Abstract: A client apparatus and method using a multimedia streaming service supporting technology that controls streaming communication with a streaming server on the basis of a buffer level independently from a pause/resuming input of a user are provided. The method includes: measuring a buffer level of a buffer of a streaming client which temporarily stores streaming data received from a streaming server; and controlling, independently from a user's input, streaming communication with the streaming server according to the measured buffer level.

Abstract: A method for setting an output bit rate for video data transmission in a WiBro system in which an uplink state value for a predetermined unit time is calculated to determine an uplink network state of the predetermined unit time. An average of uplink state values for a predetermined number of unit times is calculated, and a video encoding bit rate is increased if the average of the uplink state values is larger than a predetermined first threshold. However, the video encoding bit rate is decreased if the average of the uplink state values is less than a predetermined second threshold.

Abstract: A method for variably controlling a bit rate of video data through end-to-end channel status sensing in a Wireless Broadband (WiBro) network is provided. The method includes classifying wireless channel statuses of a transmission side and a reception side into normal and abnormal statuses during video data transmission; variably controlling and determining an encoding bit rate of a transmission side's encoder according to the classification result; and comparing the determined encoding bit rate with a Down Link Modulation & Coding Selection Level (DL MCS Level) which is a parameter of the reception side, so as to vary a final encoding bit rate of the transmission side.

Abstract: Disclosed is a radio-over-fiber (ROF) system for supporting various services, the system comprising: a central access platform (CAP) for providing time division duplexing (TDD), frequency division duplexing (FDD), and broadcasting services, converting a TDD downward signal and FDD/broadcasting downward signals into optical signals, respectively, transmitting the converted optical signals to a remote access unit (RAU), converting a TDD upward signal and an FDD upward signal, which have been transmitted as optical signals from the RAU, into electric signals, respectively, and using an optical circulator in order to separate upward and downward signals from each other; and the RAU for converting the TDD downward signal and FDD/broadcasting downward signals transmitted from the CAP into electric signals, respectively, converting the TDD upward signal and FDD upward signal to be transmitted to the CAP into optical signals, respectively, and using an optical circulator in order to separate upward and downward signa

Abstract: An audio and video synchronization apparatus and method in a wireless communication network are provided. The audio and video synchronization apparatus includes a receiver that receives audio frames and video frames, a playback buffer that sequentially buffers the audio frames, a detector that determines whether the audio frames are synchronized with the video frames and adjusts a playback time of the video frames based on a playback time of the audio frames if it is determined the audio frames are not synchronized with the video frames.

Abstract: A radio over fiber (ROF) link apparatus capable of a stable TDD wireless service for a time division duplexing (TDD) baseband signal includes a central access platform (CAP) for receiving various kinds of data including the TDD baseband signal from upper layers, multiplexing the data, electro-optically converting the multiplexed data, and transmitting the converted data as downstream data through an optical fiber, and opto-electrically converting upstream data received through the optical fiber, demultiplexing the converted upstream data, and transmitting the demultiplexed upstream data to the respective upper layers, and a remote access unit (RAU) for receiving the downstream data through the optical fiber, opto-electrically converting the received downstream data to the multiplexed data, demultiplexing the multiplexed data, performing a wireless access process of the demultiplexed data, and transmitting the wireless access processed data to a wireless local area network (WLAN) service terminal through an an

Abstract: The present invention relates to a multi fixed-point cell for calibrating a thermometer and a thermometer calibration apparatus using the same, wherein measuring errors can be checked by using a property of constant temperature of a metal on the basis of a phase transition and wide range of temperature region can be measured by one time calibration, thereby capable of increasing efficiencies of time and cost which are taken for calibration. In a multi fixed-point cell for calibrating a thermometer according to the present invention, a thermometer inserting hole in which a thermometer is inserted is formed at one side and at least two reference material inserting holes in which reference materials having different phase transition temperatures are inserted respectively are formed on a same plane as that of the thermometer inserting hole so as to be spaced apart each other.

Abstract: Disclosed are a method of transmitting/receiving streaming data, to which a bit rate suitable for a mobile communication terminal is applied, in a communication system including a server and the mobile communication terminal, and a communication system therefor. The communication system include the server for converting multimedia data into the streaming data, and transmitting the streaming data to the mobile communication terminal; and the mobile communication terminal for, on receiving the streaming data from the server, collecting streaming parameters for use to determine the bit rate, and newly determining the bit rate.

Abstract: A remote access unit (RAU) apparatus, coupled to a central station (CS) of an RoF network through at least one optical fiber, and which RAU apparatus includes at least one antenna, includes: first and second antenna ports coupled to the at least one antenna; first and second optical fiber ports coupled to the at least one optical fiber; a first coupler for decoupling a first downstream signal of a first duplexing method and a second downstream signal of a second duplexing method, which are input through the first optical fiber port; a circulator for outputting the first downstream signal input from the first coupler to the first antenna port and outputting a first upstream signal of the first duplexing method input from the first antenna port to the second optical fiber port; and a second coupler for outputting the second downstream signal input from the first coupler to the second antenna port and outputting a second upstream signal of the second duplexing method input from the second antenna port to the sec

Abstract: A method for compressing an extension field to be selectively included in a Real-time Transport Protocol (RTP) header is provided. It is determined whether an RTP header extension field is included in the RTP header. Information indicating a determination result is recorded. Profile information of the RTP header extension field is recorded. Total length information of the RTP header extension field is recorded. Information indicating whether changed data exists is recorded using a header extension information map.

