Frequency Selective Scheduling for OFDMA WLANs
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Solution Overview
Problem
Existing WLAN OFDMA systems face challenges in maximizing throughput and ensuring fair resource allocation due to differences in scheduling strategies between LTE and WLAN networks, particularly in handling sub-bands and packet sizes, leading to inefficiencies and resource wastage.
Innovation Solution
A two-phase Frequency Selective Scheduling (FSS) algorithm that uses an extended air-time fairness algorithm for time domain scheduling and an iterative process for frequency domain scheduling, considering packet lengths and channel gains to allocate sub-bands, ensuring proportional fairness and minimizing transmission time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If OFDMA sub-band allocation is performed without considering channel state information, then scheduling complexity is reduced, but throughput and fairness guarantees are lost
Solution Approach 1:
The patent segments the frequency spectrum into multiple sub-bands and applies different scheduling strategies to each sub-band based on channel conditions. This allows the system to simplify scheduling in some sub-bands while maintaining optimized scheduling in others, resolving the contradiction between complexity and throughput.
Solution Approach 2:
The patent changes scheduling parameters dynamically based on channel state information. When channel conditions are favorable, complex channel-aware scheduling is applied to maximize throughput. When conditions deteriorate or complexity constraints arise, the system transitions to simpler scheduling algorithms, thus adapting the parameter of scheduling complexity to maintain throughput.
2Productivity
If centralized scheduling control is implemented in WLAN, then resource allocation efficiency is improved, but system complexity and implementation difficulty increase
Solution Approach 1:
The patent implements preliminary channel sounding and state information collection before actual data transmission. This preliminary action allows the centralized scheduler to make informed allocation decisions without requiring complex real-time coordination during data transmission, thus improving resource allocation efficiency while controlling system complexity.
Solution Approach 2:
The patent introduces channel state information as an intermediary that mediates between the distributed wireless devices and the centralized scheduler. This intermediary provides the necessary data for efficient resource allocation without requiring direct complex interactions between all system components, thereby improving allocation efficiency while managing system complexity.
3Productivity
If sub-bands are allocated to maximize instantaneous throughput, then overall network capacity increases, but fairness among wireless devices deteriorates
Solution Approach 1:
The patent dynamically changes the scheduling parameter from pure throughput maximization to a weighted metric that incorporates both throughput and fairness considerations. By adjusting this parameter based on device conditions and network state, the system can shift between maximizing capacity and ensuring fairness, or achieve a balanced optimal point that satisfies both requirements simultaneously.
Data Source
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AI summary
A network node for an orthogonal Frequency Division Multiplexing Access, OFDMA, based wireless local area network is provided. The network node includes processing circuitry. The processing circuitry includes a processor and a memory. The memory contains instructions that, when executed by the processor, configure the processor to reduce transmission time inequality among each of a plurality of wireless device during an OFDMA subframe by assigning a respective OFDMA subband of a plurality of OFDMA subbands to each of the plurality of wireless devices, and cause data transmission on the assigned OFDMA subbands to the plurality of wireless device.