Emerging Directions in Embedded and Ubiquitous Computing

In ad-hoc networks, routing is one of the most important issues, and various protocols are proposed. However, as situations and topologies of an ad-hoc network are various and dynamic, it is difficult for a single fixed protocol to perform well for all occasions. Therefore, some dynamic and adaptive mechanism in routing protocols is necessary. In this paper, we propose an adaptive routing system for ad-hoc networks. This system begins in the same manner as a reactive protocol, and when the network situation gets unsuitable for the protocol, the system changes its manner of routing with a router-node, or a pseudo cluster-head in Cluster-based Routing, which emerges autonomously at the place of “hot spots” in the network. This paper presents its principle, design, and some preliminary experiment results.

In P2P network, there are a considerable proportion of free riders, which contribute nothing or little to the P2P system but obtain resources from the system. In order to address this problem, we present a utility-based auction cooperation incentive mechanism in the P2P network. Our approach is that before communicating with destination peer, the source peer first demands peers to auction their utilities, and then select the maximum utility as its destination peer, and gives some benefit to it, at the same time, gives some punishment to the liars. By using this mechanism, the more the peers contribute to the system, the more utility the peers can obtain, and therefore, the more benefits the peers can gain from the system. The experiment results show that the incentive mechanism assures the justice of gaining benefits for different kinds of peers in the system, and hence, controls the free riders effectively, and improves the whole performance of the P2P network.

Mobile devices have difficulty in sustaining various services as in a wired environment, due to the storage shortage of the mobile device. The research[8] which provides remote storage service for mobile appliances using iSCSI has been conducted to overcome the storage shortage in mobile appliances. In research the proposed cache server performed well with relatively small files of sizes, however, did not perform well with large files such as database files, multimedia files, etc. The reason was the mobile device could not grasp the file as a whole and thus the cache server encountered frequent cache miss in spite of its huge buffer. In this paper we propose a proxy server that accommodates large files for mobile devices thus attains very high hit ratio.

We study the maximization of throughput and energy utilization in noisy wireless channels by adjusting packet length adaptively to network instant statistics. The optimal packet length adaptation (PLA) for throughput and energy utilization in wireless networks with and without re-transmission is respectively derived and developed. As more noises introducing more energy consumptions, the noises are equivalently regarded as lengthening of transmission distances. Therefore, an equivalent distance model of noisy channels is developed for more accurate estimation of the dissipated proportion in the residual energy such that further improvement of energy utilization and throughput is obtained. We integrate the PLA with the energy-proportional routing (EPR) algorithm for best balance of energy load. Therefore, performance metrics such as lifetime extension, throughput, and energy utilization are maximized even the distribution of channel noise is so un-predictable. Since the equivalent distance is dynamic, we believe that it is useful for network topology re-organization and will be useful in the future work of mobile ad-hoc networks.

In order to develop a variety of context-aware application systems, we require a context script language to describe both various decisions on context-awareness and appropriate procedures according to the decision. In this paper, we propose a new context script language which can represent a variety of contexts as a standard syntax. The proposed context script language is a general purpose one to provide users with functions to define a given context in a clear and precise manner. To show the usefulness of the proposed context script language, we develop a context-aware application system using it, which can provide users with a music playing service in ubiquitous computing environment.

Object replication is an important and sophisticated question, it can reduce access latency and bandwidth consumption, replication can also help in load balancing and can improve reliability by creating multiple replicas of the same storage object. But there are many difficulties to realize object replication in efficiently. In this paper, we discuss the architecture of object storage system with object replication, and analyze key question of dynamic replication such as replica granularity, When to replicate storage object and Where to place the replicas etc.. In the theory, we give the formulas of these question, the analysis prove these formulas are reasonable.

A mobile network is an entire network, moving as a unit, which dynamically change its point of attachment to the Internet and its reach-ability in the topology. Network Mobility is thus the opportunity to realize the Ubiquitous Internet, i.e. permanent access anywhere at anytime, in fixed locations and while on the move, provided that any available access network can be accommodated. In this paper, we propose a cost-effective mobility modelling in nested Network Mobility which is based on binding update multi-cast by various mobility patterns of mobile nodes in nested Network Mobility. This proposed scheme is combined Hierarchical Mobile IPv6 with Network Mobility because a mobile networks and mobile nodes move in tandem and create a hierarchy in the wireless network to management of micro-mobility and seamless handoff. These issues are focuses on the area of mobility modelling in nested Network Mobility. We address the key function for our proposed scheme and simulate the usefulness of our proposed method using mathematically analyze. We then testify that the proposal has best performance compared with Network Mobility protocol.

To free analysts from knowing about the internal details of middleware when evaluating the performance of component-based system (CBS), this paper proposes a framework to automatically integrate middleware component interactions and their performance attributes to application Unified Model Language (UML) model. The framework defines a general sub-model template library of middleware, a middleware usage description file, and an approach to compositing application-specific sub-model instances and application UML models. The process is illustrated by a case study.

In the IEEE 802.15.3-based HR-WPAN(High Rate Wireless Personal Area Networks), the selection of PNC is based on the capability of each DEV in the piconet. The selected DEV playing the role of a PNC will consume the most amount of energy among the DEVs in the piconet. Since the energy consumption of the PNC is closely related to its frame transmission range in the piconet, it is important to consider the relative location of each DEV when selecting the PNC among DEVs. In this paper, we propose a novel approach to the PNC selection procedure in the piconet that attempts to position the PNC at the center of the topology. By doing so, it can minimize the total transmission distances from the PNC to all other DEVs, resulting in saving energy for the PNC and therefore extending the life-time of the PNC as well as the piconet. We describe our method in detail and present experimental results that show the significant improvement in the energy saving.

In wireless ad hoc networks, many multicast routing protocols are proposed such as ODMRP, MAODV, etc. In general, the IEEE 802.11 standard is assumed as a MAC protocol in those protocol and multicast data packets are transmitted at the basic transmission rate which is 2Mbps at the IEEE 802.11 or 802.11b. However, if the multicast packet can be transmitted at higher transmission rates than 2Mbps in a multi-rate WLAN such as IEEE 802.11b, we can achieve higher throughput gain and lower transmission delay than those at 2Mbps transmission rate. In this paper, we propose a new multicast routing protocol in multi-rate wireless ad hoc networks. In the proposed protocol, we design a multicast mesh creation method considering multiple transmission rates between any two nodes in the ad hoc networks. We also design a multicast mesh maintenance scheme when the transmission rate between two nodes comprising a multicast mesh is changed because of node mobility. The performance of the proposed protocol is compared with ODMRP using ns2 simulation, and the proposed protocol shows higher packet delivery ratio and lower end-to-end delay than the ODMRP.

Various network technologies have been developed towards ubiquitous computing. Actually, the specific network technology has its own protocol layer, characteristics and objectives. Due to these limitations, though cellular network and WPAN are being used in handset together, the services using both networks are not so popular until now. This paper presents a platform design integrating cellular network and WPAN and its application to the mobile game service. To develop services and applications which utilize cellular network and WPAN, we discuss the WPAN platform for handset. Various aspects are considered on the connection, which can expand the area of mobile services and applications. An illustrative application of this platform is introduced as a mobile game service. In the proposed game service, downloading games or game items, managing players, etc. are provided using cellular network. The actual game traffic between players utilizes WPAN. As shown in the proposed game service design, various applications are being expected through the WPAN platform.

Owing to the inflexibility of the structure, the conventional layered protocols suffer from the inability to distinguish between losses due to route failures and congestion. Recently, in efforts to overcome the challenges of dynamic environment in ad hoc networks, there have been increased interests in protocols that rely on interactions between different layers. In this paper, we propose a cross-layer architecture combining the three layers of data link, network, and transport in order to provide reliable transporting and optimal routing on rate-based, termed as RTOR. In accordance with the rate computed at MAC layer, a path with the optimal rate is selected at network layer. While the flow control and reliability is performed by the determination of transmission rate and SACKs at transport layer, respectively. The transport protocol herein is not a variant of TCP but a rehash. In flow control, the transmission rate is adjusted by rate feedback instead of AIMD congestion windows. In reliability, SACK blocks appended to feedback packet are used rather than implication of packet lost by duplicate ACKs. In addition, choosing a path with the optimal rate can balance the network load in an appropriate degree. The evaluation results clearly indicate the significant performance improvement that RTOR provides over default TCP, TCP-ELFN, and ATP.

