With the availability of low-cost small-scale imaging sensors, CMOS cameras, microphones, which may ubiquitously capture multimedia content from the field, Wireless Multimedia Sensor Networks (WMSN) have been proposed and drawn the immediate attention of the research community. WMSN applications, e.g., multimedia surveillance networks, target tracking, environmental monitoring, and traffic management systems, require effective harvesting and communication of event features in the form of multimedia such as audio, image, and video. To this end, additional challenges for energy-efficient multimedia processing and communication in WMSN, i.e., heterogeneous multimedia reliability definitions, tight QoS expectations, and high bandwidth demands, must be addressed as well. We are building a WMSN Lab to experiment with multimedia applications in sensor architectures. Frame manipulation is required to minimize the amount of data to be sent. We are also defining and evaluating network protocols for WMSN taking into account traffic characteristics and error control mechanisms.

Ongoing Projects

A Congestion Control Protocol for Wireless Multimedia Sensor Network Using Cross Layer Information

Burst traffic of data and resource constrains in WMSN (Wireless Multimedia Sensor Network) has created high necessity for creating a powerful and and specific congestion control protocol for WMSN. Multimedia packets transmitted through the network have different priorities in the respect of the received video quality. In CACC (Content-Aware Congestion Control) protocol, I, P and B frames priorities is employed along with the adjustment of the video packets inter-arrival pattern, to create an energy-aware congestion control protocol for WMSN. Congestions in CACC protocol is detected regarding with input rate of sensors and number of sources in WMSN. To adjust the sending rate of each child, we predict number of packets in GOP when we have the size of I frame and ignore less important packets such as B and P frames.

People involved: Shahin Mahdizadeh Aghdam, Mohammad Khansari, Hamid R. Rabiee

Past Projects

Cross-Layer Error Control for Wireless Multimedia Sensor Networks

Wireless sensor network (WSN) multimedia applications impose new challenges in the design of algorithms and communication protocols for sensor networks. In fact, wireless multimedia sensor networks (WMSNs) must provide relatively high throughput and low end-to-end delay and jitter while being energy-efficient. In view of these challenges, error control is an important mechanism which enables us to provide robust and high quality multimedia communication in WSNs. In this project, we want to first comprehensively evaluate the performance of different error control schemes for multimedia communication over WSNs. The results of our analysis should provide the required insights for efficient design of error control protocols in WMSNs. Then we will develop a novel adaptive cross-layer error control for reliable and efficient real-time multimedia streaming in wireless sensor networks. The proposed error control protocol use an adaptive packet-level forward error correction algorithm in the application layer and an optimized hybrid error control schema along an unequal error protection mechanism in wireless link-layer. Our comprehensive simulation studies are expected to show the efficiency of the proposed protocol in terms of energy efficiency, frame peak signal-to-noise ratio (PSNR), and delay-constrained PSNR for real-time multimedia streaming over sensor networks.

People involved: Mohammad Yousof Naderi, Mohammad Khansari, Hamid R. Rabiee

___________________________________

Mobility Prediction in Mobile Ad-Hoc Networks

Mobile ad hoc networks (MANETs) are the dynamically reconfigurable wireless networks in which mobile nodes communicate with each other without the need for any fixed infrastructure. In these networks mobile nodes are free to move, therefore, network topology changes rapidly. These changes can lead to significant performance degradations in network protocols. To cope with this, a desired solution is to predict movements of mobile nodes. In this way, we can be prepared for changes. This project proposes two mobility prediction methods. In both methods, each node uses the information extracted from its own history of movements to predict its future location. Results obtained by applying two proposed methods, show significant improvements in terms of prediction accuracy compared to the other known methods.

People involved: Mehrdad Khaledi, Hamid R. Rabiee

___________________________________

Mobility Pattern Recognition in Mobile Ad Hoc Networks

Mobility is one of the most challenging issues in mobile Ad-Hoc networks which has a significant impact on performance of network protocols. To cope with this issue, the protocol designers should be able to analyze the movement of mobile nodes in a particular wireless network. In this project, a new framework called Mobility Analyzer has been proposed. At first, Mobility Analyzer categorizes mobility models based on their mobility characteristics; subsequently, it uses mobility metrics for evaluating mobility traces which are collected by GPS or generated by mobility simulators. Finally, Mobility Analyzer recognizes the mobility model of mobility traces based on mobility metrics and measures the similarity degree between mobility traces. Simulation results show high efficiency of this framework to recognize the mobility model of mobility traces.

People involved: Mojgan Khaledi, Hamid R. Rabiee

___________________________________

Data Reduction and Aggregation in Wireless Sensor Networks

Data transmission consumes most of the power resources in wireless sensor networks. Consequently, a large number of methods have been devised to cope with this problem. In this project, we propose a data reduction algorithm based on the transmission workload of intermediate nodes. We aggregate the incoming packets to the intermediate nodes into one packet by employing the Principal Component Analysis (PCA). Therefore, each intermediate node only sends one packet in stead of relaying all the incoming packets and hence we achieve considerable reduction in power consumption at those nodes. Although this approach imposes some delay for buffering the incoming packets, but extending the lifetime of intermediate nodes ensures longevity of the whole network. Using data simulations and numerical results, we have shown that the proposed method is more efficient in compare to related works.

People involved: Pedram Rooshenas, Hamid R. Rabiee, Ali Movaghar Rahimabadi

___________________________________

A Scheme for Scheduling Real-Time Traffic in IEEE 802.16 Networks

The IEEE 802.16 is an emerging standard that provides broadband wireless access in metropolitan area networks. The standard facilitates desirable capabilities including mesh topologies and multimedia communications for users. In IEEE 802.16 based mesh networks, there is no explicit uplink and downlink subframes in the physical frame structure and the uplink and downlink traffic scheduling is done within a single time frame. A frame is divided into two subframes: the control subframe and the data subframe. The control subframe is used to carry control messages and the data subframe is used for forwarding data packets to the users. In the mesh mode, two scheduling mechanisms, called centralized and distributed, are defined for each subframe. In the centralized scheduling of data subframes, the base station scheduling algorithm allocates the required bandwidth to each subscriber and set the priority for data packets transmission. However, this scheduling algorithm is undefined in the standard and its implementation is left open to the service providers for proper design based on the desired requirements. One may argue that; because of different characteristics of uplink and downlink traffic, different scheduling methods can be used for each of the traffic types. In this project, we focus on the centralized scheduling of data subframes in the mesh mode. We first provide an analysis on the downlink traffic characteristics, and then propose a new algorithm called the Downlink Flow Specifications-aware Scheduling (DFSS). In this algorithm, the flow propagation is tuned for the maximum concurrent transmission rate. This goal is achieved by sending out packets from the Base Station (BS) quickly and distributing the data packets in a chain-like manner into the network. In addition, the algorithm starts sending those packets that have lowest interference with other nodes on their path.

People involved: Fateme Dabiran, Hamid R. Rabiee

___________________________________