Peak Interference Power Research Articles

Secrecy Analysis of Underlay CRN in the Presence of Correlated and Imperfect Channel

The presence of correlated and imperfect channel state information (CSI) affects the secrecy performance of cognitive radio networks (CRN). In this paper, we propose a physical layer security analysis of underlay CRN in terms of secrecy outage probability (SOP), average secrecy rate (ASR), and amount of secrecy loss (ASL). Closed forms of SOP, ASR, and ASL are provided over imperfect CSI of Rayleigh fading environment where the legitimate channel is correlated with the eavesdropper channel. The analytical results are compared with the simulation results. The work is also compared with existing work. It has been observed that the secrecy performance of the network improves as peak interference power increases, and the correlation positively impacts the secrecy performance at a medium-to-high signal-to-noise ratio (SNR); however, it degrades the data security capability of the network at low SNR. Furthermore, asymptotic analysis shows that the secrecy performance of the network improves with the growing correlation between legitimate and eavesdropper channels when the SNR of the legitimate channel is much higher than that of the eavesdropper channel, whereas secrecy performance decreases with a reducing correlation when the SNR of the legitimate channel is approximately equal to SNR of eavesdropper channel.

Network-Coded Cooperative Systems in Cognitive Radio Networks

We study the performance of a network-coded cooperative (NCC) system in an underlay cognitive radio network (CRN). The primary network (PN) consists of a single transmitter-receiver pair, and the secondary network (SN) is an NCC system with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> users, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$M$ </tex-math></inline-formula> relays, and a single destination. The relays employ decode-and-forward (DF) protocol and use network coding (NC). We study the performance of the SN under two types of power constraints: i) the combined peak interference power constraint on the PN and maximum transmit power constraint at the SN; and ii) the single peak interference power constraint on the PN. For the SN, an exact closed-form expression and an asymptotically tight end-to-end outage probability are derived, and the diversity order and coding gain are quantified. Compared to the existing literature, the proposed CRN NCC has four main distinguishable features: i) it applies to general CRN NCC network settings with an arbitrary number of users and relays; ii) it considers general relay selection mechanism and independent and non-identically distributed (i.n.i.d.) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Nakagami-m$ </tex-math></inline-formula> fading channels; iii) it assumes secondary-to-primary and primary-to-secondary interference links; and iv) it provides a generalization of previous work and includes existing results in the literature as special cases.

Secrecy Performance of Underlay Cognitive Radio Networks With Primary Interference

This work explores the physical layer security of an underlay cognitive radio network (CRN) in the presence of a powerful interferer called a primary transmitter (PT) under peak interference power constraint. Under this scenario, the secondary transmitter (Alice) transmits secret information on a single antenna with the highest signal-to-interference plus noise ratio (SINR) to a legitimate receiver (Bob), and an eavesdropper (Eve) attempts to intercept that information. Depending upon the availability of channel state information (CSI) of the eavesdropper channel, we investigate the secrecy performance of the proposed network in the Rayleigh fading environment for both passive and active eavesdropping scenarios. We obtain analytical expressions for the secrecy outage probability, intercept probability, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\epsilon$</tex-math></inline-formula> -outage secrecy capacity in a passive eavesdropping scenario. A complete investigation of the average secrecy capacity (ASC) has been made, and novel expressions for the exact and asymptotic ASC have been obtained for active eavesdropping. Bolstering these results, we also define a high SINR power offset, which quantifies the significance of main system parameters on the ASC explicitly. Further, the effect of outdated CSI of Alice to primary receiver link on the various performance metrics with the concept of interference-outage is also studied.

Fundamental Limits of Full-Duplex Spectrum Sharing Under Peak Interference Power Constraint

