Abstract: A method of Mission Critical Push to Talk (MCPTT) service performed by a mobile terminal includes: generating, at the mobile terminal, a group call announcement for off-network Mission Critical Push to Talk (MCPTT) service, the group call announcement for off-network MCPTT service including information of a period of the group call announcement for off-network MCPTT service; controlling a transceiver to periodically transmit, to one or more mobile terminals, the group call announcement for off-network MCPTT service based on the period; in response to the transmitted group call announcement for off-network MCPTT service, receiving a response from the one or more mobile terminals; and establishing, based on the response from the one or more mobile terminals, a group call with the one or more mobile terminals by setting a direct wireless communication with the one or more mobile terminals.

Abstract: A method for transmitting packets by a transmitter in a wireless communication network and retransmitting the packets not received correctly by receivers is discussed. The method includes transmitting the packets to at least two receivers, receiving reception acknowledgement response signals including ACK or NACK signals for the packets transmitted to the receivers, analyzing patterns of the received reception acknowledgement response signals in accordance with a number of the ACK or NACK signals, differently index coding the packets which are not received correctly by each receiver, and retransmitting the index-coded packets.

Abstract: A method of Mission Critical Push to Talk (MCPTT) service performed by a mobile terminal includes: generating, at the mobile terminal, a group call announcement for off-network Mission Critical Push to Talk (MCPTT) service, the group call announcement for off-network MCPTT service including information of a period of the group call announcement for off-network MCPTT service; controlling a transceiver to periodically transmit, to one or more mobile terminals, the group call announcement for off-network MCPTT service based on the period; in response to the transmitted group call announcement for off-network MCPTT service, receiving a response from the one or more mobile terminals; and establishing, based on the response from the one or more mobile terminals, a group call with the one or more mobile terminals by setting a direct wireless communication with the one or more mobile terminals.

Abstract: Provided is a method for retransmitting received data using index coding and statistical characteristics in a method for transmitting packets, by a transmitter, to at least two receivers in a wireless communication network and retransmitting packets which are not received correctly by each receiver, wherein the transmitter receives a reception acknowledgement response signal for the packets transmitted to the receiver and analyzes received patterns of the reception acknowledgement response signals transmitted from the receiver to differently perform index coding for each received pattern on the packets which are not received correctly by the receiver and retransmit the index-coded packets. According to the exemplary embodiment of the present invention, it is possible to effectively reduce a retransmission frequency of the packets which are not received correctly and a channel use frequency on communications and effectively use limited radio resources.

Abstract: An apparatus and a method for switching a Radio Access Technology (RAT) by a User Equipment (UE) in a wireless communication system are provided. The method includes detecting an event indicating that the UE should perform a switching operation from a first RAT to a second RAT different from the first RAT occurs while the UE uses the first RAT determining whether a RAT switching operation criterion is satisfied after detecting that the event occurs and if the RAT switching operation criterion is satisfied, performing the switching operation.

Abstract: An apparatus and a method for switching a Radio Access Technology (RAT) by a User Equipment (UE) in a wireless communication system are provided. The method includes detecting an event indicating that the UE should perform a switching operation from a first RAT to a second RAT different from the first RAT occurs while the UE uses the first RAT determining whether a RAT switching operation criterion is satisfied after detecting that the event occurs and if the RAT switching operation criterion is satisfied, performing the switching operation.

Abstract: Disclosed is a method and system for transmitting and receiving data in a communication system. The system includes a base station, and a relay station connecting the base station with at least one mobile station. The base station transmits data for a plurality of mobile stations to the relay station, and transmits the data to at least one mobile station belonging to the base station from among the plurality of mobile stations. The relay station receives the data from the base station, and transmits the data to at least one mobile station belonging to the relay station from among the plurality of mobile stations in the same interval as an interval where the base station transmits the data to the mobile station.

Abstract: An apparatus and method for transmitting/receiving a Channel Quality Information (CQI) in a communication system are provided. A Mobile Station (MS) receives first information indicating a representative MS selected from a group of MSs located within a preset range and in similar channel statuses, the group including the MS, determines from the first information whether the MS is designated as the representative MS, and transmits a CQI of the MS as a representative CQI of the MSs included in the group to a Base Station (BS), if the MS is designated as the representative MS.

Abstract: A data forwarding apparatus and method for reducing a HandOver (HO) interruption time in a wireless communication system where a macro cell and a femto cell coexist are provided. An operation method of a Mobile Station (MS) for data forwarding in a wireless communication system includes synchronizing with a serving Base Station (BS) after completing a HO procedure with a target BS, and receiving data packets existing in a queue through an air link directly from the serving BS.

