Interference Cancellation Capability Research Articles

Reliability Analysis of FD-Enabled Multi-UAV Systems With Short-Packet Communication

This paper investigates the full-duplex (FD)-enabled unmanned aerial vehicles (UAVs) communication system designed to improve spectrum utilization and coverage issues in the suburban environment. The reliability analysis of the considered system is analyzed in terms of block error rate (BLER) under ultra-reliable and low-latency communication constraints. With the assumption of the combined effect of fading and shadowing, the closed-form expressions for BLER and system goodput are obtained over Rician shadowed fading channels considering various shadowing scenarios, inter-UAV interference, and self-interference (SI) cancellation capabilities at FD node. The obtained results over Rician shadowed fading for FD-enabled UAV system are also compared with it's half-duplex counterpart over Rician fading channels. It was concluded that strong SI suppression capabilities at FD GS can results in almost 85% of performance gain at low shadowing severity conditions. The numerical results reveal important observations related to the impact of shadowing severity in the suburban areas, SI cancellation capabilities, blocklength and channel uses on the reliability performance of the FD-enabled multi-UAV system.

A Practical Spectrum Sharing Scheme for Cognitive Radio Networks: Design and Experiments

Spectrum shortage is a fundamental problem in wireless networks and this problem becomes increasingly acute with the rapid proliferation of wireless devices. To address this problem, spectrum sharing in the context of cognitive radio networks (CRNs) has been considered a promising solution. In this paper, we propose a practical spectrum sharing scheme for a small CRN that comprises a pair of primary users and a pair of secondary users by leveraging the multiple-input and multiple-output (MIMO) technology. In our scheme, we assume that the secondary users take full responsibility for cross-network interference cancellation (IC). We also assume that the secondary users have no knowledge about the primary network, including its signal waveform, frame structure, and network protocol. The key components of our proposed scheme are two MIMO-based interference management techniques: blind beamforming (BBF) and blind interference cancellation (BIC). We have built a prototype of our scheme on a wireless testbed and demonstrated that the prototyped secondary network can coexist with commercial Wi-Fi devices (primary users). Experimental results further show that, for a secondary device with two or three antennas, BBF and BIC achieve an average of 25dB and 33dB IC capability in an office environment, respectively.

A hybrid MAC for non-orthogonal multiple access Unmanned Aerial Vehicles networks

This paper considers a swarm of Unmanned Aerial Vehicles (UAVs) managed by a ground station. These UAVs may experience highly varying channel gains and collisions when they transmit to the ground station. To this end, we introduce a novel Learning Medium Access Control (L-MAC) for multi-rate UAVs and equip the ground station with Successive Interference Cancellation (SIC) capability. The ground station uses L-MAC to learn a Time Division Multiple Access (TDMA) schedule/frame length that yields the highest throughput. UAVs, on the other hand, use L-MAC to learn the best transmission slot and data rate for a given frame length. Our extensive simulation results show that L-MAC achieves up to five times higher throughput as compared to the well-known Aloha protocol. Specifically, L-MAC achieves a throughput of 500 kbps as compared to 100 kbps for Aloha. In comparison, Aloha with SIC achieves a throughput of 300 kbps for the same network scenario. On the other hand, the throughput of L-MAC is as most half that of the case when the ground station has perfect channel state information. Our results also show that the frame length is always set to around 60–75% of the total number of UAVs.

Outage Performance of Multi-Antenna Mobile UAV-Assisted NOMA Relay Systems Over Nakagami-m Fading Channels

This paper investigates the outage performance of the communications between two pairs of source−destination in a non-orthogonal multiple access (NOMA) system where a multi-antenna mobile unmanned aerial vehicle (UAV) acts as the relay for these communications. We first characterize the signal-to-interference-plus-noise ratio (SINRs) of uplink and downlink, taking into account the influences of power allocation, successive interference cancellation (SIC) capability, and the number of antennas at the UAV. We then derive the exact closed-form expression of the outage probability (OP) of each source−destination communication pair. Monte-Carlo simulations are conducted to verify the correctness of our mathematical analysis. Numerical results show that the outage performance of the proposed NOMA-UAV relay system greatly depends on the line-of-sight (LoS) probability, the SIC capability, the velocity, and the number of antennas of the UAV. The best outage performance is obtained when the UAV is in the middle of the source and destination or when suitable power allocation coefficients are assigned to the uplink and downlink.

