IEEE Communications Magazine - June 2017 - page 64

IEEE Communications Magazine • June 2017
he fifth generation (5G) of mobile networks will sup-
port a wide range of frequency bands, features, and
use cases, with native support for efficient operation.
5G is considered as a significant disruptor to traditional
mobile networks. Some of the main motivations behind the
design, standardization, and deployment of the new gen-
eration of mobile networks include: significant increase of
the supported data rates for enhanced mobile broadband
(eMBB), support for ultra-reliable and low-latency commu-
nications (URLLC), and support for massive machine type
communications (mMTC). The combination of these 5G
pillars can further enable new use cases, such as virtual or
augmented reality (VR/AR), enabled by combining eMBB
and URLLC. The 5G system design will have the flexibility to
adapt to various network operations and network operator
requirements. The flexible system design, combined with the
support for a wide range of frequency bands (from below 6
GHz to millimeter-wave [mmWave] bands), requires novel
resource management schemes, which are the focus of the
articles presented in this Feature Topic.
On this basis, the aim of this Feature Topic has been to
collect novel and innovative enhancements currently being
proposed by the academic and industrial research commu-
nities, and to provide readers with a comprehensive over-
view of the topic. Through the seven articles published in
this Feature Topic, readers gain further insight into the lat-
est enhancements in radio resource management (RRM),
for example, as proposed in the Third Generation Partner-
ship Project (3GPP), related to 5G or New Radio (NR). The
articles also provide an overview of the key technical RRM
enablers required to support deployments in higher frequen-
cy bands, where novel system design enhancements are
required to ensure basic connectivity. The impact of support-
ing URLLC use cases on RRM and the challenges introduced
by the adaptation of novel software-defined network para-
digms are also discussed.
The Feature Topic begins with the article “5G New Radio:
Waveform, Frame Structure, Multiple Access, and Initial
Access” by Lien
et al.
, which provides a detailed overview of
the currently ongoing standardization activities in 3GPP. The
focus of the work is on deployment scenarios, air interface
numerology, frame structure, waveforms, and multiple access
procedures with detailed evaluations on the performance
gains in terms of random access latency reductions using
an enhanced carrier aggregation mechanism in 5G/NR. The
next article, by She
et al.
, “Radio Resource Management for
Ultra-Reliable and Low-Latency Communications,” address-
es one of the key use cases currently being considered for
5G from an RRM perspective. The authors highlight the
requirements of URLLC service delivery in terms of end-to-
end delay, packet loss, and network availability, and outline
design aspects to fulfill these requirements. Further, open
RRM problems, which can motivate new research directions,
are identified for URLLC. With the help of an illustrative case
study and evaluations presenting required uplink transmit
power to ensure network availability considering different
resource management policies, the authors provide a solu-
tion for designing RRM for URLLC.
In the article “Fast-RAT Scheduling in a 5G Multi-RAT Sce-
nario” by Monteiro
et al.
, the authors present a novel connec-
tivity approach that allows a device to be connected to the
control plane of multiple radio access technologies (RATs),
such as NR and LTE, while being able to switch between the
user planes of the different RATs. This connectivity approach
increases the degrees of freedom available to the scheduler,
which in turn leads to a significant increase in the device
throughput and overall network performance. This work
illustrates the great performance gains that can be achieved
by designing new schedulers that build on multi-link connec-
tivity. Li
et al.
, in the article “Radio Resource Management
Aspects for 5G Millimeter Wave Radio Access Networks,”
present a detailed RRM framework for 5G millimeter-wave
key design aspects such as available spectrum, standalone
and joint centimeter-wave operation, backhauling, and the
full dimensionality of the hardware and software network
resources. The results show that by jointly considering these
key aspects, the network throughput can be increased by
almost one order of magnitude.
Within the framework of the ultra-densification of 5G net-
works, device-to-device (D2D) relaying can be an import-
ant technical enabler. This aspect is dealt by Deng
et al.
, in
the article “Resource Allocation and Interference Manage-
5G N
Anass Benjebbour
Ömer Bulakci
Klaus I. Pedersen
Nuno K. Pratas
Marco Mezzavilla
Athul Prasad
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