CF-End Indication in Wi-Fi HE Frames
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Solution Overview
Problem
Existing Wi-Fi communication protocols incur increased power consumption and overhead due to coarse virtual carrier sensing and the need for additional CF-End frames to release NAV protected time, which can reduce battery life and network efficiency.
Innovation Solution
Incorporating a CF-End indication in the MAC header or preamble of frames, specifically in the HE SIG-A field, to cancel previously specified NAV protected time, allowing for more precise control over channel availability and reducing unnecessary transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional CF-End frames are transmitted to release NAV protected time, then channel availability is accurately updated, but overhead and power consumption increase
Solution Approach 1:
The patent combines the CF-End indication with existing frame structures by setting the More Data field to a specific value (e.g., 1) in the MAC header or using the HE-SIG-A field in the physical layer preamble. This merging approach allows the CF-End function to be conveyed within already-transmitted frames, eliminating the need for separate CF-End frame transmissions and reducing overall overhead and power consumption.
Solution Approach 2:
The patent makes existing frame fields serve multiple functions: the More Data field in the MAC header or the HE-SIG-A field in the physical preamble not only indicates whether more data follows but also conveys CF-End information when set to specific values. This multi-functionality reduces the need for dedicated CF-End frames while maintaining accurate channel availability indication.
2Productivity
If CF-End frames are transmitted to free up remaining NAV protected time, then channel utilization is improved, but network overhead increases
Solution Approach 1:
The CF-End indication is merged into existing frame structures (MAC header More Data field or HE-SIG-A field), allowing the CF-End function to be conveyed within frames that are already being transmitted for data communication. This eliminates the need for additional standalone CF-End frames, reducing the total number of frames in the network while maintaining improved channel utilization.
Solution Approach 2:
Existing frame fields are given universal functionality to indicate both data continuity (original More Data function) and channel availability status (CF-End function) through specific value settings. This reduces frame quantity by making already-transmitted frames serve dual purposes.
3Adaptability or versatility
If legacy CF-End frame transmission is used, then compatibility with legacy devices is maintained, but power consumption and overhead increase
Solution Approach 1:
The patent applies different communication approaches based on the capabilities of the communicating devices. HE-capable devices use the integrated CF-End indication in the HE-SIG-A field or More Data field, while legacy devices continue to use traditional CF-End frames. This local quality approach ensures compatibility with legacy devices while reducing power consumption and overhead for modern HE-capable devices.
Solution Approach 2:
The More Data field and HE-SIG-A field are designed to serve multiple functions: they maintain backward compatibility by using established field names and formats, while simultaneously enabling CF-End indication through specific value settings. This universality allows the same field structure to serve both legacy compatibility and power-efficient operation for HE-capable devices.
Data Source
AI summary
An electronic device that transmits a frame to a second electronic device is described. In particular, during operation, an interface circuit in the electronic device (such as an access point in a WLAN) may transmit the frame to the second electronic device using a Wi-Fi communication protocol. The frame may include information cancelling a previously specified NAV protected time in a preamble of the frame. For example, the information may include a CF-End indication. Moreover, the information may be included in a MAC header of the frame and, more generally, in a preamble of a high efficiency (HE) physical layer convergence protocol (PLCP) protocol data unit (PPDU). Furthermore, the electronic device may transmit the frame in response to a block acknowledgment (BA) from the second electronic device.