<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Algorithms for reliable permutation transmission protocols in noisy communication channels⋆</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Emil Faure</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
          <xref ref-type="aff" rid="aff5">5</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Alimzhan Baikenov</string-name>
          <email>a.baikenov@aues.kz</email>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Artem Skutskyi</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Denys Faure</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff4">4</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Olga Abramkina</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff3">3</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Almaty University of Power Engineering and Telecommunications named after Gumarbek Daukeyev</institution>
          ,
          <addr-line>126 Baitursynov str., 050013 Almaty</addr-line>
          ,
          <country country="KZ">Kazakhstan</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>CPITS-II 2024: Workshop on Cybersecurity Providing in Information and Telecommunication Systems II</institution>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Cherkasy State Technological University</institution>
          ,
          <addr-line>460 Shevchenko ave., 18006 Cherkasy</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff3">
          <label>3</label>
          <institution>International University of Information Technology</institution>
          ,
          <addr-line>34A Manasa, 050040 Almaty</addr-line>
          ,
          <country country="KZ">Kazakhstan</country>
        </aff>
        <aff id="aff4">
          <label>4</label>
          <institution>Odesа Polytechnic National University</institution>
          ,
          <addr-line>1 Shevchenko ave., 65044 Odesa</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff5">
          <label>5</label>
          <institution>State Scientific and Research Institute of Cybersecurity Technologies and Information Protection</institution>
          ,
          <addr-line>3 M. Zaliznyaka str., 03142 Kyiv</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
      </contrib-group>
      <fpage>40</fpage>
      <lpage>49</lpage>
      <abstract>
        <p>The existing approaches to frame synchronization of non-separable factorial code, as well as the reliable transmission of its codewords, form the basis for creating a protocol for reliable permutation transmission in conditions of intense channel noise and, accordingly, of a high probability of bit error. This study considers a simplex data transmission system. For such a system, algorithms for frame synchronization of permutations, as well as reliable transmission of permutations have been developed, providing processing of fragments of bit sequences with a permutation length of M. A key feature of the proposed approaches is that they are designed for situations where the initial moment of the transmitter's syncword transmission is unknown. It has been shown that to ensure the required level of false synchronization, the number of K blocks, each consisting of l fragments, needs to be increased. An assessment of the probabilistic indicators of the process of transmission and reception of information has been performed. Computer simulation modeling has been carried out, confirming the theoretical results.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;permutation</kwd>
        <kwd>synchronization</kwd>
        <kwd>error correction</kwd>
        <kwd>security</kwd>
        <kwd>reliability</kwd>
        <kwd>factorial coding</kwd>
        <kwd>protocol</kwd>
        <kwd>data processing algorithm 1</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <sec id="sec-1-1">
        <title>The theory of non-separable factorial data coding [1, 2]</title>
        <p>
          allows using permutations as a transport mechanism in
communication systems with short packets [
          <xref ref-type="bibr" rid="ref4 ref5">3–5</xref>
          ], and also
to implement joint protection of transmitted data from
communication channel errors and unauthorized access [
          <xref ref-type="bibr" rid="ref6">6</xref>
          ].
        </p>
      </sec>
      <sec id="sec-1-2">
        <title>Paper [1] shows that the codewords of a non-separable</title>
        <p>factorial code belong to a subset of the set of permutations
  of length M . The permutation elements are encoded
by a fixed-length binary code with a codeword length
lr  log2 M  . Then the syncword length is equal to
n  lr  M .</p>
      </sec>
      <sec id="sec-1-3">
        <title>Due to the redundancy of the information carriers, permutations, used, and non-separable factorial codes allow detecting and correcting communication channel errors [7– 10]. In addition, the permutation structure creates</title>
        <p>conditions for the code frame synchronization using the
operating signal.</p>
      </sec>
      <sec id="sec-1-4">
        <title>At the same time, modern conditions dictate the need [3,</title>
        <p>
          11–14] to achieve high-reliability indicators in difficult
signal propagation conditions [
          <xref ref-type="bibr" rid="ref15 ref16 ref17 ref18">15–18</xref>
          ]. Three-pass
cryptographic protocols [
          <xref ref-type="bibr" rid="ref19 ref20 ref21 ref22">19–22</xref>
          ], in particular, based on
permutations [
          <xref ref-type="bibr" rid="ref23">23</xref>
          ], deserve special attention in this context.
        </p>
      </sec>
      <sec id="sec-1-5">
        <title>Previously conducted studies on the possibility of using non-separable factorial coding in conditions of a high probability of bit error in a communication channel made it possible to develop:</title>
        <p>
</p>
      </sec>
      <sec id="sec-1-6">
        <title>Methods of frame synchronization for nonseparable factorial codes [24–27].</title>
      </sec>
      <sec id="sec-1-7">
        <title>Method for reliable permutation transmission in</title>
        <p>
          short-packet communication systems [
          <xref ref-type="bibr" rid="ref28">28</xref>
          ].
        </p>
        <p>The developed approaches and methods are effective. At the
same time, the frame synchronization methods are based on
knowledge of the initial moment of the syncword bits
reception, which is not always possible. In addition, the joint
use of synchronization and reliable transmission procedures
in one protocol has not been studied.</p>
        <p>The purpose of this study is to develop algorithms for a
protocol of reliable transmission of permutations for
simplex data transmission systems with non-separable
factorial coding under conditions of high noise intensity in
the communication channel.
2. Sliding window algorithm for a
frame synchronization system</p>
      </sec>
      <sec id="sec-1-8">
        <title>The first step of the protocol involves establishing frame</title>
        <p>
          synchronization for the transmitted permutations. For this
purpose, a frame synchronization method [
          <xref ref-type="bibr" rid="ref25 ref26">25, 26</xref>
          ] will be
used. This method employs as a syncword a permutation with
the maximum value of the minimum Hamming distance from
its binary representation to all its circular shifts.
