With much advancement in the field of nanotechnology, bioengineering and
synthetic biology over the past decade, microscales and nanoscales devices are
becoming a reality. Yet the problem of engineering a reliable communication
system between tiny devices is still an open problem. At the same time, despite
the prevalence of radio communication, there are still areas where traditional
electromagnetic waves find it difficult or expensive to reach. Points of
interest in industry, cities, and medical applications often lie in embedded
and entrenched areas, accessible only by ventricles at scales too small for
conventional radio waves and microwaves, or they are located in such a way that
directional high frequency systems are ineffective. Inspired by nature, one
solution to these problems is molecular communication (MC), where chemical
signals are used to transfer information. Although biologists have studied MC
for decades, it has only been researched for roughly 10 year from a
communication engineering lens. Significant number of papers have been
published to date, but owing to the need for interdisciplinary work, much of
the results are preliminary. In this paper, the recent advancements in the
field of MC engineering are highlighted. First, the biological, chemical, and
physical processes used by an MC system are discussed. This includes different
components of the MC transmitter and receiver, as well as the propagation and
transport mechanisms. Then, a comprehensive survey of some of the recent works
on MC through a communication engineering lens is provided. The paper ends with
a technology readiness analysis of MC and future research directions.Comment: Accepted for publication in IEEE Communications Surveys & Tutorial
One of the key enablers of future wireless communications is constituted by massive multiple-input multiple-output (MIMO) systems, which can improve the spectral efficiency by orders of magnitude. However, in existing massive MIMO systems, conventional phased arrays are used for beamforming, which result in excessive power consumption and hardware cost. Recently, reconfigurable intelligent surface (RIS) has been considered as one of the revolutionary technologies to enable energy-efficient and smart wireless communications, which is a two-dimensional structure with a large number of passive elements. In this paper, we propose and develop a new type of high-gain yet low-cost RIS having 256 elements. The proposed RIS combines the functions of phase shift and radiation together on an electromagnetic surface, where positive intrinsicnegative (PIN) diodes are used to realize 2-bit phase shifting for beamforming. Based on this radical design, the world's first wireless communication prototype using RIS having 256 2-bit elements is designed and developed. Specifically, the prototype conceived consists of modular hardware and flexible software, including the hosts for parameter setting and data exchange, the universal software radio peripherals (USRPs) for baseband and radio frequency (RF) signal processing, as well as the RIS for signal transmission and reception. Our performance evaluation confirms the feasibility and efficiency of RISs in future wireless communications. More particularly, it is shown that a 21.7 dBi antenna gain can be obtained by the proposed RIS at 2.3 GHz, while at the millimeter wave (mmWave) frequency, i.e., 28.5 GHz, a 19.1 dBi antenna gain can be achieved. Furthermore, the over-the-air (OTA) test results show that the RIS-based wireless communication prototype developed is capable of significantly reducing the power consumption.
In diffusion-based molecular communication, information transport is governed
by diffusion through a fluid medium. The achievable data rates for these
channels are very low compared to the radio-based communication system, since
diffusion can be a slow process. To improve the data rate, a novel
multiple-input multiple-output (MIMO) design for molecular communication is
proposed that utilizes multiple molecular emitters at the transmitter and
multiple molecular detectors at the receiver (in RF communication these all
correspond to antennas). Using particle-based simulators, the channel's impulse
response is obtained and mathematically modeled. These models are then used to
determine inter-link interference (ILI) and inter-symbol interference (ISI). It
is assumed that when the receiver has incomplete information regarding the
system and the channel state, low complexity symbol detection methods are
preferred since the receiver is small and simple. Thus four detection
algorithms are proposed---adaptive thresholding, practical zero forcing with
channel models excluding/including the ILI and ISI, and Genie-aided zero
forcing. The proposed algorithms are evaluated extensively using numerical and
analytical evaluations
In this paper, we propose three novel modulation techniques, i.e., concentration-based, molecular-type-based, and molecular-ratio-based, using isomers as messenger molecules for nano communication networks via diffusion. To evaluate achievable rate performance, we compare the proposed techniques with conventional insulin based concepts under practical scenarios. Analytical and numerical results confirm that the proposed modulation techniques using isomers achieve higher data transmission rate performance (max 7.5 dB signal-to-noise ratio gain) than the insulin based concepts. We also investigate the tradeoff between messenger sizes and modulation orders and provide guidelines for selecting from among several possible candidates.
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