Precoder Cycling Sets for MIMO Channel Adaptation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current MIMO communication systems face challenges in high mobility scenarios due to the time required for closed-loop precoding, which can result in outdated channel information, and open-loop precoding complexity, particularly in managing interference and implementing multiple precoders, leading to increased complexity and power consumption.
Innovation Solution
The implementation of precoder cycling using a cycling codebook with precoders that are substantially separated by distance measures, allowing for efficient transmission rank adaptation and reduced complexity by reusing closed-loop precoders in open-loop schemes, optimizing precoder distance properties for diverse channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If closed-loop precoding is used in MIMO communication systems, then channel adaptation performance is improved, but the time required for channel information updates increases causing outdated channel information in high mobility scenarios
Solution Approach 1:
The patent segments the precoding process by separating channel estimation and precoder selection (closed-loop functions) from the actual precoding application. The receiver performs channel estimation and feeds back channel information, while the transmitter independently selects precoders from a codebook based on this information. This segmentation allows the system to maintain closed-loop adaptation benefits while reducing the time penalty by enabling parallel processing and eliminating waiting for full closed-loop feedback cycles.
Solution Approach 2:
The patent implements preliminary action by pre-computing and storing multiple precoders in a codebook at the transmitter before actual data transmission. These precoders are prepared in advance based on channel characteristics obtained through feedback, allowing the system to quickly select and apply appropriate precoders without real-time computation delays during high-speed transmission, thus addressing the time loss issue in high mobility scenarios.
2Reliability
If open-loop precoding with multiple precoders is implemented, then precoding diversity is improved, but system complexity and power consumption increase
Solution Approach 1:
The patent applies parameter changes by varying the precoder selection based on transmission rank, which itself is adapted to channel conditions. The system selects different numbers of precoders from the codebook depending on the transmission rank determined by channel quality indicators. This dynamic parameter adjustment provides precoding diversity when channel conditions warrant it, while reducing complexity when conditions are poor, thus resolving the contradiction between diversity and complexity.
Solution Approach 2:
The patent implements partial action by selectively applying multiple precoders only when transmission rank indicates favorable channel conditions. Rather than always using maximum precoding diversity, the system applies the appropriate level of precoding complexity partiality - using full diversity only when needed, and reducing to simpler schemes when channel conditions don't support complex precoding, thereby balancing diversity benefits against system complexity.
3Reliability
If open-loop precoding with multiple precoders is implemented, then precoding diversity is improved, but power consumption increases
Solution Approach 1:
The patent uses parameter changes to dynamically adjust power consumption based on transmission rank. When channel conditions support high transmission rank, the system activates multiple precoders and consumes higher power to achieve diverse precoding. When conditions deteriorate, the system reduces transmission rank and deactivates unnecessary precoders, thereby reducing power consumption. This dynamic parameter adaptation directly links power usage to actual channel conditions and diversity requirements.
4Device complexity
If precoders are selected from a codebook, then implementation complexity is reduced, but interference management capability is limited
Solution Approach 1:
The patent applies local quality by selecting specific precoders from the codebook based on local channel conditions and interference characteristics. Rather than using a fixed precoder for all users, the system evaluates channel quality indicators and interference levels for each user and selects precoders locally optimized for their specific conditions. This local optimization maintains the simplicity of codebook-based selection while improving interference management through condition-specific precoder choices.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Data is transmitted over multiple input multiple output (MIMO) channels. Plural bit streams are modulated into multiple data symbol vectors. Each vector has a transmission rank with one vector for each MIMO channel. Transmission rank is the number of elements in a data symbol vector corresponding to the number of data streams being transmitted in parallel over each MIMO channel. The multiple data symbol vectors are precoded into multiple precoded symbol vectors using a plurality of precoder cycling sets, one set for each transmission rank including multiple different precoders. The precoders in each precoder cycling set are well-separated with respect to a plurality of distance measures. The precoding includes precoding each data symbol vector of a transmission rank with a precoder belonging to the precoder cycling set of that transmission rank. The precoded symbol vectors are then transmitted over the MIMO channels.