Interference Cancellation Scheme Research Articles

Partial Inter-Relay Interference Cancellation in Two Path Successive Relay Network

This letter proposes a partial interference cancellation scheme to cancel the inter-relay interference (IRI) in two path successive relay (TPSR) network, where part of the IRI signals are retained at the destination node during the decoding process to improve the performance. Besides, to reduce the decoding complexity of the proposed scheme, the iteration maximal ratio combining (I-MRC) decoding algorithm is designed. Then, we analyse the diversity gain of the proposed scheme. The analysis and simulation results show that the proposed partial IRI cancellation scheme can improve the performance of the TPSR network and obtain extra diversity gain.

Multi-User Interference Cancellation Schemes for Carrier Frequency Offset Compensation in Uplink OFDMA

Each user in the uplink of an Division Multiple Access (OFDMA) system may experience a different carrier frequency offset (CFO). These uncorrected CFOs destroy the orthogonality among subcarriers, causing inter-carrier interference and multi-user interference, which degrade the system performance severely. In this paper, novel time-domain multi-user interference cancellation schemes for OFDMA uplink are proposed. They employ an architecture with multiple OFDMA-demodulators to compensate for the impacts of multi-user CFOs at the base station's side. Analytical and numerical evaluations show that the proposed schemes achieve a significant performance gain compared to the conventional receiver and a reference frequency-domain multi-user interference cancellation scheme. In a particular scenario, a maximum CFO of up to 40% of the subcarrier spacing can be tolerated, and the CFO-free performance is maintained in the OFDMA uplink.

A Review on Successive Interference Cancellation Scheme Based on Optical CDMA Network

AbstractDue to various desirable features of optical code division multiple access (OCDMA), it is believed this technique once developed and commercially available will be an integral part of optical access networks. Optical CDMA system suffers from a problem called multiple access interference (MAI) which limits the number of active users, it occurs when number of active users share the same carriers. The aim of this paper is to review successive interference cancellation (SIC) scheme based on optical CDMA system. The paper also reviews the system performance in presence of shot noise, thermal noise, and phase–induced intensity noise (PIIN). A comprehensive review on the mathematical model of SIC scheme using direct detection (DS) and spectral amplitude coding (SAC) were presented in this article.

An iterative layered interference canceller scheme for OFDM in wireless mesh security networks

The wireless mesh security networks WMSN are widely used in next generation communications due to their coverage and convenient deployment. However, when radio nodes communicate with each other simultaneously in a single network, interference may occur, leading to no recoverability of some signals. Moreover, the interference has a bad influence on the network security. To solve this problem, we introduce a novel layered interference cancellation scheme LIC. Through computer simulations, we demonstrate that the proposed system achieves good error performance and provides effective and flexible interference cancellation in WMSNs.

Choose Your Subcarriers Wisely: Active Interference Cancellation for Cognitive OFDM

A novel low complexity active interference cancellation (AIC) scheme for primary user (PU) protection is presented for application to cognitive orthogonal frequency division multiplexing (OFDM) systems, in which out-of-band radiation spilling over the PU protected band is to be minimized. A set of cancellation subcarriers are modulated by appropriate linear combinations of the remaining data subcarriers. The combination weights are fixed so that, in contrast with previous AIC approaches, they need not be recomputed on a symbol-by-symbol basis. Weight optimization can thus be carried out offline, drastically reducing the online computational cost. In addition, it is shown that by carefully selecting the location of cancellation subcarriers, significant performance improvements can be achieved. Given that finding the optimal location is an intractable combinatorial problem, an heuristic approach is proposed, based on a greedy search which provides a good tradeoff. The proposed scheme is shown to outperform current AIC solutions both in terms of performance and computational cost, obtaining significant improvements in terms of notch depth, with almost 50 dB depth in typical settings, to protect a narrowband PU inside the secondary user OFDM band. Further, experimental measurements from the implementation of the proposed scheme on both professional and off-the-shelf hardware platforms validate its effectiveness.

