14 research outputs found

    Cognitive Radio Dynamic Access Techniques

    Get PDF

    Research on Cognitive Radio within the Freeband-AAF project

    Get PDF

    Pengendalian Banjir Sungai Dombo Sayung Kabupaten Demak

    Full text link
    Flooding is one of the disasters that often occur in Demak Regency especially Sayung area, Karang Asem, and Mranggen. The impact of floods can not be ignored, such as damage to city infrastructure, and socio-economic losses in the region Demak regency occur due to inundation and inundation long time. Dombo Sayung River Flood Control Objectives is to reduce the occurrence of floodwaters in the area Demak regency using structural measures. The flood control study using a return period of 100 years. With a return period flood hydrograph Q100th Dombo Sayung River analyzed using HEC-HMS software. While the hydraulics analysis were analyzed using the HEC-RAS software. The analysis shows a cross-existing conditions Dombo Sayung River insufficient to drain the flood discharge Q100th of 343.0 m3/sec with the effect of the floods, so it needs to repair the river cross-section an attempt to enlarge the drainage of the river

    Analisis Sumber dan Penggunaan Dana pada Badan Pengelola Keuangan dan Barang Milik Daerah Kota Manado

    Full text link
    Analisis sumber dan penggunaan dana atau yang disebut dengan analisis aliran dana, merupakan alat finansial yang sangat penting bagi manajemen keuangan, disamping alat finansial lainnya. Tujuan penelitian untuk mengetahui bagaimana dana digunakan dan bagaimana dana tersebut dibelanjakan. Penelitian ini untuk mengetahui Sumber dan Penggunaan Dana Pada Badan Pengelola Keuangan dan Aset Daerah Kota Manado selama dua tahun terakhir (2013-2014). Penelitian ini termasuk jenis penelitian deskriptif. Hasil penelitian menunjukkan bahwa analisis sumber dan penggunaan modal kerja pada BPKBMD ini menggunakan modal kerja yang berasal dari pendapatan asli daerah yang terdiri dari hasil pengelolaan kekayaan daerah yang disahkan serta pendapatan asli daerah lainnya. Dana BPKBMD ternyata masih belum mampu untuk membiayai belanja langsung dan belanja tidak langsung dilihat pada pembahasan diatas yaitu pada tahun 2013 BPKBMD kekurangan modal kerja dan begtu juga pada tahun 2014. Manajemen sebaiknya melakukan perencanaan dana sebaik mungkin sehingga tidak mengalami kekurangan dana dan menggunakan manajemen pembelanjaan dana secara tepat dalam membuat kebijakan dan mengambil keputusan dalam hal penentuan besarnya kebutuhan dana bagi organisasi sendiri. Kata kunci: sumber dan penggunaan dana, modal kerja

