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Journal : EMITTER International Journal of Engineering Technology

Performance of Channel Estimation Technique in MIMO-OFDM System Using mPSK Modulation Musayyanah .; Yoedy Moegiharto; I Gede Puja Astawa
EMITTER International Journal of Engineering Technology Vol 1 No 1 (2013)
Publisher : Politeknik Elektronika Negeri Surabaya (PENS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24003/emitter.v1i1.2

Abstract

Multicarrier modulation technique as Orthogonal Frequency Division Multiplexing (OFDM) is able to vanishIntersymbol Interferences (ISI) caused by multipathchannel. Merging with multi- antenna transmission techniques such asMIMO become MIMO- OFDM system is able to improve (data rate transmission)the transmission of data and capacity of the system. Pilot channel estimation technique with the algorithm Linear Minimum Mean Square Error (LMMSE) with modulation m-PSK is applied in this study. The results obtained in the form of graphs BER against EbNo which shows that the system performance with LMMSEestimator has a different gain for QPSKmodulation better about 0.75 dB, for 8 PSKmodulation is about 1.5 dB and for 16 PSKmodulation around 1 dB compare to LS estimator. Number of the largest antenna both in the transmitter and receiver produce the best system performance. Observation for QPSKmodulation shows a scheme transmitter- receiver antenna 4x2 having gain approximately 9 dB better than the number of the lowest transmitter antenna(1x2). For scheme 4x4 shows gain around 8,5 dB than the number of the lowest receiver antenna.Keywords:MIMO, OFDM,LS, LMMSE, MPSK.
Performance Evaluation of DCT And Wavelet Coding of Image Transmission By Using of DM Technique Over Topical Shallow-Water Environment Sendi Eka Nilasari; I Gede Puja Astawa; Tri Budi Santoso
EMITTER International Journal of Engineering Technology Vol 1 No 1 (2013)
Publisher : Politeknik Elektronika Negeri Surabaya (PENS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24003/emitter.v1i1.3

Abstract

Image transmission over under water acoustic channel is one of research trends that were developed to support under ocean environment monitoring. The result of study about the source coding performance for image transmission over underwater acoustic channel over tropical shallow-water environment is presented in this paper. By using the discrete cosine transform (DCT) and wavelet coding, image file was compressed and converted into binary data sequence. Transmission process was conducted with multicarrier OFDM system over under water acoustic channel. An evaluation has been implemented on base band scale by adopting channel model of previous research. With the DCT technique at Eb/No 20 dB was achieved the value of PNSR 12.69 dB, and bit error 0.0025. While by using the wavelet technique, at same Eb/No value, achieved the value of PSNR at 21.38 dB and bit error rate 0.0022. The performance evaluation also conducted visually and showing similar trend as simulation result by using pseudo random data.Keywords: DCT, wavelet, OFDM, underwater acoustic.
Analysis of Channel Coding Performance in OFDM Technique for Underwater Acoustic Communication System Machmud Roby Alhamidi; I Gede Puja Astawa; Tri Budi Santoso
EMITTER International Journal of Engineering Technology Vol 1 No 1 (2013)
Publisher : Politeknik Elektronika Negeri Surabaya (PENS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24003/emitter.v1i1.5

Abstract

One way to increase the performance of Orthogonal Frequency Division Multiplexing System (OFDM) system is by adding a channel coding (error correction code) in order to detect and correct errors that occur when sending data.At communication of acoustic underwater channel coding is required because of the characteristics of the channel bottom water is much different compared with the air channel and errors are likely to occur.In this research it was made simulation of acoustic underwater communication system with OFDM applied channel codingin which using Hamming code (7,4) and Hamming code (15,11) that is able to correct one error and detect two errors then BCH code capable to correct two errors for BCH (15,7) and correct 9 errors forBCH (127,64) and Reed Solomon code able to correct two errors for RS (15,11) and correct 8 errors for RS (31,15). Results of the study confirm the better performance when system usesOFDM with BCH Code (127.64) than other codes that are used, starting from 1 decibel (dB) to 3 dB for the performance of BER as10 -3 on Additive Gaussian White Noise (AWGN) channel while at the multipath channel, the performance of Bit Error Rate (BER) got better result on 1 dB up to 8 dB for BER performance as10 -3.Keyword: Underwater, Orthogonal Frequency Division Multiplexing (OFDM), channel coding
An Implementation of Error Minimization Data Transmission in OFDM using Modified Convolutional Code Hendy Briantoro; I Gede Puja Astawa; Amang Sudarsono
EMITTER International Journal of Engineering Technology Vol 3 No 2 (2015)
Publisher : Politeknik Elektronika Negeri Surabaya (PENS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (363.575 KB) | DOI: 10.24003/emitter.v3i2.44

