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IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY, VOL. 52, NO. 3, AUGUST 2010 737

A New Method of Interference Evaluation Betweenan Ultrawideband System and a Wireless LAN Using

a Gigahertz Transverse Electromagnetic CellShinobu Ishigami , Member, IEEE , Masashi Yamada, Haruki Kamiya, Kaoru Gotoh , Member, IEEE ,

Yasushi Matsumoto , Member, IEEE , and Masamitsu Tokuda , Fellow, IEEE

Abstract—Anew method of evaluating theinterference to a wire-less LAN with a built-in antenna using a gigahertz transverse elec-tromagnetic (GTEM) cell is proposed. The GTEMcell can generatea wideband electromagnetic field from dc up to several gigahertzwith a high spatial uniformity in the cell. This is advantageous forconfiguring a system for a victim receiver with a built-in antenna.Furthermore, the strength of the interfering electromagnetic fieldto be applied to the victim can be directly calculated from a givenequivalent isotropically radiated power and propagation distance

of the interfering signal in free space. It should also be noted thata GTEM has a conductive enclosed structure that is much smallerthan typical anechoic rooms. As an example of use of the method,the evaluation of interference between an IEEE 802.11a wirelessLAN and a direct-sequence spread-spectrum UWB was conducted.Investigations are further conducted on the effects of the UWB sig-nal on the throughput of the victim wireless LAN system on thebasis of bit error rate estimated with measurement results of theamplitude probability distribution of the UWB signal.

Index Terms—Electromagnetic interference, gigahertz trans-verse electromagnetic (GTEM), ultrawideband (UWB) system,wireless LAN.

I. INTRODUCTION

ULTRAWIDEBAND (UWB) technology comprises wire-

less systems that transmit signals at a high transmis-

sion rate of 100–480 Mb/s with a low-power spectrum den-

sity at distances of a few meters. The Federal Communications

Commission (FCC) has allocated the frequencies from 3.1 to

10.6 GHz and from 22 to 29 GHz to the unlicensed use of UWB

technology [1]. The problem of interference between UWB sys-

temand existingwirelessLANs or other wireless systems should

be carefully considered, because UWB systems are used over

the frequency range allocated to existing wireless systems from

Manuscript received December 7, 2008; revised August 16, 2009; acceptedJanuary 18, 2010. Date of publication May 6, 2010; date of current versionAugust 18, 2010. This work was supported in part by the Ministry of InternalAffairs and Communications of Japan.

S. Ishigami, K. Gotoh, and Y. Matsumoto are with the National Institute of Information and Communications Technology, Tokyo 184-8795, Japan (e-mail:[email protected]; [email protected]; [email protected]).

M. Yamada was with the Musashi Institute of Technology, Tokyo 158-8557,Japan. He is now with Sony Corporation, Tokyo 108-0075, Japan (e-mail:[email protected]).

H. Kamiya was with the Musashi Institute of Technology, Tokyo158-8557, Japan. He is now with Canon Inc., Susono-shi 410-11, Japan(e-mail: [email protected]).

M. Tokuda is with the Tokyo City University (old Musashi Institute of Tech-nology), Tokyo 158-8557, Japan (e-mail: [email protected]).

Digital Object Identifier 10.1109/TEMC.2010.2042959

3.1 to 10.6 GHz. Therefore, there have been many studies con-

cerning the interference of UWB systems to wireless LANs

[2]–[8]. The degradation of performance of the IEEE 802.11a

wireless LAN caused by UWB transmitters was evaluated by a

numerical method in [2], [5], [6], and [8]. Ohno et al. [3] pro-

posed an interference mitigation technique for UWB systems

using the result of the interference to the wireless LAN. Exper-

imental results to quantify the impact of a UWB system on theperformance of an IEEE 802.11a wireless LAN operated in a

line-of-sight (obstacle-free outdoor) environment were reported

in [4]. Experimental results for the throughput degradation of

an IEEE 802.11b wireless LAN and Bluetooth networks caused

by the interference of a UWB system in an anechoic chamber

were presented in [7].

