Page 125 - 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

Algorithm 1: Operation of the organism.
1 = { _ }
2 ℛ = { _ }
3 ℰ = { _ _ } = {} 1
4 ℛ = { _ } = {}
5 Transmission Probability
6 _ = 0
7 _ = 0
8 _ = 0
9 while _ < and
({ℰ } < × (ℛ)/100) do
10 = random( ) Molecule Number
11 .transmit()
12 _ =
Fig. 2 – Reception behavior depending on molecule count in the vicinity.
13 while .received() == do
2.2.4 Reception
14 ℛ = { | ∈ ℛ
15 and .received() = and Reception occurs when molecules are incident on the
16 ( ∶ ) < ( _ ∶ )} receptors located on the nodes. Considering a binding
mechanism following the standard lock‑and‑key model,
17 _ = random(ℛ ) both the molecular concentration in the vicinity of the re‑
18 _ .transmit() ceptor and the orientation of molecules according to the
19 _ = _ receptor are important. In other words, while a single
molecule with the correct orientation can bind the recep‑
20 if drop then tor, many molecules without the correct orientation may
21 ℛ = {} fail to trigger a reception. Hence, to capture the stochastic
22 _ + + properties of reception, we use the following simple ap‑
23 _ + + proach. If the maximum number of molecules exceeds a
24 break
certain threshold, , the binding probability approaches
25 end
1, so we assume successful transmission. If the number
26 if .received() == then of molecules is below , there is a non‑zero chance of suc‑
27 ℛ = {} cessful binding. This chance is directly proportional to the
28 _ = 0 molecule count in the vicinity. Fig. 2 depicts the reception
29 _ + + behavior. We can summarize reception with (1),
30 break ⎧1, max ≥
31 end { → +Δ
{
32 end {
max = 0
33 end ( ) = ⎨ 0, → +Δ (1)
1
{
{ max
2.2.2 Medium { → +Δ , 0 ≤ max ≤

⎩
→ +Δ
where max is the maximum number of molecules in
The transmission medium is a 3D medium where → +Δ
molecules can diffuse. The medium is isotropic and ho‑ the vicinity of the node and ( ) is probabilities of suc‑
1
mogeneous, i.e., the diffusivity of the molecules does not cessfully receiving the emitted signal.
depend on the position or direction.
2.3 Evolution
2.2.3 Transmission As stated in Section 2.1, the organism dies after it consecu‑
tively drops messages from its sensors. The total number
Each node in the organism is capable of receiving and
of dropped messages during its life cycle measures the or‑
transmitting messages. The nodes transmit the mes‑
ganism’s success.
sage by releasing vesicles containing a ixed number of
molecules. The release is assumed to happen in the center The more successful organisms, which are chosen accord‑
of the node in an omnidirectional manner. ing to the selection process, then produce their offspring,
i.e., the creation. Iterated selection and creation stages
constitute evolution. The evolution procedure is summa‑
rized in Algorithm 2. First, as the generation dies, the

© International Telecommunication Union, 2021 113