Null Data Packet Protected Access Window Synchronization
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Solution Overview
Problem
Current WiFi wireless networks face inefficiencies in medium access control due to differences in operating standards, leading to interference and contention issues between legacy and high-efficiency devices, particularly in implementing protected access windows and synchronization signals.
Innovation Solution
The implementation of a protected access window (PAW) in IEEE 802.11ax networks using a synchronization signal with a null data packet frame, which includes a legacy signal field indicating the duration of the transmit opportunity period, allowing devices to determine when the medium is busy and preventing interference by deferring transmissions during this time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a protected access window is implemented using a null data packet frame with a legacy signal field, then interference between legacy and high-efficiency devices is reduced, but the device complexity increases due to the need to generate and process specialized synchronization signals
Solution Approach 1:
The null data packet frame with legacy signal field acts as an intermediary mechanism that bridges legacy and high-efficiency devices. The synchronization signal embedded in the null data packet frame serves as a mediator that legacy devices can detect and interpret through their existing legacy signal field processing, while high-efficiency devices can recognize and respond to the protected access window indication, thereby reducing interference without requiring complete system redesign
Solution Approach 2:
The null data packet frame structure is designed to serve multiple functions simultaneously: it acts as a synchronization signal for high-efficiency devices, provides a detectable legacy signal field for legacy devices, indicates protected access window boundaries, and enables transmit opportunity allocation. This multi-functionality reduces interference while avoiding the need for separate specialized signaling mechanisms that would increase device complexity
2Productivity
If the legacy signal field indicates the duration of the transmit opportunity period, then medium access control efficiency is improved, but the adaptability decreases because legacy devices cannot interpret the protected access window concept
Solution Approach 1:
The patent uses a copy of the legacy signal field format within the null data packet frame to convey duration information. Legacy devices interpret this copied field according to their existing protocols, while high-efficiency devices recognize the same field as indicating protected access window duration. This copying approach improves medium access control efficiency for both device types without requiring legacy devices to understand the protected access window concept, thereby maintaining adaptability
Solution Approach 2:
The interpretation of the legacy signal field parameter is changed contextually: for legacy devices, it represents a standard duration field, while for high-efficiency devices, it represents the protected access window duration. This parameter reinterpretation allows improved medium access control efficiency through unified duration indication while preserving adaptability through context-dependent interpretation rather than requiring explicit protected access window understanding from legacy devices
Data Source
AI summary
An access point including a generation module, a transceiver, and an acknowledgment module. The generation module is configured to generate a synchronization signal. The transceiver is configured to (i) transmit the synchronization signal to a station, (ii) receive a medium access control protocol data unit based on the synchronization signal during a transmit opportunity period for the station. The acknowledgment module is configured to generate an acknowledgment signal based on the reception of the medium access control protocol data unit. The synchronization signal or the acknowledgment signal includes a null data packet frame. The null data packet frame includes a legacy signal field. The legacy signal field comprises a length of a portion of the null data packet frame subsequent to the legacy signal field. The transceiver is configured to transmit the acknowledgment signal to the station.