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1 Introduction

Many systems using millimeter-wave(MMW) bands have recently been developedin the United States, Europe, and Japan. Theyinclude home-use wireless-link systems (homelinks), fixed wireless access systems (FWA),multi-point video distribution systems(MVDS), and wireless local area networks(W-LAN)[1]～[8]. In particular, the 60-GHzband is considered suitable for short-rangewireless applications such as home-linksunder high atmospheric attenuation[9]. Thesesystems use the 60-GHz band to achieve highbit-rate transmission across a wide frequencyband. The Telecommunications TechnologyCouncil of the Ministry of Public Manage-ment, Home Affairs, Posts and Telecommuni-cations (formerly, the Ministry of Posts andTelecommunications) was set up in Japan tointroduce systems using the 60-GHz band, and

regulations concerning this band were pub-lished in August 2000. A MMW video-trans-mission system[8] was earlier proposed by theCouncil as a potential system using the 60-GHz band.

The MMW video transmission system isan alternative to the feeder line that can con-nect outdoor broadcasting reception antennaswith indoor television set (TV). The videosignals (multiple broadcasting signals) aretransmitted on the MMW band in the system.This system can effectively reduce the amountof electrical wiring that is used in portable andwall-mounted TVs. Such a reduction is anadvantage since these devices are becomingmore and more popular. The MMW bandappears to be especially suitable for wide-band systems because broadcasting signalsrequire a wide frequency band[15].

When designing the MMW link for thesystem, it must be ensured that the local oscil-

Kiyoshi HAMAGUCHI et al.

3-3 Wireless Access System

3-3-1 Design and Performance of a Millimeter-Wave Video-Transmission System using 60-GHz Band for Indoor BS Signals Transmission

Kiyoshi HAMAGUCHI, Yozo SHOJI, Hiroyo OGAWA, Yasutake HIRACHI,

Seiji NISHI, Eiichiro KAWAKAMI, Eiji SUEMATSU, Toshiya IWASAKI,

Akira AKEYAMA, Youichi SHIMOMICHI, Takao KIZAWA, and Ichiro KUWANA

The design and performance of a millimeter-wave video transmission system using 60-GHz band for indoor broadcasting-satellite (BS) signals transmission is presented. This sys-tem can transmit multiple video signals such as broadcasting signals and user-oriented sig-nals to a television set indoors. To minimize the local oscillator’s frequency offset andphase-noise effects, the system uses a self-heterodyne scheme. Based on the concept, thesystem is developed to meet required carrier-to-noise-power-ratio (CNR) and 3rd-orderintermodulation (IM). The BS transmission was experimentally done by using the transmitterand receiver setup. The results are very promising and show the feasibility of the system.

Keywords millimeter wave, broadcast, BS, television, intermodulation, CNR, experiment

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lators of both the transmitter and receiver havehigh frequency stability and low phase noise,because the system uses the oscillators for thefrequency conversions. The transmitter con-verts the input signal (source signal) into anMMW band, and the receiver converts it theregenerated source signal. To minimize thedegradation of the transmission quality in thisconversion process, a self-heterodyne scheme,in which the local tone of the transmitter ismultiplexed into a transmission signal and isused in the receiver with the help of a square-law detector, was earlier developed[10][11][17].This scheme could sufficiently eliminate thedegradation from the phase noise and frequen-cy offset.

One of the critical parameters in theMMW link is the carrier-to-noise-power-ratio(CNR) margin at a specified transmission dis-tance, that is, the allowable transmission lossin the MMW link. This margin mostlydepends on the effective isotropic radiatedpower (E.I.R.P.), reception antenna gain, andnoise figure (NF) of the reception amplifier.In addition, the carrier-to-interference-powerratio (CIR) of the MMW link is of great inter-est, because signals composed of multiple car-riers will be strongly affected by the 3rd-orderintermodulation (IM3) distortion due to thenon-linearity of the power amplifier of thetransmitter[12].

