scholarly journals Hiding Stealth Optical CDMA Signals in Public BPSK Channels for Optical Wireless Communication

2018 ◽  
Author(s):  
Chih-Ta Yen ◽  
Jen-Fa Huang ◽  
Wen-Zong Zhang
Keyword(s):  
Optical Cdma ◽  
Free Space Optical ◽  
Secret Data ◽  
Optical Source ◽  
Source Power ◽  
The Public ◽  
Shift Keying ◽  
Public Channel ◽  
Code Division Multiple ◽  
Public Signal

A new optical steganography scheme is proposed that transmits a stealth optical code-division multiple-access (OCDMA) signal through a public binary phase-shift keying (BPSK) channel. Polarization beam splitters and arrayed waveguide gratings are used to implement a spectral-polarization coding (SPC) system with an incoherent optical source. We employ a Walsh–Hadamard code as the signature code of the user who wants to transmit stealth information using the system. A free space optical link applied to this system maintains the polarization states of light during propagation. The secret data is extracted using correlation detection and balanced subtraction in the OCDMA decoder of the intended receiver, and the other signal from the public channel is reduced by the OCDMA decoder. At the demodulator of the public channel, BPSK demodulation eliminates the stealth signal so that the public channel is not affected by the stealth signal. The two signals cannot interfere with each other. The results of this study show that our proposed optical steganography system is highly secure. The stealth signal can be favorably hidden in the public channel when the average source power of the stealth signal, public noise, and public signal are −5, −3, and 0 dBm, respectively.

scholarly journals Hiding Stealth Optical CDMA Signals in Public BPSK Channels for Optical Wireless Communication

2018 ◽  
Vol 8 (10) ◽  
pp. 1731 ◽  
Author(s):  
Chih-Ta Yen ◽  
Jen-Fa Huang ◽  
Wen-Zong Zhang
Keyword(s):  
Optical Cdma ◽  
Free Space Optical ◽  
Secret Data ◽  
Optical Source ◽  
Source Power ◽  
The Public ◽  
Shift Keying ◽  
Public Channel ◽  
Code Division Multiple ◽  
Public Signal

A new optical steganography scheme is proposed that transmits a stealth optical code-division multiple-access (OCDMA) signal through a public binary phase-shift keying (BPSK) channel. Polarization beam splitters and arrayed waveguide gratings are used to implement a spectral-polarization coding (SPC) system with an incoherent optical source. We employ a Walsh–Hadamard code as the signature code of the user who wants to transmit stealth information using the system. A free space optical link applied to this system maintains the polarization states of light during propagation. The secret data are extracted using correlation detection and balanced subtraction in the OCDMA decoder of the intended receiver, and the other signal from the public channel is reduced by the OCDMA decoder. At the demodulator of the public channel, BPSK demodulation eliminates the stealth signal so that the public channel is not affected by the stealth signal. The two signals cannot interfere with each other. The results of this study show that our proposed optical steganography system is highly secure. The stealth signal can be favorably hidden in the public channel when the average source power of the stealth signal, public noise, and public signal are −5, −3, and 0 dBm, respectively.

Optical steganography transmission of optical CDMA signals over a public BPSK channel

2016 ◽  
Vol 33 (6) ◽  
pp. 1810-1824 ◽  
Author(s):  
Chih-Ta Yen ◽  
Guan-Jie Huang
Keyword(s):  
Dispersion Compensation ◽  
Optical Cdma ◽  
High Dispersion ◽  
Noise Power ◽  
Content Type ◽  
The Public ◽  
Shift Keying ◽  
Code Division Multiple ◽  
Public Signal ◽  
Ber Performance

