itu-r channel model implementation issues

1/18CJK9 , Zhangjiajie, China

ITU-R Channel ModelImplementation Issues

Document numberZhangjiajia, China

8-10 April 2009

Hyun Kyu(HK) Chung([email protected])

PG707 Chair in TC7, TTA

CJK9 , Zhangjiajie, China 2/18

Introduction

Issue

Solution

Action Items

Annex


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.


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


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


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


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


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


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


Bug report about the Matlab code

5. Annex


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


5-2. Issue 2

WhereStep 6


• There is Zn ~ N(0, )

In Matlab code• use Zn like Zn ~ N(0, 2)

• Line number 295 in generate_bulk_par.m



5-3. Issue 3

WhereStep 6


• 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


5-4. Issue 4

WhereTable A1-4 of Step 7


• 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


5-5. Issue 5



In Matlab code, wrong usage of (eq.14) as follow

• Line number 383 and 409 in generate_bulk_par.m



5-6. Issue 6



In Matlab code• Wrong (eq.18) w.r.t X1 and Y1



• Not random variable, but use X1 and Y1 which is already generated


5-7. Issue 7



• There is Yn ~ N(0, )

In Matlab code• Wrong (eq.18) w.r.t Yn ~ N(0, )



• 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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