Interference Cancellation Algorithm Research Articles

Experimental investigation on backscattering interference cancellation for full-duplex UOWC based on time-reversal preprocessing

A co-frequency and full-duplex (FD) underwater optical wireless communication (UOWC) system has the potential to significantly enhance spectral efficiency, reduce complexity, and further facilitate UOWC networking. However, the inevitable performance degradation due to self-interference introduced by backscattering presents a significant challenge. In this paper, we first experimentally explore the inherent characteristics of the underwater backscattering channel. Subsequently, we propose a digital-domain backscattering interference cancellation (BIC) algorithm for FD-UOWC systems, incorporating a time-reversal preprocessing. We then experimentally investigate the communication performance of an FD-UOWC system to verify the feasibility of the proposed BIC algorithm under different channel conditions. The experimental results validate the effectiveness of the proposed method, yielding substantial enhancements in bit error rate performance across diverse scenarios.

Joint interframe separation and gamma correction for asynchronous optical camera communication systems based on high-order statistics

Optical camera communication (OCC), which is enabled by large-scale light-emitting diodes (LEDs) arrays and image-sensor (IS) based cameras, has garnered significant attention from both researchers and industries. Existing OCC synchronization techniques typically rely on either super-Nyquist sampling or on computationally expensive asynchronous recovery algorithms to relax the required camera frame rate. In this paper, we propose a kurtosis-based asynchronous interference cancellation (K-AIC) algorithm, enabling the estimation for both the asynchronous interframe overlapping ratios and nonlinear Gamma distortion levels for each grayscale frame captured by camera. Through comprehensive numerical simulations, we demonstrate that the K-AIC algorithm exhibits low computational complexity, unique global optimum, high reliability and robust performance in mitigating asynchronous-induced bit errors across diverse scenarios. Short-range OCC experiment shows that the K-AIC scheme can effectively compensate for both interframe overlapping and Gamma distortions in a plesiochronous reception scenario, resulting in a Q-factor enhancement of approximately 12 dB with fluctuations of less than 1 dB. Consequently, the system achieves a net data rate of around 200 kbps.

Intelligent interference cancellation and ambient backscatter signal extraction for wireless-powered UAV IoT network

Unmanned aerial vehicles (UAVs) offer a new approach to wireless communication, leveraging their high mobility, flexibility, and visual communication capabilities. Ambient backscatter communication enables Internet of Things devices to transmit data by reflecting and modulating ambient radio waves, eliminating the need for additional wireless channels, and reducing energy consumption and cost for sensors. However, passive ambient backscatter communication has limitations such as limited range and poor communication quality. By utilizing UAVs as communication nodes, these limitations can be overcome, expanding the communication range and improving the quality of communication. Although some research has been conducted on combining UAVs and ambient backscatter, several challenges remain. One key challenge is the strong direct link interference in ambient backscatter under UAV conditions, which significantly affects communication quality. In this paper, we propose an intelligent backward and forward straight link interference cancellation algorithm based on NOMA decoding technique to enhance ambient backscatter communication quality under UAV conditions and extract more ambient energy for UAV energy supply. The paper includes theoretical derivation, algorithm description, and simulation analysis to validate the error bit rate of labeled information bits. The results demonstrate that the forward algorithm reduces the error bit rate by approximately 20% under low signal-to-noise ratio (SNR) conditions, while the backward algorithm reduces the error bit rate under high SNR conditions. The combination of the forward and backward algorithms reduces the error bit rate under both high and low SNR conditions. The proposed method contributes to improving the quality of ambient backscatter communication in UAV settings.

