Papers by ranjan gangopadhyay
Journal of Optical Communications, 1991
Perfonrance of coded M-ary Pulse Position Modulation (M-PPM) systems in the presence of slot sync... more Perfonrance of coded M-ary Pulse Position Modulation (M-PPM) systems in the presence of slot synchronization errors is evaluated for the shot-noiselinr.tcd photon-counting receiver and the avalanche photodetection (APD) receiver. In the APD case, a well known 'timing recovery scheme is proposed to behave as a slot synchronizer and its timing jitter variance is obtained. The performance degradation of the coded M-PPM systems due to slot synchronization error is presented for the above receiver models.
IETE Journal of Research, 1975
A systematic method of generating explicit Lyapunov functions for linear time-varying differentia... more A systematic method of generating explicit Lyapunov functions for linear time-varying differential equations is presented in this paper. The linear time-varying system equation is decomposed into a fixed part and a time-varying part. A simple closed form expression of the Lyapunov function for the fixed part has been derived. This has been suitably augmented and applied to the time-varying system in the determination of stability results. Only first-order time-derivatives on the time-varying parameters of the system are involved in the stability results.
2018 24th Asia-Pacific Conference on Communications (APCC)
Device-to-Device (D2D) networks would play a paramount role in meeting the steep operational targ... more Device-to-Device (D2D) networks would play a paramount role in meeting the steep operational targets of 5G. D2D networks enable proximity based communication links, allowing the cellular network to scale up substantially with minimal impact on core network resources. Adoption of Radio Environment Map (REM) would help in transcending the performance gains from upper layers to physical layer as well. In this paper, performance evaluation of prevalent REM techniques and sensor deployment strategies has been carried out in Nakagami-m and Nakagami-lognormal channels. The results obtained support adoption of Crowd-Sensing (CS) with Inverse Distance Weighting (IDW) in D2D scenario, especially in public safety applications.
2019 International Conference on Wireless Communications Signal Processing and Networking (WiSPNET), 2019
Device-to-Device (D2D) communication has been proved to be a promising technique to efficiently u... more Device-to-Device (D2D) communication has been proved to be a promising technique to efficiently utilize the radio spectrum thereby enhancing the capacity and meeting the huge data rate requirements of the future wireless networks. However, in underlay D2D communications, channel allocation (CA) is a challenging problem so as to limit the cross-tier interferences below a certain threshold. Most of the existing works on CA are based on maintaining minimum quality-of-service (QoS) requirements only for cellular users (CUs), or the D2DQoS constraints in a non-fading scenario. Moreover, most of them assume that the central controlling entity has all the prior information about the incoming D2D users, which appears unfeasible. In this work, we consider a more realistic underlay D2D communication scenario, and introduce an outage probability-based QoS constraint on the D2D links for enhanced reliability; in the presence of the combined effect of path-loss and fading. The channels are allocated online by maximizing the sum-outage-capacity of the full-duplex D2D network. The efficacy of the CA algorithm has been evaluated through rigorous simulations and the results have been numerically analyzed.
2016 IEEE 27th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), 2016
Diversity reception schemes are well-known effective techniques for mitigating the adverse effect... more Diversity reception schemes are well-known effective techniques for mitigating the adverse effects of multipath fading in wireless mobile channels. This paper analyzes the performance of an amplify-and-forward (AF) relay-based cooperative spectrum sensing system with generalized selection combining (GSC) over a Rayleigh fading channel and compare the results with those of the conventional diversity combining schemes such as maximal-ratio-combining (MRC) and selection combining (SC). Novel closed-form expression has been derived for the average detection probability over the independently and identically distributed (i.i.d) diversity paths. Receiver operating characteristics (ROCs) and the average detection probability versus the average signal-to-noise ratio (SNR) curves have been presented for different scenarios of interest.
