Project: IEEE P802.15 Working Group for Wireless Personal Area Networks
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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks Submission Title: [RF Exposure Rule Under Part 15.255] Date Submitted: [March 2006] Source: [Gary Baldwin, SiBEAM, Freemont, CA] [ [email protected]]

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Project ieee p802 15 working group for wireless personal area networks

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks

Submission Title: [RF Exposure Rule Under Part 15.255]

Date Submitted: [March 2006]

Source: [Gary Baldwin, SiBEAM, Freemont, CA] [[email protected]]

[Abbie Mathew, NewLANS, Westford, MA] [[email protected]]

[Kamran Sayrafian, NIST, Gaithersburg, MD] [[email protected]]

Re: []

Abstract: []

Purpose:[Contribution to 802.15 TG3c at March 2006 plenary in Denver]

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.


Top level document flow chart

Top Level Document Flow Chart

§15.255

§15.255(g)

RF Radiation Exposure

§1.1307(b)

Compliance Actions

§2.1091

Mobile Device

§2.1093

Portable Device

§1.1310

Radiation Exposure

ANSI/IEEE C95.1-1992

Abbie Mathew, NewLANS


Top level document flow chart1

Top Level Document Flow Chart

2.1093(a)

2.1093(b)

2.1093(c)

2.1093(d)

2.1093(d)(1)

2.1093(d)(2)

2.1093(d)(3)

2.1093(d)(4)

§15.255

1.1307(b)(1)

1.1307(b)(2)

1.1307(b)(3)

1.1307(b)(3)(i)

1.1307(b)(3)(ii)

1.1307(b)(4)

§15.255(g)

RF Radiation Exposure

§1.1307(b)

Compliance Actions

§2.1091

Mobile Device

§2.1093

Portable Device

2.1091(a)

2.1091(b)

2.1091(c)

2.1091(d)

2.1091(d)(1)

2.1091(d)(2)

2.1092(d)(3)

2.1092(d)(4)

§1.1310

Radiation Exposure

ANSI/IEEE C95.1-1992

Abbie Mathew, NewLANS


Review of part 15 255 rules

Review of Part 15.255 Rules

1. Limits on Emission

  • Average power density ≤ 9 W/cm2 at 3 m

    • Translates to EIRP of 40 dBm in the far field

  • Peak power density ≤ 18 W/cm2 at 3 m

    • Translates to an EIRP of 43 dBm in the far field

  • Total peak transmitter power ≤ 500 mW

3 m is in the far field for small apertures

2. Limits on Human Exposure to RF Emissions

  • Information contained in OET Bulletin 65

  • Enables an applicant to make a reasonably quick determination as to whether a proposed or existing facility is in compliance with the limits

3. Transmitter Identification

  • Within any 1 second interval of signal transmission, each transmitter must transmit a transmitter identification at least

Abbie Mathew, NewLANS


Mobile portable devices 2 1091 2 1093

Mobile & Portable Devices§2.1091 & §2.1093

Abbie Mathew, NewLANS


Mobile portable devices 2 1091 2 10931

Mobile & Portable Devices§2.1091 & §2.1093

Note

For mobile devices, warning labels can be used for controlled and uncontrolled exposures

Abbie Mathew, NewLANS


Mobile portable devices 2 1091 2 10932

Mobile & Portable Devices§2.1091 & §2.1093

Unclear Distinction

If the device usage does not allow easy classification as either mobile or portable then applicants are responsible for determining minimum distances for compliance for the intended use and installation of the device based on power density

Abbie Mathew, NewLANS


Actions for non compliance

Actions For Non-Compliance

Abbie Mathew, NewLANS


Definitions

Definitions

  • Occupational/Controlled Exposure

    • Work related or transient in nature

    • Person must be fully aware of exposure

    • Person must have knowledge to control and limit exposure

    • Require RF exposure training

    • High exposure limits apply

  • General Population/Uncontrolled Exposure

    • Apply to all consumer devices

    • No knowledge of exposure is required

    • More restrictive exposure limits apply

Abbie Mathew, NewLANS


Definitions1

Definitions

  • Maximum Permissible Exposure (MPE): The plane-wave equivalent power density to which a person may be exposed without harmful effect and with an acceptable safety factor

  • Power density: Power per unit area normal to the direction of propagation, expressed in mW/cm2 or μW/cm2

Abbie Mathew, NewLANS


Absolute mpe limits for different frequencies

Absolute MPE Limits for Different Frequencies

Abbie Mathew, NewLANS


Spatial averaging

Spatial Averaging

  • These exposure guidelines apply to power densities that are spatially averaged over the body dimensions*

  • Local values of exposures that exceed the stated MPEs may not be related to non-compliance if the spatial average of RF fields over the body does not exceed the MPEs

  • Further discussion of spatial averaging as it relates to field measurements can be found in OET-65 and in the ANSI/IEEE and NCRP reference documents

* This information is as of March 2006. Spatial averaging window size is under active rulemaking process. Please direct further inquiries to FCC

Kamran Sayrafian, NIST


Partial body exposure

Partial Body Exposure

  • Partial-body exposure results when RF fields are substantially non-uniform over the body

  • Fields that are non-uniform over volumes comparable to the human body may occur due to highly directional sources, standing-waves, re-radiating sources or in the near field

  • Limits for localized absorption are based on recommendations of both ANSI/IEEE and NCRP

Kamran Sayrafian, NIST


Temporal averaging

Temporal Averaging

  • Exposures, in terms of power density, may be averaged over certain periods of time with the average not to exceed the limit for continuous exposure

  • FCC has not explicitly adopted limits for peak power density (guidance on these types of exposures can be found in Section 4.4 of the ANSI/IEEE C95.1-1992 standard)

Average (Temporal) Power

The time-averaged rate of energy transfer

Averaging Time

The appropriate time period over which exposure is averaged for purposes of determining compliance with RF exposure limits.

