Interleave Division Multiple Access System Research Articles

Conversion‐less algebraic interleaver architecture for low‐latency IDMA systems

AbstractThis letter presents a conversion‐less algebraic interleaver architecture for low‐latency interleave division multiple access (IDMA) systems. The existing architectures adopt the two‐step approach that first generates a set of sequential indices, and then converts it into a set of interleaved indices, elongating the latency. In contrast, the proposed structure directly produces the interleaved indices by employing a logic that keeps returning the next index corresponding to the current one. As a result, it can greatly alleviate the latency compared with the existing schemes in the literature.

Progressive pattern orthogonal interleaver set for interleave division multiple access based, non orthogonal multiple access schemes: Beyond 5G perspective

Abstract This communication suggests an orthogonal interleaver set for interleave division multiple access (IDMA) based non orthogonal multiple access (NOMA) schemes from beyond 5G viewpoint to support enormous increase in user count. The method generates an orthogonal interleaver set by providing two mother interleavers as seed to generate other users’ interleaving patterns progressively. The key feature of the proposed scheme is that it reduces implementation complexity and memory requirement at the base station, while implementing iterative multiuser detection (MUD), which most of the interlaever designs suggested in literature do not consider. It provides additional security to the user data due to progressively changing mother interleavers’ pattern along with the conventional purpose of providing unique identity for individual users in the system. The proposed orthogonal interleaver set is tested through simulations under multiple IDMA system configurations. It has been observed that it preserves the bit error rate (BER) performance of the IDMA scheme along with the optimal implementation complexity and minimal information exchange requirement between base station and mobile station to share the interleaver design.

Fixed‐latency architecture for multi‐stage algebraic interleavers in interleave division multiple access systems

In this letter, a fixed-latency interleaver architecture is proposed for interleave division multiple access (IDMA) systems. The existing multi-stage algebraic interleaver suffers from the high latency originated from a series of multipliers and adders residing in each stage. In contrast, the proposed interleaver employs a simple conversion logic built by precomputing all the requisites in advance. Since the logic is completely irrelevant to the number of stages, the interleaving pattern of the proposed structure can be randomized as much as it is needed without exacerbating the latency at all.

Robust Rateless Spatially Coupled Repeat-Accumulate-Repeat Multi-User Codes on IDMA Systems

In this paper, we design a kind of robust rateless multi-user code, which is called spatially coupled repeat-accumulate-repeat (SC-RA-R) code, for the interleave-division multiple-access (IDMA) system. The code is constructed by serially concatenating a fixed outer spatially coupled repeat-accumulate (SC-RA) code with an adjustable inner irregular repetition code. It achieves rateless property by simply adjusting the parameters of the inner repetition code. The IDMA system with the proposed SC-RA-R multi-user codes can adapt to varying channel qualities and varying number of users via rateless property while keeping encoder and decoder implementation unchanged. Analytical extrinsic information transfer (EXIT) functions are derived to determine belief propagation (BP) decoding thresholds of SC-RA-R codes on the IDMA system. The optimization expression is also given under the constraint that repeat parameters are monotonically non-decreasing with the sum rate decreasing. The numerical results show that the maximum achievable sum rates of the SC-RA-R codes can be close to the Shannon bound for arbitrary channel qualities. Besides, our proposed SC-RA-R codes have better BP thresholds and bit-error-rate (BER) performances than the conventional optimal parallel-concatenate codes (PCC) and the optimal partially repeated spatially coupled low-density parity-check (PR-SC-LDPC) codes on IDMA systems.

