WITH the worldwide growth in the adoption of smartphones and tablets, access to Internet video and video applications from mobile devices is projected to grow very significantly . When Internet video is accessed by a mobile device, the video must be Video-Aware Scheduling and Caching in the Radio fetched from the servers of a Content Delivery Network (CDN) . CDNs help reduce Internet bandwidth consumption and associated delay/jitter, but the video must additionally travel through the wireless carrier Core Network (CN) and Radio Access Network (RAN) before reaching the mobile device. Video-Aware Scheduling and Caching in the Radio Besides adding to video latency, bringing each requested video from the Internet CDNs can put significant strain on the carrier’s CN and RAN backhaul, leading to congestion, significant delay, and constraint on the network’s capacity to serve a large number of concurrent video requests. The above problem will be further exacerbated by the recent advances in radio technologies and architectures like LTE, LTE Advanced, small cells, and Het Nets, which will increase the radio access capacities very significantly, shifting the capacity challenge and congestion problem to RAN backhaul. Video-Aware Scheduling and Caching in the Radio According to Juniper Research, operatorswill need to spend almost $840 billion globally over the next five years in order to address serious bottlenecks in their RAN backhaul networks. According to a report just released by Strategy Analytics , “as global mobile data traffic grows by another 5 to 6 times over the next five years operators will face a new mobile capacity crunch by 2017 unless they increase traditional backhaul investment levels to match the anticipated growth in Radio Access Networks (RAN) capacity and user traffic.” According to the Video-Aware Scheduling and Caching in the Radio report, there will be potentially a 16-PB shortfall in backhaul capacity by 2017. To facilitate the tremendous growth of mobile video consumption without the associated problems of congestion, delay, and lack of capacity, in this paper we introduce caching of videos at (e)NodeBs at the edge of the RAN, shown in Fig. 1, so that most video requests can be served from the RAN caches, instead of having to be fetched from the Internet CDNs and travel through the RAN backhaul. Video-Aware Scheduling and Caching in the Radio In order to address end-to-end video capacity of the network, we also propose a video-aware wireless channel scheduler that will maximize the number of videos that can be delivered through the wireless channel, conscious of the channel conditions and the QoE needs of the videos.

THE MODERN complex network systems, including communication network, social network and smart grid, have become a key focus of security analysis nowadays. With increasing interconnection of local networks, growing communication traffic and user demand, Integrated Security Analysis on Cascading Failure in Complex Networks as well as diversifying services and emerging new technologies, the complex systems are becoming increasingly sophisticated to operate coordinately. One of many threats posed to complex network systems due to the large scale inter-connectivity is the cascading failure. Integrated Security Analysis on Cascading Failure in Complex Networks A small contingency or failure could trigger a series of chain effects across the entire system, causing a massive impact to the network operation and services . A notable case of cascading failure threats has been witnessed in power infrastructure, where blackouts, or large scale outages due to failure propagation, have affected millions of people after some disastrous cascading failures . As a practical complex network system with unique physical properties affecting Integrated Security Analysis on Cascading Failure in Complex Networks cascading failures, the electrical power infrastructure is chosen as a study case for the integrated security analysis of cascading failure against malicious attacks in this paper. It is notable that the threat of cascading failures, which is usually caused by extreme random events in the past, can be intensified by the growing integration and utilization of computer-based control and communication networks. While development of automation and intelligence brings significant benefits to the complex systems and networks, e.g. the Internet, social and business networks, and power grids alike, it is inevitable that this upgrade also comes with growing risks and complexity of cyber-security issues. Integrated Security Analysis on Cascading Failure in Complex Networks Take the future intelligent power infrastructure, i.e. the Smart Grid, as an example: studies have put forward the fact that intelligence will bring new security challenges to the power grid, a gigantic system that already yields inherent structural vulnerability of cascading failures due to its physical nature. For instance, malicious attackers can take advantage of the potential open access from smart meters in the Advanced Metering Infrastructure (AMI) to plan the attack with intelligence collected from their penetration, so that they can maximize the impact of their attacks . Integrated Security Analysis on Cascading Failure in Complex Networks Therefore, how to secure a complex network system like power grid against cascading failures has been motivating development of models and methodologies to simulate potential selective attacks that result in cascading failures in a power system with the consideration of specific network physical properties. These studies will contribute to both defensive strategies and decision supports to protect the critical components in the complex systems.

COOPERATIVE relaying is gaining a significant attention in that multiple intermediate relay nodes can collaborate with each other to enhance the overall network efficiency. It exploits the physical-layer broadcast property offered by the wireless Tradeoff Between Reliability and Security in Multiple Access Relay Networks Under Falsified Data Injection Attack medium that transmitted signals can be received and processed by any node in the neighborhood of a transmitter. The cooperative relaying approach has a great potential to provide substantial benefits in terms of reliability (diversity gain) and rate (bandwidth or spectral efficiency). These benefits can extend the coverage, reduce network energy consumption, and promote uniform energy drainage by exploiting neighbors’ resources. They can be of great value in many applications, including ad-hoc networks, mesh networks, and next generation wireless local area networks and cellular networks. In multiple access relay networks, relay nodes may combine Tradeoff Between Reliability and Security in Multiple Access Relay Networks Under Falsified Data Injection Attack the symbols received from different sources to generate parity symbols (packets) and send them to the destination. Then, the destination may use the network generated parity symbols (packets) to enhance the reliability of decoding. While this technology is promising in improving communication quality, it also presents a new challenge at the physical layer due to the dependency of the cooperation. Tradeoff Between Reliability and Security in Multiple Access Relay Networks Under Falsified Data Injection Attack That is, reliance on implicit trust relationship among participating nodes makes it more vulnerable to falsified data injection. Although this might also occur in a traditional system without cooperative communication, its effect is far more serious with cooperative communication. If a false packet is injected into the buffer of a node, the output of the node will become polluted, and this may soon propagate to the entire network. The problem of detecting malicious relay nodes in singlesource, Tradeoff Between Reliability and Security in Multiple Access Relay Networks Under Falsified Data Injection Attack multi-relay networks has been studied in the literature for different relaying strategies . Relay nodes in apply network coding while those in follow the decode-and-forward protocol. In , the authors consider a peer-to-peer (P2P) network in which peers receive and forward a linear combination of the exogenous data packets. To check the integrity of the received packets, a signature vector is generated at the source node and broadcasted Tradeoff Between Reliability and Security in Multiple Access Relay Networks Under Falsified Data Injection Attack to all nodes where it is used to check the integrity of the received packets. In , several information theoretic algorithms for mitigating falsified data injection effects are proposed. The network model used in these works is composed of a single source, multiple intermediate nodes which apply network coding.

