Analysis of 5G Wireless Systems in FR1 and FR2
Frequency Bands
Dr. Ravilla Dilli
Electronics and Communication Engineering
Manipal Institute of Technology
Manipal, Karnataka, India
dilli.ravilla@manipal.edu
Abstract— According to 3GPP, the frequency bands of 5G
technologies are occupied at various parts of the frequency
spectrum. E.g. mmWave frequencies are used for short-range
communications in 5G mobile communications which can provide
much higher bandwidth, supports greater data rates and also
overcome the effect of path loss using carrier aggregation feature.
However, the frequency bands for 5G wireless technology are
classified into FR1 and FR2 frequency ranges. FR1 (4.1 GHz to
7.125 GHz) band of frequencies are used for carrying most of the
traditional cellular mobile communications traffic, while the FR2
(24.25 GHz to 52.6 GHz) band of frequencies are focused on short-
range, high data rate capabilities.
A frequency selective wireless
channel is converted into a parallel collection of frequency flat
sub-channels using “Orthogonal Frequency Division Multiplexing
(OFDM)” techniques that improve multipath fading issues and
bandwidth efficiency, also reduces the inter-sub carrier
interference. The recent wireless communication standards like
802.11x families combine the techniques of multiple-input-
multiple-output (MIMO) and OFDM to provide improved data
rates. As MIMO uses an array of antennas, and it is possible to
achieve a higher signal-to-noise ratio (SNR) using “beamforming”
which in turn reduces the bit error rate (BER). This research
paper is focused on the performance of hybrid beamforming for
single user and multi-user “massive MIMO-OFDM systems” and
facilitate to explore various system-level configurations for
different channel modellings in FR1 and FR2 bands.
Keywords—5G, mmWave communication, massive MIMO,
hybrid beamforming, OFDM.
I. INTRODUCTION
Modern wireless communication systems are using “Spatial
multiplexing” to enhance the throughput of transmitting data
within the wireless system in severe scattered channel
conditions. To transmit multiple data streams through the
wireless channel, a channel matrix is used to derive a set of
precoding and combining weights both magnitude and phase
terms. At the receiver (Rx), each data stream is recovered
independently. 5G wireless systems have an advantage of
higher bandwidth at “millimeter wave” (mmWave) frequency.
Also, 5G wireless systems minimize severe propagation loss in
the mmWave band by deploying large scale of antenna arrays
at the cost of unique technical challenges.
5G NR defines the cyclic prefix lengths for all subcarrier
spacings in such a way that OFDM symbols align regularly,
irrespective of the subcarrier spacing. A carrier and bandwidth
part in 5G is characterized by a subcarrier spacing, several
resource blocks, and a starting resource. For the given
bandwidth, the number of resource blocks is less at higher
subcarrier spacings and vice versa. A bandwidth part is
associated with the carrier that has the same subcarrier
spacing, but there are several bandwidth parts with the same
carrier spacing. Bandwidth parts can be seen as a way to
address the available spectrum to a UE. Bandwidth parts
address the issues like when UEs may not be able to receive
the full bandwidth, even when UE is capable of receiving a
large bandwidth, it will save power if it can be addressed with
smaller bandwidth. Situations when UEs doesn’t want high
data rates then. One UE can be associated with up to four
bandwidth parts, however, one UE can only have a single
bandwidth part active at a time. These bandwidth parts are
preconfigured, and the UE can be instructed to switch between
these different parts over time. The resource element in 5G
NR is the smallest time by frequency unit, which is one
subcarrier by one OFDM symbol. A resource block is defined
as a group of 12 subcarriers with no associated time duration.
Beamforming is a method of concentrating radio frequency
(RF) energy in a particular direction and this technology
allows Access Point (AP) to see where the signal is getting
dropped and adjust accordingly. MIMO wireless systems are
increasingly being used in recent communication systems for
higher gains in capacity by realizing them using multiple
antennas that use spatial dimension apart from time and
frequency dimensions, without varying bandwidth of the
wireless system. Table I shows the various possible operating
frequencies in FR1 of 5G NR [11] [12].
As the carrier frequencies in 5G can be as high as 60 or 70
GHz, (whereas in LTE carrier frequencies are < 6GHz) there
has been significant consequences on the design of the
physical layer, as beamforming becomes required to support
those higher frequencies. At those higher frequencies, more
spectrum is available, and 5G NR is set to take advantage of
this spectrum with up to 400 MHz of bandwidth. At higher
carrier frequencies, signals need to be beamformed to
overcome propagation losses. As a result, it is both difficult
and not useful to provide cell-wide reference signals. The
signal strength would be too low and each channel is
beamformed which means that the UE would need to be
Proceedings of the Second International Conference on Innovative Mechanisms for Industry Applications (ICIMIA 2020)
IEEE Xplore Part Number: CFP20K58-ART; ISBN: 978-1-7281-4167-1
978-1-7281-4167-1/20/$31.00 ©2020 IEEE 767
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