Preemption Techniques for High Priority Wireless Packets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless local area networks (WLANs) based on IEEE 802.11 standards, high priority (HP) packets often face delays due to busy communication links resulting from ongoing uplink or downlink activities, such as frame bursts or transmission opportunities (TXOP).
Innovation Solution
A method implemented by a first wireless device to transmit HP packets by identifying the busy link, generating a preemption request message, and associating it with a frame, which is then transmitted to a second wireless device. This involves encoding the preemption request in various frames, such as QoS-Null, QoS Data, or management frames, and using mechanisms like trigger frames, reverse direction grants, or contention-free end messages to allocate resources for HP packet transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wireless device waits for the communication link to be free before transmitting high priority packets, then the link stability is maintained, but the transmission delay of high priority packets increases
Solution Approach 1:
The patent sends a preemption request message before the actual high priority packet transmission to secure channel access in advance. The receiving device responds with a preemption response, and the transmitting device sends a preemption confirmation to finalize the channel reservation, allowing immediate transmission without waiting for the current link to naturally become free.
Solution Approach 2:
The preemption request message includes a preemption indicator that actively interrupts or cancels the ongoing low priority transmission. This preliminary anti-action prevents the current transmission from completing, thereby clearing the channel for high priority packets before they arrive, resolving the contradiction between maintaining link stability and reducing transmission delay.
2Speed
If the system implements preemption mechanisms for high priority packets, then the transmission speed of critical data improves, but the device complexity increases
Solution Approach 1:
The preemption mechanism is segmented into distinct functional components: preemption request message with specific indicators, preemption response message, and preemption confirmation message. Each component has a specific function, making the overall complex mechanism manageable and implementable through modular protocol handling in wireless devices.
Solution Approach 2:
The patent uses structured message formats with specific fields (preemption indicator, preemption confirmation indicator) as intermediaries to coordinate the preemption process. These standardized message structures act as mediators between the transmitting and receiving devices, simplifying the interaction protocol while enabling fast preemption operations.
3Adaptability or versatility
If the system uses preemption request messages with multiple encoding options, then the adaptability to different transmission scenarios improves, but the difficulty of detecting and measuring the correct encoding increases
Solution Approach 1:
The patent employs different encoding methods for preemption request messages based on the specific transmission scenario: encoding in A-Control subfield for certain frame types, encoding in PPDU preamble for others, and encoding in multi-STA BA for multi-user scenarios. Each encoding location is optimized for its specific context, improving adaptability while maintaining clear local decoding rules that reduce overall complexity.
Data Source
AI summary
A method for transmitting a high priority (HP) packet from a first wireless device to a second wireless device is described. The method includes determining the presence of an HP packet for uplink transmission; determining that a communications link that uses a wireless medium for transmitting the HP packet is busy; generating a preemption request message in a frame; and transmitting the frame with the preemption request message to the second wireless device. The first wireless device can receive from the second wireless device an indication that the preemption request was accepted, such as by receiving a trigger frame with resource allocation for transmitting the HP packet or an indication of the end of a contention free period, to allow the first wireless device to contend for channel access to transmit the HP packet.