USE OF TRANSMIT POWER AND GPS DATA TO BETTER CHARACTERIZE MOBILE PHONE

EXPOSURE FOR EPIDEMIOLOGIC STUDIES J.J. Morrissey, Motorola, Ft. Lauderdale FL USA

Figure 1. A) [from ref 9]: Tx Power associated with calls (in good vs.

poor coverage) made on a US 1900 MHz GSM network. B)

Discontinuous Transmission (DTx) showing truncated transmission

during periods of no speech.

0.0001

0.001

0.01

0.1

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Time (in seconds)

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Mobile Phone Transmit Power

Average Transmit Power

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Figure 3. [from ref 9]: Upper panel: Average transmit power levels

from volunteers (n = 20) from different locations. Some of the

difference may reflect the use of 850 / 1900 MHz vs. 900 / 1800

MHz, global roaming agreements, handoff characteristics (traffic

management), indoor network deployments, driving habits, home

use, etc. Lower panel: Average error from different site locations

associated with recall of minutes performed 1-2 weeks following use.

Recall Error

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E.N.M.R.Cingular / ATT T-Mobile

Although factors such as the type of handset, distance / orientation

to the head, talking / listening status, and operating frequency band

will influence transmit power, these factors are almost impossible to

follow prospectively, or reconstruct retrospectively. Accessing

transmit power from the network operator would also be difficult.Figure 4 shows the complexity of network coverage in the US, taking

Albuquerque New Mexico as a simple example. In this case, two tier

1 carriers and one small regional carrier support GSM network

coverage and have roaming agreements to support traffic and

network needs. The situation is more complex in most parts of the

US, with over 80 different regional carriers. The solution has been to

record and save transmit power data on modified mobile phones.

Results & Discussion: The present study hopes to leverage A-GPS/ E-OTD technology mandatory in mobile phones sold in the USA to

simultaneously follow transmit power and position / location during

use in a format that can be downloaded to Google Earth maps.

While current technology has an associated error of ~10-20 meters

and is not always able to fix position inside buildings, the information

should be sufficient to determine whether the user is indoor vs.

outdoor, driving vs. stationary, general location, and talking vs.

listening. Correlations between these situations and transmit power

(e.g., ~exposure) will be evaluated.

Figure 4. Overlapping coverage maps in Albuquerque New MexicoAbstract: A level of public concern has been raised over possible

health consequences due to low-level radiofrequency (RF) exposure

from mobile phones. In response, the World Health Organization(WHO) has developed a research agenda [1] and assembled a

publicly-accessible literature database [2] to guide global funding and

research. The objective is to develop a sufficient body of data for a risk

assessment, particularly for those scheduled by the International

Agency for Research on Cancer (IARC) for cancer endpoints and by

the WHO for non-cancer endpoints. In response to these

recommendations, several epidemiologic studies have been initiated.

The largest is a case-control study (INTERPHONE) involving

researchers from 13 different Countries and coordinated by IARC [3].Other epidemiologic studies have also investigated similar correlations

[4-6]. A large prospective cohort study (COSMOS) and a case control

study of children (CEFALO / INTERPHONE KIDS) have also been

initiated. These are essential studies, although significant challenges

exist in determining retrospective / prospective individual RF exposure.

The following study leverages available technology on mobile phones

sold in the USA to provide more accurate mobile phone exposure data.

Background: A significant challenge for mobile phone epidemiologic

studies has been reconstructing retrospective (or prospective)individual exposure from questionnaire data. In addition to recall and

selection bias [7-9], the influence of normal variations inherent with

wireless communication is not well established. Dynamic power control

(Figure 1a), discontinuous transmission (Figure 1b), base station

architecture, signal penetration, and signal propagation (e.g., terrain)

can all have significant influence on the level of exposure.

Using previously developed software modified mobile phones that

record real time transmit power during use, reports [8, 9] suggest a

large intra- and inter-individual variability in RF exposure. These

studies also identified significant differences in average transmit powerbetween users in different geographical locations (Figure 3).

