Cooperative spectrum sensing is a promising technique in cognitive radio networks by exploiting multi-user diversity to mitigate channel fading. Cooperative sensing is traditionally employed to improve the sensing accuracy while the sensing efficiency has been largely ignored. However, both sensing accuracy and efficiency have very significant impacts on the overall system performance. In this article, we first identify the fundamental trade-off between sensing accuracy and efficiency in spectrum sensing in cognitive radio networks. Then, we present several different cooperation mechanisms, including sequential, full-parallel, semi-parallel, synchronous, and asynchronous cooperative sensing schemes. The proposed cooperation mechanisms and the sensing accuracy-efficiency trade-off in these schemes are elaborated and analyzed with respect to a new performance metric achievable throughput, which simultaneously considers both transmission gain and sensing overhead. Illustrative results indicate that parallel and asynchronous cooperation strategies are able to achieve much higher performance, compared to existing and traditional cooperative spectrum sensing in cognitive radio networks.

In modern smart grid networks, the traditional power grid is empowered by technological advances in sensing, measurement, and control devices with two-way communications between the suppliers and consumers. The smart grid integration helps the power grid networks to be smarter, but it also increases the risk of attacks because of the existing obsolete cyber-infrastructure. In this article, we focus on bad data injection attacks for smart grid. The basic problem formulation is presented, and the special type of stealth attack is discussed. Then we investigate the strategies of defenders and attackers, respectively. Specifically, from the defender's perspective, an adaptive cumulative sum test is able to determine the possible existence of adversaries at the control center as quickly as possible. From the attacker's point of view, independent component analysis is employed for the attackers to make inferences through phasor observations without prior knowledge of the power grid topology. The inferred structural information can then be used to launch stealth attacks.

Intercell interference management has become a critical issue for future cellular mobile systems. Coordinated multipoint transmission/reception, or CoMP, is an effective way of managing intercell interference, and has been regarded as a key technology of LTE-Advanced. This article first provides an overview of downlink CoMP techniques specified in 3GPP LTE Rel-11, which mainly focuses on transmission schemes, channel state information reporting, interference measurement, and reference signal design. Then uplink CoMP is discussed in brief as most of the coordination gain can be achieved by implementation with little standardization support. Evaluation results are provided to show the efficiency of CoMP. The challenges as well as possible solutions for future CoMP standardization are also discussed.

As the current power grid system is upgrading to the smart grid, it becomes more vulnerable to security attacks on its communication subsystem such as the denial-of-service attack. Jamming, as a kind of denial-of service attack, can be applied to interfere the real-time communication in smart grid. In this paper, we analyze the scenario in which the attacker can jam a reduced number of signal channels carrying measurement information in order to manipulate the locational marginal price and create the opportunity for gaining profit, and the defender is able to guarantee a limited number of channels in information delivery. Based on the electricity marketing model, we propose a multiact dynamic game between the attacker and defender, in which the optimal strategies are taken by the two sides to maximize their own profits. We study the gaming process and discuss the prosperities of the outcome. Simulation results present the affect of jamming attack on the electricity prices and the gained profits of the two sides. Moreover, they confirm the optimality of the proposed scheme in pursuing profit.

It has been well recognized that channel state information (CSI) feedback is of great importance for downlink transmissions of closed-loop wireless networks. However, the existing work typically researched the CSI feedback problem for each individual mobile station (MS), and thus, cannot efficiently model the interactions among self-interested mobile users in the network level. To this end, in this paper, we propose an alternative approach to investigate the CSI feedback-rate control problem in the analytical setting of a game theoretic framework, in which a multiple-antenna base station (BS) communicates with a number of co-channel MSs through linear precoder. Specifically, we first present a non-cooperative feedback-rate control game (NFC), in which each MS selects the feedback-rate to maximize its performance in a distributed way. To improve efficiency from a social optimum point of view, we then introduce pricing, called the non-cooperative feedback-rate control game with price (NFCP). The game utility is defined as the performance gain by CSI feedback minus the price as a linear function of the CSI feedback-rate. The existence of the Nash equilibrium of such games is investigated, and two types of feedback protocols (FDMA and CSMA) are studied. Simulation results show that by adjusting the pricing factor, the distributed NFCP game results in close optimal performance compared with that of the centralized scheme.