Co-channel Interference Environment Research Articles

MDE and LLM Synergy for Network Experimentation: Case Analysis of Wireless System Performance in Beaulieu-Xie Fading and κ-µ Co-Channel Interference Environment with Diversity Combining.

Channel modeling is a first step towards the successful projecting of any wireless communication system. Hence, in this paper, we analyze the performance at the output of a multi-branch selection combining (SC) diversity receiver in a wireless environment that has been distracted by fading and co-channel interference (CCI), whereby the fading is modelled by newer Beaulieu-Xie (BX) distribution, and the CCI is modelled by the κ-µ distribution. The BX distribution provides the ability to include in consideration any number of line-of-sight (LOS) useful signal components and non-LOS (NLOS) useful signal components. This distribution contains characteristics of some other fading models thanks to its flexible fading parameters, which also applies to the κ-µ distribution. We derived here the expressions for the probability density function (PDF) and cumulative distribution function (CDF) for the output signal-to-co-channel interference ratio (SIR). After that, other performances are obtained, namely: outage probability (Pout), channel capacity (CC), moment-generating function (MGF), average bit error probability (ABEP), level crossing rate (LCR), and average fade duration (AFD). Numerical results are presented in several graphs versus the SIR for different values of fading and CCI parameters, as well as the number of input branches in the SC receiver. Then, the impact of parameters on all performance is checked. From our numerical results, it is possible to directly obtain the performance for all derived and displayed quantities for cases of previously known distributions of fading and CCI by inserting the appropriate parameter values. In the second part of the paper, a workflow for automated network experimentation relying on the synergy of Large Language Models (LLMs) and model-driven engineering (MDE) is presented, while the previously derived expressions are used for evaluation. Due to the aforementioned, the biggest value of the obtained results is the applicability to the cases of a large number of other distributions for fading and CCI by replacing the corresponding parameters in the formulas for the respective performances.

Secrecy Outage Analysis of Relay Aided Multiuser Scheduling for Wireless Networks in the Face of Co-Channel Interference

In this paper, we analyze the secrecy outage probability of a relay aided multiuser network which consists of a cluster head (CH), a decode-and-forward (DF) relay, and multiple users in the presence of an eavesdropper and co-channel interference (CCI). Firstly, we propose two relay aided multiuser scheduling (RMS) schemes to improve the secrecy outage performance of the network by considering the availability of channel state information (CSI) of CCI links, including the partial CSI based RMS (PCSI-RMS) scheme and the full CSI based RMS (FCSI-RMS) scheme. For comparison purposes, the relay aided round-robin scheduling (RRRS) scheme is also employed as a baseline. Then, we derive closed-form expressions for the proposed PCSI-RMS and FCSI-RMS schemes as well as the RRRS scheme in terms of their exact and asymptotic secrecy outage probabilities over Rayleigh fading channels in the face of CCI. Finally, numerical results show that the secrecy outage performance of the proposed PCSI-RMS and FCSI-RMS schemes is better than that of the RRRS scheme, where FCSI-RMS achieves the best secrecy outage performance. With an increase of the number of users, the secrecy outage performance of the PCSI-RMS and FCSI-RMS schemes is significantly improved, while that of the RRRS scheme keeps unchanged, which demonstrates the benefits of adopting the proposed PCSI-RMS and FCSI-RMS schemes against eavesdropping in CCI environments. Moreover, there is an optimal power allocation factor between the CH and the relay, which makes the network have the best secrecy outage performance.

Spatial Spectrum Estimation of Co-Channel Direct Signal in Passive Radar Based on Coprime Array

The received signal of passive radar based on mobile communication signals contains direct and multipath interference (DMI) signals from multiple co-channel base stations (CCBS). The direct signal spatial spectrum of each CCBS should be obtained first to eliminate the co-channel interference. The performance of the traditional spatial spectrum estimation algorithms based on uniform linear array (ULA) is related to the number of array elements. In the complex co-channel interference environment, the array requires an ultra-large number of array elements and the spatial spectrum estimation resolution is poor. This paper proposes a method for estimating the direct signal spatial spectrum of the CCBS by fusing coprime array and compressive sensing. Firstly, an augmented virtual array signal is constructed by using the second-order statistics of the received signals of the coprime array and then the compressive sensing algorithm is used to estimate the spatial spectrum of the direct signal of the CCBS. The proposed method can achieve higher resolution and higher-degrees-of-freedom (DOFs) performance than traditional ULA by using the same number of array elements. The effectiveness of the proposed method is verified by numerical simulation analysis and experimental data.