While web service technology is becoming a de facto standard for integration of business applications, it is also rapidly emerging as an effective means for achieving inter-operability among the devices in network centric ubiquitous systems. When such a web service enabled device engages in a conversation with a service provider, it becomes necessary to define an interaction logic required between them. For this purpose, one can use a choreography language to specify the rules of engagement between the device and the web service provider. This paper presents a framework for automatically synthesizing conversation protocols from a choreography description defined in WS-CDL. The proposed framework adopts WSCL as a conversation protocol language, and defines a set of rules that can be used to effectively transform a WS-CDL specification into WSCL documents for collaborating peers. It is expected that the work presented in this paper can enhance the interoperability between web service-based processes in ubiquitous systems through automating the process of extracting conversation protocols from a choreography definition.

In this paper, a network-centric subcarrier allocation method is proposed for triple-sectored Orthogonal Frequency Division Multiple Access (OFDMA) systems. The proposed method is based on a network-centric algorithm that is located in a base station (BS) and coordinates the subchannel allocation of each sector. This method controls the resources (subchannels) allocated to each sector, not to waste available bandwidth and avoid inter-sector interference as much as possible. Two methods are suggested for the subchannel allocation method and the detailed algorithms for each method are provided. Simulation results show that the suggested method achieves better throughput than the distributed subchannel and adjacent subchannel configuration methods under a proportional fair algorithm.

Sharing files discovery is a fundamental problem in P2P networking. This paper presents a name-based approach for identifying sharing file correspondences in multilingual P2P systems. The problem is first analyzed through comparing the names of the sharing files in different nodes of a real P2P community, which name those files in different languages. Then based on the relationships of those files names, a computer-aided method is proposed to solve the problem. Furthermore, the framework and identifying procedure of this method have been discussed in the paper.

Gigabit Ethernet has become the main cluster interconnection for its low price and well backward compatibility. But the communication performance through Gigabit Ethernet is quite disappointing due to its performance discre- pancies between the hardware and the communication software. To achieve over two-third physical bandwidth of a gigabit network interface, zero-copy protocol architecture is absolutely necessary. Unfortunately, it is impossible to realize true zero-copy communication over non re-programmable commodity Gigabit Ethernet adapters because the DMA engines cannot separate the protocol headers from the payload data directly. This paper introduces LM (Lightweight Messages), a true zero-copy communication mechanism which combines the application level fragmentation scheme with the driver level defragmentation scheme, for existing non-programmable Gigabit Ethernet adapters. Finally, experimental results show that LM can provide better performance than other lightweight communication approaches over commodity Gigabit Ethernet.

Evaluating the efficiency of unguided search based on random walk in unstructured peer-to-peer networks is important because it provides guidelines in correctly setting the parameters of the search. Most existing work is based on simulations. We evaluate two analytical models – the algebraic model and the combinatorial model – for various search efficiency metrics against simulation results. We use the random graph topology and assume unguided searches. The results show that the two analytical models are accurate and match each other closely. We study the impact of the average node degree, hop count, number of walkers, and replication ratios on node coverage, object recall, and message efficiency, and on the accuracy of the models.

A middleware in ubiquitous computing environment (UbiComp) is required to support seamless on-demand services over diverse resource situations in order to meet various user requirements [11]. Since UbiComp applications need situation-aware middleware services in this environment. In this paper, we propose a semantic middleware architecture to detect errors, analyze causes of errors, and plan semantically meaningful strategies to deal with a problem with associating fault and service ontology in UbiComp environment. We implemented a referenced prototype, Web-service based Application Execution Environment (Wapee), as a proof-of-concept, and showed the efficiency in runtime recovery.

A fundamental feature of Peer-to-Peer (P2P) networks is the honest collaboration among an heterogeneous community of participants. After

Napster

success –the first P2P file sharing application massively used–, advances in this area have been intense, with the proposal of many new architectures and applications for content and computing sharing, and collaborative working environments. However, the inherent differences between the P2P model and the classic client-server paradigm cause that many security solutions developed for the latter are not applicable or, in the best case, have to be carefully adapted. In this paper, we present a survey on security issues in P2P networks, providing a comparative analysis of existing solutions and identifying directions for future research.

The envisioned realization of ubiquity has resulted into the emergence of new kinds of the hybrid networks. The modern hybrid networks, e.g. combination of wireless mesh and Mobile Ad-hoc Networks (MANETs), help realize ubiquity through spontaneous networking. The network management for these hybrid networks is different from conventional and infrastructure based network management. Heterogeneity, mobility, dynamic topologies, physical security, and survivability make the challenge hard. A new class of management called self-management can effectively be used to cater for the autonomous behavior of hybrid networks

.

We present HYbrid WIreless Network Management ARChitecture (HYWINMARC), a three-tier framework, covering all the management levels, for autonomic network management for hybrid networks. We integrate policy-based network management with mobile-agent technology and design a prototype for a context-aware and self-managing architecture. The context information is collected, from all levels in network hierarchy through monitoring agents, and is used to apply needed self-management operations that include self-optimization, self-healing, self-configuration, and self-growing.

Predictive

p

-persistent CSMA protocol is an important MAC solution developed for networked sensor/control applications and used in Local Operating Networks (LonWorks) technology. The protocol uses a built-in network load prediction to support collision avoidance. The paper presents an analytical study of prediction efficiency for a channel with collision detection. The approach based on Markov chains is applied. The procedure of performance analysis includes the definition of transition probabilities of Markov chain for a specified load scenario, calculation of stationary distribution of contention window, and the probabilities of successful/unsuccessful transmission. It is shown that the predictive

p

-CSMA protocol manages to control the size of a competition window in order to guarantee the sustained probability of a successful transmission. The simulative validation of analytical results is provided.

The mobile internet environment which is in the limelight as the important platform of the ubiquitous environment gets accomplished by the intimate relation with user. In order to realize the interaction between device and user, it is considered that resource of exterior/interior user information which can be collected by mobile device and the situation-aware (SA) personalization is suggested by applying the context set of collected current situation to the concept of situation-aware. Such a SA personalization is designed to offer advanced personalization using Link Retrieving Algorithm which is emphasized on prospecting. And the Markov Chain Model, prospecting matrix system, is used to support the SA personalization. Using SA personalization system, the custom service which is well-matched on the ubiquitous era and founded on user’s current situation will be offered.

Currently, there are a lot of e-learning and collaborative platforms to support distance and collaborative learning, however, all of them were designed just like an application without considering the network infrastructure below. Under these circumstances when the platform is installed and runs in a campus, sometimes it has very poor performance. This paper presents a network and data link layer infrastructure design that classifies and prioritizes the voice and video traffic in order to improve the performance and QoS of the collaborative systems applications. This infrastructure has been designed taking in consideration a typical network of a university campus, so that in this way it can be implemented in any campus. After making the design we have made some tests in a laboratory network demonstrating that our design improves 70-130% the performance of these real time collaborative systems which transmit voice and video.

Recently, the demands on information services have been increasing significantly. This is mainly due to the popularization of computer and mobile telecommunication devices and the rapid improvements on wireless communication technology. Specially, information services and their corresponding management for mobile devices, such as Location Based Service (LBS) and Telematics, become more and more important. However, the standard for geographical space data has not been finalized. Many commercial monitoring systems are using their own independent geographical information without making them compatible to others. Much efforts and resources have been wasted on managing and operating those different monitoring systems’ geographical Information System (GIS) databases. Accordingly, a standard format called GML, based on the most commonly used geographical data format such as DXF, DWG and SHP, has been emerged. In this paper, our work on GML’s visualization in Trace Monitoring Systems (TMS) is described fully. The details on how to trace and manage data moving among different mobile terminals are presented as well.

Denial-Of-Service (DOS) attack is recognized as a biggest threat against the operation of large-scale wireless sensor networks (WSN). Especially, high-mobility radio jamming like vehicles carrying radio jamming device can cause a serious damage in performance of WSNs. Because of resource-constraint design of sensor node, it is hard to provide enough protection against high-mobility jamming attack. Therefore, large-scale WSNs are extremely vulnerable to that type of DOS attack. Recognizing the importance of the problem, we conducted a simulation study to investigate the impact of radio jamming on the performance of a large-scale WSN. Based on the simulation results, the moving speed of radio jamming source has the most conspicuous effects on the WSN performance such as packet delivery success ratio and delay. As the speed changes from 8 m/sec to 1 m/sec, the success ratio drops by up to 10%. On the other hand, the delay increases by up to 55%.

