Advanced technologies for 4G: Mobile broadband multimedia everywhere

[attachment=17250]
Changing the wireless experience
The drive to 4G is being fueled by the promise of target peak data rates of
approximately 1 Gigabit per second
(Gbit/s) for low mobility (such as nomadic/local wireless access) and approximately 100 Megabits per second (Mbit/s) for high mobility (such as vehicular mobility). These data rates are part of the International Telecommunication Union (ITU) long-term vision (2010-2015) for 4G, as outlined in the ITU’s IMT-Advanced requirements.


4G technology challenges
All of these existing players and new entrants have their eyes on opportunities brought on by the transition to 4G, with its unprecedented jump in bandwidth, capacity, and multimedia capability. (The table on page 19 shows a comparison of wireless and wireline performance metrics.) As 4G technologies and standards mature, the industry will take a giant step closer to realizing the long-held vision of a single, converged, packet-based “fat pipe” that will carry all wireless multimedia services with high quality and reliability, will scale easily to accommodate subscriber growth, and will provide users with whatever bandwidth they need, wherever they need it, simply and cost-effectively. Most importantly, 4G promises a “true” broadband experience, where mobile services will be delivered with enough capacity and transparency that users will be unaware of the underlying network.
This next era in the wireless industry is an exciting one from a technology perspective. The capabilities of 4G will not be achieved through a series of incremental improvements in capacity, spectral efficiency, and throughput. Rather, the disruptive shift to a 4G architecture affords the opportunity to rethink and revamp nearly every function in the wireless access network, from the radio and antennas to the point of backhaul and every stop in between. Put simply, this next wireless network will be
designed differently.
Interestingly, there are as many different schools of thought on 4G as there are providers. For some, 4G means high-capacity metro hot spots. For others, 4G is about enabling cheaper voice service, or achieving a better experience when viewing or uploading YouTube clips. Still others are looking to 4G for mobile video, broadband for the extended enterprise or home, or as a digital subscriber line (DSL) replacement.


Support a wide variety of spectrum bands: Spectrum is a key challenge for 4G systems, because of both the differing bandwidth requirements and the spectrum bands available globally. Whereas previous wireless generations – 1G, 2G, and 3G – all globally operate roughly in two major bands [the 800 to 900 Megahertz (MHz) band and the 1.7 Gigahertz (GHz) to 2.1 GHz range allocated for Personal Communications Services (PCS)], new spectrum is spread across several additional bands – specifically, in parts of the 400 to 700 MHz range and in the 2.3, 2.5, 3.5, and 4.4 GHz bands. Unlike previous generations of wireless, 4G systems therefore will not lend themselves to a single product in a globally coordinated frequency band. As a result, 4G products must be deployable in different markets and adjustable to a wide range of different frequency bands.