Tensor-based approach for blind separation of interleave-NOMA 5G system

Nowadays, wireless broadband communication has experienced tremendous growth. The requirement for various new and advanced multiple access techniques is constantly increasing. The interleave division multiple access (IDMA) technique has attracted the attention of the scientific community as an opportune code domain non-orthogonal multiple access (NOMA) for future communication standards. In this system, the detection of the signals received from different users is done by specific interleavers.In this paper, and regarding the transmission-rate loss caused by the use of spreading codes and interleavers in the IDMA systems, we are going to place ourselves in a blind separation context for IDMA signals. For this purpose, a study of a purely deterministic approach, which is the tensor decomposition, as well as a theoretical study of the Canonical Polyadic (CP) model’s existence and uniqueness issues, is also carried out. Then, a tensor modeling of the IDMA emitter and the proposal of a new form of the interleavers will be undertaken. The separation and equalization of received signals using the CP tensor decomposition compelled us to examine the methods utilized to carry out this decomposition, as well as suggest two iterative blind receivers that take use of the algebraic features of the suggested model. On the other hand, the application of an exact performance criterion will be performed, taken into account the scale and permutation indeterminacy constraints.

On the performance of modulo based Deci power interleaver in code domain NOMA system

Non-orthogonal multiple access (NOMA) is the potential multiple access considered for next generation (5G/6G) mobile communication and most of the research papers have been focused on power-domain NOMA. However, this research paper makes an effort to contribute to understand another aspect of NOMA i.e. code domain NOMA due to its better performance in large system where number of resources and users grows unboundedly. Interleave division multiple access (IDMA) is an established framework for code domain implementation of NOMA transmission and the performance of IDMA depends greatly on the interleavers as they are used to distinguish among the users. So, a unique Deci power interleaver (DPI) has been proposed and analyzed in this paper for the suggested IDMA scheme. The proposed interleaver is based on modulo operation, which reduce the bandwidth requirement and computational complexity without any performance degradation. Simulation experiments have been carried out to compare the DPI with random and other interleavers with coded and uncoded scenario in IDMA system.

Bio‐inspired hybrid algorithm to optimize pilot tone positions in polar‐code‐based orthogonal frequency‐division multiplexing–interleave division multiple access system

SummaryIn this paper, a hybrid bio‐inspired algorithm is proposed to enhance the performance of channel estimation of the orthogonal frequency‐division multiplexing–interleave division multiple access (OFDM–IDMA) system. This algorithm is a fusion of the lion algorithm and group search optimization algorithm named as SU‐LA, scrounger updated lion algorithm. It works on the optimal selection of pilot tone positions that ensure the attainment of the least value of mean square error. Polar code is used for error detection and correction along with Quadrature Amplitude Modulation (QAM) and 16 QAM techniques. Carrier frequency offset (CFO), user, and Eb/No factors are selected to analyze their impact on the BER performance in the presence of Rayleigh channel. It is observed that the proposed SU‐LA‐based system with the QAM technique achieves 91.23% enhancement in BER at zero CFO as compared to harmony search‐based system for Eb/No of 12 dB. Further, in the presence of 0.1 CFO, the proposed system retains BER performance. The experimentation is also carried with 16 QAM over various CFOs and the number of users. The BER performance of the proposed system is also superior to the particle swarm optimization (PSO) and genetic algorithm (GA)‐based system. The effect of peak‐to‐average power ratio (PAPR) and symbol time offsets is not considered.

Low-Complexity Address Generation for Multiuser Detectors in IDMA Systems

This paper presents a low-complexity address generation unit (AGU) for multiuser detectors in interleave division multiple access (IDMA) systems. To this end, for the first time, all possible options for designing AGUs are first analyzed in detail. Subsequently, a complexity reduction technique is applied to each of those architectures. More specifically, some components in AGUs are relocated to make them shareable and removable without affecting the functionality. The complete transparency of such renovation makes it applicable to any existing multiuser detector without tailoring the interfacing components therein. Measuring the hardware complexity, all the resulting AGUs are compared with each other, and a new architecture simpler than the state-of-the-art one is developed. Implementation results in a 65 nm CMOS process, demonstrating that the proposed AGU can alleviate the equivalent gate count and the power consumption of the prior process by 13% and 31%, respectively.

