Network Densification and Energy Efficiency

Abstract

The galloping pace of development in the field of wireless communication has left the world astounded over the last decade. But this has also led to a wild and inexcusable extravagant expenditure of energy. Due to the dynamic nature of wireless network, it has become imperative to focus more on energy efficiency and achieve desired Quality of Service (QoS). The challenge of diminishing the carbon footprint and cutting down the operating expenditures and keeping up with the bludgeoning demand for coverage and capacity is the main driving force or motivation behind studying energy efficiency of mobile networks and to delve into the latest research on power saving features.

Long Term Evolution (LTE) is our prime topic of focus as it has within a small span of time proved to be the right technology to cater to the requirements of the ever-growing demand and is widely considered to be the answer to future's new and existing wireless networks. The provision of quality service has to take into consideration the maximum utilization of LTE resources as it is profitable to both the operators and the environment. To be in harmony with this arrangement the requirements on energy performance will appertain to the specifications of immediate 5G networks. In LTE networks, indoor small cells are deployed in large volume to boost performance in areas with lousy macro coverage or high traffic demand that has botched the entire network. This type of network topology, that involves a mix of radio technologies and cell types working immaculately in a well organized manner is called a heterogeneous network (HetNet).

An attempt has been made to study the energy efficiency of various Het-Net deployments in disparate environments (dense urban, urban, sub-urban and rural). The small cells deployments examined are pico base stations and micro distributed-antenna-systems. A comparison has been made between dense and sparse deployment strategies with varying transmit powers. Furthermore, an investigation has been carried out to identify the potential for energy savings by placing the small cells into a low power sleep state under certain established conditions. Both brief sleep periods between transmissions which could be described like momentary muting, called discontinuous transmission (DTX), and lengthier sleep cycles during periods of little activity has been investigated. This thesis was carried out as a project at Ericsson Systems & Technology in Lund, Sweden 2016.

Popular Abstract

There is a famous saying that states "Wasting of power is an invitation to future darkness. So, for a better tomorrow, save energy today". This is so true that even some governments have adopted initiatives with a goal of reducing carbon footprints. The primary intent of this paper is to outline the significance of energy efficiency in contemporary telecommunication networks and espouse views and theories for optimizing network performance in terms of energy demands and have a feel of the evolving energy efficient technologies trends worldwide.

Telecommunications might be one of the industries consumers dislike most because of the sub-par service but a coming upheaval in communications technology could soon turn it into a smart, responsive provider of digital services which is both needed and appreciated. For decades, the telecom industry relied on a simple model: build the biggest network and then charge customers for the demands. But now, HetNet has undergone some major enhancements, network densification strategies in particular, to ensure unparalleled performance and synergy with the macro network. This has led to energy demand which is increasing at a fast pace all around the world and if not controlled it would lead to energy shortage. This can be minimized by just taking small smart measures. Bringing in some killer energy saving features could revolutionize the Telecom industry. Furthermore, it would promote the concept of green telecommunication networks and provide information about the power consumption within wireless communication networks. The aim is to introduce the reader to current green technologies and essentialize the necessity for energy efficiency in information and communication technology.

The term "Green Communications" has now become so ubiquitous that it is a quotidian routine to refer it in every Telecom conference. In Telecom networks "Green" would refer to minimizing consumption of energy through the use of energy efficient telecom technologies and renewable energy resources. According to a survey, the telecommunications sector accounts for roughly 4 percent of the global electricity consumption. To reduce energy consumption the Telecom sector has been actively participating in efforts to reduce energy consumption - both for economic rationale and for environmental reasons. The most marked project is the Energy Aware Radio and network TecHnologies (EARTH). Initiatives like EARTH has been helpful to pinpoint telecom-specific energy usage in the network infrastructure arena. By collaborating with research institutions and universities, EARTH's coordinated knowledge could easily influence our future network designs, with the goal of reducing carbon footprints.

Not to forget the ultimate goal is to obtain a full-blown throughput and improved performance. To begin with, a balance between performance and energy efficiency was struck, ensuring that the performance was not affected and, thus, keeping the energy in check. This was facilitated by applying a power model, traffic model and energy saving features. A power model was adopted after studying the base-band architecture comprehensively. The base station was broken down into different model components which were further split into sub-components till the most fundamental element was reached. Though it might appear complex, it
is not so and comparisons can be drawn with the divide and conquer algorithm where we recursively break down a component into sub-components until they become simple enough to be solved directly. A traffic model played an important role because of the uncharacteristic nature of data traffic. This model focused on three aspects- user activity, ratio of busy hour in a day and the ratio of active users in that busy hour. What followed next was exercising some efficient energy saving techniques to these models to give a rough picture of what could be achieved. These power saving features were applied to very different environments. This was done by aligning the subscribers uniformly for the simulations. Despite increased traffic and service expansion total network energy consumption was minimized by 30%.

An interesting observation was that highest savings was found in rural areas. It has been a common conviction that most energy savings can be made where traffic is high and so maximum efforts are devoted to this section and in doing so turning a blind eye to the wasteful energy consumption in other scenarios. This stems from our inadequacy to conceive the notion that our intent is to maximize energy efficiency which differs from total energy consumption. But the investigation has proved otherwise and it is now established that it is the rural area where maximum power savings can be realized.

I believe this work could be a good background for future studies. It is true that the study suggests that energy performance requires addressing mostly in low traffic situations but it could also be applied to generic scenarios. Only a handful of combinations(traffic model plus activity type) were picked for the simulations based on some calculated judgement but it would be riveting to witness if such substantial savings can be observed in some other scenarios.

• author: Das, Sarthak
• supervisor: Maria Kihl
• organization: Department of Electrical and Information Technology
• course: EITM02 20161
• year: 2018
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Cell Sleep, Densification, Efficiency, Energy, Energy Model, FPLC, HetNet, Lean Carrier, LTE, Macro, Micro Sleep, OFDM, Power Model, PSI, Traffic
• report number: LU/LTH-EIT 2018-676
• language: English
• id: 8963333
• date added to LUP: 2018-12-05 12:26:29
• date last changed: 2018-12-05 12:26:29