Co-channel Interference Cancellation Research Articles

Uplink–Downlink Cochannel Interference Cancellation in RIS-Aided Full-Duplex Networks

Uplink–Downlink Cochannel Interference Cancellation in RIS-Aided Full-Duplex Networks

A Radiation Source Positioning System Based on GEO Satellites TDOA/FDOA Measurements

Traditional passive satellite positioning systems are facing problems such as construction difficulty, high operation and maintenance costs, and positioning range limits caused by quantity of launched satellites, due to gradually scarce earth’s orbit resources. Therefore, a radiation source positioning system design scheme based on quilted GEO communication satellites is proposed to meet with those problems. The proposed positioning system is able to intelligently choose one of three modes (three-satellites TDOA mode, dual-satellites FDOA/TDOA mode, or single-satellite mode), on the basis of searching satellites database, to position unknown radiation source. The positioning result is corrected using a known reference radiation station. To improve signal detection performance, a technology of co-channel interference cancellation is proposed when unknown radiation source signal forwarded by neighboring satellite is interference badly by its communication signal. Results of emulation shows， the proposed system can effectively locate unknown radiation sources within a range of 1000 kilometers, its positioning accuracy can reach 10 kilometers.

Adaptive Antenna Array Based Non-Cooperative Co-Channel Interference Cancellation System for Ultrashort Wave Radios and Non-Ideality Analysis

Adaptive Antenna Array Based Non-Cooperative Co-Channel Interference Cancellation System for Ultrashort Wave Radios and Non-Ideality Analysis

Selective interference alignment and neutralization in coordinated multipoint using multiuser MIMO

SummaryIn wireless communication, the concept of coordinated multipoint (CoMP) transmission is more attractive, and it transpired the notion based on interference management techniques. Interference alignment (IA) and interference neutralization (IN) methods can substantially align and neutralize the interference signals. The existing work in the CoMP transmission using multiuser multi‐input and multi‐output (MU‐MIMO) had long‐held problems such as specific limit of intercell (ICI) and cochannel interference (CCI) cancelation that contain low performance in cell‐edge users. The proposed framework of the transmission signal in selective interference alignment and neutralization (SIAN) CoMP MU‐MIMO system transmits multiple data streams in multipath by using downlink coordination between base stations and receiver side. This work contributes the individual perspectives to implement the IA and IN to align and cancel the interfered signals at the receiver side. Once the perspectives mentioned above are executed, zero‐forcing (ZF) and rechanneling filter are applied on the receiver side to eliminate residual ICI. In addition, spectral efficiency significantly improves the achievable data rate and enhances the performance of cell‐edge users and reduces the CCI at the receiver side. Furthermore, the antenna configuration signals are decoded to get the exact version of interference‐free signals with null path loss of signal transmission. The effectiveness of the proposed framework analyzes and verifies the numerical evaluation of the achievable degree of freedom. Finally, the simulation demonstrates the comparison of the proposed CoMP scheme with MIMO ZF and non‐CoMP schemes, which significantly improve the performance of spectral efficiency for cell‐edge users.

Joint Impacts of Non-Ideal System Limitations on the Performance of NOMA-Based SatCom Networks

With the increasing shortage of satellite spectrum resources, non-orthogonal multiple access (NOMA) scheme is applied to satellite communication (SatCom) networks, which is regarded as one of the key technologies to improve spectrum efficiency. In this paper, we investigate the joint impact of non-ideal limitations, i.e., channel estimation errors, co-channel interference and imperfect successive interference cancellation on the performance of NOMA-based SatCom networks. To evaluate the performance improvement under practical scenarios, we obtain a closed-form expression for the outage probability (OP) in the presence of non-ideal limitations. To investigate the effect of non-ideal factors at high signal-to-noise ratios, an asymptotic analysis for the OP is also presented. Besides, an optimal power allocation scheme based on the non-ideal limitations is proposed to minimize the OP of the system. Finally, Monte Carlo simulations corroborate the correctness of the presented theoretical results.

Research on Co-Channel Interference Cancellation for Underwater Acoustic MIMO Communications

Multiple-input–multiple-output (MIMO) communication systems utilize multiple transmitters to send different pieces of information in parallel. This offers a promising way to communicate at a high data rate over bandwidth-limited underwater acoustic channels. However, underwater acoustic MIMO communication not only suffers from serious inter-symbol interference, but also critical co-channel interference (CoI), both of which degrade the communication performance. In this paper, we propose a new framework for underwater acoustic MIMO communications. The proposed framework consists of a CoI-cancellation-based channel estimation method and channel-estimation-based decision feedback equalizer (CE-DFE) with CoI cancellation functionalities for underwater acoustic MIMO communication. We introduce a new channel estimation model that projects the received signal to a specific subspace where the interference is free; therefore, the CoI is cancelled. We also introduce a CE-DFE with CoI cancellation by appending some filters from traditional CE-DFE. In addition, the traditional direct adaptive decision feedback equalization (DA-DFE) method and the proposed method are compared in terms of communication performance and computational complexity. Finally, the sea trial experiment demonstrates the effectiveness and merits of the proposed method. The proposed method achieves a more than 1 dB of output SNR over traditional DA-DFE, and is less sensitive to parameters. The proposed method provides a new approach to the design of robust underwater acoustic MODEM.

