WLAN Access Point Virtual Channel Scheduling for Uplink Multi-User Transmission
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Solution Overview
Problem
In wireless local area networks (WLANs), existing medium access control mechanisms struggle to efficiently manage uplink multi-user transmission (UL MU transmission) due to the lack of effective medium protection mechanisms, leading to inefficiencies in resource allocation and collision avoidance.
Innovation Solution
The proposed solution involves an access point (AP) sending a request to send (RTS) frame to multiple stations (STAs), receiving clear to send (CTS) physical layer protocol data units (PPDUs) with additional training fields, and transmitting an UL transmission indication frame to schedule UL frames across overlapping time resources, allowing STAs to send frames on allocated resources while minimizing collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If one STA occupies all transmission resources through one channel to send/receive a frame to/from an AP, then collision avoidance is achieved, but resource utilization efficiency deteriorates
Solution Approach 1:
The patent segments the transmission resources by introducing multiple virtual channels (VC0, VC1, VC2, VC3) within a single physical channel. Each virtual channel can be independently allocated to different STAs, allowing simultaneous transmissions without collision. The AP manages these virtual channels and assigns them dynamically based on transmission needs, thereby maintaining collision avoidance while significantly improving resource utilization efficiency.
2Productivity
If multiple STAs transmit frames on overlapped time resources, then resource utilization efficiency is improved, but collision risk increases
Solution Approach 1:
The patent introduces virtual channels as an intermediary layer between multiple STAs and the shared physical channel. The AP acts as a mediator that assigns specific virtual channels to specific STAs for their transmissions. This intermediary mechanism allows multiple STAs to transmit on overlapped time resources while preventing collisions through virtual channel isolation, thereby achieving both improved resource utilization and maintained reliability.
3Reliability
If an RTS frame is sent to a plurality of STAs with NAV setting information, then medium protection is achieved, but the ability to enable simultaneous UL transmission deteriorates
Solution Approach 1:
The patent dynamically adjusts the NAV setting mechanism based on the transmission scenario. When simultaneous UL transmission is desired, the AP sends RTS frames with selective NAV settings that protect only the specific time resources needed for each STA's transmission, rather than blocking the entire medium. This dynamic adaptation allows the system to maintain medium protection for scheduled transmissions while enabling simultaneous UL transmissions from multiple STAs by carefully controlling which resources are protected.
Data Source
AI summary
Disclosed are a method and a device for receiving a frame in a wireless LAN. A method for receiving a frame in a wireless LAN comprises the steps of: an AP transmitting an RTS frame to a plurality of STAs, wherein the RTS frame comprises information for NAV setting of an STA other than the plurality of STAs; the AP receiving from each of the plurality of STAs, as a response to the RTS frame, a CTS PPDU and an additional CTS PPDU on overlapped time resources; and the AP transmitting an uplink transmission indication frame to the plurality of STAs, wherein the uplink transmission indication frame triggers transmission of an uplink frame of each of the plurality of STAs.