Superior Iterative Detection for Co-Channel Interference in Multibeam Satellite Systems

Aggressive frequency reuse alleviates the frequency-spectrum shortage in multibeam satellite systems targeting multi-Terabits-per-second throughput but creates harsh co-channel interference (CCI) environment. For forward-link, state-of-the-art receivers at user terminals assume memoryless CCI to avoid exponential increase in complexity. However, memory effects of CCI are inevitable, arising when co-channel signals combine asynchronously. First, we provide analytical characterization of CCI accounting for memory, a formulation that captures synchronization impairments. Then, low-complexity receivers, capable of realizing full frequency reuse, are developed to compensate for spatial and temporal CCI profiles, with computational complexity increasing linearly in the memory span. This is achieved by our novel soft-in soft-out, iterative divide-and-conquer (IDAC) paradigm, decomposing interference into smaller sets depending on intensity. A set is created from weak interferers which are not decoded but considered as thermal noise. The interferers which are decoded are further split into a set that subtracts strong ones and another set addressing intense interferers in optimal-Bayesian fashion. Extensive numerical studies reveal that IDAC architecture offers lossless compensation of dominant CCI with memory for beam-edge terminals, when rate coordination is guided by network information theory. Further, its performance is superior compared with approaches using iterative subtractive cancellation, commonly employed for return-link, random-access satellite applications.

Interference suppression by exploiting wireless cache in relaying networks for B5G communications

In this paper, we investigate the interference suppression by exploiting wireless cache in relaying networks for beyond fifth-generation (B5G) communications, where multiple decode-and-forward (DF) relays equipped with wireless cache assist the data transmission from the source to the destination over cochannel interference environments. To alleviate the severe effect of interference, wireless cache at the relays can be exploited to suppress the interference. Specifically, if the requested file falls into the cache at the relays, the relays can directly send the file to the destination; otherwise, the source has to send the file to the destination through the two-hop relaying. To further enhance the system performance, several relay selection criteria are proposed to select the best relay to suppress the interference, in order to assist the data transmission. The system transmission performance is evaluated by analyzing the system outage probability via the analytical and asymptotic expressions. Finally, simulation results are demonstrated to verify the proposed studies and the merits of wireless cache in suppressing the interference.

Coverage Study of ATSC 3.0 Under Strong Co-Channel Interference Environments

In addition to the traditional TDM/FDM, the advanced television systems committee (ATSC) 3.0 next generation digital TV standard has adopted state-of-the-art coding and modulation, as well as the new layered division multiplexing (LDM) technology. The ATSC 3.0 system is able to provide higher data throughput, more robust reception, better spectrum efficiency, and flexible service combinations in one RF channel with different robustness and reception conditions. Due to the adoption of a two-layer LDM, the coverage for ATSC 3.0 is very different from the legacy one-transmitter-one-coverage ATSC 1.0 system. With the new enabling technologies, the ATSC 3.0 can greatly increase the coverage/service areas, reduce the distance between co-channel assignments, and introduce local program insertion and targeted advertisement. This paper addresses the ATSC 3.0 coverage and co-channel interference issues, by using the two-layer LDM technology with different operating parameters. Simulations demonstrate that, similar to the 4G long term evolution, the ATSC 3.0 co-channel assignment could be reduced to two times the service coverage radius. This means an improvement of the spectrum efficiency by up to four times in comparison with today’s system. It is also proved through simulations that significant TV program gains can be obtained with this new system. The deployment of single frequency networks can further improve the coverage and reduce the interference.

