Abstract: Method and device for exchanging messages in a VLC navigation system is provided, in which a map server generates a provision message in the form of visible light signals through all lamps in an area, using a PLC network, where a navigation service is provided, a terminal that wants to implement the navigation service among terminals that have received the provision message transmits a registration request message to the map server, the map server transmits a registration response message for the registration request message to the terminal, the terminal transmits a map request message including information about a destination to the map server, the map server transmits a map response message including information about a path to the destination to the terminal, and the terminal displays map information and the path.

Abstract: Disclosed is a method for transmitting data in a wireless visible light communication system, the method including the steps of transmitting a pilot signal for obtaining channel state information according to each channel from a transmitter to a receiver, and transmitting a pilot response signal containing channel state information according to each channel from the receiver to the transmitter; controlling, by the transmitter, a data rate according to the pilot response signal, transmitting, by the transmitter, data to the receiver, with data rate information inserted into a header and controlling, by the receiver, a data rate according to each channel by making reference to data included in the header information.

Abstract: Method and device for exchanging messages in a VLC navigation system is provided, in which a map server generates a provision message in the form of visible light signals through all lamps in an area, using a PLC network, where a navigation service is provided, a terminal that wants to implement the navigation service among terminals that have received the provision message transmits a registration request message to the map server, the map server transmits a registration response message for the registration request message to the terminal, the terminal transmits a map request message including information about a destination to the map server, the map server transmits a map response message including information about a path to the destination to the terminal, and the terminal displays map information and the path.

Abstract: Automatic Repeat reQuest (ARQ) apparatus and method of a Multiple Input Multiple Output (MIMO system are provided. The ARQ method includes decoding, when one or more packets are received, the received packets and trying to detect the decoded packets; and storing, when error is detected from the packets, the corresponding error packet, requesting a transmitter to retransmit N-ary packets from which the error is detected and to transmit (M-N)-ary new packets when the number of the error packets N is smaller than the total number of the transmitted packets M. Accordingly, the error rate of the retransmitted data can be minimized, the number of retransmissions can be decreased, and the overall data transmission rate can be raised.

Abstract: A method and apparatus for transmitting/receiving an ACKnowledgement/Negative ACKnowledgement (ACK/NACK) signal to support packet data retransmission in an Frequency Division Multiple Access (FDMA) wireless communication system are provided, in which a User Element (UE) generates an ACK/NACK signal for received packet data, determines whether the UE is set to support ACK/NACK repetition, transmits the ACK/NACK signal on a basic response channel mapped to one of a DCH on which the packet data was received and a Shared Control Channel (SCCH) carrying scheduling information about the packet data, if the UE is not set to support ACK/NACK repetition, and selects one of supplementary response channels for each ACK/NACK repetition, the supplementary response channels being allocated for ACK/NACK repetition and repeatedly transmits the ACK/NACK signal on the selected supplementary response channel according to a predetermined repetition factor, if the UE is set to support ACK/NACK repetition.

Abstract: A wireless charging method and apparatus wirelessly charges power between separate electronic appliances. The wireless charging method includes searching for at least one chargeable electronic device, receiving status information from the searched at least one electronic device, determining whether the electronic device is a power supply electronic device or a power demand electronic device, receiving a supply of power from the searched at least one electronic device if the electronic device is determined to be the power demand electronic device, and supplying the power to the at least one electronic device if the electronic device is determined to be the power supply electronic device.

Abstract: A bidirectional wireless charging method includes performing a mode change to a requesting electronic device if charging is necessary, requesting charging from at least one electronic device, receiving status information from the at least one electronic device that has received the charging request, selecting the electronic device based on the status information, and performing charging by receiving power supplied from the selected at least one electronic device.

Abstract: A wireless charging method includes searching one or more rechargeable electronic devices, receiving power service information from one or more searched electronic devices, determining whether the one or more searched electronic devices are rechargeable based on the received power service information, and if the one or more searched electronic devices are rechargeable, receiving power from the electronic devices.

Abstract: A method for wireless charging of an electronic apparatus includes: requesting a server for information regarding chargeable electronic devices; receiving the information regarding chargeable electronic devices from the server; and performing charging with at least one electronic device.

Abstract: A method and apparatus for setting transmission power of a data channel by a mobile station in a Frequency Division Multiple Access (FDMA) system. The power setting method and apparatus includes receiving scheduling information from a base station; comparing a data rate of desired transmission data with a data rate of the scheduled data; if the data rate of desired transmission data is less than the data rate of the scheduled data, adjusting a currently set transmission power offset value according to the data rate of desired transmission data and the data rate of the scheduled data; and setting transmission power of the data to be transmitted to the base station using the adjusted transmission power offset value, and transmitting the data using the set transmission power value.

