# Cross-Layer Stream Allocation of mMIMO-OFDM Hybrid Beamforming Video Communications

## TL;DR

This paper introduces a new method for improving video quality in uplink mmWave communications by optimizing data stream allocation across different system layers.

## Contribution

The novel contribution is an iterative cross-layer data stream allocation framework that maximizes PSNR for uplink mMIMO-OFDM video communications.

## Key findings

- The proposed cross-layer scheme improves PSNR by 0.4 to 1.14 dB compared to conventional methods for 4–6 users.
- The framework allows users with lower PSNR to dynamically contend for data streams through iterative refinement.
- The method increases computational complexity by 1.8 to 2.3× due to requiring 3.6–5.8 iterations.

## Abstract

This paper proposes a source encoding rate control and cross-layer data stream allocation scheme for uplink millimeter-wave (mmWave) multi-user massive MIMO (MU-mMIMO) orthogonal frequency division multiplexing (OFDM) hybrid beamforming video communication systems. Unlike most previous studies that focus on the downlink scenario, our proposed scheme optimizes the uplink transmission while also addressing the limitation of prior works that only consider single-data-stream users. A key distinction of our approach is the integration of cross-layer resource allocation, which jointly considers both the physical layer channel state information (CSI) and the application layer video rate-distortion (RD) function. While traditional methods optimize for spectral efficiency (SE), our proposed method directly maximizes the peak signal-to-noise ratio (PSNR) to enhance video quality, aligning with the growing demand for high-quality video communication. We introduce a novel iterative cross-layer dynamic data stream allocation scheme, where the initial allocation is based on conventional physical-layer data stream allocation, followed by iterative refinement. Through multiple iterations, users with lower PSNR can dynamically contend for data streams, leading to a more balanced and optimized resource allocation. Our approach is a general framework that can incorporate any existing physical-layer data stream allocation as an initialization step before iteration. Simulation results demonstrate that the proposed cross-layer scheme outperforms three conventional physical-layer schemes by 0.4 to 1.14 dB in PSNR for 4–6 users, at the cost of a 1.8 to 2.3× increase in computational complexity (requiring 3.6–5.8 iterations).