A recent FCC E-911 Order [10] has directed all new mobile phone

handsets sold in the USA to provide position / location information in

the form of A-GPS or E-OTD [11] to assist emergency response teams

during E-911 calls. Although the purpose of this Order was to identify

location at the instant of an E-911 call, the resulting functionality it has

prescribed can be leveraged to reconstruct simultaneous transmit

power and movement through the environment.

References

[1] http://www.who.int/peh-emf/research/agenda/en/index.html[2] http://www.who.int/peh-emf/research/database/en/index.html

[3] Cardis et al Eur J Epidemiol (2007)

[4] Hardell L, Carlberg M, Mild KH. Environ Res. (2005) 100(2):232-41

[5] Muscat et al. Neuroepidemiol (2006) 27:55-56; Neurology (2002)

58:1304-1306

[6] Inskip et al. New England J. Med (2001) 344:79-86

[7] Vrijheid et al. J Exposure Sci Environ Epidemiol (2006) 16:371-384

[8] Erdreich et al. Radiation Research (2007) 168:253-261.

[9] Morrissey JJ. Rad Prot Dos (2007) 123:490-497[10] FCC Report & Order 94-102 (Sept 1996 + sub. rev. - 2005)

[11] Position-location for GSM networks by measuring difference in

signal arrival time from different towers (i.e., triangulating position)

World Wide Mobile Phone Use

0

500

1,000

1,500

2,000

2,500

1Q03

2Q03

3Q03

4Q03

1Q04

2Q04

3Q04

4Q04

1Q05

2Q05

3Q05

4Q05

1Q06

2Q06

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4Q06

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Su

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GSM

WCDMA

CDMA

iDEN

From: GSM Association http://www.gsmworld.com/news/statistics/index.shtml

Product Frequency (MHz) Power (W) Field strength

@ 1 m (V/m)

Paging transmitters 49 250 110 [i]

Mobile radios 138–470 25 35a

Hand-held transceivers 27, 49, 138–470 5 15a

Police/ambulance 138–900 10–100 22–70a

Commercial BW and Public Safety

(mobile)

698-806 1-2

Wireless LANs 912, 2400, 5GHz 0.1 -0.25 2.2 – 3.1

Wireless personal digital assistants 896–940 2 10

Radio modems 896–901 10 22

Cellular telephones[ii] 800–900 0.6 5.4

Personal communications satellite

telephones

1610–1626.5 1 7

Licensed PCS equipment 1850–1910 1 7

BWA (3G / IMT, WiMAX mobile) 2.5 -2.689 1-2

BWA (Fixed)) 3650-3700 1-25

Public Safety 4940-4990 2

CISPR 11, CISPR 22 [iii] 25–1000 0.04 10-6

0.0014 [iv]

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Time (in seconds)

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Mobile Phone Transmit Power

• Frequency band (e.g., 900, 1800 MHz, 2.2 GHz)

• Air interface (e.g., GSM, WCDMA, Tetra)

• Network (e.g., density, traffic management)

• Pathloss variables (e.g, fades, shadows, amplification)

• Application (e.g., voice, data)

• Multiple transmitters (e.g., GSM + WiFi + BT)

• User anatomy (e.g, head, hand size)

• Handset variables (e.g., slide, antenna type / position, size,

clam v bar)

• Antenna performance

• Human factors (e.g., age, gender, occupational trends)

• Etc …

Recall Error

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Country Time period Budget (M )

Australia 2004-2009 1.5

Denmark 2004-2008 4.0

Finland 2004-2007 1.5

Germany 2002-2007 17.0

UK: MTHR 1 (8.8 ML) MTHR 2

2002-2008 2007-2012

10.8 est 11.25

France 2006-2010 4.8

Korea 2005-2010 10.8

Netherlands 2006-2014 16.6

Switzerland 2006-2010 3.2

USA/NTP 2005-2010 18.0

Total 99.45 M = $130 million USD

+ Japan, China, EU 7th Framework, etc.

National Funding Programs (low-level health effects)

http://www.who.int/peh-emf/research/database/en/index.html

Total Citations: 3234

Mobile Phone studies: 968

Reviews: 848