A novel iterative detection method based on a lattice reduction-aided algorithm for MIMO OFDM systems

The lattice reduction-aided algorithm has received broad attention from researchers since it operates as a maximum likelihood receiver with better system performance for multiple-input multiple-output orthogonal frequency division multiplexing systems and contains a full diversity. A novel iterative detection algorithm canceling parallel iterations that employ the lattice reduction-aided approach is proposed. Soft information is exchanged through the detector itself. Its iteration occurs inside the detector, which reduces much of the exchange cost between the multiple-input multiple-output orthogonal frequency division multiplexing detector and the turbo decoder. Since the parallel interference cancellation algorithm is constrained by the accuracy of the initial value of the detection, it is easy to form error propagation after several iterations. Due to the lattice reduction-aided algorithm, its performance is approximated with the maximum likelihood algorithm. Therefore, the lattice reduction-aided algorithm is introduced into the parallel interference cancellation algorithm to make its detection algorithm more accurate and overcome the effect of error propagation in the manuscript. Simulation results indicate that the proposed algorithm leads to an improvement of 0.8–2 dB when the bit error rate is set to 10–4 when compared to other algorithms.

Implementation of SIC Algorithms in the 5G DL

In this paper, we have implemented successive interference cancellation algorithms in the 5G downlink. We have calculated the maximum throughput in Frequency Division Duplex (FDD) mode in the downlink, where we have obtained a value equal to 836932 b/ms. The transmitter is of type Multiple Input Multiple Output (MIMO) with eight transmitting and receiving antennas. Each antenna among eight transmits simultaneously a data rate of 104616 b/ms that contains the binary messages of the three users. In this case, the cyclic redundancy check CRC is negligible, the Block error rate BLER is null, the MIMO category is the spatial diversity. The technology used for this is called Non-Orthogonal Multiple Access (NOMA) with a Quadrature Phase Shift Keying (QPSK) modulation. The transmission is done in a Rayleigh fading channel with the presence of obstacles. The MIMO Successive Interference Cancellation (SIC) receiver with two transmitting and receiving antennas recovers its binary message without errors for certain values of transmission power such as 50 dBm, with 0.054485% errors when the transmitted power is 20 dBm and with 0.00286763% errors for a transmitted power of 32 dBm(in the case of user 1) as well as with 0.0114705% errors when the transmitted power is 20 dBm also with 0.00286763% errors for a power of 24 dBm(in the case of user2) by applying the steps involved in SIC.

Accumulation and Elimination: A Hard Decision-Based Multi-User Interference Cancellation Method in Satellite Communication System

With the increasing number of users in the Medium-Orbit (MEO) satellite communication system, multi-access interference (MAI) has become an important factor that restricts the reliability and capacity of the system. Additionally, the low carrier-power-to-noise-density ratio (C/N0) resulting from long-distance transmission poses a significant concern. The parallel interference cancellation (PIC) algorithm, utilized within the paradigm of multi-user detection (MUD), exhibits the capability to effectively mitigate the impact of MAI within the same system. Simultaneously, coherent accumulation serves as a means to substantially enhance the correct detection probability (Pcd) at low C/N0. In this study, a signal acquisition method for multi-user spread spectrum satellite receivers is proposed, which employs interference cancellation and coherent accumulation as its core mechanisms. Furthermore, we introduce a power estimation method based on the outcomes of signal acquisition, which can be integrated into the signal reconstruction module of PIC. Finally, we implement the aforementioned algorithms in both simulation and hardware platforms. Remarkably, we observe that when the interference-to-signal ratio (ISR) caused by MAI equals 20 dB, the improved algorithm attains a maximum Pcd of 0.95 within the high signal-to-noise ratio (SNR) region, closely approaching the theoretical limit for the bit error rate (BER). The experimental results prove the effectiveness and feasibility of the acquisition algorithm. In summary, the enhanced algorithm holds vast potential for widespread implementation in multi-user spread spectrum communication systems.