Evaluations of interference between wireless communication

systems are usually performed with all measuring apparatuses

connected or in an anechoic chamber. However, it is difficult

to connect a wireless transceiver (receiver) equipped with a

built-in antenna to the measuring apparatus. Moreover, it is also

difficult to apply interference only to the receiver under test

(“victim receiver”) without interfering with the other receivers,such as the access point of the wireless LAN, in the case of an

evaluation in an anechoic chamber.

Therefore, we proposed a new method of evaluating the in-

terference to such a victim receiver, using a gigahertz trans-

verse electromagnetic (GTEM) cell, which is applicable to a

frequency of several gigahertz [9].

In this paper, the results of the evaluation of the interfer-

ence between a direct-sequence spread-spectrum UWB (DS-

UWB) system and an IEEE 802.11a wireless LAN by a GTEM

cell using the proposed method are reported. Furthermore, the

amplitude probability density (APD) of the DS-UWB signal

was measured at each subcarrier frequency of the victim IEEE802.11a signal. The measured APDs were used to calculate the

throughput of the IEEE 802.11a wireless LAN. These results

were compared with the throughputs measured by the proposed

method.

II. EVALUATION OF THE GTEM CELL

A TEM waveguide is a device that can be used to examine

immunity by setting the equipment under test in a TEM elec-

tromagnetic field. A GTEM cell is an improved type of TEM

waveguide that can be used at frequencies above several giga-

hertz [10]. Electromagnetic compatibility (EMC) measurements

0018-9375/$26.00 © 2010 IEEE

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738 IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY, VOL. 52, NO. 3, AUGUST 2010

Fig. 1. Schematic of a GTEM cell.

TABLE ISPECIFICATIONS OF IEEE 802.11a WIRELESS LAN

using a TEM waveguide are specified in IEC 61000-4-20 [11].

Fig. 1 shows a schematic of the GTEM cell.

The approximate strength of the electric field E cell at half the

septum height for an input power P is given as

E cell =

Z 0 P (1 − |Γ|2 )

h(1)

where Γ is the reflection coefficient at the input of the cell, Z 0is the characteristic impedance of the GTEM cell, and h is the

septum height. Z 0 and h are obtained from the structure of theGTEM cell. If higher order modes are not generated, propaga-

tion loss in the GTEM cell can be ignored. The approximate

electric field can be determined using (1).

The frequency response of the electric field on the GTEM cell

was measured using an isotropic electric field probe, and was

found to satisfy the requirement of a range of ±3 dB from 3 to

6 GHz [9]. The septum height h and the septum width w are 1.0

and 1.2 m, respectively. The dimensions of the laptop computer

used for the examination are 0.27 m high, 0.25 m deep, and

0.35 m wide, which meet the EUT requirements specified in

IEC 61000–4-20.

III. EVALUATION OF INTERFERENCE

A. Specification of the Measuring Instruments

The specifications of the IEEE802.11a wireless LAN used

as a victim receiver are shown in Table I. The specifications

and spectrum of the DS-UWB system used as the interference

source are shown in Table II and Fig. 2, respectively. Although

in the U.S. the spectrum mask in the 5 GHz frequency band is

in-band, the spectrum masks of Japan and EU in this band are

out-of-band. Commercially available UWB equipment, known

as wireless USB, uses a frequency band of 3.1–4.8 GHz, and

the UWB system is called low-band UWB. Only the low-band

UWB can currently be obtained. This is the reason for the choice

TABLE IISPECIFICATIONS OF DS-UWB SYSTEM

Fig. 2. Spectrum of DS-UWB system.

Fig. 3. Setup for interference measurement.

of a UWB band. In this study, the wireless LAN channel was

selected to be #42, of which the center frequency was 5.21 GHz.

The frequency is indicated by the vertical dashed line shown in

Fig. 2. This frequency band contains four channels, as shown inTable I, and in this case the out-of-band interference is in each

channel. These channels are used in the U.S. and EU.1

B. Experimental System

The structure of the employed GTEM cell and the configu-

ration of the experimental system are shown in Figs. 1 and 3,

respectively [9]. The desired wireless LAN signal from the ac-

cess point and the interfering signal generated by the DS-UWB

transmitter are combined using a 180 hybrid coupler and are

fed into the GTEM cell. The wireless LAN terminal is placed

1

In Japan these channels were used until 2004.