Closed-Form Secrecy Outage Analysis of Cellular Downlink Systems in the Presence of Co-Channel Interference

This paper analyzes the secrecy outage probability of a cellular downlink system which consists of multiple users, one base station (BS), and one eavesdropper in the presence of co-channel interferers, where the BS transmits its signals to users which are distributed according to a Poisson point process with a fixed density, while the eavesdropper attempts to tap the transmission from the BS to the users. To enhance the transmission security against eavesdropping, we propose two multiuser scheduling schemes, namely, the partial channel state information (CSI) aided user scheduling (PCSI-US) scheme where only the CSIs of users are available without knowing the co-channel interferers’ CSIs and the full CSI aided user scheduling (FCSI-US) scheme which requires the CSIs of both users and interferers. For comparison purposes, the conventional round-robin scheduling scheme is also considered as a baseline. We derive closed-form expressions of the secrecy outage probability for the proposed PCSI-US and FCSI-US as well as conventional round-robin scheduling schemes in co-channel interference (CCI) environments. Numerical results show that the proposed FCSI-US and PCSI-US schemes outperform the conventional round-robin scheduling in terms of their secrecy outage probabilities, where FCSI-US achieves the best secrecy outage performance in CCI environments. It is also demonstrated that increasing the mean number of users has a marginal effect on the secrecy performance of conventional round-robin scheduling, which can significantly decrease the secrecy outage probabilities of PCSI-US and FCSI-US schemes. This further validates the secrecy effectiveness of the proposed user scheduling methods in terms of combating the CCI.

15-5 デジタル混信環境における地上デジタル放送波の受信実験 : Pre-FFTアレーとPost-FFTアレーの性能比較(第15部門 無線・光伝送2)

15-5 デジタル混信環境における地上デジタル放送波の受信実験 : Pre-FFTアレーとPost-FFTアレーの性能比較(第15部門 無線・光伝送2)

A Novel Hearability Enhancement Method for Forward-Link Multilateration Using OFDM Signal

Abstract – Together with the GPS-based approach, geo-location through mobile communication networks is a key technology for location-based service. To save the cost, most geo-location system is implemented on the existed network service, which has a cellular structure. Still, multilateration is limited in cellular structure because it is difficult for the mobile terminal to acquire distance measurements from multiple base stations. This low hearability in the receiver is caused by co-channel interference and multipath environment. Therefore, hearability enhancement is necessary for multilateration under multipath and interference environment. Former time domain based hearability methods were designed for real signals. However, orthogonal frequency division multiplexing (OFDM) signal, which its usage has been increased in digital wireless communication, is a complex signal. Thus, different hearability enhancement method is needed for OFDM signals. This paper proposes a hearability enhancement method for forward-link multilateration using OFDM signals, which employ interference cancellation and multipath mitigation. A novel interference cancellation and multipath mitigation strategy for complex-valued OFDM signals is presented that has an iterative structure. Simulation results show that the proposed multilateration method provides the user’s position with an accuracy of less than 80m through the mobile WiMAX cellular network in multipath environment. Keywords: OFDM, geo-location, Multilateration, Interference cancellation, Hearability

Virtual time-slot allocation scheme for throughput enhancement in a millimeter-wave multi-Gbps WPAN system

This paper proposes a virtual time-slot allocation (VTSA) scheme for throughput enhancement to realize a multi-Gbps time division multiple access (TDMA) wireless personal area network (WPAN) system in a realistic millimeter-wave residential multipath environment. TDMA system without time-slot-reuse mechanism conventionally allocates one TDMA time-slot to only one communication link at a time. In the proposed VTSA scheme, taking advantage on the large path loss in the millimeterwave band, a single TDMA time-slot can be reallocated and reused by multiple communication links simultaneously (hence the name virtual), thus significantly increasing system throughput. On the other hand, allowing multiple communication links to occupy the same time-slot causes the generation of co-channel interference (CCI). The cross layer VTSA scheme is therefore designed to be able to maximize the throughput improvement by adaptively scheduling the sharing of time-slots, and at the same time monitor the potential performance degradation due to CCI. As a result, it is found that the VTSA scheme is capable of improving system throughput as much as 30% in both AWGN and multipath channels (line-of-sight (LOS) and non-line-of-sight (NLOS) environment). Additionally, by coupling with higher-order modulation schemes, the system is able to achieve up to a maximum throughput of 3.8 Gbps. It is also observed that higher-order modulations although have higher maximum achievable throughput in low CCI environment, the tolerance against increasing CCI is considerably lower than that of the lower-order modulations.