Several wireless transmission systems[4][5]and RF devices[7] for video transmission usinga MMW band have been developed. Howev-er, to the best of our knowledge, the systemat-ic design and application of these systems,especially that using the self-heterodynescheme, have not yet been fully clarified.

In the next section, the concept of theMMW video transmission system with someassumptions is described. Next, the design ofthe system based on the CNR link-budget andIM3 distortion for BS (Japanese broadcasting-satellite) signals transmission is introduced, inwhich the remote-heterodyne scheme is used.After that, the hardware setup and the charac-teristics of the transmitter and receiver aredescribed. Next, to obtain the required CIR

for the BS signals transmission, the experi-mental CIR by using an amplifier is reported.We also discuss the experimental resultsobtained using the developed transmitter andreceiver. Finally, we conclude with a briefsummary. Hereafter “BS” is used as a recep-tion BS signals on the intermediate-frequency(IF) band (BS-IF).

2 System Concept

The conceptual image of the MMW videotransmission system is illustrated in Fig.1.The feeder lines connected to the outsideantennas such as BS antenna, communication-satellite (CS) antenna and terrestrial broad-casting antenna are fed into one room in thehouse. These broadcasting signals are multi-plexed and transmitted on a MMW band froma wall-mounted transmitter. The receivers onthe TV sets receive the MMW signal. Eachseparated broadcasting signal is obtained afterde-multiplexing. Other signals, such as acable-television (CATV) and user-orientedsignals (a video-output signal from a video-tape player, for example) may be simultane-ously multiplexed at the transmitter.

The room shown in the figure has an areaof 19.4 m2 (3.6×5.4 m) with a diagonal of 6.5m (this size corresponds to the size of a 12-tatami-mat Japanese room). For this room, apropagation distance of 10m (including a 3.5-m margin) is enough for the MMW link.When the transmission loss due to the insidewall in the house is small, the radiated MMWsignal can go through the wall into the nextroom. Therefore, a direct propagation is basi-cally assumed, the propagation across the wallcan also be considered for such a condition.

Hereafter it is assumed that the transmitterand receiver can change the frequency bandby using frequency converters. That is, thetransmitter converts the signal into an MMWband, and the receiver converts it back into anoriginal one. The transmission quality in theconversions may degrade as a result of theMMW-link-margin reduction, the frequencyoffset between the transmitter and receiver, the

Journal of the Communications Research Laboratory Vol.48 No.4 2001

67

phase noise of the converter, and the IM3 dis-tortion.

3 System Design for BS SignalsTransmission by the Millimeter-Wave Self-Heterodyne Scheme

The system design for BS signals trans-mission is given here. To determine therequirements for phase noise and frequencyoffset, the desirable performance parametersof a typical BS converter installed on a para-bolic antenna are listed in Table 1[13][14]. Asshown in the table, the output signal of the BSconverter has a frequency f0 plus a frequency

offset lower than 1.5 MHz (this means thatf1＝f0±1.5 MHz, wheref1 is the frequency ofthe signal). In contrast, a desirable capturerange of a typical BS tuner’s automatic-fre-quency-control (AFC) is f1±1.5 MHz (shownas a digital-integrated-receiver-decoder’s(DIRD’s) desirable performance[14]). Theallowable frequency offset on the MMW linkmust therefore be within±1.5 MHz, whichcorresponds to a 25 ppm deviation at 60 GHz.

The frequency converters of the transmit-ter and receiver must have low-phase-noisecharacteristics. Because a converter usuallyconsists of a mixer and a local oscillator, thetransmission quality can degrade as a result of


Conceptual image of MMW video transmission systemFig.1

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the phase noise of the local oscillator. To meetthe low-frequency-offset and low-phase-noiserequirements, a self-heterodyne scheme[10][11][17]is used. In this scheme, the local tone ismultiplexed into an MMW BS signals at thetransmitter. The local tone and the MMW BSsignals are mixed in the square-law detector,and the MMW BS signals are thus down-con-verted at the receiver. Under this scheme, thedegradation of MMW transmission occurredfrom the inferior phase noise or frequency off-set can be almost eliminated[10]. To show theeffectiveness of the scheme, the phase-noiseperformance is listed in Table 2.