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ISHIGAMI et al.: NEW METHOD OF INTERFERENCE EVALUATION BETWEEN AN UWB SYSTEM AND A WIRELESS LAN 739

in the cell as a victim receiver. An electromagnetic field equal

to the sum of the desired and interfering signals is generated in

the cell.

The generated electric field strength in the cell E cell is well

approximated by (1), by substituting the power of the desired or

interfering signal I for the input power P. On the other hand, the

field strength in free space E free at a distance r from a transmitter

with the equivalent isotropic radiated power (EIRP) PEIRP is

given by

E free =

√30P EIRP

r. (2)

Since the limit of the transmitting power of a UWB device is

specified in terms of EIRP per unit bandwidth, the interference

level to be applied can be determined using (1) and (2) if the

separation distance r is given.

C. Evaluation of Interference of Wireless LAN by

DS-UWB System

A laptop PC equipped with a commercially available IEEE

802.11a wireless LAN receiver (PCMCIA2 card) was placed in

the GTEM cell. The desired wireless LAN signal was transmit-

ted from an access point, combined with the interfering UWB

signal, and then injected into the GTEM cell. The signal of the

access point and the interfering UWB signal are mixed by ports

#In1 and #In2 of the 180 hybrid coupler, and the mixed signal

is outputted from port Σ of the hybrid coupler. The uplink sig-

nals from the wireless LAN receiver return to the access point

through the two directional couplers existing between the ac-

cess point and the GTEM cell, so that the ACK packets of the

receiver inside the cell reach the access point. The UWB signal

transmitted to the access point has to be much smaller than thosepropagating to the receiver to evaluate only the effect of the in-

terference to the receiver. This is possible because the signal

separation between ports #In1 and #In2 of the hybrid coupler is

more than 20 dB at the target frequency band.

The throughput from the access point to the victim was mea-

sured for the 6 Mb/s transmission mode (BPSK) and 48 Mb/s

mode [64 quadratic-amplitude modulation (QAM)]. During the

measurement, the feedback functions used to control the trans-

mitting power and the variable transmission rate of the wireless

LAN were both disabled. The data length of the desired signal

packet was fixed at 1024 bytes for both the 6 Mb/s and the

48 Mb/s modes.The receiver noise power spectral density of the wireless

LAN receiver N 0 was estimated by measuring the power of the

additional Gaussian noise injected into the GTEM cell [9]. The

evaluation of the interference between the DS-UWB system

and the IEEE 802.11a wireless LAN was conducted using the

GTEM cell by measuring the throughputs for various I/N ratios

against the change in the C/N ratio, where C is the carrier power

of the wireless LAN access point.

Figs. 4 and 5 show the measured throughputs. The through-

puts were degraded with increased I/N more than those in the

2

Personal Computer Memory Card International Association.

Fig. 4. Measurement results for throughput in the case of 64 QAM.

Fig. 5. Measurement results for throughput in the case of BPSK.

case of noninterference. The throughput of the DS-UWB sys-tem in the case of I/N = 0 agreed with that in the case, where

Gaussian noise instead of the UWB signal was added as the

interference signal I . Therefore, the signal of the DS-UWB is

nearly equivalent to additive white Gaussian noise (AWGN) in

the case of the throughput of 64 QAM. However, the signal of

the DS-UWB is not exactly equivalent to AWGN in the case of

the throughput of BPSK.

D. Converting Interference Level to Separation Distance

Since the electromagnetic field strength in the GTEM cell is

simply related to the free-space propagation distance by (1) and

(2), the strength of the interfering field can be converted intothe separation distance r from the interferer to the victim in free

space for a given EIRP of the UWB transmitter PEIRP

r = h

30P EIRP

Z 0 P in= h

30P EIRP

Z 0 I (1 − |Γ|2 ). (3)

The receiver noise of the wireless LAN at the input port

of the GTEM cell N 0 was measured as −118.5 dBm/MHz.

The transmission loss between the input port and the antenna

output of the wireless LAN receiver was calculated as 44.6 dB

(See Appendix).

