The Experts below are selected from a list of 8751 Experts worldwide ranked by ideXlab platform

Friedrich K Jondral - One of the best experts on this subject based on the ideXlab platform.

  • a concept for a standard independent cognitive Radio Terminal
    European Wireless Conference, 2006
    Co-Authors: Volker Blaschke, Friedrich K Jondral
    Abstract:

    During the last years the dynamic spectrum management has been classified as a necessary modification in the spectrum allocation policy. Within the huge amount of publications dealing with this topic two main approaches can be pointed out. On the one hand the overlay system concept which allocate temporary unused frequency bands of established licensed systems. On the other hand the auction-based spectrum allocation schemes providing abstract Radio resource units to the user. These units have to be transmitted using the available Radio Access Technologies (RAT). Both concepts have in common that the mobile Terminal has to be adapted to the used frequency bands or Radio transmission standards, respectively. Therefore, the Cognitive Radio concept is considered to provide the required flexibility. In order to support a high adaptability of the mobile Terminal we present a concept for the physical layer structure of a Cognitive Radio. In addition to the classical parts of a mobile transmitter the Cognitive Radio specific functions like spectral observation and knowledge processing will be included.

  • cyclostationarity based air interface recognition for software Radio systems
    IEEE Radio and Wireless Conference, 2004
    Co-Authors: M Oner, Friedrich K Jondral
    Abstract:

    Reconfigurable software Radio equipment is seen as the next evolutionary step in mobile communications. One of the most important properties of a software Radio Terminal is that it is capable of using a wide range of air interface standards, providing a seamless interoperability between different air interface standards and an enhanced roaming capability. This multimode operation has to be supported by a number of key functionalities, one of which is the air interface recognition. A software Radio Terminal has to be able to detect, recognize and monitor the air interfaces available in the frequency environment. In our work, we propose exploiting the distinct cyclostationary properties of signals from different air interfaces as features for air interface recognition.

  • air interface recognition for a software Radio system exploiting cyclostationarity
    Personal Indoor and Mobile Radio Communications, 2004
    Co-Authors: M Oner, Friedrich K Jondral
    Abstract:

    Reconfigurable software Radio equipment is seen as the key technology in the evolution of mobile communications. One of the most important properties of a software Radio Terminal is that it is capable of using a wide range of air interface standards, providing a seamless interoperability between different standards and an enhanced roaming capability. One of the key functions supporting this multimode operation is the air interface recognition. A Software Radio Terminal has to be capable of detecting, recognizing and monitoring the air interfaces available in the frequency environment. In our paper, we propose exploiting the distinct cyclostationary properties of different air interface signals as features for air interface recognition.

Hiroki Harada - One of the best experts on this subject based on the ideXlab platform.

  • Software defined Radio prototype for W-CDMA and IEEE802.11a wireless LAN
    Vehicular Technology Conference 2004. VTC2004-Fall. 2004 IEEE 60th, 2004
    Co-Authors: Hiroki Harada
    Abstract:

    In this paper, the configuration and key technologies of a newly developed small-size software Radio Terminal for new generation seamless mobile communication systems are introduced. The Terminal consists of a common platform that includes an original field programmable gate array (FPGA) board with four FPGAs, a CPU board that has two CPUs and is operated by μITRON, and RF boards with open interfaces. Users have only to prepare software for the FPGAs and CPUs that can configure mobile communication systems that the users wish to operate. In addition, the common platform has control software that can change communication systems as users require. On the common platform, the W-CDMA and IEEE802.11a software that realizes the physical layer, data-link layer, and network (TCP/IP) layer has been established. Users can change communication systems by using programmed control software that receives users' requests, propagation characteristics, data errors, and so on from the RF board and FPGA board.

Shuji Tanaka - One of the best experts on this subject based on the ideXlab platform.