An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks

 radio (CR) with spectrum sharing is regarded as a promising solution to enhance spectral efficiency and alleviate the issue of spectrum scarcity . On the other hand, cooperative relaying can provide remarkable performance advantages in ameliorating the An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks reliability and throughput of wireless systems. In recent years, incorporating relays into cognitive networks has received tremendous attentions, owing to its aforementioned merits. Previous related works are briefly introduced next. In , the authors proposed a novel design paradigm to maximize the cognitive user’s (CU’s) rate for MIMO CR under a minimum primary user (PU) rate constraint. and studied the performance of amplify-and-forward-based (AF-based) cognitive relay networks (CRNs) over Nakagami-m fading.

An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks Considering both high and low-to-medium signal-to-noise ratio (SNR) regimes, and derived closed-form expressions for the outage probability of an interference-limited AF-based CRN with only one PU. Further, the authors of investigated the scenario with multiple PUs. However, since the direct link between the source and destination was ignored in both, the resulting systems may suffer from potential diversity losses . Later, by incorporating the direct path into an An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks AF-based CRN, Duong et al. investigated the outage performance of a cognitive system, where a centralized link selection protocol was employed.

An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Network

Although the centralized selection criterion can improve outage behavior, its feedback overhead is considerable. Recently, inspired by an idea of distributed decision feedback, the authors of established several novel link/antenna selection schemes for An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks AF-based relaying systems, which significantly reduce the feedback overhead of link/antenna selection. Knowing that acquiring the instantaneous channel state information (CSI) of the interference links may incur additional cost, examined cognitive cooperative systems where only imperfect CSI of the interference links can be obtained at the secondary transmitters. An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks Motivated by the foregoing observations, in this paper we advocate a distributed link selection mechanism for a cognitive AF selection relaying network.

Specifically, by adopting an approximation to the received SNR at the destination, the tractable closed-form expression for the outage lower bound and the average feedback overhead of the secondary system are derived, where the cognitive transmitters can acquire either the instantaneous or statistical CSI pertaining to the interference links. Particularly, no matter whether the CSI knowledge of the interference links at the secondary nodes is perfect or not, the proposed scheme can alleviate the CSI feedback overhead while maintaining almost the same outage performance with that of , rendering it an attractive solution in practice.

COGNITIVE radio (CR) with spectrum sharing is regarded as a promising solution to enhance spectral efficiency and alleviate the issue of spectrum scarcity . On the other hand, cooperative relaying can provide remarkable performance advantages in ameliorating the An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks reliability and throughput of wireless systems. In recent years, incorporating relays into cognitive networks has received tremendous attentions, owing to its aforementioned merits. Previous related works are briefly introduced next. In , the authors proposed a novel design paradigm to maximize the cognitive user’s (CU’s) rate for MIMO CR under a minimum primary user (PU) rate constraint. and studied the performance of amplify-and-forward-based (AF-based) cognitive relay networks (CRNs) over Nakagami-m fading. An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks Considering both high and low-to-medium signal-to-noise ratio (SNR) regimes, and derived closed-form expressions for the outage probability of an interference-limited AF-based CRN with only one PU. Further, the authors of investigated the scenario with multiple PUs. However, since the direct link between the source and destination was ignored in both, the resulting systems may suffer from potential diversity losses . Later, by incorporating the direct path into an An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks AF-based CRN, Duong et al. investigated the outage performance of a cognitive system, where a centralized link selection protocol was employed. Although the centralized selection criterion can improve outage behavior, its feedback overhead is considerable. Recently, inspired by an idea of distributed decision feedback, the authors of established several novel link/antenna selection schemes for An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks AF-based relaying systems, which significantly reduce the feedback overhead of link/antenna selection. Knowing that acquiring the instantaneous channel state information (CSI) of the interference links may incur additional cost, examined cognitive cooperative systems where only imperfect CSI of the interference links can be obtained at the secondary transmitters. An Efficient Distributed Link Selection Scheme for AF-Based Cognitive Selection Relaying Networks Motivated by the foregoing observations, in this paper we advocate a distributed link selection mechanism for a cognitive AF selection relaying network. Specifically, by adopting an approximation to the received SNR at the destination, the tractable closed-form expression for the outage lower bound and the average feedback overhead of the secondary system are derived, where the cognitive transmitters can acquire either the instantaneous or statistical CSI pertaining to the interference links. Particularly, no matter whether the CSI knowledge of the interference links at the secondary nodes is perfect or not, the proposed scheme can alleviate the CSI feedback overhead while maintaining almost the same outage performance with that of , rendering it an attractive solution in practice.