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A bound on the capacity of the causal dirty-paper channel with arbitrary interference and general independent identically distributed additive noise is derived. In particular, it is shown that for the case of Gaussian noise, the capacity is upper bounded by \log_2\left(1+SNR/e\right) bits per real dimension. This bound is useful for SNR\leq e(e-2). [ABSTRACT FROM AUTHOR]

In this paper, we extend the interference channel with degraded message sets model by introducing multiple secondaries. The new model allows for multiple concurrent transmissions in a wireless network by employing dirty paper and superposition coding. We apply the proposed scheme to the communication between nodes in a wireless mesh network (WMN). The cases of different WMN. topologies are analyzed, and numerical results show that considerable capacity gains are achieved when using the proposed model with multiple secondaries. [ABSTRACT FROM AUTHOR]

This paper studies the combination of practical trellis and convolution codes with Tomlinson-Harashima precoding (THP) for the presubtraction of multiuser interference that is known at the transmitter but not known at the receiver. It is well known that a straightforward application of THP suffers power, modulo, and shaping losses. This paper proposes generalizations of THP that recover some of these losses. At a high signal-to-noise ratio (SNR), the precoding loss is dominated by the shaping loss, which is about 1.53 dB. To recover shaping loss, a trellis-shaping technique is developed that takes into account the knowledge of a noncausal interfering sequence, rather than just the instantaneous interference. At rates of 2 and 3 bits per transmission, trellis shaping is shown to be able to recover almost all of the 1.53-dB shaping loss. At a low SNR, the precoding loss is dominated by power and modulo losses, which can be as large as 3-4 dB. To recover these losses, a technique that incorporates partial interference presubtraction (PIP) within convolutional decoding is developed. At rates of 0.5 and 0.25 bits per transmission, PIP is able to recover 1-1.5 dB of the power loss. For intermediate SNR channels, a combination of the two schemes is shown to recover both power and shaping losses. [ABSTRACT FROM AUTHOR]

At present, the MVDC distribution grid is developing rapidly and relay protection is the key technology to ensure stable operation. Therefore, this paper focuses on the fault line selection method. Firstly, the fault characteristics are analysed when a fault occurs in the line, and a novel single‐pole fault line selection method is proposed based on 0‐mode power. The polarity of current fault component measured at the terminal of each line is used to identify the internal and external faults. And the 0‐mode power is used to select the faulty line. Finally, to verify the correctness of the proposed method, a radial MVDC distribution grid is built in PSCAD to output fault data in different fault conditions, and the fault line selection algorithm is implemented in MATLAB. The simulation results show that the proposed method is fast, effective, reliable and it has a certain degree of tolerance to transition resistance with a strong anti‐data delay and anti‐interference ability. Moreover, the fault line selection method proposed in this paper can still correctly select the fault line in the case of serious faults such as multiple line faults, sudden removal of lines, and sudden changes in photovoltaic output power. [ABSTRACT FROM AUTHOR]

The accurate voltage measurement of distribution networks is of great significance in power dispatching and fault diagnosis. Voltage sensors based on the spatial electric field effect do not require grounding, which provides the possibility for the distributed measurement of transmission line voltages. However, the divider ratio of suspension grounding voltage sensors is affected by the height between the sensor and the ground, as well as the distance between the sensor and the telegraph pole. In this paper, a self-calibration method based on internal capacitance transformation is proposed to realize the on-line calibration of suspension grounding voltage sensors. The calibration is accomplished by switching different parameters in the conditioning circuit, and the calibration process does not require power failure or known input excitation. In addition, the impact of electric fields in the other two phases of three-phase transmission lines on measurement through simulation research is quantified in this paper. In order to reduce the impact of interference electric fields, an equipotential shielding structure is designed. The circuit topology and probe prototype have been developed and testing has been conducted in laboratory conditions; the experimental results show that the maximum relative error of voltage amplitude is 1.65%, and the phase relative error is 0.94%. The measurement accuracy is not limited by the height to ground or the distance to the telegraph pole. In addition, in the application of an equipotential shielding probe, the maximum deviation of measured voltage is 0.7% with and without interference electric fields. [ABSTRACT FROM AUTHOR]

This paper presents a method for reducing apparent cable capacitance seen by sensors. The proposed method is designed for sensing in extreme environments including ultra-high temperatures, but can be applied in benign environments as well. By reducing the cable capacitance, high speed signals can be transmitted over longer distances, allowing the application of advanced control systems that require high bandwidth data for stable operation. A triaxial cable with an associated guard circuit is developed that actively reduces cable capacitance while also rejecting extraneous electric and magnetic interference on the signal. The active capacitance reduction method developed is tested experimentally and shown to reduce apparent cable capacitance to two percent of the static value. [ABSTRACT FROM AUTHOR]

In this paper, an interference channel with a cognitive relay (IFC-CR) is considered to achieve spectrum sharing between a licensed primary user and an unlicensed secondary user. The CR assists both users in relaying their messages to the respective receivers, under the constraint that the performance of the legacy primary user is not degraded. Without requiring any non-causal knowledge, the CR uses a successive interference cancellation to first decode the primary and secondary messages after a transmission phase. A power allocation is then performed to forward a linear weighted combination of the processed signals in the relaying phase. Closed-form expressions of the end-to-end outage probability are derived for both primary and secondary users under the proposed approach. Furthermore, by exploiting the decoded primary and secondary messages in the first phase, we propose the use of dirty paper coding (DPC) at CR to pre-cancel the interference seen at the secondary (or primary) receiver in the second phase, which results in a performance upper bound for the secondary (or primary) user without affecting the other user. Simulation results demonstrate that with a joint consideration of the power control at the secondary transmitter and the power allocation at CR, performance gains can be achieved for both primary and secondary users. [ABSTRACT FROM AUTHOR]