Continuous Exposure

Exposure for durations exceeding the corresponding averaging time

Kamran Sayrafian, NIST


Time averaged mpe limits 1 1310

Time-Averaged MPE Limits §1.1310

  • Controlled exposure applies in situation where a person is exposed as a consequence of his employment, provided he is fully aware of and can exercise control over his exposure.

  • Uncontrolled exposure applies in situation where the general public may be exposed, or when a person is exposed as a consequence of employment may not be fully aware of the potential for exposure or cannot exercise control over his exposure.

Kamran Sayrafian, NIST


Time averaged mpe limits

Time-Averaged MPE Limits

In general, the sum of the products of the exposure levels and the allowed times for exposure must equal the product of the appropriate MPE limit and the appropriate time-averaging interval

where

Kamran Sayrafian, NIST


Time averaging

30 mW-min/cm2

5 mW/cm2

time

6 min (Sliding Window)

Time Averaging

  • MPE limits adopted by the FCC aretime-averaged exposure limits

  • This means that the exposure duration should be taken into account

  • Especially relevant for cases of occupational/controlled exposure

Example

The relevant interval for time-averaging for occupational/controlled exposures is six minutes as shown below

Kamran Sayrafian, NIST


Time averaging example for controlled environments

15 mW/cm2

30 mW-min/cm2

30 mW-min/cm2

10 mW/cm2

time

3 min

3 min

6 min

6 min

Time AveragingExample for Controlled Environments

  • During any given six-minute period a worker could be exposed to two times the applicable power density limit for three minutes as long as he or she were not exposed at all for the preceding or following three minutes or

  • He/She could be exposed at three times the limit for two minutes as long as no exposure occurs during the preceding or subsequent four minutes, and so forth.

Kamran Sayrafian, NIST


Time averaging provision for general population uncontrolled environments

Time Averaging Provision For General Population/Uncontrolled Environments

  • For devices intended for use by consumers in general population/uncontrolled environments time-averaging provisions may not be used in determining typical exposure levels (§2.1091(d)(2)). However, source-based’ time-averaging based on an inherent property or duty cycle of a device is allowed.

In contrast to "user-based" or “activity-based”, source-based time-averaging does not consider user behavior when calculating the time-average. For example, it cannot be assumed that users will step in/out of exposure for certain periods of time.

Kamran Sayrafian, NIST


Source based time averaging

Source-Based Time Averaging

  • Example for source-based time-averaging is the determination of exposure from device that uses digital technology such as a time-division multiple access (TDMA) scheme for transmission of a signal. In general, maximum average power levels must be used to determine compliance.

  • e.g. A GSM handset can transmit in one out of eight possible time slots. This is an inherent property of the source and it does not depend on the user behavior.

Kamran Sayrafian, NIST


Ieee perspective

IEEE Perspective

IEEE Standard C95.1, 1999 Edition

  • Recommendation to prevent harmful effects in human beings exposed to electromagnetic fields in the frequency range from 3 KHz to 300 GHz

  • Apply to exposures in controlled as well as uncontrolled environments

Kamran Sayrafian, NIST


Mpe limits controlled uncontrolled environments

MPE Limits (Controlled & Uncontrolled Environments)

  • Note: f is the frequency in MHz.

  • Also, the averaging time window size is subject to change in the upcoming IEEE draft

For the frequency of 60GHz, the averaging time is approximately 1.137 minutes

* This information is as of March 2006

Kamran Sayrafian, NIST


Partial body exposures

Partial Body Exposures

  • Compliance for the MPE is determined from spatial averages of power density over an area equivalent to the vertical cross-section of the human body (projected area) at a distance no closer than 20 cm from any object *.

  • For partial body exposure (i.e. all parts except the eyes and the testes), limits on the peak value of the power density exist.

* This information is as of March 2006. Spatial averaging window size is subject to change in the upcoming IEEE draft

Kamran Sayrafian, NIST


Maximum peak value of the mean squared field strength

Maximum Peak Value of the Mean Squared Field Strength

Kamran Sayrafian, NIST


Summary as of march 2006

Summary (as of March 2006!)

1 These numbers are as of March 2006. Please watch for possible changes in the upcoming IEEE draft

2 This information is as of March 2006. Spatial averaging window size is under active rulemaking process. Please direct further inquiries to FCC

Kamran Sayrafian, NIST


Acknowledgement

Acknowledgement

We would like to express our gratitude to Mr. Ed Mantiply (from the Federal Communications Commission) for his time in answering our questions and his review of the materials in this presentation.

Kamran Sayrafian, NIST


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