        </p>
      </sec>
      <sec id="sec-1-9">
        <title>The receiver accumulates K blocks of l fragments of</title>
        <p>
          M symbols from the communication channel, followed by
majority [
          <xref ref-type="bibr" rid="ref29 ref30">29, 30</xref>
          ] and correlation processing [
          <xref ref-type="bibr" rid="ref31 ref32 ref33">31–33</xref>
          ] of the
accumulated fragments. The values of K and l change
according to the methodology defined in [
          <xref ref-type="bibr" rid="ref26">26</xref>
          ]. A
preestablished minimum threshold for the probability of
correct synchronization Ptrue determines the sufficient
number of accumulated fragments.
        </p>
        <p>
          The frame synchronization method proposed in [
          <xref ref-type="bibr" rid="ref25 ref26">25, 26</xref>
          ]
involves the sequential transmission of a syncword into the
communication channel. For example, for M  8 , such a
syncword is the permutation
  000,001,111,011,010,101,100,110 , up to its circular
shift by a number of bits that is a multiple of lr  3 , bit
inversion, and the reverse order of their sequence.
        </p>
      </sec>
      <sec id="sec-1-10">
        <title>Let us assume that high noise intensity results in the</title>
        <p>receiver being unable to determine the initial moment of the
transmitter’s syncword. In this case, the algorithm for
identifying the boundaries of the syncword is modified
slightly.</p>
      </sec>
      <sec id="sec-1-11">
        <title>Recall that according to [26], the sufficient number of</title>
        <p>accumulated fragments to ensure the minimum value of the
probability of correct synchronization Ptrue _ min is chosen as
the minimum value of l , at which the probability of correct
synchronization for K  1 is not less than the specified</p>
        <sec id="sec-1-11-1">
          <title>Ptrue _ min . Paper [26] denotes this value as lmax 1 . In this</title>
          <p>paper, we will denote it as lmax .</p>
        </sec>
      </sec>
      <sec id="sec-1-12">
        <title>Based on the above and the fact that the initial moment</title>
        <p>of syncword transmission is unknown, the receiver will use
a sliding window with a width of lmax fragments to search
for synchronization (Figure 1).</p>
      </sec>
      <sec id="sec-1-13">
        <title>Thus, the receiver, shifting the sliding window 1 bit to the</title>
        <p>right, continuously analyses lmax fragments received from
the communication channel, attempting to establish frame
synchronization. It is evident that, in this case, the dynamic
adjustment of K and l values is meaningless.</p>
      </sec>
      <sec id="sec-1-14">
        <title>The mathematical model of the syncword reception process will also differ from that presented in [26].</title>
        <p>2.1. Probabilistic metrics of the frame
synchronization system</p>
      </sec>
      <sec id="sec-1-15">
        <title>The probabilities of correct and false synchronization</title>
        <p>depend on the probability of bit error p0* after majority
processing of lmax received fragments. However, the
receiver’s lack of knowledge about the initial moment of
syncword transmission leads to the following.</p>
      </sec>
      <sec id="sec-1-16">
        <title>Since the receiver has to constantly “listen” to the channel, in the absence of a signal from the transmitter, only noise is present in the sliding window. Accordingly, the probability of bit error is equal to 0.5</title>
      </sec>
      <sec id="sec-1-17">
        <title>After the transmitter begins to transmit service signals</title>
        <p>for the clock (not considered in this study) and frame
synchronization into the communication channel,
fragments with syncwords begin to appear in the sliding
window of the receiver synchronization system (Figure 2).
Let there be L bits of the source syncword in the sliding
window (Figure 2). To provide a clearer view of the majority
reception process of the accumulated bits, we represent the
fragments in the sliding window as shown in Figure 3. The
shaded areas contain only noise bits (error probability is
0.5), while the unshaded areas contain bits of the source
syncword (with an error probability of p0 ).</p>
      </sec>
      <sec id="sec-1-18">
        <title>From the accumulated fragments, a refined sequence R is</title>
        <p>computed by the majority, in which some errors (if any) are
corrected.</p>
        <p>It should be noted that the number of bits of the source
syncword present in the sliding window of the receiver’s
synchronization system may not be a multiple of the
codeword length lr  log2 M  , as demonstrated in Figure
3. Therefore, the probability of bit error in the refined
sequence after majority processing of lmax received
fragments can be estimated as follows:
for L  n  lmax  3 :</p>
        <p>2
l1  Cli1 p0i 1  p0 l1 i 
p0*    lmax l1
i0   
 jlmax 1 2i</p>
        <p>lmax l1 0.5lmax l1 
C j 




and for L  n  lmax  3 :
2
(1)
p0* 
lmax l1  Climax l1 0.5lmax l1  
  l1
i0   jlmax 1 2i Cl1j p0j 1  p0 l1  j  ,
 

(2)
 L 
where l1    is the number of complete fragments
 n 
containing only bits of the source syncword (which may be
affected by errors).</p>
      </sec>
      <sec id="sec-1-19">
        <title>Estimates (1) and (2) are formed by replacing the</title>
        <p>fragment that contains noise bits and bits of the syncword
with a fragment that contains only noise bits, as well as
taking into account that p0  0.5 .</p>
        <p>
          Paper [
          <xref ref-type="bibr" rid="ref34">34</xref>
          ] defines that for M  8 and p0  0.4 , the
value of lmax  75 . For parameters M  8 and p0  0.4 , the
graph showing the dependence of the estimated probability
of bit error in the refined sequence R on the value of
L 0;75  24 is presented in Figure 4.
