Puspraj Singh Chauhan

A New Closed-Form Expressions of Channel Capacity with MRC, EGC and SC Over Lognormal Fading Channel

In this work, we derive the closed-form expressions of channel capacity with maximal ratio combining, equal gain combining and selection combining schemes under different transmission policies such as optimal power and rate adaptation, optimal rate adaptation, channel inversion with fixed rate (CIFR) and truncated CIFR. Various approximations to the intractable integrals have been proposed using methods such as Holtzman and Gauss–Hermite approximations and simpler expressions are suggested. Moreover, as an application, the channel capacity of lognormally distributed fading channel in the interference-limited environment is discussed. The obtained closed-form expressions have been validated with the exact numerical results.

Turbo decoding in ISI channels

Turbo codes are family of forward error correcting codes, whose performance is near Shannon limit. Turbo decoding is based on the maximum a-posterior algorithm (MAP) algorithm. In this paper, the problem of turbo decoding in ISI channel is studied. A Super-trellis structure method has been presented and modified turbo decoding is suggested. Two methods have been suggested for turbo decoding in ISI channel. In the first method, we take all possible combinations of output of encoder-2 and in method-2, output of each encoder is passed through channel filter independently. Method-2 performs better than method-1 but requires higher bandwidth. The improvement in performance is demonstrated through simulations.

A Novel Approach to Predict Field Strength in the Shadow of a 3-D Building Scenario

A novel approach to predict field strength in the shadow of a 3-D building scenario is presented. The field strength predicted by the proposed model is compared with available measurements and earlier predicted fields based on Fresnel-Kirchhoff theory. Two different scenarios have been considered to validate our model. The proposed model gives an improvement of 7.7 dB for Scenario 1; and 5.8 dB for Scenario 2. A good agreement between the prediction and the measurement is also observed.

Asymptotic Symbol Error Rate Analysis of Weibull/Shadowed Composite Fading Channel

In this work, we derive the asymptotic expressions of the average symbol error probability (SEP) of a wireless system over the Weibull-lognormal fading channel. First, we evaluate an approximation of the multipath distribution at the origin then the composite distribution is obtained by averaging the approximate multipath probability density function (PDF) with respect to shadowing. The result is further extended to include maximal ratio combining (MRC), equal gain combining (EGC), and selection combining (SC) PDF at the origin. The derived expressions of the composite PDF are further utilized to evaluate the average SEP for both coherent and non-coherent modulation schemes. The derived expressions have been corroborated with Monte-Carlo simulations.

Modelling and Performance Analysis of Energy Detector Over Weibull–Shadowed Fading Channel with Application to Cooperative Sensing

AbstractIn this work, we investigate and analyse the performance of the energy detector over Weibull–Shadowed composite fading channel. To this end, we have derived the novel expressions for the probability of detection (PD) and the average area under the receiver operating characteristic curve (AUC). Furthermore, the asymptotic analysis of such performance metrics has been carried out and the simpler and closed-form expressions of the PD and the average AUC have been proposed with maximal ratio combining, equal gain combining, and selection combining diversity schemes. Finally, the derived results have been applied to cooperative system considering erroneous channel between secondary users and a fusion center. The derived expressions are valid for both integer and non-integer values of the multipath and shadowing parameters. The derived analytical results are corroborated by both exact numerical results and Monte-Carlo simulations, and it is shown that the performance of cooperative system not only depends on the parameters of composite fading distribution but also on the erroneous feed-back channel.

A Novel Approach to Over-Rooftop Multiple Diffractions by an Array of Buildings of Arbitrary Height and Spacing for Mobile Radio Wave Propagation

A new approach to obtain field at the receiver due to multiple over-rooftop diffraction by an array of buildings with irregular height and spacing is presented. In the literature, the available approach is based on ray-tracing method that requires higher order diffraction coefficient (slope diffraction). The proposed method is efficient in the sense that it does not require higher order diffraction term to compute field strength. The method is validated by comparing the predicted results with available measurements and earlier results from the literature.

A Novel Approach for Turbo Decoding In ISI Channel

codes are family of forward error correcting codes, whose performance is near Shannon limit. Turbo decoding is based on the maximum a-posterior algorithm (MAP) algorithm. In this paper, the problem of turbo decoding in ISI channel is studied. A Super-trellis structure method has been presented and modified turbo decoding is suggested. Two methods have been suggested for turbo decoding in ISI channel. In the first method, we take all possible combinations of output of encoder-2 and in method-2, output of each encoder is passed through channel filter independently. Method-2 performs better than method-1 but requires higher bandwidth. The improvement in performance is demonstrated through simulations. Keywordscode, Intersymbol interferance, ISI channel, Iterative decoding, Turbo code.

Improved deterministic model for the characterization of wireless channel

In this work, we present an improved deterministic model to characterize the field in the shadow of a building. The model includes the higher order diffraction coefficient (slope diffraction) and transmission through the building. A generalized transmission model for a series of n buildings is also presented. The proposed model is validated for a single building scenario with the available measurements.