M. Shukla

Analysis and design of Tree Based Interleaver for multiuser receivers in IDMA scheme

Here, we propose a novel tree based interleaver (TBI) for generating user specific chip-level interleaving sequences for various users in an IDMA system, which reduces computational complexity drastically. This interleaver also solves the memory cost problem and reduces the amount of information exchange between mobile stations and base stations required to specify the interleaver. Simulation results are presented to show that the proposed TBI perform well as compared to master random and random interleavers in an IDMA scheme.

Performance analysis of first iteration koch curve fractal log periodic antenna of varying flare angles

Miniaturization has always been a crucial challenge in the field of antenna engineering. In the recent past a number of researchers have shown that fractal geometry have potential to design smaller, broad band and multi band antennas. In this proposed work performances of log periodic fractal antennas of different flare angles have been investigated. Simulation results show that fractal log periodic antenna gives better performance in terms of gain, return loss and directivity. Performance of log periodic fractal antenna has also been investigated for flare angles 30°, 45°, 60°, 70° and 80°. In this proposed work fractal antenna gives best performance with 60° flare angle.

Performance Analysis of Optimum Interleaver based on Prime Numbers for Multiuser Iterative IDMA Systems

In recently proposed multiple access techniques like IDMA and OFDM-IDMA, the user separation is done by user specific interleavers in contrast to the conventional CDMA scheme, where user separation is assured with user-specific signature sequences. The user specific interleavers must demonstrate minimum probability of collision amongst each other in addition to other merits, including minimal consumption of bandwidth, least hardware for their generation, and least memory requirement. In this paper, the authors propose an interleaver based on prime numbers for the generation of user specific interleavers to remove the problem of high consumption of bandwidth. The simulation results demonstrate the optimal performance of prime interleaver PI, which is based on prime numbers, apart from other merits in comparison to random and other interleavers.

Performance Evaluation of MRC Diversity Scheme for Iterative IDMA Receivers

In wireless communication, fading problem is mitigated with help of diversity techniques. This paper presents Maximal Ratio Combining (MRC) diversity approach to uproot the fading problem in interleave-division multiple- access (IDMA) scheme. The approach explains maximal ratio combining diversity technique, with one transmit and two received antennas in low rate coded environment. In the simulations, random interleaver as well tree based interleaver has been taken for study. The simulation results demonstrates that in both environments, tree based interleavers outperforms the random interleaver. Significant improvements in performance of IDMA scheme is observed with MRC diversity technique.

Prime Number Based Interleaver for Multiuser Iterative IDMA Systems

In recently proposed multiple access techniques such as IDMA and OFDM-IDMA, the user separation is done by user specific interleavers in contrast to conventional CDMA scheme where user separation is assured with user-specific signature sequences. The user specific interleavers must demonstrate minimum probability of collision amongst each other in addition to other merits including minimal consumption of bandwidth, least hardware for their generation, and least memory requirement. Previously, random interleaver and other interleavers proposed by researchers is still leaving some space for further research leading to optimality of interleavers. In this paper, we propose a novel interleaver based on prime numbers for generation of user specific interleavers to remove the problem of high consumption of bandwidth. The simulation results demonstrate the optimal performance of prime interleaver (PI) apart from other merits in comparison to random and other interleavers.

Optical interleave-division multiple-access scheme for long distance optical fiber communication

In this paper, we are proposing a novel optical multiple access approach which utilizes the interleaving as only means of user separation. This is different from conventional code division multiple access schemes in which different signature sequences are used to distinguish users. Optical interleave-division multiple-access (OIDMA) scheme inherits the advantage of both Optical system and IDMA technique. For pulse propagation in optical fiber, the nonlinear linear Schrödinger equation (NLSE) is used. On-Off keying (OOK) is used for pulse transmission. It is demonstrated that optical IDMA has better bandwidth utilization and less multiple access interference. Optical IDMA technique shows that high performance can be maintained with large number of users.

Performance Analysis of Tree Based Interleaver with IDMA Systems Using Optimum Power Allocation Algorithm

Power allocation with unequal strategy, is a technique to further enhance system performance in multiple access schemes. This paper is basically related with the performance enhancement of iterative IDMA systems using unequal optimum power allocation algorithm. Here, we compare the performance of coded and uncoded IDMA system with random interleaver & tree based interleaver. The simulation results demonstrate the superior performance of tree based interleaver in comparison to random interleaver in view of memory requirement along with similar BER performance.

Underwater Communication with IDMA Scheme

Underwater communication finds numerous application including oceanographic data collection, pollution, monitoring, offshore exploration, disaster prevention, assisted navigation, tactical, surveillance, and mine reconnaissance. The enabling technology for these applications is acoustic wireless networking. A major challenge for the deployment of UW-ASN is the development of a multiple-access technique and modulation technique tailored for the underwater environment. Typical frequency ranges from 1 Hz to 1 MHz resulting in low data rates. The ever-increasing demand of short- and long-distance communication is leading to further research in the field of underwater communication. In this paper, performance analysis has been done for underwater acoustic (UWA) communication with IDMA scheme using BPSK modulation techniques. fThe simulated system is subjected to additive white Gaussian noise (AWGN) in the channel in uncoded environment using random interleavers in MATLAB environment.

Representation and Calculation of Correlation Constraints of One Dimensional Unipolar Orthogonal Codes

The one dimensional unipolar orthogonal codes are employed as signature sequences in spread spectrum modulation schemes like incoherent optical CDMA system. The cardinality or upper bound of code set, containing one dimensional unipolar orthogonal codes of code length n and code weight w and correlation constraint λ, is given by Johnson bounds. Conventionally these codes are represented by weighted position representation (WPR) or position of bit 1s in the code. The auto-correlation and cross-correlation constraints of the unipolar orthogonal codes are calculated using the binary sequences equivalent to these codes in WPR. In this paper two other representations of one dimensional unipolar orthogonal codes are proposed as well as two methods for calculation of correlation constraints of these unipolar orthogonal codes.

A novel approach for lifetime analysis of sensor network using fuzzy logic

Lifetime enhancement has always been of crucial importance for energy constrained sensor network due to resource limitations of sensor nodes. In the recent past some researchers have suggested mobile sink method to enhance the lifetime of sensor network. Most of the energy is consumed in data transmission from sensor nodes to the base station. This is the main reason for energy dissipation in wireless sensor network. This energy dissipation can be minimized by using mobile base station. Motion of the base station can be effectively governed by fuzzy logic based method. In this paper lifetime of wireless sensor network has been analyzed in which base station is free to move over a square shaped path. Simulation results show that this scheme in which base station is moving over square shaped path gives better lifetime than other existing schemes.