        </p>
      </sec>
      <sec id="sec-1-20">
        <title>The graph has a stepped nature due to the simplifying upper</title>
        <p>estimates (1) and (2). At the same time, at L  0 , the value
is p0*  0.5 , and at L  1800 , the value is p0*  0.0396 .</p>
      </sec>
      <sec id="sec-1-21">
        <title>To calculate the exact value of the obtained probability</title>
        <p>of bit error in the refined sequence, the following statement
can be used.</p>
        <p>Theorem 1. The probability of bit error in the refined
sequence R after receiving L bits of the source syncword
is equal to:


 
 L
 n</p>
        <p>
 l1  </p>
        <p>
l1 1 l1 1 p0i 1  p0 l1 1i </p>
        <p> Ci
  lmax l1 1
i0  
 jlmax 1 2i</p>
        <p>lmax l1 1 0.5lmax l1 1 ;
C j 




for L  n  lmax  1 :
2
,
(3)
p0*   L  l1  </p>
        <p> n 
 1  l1  L 
 n </p>
        <p> 
lmax l1 1 Climax ll1111 0.5lmax l1 1  
i0  jlmax 1 2i Cl1j1 p0j 1  p0 l1 1 j  
 
 ,
lmaxl1  Climax l1l10.5lmax l1  
i0  jlmax 1 2i Cl1j p0j 1  p0 l1  j .</p>
        <p> 

(4)</p>
        <p>Proof.</p>
        <p>We will use Figure 3. Since the number of bits of the
source syncword L in the sliding window is generally not
a multiple of the fragment length lr  M , in L   L   n
 n 
cases out of n в the formation of a bit based on the majority
principle involves  L   1 bits of the source syncword and
 n 
lmax   Ln   1 bits of noise. Accordingly, in n  L   Ln   n
cases out of n the formation of a bit based on the majority
principle involves  L  bits of the source syncword and
 n 
 L 
lmax   n  bits of noise. Consider that a bit error occurs
when the number of errors in the corresponding bits of the
accumulated fragments is not less than the value of lmax  1
2
. Then we can obtain the necessary expressions (3) and (4)
for the bit error probability for
L  n  lmax  1
2
and
L  n  lmax  1 respectively. ■</p>
        <p>2</p>
      </sec>
      <sec id="sec-1-22">
        <title>The graph showing the dependence of the probability of</title>
        <p>bit error in the refined sequence R on the value of
L 0, 75  24 at M  8 and p0  0.4 is presented in
Fig. 5.</p>
      </sec>
      <sec id="sec-1-23">
        <title>To estimate the probabilities of correct and false</title>
        <p>
          synchronization, we will use the expressions defined in [
          <xref ref-type="bibr" rid="ref26">26</xref>
          ]:
dlim
Ptrue  n, dlim, p0, L  Cnv  p0* v 1  p0* nv
        </p>
        <p>v0 (5)
,
.</p>
        <p>Pfalse  n, dlim , p0, L 
 nj11  vdidjijdlim Cdvij  vdwij0dlim Cnw1dij pp0*0*nvwwv  
(6)</p>
        <p>For the syncword   000,001,111,011,010,101,100,110
expression
(5)
takes
the
form:
5
Ptrue 24,5, p0 , L  C2v4  p0* v 1  p0* 24v , and
v0
Error! Reference source not found. transforms to
Pfalse  24,5, p0, L  19 12 C1v2  v7 C1w2  p0* vw   
v7  w01  p0* 24vw 
14 v  v9
2 C14   C1w0  p0* vw 1  p0* 24vw 
 
v9  w0 
16 v  v11
2 C16   C8w  p0* vw 1  p0* 24vw .</p>
        <p>v11  w0 </p>
      </sec>
      <sec id="sec-1-24">
        <title>The graphs of functions (5) and (6) as a function of L at</title>
        <p>M  8 and p0  0.4 are presented in Error! Reference
source not found. and Figure 7.</p>
        <p>Figure 6 and Figure 7 show that the probability of
correct synchronization increases from 0.0033 for L  0 to
0.9997 for L  1800 , while the probability of false
synchronization decreases from 0.076 for L  0 to
1.198 106 for L  1800 .</p>
      </sec>
      <sec id="sec-1-25">
        <title>For experimental confirmation of the dependencies</title>
        <p>Ptrue  24, 5, 0.4, L and Pfalse  24,5, 0.4, L , a computer
simulation modeling of the frame synchronization system
operation process was performed and the relative
frequencies Wtrue 24, 5, 0.4, L  and Wfalse  24,5,0.4, L  of
both correct and false synchronization were determined. For
each value, 1000 tests were performed. The graphs of the
studied dependencies are presented in Figure 8 and Figure
9.</p>
        <sec id="sec-1-25-1">
          <title>A comparative visual assessment of Ptrue  24, 5, 0.4, L and Wtrue 24, 5, 0.4, L  , as well as</title>
          <p>Pfalse  24,5, 0.4, L
and</p>
        </sec>
        <sec id="sec-1-25-2">
          <title>Wfalse  24,5,0.4, L  , indicates the correctness of expressions</title>
          <p>(5) and (6), as well as the adequacy of the developed model.</p>
        </sec>
      </sec>
      <sec id="sec-1-26">
        <title>By analogy with [26]:</title>
        <p></p>
        <p>The
probability</p>
        <p>Ptrue _ final
of
correct
synchronization after receiving L bits of the
syncword is estimated below by the probability:
(7)
Ptrue _ final  n, dlim , p0 , L  Ptrue  n, dlim , p0 , L ;
</p>
        <p>The probability Ptrue _ final of false synchronization
after receiving L bits of the syncword is estimated
from above by the sum of the probabilities of false
synchronization for all values of the accumulated
syncword bits less than L :</p>
        <p>Ptrue _ final n, dlim , p0, L  Ptrue n, dlim , p0 , L . (8)</p>
      </sec>
      <sec id="sec-1-27">
        <title>Thus, the probability of false synchronization turns out</title>
        <p>to be unacceptably high. Figure 10 presents the results of an
experimental study of the relative frequency of true Wtrue
and false Wfalse synchronization for M  8 and p0  0.4 .