Generalized eigen-combining algorithm for adaptive array systems in a co-channel interference environment

This paper presents a generalized eigen-combining algorithm for an adaptive array system that provides a diversity gain in angular spread, and a maximum signal-to-interference ratio (SIR) in the presence of strong interference. The proposed technique generates the maximum ratio of signal components distributed in the spatial channel subspace using channel bases that span the signal subspace and nullify the interference. Through extensive computer simulations, it is shown that the proposed algorithm represents a breakthrough in preventing performance saturation caused by strong co-channel interference.

Precoding Technique for Minimizing BER of MIMO-OFDM System Employing MLD under Multicell Co-channel Interference

This paper proposes a MIMO-OFDM precoder that can minimize a BER upper bound of the maximum likelihood detector (MLD) under a non-cooperative downlink multicell co-channel interference (CCI) environment. Since there is no cooperation among base stations (BSs), it is assumed that information on the interference can be estimated at a mobile station (MS) and then fed back to the desired BS for the precoder. The proposed scheme controls its precoding parameters under a transmit power constraint so as to minimize the BER upper bound, which is derived from the pairwise error probability (PEP) averaged with respect to CCI plus noise. Computer simulations demonstrate that the proposed precoder can effectively improve BER performance of cell edge users and is superior in terms of BER to the eigenmode and the minimum mean squared error (MMSE) precoded transmissions which aim to maximize the channel capacity and to minimize MSE, respectively.

BER of Adaptive Arrays in AWGN Channel

A system model is presented of adaptive arrays with trellis coded modulation (TCM) to investigate the bit-error-rate (BER) of a wireless system in a co-channel interference environment. Adaptive arrays with different geometries, uniform circular array (UCA), uniform rectangular array (URA) and UCA with center element (UCA-CE), are implemented with the least mean square (LMS) algorithm to combat interference at the same frequency. The wireless systems are investigated in well-separated signals and random direction signals scenarios with additive white Gaussian noise. The URA and UCA-CE have faster convergence and their BERs, in some cases, are slightly influenced by the number of interferers. However, although the UCA converges slowly and its performance degrades as the number of interferers increases, it generally has the best BER. The recursive least square (RLS) algorithm is also investigated. It achieves much better performance than the LMS algorithm when the training sequences are short. However, the optimum BERs attained by these two algorithms are the same.

Precise Error-Rate Analysis of Bandwidth-Efficient BPSK in Nakagami Fading and Cochannel Interference

The bit-error rate (BER) of bandlimited binary phase-shift keying in a fading and cochannel interference (CCI) environment is derived for the case of perfect coherent detection. The fading-and-interference model assumed is general and of interest for microcellular system studies. The model allows both desired signal and interfering signals to experience arbitrary amounts of fading severity. A precise BER expression is derived using a characteristic function method. Using this accurate analytical result, the impact of the interfering users' fading severity on the desired user-error rate is examined. The BERs obtained under perfect coherent detection are also valid as lower performance bounds for practical realizable receivers where ideal coherent detection is difficult to implement. The error-rate performance of a novel bandwidth-efficient pulse shape is determined for the general fading and CCI environment. Analysis and numerical results show that the new pulse can provide better BER performance than the widely used raised-cosine pulse.