Transactions on Emerging Telecommunications Technologies, 2018
For a cognitive radio (CR) user to dynamically access the available primary user channels, the sp... more For a cognitive radio (CR) user to dynamically access the available primary user channels, the spectrum sensing data is required at various locations; however, the data is not generally available at the points present in between the two spectrum sensors. To obtain this data, it is also not feasible to conduct the spectrum measurement surveys at every location. This calls for an interpolation-based spectrum occupancy data collection in the space. Moreover, the information about the future primary user activity is necessary for highly enhanced dynamic channel allocation with better quality of experience (QoE) of CR users in terms of improved channel utilization and reduced spectrum sensing energy requirement. Most of the existing works are inclined toward either spatial spectrum interpolation or temporal spectrum prediction. In this work, a novel hybridized approach combining the Kriging-based statistical spatial interpolation and the recurrent neural networks-based temporal prediction of the spectrum has been proposed to obtain the spectrum occupancy probability information using empirical spectrum measurements data in cellular CR networks. Furthermore, the aforementioned framework has been utilized for dynamic channel allocation with the help of a newly investigated CR channel allocation scheme. The corresponding results have been validated through various CR QoE measures and compared with the existing channel allocation strategies, where it is found that the proposed channel allocation scheme significantly outperforms the other schemes with the enhanced QoE of CR. Finally, a spatio-temporal channel allocation map has been presented for secondary user to perform its best possible CR operation with efficient dynamic spectrum access.
Journal of Optical Communications, 1999
The sensitivity penalty of a direct detection 10 Gbit/s optical CPFSK receiver due to laser phase... more The sensitivity penalty of a direct detection 10 Gbit/s optical CPFSK receiver due to laser phase noise, interferometric intensity noise and chromatic dispersion is determined analytically at a BER of 10~9. The analysis is based on linear approximation of the output phase of a linearly filtered CPFSK signal. The significant contributory role of the laser phase noise with increasing value of chromatic dispersion index is highlighted. The theoretical results have been found to be in excellent agreement with the simulation results.
Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2016
Diversity reception schemes are well-known to have the ability to mitigate the adverse effects of... more Diversity reception schemes are well-known to have the ability to mitigate the adverse effects of multipath wireless channels. This paper analyzes the performance of an energy detector with generalized selection combining (GSC) over a Rayleigh fading channel and compares the results with those of the conventional diversity combining schemes such as, maximal-ratio combining (MRC) and the selection combining (SC). Novel closed-form expressions have been derived for the average detection probability over the independently, identically distributed (i.i.d) diversity paths. Receiver operating characteristics (ROCs) and average detection probability versus SNR curves have been presented for different scenarios of interest.
COIN-NGNCON 2006 - The Joint International Conference on Optical Internet and Next Generation Network, 2006
Abstract A comparison between path and span protection schemes has been carried out for a just-en... more Abstract A comparison between path and span protection schemes has been carried out for a just-enough-time (JET) based optical burst switched (OBS) network in case of single link failure utilizing the network link state information.
Procedia Computer Science, 2015
Spectrum sensing is the key technology in cognitive radio for the efficient use of radio spectrum... more Spectrum sensing is the key technology in cognitive radio for the efficient use of radio spectrum. The implementation of energy detection based spectrum sensing is done with the assumption of constant activity of the primary user. Practically, often the scenario occurs when primary user transmits signal in the frequency band of interest only for a fraction of the observation period. The paper aims at analyzing the degradation in performance of energy detection based sensors in the case of generalized κ-μ and α-μ fading channels. The theoretical results indicate low reliable performance in the case of fading channel due to primary user duty cycle variation at low signal-to-noise ratios.
Computer Communications, 1998
The impact of link failures on the performance of multihop lightwave networks such as shufflenet ... more The impact of link failures on the performance of multihop lightwave networks such as shufflenet (SN), hypercube (HC), is evaluated by detailed computer simulation study. The degradation in network throughput of the above networks due to link failures is compared for several routing schemes, namely store-and-forward (SF), hot-potato (HP), and single-buffer deflection (DF) routing. The throughput degradation due to link failures is found to be minimum for HP routing. The HC network is much better suited for surviving multiple failures than SN of the same size. The simulation study is also extended to consider the impact of link failures in multiwavelength shufflenet (MWSN) employing dynamic wavelength routing. For MWSN, the degradation in throughput increases with m, the number of wavelengths per fiber link. 0 1998 Elsevier Science B.V.
