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Displaying 1-20 of 20 articles from this issue
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Article type: Cover
Pages Cover1-
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSDownload PDF (14K) -
Article type: Index
Pages Toc1-
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSDownload PDF (85K) -
Takashi INOUE, Yoshio KARASAWAArticle type: Article
Pages 1-6
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSThe CNR variation characteristics after the diversity combining (the maximal-ratio combining) under Rayleigh fading environments can be evaluated by use of the eigenvalues of the covariance matrix for branch signals. However, this technique was available only when the eigenvalues had different values each other. In this report, we proposed a calculation method for deriving the cumulative distribution function of the CNR when the eigenvalues are composed of multiple groups ; the eigenvalues in each group had the same value. It was confirmed that the cdfs obtained by the proposed method and the numerical simulation agreed very well. The accuracy of the calculation results was also discussed.View full abstractDownload PDF (600K) -
Yoshio KARASAWA, Takashi INOUE, Yukihiro Kamiya, Satoshi DENNOArticle type: Article
Pages 7-12
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSWe have proposed a new concept of kaleidoscopic antenna, we call it "software antenna, " which pursues a realization of required performance under minimum software/hardware resources. The software antenna instantly reconfigures itself adapting its software and hardware to changes in the time-varying radio-environment. In this paper, we describe how to categorize the radio-environment which is one of the most important functions of the antenna. Relation between categorized environments and adaptive signal processing algorithms is discussed.View full abstractDownload PDF (678K) -
Kazumi NOGAMI, SHINICHI Fujiwara, Makoto OOTANI, Hiroshi FUJITA, Tomoh ...Article type: Article
Pages 13-18
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSSo far, to service on 2 channels with very separated frequency in broadcast, we have been built a new tower with high costs. But in the moving duration of digital terrestrial, there is high possibility to be required for one media to service on 2 channels at the same time. Then, we will introduce a new method that can be solved this problem using 'Reflector-Common antenna' assumed 4-sided with 90 degrees and we will report its simulation and experimental results.View full abstractDownload PDF (774K) -
Y. Ojiro, Y. Iitsuka, S. Kogiso, H. Kawakami, G. Sato, S. SumihiroArticle type: Article
Pages 19-23
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSThe characteristics of the batwing radiator, which is the heart of the superturnstile antenna system for VHF-TV broadcasting, are wide bandwidth. We investigate the modified batwing antenna for UHF used as the digital terrestrial broadcasting. In this paper, the characteristics of the 2-element modified batwing antenna with the reflector are calculated. This antenna is connected with each elements by a parallel feed line and fed at the center of this line. The higher gain and the broad bandwidth compared with the 2-element original twin loop antenna are obtained.View full abstractDownload PDF (425K) -
Toshihide HAYASHIDA, Seizo SEKIArticle type: Article
Pages 25-30
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSThe characteristics of the decision feedback carrier recovery loop (DFL) and the Costas carrier recovery loop (Costas Loop) for a conventional QPSK signaling were compared and evaluated experimentally. The DFL and the Costas Loop was respectively applied to the experimental QPSK system where the carrier frequency is 10.7 MHz and the simbol rate is 64 kS/s. The performance of the DFL and the Costas Loop was investigated through measurements of the signal-to-noise ratio of the recovered carrier, the lock range, the capture range and the bit error rate. A result was obtined that the capture range of the DFL did not exist due to the false lock, while the signal-to-noise ratio and the bit error rate showed more excellent performance than those of the Costas Loop. Therefore a circuit for avoiding the false lock in the DFL was proposed. With the proposal circuit, it was showed that the false lock in the DFL could be avoided.View full abstractDownload PDF (629K) -
Suguru NAKADA, Masao NAKAGAWAArticle type: Article
Pages 31-36
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSA variable length code often causes loss of synchronization due to bit error in wireless transmission, so that burst errors occur in the received codewords. In this paper, we proposed a wireless transmission technique of variable length code utilizing M-ary/SSMA. Since the information represented by a variable length code is transmitted as the combination of some spreading codes in the proposed system, the synchronization of the codewords is maintained. Besides, this system does not require many spreading codes per user. This paper evaluates the performance of the proposed system over a Rayleigh fading channel.View full abstractDownload PDF (683K) -
