Xiangming Wen

A Novel Handover Mechanism Between Femtocell and Macrocell for LTE Based Networks

The femtocell networks that use Home eNodeB and existing networks as backhaul connectivity can fulfill the upcoming demand of high data rate for wireless communication system as well as can extend the coverage area. It is also of interest to minimize operational effort by introducing self-optimizing mechanisms, and the optimization of the Home eNodeB involved handover is an important goal of LTE-Advanced. Since the different network architecture and functionality between Home eNodeB and LTE eNodeB, the handover procedure between the femtocell and macrocell should be modified in LTE network. In this paper, modified signaling procedure of handover is presented in the Home eNodeB gateway based femtocell network architecture. A new handover algorithm based on the UE’s speed and QoS is proposed. The comparison between the proposed algorithm and the traditional handover algorithm shows that the algorithms proposed in this paper have a better performance in the reducing of unnecessary handovers and the number of handovers.

A History-Based Handover Prediction for LTE Systems

Handover prediction has been considered an effective technology for improvement of LTE Handover performance. Although not a few techniques have been proposed to achieve this goal including handover preparation based on cross-layer optimization and mobility prediction, the fact is that their gains are not usually so high as their cost. To overcome such weaknesses, this paper proposes a simple handover prediction technique which is based on a novel user mobility model to approximate simulation the laws of user mobility actions. We develop a user mobility database to assist the mobility prediction based on the user mobility history records. The simulation results show that the proposed technique minimizes the number of handovers and lower the ping-pang rate in LTE system.

Filtering Short Message Spam of Group Sending Using CAPTCHA

Short message spam brings so much trouble to the users, and the volume of short message spam becomes more and more large, especially the function of group sending is used in short message. This paper proposes a method to filter short message spam of group sending, in other words, it utilizes CAPTCHA (completely automated public Turing test to tell computers and human apart) method to filter short message spam. If the short message service (SMS) can pass the CAPTCHA, it will be identified as legitimate SMS and transmitted by Short Message processing Center. Conversely, if the SMS can not pass the CAPTCHA, it will be identified as SMS spam and deleted by Short Message processing Center. Finally, it has been simulated with Smartphone of Microsoft Visual Studio 2005.

A Novel Self-Optimizing Handover Mechanism for Multi-service Provisioning in LTE-Advanced

The 3GPP is defining the next generation radio access network which introduces advanced self- optimization to reduce the operational efforts and complexity. It is also of interest to minimize operational effort by introducing self-optimizing mechanisms. Optimization of the handover parameters is an important goal of LTE-Advanced. In this paper, a new self- optimizing handover algorithm based on the estimation of the number of cell-boundary crossings is proposed. The algorithm adjusts the handover parameters, such as Time- to-Trigger, measurement interval, and hysteresis, by comparing the number of cell-boundary crossings and the number of handovers UE performed in a period. To optimize the handover performance further, an adaptive L3 filter based on the UE’s velocity is proposed in this paper. A typical application scenario of this algorithm is high/medium speed environment under multi-service provisioning. The simulation results shows that the algorithms proposed in this paper have a better performance in the rate of ping-pong handovers and the average number of handovers.

Shot Boundary Detection and Keyframe Extraction Based on Scale Invariant Feature Transform

In shot boundary detection, the key technology is to compute the visual content discontinuity values between consecutive video frames. In this paper, a unified framework is proposed to detect the shot boundaries and extract the keyframes of a shot. Firstly, the Scale invariant feature transform (SIFT) is adopted to compute the visual content discontinuity values. Then a new method, which is called the Local Double Threshold Shot Boundary Detection (LDT-SBD), is used to detect shot boundaries. Lastly, two mechanisms are proposed to extract keyframe. Experimental results show the framework is effective and has a good performance.

A Simple Method for Filtering Image Spam

Image spam can easily circumvent widely text spam filters. It is a new trend of spam, and poses a great threat to email communications. In this paper, we give the definition of image spam firstly. Then we propose a simple method for filtering image spam, which utilizes file properties and histogram (gray histogram or color histogram). Finally, a preliminary experimental evaluation of our approach is reported on a personal dataset and Princeton benchmark dataset of spam images publicly available.

A two-step vertical handoff decision algorithm based on dynamic weight compensation

Vertical handoff is crucial to future wireless communication. In this paper, a two-step vertical handoff decision algorithm based on dynamic weight compensation is proposed. This algorithm adopts the filtering mechanism to reduce the system cost and improves the conventional algorithm by dynamic weight compensation and consistency adjustment. The experimental results show that our algorithm outperforms the traditional algorithm by increasing the consistency of decision matrix, fully taking advantages of the range of network choices and reaching a better load balance of the whole wireless environment.

The Content Delivery Network System Based on Cloud Storage

Numerous Cloud storage service have recently emerged to provide Internet-enabled content storage and delivery capabilities. The CDN system based on Cloud storage, adopting distributed storage technology and the cache technology, can provide content creators with cheap CDN service and content consumers (mobile WAP users) with less response time and wider bandwidth WAP service. For the mobile WAP service users, the system provided by telecom operators has mirror servers across the country and can automatically determine the most suitable route between the mirror server and the WAP service users. In the paper, the architecture and the performance of the system will be introduced.

A Self-Optimizing Mobility Management Scheme Based on Cell ID Information in High Velocity Environment

Reduction of the operational effort and cost is a key driver for RAN LTE (Long Term Evolution or E-UTRAN). Self-configuring and self-optimizing mechanisms are introduced as a part of Self Organizing Network (SON) to maximize the integrated performance of LTE/LTE-Advanced by improving the efficient of operation and maintenance. Optimization of handover is one of the optimization aspects of Self Organizing Network in LTE-Advanced. High velocity environment, especially multi-service environment usually needs extensively investigation to optimize. Using layer3 filter, hysteresis, and time-to-trigger mechanisms is standardized for LTE Hard handover. In this paper, an interacting self-optimizing handover mechanism based on cell ID information is proposed. We have shown that significant gain can be achieved by the use of optimization mechanism while maintaining low handover rates and ping-pong handover rate.

A virtual network embedding algorithm based on mapping tree

Network virtualization enables the co-existence of multiple virtual networks (VNs) on the same substrate network (SN) by sharing the available resources. Virtual network embedding (VNE) plays an important role in building virtual networks. In this paper, we propose a new virtual network mapping algorithm based on a mapping tree on nodes mapping phase. Mapping tree, converted from the virtual network, is a simplified topology of virtual network, which is used to describe the hierarchical relationships among the virtual nodes. In our algorithm, different virtual nodes in a mapping tree which are directly connected by virtual links should be mapped to the same substrate node as long as the nodes available resources can satisfy the total resource requirements of these virtual nodes. In link mapping phase, we use the k-shortest paths method. Simulation results show that the proposed scheme has a good performance in the acceptance ratio of virtual network requests, and the average revenue of substrate network.