    Adaptive Baseband Processing Techniques for Cognitive Radio Systems

    No full text
    Cognitive Radio is a new paradigm in the wireless communications. It puts the intelligence and awareness dimension to the radio communication system. A Cognitive Radio system will be aware of the changing condition in its environment. The awareness in this thesis is related to the spectrum and the channel stipulation. By intelligent learning and understanding from the environment, a Cognitive Radio device will adapt its transmission parameters to the changing environment. The objective of a Cognitive Radio system is to have a reliable communication and efficient spectrum utilization. Although most of the spectral ranges are already licensed, studies and measurements have shown that most of the time the spectrum is not fully occupied, and even some bands are rarely occupied. The congestions happen because of the existing poor spectrum access technique. This condition raises the opportunity to rent or to access the spectrum while the licensed user is in idle condition or by having the Cognitive Radio side by side with the licensed users band occupying the spectrum holes. In this way, the spectrum is utilized in a more efficient way. The challenging problem is to settle a “win-win” co-existence between the Cognitive Radio, which is the rental system, with the legacy licensed system. Spectrum pooling has been proposed in the literature as a technique of sharing the spectrum with the licensed system by using the Orthogonal Frequency Division Multiplexing (OFDM) as modulation technique. Some of the OFDM carriers located in the licensed user’s band will be deactivated in order not to interfere the legacy system access. Due to this flexibility, the OFDM is considered as a proper modulation technique to be applied to a Cognitive Radio system. Deactivation of more carriers adjacent to the licensed user’s band, as well as windowing and several signal processing techniques could reduce the interference contribution of the OFDM based Cognitive Radio system to the licensed users signal. These techniques are studied and presented in this dissertation. The spectrum pooling technique could only work upon the reception of the accurate spectrum occupancy information. The spectrum occupancy information is derived from a spectrum sensing module. Spectrum sensing necessitates such a sophisticated module and requires a proper attention. This thesis does not focus on the spectrum sensing module, but rather it is assumed that the spectrum occupancy information is available and accurate. The work on spectrum sensing is conducted by out partner at the Twente University . Following the objective of Cognitive Radio to have reliable communications, the observation or emphasis of the technique is not only on the licensed users side but also on the rental user. Besides assuring the reliable communications of the licensed system, the target Quality of Service (QoS) of the Cognitive Radio system should be attained. The practical parameters to be observed are the Bit Error Rate (BER) and the bit rate of the system. The application of OFDM with spectrum shaping for the purpose of reducing the interference contribution to the licensed system can be achieved with the cost of self QoS degradation. Results from literature have shown that application of adaptive bit loading could enhance the BER of an OFDM system. By adaptive bit loading, the bits are allocated to each of the OFDM carrier intelligently according to the channel condition by setting the target BER and bit rate of the overall system. In this work, we propose to combine the adaptive bit loading with the spectrum shaping to preserve the Cognitive Radio system’s QoS. The impact of this combination on the OFDM Peak to Average Power Ratio (PAPR) growth is evaluated through simulations. There is a growing interest in replacing the Fourier transform in OFDM with wavelet basis functions. The technique is termed as the Wavelet Packet Multicarrier Modulation (WPMCM). Investigations reported in literature have presented the evaluation of WPMCM and compared the results with OFDM. Following the successful application of a frequency selective wavelet in the Ultra Wide Band system, in this dissertation we evaluate the suitability of the frequency selective wavelet in WPMCM combined with the spectrum pooling concept to be applied to the Cognitive Radio system. As the efficient spectrum utilization is one of the major objectives of Cognitive Radio, it is reasonable to include Multiple Input Multiple Output (MIMO) to the Cogntive Radio system. This subject is studied in this thesis and the performance of MIMO in the OFDM and WPMCM based Cogntive Radio system is evaluated. Channel estimation is the crucial module in every OFDM system. We propose an effective channel estimation scheme based on optimum pilot patterns of conventional OFDM using virtual pilots and apply it to Cognitive Radio systems. The virtual pilots are derived from the combination of the linear interpolation/extrapolation between two real pilots with the so called decision directed method. Without loss of generality we use the Wiener filter as the channel estimation technique due to its efficient and straightforward method in utilizing the channel correlation property according to the distance between pilots and data. First we adopt the Single Input Single Output (SISO) OFDM based Cognitive Radio system, and then we expand the scheme to the MIMO application. Beside OFDM and WPMCM based Cognitive Radio system, recently Transform Domain Communication System (TDCS) and Wavelet Domain Communication System (WDCS) have been introduced as promising modulation techniques for Cognitive Radio application. TDCS and WDCS have bit rate limitations. As an effort to enhance the bit rate of TDCS and WDCS, we propose to add an extra embedded symbol to TDCS and WDCS. We analyze the impact of the embedded symbol on the conventional TDCS and WDCS data detection. The impact of the embedded symbol on the data detection in a multi-user environment, which is inherently supported by the conventional TDCS and WDCS, is observed. In addition, we also evaluate the performance of the TDCS with an embedded symbol in the MIMO system. As a sort of verification platform for Cognitive Radio we proposed a practical Demonstrator that involved a spectrum scanning module and baseband processing transceiver module. The spectrum sensing is employed by the Universal Software Defined Radio Peripheral (USRP) while the baseband processing transceiver module is applied to an FPGA Development board. The current made Cognitive Radio verification platform is simple and still has a limited feature. While further developments are required in this field, details of this effort are also provided in this thesis.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc

    Cognitive Radio with Single Carrier TDCS and Multicarrier OFDM Approach with V-BLAST Receiver in Rayleigh Fading Channel

    No full text
    This article presents the performance comparison of TDCS and OFDM based cognitive radio for MIMO system using VBLAST receiver architecture to reconstruct the transmitted data. The interference avoidance performance in terms of BER and bitrate are improved by adding multiple antennas to the system and the use of V-BLAST technique at the receiver. The results show the most promising interference avoidance technique combined with MIMO V-BLAST architecture to be applied in the CR system.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc

    Cognitive radio modulation techniques

    No full text
    TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
    corecore