Fig.2 (a), (b), and (c), respectively, showsthe BS-IF frequencies, the channel allocationfor Japanese BS broadcasting[15], and the fre-quencies of the MMW band. From Fig.2 (b),there are eight signals (channels) on the IF.The BS digital broadcasting is assigned to BS-1, -3, -13, and -15. The BS-IF frequency witha range from 1.035 to 1.335 GHz (the centerfrequency is 1.185 GHz) is up-converted tothe MMW band, and the signal in the MMWband is down-converted to an IF signal. Toconvert the BS-IF frequency to the MMWband, the band-pass filter (BPF) of the trans-mitter suppresses the undesired side-band sig-nal without the local tone (shown as Lo in

Fig.2 (c), in which the lower side-band iseliminated). When a single frequency con-verter is used in the transmitter for hardwaresimplicity, the RF in Fig.2 (c) becomes to bethe local tone’s frequency plus 1.185 GHz.

The output CNR at the receiver has previ-ously been analytically derived[10], that is, thepower ratio of a detection signal (which ismade up of the product of local tone and theBS signals) to a detection noise (which ismade up of the product of local tone, BS sig-nals, and thermal noise) at the square-lawdetector is calculated. The result is given by

where Pr, k, T, B, and F are, respectively, thetotal reception power including the local tone,Boltzmann’s constant (1.38×10－23 J/K), theambient room temperature (typically, 300 K),the sum of equivalent bandwidth for all BSsignals, and the noise figure. The schemegives the best CNR performance when thetransmission power of the BS signals equalsthat of the local tone, because the detectionpower of the signal is maximized. Equation(1) means that the CNR using the MMWremote-heterodyne scheme is 9 dB worse thanthat using the usual down-conversion typedetection scheme. Although the 9 dB penaltyhas to be paid in the scheme, it is very attrac-tive that an inexpensive MMW local oscillatordevice with inferior phase-noise and frequen-cy-stability performances can be used inhome-use systems such as the MMW video-transmission system. In addition, the localoscillator is not needed at the receiver.

3.1 CNR Margin in the Link-BudgetAnalysis

The system analyzed here is a relay linkbetween the satellite broadcasting link and theMMW link. To evaluate the feasibility of thesystem, the CNR margin must be estimated byusing Equation (1). For the cutoff CNR,CNRcutoff

, at the output of the relay link, 14 dBfor BS analog transmission and 11 dB for BSdigital transmission[13] are used.

Table 3 lists the specifications and


Bs converter of parabolic antenna

Modulation Allowablefrequency

offset

Phase noise [dBc/Hz]

@10kHzoffset

@5kHzoffset

@1kHzoffset

±1.5MHzNot specifiedFM

(Frequency modulation)

BSanalog

±1.5MHz－80－70－528PSK

(8-ary phase-shift keying)

BSdigital

Table 1 Required performance of a BS converter

100105Frequency offset [kHz]

-117-104-98IF Input signal [dBc/Hz]-80-49-45Local tone [dBc/Hz]-117-103-97IF output signal [dBc/Hz]

Table 2 Phase-noise performance

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obtained CNR margin for the satellite broad-casting and MMW links. The calculated 10dBm transmission power of the MMW trans-mitter with a 5 dBi antenna, and the calculated

6 dB noise figure of the MMW receiver with a30 dBi antenna, are 24.2 dB of the total CNRvalue including that of the MMW link foreach BS signal. The CNR margin, which is


BS-IF frequencies, channel allocation, and frequencies of MMW bandFig.2

ValuesParameters

BS digitalBS analog

25 dBCNR at input of transmitter (CNRsat)

