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A path modification method using the Bézier curve is proposed to enhance pedestrian dead reckoning (PDR) information. The proposed method utilizes the encounter information between multiagents. The PDR information of an individual agent contains errors due to integration drift of the inertial sensors, and the encounter locations of multiple agents may not match. Therefore, path modification of each agent using the encounter information is required. In this study, the trajectory of a pedestrian is represented with a geometric curve, and the shape of the curve is optimized for path modification. The benefit of the proposed method lies in the ability to fuse various types of information into the algorithm to improve the performance. The optimized curve always satisfies the encounter condition, and various types of information can be considered in the optimization process. In this study, PDR information, anchor information, relative information, and heuristic information are used. The performance of the proposed method is demonstrated by simulation using indoor navigation experimental data. [ABSTRACT FROM AUTHOR]

In this article, we develop a pedestrian inertial navigation (PIN) that uses an inertial measurement unit (IMU) mounted on a shoe to locate a pedestrian in an infrastructure-free environment. In the PIN, stand-alone navigation is possible by calculating the navigation solution using the inertial navigation system (INS) mechanism. For accurate navigation, however, it is necessary to compensate for accumulated errors over time. In a foot-mounted PIN, the error can be compensated through zero-velocity (ZV) correction method by detecting the moment the foot touches the ground. One important point here is to detect ZVs accurately. In most of the literature related to this, ZV detection techniques for normal gait have been proposed. In this article, we first propose a powerful ZV detection algorithm for various gait types. This algorithm consists of a new buffering method of the sensor output power, an exact ZV detection method through glitch removal, and a reinforcement method for ZV detection based on auxiliary step detection. Second, we design a PIN/ZV integration filter, and describe the real-time operation plan of all these functions. The performance of the PIN using the proposed algorithm is verified through experiments. [ABSTRACT FROM AUTHOR]

In this letter, we consider a cognitive radio network with imperfect channel state information where secondary users transmit signals using multi-hop relaying. When the channels between secondary users are modeled as cascaded Rayleigh fading, we derive the exact outage probability of the secondary network in an analytic form and the approximate outage probability in a closed form. Then we propose a secondary user selection scheme to minimize the outage probability. The validity of our analysis is verified through simulation. [ABSTRACT FROM AUTHOR]

In this letter, we investigate cooperative device-to-device (D2D) communication in an uplink cellular network, where D2D users act as relays for cellular users. We derive the outage probability of a cellular user and the average achievable rate from a D2D transmitter to a D2D receiver in analytic form. We obtain optimal spectrum and power allocation to maximize the total average achievable rate under the outage probability constraint. The validity of the analysis is verified by computer simulations. [ABSTRACT FROM AUTHOR]

In this letter, a cooperative non-orthogonal multiple access system with imperfect successive interference cancellation is investigated in an underlay cognitive radio network. Considering that the channel coefficients between the primary source and the secondary receiving nodes follow Rayleigh distribution, we derive an exact closed form of the exact outage probability for each secondary destination. Also, asymptotic expressions for the outage probability are derived: 1) when the interference constraint goes to infinity and 2) when the transmit powers at the secondary source and relay go to infinity. The simulation results verify our analytical results. [ABSTRACT FROM AUTHOR]

In this correspondence paper, we propose a new cooperative jamming technique for an amplify-and-forward relay network with multiple relays. Also, we propose a joint power allocation and relay selection scheme for the network with the proposed technique. The secrecy outage probability of the network is derived and a joint power allocation and relay selection problem is proposed to minimize the secrecy outage probability. By using the primal decomposition method, we divide this problem into a master problem and a subproblem each of which solution is obtained. Simulation results show that the proposed scheme for the network with the proposed technique provides lower secrecy outage probability than a conventional scheme for the network with a conventional technique. [ABSTRACT FROM AUTHOR]

In this paper, we investigate underlay device-to-device (D2D) communication in cellular networks where D2D transmitters transmit data to their receivers using cellular spectrum. We analyze the average sum throughput of D2D receivers in interference-limited channels. To enhance it, we propose a semi-distributed spectrum access scheme, which consists of two stages. In the first stage, the cellular base station divides whole D2D transmitters into multiple groups and assigns a different subchannel to each group. In the second stage, D2D transmitters in each group randomly access the subchannel assigned to it with predetermined access probability. We formulate an optimization problem to find groups and access probabilities, which maximize the average sum throughput. To overcome the prohibitive computational complexity to obtain its optimal solution, we decompose it into two subproblems: one to find groups and one to find access probabilities. A heuristic grouping algorithm is adopted to solve the former, and a branch-and-bound-based algorithm is proposed to solve the latter with achieving a target accuracy. The validity of the branch-and-bound-based algorithm is shown by performance comparison with an exhaustive search. It is shown that the heuristic grouping and the branch-and-bound-based algorithm achieve higher average sum throughput than conventional methods. [ABSTRACT FROM AUTHOR]

In this letter, we investigate an underlay cognitive radio network consisting of a single-hop secondary network coexisting with a multihop primary network. In the secondary network, the secondary destination receives the same interference signals from primary terminals over different time, which are cancelled by successive interference cancellation. We analyze the outage probability of the primary network and that of the secondary network. The validity of our analysis is verified by computer simulations. [ABSTRACT FROM PUBLISHER]