MIMO-OFDM Link Adaptation for Throughput Maximization
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Solution Overview
Problem
Current MIMO-OFDM systems face inefficiencies in selecting the optimal Modulation and Coding Scheme (MCS) and spatial rate, often underestimating throughput to minimize error probability, leading to suboptimal performance due to complex calculations and mismatched optimization criteria.
Innovation Solution
A link adaptation method that selects the MCS level and spatial rate based on instantaneous broadband MIMO-OFDM signaling capacities, comparing diversity coding and spatial multiplexing schemes to maximize throughput while maintaining a fixed target probability of error, using effective SISO SINR calculations and auxiliary scaling factors to bias towards the optimal scheme.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If present methods base spatial rate selection on comparative minimum Euclidean distances, then probability of error is minimized under fixed throughput assumption, but throughput rate is underestimated and system performance is reduced
Solution Approach 1:
The patent changes the optimization parameter from minimum Euclidean distance to instantaneous broadband MIMO-OFDM signaling capacity. This parameter change allows the system to directly optimize for throughput while maintaining acceptable error rates, rather than prioritizing error minimization at the cost of throughput. The signaling capacity metric inherently balances both reliability and productivity considerations.
Solution Approach 2:
Instead of minimizing error probability as the primary goal (which leads to conservative throughput selection), the patent inverts the approach by maximizing signaling capacity as the primary objective. This inversion allows the system to achieve higher throughput while the fixed target probability of error constraint ensures reliability is maintained.
2Reliability
If complex calculations are used to minimize error probability, then reliability is improved, but computational complexity increases and system efficiency decreases
Solution Approach 1:
The patent replaces complex Euclidean distance calculations with effective SISO SINR calculations followed by signaling capacity determination. This substitution simplifies the computational process while maintaining the ability to assess channel quality and select appropriate MCS levels and spatial rates for reliable transmission.
Solution Approach 2:
The patent introduces effective SISO SINR as an intermediary metric that simplifies the complex MIMO channel assessment. By converting the MIMO channel characteristics into equivalent SISO SINR values, the system can more easily determine signaling capacity and make rate selection decisions without performing complex multi-antenna signal processing calculations.
3Reliability
If fixed target probability of error is used as optimization criterion, then reliability is maintained, but throughput maximization is not achieved with prior rate selection methods
Solution Approach 1:
The patent introduces dynamic rate selection based on instantaneous channel conditions through signaling capacity calculation. Rather than using fixed rate selection tables, the system dynamically determines the optimal spatial rate and MCS level by evaluating the instantaneous broadband MIMO-OFDM signaling capacity, which adapts to current channel quality while maintaining the target error probability.
Solution Approach 2:
The patent implements a feedback mechanism where the receiver calculates the instantaneous signaling capacity based on observed channel conditions and feeds back the optimal spatial rate and MCS level selection to the transmitter. This feedback loop enables the system to continuously optimize throughput while maintaining reliability by adapting to changing channel conditions.
Data Source
AI summary
Embodiments are directed to a link adaptation method that selects the optimum transmission scheme and modulation and coding signal (MCS) level within a MIMO system, based on optimal maximum throughput on the channels. The method selects the MCS levels and spatial rate values for broadband communication systems based on the instantaneous broadband MIMO-OFDM signaling capacities. The transmission rate over the transmission channel is selected based on a comparison of the capacities achieved under diversity coding and spatial multiplexing MIMO transmission schemes. The effect of a particular receiver type or implementation can also be factored into the signaling capacity. For a fixed target probability of error, the scheme or spatial rate that has the higher instantaneous throughput is selected for transmission.