44Number of channels

8 PSKFMModulation

34.5 MHz27 MHzBandwidth/channel

＋10 dBm(Local tone:＋7 dBm,

BS－ IF:－2 dBm/channel)5 dBi

Total power

Antenna gain

Transmitter

10 m88.0 dB@60 GHz

Transmission distancePath loss@ Free-space loss

Propagation path

30 dBi－43 dBm

6 dB－74.9 dBm

Antenna gainTotal reception power(Pr)

Noise figureDetection thermal noise(8kTBF)

Receiver

31.9 dBCNR for MMW link (CNRMMW)

24.2 dB

CNR at output of receiver (CNRtotal),

11 dB14 dBCNRcutoff

13.2 dB10.2 dBCNR margin

CNRtotal=

CNRsat

1CNRMMW

1＋

1

Table 3 Specifications and obtained CNR margin

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defined as CNRtotal －CNRcutoff, for BS analog

signal is 10.2 dB and that for BS digital signalis 13.2 dB. This margin enables the transmis-sion distance to be increased and MMW linksto be established in buildings with inner wallsmade of wood, paper, plaster, and clay, such asthose in a typical Japanese house.

3.2 Analysis of Intermodulation Distor-tion for BS Signals Transmission

The MMW video transmission systemmust transmit multiple carriers through anamplifier. As a result, in addition to the ther-mal noise, additional IM noise due to thetransmission of multiple carriers will occur. Itis a significant factor in the overall perform-ance of the system and has been analyzed in astudy on satellite communication systems[12],where the distribution of the IM products isderived for uniformly spaced multiple-carrierswith the same amplitudes. Because BS sig-nals transmission involves eight carriers, thesystem generates the same IM products asthose generated in satellite communicationsystems. However, in terms of modulation,BS signals transmission is different becausethere are two types of carriers in the BS fre-quency-band and they are spaced uniformly.One is FM with a bandwidth of 27 MHz foranalog broadcasting, and the other is 8 PSKwith a bandwidth of 34.5 MHz for digitalbroadcasting. Therefore the measuring of theIM distribution becomes difficult.

If the several signals go through a non-lin-ear amplifier, new frequency products are gen-erated that are harmonically related to theinput-signal frequency. Many of these prod-ucts are outside of the frequency band of inter-est; that is, some are higher-order productsthat are at such low level that their analysis isof little importance. Normally, the IM prod-ucts of interest are those of the lower order,such as 2nd- and 3rd-order or those that existin the pass-band of the system. In particular,IM3 products generate signals that are veryclose to the original signals, thereby degradingthe original signals when the system transmitssignals with more than two carriers in their

bands. Therefore, because the systemprocesses BS signals, which have eight carri-ers in their band, it should be designed to takeinto account the IM3 products.

The IM3 products can be classified intotwo main categories: two-tone (2f1－f2) typeproducts and three-tone (f1＋f2－f3) type prod-ucts. The two-tone and three-tone productsare harmonically generated and are related totwo and three input signals, respectively.When we assume that N carriers (f1, f2, . . . ,fN) are input into an amplifier and the fre-quency interval of each carrier is the same, thenumber of two-tone and three-tone productsthat fall in the k-th carrier can be given byequations (2) and (3), respectively[12][16].

Table 4 shows the number of IM3 productsthat fall on the transmitting channels calculat-ed by using the above two equations.

From the point of power of the IM3 prod-ucts, the power of the three-tone products isfour times larger than that of the two-toneproducts[12]. The relationship between theCIR and the 3rd-order intercept-point (IP3) ofthe device is expressed by the following equa-tion:

where Pout is the output power per channel ofeach signal and suppression level Spl3 can beexpressed as


Table 4 Number of IM3 products that fall on the transmitting channels

BS-15BS-13BS-11BS-9BS-7BS-5BS-3BS-1Channel

33333333Number of IM3(2-tone)

91214151514129Number of IM3(3-tone)

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Equations (4) and (5) give the CIR as follows.

