Adaptive Modulation and Coding Scheme Selection for Wireless Systems
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Solution Overview
Problem
Existing broadband wireless communication systems face challenges in efficiently adapting modulation and coding schemes (MCS) due to varying channel conditions across sub-bands, leading to increased latency and complexity, particularly in time-division-duplex (TDD) retro-directive beamforming systems.
Innovation Solution
The implementation of adaptive coding and modulation (ACM) techniques that allow for fine-grained selection of MCS per-sub-band and per-stream, using metrics like signal-to-interference-and-noise-ratio (SINR) and transport block error (TBE) to dynamically adjust modulation and coding schemes based on channel conditions, reducing re-transmissions and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one MCS is signaled per allocation in broadcast control channel, then system complexity is reduced, but performance deteriorates due to inability to adapt to varying channel conditions across sub-bands
Solution Approach 1:
The frequency band is divided into multiple sub-bands, and separate MCS indices are selected for each sub-band rather than using a single MCS for the entire allocation. This segmentation allows the system to adapt to varying channel conditions in different frequency regions while maintaining manageable complexity through structured processing.
Solution Approach 2:
The patent introduces frequency-domain granularity by selecting MCS per sub-band instead of per entire allocation. This adds a dimensional aspect to MCS selection, transforming it from a single-value parameter to a multi-value parameter across the frequency spectrum, thereby improving adaptability without proportionally increasing complexity.
2Adaptability or versatility
If per-sub-band MCS selection is implemented, then adaptability to channel conditions improves, but device complexity increases
Solution Approach 1:
Different MCS indices are selected for different sub-bands based on their specific channel conditions (SINR, TBE metrics). Each sub-band receives optimized coding and modulation parameters tailored to its local channel characteristics, improving overall system adaptability while maintaining structured processing to control complexity.
Solution Approach 2:
The MCS selection becomes dynamic and adaptive, allowing the system to adjust coding and modulation parameters based on real-time channel conditions in each sub-band. This dynamic adaptation improves versatility while the systematic approach to selection keeps complexity manageable.
3Reliability
If hybrid-automatic-repeat-request (HARQ) with re-transmissions is used, then error rates are reduced, but latency increases
Solution Approach 1:
The system performs preliminary action by selecting appropriate MCS indices based on channel conditions before transmission occurs. By predicting and preparing the right coding and modulation parameters in advance, the system reduces the likelihood of transmission errors, thereby reducing the need for re-transmissions and associated latency.
Solution Approach 2:
The patent uses feedback mechanisms where the receiving node measures channel conditions (SINR, TBE) and reports back to the transmitting node. This feedback loop enables the transmitting node to select optimal MCS indices for the next transmission, improving reliability while minimizing re-transmissions and latency through informed decision-making.
Data Source
AI summary
The present disclosure describes systems and methods for selecting modulation and coding schemes (MCS) per-sub-band, and in some examples, per-stream. In some examples, channel condition metrics regarding wireless communication conditions from a communication node of a wireless access system may be received. Based at least on the received channel condition metrics, a modulation and coding scheme may be selected. In some examples, the selected modulation and coding scheme may be transmitted to various modulators/demodulators, encoders/decoders, and/or other communication nodes within the wireless access system.