Interference Cancellation Algorithms for Grant-Free Multiple Access With Massive MIMO

Interference Cancellation Algorithms for Grant-Free Multiple Access With Massive MIMO

Hybrid TH precoding with subarray connection for multi‐user mmWave MIMO systems

AbstractExisting linear algorithms based on subarray connection (SC) structures may cause noise enhancement and performance degradation. To solve this problem, this paper presents a nonlinear hybrid Tomlinson‐Harashima precoding (THP) algorithm based on SC structure, named as THP‐SC algorithm. In the proposed algorithm, the sum‐rate optimization problem can be transformed into two equivalent optimization subproblems including the transmitter optimization subproblem and the receiver optimization subproblem. These two subproblems are easy to solve. Furthermore, the analog precoding and combining matrices of the optimization subproblem are solved by a new improved successive interference cancelation (SIC) algorithm based on the singular value threshold shrinkage (SVS), which can effectively reduce the computational complexity while eliminating the interference. In the end, the digital precoding and combining matrices are obtained by TH method. Through the joint optimization of the transmitter and receiver matrices in the system, the optimal solution is obtained by alternate iteration of the matrices. In this paper, a more realistic line‐of‐sight (LOS) and non‐line‐of‐sight (NLOS) channel system is also considered. Simulations verify that the proposed algorithm can improve the spectral efficiency and energy efficiency to some extent with a comparable complexity compared to the previous works.

Successive Interference Cancellation for Orthogonal Chirp Division Multiplexing

In this paper, we propose a communication receivers’ architecture to simplify the Orthogonal Chirp Division Multiplexing (OCDM) channel equalization and to subtract multi-carrier interference followed by a successive interference cancellation (SIC) scheme in order to cancel the remaining interference. The interference introduced by underwater acoustic channel is estimated using a pre-acknowledged pilot symbol sequence, and then the interference can be optimally estimated and subtracted from the received signal. This process is repeated simultaneously for all OCDM carriers until a stationary point or a threshold is reached. Simulation results from Watermark are applied to illustrate the performance of the OCDM scheme with the presented successive interference cancellation algorithm. Results shows that the Bit Error Rate (BER) enhancement can reaches 102 in BCH1 channel. As expected, the combination of OCDM and presented SIC algorithm is shown to increase the output SNR over OCDM alone in multi-path shall water acoustic channel.

A novel adaptive noise canceling system for urea NQR spectrum analysis

Due to its practical ease of use and sufficiently high reliability, Nuclear Quadrupole Resonance (NQR) has largely been used in remote sensing-based detection of quadrupole nuclei, especially Nitrogen-containing materials. Since the received signal of free induction decay (FID) is inherently weak in this technique, the noise and the interference of the environment would dramatically impair the performance of the detecting systems. To handle such challenges, an adaptive noise canceling method was employed to improve the signal to noise and interference ratio (SNIR) in FID signals. FID signals, noise, and interference were received by the main antenna, while similar noise and interference would be received by the auxiliary antenna. The proposed system significantly reduced noise and interference through the digital noise and interference cancellation algorithm, pulse integration, averaging, and singular spectrum analysis (SSA). Urea powder was empirically analyzed outdoors, suggesting that the proposed adaptive noise and interference cancellation (ANIC) system, effectively suppressed noise and interference by 41.13 dB and amplified the FID signal by 53.36 dB. The strongest signal was detected at 2870.4 kHz.

Channel Model and Signal-Detection Algorithm for the Combined Effects of Turbulence and Link Misalignment in Underwater Optical Massive MIMO Systems

In recent years, underwater wireless optical communication (UWOC) has become a potential wireless carrier candidate for signal transmission in water mediums such as oceans. Underwater signal transmission is impaired by several challenges such as turbulence, scattering, attenuation, and misalignment. In this paper, we propose an improved-order successive interference cancellation (I-OSIC) algorithm based on partition space–time block coding (STBC) technology to solve the sub-channel correlation enhancement problem, which is caused by the combined effects of turbulence and link misalignment in the underwater optical massive multiple-input multiple-output (massive MIMO) systems. The partition STBC technology can make the encoded symbols orthogonality of space and time resist random fading under turbulence environments and fully use the communication link of the massive MIMO system. Under link misalignment conditions, the receiver detector will receive multiple beams. The proposed I-OSIC algorithm based on partition STBC can precisely track the degree of link misalignment error and reorder receiver signals based on the minimum interference criterion. It can use the channel matrix to estimate the interference magnitude of the link misalignment, and then eliminate the interference successively by demodulating the least interfered signal first. When the link misalignment error is large, the I-OSIC algorithm can provide a signal-to-noise ratio (SNR) gain of about 3 dB and provides the same error performance compared with the successive interference cancellation algorithm based on the received signal power.

