Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Channel characterization proposed for Body Area Network] Date Submitted: [15 January 2008] Source: [Friedman Tchoffo Talom, Christophe Delaveaud, Julien Keignart, Serge Bories, Laurent Ouvry] Company: [Laboratory of Electronics and Information Technologies (LETI)] Address: [CEA-Leti - Minatec, 17 rue des martyrs, 38054 Grenoble Cedex 9, FRANCE] Voice: [+33-438-789-388], FAX: [ +33-438-786-586] E-Mail: [laurent.ouvry@cea.fr] Abstract: [This document describes a Channel characterization proposed for Body Area Network (BAN).] Purpose: [To describe all the elements involved in the channel characterization proposed for Body Area Network (BAN).] 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.

Channel characterization proposed for Body Area Network (BAN) Friedman Tchoffo Talom, Christophe Delaveaud, Julien Keignart, Serge Bories, Laurent Ouvry Laboratory of Electronics and Information Technologies (LETI) France

Body surface channel characterization The specifications of the body surface characterization to be conducted are the following : Frequency band of interest Used Antenna Measurements type (Frequency or Time domain) Considered environments Scenario adopted (antenna position) Parameters extracted from the characterization

Frequency band of interest The characterization will be done on a large frequency band : 400MHz – 6 GHz For practical reasons, the whole band is subdivided into 3 sub bands. - Used antennas have to be miniaturized according to the wavelength. - Design of antennas for all the band (400MHz – 6 GHz) is not very easy. The following subdivision is adopted : 400 MHz – 1.2 GHz 1.2 GHz – 2.5 GHz 2.5 GHz – 6 GHz

Used antennas In such a characterization, the antennas are key elements. As there are closed to the body, their characteristics are necessarily modified [1]: Radiation patterns Impedance matching Gain This has to be clearly understood and considered in the study. We will specifically address this point in the study by simulation and measurements for all the considered sub bands.

Measurements type Frequency domain Characteristics: Drawbacks: Frequency sweep Good dynamic Amplitude and phase are obtained Only one device  easy calibration Time domain response obtained using IFFT Time sweep : ~1 s Sensitivity : -100 dBm TX RF Components RX RF Components Vector Network Analyzer Port 1 Port 2 Frequency sweep Receiver IF S21 parameter Drawbacks: Duration of the measurements Non stationary Measurements are impossible Compromise: Resolution & dynamic VS speed High distance measurement need long RF cable Post processing

Measurements type Time domain Characteristics: Drawbacks: Generation of very short pulses Real time measurements Signal directly in time domain Used of two instruments (trigged using a cable) Sensitivity : ~ -50dBm TX RF Components RX RF Components Periodic Pulse Generator Digital Oscilloscope Trig. Drawbacks: Specific Instruments are needed Limited measurement dynamic Narrow band measurement impossible Post processing @ Emission @ Reception Real time scope Analog band: 12 GHz 40 Gech/s or Pulse generator

Measurements type Both measurements types will be performed. Frequency domain measurements: Scenario with a need of high dynamic Directly extract path loss value Time domain measurements: Simultaneously obtained different scenario characterization Directly extract delay spread Evaluate non stationary configuration

Considered environments Four environments are considered : Anechoic chamber  No multipath Indoor office Contribution of multipath to the link Indoor corridor Contribution of multipath to the link Distribution of multipath different from indoor office case Anechoic chamber without absorber on the floor Outdoor like propagation Contribution of path coming from the floor

Adopted scenarios The scenarios adopted for the measurement are all body surface to body surface (should feed CM3 [1]). B A C E F G D There are six LOS and NLOS scenarios. Sc1 : Propagation around the head (A-B) Sc2 : Propagation from waist to head (E-A/B) Sc3 : Propagation from waist to torso (E-C) Sc4 : Propagation from waist to hand (E-F) Sc5 : Propagation from waist to back (E-D) Sc6 : Propagation from waist to ankle (E-G) For all these scenarios, the subjects (~5 persons) will stand up during measurement.

Adopted scenarios B A C E F G D These scenarios are chosen because they represent four meaningful configurations in the BAN context. Config. 1 : Link with a “coordinator” at the belt Config. 2 : Link over a short range ( < 1 meter in air) Config. 3 : Link over medium range ( > 1 meter in air) Config. 4 : Link affected by non stationarities (hand or feet movements) Sc1 Sc2 Sc3 Sc4 Sc5 Sc6 Config. 1 X Config. 2 Config. 3 Config. 4

Delay spread parameters : Parameters extracted from the characterization Antennas characteristics Effect/ Radiation pattern - Impedance Matching – Gain (use of different antennas and orientations, details TBD) Path loss parameters: Friis case: General case: Delay spread parameters : mean excess delay : RMS delay spread : : power delay profile for an impulse response

Conclusion LETI will perform on body to on body BAN measurements. Characteristics of the measurements Band : 400 MHz – 6 GHz Time and frequency domain Four environments only the human body effect on propagation : anechoic chamber with the effect of the floor : anechoic chamber without absorber on the floor with channel effects (multipath) : corridor and office Six scenarios Various persons : ~ 5 subjects Parameters extracted path loss, shadowing delay spread (optionally : non stationarity analysis) The results and models obtained from these measurements will hopefully be available for March or May meetings.

Reference [1] Kamya Yekeh Yazdandoost, “Channel Model for Body Area Network (BAN) ”, IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs), Jan. 2008, doc IEEE P802.15-08-0033-00-0006