Diagonal Code Research Articles

Peningkatkan QoS Layanan Video Call dengan Metode DASTFBC Sistem MIMO2x2 pada Jaringan LTE

ABSTRACT
 The DASTFBC (Diagonal Algebraic Space Time Frequency Block Code) method is a coding scheme that utilizes different diversity sources, namely space, time and frequency. This method is one method that can be used to improve video call services. The DASTFBC method uses a rotation matrix in the DAST code which is formed using algebraic number field theory. The code matrix structure consists of rotated information symbols, expanded using a square diagonal code matrix. This method is used to overcome signal power fluctuations at the receiver which cause the service quality to decrease (not comply with) BER video call standards. The DASTFBC method is applied to the LTE network MIMO system with 64 QAM modulation. This method will be simulated in the Matlab program to obtain results to improve video call services. The DASTFBC method simulation of BER was carried out for 4 user speed scenarios, namely 5km/hour, 40km/hour, 100km/hour, 120km/hour. Significant results of the DASTFBC method can already be seen when the user moves at 40km/ hour. With this method, a smaller BER value is obtained, namely 2x10-4, this shows that with the DASTFBC method the video call BER standard (10-3) can be met. The value of BER obtained when using DASTFBC with a speed of 120km/h is 8.5x10-3 this value almost exceeds the standard BER video call. So that the maximum speed of the user when using the DASTFBC method is 120km/h above that speed the standard value of the BER video call cannot be fulfilled.
 Keywords: video call, LTE network, MIMO, DASTFBC

Fast subspace clustering by learning projective block diagonal representation

Block Diagonal Representation (BDR) has attracted massive attention in subspace clustering, yet the high computational cost limits its widespread application. To address this issue, we propose a novel approach called Projective Block Diagonal Representation (PBDR), which rapidly pursues a representation matrix with the block diagonal structure. Firstly, an effective sampling strategy is utilized to select a small subset of the original large-scale data. Then, we learn a projection mapping to match the block diagonal representation matrix on the selected subset. After training, we employ the learned projection mapping to quickly generate the representation matrix with an ideal block diagonal structure for the original large-scale data. Additionally, we further extend the proposed PBDR model (i.e., PBDRℓ1 and PBDR*) by capturing the global or local structure of the data to enhance block diagonal coding capability. This paper also proves the effectiveness of the proposed model theoretically. Especially, this is the first work to directly learn a representation matrix with a block diagonal structure to handle the large-scale subspace clustering problem. Finally, experimental results on publicly available datasets show that our approaches achieve faster and more accurate clustering results compared to the state-of-the-art block diagonal-based subspace clustering approaches, which demonstrates its practical usefulness.

Half diagonal matrix codes for reliable embedded memories

Reliability of embedded memories is dependent on at-speed rated correction capability of error detection and correction codes. Many critical applications like medical databases, rocket launch details stored in memories require accurate data and which cause major human losses or economy losses even if a 1% of data is compromised. This paper focuses on developing improved reliable error detection and correction codes with minimum redundant bits and maximum code rate. The decoder uses the concept of Encoder Reuse Technique along with the Modulo-2 addition to calculate syndrome, error location and correction of data bits when data is read from memory. The codes are represented in verilog hardware description language and simulated in the Tool Xilinx ISE 14.5 for XC7Z020-1CLG484 FPGA. The codes are evaluated for their performance in terms of technology parameters like area, delay, power, power – delay product, etc. Also for other parameters like bit overhead, code rate, code efficiency, correction coverage, correction efficiency, etc and correction coverage per cost for combined evaluation. The implemented half diagonal code is more effective as compared to existing matrix codes, it reduces bit overhead at least by 5.5% to 46.96% and coding rate increased at least by 16.74% to 23.85%.

