Abstract: A video transmission method is provided, which includes receiving state information from at least one mobile terminal that intends to perform a video stream service through a wireless network, determining a size of an image by selecting a specified spatial layer bit stream on the basis of the state information of the mobile terminal from a plurality of spatial layer bit streams generated at different bit rates during encoding of the bit stream, selecting a specified time and an SNR layer bit stream by increasing or decreasing time of the image and a layer position of the SNR layer bit stream on the basis of network parameters included in the state information of the mobile terminal, and transmitting the bit stream generated by extracting the specified layer bit stream of the selected layer to the mobile terminal.

Abstract: A client apparatus, a server, and a control method thereof are provided. The client apparatus includes a display, a user interface which receives a text input, a communication interface which transmits to the server information related to input text, a storage which receives a result of analysis of the information transmitted from the server and stores the same, and a controller which performs control operations so that, in response to the text input being received via the user interface after the result of the analysis received, the received text is converted based on a stored result of the analysis, before being displayed.

Abstract: A client apparatus which performs communication with a server is provided. The client apparatus includes a display unit which receives a user's touch manipulation through a touch sensor; a communication interface unit which transmits information corresponding to the user's touch manipulation to the server; and a control unit which, when an image corresponding to the user's touch manipulation is received from the server through the communication interface unit, controls the display unit to display the received image.

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: 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 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: Provided is a handoff processing method including measuring a moving speed of a mobile terminal; measuring a size of a data packet generated in an application layer; measuring quality of a data transmission channel of the mobile terminal; calculating a maximum handoff delay time based on a relation between the moving speed and the data packet's size; estimating a handoff occurrence time point, based on a relation between a variation of the quality of the data transmission channel and the quality of the data transmission channel; and calculating a packet size and a moving speed of the mobile terminal that can minimize a delay due to a handoff occurrence by taking account of a handoff delay time according to the size of the data packet generated in the application layer and a moving speed of the mobile terminal into consideration, and providing the calculated packet size and moving speed.

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 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: A method and apparatus for receiving streaming data is provided. The method includes establishing a plurality of real-time streaming protocol (RTSP) sessions for receiving the streaming data, and receiving the streaming data through the plurality of RTSP sessions.

Abstract: A system and method for retransmitting an Internet protocol packet for terrestrial digital multimedia broadcasting (DMB) service are provided, in which a PES packetizer and an MPEG-2 TS multiplexer are removed; video, audio, and data signals are individually carried by RTP packets; and a receiver extracts object clock reference (OCR) included in a MPEG-4 SL, and synchronizes a system clock and controls buffers by means of the OCR.

Abstract: A jitter correction method of a transmitting device, a jitter correction method of a receiving device, a transmitting device, and a receiving device are provided. The jitter correction method of the transmitting device includes: determining a time stamp of a video frame; determining a transfer time of an real-time transport protocol (RTP) packet that includes at least a part of the video frame as a payload; generating the RTP packet including the time stamp and the transfer time; and transmitting the RTP packet to a receiving device.

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 portable terminal and power supply control method are provided. The portable terminal having a power supply control feature includes a main battery for supplying power to the portable terminal, an auxiliary battery for supplying power to the portable terminal independently of the main battery, a switch module for controlling the power supply of the main battery and auxiliary battery, and a power unit controller for controlling on-off settings of the switch module and for disconnecting, when a battery level of the main battery is higher than that of the auxiliary battery, the auxiliary battery from the main battery. The battery levels of the main battery and auxiliary battery are measured and are controlled to prevent charging of the auxiliary battery with a charge current from the main battery through switch settings.

Abstract: A video transmission method is provided, which includes receiving state information from at least one mobile terminal that intends to perform a video stream service through a wireless network, determining a size of an image by selecting a specified spatial layer bit stream on the basis of the state information of the mobile terminal from a plurality of spatial layer bit streams generated at different bit rates during encoding of the bit stream, selecting a specified time and an SNR layer bit stream by increasing or decreasing time of the image and a layer position of the SNR layer bit stream on the basis of network parameters included in the state information of the mobile terminal, and transmitting the bit stream generated by extracting the specified layer bit stream of the selected layer to the mobile terminal.

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