However, the received result is calculated on the condition of use all modulation
and coding sets; but is it advisable to use them in a duplex multi-system? The answer
to this question is provided in the next section.
6.
Suggestions for improving the DVB-T2 procedures for information
transmission in MSDS.
Obviously, the DVB-T2 standard has a large set of different services and services
for transmission. DVB-T2 also must have high productivity. All these features, in terms
of quality and system performance are provided in the television standard, but the same
characteristics and performance would be useful in other telecommunication systems
as well.
Therefore, it is advisable to use these tools and features of DVB-T2 standard for
MSDS, that will respond to the changes on the line; for example, in the case of urgent
wireless networks deployment in emergency situations when no time available for
accurate channel energy calculations and when channel conditions change. In this case,
the transmission conditions are appropriate for specific conditions of use, and to adapt
to the changing conditions through appropriate adaptive responses in system.
The DVB-T2 standard has 24 combinations of six encoding gradation and four
modulation types. But is is advisable to use a combination all of these in a two-way
systems, namely in mobile communications?
Based on these considerations, it’s necessary to select those coding rates that are
appropriate for use in system.
QPSK guarantees the required BER=
10
−6
on the rate 1/2 in a switching point,
and is the starting point for productivity. Other coding stages, according to Fig. 5,
overlap by more positional modulation type QAM-16 and then the gradations 3/5, 2/3,
3/4, 4/5, 5/6 from the previous modulation QPSK are no longer relevant and should
therefore be excluded from processing. According to this principle, the other coding
modulation gradations are calculated. So, in order to finally propose the elimination of
unnecessary coding gradations, it’s needed to calculate by using the Okamura-Khata
model the new values of parameters, taking into account the fact that the percentage
of lost productivity is low.
Table 1 MCS combinations reduction
MCS : coding rate and
modulation
QPSK
QAM-16
QAM-64
1/2
+
+
-
3/5
-
-
+
2/3
-
+
-
¾
-
-
+
4/5
-
+
-
5/6
-
-
+
Source: compiled by the authors
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