Roundtable: Defining 4G

As LTE and WiMAX continue to deploy commercially, and certain carriers (paging T-Mobile USA) are claiming the 4G tag for their HSPA+ networks, there's been a bit of a scramble over what 4G really means, how mobile operators can leverage it for new business models and whether it's truly a game-changer for the industry.

In search of answers, B/OSS conducted a roundtable on this and more with Todd Rowley, vice president of 4G, Sprint; Chris Kissel, industry analyst, Mobile Internet Group, In-Stat; Philip Solis, research director, Mobile Networks, ABI Research; and Dan Warren, senior director of technology, GSMA.

Does 4G exist today? How do you define 4G and how is it different from 3G? 

Kissel: In-Stat (and I personally) are very uncomfortable with the way that mobile operators are presenting their technologies. Not one mobile operator has a 4G technology and not one mobile operator is remotely close. 4G is formerly mobile broadband technologies expected to fulfill the requirements of the ITU’s IMT-Advanced standard.

Rowley: The technology that Sprint and Clearwire are using to deploy 4G today — WiMAX — is the first wireless network designed specifically to carry wireless data and has been adopted by more than 500 companies around the world. WiMAX has recently been recognized as a 4G technology by the International Telecommunications Union and, more importantly, is clearly at a performance level that cannot be achieved by present 3G technologies. This is why we call it 4G.

Solis: Yes, 4G exists today. 4G is not a standard or specification, nor is it something defined by specific and arbitrary requirements. 4G is a short way of saying fourth generation mobile wireless technologies. A generation typically comprises a group of standards that all use a common fundamental technology. 1G was the first set of technologies, all analog, all used frequency division to split up spectrum into pairs. With 2G, time division was added to frequency division to put multiple users on each pair of frequencies. Just like in the wired telecom world, the use of time division means that the communications are now digital. With 3G, code division was used on top of either frequency division or both frequency and time division. CDMA is the core technology common to all 3G technologies. With 4G, OFDMA is the core technology and is used on larger channels to make more efficient use of the spectrum, achieve a lower cost per megabit, and reach faster speeds with lower latency. Lower latency is also achieved by using an all-IP network.

Warren: 4G exists in the minds of some and not in the minds of others. Taking the ITU-R argument, 4G technologies are defined (LTE Advanced and WiMAX 2) but neither is currently implemented in commercial networks. However, because of a broad marketing push, the term 4G has existed for some time. Interestingly, where some operators label HSPA+ as 4G, others do not.  Most operators with live LTE or WiMAX services do label them as 4G however.