Directional Clear Channel Assessment for Millimeter-Wave MIMO
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Solution Overview
Problem
Current wireless communication systems in the millimeter-wave band face challenges in efficiently managing Clear Channel Assessment (CCA) across multiple directions, leading to suboptimal performance in dense environments and interference issues during Multi-User (MU) MIMO transmissions.
Innovation Solution
Implementing a method where wireless stations dynamically adapt their transmissions by independently checking CCA states in multiple directions before transmitting, allowing for selective data stream transmission only in directions with idle CCA states, and using RTS/CTS exchanges to optimize beamforming and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional omnidirectional CCA is used in millimeter-wave wireless communication, then the system can maintain simple channel assessment procedures, but it results in suboptimal performance in dense environments and interference issues during MU-MIMO transmissions
Solution Approach 1:
The patent segments the omnidirectional CCA into multiple directional CCA checks. Instead of performing a single channel assessment in all directions, the system divides the assessment into separate directional components, allowing independent evaluation of channel availability in each spatial direction. This segmentation enables selective transmission in directions with idle channels while avoiding directions with ongoing transmissions, thereby reducing interference and improving communication efficiency in dense environments
Solution Approach 2:
The patent applies local quality by making the CCA assessment direction-dependent. Each directional beam performs its own CCA check tailored to its specific spatial orientation, rather than using a uniform omnidirectional assessment. This allows the system to adapt transmission parameters and decisions locally to each directional context, optimizing performance for each spatial sector while minimizing interference to and from other directions
2Productivity
If directional CCA is implemented for each transmission direction, then interference is reduced and communication efficiency improves, but the complexity of channel assessment increases
Solution Approach 1:
The patent implements dynamic directional CCA where the system adaptively selects which directions to assess based on transmission requirements and environmental conditions. The CCA mechanism dynamically adjusts the number and orientation of directional assessments, transitioning between simpler omnidirectional modes and more complex directional modes as needed. This dynamic approach optimizes the balance between assessment accuracy and computational complexity
Solution Approach 2:
The patent performs preliminary directional CCA assessments before final transmission decisions are made. By conducting directional channel assessments in advance and caching the results, the system prepares transmission parameters beforehand, reducing the need for complex real-time decision-making during actual data transmission. This preliminary action simplifies the overall system complexity while maintaining high throughput performance
3Reliability
If CCA is checked in multiple directions before transmission, then clear channels are identified more accurately, but the time required for channel assessment increases
Solution Approach 1:
The patent implements periodic directional CCA where channel assessments are performed at regular intervals and results are cached for reuse. Instead of performing exhaustive directional CCA before every transmission, the system conducts periodic assessments and reuses valid results within their validity period. This periodic approach maintains high assessment accuracy while significantly reducing the time penalty associated with frequent directional checks
Solution Approach 2:
The patent applies partial action by performing CCA checks in only the necessary subset of directions rather than all possible directions. The system identifies and assesses only those directions that are relevant for current transmission objectives, using beamforming training results to prioritize critical directions. This partial assessment approach achieves sufficient reliability for transmission decisions while minimizing the time required for channel assessment
Data Source
AI summary
Some demonstrative embodiments include apparatuses, devices, systems and methods of communication based on Clear Channel Assessment (CCA) in one or more directions. For example, an apparatus may include logic and circuitry configured to cause a wireless station to determine a plurality of directions to transmit a plurality of respective data streams of a Multi-Input-Multi-Output (MIMO) transmission; to detect a plurality of CCA states corresponding to the plurality of directions, respectively; and based on the plurality of CCA states, to transmit one or more selected data streams of the plurality of data streams in one or more respective selected directions of the plurality of directions.