to their low-duty-cycle operation, while other stations continue using standard parameters.
2Reliability
If low-power stations monitor the channel continuously for access opportunities, then channel access reliability is improved, but power consumption increases
Solution Approach 1:
The patent enables low-power stations to enter sleep mode during periods when their contention window is closed and wake up only when their contention window opens. By setting AIFSN to 0 for AC_SS, the system creates a periodic monitoring pattern where low-power stations wake up at specific intervals to check for channel access opportunities, rather than continuously monitoring. This periodic action maintains access reliability while dramatically reducing power consumption during idle periods.
3Reliability
If contention window size is increased for low-power stations to reduce collisions, then collision probability decreases, but access delay increases
Solution Approach 1:
The patent applies preliminary action by having low-power stations with AC_SS contend for channel access before other access categories. The AIFSN value of 0 for AC_SS causes its contention window to open first, allowing low-power stations to secure channel access before higher traffic-load stations become active. This preliminary contention resolves the contradiction by reducing collision probability through temporal separation while maintaining short access delays for low-power stations.
Data Source
AI summary
Embodiments may define traffic priorities to facilitate transmissions for wireless communications devices. Many embodiments comprise MAC sublayer logic to generate and transmit management frames such as beacon frames, association response frames, reassociation response frames, and probe response frames with an access category for low power consumption stations or sensor stations comprising a parameter record defining a contention window that is the earliest contention window to open amongst contention windows defined for the access categories for traffic. In some embodiments, the MAC sublayer logic may store the parameter record sets for access categories in memory, in logic, or in another manner that facilitates transmission of the frames. Some embodiments may receive and detect communications with frames comprising the access categories and store a parameter set for one or more of the access categories in a management information base.