Multi-User RTS CTS Protocol for OFDMA Interference Management

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Solution Overview

Problem

Wireless local area networks (WLANs) face challenges in efficiently sharing the wireless medium and minimizing interference between devices transmitting simultaneously, particularly due to the presence of legacy protocols and hidden node issues.

Innovation Solution

Implementing a method that uses multi-user request-to-send (RTS)/clear-to-send (CTS) protocols in conjunction with orthogonal frequency division multiple access (OFDMA) and multi-user multiple-input multiple-output (MU-MIMO) techniques, including a resource map and deferral mechanisms to manage subchannel allocation and ensure devices defer transmission during active communications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple devices share the wireless medium simultaneously, then network utilization increases, but interference between devices increases

Engineering Contradiction:

Improvenetwork utilizationVSAvoidinterference between devices

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The wireless medium is segmented into multiple orthogonal frequency subchannels through OFDMA, allowing simultaneous transmissions on different frequency resources without interference. The patent divides the available spectrum into discrete resource units that can be independently allocated to different devices, thus increasing network utilization while preventing interference.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces spatial dimension through MU-MIMO technology, enabling multiple devices to transmit simultaneously using different spatial streams and antenna configurations. This adds a spatial dimension to resource allocation, allowing concurrent transmissions that would otherwise interfere on the same frequency channel.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If RTS/CTS protocols are implemented for all devices, then hidden node problems are reduced, but network overhead increases

Engineering Contradiction:

Improvehidden node problem resolutionVSAvoidnetwork overhead

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies RTS/CTS protocols selectively rather than universally. Devices participating in OFDMA/MU-MIMO transmissions receive targeted RTS/CTS exchanges, while non-participating devices use simplified duration field interpretations. This localized application of protocols reduces overhead while maintaining reliability for critical transmissions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent modifies the traditional RTS/CTS mechanism by incorporating duration fields that indicate deferral times for non-participating devices. This parameter change allows the protocol to adapt its behavior based on device participation status, reducing overhead for devices that don't need full protection while maintaining reliability for active participants.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If legacy protocols are supported for compatibility, then device interoperability is maintained, but network efficiency decreases

Engineering Contradiction:

Improvedevice interoperabilityVSAvoidnetwork efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent introduces HEW-specific signal fields and preamble structures that act as intermediaries between legacy and modern devices. These intermediary elements carry enhanced information (such as duration fields and resource allocation) that legacy devices can interpret using their existing protocols, while HEW devices utilize the full capability. This allows interoperability without sacrificing efficiency for modern participants.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the protocol stack into legacy-compatible portions and HEW-enhanced portions. The physical layer preamble and signal fields are structured to provide both legacy compatibility and HEW efficiency, with different sections serving different device types. This segmentation allows the network to support both legacy and modern devices simultaneously with optimized performance.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10396952B2Wireless device, method, and computer readable media for multiply-user request-to-send and clear-to-send and uplink ACK protection in a high efficiency wireless local-area network

Publication Date: 2019.08.27 INTEL CORP

AI summary

Wireless device, method, and computer readable media for multi-user request-to-send and clear-to-send and uplink ACK protection in a high efficiency wireless local-area network are disclosed. A high-efficiency (HE) wireless local-area network (HEW) master device may include circuitry configured to generate a multi-user (MU) RTS packet for a plurality of stations (STAs), the RTS packet to include an indication of an address for each of the plurality of STAs. The circuitry may be further configured to transmit the MU-RTS to the plurality STAs and transmit data to one or more of the plurality of STAs in accordance with at least from the following group orthogonal frequency division multi-user (OFDMA) and multi-user multiple-input multiple-output (MU-MIMO). The circuitry may be configured to receive acknowledgements from the one or more of the plurality of STAs. A HEW device may set a deferral duration in an uplink transmission to enable a HEW master device to send an acknowledgement.