Aasheesh Shukla

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.

Performance Boosting in IDMA System Using Helical Interleaver and Gold Codes

In Interleave Division Multiple Access (IDMA) scheme, interleavers have significant importance in the performance of whole system. In recent years interleavers have been proved to give the best performance in terms of data security and noise immunity, but huge memory requirement and complexity are major concerns for specifying the interleaver pattern. A new helical interleaver based IDMA system has already proposed due to some distinct advantages such as low system complexity and significant reduction in memory requirement as well. In this paper the performance of layer specific helically interleaved IDMA (HIDMA) system has been compared to randomly interleave and tree based IDMA with BPSK coding and with Gold Codes. Evaluation is done on the basis of mathematics and results are simulated in MATLAB.

Application of Antenna Diversity in HIDMA Scheme Using Gold Codes

In Interleave Division Multiple Access (IDMA) scheme, interleavers play a vital role. In recent years IDMA have been proved to give the good performance in terms of data security and noise immunity, but huge memory requirement and complexity are major issues for specifying the interleaver pattern in this scheme. This paper presents the helically interleaved IDMA (HIDMA) system. HIDMA system not only achieves the performance as well as RI-IDMA (randomly interleaved) but also renders the system with low complexity and significant reduction in memory requirement. The performance can be improved significantly by the inclusion of Gold Codes in the system. Further, to take the system into practical considerations the performance of the system is examined in a fading environment. Maximal Ratio Combining (MRC) approach has been utilized using antenna diversity (transmit diversity) to combat the fading error. Evaluation is done on the basis of mathematical analysis and simulations in Rayleigh Fading Environment.

Performance analysis of modified tent map interleaver in IDMA systems

Abstract In the last years, Interleave Division Multiple Access (IDMA) has been presented as a potential alternate of Code Division Multiple Access (CDMA) system. In IDMA systems, the interleavers are used to separate the users of the system in multiple access environments. Random interleaver is popular and basic taxonomy, which scrambles information bits of craving users with different patterns. However the indispensable characteristics of a random interleaver such as bandwidth requirement, computational complexity, and memory restraint at both transmitter and receiver end is uttermost. Further, it has also been observed that the study of role of chaos in interleaver design is very limited in literature. Hence, in this paper, a low complexity chaos based interleaver named as modified Tent map interleaver is designed for further performance improvement of IDMA system and the characteristic parameters are compared with the random interleaver. The IDMA system model uses a BPSK modulation and repetition coder with a code rate of 1/2. The system is simulated in MATLAB and results show that the better BER performance without the need of extra memory resources.

Performance Analysis of PAPR Reduction in Helical Interleaved OFDM System

Orthogonal Frequency Division Multiplexing (OFDM) is one of the most promising technique for the fourth generation (4G) communication. High spectral efficiency, immunity to channel interference and nonlinear distortions are some advantages of OFDM. But frequency offset and high peak-to-average power ratios (PAPR) for large number of sub-carriers are two major drawbacks for practical application. This paper presents the PAPR reduction techniques for OFDM system such as interleaving and different phase rotation schemes. Selected mapping (SLM) and partial transmit sequence (PTS) are applied with mentioning distinct conditions for the application of these techniques. This paper also presents helical interleaver in OFDM system, for the reduction of system complexity and significant reduction in memory requirement as well. Evaluation is done on the basis of mathematical analysis and mentions best way to simulate in step-wise manner in MATLAB.

Cooperative relay beamforming in IDMA communication networks

Abstract In this paper, a new combination of Interleave division multiple access (IDMA) and spatial diversity offered by cooperative relay aided distributed beam forming is proposed. In the offered scheme communication strategy consists two steps. All users broadcast their message to relays in the first step and then relays amplifies and forward the information to the desired destination. IDMA, which is popular non-orthogonal multiple access (NOMA) technique is used to combat the effect of multiple access interference (MAI) at relay as well as destination nodes. Each relay processed the signal to maintain the QoS of destination. The goal of this work is to find the appropriate beam forming weights by minimising the transmit power and without compromising the QoS in terms of SINR. However power minimization is not the convex problem, so semi-definite relaxation is used to modify the problem in to semi-definite programming (SDP) problem and the conventional SDP problem solver CVX is used for solution. The numerical explanation and simulation experiment of the proposed scheme shows the performance improvements in terms of bit error rate.