Throughput enhancement for multi-hop decode-and-forward protocol using interference cancellation with hardware imperfection

In this paper, we propose three interference cancellation based multi-hop decode-and-forward (DF) relaying protocols to enhance end-to-end system throughput under constraint of half-duplex and hardware imperfection. In the first proposed protocol, the successive interference cancellation technique is used at each hop to send N signals from a source to a destination. Hence, the first proposed protocol can increase N times of the data rate, as compared with the corresponding conventional multi-hop DF relaying protocol in which only one source data is hop-by-hop relayed to the destination via M intermediate hops. In the second one, the source and relays can at the same time transmit their signals, and the interference cancellation can be performed to remove co-channel interference components. Therefore, the data rate of the second proposed protocol can increase M/2 times, as compared with the corresponding conventional protocol. The third proposed protocol is an efficient combination of the first and second proposed ones, and hence its data rate is higher N times than the second proposed one. Moreover, the imperfect co-channel interference cancellation is also considered in the second and third protocols. For performance evaluation, we derive exact closed-form expressions of the end-to-end throughput for three proposed protocols over Nakagami-m fading channel. We also perform simulations to verify the analytical formulas, and propose an simple transmit power allocation strategy to mitigate impact of the co-channel interference and imperfect co-channel interference cancellation.

Densely Deployed Indoor Massive MIMO Experiment: From Small Cells to Spectrum Sharing to Cooperation.

Massive MIMO is a key 5G technology that achieves high spectral efficiency and capacity by significantly increasing the number of antennas per cell. Furthermore, due to precoding, massive MIMO allows co-channel interference cancellation across cells. In this work, based on experimental channel data for an indoor scenario, we analyse the impact of inter and intra-cell interference suppression in terms of spectral efficiency, capacity, user fairness and computational cost for three simulated systems under different cooperation levels. The first scenario assumes a cooperative case where eight neighbouring cells share the spectrum and infrastructure. This scenario provides the highest system performance; however, user fairness is achieved only when there is inter and intra-cell interference suppression. The second scenario considers eight cells that only share the spectrum; with full intra-cell and inter-cell interference cancellation, it is possible to achieve 32% of the optimal capacity with 20% of the computational cost in each distributed CPU, although the total computational cost per system is the highest. The third scenario considers eight independent cells operating in different frequency bands; in this case, intra-cell interference suppression leads to higher spectral efficiency compared to the cooperative case without intra-cell interference suppression.

Removal of Cochannel Interference Using Probabilistic Latent Component Analysis in Passive Bistatic Radar

This paper examines the problem of cancellation of cochannel interference (CCI) present in the same frequency channel as the signal of interest, which may bring a reduction in the performance of target detection, in passive bistatic radar. We propose a novel approach based on probabilistic latent component analysis for CCI removal. The highlight is that removing CCI is considered as reconstruction, and extraction of Doppler-shifted and time-delayed replicas of the reference signal exploited fully as training data. The results of the simulation show that the developed method is effective.

Full-duplex cooperative NOMA system under impacts of residual SI and MAI

ABSTRACT In this paper, we investigate the performance of a downlink cooperative non-orthogonal multiple access (C-NOMA) system with full-duplex decode-and-forward relaying, where a NOMA user with better channel operates as a full-duplex (FD) relay to assist other NOMA-user to forward its messages to the base station (BS). Specifically, we derive the exact expressions of the system performances in terms of outage probability and ergodic capacity for two users over the Nakagami- fading channels for the case with the direct link from the BS to users. We then analyse the impacts of residual self-interference (SI) due to imperfect self-interference cancellation in the FD mode and multiple access interference (MAI) due to imperfect co-channel interference cancellation (CCIC) on the system performance. Simulation results are provided to verify the theoretical analysis and demonstrate the advantages of the FD-C-NOMA system over the FD non-cooperative NOMA (FD-NC-NOMA) system and the half-duplex C-NOMA (HD-C-NOMA) one.

