Jinsuk Baek

A strategic deployment and cluster-header selection for wireless sensor networks

A new cluster-based approach to increase the overall network lifetime of the wireless sensor networks is proposed in this paper. We first consider a strategic deployment especially when there are heterogeneous sensor nodes to be deployed. With the strategic deployment, the cluster header selection scheme is proposed. Unlike conventional approaches, we develop our scheme by designing the network with multiple-sized fixed grids while taking into account the arbitrary-shaped area sensed by the sensor nodes. Our simulation results show that the proposed scheme alleviates high energy consumption and a short lifetime of the wireless sensor networks supported by existing schemes.

Dynamic cluster header selection and conditional re-clustering for wireless sensor networks

We propose a new cluster header selection mechanism together with a new cluster formation scheme. With this scheme, each sensor node within a cluster evaluates its relative energy consumption compared to other nodes in a same cluster. Based upon the relative amount of energy consumption in the current round, sensor nodes autonomously select a time frame where they will act as a cluster header in that next round. In addition, they are conditionally allowed to switch their cluster header depending on the signal strength from their current cluster header. Our simulation results show the proposed scheme increases the network lifetime and provides a well-balanced energy consumption pattern among the nodes in a cluster compared to previously proposed schemes.

An auto-scaling mechanism for virtual resources to support mobile, pervasive, real-time healthcare applications in cloud computing

Cloud computing with virtualization technologies has become an important trend in the information technology industry. Due to its salient features of reliability and cost effectiveness, cloud computing has changed the paradigms of development for mobile pervasive services, effectively permeating the market. While most types of best effort mobile pervasive applications can be seamlessly migrated to cloud computing infrastructures, we need to consider specialized elements to make cloud computing infrastructures more effective in real-time healthcare applications. The client side of those applications dramatically increases its transmission rate whenever it detects an abnormal event. However, the existing server side mechanisms have limitations in adaptively allocating necessary computing resources in order to handle these various data volumes over time. In this article, we propose a novel server-side auto-scaling mechanism to autonomously allocate virtual resources on an on-demand basis. The mechanism is tested in an Amazon EC2, and the results show how the proposed mechanism can efficiently scale up and down the virtual resources, depending on the volume of requested real-time tasks.

(N, 1) secret sharing approach based on steganography with gray digital images

We present a description of a technique to embed secret data to an image, called information hiding or stegnography. We utilize some simple observed relationships between the binary representation of a pixel, the gray code representation, and the utilization of a simple Exclusive-OR operation based upon N images available to the sender and the receiver, called the cover images. We present the algorithms for embedding the secret data in the altered, last image, N+1, called the stego image; as well as extracting this data on the receiving side. We present some experimental images utilizing two cover images, and one stego image and show that the procedure we propose has a high PSNR value, and an almost identical histogram when compared to the before stego image. We also discuss the robustness of this algorithm under attack methods such as steganalysis.

A reliable overlay video transport protocol for multicast agents in wireless mesh networks

A new video transport protocol for multicast agents in wireless mesh networks (WMNs) is proposed in this paper. The proposed protocol enables a significant reduction in the transmission overhead, while providing reliable communication for its use in multicast applications. This proposed reliable protocol provides a practical approach for an overlay peer-to-peer multicast facility supported within the application layer. This obviates the need to give upgraded routers capable of handling multicast broadcasting or modify the existing protocol stack. The protocol tolerates partial losses in multimedia transmissions, while supporting control of the delay sensitivity of such transmissions in WMNs. The key issue in this protocol is the ability to detect packet loss, anticipate retransmission requests, and use the anticipated retransmission requests to transmit the lost packets prior to requests from other receiving agents. The proposed protocol allows for the receiver to determine if retransmission of lost packets is required, ensuring the greatest flexibility needed for a reliable multicast protocol. Copyright

A Lightweight SCTP for Partially Reliable Overlay Video Multicast Service for Mobile Terminals

