Since Apple introduced the iBeacons in Worldwide Developers Conference (WWDC) 2013, the iBeacon has been rapidly accepted and generalized in the market. For the deployed iBeacons, it is necessary to monitor their status. In this paper, we design a crowd sensing based monitoring framework which combines the moving and static schemas of participants to monitor the real status of iBeacons. In such a system, the inaccuracy and conflict of the collected signal information, commonly caused by the error rate of participants or the differences of sensing context, have received more and more attention. Estimating the real status of iBeacons according to the uploaded signal information becomes a big challenge for our monitoring system. Towards this end, we propose a context-aware estimation approach in this paper. We first model the effects of sensing context, and then propose an iterative method to infer the error rate of participants and estimate the real status of iBeacons with high precision. Our method is tested via extensive simulations, and verified by our monitoring system which has been applied in the teaching building. The results demonstrate that the proposed estimation approach outperforms recent popular three-estimates algorithm and OtO EM algorithm. At last, we develop the review mechanism, which ensures the efficiency of our monitoring system.

SUMMARY The Media‐Independent Handover (MIH) standard proposed by IEEE 802.21 can reduce handoff delay when mobile nodes switch between heterogeneous access networks and help Mobile Nodes (MNs) roam seamlessly. The MIH standard is suitable for not only heterogeneous networks but also homogeneous networks. According to the Fast Mobile IPv6 (FMIPv6), during handover initiation, for MNs to get new Access Router (nAR's) prefixes, using Router Solicitation for Proxy Advertisement (RtSolPr)/Proxy Router Advertisement (PrRtAdv) may be time consuming. If there are additional quality of service requirements, the FMIPv6 would require much more time. Based on FMIPv6, this paper proposes a new IS‐FMIPv6, which combines MIH services. We also propose a new mechanism for discovering the access route. This scheme reduces the time spent for finding the route to the nAR and increases the probability that FMIPv6 operates in the predictive mode by reducing initiation handoff delay. Published in 2010 by John Wiley & Sons, Ltd.

Abstract In recent years, thanks to the development and popularization of wireless network technologies, the issue of vehicularad hocnetwork (VANET) has received great attention, and more and more VANET‐related researches have been brought up. Generally speaking, the biggest difference between VANET and traditionalad hocnetwork is the velocity of carriers because in VANET, the velocity of vehicles, the carriers, is much higher than those in traditionalad hoc. Therefore, it would be a great challenge to forward data efficiently in VANETs and many researches proposed have focused on the development of routing protocols. The current proposed routing protocols are all assumed to simulate in a distributed and ideal environment. As for the complex geographic environments, such as urban scenarios, extra amendments must be needed to improve the efficiency of the routing protocols. Thus, the main purpose of this paper is to design a suitable routing protocol for urban scenarios with better performance and adaptability. For this reason, greedy on straight roads and predictive at the intersections (GSPI) routing protocol is proposed to use greedy mode on straight roads and to use predictive mode at the intersections. In greedy mode, we choose the next hop according to the weight value that combines the distances and multi‐rate. In predictive mode, we predict the directions of the vehicles to determine the next hop. The simulation results reveal that our proposed algorithm indeed proves its feasibility. Copyright © 2010 John Wiley & Sons, Ltd.

The packet-switched NGN (Next Generation Network) architecture allows users to access multimedia services via the Internet anytime and anywhere. Through the core IP Multimedia Subsystem (IMS), NGN can provide multimedia services, such as voice, video, data and messages over heterogeneous networks. However, for high-quality services in practical environment, the performance and QoS (Quality of Service) of NGN must be guaranteed. Thus, based on the Testing and Test Control Notation version 3 (TTCN-3) specifications, this paper develops a test system utilizing Open IMS Core for conformance test of IMS session initiation for fixed and mobile networks. We also verify the QoS and analyze the performance of SUT (System Under Test) from the experimental results.

In Wireless Access in Vehicular Environments (WAVE), the terminal devices are usually highly mobile vehicles or transportation tools, which handoff much more frequently than those in wireless networks. However, the quality of network services, like VoIP and multimedia streaming, will be seriously influenced by too frequent handoff or too long handoff latency. As a result, traditional handoff mechanisms no longer satisfy the need of vehicular communications. At present, most existing fast handoff mechanisms are based on the signal strength of the APs, which does not suit vehicular communications fully. Generally speaking, the regional traffic in Vehicular Ad-hoc Networks (VANETs) keep changing and varying. For example, on busy roads or in rush hours, the increase of number of vehicles may lead to the network congestion and degrade the performance of vehicular communications substantially. Therefore, this paper presents the QualityScan scheme, an efficient pre-scanning method to improve the handoff performance in VANETs. With the attempt to reduce the handoff latency and maintain the load balance among the APs, our proposed scheme regularly collects the loading states of the nodes by the pre-established AP controller (APC), and predicts the network traffic of the next moment. Consequently, Mobile Nodes (MNs) can select the most suitable AP for the best QoS according to the parameters received by passive scanning, while more QoS parameters should participate in cooperation. The simulation result proves that our proposed scheme not only maintains the QoS and the load balance among the nodes, but also further enhances the handoff performance in VANETs.

