Longzhe Han

Selfish attacks and detection in cognitive radio Ad-Hoc networks

Cognitive radio is an opportunistic communication technology designed to help unlicensed users utilize the maximum available licensed bandwidth. Cognitive radio has recently attracted a lot of research interest. However, little research has been done regarding security in cognitive radio, while much more research has been done on spectrum sensing and allocation problems. A selfish cognitive radio node can occupy all or part of the resources of multiple channels, prohibiting other cognitive radio nodes from accessing these resources. Selfish cognitive radio attacks are a serious security problem because they significantly degrade the performance of a cognitive radio network. In this article we identify a new selfish attack type in cognitive radio ad-hoc networks and propose an easy and efficient selfish cognitive radio attack detection technique, called COOPON, with multichannel resources by cooperative neighboring cognitive radio nodes.

CATA: a garbage collection scheme for flash memory file systems

The problem of flash memory is that it cannot be overwritten unless erased in advance. In order to avoid having to erase during every update, non-in-place-update schemes have been widely used. In case of non-in-place update mechanism, garbage collection is needed to reclaim the obsolete space. In this paper, we study a new garbage collection scheme to reduce its cost such as the number of erase operations and the number of data copies. The proposed scheme determines the victim blocks by exploiting usage information of data blocks such as age, utilization and erase count. In addition, the proposed scheme predicts the future I/O workload and controls the number of victims to avoid disturbing the normal I/O operations. Experimental results show that the proposed scheme can perform well especially when the degree of locality is high.

An intelligent garbage collection algorithm for flash memory storages

Flash memory cannot be overwritten unless erased in advance. In order to avoid having to erase during every update, non-in-place-update schemes have been used. Since updates are not performed in place, obsolete data are later reclaimed by garbage collection. In this paper, we study a new garbage collection algorithm to reduce the cleaning cost such as the number of erase operations and the number of data copies. The proposed scheme automatically predicts the future I/O workload and intelligently selects the victims according to the predicted I/O workload. Experimental results show that the proposed scheme performs well especially when the degree of locality is high.

A scheme for data confidentiality in Cloud-assisted Wireless Body Area Networks

Abstract The integration of Wireless Body Area Networks with a cloud computing platform creates a new digital ecosystem with advanced features called Cloud-assisted Wireless Body Area Networks. This ecosystem enables users to globally access e-healthcare services at competitive costs. However, the secure data communications between the cloud and Wireless Body Area Networks are critical because the data is related to users’ privacy information. In this paper, we propose the Multi-valued and Ambiguous Scheme to capture data confidentiality in the Cloud-assisted Wireless Body Area Networks since it is the most important issue. The approach combining the scheme with existing encryption schemes provides a general paradigm for deploying applications. The obtained results show that secure data communications between the cloud and Wireless Body Area Networks can be achieved.

An adaptive FEC mechanism using cross-layer approach to enhance quality of video transmission over 802.11 WLANs

Forward Error Correction (FEC) techniques have been adopted to overcome packet losses and to improve the quality of video delivery. The efficiency of the FEC has been significantly compromised, however, due to the characteristics of the wireless channel such as burst packet loss, channel fluctuation and lack of Quality of Service (QoS) support. We propose herein an Adaptive Cross-layer FEC mechanism (ACFEC) to enhance the quality of video streaming over 802.11 WLANs. Under the conventional approaches, FEC functions are implemented on the application layer, and required feedback information to calculate redundancy rates. Our proposed ACFEC mechanism, however, leverages the functionalities of different network layers. The Automatic Repeat reQuest (ARQ) function on the Media Access Control (MAC) layer can detect packet losses. Through cooperation with the User Datagram Protocol (UDP), the redundancy rates are adaptively controlled based on the packet loss information. The experiment results demonstrate that the ACFEC mechanism is able to adaptively adjust and control the redundancy rates and, thereby, to overcome both of temporary and persistent channel fluctuations. Consequently, the proposed mechanism, under various network conditions, performs better in recovery than the conventional methods, while generating a much less volume of redundant traffic.

Adaptive Retransmission Scheme for Video Streaming over Content-Centric Wireless Networks

This paper presents an adaptive retransmission scheme to overcome video packet losses in content-centric wireless networks. Because of in-network caching, the round-trip time (RTT) may fluctuate significantly. A new timeout estimation algorithm is proposed to quickly adjust the timeout value. The sequential hypothesis testing methodology is suggested to provide theoretical bounds on the probabilities of false-positive and false-negative detection rates. By considering the reasons for packet losses, the scheme adaptively controls its retransmission window size. Experimental results demonstrate that the proposed scheme efficiently recovers packet losses under various network conditions.