Masaaki KOIWA, Seizo SEKIArticle type: Article
Pages 37-42
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSInterchannel interference (ICI) in a roll-off band-limited QPSK signal transmission where the carrier frequency is 10.7MHz and the symbol rate is 64kS/s was measured and analyzed. Bit error rate (BER) was measured as a function of carrier-to-noise ratio (CNR) when ICI existed. But the experimental results didn't agree well with the calculated values under the assumption that the ICI-signal is the thermal noise. So, the amplitude distribution of ICI signal and the thermal noise were measured and evaluated. BER was calculated by using the amplitude distribution, and the good agreement of the calculated results and the measured values was confirmed.View full abstractDownload PDF (578K) -
Kentaro HIROHASHI, Hirohito SUDA, Fumiyuki ADACHI, Heiichi YAMAMOTOArticle type: Article
Pages 43-48
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSWe evalute impact of spreading bandwidth expansion on DS-CDMA reverse link by computer simulation with data rate and the number of the propagation paths as parameters. The evaluted bandwidths of spreading are 1.25,5,10,20MHz. As spreading bandwidth increases, the capasity improves at least from 15% to 22%. There are two reasons, one is a propagation paths increasing effect and the other is received interference power smoothing effect. It was also shown that the reverse link capasity is improved by spreading bandwidth expansion under non-continuous transmit user condition.View full abstractDownload PDF (560K) -
Hideyuki MATSUTANI, Masao NAKAGAWAArticle type: Article
Pages 49-54
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSIn multi-carrier direct sequence code division multiple access (MC-DS-CDMA), narrow-band DS signals are parallel transmitted in several sub-carriers and each signal suffers from flat fading. Hence, the effect of inter-chip interference can be eliminated. However, no path diversity gain can be obtained. In this paper, as a method to solve this problem, we propose to apply frequency spread coding to MC-DS-CDMA achieving explicit frequency diversity without reduction of bandwidth efficiency. The computer simulation results show its effectiveness in terms of the average bit error rate in a down-link of a single cell environment. In addition, the proposed system is also compared with a multi-carrier CDMA system applying spreading codes in frequency domain and a DS-CDMA system using RAKE revier.View full abstractDownload PDF (748K) -
Shuta UWANO, Yoichi MATSUMOTO, Masato Mizoguchi, Masahiro UMEHIRAArticle type: Article
Pages 55-61
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSOrthogonal frequency division multiplexing (OFDM) signals suffer from nonlinear distortion at the transmitter, in particular high-power amplifiers. As a peak-to-average power ratio (PAPR) reduction technique, Constant Peak-power OFDM (CP-OFDM) has been proposed, which can fix the envelope-peak amplitude to a constant value while maintaining linearity of the IFFT outputs. Advancing this technique, this paper proposes a nonlinear distortion compensation method by combining it with baseband predistortion in OFDM systems. This paper presents simulation and experimental results which verify that this method decreases out-of-band emission and adjacent channel interference.View full abstractDownload PDF (693K) -
Osamu MUTA, Yoshihiko AKAIWAArticle type: Article
Pages 63-68
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSAs a solution to reduce peak-to-mean power ratio (PMPR) in Multicarrier transmission system, it has been proposed that entire part of IDFT block in which envelope-peak amplitude (EPA) is detected is decreased by a appropriate constant. However, this technique loses the spectral efficiency for redundancy of time-waveform shaping consequently. In this paper, we propose a peak-power-suppression (PPS) scheme which achieves band-limitation by filtering the individual sub-channel before multiplexing and reduces average transmit pulse energy at filter input in the same way as the above. The normalized peak factor can be reduced by about 6 dB by applying the PPS scheme that does not significantly degrade BER performance in fading condition. The proposed scheme with adaptive transmit power control is effective for economizing transmit and reducing PMPR.View full abstractDownload PDF (575K) -
Y. MATSUMOTO, S. MUNETA, N. MOCHIZUKI, M. UMEHIRAArticle type: Article
Pages 69-74
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSUsing the OFDM parameters for broadband wireless access systems, this paper first clarifies the performance disparities between the sets of modulation, detection and FEC rates, assuming the same information rate : specifically, 8PSK and 16QAM for coherent detection, and D8PSK and 16DAPSK for differential detection are examined. It is revealed that 8PSK achieves substantial required-E_b/N_o performance improvements over the others. Moreover, differential detection incurs severe PER performance degradation in non-linear environments and long-multipath-existing environments. For actual application of coherent detection, this paper proposed a RLS-algorithm-based initial-equalization (IE) scheme, with practical implementation in mind. It is revealed that the proposed scheme exhibits excellent PER performance when the preamble of 2 OFDM symbols or more is allowed for coherent detection. It also revealed that the simple frequency-domain IE scheme can be a practical choice when the single-FFT- period preamble must be used.View full abstractDownload PDF (633K) -
