Throughput Analysis and Energy Efficiency Optimization for Standalone LTE-U Networks with Randomly Delayed CSI

TL;DR

This paper analyzes how randomly delayed CSI affects LTE-U network throughput and energy efficiency, proposing joint optimization of MAC and CSI feedback to improve performance and coexistence with Wi-Fi.

Contribution

It introduces a comprehensive analysis of delayed CSI impact and proposes low-complexity algorithms for joint MAC and CSI feedback optimization in LTE-U networks.

Findings

CSI feedback scheme significantly influences LTE-U performance

Optimized algorithms improve energy efficiency and throughput

Traffic load and scheduling choices affect coexistence outcomes

Abstract

To coexist with Wi-Fi friendly, a standalone long-term evolution network over unlicensed spectrum (LTE-U) under listen-before-talk (LBT) mechanism can only access channel in a random and intermittent way, which results in random and time-variant delay in both data and signaling transmissions. In this work, we explore the impact of randomly delayed channel state information (CSI) on the performance of a standalone LTE-U network by analyzing its downlink throughput and users' energy efficiency (EE) under different CSI feedback schemes and frequency-domain schedulers. Further, aiming at maximizing users' EE of a standalone LTE-U network while guaranteeing fair coexistence with Wi-Fi, joint optimization on the medium access control (MAC) protocol and CSI feedback scheme is studied. Due to the non-convex and non-concave characteristic of the formulated optimization problems, decomposition-based low-complexity yet efficient algorithms are proposed. Simulation results not only verify the analysis and the effectiveness of the proposed algorithms but also show diverse impacts of CSI feedback scheme, frequency-domain scheduler, and traffic load of Wi-Fi on the standalone LTE-U network performance.