2.2. Parameters of the algorithm for
reducing the probability of false
synchronization</p>
      </sec>
      <sec id="sec-1-28">
        <title>One way to reduce the probability of false synchronization</title>
        <p>is to increase the number of K blocks of l fragments.</p>
      </sec>
      <sec id="sec-1-29">
        <title>The approach to increasing the K value [26] involves</title>
        <p>receiving K blocks consisting of l fragments of n bits.</p>
        <sec id="sec-1-29-1">
          <title>For each block, the refined sequences Rk , k  1, K  are</title>
          <p>independently calculated. If all sequences Rk , k  1, K 
correspond to the same syncword shift, the decision device
of the frame synchronization system decides to establish
synchronization.</p>
        </sec>
      </sec>
      <sec id="sec-1-30">
        <title>According to [26, 34], the probability of false</title>
        <p>synchronization for K blocks of l fragments</p>
        <p>Pfalse  n, dlim , p0 , L, l, K  
 nj11  vdidjijdlim Cdvij vdwij0dlim Cnw1dij pp0* 0*nvvww (9)
monotonically decreases with the increase in both K and
l values. On the other hand, the probability of correct
synchronization
K
Ptrue n, dlim , p0 , L,l, K  
 PtrKue n, dlim , p0 , L </p>
        <p> dlim K
   Cnv  p0* v 1  p0* nv </p>
        <p>
 v0 
also monotonically decreases with the increase in K , but
increases with the increase in l . At the same time,
L 0;lr  M  l  K  , and the probability of bit error in the
refined sequences Rk after receiving L syncword bits from
the source can be estimated by modifying expressions (3)
and (4) as follows:
(10)
p0*  1  l1   KL   1n  </p>
        <p>l1  Cli1 p0i 1  p0 l1 i 
 ll1
i0  
 jl 1 2i</p>
        <p>Cljl1 0.5ll1  





   KL   1n  l1  
l1 1 l1 1 p0i 1  p0 l1 1i </p>
        <p> Ci
 ll1 1
i0  
 jl 1 2i</p>
        <p>Cljl1 1 0.5ll1 1 ;





for  L   n  l  1 :
 K  2
(11)
(12)
(13)
(14)
p0*    KL   1n  l1  
ll1 1 Clil1l1110.5l l1 1  
i0  jl1 2i Cl1j1 p0j 1  p0 l1 1 j  
 

  L   1  
 1  l1   K  n </p>
        <p>
l l1  Clil1 l10.5l l1  </p>
        <p> jl1 2i Cl1j p0j 1  p0 l1  j ,
i0   

where l1   L  .</p>
        <p> K  n </p>
      </sec>
      <sec id="sec-1-31">
        <title>To ensure that the probability of false synchronization</title>
        <p>does not exceed its threshold value Pfalse _ max , that the
probability of correct synchronization is at least its
threshold value Ptrue _ min , and that correct synchronization
occurs as quickly as possible, it is necessary to determine a
pair of K and l values, for which
Pfalse _ final n, dlim , p0 , L, l, K   Pfalse _ max ,
Ptrue _ final  n, dlim , p0 , L,l, K   Ptrue _ min , and</p>
      </sec>
      <sec id="sec-1-32">
        <title>K  l takes its</title>
        <p>minimum value. In this case, Pfalse _ final  n, dlim , p0, L, l, K 
and Ptrue _ final  n, dlim , p0 , L,l, K  are estimated as follows:
Pfalse _ final n, dlim , p0, L,l, K  </p>
        <p>L
  Pfalse  n, dlim , p0 , j, l, K ;</p>
        <p>j0
Ptrue _ final n, dlim , p0 , L,l, K  
 Ptrue n, dlim , p0 , L,l, K .
in</p>
        <sec id="sec-1-32-1">
          <title>Let ltrue _ min  K  be the minimum number of fragments</title>
          <p>each of the K blocks, at which
Ptrue _ final  n, dlim , p0, Lmax  K  ,ltrue _ min  K , K   Ptrue _ min ,
Lmax  K   lr  M  ltrue _ min  K   K . Then the task of
determining the pair of  K ;l  values consists of the
following:
5.
6.</p>
          <p>n , dlim , p0 values are specified, and K  1 is
accepted;
Pfalse _ final on L for various K , presented in Fig. 11,
indicate the behaviour of the estimate (13) and demonstrate
the numerical values of the estimate (13) given in Table 9.</p>
        </sec>
      </sec>
      <sec id="sec-1-33">
        <title>Based on the values presented in Table 1, for the considered</title>
        <p>example with M  8 , p0  0.4 , Ptrue _ min  0.9997 , and
Pfalse _ max  0.0003 , it is sufficient to choose the K  4 value.</p>
        <p>Another potential method for reducing the probability
of false synchronization could be to decrease the maximum
distance dlim to the syncword shifts used in identifying the
refined sequence R. However, reducing dlim leads to a
decrease in the probability of correct synchronization,
which necessitates increasing the accumulation coefficient
l. This approach may be effective; however, it is not
considered in this paper.
3. Algorithm for reliable</p>
        <p>transmission of permutations</p>
      </sec>
      <sec id="sec-1-34">
        <title>Frame synchronization establishment initiates the next stage of the protocol, the reliable transmission of permutations.</title>
      </sec>
      <sec id="sec-1-35">
        <title>The algorithm for reliable transmission of permutations based on method [28] consists of the following: 1.</title>
      </sec>
      <sec id="sec-1-36">
        <title>The transmitter sends into the communication</title>
        <p>channel a permutation-word W consisting of N
symbols-letters Lj, 1 ≤ j ≤ N. Each letter is a
circular bit shift of permutation π of length M,
which has the maximum value of the minimum
Hamming distance from its n-bit binary
representation to all its circular shifts.</p>
      </sec>
      <sec id="sec-1-37">
        <title>Analogous to the procedure of frame synchronization, for each letter, the transmitter sends and the receiver receives, accumulates, and analyses l fragments of n-bit each.</title>
      </sec>
      <sec id="sec-1-38">
        <title>For each letter, the refined sequence Rj, j ∊ [1,N], is computed using the majority processing of the received bits.</title>
      </sec>
      <sec id="sec-1-39">
        <title>For each refined sequence Rj, the Hamming</title>
        <p>distances to the letters used by the source are
calculated. If the distance does not exceed dlim, the
jth symbol of the word W is associated with the
corresponding alphabet letter.</p>
        <p>If the received word is a permutation of the letters
of the alphabet used by the source, and this
permutation is used by the source, the word is
accepted, and the process of recognizing the next
word begins.
