Co-channel Interference Signals Research Articles

In-Band Full-Duplex Communications in ATSC 3.0 Single Frequency Network

Wireless in-band backhaul, a.k.a. in-band distribution links (IDL), is a spectrum-efficient and cost-effective enabling technology to the realization of Advanced Television Systems Committee (ATSC) 3.0 in the single frequency network (SFN) mode, where all the transmitter towers are synchronized to transmit the same broadcast signal in the same frequency band. Inter-tower communications network (ITCN) transforms the broadcast towers into a mesh network, thereby introducing datacasting capability to the traditional broadcast network. Both the ITCN and IDL can be operated in the most spectrum-efficient in-band full-duplex (IBFD) mode. In these situations, the ITCN/IDL receivers at the SFN towers receive the signal of interest (SOI) not only severely corrupted by the self-interference signal from its co-located transmitter, but also the co-channel interference signals from neighbouring transmitters. Moreover, the ITCN/IDL signals may be combined with the broadcast signal in the Layer Division Multiplexing (LDM) format to achieve better overall spectral efficiency. Therefore, the LDM inter-layer interference must also be mitigated. In this paper, the interferences for the ITCN/IDL signal in the SFN environment are analyzed, and a novel iterative successive signal cancellation scheme is proposed to effectively mitigate the interferences in the ITCN/IDL signal detection process in ATSC 3.0 SFNs.

Physical Layer Security in Interference Limited Land Mobile Satellite Communication Systems: Safeguarding Data Transmission

This paper focuses on evaluating the secrecy performance of a downlink land mobile satellite (LMS) system. The system faces the challenge of providing secure communication between a satellite and a legitimate user while an eavesdropper is present on the ground. Additionally, co-channel interference signals at the user's destination are considered. To address these issues, the study proposes a novel approach that utilizes Shadowed-Rician fading channels for satellite links and Nakagami-m fading for interfering terrestrial links. The main objective is to enhance the physical layer security of Interference-Limited Land Mobile Satellite Communication Systems. The approach incorporates advanced signal processing, beamforming, and artificial noise techniques to effectively manage interference. Encryption, authentication mechanisms, and intelligent power control strategies are implemented to protect transmitted data and optimize signal strength while reducing the risk of interception by potential eavesdroppers. Through comprehensive simulations, the proposed approach is thoroughly evaluated, demonstrating its effectiveness in achieving improved secrecy performance and increased resilience against security threats. The findings highlight the potential for its application in secure satellite communication systems operating in interference-constrained environments.

Anti-Interference Technology of Surface Acoustic Wave Sensor Based on K-Means Clustering Algorithm

Various types of interference signals are available in the working environment of passive wireless surface acoustic wave (SAW) sensors. Among these kinds of interference, co-channel interference is difficult to suppress. To solve this problem, a SAW sensor anti-interference technology was proposed to improve the reliability of the SAW sensor. Wavelet denoising method was used to denoise SAW resonator (SAWR) response, which can maintain the envelope characteristics of the SAW response. The entropy energy model of the SAW response signal was established, and the signal envelope was extracted from the proposed entropy energy function. The waveform envelope and the entropy energy curve were adopted as the signal characteristics to form two-dimensional points. The K-Means algorithm was used to classify the two-dimensional points to distinguish the SAW response from sinusoidal interference. Simulation results showed that the SAW response can be detected with a rate of more than 85% when the signal-to-noise ratio was greater than 4 dB, whereas the false detection rate of the sinusoidal interference signal was less than 8%. Finally, the proposed algorithm was used to detect the actual SAW response and sinusoidal interference signal. The experimental results showed that the proposed method can clearly distinguish the SAW response from the co-channel interference signal. Moreover, the proposed method can be used as the anti-interference technology to improve the stability of the SAW sensor.

Investigation on energy harvesting enabled device-to-device networks in presence of co-channel interference

Energy harvesting from ambient radio-frequency (RF) sources has been a novel approach for extending the lifetime of wireless networks. In this paper, a cooperative device-to-device (D2D) system with the aid of energy-constrained relay is considered. The relays are assumed to be able to harvest energy from information signal and co-channel interference (CCI) signals broadcasted by nearby traditional cellular users and forward the source’s signal to its desired destination (D2D user) utilizing amplify-andforward (AF) relaying protocol. Time switching protocol (TSR) and power splitting protocol (PSR) are proposed to assist energy harvesting and information processing at the relay. The proposed approaches are applied in a model with three nodes including the source (D2D user), the relay and the destination (D2D user), the system throughput is investigated in terms of the ergodic capacity and the outage capacity, where the analytical results are obtained approximately. Our numerical results verify the our derivations, and also points out the impact of CCI on system performance. Finally, this investigation provide fundamental design guidelines for selecting hardware of energy harvesting circuits that satisfies the requirements of a practical cooperative D2D system.