Kazuyuki Sakoda, Takushi Kunihiro, Chihiro Fujita, Hideki Iwami, Mitsu ...Article type: Article
Pages 75-80
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSFrequency Hopping system based on PDC system is examined. TDMA frame length of PDC system (half-rate) last 40[msec], which consist of 6 TDMA structure. PDC does not apply interleave among slots, or strong coding either. Antithetically, here, we define Frequency Hopping system whose TDMA frame is shorter than that of PDC, and which achieve interleave among slots, then evaluate the defined system. Additionally, strongly tied coding and highly accurate transmit power control is implemented to this system. In this paper, this system's simulation results both at link level, and system level is introduced. Even though there are some problems to realize this frequency hopping system, we have found that frequency hopping system has capability to achieve much higher capacity than existing system, in principle.View full abstractDownload PDF (722K) -
Kento MIYAOKU, Masaki YAMASHINAArticle type: Article
Pages 81-86
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSARQ transmission scheme over wireless channel causes transmission time delay due to retransmission of packets. When multmedia IP packets holding voice data or video data are transmitted by this scheme, the transmission delay would cause conspicuous degradation of voice or video quality. An ARQ scheme suitable to a stable multimedia IP packet transmission over wireless channels is proposed. This scheme limits the number of retransmission for lost packets according to the relationship between data volume in a buffer and decoding speed at a receiver side. A computer simulation assuming PHS channel and H.263 video packet transmission confirms that the proposed scheme can reduce the transmission time delay of image frames into about 50% (when throughput is 98% of decoding speed) of that offered by the conventional ARQ scheme, permitting a slight image degradation.View full abstractDownload PDF (804K) -
Yoshitsugu SHIMAZU, Hidekazu MURATA, Susumu YOSHIDAArticle type: Article
Pages 87-92
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSIn recent years, vehicle-to-vehicle communicaion systems which give assistance for safe driving have received a great deal of public attension. Millimeter wave has been examined as the primary candidate for the communication medium in vehicle-to-vehicle communications. However, it is impossible to form a direct communication link with vehicles located behind other vehicles due to the sharp directivity of the medium. Therefore, the packet relay function is required in vehicle-to-vehicle communications. In this paper, a packet relay timing control protocol for vehicle-to-vehicle communications is proposed. In this protocol, the packet relay timing of each car is self-controlled. Simulation results show that the proposed protocol outperforms the flooding protocol at the packet unreachable probability.View full abstractDownload PDF (732K) -
Seigo NAKAO, Hidekazu MURATA, Susumu YOSHIDAArticle type: Article
Pages 93-98
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSIn recent years, intelligent transport systems (ITS), especially vehicle-to-vehicle communication systems, have attracted a great deal of public attention. Vehicle-to-vehicle communication and ranging system using spread spectrum (SS) technique called "SS Boomerang" transmission system has been proposed. However, when many vehicles are transmitting SS signals, transmit power control is essential due to near-far problem. Since it is very difficult to control transmitting power ideally in such an environment, time division multiple access (TDMA) is employed in this paper. Then, the effect of co-channel interference canceller is evaluated for vehicle-to-vehicle communications.View full abstractDownload PDF (755K) -
Akihiro Sato, Tomoaki Ohtsuki, Iwao SasaseArticle type: Article
Pages 99-104
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSNon-directed indoor infrared wireless system is a candidate for high-speed indoor wireless networks. However, shadowing caused by obstacles induces frequent blocking or degradation of total SNR. In this study, we evaluate the effects of shadowing by human bodies on multi basestations system. We compare the repetition system, which send the same data from each basestations sequentially, and the site diversity system, which send the same data from each basestations on the same time.View full abstractDownload PDF (843K) -
Article type: Appendix
Pages App1-
Published: November 27, 1998
Released on J-STAGE: June 23, 2017
CONFERENCE PROCEEDINGS FREE ACCESSDownload PDF (78K)
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