RFID (Radio Frequency Identification) is recently becoming popular, promising and widespread. In contrast, RFID tags can bring about traceability that causes user privacy and reduces scalability of RFID. Guaranteeing untraceability and scalability at the same time is so critical in order to deploy RFID widely since user privacy should be guaranteed. A large number of RFID protocols were designed in the open literature, but any known protocols do not satisfy untraceability and scalability at the same time to the best of our knowledge. In this paper, we suggest a RFID authentication protocol that guarantees untraceability and scalability together; needless to say preventing several known attacks: replay, spoofing, desyncronization, and cloning by eavesdropping. Our protocol supports ownership transfer and considers multi-tag-reader environment; a reader receives messages from the tags what a reader wants in our protocol. In addition, we address the reason why the item privacy is important, and a way to keep it securely.

In this paper, we analyze the security of the RFID authentication protocol proposed by Choi

et al.

at SecUbiq 2005. They claimed that their protocol is secure against all possible threats considered in RFID systems. However, we show that the protocol is vulnerable to an impersonation attack. Moreover, an attacker is able to trace a tag by querying it twice, given the initial information from

$2^{\lceil(log_2(\ell+1)\rceil)}$

+ 1( ≈ ℓ + 2) consecutive sessions and 2 ·

$2^{\lceil log_2(\ell+1)\rceil}$

( ≈ 2(ℓ + 1)) consecutive queries, where ℓ is the length of secret values (in binary).

Due to the low-cost nature of sensor network nodes, we cannot generally assume the availability of a high-performance CPU and tamper-resistant hardware. Firstly, we propose a reliable broadcast message authentication working under the above-mentioned circumstances. The proposed scheme, although based on symmetric cryptographic primitives, is secure against anyone who knew the message authentication key as well as the malicious router nodes in multi-hop networks. The proposed scheme consists of three steps; (i) reliable broadcast of a message, (ii) legitimate acknowledgments from all the nodes in the network, and (iii) disclosure of the message authentication key. Secondly, we propose a way to reduce the amount of the stored information until the disclosure of the key, in which the server transmits the message integrity code of a message before transmitting the message. Finally, we consider the characteristic and the security issues of the proposed schemes.

In distributed sensor networks, the researches for authentication in sensor network have been focused on broadcast authentication. In this paper, we propose a message and its origin authentication protocol for data aggregation in sensor networks, based on one way hash chain and Merkle tree authentication with pre-deployment knowledge. Proposed protocol provides not only for downstream messages but also for upstream messages among neighbors, and it solves the secret value update issue with multiple Merkle trees and unbalanced energy consumption among sensor nodes with graceful handover of aggregator. In treating compromised node problem, our protocol provides an equivalent security level of pair-wise key sharing scheme, while much less memory requirements compared to pair-wise key sharing scheme.

In this paper, we describe the design and implementation of a new security protocol based on Elliptic Curve Cryptosystems (ECC) for securing Wireless Sensor Networks (WSNs). Some public-key-based protocols such as TinyPK and EccM 2.0 have already been proposed in response. However, they exhibit poor performance. Moreover, they are vulnerable to man-in-the-middle attacks. We propose a cluster-based Elliptic Curve Diffie-Hellman (ECDH) and Elliptic Curve Digital Signature Algorithm (ECDSA) for efficiency and security during the pairwise key setup and broadcast authentication phases, respectively. We have implemented our protocol on 8-bit, 7.3828-MHz MICAz mote. The experimental results indicate the feasibility of our protocol for WSNs.

A new multicast authentication scheme for real-time streaming applications was proposed [28] that is resistant to denial-of-service attacks with less resource usages (CPU and buffer) at receivers compared to previously proposed schemes. This scheme utilizes prediction hashing (PH) and one-way key chain (OKC) techniques based on erasure codes and distillation codes. Detailed protocol description is presented at the sender and receiver sides, and a worst-case resource (memory and CPU) requirement at the receiver-side is obtained with an assumption of security condition.

The range of devices that are capable of connecting to data networks has been on a rise in recent times. From the perspective of an administrator, controlling access to data networks, via these devices, usually includes the creation of separate login credentials. This leads to an administrative nightmare, from both the user and administrator’s point of view. This paper proposes a novel approach to this problem and offers a single-sign-on system, where the user’s authorisation is based on the login credentials of the user, and the profile of the device the user is using. An instance of this design is presented with SESAME, to demonstrate the usefulness of the design, and also practicality for implementation.

Certificateless public key cryptography (CLPKC) is a paradi-gm to solve the inherent key escrow problem suffered by identity-based cryptography (IBC). While certificateless signature is one of the most important security primitives in CLPKC, there are relatively few proposed schemes in the literature. In this paper, we manage to construct an efficient certificateless signature scheme based on the intractability of the computational Diffie-Hellman problem. By using a shorter public key, two pairing computations can be saved in the verification algorithm. Besides, no pairing computation is needed in the signing algorithm. The proposed scheme is existential unforgeable in the random oracle model. We also present an extended construction whose trust level is the same as that of a traditional signature scheme.

This paper first introduces the concept of universal designated verifier ring signature (UDVRS), which not only allows members of a group to sign messages on behalf of the group without revealing their identities, but also allows any holder of the signature (not necessary the signer) to designate the signature to any designated verifier. According to whether the designator has a registered public key, two kinds of UDVRS are proposed. In order to distinguish the two types of UDVRS, we call it UDVRS Proof (UDVRSP) if the designator has not a registered public key, and this protocol is interactive. We give the formal security definitions and notions of UDVRS and UDVRSP. Then, we propose a UDVRS and a UDVRSP scheme, with rigorous security proofs without random oracles.

In this paper, we give a new identity-based signcryption scheme based on pairings. It is secure against adaptive chosen ciphertext and identity attack in the random oracle with the Modified Bilinear Diffie-Hellman assumption [14]. It produces shorter ciphertext than any one of schemes [7],[14] for the same plaintext and adapts to the band-constrained scenario very well.

Key-insulated cryptosystem was proposed in order to minimize the damage of secret key exposure. In this paper, we propose a strong identity based (ID-based) key-insulated cryptosystem security model, including ID-based key-insulated encryption (IB-KIE) security model and ID-based key-insulated signature (IB-KIS) security model. Based on the security models, provably secure strong IB-KIE and IB-KIS schemes are constructed in order to decrease the damage of user’s secret key exposure. These schemes are secure in the remaining time periods against an adversary who compromises the insecure device and obtains secret keys for the periods of its choice. Furthermore, the schemes remain secure (for all time periods) against an adversary who compromises only the physically-secure device. All the key-insulated encryption and signature schemes in this paper are provably secure in the random oracle model and support random-access key-updates.

A new hierarchical identity based (ID-based) cryptosystem is proposed, including hierarchical identity based encryption (HIBE) and signature (HIBS) schemes. The new HIBE scheme can be proved to be secure without relying on the random oracle model. Then, a new public key encryption (PKE) scheme is constructed based on the new HIBE. It is secure against adaptively chosen ciphertext attacks (IND-CCA) and has many attractive properties, such as efficient key generation, short private key, fast encryption, and etc. Performance of the new PKE scheme is better than all the previous PKE schemes converted from IBE, and is competitive with the best provably secure solutions to date. Furthermore, a new HIBS scheme is also constructed, which shares the same parameters with the new HIBE. The new HIBS scheme is more efficient than the previous HIBS.

Wireless sensor networks and Radio Frequency Identifiers are becoming mainstream applications of ubiquitous computing. They are slowly being integrated into our infrastructure and therefore must incorporate a certain level of security. However, both applications are severely resource constrained. Energy scavenger powered sensor nodes and current RFID tags provide only 20

μ

W to 50

μ

W of power to the digital component of their circuits. This makes complex cryptography a luxury. In this paper we present a novel ultra-low power SHA-1 design and an energy efficient ultra-low power AES design. Both consume less than 30

μ

W of power and can therefore be used to provide the basic security services of encryption and authentication. Furthermore, we analyze their energy consumption based on the TinySec protocol and come to the somewhat surprising result, that SHA-1 based authentication and encryption is more energy efficient than using AES for payload sizes of 17 bytes or larger.

