Uplink Training Sequence Merging for Interference Alignment

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Solution Overview

Problem

In wireless local area networks (WLANs), overlapping communication channels between adjacent basic service sets (BSSs) lead to high interference, deteriorating network performance, and existing methods are inefficient in reducing this interference during simultaneous transmission of training symbols.

Innovation Solution

A frame transmission method where multiple communication devices participating in interference alignment simultaneously transmit training symbols with common signal and training fields having the same values and structures, determining the number of long training fields based on the number of streams and antennas to minimize channel estimation errors and interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple communication devices simultaneously transmit training symbols using independent preambles, then each device can perform channel estimation, but overhead increases and interference between devices deteriorates network performance

Engineering Contradiction:

Improvechannel estimation accuracyVSAvoidpreamble overhead

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Multiple communication devices merge their training symbols into a single uplink multiplexing training sequence transmitted simultaneously over the same resource. This combining approach reduces preamble overhead while enabling channel estimation for multiple devices through the unified training sequence

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

A single uplink multiplexing training sequence serves multiple communication devices simultaneously for channel estimation. This multi-functional training sequence replaces individual device-specific preambles, reducing overall overhead while maintaining estimation capability for all participating devices

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

If multiple communication devices transmit training symbols simultaneously, then overhead is reduced, but interference between devices increases

Engineering Contradiction:

Improvetransmission efficiencyVSAvoidinterference between devices

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

Each communication device applies device-specific cyclic shifts and orthogonal cover codes to its portion of the uplink multiplexing training sequence. These local modifications enable simultaneous transmission while maintaining orthogonality and reducing mutual interference between devices

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system changes key parameters including cyclic shift values, orthogonal cover code indices, and resource allocation patterns for each device. These parameter variations enable multiple devices to transmit simultaneously with reduced interference while maintaining distinguishable channel estimation capability

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If communication devices use different preamble structures, then device-specific channel estimation is improved, but overhead and complexity increase

Engineering Contradiction:

Improvedevice-specific channel estimationVSAvoidpreamble quantity

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent merges multiple device-specific training sequences into a single uplink multiplexing training sequence by applying orthogonal transformations. This unified structure reduces the total quantity of training symbols while preserving the ability to estimate channels for individual devices through mathematical separation

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11463218B2Method for transmitting frame and communication device for performing the same

Publication Date: 2022.10.04 ELECTRONICS & TELECOMM RES INST

AI summary

Disclosed are a frame transmission method and a communication device performing the same. The communication device transmits a null data packet (NDP)-announcement (NDP-A) including information on a plurality of communication devices participating in interference alignment and transmits an NDP including a common signal field and a common training field commonly applied to the plurality of communication devices.