  • ultra wideband ladder filter using sh 0 plate wave in thin linbo 3 plate and its application to tunable filter
    IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2015
    Co-Authors: Michio Kadota, Shuji Tanaka
    Abstract:

    A cognitive Radio Terminal using vacant frequency bands of digital TV (DTV) channels, i.e., TV white space, strongly requires a compact tunable filter covering a wide frequency range of the DTV band (470 to 710 MHz in Japan). In this study, a T-type ladder filter using ultra-wideband shear horizontal mode plate wave resonators was fabricated, and a low peak insertion loss of 0.8 dB and an ultra-large 6 dB bandwidth of 240 MHz (41%) were measured in the DTV band. In addition, bandpass filters with different center frequencies of 502 and 653 MHz at 6 dB attenuation were numerically synthesized based on the same T-type ladder filter in conjunction with band rejection filters with different frequencies. The results suggest that the combination of the wideband T-type ladder filter and the band rejection filters connected with variable capacitors enables a tunable filter with large tunability of frequency and bandwidth as well as large rejection at the adjacent channels of an available TV white space.

  • wideband ladder filters fully covering digital tv band based on shear horizontal plate wave
    International Frequency Control Symposium, 2015
    Co-Authors: Michio Kadota, Shuji Tanaka
    Abstract:

    A cognitive Radio Terminal using vacant frequency bands of digital TV channels, i.e. TV white space, strongly requires a compact tunable filter covering a wide frequency range of the digital TV band. The authors proposed a new bandwidth- and frequency-tunable filter combining an ultra-wideband ladder filter and tunable band rejection filters. T-type and ρ-type ladder filters composed of ultra-wideband 0th shear horizontal mode (SH 0 ) plate wave resonators were fabricated on a submicron thick LiNbO 3 plate supported by a Si substrate. The wavelength ratio of the parallel/series resonators in the ladder filters was changed as a design parameter. As a result, ultra-large 6 dB bandwidths of 41 to 51%, which fully cover the digital TV band, were measured. The lowest peak insertion loss was low as 0.8 dB. The ultra-wideband ladder filter is useful for the above-mentioned new tunable filter for digital TV cognitive Radio communication.

Koichi Ito - One of the best experts on this subject based on the ideXlab platform.

  • fdtd calculations of specific absorption rate in fetus caused by electromagnetic waves from mobile Radio Terminal using pregnant woman model
    IEEE Transactions on Microwave Theory and Techniques, 2008
    Co-Authors: T Togashi, Soichi Watanabe, Tomoaki Nagaoka, S Kikuchi, Kazuyuki Saito, Masaharu Takahashi, Koichi Ito
    Abstract:

    Since the diversification of the electromagnetic (EM) environment is spreading, it is essential to estimate the EM energy absorption rate [specific absorption rate (SAR)] of a pregnant woman's body and her fetus under various exposure situations. This paper presents the EM dosimetry in a pregnant woman in proximity to a mobile-phone Terminal using the numerical model of a woman in her seventh month of pregnancy (composed of 56 organs, which includes the intrinsic organs of a pregnant woman) based on the high-resolution whole-body voxel model of a Japanese adult woman. It was found that the SAR in the fetus strongly depends on the geometrical relationship between the fetus and the EM source, while the averaged SAR for the fetus is always lower than the RF safety guidelines under the exposure conditions investigated in this paper.

Hakan Ali Çirpan - One of the best experts on this subject based on the ideXlab platform.

  • Signal detection based on linear trend in the noise-originated eigenvalues of the correlation matrix for cognitive Radio
    2011 IEEE 19th Signal Processing and Communications Applications Conference (SIU), 2011
    Co-Authors: Hakan Ali Çirpan
    Abstract:

    Cognitive Radio introduces the opportunistic usage of unoccupied frequency bands by unlicensed users without disturbing the Quality-of-Service of the licensed users. The first problem to be solved by a Cognitive Radio Terminal is sensing the signals of the licensed users. In our study, we offer a new sensing method based on the eigenvalue decomposition of the covariance matrix of received signals. The method defines a test statistic on the distribution of eigenvalues to give a “Yes or No” decision about the signals in the band-of-interest. The main idea behind the method is that eigenvalues belonging to the noise subspace of the covariance matrix tend to exhibit a linear trend of decrease in case of limited number of samples of the received signals. The proposed method presents a realistic approach, and due to its robustness to sensing without suffering from noise power uncertainty, it has advantages against the energy level comparison based detectors that are highly influenced by the noise.