When an amplifier with a known IP3 ampli-fies BS signals with the same power, requiredCIR is obtained from Equation (6) by substitu-tion of the signal’s power, Pout, at the output ofthe amplifier when the video signal’s qualitybecomes worse. Then IP3 can be obtainedfrom Equation (4) and (5) at a designed Pout

using the required CIR.

4 Hardware Description

Based on the analytical link-budget shownin Table 3, a transmitter and receiver set thatuses a new microwave-monolithic-integrated-circuit (MMIC)-based RF module for theMMW self-heterodyne scheme was devel-oped. The built-in module of the transmitterhas a flat antenna. To ensure the gain of theantenna of the receiver is high, a circularwaveguide array antenna with an inexpensiveplastic base was used. For performance com-parisons, a structurally similar antenna with analuminum-base is also developed. The MMWvideo-transmission system specifications aresummarized in Table 5.

4.1 TransmitterFig.3 shows a block diagram of the trans-

mitter, including the RF module and a DC-power-supply circuit. The up-converter of themodule consists of a double-balanced FETmixer, a gain-controlled amplifier, a doubler,and a dielectric-resonant-oscillator (DRO). Agate-bias voltage is applied in the FET mixerand is made from VGG inside the module (thevoltage can be controlled at adjustment point1). Fig.4 shows the up-converter outputpower for the RF signal and the local toneagainst the gate-bias voltage under IF inputpower of －15dBm and the IF frequency of1.1 GHz. The figure shows that the gate-biasvoltage can control the output power for theRF signal and the local tone. This is becausethe balanced point and the conversion loss ofthe mixer are changed. To leak the local tone,the mixer is used as an “un-balanced” point.From the figure, we can see that an equalpower distribution between the RF signal andthe local tone can be obtained when the gate-bias voltage is－0.4V. The power of the RFsignal and that of the local tone as a functionof the local input power (the power can becontrolled at adjustment point 2) is also shownin Fig.5, which shows that the up-converteroutput power for the RF signal and local tonecan be linearly controlled by the local inputpower. Thus－0.4V is set as the gate-biasvoltage.

The RF module in the transmitter (packagesize: 50×23×6.5 mm) is shown in Fig.6. Apatch antenna (planar-antenna, 1.60×1.13mm) with linear polarization is mounted with-in the module. The window is made of aborosilicate-opaque glass and is hermeticallysealed.

The IF-input power vs. RF output powerof the transmitter is shown in Fig.7. When theIF input power is－15 dBm, the RF outputpower and the local tone’s power are equal,and each RF output power is 7 dBm. In thiscase, the compression level of the image sig-nal (that corresponds to the lower side-band)is－22 dBc when the IF input power is－15dBm.


59.010 GHzLocal tone (Lo)

60.195 GHzRF frequency (RF)

10 dBmTotal power

Transmitter-45 dBc/Hz@5 kHz-49 dBc/Hz@10 kHz-80 dBc/Hz@100 kHz

Local oscillator’sphase noise

(measured value)

5 dBiAntenna gain

6 dBNoise figure

Receiver UnnecessaryLocal oscillator

30 dBiAntenna gain

Table 5 MMW video-transmission system specifications

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4.2 ReceiverFig.8 shows a block diagram of the receiv-

er. The receiver consists of the array antenna,the RF module, and a DC power supply cir-cuit. The RF module consists of two ampli-fiers, a single-ended FET mixer, and a band-pass filter. The mixer is used as a square-lawdetector. The appearance and the packagedimensions of the receiver are the same asthose of the transmitter except for the V-bandconnector (shown in Fig.9). Fig.10 plots RFinput power vs. IF output power of the receiv-er. The RF input power is equivalent to totalreception power including RF signal powerand local tone power. Two MMW tones with59.01 GHz (local tone) and 60.11 GHz, andthe same power are fed into the module.According to the figure, when the total recep-tion power is －53 dBm, IF output power isabout －46 dBm. This means that the conver-


