Weak Interference Research Articles

Capacity Bounds and Sum Rate Capacities of a Class of Discrete Memoryless Interference Channels

This paper studies the capacity of a class of discrete memoryless interference channels (DMICs), where interference is defined analogous to that of a Gaussian interference channel with one-sided weak interference. The sum-rate capacity of this class of channels is determined. As with the Gaussian case, the sum-rate capacity is achieved by letting the transceiver pair subject to interference communicate at a rate such that its message can be decoded at the unintended receiver using single user detection. It is also established that this class of DMICs is equivalent in capacity region to certain degraded interference channels. This allows the construction of capacity outer-bounds using the capacity regions of associated degraded broadcast channels. The same technique is then used to determine the sum-rate capacity of DMICs with mixed interference as defined in this paper. The obtained capacity bounds and sum-rate capacities are used to resolve the capacities of several new DMICs.

Sensitive detection of CO2 concentration and temperature for hot gases using quantum-cascade laser absorption spectroscopy near 4.2 μm

Mid-infrared quantum-cascade laser (QCL) absorption spectroscopy of CO2 near 4.2 mu m has been developed for measurement of temperature and concentration in hot gases. With stronger absorption line-strengths than transitions near 1.5, 2.0, and 2.7 mu m used previously, the fundamental band (00(0)1-00(0)0) of CO2 near 4.2 mu m provides greatly enhanced sensitivity and accuracy to sense CO2 in high-temperature gases. Line R(74) and line R(96) are chosen as optimum pair for sensitive temperature measurements due to their high-temperature sensitivity, equal signal-to-noise ratio (SNR), weak interference of H2O transitions, as well as relatively strong line-strengths in high temperature and weak absorption in room temperature. The high-resolution absorption spectrum of the far wings of the R-branch (R56-R100) in the fundamental vibrational band of CO2 is measured in a heated cell over the range 2,384-2,396 cm(-1) at different temperatures from 700 to 1,200 K. Taking three factors into consideration, including SNR, concentration detectability, and uncertainty sensitivity, the absorption line R(74) is selected to calculate CO2 concentration. The tunable QCL absorption sensor is validated in mixtures of CO2 and N-2 in a static cell for temperature range of 700-1,200 K, achieving an accuracy of +/- 6 K for temperature and +/- 5 % for concentration measurements.

Foundations and applications of weak quantum measurements

Following earlier applications of weak measurement to new cases (Part I), we proceed to explore its temporal peculiarities. We analyze an idealized experiment in which weak which-path measurements do not prevent consecutive weak interference effects, and then again the which-path information is recovered by strong measurements. We also show how the same effect can be obtained even by all these measurements being carried out on a single particle. The simplified setting enables critically assessing competing interpretations of the results. The most natural one is that of the Two-State-Vector Formalism, according to which the quantum "two-state" between an earlier and a later measurement is equally determined by both of them.

Laser induced microwave oscillator under the influence of interference

An optoelectronic oscillator (OEO) under the influence of a weak interference has been investigated. The system equation of the OEO under the influence of interference has been derived. A novel technique for calculating the lock range of the oscillator using the harmonic balance method in presence of interference has been demonstrated. Theoretical analysis coupled with experimental results has been presented.

A cataluminescence sensor for propionaldehyde based on the use of nanosized zirconium dioxide

A sensor is described for the detection of propionaldehyde in the gas phase. The sensing scheme is based on the blue cataluminescence (CTL) emission that results from the catalytic oxidation of propionaldehyde on the surface of nanosized zirconium dioxide. The sensor displays high sensitivity to propionaldehyde, a response time of 3 s, and a recovery time of 8 s. Under optimized conditions, the intensity of CTL is linearly related to the concentration of propionaldehyde in the 2.5–1,300 mg·m−3 concentration range, with a limit of detection of 0.6 mg·m−3 (at an SNR of 3) and a relative standard deviation (for n = 6) of 2.2 % at a level of 80 mg·m−3 of propionaldehyde. Relatively weak interference is observed for ethanol, acetone and acetaldehyde. The method was applied to analyze environmental air samples containing propionaldehyde, and data were compared with those obtained by GC-MS. The results were in good agreement, thereby indicating the utility of the sensor for routine monitoring. A possible mechanism for the catalytic oxidation of propionaldehyde on the ZrO2 surface is discussed on the basis of the chromatograms of the reaction products.