Cognitive radio (CR) and full-duplex (FD) have received extensive attention and research due to their high spectrum efficiency, which can effectively solve the problem of low spectrum efficiency in current communication systems. Based on CR and FD techniques, in this paper, a FD spectrum sharing CR networks is considered, in which both secondary users (SU1 and SU2) are each equipped with dual antennas, one antenna is used to transmit signals, and the other antenna is used to receive signals at the same time and frequency. Under peak interference power and peak transmit power constraints, we analysis the ergodic sum capacity and the outage probability based on the FD spectrum sharing CR networks and the conventional spectrum sharing CR networks. Furthermore, under no peak transmit power constrain and perfect self-interference cancellation (SIC), based on the FD spectrum sharing CR networks and the conventional spectrum sharing CR networks, the closed-form expressions of the theoretical performance upper bound of the ergodic sum capacity and the outage probability are derived by two lemmas and four propositions. Accurate mathematical analysis display, under the same bandwidth, the upper bound of ergodic sum capacity for the full-duplex spectrum sharing CR networks is twice as much as the traditional spectrum sharing CR networks, and the FD spectrum sharing CR networks based on SU1, also has better performance upper bound on the outage probability than the traditional spectrum sharing CR networks. Simulations results also validate that, the FD spectrum sharing CR networks obtains better communication performance than the conventional spectrum sharing CR networks, especially when the mean of self-interference channel power gain is small. Finally, we also can see that the simulation performance upper bound is completely consistent with the theoretical analysis performance upper bound, whether in the FD spectrum sharing CR networks or the conventional spectrum sharing CR networks. So also verifies the correctness of the theoretical performance upper bound derivation.

Underlay Cognitive Radio With Instantaneous Interference Constraint: A Secrecy Performance

We examine the secrecy performance of the receive antenna selection scheme in interference-limited underlay cognitive radio network (CRN) where the antenna that results in the highest signal-to-interference ratio at the secondary receiver is chosen to improve the secrecy performance of the secondary transmission. Exact and asymptotic expressions for the secrecy outage probability and intercept probability are derived for an interference-limited scenario over a general fading scenario with the assumption that the channel state information (CSI) on the secondary transmitter (ST)- primary receiver (PR) channel is perfect. However, CSI on the ST-PR channel may be outdated due to the time-varying properties or feedback latency from the PU. If the ST allocates transmission power using this outdated CSI, PR's interference constraint will not be satisfied. Therefore, we investigate the impact of outdated CSI on the secrecy performance of an interference-limited CRN when interference from the primary transmitter to SU exits under peak interference power constraint.

ПОВЫШЕНИЕ ПОМЕХОЗАЩИЩЕННОСТИ ПЕРЕДАЧ ДЕКАМЕТРОВЫХ РАДИОКАНАЛОВ В УСЛОВИЯХ НЕПРЕДНАМЕРЕННЫХ ПОМЕХ

The transmission of messages is a complex process, which is largely determined by the properties of the radio channel used. Decameter radio channels are the most difficult for organizing communication, since the ionospheric propagation of radio waves is associated with their significant attenuation, due to the significant length of the paths, as well as the presence of Rayleigh fading in the channel. However, the possibility of transmitting information over long distances without serious resource costs stimulates further research to improve the reliability of decameter radio communication. In this paper, we investigate the possibility of increasing the noise immunity of frequency-shift keying transmissions of decameter radio channels in conditions of unintentional interference due to the use of broadband signals. An analytical expression of the dependence of the probability of a bit error on the level of the ratio of the peak signal power to the peak interference power is considered; a graph of this dependence is presented. It is shown that the plot is consistent with the overall noise immunity estimate for Rayleigh fading channels using double FSK signals. The rationality of methods for obtaining the required reception quality in decameter radio channels is analyzed. It is shown that the most rational direction for increasing the noise immunity of FM-2 transmissions in decameter radio channels with Rayleigh fading in conditions of unintended interference is the use of broadband signals. In this case, for expansion, it is advisable to choose a value kf = 7, which makes it possible to increase the noise immunity by 9 dB. The conclusions are illustrated by graphs.

Performance Analysis of Cooperative Underlay Spectrum Sharing System in Co-channel Interference Limited Environment

In this paper, performance analysis of an asynchronous distributed space time block coded system with optimum combining at the cognitive radio receiver (CR-Rx) has been done in a cooperative underlay cognitive Internet of Things network under the influence of multiple co-channel primary users (PUs) interferers. The transmit power strategy being employed at the CR-Tx considers the PIP (peak interference power) at the PU-Rx and peak transmit power constraints at the CR-Tx, respectively. We have derived the probability density function of the signal-to-interference ratio (SIR) at the destination for the proposed system. The system is numerically and mathematically analyzed in terms of average post processed SIR (APPSIR), ergodic capacity ($${\text{C}}_{\text{erg}}$$), average bit error rate (ABER) and outage probability. All the numerical outcomes are in corroboration with its simulation counterpart.