Energy-Constrained Uncoordinated Multiple Access for Next-Generation Networks

This article analyzes the performance of a distributed joint power/packet diversity random access scheme in the presence of energy requirements. In particular, the two main approaches separately developed in the recent years for exploiting the Interference Cancellation (IC) capabilities of modern receivers, that is, Non-Orthogonal Multiple Access (NOMA) and Packet Repetition (PR), are firstly compared and then combined by imposing a constraint on the total available power. This constraint, which is alternative to the commonly adopted one based on the maximum power allowed for a transmission, results much more practical, since it enables to better infer the energy efficiency of a scheme, be it a pure NOMA, PR or combined NOMA/PR one. Both theoretical derivations and numerical simulations are carried out to evaluate the success probability and the throughput of the considered schemes by accounting for evolved reception criteria and different fading scenarios. Furthermore, the influence of several nonidealities, including imperfect IC and packet overhead, is discussed together with the impact of the system parameters, such as the user rate, the average signal to noise ratio, and the number of slots that compose a random access frame.

Heterogeneous FD-mm-Wave Cellular Networks With Cell Center/Edge Users

In this paper, we assess the effect of full-duplex (FD) radio in the context of millimeter-wave (mm-Wave) communications. Particularly, we propose an analytical framework, based on stochastic geometry, to evaluate the performance of heterogeneous FD-mm-Wave cellular networks for two user location-based classifications, namely cell-center users (CCUs) and cell-edge users (CEUs). Moreover, we evaluate the performance of the considered networks with successive interference cancellation (SIC) capabilities. Based on the proposed framework, analytical expressions for the coverage and sum-rate performance are derived. We investigate the impact of FD-mm-Wave communications on the network performance of CCUs/CEUs and quantify the associated performance gains under different network parameter settings. Our results demonstrate the beneficial combination of FD radio with heterogeneous mm-Wave cellular networks, since it increases the spectral efficiency but also alleviates the effects of the multi-user interference. Furthermore, we present the tradeoff between the coverage and sum-rate performance of heterogeneous FD-mm-Wave cellular networks for the considered user classifications. The results show that half-duplex mode is beneficial for the CEUs to achieve better network performance, as opposed to the CCUs for which FD mode is more efficient. Finally, we show the effectiveness of SIC on the network performance, with significant performance gains for the CEUs.

Full-Duplex Cloud Radio Access Network: Stochastic Design and Analysis

Full-duplex (FD) wireless has emerged as a disruptive communications paradigm for enhancing the achievable spectral efficiency (SE), thanks to the recent major breakthroughs in self-interference mitigation. The FD versus half-duplex (HD) SE gain in cellular networks is, however, largely limited by the mutual-interference (MI) between the downlink (DL) and the uplink (UL). A potential remedy for tackling the MI bottleneck is through cooperative communications. This paper provides a stochastic design and analysis of FD enabled cloud radio access network (C-RAN) under the Poisson point process-based abstraction model of multi-antenna radio units and user equipments. We consider different network- and user-centric approaches toward the formation of finite clusters in the C-RAN. Contrary to most existing studies, we explicitly take into consideration non-isotropic fading channel conditions and finite-capacity fronthaul links. Accordingly, upper-bound expressions for the C-RAN DL and UL SEs, involving the statistics of all intended and interfering signals, are derived. The performance of the FD C-RAN is investigated through the proposed theoretical framework and Monte-Carlo simulations. According to simulations using parameters of a state-of-the-art system, significant FD versus HD C-RAN SE gains can be achieved in the presence of advanced interference cancellation capabilities and sufficient-capacity fronthaul links.