Approximate Sum-Capacity of K-user Cognitive Interference Channels with Cumulative Message Sharing

This paper considers the K-user cognitive interference channel with one primary and K-1 secondary/cognitive transmitters with a cumulative message sharing structure, i.e., cognitive transmitter i ϵ [2 : K] has non-causal knowledge of the messages of users with index less than i. A computable outer bound valid for any memoryless channel is proposed. The sum-rate outer bound is evaluated first for the high-SNR linear deterministic approximation of the Gaussian noise channel. This is shown to be both the sum capacity for the 3-user channel with arbitrary channel gains, and the sum-capacity for the symmetric K-user channel. Interestingly, for the K user channel, cognition at transmitters 2 to K-1 is not needed, and knowledge of all messages at the K-th transmitter only is sufficient to achieve the sum-capacity. Next, the sum-capacity of the symmetric Gaussian noise channel is characterized to within a constant additive and multiplicative gap, both of which are functions of K. As opposed to other multiuser interference channel models, a single scheme (in this case based on dirty-paper coding) suffices for both the weak and strong interference regimes. The generalized degrees of freedom (gDoF) are then derived and are shown, unlike interference and broadcast channels, to be a function of K. Interestingly, it is shown that as the number of users grows to infinity the gDoF of the K-user cognitive interference channel with cumulative message sharing tends to the gDoF of a broadcast channel with a K-antenna transmitter and K single-antenna receivers. Finally, numerical evaluations show that the actual gaps between the presented inner and outer bounds are significantly smaller than the analytically derived gaps.

Multi-channel power allocation based on market competitive equilibrium in cognitive radio networks

Cognitive radios such as intelligent phones and Bluetooth devices have been considered essential goods in next-generation communication systems. Such devices will have to share the same frequency band owing to the limited bandwidth resource. To improve spectrum efficiency, we formulate multi-channel power allocation as a market competitive equilibrium (CE) problem, and prove that its solution exists and is unique under the condition of weak interference. We then propose two distributed power allocation algorithms achieving CE, namely the fast convergent power allocation algorithm (FCPAA) and the social-fairness-aware FCPAA (SFAF). Theoretical analysis and simulation results demonstrate that the proposed algorithms lead to better system performance in terms of the guaranteed interference temperature constraint using the price mechanism instead of a strategy based on the Nash equilibrium. Moreover, it is shown that the FCPAA maximizes total utility, and converges more quickly than the method addressed in prior research with the help of improved round-robin rules. However, the FCPAA cannot ensure the same social fairness among secondary users as the SFAF scheme in both the non-fading channel and Rayleigh fading channel; the SFAF balances the individual utility by adjusting each user’s budget at the expense of a small quantity of system total throughput.

Dynamic Hierarchical Power Control in Multi-User Cognitive Wi-Fi 2.0 Wireless Networks

具有认知性、自主性和适变性等特点的认知Wi-Fi 2.0 无线网络技术,作为提高无线网络容量的重要技术不断引起学术界、标准组织和工业界的关注.针对现有功率控制技术不能刻画多个认知节点存在分层决策的现象,提出一种认知Wi-Fi 2.0 无线网络中多用户动态分层功率控制算法.基于提出的斯坦科尔伯格(Stackelberg)容量最大化博弈模型,为认知Wi-Fi 2.0 无线网络中感知信息不对称的多用户分别设计了分布式功率控制方法,实现领导者用户和跟随者用户的多阶段动态交互在保证个体效用的同时实现网络整体性能.该算法根据当前认知Wi-Fi 2.0 无线网络中多个认知节点接入频谱顺序的不同,确定领导者用户和跟随者用户;然后,对于领导者和跟随者分别采用不同的功率控制策略,并多次交互实现多用户分层算法的动态交互收敛.蒙特卡洛仿真验证了算法的有效性.;Cognitive Wi-Fi 2.0 wireless networks with the typical characteristics of cognition, reconfirmation and self-organizing abilities as the novel open spectrum sharing technology, that are used to improve the network performance, have promisingly captured a great attention from the wireless community. In this paper, to capture the hierarchical decision-making properties of the power control, the study proposes a dynamic hierarchical power control for the cognitive Wi-Fi 2.0 wireless networks. The spectrum sharing issue is formulated as the Stackelberg game with the more foresighted cognitive users as the leaders and short-sighted users as follower, and the paper derives the closed-form power policy, respectively. Meanwhile, the study concludes that this policy can achieve the optimal performance in the weak interference environment after analysis. Simulations results show that the proposed algorithm converges after limited iterations, which also effectively guarantees the optimal trade-off between the individual performance and the network overall performance.

