IV - Extra » History » Version 7

COLIN, Tony, 12/15/2015 10:11 PM

1 3 COLIN, Tony
h1. IV - Extra
2 2 COLIN, Tony
3 7 COLIN, Tony
{{>toc}}
4 7 COLIN, Tony
5 5 COLIN, Tony
h2. 1. CubeSat performances
6 1 COLIN, Tony
7 5 COLIN, Tony
h3. 1.1 Measurement of encoding/decoding time.
8 5 COLIN, Tony
9 4 COLIN, Tony
POSIX requires that CLOCKS_PER_SEC equals 1000000 independent of the actual resolution.
10 4 COLIN, Tony
11 4 COLIN, Tony
p=. !Clock1.png!
12 4 COLIN, Tony
*1000 ticks per milliseconds*
13 4 COLIN, Tony
14 4 COLIN, Tony
p=. !Clock2.png!
15 4 COLIN, Tony
*Time measurement of data encoding*
16 4 COLIN, Tony
17 4 COLIN, Tony
p=. !Clock3.png!
18 4 COLIN, Tony
*Printing clock data*
19 4 COLIN, Tony
20 4 COLIN, Tony
p=. !Time_RS_resized.PNG!
21 4 COLIN, Tony
*Chart of Reed Solomon time measurement*
22 4 COLIN, Tony
23 4 COLIN, Tony
Floating-Point OPeration (FLOP)
24 4 COLIN, Tony
25 4 COLIN, Tony
p=. !FLOPs2.png!
26 4 COLIN, Tony
27 4 COLIN, Tony
28 1 COLIN, Tony
Hence, encoding stands for *O(nbytes x NPAR)* with _nbytes_ is the codeword length, _NPAR_ the number of parity bits.
29 1 COLIN, Tony
Since it is a systematic code _nbytes = information_word_length + NPAR_ encoding stands for *O(information_word_length)* with NPAR constant.
30 5 COLIN, Tony
31 5 COLIN, Tony
h3. 1.2 Busy memory on CubeSat.
32 5 COLIN, Tony
33 5 COLIN, Tony
p=. !Memory.png!
34 5 COLIN, Tony
35 5 COLIN, Tony
---
36 1 COLIN, Tony
37 7 COLIN, Tony
h2. 2. Current topics.
38 6 COLIN, Tony
39 6 COLIN, Tony
For the purpose of reliability for Land Mobile Satellite (LMS) channel, a solution is discussed about error correcting code on the Transport layer [1]. Regarding new trends of erasure codes related to satellites [2], an efficient way to perform encoding over LMS channel is to consider _Non-Binary codes_ such as Reed-Solomon code (studied in [[III - Advanced Project]] chapter) or Non-Binary LDPC code (which is highly complex to implement). The Non-Binary characteristic would be to consider a whole packet or a sliced packet as a symbol in order to decrease the error probability of packets. 
40 6 COLIN, Tony
A possible continuity to this project could be to integrate the OpenFEC code available on "OpenFEC - Downloads":http://openfec.org/downloads.html in the CubeSat Kit. This would be easily done by following chapter [[II - Tutorial - Simple project on CubeSat Kit|II - Tutorial]] and [[III - Advanced Project|III - Advanced Project]]
41 6 COLIN, Tony
42 1 COLIN, Tony
Research papers proposed on IEEE Website :
43 6 COLIN, Tony
[1] "Transport layer coding for the land mobile satellite channel":http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=1391458&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D1391458
44 6 COLIN, Tony
[2] "Erasure Codes for Space Communications: Recent Findings and New Challenges":http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6333092&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6333092
45 6 COLIN, Tony
46 6 COLIN, Tony
---