During the rainy season roads are washed away, and diesel has to be helicoptered to mobile base stations not connected to the electrical grid, so it's easy to understand the communications industry's growing interest in energy-efficiency and renewable energy sources.

All mobile carriers are currently investigating how to improve energy efficiency, according to Gartner analyst Martin Gutberlet.

'The main driver is to reduce the cost of running mobile networks, but then you also get to reduce CO2 emissions as a bonus,' he said.

Just recently Vodafone announced it would reduce its carbon-dioxide emissions by 50 percent by 2020. The push makes sense from an environmental and business point of view, according to CEO Arun Sarin.

Vodafone started looking at energy efficiency two years ago, but as evidence has mounted of how carbon-dioxide affects the environment the company felt it was time to do more.

'Succeeding will be a big challenge, and today we don't know exactly how to do it,' said Ulrich Blau, senior manager Site Infrastructure & Energy, at Vodafone Group.

The primary focus should be on the mobile base stations, since they consume almost 70 percent of all energy in a mobile network, according to Ericsson.

There are a number of ways for mobile operators to become more energy efficient.

One way is to increase the temperature at which equipment will work, which reduces the energy needed for air conditioning. Instead operators can use free cooling, which uses outside air.

Raising the temperature from 25 degrees Celsius to 40 degrees Celsius reduces required energy by up to 30 percent, according to Nokia Siemens Networks.

Another method is to reduce energy consumption during off-peak hours by adapting the energy use of the base station according to the level of calls, just like a laptop goes into sleep mode when it isn't used. A feature from Ericsson, called Base Transceiver Station Power Savings (BTS Power Savings), does just that and can lower energy use by 15 percent to 25 percent.

A more spectacular way of reducing carbon-dioxide is Ericsson's radio base station site concept Tower Tube, which looks like something from a science-fiction movie, designed to require no active cooling. It is built using concrete instead of steel, which lowers emissions by up to 40 percent.

Nokia Siemens has set a target to reduce energy use of typical GSM (Global System for Mobile Communications) base stations by 20 percent by 2010, from the 2007 level of 800W, and 3G (third-generation) base stations by 40 percent from 500W, during the same period.

In 2008 Ericsson exceeded its target to lower energy use in a 3G base station by 50 percent compared to 2005 levels. Later this year it will introduce future targets.

As the need for power decreases, the use of renewable energy, like solar and wind power, becomes more viable. A base station that needed 200 square meters of solar panels five years ago, today needs 50 square meters, according to Ericsson.

Wind and solar power have advantages and disadvantages. Wind is more efficient, if you find a spot with enough speed and wind occurrence, according to Blau.

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Nortel says it's publishing its LTE patent royalty rates "to provide increased transparency and predictability of IPR costs that could help prevent uncertainties in handset costs from inhibiting the growth of the 4G market" and "to help service providers and their handset vendors develop business plans for launching LTE.'

Last month, seven big-name vendors - Alcatel-Lucent, Ericsson, NEC, NextWave Wireless, Nokia, Nokia Siemens Networks and Sony Ericsson - signed an agreement hoping to achieve similar goals by limiting intellectual property licensing fees for LTE.

The seven-way alliance insists that an aggregate approach would provide more certainty regarding LTE handset development costs.

However, that also potentially means less money for each alliance member as royalties would be split seven ways. In a statement, Nortel said its approach would do more to spur innovation and ensure companies are proportionately rewarded for their contributions to LTE development.

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Nobody has been more surprised at how quickly operators and vendors have moved from WCDMA to HSPA than the GSM industry itself.

According to the GSM Association (GSMA), the number of networks now offering commercial HSPA services jumped 44% between May 2007 and March 2008, with 166 networks now available in more than 73 countries around the world. There are now more than 467 HSPA-enabled devices available, including mobile handsets, notebook PCs, data cards, wireless routers and USB modems. As of March 2008, there are now more than 32 million HSPA connections worldwide. Even die-hard Star Trek fans would be compelled to describe this level of activity as positively warp-speed compared with the snail's pace at which these same operators roll-out their first generation 3G networks.

With this level of support for HSPA technology and the momentum now behind deployments worldwide, some are beginning to question how the industry's current love affair with the standard will affect demand for LTE, the technology which sits the next step along the UMTS evolutionary path. HSPA has a sub-evolutionary path of its own - moving towards HSPA+ which can support data rates of up to 28.8 Mbps - and there are signs that many operators intend to squeeze as much performance from their HSPA networks as they can before eventually biting the bullet and committing to LTE.

To some extent, this attitude is unsurprising. The substantial investment made by operators in UMTS means some are looking at LTE with trepidation and see it as narrowing the window in which to make a return on their 3G investment.

Some operators will look to offset the negative impact of this by adopting strategies to enhance their UMTS networks for many years to come, while deploying LTE for specific user groups or applications. HSPA+, therefore, will be deployed in the 2009 timeframe, and, in Europe in particular, will be the basis of the advanced wide area networks. LTE will remain a technology for selected metrozones and enterprises, with the focus on nomadic and advanced multimedia services, rather than generic mobile Internet usage.

Operators looking to get a head start in implementing LTE can begin by deploying advanced 4G-ready multi-technology base stations today. Once a range of LTE devices become commercially available, upgrading their platforms to support these new standards will be a simple and cost-effective upgrade. This is a strategy being adopted by Vodafone in some of its territories. According to Steve Pusey, Group CTO, networks such as the one being deployed by its Spanish operations should simply require a card upgrade to enable LTE.

Nonetheless, despite operator moves to LTE-ready their network, the overall attitude is that HSPA will be able to comfortably meet the growing demand for data capacity in the immediate future. Barring a step change in consumers' mobile data usage (which cannot be completely discounted), the commercialization of LTE is likely to be pushed beyond the 2009/10 timelines that were originally suggested. ARCchart predicts that the technology is unlikely to see the light of day until 2011 and, even then, subscriber numbers are forecast to be only 4.2 million with a large proportion using LTE via data cards on their laptops

Of course, an alternative operator strategy involves taking a calculated risk that LTE will be available in time to enable a rapid roll-out to compete with HSPA+ technologies and Wimax. In that way, the operator can avoid the costs of rolling out HSPA+ and potentially leapfrog to a higher performance technology, giving it a competitive advantage in the market.

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