Page 47 - ITU Journal Future and evolving technologies Volume 2 (2021), Issue 3 – Internet of Bio-Nano Things for health applications

ITU Journal on Future and Evolving Technologies, Volume 2 (2021), Issue 3

overview of transmitter and receiver nano‑systems has drugs can be delivered to the malignant cell while min‑
been provided in [17]. A survey related to transmitter and imizing the drug delivery to healthy cells. Fig. 3 shows
receiver architectures has been published in [18], where the static nano‑machines bound to the endothelial cells.
some of the modulation, coding, and detection techniques However, the signaling molecules reach the receiver via
have been discussed. In addition to these techniques, a drift and diffusion inside the blood vessel. This case can
Graphene‑based transmitter and bio‑Field Effect Transis‑ be found in the application of blood viscosity monitoring
tor (bio‑FET)‑based receiver have been described to real‑ [9] and other health monitoring applications. In Fig. 4
ize the MC based systems. the nano‑machines and the signaling molecules are mo‑
bile and follow Brownian motion (free diffusion). This
A cooperative drug delivery system was discussed in [19] scenario can arise in the TDD application within the Ex‑
where multiple mobile nano‑machines communicate and
tracellular Fluid (ECF) [25] as the movement of transmit‑
deliver drugs in cooperative manner. More speci ically,
ter/receiver within ECF is governed by free diffusion. Fig.
the leader nano‑machines sense the presence of a tar‑
5 shows that the nano‑machines and signaling molecules
get and release the attractant molecules in the environ‑
are mobile under the in luence of drift and diffusion in‑
ment. The follower nano‑machines subsequently sense
side the blood vessel. Mobile nano‑machines inside the
the attractant molecules and move towards the target
blood vessels can be used for early detection of biomark‑
for releasing drugs. Channel modeling for an MC‑based
ers released by cancer cells in the blood vessels [15]. This
system considering different types of transmitters (e.g., is also a health monitoring application.
point, volume and ion channel based), and receivers (e.g.,
passive, fully absorbing and reactive) has been studied Also, different types of MC systems have been proposed in
in [20]. A survey on biological building blocks for MC the literature in which the simplest case considers a single
has been presented in [21] where the transmitter and transmitter and receiver. An example of a single transmit‑
receiver for different types of signaling particles (i.e., ter and receiver communicating in a low‑based channel
cations, neurotransmitters, and phosphopeptides) have is shown in Fig. 6. A wearable device with a transmitter
been described. This work also discussed the biologi‑ and receiver is implanted over human skin for monitoring
cal approach for Inter‑Symbol Interference (ISI) mitiga‑ the blood viscosity. The transmitter releases molecules
tion. Further, a survey on modulation techniques for through a needle and these molecules pass through the
molecular communication has been presented in [22]. blood vessel. On the other hand, the statistics of the re‑
In [22], the modulation techniques have been classi ied ceived signal are monitored at the receiver since the diffu‑
as concentration‑based, type‑based, release‑time‑based, sion coef icient of the released molecules varies with vis‑
spatial techniques and higher order modulations. More‑ cosity of blood which in turn change the statistics of the
over, the metrics used for evaluating the performance of received signal. This setup can be useful for detecting the
modulation schemes are also presented therein. hyper‑viscosity syndrome [9].

In contrast to these existing survey papers, this survey This simple case is further extended for the Multiple‑
paper comprehensively focuses only on the transmission Input Multiple‑Output (MIMO) scenario to enhance the
and detection techniques present in the existing litera‑ data rate by dividing the bit stream among multiple trans‑
ture under different channel conditions. It is worth not‑ mit antennas. As shown in Fig. 7, these MIMO‑MC sys‑
ing that the modeling of the channel is different for differ‑ tems can also be used for improving the rate of drug de‑
ent applications. Therefore, this paper also classi ies the livery by using multiple transmitters and receivers. Here a
transmission and detection techniques based on the ap‑ transmitter (e.g., controller nano‑machine) can sense the
plications. Broadly we discuss four different scenarios as amount of drug required over the cell surface and sends a
shown in Fig. 1: (i) static nano‑machines communicating signal to the receiver for drug delivery [26]. The receiver
in pure‑diffusive channel without drift or low, (ii) static carrying drug molecules can deliver the drug molecules
nano‑machines under a low‑induced diffusive channel at the cell surface after receiving the signaling molecules
which experiences diffusion as well as drift, (iii) mobile from the transmitter. This process can be faster if more
nano‑machines under a pure‑diffusive channel, and (iv) than one transmitter and receiver are used for drug deliv‑
mobile nano‑machines under the low‑induced diffusive ery. Further, note that in diffusion‑based MC, the range
channel. Further, we discuss the transmission and de‑ of communication is limited due to the loss of molecules
tection for relay‑assisted‑based MC systems, cooperative caused by the random Brownian motion. Therefore, to in‑
or distributed‑detection‑based MC systems, MIMO‑based crease the range of communication, an intermediate relay
MC systems, and machine‑learning‑based MC systems un‑ node is introduced in between the transmitter and the re‑
der all four possible scenarios described above. ceiver.
The irst static transmitter and receiver scenario is shown On the other hand, cooperative or distributed detection
in Fig. 2, where nano‑machines reach the cell surface re‑ is proposed mostly for abnormality detection problems,
ceptor and can communicate over the cell surface. Such where multiple receivers send their individual decision to
a con iguration of nano‑machines is present in the ap‑ a Fusion Center (FC) to make a global decision.
plication of TDD over a cell surface [23], [24]. Here the

© International Telecommunication Union, 2021 35