Performance improvement of non-orthogonal multiple access with a 3D constellation and a 2D IFFT modulator.

In this paper, we propose a performance improvement of non-orthogonal multiple access (NOMA) with a three-dimensional (3D) constellation and a two-dimensional Inverse Fast Fourier Transform IFFT modulator (2D-IFFT) for the passive optical network (PON). Two kinds of 3D constellation mapping are designed for the generation of a three-dimensional NOMA (3D-NOMA) signal. Higher-order 3D modulation signals can be obtained by superimposing signals of different power levels by pair mapping. Successive interference cancellation (SIC) algorithm is implemented at the receiver to remove interference from different users. Compared with the traditional two-dimensional NOMA (2D-NOMA), the proposed 3D-NOMA can increase the minimum Euclidean distance (MED) of constellation points by 15.48%, which enhances the bit error rate (BER) performance of the NOMA. The peak-to-average power ratio (PAPR) of NOMA can be reduced by 2 dB. A 12.17 Gb/s 3D-NOMA transmission over 25 km single-mode fiber (SMF) is experimentally demonstrated. The results show that at the bit error rate (BER) of 3.8 × 10-3, the sensitivity gain of the high-power signals of the two proposed 3D-NOMA schemes is 0.7 dB and 1 dB compared with that of 2D-NOMA under the condition of the same rate. Low-power level signal also has 0.3 dB and 1 dB performance improvement. Compared with 3D orthogonal frequency-division multiplexing (3D-OFDM), the proposed 3D-NOMA scheme could potentially expand the number of users without obvious performance degradation. Due to its good performance, 3D-NOMA is a potential method for future optical access systems.

A data-driven deep learning network for massive MIMO detection with high-order QAM

Massive multiple-input multiple-output (MIMO) can provide higher spectral efficiency and energy efficiency compared to conventional MIMO systems. Unfortunately, as the numbers of modulation orders and antennas increase, the computational complexity of conventional symbol detection algorithms becomes unaffordable and their performance deteriorates. However, deep learning (DL) techniques can provide flexibility, nonlinearity and computational parallelism for massive MIMO detection to address these challenges. We propose an efficient data-driven detection network, i.e., accelerated multiuser interference cancellation network (AMIC-Net), for uplink massive MIMO systems. Specifically, we first introduce an extrapolation factor regarded as a learnable parameter into the multiuser interference cancellation (MIC) algorithm for iterative sequential detection (ISD) detector through extrapolation technique to enhance the convergence performance. Then we unfold the above accelerated iterative algorithm and adopt a sparsely connected approach, instead of fully connected, to obtain a relatively simple deep neural network (DNN) structure to enhance the detection performance through the data-driven DL approach. Furthermore, in order to accommodate communication scenarios with higher-order modulation, a novel activation function is proposed, which is composed of multiple softsign activation functions with additional learnable parameters to implement a multi-segment mapping of the set of constellation points with different modulations. Numerical results show that the proposed DL network can bring significant performance gain to ISD detector with various massive antenna settings and outperform the existing detectors with the same or lower computational complexity, especially in high-order QAM modulation scenarios.

