20,311 research outputs found
Frequency-Domain Turbo Equalisation in Coded SC-FDMA Systems: EXIT Chart Analysis and Performance
Full text linkIn this paper, we investigate the achievable performance of channel coded single-carrier frequency division multiple-access (SC-FDMA) systems employing various detection schemes, when communicating over frequency-selective fading channels. Specifically, three types of minimum mean-square error (MMSE) based frequency-domain (FD) turbo equalisers are considered. The first one is the turbo FD linear equaliser (LE). The second one is a parallel interference cancellation (PIC)-assisted turbo FD decision-feedback equaliser (DFE). The final one is the proposed hybrid interference cancellation (HIC)-aided turbo FD-DFE, which combines successive interference cancellation (SIC) with iterative PIC and decoding. The benefit of interference cancellation (IC) is analysed with the EXtrinsic Information Transfer (EXIT) charts. The performance of the coded SC-FDMA systems employing the above-mentioned detection schemes is investigated with the aid of simulations. Our studies show that the IC techniques achieve an attractive performance at a moderate complexity
First-hop-quality-aware dynamic resource allocation for amplify-and-forward opportunistic relaying assisted SC-FDMA
No full textIn this paper we exploit the benefits of the diversity gains arising from a cluster of opportunistic relays (OR) and from the independently fading subcarriers of multiple users. Our goal is to improve the energy-efficiency of the OR assisted single-carrier frequency-division multiple-access (SC-FDMA) uplink using amplify-and-forward (AF), where the direct transmission (DT) link is unavailable. By assuming that the pilot aided channel quality information (CQI) of all the users may be exchanged amongst the cooperating relays, we propose two joint dynamic resource allocation (DRA) schemes based on the so-called ’first-hop quality awareness’. Our results demonstrate that compared to the DT benchmark, the proposed joint DRA schemes are capable of achieving a power reduction of 10dB for a single-antenna base station (BS) receiver, albeit for a multi-antenna BS the power-reduction remains more modest
Energy-Efficient Channel-Dependent Cooperative Relaying for the Multiuser SC-FDMA Uplink
Full text linkStudi tentang Karakteristik SC Geomagnet sebagai Upaya Awal Mengembangkan Sistem Deteksi Otomatis Badai Geomagnet
No full textSC (sudden commencement) dicirikan oleh kenaikan mendadak intensitas medan magnet. SC dalam makalah ini dibedakan menjadi 2 tipe berdasarkan orientasi arah IMF Bz .dengan notasi SC(SI) dan SC(SSC). Tipe SI (sudden impulse) adalah SC yang tidak disertai badai geomagnet dan umumnya berkaitan dengan arah utara IMF, sedanghn tipe SSC (storm sudden commencement) adalah SC yang disertai badai geomagnet dan umumnya berkaitan dengan arah selatan IMF. Untuk mengetahui karakteristik masing-masing SC (bail SI maupun SSC) maim dalam kegiatan ini akan dilakukan identifikasi ke-3 kriteria SC bail tipe SC(SI) maupun tipe SC(SSC) yaitu amplitudo, perioda dan gradiennya menggunakan data komponen H stasiun Biak tahun 1994-1998. Setelah diidentifilcasi kemudian dilakukan analisis menggunakan metode analisis statistik yaitu analisis distribusi data. Hasil analisis diperoleh bahwa SC yang tidak berkaitan dengan badai geomagnet (SC(SI)) memiliki ciri-ciri umum amplitudonya terdistribusi > 8nT, periodanya terdistribusi 2.2nT/menit. Sedangkan untuk SC yang berkaitan dengan kejadian badai geomagnet (SC(SSC)) memiliki ciri-ciri umum amplitudonya terdistribusi > lOnT, periodanya terdistribusi 2.7nT/menit. Hasil di atas merupakan hasil awal untuk selanjutnya dapat digunakan dalam deteksi SC terutama yang terkait dengan badai geomagnet (SC(SSC)) dan berikutnya mengembangkan sistem deteksi otomatis badai geomagnet.Hal. 127-13
Improved DFT-Based Channel Estimation for TDS-OFDM Wireless Communication Systems
No full text[[abstract]]This paper proposes an improved discrete Fourier transform (DFT)-based channel estimation technique for time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) communication systems. The proposed technique, based on the concept of significant channel tap detector (SCTD) scheme, can effectively improve the system performance of TDS-OFDM systems. The correlation of two successive preambles is employed to estimate the average noise power as the threshold for obtaining the SCTD threshold estimation error and loss path information in large delay spread channel environments. The proposed estimation scheme roughly predicts the noise power in order to choose the significant channel taps to estimate the channel impulse response. Some comparative simulations are given to show that the proposed technique has the potential to achieve bit error rate performance superior to that of the conventional least squares channel estimation[[note]]SC
Automatic Viewpoint Dependent Representation of 3-D Object Based on Extended Boundary Model
No full textPower-Efficient Opportunistic Amplify-and-Forward Single-Relay Aided Multi-User SC-FDMA Uplink
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