Aerospace and Electronic Systems Magazine April 2017 - 52
Integration of Reed-Solomon Codes to Licklider Transmission Protocol (LTP) for Space DTN
focus is on the evaluation the performance advantage of RS-LTP
over LTP without RS coding implemented (termed "LTP-UDP").
Figure 3 provides a comparison of the data delivery time between LTP-UDP and RS-LTP for transmission with different bundle
sizes over the emulated space communication infrastructure with
different channel qualities (i.e., with BERs of 10−6, 10−5, and 10−4).
Overall, the two protocols show statistically signficant difference of
the data delivery time at all the experimented scenarios-for each of
four experimented bundle sizes, RS-LTP shows significantly shorter
data delivery time at all three channel BERs. This indicates that RSLTP outperforms LTP-UDP from the perspective of transmission
effectiveness for reliable delivery in the emulated space scenarios.
In comparison, the performance variation trends of LTP-UDP
and RS-LTP along with an increase of channel BER are quite different. This leads to variations of the performance difference between
two protocols. For each of the experimented bundle sizes, RS-LTP
shows nearly equal data delivery time even with the variations of
channel BER. In contrast, LTP-UDP shows significant increase of
the data delivery time. When channel BER increases from 10−6 to
10−5, LTP-UDP has obvious increase of the time, around 2-5 sec,
depending on the selected bundle size. Along with further increase
in BER from 10−5 to 10−4, the data delivery time of LTP-UDP increases drastically, for around 10-13 sec.
To have a better understanding of how the performance changes with variations in bundle size and channel quality, Figure 4 presents a comparison of the data delivery time among three BERs and
four bundle sizes for each protocol. For LTP-UDP, its data delivery
time increases gradually with an exponential increase in bundle
size from 4 Kbytes to 32 Kbytes for each of three channel quality settings. This indicates that increasing bundle size results in an
increase of the data delivery time of LTP-UDP. In other words, the
larger the bundle size, the longer the data delivery time. It is also
Comparison of data delivery time between LTP-UDP and RS-LTP for transmission with different channel qualities for different bundle sizes. (a) Bundle
size = 4 Kbytes. (b) Bundle size = 8 Kbytes. (c) Bundle size = 16 Kbytes. (d) Bundle size = 32 Kbytes.
IEEE A&E SYSTEMS MAGAZINE