Product and Ratio of Product of Fisher-Snedecor ℱ Variates and Their Applications to Performance Evaluations of Wireless Communication Systems

This article considers the product, and the ratio of the product of Fisher-Snedecor $\mathcal {F}$ random variables (RVs), which can be used in modeling fading conditions that are encountered in realistic wireless transmission. To this end, exact analytical expressions are derived for the probability density function (PDF) and cumulative distribution function (CDF) of the product of $N$ statistically independent, but not necessarily identically distributed, Fisher-Snedecor $\mathcal {F}$ RVs. Capitalizing on these, exact analytical expressions are then derived for the outage probability, average channel capacity and average bit error probability over cascaded fading channels. Moreover, some important statistical metrics such as amount of fading, channel quality estimation index, kurtosis, and skewness are also provided, since they provide useful insights on the characteristics of the encountered fading conditions. In addition, with the aid of the central limit theorem, an approximation for the PDF of $N*$ Fisher-Snedecor $\mathcal {F}$ RVs is proposed using a lognormal density, and its accuracy is quantified in terms of the resistor-average distance. Finally, novel expressions for the PDF and CDF of the $N$ -fold product ratio of Fisher-Snedecor $\mathcal {F}$ RVs are also derived. As a potential application of our new results, a spectrum sharing network is considered, for which exact analytical expressions for the outage probability, delay-limited capacity, and ergodic capacity are derived. For the cascaded fading scenario and the spectrum sharing network, numerical examples are provided to show the impact of different channel-related parameters, such as fading severity, shadowing, peak and average interference power on the system performance, which is rather useful in the design of conventional and emerging wireless communication systems. Monte-Carlo simulation results are provided to corroborate the presented mathematical analysis.

Fundamental Limits of Spectrum Sharing for NOMA-Based Cooperative Relaying Under a Peak Interference Constraint

Non-orthogonal multiple access (NOMA) and spectrum sharing (SS) are two emerging multiple access technologies for efficient spectrum utilization in future wireless communications standards. In this paper, we present the performance analysis of a NOMA-based cooperative relaying system (CRS) in an underlay spectrum sharing scenario, considering a peak interference constraint (PIC), where the peak interference inflicted by the secondary (unlicensed) network on the primary-user (licensed) receiver (PU-Rx) should be less than a predetermined threshold. In the proposed system the relay and the secondary-user receiver (SU-Rx) are equipped with multiple receive antennas and apply selection combining (SC), where the antenna with highest instantaneous signal-to-noise ratio (SNR) is selected, and maximal-ratio combining (MRC), for signal reception. Closed-form expressions are derived for the average achievable rate and outage probabilities for SS-based CRS-NOMA. These results show that for large values of peak interference power, the SS-based CRS-NOMA outperforms the CRS with conventional orthogonal multiple access (OMA) in terms of spectral efficiency. The effect of the interference channel on the system performance is also discussed, and in particular, it is shown that the interference channel between the secondary-user transmitter (SU-Tx) and the PU-Rx has a more severe effect on the average achievable rate as compared to that between the relay and the PU-Rx. A close agreement between the analytical and numerical results confirm the correctness of our rate and outage analysis.

Spectrum Sharing Paradigm Under Primary Interference and Nakagami-m Fading: Security Analysis

The spectrum sharing paradigm is a promising countermeasure to the spectrum under-utilization problem. However, it causes both primary interference (inflicted by primary transmitters upon secondary receivers) and secondary interference (inflicted by secondary transmitters upon primary receivers) and un-secures information transmission. Most works ignored the primary interference and considered the Rayleigh fading in evaluating the information security of the spectrum sharing paradigm. This paper generalizes these works with considerations of the primary interference and the Nakagami-m fading. First, the exact expression of the secrecy outage probability is proposed for the spectrum sharing paradigm under considerations of both primary/secondary interferences, the Nakagami-m fading, and the peak transmit and interference power constraints. Then, computer simulations are provided to corroborate the proposed expression. Finally, numerous simulation/theory results are generated to assess the security performance in key system parameters such as the fading severity degree, the primary interference level, the peak transmit power, the peak interference power, the security threshold.

Spectrum sharing systems capacity under η-μ fading environments

This paper presents general, closed-form, and exact expressions for cumulative distribution function, probability density function and average value for the ratio of independent η-μ random variables, with arbitrary parameters. More specifically, the outage capacity with peak interference power constraint, the delay-limited capacity, and the ergodic capacity considering constraints on the interference power are derived for non-homogeneous environments containing multipath waves clusters. Numerical curves are presented to evaluate the effects of the general fading variables in spectrum sharing systems. Besides, the results are validated by performing Monte-Carlo simulations. Notably, the provided results find important applications in cognitive radio systems considering the spectrum sharing approach and channels modeled by η-μ distribution.