should
be
noted
that
the
function</p>
        <sec id="sec-1-39-1">
          <title>Ptrue _ final  n, dlim , p0 , L,l, K  monotonically increases with an</title>
          <p>increase in L and, for example, at L  4432 the value is
Ptrue  24,5, 0.4, L,85, 4  0.5 , while at L  5640 the value is
Ptrue  24,5, 0.4, L,85, 4  0.9 .</p>
        </sec>
      </sec>
      <sec id="sec-1-40">
        <title>Considering that</title>
        <p>Pfalse _ final  24,5, 0.4, L,85, 4  2.9 106 , this leads to the
conclusion that there will be a 90% probability of correct
synchronization being established after receiving 5640
fragments containing bits of the source’s synchronization
word. Since 8160 – 5640 = 2520, n = 24, in 90% of cases, the
reliable reception procedure for the permutation, which
follows the synchronization procedure and is initiated by
the fact of establishing synchronization, will utilize the
shifted boundaries of the data block used for transmitting a
single permutation (synchronization was completed earlier,
the recognition of the permutation began sooner, while the
synchronization words are still being transmitted in the
channel).</p>
      </sec>
      <sec id="sec-1-41">
        <title>Such desynchronization leads to a decrease in the</title>
        <p>efficiency of the permutation recognition procedure, which
needs to be compensated for with additional procedures.</p>
      </sec>
      <sec id="sec-1-42">
        <title>The development of such procedures requires separate research and is beyond the scope of this study.</title>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>4. Conclusions</title>
      <p>The completed study has led to the development of
algorithms for the protocol of reliable permutation
transmission for simplex data transmission systems with
non-separable factorial coding under conditions of high
noise intensity in the communication channel. To achieve
this, it was considered the problem of joint application of
the frame synchronization algorithm, which uses as a
syncword a permutation with the maximum value of the
minimum Hamming distance from its binary representation
to all its circular shifts, as well as the reliable permutation
transmission algorithm. The adaptation of the frame
synchronization algorithm for simplex communication
systems with an unknown moment of the start of receiving
syncwords from the transmitter has necessitated the use of
a sliding window.</p>
      <p>An example of the reliable permutation transmission
protocol algorithms has been considered for a
communication channel error probability p0 = 0.4. The
defined parameters of the proposed algorithms made it
possible to conduct a simulation of the frame
synchronization process. The obtained simulation results
confirmed the theoretical estimates.</p>
      <sec id="sec-2-1">
        <title>The identified problem areas related to the detection of syncword and data word boundaries have allowed for the formulation of pathways for further research.</title>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>Acknowledgments</title>
      <sec id="sec-3-1">
        <title>This research was funded by the Science Committee of the</title>
      </sec>
      <sec id="sec-3-2">
        <title>Ministry of Science and Higher Education of the Republic of</title>
      </sec>
      <sec id="sec-3-3">
        <title>Kazakhstan (Grant No. AP23489168).</title>
      </sec>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          <string-name>
            <given-names>E. V.</given-names>
            <surname>Faure</surname>
          </string-name>
          ,
          <article-title>Factorial Coding with Data Recovery</article-title>
          , Bulletin of Cherkasy State Technological University,
          <volume>2</volume>
          (
          <year>2016</year>
          )
          <fpage>33</fpage>
          -
          <lpage>39</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          <string-name>
            <given-names>J. S.</given-names>
            <surname>Al-Azzeh</surname>
          </string-name>
          , et al.,
          <source>, Telecommunication Systems with Multiple Access Based on Data Factorial Coding</source>
          ,
          <source>International Journal on Communications Antenna and Propagation (IRECAP)</source>
          ,
          <volume>10</volume>
          (
          <issue>2</issue>
          ) (
          <year>2020</year>
          )
          <fpage>102</fpage>
          -
          <lpage>113</lpage>
          . doi:
          <volume>10</volume>
          .15866/irecap.v10i2.
          <fpage>17216</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          <string-name>
            <given-names>A.-S.</given-names>
            <surname>Bana</surname>
          </string-name>
          , et al.,
          <article-title>Short Packet Structure for UltraReliable Machine-Type Communication: Tradeoff between Detection and Decoding</article-title>
          , IEEE International Conference on Acoustics,
          <source>Speech and Signal Processing (ICASSP)</source>
          (
          <year>2018</year>
          )
          <fpage>6608</fpage>
          -
          <lpage>6612</lpage>
          . doi:
          <volume>10</volume>
          .1109/ICASSP.
          <year>2018</year>
          .
          <volume>8461650</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          [4]
          <string-name>
            <given-names>C.</given-names>
            <surname>Feng</surname>
          </string-name>
          ,
          <string-name>
            <given-names>H.</given-names>
            <surname>Wang</surname>
          </string-name>
          ,
          <article-title>Secure Short-Packet Communications at the Physical Layer for 5G and Beyond (</article-title>
          <year>2021</year>
          ). doi:
          <volume>10</volume>
          .48550/arXiv.2107.05966.
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          [5]
          <string-name>
            <given-names>C.</given-names>
            <surname>Feng</surname>
          </string-name>
          , H.
          <string-name>
            <surname>-M. Wang</surname>
            ,
            <given-names>H. V.</given-names>
          </string-name>
          <string-name>
            <surname>Poor</surname>
            , Reliable and
            <given-names>Secure</given-names>
          </string-name>
          <string-name>
            <surname>Short-Packet</surname>
            <given-names>Communications</given-names>
          </string-name>
          ,
          <source>IEEE Trans. Wireless Commun</source>
          .