Interference aided cooperative SWIPT for cellular IoT networks towards 5G and beyond

To meet the anticipated challenges of the fifth-generation and beyond wireless networks, multiple candidate technologies are needed to be integrated. Motivating by this, two cooperative simultaneous wireless information and power transfer (SWIPT) protocols are proposed in this study for cellular internet of things (IoT) networks by exploiting non-orthogonal multiple access considering two different scenarios. In the proposed SWIPT protocols, both the signal of source and co-channel interference (CCI) signals are exploited as a potential source of energy. The source considered as a cellular base station communicates with its user via the assistance of energy-constrained IoT nodes acting as relays. In the first scenario, one of the assisting IoT nodes acts as a best relay to forward source information and its own information simultaneously in the same channel by exploiting non-orthogonal multiple access. The best relay is selected based on the maximum harvested energy from the signal of source and CCI signals. Second scenario is the extended version of the first scenario, where two extra energy constraint IoT transmitter–receiver pairs are assumed to be present. To evaluate the performance of the proposed protocols, delay-tolerant throughput, outage probability, delay-limited throughput, and energy efficiency are investigated over Nakagami-m fading channels. Finally, comparative results with the existing strategies are demonstrated to show the effectiveness of the proposed protocols.

Interference Management in In-Band D2D Underlaid Cellular Networks

Recently, it has been standardized by the 3rd generation partnership project (3GPP) that device-to-device (D2D) communications should use uplink resources when coexisting with conventional cellular communications. With uplink resource sharing, both cellular and D2D links cause significant co-channel interference. In this paper, we address the critical issue of interference management in the network considering a practical path loss model incorporating both line-of-sight (LoS) and non-LoS (NLoS) transmissions. To reduce the severe interference caused by active D2D links, we consider a mode selection scheme based on the maximum received signal strength (MRSS) for each user equipment (UE) to control the D2D-to-cellular interference. Furthermore, we analyze the performance in terms of the coverage probability and the area spectral efficiency (ASE) for both the cellular network and the D2D one. Analytical results are obtained and the accuracy of the proposed analytical framework is validated through Monte Carlo simulations. Through our theoretical and numerical analyses, we quantify the performance gains brought by D2D communications in cellular networks and we find an optimum mode selection threshold $\beta $ to maximize the total ASE in the network. This insight is expected to provide a design guideline for D2D mode selections.

Analysis of Self-Interference Cancellation Under Phase Noise, CFO, and IQ Imbalance in GFDM Full-Duplex Transceivers

This article investigates a full-duplex base station using a generalized frequency division multiplexing (GFDM) transceiver with the radio frequency (RF) impairments including phase noise, carrier frequency offset (CFO) and in-phase (I) and quadrature (Q) imbalance. To fully focus on the RF impairment issue, we study the simple configuration of single uplink user and single downlink user. They both are half-duplex wireless. In the uplink, we study analog and digital self-interference (SI) cancellation and propose a complementary SI suppression method. Desired signal and residual SI powers and signal-to-interference ratio (SIR) are derived in closed form. Similarly, in the downlink, we derive desired signal power, co-channel interference signal power caused by the uplink user and SIR. The RF impairments degrade the efficiency of SI cancellation and affect GFDM more negatively than full-duplex orthogonal frequency division multiplexing (OFDM). Hence, we propose full-duplex GFDM receiver filters for maximizing the SIR for both uplink and downlink transmissions. Finally, the uplink and downlink rates and the uplink-downlink rate region are derived. Significantly, the optimal-filter based GFDM outperforms full-duplex OFDM by 25 dB higher SIR and an uplink rate increase of 500%.