New Achievable Rates for Gaussian Partially Cognitive Interference Channels With Multiple Cognitive Pairs

This paper characterizes achievable rate regions for the Gaussian partially cognitive interference channel with multiple cognitive pairs (K-PCIFC), where the cognitive transmitters know one part of the primary transmitter's message. We explore a novel methodology using the deterministic discrete superposition model (DSM). We find codes and their achievable rate regions in the DSM, and we show that they yield achievable rate regions in the Gaussian model. Our coding scheme in the DSM can be applied in general scenarios. We devise an achievable rate region for the K-PCIFC, which is within a constant gap to known outer bounds for K = 2 in the weak interference regime. From our expressions we derive guidelines for designing the cognitive link between the primary transmitter and the cognitive transmitters. Furthermore, we show that the gain from cognition diminishes for increasing K.

Implementation and Experiments of TDOA Monitoring Techniques for Broadcasting Interferences

Since the rapid developing of economy in Taiwan in recently years, a large numbers of constructions have made the changes on theterrain surrounding of the radio monitoring stations rapidly. Hence, the accuracy performance of the radio monitoring station configured by signal angle of arrival (AOA) location technology has been seriously degraded. In this paper, the simulated result of 20km ~ 30km coverage area is evaluated. Furthermore, the implementation and experiments supported by the radio frequency interference have been governed by authority of national communication commissions (NCC) in Taiwan. The results show that the locating accuracy at circle error probability (CEP) 50% is less than 950 m distance under multi-path effect in metropolitan area. Hence, the solution of integrated the AOA/TDOA technologies can be applied and the interference transmitter characterized with low transmitted power, burst and weak signal and metropolitan interference is easy identified, analyzed (located) and prevented.

Genome Analyses of Single Human Oocytes

Single-cell genome analyses of human oocytes are important for meiosis research and preimplantation genomic screening. However, the nonuniformity of single-cell whole-genome amplification hindered its use. Here, we demonstrate genome analyses of single human oocytes using multiple annealing and looping-based amplification cycle (MALBAC)-based sequencing technology. By sequencing the triads of the first and second polar bodies (PB1 and PB2) and the oocyte pronuclei from same female egg donors, we phase the genomes of these donors with detected SNPs and determine the crossover maps of their oocytes. Our data exhibit an expected crossover interference and indicate a weak chromatid interference. Further, the genome of the oocyte pronucleus, including information regarding aneuploidy and SNPs in disease-associated alleles, can be accurately deduced from the genomes of PB1 and PB2. The MALBAC-based preimplantation genomic screening in in vitro fertilization (IVF) enables accurate and cost-effective selection of normal fertilized eggs for embryo transfer.

Research on Achievable Rate of Interference Channel with Cooperative Transmission

This paper studies the achievable data rate of the two-transmitter and two-receiver interference channel model with cooperative transmission. To implement the cooperation, a finite rate conferencing link is deployed at the transmitters side in order to share the message. A new transmit scheme with private message sharing is proposed based on the dirty paper coding. The achievable rate region is established in both strong interference regime and weak interference regime. In weak interference regime, the asymptotically rate region shows the conferencing link can improve the achievable rate region for cooperative receiver. In strong interference regime, the conferencing link not only improves the achievable rate for cooperative receiver but also improves the sum rate of the cooperative network. Numerical results demonstrate these theories in a Gaussian interference channel.

