Image Processing Reference
In-Depth Information
8.1 End-to-End Energy Saving and QoS Control
Requirements
Energy efficiency is essential for sustainable development of the Information and
Communications Technology (ICT), ensuring the profitability of the operators by
reducing the Operational Expenditure (OPEX) and prolonging the battery lifetime
of mobile User Equipments (UEs). The ICT sector, including wireless and wired
networks, is responsible for approximately 2 % of global greenhouse gas emission,
which is equivalent to the contribution of the aviation industry [
1
]. This contribu-
tion will increase even rapidly over the coming years with ubiquitous provisioning
of ultra-broadband mobile Internet and the explosion of the mobile traffic. In fact,
ICT has become an integral part of our lives, playing a key role in modern economy,
from e-businesses, teleworking and transportation to health, security and safety.
According to Cisco forecast, the global IP traffic has increased fivefold over the past
5 years and will increase threefold over the next 5 years, while video communica-
tion will continue to be in the range of 80-90 % of total IP traffic [
2
]. It is also worth
mentioning that mobile traffic almost doubles every year [
3
]. Hence, if no action is
taken, the carbon footprint of the ICT industry is projected to double by 2020 [
4
].
Therefore, pursuing green communication solutions to reduce the energy cost for
transferring one unit of information (i.e., Joule/bit) is of paramount importance to
reduce the carbon footprint of not only the ICT sector itself, but also the correlated
sectors, such as transportation and safety. As the OPEX is reduced, operators can
keep offering affordable services despite the 10-100 times data rate improvement
expected by 2020. However, these requirements are very challenging due to the
unpredictability of network behaviour as the traditional networking design
approaches have shown serious limitations to meet the expectations. Moreover,
an effective support for energy efficiency in a network must be end-to-end driven
and Quality of Service (QoS)-aware; that is, from the access network to the core
network while guaranteeing acceptable QoS delivery to the network users.
From access network standpoint, pursuing energy efficient communication tech-
niques is important for its impact on the battery lifetime of mobile UEs constrained
by limited battery. The evolution of the battery capacity for mobile UEs is slow,
comparing to the Moore
s law, while the traffic generated and consumed by mobile
users is growing exponentially. This creates a growing gap between the energy
consumption of the UEs and the energy available in the batteries. In fact, unless
proper action is taken, there is a threat that mobile users will likely be searching for
power outlets than a network access, and once again they will be trapped into a
single location—the proximity of power outlets [
5
]. Hence, energy efficiency has
become a key requirement for designing the fifth Generation cellular system (5G),
expected to be commercialized by 2020. In fact, for 5G, we need 1,000 times
improvement in the energy efficiency of the Radio Access Network (RAN) as well
as ten times improvement in the battery lifetime of the UEs [
6
]. To achieve these
energy efficiency requirements, cooperative communications approach is promis-
ing. Mobile UEs can adopt cooperative relaying strategy exploiting their spatial
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