Vision for Beyond 4G Broadband Radio Systems



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INTRODUCTION

Mobile communication experienced a tremendous success,
ever increasing availability and performance of mobile
services, starting with voice but recently expanding into
various data services. This trend is expected to accelerate due
to increasing popularity of smart phones, super phones and
tablets with powerful applications and multimedia capabilities
up to pervasive 3D multimedia and other applications allowing
a completely new mobile experience. While the number of
subscribers may eventually saturate, proliferation of mobile
broadband into billions of machine devices and consequent
machine to machine (M2M) applications will add to the
exponential increase in traffic volume and transactions.


TECHNOLOGY COMPONENTS

In order to achieve the requirements for the next decades as
set out in the previous section, several key enablers which are
introduced in the following sections will need to be
investigated and eventually incorporated into the B4G system.


Interference mitigation

Since the beginning of mobile radio communications, intercell
interference is one of the main issues to be solved. Some
good progress has been made in the meantime, starting from
large frequency reuse factors for 2G, frequency reuse one for
3G and some form of interference aware scheduling (inter cell
interference coordination: ICIC) and interference-aware
transceiver techniques such as interference rejection combining
(IRC) for 4G. Within the 3GPP LTE Release 11 coordinated
multi point (CoMP) study item, more powerful means like joint
precoding over several cells are being investigated. Still, for the
time being, performance is significantly limited by inter cell
interference. Note that in theory effective cooperative
transmission and detection schemes will even partly benefit
from interference by exploiting spatial multiplexing,
interference cancellation, array, and diversity gains [4].


TOWARDS REACHING B4G SYSTEM PERFORMANCE

The well known ways to increase peak data rate are to
provide more RF bandwidth, more MIMO branches and usage
of higher modulation order. In addition, reduction of overhead
through scalable air interface design helps in increasing both
peak and average data rates.


CONCLUSION
Radio access technologies will utilize significant
advancements allowing to meet the predicted requirements in
2020 of 1000 fold capacity increase under flattish revenues,
and consequently flattish costs. The technology mix will
combine a much more versatile radio numerology, a large
number of heterogeneous base stations, some of them tightly
co-operating using centralized architectures, others being
deployed in a distributed manner, a massive use of advanced
antenna technologies, self organizing networks enhanced with
cognitive elements, true wideband RF radios and extensive use
of available fiber optics networks for the back- & fronthauling.
In the long run, when we reach the point where the
spectral efficiency per access point may not be further
improved at reasonable effort, we may also consider novel
spectrum usage concepts, a re-definition of cell concepts or
entirely re-designed air interfaces. We will have to drive research
and development of the most economical and powerful
technologies and solutions within industry and academia.