# LoRaWAN Communication Protocols: A Comprehensive Survey under an Energy Efficiency Perspective
## 5 Conclusions  
Choosing a communication protocol has serious consequences on the performance of LoRaWAN and on its energy consumption. This paper provides an extensive literature survey on communication protocols of LoRaWANs. We examine energy consumption both at the PHY, MAC and network layers in LoRaWAN. In light of energy efficiency, we have identified critical aspects of the design of a LoRaWAN communication protocol. For the design of a communication protocol focused on energy efficiency, a number of challenges should be considered because as we have discussed, there is an interrelation between different mechanisms that minimize energy consumption, as well as influence on performance of LoRaWAN. Research efforts are revisited, potential solutions are highlighted, and research directions for a novel green LoRaWAN communication protocol are discussed, emphasizing energy efficiency, robustness, and scalability.  
Methodology, M.L.; Writing--original draft preparation, K.B., I.K., T.D.; writing--review and editing, M.L., T.K., A.-A.A.B.; supervision, M.L.; project administration, M.L.; All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research has been co-financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH--CREATE--INNOVATE (project code T2 EDK-04211).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** No data were used to support the findings of this study.  
**Conflicts of Interest:** The authors declare no conflict of interest.  
**Abbreviations**  
3 GPP  
Third Generation Partnership Project  
ABP  
Activation By Personalization  
ACK  
Acknowledgement  
ADR  
Adaptive Data Rate  
AES  
Advanced Encryption Standard  
AODV  
Ad hoc On-Demand Distance Vector  
AS  
Application Server  
BW  
Bandwidth  
CA  
Clustering Approaches  
CAD  
Channel Activity Detection  
CCT  
Clustering and Concurrent Transmission  
CDMA  
Code Division Multiple Access  
CF  
Carrier Frequency  
CR  
Coding Rate  
CRC  
Cyclic Redundancy Check  
CSMA  
Carrier Sensing Multiple Access  
CSMA/CA  
Carrier Sensing Multiple Access/Collision Avoidance  
CSS  
Chirp Spread Spectrum  
DR  
Data Rate  
DC  
Duty Cycle  
EB
Enhanced Beacons  
ETSI  
European Telecommunications Standards Institute  
FDMA  
Frequency Division Multiple Access  
GW  
Gateway  
GPS  
Geolocation Positioning System  
HWMP  
Hybrid Wireless Mesh Protocol  
ID  
Identifier  
IoT  
Internet of Things  
IP  
Internet Protocol  
ISM  
Industrial, Scientific And Medical  
LBT  
Listen Before Talk  
LLN  
Lossy Network  
LoRa  
Long Range  
LoRaWAN  
Long Range Wide Area Network  
LPSAN  
Low Power Short Area Network  
LPWAN  
Low Power Wide Area Network  
LTE  
Long-term evolution  
MAC  
Medium Access Control  
MEE  
Minimal Energy Efficiency  
mIoT  
Massive Internet of Things  
NB-IoT  
Narrow Band Internet of Things  
NCA  
Non-clustering Approaches