          <volume>21</volume>
          (
          <issue>3</issue>
          ) (
          <year>2022</year>
          )
          <fpage>1913</fpage>
          -
          <lpage>1926</lpage>
          . doi:
          <volume>10</volume>
          .1109/TWC.
          <year>2021</year>
          .
          <volume>3108042</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          [6]
          <string-name>
            <given-names>R.</given-names>
            <surname>Aleksieieva</surname>
          </string-name>
          , et al.,
          <article-title>Software Tool for Ensuring Data Integrity and Confidentiality Through the Use of Cryptographic Mechanisms</article-title>
          ,
          <source>in: 5th International Workshop on Modern Machine Learning Technologies and Data Science</source>
          , vol.
          <volume>3426</volume>
          (
          <year>2023</year>
          )
          <fpage>259</fpage>
          -
          <lpage>273</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          [7]
          <string-name>
            <given-names>E. V.</given-names>
            <surname>Faure</surname>
          </string-name>
          ,
          <article-title>Factorial Coding with Error Correction, Radio Electronics</article-title>
          , Computer Science, Control,
          <volume>3</volume>
          (
          <year>2017</year>
          )
          <fpage>130</fpage>
          -
          <lpage>138</lpage>
          . doi:
          <volume>10</volume>
          .15588/
          <fpage>1607</fpage>
          -3274-2017-3-15.
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          [8]
          <string-name>
            <given-names>O. A.</given-names>
            <surname>Borysenko</surname>
          </string-name>
          , et al.,
          <article-title>Noise-Immune Transfer of Decimal Data with Protection Based on Permutations</article-title>
          ,
          <source>in: IEEE 13th International Conference on Electronics and Information Technologies (ELIT)</source>
          (
          <year>2023</year>
          )
          <fpage>248</fpage>
          -
          <lpage>251</lpage>
          . doi:
          <volume>10</volume>
          .1109/ELIT61488.
          <year>2023</year>
          .
          <volume>10310685</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          [9]
          <string-name>
            <given-names>O.</given-names>
            <surname>Borysenko</surname>
          </string-name>
          ,
          <source>Protection of Numerical Information Based on Permutations, in: 3rd International Scientific and Practical Conference “Information Security and Information Technologies”</source>
          , vol.
          <volume>3200</volume>
          (
          <year>2021</year>
          )
          <fpage>62</fpage>
          -
          <lpage>67</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          [10]
          <string-name>
            <given-names>O.</given-names>
            <surname>Borysenko</surname>
          </string-name>
          et al.,
          <source>Factorial Numbers and Their Practical Applications, Appl. Sci</source>
          .
          <volume>14</volume>
          (
          <issue>19</issue>
          ) (
          <year>2024</year>
          )
          <article-title>8588</article-title>
          . doi:
          <volume>10</volume>
          .3390/app14198588.
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          [11]
          <string-name>
            <given-names>B.</given-names>
            <surname>Lee</surname>
          </string-name>
          , et al.,
          <article-title>Packet Structure and Receiver Design for Low Latency Wireless Communications with UltraShort Packets</article-title>
          ,
          <source>IEEE Trans. Commun</source>
          .
          <volume>66</volume>
          (
          <issue>2</issue>
          ) (
          <year>2018</year>
          )
          <fpage>796</fpage>
          -
          <lpage>807</lpage>
          . doi:
          <volume>10</volume>
          .1109/TCOMM.
          <year>2017</year>
          .
          <volume>2755012</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          [12]
          <string-name>
            <given-names>H.</given-names>
            <surname>Lee</surname>
          </string-name>
          ,
          <string-name>
            <given-names>Y.-C.</given-names>
            <surname>Ko</surname>
          </string-name>
          ,
          <article-title>Physical Layer Enhancements for Ultra-Reliable Low-Latency Communications in 5G New Radio Systems</article-title>
          ,
          <source>IEEE Comm. Stand. Mag</source>
          .
          <volume>5</volume>
          (
          <issue>4</issue>
          ) (
          <year>2021</year>
          )
          <fpage>112</fpage>
          -
          <lpage>122</lpage>
          . doi:
          <volume>10</volume>
          .1109/
          <string-name>
            <surname>MCOMSTD</surname>
          </string-name>
          .
          <volume>0001</volume>
          .2100002.
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          [13]
          <string-name>
            <given-names>J.</given-names>
            <surname>Park</surname>
          </string-name>
          , et al.,
          <article-title>Extreme Ultra-Reliable and</article-title>
          <string-name>
            <surname>Low-Latency</surname>
            <given-names>Communication</given-names>
          </string-name>
          ,
          <source>Nat Electron</source>
          ,
          <volume>5</volume>
          (
          <issue>3</issue>
          ) (
          <year>2022</year>
          )
          <fpage>133</fpage>
          -
          <lpage>141</lpage>
          . doi:
          <volume>10</volume>
          .1038/s41928-022-00728-8.
        </mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>
          [14]
          <string-name>
            <given-names>Y.</given-names>
            <surname>Li</surname>
          </string-name>
          , et al.,
          <article-title>Unmanned Aerial Vehicle‐Aided Edge Networks with Ultra‐Reliable Low‐Latency Communications: A digital twin approach</article-title>
          ,
          <source>IET Signal Processing</source>
          ,
          <volume>16</volume>
          (
          <issue>8</issue>
          ) (
          <year>2022</year>
          )
          <fpage>897</fpage>
          -
          <lpage>908</lpage>
          . doi:
          <volume>10</volume>
          .1049/sil2.
          <fpage>12128</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          [15]
          <string-name>
            <given-names>A.</given-names>
            <surname>Traßl</surname>
          </string-name>
          , et al.,
          <article-title>Outage prediction for ultra-reliable low-latency communications in fast fading channels</article-title>
          ,
          <source>J. Wireless Com. Netw</source>
          .
