DRCA Uplink Priority List for WLAN Contention-Free Access
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Solution Overview
Problem
The IEEE 802.11 channel access technology, specifically CSMA, experiences efficiency and throughput degradation in overloaded wireless local area network (WLAN) environments with numerous STAs and APs, leading to channel access efficiencies as low as 10-20% in high-demand scenarios.
Innovation Solution
A method for scheduled priority access in WLAN systems, where a station (STA) receives an Uplink Priority List (UPL) from an access point (AP), allowing it to determine its access order and transmit without contention during an Exclusive Priority Access (EPA) period, enabling contention-free access by waiting for preceding STAs to complete their transmissions and sending an indication to proceed with packet transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If CSMA is used for channel access in WLAN, then simple and fair channel access is provided in lightly loaded channels, but channel access efficiency and throughput degrade when the channel is overloaded
Solution Approach 1:
The patent applies preliminary action by having STAs register with the AP in advance and receive scheduled transmission opportunities through UPL updates. The AP maintains a registration list and proactively assigns transmission slots before contentions arise, allowing STAs to prepare and transmit without contention during their assigned EPA periods, thus resolving the efficiency degradation in overloaded channels while maintaining operational simplicity through centralized scheduling
Solution Approach 2:
The patent segments the channel access mechanism into two distinct phases: a scheduled priority access phase using EPA where registered STAs transmit without contention according to their UPL positions, and a traditional CSMA phase for other STAs. This segmentation allows the system to achieve high efficiency for registered STAs while preserving the simplicity and fairness of CSMA for non-registered STAs, effectively resolving the contradiction between simplicity and efficiency
2Quantity of substance
If the number of STAs and APs increases in the WLAN, then more users can access the network, but channel access efficiency drops to 10-20%
Solution Approach 1:
The patent applies preliminary action by requiring STAs to register with the AP in advance of their transmissions. The AP maintains a registration list and proactively assigns transmission slots through UPL updates before contentions arise. This allows the system to scale to many STAs and APs while maintaining high efficiency for registered STAs who transmit without contention during their assigned EPA periods
Solution Approach 2:
The patent introduces the AP as an intermediary that maintains a centralized registration list and coordinates EPA allocations. The AP receives registration requests from STAs, manages the UPL, and distributes scheduled transmission opportunities. This intermediary role enables the system to handle large numbers of STAs and APs efficiently by centralizing the scheduling function, preventing the efficiency degradation that would otherwise occur with increased network density
3Productivity
If scheduled priority access with EPA periods is implemented, then channel access efficiency improves significantly, but system complexity increases compared to traditional CSMA
Solution Approach 1:
The patent applies universality by designing the EPA mechanism to be compatible with existing CSMA operations. The system can simultaneously support both scheduled priority access for registered STAs and traditional CSMA for non-registered STAs. The AP maintains the registration list and UPL while STAs can optionally register to receive EPA allocations, allowing the system to achieve high efficiency where needed while preserving simplicity elsewhere, thus reducing the overall complexity burden
Solution Approach 2:
The patent applies self-service by allowing STAs to autonomously register with the AP and receive their UPL positions without requiring complex centralized control for each transmission decision. Once registered, STAs independently know their EPA transmission opportunities and can transmit without contention during their assigned slots. This self-service approach reduces the control overhead and system complexity compared to fully centralized scheduling, while still achieving high channel access efficiency
Data Source
AI summary
A method and apparatus are disclosed for enabling high-efficiency communication in wireless local area network (WLAN) systems. A station (STA) may receive an Uplink Priority List (UPL) from an access point (AP). In one example embodiment, a STA may send a request for prioritized access to an AP. The STA may then receive an ordered queue of STAs granted contention free prioritized access in a predetermined time interval, which may be referred to as the Exclusive Priority Access (EPA) period. The STA may then determine whether it is identified in the ordered queue of STAs granted prioritized access. The STA may then access a medium such as a Carrier Sense Multiple Access (CSMA) wireless medium associated with the IEEE 802.11 network, in turn with other STAs in the ordered queue per the queue order during the predetermined time interval using an inter-frame spacing, thereby enabling contention free access.