CoBRA: Cooperative Beamforming-Based Resource Allocation for Self-Healing in SON-Based Indoor Mobile Communication System

For the purpose of automating network management, self-organizing network (SON) technology is currently being investigated. There are three important issues in SON: self-configuration, self-optimization, and self-healing. This paper focuses on self-healing, in order to resolve the problem of unexpected network faults and improve network throughput simultaneously. To deal with this problem, we propose a healing channel selection and a cooperative beamforming-based iterative resource allocation algorithms. We utilize the cooperative beamforming in the healing channel based on phase pre-adjustment, and this cooperative beamforming can be performed without power cooperation between distributed nodes. Moreover, we derive the sub-optimality and convergence of the proposed algorithm in weak interference condition by using contraction mapping. Finally, simulation results demonstrate that the proposed algorithm improves average cell capacity and user fairness while repairing network failure effectively.

Capacity of All Nine Models of Channel Output Feedback for the Two-User Interference Channel

In this paper, we study the impact of different channel output feedback architectures on the capacity of the two-user interference channel. For a two-user interference channel, a feedback link can exist between receivers and transmitters in nine canonical architectures (see Fig. 3 ), ranging from only one feedback link to four feedback links. We derive the exact capacity region for the symmetric deterministic interference channel and the constant-gap capacity region for the symmetric Gaussian interference channel for all of the nine architectures. We show that for a linear deterministic symmetric interference channel, in the weak interference regime, all models of feedback, except the one, which has only one of the receivers feeding back to its own transmitter, have the identical capacity region. When only one of the receivers feeds back to its own transmitter, the capacity region is a strict subset of the capacity region of the rest of the feedback models in the weak interference regime. However, the sum-capacity of all feedback models is identical in the weak interference regime. Moreover, in the strong interference regime, all models of feedback with at least one of the receivers feeding back to its own transmitter have the identical sum-capacity. For the Gaussian interference channel, the results of the linear deterministic model follow, where capacity is replaced with approximate capacity.

Analysis of Compounds That Interfere with Herpes Simplex Virus–Host Receptor Interactions Using Surface Plasmon Resonance

The entry of herpes simplex virus into host cells involves a complex series of events that require concerted inputs from multiple HSV glycoproteins. Among these glycoproteins, the gD protein of HSV-1 and HSV-2 plays an important role for host receptor binding and membrane fusion. In the present study, we evaluated the ability of different sulfated saccharides to interfere with gD-host receptor (HVEM) interactions using our recently reported molecular assay (Gopinath, S. C. B.; Hayashi, K.; Kumar, P. K. R. J. Virol. 2012, 86, 6732-6744). Initially, we tested the ability of heparan sulfate to interfere with the HVEM-HSV-1 gD interaction and found that heparan sulfate is able to interfere efficiently, with an apparent EC50 of 2.1 μM. In addition, we tested different synthetic sulfated polysaccharides and natural sulfated polysaccharides from an edible alga, Sargassum horneri , after fractionation into different sizes and sulfate and uronic acid contents. Six polysaccharides isolated from S. horneri were found to efficiently interfere with the HVEM-gD interaction. Three others caused moderate interference, and five caused weak interference. These results were confirmed with plaque assays, and good agreement was found with the results of the SPR assay for the identification of compounds that interfere with HVEM-HSV-1 gD binding. These studies suggest that our molecular assay based on surface plasmon resonance is not only useful for the analysis of viral-host protein interactions but is also applicable for the routine screening of compounds to identify those that interfere with the first step of viral entry, thus facilitating the rapid development of novel antiviral compounds that target HSV.

Capacity region of a class of Gaussian cognitive degraded broadcast channel

This paper studies the cognitive broadcast channel in which the primary user communicates to the primary receiver, while the secondary user has noncausal knowledge of the primary radio's codeword and expects to communicate to two secondary receivers. Comparing with the existing cognitive radio channel which considers only one secondary receiver, cognitive broadcast channel studies the case that there are multiple secondary receivers. To this end, we investigate the fundamental limits of the performance of the Gaussian cognitive broadcast channel from the information theoretic perspective. Specifically, we derive the capacity region of the Gaussian cognitive degraded broadcast channel with weak interference.

