Abstract: A device communicating with a node, includes a communication unit configured to transmit a transmitting data segment to the node, and receive a receiving data segment from the node. The device further includes a phase locked loop (PLL) configured to generate an operating frequency for the communication unit. The device further includes a PLL controller configured to control a hold time and a lock time, of the PLL, that are shared between the node and the device. The device further includes a scheduler configured to schedule the transmitting data segment and the receiving data segment based on the controlled hold time and lock time.

Abstract: An apparatus and method for hierarchical modulation and demodulation in a wireless communication network are provided. A hierarchical modulation apparatus may map information bits to a plurality of levels based on a predetermined level map, may generate an error verification code for each of the levels based on the information bits mapped to the levels, may generate coded information bits for each of the levels, and may map bits in a predetermined position among the coded information bits, to Pulse-Position Modulation (PPM) symbols in a sequence of the levels.

Abstract: A method and apparatus for notifying status of an MN in a WLAN system using VLC are provided, in which an AP allocates a first predetermined number of time slots per frame as unallocated slots, for status notification of an initially accessing MN and allocates a second predetermined number of time slots per frame as reserved slots, for status notification of an initially accessing MN and uplink data transmission of an MN, and the MN transmits a visible light signal carrying status information about the MN in one of an unallocated slot and a reserved slot, if the MN initially accesses the AP.

Abstract: A communication device for detecting a collision in an operating frequency band and another frequency band, and a communication method thereof. The communication method includes transmitting or receiving a packet using an operating frequency band. The communication method further includes detecting whether another communication device transmits another packet using another frequency band different from the operating frequency band while the transmitting or the receiving of the packet using the operating frequency band. The communication method further includes ceasing the transmitting or the receiving of the packet using the operating frequency band based on a result of the detection.

Abstract: A low power radio device and a radio resource sharing method for the low power radio device are provided. In the low power radio device, a channel state (CS) is detected by carrier sensing before transmission of each frame to reduce interference and a need of retransmission of each frame, accordingly, reducing energy consumption.

Abstract: A communication method of a coordinator in a bidirectional event transmission sensor network comprising a sensor node and the coordinator is provided. The method includes sensing, in an uplink section, whether a signal having energy greater than or equal to a predetermined magnitude is received, the signal indicating occurrence of an uplink event detected by the sensor node, and transmitting, to the sensor node in a downlink section, a synchronization packet that is used for receiving the uplink event or for transmitting a downlink event in response to the coordinator detecting the downlink event or sensing the signal having energy greater than or equal to the predetermined magnitude in the uplink section.

Abstract: A method for retransmitting data when data transmission/reception has failed in a wireless LAN system using visible light communication. A mobile node searches a received frame for a fast feedback slot allocated for retransmission information when momentary data transmission/reception failure has occurred. One mini-slot from among the plurality of mini-slots is selected from the fast feedback slot. The mobile node transmits a fast feedback message, including information for retransmission, to an access point by using the selected mini-slot.

Abstract: Apparatuses and methods for processing a bandwidth request in a multihop relay Broadband Wireless Access (BWA) communication system are provided. A communication method of a Relay Station (RS) includes determining a number of bandwidth request ranging codes received from Subscriber Stations (SSs); and reporting the number of the bandwidth request ranging codes to a Base Station (BS). A communication method of the BS includes allocating a resource to an RS to report on a number of detected bandwidth request ranging codes; and receiving a report on the number of the bandwidth request ranging codes using the allocated resource.

Abstract: An apparatus and method for UpLink (UL) radio resource allocation in a wideband wireless communication system are provided. In a method of operating a Relay Station (RS) for UpLink (UL) radio resource allocation in a wideband wireless communication system, the method includes relaying to a Base Station (BS) a resource request message of at least one or more Mobile Stations (MSs); receiving data from the at least one or more mobile stations; if the received data is non-real time traffic, queuing the data received from the mobile stations according to a traffic type; and requesting the base station to allocate necessary radio resources by checking a queue status. Accordingly, a delay can be reduced when the UL resource is allocated to an relay station for real time traffic.

Abstract: Provided are an ARQ apparatus and method for a multihop system in a broadband wireless access communication system. The ARQ method of a relay includes determining if the relay successfully receives specific data from a source and transmitting the specific data to a destination; receiving feedback data from the destination and determining if the destination successfully receives the specific data; generating feedback data including data indicating if the relay and the destination successfully receive the specific data, and outputting the feedback data to the source; and retransmitting the specific data, when the relay successfully receives the specific data but the destination fails to receive the specific data. Accordingly, when the MH-BTS successfully receives the data from the source but the destination fails to receive the data, the source does not retransmit same data to the MH-BTS.