Purpose – The purpose of this paper is to propose a new optical steganography framework that can be applied to public optical binary phase-shift keying (BPSK) systems by transmitting a stealth spectrum-amplitude-coded optical code-division multiple-access signal through a BPSK link. Design/methodology/approach – By using high-dispersion elements, the stealth data pulses temporally stretch and the amplitude of the signal decreases after stretching. Thus, the signal can be hidden underneath the public signal and system noise. At the receiver end, a polarizer is used for removing the public BPSK signal and the stealth signal is successfully recovered by a balanced detector. Findings – In a simulation, the bit-error rate (BER) performance improved when the stealth power increased. Research limitations/implications – The BER performance worsens when the noise power become large. Future work will consider increasing the system performance during high-noise power situation. Practical implications – By properly adjusting the power of the amplified spontaneous emission noise, the stealth signal can be hidden well in the public channel while producing minimal influence on the public BPSK signal. Originality/value – In conclusion, the proposed optical steganography framework makes it more difficult for eavesdroppers to detect and intercept the hidden stealth channel under public transmission, even when using a dispersion compensation scheme.

scholarly journals Noncoherent Spectral Optical CDMA System Using 1D Active Weight Two-Code Keying Codes

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Bih-Chyun Yeh
Keyword(s):  
Cross Correlation ◽  
Transfer Functions ◽  
Block Design ◽  
Optical Network ◽  
Optical Cdma ◽  
Spectral Amplitude ◽  
Source Power ◽  
New Family ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

We propose a new family of one-dimensional (1D) active weight two-code keying (TCK) in spectral amplitude coding (SAC) optical code division multiple access (OCDMA) networks. We use encoding and decoding transfer functions to operate the 1D active weight TCK. The proposed structure includes an optical line terminal (OLT) and optical network units (ONUs) to produce the encoding and decoding codes of the proposed OLT and ONUs, respectively. The proposed ONU uses the modified cross-correlation to remove interferences from other simultaneous users, that is, the multiuser interference (MUI). When the phase-induced intensity noise (PIIN) is the most important noise, the modified cross-correlation suppresses the PIIN. In the numerical results, we find that the bit error rate (BER) for the proposed system using the 1D active weight TCK codes outperforms that for two other systems using the 1D M-Seq codes and 1D balanced incomplete block design (BIBD) codes. The effective source power for the proposed system can achieve −10 dBm, which has less power than that for the other systems.

scholarly journals Spectral Amplitude Coding Optical CDMA: Performance Analysis on Free Space Optical Channel

2018 ◽  
Vol 7 (4.38) ◽  
pp. 31
Author(s):  
Kehkashan A. Memon ◽  
A. W. Umrani ◽  
M. A. Unar ◽  
Wajiha Shah ◽  
B. S. Chowdhry
Keyword(s):  
Performance Analysis ◽  
Free Space ◽  
Optical Filters ◽  
Optical Cdma ◽  
Optical Channel ◽  
Spectral Amplitude ◽  
Free Space Optical ◽  
Spectral Amplitude Coding ◽  
Point To Point ◽  
Code Division Multiple

In this paper, we investigate the performance of Spectral Amplitude Coding Optical Code Division Multiple Access technique based on Free Space Optical channel. SAC OCDMA is one of the most popular multiplexing techniques since many years and FSO is gaining popularity and is very useful especially in point to point communication. The system presented in this paper utilizes Walsh Hadamard code as signature code. The coder and decoder structures are based on optical filters of fiber Bragg gratings (FBGs). This system focuses on the performance analysis of FSO based systems for subtropical regions. This paper demonstrates the error rate performance in the form of eye diagrams/BER under varying channel gain and link distances. Five cases have been taken which shows that SAC OCDMA FSO system is reliable even for distances sufficient to overcome the last mile problem.  

Effect of Pointing Error on the BER Performance of an Optical CDMA FSO Link with SIK Receiver

2017 ◽  
Vol 38 (4) ◽  
Author(s):  
A. K. M. Nazrul Islam ◽  
S. P. Majumder
Keyword(s):  
Bit Error Rate ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Direct Detection ◽  
Optical Cdma ◽  
Free Space Optical ◽  
Power Penalty ◽  
Pointing Error ◽  
Multi Access ◽  
Code Division Multiple

AbstractAn analytical approach is presented for an optical code division multiple access (OCDMA) system over free space optical (FSO) channel considering the effect of pointing error between the transmitter and the receiver. Analysis is carried out with an optical sequence inverse keying (SIK) correlator receiver with intensity modulation and direct detection (IM/DD) to find the bit error rate (BER) with pointing error. The results are evaluated numerically in terms of signal-to-noise plus multi-access interference (MAI) ratio, BER and power penalty due to pointing error. It is noticed that the OCDMA FSO system is highly affected by pointing error with significant power penalty at a BER of 10