          <year>2021</year>
          (
          <volume>92</volume>
          ) (
          <year>2021</year>
          ). doi:
          <volume>10</volume>
          .1186/s13638-021-01964-w.
        </mixed-citation>
      </ref>
      <ref id="ref16">
        <mixed-citation>
          [16]
          <string-name>
            <given-names>K.</given-names>
            <surname>Wang</surname>
          </string-name>
          , et al.,
          <article-title>Packet Error Probability and Effective Throughput for Ultra-Reliable and Low-Latency UAV Communications</article-title>
          ,
          <source>IEEE Trans. Commun</source>
          .
          <volume>69</volume>
          (
          <issue>1</issue>
          ) (
          <year>2021</year>
          ). doi:
          <volume>10</volume>
          .1109/TCOMM.
          <year>2020</year>
          .
          <volume>3025578</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref17">
        <mixed-citation>
          [17]
          <string-name>
            <given-names>R.</given-names>
            <surname>Odarchenko</surname>
          </string-name>
          ,
          <article-title>Evaluation and Improvement of QoE and QoS Parameters in Commercial 5G Networks: 5GTOURS Approach, IJC (</article-title>
          <year>2023</year>
          )
          <fpage>462</fpage>
          -
          <lpage>474</lpage>
          . doi:
          <volume>10</volume>
          .47839/ijc.22.4.3353.
        </mixed-citation>
      </ref>
      <ref id="ref18">
        <mixed-citation>
          [18]
          <string-name>
            <given-names>X.</given-names>
            <surname>Li</surname>
          </string-name>
          , et al.,
          <article-title>Blocklength Allocation and Power Control in UAV-Assisted URLLC System via Multi-agent Deep Reinforcement Learning</article-title>
          ,
          <source>Int. J. Comput. Intell. Syst</source>
          .
          <volume>17</volume>
          (
          <issue>138</issue>
          ) (
          <year>2024</year>
          ).
          <source>doi: 10.1007/s44196-024-00530-8.</source>
        </mixed-citation>
      </ref>
      <ref id="ref19">
        <mixed-citation>
          [19]
          <string-name>
            <given-names>B.</given-names>
            <surname>Schneier</surname>
          </string-name>
          , Applied Cryptography: Protocols, Algorithms, and Source Code in
          <string-name>
            <surname>C</surname>
          </string-name>
          , 2nd ed. New York: Wiley (
          <year>1996</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref20">
        <mixed-citation>
          [20]
          <string-name>
            <surname>D. M. Nguyen</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          <string-name>
            <surname>Kim</surname>
            ,
            <given-names>A Quantum</given-names>
          </string-name>
          <string-name>
            <surname>Three</surname>
          </string-name>
          <article-title>Pass Protocol with Phase Estimation for Many Bits Transfer</article-title>
          ,
          <source>International Conference on Advanced Technologies for Communications (ATC)</source>
          (
          <year>2019</year>
          )
          <fpage>129</fpage>
          -
          <lpage>132</lpage>
          . doi:
          <volume>10</volume>
          .1109/ATC.
          <year>2019</year>
          .
          <volume>8924514</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref21">
        <mixed-citation>
          [21]
          <string-name>
            <given-names>A.</given-names>
            <surname>Badawi</surname>
          </string-name>
          ,
          <string-name>
            <given-names>M.</given-names>
            <surname>Zarlis</surname>
          </string-name>
          ,
          <string-name>
            <given-names>S.</given-names>
            <surname>Suherman</surname>
          </string-name>
          , Impact Three Pass Protocol Modifications to key Transmission Performance,
          <source>J. Phys.: Conf. Ser</source>
          .
          <volume>1235</volume>
          (
          <year>2018</year>
          ). doi:
          <volume>10</volume>
          .1088/
          <fpage>1742</fpage>
          -6596/1235/1/012050.
        </mixed-citation>
      </ref>
      <ref id="ref22">
        <mixed-citation>
          [22]
          <string-name>
            <given-names>A.</given-names>
            <surname>Moldovyan</surname>
          </string-name>
          ,
          <string-name>
            <given-names>D.</given-names>
            <surname>Moldovyan</surname>
          </string-name>
          , N. Moldovyan, PostQuantum Commutative Encryption Algorithm,
          <source>Comput. Sci. J</source>
          . Moldova,
          <volume>81</volume>
          (
          <issue>3</issue>
          ) (
          <year>2019</year>
          )
          <fpage>299</fpage>
          -
          <lpage>317</lpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref23">
        <mixed-citation>
          [23]
          <string-name>
            <given-names>A.</given-names>
            <surname>Shcherba</surname>
          </string-name>
          ,
          <string-name>
            <given-names>E.</given-names>
            <surname>Faure</surname>
          </string-name>
          ,
          <string-name>
            <given-names>O.</given-names>
            <surname>Lavdanska</surname>
          </string-name>
          , Three-Pass
          <source>Cryptographic Protocol Based on Permutations, IEEE 2nd International Conference on Advanced Trends in Information Theory (ATIT)</source>
          (
          <year>2020</year>
          )
          <fpage>281</fpage>
          -
          <lpage>284</lpage>
          . doi:
          <volume>10</volume>
          .1109/ATIT50783.
          <year>2020</year>
          .
          <volume>9349343</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref24">
        <mixed-citation>
          [24]
          <string-name>
            <given-names>E.</given-names>
            <surname>Faure</surname>
          </string-name>
          , et al.,
          <source>Method of Cyclic Synchronization Based on Permutations</source>
          , Bulletin of Cherkasy State Technological University,
          <volume>4</volume>
          (
          <year>2020</year>
          )
          <fpage>67</fpage>
          -
          <lpage>76</lpage>
          . doi:
          <volume>10</volume>
          .24025/
          <fpage>2306</fpage>
          -
          <lpage>4412</lpage>
          .4.
          <year>2020</year>
          .