Full-Duplex Small-Cell Networks: A Physical-Layer Security Perspective

We provide a theoretical study of physical (PHY)-layer security performance in full-duplex (FD) small-cell networks. Here, the multi-antenna base stations (BSs) and user equipments (UEs) follow from the homogeneous Poisson point process-based abstraction model. To facilitate FD communications, we take into account: 1) successive interference cancellation capability at the UE side via guard regions of arbitrary radii and 2) residual self-interference at the BS side using Rician fading distribution with arbitrary statistics. We investigate the small-cell network PHY-layer security performance in the presence of a Poisson field of eavesdroppers, under the different scenarios of passive and colluding eavesdropping. Considering linear zero-forcing beamforming, we characterize the downlink and the uplink ergodic secrecy rates and derive closed-form expressions for the different useful and interference signals statistics. In certain special cases of interest, we apply non-linear curve-fitting techniques to large sets of (exact) theoretical data in order to obtain closed-form approximations for the different ergodic rates and ergodic secrecy rates under consideration. Our findings indicate that the FD functionality, in addition to enhancing the spectral efficiency, can significantly improve the PHY-layer security performance, especially with the aid of multi-antenna communications and interference cancellation schemes.

Benefits of the sparsity of mmWave outdoor spatial channels for beamforming and interference cancellation

Future outdoor communication networks are expected to make use of the mmWave bands. In this context, this paper investigates the use of sparse signal processing for efficient angular frequency estimation. Compressive sensing (CS) and correlation-based method are shown to provide accurate estimates of the Power Angular Profile (PAP). The recovered PAP is used to perform analogue beamforming. When tracking mobile users it is shown that codebook based analogue beamforming, as used in IEEE 802.11ad, results in a large signalling overhead. This adversely affects net throughput. Our CS approach requires just 2% of the resources consumed by codebook-based beamforming while providing similar SNR performance.Interference cancellation is implemented by exploiting the accurate PAP recovered by CS. This method estimates the beamforming vector required to optimise the signal to leakage and noise ratio (SLNR), allowing the coexistence of both non-interfering and interfering links. To maximise user fairness the interference cancellation capabilities of CS beamforming are combined with a Space–Time Division Multiple Access (STDMA) scheduling scheme. Considerable network throughput enhancement is demonstrated when compared to the IEEE 802.11ad codebook based beamforming approach.

Guard Zone Based Interference Management for D2D-Aided Underlaying Cellular Networks

In this paper, the critical issues associated with interference management in device-to-device (D2D) aided underlaying cellular networks are addressed. To mitigate the severe interference imposed by activating D2D links, a guard zone based D2D-activation scheme is proposed by enabling the successive interference cancellation (SIC) capabilities at the base stations (BSs). Furthermore, the exact closed-form expressions for the successful transmission probability (STP) of cellular users (CUEs) are derived by assuming a uniform distribution of both CUEs and D2D users (DUEs) within a given geographical area. After that, the approximated average throughput of CUEs is derived, relying on the method of Taylor-series expansion. In addition, the guard zone's inner radius can be optimized under the criteria of maximizing both STP and average throughput. Numerical results show that both the STP and average throughput of CUEs can be substantially improved by invoking the proposed interference management scheme.

Message-Passing Receiver for OFDM Systems Over Highly Delay-Dispersive Channels

Propagation channels with maximum excess delay exceeding the duration of the cyclic prefix (CP) in OFDM systems cause intercarrier and intersymbol interference which, unless accounted for, degrade the receiver performance. Using tools from Bayesian inference and sparse signal reconstruction, we derive an iterative algorithm that estimates an approximate representation of the channel impulse response and the noise variance, estimates and cancels the intrinsic interference and decodes the data over a block of symbols. Simulation results show that the receiver employing our algorithm outperforms receivers applying traditional interference cancellation and pilot-based schemes, and it approaches the performance of an ideal receiver with perfect channel state information and perfect interference cancellation capabilities. We highlight the relevance of our algorithm in the context of both current and future wireless communications systems. By enabling the OFDM receiver experiencing these harsh conditions to locally cancel the interference, our design circumvents the spectral efficiency loss incurred by extending the CP duration, otherwise a straightforward solution. Furthermore, it sets the premises for the development of receivers for multicarrier systems like 5G, in which the subcarrier orthogonality may be relaxed or the frame duration shortened, at the expense of cutting down the CP or even removing it altogether.

Does Network Coding Combined With Interference Cancellation Bring Any Gain to a Wireless Network?