Physical Layer Security Enhancement for Internet of Things in the Presence of Co-Channel Interference and Multiple Eavesdroppers

This paper investigates the secrecy performance of a multiuser system that utilizes transmit antenna selection scheme at the base station and adopts threshold-based selection diversity opportunistic scheduling over legitimate nodes. The legitimate transmission suffers from the presence of noncolluding (Non-Col) and colluding (Col) multiple passive eavesdroppers. Both the legitimate and eavesdropping nodes are assumed to suffer from co-channel interference (CCI) signals from independent channels that follow Rayleigh fading. Closed-form expressions for the probability density functions and cumulative density functions of the end-to-end signal-to-interference-plus-noise ratio for both eavesdropping scenarios in the presence of CCI signals are derived. In addition, closed-form expressions for the network secrecy outage probability (SOP) for Non-Col/Col scenarios are derived. At the high signal-to-noise ratio values, closed-form expressions for the asymptotic secrecy outage probabilities are obtained. Following this obtained asymptotic analysis, an optimization problem for power allocation is formulated and solved to improve the secrecy performance of the network by minimizing the asymptotic SOP for both Col and Non-Col cases. The derived analytical expressions are then validated using both simulations and numerical results.

Interference-Aware Cooperative Anti-Jamming Distributed Channel Selection in UAV Communication Networks

This paper investigates the cooperative anti-jamming distributed channel selection problem in UAV communication networks. Considering the existence of malicious jamming and co-channel interference, we design an interference-aware cooperative anti-jamming scheme for the purpose of maximizing users’ utilities. Moreover, the channel switching cost and cooperation cost are introduced, which have a great impact on users’ utilities. Users in the UAV group sense the co-channel interference signal energy to judge whether they are influenced by co-channel interference. When the received co-channel interference signal energy is lower than the co-channel interference threshold, users conduct channel selection strategies independently. Otherwise, users cooperate with each other and take joint actions with a cooperative anti-jamming pattern under the impact of co-channel interference. Aiming at the independent anti-jamming channel selection problem under no co-channel interference, a Markov decision process framework is introduced, whereas for the cooperative anti-jamming channel selection case under the influence of co-channel mutual interference, a Markov game framework is employed. Furthermore, motivated by Q-learning with a “cooperation-decision-feedback-adjustment” idea, we design an interference-aware cooperative anti-jamming distributed channel selection algorithm (ICADCSA) to obtain the optimal anti-jamming channel strategies for users in a distributed way. In addition, a discussion on the quick decision for UAVs is conducted. Finally, simulation results show that the proposed algorithm converges to a stable solution with which the UAV group can avoid malicious jamming, as well as co-channel interference effectively and can realize a quick decision in high mobility UAV communication networks.

Analysis of D2D Communication System Over κ-μ Shadowed Fading Channel

Outage performance of a device-to-device (D2D) communication system in the presence of co-channel interference (CCI) is analyzed in this paper. Channels for the D2D and CCI signals are assumed to be κ-μ shadowed faded. Maximal ratio combining (MRC) and selection combining (SC) techniques are considered to combat fading conditions. Characteristic function (CF) expression of the D2D system in the presence of CCI is presented. Outage probability and success probability expressions are presented for the MRC and SC schemes. These outage probability and success probability expressions are functions of various CCI, path-loss and channel fading parameters. With the help of numerical results, effects of CCI on the performance of D2D communication system under different channel fading and path-loss conditions are discussed.

Interference-Aided Detection of Subthreshold Signal Using Beam Control in Polarization Diversity Reception

The present letter discusses a detectability enhancement induced by co-channel interference signals in the polarization diversity reception. The challenge is the detection of weak (subthreshold) signals, the level of which is less than the detection limit of radio receivers. To understand the theory underlying the mechanism in the presented diversity scheme, we introduce an analytic model of a dual polarized antenna array in the fading channel. In addition, the channel capacity in a binary data transmission is derived. As a result, we reveal that the interference-aided diversity reception enables us to detect signals even below the detection limit of the receiver. Moreover, the appropriate source code is needed to achieve the channel capacity because the transmission channel is asymmetric in the present reception scheme.

ATSC 3.0 Transmitter Identification Signals and Applications

In the ATSC 3.0 PHY layer standard, a transmitter identification (TxID) signal is defined in order to provide the identification of an ATSC 3.0 transmitter. TxID signal can also be used to find the co-channel and adjacent interference signals, to assist accurate location finding calculation, and to obtain the channel estimation for each transmitter, which can help local service (e.g., targeted advertisement) reception, as well as for emergency alert. For efficient use of spectrum and quality of service improvement, single frequency network (SFN) where all transmitters share a single RF channel is often implemented. The recently developed ATSC 3.0 physical layer standard has been designed to support SFN. For efficient designing, fine-tuning and operating an SFN, it is crucial to identify each transmitter, as well as to adjust transmitting power and emission time of each transmitter. This paper presents TxID for ATSC 3.0, and analyzes its detection performance under very low signal to noise ratio environments and other applications, such as location finding, and channel estimation etc. for each SFN transmitter.