Lately, the ISO fixed on UHF Gen2 as one of the standard protocols for RFID, called ISO 18000-6 C, along with ISO 18000-6 A/B. It means that the RFID system should provide the multi-protocol support for tag identification and a proper protocol should be chosen depending on the situation. The tag anti-collision algorithm is one of the important research issues to be on top of the protocol’s performance. This paper introduces several anti-collision algorithms for tag identification in the literature and presents the performance comparison and evaluation of those algorithms based on the 96-bit EPC

TM

(Electronic Product Code

TM

). The performance results show that the collision tracking tree algorithm is found to have the highest performance than any other anti-collision algorithm, identifying 749 tags per second.

RFID reader networks often have to operate in frequency and time constrained regimes. One approach to the allocation of frequency and time to various readers in such regimes is to perturb the network slightly so as to ease the constraints. We investigate how to perform these perturbations in a manner that is profitable from time and frequency allocation point of view.

In RFID system, one of the problems that we must solve is the collision between tags that may occur when a reader attempts to read a number of tags simultaneously. Most of the popular anti-collision algorithms are based on the ALOHA-type algorithm, which are simple and show good performance when the number of tags to read is small. However, for ALOHA-type algorithms the time required to read the tags generally increases exponentially as the number of tag increases. Thus, they are not very efficient when the number of tags to read is large. In the paper, we propose a new anti-collision algorithm called Enhanced Dynamic Framed Slotted ALOHA (EDFSA) in which the time required to read the tags increases linearly with the number of tags. The proposed algorithm estimates the number of unread tags first and adjusts the number of responding tags or the frame size to give the optimal system efficiency. Simulation results show that the proposed algorithm improves the reading rate of data of the tags by 85~100% compared to the conventional algorithms.

Advances in wireless and mobile communication technologies have enabled the development of various RFID-based systems and applications in addition to the extension of the tag reading range of mobile readers. Thus, it has become commonplace that multiple readers concurrently attempt to read tags within ranges of the readers. However, this concurrent access among multiple mobile readers brings about a new problem called reader collision, where a reader’s transmission is interfered by other readers. There have been several studies focusing on solving the reader collision problem. These studies employ time division, frequency division, space division, or the centralized scheduling approach. In this paper, a cooperative, distributed reader collision avoidance algorithm is introduced. In particular, the proposed DiCa (Distributed Tag Access with Collision-Avoidance) is considerably suitable for energy-efficient wireless mobile network environments cooperated with RFID, since the DiCa is capable not only of avoiding collisions, but also changing power states autonomously through simple interaction of adjacent readers.

In this paper, we present a high-speed RFID data filtering engine designed to carry out filtering under the conditions of massive data and massive filters. We discovered that the high-speed RFID data filtering technique is very similar to the high-speed packet classification technique which is used in high-speed routers and firewall systems. Actually, our filtering engine is designed based on existing packet classification algorithms, Bit-Parallelism and Aggregated Bit Vector (ABV). In addition, we also discovered that there are strong temporal relations and redundancy in the RFID data filtering operations. We incorporated two kinds of caches, tag and filter caches, to make use of this characteristic to improve the efficiency of the filtering engine. The performance of the proposed engine has been examined by implementing a prototype system and testing it. Compared to the basic sequential filter comparison approach, our engine shows much better performance, and it gets better as the number of filters increases.

Radio Frequency Identification (RFID) systems have become popular for identifying not only objects but also persons. For example, in supply chain applications, the company can constantly track the movements of goods. Also, for Body Area Network or Personal Area Work, the tag is used for identifying a person. However, the movements and current locations of goods and a person’s activity profiles are the sensitive information and should be kept secret. This paper develops the interaction protocols between readers and tags to address this privacy issue of protecting tagged objects from tracking and tracing by non-authorized readers.

In this paper, we propose a new medium access control protocol for wireless sensor networks, named LE-MAC (Latency and Energy aware MAC) that aims to minimize data delivery latency as well as energy consumption. To achieve both goals, we exploit a physical carrier sensing feature in CSMA/CA and combine it with a cross-layer technique. When nodes that are in routing path between source and sink become aware of the traffic based on the carrier signal, they wakeup once more during the sleep period for transmitting data over multiple hops. We evaluated the proposed scheme compared with S-MAC on the ns-2 simulator. The results show that our scheme outperforms S-MAC protocols in balancing the need of low latency and energy consumption.

In this paper, we propose a new self-organization scheme, DICSION (Data-centrIC Self-organizatION), which can improve the energy efficiency and prolong network lifetime of wireless sensor networks. Since a large number of sensor nodes are densely deployed, neighboring nodes may be very close to each other. Therefore, we assume that sensor nodes have a high possibility to collect the duplicate data about the same event. DICSION can considerably reduce the energy consumption because a zone head only can transmit and receive a representative data to base station or neighboring zone heads after zone formation. Our performance evaluation results demonstrate that DICSION outperforms to STEM.

Wireless sensor network consisting of a large number of small sensors is efficient in gathering data in a variety of environments. Since the sensor nodes operate on batteries, energy efficient operations are indispensable to maximize the lifetime of the network. Among the schemes proposed to improve the lifetime of the network, the cluster-based schemes aim to evenly distribute the energy consumption among all the nodes in the network. In this paper we propose an approach for finding an optimal number of clusters which allows minimal energy consumption of the network. The key idea of the proposed approach is to model the energy consumption with independent homogeneous spatial Poisson process, while considering the distribution of cluster-heads and other sensor nodes. With the number of cluster-heads obtained by the proposed approach, the energy consumption can be significantly reduced and consequently the lifetime of the sensor network is increased compared to the existing schemes. Computer simulation confirms this with practical operational environment.

When deploying sensors in the field in order to collect useful information, one of the most important issues is how to prolong the lifetime of the network because of energy constraint of the sensors while guaranteeing that every point in the network is covered. In this paper, we propose the formulation of integer linear programming (ILP) model to find the optimal network flow in the sensor fields in order to maximize the network lifetime while maintaining the coverage and connectivity. By dividing the network into grid structure, the problem can become manageable in size and complexity thus can be applied to large network with high number of nodes. The experimental results show that our proposed scheme outperforms previous protocols in terms of coverage lifetime.

Utilization of an ultrasound tracking system in wireless sensor networks is a well-known technique with low-cost and high-accuracy advantages in an indoor environment. In this paper, we present the implementation of an active tracking system based on an ultrasonic sensing device using the IEEE 802.15.4 compatible radio. IEEE 802.15.4 is used in wireless sensor networks because of its low power consumption and high bit-rate. Many of the technical issues for actual deployment of the system in an indoor environment are herein analyzed and solved.

In many applications of wireless sensor networks (WSNs), the location information of users is very important. In this paper we present a localization method without on-body sensor (LWOS). The basic idea is that when a person is standing between a pair of transceivers, the human body will attenuate the received signal. From the detected attenuation of Received Signal Strength Indication (RSSI), LWOS can detect and localize people directly utilizing the wireless communication in WSNs. No additional sensor is needed and users do not need to wear a sensor node any more. A signal-shielding device is used at the transmitter side to minify the interference of RSSI variability from multi-path effects. Experiment results show a good capability of localizing a single user in an indoor environment.

“Ubiquitous” has been the key buzzword in the research community as well as in everyday life these days. In Korea, ubiquitous become decorative words for many new products, which has not necessarily enough link to the world of ubiquitous. In research field, many public, private sectors research activities decorated with the word of “ubiquitous” has drawn so much attention, but still, little examples are shown which truly implements the ideals of “Ubiquitous”. In this paper, we review the research activities under the flag of “ubiquitous”, and then present possible research directions for proper research directions which can prompt practical incorporation of ubiquitous concept in the near future.

Sensor networks are characterized by their large-scale and unattended deployment that invites numerous critical attacks, thereby necessitating high-level security support for their intended applications and services. However, making sensor networks secure is challenging due mainly to the fact that sensors are battery-powered and it is usually very difficult to change or recharge their batteries. In this paper, we give a comprehensive overview of recent research results for securing such sensor networks, and then describe how to build a security framework, called a

Lightweight Security Architecture

(LiSA), for sensor networks, which achieves

energy-aware security

via closely-coupled, mutually-complementary security solutions.

