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In this paper, the performance evaluation of an asymmetric turbo code for different codec parameters have been done. The asymmetric turbo codes performances are compared with symmetric counter part of the turbo code. With proper selection of weight configuration, the turbo code can show better results in both water fall region as well as error floor region simultaneously. So, in some cases asymmetric...
In this paper, we describe the concatenation of Turbo/Convolutional codes with transmit and receive diversity schemes by using Space-Time Block Code. It is shown that, by using two transmit antennas and one/or two receive antenna, large coding gain for the bit error rate is achieved over the system without diversity. Simulation results show that, by using systems with transmit and receive diversity,...
In this paper, we propose a Distributed Turbo Product Code (DTPC) over cooperative network using block Bose Chaudhuri Hochquenghem (BCH) codes as component codes. The source broadcasts extended BCH coded frames to the destination and nearby relays. After decoding the received sequences, each relay constructs a product code by arranging the corrected bit sequences in rows and re-encoding them vertically...
Adopting Forward Error Correction (FEC), technologies for the laser communication system such as encode, interleaving, decode have been discussed in detail in the system. TURBO code is applied in this system which can reduce the system BER effectively. We make a detailed analysis of principle and performance of encoder, interleaver and decoder. Meanwhile, we compare their performance and computational...
According to the problem that the laser signal will produce serious distortion and BER increases affected by influences of the space channel environment including atmospheric turbulence, refraction and so on, the forward error correction (FEC) technique is adopted. Meanwhile, technologies for the laser communication system such as encode, interleaving, decode have been discussed in details. RS code...
The proposed singular value decomposition (SVD) aided spatial multiplexing (SM) based multiple-input-multiple-output (MIMO) system is capable of achieving a high bandwidth efficiency. The SVD operation effectively splits the MIMO channel into orthogonal eigen-beams having unequal bit-error-ratios (BERs). This property may be exploited for the transmission of speech, audio, video and other multimedia...
We experimentally demonstrate error-free (BER<10-9) transmission of full-duplex, asynchronous, 10 Gbps x 4user DPSK-OCDMA system on same wavelength using hybrid multi-port and SSFBG en/decoder.
This paper presents two algorithms to extend the MIMO-decoding capability of successive projection algorithm (SPA). The algorithms, called Flag-SPA and Relaxed-SPA, are based on different methods to avoid repeating the selected path in each iteration of the algorithm, the first by using a flag matrix, the second by assigning a high weight to a selected path. Equivalences with K-best algorithm in terms...
With recent developments in forward error correction (FEC) schemes, low-density parity check (LDPC) codes are gaining more and more popularity with their performance approaching to near Shannon's limits. In this paper a flexible LDPC codec is designed and optimized for OFDM transceivers in aeronautical channels. We considered OFDM based aeronautical communication systems and investigated en-route...
A novel turbo codec with hybrid modulation is proposed in this paper. Instead of brutal puncturing, we apply different modulation alphabets to the original not-punctured turbo coded bits, where the systematic bits are modulated by a lower order constellation and the parity bits are mapped by a higher order constellation, respectively. Numerical results show that the proposed scheme without puncturing...
We successfully demonstrate a spectral phase-encoded time-spreading (SPECTS) optical code-division multiple-access (O-CDMA) field trial on an 80.8-km link within the Boston-South Network (BOSSNET) using a fully-integrated, polarization-independent arrayed-waveguide grating (AWG)-based encoder/decoder. The subpicosecond pulse source is based on an ultrastable optical frequency comb generator employing...
The quality of transmission is very important in digital communication. However, in non-deterministic environment or different transmission message signal, bit error rate of PCM encoding methodologies maybe be varied according to different working condition or different signal source. Theoretically, the bit error rate of PCM encoding methodology can be computed by either mathematical or statistical...
We describe the transmission performance of acoustic OFDM. Acoustic OFDM is an OFDM system with free air links. We perform a simulation and a measurement to confirm that the transmission data rate of 0.9 kbps with BER below 0.1 can be obtained over distances to 4 m with angular offsets of up to 30 degrees. The system is robust to various noises and supports many audio codecs. The acoustic OFDM system...
In this study, we considered a MIMO system with available channel state information at the transmitter side and compared three known precoders based on different and pertinent criteria: the post processing signal-to-noise ratio (max-SNR), the mean square error between transmitted and received symbols (MMSE) and the minimum distance of the received constellation (max-dmin). We demonstrate that, alike...
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