A High Performance Hybrid Two Dimensional Spectral/Spatial NZCC/MD Code for SAC-OCDMA Systems with SDD Detection

This paper proposes a new technique to construct a hybrid zero cross-correlation (NZCC) based on multiple diagonal (MD) code for two-dimensional (2D) spectral amplitude coding for optical code division multiple access code division multiple access (SAC-OCDMA) systems. The proposed hybrid code eliminates totally the multiple access interference (MAI) between a large number of users and allows them to connect simultaneously via the optical communication link with a high speed to receive huge data and serve various areas such as Internet, telephony, DAB radio, digital audio broadcasting, and DVB video. Simulation results demonstrate that the performance of such a SAC-OCDA system based on novel 2D hybrid NZCC/MD code can be easily improved keeping a less complex structure using couplers for direct spectral/spatial dimension (SDD) detection and show superior bit error rate (BER) values comparing to previously developed two-dimensional codes including perfect difference (2D-PD), diagonal Eigen-value units (2D-DEU), multi-service (2D-MS) and balanced incomplete block design (2D-BIBD) codes.

Phase Carrier approach based on Optical Code Division Multiple Access Networks

A technique for optical code-division multiple-access (OCDMA) spectral amplitude coding is proposed and analyzed. The proposed approach is based on combining both OCDMA systems over a phase carrier. Compared with conventional OCDMA systems, this approach exhibits numerous advantages such as simplicity in the system design and cost efficiency. The phase shift based on phase modulation is adopted in the proposed system, and the orthogonal function based on the random diagonal code is applied. The proposed scheme is considered cost-effective because only one laser source is used; which minimizes interference for access network passive optical network applications and improves the system performance of bit-error rate (BER 10-12).

Performance Analysis of Bipolar Optical Code Division Multiple Access with Dual Electro-Optical Modulator Scheme for Free-Space Optical Communication

In this study, the performance of bipolar optical code division multiple access (OCDMA) with dual electro-optical modulator (EOM) scheme for multi-user scenario was tested and analyzed with OptiSystem version 10. The performance measurement was implemented for free-space optical (FSO) communication and includes the common noises in optical communication. Two different channels were used in the measurement, i.e., additive white Gaussian noise (AWGN) and fading channel. Two extreme weather conditions, strong rain and storm, were considered in the simulation. The performance between three spectral amplitude coding (SAC) codes, i.e., Modified M-Sequence code, Walsh-Hadamard code, and random diagonal (RD) code were measured and compared. The simulation results indicate that Modified M-Sequence code had the highest BER while RD code achieved the lowest BER in the short-range and Walsh-Hadamard code got the lowest BER for the medium-range of FSO, both for AWGN only and AWGN with fading channel. In strong turbulence condition, the performance of all codes become comparable after 500 m of FSO range. Modified M-Sequence suffered the lowest performance degradation while RD code endured the highest performance deterioration in all-weather condition. The results show that Modified M-Sequence can be applied for medium to long-range FSO.

Performance of zero cross correlation resultant weight spectral amplitude codes in lower Earth orbit‐based optical wireless channel system

SummaryA consolidated performance investigation and design of newly constructed zero cross correlation resultant weight (ZCCRW) code is presented without mapping over optical wireless channel (OWC) in lower Earth orbit (LEO). Multiple access interference (MAI) is suppressed by incorporating proposed 1‐D code at 10 Gbps with an algorithm. A further state of the art comparison of diverse optical code division multiple access (OCDMA) codes such as multi diagonal codes and diagonal double weight codes is accomplished with proposed code in terms of root mean square (RMS) jitter, extinction ratio, MAI, quality factor (QF), and bit error rate (BER) at different linewidths, chip sizes, link lengths, and active users. It is perceived that for ZCCRW code, QF obtained is 16.5 for chip size (0.1 ns), and at 4000 km, BER 10‐9 is achieved using the forward error correction (FEC) technique. OWC system in LEO with lasers in spectral amplitude code (SAC) OCDMA is proposed for the first time as per the author's best knowledge.

Performance Analysis of Shift ZCC Codes and Multi Diagonal Codes in 100 Gbps MDM-FSO System

Abstract With the rapid growth in the internet applications, pressure is observed on the optical communication systems. Free space optical communication (FSO) is very important alternative to the optical fiber because of elimination of licenses, trenching, and no cost of ways and saves the time of installation. Wavelength division is capacity enhancement multiplexing but due to large number of laser requirements, it becomes expensive. Mode division multiplexing (MDM) is suitable multiplexing technique because it needs only single laser and can support high data rates. Optical code division multiplexing and MDM is demonstrated in this work at 100 Gbps over FSO supporting 10 users. Multiple access interference is prominent issue in OCDMA codes and in order to suppress MAI, zero cross correlation codes are used and use of Laguerre Gaussian modes has been done. Different fog conditions are analyzed and two different OCDMA cods are incorporated as well as compared in the proposed system such as shift zero cross correlation codes and multi diagonal codes in terms of Q factor and BER.