Abstract: A technique for managing a packet to be transmitted to a Mobile Station (MS) that performs Relay Station (RS) handover in a multi-hop relay Broadband Wireless Access (BWA) system is provided. In the BWA system, a Base Station (BS) includes a controller for determining whether to perform activecasting on an MS upon receiving an activecast request message; a scheduler for allocating a resource by taking into consideration a channel condition between the MS and a serving RS when activecasting is determined to be performed; and a transmitter for multicasting a packet, which is to be transmitted to the MS, to a target RS and the serving RS by using the allocated resource.

Abstract: Disclosed is a system and method for transmitting data based on an operational state of a mobile station in a communication system. The method includes, when detecting a low battery state of the mobile station, storing one or more data packets to be transmitted to the mobile station, extracting at least one data packet, which has a transmission delay time larger than a difference between a maximum delay time and preset margin, from the one or more stored data packets, and transmitting at least a part of the extracted at least one data packet to the mobile station by using a resource allocated to the mobile station.

Abstract: Provided is an apparatus and method for transmitting/receiving signals in a communication system. A base station allocates a quasi-dedicated control channel (QDCCH) to a first mobile station (MS), and allocates the QDCCH allocated to the first MS, to a second MS for a preset time. An MS receives a QDCCH allocated from the base station. If there is data to transmit to the base station, the MS determines whether the QDCCH is allocated to another MS different from the MS. If it is determined that the QDCCH is allocated to the MS itself, the MS transmits the data to the base station over the QDCCH.

Abstract: A system and method for transmitting resource allocation information in a wireless communication system is provided. A transmitter transmits resource allocation information mapped to a current time interval in a first region to a receiver, and transmits resource allocation information mapped to a next time interval in a second region. When receiving the resource allocation information of the second region, the receiver notifies the transmitter whether the resource allocation information has been received. The transmitter receives notification that the resource allocation information of the second region has been received and transmits resource allocation information mapped to a subsequent time interval in the second region.

Abstract: A method of reporting channel state information by a Mobile Station (MS) in a mobile communication system is disclosed. The method includes measuring a state of a downlink channel for the entire frequency band, determining a first Modulation and Coding Scheme (MCS) level corresponding to the measured channel state, and reporting the determined MCS level to a Base Station (BS).

Abstract: A data forwarding apparatus and method for reducing a HandOver (HO) interruption time in a wireless communication system where a macro cell and a femto cell coexist are provided. An operation method of a Mobile Station (MS) for data forwarding in a wireless communication system includes synchronizing with a serving Base Station (BS) after completing a HO procedure with a target BS, and receiving data packets existing in a queue through an air link directly from the serving BS.

Abstract: A method of compressing uplink control information in a wireless communication system where an MSS scans neighbor BSs upon request from a serving BS and transmits neighbor BS information to the serving BS. In the method, the serving BS broadcasts a neighbor advertisement message including the BS ID of at least one neighbor BS about which the serving BS wants to acquire information, and the BS ID of the at least one neighbor BS. The MSS then scans a channel from the at least one neighbor BS and transmits a scanning result along with a BS index of the at least one neighbor BS to the serving BS.

Abstract: A method of scheduling uplink resources in a wireless communication system supporting VoIP service is provided. A BS allocates an identical amount of the resource continuously until an uplink data rate is changed by an SS's request for a data rate change. When the data rate is changed, the SS reports this event to the BS so that the BS allocates an amount of resource corresponding to the requested data rate.

Abstract: Disclosed is a method and system for transmitting and receiving data in a communication system. The system includes a base station, and a relay station connecting the base station with at least one mobile station. The base station transmits data for a plurality of mobile stations to the relay station, and transmits the data to at least one mobile station belonging to the base station from among the plurality of mobile stations. The relay station receives the data from the base station, and transmits the data to at least one mobile station belonging to the relay station from among the plurality of mobile stations in the same interval as an interval where the base station transmits the data to the mobile station.

Abstract: Disclosed is a system and method for transmitting data based on an operational state of a mobile station in a communication system. The method includes, when detecting a low battery state of the mobile station, storing one or more data packets to be transmitted to the mobile station, extracting at least one data packet, which has a transmission delay time larger than a difference between a maximum delay time and preset margin, from the one or more stored data packets, and transmitting at least a part of the extracted at least one data packet to the mobile station by using a resource allocated to the mobile station.

Abstract: An apparatus and method for transmitting/receiving a Channel Quality Information (CQI) in a communication system are provided. A Mobile Station (MS) receives first information indicating a representative MS selected from a group of MSs located within a preset range and in similar channel statuses, the group including the MS, determines from the first information whether the MS is designated as the representative MS, and transmits a CQI of the MS as a representative CQI of the MSs included in the group to a Base Station (BS), if the MS is designated as the representative MS.