To the significant amount of pilot overhead of the interference cancelation methods in orthogonal frequency division multiplexing (OFDM) based on offset quadrature amplitude modulation (OFDM/OQAM) system, we proposed an improved interference cancelation method (ICM) for OFDM/OQAM system in this paper. In this method, we use the auxiliary pilot (AP) to eliminate the influence of the intersymbol interference on channel estimation, which can reduce the pilot overhead of OFDM/OQAM system significantly. At the same time, to improve the channel estimation performance, we analyze the source of the intrinsic interference of system and its distribution in time and frequency domain, then, we reset the interference cancelation range of AP, which can cancel more intrinsic interference for OFDM/OQAM system. According to the results of performance analysis, compared to the conventional interference cancelation methods, the proposed method performs better in terms of energy efficiency and spectral efficiency. Also, the simulation results of the proposed method show that the proposed method can outperform traditional interference cancelation methods in channel estimation performance. [ABSTRACT FROM AUTHOR]

A compact and efficient design for the electromagnetic interference (EMI) filter stage has become one of the most critical challenges in designing a high-density power converter, particularly for avionic applications. To maintain the regulatory standard requirements, EMI filter design needs to be precisely implemented. However, the attenuation characteristics of common-mode (CM) and differential-mode (DM) EMI filters may vary in practice from their respective theoretical calculations due to difficulty and inaccuracy in the noise modeling. This is particularly true for a three-phase active boost rectifier, which inherently has a CM high-frequency component in the rectifier output. This paper puts forward a detailed mathematical modeling of CM noise, originated from different sources, and discusses a concept to significantly reduce the CM noise effects. Furthermore, minimizing the weight and size of DM filter stage has been a design concern as the DM stage consumes a significant part of the weight of the whole system. This paper proposes a compact EMI filter topology with enhanced power density, which aims at satisfying the conducted EMI requirements according to DO-160F in avionics applications. The experimental verifications of the designed EMI filter are performed from the conducted emission results, obtained from a 6-kW laboratory prototype of an integrated stage of EMI and three-phase boost PFC converter. [ABSTRACT FROM AUTHOR]

Based on the purpose of proactive anti-reconnaissance, the essential characteristics of several typical pulse repetition interval (PRI) sorting algorithms were analysed and the feasibility of counter-deinterleaving was discussed. A method for disturbing arrival time sequence by using interference pulse was proposed, which changes the statistical properties of the radar PRI to disturb the deinterleaving results. The simulation results show that the pulse jamming method proposed in this paper can influence PRI sorting process effectively, which let signal processer make a misjudgment on PRI pattern of radar. [ABSTRACT FROM AUTHOR]

Papers, books, and standards consider the problem of mutual interactions of ground systems (GSs) by experimental data, parametric curves, mathematical approaches, and computer programs. This paper aims to analyze the physical phenomenon and basics, exemplifying the interference between GSs, such as their comparability, common intersection, mutual transfer resistance, and coupling factors. These characteristics assist to suppose the systems behavior in interaction and to suggest practical criteria for verifying the adequacy of GSs also versus the external interferences among them or/and with buried extraneous conductive part. The presence of a “global grounding system” (GGS) in the influence zone of a GS is a relevant case of interference. For definition, the GGS is not interfering, but can be locally interfered with unexpected increases of touch and step voltages. The global performance of an interfered GS can be defined by the overlap of two opposite and simultaneous behaviors: the passive and active behaviors, useful to characterize a GGS. In fact, a GGS essentially presents a passive behavior. [ABSTRACT FROM AUTHOR]

This paper suggests an advanced approach in the verification of the adequacy of a grounding system (GS) located in a common zone of influence with other GSs, taking into account the mutual interferences between the GSs. In fact, the presence of other GSs can transfer inadmissible touch and step voltages on the testing GS, particularly sensitive for critical power systems as data centers and hospitals. The safety of a local GS or of a global GS (GGS) does not admit uncontrolled interferences. Simulation programs assume a relevant importance, because they allow analyzing the interferences of GSs, particularly in operational difficulties for the tests. GSs have to maintain within the installation lifetime their characteristics of integrity and continuity and their safety performances; hence, they require a management program. This paper highlights the relevance of intrinsically safe GSs that guarantee safe touch/step voltages lower than permissible permanent voltages such as GGSs. GSs in city centers and urban and industrial areas evolve in time. Each installation of a new GS can influence the performance of the GSs existent in the area. Inspections and measurements are also necessary, following variations that can influence essential requirements. [ABSTRACT FROM AUTHOR]

A time instant is said to be a critical instant for a task, if the task’s arrival at the instant makes the duration between the task’s arrival and completion the longest. Critical instants for a task, once revealed, make it possible to check the task’s schedulability by investigating situations associated with the critical instants. This potentially results in efficient and tight schedulability tests, which is important in real-time systems. For example, existing studies have discovered critical instants under preemptive fixed-priority scheduling (P-FP), which limit interference from carry-in jobs, yielding the state-of-the-art schedulability tests on both uniprocessor and multiprocessor platforms. However, studies on schedulability tests associated with critical instants have not matured yet for non-preemptive scheduling, especially on a multiprocessor platform. In this paper, we find necessary conditions for critical instants for non-preemptive global fixed-priority scheduling (NP-FP) on a multiprocessor platform, and develop a new schedulability test that takes advantage of the finding for reducing carry-in jobs’ interference. Evaluation results show that the proposed schedulability test finds up to 14.3 percent additional task sets schedulable by NP-FP, which are not deemed schedulable by the state-of-the-art NP-FP schedulability test. [ABSTRACT FROM AUTHOR]