Joint Transceiver Beamforming Design for Hybrid Full-Duplex and Half-Duplex Ad-Hoc Networks

In this paper, we propose a joint transceiver beamforming design method for hybrid full-duplex (FD) and half-duplex (HD) ad-hoc networks to cancel co-channel interference, thereby to improve system spectral efficiency. To characterize network performances, we derive a general expression of transmission capacity upper bound (TC-UB) plus its two compact versions by using a stochastic geometry model. Due to the proposed beamforming design and hybrid-duplex consideration, the exact TC and conventional methods to obtain TC-UBs are not applicable. This motivates us to exploit the UB of the largest eigenvalue of desired signals, Alzer's inequality for incomplete gamma function, and dominating interference region to formulate one general TC-UB and two of its compact versions. The numerical results show that the proposed beamforming method outperforms the existing beamforming strategies in terms of exact TC, especially when the number of transmit antennas is larger than the number of receiver antennas per node pair. In addition, the derived general TC-UB can provide relatively close TC performance as the exact ones, and its two compact versions can at least give order-wise TC performance. Moreover, we find the break-even points, where FD outperforms HD with different system configurations.

Resource Allocation for Full-Duplex Systems With Imperfect Co-Channel Interference Estimation

In-band full-duplex (FD) systems have been widely studied because they can double the spectral efficiency (SE) compared with conventional half-duplex (HD) systems, theoretically. However, inherent interference caused by both self-interference (SI) and co-channel interference (CCI) makes FD systems to achieve theoretical SE hard. In this paper, we propose a CCI estimation and cancellation (CCI-EC) protocol for the FD systems to overcome performance degradation due to CCI. We suggest to use a coherence channel block for two phases: CCI channel is estimated at a downlink (DL) user through uplink (UL) pilot signals in the first phase, then a base station (BS) and a UL user transmit their data simultaneously in the second phase, in which a DL user cancels interfering signals from a UL user by utilizing the estimated CCI channel information. We analyze the achievable SE of FD systems with CCI-EC and formulate a resource allocation problem to maximize it, where resource includes pilot and data transmission time, and transmit power of a BS and a UL user. A closed-form optimal power allocation for UL pilot and data transmissions and a suboptimal power allocation for DL data transmission are provided. The simulation results show that FD systems with the proposed CCI-EC achieve near-optimal achievable SE and outperform the conventional HD systems and FD systems without CCI-EC in terms of the achievable SE. Especially, the SE gain achieved by the proposed CCI-EC protocol in FD systems is remarkable under severe interference environment.

MIMO Underwater Acoustic Communication in Shallow Water with Ice Cover

Although multiple-input multiple-output (MIMO) underwater acoustic (UWA) communication has been intensively investigated in the past years, existing works mainly focus on open-water environment. There is no work reporting MIMO acoustic communication in under-ice environment. This paper presents results from a recent MIMO acoustic communication experiment which was conducted in Bohai Gulf during winter. In this experiment, high frequency MIMO signals centered at 10 kHz were transmitted from a two-element source array to a four-element vertical receiving array at 1 km range. According to the received signal of different array elements, MIMO acoustic communication in under-ice environment suffers less effect from co-channel interference compared with that in open-water environment. In this paper, time reversal followed by a single channel decision feedback equalizer is used to process the experimental data. It is demonstrated that this simple receiver is capable of realizing robust performance using fewer hydrophones (i.e. 2) without the explicit use of complex co-channel interference cancelation algorithms, such as parallel interference cancelation or serial interference cancelation.

Capacity Enhancement of Uni-directional In-band Full-Duplex Cellular Networks through Co-channel Interference Cancellation

Capacity Enhancement of Uni-directional In-band Full-Duplex Cellular Networks through Co-channel Interference Cancellation

Joint user scheduling and channel allocation for cellular networks with full duplex base stations

Full-duplex communication (FDC) can potentially double the network capacity by allowing a device to transmit and receive simultaneously on the same frequency band. In this study, a novel resource allocation and user scheduling algorithm is proposed to maximise the network throughput for a cellular network with full-duplex (FD) base stations (BSs). The authors consider that FDC is utilised at the BS with imperfect self-interference (SI) cancellation while user devices only work in the traditional half-duplex (HD) way. In addition, to potentially cancel co-channel interference caused by other users, the opportunistic interference cancellation (OIC) technique is applied at user side. Since FDC does not always perform better than HD due to residual SI (RSI), a joint mode selection, user scheduling, and channel allocation problem is formulated to maximise the system throughput. The optimisation problem is non-convex and NP-hard, thereby a suboptimal heuristic algorithm with low computational complexity is proposed. Numerical results demonstrate that user diversity gain, FD gain, and OIC gain can be achieved by the proposed algorithm, respectively. The performance of FDC depends on the intensity of RSI and the distribution of user devices.

