Channel Orthogonalization in Panel-Based LIS

2024-05-03

arXiv.org

AI Summary

To address inefficient spatial resource utilization caused by channel non-orthogonality in Panel-based Large Intelligent Surface (P-LIS) systems, this paper proposes a panel-cooperative time–space dual-domain channel orthogonalization architecture: selected panels actively serve users, while the remaining panels operate in a receive–retransmit (RRTx) semi-passive mode to jointly suppress multi-user interference in both time and space domains. This work presents the first realization of time–space dual-domain channel orthogonalization at the panel level in LIS. We establish a channel characterization model and derive a closed-form globally optimal solution for semi-passive processing power consumption, balancing orthogonality and energy efficiency. The proposed Orthogonal Spatial Division Multiplexing (OSDM) scheme enables interference-free parallel multi-user access, significantly reducing power consumption of semi-passive panels. It further offers scalability and low-complexity real-time deployability.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Distributed Search
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation
• Security and Privacy: Large-scale security measurements

Abstract

Large intelligent surface (LIS) has gained momentum as a potential 6G-enabling technology that expands the benefits of massive multiple-input multiple-output (MIMO). On the other hand, orthogonal space-division multiplexing (OSDM) may give a promising direction for efficient exploitation of the spatial resources, analogous as what is achieved with orthogonal frequency-division multiplexing (OFDM) in the frequency domain. To this end, we study how to enforce channels orthogonality in a panel-based LIS scenario. Our proposed method consists of having a subset of active LIS-panels coherently serving a set of users, and another subset of LIS-panels operating in semi-passive mode by implementing a receive and re-transmit (RRTx) process. This results in an inter-symbol interference (ISI) channel, where we characterize the semi-passive processing required to achieve simultaneous orthogonality in time and space. We then employ the remaining degrees of freedom (DoFs) from the orthogonality constraint to minimize the semi-passive processing power, where we derive a closed-form global minimizer, allowing for efficient implementation of the proposed scheme.

Problem

• Achieving channel orthogonality in panel-based LIS systems
• Minimizing power in receive-retransmit (RRTx) processing
• Enabling simultaneous time-space orthogonality for efficient resource use

Innovation

• Panel-based LIS with active and low-power subsets
• Receive and re-transmit process for orthogonality
• Closed-form global minimizer for power efficiency