Comparative analysis of SISO and wavelength diversity-based FSO systems at different transmitter power levels

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Varun Srivastava ◽  
Abhilash Mandloi ◽  
Dhiraj Kumar Patel
Keyword(s):  
Optical Signal ◽  
Free Space Optical ◽  
Optical Source ◽  
Transmit Power ◽  
Single Input Single Output ◽  
Transmitter Power ◽  
Single Output ◽  
Communication Links ◽  
Single Input ◽  
Matching Performance

AbstractFree space optical (FSO) communication refers to a line of sight technology, which comprises optical source and detector to create a link without the use of physical connections. Similar to other wireless communication links, these are severely affected by losses that emerged due to atmospheric turbulence and lead to deteriorated intensity of the optical signal at the receiver. This impairment can be compensated easily by enhancing the transmitter power. However, increasing the transmitter power has some limitations as per radiation regulations. The requirement of high transmit power can be reduced by employing diversity methods. This paper presents, a wavelength-based diversity method with equal gain combining receiver, an effective technique to provide matching performance to single input single output at a comparatively low transmit power.

Design and Performance Analysis of 2D OCDMA System with Polarization States

2016 ◽  
Vol 37 (4) ◽  
Author(s):  
Manisha Bharti ◽  
Ajay K. Sharma ◽  
Manoj Kumar
Keyword(s):  
Phase Shift ◽  
Polarization State ◽  
Phase Shift Keying ◽  
Modulation Formats ◽  
Differential Phase Shift ◽  
Differential Phase ◽  
Differential Phase Shift Keying ◽  
Shift Keying ◽  
Polarization States ◽  
Code Division Multiple

AbstractThis paper focuses on increasing the number of subscribers in optical code-division multiple access (OCDMA) system by using one of the features of light signal that it can be propagated in two polarization states. The performance of two-dimensional (2D) OCDMA system based on wavelength-time coding scheme by adding polarization state is investigated at varying data rates from 1 GHz to 6 GHz and for various modulation formats. It is reported that with increase in data rate of system, the performance of the system deteriorates due to polarization mode dispersion. Non-return to-zero (RZ), return to-zero (RZ), carrier suppressed return-to-zero (CSRZ) and differential phase shift keying (DPSK) modulation formats are simulated for a single user system with polarization. Investigations reveal that differential phase shift keying (DPSK) modulation format suits best to the proposed system and exhibit the potential to improve the flexibility of system for more number of users. The investigations are reported in terms of Q-factor, BER, received optical power (ROP) and eye diagrams.

Effect of adverse weather conditions and pointing error on the performance of 2-D WH/TS OCDMA over FSO link

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Bithi Mitra ◽  
Md. Jahedul Islam
Keyword(s):  
Free Space ◽  
Atmospheric Condition ◽  
Optical Power ◽  
Weather Conditions ◽  
Free Space Optical ◽  
Central Wavelength ◽  
Pointing Error ◽  
Adverse Weather ◽  
Code Division Multiple ◽  
Ber Performance

AbstractIn this paper, the performance of two-dimensional (2-D) wavelength-hopping/time-spreading (WH/TS) optical code division multiple access (OCDMA) system over free space optical (FSO) channel is analyzed in the presence of pointing error and different weather conditions. Prime code scheme is employed for both wavelength-hopping and time-spreading to address user code-matrix. The operating central wavelength of 1550 nm is considered to demonstrate the bit error rate (BER) performance of the proposed system as a function of various system parameters. The required optical power of the proposed system is determined to maintain a BER value of 10−9. The numerical evaluation interprets that the BER performance is highly dependent on transmission length, transmitted power, pointing error angle as well as the number of simultaneous user. It is also observed that the 2-D OCDMA system over free space needs minimum required optical power in case of rainy atmospheric condition, but it is maximum for foggy atmospheric condition.

Sign in / Sign up

Export Citation Format

Share Document