Comparative Study of Random and Tree Base Interleaver for Optical IDMA

This paper presents high-spread (HS) random interleavers based interleave-division multiple access (IDMA) scheme. High-spread feature of a randodecm interleaver offers high-spread characteristics to interleavers and thus produces extrinsic values with low correlation. As interleavers are key components for user separation in the IDMA, the HS interleavers are employed in the IDMA for performance improvement. In addition, by replacing random interleavers with the HS interleavers in the IDMA, bandwidth efficiency is achieved by means of reducing the length of the repetition code. Performance evaluation shows that the proposed scheme of the IDMA with the HS interleavers provides significant BER performance improvement and moderate increase in bandwidth efficiency.

The Interleave-Division Multiple-Access (IDMA) scheme is known for property of orthogonality amongst its user-specific interleavers. The interleavers are, therefore, referred has the heart of IDMA Transceivers. In the literature, researchers have proposed Tree Based Interleaver (TBI) which not only reduces the bandwidth requirement in comparison to that required in case of Random Interleavers (RI) but also reduces computational complexity drastically when compared with that of power interleavers. The memory requirement at receiver end and its cost problem are also solved by tree based interleaver with further reduction of the amount of information exchange between mobile stations and base stations required to specify the user-specific interleavers. In this paper, the performance analysis of iterative IDMA receivers have been evaluated with BPSK & QPSK modulation techniques employing tree based interleavers and random interleavers in uncoded and rate 1/2 covolutionally coded conditions with Additive White Gaussian Noise (AWGN) channel. During the simulation, it has been observed that IDMA system with QPSK modulation techniques employing TBI outperforms its counterparts optimally.

In this paper, we propose a parallel interleaver design for interleave-division multiple-access (IDMA) systems. The advantages of our approach are the low complexity induced from an algebraic solution and the parallel processing with negligible performance degradations against random interleavers. It is specially suitable for parallel implementation of multiple user detections and decoding of IDMA signals, resulting in efficient improvements of system throughput. Simulation results show that the parallel interleavers perform as well as the random interleavers in an IDMA system.

In this paper, let's exhibit the exploitation of Gaussian Approximation (GA) based detection algorithm for Non-Orthogonal Coded Access (NOCA). NOCA belongs to one candidate solution of Non-Orthogonal Multiple Access (NOMA), recently discussed for future wireless communications towards 5th Generation (5G) New Radio (NR) standard. It is well known that GA based detection algorithm was very elegantly introduced in Interleave Division Multiple Access (IDMA). As being an iterative detection approach, the computational requirement belongs to one of the major focuses of GA based detection algorithms. Thus, in this paper, the efficiency in sense of complexity, suitable use cases of GA based detection will be investigated with respect to NOCA and IDMA by link level simulations. Numerical results reveals that both IDMA and NOCA are suitable for sporadic traffic. Especially, NOCA exhibits high detection efficiency for earlier iterations, and IDMA exhibits the capability of overloading and performance convergence under very low Signal-to-Noise Ratio (SNR).

This paper carries comprehensive comparison of Interleave Division Multiple Access (IDMA) and Code Division Multiple Access (CDMA) systems in terms of performance (BER) and behavior to different number of users. Performance analysis of two systems whose transmitter and receiver structures are almost same are studied under Additive White Gaussian Noise (AWGN) and performance differences are illustrated by simulation results. Although Multiple Access Interference (MAI) and Intersymbol Interference (ISI) can affect the performance of the CDMA system, simulation results illustrates that IDMA system model achieves this type of problem using their interleavers. Results also show that large number of users can easily be adapted by the IDMA scheme much easier than CDMA scheme.

In this paper, turbo multiuser detectors in Interleave Division Multiple Access (IDMA) based systems are considered for short range underwater acoustic channels (UACs). In such long reverberant channels that demand high computational complexity, turbo detectors based on minimum mean square error (MMSE) criterion are an attractive solution to achieve a good balance between performance and complexity. Two different synchronous IDMA structures are studied and applied to signals acquired during sea trials in the North Sea; firstly, a channel estimation (CE) based IDMA with Rake reception, and secondly, an adaptive interference canceller (IC-IDMA). Both schemes include phase tracking, channel coding and are based on a chip-rate equalization and detection, which are fed in by a composite multiuser signal of the users' feedback soft information. Experimental results of three different channel ranges demonstrate that the direct adaptive receiver has better performance and additionally mitigates the errors associated with the CE based IDMA receiver while maintaining lower complexity.

Interleave division multiple access (IDMA) is a potential candidate for the future fifth generation (5G) systems. In this paper, we propose a novel architecture for IDMA system with low latency while maintaining low complexity. In the conventional architecture, the IDMA receiver sequentially processes deinterleaving, despreading, spreading and interleaving for multiuser detection. The proposed architecture, which is called the interleaved domain, can perform multi-user detection directly without deinterleaving the received frame. Because of this, the interleaving is no longer needed in the interference cancellation loop resulting in the decrease of latency by half and the increase of throughput by twice. In VLSI implementation results, the proposed architecture has reduced circuit area and power consumption by 53% and 58% compared to the conventional architecture on the same throughput condition.

In this paper, we develop a new one-dimensional chaotic map, completely based on the logistic map: ”New Logistic Map (NLM)”; this new map expand the definition domain of logistic map and their utilization. The simulation results and theoretical analysis of chaotic dynamical behaviours show that the NLM is a chaotic system and has an ideal distribution. It is also characterized by its wide range of definition, and depends on the number of the desired real values.We have applied the NLM to generate the interleaver matrix for Interleave Division Multiple Access (IDMA): NLMInterleaver. Our design easy to generate, and requires a low memory bandwidth consumption (low amount of data can travel over a communications channel), and low computational complexity compared to the literature algorithms.

