# Pilot Reuse Strategy Maximizing the Weighted-Sum-Rate in Massive MIMO Systems

## TL;DR

This paper proposes an optimal pilot assignment strategy for multi-cell massive MIMO systems with user priorities, maximizing weighted sum rate by selectively reusing pilots, outperforming conventional full reuse methods.

## Contribution

It derives a closed-form solution for the optimal pilot assignment that accounts for user priorities and demonstrates improved performance over traditional methods.

## Key findings

- Optimal pilot assignment improves weighted sum rate.
- Extra pilot sets outperform full reuse in various conditions.
- Closed-form solution is intuitive and practical.

## Abstract

Pilot reuse in multi-cell massive multi-input multi-output (MIMO) system is investigated where user groups with different priorities exist. Recent investigation on pilot reuse has revealed that when the ratio of the coherent time interval to the number of users is reasonably high, it is beneficial not to fully reuse pilots from interfering cells. This work finds the optimum pilot assignment strategy that would maximize the weighted sum rate (WSR) given the user groups with different priorities. A closed-form solution for the optimal pilot assignment is derived and is shown to make intuitive sense. Performance comparison shows that under wide range of channel conditions, the optimal pilot assignment that uses extra set of pilots achieves better WSR performance than conventional full pilot reuse.