Recently, soft sensors have been widely adopted as alternatives to physical sensors. However, their generalization performance often degrades under distribution shifts, and their prediction errors are not directly observable without ground-truth measurements. As a result, cost-expensive sensors that consume significant energy or resources are still required in practice. To address this challenge, we study cost-efficient sensing scheduling in systems equipped with both soft and cost-expensive sensors, operating under a limited budget for activating the latter. We first develop an optimal sensing scheduling algorithm that minimizes measurement error while satisfying an average cost constraint. To enable its practical deployment, we propose a self-improving soft sensor that estimates predictive uncertainty and enhances its performance using selectively collected ground-truth measurements. We then design a cost-efficient sensing scheduling framework by integrating them. In this framework, predictive uncertainty serves as a proxy for unknown measurement errors, which provides guidance on when to activate cost-expensive sensors. Based on this guidance, the scheduling algorithm selectively acquires informative measurements that facilitate not only error reduction but also soft sensor improvement, given the limited budget. Extensive simulations on real-world datasets demonstrate that the proposed framework effectively quantifies predictive uncertainty, improves soft sensor accuracy, and significantly outperforms baseline algorithms in both error reduction and data efficiency.

Interference alignment (IA) needs multiple dimensions, which can be achieved by extending time, frequency or spatial domain. However, using time or frequency domain for alignment requires an exponential number of resources as the degrees of freedom increases. In addition, it is impractical to employ many number of antennas in the spatial-domain-based interference alignment system. In this paper, we consider MIMO-OFDM systems over K-user interference channels and present resource allocation criteria based on the IA scheme utilizing spatial and frequency domain simultaneously. Then, we propose a low complexity resource allocation scheme appropriate to both spatial and frequency domain IA. We show that a single additional subcarrier in the proposed resource allocation scheme is enough to improve the sum-rate performance close to the optimal performance.

In this paper, we consider an alternate transmission scheme for a multiple-input multiple-output interference relay channel where multiple sources transmit their own signals to their corresponding destinations via one of two relaying groups alternately every time phase. Each of the relaying groups has arbitrary number of relays, and each relay operates in half-duplex amplify-and-forward mode. In our scheme, the received signals at the relay nodes consist of desired signals and two different interference signals such as the inter-source interferences and the inter-group interferences which are caused by the phase incoherence of relaying. As such, we propose an iterative interference alignment algorithm to mitigate the interferences. We show that our proposed scheme achieves additional degrees of freedom compared to the conventional half-duplex relaying system in the interference relay channels.

For multicell environment, relays introduce additional interferences at the cell edge. To overcome such intercell interferences, we propose the alternate relay transmission schemes. We quantify the ergodic rate performance of the proposed schemes over Nakagami-m fading channel. Numerical results show that the proposed schemes can effectively cancel the inter-cell interference and improve the sum rate performance for cell edge users.

In a half-duplex relaying, the capacity pre-log factor 1/2 is a major drawback in spectral efficiency. This paper proposes a linear precoding/decoding scheme and an alternate relaying protocol in a dual-hop half-duplex system where three relays help the communication between the source and the destination. In our proposed scheme, we consider a phase incoherent method in relays in which the source alternately transmits message signals to the different relays. In addition, we propose a linear interference alignment scheme which can suppress the inter-relay interference resulting from the phase incoherence of relaying. Based on our analysis of degrees of freedom and our simulation results, we show that our proposed scheme achieves additional degrees of freedom compared to the conventional half-duplex relaying.

In wireless X networks where all transmitters send the independent messages to all receivers, the theoretical degrees of freedom (DOF) and interference alignment (IA) scheme for its achievability are given by Cadambe and Jafar. However, IA scheme for wireless X network may be infeasible in practice unless the transmitters have the perfect channel information. In addition, if the transmitter with single antenna uses time-varying channel coefficients as a beamforming vector, the infinite channel extension is required to achieve the theoretical DOF of wireless X networks with perfect IA scheme. In this paper, we consider K-user MIMO X network where K transmitters and K receivers have M antennas each. While the beamforming vectors have been constructed with multiple channel uses over multiple time slot in the earlier work, we consider the beamforming vectors constructed only by a spatial signature over unit time. Accordingly the channel information at the transmitters can be available instantaneously. Then we propose the perfect IA scheme with no channel extension. Based on our sum-rate analysis and the simulation results, we confirm that our proposed scheme can achieve MK/2 DOF which is quite close to the theoretical degrees of freedom region of wireless X networks.

We introduce places with negative holding times and tokens with negative token counts into a timed event graph in order to model and analyze time window constraints. We extend the enabling and firing rules for such an extended event graph named a negative event graph (NEG). We develop necessary and sufficient conditions based on the circuits for which the NEG is live, that is, an infinite sequence of feasible firing epochs exist for each transition. We prove that the minimum cycle time is the same as the maximum circuit ratio of the circuits with positive token counts. We also show that when there exists circuits with negative token counts, the maximum cycle time is bounded and the same as the minimum circuit ratio of such circuits. A scheduling example for a robot-based cluster tool with wafer residency time constraints for semiconductor manufacturing is explained. Note to Practitioners-Scheduling and control problems for modern man-made systems, including automated manufacturing systems such as cluster tools for semiconductor manufacturing, microcircuits, and real-time software systems, are usually modeled as discrete event systems. Such systems often have strict time constraints on timings of some events. Our results can be used for identifying whether there can be a feasible schedule that satisfies all time constraints, computing the range of the feasible cycle times, and determining a steady schedule with the minimum cycle time. By using the feasibility condition, we also can accommodate the system configuration, the task times, and the task sequence so that the system can satisfy the time constraints while meeting the target cycle time. Such practice is already used for real cluster tool engineering. We have more results on implementing a real-time scheduler and controller for time constrained systems.

In the current Internet, the quality of service of audio application is not guaranteed due to variable loss and delay. Forward error correction (FEC)-based error control mechanisms which send the redundant information with the main information can be used to minimize the effects of packet loss. However, increasing the amount of redundancy may waste bandwidth and increase the end-to-end delay. The existing FEC-based error control mechanisms select the codec combination only based on the network loss rate. These mechanisms do not consider the end-to-end delay by increasing the amount of redundancy. This may result in exceeding the acceptable maximum delay. We propose a selection mechanism of the audio codec combination for error control. In simulations, we confirm that the proposed algorithm reduces the end-to-end delay and the packet loss together.

In this paper, we propose a PPC (Populari@-based Partial Caching) scheme for continuous media objects on the proxy servers. In this scheme, either the initial portion or the entire blocks of objects are cached and the size of the initial portion of each stream varies with the popularity of that stream. Under the proposed scheme, the initial latency otherwise happens to access the requested objects from the remote server can be reduced signijlcantly and moreover, the limited cache storage space can be utilized ef~cient~. Considering the characteristics of continuous media objects, we also apply the popularity of each stream by taking the amount of the data of eac~~ stream played back by clients into consideration. As a result of trace-driven simulations with 9 days of log jiles for VOD server, which were obtained from the website http://imbc.hananet. net, we show that, PPC, our proposed caching scheme, outperforms other well-known caching schemes in hit ratios and replacement overhead.