In this article, a video multicast protocol for multi-homed mobile terminals is proposed as an alternative stream control transmission protocol (SCTP) for partially reliable multicast services. It works with overlay peer-to-peer video multicast facility in the application layer. For a multi-homed mobile terminal, an error burst may occur when a handover is in process in the primary path switching procedure. The key issue concerned in this protocol is the ability to predict packet loss and to retransmit the lost packets as soon as a mobile terminal completes its primary path switching procedure. This property controls the delay sensitivity of transmissions. Conversely, the protocol can tolerate partial loss in video transmission as long as the loss is limited to a relatively short error burst. In addition, it reduces the message overhead significantly and provides a scalable communication mechanism for multicast applications. The performance improvement of the proposed protocol comes from 1) the estimation of temporal velocity of mobile terminals with lost packet prediction in a long error burst, and 2) the requirement for each mobile terminal to indicate which packets can be safely discarded from its agent.

Motion recognition with smart phone embedded 3-axis accelerometer sensor

As the technology surrounding smart phone devices has changed over the past few years, we now find a device containing a collection of sensors. Indeed, one can say that the development of smart phones has been one of the most important advances in science and technology. We will show an additional usage for the smart phone: utilizing it for a generic, hardware, gaming controller. We will show how a motion recognition mechanism can be used for determining rate of change and position of the phone as it moves in 3D-space using the embedded 3-axes accelerometer sensor. Upon sensing a users motions with the smart phone, the corresponding accelerometer values are transmitted to the gaming console through the Wi-Fi communication. Motion recognition is then performed at the gaming console using a pattern matching mechanism. The proposed mechanism is applied to the game of tennis to recognize three primary ground stroke motions: the forehand stroke, backhand stroke, and service. With individual calibration for these three motions, we show how accurately the system can recognize the motions, and derive ball-hit likelihood. These types of results, when fully realized, can provide a much richer and simpler experience for the user.

A Fair Transmission Opportunity by Detecting and Punishing the Malicious Wireless Stations in IEEE 802.11e EDCA Network

We propose a malicious detection algorithm that permits identification of misbehaving wireless stations, and then dispenses punishment by denying an ACK packet which allows transmission by the malicious stations. The proposed algorithm is designed for an IEEE 802.11e network and is based upon detecting a change in quality of service (QoS) where a station is moved up in terms of permission to a level not justified. Non-detection causes honest stations to increase their retransmit attempts, exceeding the specified deadline in order to sustain continuous receipt of their data. Even with the coexistence of such malicious stations, our algorithm guarantees the lower bound of performance degradation to the honest stations. Also, the punished period imposed upon the malicious stations compensates the experienced degradation in QoS for the honest stations in the next transmission period. As a result, we provide fair resource sharing among the stations operating from the same access point. Our simulation within the ns-2 framework of the IEEE 802.11e enhanced distributed channel access network shows how our algorithm actually detects and adjusts the punishment phase for stations that may be misbehaving as well as stations which are misbehaving.

Dynamic cluster header selection with self-incentive for wireless sensor networks

The unbalanced energy consumption among self-powered sensor nodes negatively impacts network lifetime. In order to overcome this limitation, we propose a new cluster header selection and cluster formation scheme. With our scheme, sensor nodes within a cluster autonomously decide in which time frame they will act as a cluster header based on the amount of energy consumption in the current round. In addition, they are conditionally allowed to switch their cluster header depending on signal strength of their current cluster header. Our simulation results show the proposed scheme increases the network lifetime and provides a well-balanced energy consumption pattern among the nodes in a cluster compared to previously proposed schemes.

An Adaptive Primary Path Switching Scheme for Seamless mSCTP Handover

In this paper, a primary path switching scheme is proposed to provide a seamless handover for dual-homed mobile terminals. This scheme is proposed as an enhancement to the mSCTP protocol. With this scheme, a mobile terminal performs primary path switching before it becomes unavailable due to its primary path drop. The improvement achieved by the scheme is that it considers the temporal velocity of the mobile terminal with relative RTT variances of all available paths when it performs the handover process in the overlapped area between two different networks. Our simulation results show that the proposed scheme achieves a better overall performance than other schemes, and anticipatory switching is more important for faster moving terminals.