Vivek K. Dwivedi

A Novel Mgf Based Analysis of Channel Capacity of Generalized-K Fading with Maximal-Ratio Combining Diversity

In this paper, we have analyzed the channel capacity by using the maximal-ratio combing (MRC) diversity scheme for communication systems operating over a composite fading environment modeled by the Generalized-K distribution at the receiver. For the Generalized-K fading channel with arbitrary values for small and large scale fading parameters, we have derived a closed-form expression for the moment generating function (MGF) of the received signal-to-noise ratio (SNR) and utilized it to obtain a novel closed-form expressions for the channel capacity under difierent adaptive transmission schemes. The result of the proposed methods is compared with other reported literature to support the analysis.

Repeated correlative coding scheme for mitigation of inter-carrier interference in an orthogonal frequency division multiplexing system

In this study, a repeated correlative coding scheme is proposed to combat the inter-carrier interference (ICI) caused by the frequency offset in orthogonal frequency division multiplexing (OFDM) communication systems. This proposed scheme combine two ideas of the well-known methods, which are the coding of adjacent subcarriers with antipodal of the same data symbol (ICI self-cancellation) and correlative coding. A mathematical expression for the carrier-to-interference ratio (CIR) by using this proposed repeated correlative coding scheme is derived. The simulated result of CIR for the proposed scheme is significantly improved compared to the correlative coding as well as a self-cancellation scheme. The bit-error-rate (BER) of the proposed scheme is also compared with the ICI self-cancellation scheme and correlative coding scheme, which is comparable to that of the ICI self-cancellation scheme and better than the correlative coding scheme.

Improved BER analysis of OFDM communication system on correlated Nakagami-m fading channel

In this paper, performance of OFDM digital communication systems have been analyzed over correlated Nakagami-m fading channel using maximal ratio combining (MRC) diversity at the receiver. We have studied statistical characteristics of inter-carrier-interference over correlated Nakagami-m fading channel and also presented signal to interference noise ratio (SINR) over correlated Nakagami-m fading channels. We also derived a novel mathematical expression of bit error rate (BER) for QPSK/QFSK OFDM systems.

A new windowing function to reduce ICI in OFDM systems

A new transmitter side windowing function to reduce inter-carrier interference (ICI) in orthogonal frequency division multiplexing (OFDM) systems with carrier frequency offset is proposed in this paper. The results show that the proposed method outperforms all the recently proposed windowing functions in the literature in terms of average signal power to average ICI power ratio (SIR), bit error rate (BER) and peak to average power ratio (PAPR).

Error-rate analysis of the OFDM for correlated Nakagami-m fading channel by using maximal-ratio combining diversity

In this paper, we have analyzed the performance of correlated Nakagami-m fading channel by using the maximal-ratio-combing diversity at the receiver. A closed-form mathematical expression is derived for the average bit error rate (BER) for binary phase-shift keying (BPSK) and average symbol-error-rate (SER) for M-Quardrature amplitude modulation (M-QAM) scheme in terms of the higher transcendental function such as Appell hypergeometric function by using the well-known moment generating function (MGF)-based approach with arbitrary fading index for the orthogonal frequency division multiplexing (OFDM) communication systems. Moreover, we also derived an expression for the outage probability and the proposed numerical results are compared with the reported literature.

Joint Overlay-Underlay Optimal Power Allocation in Cognitive Radio

In this paper a novel cognitive radio system model is proposed in which secondary user transmitter (SU-Tx) operates under two modes underlay and overlay, based on the channel sensing information it receives. This is an effort to maximize transmission data rate based on the threshold which decides the mode of operation. In this paper, the resources are utilized efficiently by making them operate in both the modes. It provides the optimal power allocation to the CR user in a way that it should not provide interference to its neighbouring users, specifically the most prioritized primary/licensed users. The performance of each mode is analyzed with attainable ergodic and outage capacity.

Moment Generating Function Based Performance Analysis of Maximal-Ratio Combining Diversity Receivers in the Generalized-K Fading Channels

In this paper, we have analyzed the performance of maximal ratio combing (MRC) diversity receiver of the wireless communication systems over the composite fading environment, which is modelled by using the generalized-K distribution. However, this distribution has been considered as a versatile distribution for the precise modelling of a great variety of the short-term fading in conjunction with the long-term fading (shadow fading) channel conditions. In this proposed analysis, we have derived the mathematical expression for the moment generating function (MGF) of the generalized-K fading channel model that is used to evaluate a novel closed-form expression of the average bit error rate for (BER) the binary phase-shift keying /binary frequency-shift keying and average symbol error rate (SER) for the rectangular quadrature amplitude modulation scheme. We have also derived the mathematical expressions for the outage probability as well as the channel capacity for the generalized-K fading channel model.

Analysis of Channel Capacity of Generalized -K Fading with Maximal-Ratio Combining Diversity Receivers

In this paper, we have analyzed the channel capacity of the maximal -- ratio combing (MRC) diversity scheme over Generalized-K fading channels model at the receiver. For this analysis, we have evaluated the moment generating function (MGF) for the Generalized-K fading channel model. The derived MGF expression is used to obtain, new closed-form expression for the channel capacity under different adaptive transmission schemes.

Joint chunk, power and bit allocation in multicast OFDMA system with average BER constraint

In this paper, resource allocation in multicast OFDMA system has been studied using joint chunk, power and bit allocation scheme. Multicasting is widely used in broadband wireless systems in which the same information is transmitted to many users at the same time while making minimum use of network resources. To reduce the complexity of the system resource allocation is carried out chunk by chunk. We propose an approach to maximize the overall throughput while decreasing the outage probability of the subcarriers. Numerical results show that in a multicast OFDMA system the throughput with joint chunk, power and bit allocation scheme is higher than the given chunk-based allocation scheme.

Performance Comparison of BPSK in Rayleigh and AWGN Channel by Monte Carlo Simulation Method

Wireless communications has witnessed a tremendous growth during the past decade and further spectacular enabling technology advances are expected in an effort to render ubiquitous wireless connectivity a reality. The first step towards high speed digital communication over a wireless media includes the understanding of the channel and its characteristics. In a wireless media we have multipath components because of scattering, diffraction, reflection etc. In this paper we are comparing the performance of BPSK in AWGN and Rayleigh fading channel. We are using Monte Carlo based algorithm for the same. Here we will compare BER using simulated and theoretical results.