Reliability-Intercept Gap Analysis of Underlay Cognitive Networks Under Artificial Noise and Primary Interference

Underlay mode of cognitive radio networks (CRNs) permits secondary users (SUs) to simultaneously operate with primary users (PUs), inducing mutual interference between them. Nevertheless, primary interference (interference from PUs to SUs) is either neglected or treated as Gaussian noise in existing works. Moreover, artificial noise, which is deliberately introduced to harm signal reception of wire-tappers, can enhance information securing capability of CRNs. This paper analyzes a gap between reliability probability (successful decoding probability of legitimate receiver) and intercept probability (successful decoding probability of wire-tappers), which accounts for artificial noise, peak transmit power constraint, interference power constraint, and fading channels, and considers primary interference as non-Gaussian noise. Towards this end, exact closed-form expressions of reliability probability and intercept probability are first derived and then validated by computer simulations. Numerous results illustrate that both probabilities are saturated at either large peak interference power or large peak transmit power, the primary interference dramatically deteriorates them while the artificial noise creates a large gap between them, demonstrating its effectiveness in securing legitimate information.

Cognitive Heterogeneous Networks With Multiple Primary Users and Unreliable Backhaul Connections

Wireless backhaul has emerged as a suitable and flexible alternative to wired backhaul; however, it is not as reliable as its wired counterpart. This paper presents, for the first time, a comprehensive model including a heterogeneous underlay cognitive network with small cells also acting as multiple secondary users, multiple primary users, and unreliable wireless backhaul. In this system, a macro-base station connects to multiple secondary transmitters via wireless backhaul links. In addition, multiple secondary transmitters send information to a secondary receiver by sharing the same spectrum with multiple primary users. A Bernoulli process is adopted to model the backhaul reliability. A selection combining protocol is used at the secondary receiver side to maximize the received signal-to-noise ratio. We investigate the impact of the number of secondary transmitters, the number of primary users, as well as the backhaul reliability on the system performance in Rayleigh fading channels. Two key constraints are considered on the system performance: 1) maximum transmit power at the secondary transmitters and 2) peak interference power at the primary users caused by secondary transmitters. Closed-form expressions for outage probability, ergodic capacity, and symbol error rate and the asymptotic expressions for outage probability and symbol error rate are derived. Moreover, closed-form expressions are also applicable to non-cooperative scenarios.

Delay analysis for cognitive radio networks

In this article, we derive the waiting time and total delay of packets for cooperative cognitive radio networks. In the primary network, there are primary transmitter (PT) and receiver (PR). In the secondary network, there are a source, M relays and a destination. Our results are valid for any number of relays and different relaying protocols: opportunistic amplify and forward (AF), partial AF, reactive AF and reactive DF. The analysis is carried out for nodes with fixed and adaptive transmit power. For fixed transmit power (FTP), we cannot guarantee that interference to PR is less than threshold T. Therefore, some relays are inactive because they generate harmful interference to PR. For adaptive transmit power (ATP), the power of a relay node is fixed so that peak interference power (PIP) or average interference power (AIP) constraints are verified. We also take into account interference from the primary transmitter (PT) by analyzing the delays based on signal to interference plus noise ratio (SINR). © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

Impacts of Licensed Interference and Inaccurate Channel Information on Information Security in Spectrum Sharing Environment

Spectrum sharing environment creates cross-interference between licensed network and unlicensednetwork. Most existing works consider unlicensed interference (i.e., interference from unlicensed networkto licensed network) while ignoring licensed interference (i.e., interference from licensed networkto unlicensed network). Moreover, existing channel estimation algorithms cannot exactly estimate channelinformation. In this paper, impacts of licensed interference and inaccurate channel information oninformation security in the spectrum sharing environment is analyzed under peak transmit power bound,peak interference power bound, and Rayleigh fading. Toward this end, a secrecy outage probabilityformula is proposed in an exact form and validated by simulations. Various results illustrate that secrecyoutage probability is constant in a range of large peak interference powers or large peak transmit powers,and is severely affected by licensed interference and inaccurate channel information.