Effective Interference Cancellation Schemes for Device-to-Device Multicast Uplink Period Underlaying Cellular Networks

Device-to-Device (D2D) multicast will become an important technology with the increasing requirements of local communication services in future networks. To increase the overall capacity and improve resource utilization, a novel interference coordination scheme is proposed. The proposed scheme includes three steps. First, in order to mitigate the interference from D2D multicast transmission to cellular networks (CNs), a dynamic power control scheme is proposed that can determine the upper bound of D2D transmitter power based on the location of Base Station and areas of adjacent cells from the coverage area of D2D multicast group. Next, an interference limited area control scheme that reduces the interference from CNs to each D2D multicast receiver is proposed. The proposed scheme does not allow the coexistence of cellular equipments (CUEs) located in the interference limited area to reuse the same resources as the D2D multicast group. Then two resource block (RB) allocation rules are proposed to select the appropriate RBs from a candidate RB set for D2D multicast group. From the simulation results, it is confirmed that the proposed schemes improve the performance of the hybrid system compared to the conventional ways.

An Inter Symbol Interference Estimation and Cancellation Scheme for Asynchronous Distributed Differential Space-Time Code

In cooperative communication systems, as poor synchronization of different relays may induce inter symbol interference (ISI) and lead to substantial performance degradation, it is necessary to cancel ISI. In this letter, a simple ISI estimation and cancellation scheme is proposed for asynchronous distributed differential space-time code, where the destination node does not need to know the channel state information (CSI) from the source node to different relays or the CSI from the relays to the destination node. Simulation results show that the proposed scheme can cancel ISI effectively and obtain good bit error rate performance.

Optimal power allocation in DS-CDMA with adaptive SIC technique

This paper proposes an optimal power allocation in direct sequence-code division multiple access (DS-CDMA) system. The objective is to minimize total transmit power, while simultaneously meeting the certain sum channel capacity (data transmission rate) and outage probability constraints on Rayleigh fading channel. Then a weighted correlator with an adaptive successive interference cancelation (SIC) scheme is developed using neural network (NN) for an improvement in receiver performance. A closed mathematical form of joint probability of error (JPOE) is derived. This determines the number of active users' interfering effect that needs to be canceled in order to achieve a desired bit error rate (BER) value. Mathematical analysis shows that better receiver performance can be achieved through large change in weight up-gradation (w) for the strong users with a particular change in learning rate (η). Simulation results in terms of sum capacity as well as weak user's (users with poor channel gain) capacity, outage probability and BER performance duly support the effectiveness of the proposed scheme over the existing works.

Interference Cancellation with Space Diversity for Downlink MC-CDMA Systems

Modern wireless communications require an efficient spectrum usage and high channel capacity and throughput. Multiple-input and multiple-output (MIMO), Linear equalizers, multi-user detection and multicarrier code-division multiple access (MC-CDMA) are possible solutions to achieve spectral efficiency, high channel capacity, eliminate multiple access interference (MAI), eliminate Inter symbol interference (ISI) and robustness against frequency selective fading. In this paper, we combine all these techniques and investigate BER performance. We propose a low complexity receiver structure for Single-input Multiple-output (SIMO) downlink MC-CDMA systems. It employs an interference cancellation scheme to suppress the interference caused by the multipath fading channel. Also, the proposed scheme is developed for MIMO MC-CDMA system. The performance analysis of Downlink MIMO MC-CDMA systems with V-BLAST over frequency selective fading channel is investigated under various number of transmit and receive antennas. The simulation results show proposed SIMO equalization with parallel interference cancellation scheme is effective in reducing the ISI and the MAI. It improves the performance significantly and the simulation results show that MIMO MC-CDMA with V-BLAST multi-user detection provides high data rate and the BER significant improvement.

Low Complexity Intercarrier Interference Cancellation for DVB-SH Receivers

In this paper, the authors survey the system degradation due to mobility and propose a new technique to combat the effects of Doppler spread in Digital Video Broadcasting Satellite to Handheld (DVB-SH) receivers. This paper proposes a very low complexity Intercarrier Interference (ICI) cancellation scheme that performs as other existing methods, while reducing significantly the hardware resources consumption. The proposed method is based on implementing a reduced version of the leakage matrix, that models the ICI in a mobile channel. Simulation results show a gain in the carrier to noise ratio C/N up to 9 dB for a bit error rate BER = 10?5 when compared to a DVB-SH receiver with no ICI compensation. In terms of receiver speed, simulations show an improvement up to 50 % in the best case.