In an interleave-division multiple access (IDMA) system, interleavers have a crucial role for the system performance. This paper presents a new approach to random interleavers for traditional IDMA systems. The proposed interleaver uses a random variable which is defined by Rayleigh distribution for mapping. Simulation results demonstrate that the proposed interleaver approach improves the bit-error rate (BER) performance of the IDMA systems.

In this contribution, we consider the performance of multi-user transmitter pre-processing (MUTP) assisted interleaved division multiple access (IDMA) scheme for downlink (DL) communications. We realize MUTP using Zero Forcing (ZF)algorithm. In this paper, we consider turbo coded system to achieve high coding gain. We construct the turbo code using parallel concatenated convolutional encoder and certain bits are punctured periodically to achieve code rate ½. We construct the pre-processing matrix using channel state information of all the users. We evaluate the performance of such coded ZF-MUTP assisted IDMA system for realistic channel model based on SUI channel model specifications. From our simulations, we observe that the ZF-MUTP assisted multi-user IDMA system provides better performance in terms of bit error rate (BER) with low signal to noise ratio (SNR).

Problem statement: This study presents the performance analysis of turbo assisted Interleave Division Multiple-Access (IDMA) system with Multi Input Multi Output (MIMO) support for multi user scenario over correlated frequency selective and uncorrelated frequency selective channel. Approach: The key principle of IDMA is that interleaver unique which distinguishes the users in contrast to spreading sequence in Code Division Multiple Access System (CDMA). Results: In this work, we assume that Interleavers are generated independently and randomly. At the receiver, we employed Ordered SIC (OSIC) technique using ZF and MMSE criterion to combat Inter Antenna Interference (IAI) and Multi User Interference (MUI) problem along with iterative decoding to improve the performance in terms of BER. The performance of system has been discussed for different channel conditions with realistic channel model using extensive simulation runs based on Monte Carlo simulation trials. We have exhibited the flexibility and robustness provided by MIMO-IDMA. Conclusion/Recommendations: It has been proved from the results that IDMA principle can be applied to realize many potential performance gains highlighted by information theory, including coding gain multiplexing gain and multiuser gain. Simulation results presented to demonstrate the benefits of IDMA with MUD and iterative decoding. It is discerned that IDMA performs better than CDMA in frequency selective channel for high load conditions which is assessed through computer simulation results.

This paper investigates various interference canceller structures appropriate for interleave division multiple access (IDMA)-based random access in order to support massive machine-type communications (mMTC) in the fifth generation (5G) mobile communication system. To support massive connectivity in the uplink, a grant-free and contention-based multiple access scheme is essential to reduce the control signaling overhead and transmission latency. To suppress the packet loss due to collision and to achieve multi-packet reception, non-orthogonal multiple access (NOMA) with interference cancellation at the base station receiver is essential. We use IDMA and compare various interference canceller structures such as the parallel interference canceller (PIC), successive interference canceller (SIC), and their hybrid from the viewpoints of the error rate and decoding delay time. Based on extensive computer simulations, we show that IDMA-based random access is a promising scheme for supporting mMTC and the PIC-SIC hybrid achieves a good tradeoff between the error rate and decoding delay time.

This paper deals with a system combining orthogonal frequency division multiplexing (OFDM), interleave-division multiple access (IDMA) and space time block coding (STBC). Less investigated in the literature than multicarrier code division multiple access or OFDMA, OFDM-IDMA can be viewed as a promising technique to solve the problem of bandwidth scarcity. With a specific frame organization to estimate the carrier frequency offsets (CFO) and the channels, we suggest a new receiver architecture. Indeed, based on a modification of the standard IDMA receiver where a CFO correction is no longer necessary unlike common OFDM approaches, we show that the transmitted bits can be still recovered. When considering a STBC-OFDM-IDMA uplink system over different Rayleigh channels, simulation results show the efficiency of the proposed algorithm. These results confirm the utility of this technique as a mid-term solution to solve the constant increase of data rate and user density per cell in cellular systems.

Objective: To execute the Avalanche photodiode instead of a PIN photodiode in Optical Interleave Division multiple Access (O-IDMA) communication system and to analyze the performance for high data rate transmission. Methods/Statistical Analysis: The detection of optical signal at the receiver of the O-IDMA system is an important operation and decides the performance of the system. Here the detection is done using Avalanche Photodiode for O-IDMA system and analyzed. Iterative decoder is used for decoding at the receiver using the soft decision method. MATLAB is utilized as a simulation tool. Findings: The simulation results have been demonstrated that Avalanche Photodiode is appropriate than PIN Photodiode. The completion and efficiency of the O-IDMA system can be ameliorated with the utilization of avalanche photo detector. Applications/Improvements: The completion of the O-IDMA system is ameliorated appreciably by utilizing Avalanche photodiode and system support more no. of users, less bit error rate and large data rate transmission.Keywords: Avalanche Photodiode, Bit Error Rate, IDMA Scheme, Optical Fiber, PIN Photodiode

In this paper we investigate the detection algorithms for interleave division multiple access (IDMA) systems in the presence of carrier frequency offsets (CFOs). The existing IDMA detection algorithm is designed under the zero CFO assumption and its performance will be degraded when the CFOs are present. We first extend the existing algorithm to the nonzero CFO case by utilizing effective channel coefficients which take the CFO effects into account. Then we turn to a more practical scenario with imperfect CFO estimates. We propose an algorithm that can cope with the residual CFO effects by integrating the CFO updating into the iterative receiver. Signal-to-interference-plus-noise ratio analysis and simulations show the feasibility and superiority of our proposed algorithms.