Multi-User CTS Frame Combining for WLAN Scheduling
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Solution Overview
Problem
Existing protection mechanisms for multi-user simultaneous transmissions in wireless local area networks (WLANs) are inadequate, as they are designed for point-to-point communications and fail to effectively protect transmission duration and schedule uplink transmissions in shared wireless media, leading to interference and data reception failures.
Innovation Solution
The system employs a method where an access point transmits a single Request-to-Send (RTS) frame addressed to multiple stations, which respond with identical Clear-to-Send (CTS) frames using the same scrambling code, modulation, and frequency bands, allowing these frames to be combined and detected as a single frame, followed by an Uplink Reference frame to trigger data transmissions, enabling efficient resource allocation and scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing protection mechanisms are used for multi-user simultaneous transmissions, then point-to-point communication protection is maintained, but transmission duration protection and uplink scheduling efficiency deteriorate due to interference and data reception failures
Solution Approach 1:
The patent segments the multi-user transmission protection into distinct phases: downlink transmission phase protected by traditional RTS/CTS, and uplink transmission phase protected by uplink CTS frames. This segmentation allows each phase to have dedicated protection mechanisms, improving both reliability of downlink and productivity of uplink scheduling
Solution Approach 2:
The patent implements preliminary action by having stations send CTS frames in advance before uplink data transmissions. The uplink CTS frames are sent during the downlink phase to reserve the medium for subsequent uplink transmissions, preventing collisions and improving scheduling efficiency without compromising downlink protection
2Measurement precision
If multiple stations transmit CTS frames simultaneously using different scrambling codes, then individual station identification is improved, but frame detection accuracy deteriorates due to signal interference
Solution Approach 1:
The patent merges multiple CTS frames from different stations into a single combined frame by using the same scrambling code for all stations. This combining approach allows the access point to detect a single unified CTS frame, eliminating detection accuracy deterioration caused by simultaneous transmissions with different scrambling codes, while still maintaining the ability to identify participating stations through other frame elements
3Reliability
If traditional RTS/CTS protection is used for downlink transmissions, then downlink transmission protection is improved, but uplink transmission scheduling deteriorates due to lack of dedicated protection mechanisms
Solution Approach 1:
The patent implements universality by designing the CTS frame structure to serve multiple functions: traditional CTS frames protect downlink transmissions by reserving the medium, while uplink CTS frames simultaneously indicate uplink transmission opportunities. This multi-functional approach maintains downlink protection reliability while enabling efficient uplink scheduling without requiring separate mechanisms
Data Source
AI summary
Systems, methods, and devices are provided for protecting a multiuser (MU) transmission between an access point and a plurality of wireless stations. The access point may transmit a frame that is addressed to multiple stations in a wireless network. Each of the stations addressed by the frame may respond with an identical clear-to-send frame. In some instances, the clear-to-send frames transmitted by each wireless station may utilize the same scrambling code utilized by the frame transmitted by the access point, use the same modulation and coding scheme, and/or occupy the same frequency bands such that the multiple clear-to-send frames are combined in the air and detected as a single frame by the access point. In some instances, the access point may thereafter transmit an uplink reference frame to trigger the wireless stations to transmit an uplink data request frame to the access point.