Abstract

This paper presents about error minimization in OFDM system. In conventional system, usually using channel coding such as BCH Code or Convolutional Code. But, performance BCH Code or Convolutional Code is not good in implementation of OFDM System. Error bits of OFDM system without channel coding is 5.77%. Then, we used convolutional code with code rate 1/2, it can reduce error bitsonly up to 3.85%. So, we proposed OFDM system with Modified Convolutional Code. In this implementation, we used Software Define Radio (SDR), namely Universal Software Radio Peripheral (USRP) NI 2920 as the transmitter and receiver. The result of OFDM system using Modified Convolutional Code with code rate is able recover all character received so can decrease until 0% error bit. Increasing performance of Modified Convolutional Code is about 1 dB in BER of 10-4 from BCH Code and Convolutional Code. So, performance of Modified Convolutional better than BCH Code or Convolutional Code.Keywords: OFDM, BCH Code, Convolutional Code, Modified Convolutional Code, SDR, USRP
Performance Analysis of CP-Based and CAZAC Training Sequence-Based Synchronization in OFDM System R. Gaguk Pratama Yudha; I Gede Puja Astawa; Amang Sudarsono
EMITTER International Journal of Engineering Technology Vol 4 No 2 (2016)
Publisher : Politeknik Elektronika Negeri Surabaya (PENS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (363.5 KB) | DOI: 10.24003/emitter.v4i2.146

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) is a popular wireless data transmission scheme. However, its synchronization is still being a major problem when it is applied in real hardware. Cyclic Prefix (CP) based synchronization is one of the solutions in this problem, but CP has high crest factor. In the other hand, CAZAC sequence is another solution with lower crest factor but the higher complexity and also CAZAC has potential in security and channel estimation implementation. The performance between CP and CAZAC sequence based synchronization in OFDM system is analyzed in this paper. The real hardware, Universal Software Rado Peripheral (USRP), is used to prove the analysis. The CAZAC sequence has 10% performance increased in frequency offset than CP based synchronization.
Performance Analysis of Circular 8-QAM Constellation with MMSE Equalizer for OFDM System Using USRP Muh. Alfan Taufiqurrahman; I Gede Puja Astawa; Amang Sudarsono
EMITTER International Journal of Engineering Technology Vol 4 No 2 (2016)
Publisher : Politeknik Elektronika Negeri Surabaya (PENS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1974.161 KB) | DOI: 10.24003/emitter.v4i2.148

Abstract

Bandwidth is very important in communication system, and it is a limited resource. In order to save the limited bandwidth resource, high order M-ary modulation is widely employed in modern communication and broadcasting systems. In Orthogonal Frequency Division Multiplexing (OFDM), fading environment lead to a loss of orthogonality between the subcarriers. In this paper, we present the performance analysis of circular 8-Quadrature Ampilutude Modulation (QAM) constellation for Orthogonal Frequency Division Multiplexing (OFDM) system. We also combine the system with Minimum Mean Square Error (MMSE) equalizer to mitigate the effect of Inter Symbol Interference (ISI). Then, all of this system is implemented practically using Universal Software Radio Peripheral (USRP). The performance of circular 8-QAM and MMSE equalizer is evaluated by comparing with other 8-QAM modulation models such as circular-Zero Forcing (ZF), star-ZF, Square-ZF, Star-MMSE, and Square-MMSE. The performance of circular 8-QAM with MMSE equalizer is  better than the other combinations. Bit Error Rate (BER) graph shows that the performance of circular-MMSE is better than star-MMSE. The performance improvement using circular-MMSE is about 1.6%. The performance will decrease when the distance is increased. The performance of this system is greatly affected by the distance between transmitter and receiver.
Trusted Data Transmission Using Data Scrambling Security Method with Asymmetric Key Algorithm for Synchronization Nihayatus Sa'adah; I Gede Puja Astawa; Amang Sudarsono
EMITTER International Journal of Engineering Technology Vol 6 No 2 (2018)
Publisher : Politeknik Elektronika Negeri Surabaya (PENS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (804.766 KB) | DOI: 10.24003/emitter.v6i2.267

Abstract

Security is a major concern of the internet world because the development of the Internet requires the security of data transmission. The security method helps us to store valuable information and send it over an insecure network so that it can not be read by anyone except the intended recipient. Security algorithm uses data randomization method. This method of data information randomization has a low computation time with a large number of bits when compared to other encryption algorithms. In general, the encryption algorithm is used to encrypt data information, but in this research the encryption algorithm is used for synchronization between the sender and the intended recipient. Number of bits on asymmetric key algorithm for synchronization are the 64-bits, 512-bits and 1024-bits. We will prove that security methods can secure data sent with low computational time with large number of bits. In the result will be shown the value of computing time with variable number of bits sent. When data are sent by 50 bytes, encryption time required 2 ms using 1024 bits for synchronization technique asymmetric key algorithm.Â