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Multi-agent technologies are essential in realizing the upcoming ubiquitous environment. In the multi-agent environment, each agent has its own set of services and stores these services in the service repository of the multi-agent system. By using this repository, the user can retrieve the most appropriate service. In this paper, we propose an efficient service repository architecture that can improve the existing repository by using context inferencing, context filtering, user-predefined policies, and the categorized tree. An advantage of the proposed architecture is that the user can obtain more suitable services than existing approaches about service discovery. [ABSTRACT FROM AUTHOR]

Service discovery in ubiquitous environments faces various issues such as dynamic-topology, devices-capability, resource-sharing, interoperability etc. In this paper, we propose Service Discovery Middleware (SDM) to solve the interoperability issue by using Discovery Middleware (DM), which was introduced by the FIPA (Foundation for Intelligent Physical Agents) [1]. The SDM provides an appropriate choice for providing interoperability in heterogeneous environments. Moreover, it supports a means for autonomic discovery of heterogeneous integration services in ubiquitous computing and transparency between users and services. With these ideas in mind, we design a simple mechanism for building a wide range of distributed services and applications as well as for supporting a softness and adaptable means to control and manage the Service Discovery Protocols (SDP). Furthermore, we implement as an example, a Personal Agent (PA) platform based on the FIPA-OS agent platform, in order to provide SDM component functionality [10] [20]. [ABSTRACT FROM AUTHOR]

Service discovery middleware allows users to find and use services through service discovery protocols in heterogeneous and ubiquitous environments without previous knowledge of the specific service location or characteristics, and with minimum manual effort. For this reason, in recent years, a number of researchers have studied service discovery middleware and many of papers dealing with this field have been published. However, when a number of service consumers request services from middle agents (e.g. matchmaker, broker, yellow page, blackboard, lookup server, etc) within the service discovery middleware, the middle agents do not guarantee efficient and rapid matching results because they use only a simple matching algorithm based on set theory for match processing. In this paper we address issues of existing matching algorithms, and propose a new matchmaking method adopting the marriage matching algorithm of the ATM network [1] to improve middle agent performance, complementing shortcomings of the existing matching algorithms. Furthermore, we use traffic type (e.g. voice/video applications, data-sharing applications, convenience applications, and so on) priority information for providing application-oriented QoS. [ABSTRACT FROM AUTHOR]

The Simple Object Access Protocol (SOAP) is a novel protocol which supports information exchange in a decentralized, distributed environment, which brings flexibility and extensibility to the communication and invocations among remote hosts. However, SOAP requires a high performance for collaboration such as service delivery and invocation. Furthermore, SOAP itself is not well suitable for mobile devices due to network bandwidth or resource-constraints problems. In this paper, we describe SOAP-based remote data access scheme which is comprised of XML and RPC technology. Especially, we focus on the scheme which is optimal over service discovery and invocation based on SOAP technology. Also, we apply the proposed scheme to LSD (Lightweight Service Discovery) which is a peer-to-peer, cache-based service discovery protocol for ad hoc environments. [ABSTRACT FROM AUTHOR]

The integration of WLANs and CDMA networks has recently evolved into hot issue. We propose a vertical handoff algorithm between WLAN and CDMA network. A handoff initiation is decided by the received signal strength (RSS). To reduce the unnecessary handoff probability, we also consider a distance. As a mechanism of network selection, we propose a context based network selection algorithms between WLAN to CDMA network, based on wireless channel assignment such as dropping probability, blocking probability, GoS (Grade of Service), the number of handoff attempts. As a decision making criterion, velocity threshold is determined to optimize the system performance. The optimal velocity threshold is adjusted to assign available channels to the mobile stations. The proposed scheme is validated by computer simulation. [ABSTRACT FROM AUTHOR]

Wireless LANs (WLANs) are one of the fastest growing wireless access technologies. Unfortunately, since they were developed to closely match existing wired LANs, the popular IEEE 802.11 standards have several problems in providing Quality of Service (QoS) to stations. The IEEE 802.11e standard is being developed to overcome these drawbacks. One of most important function in 802.11e is the contention-based channel access mechanism called enhanced distributed coordination function (EDCF), which provides a priority scheme by differentiating the inter-frame space and the initial window size. In this paper, we first consider the enhanced DCF access method of IEEE 802.11e. We then introduced analytical model, which can be used to calculate the traffic priority and throughput corresponding to the configuration of multiple DCF contention parameters under saturation throughput. This enhanced DCF access method differs from the standard backoff schemes in that the backoff time is not uniformly chosen in the contention window interval that results in reduced collision probability under high loads. Numerical analysis shows that saturation throughput of the proposed scheme outperform the earlier approach. [ABSTRACT FROM AUTHOR]