As much larger than the number of

As
considering the current trends and the need for improvement of the bandwidth
and the required speed , it push our network into a more faster and new
generation termed as the fifth generation, advanced concepts like massive MIMO
and milli meter wave design have a significant role in the conceptual
architecture design of the fifth generation

MASSIVE MIMO :

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Normally
and conventional cellular architecture uses the outdoor BS in the middle of the
cell communicating with the mobile users, no matter whether they
stay indoors or outdoors. For indoor users communicating with the outdoor BS,
the signals suffer from high penetration loss, which significantly decrease
data rate, spectral and energy efficiency of wireless transmissions. One of the
key

concepts
of designing the 5G cellular architecture is to separate outdoor and indoor
scenarios so that propagation loss can somehow be avoided. This will be
assisted by distributed antenna system (DAS) and massive (large-scale)
multiple-input

multiple-output
(MIMO) technology. Massive MIMO is a form of multiuser MIMO in which the number
of antennas at the BS is much larger than

the
number of devices per signaling resource. This concept allow for orders of
magnitude improvement in spectral and energy efficiency using relatively

simple
(linear) processing. Massive MIMO relies on phase-coherent but

computationally
very simple processing of signals from all the antennas at the BS. Some
specific benefits of a massive MIMO system are identified in as follows:

? It can increase the capacity 10 times or more and
simultaneously improve the radiated  energy
efficiency on the order of 100 times.

The
capacity increase results from the aggressive spatial multiplexing. The fundamental
principle that makes the significant increase in energy efficiency

possible
is that with a large number of antennas, energy can be focused with extreme sharpness
into small regions.

? It can be built with inexpensive, low-power components,
i.e., instead of expensive ultralinear amplifiers, hundreds of low-cost amplifiers
with output power in the milli- Watt range can be implemented.

? This system enables significant reduction of latency
on the radio interface using the low of large numbers and beamforming in order
to avoid fading dips.

? Multiple access layer is simplified, because each
subcarrier will have substantially the same channel gain. In that way, each
terminal

can
be given the whole bandwidth, which renders most of the physical layer control signaling
redundant.

? System is much more resistant against both unintended
interference and intentional jamming by offering many excess degrees of freedom
that can be used to cancel harmful signals.

MILLIMETER WAVE TECHNOLOGY :

Almost
all mobile communication systems today use sub-3 GHz spectrum. However, as the
mobile traffic demands grow, this band is becoming increasingly crowded, while
vast amount of spectrum in the 3–300 GHz range remains underutilized. A logical
way of increasing the throughput will be through bandwidth expansion.

Millimeter-wave
(mmWave) communication systems that can achieve multigigabit data rates at a distance
of up to a few kilometers already exist for

point-to-point
communication. However, the component used in these systems (e.g., power amplifiers,
low noise amplifiers, antennas, etc.) are bulky and consume too much energy to
be applicable in mobile communication. The

availability
of the 60 GHz band as unlicensed spectrum has spurred interest in multigigabit
shortrange communication for wireless personal area

networks
(WPANs) and wireless local area networks (WLANs). After deep

analysis
of propagation characteristics, it was concluded that mmWave technology can
potentially provide the bandwidth required for mobile broadband applications
for the next few decades and beyond mmWave frequencies of 28 GHz and 38 GHz are
extensively studied to understand their propagation characteristics in
different environments, paving the way for their use in 5G systems. Two
principal features of mmWave technology are identified as large amounts of  bandwidth, enabling very high incoverage throughput,
and very small wavelengths enabling a large number of antennas .

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