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The next generation wireless network is expected to connect billions of nodes, which brings up the bottleneck on the communication speed for distributed data fusion. To overcome this challenge, computation over multiple access channel (CoMAC) was recently developed to compute the desired functions with a summation structure (e.g., mean, norm, etc.) by using the superposition property of wireless channels. This work aims to maximize the achievable function rate of reliable CoMAC in wireless networks. More specifically, considering channel fading and transceiver design, we derive the achievable function rate adopting the quantization and the nested lattice coding, which is determined by the number of nodes, the maximum value of messages and the quantization error threshold. Based on the derived result, the transceiver design is optimized to maximize the achievable function rate of the network. We first study a single cluster network without inter-cluster interference (ICI). Then, a multi-cluster network is further analyzed in which the clusters work in the same channel with ICI. In order to avoid the global channel state information (CSI) aggregation during the optimization, a low-complexity signaling procedure irrelevant with the number of nodes is proposed utilizing the channel reciprocity and the defined effective CSI. [ABSTRACT FROM AUTHOR]

To accommodate the dramatically increasing traffic demand, some of the intermediate nodes within HetNets should be endowed with storage and computation capabilities for facilitating pervasive computation service and massive content delivery. ICN and MEC are recognized as two promising techniques, with which content can be cached and computed in close proximity to mobile devices. These advanced techniques enable Het- Nets to accommodate and support more mobile users, but also bring challenges of architecture deployment and resource deployment. Along these lines, the fist part of this article offers a novel joint architecture of communications, caching, and computing for HetNets based on wireless network virtualization with software defined networking, where ICN and MEC support each other to promote network performance and guarantee different types of business demands. Based on the integrated framework, we further present two different self-enforcing mechanisms (i.e., a caching-assisted MEC approach and a computing-assisted ICN approach) to achieve mutual promotion between caching and computing. Against this background, the second part of this article offers virtual multi-resource deployment for both uplink and downlink scenarios to evaluate a three-way trade-off among communication, caching, and computing revenues. The results demonstrate our hypothesis on the utilization of the mutual promotion between ICN and MEC to improve the overall performance of future wireless systems. [ABSTRACT FROM AUTHOR]

The explosively growing demands for mobile traffic services bring both challenges and opportunities to wireless networks. Wireless network virtualization is proposed as the main evolution path toward the forthcoming fifth generation (5G) cellular networks. In this paper, we propose a software defined and virtualized (SDV) wireless network architecture for enabling multi-flow transmission with multiple infrastructure providers (InPs) and multiple mobile virtual network operators (MVNOs). In order to ensure the heterogeneity, we formulate the virtual resource allocation problem with diverse QoS requirements as a social welfare maximization problem with distance-related transaction cost. Due to hidden information of InPs and MVNOs for the auctioneer, we introduce a shadow price for ensuring desirable economic properties and total welfare for the system. Simulations are conducted with different system configurations to show the effectiveness and the energy efficiency performance of the proposed SDV wireless network framework and iterative double auction mechanism. [ABSTRACT FROM PUBLISHER]

In existing urban rail transit systems, the train-ground communication system for different subsystems is deployed independently. Investing and constructing the communication infrastructures repeatedly not only wastes substantial social resources, but it also is difficult to maintain all these infrastructures. In this paper, we propose an integrated train-ground communication system based on wireless network virtualization for urban rail transit systems. In order to improve the communication-based train control (CBTC) subsystem performance during handoff, we propose a novel handoff scheme to support handoff between virtual networks. The application-layer quality-of-service (QoS) parameters of the CBTC, passenger information system, and closed circuit television subsystems are used as the performance measures in the handoff design. We then formulate the QoS optimization problem in the proposed integrated train-ground communication system as an approximate dynamic programming (ADP) problem. The extensive simulation results show that the proposed integrated train-ground communication system QoS can be improved substantially with our ADP-based optimization model. [ABSTRACT FROM PUBLISHER]

Communication-based train control (CBTC) systems use wireless local area networks for information transmission between trains and wayside equipment. Since inevitable packet delay and drop are introduced in train–wayside communications, information uncertainties in trains' states will lead to unplanned traction/braking demands, as well as waste in electrical energy. Moreover, with the introduction of regenerative braking technology, power grids in CBTC systems are evolving to smart grids, and cost-aware power management should be employed to reduce the total financial cost of consumed electrical energy. In this paper, a cognitive control method for CBTC systems with smart grids is presented to enhance both train operation performance and cost efficiency. We formulate a cognitive control system model for CBTC systems. The information gap in cognitive control is calculated to analyze how the train–wayside communications affect the operation of trains. The Q-learning algorithm is used in the proposed cognitive control method, and a joint objective function composed of the information gap and the total financial cost is applied to generate optimal policy. The medium-access control layer retry-limit adaption and traction strategy selection are adopted as cognitive actions. Extensive simulation results show that the cost efficiency and train operation performance of CBTC systems are substantially improved using our proposed cognitive control method. [ABSTRACT FROM PUBLISHER]

The article discusses challenges of proposing a novel framework which jointly considers networking, caching, and computing techniques in a systematic way to support energy-efficient information retrieval and computing services in green wireless networks. It also highlights advances in networking, caching and computing for development of green wireless networks.

Designing a train control system over wireless train-wayside communications is a challenging task due to the packet delay and loss caused by unreliable wireless communications. In this paper, we study the performance optimization issues in communication-based train control (CBTC) systems with both packet delay and loss introduced by random transmission errors and frequent handoffs in train-wayside communications. A networked control system (NCS) model is formulated for multitrain CBTC systems with packet delay and loss. Then, we propose a novel train control scheme to enhance the quality of service (QoS) of CBTC systems. In the proposed scheme, medium-access control layer retry limit adaption is used to minimize the energy consumption, and guidance trajectory update is used to mitigate the trip time tracking errors. Extensive simulation results show that the QoS of CBTC systems can be substantially improved in the proposed scheme. The energy consumption and trip time error can be reduced in both static and time-varying wireless environments. [ABSTRACT FROM PUBLISHER]

Communication-based train control (CBTC) systems use wireless local area networks (WLANs) to transmit train status and control commands. Since WLANs are not originally designed for applications with high mobility, random transmission delays and packet drops are inevitable, which could result in unnecessary traction, brakes or even emergency brakes of trains, loss of line capacity, and passenger satisfaction. In this paper, we study the packet drops introduced by random transmission errors and handovers in CBTC systems, analyze the impact of random packet drops on the stability and performances of CBTC systems, and propose two novel schemes to improve the performances of CBTC systems. Unlike the existing works that only consider a single train and study the communication issues and train control issues separately, we model the system to control a group of trains as a networked control system (NCS) with packet drops in transmissions. Extensive field test and simulation results are presented. We show that our proposed schemes can provide less energy consumption, better riding comfortability, and higher line capacity compared with the existing scheme. [ABSTRACT FROM PUBLISHER]