Aditya Goel

Effect of wavelength conversion factor on blocking probability and link utilization in wavelength routed optical network

Due to introduction of various wide-band applications in wired and wireless network demand of bandwidth is growing exponential. The existing network is not capable to meet the requirement of vast bandwidth. These requirement can be meet by all optical network which is capable of transmitting enormous data at very high speed, around 50 Tera bits per seconds (Tbps) A wavelength conversion technique is addressed in this paper to reduced the blocking probability in wavelength routed networks. It is seen that the blocking probability of traffic requests decreases as the wavelength conversion factor increases. We explode the possibility for network with different size comprising of 25, 50 and 100 nodes with variation in wavelength per link In this work the effects of varying number of wavelength converters, different traffic types on fiber link utilization and network blocking probability are evaluated and results are shown that the blocking probability is minimum with wavelength conversion factor of 0.5. Thus we propose a network with 32 and 64 wavelengths and 50 % wavelength convertible nodes.

Performance analysis of long reach colorless wavelength division multiplexed-orthogonal frequency division multiplexing-passive optical network with broadcast capability

Abstract. A colorless wavelength division multiplexed-orthogonal frequency division multiplexing-passive optical network (WDM-OFDM-PON) is presented, which is capable of supporting symmetric 10 Gbps downlink direct detection (DD) OFDM unicast signal, broadcast signal, and uplink on–off keying (OOK) signal up to 60 km that includes both single mode and dispersion compensation fiber. At each optical network unit (ONU), DD has been used to receive downlink unicast and broadcast OFDM data. A delay interferometer (DI) has been used at a central office to achieve 10 Gbps uplink signal transmission over 60 km distance utilizing a reflective semiconductor optical amplifier (bandwidth=1.5  GHz) at the ONU because DI works as a vestigial sideband filter and an optical equalizer. Broadcast channel does not affect the system performance because it generates a limited interference of the order of 0.1 to 0.28 dB to downlink and uplink channels, and this interference is distributed to every ONU. For bit error rate of 10−9, the receiver sensitivity of −24, −23.1, and −20.14  dBm is achieved by simulating downlink OFDM unicast channels, OFDM broadcast channel, and uplink OOK unicast channels, respectively, for a symmetric data rate of 10 Gbps over 60 km.

New Approach for Performance and Security Enhancement in OCDMA Networks

A new technique is proposed for the enhancement of security against the eavesdropper in Optical code division multiple access (OCDMA) Spectral amplitude coding (SAC) System. This technique is the combination of real and virtual user’s spectral chip, according to the newly developed Zero cross correlation code. The define sequence assign to virtual users, is complement to each other in a group of two users. Probability of code detection of individual user decreases due to virtual user and complement of defined sequence of virtual user, removes the occurrence of single user’s code in the channel. The simulation and analytical results show that the proposed scheme has a better performance than existing methods.

Performance Analysis of Long-Reach Coherent Detection OFDM-PON Downstream Transmission Using m-QAM-Mapped OFDM Signal

Abstract In this paper, orthogonal frequency division multiplexing (OFDM)-passive optical network (PON) downstream transmission is demonstrated over different lengths of fiber at remote node (RN) for different m-QAM (quadrature amplitude modulation)-mapped OFDM signal (m=4, 16, 32 and 64) transmission from the central office (CO) for different data rates (10, 20 30 and 40 Gbps) using coherent detection at the user end or optical network unit (ONU). Investigation is performed with different number of subcarriers (32, 64, 128, 512 and 1,024), back-to-back optical signal-to-noise ratio (OSNR) along with transmitted and received constellation diagrams for m-QAM-mapped coherent OFDM downstream transmission at different speeds over different transmission distances. Received optical power is calculated for different bit error rates (BERs) at different speeds using m-QAM-mapped coherent detection OFDM downstream transmission. No dispersion compensation is utilized in between the fiber span. Simulation results suggest the different lengths and data rates that can be used for different m-QAM-mapped coherent detection OFDM downstream transmission, and the proposed system may be implemented in next-generation high-speed PONs (NG-PONs).

WDM PON enhanced capacity architecture for unicast, multicast and broadcast through efficient sideband carrier modulation

We propose a flexible architecture of WDM-PON in which unicast, multicast and broadcast data is transmitted based on a novel scheme of using sidebands as carrier. We here transmit one unicast data, one multicast data and two broadcast data transmission to each ONU. With the help of single frequency reflection capacity of FBG and cyclic wavelength distribution property of the AWG a unicast/multicast data and broadcast data is transmitted to each ONU. Simulation with 10 Gbps downstream channel, 10 Gbps broadcast channel and 2.5 Gbps upstream transmission is demonstrated with acceptable performance. In the proposed architecture DI is used to separate optical carrier and sideband carrier. Carrier reuse scheme is used and therefore the ONUs are colourless.