Recent history demonstrates that threat has no borders, though risk does, due to national and regional differences in vulnerabilities and exposure landscapes. The difference between well and poorly managed threat is striking. Inequalities in preparing for threats as a function of their type are still apparent. Compared to more concerning electromagnetic interference threats, the impact of geomagnetic disturbance (GMD) on power grid operation is not well studied. The need for detailed research of GMD negative impacts is expected to broaden awareness. The amplitude of geomagnetically induced currents (GICs) is treated as a uniform measure of danger that can be processed by various stakeholders. Hence, methods for increasing the accuracy of GIC representation are presented in this paper. A low-entropy signal is defined and it is shown that the feature of low signal entropy can be used for increasing the accuracy of the measurement equipment. At the end, a full-system view of GMD impact on power grid operation is given. [ABSTRACT FROM AUTHOR]

Recent information-theoretic results show the optimality of dirty-paper coding (DPC) in achieving the full capacity region of the Gaussian multiple-input multiple-output (MIMO) broadcast channel (BC). This paper presents a DPC based code design for BCs. We consider the case in which there is an individual rate/signal-to-interference-plus-noise ratio (SINR) constraint for each user. For a fixed transmitter power, we choose the linear transmit precoding matrix such that the SINRs at users are uniformly maximized, thus ensuring the best bit-error rate performance. We start with Cover's simplest two-user Gaussian BC and present a coding scheme that operates 1.44 dB from the boundary of the capacity region at the rate of one bit per real sample (b/s) for each user. We then extend the coding strategy to a two-user MIMO Gaussian BC with two transmit antennas at the base-station and develop the first limit-approaching code design using nested turbo codes for DPC. At the rate of 1 b/s for each user, our design operates 1.48 dB from the capacity region boundary. We also consider the performance of our scheme over a slow fading BC. For two transmit antennas, simulation results indicate a performance loss of only 1.4 dB, 1.64 dB and 1.99 dB from the theoretical limit in terms of the total transmission power for the two, three and four user case, respectively. [ABSTRACT FROM AUTHOR]

Due to the electromagnetic induction between transmission lines and the associated grounding wires, power frequency current causes flow into the ground network via the metallic tower, which may interfere with grounding resistance measurements. This paper analyzes the mechanisms of this interference, and shows that power frequency interference becomes stronger at phase-wire transposition towers. Grounding resistance measurement by the variable frequency (VF) method has been proven to be effective in dealing with power frequency interference. However, the test equipment based on the VF method is always deactivated when the external interference voltage exceeds a preset level in order to avoid false readings. This paper aims at tackling the problem by introducing a reverse phase cancellation (RPC) method, which acquires and processes the interference signal before generating a cancelling signal with the same amplitude and frequency and a phase which is exactly opposite in polarity. This paper proves that the RPC method represents an excellent improvement over the VF method since it retains the advantages of VF and avoids the trip-out of test equipment due to excessive interference. [ABSTRACT FROM AUTHOR]

This paper presents an optimization approach for a system consisting of multiple bidirectional links over a two-way amplify-and-forward relay. Improvement to the fairness of the system is desired. All user pairs exchange information over one relay station (RS) with multiple antennas. Due to the joint transmission to all users, the users are subject to mutual interference. A mitigation of the interference can be achieved by max–min fair precoding optimization where the relay is subject to a sum power constraint. The resulting optimization problem is nonconvex. This paper proposes a novel iterative low-complexity approach based on a modified Levenberg–Marquardt (LM) method to find near optimal solutions. The presented method finds solutions close to the standard convex-solver-based relaxation approach. [ABSTRACT FROM PUBLISHER]

Wireless network virtualization is a promising technique for future wireless networks. In this paper, different from traditional virtualization approaches by means of resource isolation at the subchannel or time-slot level, we propose a novel framework of heterogeneous cellular network virtualization combined with interference alignment (IA) technology, which utilizes IA to cancel the mutual interference, by aligning the interference from other transmitters into a lower dimensional subspace at each receiver. In this framework, we formulate the virtual resource allocation as a joint virtualization and IA problem, considering the gain not only from interference mitigation introduced by IA but from the sum-rate improvement brought by virtualization as well. In addition, to reduce the computational complexity, with the recent advances in discrete stochastic approximation (DSA), we propose a two-step algorithm to solve the formulated problem. The basic principle is to design IA schemes for each feasible association combination and then to traverse the association space to search for the optimal association combination with the maximum sum rate. Extensive simulations are conducted with different system parameters to show the effectiveness of the proposed scheme. [ABSTRACT FROM PUBLISHER]

In grounded photovoltaic (PV) systems, dc leakage to earth is formed by the contribution of the PV modules, inverters, and dc circuitry. Ground faults in such systems occur when there is an unintentional connection between any dc-carrying conductor with a grounded surface or earth. On the occurrence of ground faults, dc leakage will be intensified and will flow through the earth or other conductive paths, before returning back to the source. Thus, it is highly probable that some portion of the dc leakage will attempt to return to the source through any low-resistance paths that exist in the nearby vicinity, for example, through nearby buried pipelines. Therefore, unattended dc leakage may induce stray current corrosion concerns on these pipelines. To this extent, this paper presents a detailed dc interference modeling for assessing the dc leakage activity in PV systems—particularly under undetected fault conditions. First, the modeling carried out embraces the topologically accurate consideration of all sources of dc leakage that are associated with the grounded PV systems. A second feature presented in the paper is the modeling of blind-spot dc faults and their impact on third-party infrastructure. [ABSTRACT FROM AUTHOR]

