Full-Duplex Communication: Challenges and Solutions for 5G Mobile Communication

This paper discusses the challenges and solutions for implementing full-duplex communication in 5G mobile networks. It explores the issues related to self-interference cancellation, circuit impairments, and antenna sharing. The paper also highlights the importance of quality components and wideband signal enhancement in the 5G communication system.

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FULL-DUPLEX COMMUNICATION
By (Student’s Name)
Tutor’s Name
University
City
Date

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Introduction
Information is simultaneously transferred in two directions by use of the full-duplex communication
devices. These communication systems are considered as the most suitable solution in achieving spectral
efficiency in improved wireless networks such as the 5G communication system. The rationale is to
enable the maximum utilization of the available temporal and spectral resources during simultaneous
reception and transmission of signals with the application of a single centre of data frequency (Ratasuk et
al., 2015). When the data rates are doubled without the requirement for additional bandwidths, it would be
termed as successful technological attainment. This is very crucial in coming up with a creation in the 5G
era. Therefore, the duplex communication systems have a great impact as it enhances steps to the
necessary enormous increase in the transmission of data. Implementing the full-duplex project for 5G
communication is so tempting. This paper looks at the issues, possibilities, solutions and problems related
to the full-duplex implementation on the mobile communication system.
Issues
Theoretically, in full-duplex communication system, obtaining prominent self-interference cancellation
involve subtracting the transmission signal from the total waveform signal received. This is different to
what occurs in practice. Practically, during reception and propagation, distortion of the SI signals occurs in
either a linear or nonlinear way hence creating difficulty in attenuating the SI signal. Therefore, sufficient
improvements have to be addressed before the full-duplex system is implemented within the 5G mobile
communication (Fettweis & Alamouti, 2014).
Normally, FD systems are inexpensively made thus impairing the circuits. The impairment of these
analogue devices will probably lead to non-linear signal distortions in 5G mobile devices. This major
concern may appear in the 5G mobile devices which may also be made of low-cost RF components that
are produced in volume. Hence, inhibiting FD system’s use in 5G mobile communication. Also, most
communication systems use base station that can apply the modes of full-duplex for communication with
the mobile devices that only use half-duplex systems (Ma et al., 2015).
Challenges
The present technology used in communication system limits the use of full-duplex transceiver for 5G
mobile communication networks. The technology, currently in use, has difficulty in availing separate
space between the transmitting and receiving antennas. It therefore implies that when using the FD
system, the signal transmitter and receiver must share a similar antenna. This brings in need for better
modelling and processing before accurately and succefully cancelling signals when using FD systems for
5G communication. (Zhang et al., 2015).
Problems and Solutions
Distortion is a major challenge when it comes to signal reproduction. The circulator, however, is among
the components that accommodates the use of full-duplex systems in 5G communication devices. The
circulator ensures transmitter and receiver are able use a similar antenna. The antenna is linked with the
transceiver by the circulator. The incoming signals access the circulator via one port while the outgoing
signals use another port depending on the direction in which they are rotating. This principle is used by
each of the circulator ports which ensures that there is a certain isolation quantity between the transceiver
and the receiver in a 5g communication system (Thompson et al., 2014).
Another method of applying the FD system in 5G communication through connecting a duplex electrical
balance. The duplex electrical balance isolates the transmitter and receiver while applying one antenna.
Additionally, for better significant isolation quantities, the hybrid transformer should be used. The duplex
electrical balance is an update to the circulator since it is substantially more compact. This is what makes
duplex electrical balance to be a most preferred future candidate for FD system implementation within the
5G mobile communication (Aijaz et al., 2017).
There are two SI signal’s components that are observed at the receiving path when applying the
architectural circulator in the 5G mobile communication era. Firstly, the attenuated SI, averagely at 20dB,
causes leakages within the circulator. The mismatched impedance during input is among the crucial