Successive Light Interference Cancellation and Allocation (SLICA) Algorithm for Indoor VLC System: A Backbone for 6G Network

This paper considers a successive light interference cancellation and allocation algorithm (SLICA) practicing interference cancellation for an indoor visible light communication (VLC) system based on successive interference cancellation (SIC) technique. The interference among users is cancelled with the help of the proposed approach to reduce computational complexity. VLC has become the cornerstone of intelligence in the current scenario. The data services allocated to the users are demand based and rely on their channel conditions. The data is allocated to user by modulating light waves via illuminated LEDs. The receiving end has photodiode installed in it to recover back the data. Better performance rate is achieved with lesser interference with the proposed approach. To guarantee good (quality-of service) QoS, considerable simulations are carried out considering real- time scenario which further demonstrates the high level performance of the proposed approach over conventional approach. Based on the analysis, the SINR and interference level is demonstrated for the conventional and the proposed approach and there is a hike in the performance rate of SINR and interference level of about 20 – 30 % with the applied proposed approach. The prior motto of this study is to enhance the system throughput and improve per user average performance rate and reducing the complexity of the system. This contributes to the total efficiency of the optical indoor VLC network. Our proposed algorithm will provide a strong backbone for the 6G deployment.

Database supported successive interference cancellation scheme for intra-platoon communications

High reliability of wireless communications is a rudimentary requirement for guaranteeing safe autonomous driving. This paper discusses the performance of communications between cars within autonomous platoons, with the application of a proposed database-supported successive interference cancellation (SIC) algorithm. By assumption, it utilizes the knowledge on other existing interfering transmissions (such as pre-entered information on digital television transmissions stored in the roadside database) to remove the interfering signal at the receiver side. It is shown that this approach improves the bit error rate, and in turn — the reliability of intra-platoon transmission. The proposed solution is evaluated using link-level extensive computer simulations.

Multi-user detection for CPM spread system with turbo in VDES

The multi-user detection technology uses the spread sequence, delay, amplitude and phase information of each user to jointly detect users, which can effectively suppress multiple access interference, It is one of the key technologies in satellite communication system to make full use of uplink spectrum resources and improve system performance and capacity. Continuous phase modulation spread signal can adapt to multi-user communication due to the random variation of spread sequence, which is gradually applied to satellite communication. QPSK-CPM spread modulation scheme is adopted in the random access channel of VHF data exchange system. Aiming at the multi-user detection problem of QPSK-CPM spread system, proposing a multi-user detection algorithm based on interference elimination joint Turbo iterative detection based on the characteristics of CPM spread sequence. Compared with the traditional serial interference cancellation algorithm, the algorithm can effectively eliminate the multiple access interference problem caused by user aliasing by using the characteristics of Turbo codes. The theoretical simulation shows that the algorithm has a good detection effect on multi-user aliased signals.

Non-Orthogonal Multiple Access Technique Performance Characterization in Downlink Network

In this paper, a Non Orthogonal Multiple Access (NOMA) downlink multiuser communication system is, composed of a single base station (BS) over a wireless channel to M users equipped with single antenna is considered. The BS is located at the center of a disc denoted by D with radius R. A Gaussian-Chebyshev quadrature approximation of the cumulative density function, of unordered channel gain is applied in the case of two users independent and identically distributed, located in a disk of radius R, under two techniques OMA and NOMA, in a downlink network, to evaluate ergodic capacities of NOMA and OMA users at the bounds of the fairness region of NOMA are calculated, and from a comparison between NOMA and OMA ergodic capacities as functions of SNR ratio, one can observe that NOMA always outperforms OMA technique. In this system model, NOMA users are sorted according to their locations from the BS, so that an mth user is able to detect its own signal, after performing Successive Interference Cancellation (SIC) algorithm based on an iterative cancellation of the ith user information. In the case of the failure of mth user to detect the ith user signal, mth user meets outage probability. This outage probability under an increasing SNR ratio of two NOMA users is evaluated for different values of N parameter, disk radius R, path loss exponent and power allocation coefficients. One can note that, NOMA users achieve more outage probability with increasing values of disk radius R, and the path loss exponent tends to increase, as there are more obstructions, and NOMA users tend to achieve more outage probability.