We investigate the achievable performance gain that network coding (NC) when combined with successive interference cancellation (SIC) brings to a multihop wireless network. While SIC enables concurrent receptions from multiple transmitters, NC reduces the transmission time-slot overhead, and each of these techniques has shown independently great benefits in improving the network performance. We present a cross-layer formulation for the joint routing and scheduling problem in a wireless network with NC (with opportunistic listening) and SIC capabilities. We use the realistic signal-to-interference-plus-noise ratio (SINR) interference model. To solve this combinatorially complex nonlinear problem, we decompose it (using column generation) to two linear subproblems--namely opportunistic NC aware routing and scheduling subproblems. Our scheduling subproblem consists of activating noninterfering NC components, rather than links, which do not interfere with each other and will be used to route the traffic. We further extend our design to consider a multi-rate multihop wireless network with interference cancellation capabilities. We use numerical evaluation to present the achieved performance gain and compare our work to three other models: a base model with no NC and SIC, a model with only NC, and a model with only SIC capabilities. The numerical results show that our proposed method (both with and without variable transmission rate selection) achieves performance gains that range between moderate and significant for the various considered scenarios. Such improvements are attributed to the joint capabilities of SIC and NC in effectively controlling the interference and improving the spatial reuse.

Successive Interference Cancellation in Heterogeneous Networks

At present, operators address the explosive growth of mobile data demand by densification of the cellular network so as to reduce the transmitter-receiver distance and to achieve higher spectral efficiency. Due to such network densification and the intense proliferation of wireless devices, modern wireless networks are interference-limited, which motivates the use of interference mitigation and coordination techniques. In this work, we develop a statistical framework to evaluate the performance of multi-tier heterogeneous networks with successive interference cancellation (SIC) capabilities, accounting for the computational complexity of the cancellation scheme and relevant network related parameters such as random location of the access points (APs) and mobile users, and the characteristics of the wireless propagation channel. We explicitly model the consecutive events of canceling interferers and we derive the success probability to cancel the n-th strongest signal and to decode the signal of interest after n cancellations. When users are connected to the AP which provides the maximum average received signal power, the analysis indicates that the performance gains of SIC diminish quickly with n and the benefits are modest for realistic values of the signal-to-interference ration (SIR). We extend the statistical model to include several association policies where distinct gains of SIC are expected: (i) maximum instantaneous SIR association, (ii) minimum load association, and (iii) range expansion. Numerical results show the effectiveness of SIC for the considered association policies. This work deepens the understanding of SIC by defining the achievable gains for different association policies in multi-tier heterogeneous networks.

Robust Efficient Broadband Antenna Array Pattern Synthesis Techniques

This paper presents efficient robust broadband antenna array pattern synthesis techniques with interference cancellation capabilities. The synthesis techniques are able to place multiple broad nulls and isolated point nulls at regions of interest for interference cancellation. The new synthesis algorithms result in improved performance broadband antenna array processors. The presented synthesis techniques are computationally more efficient than the existing synthesis techniques. The paper includes numerical simulations that demonstrate the performance of the new techniques compared to existing methods.

A novel MIMO DoF model for multi-hop networks

The rapid advances of MIMO to date have mainly stayed at the physical layer or single-hop communications. Such advantages have not been fully realized at the network level, particularly for multi-hop networks. This is mainly due to the lack of a tractable and accurate model that can characterize MIMO's powerful capabilities such as spatial multiplexing (SM) and interference cancellation (IC). Recently a new DoF-based model was proposed to capture MIMO's SM and IC capabilities in multi-hop networks. This model is based on a novel node-ordering concept and only requires simple numeric computation on DoFs. In this article we review previous models for MIMO and then describe this new DoF model. This new DoF model has the potential to enable significant advances in MIMO research in the networking community.

Characterization of the Pareto Boundary for the Two-User Symmetric Gaussian InterferenceChannel

We characterize the Pareto boundary of the achievable rate region of the two-user symmetric Gaussian interference channel when transmitters control their transmission power and receivers have successive interference cancellation capability. By identifying the shape of achievable rate region according to the strength of interference channels, we find combinations of decoding and power allocation strategies achieving the Pareto boundary. We also characterize the Pareto boundary of the achievable rate region when time sharing is additionally considered.