Theminimum receiver sensitivity (MRS) of the wireless LAN

in the case of 64 QAM is −66 dBm/20 MHz. The absolute gain

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Fig. 6. Evaluated separation distances for regulation limits of U.S. andEU/Japan.

of the receiving antenna was assumed to be 0 dBi. The C/N ratio

that corresponds to the MRS CNRmin64QAM can be calculated

as

CNRmin64QAM = −66 − −118.5 − 44.6 + 10 log(20 MHz)= 24 dB.

The dashed lines in Fig. 6 denote the MRS in the case of

CNRmin64QAM . The separation distance r is given by (3).

We apply the regulation limits of the U.S. (FCC) and

EU/Japan to PEIRP . The regulation limit in EU/Japan for EIRP

is −70 dBm/MHz, and the U.S. regulation limit is −41.3

dBm/MHz at a frequency of 5.21 GHz.

Fig. 6 shows the evaluated separation distances. The separa-

tion distance under a severe condition, i.e., I / N = −4.5 dB, is0.36 m in the case of the EU/Japan limit, if we assume that the

maximum permissible degradation of the throughput caused by

the interference is 50% under the interference-free condition.

The throughput degradation of the wireless LAN receiver may

be avoided at a distance of 0.36 m or more. The separation

distance for the C/N ratio that corresponds to the MRS of the

wireless LAN is 0.18 m under the same conditions. In contrast,

the separation distance when I / N =−4.5 dB is 9.8 m in the case

of the U.S. limit. For the C/N ratio at the MRS, the separation

distance is 4.9 m. Thethroughput evaluations are under the small

C/N ratio around the MRS of the wireless LAN. It should be

noted that theC/N ratio in practicaluse of wireless LANs is much

larger than the ratio that corresponds to the MRS. When the C/N

ratio is 4 dB larger (C/N = 28 dB) than the ratio of the MRS,

there are almost no effects of interference to the throughput of

the wireless LAN as shown in Fig. 6. The UWB system probably

has a negligible effect on wireless LANs in practical use.

IV. APD MEASUREMENT OF UWB SIGNAL

The APD is widely used to evaluate a statistical characteristic

of a noise wave shape. As shown in Fig. 7, the APD of a signal

is expressed as the percentage of time for which the disturbance

intensity exceeds a threshold level. The APD of a noise enve-

lope x(t ) is expressed in terms of the time exceeding a certain

Fig. 7. Definition of APD.

Fig. 8. Subcarriers of IEEE 802.11a wireless LAN.

threshold W ( x) and the threshold xk as

APD(xk ) =

n(xk )i=1

W i (xk )

T 0

. (4)

A. APD Measurement of DS-UWB System

The impact of interference depends not only on the power of the interfering signal but also on the statistical properties of the

interfering waveform. It has been shown [12]–[14] that the bit

error rate (BER) of a digital wireless communication system un-

der interference can be directly calculated using a simple closed

form of the APD of the interfering signals under some condi-

tions. It has been demonstrated theoretically and experimentally

that APD of an interfering signal has a good correlation with the

BER of the victim wireless system [14], [15]. Considering the

above background, additional measurements were conducted to

obtain the APD of the DS-UWB signal. APD measurements

were also conducted to validate the interference results given

in the previous section. In line with the necessary conditions of

APD measurement, to allow the results to be correlated with thedegradation in the performance of the victim system [12]–[14],

the measurement conditions were as given in the following.

1) We set the APD measurement bandwidth to 300 kHz, con-

sidering the subchannel bandwidth of the IEEE 802.11a

(312.5 kHz) LAN. Thenumber of subchannels of the IEEE

802.11a LAN is 52 (see Fig. 8).

2) We adjusted the system noise level of the APD measure-

ment apparatus to be equivalent to the internal noise level

of the victim receiver.

3) The sampling frequency for the APD measurement was

10 MHz, which is sufficiently higher than the measure-

ment bandwidth (300 kHz).

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Fig. 9. Setup for APD measurement of DS-UWB system.

Fig. 10. APD of DS-UWB signal measured at each subcarrier frequency.

Fig. 9 shows the setup for the APD measurement. Note that

the power of the interfering UWB signal used for the APD

measurement corresponds to I/N = 0 dB in Fig. 5, which means

that the separation distance is 5.3 m in Fig. 6.

The measurement results are compared with APD for theGaussian noise, calculated as

APDG (vi ) = exp

− v2

i

2σ2

(5)

where vi and σ2 are the instantaneous voltage and average

power, respectively.