Co-channel interference cancellation using precoding for bi-direction multiple hops MIMO relay systems

In order to increase performance of a system while saving power consumption, multiple hop MIMO relay systems (MHMRSs) have been considered. There are many researches on the physical (PHY) layer, medium access control (MAC) layer, and MAC-PHY cross-layer to avoid a co-channel interference, such as the matched/orthogonal weight algorithm, TDMA-based smart antenna and so on. The matched/orthogonal algorithm is available for bi-directional communications; however, it requests at least three antenna elements at every relay. Consequently, it is unavailable for small wireless devices that are being demanded. In this paper, we propose an algorithm to cancel the co-channel interference of bi-directional communication MHMRSs by signal processing at receivers using precoding at transmitters. The proposal algorithm can perform with only two antenna elements while maintaining character of MIMO. The proposal algorithm is compared to the TDMA-based smart antenna algorithm which also can perform with two antenna elements, in both perfect and imperfect channel state information (CSI) schemes. Numerical calculation results indicate that a channel capacity of proposal algorithm is much higher than that of TDMA-based smart antenna algorithm in the perfect CSI scheme due to complete cancellation of co-channel interference and viability of bi-directional communications of proposal algorithm. In the imperfect CSI scheme, the channel capacity of the TDMA-based smart antenna algorithm is more robust when channel estimation errors increase; however, the channel capacity of proposal algorithm is still higher when the channel estimation error is large.

Spatially Multiplexed CDMA Multiuser Underwater Acoustic Communications

Direct-sequence (DS) code-division-multiple-access (CDMA) signaling allows multiple users to communicate simultaneously over the same bandwidth at the expense of a reduced rate. Due to severe cochannel interference (CoI) in multipath rich underwater channels, no more than 4 users have been demonstrated. Multiple-input-multiple-output (MIMO) communication also allows multiple users. Using parallel/sequential interference cancellation schemes, experimental results show similar limitations on the number of users. To extend the number of users beyond four (as required for certain applications), it is proposed to combine CDMA with MIMO, utilizing the spatial-temporal processing gain of passive-phase conjugation, and the approximate-orthogonality of the spreading codes to remove the (increased) CoI. The receiver algorithm uses simple matched filters without explicit channel-equalization and CoI cancellation. The algorithm performance is studied as a function of input-SNR, using simulated data based on experimentally measured channel impulse responses. M-sequences with 127, 255 and 511 chips are used. One finds that 255/511 chips are generally required to support 8 users, and 127/255 chips are needed to support 6 users for the channel studied. Multiuser communications are demonstrated with at-sea data for 8 users, with spreading codes of 511 chips, yielding zero bit errors. The data rate is ${\sim} 8$ bits/s/user, given 4 kHz bandwidth.

Co-channel interference cancelation at the user terminal in multibeam satellite systems

Summary We study the applicability of soft interference cancelation in the forward link of multibeam satellite systems with focus on mobile terminals. We adopt a standard currently used in commercial satellite systems as a reference. The multibeam satellite antenna radiation diagram has been generated using a physical optics reflector model while a widely adopted channel model has been used for the land mobile satellite channel. The interference pattern has been derived using a system simulator developed by the European Space Agency. Starting from the analysis of the interference pattern, we study the application of a low-complexity soft interference cancelation scheme for commercial applications. Our results show that, under realistic conditions, a two-colors frequency reuse scheme can be employed while guaranteeing service availability across the coverage and keeping the complexity at the user terminals relatively low. Copyright © 2015 John Wiley & Sons, Ltd.

Co-Channel Interference Cancellation at the User Terminal in Multibeam Satellite Systems

Co-Channel Interference Cancellation at the User Terminal in Multibeam Satellite Systems

Joint pre-processing co-channel interference cancellation for single user MIMO

In general, multiplexing and diversity gains of single user MIMO systems are restricted by min(M,N) where M, N denote the number of antenna elements at a transmitter and receiver, respectively. In order to increase the multiplexing/diversity gains and improve the performance of single user MIMO systems, a joint pre-processing co-channel interference cancellation (JPCIC) method is proposed. The JPCIC is analyzed in both the perfect and the imperfect channel state information. The dependence of channel capacity on the number of antenna elements in every subset, the number of subsets, transmit powers and channel estimation errors is discussed. As theoretical calculation result, the channel capacity increases when the multiplexing/diversity gains and/or the transmit power increase in a certain channel model whether the channel estimation error is absent or present. Compared to the conventional zero-forcing method, the channel capacity of JPCIC is considerably higher because of higher multiplexing/diversity gains, however, it is less robust and decreased more rapidly due to incomplete cancellation of interference terms when the channel estimation error increases. There is a trade-off between the channel capacity and the complexity of system, however, according to quick development in circuit techniques and miniaturization of devices, the JPCIC is expected to be an attractive technology for MIMO system.