Abstract: A method for performing an encrypted voice call between a first terminal and a second terminal supporting a Voice over Internet Protocol (VoIP)-based voice call. In the method, the first and second terminals generate and store a bio key using biographical (bio) information of a user in advance before performing a voice call, the first terminal sends a request for a voice call to the second terminal and establishing a session, the first and second terminals exchange and store a bio key stored in each terminal, and the first and second terminals generate a session shared key using the exchanged bio key and starting a Secure Real-time Transport Protocol (SRTP) session, and a restored bio key by acquiring bio information from received data. User authentication is then performed by comparing the bio key with the restored bio key.

Abstract: Disclosed is a remote access unit for transmitting and receiving upstream and downstream data in which channels having different transmission scheme are multiplexed, and an optical network for bi-directional wireless communication using same. The remote access unit includes an antenna for receiving the downstream data and wirelessly transmitting same and for receiving the upstream data and providing same to the remote access unit, a switch for outputting downstream time division channels of the downstream data to the antenna and for receiving upstream time division channels of the upstream data from the antenna, and a controller for controlling the switch in order to prevent the upstream and downstream time division channels from overlapping.

Abstract: A system and method for video quality assessment includes utilizing codec auxiliary information related to the encoding and decoding process to enhance performance of picture quality assessment. In a video transmission system, video quality assessment can be accurately performed in real time with reduced computational load upon the client. In particular, the server performs first picture quality assessment and sends the assessment result to the client, and the client performs second picture quality assessment only when a transmission error occurs to reduce the computational load on the client.

Abstract: A method for setting an output bit rate for video data transmission in a WiBro system in which an uplink state value for a predetermined unit time is calculated to determine an uplink network state of the predetermined unit time. An average of uplink state values for a predetermined number of unit times is calculated, and a video encoding bit rate is increased if the average of the uplink state values is larger than a predetermined first threshold. However, the video encoding bit rate is decreased if the average of the uplink state values is less than a predetermined second threshold.

Abstract: Disclosed is a method for detecting a scene change in real time in order to control a moving-picture encoding data rate, the method including: dividing a current frame into a plurality of regions, and calculating a dissimilarity metric (DM) of each divided region; determining if the dissimilarity metric of each divided region is beyond a preset reference value; calculating the number of regions, the dissimilarity metric of which is beyond the preset value, in the current frame; and determining that a scene change occurs in the current frame, when the number of regions, the dissimilarity metric of which is beyond the reference preset value, is equal to or greater than a preset threshold value.

Abstract: Disclosed is a method for controlling bit rates in consideration of wireless channel environment by an apparatus that transmits and receives moving picture encoding data via a wireless network. The apparatus for transmitting/receiving data through a wireless communication network connected to the apparatus including a channel state analyzing unit for analyzing a wireless channel environment, an encoding controller for generating control information containing information about a quantization parameter, skip or non-skip of frames indication, frame type indication, and use or non-use of an Error Resilient Tool (ERT) indication, in consideration of an analyzation result received from the channel state analyzing unit, a moving picture encoding unit for encoding incoming moving picture data, based on the control information received from the encoding controller; and a data transmitting/receiving unit for transferring the encoded moving picture data through the wireless channel to an exterior.

Abstract: An optical transmitter for generating return-to-zero alternative-mark-inversion (RZ-AMI) optical signals and a method for generating the optical signals are provided. The optical transmitter includes a light source radiating at its output an intensity-modulated light beam based upon intensity of a first data, a precoder for precoding a second data having the information identical to the first data, and a Mach Zehnder modulator for phase-modulating the intensity-modulated light on basis of the precoded second data to generate a return-to-zero alternative-mark-inversion (RZ-AMI) optical signal.

Abstract: A cross-layer optimization method for controlling a bit rate of a video coder/decoder (codec) in video data transmission for wireless devices such as a wireless broadband (WiBro) system terminal that adapts to changing transmission/reception characteristics and usage. The method typically includes checking, by a sender, radio channel state information of a sender side and a receiver side; determining, by the sender, a transmission bit rate of a video codec by using the radio channel state information of the sender side; and adjusting, by the sender, the transmission bit rate of the video codec by using the radio channel state information of the receiver side when a communication network used by a receiver typically based on the type of a communication network being used by the sender.

Abstract: Disclosed is a data transmission method for an MBS in a broadband wireless access system. The method includes the steps of constructing a Wibro frame by adding an FEC zone to a downlink portion of the Wibro frame by a radio access station, the FEC zone containing an FEC packet for performing a packet-based FEC scheme; and transmitting data to a plurality of mobile stations by the radio access station, the Wibro frame constructing the data.

Abstract: A mobile communication system for providing a multicast/broadcast service is disclosed. The mobile communication systems comprise a base station that encodes video data of the mobile communication system into scalable bit streams and adaptively modulates and channel codes the scalable bit streams. A mobile communication terminal receives, demodulates and channel decodes the scalable bit streams transmitted from the base station and performs a process for scalable decoding the bit streams according to reception sensitivity. Overall system efficiency can be improved while increasing a transmission rate using scalable video coding according to channel characteristics between the mobile communication terminal and the base station in the multicast/broadcast service. Quality of service (QoS) can be provided based on the performance of the mobile communication terminal.