An Improved LEACH Routing Protocol for Energy-Efficiency of Wireless Sensor Networks

A wireless sensor network (WSN) is a wireless network consisting of a base station (BS) and multiple micro-sensor nodes. The micro-sensor nodes run on batteries that are not recharged during the network’s lifetime. Therefore, prolonging WSN lifetime is a significant problem. There are some energy-efficient hierarchical routing protocols designed especially for WSNs, such as sensor protocols for information negotiation (SPIN), low-energy adaptive clustering hierarchy (LEACH) and LEACH-centralized (LEACH-C). In this article, we propose an improvement on the LEACH routing protocol to decrease energy consumption and prolong network lifetime. LEACHDistance Energy (LEACH-DE) selects a cluster head node not only by considering residual energy of the node greater than the average residual energy level of nodes in network, but also by examining the geometric distance between the candidate node to the BS as a key parameter. The results of simulation show our proposed algorithm outperforms LEACH and LEACH-C in terms of conserving energy and prolonging WSN lifetime.

Quasi-Quadrature Modulation Method for Power-Efficient Video Transmission Over LTE Networks

New emerging services, such as real-time video streaming or video on demand, are causing rapid growth in packet transmission over wireless networks. Unlike voice calls, for which the duration is usually not very long, video streaming applications require continuous transmission for a long time. Therefore, video streaming applications in mobile networks consume more energy compared with voice calls. Thus, the task of optimizing data transmission algorithms has become more important during the last few years. Apparently, the majority of multimedia traffic is video transmission. These applications consume much more power, compared with audio or general data transmission, because of higher throughput requirements. This paper addresses the problem of decreasing power consumption due to video transmission applications in Long-Term Evolution (LTE) networks. There are existing solutions for managing power consumption during video transmission. In particular, Third-Generation Partnership Project LTE Advanced (LTE-A) has defined the discontinuous reception/transmission (DRX/DRT) mechanism to allow devices to turn off their radio interfaces and go to sleep in various patterns. Some other similar solutions suggest DRX/DRT optimization to maximize the sleep periods of devices while guaranteeing quality of service in multimedia applications. However, existing solutions for packet transmission optimization are not very effective without physical-layer optimization. However, existing solutions for packet transmission optimization are not very effective without physical-layer optimization. We suggest a new method of modulation for improving energy efficiency of wireless video transmission. Four different schemes of quasi-quadrature modulation using multiple-input-multiple-output (MIMO) techniques with different quality of service performances are proposed in this paper. We simulate H.264/AVC video transmission. Results confirm the theoretical analysis. The proposed approach is able to improve energy efficiency while providing the same packet loss probability.

A survey: energy exhausting attacks in MAC protocols in WBANs

Because the sensors of wireless body area networks (WBANs) have limited battery power, many studies have focused on energy efficient medium access control (MAC) protocols to extend the lifetime of the sensors. In addition, WBANs face energy-exhausting attacks, which force the sensors to consume battery power partially or thoroughly. These attacks occur mainly in the MAC layer and threaten severely the energy efficiency of MAC protocols in WBANs. Because the attacks are made abruptly and unexpectedly, the lives of human beings and the quality of health care services can be threatened. Therefore, the aim of this study was to identify the major types of energy exhausting attacks in MAC protocols in WBANs, and show how easily the attacks can cause energy exhaustion in different MAC protocols. This survey provides clues for future research into energy efficient MAC protocols in WBANs.

Efficient Data Dissemination in Mobile P2P Ad-Hoc Networks for Ubiquitous Computing

In this paper we propose Rank-Based Broadcast (RBB) algorithm using High Order Markov Chain (HOMC) with weight values in mobile p2p ad-hoc networks (MOPNET) for ubiquitous. RBB using HOMC focuses on the first step to improve the performance of Ubiquitous broadcast computing. The proposed model is characterized by its ability to optimize the receiving query and sending report for broadcasting with probabilistic priority by Markov assumption. Moreover, our model enhanced the reliability of broadcasting by weight value. In this paper we also set up a mobile p2p ad-hoc networks by Qualnet simulator which created the value of the specific configuration of mobile units and estimated the performance our model with other algorithm or ideal case.