Increased energy efficiency in LTE networks through reduced early handover

“A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the degree of Doctor of Philosophy”.Long Term Evolution (LTE) is enormously adopted by several mobile operators and has been introduced as a solution to fulfil ever-growing Users (UEs) data requirements in cellular networks. Enlarged data demands engage resource blocks over prolong time interval thus results into more dynamic power consumption at downlink in Basestation. Therefore, realisation of UEs requests come at the cost of increased power consumption which directly affects operator operational expenditures. Moreover, it also contributes in increased CO2 emissions thus leading towards Global Warming. According to research, Global Information and Communication Technology (ICT) systems consume approximately 1200 to 1800 Terawatts per hour of electricity annually. Importantly mobile communication industry is accountable for more than one third of this power consumption in ICT due to increased data requirements, number of UEs and coverage area. Applying these values to global warming, telecommunication is responsible for 0.3 to 0.4 percent of worldwide CO2 emissions. Moreover, user data volume is expected to increase by a factor of 10 every five years which results in 16 to 20 percent increase in associated energy consumption which directly effects our environment by enlarged global warming. This research work focuses on the importance of energy saving in LTE and initially propose bandwidth expansion based energy saving scheme which combines two resource blocks together to form single super RB, thereby resulting in reduced Physical Downlink Control Channel Overhead (PDCCH). Thus, decreased PDCCH overhead helps in reduced dynamic power consumption up to 28 percent. Subsequently, novel reduced early handover (REHO) based idea is proposed and combined with bandwidth expansion to form enhanced energy ii saving scheme. System level simulations are performed to investigate the performance of REHO scheme; it was found that reduced early handover provided around 35% improved energy saving while compared to LTE standard in 3rd Generation Partnership Project (3GPP) based scenario. Since there is a direct relationship between energy consumption, CO2 emissions and vendors operational expenditure (OPEX); due to reduced power consumption and increased energy efficiency, REHO subsequently proven to be a step towards greener communication with lesser CO2 footprint and reduced operational expenditure values. The main idea of REHO lies in the fact that it initiate handovers earlier and turn off freed resource blocks as compare to LTE standard. Therefore, the time difference (Transmission Time Intervals) between REHO based early handover and LTE standard handover is a key component for energy saving achieved, which is estimated through axiom of Euclidean geometry. Moreover, overall system efficiency is investigated through the analysis of numerous performance related parameters in REHO and LTE standard. This led to a key finding being made to guide the vendors about the choice of energy saving in relation to radio link failure and other important parameters

Energy Management in LTE Networks

Wireless cellular networks have seen dramatic growth in number of mobile users. As a result, data requirements, and hence the base-station power consumption has increased significantly. It in turn adds to the operational expenditures and also causes global warming. The base station power consumption in long-term evolution (LTE) has, therefore, become a major challenge for vendors to stay green and profitable in competitive cellular industry. It necessitates novel methods to devise energy efficient communication in LTE. Importance of the topic has attracted huge research interests worldwide. Energy saving (ES) approaches proposed in the literature can be broadly classified in categories of energy efficient resource allocation, load balancing, carrier aggregation, and bandwidth expansion. Each of these methods has its own pros and cons leading to a tradeoff between ES and other performance metrics resulting into open research questions. This paper discusses various ES techniques for the LTE systems and critically analyses their usability through a comprehensive comparative study

Euclidean geometry axioms assisted target cell boundary approximation for improved energy efficacy in LTE systems

Long Term Evolution (LTE) facilitates users with high data rate at the cost of increased energy consumption. The base station, also known as eNodeB, is the main energy hungry elements in LTE networks. Since power consumption directly affects the operational expenditure, thus the provision of cost-effective services with adequate quality of service has become a major challenge. This paper investigates reduced early handover (REHO) scheme aimed at increased energy efficiency in LTE systems. REHO, compared to standard LTE A3 event, initiates early handover, thereby resulting into reduced energy consumption. Axioms of Euclidean geometry are employed to estimate the target cell boundary towards calculation of the time difference ΔT between standard LTE and REHO. Performance analysis involved comparison of standard LTE with REHO in the presence of varying velocity and Hysteresis values. Early handover ΔT in REHO is calculated in terms of transmission time intervals and results into improved energy efficiency at the cost of slightly increased radio link failure (RLF). The key finding of the work is the nonsensitivity of users towards velocity in standard LTE, whereas REHO leads to considerably improved energy efficiency at low velocity thereby making it an advantageous scheme for urbanised densely deployed LTE networks. Outcomes provided also deliver a guideline for vendors to choose suitable value of hysteresis, while achieving appropriate results of energy saving and RLF

Reduced early handover for energy saving in LTE networks

Long-term evolution (LTE) facilitates users with high data rate at the cost of increased energy consumption. eNodeBs are main energy hungry elements in LTE networks. Since power consumption directly affects the operational expenditure, thus the provision of cost effective services with adequate quality of service (QoS) has become a major challenge. This letter exploits the phenomenon of handover and presents a novel hybrid idea of reduced early handover with bandwidth expansion to achieve improved energy saving in LTE networks. Through system level simulations, the effectiveness of the proposed scheme is demonstrated. It is shown that the proposed energy saving scheme achieves around 35% energy efficiency compared to benchmark and other state of the art while still maintaining acceptable level of radio link failure

Joint Resource Blocks Switching Off and Bandwidth Expansion for Energy Saving in LTE Networks

In the wireless networks community, Long Term Evolution (LTE) facilitates users with high data rate at the cost of increased energy consumption. The base station (BS) also known as eNodeBs are the main energy hungry elements in LTE networks. Power is consumed by different components of BS such as Baseband Unit (BB), Power Amplifier (PA) and other cooling systems. Since power consumption directly affects the Operational Expenditure (OPEX), thus the provision of cost effective services with adequate quality of service (QoS) has become a major challenge. Moreover, the energy consumed by Information and Communication Technology (ICT) appliances contributes 2% to global warming (CO2 emission), which is another significant problem. This paper presents a joint resource blocks switching off and bandwidth expansion energy saving scheme for LTE networks. Performance analysis of the proposed scheme has revealed that it is around 29% energy efficient as compared to the benchmark LTE systems

Energy Efficiency Led reduced CO2 Emission in Green LTE Networks

The technological advancements in smart phones and their applications have rapidly raised the number of users and their data demands. To fulfil enlarged user’s data requirements, Basestation (BS) engages their resources over prolong time intervals at the cost of increased power consumption. In parallel, operators are expanding network infrastructure by employing additional BSs which also adds in power consumption. This directly increases carbon emission (CO2) thus results in to more global warming. Therefore, Information and Communication Technology (ICT) has become major contributor in global warming while mobile communication is one of the key contributors within ICT. This paper investigates reduced CO2 emission through decreased power consumption in LTE networks. Proposed energy saving scheme is validated through the analysis of various performance related parameters in MATLAB. Results have proven that proposed scheme reduces CO2 emission by 2.10 tonnes per BS

Nonsurgical healing of a large periapical lesion associated with a two-rooted maxillary lateral incisor

Maxillary lateral incisors are teeth which have shown a high incidence of anatomic variation. Correct diagnosis along with proper treatment plan ensures a successful treatment outcome in these teeth. This paper reports a nonsurgical healing of a two-rooted maxillary lateral incisor with a large periapical lesion