Among the present wireless network technologies, wireless sensor is one of the most extensively applied devices. In addition, with the rapid advancement of wireless communication in recent years, Wireless Sensor Network (WSN) has become very popular research issue and how to realize indoor localization by using sensors is the most common topic. For the time being, localization in wireless sensor networks can be divided into two major categories: Range-based and Range-free localization algorithms. The Range-based algorithms mainly use ranging techniques (ToA, TDoA, AoA, RSS, for example) as the tools to measure the distances between the nodes. From the measured information, the estimated position can be figured out. On the other hand, instead of utilizing ranging techniques, the Range-free algorithms estimate the positions by making use of reference nodes. However, indoor environment exist many interference factors that easily lead to localization inaccuracy. In order to solve the problems that indoor localization may encounter, some algorithms use RF-mapping method to avoid the influence of indoor environment to the localization result. Nevertheless, to make the localization precise needs more data about reference nodes and this greatly increases both the time to set up and the volumes of calculation. Thus, this paper proposes a GA-based (Genetic Algorithms, GA) localization algorithm to estimate the location of unknown nodes and avoid the influence of environmental factors by pre-establishing the pattern. Moreover, the proposed algorithm does not need too much information about reference nodes to pre-establish the pattern.

In the vehicular environment, the transmissions of signals have to face the higher challenges then indoor wireless local area networks (WLAN). Multipath fading cause high bits error rate (BER), in such an unstable transmission environment. And high BER cause high dropping probability of packets. In order to reduce the dropping probability of handshaking packets without increase the capability of infrastructures, a mechanism is proposed in this paper. In our work, we altered the traditional cyclic prefix (CP) into a variable cyclic prefix (VCP) of request to send (RTS) frame and clear to send (CTS) frame, and reduce the handshaking packets error rate in vehicular wireless transmissions, hence we can improve the contending ability in Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) at vehicles to infrastructure (V2I) transmission., By analyzing environment parameters, we can predict the suitable VCP time slots and dynamic adjust VCPs. And we can competently eliminates the impacts of Intersymbol interference (ISI) caused by multipath fading in CSMA/CA.

Home media is getting more and more popular. For home users, a variety of applications are established based on HMWN (Home-Media Wireless Network). Nowadays, most of video streaming algorithm use extra bandwidth to keep high video quality. In fact, mobile users nowadays can participate in file sharing communities to download or upload files by different mobile devices on HMWN. Furthermore, to guarantee quality of video streaming when error occur the retransmission and selection drops method should be present. The receiver node decides a scheme in the end of frame and feedback to sender immediately before sender start encode next frame. The home media algorithm use MPEG-4 part2 visual video codec. MPEG-4 part 2 visual provide a simple reference coder tactic. It just code previous one frame not like multi reference frame tactic in H.264 or MPEG-4 part 10 AVC. In this paper, the main goal of this paper is to design a better mechanism called "A Robust End-to-End Delivery Scheme", we not only take simple coding method, but also consider the change the motion prediction coding method before coded next frames and send it. A novel video stream algorithm was proposed in this paper that can make usage of bandwidth more efficiency and also can be adaptive with error modules on HMWN.

A pervasive computing system has to be context-aware because it cannot distract users. However, user's context information can be quite rich and unpredictable. Therefore, how to design an extensible protocol to achieve these requirements and implement a context-aware Internet service is very important. In this paper, we propose a SIP-compatible protocol for context-aware services, and this protocol is easy to understand, implement, and deploy. We also demonstrate some scenarios about this protocol to show transactions between client and server as well as behaviors of proxy/redirect servers. Finally, our projects implemented by this protocol are introduced. This study also provides a further insight on the issues of context-aware concept in pervasive computing, and demonstrates a referable methodology to propose and implement a context-aware framework in pervasive computing, which can promote the technology of future Internet.

The short message service (SMS), a bidirectional service for short alphanumeric (up to 160 bytes) messages, is a unique feature of GSM, not found in older analog systems. We propose a multicast short message service architecture over a backbone network. We demonstrate some approaches to maintain the location information of the short message service center consistent to the home location register and illustrate our scheme for mobile-terminated short message transfer. Finally, we simulate and evaluate this architecture. Our simulation indicates that the proposed strong consistency approach has optimal efficiency by adjusting parameters. Also, the proposed architecture efficiently provides a self-routing capability and multicast functionality in the cellular backbone network. This study also provides a further insight on the issues of a multicast wireless cellular backbone network and demonstrates a referable methodology to propose and analyze a multicast cellular backbone network, which can promote the technology of personal communication networks.

We introduce a new network access protocol for a CSMA-type multichannel local area network (MLAN). This new protocol has the capability of providing different network access priority among the various applications. From the earlier research, it has been shown that the CSMA-type MLAN is superior to a single channel of equal network bandwidth. On the basis of the developed MLAN architecture, we construct a new network access protocol to provide multiple transmission priorities for various applications e.g., text, voice, video, image, etc. This protocol is called multiple-priority multichannel local area network (MP-MLAN). The data transmission of MP-MLAN is collision-free, and we can find the throughput characteristics of MP-MLAN are higher and more stable than the conventional CSMA/CD or multichannel CSMA/CD network from the analysis results. A queueing analysis model for representing the MP-MLAN protocol is established and simulation results are also provided to evaluate the performance of this network.

In this paper, a simple addressing methodology called binary address scheme (BAS) is presented for the Manhattan Street Networks. It overcomes some of the deficiencies of other previously proposed schemes. It allows new nodes to be inserted into the network without changing the addresses of any existing nodes. In addition, it also reduces the computational complexity of routing. BAS provides a simple distributed routing rule that can be easily implemented by hardware in each node to achieve better performance. BAS can also be used in other networks which have strong dependence on the sequential order of node addressing.>

A high speed integrated local area network and its protocols are described. The protocols combine blocking, queueing, and connection management disciplines to maximize the use of network bandwidth. This ensures that many stations can transmit real-time packets simultaneously, even real-time video data. Performance results including transmission delay and discarding ratio are presented and discussed.>