In mobile ad hoc networks, mobile devices wander autonomously for the use of wireless links and dynamically varying network topology. AODV (Ad-hoc on-demand Distance vector routing) is a representative among the most widely studied on-demand ad hoc routing protocols. Previous protocols have shown some shortcomings on performance. AODV and most of the on-demand ad hoc routing protocols use single route reply along reverse path. Rapid change of topology causes that the route reply could not arrive to the source node, i.e. after a source node sends several route request messages, the node obtains a reply message, especially on high speed mobility. This increases both in communication delay and power consumption as well as decrease in packet delivery ratio. To avoid these problems, we propose a reverse AODV which tries multiple route replies. The extended AODV is called reverse AODV (R-AODV), which has a novel aspect compared to other on-demand routing protocols on Ad-hoc Networks: it reduces path fail correction messages and obtains better performance than the AODV and other protocols have. We design the R-AODV protocol and implement simulation models using NS-2. Simulation results show that the reverse AODV provides good experimental results on packet delivery ratio, power consumption and communication delay.

Currently, the IETF group is working on service differentiation in the Internet. However, in wireless environments such as ad hoc networks, where channel conditions are variable and bandwidth is scarce, the Internet differentiated services are suboptimal without lower layers’ support. The IEEE 802.11 standard for Wireless LANs is the most widely used WLAN standard today. It has a mode of operation that can be used to provide

service differentiation

, but it has been shown to perform badly. In this paper, a new scheme of service differentiation to support QoS in the wireless IEEE 802.11 is proposed. It is based on a multiple queuing system to provide priority of user’s flow. Compared with the original IEEE 802.11b protocol, the proposed scheme increases overall throughput in the MAC layer.

We presents a power-aware routing protocol called Multi-Route Transmission Routing that utilizes multiple routes to transmit the data traffic simultaneously and leads to a balanced energy consumption. The proposed routing approach can extend the system lifetime of the network. A new routing decision index is also proposed for the route selection mechanism, which takes both the shortest-path and the maximum system lifetime into consideration and dynamically adjusts its weight between them according to the energy usage of the network. Experiment results show that, the proposed routing protocol provides a higher performance than other well-known power-aware routing protocols in terms of the energy-efficiency.

We propose a novel multicast scheme that can provide quality-of-service (QoS) to multicast service over IEEE 802.11 wireless LANs by utilizing medium access control (MAC) layer relay. It is well known that IEEE 802.11 provides a physical layer multi-rate capability in response to different channel conditions, and hence packets may be delivered at a higher data rate through a relay node than through the direct link if the direct link has low quality and low data rate. We develop the distributed relay node selection algorithm and the relay channel selection algorithm. The effectiveness of proposed scheme is examined by numerical method and simulation. Simulations show that the proposed relayed multicast significantly improves throughput and delay performance.

This paper presents the design of the adaptive concurrency control QOS agent, which is running on RCSM(Reconfigurable Context Sensitive Middleware) for ubiquitous networks. RCSM provides standardized commu-nication protocols to interoperate an application with others under dynamically changing situations. It describes a hybrid software architecture that is running on situation-aware middleware for a web based distance education system which has an object with a various information for each session and it also supports multicasting with this information. There are two approaches to software architecture on which distributed, collaborative applications are based. Those include CACV(Centralized-Abstraction and Centralized-View) and RARV(Replicated-Abstraction and Replicated-View). We propose an adaptive concurrency control QOS agent based on a hybrid software architecture which is adopting the advantage of CACV and RARV for situation-aware middleware.

This paper proposes an efficient end-to-end QoS supporting mechanism in Next Generation Network (NGN) with heterogeneous QoS capability to support ubiquitous and distributed applications. To address this, there should be proper admission control mechanism and adaptive provisioning to sustain end-to-end QoS and maximize network utilization. Resource and Admission Control Subsystem of NGN has unique feature of centralized network resource control rather than other network control protocol system in IP network. By showing optimal flows in heterogeneous QoS capability network, NGN can support average delay of end-to-end which the applications could receive proper Quality of Service over network.

Radio Frequency Identification (RFID) systems are increasingly becoming accepted for many EPC Network applications. However, RFID systems have some privacy problems. In this paper, a system for missing child location tracking in the EPC Network applications, is proposed. The proposed system improves security and privacy compared to existing applications, while also keeping in line with traditional procedures, commonly accepted by most industrial applications. The proposed MCLT (Missing Child Location Tracking) system can protect users’ privacy while providing location tracking of the RFID tag.

The ability to recognize many tags simultaneously is crucial for many advanced RFID-based applications. The tag anti-collision algorithm of an RFID system, which arbitrates collisions on the air interface among tags in the same reading range of a reader, makes a great influence on the speed and the reliability in multiple tag recognition. This paper presents a new memoryless tag anti-collision algorithm, QT-CBP (Query Tree with Collision Bit Positioning), which is designed based on QT (Query Tree) algorithm. QT-CBP is likely to make more concise tree traversal than QT by extracting and making use of detailed information on a collision condition, such as the number of collision bits and their positions. Basically QT-CBP is an enhanced algorithm for readers running QT, so no change is required at tags. Simulation study shows that QT-CBP outperforms QT, especially on the condition where tags have similar tag IDs by having the same company or product ID prefixes.

Grid computing and pervasive computing have rapidly emerged and affirmed as paradigms for high performance computing and for user-friendly computing respectively. These two separate worlds, however, can now interact each other in such a way that both pervasive and grid computing communities can benefit from integrating the two paradigms into a whole. This conjunction is already taking place to yield the

pervasive grid computing

model, and the present paper is focused on this approach. Purposely, it describes an Access&Location service for pervasive grid applications which uses RFID and WiFi technologies to grant access and locate mobile objects within a pervasive environment. Since this service is compliant to the OGSA specifications, it can be easily integrated into classic grid environments, therefore enhancing them with pervasive capabilities.

A framework for the autonomous management of large-scale ubiquitous sensor networks called SNOWMAN (SeNsOr netWork MANagement) is proposed in this paper. In large-scale ubiquitous sensor networks, a huge number of sensor nodes are deployed over a wide area and long distances and multi-hop communication is required between nodes. So managing numerous ubiquitous sensor nodes directly is very complex and is not efficient. The management of large-scale ubiquitous sensor networks therefore must be autonomic with a minimum of human interference, and robust to changes in network states. The SNOWMAN is responsible for monitoring and controlling ubiquitous sensor networks based on policy-based management paradigm. It allows administrators to simplify and automate the management of ubiquitous sensor networks. It can also reduce the costs of managing sensor nodes and of the communication among them using a new hierarchical clustering algorithm.

In a ubiquitous computing environment, every service should have the characteristic of context-awareness and location information is an important factor to grasp a user’s context. Thus, location privacy is an major security issue of ubiquitous computing environment. Most research on location privacy is focused on protecting the location information itself. However, not only prohibiting acquirement of the sensitive information illegally but also forbidding abuse of the information obtained legally is important to protect user privacy. In order to satisfy this claim, we propose a new privacy-aware service protocol for a ubiquitous computing environment. The proposed protocol decouples the relation between a user’s identity and location. Moreover, it uses anonymous communication channel to hide the user’s service consume pattern.

Nowadays, computer network systems play an increasingly important role in our society. They have become the target of a wide array of malicious attacks that can turn into actual intrusions. This is the reason why computer security has become an essential concern for network administrators. Intrusions can wreak havoc on LANs. And the time and cost to repair the damage can grow to extreme proportions. Instead of using passive measures to fix and patch security holes, it is more effective to adopt proactive measures against intrusions. Recently, several IDS have been proposed and they are based on various technologies. However, these techniques, which have been used in many systems, are useful only for detecting the existing patterns of intrusion. It can not detect new patterns of intrusion. Therefore, it is necessary to develop a new technology of IDS that can find new patterns of intrusion. This paper investigates the asymmetric costs of false errors to enhance the detection systems performance. The proposed method utilizes a network model considering the cost ratio of false errors. Compared with false positive, this scheme accomplishes both security and system performance objectives. The results of our empirical experiment show that the network model provides high accuracy in detection. In addition, the simulation results show that effectiveness of probe detection can be enhanced by considering the costs of false errors.