Fig. 10 shows the measured APD of the DS-UWB signal at

each measurement frequency. Note that the APD is plotted at

four typical subcarrier frequencies.

As a result, the difference between the APD curves for each

subcarrier was about 2 dB. It was also found that some of the

measured APD curves did not agree with the APD of Gaussiannoise. Therefore, it was revealed that the DS-UWB system has a

slightly different effect on each subcarrier of the IEEE 802.11a

wireless LAN from that of AWGN.

B. BER Evaluation From APD

Fig. 11 shows a schematic diagram of BER evaluation of the

IEEE 802.11a LAN from the APD of the DS-UWB system. The

BER before error correction can be evaluated from the APD

distribution using

P ( dec i n)(A) =1

K

K

k =1

1

mk

APDβ k Ak 1

mk (6)

Fig. 11. Schematic diagram of BER evaluation of DS-UWB from APD.

Fig. 12. Schematic diagram of BER evaluation of AWGN from APD.

where K , m, β , and A are the number of subcarriers, the number

of bits, the half distance between symbols normalized by the

square root of the energy per bit, and the amplitude of the signal,

respectively [15].

Next, the BER before error correction for the IEEE 802.11a

wireless LAN was calculated for the interference due to AWGNusing a MATLAB Simulink simulation. In this case, BER is cal-

culated from the average APD over all subcarriers. A schematic

diagram of the simulation is shown in Fig. 12. Simulation results

are shown in Fig. 13.

In these figures, “AWGNcalc.” and“estimated” denote the re-

sults of simulation using the MATLAB Simulink and estimation

from the APD including an effect of a guard interval, respec-

tively. The term “theoret.” denotes the BER curve calculated by

(6). The BER curve evaluated from the APD of the DS-UWB

signal and the simulation result of AWGN were good agreement

in the case of 64 QAM. On the other hand, the differences in

the case of BPSK were about 1 dB and the estimated BER was

largerthanthe simulated BER when the BER was lessthan10−2 .

Thus, it can be concluded that the APD of the DS-UWB signal

can be assumed to be AWGN in the case, where the modulation

scheme of the IEEE 802.11a LAN is 64 QAM. However, the

result shows that the DS-UWB signal is not exactly equivalent

to AWGN in the case of BPSK.

C. Throughput Evaluation From APD

The throughputs measured in a GTEM cell were compared

with those obtained from the measured APD of the DS-UWB

signal. The procedure for calculating the throughput from the

measured APD is explained in the following.

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Fig. 13. Calculated results of BER before error correction in cases where themodulation schemes of IEEE 802.11a are (a) 64 QAM and (b) BPSK.

The BER after error correction is calculated from that beforeerror correction using the difference between the BER before

and after error correction in the case, where AWGN is the inter-

ference source. The packet error rate (PER) is calculated using

PER ≤ 1 − (1 − P b )N b ≈ N b P b (0 < P n 1) (7)

where N b and Pb are the number of bits per packet and the BER

after error correction, respectively [16].

The throughput (TP) can be obtained from the PER using

TP = (1

−PER)TPm ax (8)

where TPm ax is the maximum throughput, which is determined

by the modulation scheme of the wireless LAN [17]. In the cases

of 64 QAM and BPSK, the values of TPm ax are about 16 and

4.4 Mb/s, respectively.

Thethroughputs measured using the GTEM cell and those ob-

tained from the APD by (8) are shown in Fig. 14. The estimated

throughputs contain the effect of the guard interval. Compar-

ing these throughputs at half the maximum throughput TPm ax

(8 Mb/s for 64 QAM and 2.2 Mb/s for BPSK), the differences

between the measured and estimated throughputs are from 0.1

( I/N =−1.5 dB) to0.8 dB( I/N = 4.5 dB)in the case of64 QAM

and from 0.2 ( I/N = 1.5 dB) to 1.7 dB (for noninterference) in

Fig. 14. Calculated and measured throughputs in cases where the modulationschemes of IEEE 802.11a are (a) 64 QAM and (b) BPSK.

the case of BPSK. In this regard, the measured throughputs be-low 3 Mb/s in the cases of noninterference, I/N = −4.5 dB and

I/N = −1.5 dB for BPSK, were estimated by extrapolating the

measured throughput curve downwards.