Interference alignment (IA) is a promising technique to effectively manage the interference. The realization of IA requires a proliferation of feedback bits. In a general centralized feedback model, the feedback rate of the precoder and the decoder affects the performance of the IA directly. In this paper, to improve the feedback efficiency of the precoder and the decoder, a strategy that can adaptively allocate the feedback bits of the precoder and the decoder is proposed. We consider the effect of link loss on the throughput loss caused by the quantization error of the precoder and decoder. An upper bound of leaked interference as a function of the link loss and the feedback bits of the precoders and the decoders is derived. The feasibility conditions for dynamically allocating the feedback bits of the precoder and the decoder are analyzed. It is proven that the properties of general asymmetric interference network can satisfy the feasibility conditions for dynamic feedback scheme. According to the simulation results, our proposed scheme achieves higher throughput compared with the conventional schemes in the asymmetric interference network. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the performance of single-stream and multistream spatial multiplexing (SM) systems employing opportunistic scheduling in the presence of interference. In the proposed downlink framework, every active user reports the postprocessing signal-to-interference-plus-noise power ratio (post-SINR) or the receiver-specific mutual information (MI) to its own transmitter using a feedback channel. The combination of scheduling and multiantenna receiver processing leads to substantial interference suppression gain. Specifically, we show that opportunistic scheduling exploits the spatial interference alignment (SIA) property inherent to a multiuser system for effective interference mitigation. We obtain bounds for the outage probability and the sum outage capacity for single-stream and multistream SM employing real or complex encoding for a symmetric interference channel (SIC) model. The techniques considered in this paper are optimal in different operating regimes. We show that the sum outage capacity can be maximized by reducing the SM rate to a value less than the maximum allowed value. The optimal SM rate depends on the number of interferers and the number of available active users. In particular, we show that the generalized multiuser SM (MU SM) method employing real-valued encoding provides a performance that is either comparable or significantly higher than that of MU SM employing complex encoding. A combination of analysis and simulation is used to describe the tradeoff between the multiplexing rate and the sum outage capacity for different antenna configurations. [ABSTRACT FROM PUBLISHER]

In this paper, we evaluate the outage performance of a decode-and-forward (DF) relay system with two low-complexity relay selection schemes and interference at the relays and the destination. The schemes are mainly based on the switch-and-examine diversity combining (SEC) and SEC postexamine selection (SECps) techniques in which a relay out of multiple relays is selected to forward the source message to the destination. The selection process is performed such that the signal-to-noise ratio (SNR) of the second hop of the selected relay satisfies a predetermined switching threshold. In this paper, we first derive the probability density function (pdf) of the SNR of the relay selection scheme and the conditional cumulative distribution function (cdf) of the end-to-end (e2e) signal-to-interference-plus-noise ratio (SINR), assuming Rayleigh fading channels. The derived statistics, along with the statistics of first-hop channels of the relays and the direct link, are then used to derive a closed-form expression of the e2e outage probability. Maximal-ratio combining (MRC) is used at the destination to combine the signals from the relay and the direct link. Furthermore, the outage performance is studied at the high-SNR regime where approximate expressions for the outage probability, diversity order, and coding gain are derived and analyzed. Monte Carlo simulations and some numerical examples are provided to illustrate the validity of the derived results and to show the effect of interference and other parameters on the system performance. Main results illustrate that when the interference power is fixed, the system can still achieve some performance gain when more relays are added, particularly at SNR values that are comparable with the switching threshold. Asymptotic results show that at a high SNR, the system with the SEC and SECps relaying schemes achieves a diversity order of 2 and approximately the same coding gain. Finally, findings illustrate that the interference at the destination is more severe on the system performance compared with that at the relays. [ABSTRACT FROM PUBLISHER]

This paper presents a fully automatic leak detection system for slow oscillation high-pressure fluid-filled (HPFF) circuits. It also presents the concept of detecting leaks in such circuits, utilizing only a limited number of sensors. It will describe algorithms built upon this concept, including two different approaches to the construction of the decision module, crucial for detection capabilities. The proposed solution utilizes adaptive digital filters for modeling the circuit behavior and a Bayesian network coupled with a software leak simulator in the decision stage. These tests were performed using data obtained from a real-life circuit, including real-leak data. This paper may enable practical application of high-precision low-cost leak detection solutions for a wide range of HPFF circuits. [ABSTRACT FROM AUTHOR]

Magnetically levitated planar motor (MLPM) with moving-magnet has the advantages of no electric cable interference and no cooling for moving part. In this paper a novel superconducting magnetic levitation planar motor (SMLPM) whose stator uses high-temperature superconducting coils is proposed. Based on the traditional design, the cooling system and thermal shield are added. The copper coil used in the traditional magnetic levitation planar motor cannot provide large current density and have very low force-to-mass ratio. As superconducting technology has the advantages of low energy consumption and high current density, SMLPM could provide greater driving force and torque. Based on the new system, an analytical model was used to calculate the electromagnetic force/torque acting on the Halbach permanent magnet array. The heat load to the cryogenic system is calculated. The finite element method (FEM) for full model has been used to benchmark the magnetic field and force of the theoretical result. [ABSTRACT FROM AUTHOR]

