Relay Data Unit Delivery Through Selective Out-of-Order Forwarding
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently relaying data units with low latency and reliability, particularly in scenarios where reorder buffers cause delays due to missing data units, especially in IEEE 802.11 networks with relay stations.
Innovation Solution
A first station receives frames from a second station, including data units and an indication on whether to transmit a second data unit before a first data unit, based on the capabilities and conditions of a third station, allowing for out-of-order delivery to enhance data unit forwarding to higher layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data units are transmitted in strict in-order sequence through relay stations, then reliability of data delivery is improved, but latency increases due to reorder buffer delays when data units are missing
Solution Approach 1:
The patent inverts the traditional in-order delivery approach by enabling out-of-order delivery of data units at relay stations. Instead of waiting for missing data units to arrive before forwarding subsequent units, the relay station forwards received data units immediately in the order they arrive, allowing the destination to handle reordering. This resolves the contradiction by maintaining reliability through destination-side reordering while reducing latency by eliminating intermediate buffer delays.
Solution Approach 2:
The patent extracts the reordering function from the relay station and relocates it to the destination station. By removing the reorder buffer from the relay station, data units can be forwarded immediately without waiting for sequence completion. The destination station then performs the reordering operation, achieving both low latency at the relay and reliable in-order delivery at the final destination.
2Reliability
If relay stations use reorder buffers to ensure in-order delivery, then data unit sequence reliability is improved, but device complexity and buffer congestion increase
Solution Approach 1:
The patent extracts the reorder buffer functionality from the relay station and relocates it to the destination station. This reduces device complexity at relay stations by eliminating the need for large reorder buffers, while maintaining sequence reliability at the destination where the buffer is ultimately needed for application-layer processing.
Solution Approach 2:
The destination station serves itself by performing the reordering operation locally rather than relying on relay stations to maintain ordered sequences. This self-service approach reduces the burden on relay stations and simplifies their buffer management while maintaining the ability to deliver data in the correct sequence to upper layers.
3Loss of time
If relay stations forward data units immediately upon receipt, then latency is reduced, but data delivery reliability deteriorates when units are transmitted out-of-order
Solution Approach 1:
The patent introduces the destination station as an intermediary that handles the reordering function. Relay stations forward data units immediately without waiting for sequence completion, and the destination station acts as the mediator that reorders these out-of-order arrivals into the correct sequence before delivering to upper layers. This resolves the contradiction by enabling immediate forwarding while maintaining reliability through the intermediary reordering function.
4Productivity
If out-of-order delivery is enabled at relay stations, then productivity and data delivery speed are improved, but adaptability to different network conditions deteriorates
Solution Approach 1:
The patent implements dynamic adaptability by allowing the destination station to selectively enable or disable out-of-order delivery based on network conditions and application requirements. The system can adapt between strict in-order delivery (when reliability is paramount) and out-of-order delivery (when speed is critical), providing versatility while maintaining high productivity when the optimized mode is activated.
Data Source
AI summary
A first station (STA) receives, from a second STA, one or more first frames including a first data unit and a second data unit, following the first data unit, for transmission by the first STA to a third STA, and an indication of whether transmission of the second data unit before the first data unit is allowed. The first STA transmits, to the third STA, a second frame including one or more of the first and the second data units, based on the indication.