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ITU-R Channel Model Implementation Issues

ITU-R Channel Model Implementation Issues. Hyun Kyu(HK) Chung ( hkchung@etri.re.kr ) PG707 Chair in TC7, TTA. Document number Zhangjiajia, China 8-10 April 2009. Contents. Introduction. Issue. Solution. Action Items. Annex. 1. Introduction.

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ITU-R Channel Model Implementation Issues

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  1. ITU-R Channel Model Implementation Issues Hyun Kyu(HK) Chung (hkchung@etri.re.kr) PG707 Chair in TC7, TTA Document number Zhangjiajia, China 8-10 April 2009

  2. Contents Introduction Issue Solution Action Items Annex

  3. 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.

  4. 2. Issue • 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 but • Not sure we implement the channel model correctly • Start thinking about the comparison • Unlike 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

  5. 3. Solution • Start viewing the channel simulator as • Deterministic System • Various Independent Random Variables are inputs • Let’s draw a block diagram from the ITU-R Channel Model Document • Use the ASIC-verification concept • Reference-model (Vector-based) verification

  6. 3-1. Small-Scale ITU-R Channel Model • Bubbles are independent Random Variables • G/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

  7. 3-2. Large-Scale ITU-R Channel Model • Compare Matlab & C code results for the same (deterministic) input for all the intermediate points • Also, compare each point’s probability density function

  8. 3-3. How did we proceed • If mismatch is found • Either 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 issues • Refer the annex

  9. 4. Action Items • Already implemented into the SLS • Report to WINNER Group • Co-work, maybe? • Contribution (Bug report and C-Source code) to • CJK • ITU-R

  10. 5. Annex • Bug report about the Matlab code

  11. 5-1. Issue 1 • Where • (eq.11) of Step 6 • Problem • In 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 • Solution • Correct the Matlab code

  12. 5-2. Issue 2 • Where • Step 6 • Problem • In Document M.2135 • There is Zn  ~ N(0, z) • In Matlab code • use Zn like Zn  ~ N(0, z2) • Line number 295 in generate_bulk_par.m • Solution • Correct the Matlab code

  13. 5-3. Issue 3 • Where • Step 6 • Problem • In 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 • Solution • Delete the Matlab code

  14. 5-4. Issue 4 • Where • Table A1-4 of Step 7 • Problem • In 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 • Solution • Add and Correct the Matlab code

  15. 5-5. Issue 5 • Where • (eq.14) of Step 7 • Problem • In Document M.2135 • In Matlab code, wrong usage of (eq.14) as follow • Line number 383 and 409 in generate_bulk_par.m • Solution • Correct the Matlab code

  16. 5-6. Issue 6 • Where • (eq.18) of Step 7 • Problem • In Document M.2135 • In Matlab code • Wrong (eq.18) w.r.t X1 and Y1 • Line number 387 in generate_bulk_par.m • Solution • Correct the Matlab code • Not random variable, but use X1 and Y1 which is already generated

  17. 5-7. Issue 7 • Where • (eq.18) of Step 7 • Problem • In Document M.2135 • There is Yn ~ N(0, sj/7) • In Matlab code • Wrong (eq.18) w.r.t Yn ~ N(0, sj/7) • Line number 387 in generate_bulk_par.m • Solution • Correct the Matlab code • In Document M.2135 step 7, there is , Yn ~ N(0, sj/7) but Matlab code Yn use like Yn ~ N(0, (sj/7)2)

  18. Thank you www.tta.or.kr

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