Out-of-band interference by antenna coupling is frequently encountered and difficult to compensate. In this paper, it is studied for the first time using characteristic mode analysis (CMA). Mutual coupling between two antennas is separated into several fundamental modes, and the contribution of each mode is evaluated through modal mutual admittance (MMA). Some higher order modes, which contribute little to the in-band radiation but much to the out-of-band coupling, are discriminated and controlled by means of inductive loadings. The placement of loadings is suggested by the distribution of eigencurrents and optimum values are obtained by evaluating the MMA. Numerical and experimental results are presented for verification. [ABSTRACT FROM AUTHOR]

Base station cooperation can exploit knowledge of the users' channel state information (CSI) at the transmitters to manage co-channel interference. Users have to feedback CSI of the desired and interfering channels using finite-bandwidth backhaul links. Existing codebook designs for single-cell limited feedback can be used for multicell cooperation by partitioning the available feedback resources between the multiple channels. In this paper, a new feedback-bit allocation strategy is proposed, as a function of the delays in the communication links and received signal strengths in the downlink. Channel temporal correlation is modeled as a function of delay using the Gauss-Markov model. Closed-form expressions for bit partitions are derived to allocate more bits to quantize the stronger channels with smaller delays and fewer bits to weaker channels with larger delays, assuming random vector quantization. Cellular network simulations are used to show that the algorithm presented in the paper yields higher sum-rates than the equal-bit allocation technique. [ABSTRACT FROM PUBLISHER]

In 1975, Carleial presented a special case of an interference channel, called the very strong interference regime, in which the interference does not reduce the capacity of the constituent point-to-point Gaussian channels. In this paper, we show that in the strictly very strong interference regime, the dispersions are similarly unaffected. More precisely, in this paper, we characterize the second-order coding rates of the Gaussian interference channel in the strictly very strong interference regime. In other words, we characterize the speed of convergence of rates of optimal block codes toward a boundary point of the (rectangular) capacity region. These second-order coding rates are expressed in terms of the average probability of error and variances of appropriately defined information densities which coincide with the dispersion of the (single-user) Gaussian channel. This allows us to conclude that the dispersions are unaffected by interference in this channel model. [ABSTRACT FROM AUTHOR]

This paper addresses a decentralized wireless networks of K separate transmitter-receiver pairs. Users treat each other as noise and there is no central controller to assign the resources to the users. Each user randomly spreads the symbols in its Gaussian codewords by the so-called signatures of spreading gain N . Any receiver is aware of the signatures of its affiliated transmitter, however, it is unaware of the signatures of other users. This makes the interference plus noise at each receiver be mixed Gaussian, and hence, there is no closed expression for the achievable rates of users. Invoking conditional entropy power inequality and a key upper bound on the differential entropy of a mixed Gaussian random vector, we develop a lower bound on the achievable rates of users. This lower bound has the same signal-to-noise ratio (SNR) scaling as that of the exact achievable rate. It is shown that the sum multiplexing gain (SMG) in the network can be made arbitrarily close to (K/N) for any finite values of K and N where K\leq N . The effect of matched filtering is studied in the particular case where the signatures are constructed over a binary alphabet. It is established that the SMG of the network is larger than (1/2e) regardless of the value of K as long as $N=2$ and the signatures are generated according to a proper nonuniform distribution. This paper is concluded by a section on signature design in the finite SNR regime. The main observation is that for any two different methods A and B of designing the signatures, if method A results in a larger achievable rate per user for sufficiently large SNR values, then construction B is likely to yield larger achievable rates for sufficiently small values of SNR. This behavior is attributed to the interplay between two critical factors, namely, the multiplexing gain per user and what we refer to as the interference entropy factor. [ABSTRACT FROM AUTHOR]

Heterogeneous networking is a promising solution for improving wireless coverage, relieving overcrowded bandwidth, and enhancing system throughput for next-generation wireless networks. However, one of the main concerns to put through heterogeneous networks is the interference among overlaid cells. In this paper, we consider femtocell uplink transmissions with dynamic and short-period interference (also called shot interference) from macrocell users. It is shown that, without the information on interferer channels between femtocells and macrocells at any base station, femtocell networks suffer from severe performance degradation when they adopt orthogonal frequency-division multiple access (OFDMA) or single-carrier FDMA (SC-FDMA) techniques. To mitigate the stringent shot interference, we propose a precoded FDMA (P-FDMA) transmission with novel detectors. Our results show that the proposed designs collect multipath diversity in the presence of interference without the knowledge of interferer channels, and our designs are robust to the power levels of shot interference. Simulation results validate our theoretical findings. [ABSTRACT FROM PUBLISHER]

Mobile edge computing (MEC) has attracted great interests as a promising approach to augment computational capabilities of mobile devices. An important issue in the MEC paradigm is computation offloading. In this paper, we propose an integrated framework for computation offloading and interference management in wireless cellular networks with MEC. In this integrated framework, we formulate the computation offloading decision, physical resource block (PRB) allocation, and MEC computation resource allocation as optimization problems. The MEC server makes the offloading decision according to the local computation overhead estimated by all user equipments (UEs) and the offloading overhead estimated by the MEC server itself. Then, the MEC server performs the PRB allocation using the graph coloring method. The outcomes of the offloading decision and PRB allocation are then used to distribute the computation resource of the MEC server to the UEs. Simulation results are presented to show the effectiveness of the proposed scheme with different system parameters. [ABSTRACT FROM AUTHOR]