An intelligent reflecting surfaces based iterative PhC‐MIMO system for atmospheric optical channels

AbstractOptical intelligent reflecting surface (IRS) is regarded as a forward‐looking technology to deal with line‐of‐sight limitations in optical wireless communications. This paper proposes an iterative photon counting nonorthogonal multiple access‐multiple‐input–multiple‐output (NOMA‐MIMO) system based on optical IRS. By analyzing the geometric and misalignment losses under turbulence effect in the optical IRS‐based atmospheric channel, we construct the channel fading coefficient matrix of the NOMA‐MIMO system. At the receiver, a novel iterative parallel interference cancellation algorithm based on logarithmic likelihood ratio is developed for signal detection. Through the simulation of bit error rate (BER), the reliability of the proposed system is proved. Quantitatively, the BER performance can achieve at the dBJ per bit for the scenario of MIMO system. Furthermore, the numerical results of the external information transfer process indicated that the proposed system has a rapid convergence performance.

MMW-NOMA: An Uplink NOMA Communication System Based on the Node Pairing Algorithm of Maximum and Minimum Weight in Underwater Acoustic Networks

In orthogonal multiple access (OMA) communication systems, resources are allocated to numerous users based on time, frequency, or code domains. The low bandwidth of the underwater acoustic network limits the number of nodes that can be supported by the OMA system, due to limited resources. The innovative concept of nonorthogonal multiple access (NOMA) provides a solution that offers more nodes and increases spectral efficiency. As a promising technique, it optimizes power allocation through channel characteristics and adopts serial interference cancellation algorithms to decode the signal at the receiver. This paper introduces an underwater communication system based on the node pairing algorithm of maximum and minimum weight (MMW-NOMA). First, we build the system model in a UAN scenario. Second, we present the node pairing strategy. Third, we design a node replacement mechanism. Furthermore, we offer a power allocation algorithm. Finally, we compare the performance of MMW-NOMA with randomly paired NOMA (RP-NOMA) and orthogonal frequency division multiplexing (OFDM). Numerical results show that MMW-NOMA outperforms RP-NOMA and OFDM in throughput, mean square error, and energy efficiency. However, the complexity of MMW-NOMA is slightly higher than that of RP-NOMA but significantly lower than OFDM. These results show that MMW-NOMA achieves a reasonable trade-off between performance and complexity.

Reconfigurable photonics-based millimeter wave signal aggregation for non-orthogonal multiple access.

A reconfigurable optical-to-electrical signal aggregation is proposed, for the first time, using optical signal processing and photo-mixing technology. Two optically modulated quadrature phase-shift keying (QPSK) signals are aggregated into a single 16-quadrature amplitude modulation (16-QAM) signal and, simultaneously, carried over a 28-GHz millimeter wave (MMW) carrier using an optimized heterodyne beating process through a single photodiode. To demonstrate the system reconfigurability, aggregation of two optical binary phase-shift keying signals is mapped into MMW QPSK or four-level pulse amplitude modulation signals by controlling the relative phases and amplitudes, respectively, of the input signals. In addition, the aggregation of two 16-QAM signals into a 256-QAM signal and the aggregation of three QPSK signals into a 64-QAM format are achieved. Besides, we report the effect of laser phase noise on signal aggregation performance. The de-aggregation of the aggregated MMW signals is performed electrically using a successive interference cancellation algorithm. Moreover, a proof-of-concept experiment is conducted to validate the numerical simulations. Two 1-Gbaud BPSK (1 Gbps) and QPSK (2 Gbps) optical signals are optically transmitted over a 20-km single-mode fiber as MMW over fiber signals. Then, the signals are aggregated into QPSK (2 Gbps) and 16-QAM (4 Gbps) 28-GHz MMW signals, respectively. The aggregated signal is further transmitted over a 1-m wireless channel. The performance of the proposed system is evaluated using bit error rate and error vector magnitude metrics.