In this paper, channel estimation for Spatial Multiplexing (SM) is investigated for MIMO-OFDM system. Due to the channel characteristic of the transmission system is always changed by the time and its importance in wireless transmission to reconstruct the transmitted signals, the channel needs to be known as well as possible. Pilot symbols are used to gather knowledge about the channel and try to estimate it. The channel estimation based on the pilot symbol is called pilot aided channel estimation. In this research, Least Square (LS) method was chosen for initial channel estimation. By using applicable proposed system design, channel state information is estimated through the use of channel information before in subcarriers with no pilot symbols. Zero forcing (ZF) algorithm is used to detect and separate the received signal. The result shows that channel estimation would be better by increasing SNR. Normalized Mean Square Errror (NMSE) value of the channel reached 5xlO· 5 for SNR 25 dB. The value of BER reached 3xlO· 4for SNR 25 dB. The estimated channel capacity has the values that closed to the known channel capacity.

Radio over fiber (RoF) system with the coherent detection offers high linearity for the transparent transport of high-frequency microwave signals, and better receiver sensitivity compared with intensity-modulated direct detection systems. The purpose of this paper is to analyze the performance of digital modulation for coherent detection of orthogonal frequency division multiplexing (OFDM) scheme on RoF system at 10 Gbps up to 100 km fiber length. The results show that coherent detection of OFDM-RoF system with 16 quadrature amplitude modulation (16-QAM) has the value of  bit error rate (BER) and the symbol error rate (SER) is very low and its constellation is better compared with other modulation formats (4-QAM, quadrature phase shift keying (QPSK), 8-PSK and 16-PSK), which BER 16-QAM is 0.053 and SER is 15.7%. The results also show that BER value of 4-QAM and QPSK relatively similar to fiber length variations. In general, an increasing value of the BER and SER for each modulation format are almost equal to the fiber length of 60-70 km (Region I and II). However, there is a significant increase in the value of BER in fiber length of 80-100 km (Region III. A and III. B) for the modulation of 4-QAM, QPSK, 8-PSK, and 16-PSK.

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DVB-T2 (Digital Video Broadcasting Terrestrial Second Generation) reception requires a sufficient quality of the received signal. <em>CNR</em> (carrier-to-noise ratio) and <em>BER</em> (bit-error-rate) are two of quantities describing the quality. This paper presents the range of each quantity providing a successful reception based on real data obtained by field-measurements. This data was collected from MO (mobile-outdoor) and SI (stationary-indoor) receiving-systems capturing signal sent by some on-air trial transmitters broadcasting services focused on the fixed-receivers. The result indicated that the successful and failed receptions were split into two quite separated (concentrated) ranges of post-decoded <em>BER</em> and therefore a boundary distinguishing them could be prominently defined. In contrast, they were spread in a wide common range of <em>CNR</em> and pre-decoded <em>BER</em>. Furthermore, the boundary that corresponded to this last quantity was ambiguous. In the case of MO reception as numerical examples, the two split ranges of post-decoded <em>BER</em> were less than about 10^-5 and more than about 2.7 × 10^-4 for the successful and failed receptions, respectively, whereas <em>CNR</em> as high as about 14 dB could be viewed as a soft boundary distinguishing these both reception-success conditions.

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Abstract-In many countries, migration from analog to digital in television (TV) broadcasting technology is being in progress. Indonesia has adopted DVB-T2 (Digital Video BroadcastingTerrestrial Second Generation) as the standard of free-to-air digital TV (DTV) broadcasting system. Frequency selective fading due to multipath propagation affects the reception of this terrestrial radio communication system. This paper presents those effects on reception of DVB-T2 signal from the Yogyakarta transmitting stations. The presence of these effects were identified experimentally, based on several received-signal describing quantities obtained from some field-observations on indoor/outdoor stationary/mobile receptions. Examples of these quantities are spectrum flatness measurement (SFM), signal quality (SQ) versus signal intensity (SI), power level (P) versus carrier-to-noise ratio (CNR), CNR versus modulation error ratio (MER), local variation of reception-success, and received data packet. Several numerical examples are: (1) SFM achieved as high as about 0.7 and 0.9 for indoor and outdoor, respectively, and (2) spatial-probability of reception-success at an indoor receiver location varied from 40,06 % to 81,85 %, approximately.Intisari-Di beberapa negara, migrasi dari analog ke digital dalam teknologi penyiaran TV sedang berlangsung. Indonesia telah mengadopsi DVB-T2 sebagai standar untuk penyiaran DTV teresterial tak-berbayar. Pudaran selektif frekuensi sebagai akibat propagasi lintasan-jamak memengaruhi penerimaan sistem komunikasi nirkabel teresterial ini. Makalah ini menyajikan pengaruh tersebut pada penerimaan isyarat DVB-T2 dari stasiun pancar Yogyakarta. Kehadiran pengaruh ini diidentifikasi secara eksperimental, berdasar sejumlah besaran pendeskripsi isyarat-terima yang diperoleh dari pengamatan-lapangan pada penerimaan stasioner dan bergerak, di dalam dan luar ruang. Contoh besaran-besaran tersebut adalah SFM, nisbah SQ/SI, nisbah P/CNR, nisbah MER/CNR, keberhasilan penerimaan di lokasi penerima, dan jumlah paket data yang diterima. Contoh sebagian hasil numeris adalah: (1) SFM mencapai sekitar 0,7 dan 0,9, berturut-turut untuk dalam dan luar ruang, (2) peluang keberhasilan penerimaan di suatu lokasi penerima dalam ruang bervariasi dari sekitar 40,06 % hingga 81,85 %.Kata Kunci-DVB-T2, lintasan-jamak, SFM, CNR, MER.