This paper reconsiders the design of blind interference alignment (BIA) for $K$-user MISO interference channel in which each receiver is equipped with a reconfigurable antenna of preset $M_k\geq 3$ modes. Beyond the degree of freedom (DoF)-oriented BIA (D-BIA) design proposed by Lu et al., we further take into account the frequency of mode switching within one supersymbol frame. Even though every receiving antenna is reconfigurable with preset multiple modes, from an engineering perspective, it is of practical importance for each receiving antenna to make less number of mode switching in order to gain the benefits such as less switching power consumption and less signal distortion. To this end, we propose in this paper switching-oriented BIA (S-BIA) scheme, which preserves the same degree of freedom (DoF) gain as D-BIA while offering reduced mode switching frequency. Theoretical analysis and simulation results demonstrate that, compared to D-BIA, S-BIA can gain $100/(M-1)$ percent of switching saving when $M_k = M$ is odd for all transmitters. Remarkably, S-BIA offers 50% switching saving for multiuser $3\times 1$ interference channels. [ABSTRACT FROM AUTHOR]

This paper describes an evaluation of the Keysight 3458A digital multimeter (DMM) noise performance. A DMM noise model is given in closed form for all ranges and integrating analog-to-digital converter (IADC) aperture times. When the DMM is used for sampling, different sources of noise contribute to the total noise of the sampled signal. Their combined effect was measured using both short-circuited input terminals and spectrally pure Josephson arbitrary waveform synthesizer. Both white noise and 1/ f noise were evaluated. The results confirmed that the internal IADC can be used to measure DMM input referred noise when the IADC quantization noise is smaller than the instrument front-end analog circuitry-related noise. Further, it is shown that the DMM noise can be effectively measured with short-circuited input terminals when using double integer output format, but not always when using single integer output format. The manufacturer specifications were confirmed on all but the 100-V range. [ABSTRACT FROM AUTHOR]

The paper focuses on the two-way relay channel (TWRC) and the multi-way wireless network with three terminals, where all three want to exchange or share data and have to do that with the help of a relay. This paper shows how it is possible to significantly decrease the number of time slots required to exchange messages between terminals in networks based on time-division multiple access (TDMA), by taking into consideration new techniques at the physical (PHY) layer. The paper considers a PHY layer where physical-layer network coding (PLNC), multiple-input multiple-output (MIMO), and in-band 'full-duplex' (IBFD) with loopback interference cancellation are all integrated, so that it is possible to significantly increase the overall throughput of the network. This is entirely attained by transferring the burden from the time domain to the spatial domain, via spatial multiplexing and by simultaneously resorting to non-orthogonal multiple access, which is the consequence of using both PLCN and IBFD. For the TWRC, it is shown that, if a massive MIMO relay is used, a simple lattice-based PLNC can be directly applied and, with typical IBFD interference cancellation amounts, a TWRC can effectively use only one time slot instead of the four needed when adopting the traditional TDMA exchange. In the case of the Y-network (i.e., with three terminals), a technique is presented that allows all the information exchange between terminals to be cut from the six time slots required in TDMA to only one time slot, provided that the information packets are not too short. The error performance of these systems is measured by means of simulation using MIMO Rayleigh fading channels. [ABSTRACT FROM AUTHOR]

Building on the recent coded-caching breakthrough by Maddah-Ali and Niesen, the work here considers the $K$ -user cache-aided wireless multi-antenna symmetric broadcast channel with random fading and imperfect feedback, and analyzes the throughput performance as a function of feedback statistics and cache size. In this setting, this paper identifies the optimal cache-aided degrees-of-freedom (DoF) within a factor of 4, by identifying near-optimal schemes that exploit a new synergy between coded caching and delayed CSIT, as well as by exploiting the unexplored interplay between caching and feedback-quality. The DoF expressions reveal an initial gain due to current CSIT, and an additional gain due to coded caching, which is exponential in the sense that any linear decrease in the required DoF performance, allows for an exponential reduction in the required cache size. In the end, this paper reveals three new aspects of caching: a synergy between memory and delayed feedback, a tradeoff between memory and current CSIT, and a powerful ability to provide cache-aided feedback savings. [ABSTRACT FROM PUBLISHER]

Multiple-input–multiple-output (MIMO) full-duplex relaying (FDR) has been considered an efficient technique to provide coverage to users where their direct links from the base station (BS) are too weak for reliable signal reception. However, when multiple MIMO full-duplex relays are deployed in a network, the signal reception quality relies on the effective suppression of multiple types of interference. In this paper, the distributed beamforming is studied for the MIMO FDR network by formulating a power minimization problem with a nonstrict convex objective function (total transmit power of both the BS and all the relays in the network) under individual user rate constraints. We come up with two iterative distributed beamforming algorithms, Algorithm 1 for relays equipped with single receive antenna and Algorithm 2 with multiple receive antennas. The former can yield a global optimal solution of the power minimization problem, whereas the latter can yield only a local optimal solution due to conservative successive convex approximations (SCAs) performed at each iteration, and a rigorous analysis on the upper bounds of step sizes is proposed to guarantee their convergence. The proposed two algorithms only require local information exchange between relays and hence are scalable for different network sizes and topologies. An “early termination” strategy in the operation of the proposed two algorithms is also presented to acquire an acceptable transmit power solution with less computation time consumption and thus suitable for realistic applications. Finally, some simulation results are provided to demonstrate that the proposed two algorithms perform well and significantly better than the existing state-of-the-art scheme reported in the work of Lee and Shin. [ABSTRACT FROM PUBLISHER]

