Posts Tagged ‘Wireless’

Fourth Generation (4G) Technologies

Thursday, January 6th, 2011

ATETV adviser Gordon Snyder oversees the Telecommunications Technology program at Springfield Technical Community College, which concentrates on the numerous technologies that deliver information — in the form of voice, data, video or a combination of these.

Today, federal deregulation, growing security requirements, and rapidly changing developments in the areas of fiber optics, ATM, DSL, LAN/WAN technology, Cisco networking, and wireless technology, have all helped to make telecommunications and network technicians highly sought after in the marketplace.

In this week’s blog, Gordon brings us up to speed on some of the latest developments in wireless technology.

I’d like to thank the folks at ATE TV this week for the re-airing of episode #34 to coincide with our Winter 2011 ICT Educator Conference and for allowing me to post here on the ATETV blog. The episode covers why internships are important to employers and employees, the future of Information and Communication Technologies, and Biotechnology career options.

These days, most of us are carrying some sort of mobile device with the expectation of continuous connectivity and availability. With all of the advertising we’re seeing lately from providers like Verizon Wireless, AT&T Wireless and Sprint I thought it would be interesting to write a little bit about 4G wireless technologies.

4G is short for fourth generation and is a successor to third generation (3G) wireless technologies. 4G includes both LTE (Long Term Evolution) and WiMAX (Worldwide Interoperability for Microwave Access), and sets peak mobile download speeds of 100 Megabits per second (Mbps) and 1 Gigabit per second (Gbps) for fixed services. An example of a fixed service would be an antenna used for wireless access on top of your house.

You may be wondering – if both are considered 4G technologies and both offer the same bandwidths, what’s the differences between LTE technology used by providers like Verizon and AT&T and WiMAX used by other companies like Sprint? Is one technology better than the other? Why would one company decide on LTE while another decides on WiMAX to deliver next generation services? If they are very similar – what makes them different?

Here’s some quick answers taken from a few of my recent blog posts:

LTE is the 4G technology of choice of the larger mobile carriers like Verizon Wireless (launched LTE last month) and AT&T Wireless (scheduled to start LTE rollout this year). These carriers already have LTE spectrum and the money to buy more spectrum. They will also tell you that LTE more easily supports backward compatibility with earlier cellular technologies. LTE uses Frequency Division Duplex (FDD) spectrum.

WiMAX is the choice of carriers with Time Division Duplex (TDD) spectrum (launched by Sprint in 2008) and also makes sense for for green-field situations where backward compatibility is not needed.

So, LTE uses FDD spectrum and WiMAX uses TDD spectrum – what’s the difference? Here’s a quick explanation from three-g.net:

Frequency Division Duplex (FDD) and Time Division Duplex (TDD) are the two most prevalent duplexing schemes used in broadband wireless networks. TDD is the more efficient scheme, however, since it does not waste bandwidth. FDD, which historically has been used in voice-only applications, supports two-way radio communication by using two distinct radio channels. Alternatively, TDD uses a single frequency to transmit signals in both the downstream and upstream directions.

Basically, FDD (LTE) uses two channels and TDD (WiMAX) uses one channel for two-way communications.

Which technology will dominate? It looks like LTE in the United States but….. there are already issues with expensive and crowded spectrum. There’s also a lot more TDD spectrum available than FDD spectrum and TDD spectrum is cheaper.

Now, if LTE is preferred by the larger carriers in the United States and spectrum is in short supply, wouldn’t it make sense to try and develop a version of LTE that could use TDD spectrum? That’s what an emerging technology called TD-LTE does – it uses TDD spectrum for LTE transmission. Does it work? It sure looks like it. Last July, Ericsson and China Mobile demonstrated an end-to-end TD-LTE solution that achieved a single user peak downlink rate of 110Mbps and on Friday (December 31, 2010) China Mobile announced it had finally received approval from regulators and will start large-scale testing of domestically developed TD-LTE technology. This is going to be really interesting to watch!

Want to find out more? Watch (and search) places like ATETV.org and Gordon’s Information and Communications Technologies (ICT) Blog (my blog!) for more on emerging information and communications technologies like 4G along with the different kinds of great technical career opportunities community colleges can provide.