Modeling and Theoretical Analysis of Multistage Interference Cancellation Scheme

Modeling and Theoretical Analysis of Multistage Interference Cancellation Scheme

Blind Known Interference Cancellation

This paper investigates interference-cancellation schemes at the receiver, in which the interference data, which is valid data intended for another receiver, is known a priori. The interference channel, however, is unknown (the blind part). Such a priori knowledge is common in wireless relay networks. For example, a relay could be relaying data that was previously transmitted by a node A. If node A is now receiving a signal from another node B, the interference from the relay is actually self-information known to node A. Besides the case of self-information, the node could also have overheard or received the interference data in a prior transmission by another node. Directly removing the known interference requires accurate estimate of the interference channel, which may be difficult in many situations. In this paper, we propose a novel scheme, Blind Known-Interference Cancellation (BKIC), to cancel known interference without interference channel information. BKIC consists of two steps. The first step combines adjacent symbols to cancel the interference, exploiting the fact that the channel coefficients are almost the same between successive symbols. After such interference cancellation, however, the signal of interest is distorted. The second step recovers the signal of interest amidst the distortion. We propose two algorithms for the critical second steps. The first algorithm (BKIC-S) is based on the principle of smoothing. It is simple and has near optimal performance in the slow fading scenario. The second algorithm (BKIC-RBP) is based on the principle of real-valued belief propagation. Since there is no loop in the Tanner graph, BKIC-RBP can achieve MAP-optimal performance with fast convergence, and has near interference-free performance even in the fast fading scenario. Both BKIC schemes outperform the traditional self-interference cancellation schemes that have perfect initial channel information by a large margin, while having lower complexities.

A Novel Analog Photonic Method for Broadband Multipath Interference Cancellation

A novel analog optical technique for multipath interference cancellation of broadband signals is proposed. Multiple optical compensation branches are utilized to replicate wireless multipath channel effects. The duplicated signal is subtracted from the total received signal to recover the signal of interest while suppressing interference. The proposed architecture achieved 40 dB of cancellation over 200 MHz and 50 dB over 10 MHz. The depth and broadband nature of the cancellation demonstrates the precision of optical components and the validity of our interference cancellation scheme.

Hybrid successive continuous wave interference cancellation scheme for global positioning system receivers

The authors propose a hybrid successive continuous wave interference (CWI) cancellation scheme for GPS receivers. The proposed hybrid scheme successively detects and estimates CWIs in the time domain and nulls the estimated contaminated frequencies in the frequency domain. An adaptive second-order infinite impulse response (IIR) filter to perform the CWI detection and estimation is devised. One IIR filter is able to estimate one CWI in each iteration. Then, the detected CWI is fed back to the excision module in the frequency domain. Therefore, the hybrid scheme can successively null multiple CWIs. Moreover, the proposed architecture allows additional cascading of IIR filters to handle multiple CWIs simultaneously. Unlike the existing frequency-domain approach, CWI estimation does not rely on the statistical values in the frequency domain. Therefore the proposed hybrid scheme can be implemented using a fast Fourier transform (FFT) with fewer points. Simulation results show that the proposed hybrid scheme can operate normally with only a 256-point FFT and can perform better than the conventional N-sigma and consecutive mean excision algorithms in terms of the effective signal to interference plus noise ratio of the acquisition results.

Chip-interleaved optical code division multiple access relying on a photon-counting iterative successive interference canceller for free-space optical channels

In this paper, we design a novel Poisson photon-counting based iterative successive interference cancellation (SIC) scheme for transmission over free-space optical (FSO) channels in the presence of both multiple access interference (MAI) as well as Gamma-Gamma atmospheric turbulence fading, shot-noise and background light. Our simulation results demonstrate that the proposed scheme exhibits a strong MAI suppression capability. Importantly, an order of magnitude of BER improvements may be achieved compared to the conventional chip-level optical code-division multiple-access (OCDMA) photon-counting detector.

