Abstract: A network system using Mobile Internet Protocol (IP). The network system includes a correspondent node for transmitting a packet in which information passing a packet filter rule is included, and a packet filtering apparatus for determining whether an address included in information of the packet received from the correspondent node is identical to a destination address stored in the packet filter rule, and determining whether to pass the packet according to the determination result.

Abstract: A method and system for supporting a handoff of an MS in a PMIP mobile communication system are provided. The method includes a target node transmitting a first registration request message to an HA in order to request registration of the MS, when the MS moves from the service area of a serving node to the service area of the target node; the serving node discarding a second registration request message without processing the second registration request message, when the serving node receives the second registration request message from the MS before the target node receives a first registration response message for the first registration request message from the HA; and the serving node requesting deregistration of the serving node to the HA, when the target node receives the first registration response message from the HA.

Abstract: Disclosed is a method for calculating a routing cost or a hop count of a mobile IP (Internet Protocol) in an IP network. The IP network can communicate with the MN having a mobile IP and includes a plurality of access routers. If the MN moves to a new access router, the MN generates a distance measurement request message and transmits the generated distance measurement request message to an access router serving as a regional anchor point (RAP) of the MN. Upon receiving the distance measurement request message, the access router serving as the RAP generates an acknowledgement message having an initial hop limit field value and a hop limit value, and transmits the acknowledgement message. The MN calculates a hop count using the initial hop limit field value and the hop limit value.

Abstract: A security management method in a mobile communication system supporting Proxy Mobile Internet Protocol (IP). In the security management method, a Mobile Node (MN), a Serving Packet Data Service Node (S-PDSN), and an Authentication, Authorization and Accounting (AAA) server generate a security key of the Proxy Mobile IP. Upon receipt of information for authentication of a security key from the MN, the S-PDSN sends an access request message to the AAA server and receives information for verification of the security key. The S-PDSN sends a first message for requesting verification of the security-related key to a Home Agent (HA). The HA verifies the security-related key through the AAA server and sends a second message to the S-PDSN when the security-related key is verified. The S-PDSN sends a message indicating initiation of the Proxy Mobile IP, to the MN.

Abstract: A method for maintaining data transmission from a corresponding node when a mobile node moves from a first access router to a second access router in a network system, the method comprising: transmitting using the mobile node a home address of the mobile node and a one care-of address (CoA) assigned from the first access router to the corresponding node and a home agent, when the mobile node is located in the first access router; and transmitting using the mobile node the home address, the one CoA, and another CoA assigned from the second access router to the first access router so that data from the corresponding node is received via the first access router and the second access router, when the mobile node moves from the first access router to the second access router and the second access router is located within a predetermined distance from the first access router.

Abstract: A signal detection apparatus and method using a modified stack algorithm in a Multi-Input Multi-Output (MIMO) system are provided. The signal detection method includes sorting signals received via antennas and channel coefficients for respective users in descending order, decomposing a channel matrix composed of the sorted channel coefficients into a unitary matrix and an upper-triangular matrix, determining the number of candidate symbol-sequences using the decomposed upper-triangular matrix, obtaining a signal vector for the antennas by using the sorted signals received via respective antennas and the unitary matrix, wherein the signal vector is proportional to the upper-triangular matrix, and detecting the determined number of candidate symbol-sequences by using a modified stack algorithm while expanding a stack structure for the obtained signal vector.

Abstract: A method for controlling power in a communication system is disclosed. The power control method includes the steps of calculating a first offset according to traffic information of a mobile station and data transmission channel quality information of the mobile station, determining a second offset according to received channel quality information of the mobile station, received from the mobile station, determining a third offset according to interference information received from other base stations neighboring the base station, and transmitting, to the mobile station, power control information determined based on the first offset, the second offset and the third offset.

Abstract: An apparatus and method for lowering a tree searching complexity in a Spatial Multiplexing (SM) Multiple Input Multiple Output (MIMO) antenna system are provided. A transmitting apparatus includes a generator for generating a plurality of transmit streams by spatial-multiplexing a transmit data, a determiner for determining modulation schemes to be applied to the plurality of the transmit streams respectively and a modulator for modulating the plurality of the transmit streams using at least two modulation schemes under control of the determiner. The receiver detects the signals by allocating the modulation scheme of the lowest order to the upper tree level.

