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SUMMARYThe next generation wireless communication system will likely be heterogeneous networks, as various technologies can be integrated on heterogeneous networks. A mobile multiple-mode device can easily access the Internet through different wireless interfaces. The mobile multiple-mode device thus could switch to different access points to maintain the robustness of the connection when it can acquire more resources from other heterogeneous wireless networks. The mobile multiple-mode device therefore needs to face the handover problem in such environment. This work introduces Session Initiation Protocol (SIP)-based cross-layer scheme to support seamless handover scheme over heterogeneous networks. The proposed scheme consists of a battery lifetime-based handover policy and cross-layer fast handover scheme, called the SIP-based mobile stream control transmission protocol (SmSCTP). This work describes the major idea of the proposed scheme and infrastructure. The proposed scheme has been implemented in Linux system. The simulation and numerical results demonstrate that the proposed SmSCTP scheme yields better signaling cost, hand-off delay time, packet loss and delay jitter than SIP and mSCTP protocols.

Low Power Wireless (LPW) networks have recently been emerging as key candidates to offer affordable connectivity for the constrained devices in the Internet of Things (IoT). However, they also raise major security concerns due to the inherent security vulnerabilities of built-in communication protocols. By exploiting these flaws, an adversary can attack sensors or actuators in an LPW network and force them to execute energy-hungry tasks such as verifying unauthenticated garbage messages repeatedly. This attack, namely energy depletion attack (EDA), can drain the batteries of the devices rapidly and lead to soaring network-wide energy expenditure. Consequently, the offense can leave the victims disabled, and even shut down the whole network due to the battery exhaustion of all the devices. In this paper, we investigate existing studies and provide a systematic review of EDAs and defenses in LPW networks. Through this work, we conclude that most existing LPW technologies are vulnerable to EDAs. This paper also indicates the security challenges in LPW networks related to EDAs along with the potential research directions. While LPW technologies have already hit the market with the promising deployment schedules, our attempt can inspire the research community to enhance the security of underlying protocols that will shape the connectivity of billions of devices in the future IoT ecosystem.INDEX TERMS Energy depletion attacks, IoT security, IoT embedded devices, low power wireless sensor networks.

ith the rapid growth of wireless traffic, the current wireless technology will reach its limits in the next 10 years. The future International Mobile Telecommunication (IMT) systems are expecting that 5G communication technology will be able to achieve some challenging requirements, such as 10 times higher spectral efficiency, five times reduced end-to-end delay, a 50 Gb/s data rate for low mobility user equipment (UE), and 5 Gb/s for high mobility UE, etc [1]. Thus it makes the performance of traditional network architecture increasingly unable to keep up with 5G communication [2,3]. Therefore, software-defined networks (SDNs) were regarded as a revolutionary technology to subvert the traditional networking industry [4,5]. With the emerging technologies of network and communication, the multimedia streaming that has always been one of the most bandwidth-consuming services will achieve further development. Currently, due to emerging on-line streaming video websites, such as YouTube, Netflix, and Tudou, people tend to watch movies, videos, and TV programs via streaming servers, resulting in the discussion of various subjects, such as how to use appropriate network protocols to transmit video content, how to effectively reduce the delay time, how to select appropriate video formats, how to achieve seamless streaming, and how to balance the operating load between the streaming servers. Hence the adaptive streaming technologies were proposed in the past that can dynamically select video content based on current network conditions or mathematical capabilities of hardware in order to provide higher-quality streaming service to users [6,7]. However, in heterogeneous networks some studies have attempted to improve the bandwidth prediction for effective transmission rates [8,9].Therefore, how to provide users with the adaptive streaming services between 5G wireless communication networks and SDNs will be an interesting challenge. Different from other studies on 5G networks, this study aims at a dynamic adjustment video streaming mechanism with HTTP live streaming (HLS) protocol according to the utilization and stability of the routers and switches of SDN and the network condition of 5G, enhancing service quality. The paper is organized as follows. We first propose the two modes of SDN controller for adaptive streaming. Then we evaluate the traffic bandwidth based on two modes with different network conditions. Furthermore, the five network scenarios of SDN- W AbstractWith increasing interest in the concept of 5G wireless networks and the popularization of mobile devices, users gradually watch videos through mobile devices in streaming mode rather than off-line mode. However, the latency and lags of mobile networks will reduce the quality of service. In HTTP live streaming services, when there are multiple sources for the same content stored in the streaming servers, the suited quality content is able to be selected for playing according to the networking bandwidth conditions between servers and user equipment, and the use...

The requirement for in-vehicle passengers to access Internet multimedia services has risen recently. As a consequence, Vehicle Ad hoc NETwork (VANET) has gained much attention, and is regarded as a promising solution for providing in-vehicle Internet service through inter-vehicle and infrastructure communication. A new developed wireless network technique, termed WiMAX Mobile Multihop Relay (MMR), provides a good communication framework for a VANET formed from vehicles on high-speed freeways. Applying MMR WiMAX allows some public transportation vehicles to act as relay vehicles (RVs) to provide Internet access to passenger vehicles. However, the standard handover procedure of mobile or MMR WiMAX suffers long delay due to the lack of information about the next RV. This study presents a cross-layer fast handover scheme, called vehicular fast handover scheme (VFHS), where the physical layer information is shared with the MAC layer, to reduce the handover delay. The key idea of VFHS is to utilize oncoming side vehicles (OSVs) to accumulate physical and MAC layers information of passing through RVs and broadcast the information to vehicles that are temporarily disconnected, referred to as disconnected vehicles (DVs). A DV can thus perform a rapid handover when it enters the transmission range of one of approaching RVs. The effectiveness of VFHS is verified using ns2 simulations. Simulation results indicate that VFHS significantly decreases handover latency and packet loss.