24-Aug-04 Ulrich G. Schuster, ETH Zurich 1 doc.: IEEE 802.15-04-0447-00-004a Submission Project: IEEE P802.15 Working Group for Wireless Personal Area Networks ( Project: IEEE P802.15 Working Group for Wireless Personal Area Networks ( WPANs WPANs ) ) Submission Title: [Indoor UWB Channel Measurements from 2 GHz to 8 GHz] Date Submitted: [24 August, 2004] Source: [Ulrich G. Schuster] Company [Communication Technology Laboratory, ETH Zurich] Address [Sternwartstr. 7, ETH Zentrum, 8092 Zürich, Switzerland] Voice:[+41 (44) 632 5287], FAX: [+41 (44) 632 1209], E-Mail:[[email protected]] Re: [IEEE 802.15.4a Channel Modeling Subcommittee Call for Contributions] Abstract: [This presentation describes UWB channel measurements from 2 to 8 GHz, conducted in two office buildings at ETH Zurich, Switzerland. Measurements were taken for LOS, OLOS and NLOS settings in a corridor and a large entrance lobby, with transmitter-receiver separations ranging from 8 m to 28 m] Purpose: [To provide additional data for the proposed generic 802.15.4a channel model and discuss some of the modeling aspects used in the generic model] Notice: This document has been prepared to assist the IEEE P802.15. 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 P802.15.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
24-Aug-04
Ulrich G. Schuster, ETH Zurich1
doc.: IEEE 802.15-04-0447-00-004a
Submission
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANsWPANs))
Submission Title: [Indoor UWB Channel Measurements from 2 GHz to 8 GHz]Date Submitted: [24 August, 2004]Source: [Ulrich G. Schuster] Company [Communication Technology Laboratory, ETH Zurich]Address [Sternwartstr. 7, ETH Zentrum, 8092 Zürich, Switzerland]Voice:[+41 (44) 632 5287], FAX: [+41 (44) 632 1209], E-Mail:[[email protected]]Re: [IEEE 802.15.4a Channel Modeling Subcommittee Call for Contributions]
Abstract: [This presentation describes UWB channel measurements from 2 to 8 GHz, conducted in twooffice buildings at ETH Zurich, Switzerland. Measurements were taken for LOS, OLOS and NLOSsettings in a corridor and a large entrance lobby, with transmitter-receiver separations ranging from 8 m to28 m]
Purpose: [To provide additional data for the proposed generic 802.15.4a channel model and discuss someof the modeling aspects used in the generic model]Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis fordiscussion and is not binding on the contributing individual(s) or organization(s). The material in thisdocument is subject to change in form and content after further study. The contributor(s) reserve(s) theright to add, amend or withdraw material contained herein.Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEEand may be made publicly available by P802.15.
Indoor UWB Channel Measurementsfrom 2 GHz to 8 GHz
Ulrich Schuster and Helmut Bolcskei,
Swiss Federal Institute of Technology (ETH), Zurich
assumes specular reflections — there are distinct, frequencyindependent propagation paths.
Assumption might not hold for UWB Channels!
Instead, we simply consider the discrete time LTI system h[n]. There is nonotion of resolvable paths; the model is still sufficient for system analysisand design.
Model Selection using Akaike’s Information Criterion (AIC)
A measure for the difference of distributions is relative entropy. AIC is anunbiased estimate of the relative entropy difference between acandidate model and the true distribution, given as
−2 log qi(y | Θ(y)) + 2K
with qi(· |Θ) the parameterized PDF of candidate model i, i.i.d. datavector y and ML parameter estimate Θ(y).
From this, it is possible to compute the probability for each candidatemodel of providing the best fit, called Akaike weight wi.
Advantage: no ambiguities due to confidence level selection, test powerand binning.
Conclusion: there is not single true model, but Rayleigh still seems to bean appropriate and convenient choice for UWB, except for the first tapsin each cluster.
Mean delay and delay spread often used to characterize timedispersiveness of the channel. They are not the most general description.
Estimates can be computed as
τ =L∑
l=1
h[l]l mean delay
s =
√√√√ L∑l=1
(l − τ)2h[l] delay spread
where the h is the magnitude of the power normalized impulseresponse. Mean and standard deviation can now be computed over allsmall scale positions on the virtual array.
Our discrete time model does not fit this framework⇒ cannot extract allparameters since there are no rays. Using the methodology presented byBalakrishnan in doc. 802.15-04-0342-00-004a, we computed
• Cluster decay coefficient Γ
• Inter-cluster decay coefficient γ
• Cluster interarrival time Λ
The model fit is not always satisfactory, as can be seen in the followingplots. We only extracted S-V parameters for the LOS scenarios, whereclusters were observable.
The simplest pathloss model consists of a single slope with exponentialdecay
10 log P (d) = G0 + 10ν logd
d0, d ≥ d0
with d0 = 1m, an arbitrarily chosen reference distance, and G0 thereference loss at d0.
Our measurements are not targeted at pathloss extraction; only in threesettings enough large scale data points are available to yield crudeestimates, as can be observed from the following scatter plots.