MIMO Retransmission Control Using Stream Reliability Thresholds
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Solution Overview
Problem
In MIMO wireless communication systems, existing retransmission protocols fail to adaptively select the optimal retransmission method based on the reliability of spatial data streams, leading to suboptimal decoding performance due to antenna diversity and varying link conditions.
Innovation Solution
A retransmission control method that receives a NACK signal, assesses the reliability of system and parity bits, and selects between Chase combining and Incremental Redundancy protocols based on predetermined thresholds, adjusting coding rates and spatial processing to optimize retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed retransmission protocol is used in MIMO systems, then the system implementation is simple, but the decoding performance is suboptimal due to varying link conditions caused by antenna diversity
Solution Approach 1:
The patent implements dynamic retransmission control by selecting between Chase combining and Incremental Redundancy protocols based on real-time reliability measures of spatial data streams. The system adapts the retransmission strategy according to channel conditions, transitioning from a static to a dynamic control mechanism that optimizes decoding performance while managing complexity through structured decision-making based on stream reliability assessments.
2Reliability
If Chase combining protocol is used for retransmission, then energy gain is provided to improve decoding performance, but resource utilization is suboptimal when link conditions are good
Solution Approach 1:
The patent changes the retransmission parameter (protocol type) based on the reliability measure of spatial data streams. When link conditions are good (high reliability), the system switches to Incremental Redundancy protocol to improve resource utilization. When link conditions are poor (low reliability), it uses Chase combining protocol to provide energy gain for decoding. This dynamic parameter adjustment optimizes both decoding performance and resource utilization according to actual channel conditions.
3Reliability
If Incremental Redundancy protocol is used for retransmission, then coding gain is achieved by providing more redundancy, but resource utilization deteriorates when link conditions are poor
Solution Approach 1:
The system dynamically adjusts the retransmission protocol parameter based on reliability measures. When link conditions are poor (low reliability), the patent switches to Chase combining protocol which provides energy gain and is more resource-efficient in such conditions. When link conditions are good (high reliability), it employs Incremental Redundancy protocol to achieve coding gain through additional redundancy. This adaptive parameter selection optimizes the trade-off between decoding performance and resource utilization.
4Productivity
If spatial data streams are transmitted through multiple antennas, then transmission capacity is enhanced, but varying link conditions cause suboptimal decoding performance
Solution Approach 1:
The patent applies local quality assessment by evaluating the reliability measure of each spatial data stream individually. Instead of treating all streams uniformly, the system identifies which specific streams have poor reliability and selects appropriate retransmission protocols for those streams. This localized approach maintains the transmission capacity benefits of multiple antennas while addressing decoding performance issues on a per-stream basis.
Data Source
AI summary
A retransmission control method, a transmitter and a receiver. The method comprises the steps of receiving, at a MIMO transmitter, a NACK signal indicating an unsuccessful decoding of a coded data packet at a MIMO receiver; receiving a reliability measure associated with one or more transmitted spatial data streams for the unsuccessfully decoded data packet; comparing the reliability measure with at least one predetermined threshold; and selecting a retransmission protocol based on the comparison of the reliability measure with the at least one predetermined threshold.