A tractable approach to analyzing the energy-aware two-way relaying networks in the presence of co-channel interference

Under the impact of co-channel interference (CCI) at two source nodes and the relay, we investigate the performance of dual-hop amplify-and-forward (AF) relaying networks. In terms of energy harvesting, the power-constrained relay first scavenges energy from the received signal and CCI signals then amplifies them and forwards them to the destination. In particular, we provide closed-form expressions for outage probability and bit error ratio (BER) to easily analyse the system performance. In this paper, the impact of distinct interference power level and the number of CCIs are derived. Monte Carlo simulations are used to provide expressions related to outage probability performance. It is confirmed that energy efficiency at the relay can be enhanced due to several advantages of CCI signals which can also prolong the life expectancy of relaying systems.

Performance Analysis of Opportunistic Scheduling in Dual-Hop Multiuser Underlay Cognitive Network in the Presence of Cochannel Interference

In this paper, the performance of a dual-hop multiuser underlay cognitive network is thoroughly investigated by using a decode-and-forward (DF) protocol at the relay node and employing opportunistic scheduling at the destination users. A practical scenario where cochannel interference signals are present in the system is considered for the investigation. Considering that transmissions are performed over nonidentical Rayleigh fading channels, first, the exact signal-to-interference-plus-noise ratio (SINR) of the network is formulated. Then, the exact equivalent cumulative distribution function (cdf) and the outage probability of the system SINR are derived. An efficient tight approximation is proposed for the per-hop cdfs, and based on this, the closed-form expressions for the error probability and the ergodic capacity are derived. Furthermore, an asymptotic expression for the cdf of the instantaneous SINR is derived, and a simple and general asymptotic expression for the error probability is presented and discussed. Moreover, adaptive power allocation under the total-transmit-power constraint is studied to minimize the asymptotic average error probability. As expected, the results show that optimum power allocation improves the system performance compared with uniform power allocation. Finally, the theoretical analysis is validated by presenting various numerical results and Monte Carlo simulations.

RF-Based Energy Harvesting in Decode-and-Forward Relaying Systems: Ergodic and Outage Capacities

Radio-frequency energy harvesting constitutes an effective way to prolong the lifetime of wireless networks, wean communication devices off the battery and power line, benefit the energy saving and lower the carbon footprint of wireless communications. In this paper, an interference aided energy harvesting scheme is proposed for cooperative relaying systems, where energy-constrained relays harvest energy from the received information signal and co-channel interference signals, and then use that harvested energy to forward the correctly decoded signal to the destination. The time-switching scheme (TS), in which the receiver switches between decoding information and harvesting energy, as well as the power-splitting scheme (PS), where a portion of the received power is used for energy harvesting and the remaining power is utilized for information processing, are adopted separately. Applying the proposed energy harvesting approach to a decode-and-forward relaying system with the three-terminal model, the analytical expressions of the ergodic capacity and the outage capacity are derived, and the corresponding achievable throughputs are determined. Comparative results are provided and show that PS is superior to TS at high signal-to-noise ratio (SNR) in terms of throughput, while at low SNR, TS outperforms PS. Furthermore, considering different interference power distributions with equal aggregate interference power at the relay, the corresponding system capacity relationship, i.e., the ordering of capacities, is obtained.

Succesive Co-Channel Interference Cancellation

In this work, a successive four-stage interference cancellation model to unwrap and remove two co-channel interference signals is introduced and successfully tested. This model utilizes the second order statistics of the co-channel interference signals in an interference limited communication environment for interference cancelation. In this model, interferers and the signal of interest (SOI) are considered as multiple inputs of a multiple-input multiple-output (MIMO) system. Therefore, MIMO equalizers and blind MIMO channel estimator are employed for the corresponding tasks. At any stage of equalization in this model, a single signal is equalized and recovered. Later, a replica of the captured signal is cancelled from the received signal mixture. The remaining signal is fed to the next stage for equalization. The benefit of using this scheme is mainly improving the quality of the SOI by re-equalizing after interferers are completely removed. In the results section, 16 dB interference cancellation gain is shown where interferers are as strong as signal (SIR=0) and SNR is 30 dB. A Rayleigh fading (iid) channel is used for simulation.

