# Cross-Layer Optimization of MIMO-Based Mesh Networks with Gaussian Vector Broadcast Channels

## TL;DR

This paper explores the joint optimization of power allocation and routing in MIMO mesh networks using Gaussian vector broadcast channel theory, demonstrating significant performance improvements with advanced coding strategies.

## Contribution

It introduces a novel cross-layer optimization framework leveraging channel duality and advanced algorithms for MIMO mesh networks, addressing the non-convexity of the problem.

## Key findings

- Achieved a 34.4% network performance gain with DPC.
- Developed an efficient solution combining multiple optimization techniques.
- Addressed the non-convex optimization challenge in MIMO mesh networks.

## Abstract

MIMO technology is one of the most significant advances in the past decade to increase channel capacity and has a great potential to improve network capacity for mesh networks. In a MIMO-based mesh network, the links outgoing from each node sharing the common communication spectrum can be modeled as a Gaussian vector broadcast channel. Recently, researchers showed that ``dirty paper coding'' (DPC) is the optimal transmission strategy for Gaussian vector broadcast channels. So far, there has been little study on how this fundamental result will impact the cross-layer design for MIMO-based mesh networks. To fill this gap, we consider the problem of jointly optimizing DPC power allocation in the link layer at each node and multihop/multipath routing in a MIMO-based mesh networks. It turns out that this optimization problem is a very challenging non-convex problem. To address this difficulty, we transform the original problem to an equivalent problem by exploiting the channel duality. For the transformed problem, we develop an efficient solution procedure that integrates Lagrangian dual decomposition method, conjugate gradient projection method based on matrix differential calculus, cutting-plane method, and subgradient method. In our numerical example, it is shown that we can achieve a network performance gain of 34.4% by using DPC.