Two-Way Networks: When Adaptation is Useless

Most wireless communication networks are two-way, where nodes act as both sources and destinations of messages. This allows for adaptation at or interaction between the nodes-a node's channel inputs may be functions of its message(s) and previously received signals allowing for potentially larger rates than those achievable in feedback-free one-way channels where inputs are functions of messages only. However, examples exist of channels where adaptation is not beneficial from a capacity perspective. We ask whether analogous results hold for several multiuser two-way networks. We first consider deterministic two-way channel models: the binary modulo-2 addition channel and a generalization of this, and the linear deterministic channel, which models Gaussian channels at high SNR. For these deterministic models, we obtain the capacity region for the two-way multiple access/broadcast channel (MAC/BC), the two-way Z channel, and the two-way interference channel (under certain partial adaptation constraints in some regimes). We permit all nodes to adapt their channel inputs to past outputs (except for portions of the linear high-SNR two-way interference channel where we only permit two of the four nodes to fully adapt). However, we show that the two-way fully or partially adaptive capacity region consists of two parallel one-way regions operating simultaneously in opposite directions, i.e., adaptation is useless. We next consider two noisy channel models: 1) the Gaussian two-way MAC/BC, where we show that adaptation can at most increase the sum-rate by (1/2) bit in each direction and 2) the two-way interference channel, where partial adaptation is shown to be useless when the interference is very strong. In the strong and weak interference regimes, we show that the nonadaptive Han and Kobayashi scheme utilized in parallel in both directions achieves to within a constant gap for the symmetric rate of the fully (for some regimes) or partially (for the remaining regimes) adaptive models. The central technical contribution is the derivation of new, computable outer bounds which allow for adaptation.

Determination of Dimethyl Ether in Air by Cataluminescence-Based Gas Sensor

A rapid and sensitive cataluminescence-based gas sensor utilizing nanosized Y2MnO5as the sensing materials for determining dimethyl ether in air was proposed. The luminescence characteristics and the optimal conditions were investigated in detail. The gas sensor showed high selectivity for dimethyl ether at 620 nm and satisfying activity at 210°C under the optimized conditions. The linear range of cataluminescence intensity versus concentration of dimethyl ether was 5~120 mg/m3, and the detection limit (3σ) was 3 mg/m3. No or weak interference was observed while the foreign substances, such as formaldehyde, ammonia, ethanol, benzene, carbon monoxide and sulfur dioxide, were passing through the sensor under selected conditions. The gas sensor displayed good stability for continuously introducing dimethyl ether over 100 h, and allowed real-time monitoring of dimethyl ether in air.

Gaussian Interference Channel with State Information

In this paper, we study the state-dependent two-user Gaussian interference channel, where the Gaussian distributed state information is non-causally known at both transmitters but known to neither of the receivers. We apply the simultaneous encoding scheme and propose an active interference cancellation mechanism, which is a generalized dirty-paper coding technique, to partially eliminate the state effect at the receivers. The corresponding achievable rate region is then derived. We also propose several heuristic schemes for some special cases: the strong interference case, the mixed interference case, and the weak interference case. For the strong and mixed interference cases, numerical results are provided to show that active interference cancellation significantly enlarges the achievable rate region. For the weak interference case, flexible power splitting instead of active interference cancellation improves the performance significantly.

Analysis of Capacity Bound on Two-User Transmitter Preprocessing Weak Interference MIMO Channels

In information theory (IT), it is an open problem for thirty years to establish an entire capacity bound of two-user Gaussian weak interference network. Under the assumption that channel situation information (CSI) is known at transmitter, we analyze the effects of three methods of transmitter preprocessing on performance of weak interference MIMO channels. Due to treat weak interference as noise, the bounds on the capacity region of two-user Gaussian weak interference channels (ICs) with the three transmitter preprocessing methods are derived. Compared with the performance without transmitter preprocessing, the sum rate in our system is larger. Finally the simulation results are proposed to be consistent with the theorem.