Abstract-Because of the rising energy prices and environmental concerns, the calculation of energy-optimal reference trajectories for trains is significant for energy saving. On the other hand, with the development automatic train operation (ATO), the optimal trajectory planning is significant to the performance of train operation. In this paper, we present an integrated survey of this field. First, a nonlinear continuoustime train model and a continuous-space model of train operations are described, after which the optimal trajectory planning problem is formulated based on these two models. The various approaches in the literature to calculate the reference trajectory are reviewed and categorized into two groups: analytical solutions and numerical optimization. Finally, a short discussion of some open topics in the field of optimal trajectory planning for train operations are given.

No abstract

No abstract

The tradeoff between the energy efficiency (EE) and delay problem in cooperative relaying system is studied by using Non-orthogonal multiple access (NOMA) in this paper. To obtain an efficiency tradeoff between EE and delay, a stochasticbased EE optimization problem is formulated by considering the system queue stability. Then, the fractional programming and control parameter-based Lyapunov optimization method is proposed to solve the formulated problem. Furthermore, we derive the analytical bounds of EE and delay based on the control parameter. Finally, simulation results verify that the proposed cooperative NOMA system performs better than the traditional orthogonal multiple access (OMA) cooperative system. Index Terms-NOMA, cooperative relaying system, EE, delay I. Introduction NOMA technique has recently been included into the 3GPP long term evolution advanced (LTE-A) standard, owing to its enormous potential in improving system spectrum efficiency [1]. Different from the traditional OMA, the users are allowed to share the same time/frequency resource in NOMA. Meanwhile, the success interference cancellation (SIC) is applied at the receivers to reduce the co-channel interference and extract desired components from the received signals. Recently, cooperative NOMA is further proposed to improve the transmission reliability of the system, by exploiting the spatial diversity gain [2]-[6]. The power allocation strategy is optimized based on the closed form expressions for the base station's outage probability and sum rate in [2]. [3] derives the sum rate region in the cooperative NOMA system with compress-and-forward relaying by using the noisy network coding. In [4], the achievable rate is calculated approximatively through the Gauss-Chebyshev Integration method in a Rician fading channel. [5] proposes a two-stage selection strategy under different quality of services (QoSs) for the users, and then the closed-form expression of the outage probability is obtained. However, recent studies mainly focus on the rate and outage probability for the cooperative NOMA system.

No abstract

Resource allocation with sensing-based interference price is considered for multi-users cognitive radio (CR) network, in which the primary base station (PBS) controls the secondary users' (SUs) transmission by pricing the SUs' interference power. SUs firstly initiates data transmission based on the sensing decision and then PBS sets the interference price according to each SU's interference power. Stackelberg game is formulated to jointly obtain the maximum revenue for PBS and optimize the resource allocation to maximize the transmission gain for SUs. Two practical CR network models are investigated: the sensing based spectrum sharing(SBSS) and the opportunistic spectrum access(OSA). For each scenario, the resource allocation strategy is investigated under the two pricing schemes, namely uniform interference pricing and non-uniform interference pricing. Especially, the stackelberg equilibriums for the proposed games is characterized, and the distributed sensing based interference price bargaining algorithm is proposed according to different channel state information (CSI) for the non-uniform interference pricing case. Numerical examples are carried out to demonstrate the effectiveness of the proposed game algorithm under different pricing scheme. INDEX TERMS Resource allocation, Stackelberg game, cognitive radio networks, interference management. BING NING (Member, IEEE) received the B.E. degree in electronic information engineering from the Nanjing Artillery Academy of PLA, Nanjing, China, in 2009, and the Ph.D. degree in information and communication system from

Automatic Train Operation (ATO) is one of the most important functions for an advanced train control system in high-speed railway systems. Research on optimization methods for ATO has been done before it is implemented in a train control system. From a theoretical point of view, it can be formulated as one of the functions of multi-objective Optimal Control Theory. This paper presents a new multi-objective optimization method for an ATO system using Cellular Automata (CA). A CA model for an ATO system is applied to simulate train operation. An optimal method for ATO is proposed. Compared with actual train operation results, the control algorithm can reduce energy consumption and ensure train operation safety such as higher accuracy of train stop. Therefore, it can improve the efficiency and safety of the train operation.

Train-ground communication technology is one of the key technologies for communication-based train control (CBTC), which is an automated train control system for railways that ensures safe operation of rail vehicles using data communications. In CBTC systems, less service availability could cause train derailment, collision or even catastrophic loss of lives or assets. Therefore, the availability of train-ground communication should be carefully considered in designing CBTC systems. In this paper, we propose two WLAN-based trainground communication schemes with redundancy to improve the availability in CBTC systems. The availability is analyzed using continuous time Markov chain (CTMC) model. Numerical examples illustrate that the proposed schemes with redundancy can significantly improve the availability of WLAN-based trainground communication in CBTC systems.