Design and performance of spectral efficient modified new diagonal code for a spectral amplitude code-optical code division multiple access system

Our study contains performance and design of a spectral amplitude code-optical code division multiple access (SAC-OCDMA) system using proposed modified new diagonal (MND) code. The proposed MND code has advantages as very low cross-correlation value compared to other code sequences. Also the code has a short length for the higher code weight value. Furthermore, due to its enormous code property, it also introduces very low multiple access interference. Thus the MND code-based SAC-OCDMA system permits a higher number of users. The MND code construction method is also explained, which is very easy using diagonal matrices. Based on the theoretical analysis, bit error rate (BER) performance of MND code AND-subtraction scheme compare with conventional codes is better than random diagonal code, Pascal’s triangle matrix code (PTMC), and multidiagonal (MD) code, which makes it spectral efficient. It provides 5 dB lower BER compared to MD code and PTMC for 90 users. Simulation of the MND code-based system for four users with 2 Gbps data rate has been successfully demonstrated using the AND-subtraction scheme and the direct detection scheme.

Channel Crosstalk Impact on OCDMA Performance Under Efficient Diagonal Code and Optimized Pulse Shaping

This paper examines the four-wave mixing (FWM) effect on optical code-division multiple-access (OCDMA) performance systems in the presence of Multi-Diagonal code (MD). System performance improvement is accomplished by means of fibre length tuning and stratified different modulation shapes, which are Non-return-to-Zero (NRZ), Gaussian, and Sine wave, all examined with 500 and 1Gb/s data rate values. The tests show that the NRZ modulation offers better system performance compared with other modulations for all data rate values used. Moreover, the second channel of each user offered better system performance than the other channels used. For instance, for 1Gb/s, at the second channel, the NRZ modulation offered the best performance with a quality factor (Q –factor) of 5.1 at 100 km fibre length, whereas the first channel introduced a worse Q-factor of 3.1 at the same fibre length value.

Two dimensional optimized enhanced multi diagonal code for OCDMA passive optical networks

This paper optimizes the design of two-dimensional enhanced multi diagonal (2D-EMD) code and conventional spectral/spatial (SS) optical code division multiple access system architecture for large capacity at relatively low powers. The existing 2D-EMD coding scheme is optimized by reducing the weight and length of spatial code sequence to minimize power losses across the encoding and decoding arrangement. Moreover, a complete system architecture is developed by optimizing the structures of conventional 2D SS optical line terminal (OLT) and remote node (RN) racks to reduce the use to long span optical fibers between the central office and subscribers premises. The optimized system architecture is implemented as per passive optical network (PON) specification in Optisystem and analysis is performed using several pivotal performance parameters. It is observed that optimization of the 2D-EMD (2D-OEMD) coding algorithm elevates both transmission capacity and cardinality at received powers as low as of − 10 dBm. Moreover, the new OLT and RN racks significantly reduces the length and number of optical fibers between the OLT and receiver modules. Consequently, the optimized SS 2D-OEMD system can support 192 subscribers at 2 Gbps of data each over the span of 25 km single mode fiber. Consequently, the proposed architecture can be adapted for numerous application with high bandwidth requirement including next generation PON, back bone for free space optical and fifth generation communication systems.

A high speed 100 Gbps MDM-SAC-OCDMA multimode transmission system for short haul communication

In this work, a cost-effective spectrum amplitude coding optical code division multiple access (SAC-OCDMA) multimode transmission system is designed with the integration of mode division multiplexing (MDM) scheme in order to transmit 100 Gbps of data over 11 km multimode link. OCDMA scheme is carried out by using random diagonal (RD) code whereas MDM scheme is carried out by using modal multiplexing of Hermite Gaussian (HG) modes 00 and 01. The reported results show the successful transmission of 100 Gbps data over multimode link. Furthermore, the performance of multimode fiber and few mode fiber is investigated in terms of bit error rate which shows that few mode fiber performs better than multimode fiber link for the proposed MDM-OCDMA system. Moreover, the decomposition of HG modes into linearly polarized (LP) modes at receiver side is presented.

