Moad Yassin Mowafi

Use of elliptic curve cryptography for multimedia encryption

The unique characteristics of the elliptic curve cryptography (ECC) such as the small key size, fast computations and bandwidth saving make its use attractive for multimedia encryption. In this study, the ECC is used to perform encryption along with multimedia compression, and two ECC-based encryption algorithms are introduced and applied before and during compression. The first algorithm performs selective encryption on the transform coefficients during compression, whereas the second algorithm achieves perceptual encryption based on selective bit-plane encryption before compression. The results of applying ECC to multimedia encryption are presented and analysed with respect to the requirements of multimedia encryption: the encryption efficiency, compression efficiency, codec compliance and security level. It is shown that ECC is highly efficient and does not affect the compression efficiency, and accordingly can meet the multimedia encryption requirements.

Fuzzy logic based energy efficient adaptive clustering protocol

In order to overcome the problem of the limited power of the sensor battery and thus prolonging the lifetime of a Wireless Sensor Network (WSN), many routing algorithms were proposed to gather and forward the sensed data to the base station. One of the most well-known routing algorithms that were proposed in the last years is the LEACH protocol. It is a dynamic cluster-based routing protocol that divides the network lifetime to rounds where each round is composed of two phases: setup and steady state. The key factor of each round is the number of nodes that will act as cluster heads (CHs). Each CH is responsible for collecting the sensed data from the sensor nodes that are in the same cluster and then forwarding the aggregated data to the base station. In this paper we suggest FL-LEACH protocol that employs fuzzy logic in order to determine the number of CHs that should be used in the WSN. FL-LEACH is a fuzzy inference system that depends on two variables: number of nodes in the network and nodes density. Assuming uniform distribution of the nodes over the sensor field, the novelty of the proposed approach is in its ability to determine the number of CHs without getting other information about the network. Matlab simulation is used to show the effectiveness of the FL-LEACH protocol compared with other protocols, such as the pure LEACH and the genetic-based protocol, LEACH-GA. Simulation results have shown that FL-LEACH outperforms LEACH and LEACH-GA in terms of network lifetime.

A novel approach for extracting spatial correlation of visual information in heterogeneous wireless multimedia sensor networks

In applied wireless multimedia sensor networks, heterogeneous camera nodes with different sensing capabilities are usually deployed due to their role in enhancing the overall network performance and lifetime. Exploiting the correlation characteristics of the overlapping fields of view of different camera nodes would enable very efficient collaborative in-network processing algorithms. This paper introduces a novel geometrical model to extract the spatial correlation characteristics of heterogeneous camera nodes in wireless multimedia sensor networks, taking into consideration the different sensing radii and the angles of view of the camera nodes. The novelty in the proposed model is in using virtual cameras at the two far ends of the cameras field-of-view. In order to provide better coverage of the field-of-view and hence better estimation of the correlation characteristics, key points in the observed scene are projected at the virtual cameras; in addition to the physical camera. This is shown to significantly improve the estimation of the spatial correlation characteristics to be almost identical to that extracted by well-known image processing techniques. An analytical closed-form solution of the proposed model is derived and validated and its performance is evaluated and compared against the state-of-the-art models; in terms of correlation characteristics estimating accuracy, visual information gain, and distortion ratio. The experimental and simulation results demonstrate that, compared to similar existing models, the proposed model achieves very accurate estimation of the correlation characteristics and significant improvement on the overall network resource utilization for a negligible increase in the camera nodes computational cost.

Opportunistic Network Coding for Real-Time Transmission over Wireless Networks

Network coding has shown a good potential for improving network throughput and, recently, has been used in multimedia transmission over wireless networks. In addition to guaranteed throughput, real-time multimedia transmission requires bounded delay, delay variation, and packet loss. This paper presents RTOC, a new XOR-based opportunistic network coding architecture for real-time data transmission. RTOC is an application-independent architecture that takes into consideration the characteristics of real-time traffic and provides an efficient framework to optimize multimedia application requirements such as bandwidth, delay, delay variation, and loss. The performance of RTOC was evaluated using simulated video streaming traffic. The results demonstrated that RTOC can improve the real-time performance metrics such as the packet delivery ratio, end-to-end delay, jitter, and throughput by considerable margins.

Experimental evaluation of image compression and transmission for TinyOS-based imote2 platform

In this paper, the performance of JPEG image compression and transmission using TinyOS-based Imote2 wireless sensor network platform is experimentally evaluated via a newly developed testbed. This testbed supports multihop sensor networks based on the Imote2 platform equipped with the Imote2 Multimedia Sensor Board. In addition, a standard JPEG library is embedded into the Imote2 platform to provide in-node image compression. The processing and transmission times, power consumption, and peak-signal-to-noise ratio performance metrics measurements are reported. The results show that the processing requirements are less than those of the transmission. According to the results, a tradeoff between the image quality and the energy and delay costs may be obtained.