Dense wavelength-division multiplexing networks waves system for high data rate communication

This paper describes new approach to construct 60-GHz-band bidirectional fiber-fed wireless access systems, which provide simple antenna base-station architecture and full compatibility with dense wavelength- division multiplexing (DWDM) fiberoptic networks. For downlink millimeter-wave signal generation, the scheme utilizes uplink optical transmitters as downlink optical heterodyne sources, which promises wavelength allocations of downlink and uplink signals that are fully compatible with those of DWDM networks. The excessive RF phase-noise originating from these uncorrelated uplink and downlink optical signals exerts negligible influence on the transmission performance because of the use of self-heterodyne transmission techniques, which make it possible to perform phase-modulated data transmission without expensive phase-locked oscillators at both transmitter and receiver sides.

A capacity analysis of MIMO OFDMA for 4G cellular system design

Orthogonal frequency division multiple access is a promising candidate for multiple access. It was originally proposed for cable TV (CATV) networks in Europe. Recently it has been considered in IEEE-802.16 Wireless Metropolitan Area Network. [2] OFDMA possess finer granularity in resource allocation. If we get channel state information at the transmitter, (CSIT); We can say that OFDMA possess higher system capacity in a single cell environment. In single cell environment, interference is white but in multicellular systems, the intercell interference must be considered and that is colored. Colored intercell interferences arise in a multicarrier system due to various reasons such as frequency selective channels, bursty transmission or non-uniform subcarrier power allocation. The absence or the imperfection of the interference knowledge will cause outage, despite CSIT. In this case, the Ergodic capacity is no longer sufficient to compare the performance of the systems. Instead, the system goodput is more meaningful for performance evaluation. In addition to intercell interference pattern, the transmit power spectrum also affects suitability of the multiple access system for multi-cell system applications. It has become very much necessary to investigate performance of various multiple access systems in a multi-cell scenario for traffics of data such as voice and packets with high data rate. Industry needs to get precise and useful insights for effective B3G or 4G cellular system designs.

Advance Method for Security Enhancement in Optical Code Division Multiple Access System

Abstract This paper proposes a new design of encoder and decoder with novel code design for one–dimensional (1D) (spectral domain) and two-dimensional (2D) (spectral and time domain) optical code divisions multiple access system. The suggested code has a zero cross-correlation property in 1D and 2D modes, so multiple-access interference (MAI) is totally eliminated. In proposed new encoder, code reconfiguration is achieved within two users in each group at the transmitter end with defined sequence. This approach degrades the code detection probability at the receiving end against the eavesdropper in the presence of single user in network. Another switching improves the code security against the on–off energy-level detection at the transmitter end. The mathematical and simulation analysis is performed for the proposed code. The probabilities of code estimation at the transmitter and receiver ends are analysed which shows a better confidentiality. The mathematical analysis shows that the proposed code has a better performance than the existing 1D random diagonal, 1D modified double-weight, 2D perfect difference, and 2D diluted perfect difference codes.

Design of Multiservice Code (MS) in Spectral/Temporal/Spatial Domain for OCDMA System

Abstract This paper explores the design of multiservice code (MS) in spectral, time spreading and wavelength domains (3-Dimensional). The proposed 3D code is designed in such a manner that follows the ideal in phase unit cross correlation in spectral, time spreading and wavelength domains. The proposed encoder generates the MS code effectively in 3D domain and decoder suppresses the multi-user interferences successfully. Performance analyses are carried out by considering the all noises such as phase induce intensity noise(PIIN), shot noise and thermal noise. The analysis of 3D-MS code for variable code length is also performed for measurement of variation in bit error rate against the received power and number of active users in the design. The observed performances are also compared with existing codes such as 2D-MDW, 3D-PDC and 1D-MS code and the proposed code shows the better performance. The analysis of bit error rate of proposed code is carried out against the number of users at 0.622Gbits/s data rate and 0 dBm received power and comparison is also formed with the existing code such as 3D PD(M=21, N=3, P=3), 2DMDW(M=63, P=3), PDC(M=57, P=3) and 1D MS Code. It is noted that 3D MS code shows the better performance than the existing methods. Analysis is also evaluated for variable weight and variable length codes in order to observe the variation in bit error rate with variation in received power and number of simultaneous users.

OCDMA technique with the switching of code between the users for enhancing the security

A new technique is proposed for optical code division multiple accesses for enhancing the security against the eavesdropper. Switching of the pulse spectrum of code is performed between the two users and switching position of the pulse spectrum of code varies from group to group. In this technique every pulse of a code does not have direct information. Code detection probability of individual user decreases against the eavesdropper. The analysis and simulation result compares with the exiting method MQC, RD and MDW code.