We said the 4G era had unofficially begun. There is contention over the meaning of the term. Some take a narrow view, some a broader interpretation. The latter group would say that Xohm, while it may be intriguing in a number of ways and certainly "next-gen," is in fact not a 4G service. According to Phillip Redman, a research vice president at Gartner, Xohm is not 4G because the underlying WiMAX technology it uses, 802.16e, fails to meet minimum objectives for 4G set out by the International Telecommunications Union(ITU), a United Nations agency. "They're the ones that decide what is 3G, what is 4G - what is 10G," Redman says of the ITU. "There is a misconception out there right now that 4G is WiMAX, and that is absolutely not true. There is in fact no definition of 4G yet, but there are goals [the ITU] is working towards." What are those goals? 4G networks will be based on Internet protocol (IP), the standard used for sending data over the Internet and other packet-switching networks.
This means that unlike today's 3G networks, which are circuit-switched with an overlay of data carrying capabilities, 4G networks will be entirely packet switched. Mobile voice will be carried as a stream of IP packets - VoIP in other words.4G networks will deliver data throughput to mobile users as high as 100 megabits per second (Mbps), with, it's hoped, an evolutionary path to gigabit speeds. They will feature a higher level of security than existing wireless technologies provide and better implementation of quality of service (QoS) techniques for ensuring smooth flow of time-sensitive data, such as video and voice. And they will use two key underlying technologies: Orthogonal Frequency-Division Multiple Access (OFDMA), a highly efficient digital radio modulation scheme, and MIMO (multiple input multiple output), a multi-antenna system that minimizes data errors and optimizes speed. Speed Matters
Both these last technologies, it's worth noting, are already used in WiMAX 16e, and in Wi-Fi 11n for that matter. Current networks based on 802.16e, including Xohm's, are also already pure IP networks. "The current WiMAX has good characteristics," Redman concedes. "But realistically, [WiMAX] carriers are saying they're going to support 2 to 4 Mbps [data speeds]. We expect 4G to be ten times that. So today, the actual capabilities of the WiMAX network aren't anywhere close to what we expect from 4G." Maybe true. But many industry observers, and certainly vendors wanting to cash in on the hype value, are referring to today's WiMAX as 4G.
That process is underway. It's expected the ITU will next year choose two standards - just as it chose two competing 3G standards. The principal 4G contenders? A beefed up WiMAX standard - 802.16m - currently being developed by the American-based, but international, Institute of Electrical and Electronics Engineers (IEEE), which also developed 802.16e and Wi-Fi. LTE (Long Term Evolution), being developed by the 3rd Generation Partnership Project (3GPP), the mainly European-based, but international, association of telecom associations that defined Universal Mobile Telecommunications System (UMTS), the current GSM-based 3G mobile standard. Despite the fact that neither standards body has submitted a 4G proposal to the ITU yet, the battle lines among vendors and operators are forming. Choosing Sides
For GSM operators, the logical progression is to LTE and it is expected that virtually all will choose it. Some have already announced they will, including Verizon in the U.S., Vodaphone in the UK and China Telecom. Verizon declined further comment for this article because its development team is too busy "working through LTE strategies for 4G," a spokesperson said. It also didn't want to comment at such an early stage with the market evolving so rapidly. For CDMA carriers, the evolution to either of the likely 4G standards will be a slightly bigger challenge.
They could, like Sprint, jump on the WiMAX bandwagon and operate parallel 802.16e and CDMA-based 3G networks until they can eventually upgrade to a true 4G WiMAX technology. Some smaller carriers have announced they will go this route.Most major CDMA operators, however, at least in North America, are expected to bite the bullet and choose LTE as the lesser of two evils, the one that at least has a similar legacy to their current technology. Some of those, such as Bell Mobility in Canada, will take the interim step of building a GSM-based HSPA (High-speed Packet Access) data network on top of their existing CDMA/EVDO infrastructures. Others will go directly to LTE - when it becomes available. "The market," Redman sums up, "is moving toward LTE over WiMAX. WiMAX will not dominate. LTE is considered a more traditional evolutionary path for existing 3G operators. WiMAX is considered something new, and many don't want to take a risk with it." Another reason for LTE's dominance: while some mobile network equipment suppliers such as Nortel are backing both WiMAX and LTE, the dominant infrastructure supplier, Ericsson, is only backing LTE, Redman points out. Kerravala says, "What we're likely to see is LTE being much more widely deployed in developed markets because of the installed base [of CDMA and GSM infrastructure], but WiMAX prevailing in emerging markets, such as India."
This article was first published on SmartPhoneToday.com.