scholarly journals Quaternion Codes in MIMO System of Dual-Polarized Antennas

2021 ◽  
Vol 11 (7) ◽  
pp. 3131
Author(s):  
Sajid Ali ◽  
Sara Shakil Qureshi ◽  
Syed Ali Hassan
Keyword(s):  
Mimo System ◽  
Block Code ◽  
System Model ◽  
Polarization Diversity ◽  
Time Block ◽  
Orthogonal Designs ◽  
Dual Polarized ◽  
Point To Point ◽  
Recursive Techniques ◽  
Bounded Below

The use of quaternion orthogonal designs (QODs) to describe point-to-point communication among dual-polarized antennas has the potential to provide higher rate orthogonal and quasi-orthogonal complex designs exploiting polarization diversity among space and time diversities. Furthermore, it is essential to have a space time block code (STBC) which offers a linear and decoupled decoder which quasi-orthogonal designs fail to attain. In this paper, we show how the realm of quaternions unexpectedly offers us a possible solution and codes obtained from quaternion designs mostly achieve both linear and decoupled decoders. This motivated us to perform an indispensable search for QODs such that the code rate is bounded below by 1/2 and does not sharply decrease as the number of transmit antennas increases. It is shown that three famous recursive techniques do not satisfy this criteria and their code rates decrease rather rapidly. Therefore, we propose another method of constructing quaternion designs suitable for any number of transmit antennas and verify that these attain linear and decoupled decoders with the system model based on quaternionic channel. It is shown that such designs outperform others in terms of transmit diversity, code rates and the optimality of the proposed decoder is validated through simulation results.

scholarly journals Improvement of FER using Differential Space-Time Block Code

2020 ◽  
Vol 8 (5) ◽  
pp. 4144-4148
Keyword(s):  
Communication Systems ◽  
Mimo Systems ◽  
Mimo System ◽  
Radio Channel ◽  
Block Code ◽  
Space Time ◽  
Coherent Detection ◽  
Doppler Spectrum ◽  
Time Block ◽  
Space Time Block Code

Over recent years, various modulation and coding techniques have been proposed in MIMO wireless communication systems. A MIMO system uses the concept of spatial diversity which is very successful and promising technique. When a coherent transmission system is considered, the estimation of radio channel impulse response is done precisely. In MIMO systems, the radio channel is estimated among every transmitting and receiving antennas such that the complexity can be increased. For this reason, in MIMO systems differential modulation schemes are estimated. A Differential Space-Time Block Code (DSTBC) is useful in the Raleigh fading channel as they do not require channel estimates. Space-time coding with MIMO antennas at transmitting and receiving reduces the consequences of fading in multiple paths and therefore the performance of digital transmission throughout wireless radio channel can be improved. So it has been presumed that perfect CSI is available at the receiver and coherent detection is employed. This paper presents improvement of Frame Error Rate (FER) for differential space-time block code using various Doppler spectra. When the channels estimates are not available the DSTBC system noticed that at SNR of 10 dB, for two transmitting and four receiving antennas the FER is 0.0067 for rounded Doppler spectrum. The differential schemes attains full transmit diversity owing to orthogonal designs. However, the receiver or the transmitter needs the channel state information so these differential schemes are 3 dB worse than the STBC with coherent detection.

scholarly journals Construction method of space-time code in MIMO-VLC system

2021 ◽  
Vol 336 ◽  
pp. 04017
Author(s):  
Chengnan Sun
Keyword(s):  
Visible Light ◽  
Mimo System ◽  
Visible Light Communication ◽  
Block Code ◽  
Block Codes ◽  
Space Time ◽  
Design Criterion ◽  
Time Block ◽  
Space Time Block Code ◽  
Space Time Block Codes

In the recent years, the design of any order of space-time block code did not appear in the previous. In this paper, we investigate the criterion that how to design the space-time block code in Multiple input multiple output(MIMO) visible light communication(VLC) system. Based on the second order space-time block code, we give the design criterion of space-time block code of arbitrary order. Then we discuss the space-time block difference between traditional MIMO system and optical system. It is found that the space-time block codes of visible light system can be modified by the traditional space-time block codes and it can also realize independent decoding at the receiving end. In addition, in the receiver, how to realize fast calculation of the estimated value of the transmitted signal and a unified independent decoding scheme is presented.

scholarly journals Signal Classification Algorithms over Time Selective Channels

Electronics ◽  
2021 ◽  
Vol 10 (14) ◽  
pp. 1714
Author(s):  
Mohamed Marey ◽  
Hala Mostafa
Keyword(s):  
Block Code ◽  
Classification Problem ◽  
Classification Performance ◽  
Signal Classification ◽  
Final Decision ◽  
Time Block ◽  
Channel Response ◽  
Over Time ◽  
Parallel Fashion

In this work, we propose a general framework to design a signal classification algorithm over time selective channels for wireless communications applications. We derive an upper bound on the maximum number of observation samples over which the channel response is an essential invariant. The proposed framework relies on dividing the received signal into blocks, and each of them has a length less than the mentioned bound. Then, these blocks are fed into a number of classifiers in a parallel fashion. A final decision is made through a well-designed combiner and detector. As a case study, we employ the proposed framework on a space-time block-code classification problem by developing two combiners and detectors. Monte Carlo simulations show that the proposed framework is capable of achieving excellent classification performance over time selective channels compared to the conventional algorithms.

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