Multi-layer MIMO SIC with Shared HARQ for Detection Complexity
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Solution Overview
Problem
Current Multiple Input Multiple Output (MIMO) systems face challenges in efficiently detecting signals due to exponential complexity, leading to inferior bit-error-rate and frame-error-rate performance, especially in systems like 5G New Radio, 3GPP LTE/LTE-Advanced, where suboptimal detection techniques struggle with multi-antenna interference without effective error correction.
Innovation Solution
The implementation of a multi-layer MIMO system using multiple transport blocks with shared Hybrid Automatic Repeat Request (HARQ) process identifiers across layers, allowing for error-free layers to reconstruct signals and reduce interference through Serial Interference Cancellation (SIC), while minimizing feedback channel overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ML/MAP detection using exhaustive search is used in MIMO systems, then detection accuracy is improved, but computational complexity increases exponentially
Solution Approach 1:
The patent segments the detection process into multiple stages: initial detection of all layers, error detection via CRC, identification of error-free layers, and sequential interference cancellation. This divides the complex ML/MAP detection into manageable steps that achieve near-optimal performance with reduced complexity.
Solution Approach 2:
The patent performs preliminary error detection using CRC checks before attempting full decoding. By identifying error-free layers in advance, the system can cancel their interference early in the process, avoiding the need for exhaustive search on all layers and reducing overall computational complexity.
2Device complexity
If suboptimal detection techniques are used to reduce complexity, then device complexity is reduced, but bit-error-rate and frame-error-rate performance deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where CRC results from initial detection are used to guide subsequent interference cancellation steps. The system feeds back information about which layers are error-free and uses this to adaptively cancel interference, improving error-rate performance while maintaining reduced complexity.
Solution Approach 2:
The detection process is made dynamic by adaptively selecting which layers to cancel based on real-time CRC results. Rather than following a fixed cancellation order, the system dynamically adjusts the interference cancellation strategy based on which layers are actually error-free, improving reliability without increasing complexity.
3Ease of manufacture
If traditional SIC is used without utilizing CRC potential, then implementation is simplified, but error correction capability is reduced
Solution Approach 1:
The patent enables the system to self-identify error-free layers through CRC checks performed on initially detected layers. This self-service capability allows the system to automatically determine which layers can be used for interference cancellation without external control, improving error correction while maintaining implementation simplicity.
4Reliability
If multiple HARQ processes are used for multiple layers, then error correction is improved, but feedback channel overhead increases
Solution Approach 1:
The patent merges multiple HARQ processes into a single shared HARQ process for all layers. Instead of maintaining separate HARQ processes for each layer, the system combines them and uses CRC results to determine which layers need retransmission, reducing feedback overhead while maintaining error correction capability through selective retransmission.
Data Source
AI summary
Aspects of the subject disclosure can include, for example, a first logical codeword is associated with multiple layers of a MIMO system to obtain a logical codeword mapping. The first logical codeword is associated with a hybrid automatic receive request (HARQ) process identifier and based on a first number of channel-encoded codewords of a first number of transport data blocks. In response to detection of an error in one of the channel-encoded codewords, a modified first logical codeword is generated based on the one channel-encoded codeword and mapped to the number of layers of the MIMO s system for transmission to the receiver for further processing associated with the HARQ identifier. Other embodiments are disclosed.