This paper presents a pulse width modulation (PWM) technique for the minimization of the leakage current in the grid-connected/stand-alone transformerless photovoltaic (PV)-cascaded multilevel inverter (CMLI). The proposed PWM technique is integrated with the MPPT algorithm and is applied to the five-level CMLI. Furthermore, using the proposed PWM technique the high-frequency voltage transitions in the terminal and common mode voltages are minimized. Thus, the proposed PWM technique minimizes the leakage current of the PV array and electromagnetic interference filter requirement in the system without addition of any extra switches. Furthermore, this paper also presents the analysis for the terminal voltage across the PV array and the common mode voltage of the inverter based on the switching function. Using the given analysis, the effect of the PWM technique can be analyzed, as it directly links the switching function with the common mode voltage and leakage current. Also, the proposed PWM technique requires reduced number of carrier waves compared to the conventional sinusoidal pulse width modulation technique for the given CMLI. Complete details of the working principle and analysis with the support of simulation and experimental results of the proposed PWM technique are presented in this paper. [ABSTRACT FROM PUBLISHER]

In this paper, we explore the three-node multi-terminal lossy source coding problem, which seems to offer a formidable mathematical complexity. We derive an inner bound to the general rate-distortion region of this problem, which is a natural extension of the seminal work by Kaspi on the interactive two-terminal source coding problem. It is shown that this (rather involved) inner bound contains several rate-distortion regions of some relevant source coding settings. In this way, besides the non-trivial extension of the interactive two terminal problem, our results can be seen as a generalization and hence unification of several previous works in the field. By specializing the inner bound to particular cases, we obtain some novel rate-distortion regions for several multi-terminal lossy source coding problems. [ABSTRACT FROM PUBLISHER]

This paper addresses the identification and correction of amplitude and offset errors in the sinusoidal outputs from incremental position encoders. Precise angular position measurement is of high importance in many position control applications. Manufacturing tolerances and noise from thermal and electromagnetic interference sources introduce systematic and random errors in the orthogonal sine cosine output line signals. Evaluation of these signals reproduces deviations in the measured angular position. This paper proposes two methods to identify and compensate for the influence of the systematic errors online without the necessity of a reference measurement during identification. The key component of the methods is a nonlinear estimator that exploits the orthogonality property of harmonic functions. The first method explains the basic idea with a scalar error model and operates continuously but exhibits an angular shift in direction of rotation during transients of the parameters, whereas the second method assumes an error model with error parameters as a function over one full revolution of the encoder. The latter updates the error function iteratively in subsequent revolutions. [ABSTRACT FROM AUTHOR]

The dynamic colour of three commercial reversible thermochromic inks were studied. Thermochromic printing inks change their colour according to a change in temperature. The two types of thermochromic inks are based on leuco dyes and liquid crystals. The thermochromic effect achieved by liquid crystals is quite different from the effect achieved with leuco dyes. Leuco dyes change from a coloured to a colourless state, or from one colour shade to another due to structural changes inside leuco dye molecules under assistance of developer. Liquid crystal inks change colour continuously throughout the spectrum, producing iridescent colours starting from red and shifting to blue part of the spectrum with temperature. The colour change results from the way light interacts with special arrangement of liquid crystal molecules to produce coloured reflection by interference, and with the variation of this structure with temperature. In this paper we will present differences between two types of thermochromic printing inks giving careful colorimetric characterization. [ABSTRACT FROM AUTHOR]

This paper studies the capacity region of a K-user cyclic Gaussian interference channel, where the kth user interferes with only the (k-1)th user (mod K) in the network. Inspired by the work of Etkin, Tse, and Wang, who derived a capacity region outer bound for the two-user Gaussian interference channel and proved that a simple Han–Kobayashi power-splitting scheme can achieve to within one bit of the capacity region for all values of channel parameters, this paper shows that a similar strategy also achieves the capacity region of the K-user cyclic interference channel to within a constant gap in the weak interference regime. Specifically, for the K-user cyclic Gaussian interference channel, a compact representation of the Han–Kobayashi achievable rate region using Fourier–Motzkin elimination is first derived; a capacity region outer bound is then established. It is shown that the Etkin–Tse–Wang power-splitting strategy gives a constant gap of at most 2 bits in the weak interference regime. For the special three-user case, this gap can be sharpened to 1 1\over 2 bits by time-sharing of several different strategies. The capacity result of the K-user cyclic Gaussian interference channel in the strong interference regime is also given. Further, based on the capacity results, this paper studies the generalized degrees of freedom (GDoF) of the symmetric cyclic interference channel. It is shown that the GDoF of the symmetric capacity is the same as that of the classic two-user interference channel, no matter how many users are in the network. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the multiuser diversity gain in a cognitive radio (CR) system where the secondary transmitters opportunistically utilize the spectrum licensed to primary users only when it is not occupied by the primary users. To protect the primary users from the interference caused by missed detection of primary transmissions at the secondary receivers, minimum average throughput of the primary network is guaranteed by transmit power control at the secondary transmitters. The traffic dynamics of a primary network are also considered in our analysis. We derive the average system throughput of the secondary network and analyze its asymptotic behaviors to characterize the multiuser diversity gain in the CR system. It is shown that the throughput gain of the CR system depends on the levels of the peak power constraints on the secondary transmitters and the reliability of spectrum sensing. The asymptotic scaling law of the secondary network throughput is also shown to be different according to maximum allowable transmit power at the secondary transmitters. The derived scaling law is interestingly similar to that in underlay CR systems even though the spectrum utilization mechanism of the underlay CR systems is totally different from the CR model considered in this paper. We also extend our results to non-independent and identically distributed (non-i.i.d.) channels by employing fairness scheduling and show that fairness scheduling in non-i.i.d. channels has the same asymptotic throughput characteristics as the best user selection in i.i.d. channels. [ABSTRACT FROM PUBLISHER]

