Gyung-Chul Sihn

Research activities on next-generation mobile communications and services in Korea

In this article we present a perspective on next-generation mobile communications and services. As a preliminary research work on next-generation mobile communications, we exploit what next-generation mobile services will be (S. Ryu et al., May 2003). We define next-generation mobile services as a hierarchy of services consisting of three different service levels: the service areas, the service functionalities, and the service technologies. We derive these service levels by means of scenario-based analysis. Next we propose conceptual reference network architecture, focusing on the realization of the service technologies. We divide the network into four different parts: a user equipments and access part, a network service provisioning layer part, a network control layer part, and non-mobile network operator service pan, according to characteristics of information and service flows within a network. In this reference network architecture, service elements such as servers, processors, and gateways are placed in each network part to support the derived next-generation mobile services. Finally, we give a brief introduction of research and development activities for next-generation mobile communication systems and services in Korea.

Provision of User-Centric Mobile Services in Next Generation Mobile Communication Environment

In next generation (NG) mobile communication environment, it is expected that mobile services will be user- centric and the mobile service platform will play an important role in supporting various future mobile services not only for service providers to provide services effectively but also for users to use services easily. In-this-paper,-we propose the architecture, functions and protocols of the NG mobile service platform of the NG mobile service platform which gives efficient means of connecting users and service providers to fulfill user-centric mobile services. Then we describe the NG mobile service environment with focusing on the NG service platform and how user-centric mobile services are provided in the NG mobile service environment. We then introduce the context aware follow-me (CAF) service developed as a prototype of promising NG user-centric mobile service followed by introduction of test- bed system developed to investigate feasibility of the CAF service.

Method of codec operation control by the call control protocol in 3GPP mobile station

Types of codec for the 3GPP UE are presented but it is not clear which protocol entity performs codec controls such as the activation, start, stop and deactivation of codec functions and when the codec is controlled. So a normal telephony service is not guaranteed because a call might be established while the codec is not normally worked, and unnecessary resource wastage is happening because a call might be cleared while the operation of codec functions is continued Therefore, it is required that the codec is controlled depending on the call state. In this paper, it is proposed that the codec in the UE is controlled by the call control protocol which administers the call state by execution of call control procedures, and preventing normal call control procedures being executed even in case of abnormal codec operation, call control procedures are executed depending on the result of codec controls. Due to methods proposed in this paper, the establishment of a call guarantees the normal operation of codec functions and the call clearing guarantees stopping of the operation of codec functions.