An efficient and robust multi-user detection in IDMA system

Multi-user detection (MUD) is a popular method in wireless communication systems to enhance efficiency by together processing the signals received from all users. The complexity of MUD has been a great problem in practical scenario. Wiener (optimum) filter yields best estimate of the input signal from noisy observations. In this paper, using Wiener filtering, a less complex and robust MUD strategy is introduced in a new multiple access scheme called interleave-division multiple-access (IDMA) which supports MUD in a simple way. The proposed IDMA system helps in achieving lower bit error rate and manages multiple number of users easily when compared to other multiple access schemes.

Efficient power allocation method for non orthogonal multiple access 5G systems

One of the hot research topics for the upcoming 5G (fifth-generation) wireless communication networks is the non orthogonal multiple access (NOMA) systems, where it have attracted both industrial and academic fields to improve the existing spectral efficiency. In fact, the multiuser detection process for NOMA systems is largely affected by the power distribution of the received signals. In this paper, a new method has been proposed to control the transmit power among active users in one of the promising NOMA systems; the interleave division multiple access (IDMA) which has been adopted here for consideration. Unlike conventional methods, where tedious mathematical computations are required; a simple and direct method has been derived. The proposed method has been applied to IDMA system with different FEC codes. The obtained results show that the proposed method outperforms the conventional one as compared to optimal results.

A New IDMA System Based on CSK Modulation for Multiuser Underwater Acoustic Communications

This work proposes a novel interleave-division multiple access (IDMA) system based on cyclic shift keying (CSK) modulation, named CSK-IDMA, for multiuser underwater acoustic (UWA) communications. The CSK modulation uses a circular cyclic shift of the spreading sequence to represent the information, which can be viewed as a special $M$ -ary spread spectrum modulation. Compared with conventional direct-sequence spread spectrum (DSSS) technique, CSK overcomes the spreading gain versus data rate limitations. The proposed scheme adopts the IDMA technique to reduce the cochannel interference. At the receiver, we employ passive time reversal (PTR) technique to compress the channels and improve the signal-to-interference-noise ratio (SINR) at first. In order to perfectly incorporate with the IDMA receive structure, we propose a soft CSK demodulation which can iteratively exchange extrinsic information with a soft channel decoder to form a turbo equalization. Simulation results show the proposed CSK-IDMA scheme can offer significantly improved performance. The data processing results from a lake experiment show that the proposed scheme can support 8 users and 10 users with zero error bits for 2.3 km transmission and 2.7 km transmission, respectively. The corresponding bit error rate (BER) for 16 users are $\text{8.4} \times \text{10}^{-4}$ and $\text{9.7} \times \text{10}^{-4}$ , respectively. The data rate is 62.5 bit/s per user within 4 kHz bandwidth and spreading sequences of 256 chips. To the best of our knowledge, this is the first work which can support more than 8 users for multiuser UWA communications with a high bandwidth efficiency.

MMSE Equalization Based Performance of Chaotic Interleaving Scheme for Iterative IDMA System

Background: In this paper, a chaotic interleaving scheme is proposed for further performance improvement of Interleave Division Multiple Access (IDMA). Interleavers are used to generate permuted sequence of signals to be transmitted with optimum correlation. Methods: Random interleaving (RI) was the fundamental taxonomy and used to distinguish the different users in IDMA scheme. The logistic map based chaotic interleaving scheme is suggested for IDMA. The system is also combined with Minimum Mean Square Error (MMSE) equalizer to combat the effect of Inter Symbol Interference (ISI). Results: For the sake of simplicity, no pulse shaping is assumed at the transmitter and ISI channel is considered to be a fixed 3 tap channel. Simulations are performed in MATLAB. BPSK modulation is used. Furthermore, the results show that the IDMA with proposed logistic map based chaotic interleaver outperforms the traditional random interleaving scheme in terms of BER without the need of extra memory and computational complexity. Conclusion: The obtained results show the noticeable performance improvement of CI-IDMA with MMSE equalization in deep fading situations. Chaos based interleaver also offers other advantages such as less requirement of memory and small implementation complexity.

