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Using Waste Factor to Optimize Energy Efficiency in Multiple-Input Single-Output (MISO) and Multiple-Input Multiple-Output (MIMO) Systems

Mingjun Ying, Dipankar Shakya, Theodore S. Rappaport

TL;DR

This work introduces Waste Factor ($W$) and Waste Figure (WF) as a unified KPI to quantify power efficiency in cascaded and parallel wireless systems, extending Friis’s cascade theory to quantify wasted power in $MISO$, $SIMO$, and $MIMO$ architectures. It derives closed-form $W$ expressions for non-coherent and coherent combining across MISO, SIMO, and MIMO, including general multi-antenna configurations, and develops a RAN-level analysis linking channel losses to system-wide waste ($W$). The paper validates the framework with a 28 GHz CoMP simulation, showing that network densification reduces WF and improves energy efficiency, while also providing a practical methodology to evaluate power waste along the entire source-to-sink chain. These contributions offer a flexible, system-wide tool for optimizing energy efficiency in modern wireless networks, with potential applications in beamforming, RF-on/off strategies, and ring-topology networks.

Abstract

This paper introduces Waste Factor (W) and Waste Figure (WF) to assess power efficiency in any multiple-input multiple-output (MIMO) or single-input multiple-output (SIMO) or multiple-input single-output (MISO) cascaded communication system. This paper builds upon the new theory of Waste Factor, which systematically models added wasted power in any cascade for parallel systems such as MISO, SIMO, and MIMO systems, which are prevalent in current wireless networks. Here, we also show the advantage of W compared to conventional metrics for quantifying and analyzing energy efficiency. This work explores the utility of W in assessing energy efficiency in communication channels, within Radio Access Networks (RANs).

Using Waste Factor to Optimize Energy Efficiency in Multiple-Input Single-Output (MISO) and Multiple-Input Multiple-Output (MIMO) Systems

TL;DR

This work introduces Waste Factor () and Waste Figure (WF) as a unified KPI to quantify power efficiency in cascaded and parallel wireless systems, extending Friis’s cascade theory to quantify wasted power in , , and architectures. It derives closed-form expressions for non-coherent and coherent combining across MISO, SIMO, and MIMO, including general multi-antenna configurations, and develops a RAN-level analysis linking channel losses to system-wide waste (). The paper validates the framework with a 28 GHz CoMP simulation, showing that network densification reduces WF and improves energy efficiency, while also providing a practical methodology to evaluate power waste along the entire source-to-sink chain. These contributions offer a flexible, system-wide tool for optimizing energy efficiency in modern wireless networks, with potential applications in beamforming, RF-on/off strategies, and ring-topology networks.

Abstract

This paper introduces Waste Factor (W) and Waste Figure (WF) to assess power efficiency in any multiple-input multiple-output (MIMO) or single-input multiple-output (SIMO) or multiple-input single-output (MISO) cascaded communication system. This paper builds upon the new theory of Waste Factor, which systematically models added wasted power in any cascade for parallel systems such as MISO, SIMO, and MIMO systems, which are prevalent in current wireless networks. Here, we also show the advantage of W compared to conventional metrics for quantifying and analyzing energy efficiency. This work explores the utility of W in assessing energy efficiency in communication channels, within Radio Access Networks (RANs).
Paper Structure (20 sections, 37 equations, 6 figures)

This paper contains 20 sections, 37 equations, 6 figures.

Table of Contents

  1. Introduction
  2. Advantages of the Waste Factor Compared to Conventional Energy Efficiency Metrics
  3. Noise Factor and Waste Factor Fundamentals
  4. Quantifying Additive Noise with Noise Factor
  5. Quantifying Additive Wasted Power with Waste Factor
  6. W Analysis for Parallel Communication Systems
  7. W for Multiple-Input Single-Output (MISO) System
  8. W for non-coherent combining MISO
  9. W for coherent combining MISO
  10. W for Single-Input Multiple-Output (SIMO) System
  11. W for non-coherent combining SIMO
  12. W for coherent combining SIMO
  13. W for Multiple-Input Multiple-Output (MIMO) System
  14. W for non-coherent combining MIMO
  15. W for coherent combining MIMO
  16. ...and 5 more sections

Figures (6)

  • Figure 1: A two TX and one RX MISO communication system.
  • Figure 2: A MISO system with M paralleled input cascade.
  • Figure 3: A SIMO system with M paralleled output cascade.
  • Figure 4: A two-input and two-output MIMO system.
  • Figure 5: General structure of the RU and UE.
  • ...and 1 more figures