Wireless Outstation Trigger Framing for Scheduled Uplink Sync
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Solution Overview
Problem
Fixed wireless access networks using Wi-Fi standards face challenges in accommodating pre-determined time division duplex schedules, limiting the use of commercially available chipsets and preventing efficient operation of features like Triggered Uplink Access (TUA) due to varying propagation distances and times.
Innovation Solution
A wireless outstation generates a locally triggered frame based on a predetermined time division duplex schedule, allowing simultaneous uplink message transmission by outstations, using MU-MIMO and OFDMA, and providing the trigger frame directly to the receiver circuit, bypassing over-the-air reception from the access point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed wireless access network uses pre-determined time division duplex schedule, then efficient operation is achieved, but compatibility with Wi-Fi standards is lost
Solution Approach 1:
Instead of the access point generating trigger frames and transmitting them to outstations (conventional Wi-Fi approach), the outstation locally generates trigger frames based on pre-determined TDD schedules. This inversion of the trigger frame generation role allows the system to maintain Wi-Fi compatibility while implementing efficient TDD scheduling, as the outstation can precisely control uplink transmission timing according to the network schedule.
2Ease of operation
If trigger frames are transmitted from access point to outstations, then uplink messages can be triggered, but only a limited range of propagation times can be tolerated
Solution Approach 1:
The outstation pre-calculates and applies timing advance values based on its distance from the access point and the pre-determined TDD schedule. By generating the trigger frame locally with embedded timing advance information, the system compensates for propagation delays before transmission occurs, enabling outstations with widely varying propagation times to synchronize their uplink messages at the access point without requiring the access point to transmit trigger frames that would be subject to propagation delay variations.
3Loss of time
If uplink messages are triggered by receipt of trigger frame from access point, then transmission timing can be controlled, but simultaneous reception at access point is difficult with wide propagation time range
Solution Approach 1:
Each outstation independently generates its own trigger frame locally based on the pre-determined TDD schedule and its specific propagation time characteristics. This self-service approach allows each outstation to autonomously adjust its transmission timing using timing advance values, ensuring that uplink messages from outstations with different propagation times arrive simultaneously at the access point during the designated uplink time slot, thereby improving both timing control and simultaneous reception reliability.
Data Source
AI summary
A wireless outstation is operated in a fixed wireless access network comprising an access point and a plurality of wireless outstations, the wireless outstation comprising a receiver circuit configured to receive a message from the access point comprising a trigger frame to trigger transmission of an uplink message from the wireless outstation. The trigger frame is generated at the wireless outstation based on a predetermined time division duplex schedule and the generated trigger frame is provided as an input to the receiver circuit.