Virtual MIMO Scheduling via Interference Cancellation
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Solution Overview
Problem
In wireless communication networks, especially in MIMO-OFDM environments, spectral efficiency is reduced due to interference among mobile terminals, leading to decreased communication throughput and capacity, particularly in wideband implementations where orthogonality-based scheduling is ineffective.
Innovation Solution
The implementation of decision-based feedback interference cancellation, which estimates and schedules wireless communication based on post-processing SINR, selects the highest SINR mobile terminal for cancellation, and re-estimates SINR for remaining terminals to iteratively schedule communication, thereby exploiting multi-user gain and enhancing channel capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If orthogonality-based scheduling is used in wideband MIMO-OFDM systems, then spectral efficiency should be improved, but the method becomes ineffective due to varying channel characteristics across frequency bands
Solution Approach 1:
The patent segments the wideband channel into multiple frequency sub-channels, each with relatively constant characteristics. By applying orthogonality-based scheduling independently to each sub-channel rather than across the entire wideband, the system maintains effectiveness while improving spectral efficiency. This segmentation allows the scheduling to adapt to local channel conditions in each frequency band.
2Productivity
If multiple mobile terminals transmit simultaneously in virtual MIMO, then data transmission capacity increases, but inter-terminal interference increases reducing system performance
Solution Approach 1:
The patent implements feedback-based scheduling where the base station receives channel quality indicators from mobile terminals and uses this information to make scheduling decisions. By continuously monitoring channel conditions and adjusting scheduling assignments based on feedback, the system can maximize simultaneous transmissions while keeping interference manageable through informed resource allocation.
Solution Approach 2:
The patent changes scheduling parameters dynamically based on channel conditions, including selecting which mobile terminals transmit simultaneously, assigning different frequency sub-channels to different terminals, and adjusting modulation and coding schemes. These parameter changes allow the system to optimize the balance between utilizing multiple simultaneous transmissions for higher capacity and managing interference through adaptive resource allocation.
3Productivity
If channel resources are shared among multiple mobile terminals, then network capacity increases, but interference from adjacent cells and terminals increases reducing throughput
Solution Approach 1:
The patent exploits the frequency dimension by dividing the available spectrum into multiple orthogonal frequency sub-channels. By allocating different sub-channels to different mobile terminals and cells, the system increases network capacity through frequency division while maintaining orthogonality that minimizes interference. This dimensional approach to resource allocation allows simultaneous transmissions without mutual interference.
Data Source
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AI summary
A wireless communication method and system using virtual MIMO ("V-MIMO") are provided. Post processing signal to interference and noise ratios ("SINR") for a plurality of signals corresponding to a plurality of mobile terminals arranged as a V-MIMO group are estimated. The one of the plurality of mobile terminals having the highest post processing SINR is selected. Wireless communication for the selected mobile terminal is scheduled. The signal corresponding to the selected mobile terminal is cancelled. Post processing signal to interference and noise ratios ("SINR") for the signals corresponding to the remaining mobile terminals is re-estimated. The one of the remaining mobile terminals having the highest post processing SINR is selected. Wireless communication for the selected remaining mobile terminal is scheduled.