Development of an Improved Dynamic Algorithm to Enhance Energy Saving in Long Term Evolution Mobile Access Networks
CHAPTER ONE
AIM AND OBJECTIVES
The aim of this research is the development of a dynamic algorithm to improve energy saving in LTE mobile access networks while guaranteeing the quality of service offered to mobile stations.
The objectives of this research work are as follows:
- Development of a dynamic algorithm for improving energy saving of LTE access network.
- Development of an energy saving analysis MATLAB graphical user interface(GUI).
- Evaluation of the energy savings resulting from the developed
- Validation of the developed algorithm by comparing its performance in terms of the energy saving and blocking probability with the“always-on” algorithm by Chiaraviglio et al., (2012) and the “sleep-wake” algorithmby Hossain et al.,(2013).
CHAPTER TWO
LITERATURE REVIEW
INTRODUCTION
This chapter is divided into two parts. The first part discussed the fundamental concepts relevant to the study and the second part provides a review of related prior research works.
REVIEW OF FUNDAMENTAL CONCEPTS
This sub-section presents an overview of concepts fundamental to the research work and a review of standard algorithms for energy saving in mobile cellular networks:
LTE Radio Access Scheme
LTE, marketed as fourth generation (4G) LTE, is a standard for wireless communication of high-speed data for mobile phones and data terminals. The standard is developed by the 3GPP(Adeyemi and Ike, 2013). LTE as a wireless access standard supersedes the GSM and UMTS for increased network capacities. This is because LTE develop a framework for the evolution of the 3GPP radio access technology towards a high-data-rate, low-latency and packet-optimized radio access technology(Mishra and Mathur, 2014). Thus, the main objective of LTE among others are as follows(Adeyemi and Ike, 2013):
- Significant increase in peak data rate e.g. 100Mbps (downlink) and 50Mbps(Uplink)
- Significantly improved spectrum efficiency
- Scalable bandwidth up to 20MHz (lowest possible bandwidth is:25MHz)
- Low-latency of 1ms
Orthogonal frequency division multiple access (OFDMA) is used in the LTE downlink access technology. The system supports a scalable bandwidth of up to 20MHz, with smaller bandwidths of 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz and 15 MHz to allow for the operations of different sized spectrum allocations(Adeyemi and Ike, 2013).OFDMA breaks the available bandwidth into many narrow sub carriers and transmits the data in parallel streams. Orthogonal frequency division multiplexing (OFDM) extends the Frequency division multiplexing(FDM) to provide a very flexible high capacity multiple access scheme. OFDM is a radio access technology that subdivides the bandwidth available for signal transmission into a multitude of narrowband subcarriers. The transmission duration is divided into short slots to create an OFDM block. In LTE, such an OFDM block is labelled a resource element. The available bandwidth and a duration called frame are divided into a number of resource element. Multiple resource elements are combined to constitute a resource block. When OFDM is used to grant mobile stations access to the shared transmission medium, the wireless medium is inherently shared and wireless transmissions occur simultaneously in resources such as frequency and time. The access scheme using the OFDM technology is called OFDMA.
CHAPTER THREE
MATERIALS AND METHODS
INTRODUCTION
This chapter describes the detailed procedure carried out in modeling the LTE cellular environment, energy saving of the LTE mobile network and the quality of service constraint. The development of the dynamic energy saving algorithm, MATLAB graphical user interface (GUI) for the simulation and analysis of the energy saving are also covered in this chapter
CHAPTER FOUR RESULTS AND DISCUSSIONS
INTRODUCTION
This chapter presents the result discussion of the mobile station distribution factor, instantaneous power consumption, total energy consumed by the simulated LTE access network eNodeBs, the energy saving of the proposed dynamic energy saving algorithm and its validation.
CHAPTER FIVE
SUMMARY, CONCLUSION AND RECOMMENDATIONS
INTRODUCTION
This chapter presents a summary of the research work, the limitations that were observed during the research work, the recommendation for further work and the conclusion.
SUMMARY
The dynamic algorithm for improving energy saving in LTE mobile networks through off mode, sleep mode and multi-cell cooperation utilization at the eNodeBs has been developed. The LTE network environment and the eNodeBs power consumption models were developed with a view to implementing the dynamic energy saving algorithm which comprises of the energy estimation algorithm and the load/traffic sharing algorithm. The energy estimation algorithm estimate the energy consumption of the eNodeBs when they are powered on irrespective of their utilization. The load/traffic sharing algorithm transfer traffic between eNodeBs which enables the off mode, sleep mode and multi-cell cooperation of eNodeBs.The dynamic energy saving algorithm was implemented on MATLAB 2013b environment. The simulation and analysis of the energy saving resulted from the energy saving algorithm was done using the developed MATLAB graphical user interface called the LTE network energy saving analysis software based on dynamic scheduling for the energy load proportionality constant ranging from 0 to 1 at a step of 0.1.Validation of the proposed energy saving algorithm was done by comparing its performance in terms of the energy saving and call blocking probability with the “always-on” algorithm by Chiaraviglio et al., (2012) and the “sleep-wake” algorithm by Hossain et al., (2013).
CONCLUSION
The development of the proposed dynamic algorithm for improving energy saving in LTE mobile access networks through off mode, sleep mode, active mode and multi-cell cooperation utilization at the eNodeBs has been presented in this research work. The dynamic energy saving algorithm which is an integration of the energy estimation algorithm and the load/traffic sharing algorithm was implemented MATLAB 2013b environment. A MATLAB GUI program called LTE network energy saving analysis software base on dynamic scheduling was developed to run the proposed dynamic energy saving algorithm for the purpose of simulation and performance analysis. The results show that the energy saving in the network increases as the energy load proportionality constant and call blocking probability increases. The proposed energy saving algorithm achieved the highest energy saving of and when the energy load proportionality constant equals 1 with respect to the “always-on” algorithm by Chiaraviglio et al., (2012) and “sleep-wake” algorithm by Hossain et al., (2013) with energy saving of 0% and 40% respectively, while guaranteeing a call blocking probability of 1%.
LIMITATIONS
During the course of this research work, certain limitations were observed which are itemized as follows:
- The proposed dynamic energy saving algorithm assumed constant number of uniformly distributed mobile stations and equal number of randomly distributed active mobile stations for each of the eNodeBs
- The eNodeBs in the proposed dynamic energy saving algorithm were dimensioned to have equal capacity
- The proposed dynamic energy saving algorithm considered only constant rate traffic types.
RECOMMENDATIONS FOR FURTHER WORK
Future works should consider the following areas:
- This research work only focus on downlink communication (that is from eNodeB to mobile station). Nevertheless, it would be interesting to develop a dynamic energy saving algorithm for eNodeBs that considers downlink and uplink trafficsjointly.
- Another extension of this research work can be to develop dynamic energy saving algorithms considering heterogeneous LTE networks, consisting of different types of eNodeBs, such as macro, micro, femto eNodeBs and even WiFi access points, which have different transmission powers as well as total operational
REFERENCES
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