Improving of Scm-Sac-Ocdma System by Using Optical Amplifier Based on Md Code

Free space optic (FSO) is one of the most effective solution technique to transmit the information due to its advantage such as cost and speed, but it suffers from various disadvantage that affects on the signal performance like weather condition that results loss in optical signal power over the communication path. So, in this paper we study the effect of the rain weather in Iraqi cities [ Baghdad, Basra, Mosul ] during 2017 on the FSO signal with system of hybrid Sub-carrier multiplexing _Spectral amplitude coding _ optical code division multiple access (SCM-SAC-OCDMA) with multi diagonal (MD) code and intermediate stage called ‘optical amplifier’. OCDMA allows multiple users to access the medium without any contention; it provides privacy and security with reducing the interference that may occur due to multiple users. MD code has been use to provide simplicity in design and high data rate. The optical amplifier with controlled gain leads to amplify the power of the signal. Results from simulation analysis for the proposed system can transmit data rate with (1Gbps) for (1 Km) distance and transmit power of (5dB) with bit error rate (BER) 10−12 in Mosul, 3× 10−56 in Baghdad, 1 × 10−62 in Basra.

Analysis of noise suppression for OCDMA systems with fixed in-phase cross-correlation codes and single O/E converter

Performance of the non-coherent spectral amplitude coding optical code division multiple access (SAC-OCDMA) systems is primarily degraded by the presence of noise sources generated during the process of optical-to-electrical (O/E) conversion at the receiving photodiode (PD). Phase induced intensity noise (PIIN) is generated by limitations in the coding scheme that leads to the mixing of adjacent spectrum's commonly known as multiple access interference (MAI). While, shot and thermal noise sources are generated at PD during the conversion of signal from O/E domain for further processing. This paper investigates and compares the performance of two detection techniques with reference to the received power units and suppression of noise sources while recovering and decoding enhanced multi diagonal (EMD) code. Both techniques namely spectral direct detection (SDD) and single PD detection (SPD) use one PD for O/E conversion to reduce the effect of shot and thermal noise. Numerical analysis using Gaussian approximation shows that SPD technique provides better performance for an acceptable bit error rate (BER) of 10−9 as compared with SDD technique, due to maximum recovery of power units in the received spectrum. Simulation analysis through a highly recognized software called Optisystem also validates the mathematical formalism and shows the EMD and SPD based SAC-OCDMA system is able to support 64 subscribers communication simultaneously beyond 1 Gbps of data while −10 dBm power is maintained at the receiving PD.

Study of the Different Optical Filters in SAC-OCDMA System

Abstract Spectral amplitude coding for optical code division multiple access (SAC-OCDMA) networks has received much attention over the last two decades. This article aims to explore the impact of encoder change on different types of optical filters, such as the Gaussian optical filter and the Bessel optical filter, for high data rates and to give an overview on importance of choosing the optimal type of optical filter according to the frequency range selected by the user is 25 and 50 GHz. SAC-OCDMA transmitter utilizes Wavelength Division Multiplexing multiplexer (WDM MUX) as an encoder, to generate a code having low cross-correlation called Random Diagonal code, and spectral direct detection as a detection technique. The change of optical filter, in WDM MUX, directly affects the performance of the system. The results show that the system for 50 GHz, with a WDM MUX, using a Gaussian optical filter has better performance compared to the optical Bessel filter and can reach a bit error rate (BER) of 10−25. SAC-OCDMA system, using a WDM MUX based on Bessel filters with a bit rate of 300Mb/s, achieves a BER of 10−28 which leads us to recommend it for second norm 25 GHz. Moreover, the power received increases by 4 dBm every 20 Km with the increase in the length of the fibre for both filters Bessel and Gaussian. Our work focuses on the two 25 and 50 GHz bands, after a study on the impact of the change of the bandwidth and the order of the different optical filters used according to the BER applied to the different networks of access, such as local area network (LAN).

