Two-Dimensional Random Access Resource Allocation for Latency Reduction
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Solution Overview
Problem
In uplink orthogonal frequency-division multiple access (OFDMA) systems, non-associated stations (STAs) may not have opportunities to transmit latency-sensitive packets if they arrive after a trigger-based physical protocol data unit (PPDU) has started, leading to increased latency and inefficiencies in resource allocation.
Innovation Solution
The introduction of a two-dimensional random access (RA) resource unit (RU) allocation mechanism allows for the insertion of latency-sensitive packets into ongoing PPDU transmissions, enabling immediate transmission without waiting for the completion of the current PPDU, by allocating contiguous sets of RUs in the frequency domain and utilizing specific trigger frames to indicate RA-RUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the AP allocates RUs based on traditional trigger frames, then the resource allocation is simple and manageable, but latency-sensitive packets arriving after TB-PPDU starts cannot be transmitted in time
Solution Approach 1:
The patent transitions from traditional one-dimensional frequency-domain RU allocation to two-dimensional time-frequency domain RA-RU allocation. By introducing a time dimension with multiple RA-RU sets across different OFDM symbols, the system can accommodate latency-sensitive packets arriving at different times, allowing immediate transmission without waiting for the next TB-PPDU opportunity while maintaining manageable complexity through structured 2D resource indexing.
2Productivity
If the AP waits for the next TB-PPDU opportunity to allocate RUs, then the resource allocation is orderly and controlled, but the transmission latency increases significantly
Solution Approach 1:
The patent implements preliminary action by pre-allocating multiple sets of RA-RUs across different OFDM symbols within the TB-PPDU structure before transmissions begin. When latency-sensitive packets arrive, the STA can immediately utilize the pre-configured RA-RUs in the current TB-PPDU without waiting for the next opportunity, thereby improving channel efficiency while minimizing waiting time through advance resource preparation.
3Ease of operation
If the AP assigns contiguous RUs in frequency domain only, then the allocation is straightforward, but packets arriving after PPDU start must wait for completion
Solution Approach 1:
The patent segments the TB-PPDU structure into multiple sets of RA-RUs distributed across different OFDM symbols in the time-frequency domain. Each set can be independently allocated to different STAs, maintaining allocation simplicity through clear indexing while ensuring timely transmission guarantee by providing multiple time opportunities within the same TB-PPDU for packets arriving at different moments.
Data Source
AI summary
Methods and apparatuses are provided in which an access point (AP) transmits a trigger frame to one or more user equipments (UEs). The trigger frame includes an indication of allocated resource units (RUs) for random access (RA). A UE allocates respective data to a sets of RUs for RA that are consecutive in a single frequency segment over a time domain of a physical protocol data unit (PPDU), based on the trigger frame. The UE transmits the PPDU to the AP.