Bernhard H. Walke, Communication Networks, RWTH Aachen University,
walke@comnets.rwth-aachen.de

"Mobile Broadband Internet Access - What comes next?"

Abstract: 3G mobile services started in 2001 (Japan) and 2003
(Europe) to serve voice and Internet access. The initial mean user
data rate developed from 128 to 356 kbit/s, and was further
increased in 2005 to a few Mbit/s. Two notable examples of 3G
radio interfaces are W-CDMA and cdma2000, both under the umbrella
of IMT-2000 - the 3G mobile systems specified by ITU-R. The 4th
Generation (4G) systems expected to be in operation around the
year 2015 are called IMT-Advanced, currently specified by Working
Party 8 Future (WP8F) of ITU-R. 4G systems will support mobile
services/applications with a peak user data rate of 100Mbit/s for
highly mobile terminals and up to 1Gbit/s for slowly moving
terminals in metropolitan areas. These extremely high data rates
will require much additional frequency spectrum, compared to the
current allocations for IMT-2000 mobile services. In addition, the
coverage range of base stations will reduce substantially, owing
to a higher signal attenuation at carrier frequencies around 3GHz
where IMT-Advanced systems will operate. We will discuss the
method for estimating the spectrum required for IMT-Advanced
systems as applied by ITU-R World Radio Conference WRC-07 and the
allocations made. Trends in mobile broadband communication will be
addressed based on 1. applications and services, 2. radio
interface technologies, and 3. standardisation. The capabilities
of future mobile and wireless systems will be discussed in terms
of degree of mobility support, spectral efficiency, interworking,
the roadmap of its introduction and the philosophies of the IT and
Telecommunications communities competing for operation of future
broadband systems and the current and future developments of
wireless systems developed by IEEE Project 802 will also be
considered. Common features of IMT-Advanced candidate systems will
be addressed and the architecture of multi-hop cellular networks
(MCN) based on fixed layer-2 relay nodes (RNs) as developed by the
WINNER project will be presented that is more spectral and cost
efficient in any scenario studied in WINNER than single-hop
cellular: wide area, urban, metropolitan and short-range indoors.
RNs are expected to appear in the forthcoming LTE releases. Since
all forthcoming mobile broadband systems like 3GPP LTE, WiMAX, UMB
will be based on OFDMA transmission, the WINNER results apply to
all of them, accordingly, project IEEE 802 has specified layer-2
relays in both Amendments to 802.11s Mesh and to 802.16j Mobile
Multihop Relay (Draft 2007). Higher spectral efficiency of MCN
compared to SCN can only be realized when applying intelligent RNs
positioning and dynamic radio resource partitioning strategies.
Therefore, radio resource management algorithms whose complexity
will scale well with the resultant network capacity will be
introduced as one of the most motivating further research domains.