Novel Transceiver Architecture for an Asynchronous Grant-Free IDMA System

This paper investigates a grant-free non-orthogonal multiple access (NOMA) system where massive number of users wake up and send data right away without performing a grant-based initial access procedure. Since no scheduling grant is used in this system, the base station (BS) does not know which user is transmitting on each resource. Also, due to the lack of an uplink (UL) timing control process, multiple user’s signals are asynchronously received at the BS. This causes asynchronous interference, or multiuser inter-carrier and inter-symbol interference. We propose two ideas to address these two problems. We first propose an auxiliary preamble structure to successfully detect the user activity, even in the presence of a massive number of users. We, then, propose a modification to the interleave-division multiple access (IDMA) receiver to mitigate asynchronous interference. The simulation results show that the proposed scheme significantly improves the preamble detection performance and BER performance compared to the conventional schemes. Furthermore, we show that the proposed grant-free NOMA system can achieve much better performance than the grant-based NOMA system in terms of transmission time and signaling overhead.

User Identity-Aided Pilot Access Scheme for Massive MIMO-IDMA System

A novel pilot access scheme is presented to address the intra-cell pilot collision in crowded scenarios of massive multiple-input multiple-output with interleave-division multiple-access system. This scheme, termed identity-aided pilot access (IDPA), makes each user equipment (UE) transmit its identity number (ID) to the base station (BS), which makes its interleaver available at the BS according to the one-to-one correspondence between UE's ID and its interleaver. Then, the BS obtains the uplink message of the contenders selecting the same pilot by performing the multi-user detection, where the BS only needs to estimate the sum of contenders’ channel responses instead of each UE's channel response. Furthermore, we present a method of estimating the number of active UEs, based on which an access class barring factor is derived to reduce the traffic overload. We make an analysis on the uplink throughput of this IDPA scheme and the normalized root mean square error performance for the estimation about the number of active UEs. Numerical results verify the analytical results, and show that the IDPA scheme achieves extraordinary improvements in the uplink throughput.

Power Line based Data Communication (as A Cost Effective Solution to Traditional System) and Interleave Division Multiple Access

Objectives: This paper presents a novel generalized PLC transceiver architecture (in IDMA system) and also compares the Channel frequency response based performance of PLC (in IDMA system) by varying the number of channels. Methods: The Matlab software is used for Simulation of Power Line Communication model. Multipath channel model for PLC is the model employed for considering the effect of multipath fading, frequency selective fading, physical signal propagation effects in main network and effect of impedance mismatching. The dispersive nature of channel is the base approach used for considering the effect of Intersymbol Interference. Single carrier modulation, FSK, QPSK, or other modulation methods are used as the modulation technique for narrowband applications on power lines. Power Line model Simulated Result for 4 and 15 number of channels concludes the relation between the parameters frequency, magnitude and phase. Findings: It shows the improvement in attenuation (frequency-dependent) and the frequency selective fading in Power Line Channel. The deep notches in the Frequency Response of the channel get reduced hence resulting in the attenuation improvement. By using IDMA with PLC, we can achieve a communication system which inherits the advantages of both schemes IDMA as well as power line channel. Wide variation in the Data rates can be achieved using power line communication. PLC major advantage is that its uses an existing infrastructure, so the cost of communication will get reduced. With PLC which can work over the various frequencies, communication becomes easier and maximum bandwidth can be utilized. Power Line (carrier) Communication system can be preferred choice over wireless or other Home Networking technology because of its easy installation and availability. With PLC which can work over the various frequencies, communication becomes easier and maximum bandwidth can be utilized. PLC technology promotes data communication of medium and low voltage power lines. Application: It involves the delivery of Communication signal with maximum efficiency over PLC applications. Frequency selective fading gets improved with increase in the number of channels when the PLC is used as the media of communication in IDMA system. Keywords: BER (Bit Error Rate), CDMA (Code Division Multiple Access), IDMA (Interleave Division Multiple Access), Power Grid, Smart Grid, FSK, QPSK

