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Improving Network Efficiency: Vendors offer cite-centric solutions

October 31, 2011
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Rajendu Choubisa, Key Account Manager, CommScope

With the number of connected devices and internet usage increasing substantially, the power needs of the telecom sector have been growing rapidly. To illustrate, let us consider that globally there are 5 billion subscribers, 5 million base stations and 2,500 core network components. The assumption is that each subscriber uses one wireless device per day and each base station consumes about 1.7 kW of energy on an average. Based on these parameters, 2 TWh of energy per year is consumed by the user, 75 TWh of energy per year is consumed by the base station while approximately 1 TWh of energy is being consumed by the core network. Overall, the consumer’s carbon footprint equals approximately 1 million tonnes (mt) per year, base stations emit 38 mt of carbon dioxide each year, while the core network releases nearly 0.5 mt of carbon dioxide per year.

Today, reducing the carbon footprint is at the top of several Asian operators’ to-do list. Vodafone plans to reduce its absolute carbon dioxide emissions by 50 per cent by 2020 as compared to its emission levels in 2006-07, while Bharti Airtel has embarked on a drive to adopt cleaner technologies in order to reduce its dependence on diesel backup for towers.

To achieve this, numerous energy conservation and site management solutions are being implemented. The basis for these solutions is examining the impact of energy consumption at wireless cell sites. For example, 65 per cent of a telecom service provider’s power is consumed by the mobile network. In this scenario, if 20 per cent energy savings can be achieved at 10,000 cell sites (assuming the average power consumed per site to be 5 kW), the annual savings will be 87.6 million kWh of electricity usage. This is roughly equivalent to 62,000 metric tonnes of carbon dioxide.

For a typical cell site in Asia, power consumption can be broken down into the following components: 2,200 W is consumed by the radio unit, 700 W by the climate equipment, 300 W by the base band, 370 W by  power supply and 120 W by the antenna feeder.

The major energy utilising components include direct current (DC) power, radio equipment and a shelter cooling facility. In this context, CommScope suggests using a fuel cell for power backup, various shelter cooling solutions, and a hybrid fibre feeder for split radios.

Using a fuel cell for power back-up will remove over 13,820 kg per site of greenhouse gas emissions from the atmosphere; implementing various shelter cooling solutions would save 11-20 per cent of power consumption; and using a hybrid fibre feeder for split radios would save over 33 per cent power consumption at the cellular site. Besides, various cost benefits will accrue from using a fuel cell as opposed to a diesel generator (DG) set. These include lower capex and opex, and environmental benefits.

The energy consumed by the cooling system at a cell site can be reduced by shortening the number of hours an air conditioner (AC) is used and by adding a secondary cooling system. The AC could also be replaced with an alternative cooling solution. CommScope’s alternative solution is based on the concept of free air cooling. It involves using a remote fibre feeder cable that provides a combination of power conductors and fibre into a single high-performance cable.

Samar Mittal, Head, Services Sales, India, Nokia Siemens Networks

The energy consumption of cellular operators is currently divided into base transceiver station (BTS) sites (65 per cent); switch sites (21 per cent); offices, facilities, etc. (12 per cent); retail (1 per cent); and vehicle maintenance (1 per cent).

The main question going forward is how does one optimise energy consumption at BTS sites?

This can be achieved in a number of ways. First, network utilisation must be re-looked at. The network must be flexible at all times, even during peak traffic hours. Second, the site design must be reconsidered with an aim to reduce the carbon footprint to zero. Third, the energy chain must be revised to optimise the available energy sources. The aim should be to deploy green energy solutions in an innovative manner. Fourth, the energy sources used at the site must be re-examined and renewable energy solutions must be deployed.

Nokia Siemens Networks (NSN) has undertaken a number of measures to reduce energy consumption and enhance energy efficiency in its radio product portfolio. For example, capacity has been enhanced at each of the sites instead of setting up newer sites. Voice capacity at each site has been doubled with software rather than by doubling the number of transceivers. Moreover, various power efficiency features, site-centric solutions and enhanced coverage have been implemented. In terms of site solutions, the radio frequency has been placed closer to the antenna, thereby eliminating feeder losses; renewable energy sources have been used; a BTS with the lowest power consumption has been deployed; and air-conditioning has been done away with. NSN’s Orthogonal Sub-Channel feature reduces BTS power consumption by up to 50 per cent.

Other energy modernising solutions include free cooling (which saves energy by 20 per cent); passive cooling (whereby 25 per cent energy is saved); underground batteries (which double battery life); solar sun roofs (helps save 15 per cent energy) and solar paint (saves energy by 5-10 per cent).

In all, NSN’s green energy solutions are aimed at reducing opex by improving network utilisation, site design and end-to-end energy management.

Anup Sharma, General Manager, Managed Services, Ericsson India

Off-grid tower sites in India currently use DG sets for more than 10 hours.  As a result, energy-related opex constitutes 40-55 per cent of the direct site opex; and rural penetration is a challenge, as energy-related opex per site is higher than the revenue generated per site.

Today, energy is a major cause of quality-related issues. On an average, 50 per cent of the issues in an operator’s network operation centre (NOC) are related to energy outages. Also, issues in energy supply cause lower cell availability and impact revenues and end-customer satisfaction, and increase churn rates.

The biggest energy-related challenges today are managing energy costs, ensuring network efficiency, unpredictable external forces and outages that impact revenue.

These can be addressed with the help of several solutions like using alternative energy sources, managed power and an energy-efficient site design; undertaking energy-saving measures and network modernisation; availing of consulting services; ensuring optimised power supply and network energy; undertaking site management and energy-control measures; implementing cooling concepts; and deploying energy-saving features.

As of now, the initiatives undertaken include deploying power-saving features, optimising energy utilisation, and applying capacity features and functionality that can handle more traffic on the same hardware.

However, several areas including site power, site climate, remote site management and alternative energy solutions still need to be explored. With regard to site power, a diesel-battery hybrid may be used for saving energy; the DG set may be resized; and durable batteries and high-efficiency rectifiers may be deployed. With regard to site climate, an enclosure layout should be used and the site temperature should be regularised. Moreover, insulation should be carried out at the site and free-cooling equipment, heat exchangers and a DC air-conditioner should be deployed. In terms of remote site management, power consumption monitoring should be undertaken and a smart cooling control mechanism should be used. Besides, alternative energy solutions like wind, solar and fuel cells need to be explored.

Going forward, a managed energy solution is likely to catch on. The solution includes design and deployment, operations (field and NOC), energy provision, and optimisation and management.

Also, additional opex savings can be achieved through passive infrastructure transformation. This will also ensure operational efficiency and reduced fuel consumption, leading to lower emissions, greater carbon credits (35 per cent to 45 per cent) and improved power supply. This, in turn, would result in increased network quality and availability.

Operators can obtain several benefits by deploying managed energy solutions. These include reduced opex due to increased energy efficiency across the network; increased adaptation to new environmental directives; minimised downtime risks in unstable power grid areas with no loss of income; cost-efficient off-grid expansion with alternative energy sources; and energy-efficient operations leading to competitive advantages.

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