Energy efficiency analysis of hybrid-ARQ relay-assisted schemes in LTE-based systems

Mohamad Maaz,Maryline Hélard,Philippe Mary,Jordane Lorandel,Jean-Christophe Prévotet

doi:10.1186/s13638-016-0520-9

Mohamad Maaz, Maryline Hélard + Show 3 more

Open Access

https://doi.org/10.1186/s13638-016-0520-9

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Abstract

This work deals with the analysis of energy efficiency (EE) issues of hybrid automatic repeat request (HARQ) protocols such as Chase combining (CC) and incremental redundancy (IR), in a LTE baseband-based half-division duplex relay-assisted network. The EE performance is highly dependent on delay and circuitry power consumption, i.e., baseband and radio-frequency (RF) parts, and the effects of these components are investigated for amplify and forward (AF) and decode and forward (DF) protocols. Moreover, a realistic estimation of the baseband power consumption is provided. Our contributions in this paper can be summarized as follows: (1) an accurate estimation of power consumption of the main blocks of the LTE baseband is provided based on a real field-programmable gate array (FPGA) target and is integrated to a global energy consumption model (2) based on the previous power consumption evaluation; energy-efficiencies of DF protocol with HARQ-CC and HARQ-IR are investigated with various modulation orders; in addition, a quite insightful study of the energy efficiency-spectral efficiency trade-off is conducted, and (3) DF and AF protocols with HARQ are compared in terms of EE, and recommendations are suggested in order to jointly enhance the QoS and the energy efficiency of wireless systems.

Highlights

1.1 Context Energy consumption devoted to implement information and communication technologies is becoming larger and larger over the years
In 2012, 4.7 % of the global electric consumption was due to networks, data centers, and computers, and 3 % of the greenhouse gas emission was due to the ICT (Information & Communications Technologies) sector and it will not get better; the number of devices increases (+11 % per year), traffic demand increases (+21 % per year), and wireless technologies represent a larger and larger part of the ICT energy consumption [1, 2]
It focuses on EE evaluation and EE-spectral efficiency (SE) trade-off for hybrid automatic repeat request (HARQ)-Chase combining (CC) and HARQincremental redundancy (IR) protocols and two relaying schemes, i.e., AF and decode and forward (DF)

Summary

Introduction

1.1 Context Energy consumption devoted to implement information and communication technologies is becoming larger and larger over the years. Hardware power consumption has been proven to have a significant impact on EE [27] Circuits such as field-programmable gate array (FPGA) devices have been considered as a viable solution to support advanced signal processing algorithms that are implemented in wireless embedded communication systems. These devices can support complex applications due to the large amount of available hardware resources. 1.3 Contributions This paper aims at quantifying the impact of baseband power consumption on EE of LTE relay-assisted communication for small cell sizes It focuses on EE evaluation and EE-SE trade-off for HARQ-CC and HARQincremental redundancy (IR) protocols and two relaying schemes, i.e., AF and DF.

System model

Relaying protocols DF protocol

Hardware baseband processing energy consumption model

System performance analysis

Findings

Conclusions