Ergodic Capacity Comparison of Different Relay Precoding Schemes in Dual-Hop AF Systems With Co-Channel Interference

In this paper, we analyze the ergodic capacity of a dual-hop amplify-and-forward relaying system, where the relay is equipped with multiple antennas and subject to co-channel interference and the additive white Gaussian noise. Specifically, we consider three heuristic precoding schemes, where the relay first applies the: 1) maximal-ratio combining (MRC); 2) zero-forcing (ZF); and 3) minimum mean-squared error (MMSE) principle to combine the signal from the source, and then steers the transformed signal toward the destination with the maximum ratio transmission (MRT) technique. For the MRC/MRT and MMSE/MRT schemes, we present new tight analytical upper and lower bounds for the ergodic capacity, while for the ZF/MRT scheme, we derive a new exact analytical ergodic capacity expression. Moreover, we make a comparison among all three schemes, and our results reveal that, in terms of the ergodic capacity performance, the MMSE/MRT scheme always has the best performance and the ZF/MRT scheme is slightly inferior, while the MRC/MRT scheme is always the worst one. Finally, the asymptotic behavior of ergodic capacity for the three proposed schemes are characterized in large N scenario, where N is the number of relay antennas. Our results reveal that, in the large N regime, both the ZF/MRT and MMSE/MRT schemes have perfect interference cancellation capability, which is not possible with the MRC/MRT scheme.

Congestion Control, Routing and Scheduling in Wireless Networks with Interference Cancellation Capabilities

Recently, there has been strong interest in exploiting advanced physical-layer techniques to increase the capacity of multihop wireless networks. Several recent studies have emerged with a particular focus on successive interference cancelation (SIC) as an effective approach to allow multiple adjacent concurrent transmissions to coexist, enabling multipacket reception. This paper is in line with those efforts in that we attempt to understand the benefits of SIC on the throughput performance of wireless networks. We consider a cross-layer design for the joint congestion control, routing, and scheduling problem in wireless networks where nodes are endowed with SIC capabilities and under the general physical signal-to-interference-plus-noise ratio (SINR) interference model. We use duality theory to decompose the joint design problem into congestion control and routing/scheduling subproblems, which interact through congestion prices. This decomposition enables us to solve the joint cross-layer design problem in a completely distributed manner. Given that the problem of scheduling with SIC and under the SINR interference regime is NP-hard, this paper develops a decentralized approach that allows links to coordinate their transmissions and, therefore, efficiently solve the link scheduling problem. Numerically, we show that our decentralized algorithm achieves similar results to those obtained by other centralized methods (e.g., greedy maximal scheduling). We also study the performance gains SIC brings to wireless networks, and we show that flows in the network achieve up to twice their rates in most instances, in comparison with networks without interference cancelation capabilities. These gains are attributed to the capabilities of SIC to better manage the interference and promote higher spatial reuse in the network.

LMS and RLS Based Interference Cancellation in Uniform Array System

Array of antennas or sensors is widely used in many applications like communication, Rader, Sonar, Speech Processing and etc. Advantages of such system are higher degree of freedom, Adoption, Redundancy, Flexibility and etc. In real world the signals received by the array not only consist of desired signal but also consists the interferences from the sources in the surrounding environment. It is essential to remove the interfering signal and increase the Signal-to-Interference plus Noise Ratio (SINR) of the desired signal. Interference degrades the performance of the system and reduces the Detection and Estimation of the desired signal in the received signal. The goal of this Paper is to find the behaviour of LMS and RLS for different set of interfering signal, and to find the interference cancellation capability of the algorithms, and Comparison between the algorithms.

The Ergodic Rate Density of ALOHA Wireless Ad-Hoc Networks

In recent years, much attention has been paid to the analysis of random wireless ad hoc networks (WANETs) that combine the effect of the physical layer and the medium access layer. However, most works have concentrated on an outage rate model which does not accurately describe the performance of modern communication systems. In this work we consider the ergodic rate density (ERD) of a random ALOHA WANET with a homogenous Poisson point process node distribution. We present two novel lower bounds on the ERD, one for general transmission and reception strategies and the other for receivers with a spatial interference cancellation capability. The bounds are simpler than previously published results for ALOHA WANETs (that have primarily considered the outage rate density). In addition, the bounds and the bounding technique are quite general and enable the derivation of closed form expressions of the ERD for various network models. The efficiency and simplicity of the bounds are demonstrated through several applications, and insights are drawn on the behavior of the network performance as function of the path-loss factor, transmission strategies and number of antennas. Simulation results demonstrate that these simple lower bounds predict the performance of ALOHA WANETs with high accuracy.