Iterative reweighted least squares interference alignment approach for multicell MIMO networks

In this paper, we investigate iterative interference alignment (IA) approaches for multi-input multi-output (MIMO) multicell communication systems. We proposed an iterative reweighted least square (IRLS) approach for MIMO interference channel in single-cell scenario. The basic contribution of this paper is to extend the proposed IRLS algorithm to the more practical case of aligning co-channel interference signals in orthogonal frequency division multiple access (OFDMA) based cellular systems. The simulation results show that the proposed approach achieves a superior total system sum-rate than both the conventional Orthogonal-Minimum Leakage (OR-ML) and the Orthogonal-Maximum Signal to Interference Noise Ratio (OR-MSINR) approaches.

Adaptive Decode-and-Forward Protocol Based Cooperative Spectrum Sensing in Cognitive Radio with Interference at the Secondary Users

In this paper a novel multiple-user cooperative spectrum sensing scheme (MCSS) based on hybrid relay is proposed to achieve the spatial diversity gain in detection of the primary user (PU) in a cognitive radio (CR) network. A practically important case where co-channel interference signals are present at the network is considered for the analysis. Closed-form expressions of detection probability $$(\hbox {P}_{\mathrm{d}})$$ ( P d ) and false alarm probability $$(\alpha )$$ ( ? ) for the proposed adaptive decode-and-forward based multiple-user cooperative spectrum sensing scheme (ADF-MCSS) using energy detector over Rayleigh fading sensing channels is derived in presence of co-channel interference at the secondary user which is far away from the PU. Further we extend the concept of two user amplify-and-forward (AF) and decode-and-forward (DF) cooperative spectrum sensing schemes in multiple-user scenario (i.e. AF-MCSS and DF-MCSS) over Rayleigh fading channels when the secondary user (which is far away from PU) is affected by interference. Closed-form expressions of AF-MCSS and DF-MCSS schemes over a Rayleigh fading channels are also evaluated and compared with that of proposed ADF-MCSS in presence of interference signals at the secondary user. Further the performance analysis of AF-MCSS, DF-MCSS and ADF-MCSS schemes are compared with the existing non-cooperative spectrum sensing schemes in presence of interference at the secondary user. Our analysis is validated by numerical and simulation results for multiple-user CR network. The impact of number of cooperative relays, SNR in sensing channel, energy of interference signal, false alarm on detection probability in proposed ADF, AF and DF schemes is shown.

Narrowband PLC SIMO-Based Interference Suppression With Zero-Forcing

A single-input multiple-output-based architecture is considered to support co-channel interference (CCI) suppression processing at the receiver, where narrowband (NB) outdoor power-line communications (PLC) in the 42-89 kHz frequency band are assumed. The phantom mode (PM) in a multiconductor power transmission cable is employed for transmission, and both the PM and the differential mode (DM) are used at the receiver. Transfer functions for the PM-PM and the PM-DM modes are modeled for short-range and long-range outdoor NB PLC topologies incorporating three-path propagation using a deterministic transmission-line modeling approach. An orthogonal frequency-division multiplexing (OFDM) waveform based on the PRIME standard is used for the desired and CCI signals. Interference suppression is achieved through a zero-forcing algorithm that leverages multichannel reception and requires channel state estimates for the interference signal. Stochastic network structures are further discussed to demonstrate the average interference suppression performance. Bit-error-rate performance is estimated in the presence of interference with and without zero-forcing suppression. Results indicate that the suppression algorithm leads to a more robust interference-tolerant receiver, particularly when the relative channel responses between modes for the desired signal and the interference signal are sufficiently different.

Outage Analysis of Opportunistic Scheduling in Dual-Hop Multiuser Relay Networks in the Presence of Interference

The outage probability of a multiuser two-hop amplify-and-forward relaying system employing opportunistic scheduling is investigated. A practically important case where there are cochannel interference signals present at the network is considered for the analysis. Exact expressions and closed-form lower bounds are derived for the outage probability. Exact closed-form expressions are derived for the system outage probability when interference signals are present at the relay and at the destination separately. A closed-form lower bound is derived for the outage probability when the relay and the destination nodes are affected by interference simultaneously. The effects of channel state information feedback delay are investigated for special cases. In addition, asymptotic outage probability results are derived to obtain useful insights on the effects of interference and feedback delay. The novel expressions can be used by practicing engineers to obtain reliable and realistic performance estimates for dual-hop multiuser relay networks. The results are useful for understanding the capabilities of the feedback channel required in this system.