IF input power vs. RF output power oftransmitter

Fig.7

RF module in transmitterFig.6

Block diagram of transmitterFig.3

Gate-bias voltage vs. up-converteroutput power applied in the balancedmixer

Fig.4

Local input power vs. up-converteroutput power

Fig.5

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sion loss of the module is about 10 dB whenthe reception signal power is 3 dB below thetotal reception power. The measured phase-noise characteristics of the receiver is shownin Table 5. It is clear that the phase-noisepower is less than－100 dBc/Hz at 10 kHzfrequency-offset.

4.3 Reception AntennaFig.11 and 12, respectively, show the

schematic structure and a photograph of thedeveloped 16×16 circular-waveguide-arrayantenna. Each element of the array is distrib-uted using a strip-line. Two antennas, with thesame structure and shape but with bases madeof plastic (a syndiotactic-polystyrene withgold plated) and aluminum, were fabricated.The syndiotactic-polystyrene base can bemade by injection molding in order to reducethe cost.

The circular waveguide of the antenna(diameter: 3.5 mm) has only a single mode atthe V-band. Its cutoff frequency forTE11mode is 50.2 GHz and that for higher-order modes is 65.6 GHz. The aperture size ofthe antenna is 71×71 mm. For power distri-bution, strip-line parallel feed with a quarter-wavelength transformer is used. PTFE (apolytetrafluoroethylene) is used as a dielectricsubstrate. For the connection from the circu-lar waveguide to the strip-line, and from thestrip-line to the coaxial line, the size is opti-mized using an electromagnetic simulator. Wealso made the output port of the antenna a V-band connector.


Schematic structure of 16×16 arrayantenna

Fig.11

Block diagram of receiverFig.8

RF module in receiver (face and back)Fig.9

RF input power vs. IF output power ofreceiver

Fig.10

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Measured far-field patterns of the plastic-base antenna for the E- and H-planes at 60GHz are shown in Fig.13(a) and (b), respec-tively. A near-field method[18] is used in themeasurement. As a power of each element isuniformly distributed, the sidelobe level isabout－11dB. The full beam width at halfmaximum of gain for this antenna is around3.7 degrees for E- and H-plane.

To measure the gain of this receptionantenna on the frequency, a standard hornantenna with a known gain is measured for

various frequencies. Next, the gain of thereception antenna is also measured for variousfrequencies. The gain can be obtained ascompared with these two gains. The near-field method is also used in the measurement.The measured gains of both antennas areshown in Fig.14 as a function of frequency.As the interface of the antenna is the V-bandconnector while that of the near-field measure-ment system is the waveguide, a waveguide-to-coaxial adapter was used in the measure-ment. The measured antenna gain shown inthe figure includes the loss (within 0.5 dB) ofthe adapter. We can see that the measuredgains of both antennas are almost the same.The obtained gain of the plastic-base antennais around 30 dBi for 58 GHz at maximum, andaround 27 dBi at 55 GHz and 64 GHz. There-fore the flatness within 3 dB is obtained for 9GHz band. This bandwidth is 15% at 60 GHz.

The efficiency,η, is calculated from thefollowing equation,

where G, A, andλare, respectively, an anten-na gain, an aperture size, and a free spacewavelength. The efficiency of the antenna iscalculated to be 37%. Such a wide bandwidth(9 GHz) shows that this planar antenna struc-ture is suitable for wide-band applicationssuch as our system. The plastic- and alu-minum-based antennas have almost the sameantenna gain as well as other characteristicssuch as a reflection property and a radiationpattern.


Photograph of 16×16 array antenna(left: aluminum-base, rigit: plastic-base)

Fig.12

Far field pattern of 16×16 arrayantenna

Fig.13

Antenna gain of plastic-base and ofaluminum-base antennas

Fig.14

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5 Experimental Performance of BSSignals Transmission

First, the required CIR for the BS analogand digital signals in an experiment based onsubjective evaluation is calculated. Then, byusing the required CIR, the required IP3 forthe power amplifier of the transmitter is esti-mated. An experimental BS signals transmis-sion by using the developed transmitter andreceiver is also performed.

