OFDMA Scheduling in Wireless LANs
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Solution Overview
Problem
Wireless local-area networks (WLANs) face challenges in improving throughput and reducing delay time due to limited wireless medium resources and the need for better performance from users.
Innovation Solution
Implementing low-overhead scheduling techniques in orthogonal frequency division multiple access (OFDMA) systems, specifically for high-efficiency wireless (HEW) devices, which involve the access point transmitting schedule indicators to allocate channels efficiently among HEW devices, allowing for non-contention based multiple access during designated control periods, and adapting channel contention settings to optimize resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional contention-based access is used in WLANs, then devices can access the medium freely, but throughput is limited and delay time increases due to collisions and contention overhead
Solution Approach 1:
The access point performs preliminary scheduling of multiple stations before transmission, allocating specific time slots and frequency resources to each station in advance. This eliminates contention-based access delays and collisions by pre-organizing the transmission sequence, thereby improving throughput and reducing delay time simultaneously
Solution Approach 2:
The wireless medium is segmented into multiple orthogonal frequency subcarriers and time slots, allowing multiple stations to transmit simultaneously without interference. This segmentation enables parallel transmissions that increase overall throughput while reducing the delay each station would experience in traditional sequential contention-based access
2Productivity
If more scheduling information is transmitted to allocate channels efficiently, then resource allocation improves, but overhead increases
Solution Approach 1:
A universal resource allocation table structure is used that can represent multiple different allocation scenarios using the same format. The table includes fields for station identifiers, frequency subcarrier assignments, and time slot allocations that can accommodate various scheduling configurations, reducing the need for multiple specialized message formats and thereby reducing overhead
Solution Approach 2:
The scheduling information uses compact parameter encoding where frequency subcarrier allocations are represented by starting subcarrier indices and lengths rather than listing every subcarrier individually. This parameter-based representation significantly reduces the number of bits required to convey the same allocation information, improving resource allocation efficiency while minimizing overhead
Data Source
AI summary
Methods, apparatuses, and computer readable media are shown for multi-user scheduling in wireless local-area networks (WLANs). A wireless communication device is shown including circuitry to determine a plurality of schedules for each of a plurality of channels for an orthogonal frequency division multiple access (OFDMA) communication in a wireless local-area network (WLAN). Each of the plurality of schedules may include a frequency allocation for one or more communication devices. The circuitry may be further configured to transmit the corresponding schedule of the one or more schedules on each of the one or more channels. Each of the plurality of schedules may include a schedule type and a user association identification (AID) list. A number of user AIDs in the user AID list may be based on the schedule type.