# Interference-Alignment and Soft-Space-Reuse Based Cooperative Transmission for Multi-cell Massive MIMO Networks

## TL;DR

This paper introduces a cooperative transmission scheme combining interference alignment and soft-space reuse for multi-cell massive MIMO networks, aiming to enhance capacity while reducing CSI overhead.

## Contribution

It proposes a novel IA-SSR framework with two-stage precoding, optimal power allocation, and a low-cost channel estimator for efficient massive MIMO operation.

## Key findings

- Significant capacity improvements demonstrated through numerical results
- Effective reduction of CSI acquisition overhead
- Enhanced performance for cell-edge users

## Abstract

As a revolutionary wireless transmission strategy, interference alignment (IA) can improve the capacity of the cell-edge users. However, the acquisition of the global channel state information (CSI) for IA leads to unacceptable overhead in the massive MIMO systems. To tackle this problem, in this paper, we propose an IA and soft-space-reuse (IA-SSR) based cooperative transmission scheme under the two-stage precoding framework. Specifically, the cell-center and the cell-edge users are separately treated to fully exploit the spatial degrees of freedoms (DoF). Then, the optimal power allocation policy is developed to maximize the sum-capacity of the network. Next, a low-cost channel estimator is designed for the proposed IA-SSR framework. Some practical issues in IA-SSR implementation are also discussed. Finally, plenty of numerical results are presented to show the efficiency of the proposed algorithm.