An Energy-Balanced Cluster-Based Protocol for Wireless Sensor Networks

This paper proposes a novel energy-efficient clustering protocol for wireless sensor networks. It combines the benefits of using the k-means clustering algorithm with the, recently developed, LEACH with virtual forces LEACH-VF protocol. In this work, the k-means algorithm is employed to determine k centroids around which the clusters will be formed. After that, the virtual field force method is applied to these clusters to determine the most suitable positions for each node. The main target of such an approach is to improve the energy balance in the network and to extend the network lifetime. Simulation results show that the proposed protocol extends the time before the first node death, minimizes the variance of the average node energy, and reduces the distance that the sensor nodes travel within their respective clusters.

A Practical Study of Jointly Exploiting Multiple Image Compression Techniques for Wireless Multimedia Sensor Networks

In Wireless Multimedia Sensor Networks, the amount of multimedia traffic generated by the source nodes and relayed throughout the network towards the sink nodes is relatively vary large. As a result, the overall network performance and operational lifetime rely heavily on the efficiency and the complexity of the compression techniques used. However, known compression techniques have either high efficiency or low complexity but not both, which causes an imbalance in the distribution of the available network resources and hence shortens the network lifetime. In this work, a testbed to experimentally evaluate the performance and energy consumption of image compression and transmission was developed. Based on the testbed, the JPEG and JPEG2000 image compression algorithms were simultaneously embedded and evaluated with the purpose of jointly utilizing the features of both algorithms in order to facilitate a balanced tradeoff between the application performance requirements and the current network status. The analysis of the results verified that, in practical implementations of Wireless Multimedia Sensor Networks, using more than one compression technique by the same source node is feasible and has the potential of utilizing the capabilities of each technique based on the given situation.

A simulation testbed to jointly exploit multiple image compression techniques for wireless multimedia sensor networks

As the demand for large-scale wireless multimedia sensor networks increases, so does the need for well-designed protocols that optimize the utilization of available networks resources. This requires experimental testing for realistic performance evaluation and design tuning. However, experimental testing of large-scale wireless networks using hardware testbeds is usually very hard to perform due to the need for collecting and monitoring the performance metrics data for multiple sensor nodes all at the same time, especially the nodes energy consumption data. On the other hand, pure simulation testing may not accurately replicate the real-life scenarios, especially those parameters that are related to the wireless signal behavior in special environments. Therefore, this work attempts to close this gap between experimental and simulation testing. This paper presents a scalable simulation testbed that attempts to mimic our previously designed small-scale hardware testbed for wireless multimedia sensor networks by tuning the simulation parameters to match the real-life measurements obtained via experimental testing. The proposed simulation testbed embeds the JPEG and JPEG2000 image compression algorithms and potentially allows for network-controlled image compression and transmission decisions. The simulation results show very close match to the small-scale experimental testing as well as to the hypothetical large-scale extensions that were based on the experimental results.

A More Secure Image Hiding Scheme Using Pixel Adjustment and Genetic Algorithm

This paper proposes a more secure image hiding scheme using Optimal Pixel Adjustment Process (OPAP) and Genetic Algorithm (GA). The security issues of key selection that is used in image hiding are addressed. Thus, a more secure scheme is proposed in order to improve the security as well as the quality of the stego-image. Since GA is a semi-blind algorithm, it may select a key that affects the security. Therefore, the authores improve the security by applying image transformation not only using the GA key, but also using a user key. The user key is used to disarrange the pixel locations of the secret image. Then, the GA, using OPAP, selects the key that maximizes the quality as well as the security of the stego-image. From implementation point of view, the scheme uses a simple and fast transformation method that increases the difference between the secret image and its transformed version. The results showed that the resultant disarranged image cannot be detected, and at the same time the stego-image quality is still high.

Fuzzy Logic-Based Cluster Heads Percentage Calculation for Improving the Performance of the LEACH Protocol

In wireless sensor networks, cluster-based routing was proven to be the most energy-efficient strategy to deal with the scaling problem. In addition, selecting the proper number of clusters is a critical decision that can impose a significant impact on the energy consumption and the network lifetime. This paper presents FL-LEACH, a variant of the well-known LEACH clustering protocol, which attempts to relax the stringent strategy of determining the number of clusters used by LEACH via fuzzy logic decision-making scheme. This relates the number of clusters to a number of network characteristics such as the number of sensor nodes, the area of the sensing field, and the location of the base station. The performance of FL-LEACH was evaluated via simulation and was compared against LEACH using standard metrics such as network lifetime and remaining network energy. The results depicted that the proposed approach has the potential to substantially conserve the sensor node energy and extend lifetime of the network.