MIMO-OFDM HARQ Retransmission Mode Selection for Higher Throughput
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Solution Overview
Problem
Current technologies do not effectively apply Hybrid ARQ (HARQ) techniques to MIMO-OFDM systems, which limits data throughput performance and increases the number of retransmission requests due to the absence of efficient retransmission methods in these systems.
Innovation Solution
An automatic repeat request (ARQ) control system and retransmission method that determines the need for retransmission based on feedback information, selects optimal retransmission schemes considering system requirements such as latency and performance, and utilizes cyclic redundancy checks, space-time block coding, and incremental redundancy to improve accuracy and reduce retransmissions in MIMO-OFDM systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HARQ techniques are applied to MIMO-OFDM systems, then data throughput performance is improved, but the complexity of the system increases due to the need for multiple retransmission schemes
Solution Approach 1:
The patent implements dynamic selection of retransmission schemes (spatial multiplexing, spatial diversity, or single-antenna modes) based on real-time channel conditions and system requirements. The transmitter adapts the retransmission strategy by evaluating feedback information and selecting the most appropriate scheme, making the system flexible rather than static. This dynamic approach allows the system to optimize throughput while managing complexity by only activating necessary retransmission mechanisms.
Solution Approach 2:
The system changes operational parameters such as the number of transmit antennas, receive antennas, and coding schemes based on channel state information and QoS requirements. By adjusting these parameters dynamically, the system can improve throughput performance when conditions allow while reducing complexity when channel conditions are poor or resources are constrained.
2Reliability
If multiple retransmission schemes are implemented, then retransmission accuracy is improved, but the number of control decisions and processing overhead increases
Solution Approach 1:
The patent segments the retransmission process into distinct schemes (spatial multiplexing retransmission, spatial diversity retransmission, and single-antenna retransmission), each optimized for specific channel conditions. By dividing the complex retransmission problem into manageable segments with clear selection criteria, the system improves accuracy by choosing the right scheme while reducing overall control complexity through structured decision-making.
Solution Approach 2:
The system performs preliminary classification of channel conditions and pre-determines the appropriate retransmission scheme before actual retransmission occurs. By evaluating channel state information and system requirements in advance, the system prepares the optimal retransmission strategy, reducing the complexity of real-time control decisions during the retransmission process itself.
3Reliability
If retransmission requests are increased to ensure reliability, then data delivery reliability is improved, but the latency and throughput performance deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the receiver sends ACK/NACK information and channel state information back to the transmitter. This feedback allows the system to make informed decisions about retransmission necessity and scheme selection, ensuring reliability only when needed while avoiding unnecessary retransmissions that would degrade throughput performance.
Solution Approach 2:
The system applies retransmission selectively rather than universally - using partial retransmission only for packets that require it based on error detection and channel conditions. This partial action approach maintains reliability for necessary retransmissions while avoiding the throughput penalty of excessive retransmissions across all data packets.
Data Source
AI summary
An automatic retransmission request control system in an OFDM-MIMO communication system includes a retransmission mode selection part which selects a retransmission mode from among (a) a mode in which to transmit the data, which are to be retransmitted, via the same antenna as in the previous transmission, while transmitting, at the same time, new data by use of an antenna via which no data retransmission is requested; (b) a mode in which to transmit the data, which are to be retransmitted, via an antenna via which no retransmission is requested, while transmitting new data via another antenna at the same time; (c) a mode in which to use STBC to retransmit the data via an antenna via which no retransmission is requested; and (d) a mode in which to use STBC to retransmit the data via all the available antennas.