Implementation of Spectral Amplitude Coding OCDMA System Based on Multi- Carrier Optical Signal

Incoherent SAC-OCDMA systems are designed to support low cost passive optical networks. However, incoherent nature of these systems limits their capability to support large amount of data. It is therefore necessary to utilize coherent optical sources like laser diode to provide high capacity in terms of data and the number of subscribers. Use of a single laser source in SAC-OCDMA system significantly increases the cost, which reduce its feasibility for deployment at the access domain. This paper proposes a novel technique for the implementation of SAC-OCDMA system using multi carrier laser. This technique can reduce the cost of SAC-OCDMA system by using a single laser for multiple subscribers in the system. Simulation analysis of the proposed SAC-OCDMA system while using random diagonal codes shows that it can support up to 12 Gbps of data at fiber lengths of 25 km.

Implementation of Spectral Amplitude Coding OCDMA System Based on Multi- Carrier Optical Signal

Incoherent SAC-OCDMA systems are designed to support low cost passive optical networks. However, incoherent nature of these systems limits their capability to support large amount of data. It is therefore necessary to utilize coherent optical sources like laser diode to provide high capacity in terms of data and the number of subscribers. Use of a single laser source in SAC-OCDMA system significantly increases the cost, which reduce its feasibility for deployment at the access domain. This paper proposes a novel technique for the implementation of SAC-OCDMA system using multi carrier laser. This technique can reduce the cost of SAC-OCDMA system by using a single laser for multiple subscribers in the system. Simulation analysis of the proposed SAC-OCDMA system while using random diagonal codes shows that it can support up to 12 Gbps of data at fiber lengths of 25 km.

Design of Variable Weight code for multimedia service in SAC–OCDMA systems

Variable weight (VW) codes for spectral amplitude coding–optical code division multiple access system are useful in multimedia applications. VW code algorithm is proposed which is based on enhanced and modified double weight codes. The proposed algorithm can be used for any combination of weights >2. The cross-correlation among all users is at most 1. This code construction algorithm ensures higher power at receiver for higher-weight users. Lower-weight users receive less power compared with higher-weight users. The difference in received power translates as varying performance, and are useful for multimedia applications. The performance of VW code is analysed using balanced detection (BD) exclusive-OR operation and direct detection with exclusive-OR operation. VW code gives comparable or better performance than previously reported code. It is observed that supportable number of users for higher weight, at bit error rate (BER) of 10−9 (data) are 28, 33 and 35 for random diagonal (RD) code, Khazani-Syed (KS) code and VW code, respectively, using BD. Supportable number of users for lower weight, at BER of 10−4 (voice) are 23, 31 and 37 for RD code, KS code and VW code, respectively, using BD.

Three-dimensional multi-diagonal codes for OCDMA system

In this paper, we propose a new three dimensional multi diagonal (3D-MD) code for optical code division multiple access (OCDMA) system. Its corresponding system structure reduces 75% and 50% the complexity of 3D-perfect difference (3D-PD) and 3D-perfect/multi-diagonal (3D-PD/MD) receivers, respectively. Moreover, the numerical analysis shows that the proposed code outperforms the performance of one and two dimensional multi-diagonal (1D-MD and 2D-MD), 3D-PD and 3D-PD/MD codes.

A cost effective 100 Gbps hybrid MDM–OCDMA–FSO transmission system under atmospheric turbulences

FSO or free space optics is a familiar name used in a wide array of applications in the area of telecommunications. Due to its features of low maintenance cost and deployment time, most of the applications consider FSO as the alternative solution for appropriately replacing fiber optics. In this work, we have designed 100 Gbps FSO system by combining mode division multiplexing (MDM) and optical code multiple access scheme (OCDMA). Ten channels, each carrying 10 Gbps data, are transported over 8 km FSO link by using MDM of two Laguerre Gaussian modes and random diagonal codes. Moreover, the performance of proposed MDM–OCDMA–FSO system is also investigated under atmospheric turbulences.