An analysis of results of performed calculations
shows the following: an increase of
leads to a decreasing in the bit error probability.
This matches with the requirements on the CQ and
the noise immunity level of DTS tracts at the given
rates for bit and code. Thus, the proposed
mathematical model allows to assessment of noise
immunity of the CM receiver when impacts of the
unintentional interference. This MM considers the
energy indicators of the modems, manipulation type
at modulation, bit rate, and coding rate.
The results of research and analysis presented in
the article can be used in a mathematical model for
assessment of the noise immunity (NI) at incoherent
receiving in DTS. These research results increase
the reliability and accuracy of data receiving. To
provide the CQ of DTS under the influence of
unintentional interference, and to ensure noise
immunity of DTS with the required quality of
service (QoS) at the channel and physical levels, it
is necessary to develop and apply the new receiving
models. Regarding this, the problems of assessment
of the noise immunity parameters during the design
of DTS are urgent. Investigation results on the
optimal receiving of discrete signals and
determination of an error probability in coherent
receiving were presented in, [4], [5]. The aim of this
work is to develop a MM to assess of the noise
immunity during the incoherent receiving in DTS
that operate under the impacts of unintentional
interference.
Let now us analyze the operating quality of the
DTS, under the influence of unintentional
interference sources.
At the channel and physical level in
telecommunication system (TCS) Modularly Phase
Shift Keying (M-PSK) modulation and the
polynomial RS code
are used. The
parameters of the RS code are [8]. The RS
codes that used in the given system are directly
cyclic codes, with an error correction set, which can
be defined as presented in, [2]. As the main
indicator to assess the quality of TCS during the
impacts of interference, the average value of an
error probability is accepted. Thus, the need of
development a MM to improve the QC by applying
effective coding and modulation algorithms, as well
as for assessment of the noise immunity, is the
actuality of the problem. So, if the noise immunity
of receiving depends on the random parameters of
the receiver, then it’s the quantitative measure can
be the malfunction probability of the system. This
probability is assessed by the average probability,
which shows of an erroneous receiving and depends
on SNR at the input of the receiver, also is a
monotonic function as:
},)],(,[(,{][ bbEbkse VMVkESNRRFPE
, (17)
where
is the Reed-Solomon coding rate,
.
An energy transmitting coefficient
is
determined considering the bit signal energy and the
signal-to-noise ratio as follows:
, (18)
where
the bit signal energy is at the input.
Considering the above and expression (18), the
mathematical statement of the given problem on the
development of MM, the objective function to
assess noise immunity of the TCS can be recorded
as follow:
)]}([min{)( 2
cse
h
nhPEArgWЕK
c
, (19)
at the following restrictions
, ,
С
, (20)
where - maximum throughput for the given
TCS during the multimedia services;
bit
errors probability;
spectral efficiency of
TCS at the incoherent receiving. which shows the
using efficiency of the bandwidth
of the binary
signal;
,
the admissible
values respectively.
The last expression (20) also (21) is the basis of
the new approach. Based on them a MM for
assessment of the NI of a TCS was developed. This
MM considers the CQ, coding methods, modulation
scheme, and spectral efficiency, [14]. At the same
time, obtained expressions allow us to analytically
represent the NI function to assess the performance
of the TCS enough simple. To implement the new
approach used in constructing the MM, a scheme for
the operation of an optical receiver with incoherent
receiving is proposed. To perform the task by the
method of random-phase incoherent receiving, it is
necessary to study the paths of the transmission and
receiving systems of discrete data. Then, by
comparison with the threshold estimation DQ, a
decision is made in favor of assumptions H0 and H1.
WSEAS TRANSACTIONS on COMMUNICATIONS
DOI: 10.37394/23204.2023.22.19
Mehdiyeva Almaz, Bakhshaliyeva Sevinj