1. A Flexible Doppler Behavior Model IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: S802.16m-07/140r2 Date Submitted: 2007-07-18 Source: Shuangquan Wang, Xiaodong Wang NEC Laboratories America, Inc. Email: {shuangquan, wangx}@nec-labs.com Mohammad.Madihian@necam.comshuangquanwangx}@nec-labs.com Mohammad.Madihian@necam.com Mohammad Madihian NEC Corporation of America Venue: IEEE 802.16 Session #50 San Francisco, CA, USA Base Contribution: C802.16m-07/140r1 Purpose: Discussion and Approval Notice: This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the Source(s) field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and.http://standards.ieee.org/guides/bylaws/sect6-7.html#6http://standards.ieee.org/guides/opman/sect6.html#6.3 Further information is located at and.http://standards.ieee.org/board/pat/pat-material.htmlhttp://standards.ieee.org/board/pat

2. 2 Doppler Behavior Modeling Problems and Proposed Solution Problems: –Power azimuth spectrum (PAS), antenna pattern, angular distribution are not clearly defined or separated. –Laplace distribution is used to model the PAS and the angular distribution Laplace angular distribution + antenna pattern in Figure 2 Laplace PAS! No simple closed-form solutions for spatial correlations, which are calculated by the numerical integration, quantized-angle summation, etc. No simple closed-form expressions for the temporal autocorrelation and the Doppler spectrum. –Figure 6 is incomplete and the mean angle of departure (AoD) is not correctly defined. Proposed Solution: –Use von Mises distribution to model the PAS Simple closed-form expressions for spatial correlations, temporal autocorrelation and Doppler spectrum Includes Jakes model as a special case.

3. 3 Non-isotropic Scattering Environments Cluster of scatterers around the MS Elliptical Model Non-isotropic scattering

4. 4 Directional Antennas

5. 5 Power Azimuth Spectrum (PAS) Non-isotropic Scattering Environments Directional Antenna Non-uniform power azimuth spectrum (PAS) in most cases In the current draft, PAS, antenna pattern, angular distribution are not well defined or separated. We made clear definitions in IEEE C802.16m-07/140r1.

6. 6 von Mises Distribution Also known as the circular normal distribution Plays a prominent role in statistical modeling and analysis of angular variables PAS is von Mises! von Mises

7. 7 An Example Antenna Pattern (Figure 2) Angular distribution (elliptical model) von Mises PAS, not Laplace!

8. 8 Comparison between von Mises and Laplace von MisesLaplace Doppler spectrum includes Jakes? YES (flexible simulation) NO Simple closed-form expressions for both spatial and temporal correlations? YES (easy correlation computation) NO In IEEE C802.16m-07/140r1, we propose using von Mises to model the angular distribution.

9. 9 with von Mises, we can do … With Laplace, it is difficult to compute the spatial correlations. However, with von Mises, there are simple formulas. In IEEE C802.16m-07/140r1, we proposed the text change. With Laplace, it is impossible to include the Jakes model by changing the parameters. However, with von Mises, it is easy. This helps us to simulate Jakes and non-Jakes Doppler spectrum in a uniform frame.

10. 10 Mean AoA and AoD Definitions The mean AoD (AoA) should not be defined with respect to the BS (MS) array broadside. Otherwise, the BS (MS) array correlation will be fixed for any drop. The new figure is shown in IEEE C802.16m-07/140r1

11. 11 Answers to Some Issues Raised Regarding Our Contribution in the Ad Hoc Meeting, 7/17 Support by experimental data –Laplace, wrapped Gaussian (used in the WINNER model), and von Mises are all approximations to the real propagation environment –The well-known elliptical scattering model in [12], its AoA and AoD distributions (Fig. 6a of [12]) are not Laplacian, but closer to von Mises or wrapped Gaussian.

12. 12 Contd Concern that the proposed model may not match the WINNER model –In the WINNER model, the wrapped Gaussian is used to model the AoA and the AoD. –The von Mises distribution is approximately equal to the wrapped Gaussian if the angular spread is small. (This is true for the wideband systems; please refer to Tables 8-15 for the angular spreads.)

13. 13 Contd Bottomline –Laplacian, wrapped Gaussian (WINNER model), and von Mises are some kind of approximations to the real propagation environment. –In the system-level simulation, the shape may not be important for given angular spreads since we will do the geometrical averaging to evaluate the performance. –This is the reason for the difference between SCM and WINNER (3GPP SCM has the Laplace, and WINNER has the wrapped Gaussian.) Our contribution –includes the uniform as a special case, making it possible to simulate Jakes' and non-Jakes' Doppler spectrums in a unified frame. –provides the closed-form expressions for the spatial and temporal correlations, which is a highly desired feature for the correlation-based method (not needed for the ray-based method).

14. 14 Implementation Issue If the method (in C80216m-07_141r1.pdf) works, can just replace the Laplace distribution with the von Mises and calculate those angles. There are other simple and more accurate methods, e.g., the spectrum representation method

15. 15 Procedural Suggestion In the ad hoc meeting on 7/17, the consensus was that the group could not accept nor reject our contribution due to the previous issues Therefore, the ad hoc meeting suggested –to have a revised text making this as an optional evaluation methodology –to address the previously shown issues Having shown our answers, our suggestion to TGm is –to adopt the contribution as an optional eval method –to have the authors of the contribution provide revised text by the time the Editor starts to put together all the resolved comments.