A number of reasons can be given for this difference. For

example, a slight displacement of the victim receiver inside the

GTEM cell may cause the difference. Another reason is that

the APD measurement and interference test were not conducted

simultaneously, i.e., the DS-UWB signals in the APD measure-

ment and interference test are not exactly the same. Moreover,

although the absolute gain of the antenna built in the wireless

LAN receiver is assumed to be 0 dBi in Section III-D, there is a

possibility that the actual gain may be 1 or 2 dB larger (i.e., thisantenna is not isotropic) than the assumed gain because the an-

tennae of Wi-Fi equipment are known to have a maximum gain

of 2 dB or more in general. If the difference due to these rea-

sons is assumed to be about 1 dB, the throughputs measured in

the GTEM cell are appropriate. Thus, it was confirmed that the

proposed method of evaluating the interference using a GTEM

cell is feasible.

V. CONCLUSION

We proposed a method of evaluating the interference between

a UWB system and a wireless LAN using a GTEM cell that can

test a receiver with a built-in antenna.

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The evaluation of interference between an IEEE802.11a wire-

less LAN and a DS-UWB system was conducted. It was shown

that the signal of the DS-UWB was almost equivalent to AWGN

in the case of the throughput variation of 64 QAM.

We evaluated the separation distances for the U.S. and

Japan/EU regulation limits. In practical use, where the C/N ratio

is much larger than that corresponding to the MRS, the UWB

system probably has a negligible effect on wireless LANs.

The APD of the DS-UWB signal was determined at each

subcarrier frequency of the victim IEEE 802.11a signal. It was

found that the APD of the UWB signal measured using the

subchannel bandwidth of the IEEE 802.11a LAN could not be

regarded as AWGN, but the total effect of the interference on

the measured throughput was nearly the same as that of AWGN

in the case of 64 QAM.

The measured APDs were used to calculate the throughput of

the IEEE802.11a LAN. These results were compared with the

throughputs measured by the proposed method using a GTEM

cell. The throughputs obtained from the APD agreed with those

measured by the proposed method. It was confirmed that theproposed method of evaluating the interference using a GTEM

cell is feasible.

APPENDIX

The transmission loss between transmitting and receiving an-

tennas AT , which is the ratio of power received by the receiving

antenna PR to the power input to the transmitting antenna PT ,

is expressed by the Friis transmission equation as

AT =P R

P T

=λ

2 GaT GaR

(4πr)

2 (A1)

where GaT and GaR are the absolute antenna gains of the

transmitting and receiving antennas, respectively, λ is the wave-

length, and r is the distance. The antennas are in unobstructed

free space with no multipath. PR is the available power at the

receiving antenna terminals. PT is the net power inputted to the

transmitting antenna.

The electric field strength in free space under the far-field

condition E f is given by

E f =

√30P T GaT

r. (A2)

In contrast, the electric field at half the septum height in a

GTEM cell E G is

E G =

√P T Z 0

h(A3)

where Z 0 and h are the characteristic impedance of the input port

of the GTEM cell and the septum height, respectively. When the

GTEM cell generates the electric field in the far field instead of

at a transmitting antenna ( E f = E G ), (A2) and (A3) yield

GaT

r2

=Z 0

30h2

. (A4)

Using (A4), the transmission loss AT is finally obtained as

AT =λ

2 GaR Z 0

30h2 (4π)2 . (A5)

The values of the parameters for the cases discussed in the pa-

per are as follows: the wavelengthλ is 5.758 cm at a frequency of

5.21 GHz, the receiving antenna gain GaR isassumedto be0 dBi(= 1), the characteristic impedance Z 0 is 50 Ω, and the septum

height is 1 m. The loss is calculated as −44.6 dB using (A5).

ACKNOWLEDGMENT

The authors would like to thank Mr. Yamanaka, group leader

of the EMC Group, National Institute of Information and Com-

munications Technology (NICT), for his support and helpful

suggestions. The authors would also like to thank the Medical

ICT Group of NICT for their support and helpful suggestions.

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Shinobu Ishigami (M’92) was born in Yokohama,Japan, on February 19, 1968. He received the B.E.,M.E., and the D.E. degrees from the University of Electro-Communications, Chofu, Tokyo, Japan, in1990, 1992, and 1997, respectively.