          <volume>222439</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref25">
        <mixed-citation>
          [25]
          <string-name>
            <given-names>E.</given-names>
            <surname>Faure</surname>
          </string-name>
          ,
          <string-name>
            <given-names>A.</given-names>
            <surname>Shcherba</surname>
          </string-name>
          ,
          <string-name>
            <given-names>B.</given-names>
            <surname>Stupka</surname>
          </string-name>
          ,
          <article-title>Permutation-Based Frame Synchronisation Method for Short Packet Communication Systems</article-title>
          ,
          <source>in: 11th IEEE International Conference on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications (IDAACS)</source>
          (
          <year>2021</year>
          )
          <fpage>1073</fpage>
          -
          <lpage>1077</lpage>
          . doi:
          <volume>10</volume>
          .1109/IDAACS53288.
          <year>2021</year>
          .
          <volume>9660996</volume>
          .
        </mixed-citation>
      </ref>
      <ref id="ref26">
        <mixed-citation>
          [26]
          <string-name>
            <given-names>J.</given-names>
            <surname>Al-Azzeh</surname>
          </string-name>
          , et al.,
          <article-title>Permutation-based Frame Synchronization Method for Data Transmission Systems with Short Packets</article-title>
          , Egyptian Informatics J.
          <volume>23</volume>
          (
          <issue>3</issue>
          ) (
          <year>2022</year>
          )
          <fpage>529</fpage>
          -
          <lpage>545</lpage>
          . doi:
          <volume>10</volume>
          .1016/j.eij.
          <year>2022</year>
          .
          <volume>05</volume>
          .005.
        </mixed-citation>
      </ref>
      <ref id="ref27">
        <mixed-citation>
          [27]
          <string-name>
            <given-names>J.</given-names>
            <surname>Al-Aazzeh</surname>
          </string-name>
          , et al.,
          <source>Efficiency Assessment of the Permutation-based Frame Synchronization Method, Int. J. Commun. Antenna Propagation</source>
          ,
          <volume>13</volume>
          (
          <issue>4</issue>
          ) (
          <year>2023</year>
          ). doi:
          <volume>10</volume>
          .15866/irecap.v13i4.
          <fpage>23567</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref28">
        <mixed-citation>
          [28]
          <string-name>
            <given-names>E.</given-names>
            <surname>Faure</surname>
          </string-name>
          , et al.,
          <article-title>A Method for Reliable Permutation Transmission in Short-Packet Communication Systems, Information Technology for Education, Science</article-title>
          , and Technics,
          <volume>178</volume>
          (
          <year>2023</year>
          )
          <fpage>177</fpage>
          -
          <lpage>195</lpage>
          . doi:
          <volume>10</volume>
          .1007/978-3-
          <fpage>031</fpage>
          -35467-0_
          <fpage>12</fpage>
          .
        </mixed-citation>
      </ref>
      <ref id="ref29">
        <mixed-citation>
          [29]
          <string-name>
            <given-names>D. E.</given-names>
            <surname>Knuth</surname>
          </string-name>
          ,
          <article-title>The Art of Computer Programming: Introduction to Combinatorial Algorithms</article-title>
          and Boolean Functions, vol. 4A. Upper Saddle River, NJ:
          <string-name>
            <surname>Addison-Wesley</surname>
          </string-name>
          (
          <year>2008</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref30">
        <mixed-citation>
          [30]
          <string-name>
            <surname>I. Yoshinori</surname>
          </string-name>
          , Majority Circuit,
          <source>JPH01296825A</source>
          (
          <year>1989</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref31">
        <mixed-citation>
          [31]
          <string-name>
            <given-names>T. J.</given-names>
            <surname>Terrell</surname>
          </string-name>
          , L.
          <article-title>-</article-title>
          K. Shark,
          <source>Digital Signal Processing. London: Macmillan Education UK</source>
          (
          <year>1996</year>
          ). doi:
          <volume>10</volume>
          .1007/978-1-
          <fpage>349</fpage>
          -13735-0.
        </mixed-citation>
      </ref>
      <ref id="ref32">
        <mixed-citation>
          [32]
          <string-name>
            <given-names>L.</given-names>
            <surname>Tan</surname>
          </string-name>
          ,
          <string-name>
            <given-names>J.</given-names>
            <surname>Jiang</surname>
          </string-name>
          ,
          <source>Digital Signal Processing, Fundamentals and Applications</source>
          , 3rd ed.
          <source>Elsevier</source>
          (
          <year>2019</year>
          ). doi:
          <volume>10</volume>
          .1016/C2017-0-02319-4.
        </mixed-citation>
      </ref>
      <ref id="ref33">
        <mixed-citation>
          [33]
          <string-name>
            <given-names>G.</given-names>
            <surname>Galati</surname>
          </string-name>
          , G. Pavan,
          <string-name>
            <given-names>C.</given-names>
            <surname>Wasserzier</surname>
          </string-name>
          , Signal Design and
          <article-title>Processing for Noise Radar</article-title>
          ,
          <string-name>
            <given-names>EURASIP J.</given-names>
            <surname>Adv</surname>
          </string-name>
          .
          <source>Signal Process</source>
          .
          <volume>52</volume>
          (
          <year>2022</year>
          ).
          <source>doi: 10.1186/s13634-022-00884-1.</source>
        </mixed-citation>
      </ref>
      <ref id="ref34">
        <mixed-citation>
          [34]
          <string-name>
            <given-names>E. V.</given-names>
            <surname>Faure</surname>
          </string-name>
          ,
          <string-name>
            <given-names>B. A.</given-names>
            <surname>Stupka</surname>
          </string-name>
          ,
          <article-title>Evaluation of Frame Synchronization Efficiency for Non-Separable Factorial Codes Depending on Synchronization Parameters, Èlektron</article-title>
          . Model.
          <volume>44</volume>
          (
          <issue>6</issue>
          ) (
          <year>2022</year>
          )
          <fpage>21</fpage>
          -
          <lpage>35</lpage>
          . doi:
          <volume>10</volume>
          .15407/emodel.44.06.021.
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>