WLAN Control Information Transmission via Beamforming
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Solution Overview
Problem
In WLAN systems, especially those supporting MU-MIMO and VHT, there is a challenge in efficiently transmitting control information while maintaining backward compatibility with legacy stations and ensuring coexistence with both VHT and legacy stations, leading to increased overhead and potential malfunctions due to unrecognized PLCP formats.
Innovation Solution
A method involving cyclic shift delay diversity beam-forming for transmitting control information, where first control information is sent omnidirectionally and second control information is beamformed, with specific details including modulation and coding scheme, channel bandwidth, and transmission power information, to accommodate increasing control needs and ensure compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PLCP format is changed to support VHT and MU-MIMO, then transmission speed and throughput are improved, but backward compatibility with legacy stations deteriorates
Solution Approach 1:
The control information is segmented into two distinct parts: first control information transmitted omnidirectionally using legacy PLCP format for backward compatibility, and second control information transmitted using beamforming for VHT/MU-MIMO functionality. This segmentation allows legacy stations to process the first part while VHT stations can access both parts.
Solution Approach 2:
The first control information acts as an intermediary that bridges legacy and VHT stations. It contains essential information for both legacy station operation and provides guidance for VHT stations to receive the second control information, enabling smooth coexistence without requiring legacy stations to understand VHT-specific formats.
2Adaptability or versatility
If control information is transmitted omnidirectionally for legacy compatibility, then backward compatibility is maintained, but frequency efficiency deteriorates
Solution Approach 1:
Different transmission methods are applied to different parts of control information based on their specific requirements. The first control information uses omnidirectional transmission for broad compatibility, while the second control information uses directional beamforming for frequency efficiency, optimizing each part according to its local needs.
Solution Approach 2:
The system dynamically selects transmission methods based on the type of control information being transmitted. This dynamic approach allows the system to switch between omnidirectional and beamformed transmission, optimizing frequency efficiency for STA-specific information while maintaining compatibility for public control information.
3Use of energy by moving object
If beamforming is used for control information transmission, then frequency efficiency is improved, but reliability for legacy stations deteriorates
Solution Approach 1:
The first control information is transmitted preliminarily in an omnidirectional manner before the second control information is transmitted via beamforming. This preliminary transmission ensures that legacy stations receive necessary information reliably before the more efficient but targeted beamformed transmission occurs.
Solution Approach 2:
The omnidirectional first control information acts as a cushioning layer that protects against reliability issues for legacy stations. It provides a fallback mechanism ensuring that even if beamforming fails or is not supported, legacy stations can still receive essential control information reliably.
4Adaptability or versatility
If separate control information structures are used for VHT and legacy stations, then functionality for both is improved, but device complexity increases
Solution Approach 1:
The first control information structure serves multiple functions: it acts as public control information for all stations, provides legacy-compatible PLCP format, and contains embedded information that guides VHT stations in receiving the second control information. This multi-functionality reduces the need for completely separate structures.
Solution Approach 2:
The control information is structured in a nested manner where the first control information contains or references information about the second control information. This nested structure allows legacy stations to process the outer layer while VHT stations can access the inner layer, reducing overall structural complexity compared to completely separate systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for efficient control information transmission in WLAN systems supporting MU-MIMO, guarantees backward compatibility, and enhances frequency efficiency by allocating resources effectively between public and STA-specific control information.
Implementation Method 1
transmitting first control information by means of cyclic shift delay diversity beam-forming, and transmitting second control information, wherein the first control information comprises information necessary for each of a plurality of target stations of the second control information to receive the second control information
Data Source
AI summary
A method and a radio apparatus for signal transmission in a Wireless Local Area Network (WLAN) system are discussed. The method according to an embodiment includes generating first and second very high throughput (VHT) fields including first and second control information, respectively; and transmitting a physical layer protocol data unit (PPDU) including the first and second VHT fields to at least one target station. The first VHT field includes an indicator indicating whether the PPDU is to be transmitted by using a single-user multiple input multiple output (SU-MIMO) scheme or a multi-user multiple input multiple output (MU-MIMO) scheme.