Application of best relay selection approach to cooperative DF IDMA systems over Rayleigh/Weibull fading channels

SummaryThis paper analyzes the performance of cooperative decode‐and‐forward (DF) interleave‐division multiple‐access (IDMA) networks with best relay selection over Rayleigh/Weibull fading environments. In the analysis, approximate outage probability (OP) and bit error probability (BEP) expressions are derived for the considered system. Further, a 2‐hop DF IDMA system is also designed to compare with cooperative one. We propose OP and BEP expression for 2‐hop DF IDMA systems. Numerical results are obtained by changing the number of relays and the value of fading parameter in the proposed expressions. Also, simulations are provided to corroborate the exactness of the derived approximate OP and BEP expressions.

Uncoded integrated interleave division multiple access systems in presence of power interleavers

Interleaving is one of the most common methods known to eradicate the effects of multiple user interference. Removal of different interferences is one of the major challenges for advanced communication system designers. Several methods of interleaving have been proposed in literature and their performances have been analyzed on different communication systems to prove their worthiness in multiple user interference removal. One of such interleavers is power interleaver, which can be employed in communication systems as a means to control burst errors and reduce the multiple user interference. In this paper, performances of two different integrated interleave division multiple access (IIDMA) techniques i.e. SCFDM-IDMA and OFDM-IDMA have been analyzed. Novelty of this work is in the sense that the entire analysis has been performed in the presence of power interleavers for the above two IIDMA techniques as the conventional IDMA fails to mitigate the problems of inter-carrier and inter-symbol interferences. Hence, the two techniques in presence of power interleavers empower the idea of quality communication without any interference for future generation communication systems.

Performance analysis of multi-carrier IDMA system for co-operative networks

In this paper, we explicate error-rate (ER) results of transmitter pre-processing (TP) aided coded multi-carrier (MC)-interleave-division-multiple-access (IDMA) scheme for co-operative downlink (DL) communication. The base station (BS) transmits the coded symbols to the relays during the first time interval. The relay decodes the symbol and then re-encodes the information so that error free communication can be achieved. Then, the coded bit stream is transmitted during the second time interval. Finally, we will obtain the user’s information at the destination using iterative decoding algorithm and achieve better ER with lower signal-to-noise ratio (SNR). We assume that each user is reinforced by at least single relay. We consider MC modulation which convert frequency-selective channel into flat-fading channel. We realize TP technique on both the BS and the intermediate relays, so that the effects of Multi-user interference and Inter-relay-interference are suppressed. To be specific, we evaluate ER performance of MC-IDMA system using TP for co-operative network with rich scattering effects based on LTE-vehicular channel environments considering both BS to relay and relay to mobile stations (MS). From our simulation results, we observe that turbo-coded co-operative aided MC-IDMA DL system with MUTP shows a substantial improvement in its ER performance with reduced amount of transmit power in terms of SNR.

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.

Cooperative IDMA systems with regenerative relays over Weibull fading channels: outage probability and error analysis

Cooperative communications has recently been introduced into multiple-access networks to combat the signal attenuation caused by fading and therefore improve the network performance. This study proposes the outage probability and error analysis of cooperative interleave-division multiple-access (IDMA) networks with regenerative relays over Weibull fading channels. The main contribution of this study relies on deriving a moment-generating function (MGF) of the total signal-to-noise ratio with the help of Pade approximation for IDMA with regenerative relaying. The derived MGF expression is employed to evaluate the outage probability of the considered system. Moreover, a closed-form asymptotic expression for the error probability of the considered system is derived and then comprehensive computer simulations have been performed to validate the accuracy of the authors’ analytical results. It is shown that results obtained by the proposed MGF and asymptotic error expressions are in good agreement with their corresponding simulation results.