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properties caused by the mobile antenna's power reflections. The antenna will only key in data where the
input has been correctly matched. Partial power into the transmission is as a result of reflections
occasioned by mismatches. Thus, very high values in matching are important due to their ability to be
translated directly to less SI quantities. It uncommon to obtain substantial matching values exceeding
20dB even though off-the-shelf antenna might have been applied (Ma et al., 2015).
It is crucial, for the analogue and digital equipment used in the FD system domain, to possess additional
SI attenuators before being implemented in 5G mobile communication. This is due to the existing
reflections caused by the surrounding environment and leakages within the circulator or from the
antennas (Pirinen, 2014). Prior to getting into the receiver chain, the attenuated SI signals must generally
be sufficient to facilitate:
 The low-noise amplifier receivers do not experience higher amounts of power to ensure that the
receiver does not saturate.
 There are higher typical ranges in the ADC to facilitate the capture of SI residual and the other
important signal received even though weak but contains sufficient precision.
The receiver itself will determine whether the factors mentioned above could also be restricting
communication. The passive SI attenuation is generated as a result of isolated circulators and antenna
matchings. The creation of sufficient motivation leads to the cancellation of active RF allowing the SI to be
further suppressed before the exact receiver chain. The component behind the cancellation of active RF
within the mobile full-duplex equipment needs to be capable of efficiently cancelling the wideband (Zhang
et al., 2017). In the 5G era, using an SI analogue multi-trap canceller in an FD system makes it
convenient for the transmission of copied signals. In that the varying delays which act as the reference
signals. Thus, each signal consists of amplitudes and phases that can be easily tuned. Cancellation
circuits are concerned with the reference signal's phases and amplitudes matching. This implies that
when implemented using an FD system, the resultant signal cancellations will be matching with the
composites of SI signal produced by the circulators and the antennas during the summing node before
the receiver chain (Talwar et al., 2014). Hence, making the system applicable in the 5G mobiles.
There are other challenges in regards to full-duplex system implementation in 5G mobile devices to be
addressed includes strong adaption in the RF canceller. The phases and amplitudes controls of the RF
cancellation signal must gain self-adaptability features to enable it to track immediate changes at near
proximities within the antenna. Self–adaptability properties will be successful if the SI cancellations are
properly met during exposure to actual supporting condition. For instance, the FD system’s automation of
the controls is achieved with the use of either the digital or analogue track circuits while the amounts of
power are under supervision at the output canceller. This makes it possible for the cancellation of SI
analogue signal to self-tune, hence, operating appropriately in the 5G era (Wu et al., 2014).
Moreover, the SI cancellation on its own cannot typically be enough for fewer attenuations compared to
noise receiver floor. The last attenuation of the SI must be performed in the digital domain. Constructing
the cancellation signal is possible whereby, it is done by acquiring the original transmitter of data by
filtrating the effective remainder channel of SI only if this process is conducted within the digital domain.
The most crucial importance of the cancellation of the digital SI is that it makes it simple for the addition of
the nonlinear modelling of the SI waveforms. Naturally, the SI channel comprises of the self-tracking
properties through filtration adaptability. Therefore, the adaptive digital nonlinear signals will efficiently
lead to the cancellation and tracking of the SI residual (Boccardi et al., 2013).
Conclusion
This paper has looked at the challenging issues regarding the full-duplex communication system and
outlined how the challenges can be resolved. It is quite important for the 5G mobile’s full duplex systems
to adapt to various changes within the channel environment other than facilitating an antenna sharing
ability for good communication (Fettweis & Alamouti, 2014). The mobile equipment normally rely on their
components that are cost-effective, however, a lot of communication impairments are brought about by
their circuit’s low quality makes. It is therefore important to consider a mobile’s quality because quality
directly affects the potential cancellation of the self-interference properties. Additionally, the FD system

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should posses the capability of enhancing a variety of wideband signals to fit in the 5G communication
system (Eid et al., 2011).

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