Abstract: The need for backup diesel generators in a data center is obviated by using fuel cells to convert a fuel to electrical energy, which provide backup power to equipment in a data center, which may include the servers in the data center and other important systems that normally use utility power. When the utility power fails, the equipment switches to backup power that is provided by fuel cells supplied with fuel (such as natural gas), possibly using a source of temporary power (e.g., a UPS or direct tie-in of batteries) while the fuel cells come online. The fuel may also be used to power a turbine or generator, coupled to a chiller for providing a cooled liquid to a cooling system.

Abstract: To avoid the need to operate in-chassis fans to cool rack-mounted servers in a data center, the data center is arranged into a hot aisle and a cold aisle. The cold aisle is adjacent to a first side of the rack mounted servers and receives cold air from a cold air supply unit. The hot aisle is adjacent to a second side of the rack-mounted servers and has a lower pressure than the cold aisle. Because of the pressure difference between the cold aisle and the hot aisle, cold air flows through the rack-mounted servers, cooling electronic equipment therein, into the hot aisle. Control systems are used to obtain sufficient cooling.

Abstract: An apparatus and method for Automatic Repeat reQuest (ARQ) in a Multi Input Multi Output (MIMO) system. The method includes computing weights of erroneous packets and weights of transmitting antennas by using channel information; sorting the weights of the erroneous packets in descending order; sorting the weights of the transmitting antennas in ascending order; and assigning the transmitting antennas to the erroneous packets according to sorting results.

Abstract: Provided is a method for operating multi-type beacons by a first terminal connected with at least one second terminal through short-range communication. The method includes checking at least one variable related to the second terminal, allocating one selected from a plurality of beacons having different characteristics to the second terminal, taking into account the checked variable, and transmitting the beacon allocated to the second terminal.

Abstract: The need for an uninterrupted power supply (UPS) in a data center is obviated by tying a DC voltage from a backup power source directly to the motherboards of multiple servers in the data center. AC power received from a power utility service is converted into a lower voltage by a site transformer and then provided to one or more power distribution units at a site. The power distribution units supply power to a plurality of servers, which include power supplies that convert the AC electrical power to DC electrical power for use by the servers' motherboards. In the event of a failure of power from the utility service, the backup power source provides DC electrical power to the motherboards, e.g., for sufficient time to start up a generator to provide power in place of the utility service.

Abstract: Short range wireless communication is provided. A first node included in a Wireless Body Area Network (WBAN) communicates with at least one neighboring second node. The first node transmits or receives data to or from at least one device node connected to the first node during a time division communication period, using a super-frame in which the time division communication period, a time division schedule advertisement message transmission period, and a Contention Access Period (CAP) are sequentially arranged. The first node broadcasts a time division schedule advertisement message of the first node to the at least one second node during the time division schedule advertisement message transmission period within the super-frame.

Abstract: A self-organizing resource access method is provided for transmitting data by self-organizing resource access by each individual node in a Local Area Network (LAN) communication environment where at least two nodes exchange data with each other. A first node listens to at least one data transmission of at least one other node connected to the LAN, and adjusts a data transmission start time of the first node in accordance with a data transmission start time of the at least one other node so that the data transmission start time of the first node does not overlap the data transmission start time of the at least one other node. The first node transmits data to the at least one other node at the adjusted data transmission start time.

Abstract: In multicarrier communication system using N subcarriers, in which a transmitter communicates with K receivers, the transmitter determines a channel quality information (CQI) feedback quantity indicative of the number of subcarriers for which CQIs will be fed back among the N subcarriers, for the K receivers, and transmits the CQI feedback quantity to the K receivers. Thereafter, upon receiving CQIs corresponding to the determined CQI feedback quantity, being fed back from the K receivers, the transmitter allocates subcarriers for which there are CQIs being fed back from at least one receiver among the K receivers among the N subcarriers, to any one receiver among the receivers that have fed back CQIs according to a first scheme, thereby guaranteeing the maximum throughput and the maximum fairness.

Abstract: A channel interleaving method and apparatus in a communication system using a low density parity check (LDPC) code. Upon receipt of information data bits, an encoder encodes the information data bits into an LDPC codeword using a predetermined coding scheme. A channel interleaver interleaves the LDPC codeword according to a predetermined channel interleaving rule. A modulator modulates the channel-interleaved LDPC codeword into a modulation symbol using a predetermined modulation scheme.

Abstract: Disclosed is a method for transmitting data in a wireless visible light communication system, the method including the steps of transmitting a pilot signal for obtaining channel state information according to each channel from a transmitter to a receiver, and transmitting a pilot response signal containing channel state information according to each channel from the receiver to the transmitter; controlling, by the transmitter, a data rate according to the pilot response signal, transmitting, by the transmitter, data to the receiver, with data rate information inserted into a header and controlling, by the receiver, a data rate according to each channel by making reference to data included in the header information.