Improved interference cancellation for downlink DCT‐MC‐CDMA systems

The low complexity receiver structure based on discrete cosine transform for a downlink multicarrier code division multiple access (DCT-MC-CDMA) system is proposed. It employs an interference cancellation scheme with a linear equaliser to suppress the multiple access interference and interference caused by the multipath fading channel The performance of the proposed receivers is analysed and compared to the conventional downlink DFT-MC-CDMA system. Simulation results show a large performance improvement when using such an interference cancellation scheme relative to the DCT equalisation receiver, and interference cancellation for the downlink DFT-MC-CDMA system.

Mobility-Based Interference Cancellation Scheme for BS-IFDMA Systems With Optimum Code Assignment

In this paper, we propose a mobility-based multiple-access interference (MAI) cancellation scheme for block spread-interleaved frequency-division multiple-access (BS-IFDMA) systems. We optimize the assignment of spreading codes to users to maximize the performance of the cancellation scheme. The optimization is formulated as an NP-hard quadratic assignment problem, which is solved using the branch-and-bound approach. We propose an efficient search algorithm that significantly reduces the number of branches to be searched and hence speeds up the computation by a factor equal to the number of users in the system. Through analysis and simulations, we demonstrate that the proposed cancellation scheme is able to mitigate the MAI in BS-IFDMA systems due to the presence of high-mobility users. We show that without the proposed scheme, a single high-mobility user in the system will cause significant system performance degradation in terms of high bit error floor for most users in the system. In comparison, the proposed cancellation scheme with proper code assignment allows half of the users in BS-IFDMA systems to have high mobility without any significant performance degradation.

A Novel Multi User Interference Cancellation Scheme for Synchronous OCDMA Networks

In this paper we have proposed a novel multi-user interference (MUI) cancellation scheme for OCDMA systems employing prime code families. We have also discussed in detail the feasibility and implementation of this novel scheme. In addition, the performance analysis of a few prime code families are evaluated experimentally using this newly proposed MUI cancellation scheme. The results reveal that the proposed scheme is easy to implement and totally removes the MUI effect.

On the Throughput Capacity and Performance Analysis of Hybrid Wireless Networks over Fading Channels

In this paper, we investigate the theoretical per-node transmission limit of hybrid wireless networks over fading channels. We formulate a hybrid wireless network model, in which a wired network of base stations is deployed to support long-range communications between wireless nodes. Two types of transmission mode, the so called intra-cell transmission mode and the infrastructure transmission mode are considered. Aiming to effectively overcome the fading impairments, we introduce an optimal multiple access technique allowing opportunistic sources to transmit concurrently with the scheduled source. A successive interference cancelation (SIC) strategy is then applied at the receiver to limit the intra-cell interference and achieve the maximum throughput. In addition, the frequency reuse scheme is employed to minimize the inter-cell interference. We first study the scaling laws for outage throughput capacity in the slow fading scenario and provide the closed-form analytical expressions for the outage throughput capacity at the regime of high signal-to-interference-plus-noise ratio (SINR). The ergodic throughput capacity, which serves as the performance criterion for fast fading situation, is then explored. We derive the tight bounds for ergodic throughput capacity at low SINR and high SINR scenarios, respectively. Finally, we provide the detailed quality of service (QoS) performance analysis in terms of the per-node average error probability (AEP). The theoretical bounds obtained are instrumental to the future energy-limited network modeling and design.

Multi-User Interference Cancellation in Complementary Coded CDMA with Diversity Gain

This letter analyzes the performance of complementary coded code division multiple access (CC-CDMA) systems in frequency selective fading channels. Based on the evaluation of various combining algorithms for the correlation functions of M element sequences of a CC, a per-carrier parallel interference cancellation scheme based on minimum mean square error combining (MMSEC) is proposed for CC-CDMA to achieve a frequency diversity gain and multi-user interference resistance. Both analytical and simulation results verify the superiority of the proposed scheme. It is shown that combining algorithms and correlation properties of element sequences have a significant impact on the performance of CC-CDMA systems in frequency selective fading channels.