5.1 Experimentally Measured Inter-modulation Products

Fig.15 shows the experimental setup forevaluating IM3 products. An actual BS recep-tion signals are used for this experiment. AnIF amplifier is used as a non-linear device thatmakes IM noise. In the experiment, the levelof the signal input into the IF amplifier ischanged by using a variable attenuator (ATT-1). When the level of the signal input isincreased, the quality of the video signal onthe monitor becomes worse because of the IMnoise. When any degradation of the video sig-nal’s quality can be recognized from a visualinspection, the level of the signal input intothe IF amplifier is measured. More IM3 prod-ucts are generated in the center of the trans-mitting band than around the edges of theband[12]. Both the BS-7 (BS analog) and BS-3 (BS digital) signals are measured becausethey are the nearest channels to the center ofthe band. The IF amplifier with a gain of 18dB and IP3 of 26 dBm is used.

Table 6 lists the level of each BS signal’sinput into the IF amplifier (shown as “IF ampinput” in Fig.15) when a degradation (a beatpattern on the monitor) is observed in the BS-7 channel. Table 7 also shows the level of

each BS channel’s input into the IF amplifierwhen a degradation (an impulse block noise)is observed in the BS-3 channel. From theseTables, we can see the difference in level is1.5 dB from Table 6 and 2. 0 dB from Table 7among eight BS channels. This is because theactual reception power from the BS converteritself includes a difference.

By substituting IP3, Pout , D2(N, k), andD3(N, k) for Equation (6), the required CIR forBS-7 and BS-3 channels can be calculated asfollows:

Although it is needed that all BS signals havethe same power level in our analysis describedin Section 3.2, there is a difference among BSsignals. To include the difference, the maxi-mum and minimum levels in each Table areused hereafter. In this case, Pout is－12.75±0.75 dBm plus the amplifier’s gain for BS-7,and－6.5±1.0 dBm plus the amplifier’s gainfor BS-3. By substituting Pout for Equations (8)and (9), the required CIR for BS-7 and BS-3channels can be obtained.

The required IP3 is also calculated fromEquations (4) and (5) in which the transmis-sion power for each BS channel, Pout , isassumed to be －2 dBm. The CIR andrequired IP3 are summarized in Table 8.


Experimental setup for evaluatingIM3 products

Fig.15

Table 6 Level of each BS signal' s input into IF amplifier when a degradation occurred in BS-7 (BS analog)


-13.5-13.0-12.0-12.0-13.0-13.0-13.5-13.5Power[dBm]

Table 7 Level of each BS signal' s input into IF amplifier when a degradation occurred in BS-3 (BS digital)


-7.5-7.1-5.5-5.5-5.5-5.5-7.1-7.1Power[dBm]

76

It is clear from Table 8 that the BS digitalchannel (BS-3) is around 12 dB more robustagainst the interference power than the BSanalog channel (BS-7). The analog channelalso requires a higher IP3 (around 19 dBm).

5.2 Experimentally measured CNR Per-formance

Fig.16 shows the experimental systemsetup. Fig.17 shows photographs of the trans-mitter and receiver. The bandwidth of thetransmitter and receiver was tuned to 300MHz in order to evaluate the performance ofthe BS signals transmission system.

BS signals in the 1-to-1.3 GHz band fromthe parabolic BS antenna were input into thetransmitter. The transmitter up-converted theinput signals into 60-GHz band signals andtransmitted them from the 5-dBi patch anten-na. The receiver, which had a 30-dBi planner

array antenna, amplified the received MMWsignals and down-converted them into BS-IFsignals. The signals were fed into the BStuner. To measure the CNR , the BS outputsignals are connected to a spectrum analyzerinstead of the BS tuner. When the outputpower of each BS signal is measured, centerfrequency and bandwidth of the analyzer areset for each BS signal’s center frequency andbandwidth because this system handles multi-carrier signal.