He was a Research Associate in the Departmentof Electronic Engineering, University of Electro-Communications, Tokyo, from 1992 to 1999. Since1999,He hasbeena SeniorResearcherat theNationalInstitute of Information and Communications Tech-nology, Tokyo, where he is engaged in research on

electrostatic discharge radiation, immunity and emission testings, field-probecalibration, and ultrawideband measurement. He is an expert of IEC TC77WG13.

Dr. Ishigami is a member of the Institute of Electronics, Information, andCommunication Engineers, Japan, and the Institute of Electrical Engineers,Japan.

Masashi Yamada was born in Kanagawa, Japan, onJanuary 30, 1984. He received the B.E. and M.E.degrees from the Musashi Institute of Technology,Tokyo, Japan, in 2006 and 2008, respectively.

He was a Trainee at the National Institute of In-formation and Communications Technology, Tokyo,from 2005 to 2008, where he was engaged in theresearch on communications system electromagneticcompatibility. He is currently with Sony Corporation,Tokyo.

Haruki Kamiya was born in Gifu, Japan, on January22, 1985.He receivedthe B.E. andM.E.degreesfromthe Musashi Institute of Technology, Tokyo, Japan,in 2007 and 2009, respectively.

He was a Trainee at the National Institute of Infor-mation and Communications Technology, from 2006to 2009, where he was engaged in research on com-munications system electromagnetic compatibility.He is currently with Canon Inc., Susono-shi, Japan.

Mr. Kamiya is a member of the Institute of Electronics.

Kaoru Gotoh (M’07) received the B.E., M.E.,and D.E. degrees from the University of Electro-Communications, Tokyo, Japan, in 1996, 1998, and2002, respectively.

She was a Research Associate at St. PetersburgUniversity in Russia, in 2001 and the University of Electro-communications, in 2002. Since 2003, shehas been at the Communications Research Labora-tory (currently, National Institute of Information andCommunications Technology), where she is engagedin research on electromagnetic compatibility for ra-

dio communication systems.Dr. Gotoh is a member of the Institute of Electronics, Information, and Com-

munications Engineers, Japan.

Yasushi Matsumoto (M’99) receivedthe B.E.,M.E.,and Ph.D. degrees in electrical and communicationengineering from Tohoku University, Sendai, Japan,in 1983, 1985, and 1998, respectively.

In 1985, he joined Radio Research Labora-tory [currently, National Institute of Information andCommunications Technology (NICT)], where he iscurrently a Research Manager in the electromagneticcompatibility group. From 1990 to 1994, he was atNational Space Development Agency, Japan (cur-rently, Japan Aerospace Exploration Agency). From

1999 to 2005, he was an Associate Professor at Tohoku University. His researchinterests include electromagnetic compatibility and wireless communications.

Masamitsu Tokuda (M’84–F’07) was born inManchuria, on October 19, 1944, and grew up inHokkaido, Japan. He received the B.E. and M.E.degrees in electric engineering, in 1967 and 1969,respectively, and the Dr.E. degree in electronics, in1983, from HokkaidoUniversity, Sapporo-shi, Japan.

He was at Nippon Telegraph and Telephone Cor-

poration Laboratory, where he was engaged in re-search anddevelopment of many kinds of telecommu-nication cables, especially optical fiber cables from1969 to 1986, and in studies of electromagnetic com-

patibility (EMC) for telecommunication systems in 1986. In 1996, he was withthe Kyushu Institute of Technology, Kitakyushu-shi, Japan, where he was en-gaged in the education and research of EMC for electronic systems. In 2001, he

joined the Musashi Institute of Technology, Tokyo, Japan(currently, Tokyo CityUniversity since April 2009), where he is currently a Professor and is engagedin the education and research of telecommunication system such as a power linecommunication system and wireless communication systems.

Prof. Tokuda has been the Chairman of IEC/TC77 (EMC Standard), since2007. He was the Chairman of the Technical Group on EMC of the Institute of Electronics, Information, and Communication Engineers (IEICE) Japan, from1991 to 1993. He is a recipient of the Achievement Award of IECE, Japan, in1986.

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