Secure resource allocation for energy harvesting cognitive radio sensor networks without and with cooperative jamming

This paper studies secure resource allocation for energy harvesting cognitive radio sensor networks (EH-CRSNs) underlaying a small cell network, wherein the small cell base station (SCBS) employs adaptive or fixed transmit power for cooperative jamming or not while serving cellular users (CUs). Correspondingly, cognitive sensors (CSs) first harvest energy from the RF signals of SCBS and then communicate with each other concurrently with CUs in the licensed cellular channel which is wiretapped by an eavesdropper. Fully considering the peak interference power at CUs and the energy causality imposed by energy harvesting and processing cost, we investigate two secrecy rate maximization problems for secure resource allocation. For EH-CRSNs without cooperative jamming, we first transform the original non-convex problem into a convex problem and then employ the primary decomposition method to derive the optimal harvesting time and power allocation, with which CSs can perform reactive secure resource allocation according to the instantaneous channel state and the setup of the small cell. For EH-CRSNs with cooperative jamming, we employ the iterative optimization method to optimize the charging time and power allocation, with which SCBS can perform proactive secure resource allocation according to the instantaneous channel state. Extensive simulations evaluate the performance of EH-CRSNs and validate the effectiveness of the proposed algorithms.

Impact of Primary Interference on Secrecy Performance of Physical Layer Security in Cognitive Radio Networks

In cognitive radio networks (CRNs), primary interference is either neglected or considered as an additive white Gaussian random variable (r.v.). Current literature investigated such a case in evaluating their security capability. Generalizing this literature by considering primary interference power as exponentially-distributed r.v., we propose an analysis framework on impact of primary interference on security capability of CRNs under Rayleigh fading channels, peak transmit power constraint, and interference power constraint. The proposed framework is corroborated by Monte-Carlo simulations and illustrates that information securing performance in CRNs is saturated at either large values of peak transmit power or peak interference power, and can be enhanced by primary interference.

Performance Analysis of Optimum Combiner in Power Limited Cognitive Radios with Multiple Primary Interferers

This paper investigates the performance of power limited Cognitive Radio system with optimum combining at the cognitive user receiver under the influence of interference from multiple primary users’ transmitters (Lt) in flat Rayleigh fading channels. An approximate analytical result of the probability density function of maximum signal-to-interference ratio at the output of CR-OC receiver is derived. Using this derived PDF, the closed form expressions for the performance metrics viz. Average post processed SIR, Ergodic capacity, Average bit error rate and outage probability of CR-OC system are derived by taking into account peak interference power constraint denoted by ‘Q’ at PU-Rx. Based on the achieved result, it is concluded that the performance of the proposed system degrades when number of primary interferers exceeds from Lt=3. Analytical results for CR-OC system are validated through Monte Carlo simulations also.DOI: http://dx.doi.org/10.5755/j01.eie.24.1.20159

Resource Allocation for Green Cognitive Radios: Energy Efficiency Maximization

Green cognitive radios are promising in future wireless communications due to high energy efficiency. Energy efficiency maximization problems are formulated in delay‐insensitive green cognitive radio and delay‐sensitive green cognitive radio. The optimal resource allocation strategies for delay‐insensitive green cognitive radio and delay‐sensitive green cognitive radio are designed to maximize the energy efficiency of the secondary user. The peak interference power and the average/peak transmit power constraints are considered. Two algorithms based on the proposed resource allocation strategies are proposed to solve the formulated problems. Simulation results show that the maximum energy efficiency of the secondary user achieved under the average transmit power constraint is higher than that achieved under the peak transmit power constraint. It is shown that the design of green cognitive radio should take the tradeoff between its complexity and its achievable maximum energy efficiency into consideration.

Throughput of Cooperative HARQ protocols for Underlay Cognitive Radio Networks using Adaptive and Fixed Transmit Power

In this paper, we study theoretically and by simulations the throughput of cooperative hybrid automatic repeat request (HARQ) protocols for underlay cognitive radio networks (CRN). Both fixed and adaptive power transmission are studied. Different relay selection techniques with amplify and forward (AF) and decode and forward (DF) relaying are investigated. For fixed transmit power, some relays are not available due to interference constraints. The best relay is selected among the available ones. For adaptive transmit power, all relays adapt their power so that interference to primary receiver is always lower than a predefined threshold T. In this case, all relays will be available for retransmitting the secondary source packet. Both average interference power (AIP) and peak interference power constraints (PIP) are studied. We also analyse the effect of primary interference on secondary throughput.