Fig.18(a) and (b), respectively, show thepower spectrum of the BS input at the trans-mitter and that of BS output at the receiver fora transmission distance of 10 m. The lowertwo signals and upper two signals are BS digi-tal channels, and the four middle signals areBS analog channels. We can recognize thatthe spectrum at the receiver is almost the sameas that at the transmitter, and particular fre-quency response is not observed on the IFband.

Fig.19 shows the experimental CNRbefore and after the MMW transmission (10-m transmission distance). The CNR of the BSoutput is degraded about 1－3 dB compared tothat of BS input. From the link-budget analy-sis shown in Table 2, the CNRtotal for the BSanalog and digital signals transmission is 24.2dB when CNRsat is 25 dB. This also meansthat the CNR of BS signals degrade 0.8 dBafter the MMW link. The performance degra-dation in the experiment is slightly worse than


BS-3 (digital)BS-7 (analog)Channel

11.9±2.023.5±1.5Required CIR [dB]

12.5±1.018.75±0.75Required IP3 [dBm]

Table 8 Required CIR and IP3 for non-linear devices for BS-7 and BS-3

Transmitter and receiverFig.17

Experimental system setupFig.16

77

that of the analytical value. It can be thoughtthat the difference comes from the uneveninput power of BS signals or hardware imper-fections, while the uniform input power issupposed in our analysis.

CNR is more than 20 dB for MMW trans-mission of over 10 m, which meet the requiredCNR values of 14 dB for BS analog signalsand 11 dB for BS digital signals. In this trans-mission case, we did not observe any degrada-tion in video quality either with or without theMMW transmission link. From these results,we can conclude that our system is realistic.

6 Conclusion

This paper presents the design and per-formance of a MMW video transmission sys-tem using 60-GHz band for indoor BS signalstransmission. A selt-heterodyne scheme isused in the system. Based on the concept, wedesigned the system by using a CNR link-budget and an IM3 analysis. The transmitterand receiver setup and its characteristics arealso presented. To find a required CIR andIP3 of a power amplifier in the transmitter, weused an amplifier with a known gain and IP3in the experiment based on our subjectiveevaluation. The feasibility of the system isexperimentally verified by using a transmitterand receiver setup we developed. In theMMW transmission experiment over a dis-tance of 10 m, CNR was more than 20 dBwhen the transmission power was 10 dBm,and high-quality video signals were generated.


Power spectrum of BS-IFFig.18

Experimental CNR before and afterMMW transmission

Fig.19

78 Journal of the Communications Research Laboratory Vol.48 No.4 2001

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79Kiyoshi HAMAGUCHI et al.

Kiyoshi HAMAGUCHI, Ph. D.

Senior Researcher, Broadband Wire-less Access Systems Group, YokosukaRadio Communications Research Cen-ter

Multimedia Wireless Access Technolo-gy

Hiroyo OGAWA, Dr. Eng.

Leader, Broadband Wireless AccessSystems Group, Yokosuka Radio Com-munications Research Center


Yozo SHOJI, Ph. D.

Researcher, Broadband WirelessAccess Systems Group, Yokosuka RadioCommunications Research Center


Yasutake HIRACHI, Ph. D.

Fujitsu Quantum Devices Ltd.

Seiji NISHI, Ph. D.

Oki Electric Industry Co. Ltd.

Eiichiro KAWAKAMI

Oki Electric Industry Co. Ltd.

Eiji SUEMATSU

Sharp Corporation

Toshiya IWASAKI

SANYO Electric Co. Ltd.

Akira AKEYAMA

Telephon Public Corporation (NTT)

Youichi SHIMOMICHI

Hitachi Kokusai Electric Inc.

Takao KIZAWA

Japan Radio Company

Ichiro KUWANA

CANON INC

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