This paper gives the long sought network version of water-filling named as polite water-filling.Unlike in single-user MIMO channels, where no one uses general purpose optimization algorithms in place of the simple and optimal water-filling for transmitter optimization, the traditional water-filling is generally far from optimal in networks as simple as MIMO multiaccess channels (MAC) and broadcast channels (BC), where steepest ascent algorithms have been used except for the sum-rate optimization. This is changed by the polite water-filling that is optimal for all boundary points of the capacity regions of MAC and BC and for all boundary points of a set of achievable regions of a more general class of MIMO B-MAC interference networks, which is a combination of multiple interfering broadcast channels, from the transmitter point of view, and multiaccess channels, from the receiver point of view, including MAC, BC, interference channels, X networks, and most practical wireless networks as special case. It is polite because it strikes an optimal balance between reducing interference to others and maximizing a link's own rate. Employing it, the related optimizations can be vastly simplified by taking advantage of the structure of the problems. Deeply connected to the polite water-filling, the rate duality is extended to the forward and reverse links of the B-MAC networks. As a demonstration, weighted sum-rate maximization algorithms based on polite water-filling and duality with superior performance and low complexity are designed for B-MAC networks and are analyzed for Interference Tree (iTree) Networks, a sub-class of the B-MAC networks that possesses promising properties for further information theoretic study. 5 interpretation.Directly applying single-user water-filling to networks is referred to as selfish water-filling here. It is well known to be far from optimal [26]-[28] because it does not control interference to others. Based on selfish water-filling, game-theoretic, distributed, and iterative algorithms have been well studied for DSL [26], [29]-[33], for MIMO interference channels, e.g., [34]-[37], and for multiaccess channels, e.g., [28]. The algorithms converge only under stringent conditions and the performance is not near optimal.The importance of controlling interference to others has been recognized in literature, e.g., [11],[38]- [40]. But a systematic, general, and optimal method has not been found. In interference pricing method, each user maximizes its own utility minus the interference cost determined by the interference prices. With a proper choice of the interference price which can be reverse engineered from the KKT conditions, the interference pricing based method can find a stationary point of the sum utility maximization problem. Several monotonically convergent interference pricing algorithms have been proposed in [41]-[43] for the SISO/MISO interference channels, and the MIMO interference channel with single data stream transmission. Except for the SISO case, all these algorithms update e...

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Vacuum assisted microwave curing technologies and modified optical sensing systems have been employed to investigate the influence of ply orientation and thickness on through-thickness temperature distribution of carbon fiber reinforced composite laminates. Two different types of epoxy systems have been studied. The results demonstrated that the ply orientation did not affect the temperature distribution of composite materials. However, the thickness was an important influencing factor. Nearly 10 °C temperature difference was found in 22.5mm thick laminates. Through analyzing the physical mechanisms during microwave curing, the temperature difference decreased when the heat-loss in surface laminates was reduced and the absorption of microwave energy in the center laminates was improved. The maximum temperature difference of the samples formed using themodified microwave curing technologies in this research could be reduced by 79% to 2.1 °C.Compared with the 5.29 °C temperature difference of laminates using thermal heating process, the maximum temperature difference in laminates using modified microwave curing technologies was reduced by 60%, and the curing time was cut down by 25%.

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Network slicing has been advocated by both academia and industry as a cost-efficient way to enable operators to provide networks on an as-a-service basis and meet the wide range of use cases that the fifth generation wireless network will serve. The existing works on network slicing are mainly targeted at the partition of the core network, and the prospect of network slicing in radio access networks should be jointly exploited. To solve this challenge, an enhanced network slicing in fog radio access networks (F-RANs), termed as access slicing, is proposed. This article comprehensively presents a novel architecture and related key techniques for access slicing in F-RANs. The proposed hierarchical architecture of access slicing consists of centralized orchestration layer and slice instance layer, which makes the access slicing adaptively implement in an convenient way. Meanwhile, key techniques and their corresponding solutions, including the radio and cache resource management, as well as the socialaware slicing, are presented. Open issues in terms of standardization developments and field trials are identified.

Abstract-We take two new approaches to design efficient algorithms for transmitter optimization under rate constraints in order to guarantee the Quality of Service for MIMO B-MAC interference networks. A B-MAC network is a generalized interference network that is a combination of multiple interfering broadcast channels (BC) and multiaccess channels (MAC). Two related optimization problems, maximizing the minimum of weighted rates under a sum-power constraint and minimizing the sum-power under rate constraints, are considered. The first approach takes advantage of existing algorithms for SINR problems by building a bridge between rate and SINR through the design of optimal mappings between them. The second approach exploits the polite water-filling structure, which is the network version of water-filling satisfied by all the Pareto optimal input of a large class of achievable regions of B-MAC networks. It replaces most generic optimization algorithms currently used for such networks and reduces the complexity while demonstrating superior performance even in non-convex cases. Both centralized and distributed algorithms are designed and the performance is analyzed in addition to numeric examples.Index Terms-Duality, MIMO, interference network, polite water-filling, quality of service.

Incorporating cloud computing into heterogeneous networks, the heterogeneous cloud radio access network (H-CRAN) has been proposed as a promising paradigm to enhance both spectral and energy efficiencies. Developing interference suppression strategies is critical for suppressing the inter-tier interference between remote radio heads (RRHs) and a macro base station (MBS) in H-CRANs. In this paper, inter-tier interference suppression techniques are considered in the contexts of collaborative processing and cooperative radio resource allocation (CRRA). In particular, interference collaboration (IC) and beamforming (BF) are proposed to suppress the inter-tier interference, and their corresponding performance is evaluated. Closed-form expressions for the overall outage probabilities, system capacities, and average bit error rates under these two schemes are derived. Furthermore, IC and BF based CRRA optimization models are presented to maximize the RRH-accessed users' sum rates via power allocation, which is solved with convex optimization. Simulation results demonstrate that the derived expressions for these performance metrics for IC and BF are accurate; and the relative performance between IC and BF schemes depends on system parameters, such as the number of antennas at the MBS, the number of RRHs, and the target signal-to-interference-plus-noise ratio threshold. Furthermore, it is seen that the sum rates of IC and BF schemes increase almost linearly with the transmit power threshold under the proposed CRRA optimization solution.Index Terms-Heterogeneous cloud radio access network, interference suppression, interference coordination, cooperative radio resource allocation.