Abstract: Provided is an apparatus and method for determining a data transmission rate in consideration of the queue length of a Relay Station RS in a multi-hop relay system. A Base Station BS apparatus of the multi-hop relay system includes a receiver and a calculator. The receiver receives channel condition information and queue length information for a Mobile Station MS from an RS. The calculator of the BS apparatus determines a data transmission rate between the BS and the RS for data of the MS using the channel condition information and the queue length information.

Abstract: A cognitive radio-based wireless communication system and an air interface method in a physical layer and a data link layer, which constitute a cognitive radio-based next-generation wireless communication system. The air interface method for wireless communication in the cognitive radio-based wireless communication system of the present invention is provided in the cognitive radio-based wireless communication system including a base station system and a plurality of mobile station systems. The base station system and a certain mobile station system communicate with each other using an overlay method that uses a spectrum hole. The base station system and the mobile station system switch from the overlay method to an underlay method to communicate with each other when a paying user having high priority performs communication using the spectrum hole.

Abstract: Disclosed herein are a method of communicating and establishing a relay channel between a base station and a non-line-of-sight channel terminal in a next generation cellular communication system.

Abstract: Provided is a multi-hop wireless mobile communication system where a plurality of nodes exist. To select a serving node to be provided with a service, a Mobile Station (MS) receives relay information provided for serving node selection from at least two nodes and selects a first mode of selecting a node that requires the minimum time for unit data transmission/reception as the serving node or a second mode of selecting a node that can transmit and receive the maximum data per unit time as the serving node, based on the received relay information, in order to select the serving node.

Abstract: A method for retransmitting data when data transmission/reception has failed in a wireless LAN system using visible light communication. A mobile node searches a received frame for a fast feedback slot allocated for retransmission information when momentary data transmission/reception failure has occurred. One mini-slot from among the plurality of mini-slots is selected from the fast feedback slot. The mobile node transmits a fast feedback message, including information for retransmission, to an access point by using the selected mini-slot.

Abstract: A method and apparatus for notifying status of an MN in a WLAN system using VLC are provided, in which an AP allocates a first predetermined number of time slots per frame as unallocated slots, for status notification of an initially accessing MN and allocates a second predetermined number of time slots per frame as reserved slots, for status notification of an initially accessing MN and uplink data transmission of an MN, and the MN transmits a visible light signal carrying status information about the MN in one of an unallocated slot and a reserved slot, if the MN initially accesses the AP.

Abstract: An apparatus and method for UpLink (UL) radio resource allocation in a wideband wireless communication system are provided. In a method of operating a Relay Station (RS) for UpLink (UL) radio resource allocation in a wideband wireless communication system, the method includes relaying to a Base Station (BS) a resource request message of at least one or more Mobile Stations (MSs); receiving data from the at least one or more mobile stations; if the received data is non-real time traffic, queuing the data received from the mobile stations according to a traffic type; and requesting the base station to allocate necessary radio resources by checking a queue status. Accordingly, a delay can be reduced when the UL resource is allocated to an relay station for real time traffic.

Abstract: The present invention relates to a cognitive radio-based wireless communication system and to an air interface method in a physical layer and a data link layer, which constitute a cognitive radio-based next-generation wireless communication system. The air interface method for wireless communication in the cognitive radio-based wireless communication system of the present invention is provided in the cognitive radio-based wireless communication system including a base station system and a plurality of mobile station systems. The base station system and a certain mobile station system communicate with each other using an overlay method that uses a spectrum hole. The base station system and the mobile station system switch from the overlay method to an underlay method to communicate with each other when a paying user having high priority performs communication using the spectrum hole.

Abstract: Apparatuses and methods for processing a bandwidth request in a multihop relay Broadband Wireless Access (BWA) communication system are provided. A communication method of a Relay Station (RS) includes determining a number of bandwidth request ranging codes received from Subscriber Stations (SSs); and reporting the number of the bandwidth request ranging codes to a Base Station (BS). A communication method of the BS includes allocating a resource to an RS to report on a number of detected bandwidth request ranging codes; and receiving a report on the number of the bandwidth request ranging codes using the allocated resource.

Abstract: Provided is an apparatus and method for determining a data transmission rate in consideration of the queue length of a Relay Station RS in a multi-hop relay system. A Base Station BS apparatus of the multi-hop relay system includes a receiver and a calculator. The receiver receives channel condition information and queue length information for a Mobile Station MS from an RS. The calculator of the BS apparatus determines a data transmission rate between the BS and the RS for data of the MS using the channel condition information and the queue length information.