In this paper, we study the web technologies that allow ubiquitous spaces to create dynamic web pages in accordance with user profiles. Especially, we explore the server-side scripting approach, the most popular technology for dynamic web pages. This approach mainly adopts the execute-while-parsing model, which suffers from the interpretation overhead. Recently, the compilethen- execute model was proposed to address the overhead. This paper compares and analyzes the two models, while performing benchmark test in Microsoft ASP and ASP.NET environment. The benchmark results show that, due to the high initialization overhead, the compile-then-execute model cannot substantially improve the execute-while-parsing model. Also, the best performance can be achieved through optimization rather than compiled execution. Based on the results of the benchmark test, we develop a speedup model, which estimates the maximum performance improvement achievable by the compile-then-execute model.

The goal of our research is to provide an advanced programming environment for ubiquitous computing, which facilitates the development of secure and reliable ubiquitous software. The environment consists of a high-level ubiquitous programming framework, a run-time system enhanced with better context adaptation and security, and programming support tools.

In this paper, we focus on a ubiquitous programming framework, which includes a high-level policy description language, a translator to Java and a runtime system. We first present a high-level policy description language for formally specifying context entity relation, as well as context-based access control and adaptation policies. We then describe how a specification in the policy description language can be translated into Java code which makes use of JCAF.

In this paper, we propose multimedia service system, called

C-i

UMS (

Context based intelligent

Ubiquitous Multimedia Service), for smart and secure service based on context in intelligent ubiquitous home. The proposed system provides user centric multimedia service based on context including user location, user preference and device status information. In addition, the proposed system supports ubi-home super-distribution which contents can distribute safely and consume from the central intelligent and secure media center to the end terminal in intelligent ubi-home. Furthermore, we propose and apply a VTD

i

C algorithm for customized contents to multimedia players. Finally, a prototype of USN device is designed and implemented to realize intelligent Ubi-home supporting smart service.

Due to the stateless nature of the internet, it is an intricate problem to determine the source of spoofed attacking packets. To handle this problem we utilize the IP traceback mechanism to know the actual source of an IP datagram. While many IP traceback techniques have been proposed but most of the previous studies focus and offer solutions for DDoS attacks done on IPv4 environment. Significant difference exists between IPv4 and IPv6 Networks. Therefore, the mechanisms for tracing the origin of attacks in IPv6 networks have abundant differences from those of IPv4 networks. In this paper, we proposed an efficient Lightweight IPv6 traceback algorithm. We also discussed the problems related to previously proposed IPv4 traceback schemes and presented the Error Correction and Modified Path MTU calculation algorithm to make our scheme more practical.

The lack of verifying source address in Internet makes it easy for attackers to spoof the source IP address. One of challenges of Internet has been recognized is building mechanisms in routers to verify the source address. This paper discusses Source Address Spoofing Prevention (SASP) mechanisms, presents a formal description on SASP network and SASP router, proposes a hierarchical SASP architecture, and presents some design principles of SASP mechanisms.

In this paper, we present FBAC (Flexible Bound Admission Control) algorithm using softness profile to reduce handover blocking probability over WLAN and WAAN (Wide Area Access Network). FBAC algorithm utilizes dynamic resource allocation scheme to decrease the blocking probability of vertical handover connections within the limited capacity of system. Based on FBAC algorithm, we derive the handover blocking probability as new traffic load and handover traffic load increase. In order to evaluate the performance, we compare FBAC algorithm against traditional non-bounded and fixed bound schemes. Numerical results show that the FBAC scheme improves handover blocking probability in ubiquitous environment.

The new algorithmic technique which allow higher efficiency in the precise calculation of the reliability of an undirected graph with absolutely reliable nodes and unreliable edges is considered in this paper. As graph’s reliability we mean its probabilistic connectivity. The proposed technique is based on the reduction of the dimension of a calculated graph by considering its node’s cuts. Comprehensive computer simulation results show the advantages of the proposed algorithms, that the calculation time decreases significantly in comparison with existent methods.

Even though its advantages such as non-volatility, fast write access time and solid-state shock resistance, NAND flash memory suffers from out-place-update, limited erase cycles, and page-based I/O operations. How to provide fast mounting and consistency of file system and data for flash memory file systems has become important research topics in recent years. In this paper, we design and propose a new flash memory file system called RFFS (Reliable Flash File System), which targets NAND flash memory based embedded systems that require fast mounting and fault tolerant file system. We have experimented on the performance of RFFS and the results showed that RFFS could improve the mounting time by 65%–76% compared with YAFFS. Also RFFS improved mounting time after sudden system faults by 89%–92% compared with JFFS2.

The method of broadcast encryption has been applied to the transmission of digital information such as multimedia, software, and paid TV on the open network. In this broadcast encryption method, only previously authorized users can gain access to digital information. When broadcast message is transmitted, authorized users can first decode the session key using the previously given private key and get digital information using this session key. This way, users retrieve a message or a session key using the key transmitted by broadcasters. For their part, broadcasters need to generate and distribute keys. Broadcasters should also carry out efficient key renewal when users subscribe or unsubscribe. This paper introduces how to generate and distribute key efficiently and how key renewal works. The proposal uses two methods: (1) the server generates keys without the consent of users by anticipating users, and; (2) the server and users generate keys by mutual agreement. The advantage of the two proposed methods is that the receiver can decode broadcast message using a secret key. Even if the key is renewed later, the user can efficiently renew using only a single set of information.

A verifiably encrypted signature can convince the verifier that a given cipher-text is the encryption of a signature on a given message. It is often used as a building block to construct optimistic fair exchange. Recently, Gu

et.al

gave an ID-based verifiably encrypted signature scheme and claimed that their scheme was secure in random oracle model. Unfortunately, in this works, we show that their scheme is insecure. And we can mount to universal forgery attack in their model. In other words, any one is able to forge a verifiably encrypted signature on arbitrary message

m

. Subsequently, a novel verifiably encrypted signature scheme (VES) is proposed and the scheme is proven secure in random oracle model. Moreover, the size of verifiably encrypted signature in our scheme is shorter than that of Gu

et.al

’s signature.

An iterative modulo scheduling is very important for compilers targeting high performance multi-issue digital signal processors. This is because these processors are often severely limited by idle state functional units and thus the reduced idle units can have a positively significant impact on their performance. However, complex instructions, which are used in most recent DSPs such as

mac

, usually increase data dependence complexity, and such complex dependencies that exist in signal processing applications often restrict modulo scheduling freedom and therefore, become a limiting factor of the iterative modulo scheduler.

In this work, we propose a technique that efficiently reselects instructions of an application loop code considering dependence complexity, which directly resolve the dependence constraint. That is specifically featured for accelerating software pipelining performance by minimizing length of intrinsic cyclic dependencies. To take advantage of this feature, few existing compilers support a loop unrolling based dependence relaxing technique, but only use them for some limited cases. This is mainly because the loop unrolling typically occurs an overhead of huge code size increment, and the iterative modulo scheduling with relaxed dependence techniques for general cases is an NP-hard problem that necessitates complex assignments of registers and functional units. Our technique uses a heuristic to efficiently handle this problem in pre-stage of iterative modulo scheduling without loop unrolling.

A priority-driven scheduling algorithm is said to be

start time (finish time) predictable

if the start time (finish time) of jobs in the schedule where each job executes for its actual execution time is bounded by the start times (finish times) of jobs in the schedules where each job executes for its maximum/minimum execution time. In this paper, we study the predictability of a job-level dynamic priority algorithm, LLF (Least Laxity First), on multiprocessor real-time systems. We present a necessary and sufficient condition for a priority-driven algorithm to be start time (finish time) predictable. Then, in LLF scheduling, we show that both the start time and the finish time are predictable if the actual execution times cannot be known. However, solely the finish time is predictable if the actual execution times can be known.

