1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Presentation on Radio Channel Model for Indoor UWB WPAN Environments]
Date Submitted: [08 July, 2002]
Source: [J. Kunisch, J. Pamp] Company [IMST GmbH]
Address [Carl-Friedrich-Gauß-Str. 2, Kamp-Lintfort, Germany]
Voice:[ ], FAX: [ ],
Re: [Call for Contributions on Ultra-wideband Channel Models (02208r1P802-15_SG3a-Call-Contributions-UWB-Channels.doc) 17 April, 2002]
Abstract: [Presentation of 02281r0P802-15_SG3a-IMST-Response-Call-Contributions-UWB-Channel- Models.doc]
Purpose: [For presentation at July 2002 meeting]
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P
J. Kunisch, J. Pamp, IMST GmbH

2. Radio Channel Model for Indoor UWB WPAN Environments
J. Kunisch, J. Pamp
IMST GmbH, Kamp-Lintfort, Germany
Measurements
Model Objectives
Modeling Approach
Results
Summary and Outlook
J. Kunisch, J. Pamp, IMST GmbH

3. Measurement Bandwidth
FCC GHz (Feb 2002)
MEASUREMENTS (2001)
MEASUREMENTS 1-11 GHz (2001)
160 ns (48 m) unique excess delay
J. Kunisch, J. Pamp, IMST GmbH

4. Measurement Procedure
For all Rx positions
For all Tx positions
Rx Antenna:
Mounted on tripod
Omni
~1.5 m height
Rx positions separated ~ 1-2 m
Tx Antenna:
Mounted on positioner
Omni
~1.5 m height
150 x 30 (150 x 8) grid positions
Stepsize: 1 cm (x, y)
For all Tx grid points
Measure
S21
Equal
 transfer functions
DOA/DOD/SAR analysis at Tx position
(n,m)-MIMO analysis (n = 2...3, m >> 1) …
SETUP
J. Kunisch, J. Pamp, IMST GmbH

5. Measurement Environment
Office-to-Office (R131-R132)
Office (R131)
3 Rx positions increasingly shadowed by metal cabinet
3 Rx-Tx pairs  NLOS, (N)LOS, LOS conditions
J. Kunisch, J. Pamp, IMST GmbH

6. Model Objectives
Why is there a need for “ultra-wideband” radio channel models?
What should an UWB model account for?
Example:
Minimum bandwidth
for two-way echo
resolution
J. Kunisch, J. Pamp, IMST GmbH

7. Model Objectives Individual echoes
Dense multipath exponential decay region
Deviation of multipath envelope from exponential decay
Average power delay profile for 30 x 30 measured baseband impulse responses on a 30 cm x 30 cm grid (LOS conditions). Bandwidth = 10 GHz.
J. Kunisch, J. Pamp, IMST GmbH

8. Model Objectives Individual echoes
Trailing multipath behind LOS (regular structure)
Wall reflection trailing multipath
LOS
Plots: |S21(t, r)|
Fading pattern
Coherent superposition: dense multipath
Measured PDP’s as function of distance (LOS conditions).
J. Kunisch, J. Pamp, IMST GmbH

9. Spatial Frequency (l-1) Distance
Model Objectives
Measurement
Plots: |S21|
Spatial Frequency (l-1) Distance
Delay Frequency
J. Kunisch, J. Pamp, IMST GmbH

10. Model Objectives
R.M.S. average of 10 measured transfer functions (non-LOS conditions).
J. Kunisch, J. Pamp, IMST GmbH

11. Model Objectives
Model type: hybrid statistical/quasi-deterministic; “synthetic measurement”
Space-variant complex (baseband) impulse responses / transfer functions
Time-variance by trajectory of receiver
“Simple”
Suited for simulations
J. Kunisch, J. Pamp, IMST GmbH

12. Modeling Approach Proposal: Hybrid modeling
Individual echoes: Quasi-deterministic approach
Dense multipath: Statistical approach
Each individual echo has an associated multipath cluster
J. Kunisch, J. Pamp, IMST GmbH

13. Modeling Approach Generation of individual echoes by virtual sources
Points that apparently emit wave fronts impinging at Rx (corresponding to individual echoes)
Proposal:
Generate individual echoes by fixed set of virtual sources
Rationale:
Introduce coherence if Rx position changes locally
J. Kunisch, J. Pamp, IMST GmbH

14. Modeling Approach Definition of virtual source positions by imaging
Proposal:
Virtual source position definition by imaging
Only a subset of all images of a Tx in a generic room is used
Rationale:
Some strong early echoes indeed correspond geometrically to imaging
Floor reflections
Ceiling reflections
Wall reflections
Captures characteristic dimensions of generic rooms (interarrival times)
Simple and extensible
J. Kunisch, J. Pamp, IMST GmbH

15. Modeling Approach 1. Definition of virtual sources Tx
Example for set of Rx positions Y1 Y0 X0 X1
Images up to order 3 (in x, y, z)
Top view
J. Kunisch, J. Pamp, IMST GmbH

