Linear Precoding for MIMO Systems with Outdated CSI

The patent applies preliminary action by deriving the pairwise error probability with respect to both minimum and average codeword distance design metrics in advance, and formulating the optimization problem before solving it through iterative techniques. The precoder designs are prepared based on available (though outdated) CSI before transmission occurs, allowing the system to exploit whatever channel state information is available rather than waiting for updated information.

The patent applies parameter changes by formulating the optimization problem in terms of pairwise error probability with respect to both minimum and average codeword distance design metrics. By changing the optimization parameters and using iterative techniques (alternating minimization and projected gradient algorithms), the system adapts to work with outdated CSI rather than requiring real-time updates, thus maintaining performance despite time delays.

The patent applies segmentation by breaking down the non-convex optimization problem into smaller sub-problems that can be solved through alternating minimization. Instead of attempting to solve the entire complex optimization problem at once, the patent segments it into iterative steps where different components are optimized sequentially, reducing the computational burden while still achieving improved precoder performance.