itu-r channel model implementation issues
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1/18CJK9 , Zhangjiajie, China
ITU-R Channel ModelImplementation Issues
Document numberZhangjiajia, China
8-10 April 2009
Hyun Kyu(HK) Chung(hkchung@etri.re.kr)
PG707 Chair in TC7, TTA
CJK9 , Zhangjiajie, China 2/18
Introduction
Issue
Solution
Action Items
Annex
CJK9 , Zhangjiajie, China 3/18
1. Introduction
WINNER Group (Finland & China) released the Matlab source code (in a contribution) claiming implementation of the IMT-Advanced Channel Model.
TTA Eval Group PG707 has been developing C-based implementation of IMT-Advanced channel model for LLS and SLS.
Our works are intended to release C-level source code in the coming WP5D meeting in Geneva
We have some correction issues for Matlab source code, and hope to share with CJK SIG, seeking for comments and possible cooperation.
CJK9 , Zhangjiajie, China 4/18
We cannot simply rely on the Matlab Code from the WINNER
Not C/C++
Have we checked they are really correct
We have a C-based channel model butNot sure we implement the channel model correctly
Start thinking about the comparisonUnlike the conventional channel model – described in power delay profile, the comparison is not straightforward
e.g. For a same speed of Mobile Station, Coherence Time can be quite different … Autocorrelation comparison may not work
Conclude that the Random Process Comparison is challenging
2. Issue
CJK9 , Zhangjiajie, China 5/18
Start viewing the channel simulator asDeterministic System
Various Independent Random Variables are inputs
Let’s draw a block diagram from the ITU-R Channel Model Document
Use the ASIC-verification conceptReference-model (Vector-based) verification
3. Solution
CJK9 , Zhangjiajie, China 6/18
Bubbles are independent Random VariablesG/U are Gaussian N(0,12) and Uniform (0,1) random variables
N is the scenario index LOS indicates LOS or NLOS – binary random variable
3-1. Small-Scale ITU-R Channel Model
CJK9 , Zhangjiajie, China 7/18
Compare Matlab & C code results for the same (deterministic) input for all the intermediate points
Also, compare each point’s probability density function
3-2. Large-Scale ITU-R Channel Model
CJK9 , Zhangjiajie, China 8/18
If mismatch is foundEither C program’s bug
Or Matlab’s bug
Or Unclear ITU-R description
We found many C program bugs (but now corrected) and have a report for the other two cases
We have about 7-8 issuesRefer the annex
3-3. How did we proceed
CJK9 , Zhangjiajie, China 9/18
Already implemented into the SLS
Report to WINNER Group Co-work, maybe?
Contribution (Bug report and C-Source code) to CJK
ITU-R
4. Action Items
CJK9 , Zhangjiajie, China 10/18
Bug report about the Matlab code
5. Annex
CJK9 , Zhangjiajie, China 11/18
5-1. Issue 1
Where(eq.11) of Step 6
ProblemIn Document M.2135
• Delay distribution for B1 NLOS is exponential distribution
In Matlab code• It is uniform distribution• Line number 310 in generate_bulk_par.m
SolutionCorrect the Matlab code
CJK9 , Zhangjiajie, China 12/18
5-2. Issue 2
WhereStep 6
ProblemIn Document M.2135
• There is Zn ~ N(0, )
In Matlab code• use Zn like Zn ~ N(0, 2)
• Line number 295 in generate_bulk_par.m
SolutionCorrect the Matlab code
CJK9 , Zhangjiajie, China 13/18
5-3. Issue 3
WhereStep 6
ProblemIn Document M.2135
• There is no additional process after (eq.12)
In Matlab code• There is a additional process after (eq.12)• Line number 325 in generate_bulk_par.m
SolutionDelete the Matlab code
CJK9 , Zhangjiajie, China 14/18
5-4. Issue 4
WhereTable A1-4 of Step 7
ProblemIn Document M.2135
• As if the scenario is the Indoor Hotspot(InH), there is especial constant C
In Matlab code• We cannot fine the constant C of InH• ConstantCMapping.m
SolutionAdd and Correct the Matlab code
CJK9 , Zhangjiajie, China 15/18
5-5. Issue 5
Where(eq.14) of Step 7
ProblemIn Document M.2135
In Matlab code, wrong usage of (eq.14) as follow
• Line number 383 and 409 in generate_bulk_par.m
SolutionCorrect the Matlab code
CJK9 , Zhangjiajie, China 16/18
5-6. Issue 6
Where(eq.18) of Step 7
ProblemIn Document M.2135
In Matlab code• Wrong (eq.18) w.r.t X1 and Y1
• Line number 387 in generate_bulk_par.m
SolutionCorrect the Matlab code
• Not random variable, but use X1 and Y1 which is already generated
CJK9 , Zhangjiajie, China 17/18
5-7. Issue 7
Where(eq.18) of Step 7
ProblemIn Document M.2135
• There is Yn ~ N(0, )
In Matlab code• Wrong (eq.18) w.r.t Yn ~ N(0, )
• Line number 387 in generate_bulk_par.m
SolutionCorrect the Matlab code
• In Document M.2135 step 7, there is , Yn ~ N(0, ) but Matlab code Yn use like Yn ~ N(0, ()
18/18
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