16. Modeling Approach 1. Definition of virtual sources
Positions of potential virtual sources …
Image positions
Index mapping
J. Kunisch, J. Pamp, IMST GmbH

17. Modeling Approach 2. Generation of individual echo parameters
Parameter Profile: Office LOS
J. Kunisch, J. Pamp, IMST GmbH

18. Modeling Approach 2. Generation of individual echo parameters
LOS amplitude: free-space
Distance dependent amplitude of selected individual echoes
Parameter Profile: Office LOS
Other amplitudes: power law
J. Kunisch, J. Pamp, IMST GmbH

19. Modeling Approach 2. Generation of individual echo parameters
Distance to k-th individual echo Delay of k-th individual echo
Power gain of k-th individual echo
direct path other
Complex amplitude gain of k-th individual echo
J. Kunisch, J. Pamp, IMST GmbH

20. Modeling Approach 3. Generation of associated multipath clusters
Proposal:
Cluster amplitudes: Rayleigh distributed
Expectation value ~ exp(-t/g)
Uniform phase
A single cluster realization (per individual echo) for all Rx positions
Rationale:
Doppler behavior: Frequency dependent constraint for maximum wavenumber
Delayed copies
Plot: 20 log10(|S21|); one individual echo + associated multipath cluster
J. Kunisch, J. Pamp, IMST GmbH

21. Modeling Approach 3. Generation of associated multipath clusters
Multipath power values k-th echo, n-th delay bin wrt cluster start
Exponential decay with delay n
Drawn from exponential distribution with parameter
Complex multipath amplitudes, wrt associated individual echo
Phase uniformly distributed
J. Kunisch, J. Pamp, IMST GmbH

22. Modeling Approach
4. Superposition of individual echoes and associated multipath clusters
Complex amplitude gain of k-th individual echo at -th
receiver position
Shift multipath cluster to delay of k-th echo at r-th
receiver position
Basic gain
Delay of k-th individual echo
Normalized baseband impulse response for
delay bin n
receiver position r
individual echo k
J. Kunisch, J. Pamp, IMST GmbH

23. Modeling Approach 5. Filtering and frequency power decay DFT
DFT frequency map
Limitation to bandwidth B
Frequency dependent power decay
J. Kunisch, J. Pamp, IMST GmbH

24. Modeling Approach 6. Observation noise 7. Normalization Discrete
Continuous
Impulse response
Transfer function
J. Kunisch, J. Pamp, IMST GmbH

25. Modeling Approach Hybrid modeling approach:
Individual echoes: quasi-deterministic
Dense multipath: statistical
Individual echoes generated for several receiver positions
Each individual echo: associated with a diffuse multipath cluster
Cluster arrival time: equal to arrival time of associated individual echo
Rayleigh amplitude echoes generated in every bin
Exponential echo power decay law, uniformly distributed phase
Cluster height: set to a certain amount below power of associated individual echo
Decay parameter (unique for all clusters) similar to decay parameter of the overall single cluster
All clusters generated according to the same parameters
Each individual echo: only a single multipath cluster realization generated for all positions
J. Kunisch, J. Pamp, IMST GmbH

26. Results Measurement Model
Average power delay profile for 30 x 30 baseband impulse responses on a 30 cm x 30 cm grid for LOS conditions.
Plots are expected to be “similar”, not identical.
J. Kunisch, J. Pamp, IMST GmbH

27. Results Measurement Model
Color-coded power delay profiles for 150 baseband impulse responses along 150 cm distance almost perpendicular to the Rx-Tx line-of-sight.
Plots are expected to be “similar”, not identical.
Plots: 20 log10(|S21(t, r)|)
J. Kunisch, J. Pamp, IMST GmbH

28. Spatial Frequency (l-1) Distance
Results
Measurement
Plots: |S21|
Spatial Frequency (l-1) Distance
Delay Frequency
J. Kunisch, J. Pamp, IMST GmbH

29. Spatial Frequency (l-1) Distance
Results
Model
Plots: |S21|
Spatial Frequency (l-1) Distance
Delay Frequency
J. Kunisch, J. Pamp, IMST GmbH

30. Results Measurement Model
Example for a single impulse response. A Kaiser-Bessel frequency domain window has been applied.
Plots are expected to be “similar”, not identical.
J. Kunisch, J. Pamp, IMST GmbH

31. Results Measurement Model
Example for a single impulse response (detail). A Kaiser-Bessel frequency domain window has been applied.
Plots are expected to be “similar”, not identical.
J. Kunisch, J. Pamp, IMST GmbH

32. Summary and Outlook
Hybrid modeling approach
Individual echoes: quasi-deterministic
Dense multipath: statistical
Measurement based
General and extensible, e.g.
Virtual sources: more sophisticated algorithms possible.
Various criteria for individual echo selection e.g.
minimum/maximum distance, mirroring order, angle-of-arrival masks, radiation pattern weighting, ….
Selection of individual echo power
radiation pattern weighting, …
Time variance: movement of virtual sources.
MIMO analysis (yet to be verified based on already available measurement data)
J. Kunisch, J. Pamp, IMST GmbH