In this paper, we propose a dynamic channel reservation scheme to satisfy a desired handoff dropping probability and to reduce the blocking probability of new calls using mobility characteristics of network traffic which is defined as the ratio of the handoff call arrival rate to new call arrival rate. For the scheme, the request probability of channel allocation for the new calls is determined by considering the total available channels in a BS, threshold, the number of channels in use, and mobility characteristics. Also we perform mathematical analysis and simulation to evaluate the performance of proposed scheme, and compare to conventional guard channel scheme in terms of dropping probability, blocking probability, and the utilization efficiency of wireless channels.

Recently, a number of studies have focused on multimedia applications after the emergence of the ATM based B-ISDN and data compression techniques such as MPEG. Due to bursty traffic characteristics of the Variable Bit Rate MPEG video data, in order to transmit video streams, Bandwidth Smoothing Schemes perfetchting sufficient data from the server, have been provided to reduce the Bandwidth Requirements. In the Interactive VOD service providing VCR operations (Fast Forward, Rewind, Pause, etc.), after the users requested interactive operations, the playback of the paused video frame is restarted. For this purpose, the server has to reschedule the transmission information at a new frame position in the steam in order to transmit the remainder VBR Video Streams. That is adaptive for the interactive VOD service with a few calculations and information of And we analyzed the performance of the proposed scheme using the VBR MPEG-1 bit trace data.

Multicasting refers to concurrently transmitting the same data from a source to multiple destinations in a packet network. To handle large number of multicast sessions, a network must minimize the sessions's resource consumption, while meeting their QoS requirements. In this paper, we propose a distributed multicast algorithm for constructing minimum-cost multicast trees with delay constraints. The proposed algorithm requires limited network state information at each network node and the routing tree is computed through a single round of message exchanges between network nodes, We prove the algorithm's correctness by showing that it is always capable of constructing a delay-const mined multicast tree, if one exists, and it has the worst case message complexity of O(ㅣvㅣ2), where ㅣVㅣ is the number of network nodes. The proposed algorithm is verified by simulation, and it is shown that the proposed algorithm exhibits much better performance than the existing ones for static and dynamic multicast groups in all circumstances, which include various network sizes, multicast group sizes and end-to-end delay bounds.

With the emergence of erbium-doped optical amplifier, High-speed optical network employing linear bus such as BQDB have become more attractive. in this paper, a new WDMA protocol is developed for optical network based on a Distributed Queue Dual Bus(DQDB) Metropolitan Area Networks with grouping scheme. Performance evaluation shows that not only proposed protocol overcomes the several limitations of existing protocol but achieves almost same performance. Especially, if 친e network size is increase. our protocol as better system performance than existing protocol. Also, proposed protocol is applicable to classic DQDB network directly without protocol change of basic counter scheme.

In recent years, it is required that computing support mobile user with computer. The advantage of mobile computing is that users may access all their applications from any location whether they are in another building or a different state. So, internet combines with mobile computing technology to make new communication environment for supporting mobility. The research for solving the problem of mobility is actively in progress.-This paper describes the implementation of tunneling method (or flexible bypass between specif?c region. Tunneling method provide mobile service to mobile hosts. If datagram address transform method is IP-within-lP encapsulation by which an IP datagram may be encapsulated within an If datagram, The developed IP-whitin-lP protocol can provide not only enhanced performance because it is implemented in kernel mode, but also convenience of usage to the application developers because it gives user interface as a dynamic link library. Verificationof If packet Tunneling: was text file transfer program.

The security and the efficiency of McEliece’s public-key system are revisited through investigating the characteristics and the performance analysis of the public-key cryptosystem based on Goppa code introduced by McEliece’s. also introduced is the public key cryptosystem which is able to correct the channel error through a design and an analysis of the integration system.

The blind algorithms can be used to separate the multi-user signals, a superposition of signals from all the users and the additive noise. in this paper Equalizers having ability to separate those multi-user signals without the training sequence are proposed and multi-stage radius-directed algorithm is compared to CMA. A cascade system is constructed by serially connecting a number of stages, each of which is composed of equalizers that capture the one source signal and a correlation canceller that subtracts the captured source signal from the equalizer input. The output of the canceller is then processed in the next stage, which recovers another source signal in a similar manner. A hybrid system using a parallel structure initialized by the cascade system achieves no accumulation of maladjustment from stage to stage unlike the cascade system, Also Those systems using the multi-stage radius-directed algorithm obtain good convergence properties.

A doppler weather radar is a very useful remote sensing system for the detection and prediction of weather phenomena under the rapidly changing weather conditions. However, the signal and data processing unit of a weather radar should be reliable and efficient enough to provide an accurate information in time. For the improvement and verification of this unit it is very important to simulate Doppler weather signals under various weather conditions considering many system-related parameters. Therefore, this paper analyzed the effects of radar system parameters and also proposed the skewed Gaussian model for the purpose of simulating various weather signals.

In this papaer, an efficient method for detection of dominant points and clain codes if binary images based on run-length coding is proposed. In order to analyze and recognize binary images, especially to obtain geometrical information, dominant points of region boundaries are very important features. Several special runs such as D, F, R,. R*, s, s* and X_run are introduced for run-length coding, and the binary image is represented by the special runs. Each special run includes its nm property. The chain code and dominant points are detected simultaneously, and the proposed method is simulated using several binary images. By the computer simulation it has been shown that the Proposed method can be used to detect dominant points in boundaries.

Linearity of MQW electroabsorption optical modulators for broad band analog SCM optical transmission systems have been analyzed by varying the structure of optical modulators. Increasing the number of quantum well and modulator’s length, the DC bias operating point which has the minimum CSO was shifted to the low bias voltage. The variation of CTB was negligible for the number of quantum well and modulator’s length variations. Since the absorption variation of quantum well considering exciton effect is nonlinear for bias voltage variation, both CSO and CTB enhancement could not be related to the wavelength detuning.

In this paper, a ridge type polarization controller which has merits of low drive voltage and wide bandwidthto coplanar waveguide type, is proposed. The Ti:LiNb03 ridge waveguide is applied to the conventional polarization controller The drive voltage and bandwidth of the device are dependent on the microwave characteristics of electrodes and the relative structure between the waveguides and electrodes. So, the characteristic impedance and microwave effective index of the device have been calculated by the various design factors, which are electrode gap, electrode thickness and ridge depth, using FEM(Finite Element Method) numerical analysis tool. The overlap integral factor between the guided wave and the external electric field has also been calculated in order to obtain the value of drive voltage. for wider bandwidth and lower drive voltage, the polarization controller has to be designed to have deep ridge, narrow?electrode gap, and thick electrodes. For the drive voltage with various ridge depth, it is shown that the drill? voltage is decreased as the ridge depth increases and that the drive voltage of the proposed polarization controller Is lower than that of coplanar type.