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: 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 are an Automatic ReQuest (ARQ) apparatus and method for a multihop system in a broadband wireless access communication system. When the number of ACK MAPs in ARQ feedback information element of ARQ feedback message transmitted from a destination or Multi-Hop Base Transceiver Station (MH-BTS) is not zero, and it is determined that the destination or a lower MH-BTS successfully receives data corresponding to Block Sequence Number (BSN), the BSN is updated with a BSN successfully received at the destination or the lower MH-BTS, and is transmitted to the upper MH-BTS or the source. 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 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 handover apparatus and method for a multi-hop system in a BWA communication network are provided. In a handover system supporting multi-hop system in a BWA communication network, a BS periodically broadcasts a message with neighboring BS/RS information. When a new BS or RS needs to be added, an RS periodically broadcasts the broadcast message received from the BS with information about the new BS or RS. An MS receives the broadcast message from the RS and requests information about BSs or RSs to which the MS can perform a handover by notifying candidate BSs or RSs for the handover. The candidate BSs or RSs may include a BS or RS not included in the broadcast message, if the MS detects the BS or RS by scanning. The MS selects a target BS or RS based on the BS or RS information received from the BS, and performs the handover to the target BS or RS.

Abstract: A method is provided for transmitting and receiving data in a multi-hop wireless mobile communication system having a first mobile station (MS), a second MS, a base transceiver station (BTS), and a relay BTS. The method includes allowing the first MS to directly communicate with the BTS, and allowing the second MS to communicate with the BTS by relay of the relay BTS; performing communication between the BTS and the first MS and communication between the relay BTS and the second MS using a first frame; and performing communication between the BTS and the relay BTS using a second frame.

Abstract: A method and apparatus of supporting a fast handover in a transport layer is provided. In a network using an SCTP (Stream Control Transmission Protocol), an MN (Mobile Node) acquires a first new IP (Internet Protocol) address after a first handover to a first new network area, stores information about the first handover to the first new network area, and sends (i.e., transmits) a first handover message including the new IP address to a CN (Correspondent Node). If a second handover to a second network area is required, the MN performs the second handover even if a response message for the first handover message has not been received, acquires a second new IP address, stores information about the second handover, and sends a second handover message including the second new IP address to the CN.

Abstract: A method and apparatus for supporting a seamless handover in a transport layer is provided. In a network using an SCTP, an MN notifies a CN of a handover after the handover occurs. The MN receives a handover confirm message from the CN and sends a response message for the handover confirm message to the CN. The MN checks a recipient IP address at which data is received from the CN. If the recipient IP address is a new IP address, the MN changes a primary IP address of the MN to the new IP address. If the recipient IP address is the primary IP address, the MN maintains the primary IP address.

Abstract: A method is provided for transmitting a packet data unit (PDU) by a transmitter in a wireless mobile communication system. The method includes determining at least one desired transmission PDU, determining a modulation scheme corresponding to the number of PDUs, and transmitting a first indicator value indicating the number of PDUs and the modulation scheme, transmitting the PDUs, receiving a second indicator value indicating a reception state of the PDUs, from a receiver that receives the PDUs, determining a new PDU or a retransmission PDU according to the second indicator value, and determining a modulation scheme corresponding to the number of the determined PDUs, and transmitting a third indicator value indicating the number of PDUs and the modulation scheme, and the corresponding PDUs.

Abstract: A method and system for performing an inter-FA handover in a communication system are provided. An MS receives from a serving BS neighbor BS information including a BS ID of at least one neighbor BS and a reference signal index of a reference signal used in the at least one neighbor BS. When it is necessary to scan the reference signal from the at least one neighbor BS, the MS scans the reference signal corresponding to the reference signal index. If the scanned reference signal has a quality equal to or greater than a threshold, the MS determines the BS ID of the at least one neighbor BS using the reference signal index as a BS ID for a recommended neighbor BS available for the inter-FA handover.

Abstract: Disclosed is a method of preventing a replay attack during a handoff in a communication system using a Mobile IPv6 protocol. A mobile node creates a CoA (Care of Address) by handoff and sends the CoA to a correspondent node, thereby creating a binding entry. Upon receipt of a binding update message including a HoA and a CoA from the mobile node or an attacker, the correspondent node searches a binding cache for a binding entry having the same HoA (Home Address) and CoA as included in the binding update message. If it is determined that the binding entry has the same respective HoA and CoA as contained in the binding update message, the correspondent node checks a Used field of the binding entry. If it is determined that the Used field of the binding entry is equal to a predetermined value, the correspondent node sends a reauthentication command message to the mobile node.

Abstract: Disclosed is a method for providing a multicast service when an MN performs handoff from a first AR to a second AR in a mobile IP communication system including the first AR and second AR. The MN is a source node for providing the multicast service to a number of receivers and currently performs communication with the first AR. The second AR is different from the first AR.