IEEE Transactions on Communications, 1991
Performance of convolutionally coded M-ary pulse position modulation (M-PPM) systems in the prese... more Performance of convolutionally coded M-ary pulse position modulation (M-PPM) systems in the presence of slot synchronization errors is evaluated for the shot-noise-limited photon-counting receiver and the avalanche photodetection receiver. Both hard and soft (δ-max) demodulation results are given, and two soft-decision metrics are investigated
Electronics Letters, 1991
Asia-Pacific Conference on Communications, 2003
The paper presents an efficient algorithm for routing and wavelength assignment for dynamic light... more The paper presents an efficient algorithm for routing and wavelength assignment for dynamic lightpath establishment as well as bandwidth guaranteed path protection against single link failure in WDM mesh network. Several protection strategies for multiwavelength optical network have been studied to indicate their relative efficiency in terms of network blocking probability and resource requirement.
International conference on fiber optics and photonics, 1997
Optical multi-wavelength transport networks (MWTN) have generated considerable recent interests b... more Optical multi-wavelength transport networks (MWTN) have generated considerable recent interests because of their inherent capability to achieve higher information capacity, greater flexibility, efficient routing, transparent switching, reconfugarability etc.. The effect of switch cross-talk, adjacent channel cross-talk, filtering effect, accumulated ASE in MWTN has been recently addressed. However, the performance of closely packed WDM systems with dispersion shifted fibers is highly vulnerable to the effect of FWM. The present study investigates the degradation encountered in multi-wavelength switched optical network due to the combined influence of receiver noise, phase noise, accumulated amplified spontaneous emission (ASE), FWM crosstalk and dispersion. For each channel CPFSK modulation is considered with direct detection receiver employing Mach-Zehnder interferometer (MZI). The analysis is carried out to include the combined effect of accumulated optical amplifiers’ spontaneous emission (ASE) noise and the beat noise components viz. signal-spontaneous emission beat noise, ASE-ASE beat noise, adjacent channel-spontaneous beat noise, signal- FWM beat noise, FWM-spontaneous beat noise etc.. An expression for the probability density function (pdf) of the random phase fluctuation due to FWM effect is developed and the bit error rate is estimated at each node for different number of channels. In the present analysis, a node architecture of the optical mesh network is considered in which an interconnection between two consecutive nodes consists of optical in-line amplifiers, optical space-switches, power splitters, wavelength multiplexers and demultiplexers and the fiber protection switch. All the wavelengths are combined in the multiplexer and amplified before feeding to the transmission fiber. The gains of the in-line amplifiers are adjusted to compensate for the losses in the fiber, splitters and other passive components. The demultiplexer separates the desired signal wavelength from the WDM multiplex and is realized by a Febry-Perot filter (FPF) tuned to the desired signal channel. The node uses M transmitters and M receivers if M is the number of wavelength channels. Computations of results are carried out at a bit rate of 2.5 Gb/s for several fiber spans with different sets of system parameters, viz. number of channels, number of nodes, optical SPIE Vol. 3211 • 0277-786X/97/$10.00? wavelength from the WDM multiplex and is realized by a Febry-Perot filter (FPF) tuned to the desired signal channel. The node uses N transmitters and N receivers if N is the number of wavelength channels
2012 5th International Conference on Computers and Devices for Communication (CODEC), 2012
Wireless body area networks (WBAN) are being increasing developed for medical healthcare includin... more Wireless body area networks (WBAN) are being increasing developed for medical healthcare including medical diagnosis, remote health monitoring and medical alert. The talk will highlight comprehensive planned initiative for establishing an end-to-end mobile platform based on WBAN and associated body sensors for pervasive healthcare.
9th Asia-Pacific Conference on Communications (IEEE Cat. No.03EX732)
The performance achievable with turbo codes for MC- CDMA in fading channel has been recently repo... more The performance achievable with turbo codes for MC- CDMA in fading channel has been recently reported [C. Ghosh et al., 2003]. Further performance gain can be achieved by jointly using turbo decoding and multiuser detection. Turbo decoding in combination with detection strategy for multi-access interference (MAI) cancellation has been shown to be very effective for MC-CDMA system in Rayleigh multipath fading environment. This paper reports new simulation results on the efficacy of joint decoding and detection for MC-CDMA in a nonlinear and fading channel.
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Papers by ranjan gangopadhyay