A coded VSB-QPSK transmission scheme for digital satellite communications in co-channel interference environments

A coded VSB (vestigial side band)-QPSK (quadrature phase-shift keying) transmission scheme is proposed to realize interference-resistant digital satellite communication system. It uses an interference suppression filter to suppress the interference power in the receiving side. The suppressed power can be assigned to the transmission signals in advance by also using a same characteristic band limitation filter in the transmission side. Moreover, high coding-gain forward error correction (FEC) is employed to improve the degradation due to I and Q channel crosstalk by interference suppression. When a D/U (desired and undesired signal power ratio) equals 3 dB and a /spl Delta/f/f/sub N/ (/spl Delta/f: interference frequency offset, f/sub N/: one-half the Nyquist bandwidth) equals 1.05, the proposed scheme achieves an Eb/No improvement of 7.3 dB in a CCI (co-channel interference) environment.

Use of antenna nulling with broadcast meteor burst communications

An antenna nulling system exploiting the duty cycle difference between the interference and the meteor burst signal was developed for combating interference experienced in broadcast meteor burst communications. Using an existing experimental broadcast meteor burst communication system, the impact of antenna nulling on communication statistics was measured both against an intentionally generated interference signal and against the benign or co-channel interference environment experienced at the reception site. >

Decision feedback multiple-symboldifferential detection with MRC diversity

The authors propose decision feedback multiple-symbol differential detection with maximal ratio combining the diversity of π/4 shift DQPSK. Its performance is then evaluated in a combined additive-white-Gaussian-noise, Rayleigh-fading and cochannel-interference environment by computer simulation. We show that the performance of this structure is superior to conventional schemes under both the conditions of static and fast fading in the presence of cochannel interference.

Performance of microcellular mobile radio in a cochannel interference, natural, and man-made noise environment

A model is developed for performance analysis of a microcellular digital mobile radio system with Rayleigh-faded cochannel interference, Gaussian noise, and narrowband impulsive noise (Middleton's Class A noise) using the differential phase shift keying (DPSK) modulation technique. The desired signal is assumed to be Rician faded. The effects of selection diversity on the performance are investigated and compared to the nondiversity case. The performance is measured in terms of bit error probability and spectrum efficiency. The influence of reuse distance (i.e. cluster size), traffic intensity (i.e. blocking probability), impulsive index, Rician parameter, and turning point of the dual path loss law characteristic of microcells on the performance parameters is investigated in detail.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Nonredundant error correction analysis and evaluation of differentially detected pi /4-shift DQPSK systems in a combined CCI and AWGN environment

The application of the nonredundant error correction (NEC) technique to the North American and Japanese digital cellular modulation standard, pi /4-shift differential quadrature phase shift keying (DQPSK), in a combined additive white Gaussian noise (AWGN) and cochannel interference (CCI) environment is proposed, analyzed, and theoretically evaluated. The performance for NEC receivers with single, double, and triple error correction capability is theoretically analyzed and evaluated. For the CCI, the general model, which includes M statistical independent interferers also employing the pi /4-shift DQPSK modulation format, is adopted. The theoretical symbol error probability versus carrier-to-noise ratio have been obtained with M and the carrier-to-interference ratio (C/I) as parameters. The results indicate significant performance improvements over conventional differentially detected systems. Some of the results have been verified by computer simulation. The gains offered by the NEC receivers increase as C/I decreases and/or M increases. Significant error floor reductions have been observed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Spectral self-coherence restoral: a new approach to blind adaptive signal extraction using antenna arrays

A new approach to blind adaptive signal extraction using narrowband antenna arrays is presented. The approach has the capability to extract communication signals from cochannel interference environments using only known spectral correlation properties of those signals, i.e. without using knowledge of the content or direction of arrival of the transmitted signal, or the array manifold or background noise covariance of the receiver, to train the antenna array. The class of spectral self-coherence restoral (SCORE) objective functions is introduced, and algorithms for adapting antenna arrays to optimize these objective functions are developed. Using the theory of spectral correlation, it is shown by analysis and simulation that these algorithms maximize the signal-to-interference-and-noise ratio at the output of the narrowband antenna array when a single communication signal with spectral self-coherence at a known value of frequency separation, along with an arbitrary number of interferers without spectral self-coherence at that frequency separation, are impinging on the array.