Modern portable or embedded systems support more and more complex applications. These applications make embedded devices require not only low power-consumption, but also high computing performance. To enhance performance while hold energy constraints, some high-end embedded processors, therefore, adopt conventional features to exploit instruction-level parallelism and increase clock rates. The reorder buffer (ROB) and the register file are the two most critical components to implement these features. The cooperation of them, however, causes serious leakage power, especially for a large register file. In this paper, we propose a pure hardware approach to reduce the leakage power for the register file, such that more complex features (e.g., out-of-order execution, speculation execution, etc) can be applied to high-end embedded processors. In the proposed approach, we design a monitoring scheme in the pipeline datapath to identify the timing of powering up or powering down a register. Simulation results show that our approach saves at least 50% power consumption of the register file, with almost negligible performance lost.

Most vendors of digital signal processors (DSPs) support a Harvard architecture, which has two or more memory buses, one for program and one or more for data and allow the processor to access multiple words of data from memory in a single instruction cycle. We already addressed how to efficiently assign data to multi-memory banks in our previous work. This paper reports on our recent attempt to optimize run-time memory. The run-time environment for dual data memory banks (DDMBs) requires two run-time stacks to control activation records located in two memory banks corresponding to calling procedures. However, activation records of two memory banks for a procedure are able to have different size. As a consequence, dual run-time stacks can be unbalanced whenever a procedure is called. This unbalance between two memory banks causes that usage of one memory bank can exceed the extent of on-chip memory area although there is free area in the other memory bank. We attempt balancing dual run-time stacks to enhance efficiently utilization of on-chip memory in this paper. The experimental results have revealed that although our call chain balancing (CCB) algorithm is relatively quite simple, it still can utilize run-time memories efficiently; thus enabling our compiler to run extremely fast, yet minimizing the usage of run-time memory in the target code.

Currently the Java programming language is popularly used in Internet-based systems, mobile and ubiquitous devices because of its portability and programability. However, inherently its performance is sometimes very limited due to interpretation overhead of class files by Java Virtual Machines (JVMs). In this paper, as one of the solutions to resolve the performance limitation, we present code generation and optimization techniques for a Java-to-C translator. Our compiler framework translates Java bytecode into C codes with preserving Java’s programming semantics, such as inheritance, method overloading, virtual method invocation, garbage collection, and so on. Moreover, our compiler translates

for

in Java into

for

in C instead of

test

and

jump

for better performance. Our runtime library fully supports Connected Limited Device Configuration (CLDC) 1.0 API’s.

With the increasing complexity of the real-time embedded software, the power consumption is becoming a real challenge in the system designs. In this paper, for modelling the component-based embedded software, the interface automata is extended by adding time intervals on the actions and assigning energy consumption rates on the states. The extensional formalism is called

energy interface automata

. Then the system designs are modelled by energy interface automaton networks which consist of a set of energy interface automata synchronized by shared actions. Based on analyzing the integer state space of the energy interface automaton networks and its compatible reachiability graph, we develop two algorithms for the problem of the minimal energy consumption calculation and the maximal energy consumption verification respectively.

Programmable vertex processing unit increases the programmability and enables customizations of transformation and lighting in the graphics pipeline. Furthermore, it offers various effects such as procedural vertex animation and deformation, which were impossible to handle in fixed vertex processing. Since it is hard to find a programmable graphics hardware for the embedded systems such as mobile phones, we’ve designed and implemented a programmable vertex processing unit based on the OpenGL ES 2.0 specification. In this paper, we explain the architecture, instruction format, implementation and test results of our vertex processing unit.

This paper presents the design of a high performance energy-aware whole-system emulator – SkyEye. Several optimization and novel energy estimation methods used in SkyEye are proposed. By using novel searching strategy for Translated Block (TB), SkyEye save the time to find proper translated block. SkyEye uses Basic Equal Length Unit (B-ELU) method, and dynamic binary translation to reduce the simulation and energy evaluation time. The performance model of B-ELU is built to get the best length of translated block. In addition, the simulator automatically detects the voltage/frequency variation, and adjusts the energy estimation model accordingly. Using these methods, SkyEye which simulates ARM CPU based hardware system achieves marvelous performance and energy-aware statistic capability in experiments.

Runtime data alignment has been paid attention recently since it can allocate data segment to processors dynamically according to applications’ requirement. One of the key optimizations of this problem is to schedule simultaneous communications to avoid contention and to minimize the overall communication costs. The NP-completeness of the problem has instigated researchers to propose different heuristic algorithms. In this paper, we present an algorithm independent technique for optimizing scheduling stability of different scheduling heuristics. The proposed technique introduces a new scheduling policy, Local Message Reduction (LMR), to obtain better communication schedule adaptive to different environments. o evaluate the performance of the proposed technique, we have implemented LMR along with two existing algorithms, the two-phase degree reduction and the list scheduling algorithms. The experimental results show that the proposed technique is effective in terms of scheduling stability, communication efficiency and easy to implement.

This paper birefly introduces a Chinese digital input method named as CKCDIM (CKC Digital Input Method) and then applies it to the Symbian OS as an example, and it also proposes a framework of input method which adopted the Client/Server architecture for the handheld computers. To improve the performance of CKCDIM, this paper puts forward a dynamic and self-study language model which based on a general language model and user language model, and proposes two indexes which are the average number of pressed-keys (ANPK) and the hit rate of first characters (HRFC) to measure the performance of the input method. Meanwhile, this paper brings forward a modified Church-Gale smoothing method to reduce the size of general language model to meet the need of mobile phone. At last, the experiments prove that the dynamic and self-study language model is a steady model and can improve the performance of CKCDIM.

In this paper, we propose an identities(

ID

) based watermarking scheme for Java programs. In our scheme, the watermark is generated by participants’ identities, embedded via the watermarked opaque predicates, and verified using zero-knowledge proof. We also present a construction of a family of opaque predicates by Legendre symbol, which is resilient, cheap, and stealthy. The order of the watermark is encoded and embedded into the watermarked opaque predicates, and the watermarked opaque predicates are treated as threads of a Java program. Thus, the embedded watermark is dynamic and secure against all usual types of watermarks algorithms attacks and watermarks protocols attacks, and also secure against static and dynamic attacks.

As the ever-increasing gap between the speed of processor and the speed of memory has become the cause of one of primary bottlenecks of computer systems, modern architecture systems use cache to solve this problem, whose utility heavily depends on program data locality. This paper introduces a platform independent data-layout optimization framework to improve program data locality. This framework uses a variable relation model based on variables’ reuse distance distribution to quantitate the relation of variables and accordingly assigns variables which are often accessed together in one group. At the same time this framework introduces a dynamic array regrouping method to group dynamic arrays assigned in a group. Experiments show that this data-layout optimization framework can effectively improve program data locality and program performance.

As process technology scales down, power wall starts to hinder improvements in processor performance. Performance optimization has to proceed under a power constraint. The co-optimization requires exploration into a huge design space containing both performance and power factors, whose size is over costly for extensive traditional simulations. This paper describes a unified model covering both performance and power. The model consists of workload parameters, architectural parameters plus corresponding power parameters with a good degree of accuracy compared with physical processors and simulators. We apply the model to the problem of co-optimizing the power and performance. Concrete insights into the tradeoffs of designs for performance and power are obtained in the process of co-optimization.

Flash memory is used at high speed as storage of personal information utilities, ubiquitous computing environments, mobile phones, electronic goods, etc. This is because flash memory has the characteristics of low electronic power, non-volatile storage, high performance, physical stability, portability, and so on. However, differently from hard disks, it has a weak point that overwrites on already written block of flash memory is impossible to be done. In order to make it possible, an erase operation on the written block should be performed before the overwrite, which lowers the performance of flash memory highly. In order to solve this problem, the flash memory controller maintains a system software module called the flash translation layer(FTL). In this paper, we propose an enhanced log block buffer FTL scheme, FAST(Fully Associative Sector Translation), which improves the page usability of each log block by fully associating sectors to be written by overwrites to the entire log blocks. We also show that our FAST scheme outperforms the previous log block buffer scheme.

The hardware-software automated partitioning of a RTOS in the SoC (SoC-RTOS partitioning) is a crucial step in the hardware-software co-design of SoC. First, a new model for SoC-RTOS partitioning is introduced in this paper, which can help in understanding the essence of the SoC-RTOS partitioning. Second, a discrete Hopfield neural network approach for implementing the SoC-RTOS partitioning is proposed, where a novel energy function, operating equation and coefficients of the neural network are redefined. Third, simulations are carried out with comparisons to the genetic algorithm and ant algorithm in the performance and search time used. Experimental results demonstrate the feasibility and effectiveness of the proposed method.

