Niu Jianwei

Adaptive Copy and Spread data dissemination in vehicular ad-hoc networks

Vehicular ad-hoc networks (VANETs) are promising for more and more intelligent transportation applications, where information is disseminated over a group of vehicles. VANETs are characterized for its unstable framework, in which the isolated vehicles communicate with others only when the unexpected meetings occur. As a result, some available data dissemination schemes do not work well in VANETs. In this paper, we propose an opportunistic auto-adaptive dissemination scheme - Adaptive Copy and Spread (ACS) Algorithm - for VANETs, which makes use of the moving patterns of vehicles like direction and velocity, and dynamically adjusts the dissemination strategies. This scheme dynamically increases or decreases the number of message copies inside the broadcast area, and vehicles can intelligently decide when to start or stop broadcast a message. ACS is designed to keep the message at the effective areas boundary to inform the entering vehicles as soon as possible. The simulation results show that ACS enhance the data dissemination performance significantly with a smaller network load compared with random choice algorithm and Epidemic dissemination algorithm over a series of scenarios.

P2P-Leveraged Mobile Live Streaming

Providing high rate streaming service over cellular data networks is a challenging work. In this paper, a mobile streaming broadcast system, called P2P-leveraged mobile live streaming system (P2PMLS), is proposed. In P2PMLS, the multiple network interfaces of mobile hosts are used. The mobile hosts form a peer-to-peer overlay networks through WiFi or Bluetooth. A part of the peers, called seed peers, receive streaming data from the server through cellular data networks and share the obtained data with other mobile hosts in the overlay network. The peer layer protocol is also proposed to manage the overlay network. Based on the design, a simple prototype is implementing. The performance of the design is compared with the cellular network streaming scheme in an analysis way. The results show that P2PMLS is superior to the cellular network streaming scheme.

Modeling of Broadcasting Based on Distance Scheme for WSN

The modeling of the natural WSN (Wireless Sensor networks) is very difficult because of its complexity. Therefore, the normal way is to evaluate various broadcasting protocols for WSN in simulation. The actual structure of WSN really can be modeled via simplifying some condition to validate the simulation results. In this paper, a modeling method for data broadcasting in WSN is advanced by calculating the transmission probability based on distance coverage. The simulation results indicate that the proposed model is accurate.

A Lightweight Video Encryption Algorithm for Wireless Application

Protecting the confidentiality and integrity of video information is one of the crucial security elements for many wireless video applications. Taking limited power, processor resource and bandwidth of mobile device into account, a lightweight luminance transform coefficients encryption (LTCE) algorithm, is proposed based on the special feature of the H.264 video coding standard. In LTCE algorithm, the luminance transform coefficients of residual data before entropy coding are adjustably partially encrypted by stream cipher, and it is discussed when ciphertext value are equal to zero in detail. Experimental results demonstrate the proposed algorithm that encrypts much less important data can achieve good security and high efficiency, as well as obtain low complexity and time cost. LTCE algorithm is suitable for security multimedia services for wireless application.

A robust multi-cue blending-based approach for floor detection

The task of indoor localization has been carried out with different approaches, which utilize data integrated from distinct sensors belonging to mobile devices. Floor determination is one of the crucial challenges encountered during indoor localization. The solutions to floor determination are mainly based on the techniques of Wireless Fingerprint and RFID (Radio Frequency Identification) sensors. However, the accuracy of such methods still needs to be improved, especially for complex multi-floor building environments with few APs (Access Points). To enhance the accuracy associated with floor determination, in this work, we propose a robust approach for floor detection based on fusion of the RSSI (Received Signal Strength Indication) values and data acquired from an acceleration sensor. Our approach has two key phases. Firstly, the floor pertaining to the users initial position is automatically generated by using the RSSI data. Secondly, the estimated floor number is verified by utilizing the data acquired from acceleration sensors. With the aid of sufficient experiments on our challenging datasets, we demonstrate that our proposed approach yields more accurate results than state-of-the-art approaches used for determining the floor number.

P2PMP2: A Peer-to-Peer Leveraged Mobile Streaming System Based-on Push and Pull

In a traditional mobile streaming system, all users pull streams from the server. This model would cause users a high communication cost and heavy burden to the base station. At the same time, the low bandwidth of the cellular network cannot meet the requirements of high quality video, which greatly limits the large-scale deployment of the mobile multimedia streaming service.In a traditional mobile streaming system, all users pull streams from the server. This model would cause users a high communication cost and heavy burden to the base station. At the same time, the low bandwidth of the cellular network cannot meet the requirements of high quality video, which greatly limits the large-scale deployment of the mobile multimedia streaming service. In this paper, we propose a fully distributed, scalable, and cost-effective system called Peer-toPeer leveraged Mobile streaming based on Pull and Push (P2PMP). Under this solution, a novel network architecture based-on ‘‘pull-push’’ transmission strategy is proposed, which makes use of the secondary free local channels already available in mobile devices today to form a peer-to-peer network. There are two roles in the local network: seed and passive receiver, as shown in Fig. 1. Seeds in P2PMP download video contents through the cellular channel, and share them with its nearby neighbors by broadcasting using the secondary wireless channel. Regarding the lost data, passive receivers use another local wireless channel to request from their neighbors. The way that seeds broadcast video data to passive receivers is called ‘‘push.’’ While the way that passive receivers request lost data from neighbors using another channel is called ‘‘pull.’’ This architecture aims at ‘‘few users download video data from base station, and most users can get a high quality video.’’ In our paper, an important issue about seed selection strategy under this network architecture is addressed. It consists of two parts:

Dynamic Prediction of Data Validity for Mobile Databases

Optimistic replication which does not lock resources and can tolerate disconnections appears to be the natural choice for mobile computing environment. The replication approach allows updates to be performed independently at any replica, so the fundamental problem in this scheme is that data at any replica has the probability of invalidation. To resolve this problem, this paper presents a new dynamic prediction of data validity algorithm (DPDVA), which predicts the validity of data replica stored in mobile nodes by local history information. Experimental results show that DPDVA is an effective prediction algorithm to maintain database consistency. The more local information mobile nodes store, the better the prediction effects will be.

A Novel Protocol in Intermittent Connected Mobile Networks

Intermittent connected mobile sensor networks (ICMSN) have emerged in recent studies, e.g. underwater sensor networks, wildlife tracking and human-oriented flu virus monitoring. In these networks, there are no end to end connections from sensor nodes to sink nodes due to low node density and node mobility. Therefore, conventional routing protocols in WSN are not practical for ICMSN since packets will be dropped when no complete route to the sink is available. In this paper, we propose an efficient routing protocol for ICMSN, which is composed of buffer management and message forwarding. Buffer management consists of two related components: queuing mechanism and purging mechanism. The former determines priority of messages to transmit or discard based on the importance factor, which indicates the QoS requirement of the messages. The latter utilizes a death vector generated by the sink to purge useless messages that have been delivered from the network. Message forwarding makes decision on which sensors are qualified for next hop based on node delivery probability, which synthesizes the meeting predictability to the sink, current buffer state and residual energy and increases the likelihood that the sensor can deliver the message to the sink. Our experimental results show that the proposed routing protocol not only supports the QoS requirement of different content but also achieves the good performance tradeoff between delivery ratio, delay and resource consumption.