This paper investigates the possibility of having convex or concave formulations of optimization problems for interference coupled wireless systems. An axiomatic framework for interference functions proposed by Yates in 1995 is used to model interference coupling in our paper. The paper shows that under certain natural assumptions, the exponential transformation is the unique transformation (up to a positive constant) for “convexification” of resource allocation problems for linear interference functions. Furthermore, it is shown that under certain intuitive assumptions, it is sufficient to check for the joint concavity (convexity) of sum of weighted functions of SINR (inverse SINR) with respect to s (p=e^s, where p is the power vector of the users), if we would like the resulting resource allocation problem to be concave (convex). This paper characterizes the largest class of utility functions and the largest class of interference functions (respectively), which allow a convex and concave formulation of a problem for interference coupled wireless systems. It extends previous literature on log-convex interference functions and provides boundaries on the class of problems in wireless systems, which can be algorithmically tackled by convex optimization techniques. [ABSTRACT FROM AUTHOR]

When two filters are cascaded together, unwanted spikes appear in the rejection region. These spikes can have a strong impact on the rejection performance of the resulting filter. Therefore, it is desired to suppress or move them far away from the operational band, including part of the rejection band as well. This paper addresses a systematic evaluation of such phenomenon and proposes a simple yet effective method, called spike envelope curve, to have, in a single run and for any frequency, the worst possible case, without the need of repeating onerous analyses. It is also shown that a judicious choice of the length and losses of the line separating the filters can be exploited to mitigate considerably such a negative effect. The method is assessed by full-wave simulations and measurements. [ABSTRACT FROM AUTHOR]

The ultrawideband software-defined microwave radiometer is a 500–2000-MHz radiometer developed to probe temperatures inside ice sheets. Given the instrument’s operation outside of protected portions of the spectrum, radio frequency interference (RFI) is a significant concern, and the instrument is designed to facilitate RFI detection and filtering. This paper analyzes the design and operation of the radiometer, the accuracy and stability of the brightness temperatures it produces, and the RFI analyses of the results acquired in its debut flight over northern Canada and Greenland in September 2016. [ABSTRACT FROM AUTHOR]

Interference in multiuser systems is often characterized by a non-negative and irreducible coupling matrix. The maximum eigenvalue (Perron root) of the weighted coupling matrix provides a single measure for the joint achievability of certain signal-to-interference ratios (SIR). In this paper, we address the more general case where the users are coupled by concave interference functions. This corresponds to a system with adaptive receive strategies which minimize the interference received by each user. A necessary and sufficient condition for feasibility is obtained by minimizing the Perron root over the set of possible receive strategies. This type of problem is directly related to the problem of (weighted) max-min-SIR balancing. This paper provides an analytical framework and an iterative algorithm that converges monotonically to a global optimum. We also study an alternative approach based on a fixed point iteration. This iteration is shown to converge to the global optimum if the SIR targets lie on the boundary of the region. [ABSTRACT FROM AUTHOR]

Most reported compensation schemes for active electromagnetic interference filters (AEFs) use either voltage canceling or current canceling to deal with high-frequency noise interference. The purpose of this paper is to investigate the compensation characteristics of these two kinds of AEFs for different types of noise sources, i.e., common mode (CM) and differential mode (DM) noise source. This is examined by experimental identification and theoretical analysis of the insertion losses of AEF with voltage- or current-cancellation scheme. It is demonstrated that current-canceling AEFs are effective in eliminating high-impedance CM noise, while voltage-canceling AEFs are good compensation solutions for low-impedance DM noise. The results reported in the paper enable the choice of optimized compensation schemes, using the aforementioned indicated aspects. [ABSTRACT FROM AUTHOR]

This paper predicts programs' effect of time-domain electromagnetic interference (EM!) on a simple microcontroller. Using the instruction current concept and a modified instruction set simulator (ISS) for this purpose, this paper can predict, in the time domain, accurate conducted EM! behaviors when different programs are running on this system. Different program codes' EMI behaviors are predicted, and all of these codes fit well with the measurement results. The modified ISS is adapted to estimate the pipeline effect of a microcontroller and to give an accurate current profile of any complex multi-instruction program. By using the instruction current model and the proposed ISS, this paper can predict the EM! behavior of a very complex program-a simple home-made operating system (OS) kernel. To the best of our knowledge, this paper is the first work on observation and prediction of EM! behavior of an embedded system OS kernel. [ABSTRACT FROM AUTHOR]

The capacity region of a class of discrete memoryless interference channels with common information is established. The setup is similar to the class of deterministic interference channels without common information studied by El Gamal and Costa, which was later extended to the class of deterministic interference channels with common information. In this paper, certain conditions that were originally imposed by El Gamal and Costa are relaxed and it is shown, by a specific example, that this new class of interference channels is strictly larger than the class of deterministic interference channels previously studied. In fact, the result of this paper is obtained by combining the class of deterministic interference channels with the class of discrete memoryless interference channels with strong interference. Hence, it also includes the capacity region of the class of discrete memoryless interference channels with strong interference as a special case. [ABSTRACT FROM AUTHOR]