Multimedia stream standards evolve rapidly as stream applications prosper in embedded systems. A key component of standards, discrete cosine transform is being replaced by SA-DCT, whose complexity results in a large design space. The paper describes a UML 2.0 based design approach to quick evaluation of SA-DCT implementations containing both hardware and software, which are hard to describe and verify in C, Verilog and VHDL. Using the approach, we manage to study the partitioning, reconfigurability as well as performance and hardware cost. The design specifications in UML can be translated into SystemC models consisting of simulators and synthesizable code under proper style constraints. The paper demonstrates the feasibility of quick specifications, verification, evaluation and generation of embedded system designs.

Java Card technology provides a secure, vendor-independent, ubiquitous Java platform for smart cards and other memory constrained devices such as SIM technology. It is also an open standard in SIM and UIM technology for 3G environment. However, the major point of criticism with regard to Java for smart cards and SIM cards is its low execution speed, aside from its memory demands. We found out that the most long-time work during the execution is to write data to non-volatile memory such as Flash memory. In this paper, we make a suggestion to improve the execution speed by buffering effectively Java Card Objects in order to reduce the number of flush() method. With our approach, the total number of flash writing and the execution speed of applications reduced by about 50% and 38% separately.

This paper presents a mobility prediction method for context-aware service in mobile networks. It aims to reduce the latency time to get the refreshed information appropriated to the current location of mobile users. The proposed method is to effectively limit the prefetched information into the most next location context. It makes use of the mobile reference count and the residence time that stands for the mobile user’s visiting characteristics in any cell area. Then it also considers the information usability in order to further predict the prefetching candidates. In the numerical results, the proposed method is less latency time than that of the previous schemes to prefetch information matched to user’s current location.

This paper presents a true ortho-image generation scheme in urban areas for web GIS application such as urban management system. Proposed scheme includes the solution of conventional problems in normal ortho-image generation. Especially, our approach is focused on the automation and consistency of ortho-image in complex urban areas. For this purpose, we generated additionally plotted DSM (Digital Surface Model), which includes roads, high-level roads, bridges, and tunnels, automatically detected occlusion pixels and restored occlusion areas using a self-developed algorithm, and performed mosaic process using road-based seamlines. Total 2,677 aerial color images were used to create the so called true ortho-image map for Seoul metropolitan city. It turned out that the proposed method could generate true ortho-image map for urban areas with high positional accuracy and good visual consistency. The generated ortho-image database is being successfully operated by Seoul Metropolitan Aerial Photography Management Systems on the web and urban management systems.

This paper proposes more various key generation algorithms than conventional encryption method, and more secure encryption method that does not keep each symmetric key of key generation algorithm in server. After implementing proposed system, we verify the system using various sizes of video data. We get the fact that proposed system can reduce the delay time of encryption and decryption at the replay of video data.

This paper propose to see how the center based car navigation systems are practical in terms of using real time traffic information and guiding the way with different media of both of the Turn by Turn and the digital map service. The systems have been applied to all the road networks in Korea but the traffic actuated car navigation systems are mainly applicable to the road networks in the Seoul, which has 40 km diameter, including satellite cities. As a result of this, the actual driving tests are conducted in that area. The tests are analyzed using two aspects. The first aspect is that the quality of the information using the car navigation systems can be acceptable to the customers in around 80 percentage of a statistical level. The other is if the user- friendly interface is relatively helpful to the customers while they are driving a car. The result shows that the route displayed on the TFT LCD helps the drivers to understand which way they have to take.

We propose analytic model of the delay of the Slotted ALOHA protocol with Binary Exponential Backoff (BEB) as a collision resolution algorithm in mobile multimedia networks. We verify the proposed analytic model using the computer simulation. In numerical results, our proposed method show correct analytic model and has better performance results than previous methods in mobile multimedia networks.

Detecting network address translation is helpful for network administrators to enhance the network security. Current network address translation detection approaches can not work effectively in all scenarios. In this paper, a new detection scheme ImNatDet utilizing instant messaging information is presented, a case study based on characters of MSN Messenger is analyzed, and related security issues are discussed. This paper also indicates that characters of instant messaging applications can be used to detect users’ privacy information.

We propose a new authentication scheme of binding update protocol, which its Correspondent Node (CN) issues a ticket to Mobile Node (MN) when MN first executes the Binding Update (BU). This ticket assist that it is able to do efficiently the BU whenever MN requires the BU for the future. The proposed protocol need not be repeated equal BU course whenever the MN moves to foreign link or network, and is able to be executed in environment of not operating the Home Agent (HA), and also easies scalability.

At the transition from a tangent section to a curved section, it is possible for a following vehicle with adaptive cruise control in car-following mode to lose track of the lead vehicle. This occurs because the lead vehicle enters the curve and its path diverges from the axis of the following vehicle, yet the following vehicle does not yet have lateral acceleration information that would induce its range sensor to bend according to the curvature of its own path. This is a temporary situation, but one that could have an impact on cruise control safety and appropriate algorithms. In this paper, the conditions of time and distance that produce this circumstance are derived. Examples are given using typical values of roadway and vehicle parameters. Finally, some conclusions regarding possible solutions are offered.

Until a recent date all telephony connections are set up via circuit switching. Advances in networking technology have made it possible for the Internet evolves into a Broadband convergence Network (BcN) and provides various services including Internet Protocol (IP) telephony over high-speed IP networks. Voice-over-IP (VoIP) uses packetized transmission of speech over the Internet. In order for the Internet to realize a profit as traditional Public Switched Telephone Network (PSTN), it must provide high quality VoIP services. The VoIP metrics report block of Real-Time Transport Protocol Control Protocol Extended Reports (RTCP XR) can be applied to any one-to-one or one-to-many voice application for which the use of RTP and RTCP is specified. However, RTCP XR only defines packet type to convey information that supplements the six statistics that are contained in the report blocks used by RTCP’s Sender Report (SR) and Receiver Report (RR) packets. Our objective in this paper is to describes a practical measuring framework for end-to-end QoS of packet switched voice in an IP environment including Packet Loss Concealment (PLC) techniques. It includes concepts as well as step-by-step procedures for setting up components, creating session, measuring packetized voice streams over IP networks.

It is very crucial in the field of security control to acquire the capability of promptly coping with various threatening elements in cyber world such as vicious worms, virus and hackings that cause enormous damage and loss across the nation within a rather short term period like the large scale network paralyzed by vicious traffic, disturbance of electronic commerce, etc. As such, it can be the fundamental measure on these sorts of threats to establish the new method of detecting the similar threats as well as to reinforce the user’s recognition of security. The purpose of this study is to analyze the problems in the existing IDS and TMS, which are monolithic in terms of detection method, and further to suggest the improved detection method and HOIDS system which is recently introduced and in test operation.

It is widely accepted that the coverage with high user densities can only be achieved with small cell such as Micro / Pico-cell. The smaller cell size causes frequent handoffs between cells and a decrease in the permissible handoff processing delay. This may result in the handoff failure, in addition to the loss of some packets during the handoff. In this paper we propose new handoff control scheme in the next generation mobile communications, in which the handoff setup process is done in advance before a handoff request by predicting the handoff cell based on mobile terminal’s current position and moving direction.

Wireless communication technology has been introduced in the field of Intelligent Transportation Systems (ITS) in the past decades, and its applicability has been widely expending. Feasibility of the IR-DSRC based vehicle detection systems in measuring vehicle speed was tested as a possible alternative of the conventional inductive loop based systems requiring high construction and maintenance cost. It was found from the field test that the speed data from the IR-DSRC detection systems were statistically identical to the ones from the loop based systems at 95% confidence level.

Ubiquitous Sensor Networks (USN) environment is composed of dense nodes of Ad-Hoc network structure which has small size node, low power and low calculation ability. Sensor nodes have constraints in operation which small size and distribution features so that they should be operated using low power. In this paper we propose a grid computing scheme to solve limited energy problems which can maintain the energy consumption as a same level though measuring remain energy with analyzing energy consumption of nodes. We confirm the improvement of survival time of entire nodes and less variation of topology in case of our proposed scheme through simulation.