113 results about "Handover latency" patented technology

In next generation wireless networks such as a Mobile WiMAX traffic prioritization is used to provide differentiated quality of service (QoS). Unnecessary ping-pong handovers that result from premature reaction to fluctuating radio resources pose a great threat to the QoS of delay sensitive connections such as VoIP which are sensitive to scanning and require heavy handover mechanisms. Traffic-class-specific variables are defined to tolerate unbalance in the radio system in order to avoid making the system slow to react to traffic variations and decreasing system wide resource utilization. By setting thresholds to trigger load balancing gradually in fluctuating environment the delay sensitive connections avoid unnecessary handovers and the delay tolerant connections have a chance to react to the load increase and get higher bandwidth from a less congested BS. A framework for the resolution of static user terminals in the overlapping area within adjacent cells will be described.

In accordance with the present invention, computer implemented methods and systems are provided for reducing handoff latency in a wireless network. In response to detecting that a handoff is necessary, the present invention uses a selective scanning algorithm that includes the use of a channel mask and / or a caching algorithm for detecting one or more new access points.

Various embodiments are described to address the need for reduced handoff delays associated with inter-AN (access network) HRPD (High Rate Packet Data) / 1×EV-DO handoffs. The disclosed approach enables an AT (101) with an active packet data session to perform a hard handoff from a source AN (121, 221) to a target AN (122, 222) without having to force the data session dormant. Unlike known hard handoff approaches that involve coordination by a mobile switching center (MSC), the disclosed approach uses peer-to-peer signaling with no MSC involvement, such as that between source and target ANs or PCFs (131, 132, 231, 232). For example, data session information at the source side is transferred via new A13 messaging to the source entity's target-side peer to otherwise reduce signaling between the source and target equipment.

A buffered distributor (i.e., a full-duplex repeater) having receive buffers for respective network ports calculates pause frames based on the size of stored data packets that need to be output by the repeater core according to a round robin sequence before congestion in an identified receive buffer is eliminated. The distribution core within the buffered distributor includes a linked list register that stores the determined links of received data packets for each network port. Upon detecting a congestion condition in one of the receive buffers for a corresponding port, the buffered distributor determines the relative position of the congested port within the round robin sequence, and calculates the pause interval based on the length of the data packets that need to be output before congestion is eliminated. The sum of the data packet lengths are compared to an output data rate of the distribution core, as well as switching delays within the core. The calculated pause frames, in conjunction with the prescribed congestion threshold, ensures that buffer sizes can be efficiently designed at a low cost, without compromising cost or risk of lost data packets.

The present invention relates to a handover procedure, and more particularly, to a method of reducing latency in performing handover using fast ranging. The present invention includes the steps of receiving a handover message including a specific ranging code and uplink resource information from a serving base station and transmitting the specific ranging code to a target base station using the uplink information.

Provided is a probing method for handoff including constructing a group of neighbor access points of a current access point with which the station associated, generating subgroups of the neighbor access points by the channel assigned to the access points, probing the access points by subgroup in a subgroup selection order, and selecting the neighbor access point having best link quality as a target access point to handoff. The probing method of the present invention is implemented with a novel non-overlap graph for constructing the neighbor graph such that the probing latency is dramatically reduced, resulting in reduction of handoff delay.

Communication handover methods and apparatuses for use in an environment involving terminals having mobile nodes moving at a high speed. The handover method includes actively requesting handover to an access router based on the moving speed of a mobile node. The handover methods and apparatuses reduce handover latency and packet losses in a handover process of a terminal moving at a high speed.

A handover method and apparatus at a link layer of a wireless LAN according to the IEEE 802.11 standard are provided to minimize a handover latency. The handover method is performed in a mobile station moving from one subnet to another subnet, each subnet being managed by one of a plurality of access points. Channels available to the mobile station are selectively scanned based on information regarding one and more access points which are estimated to be present in a communication area of the mobile station, and a handover is performed to one of the access points based on the scanning result.

In the public WLAN systems, reliable user re-authentication for mobility support is an essential step. However, re-authentication during handoff procedures causes long handoff latency which deteriorates the quality of service specifically for real-time multimedia applications. One possible solution is to authenticate the Mobile Node (MN) in advance with all the neighboring Access Points (APs) and distribute the Session Keys to them. However, the key issue is how to optimally and efficiently select the neighboring APs. In the preferred embodiments, we propose a system that takes into account the user current “Geo-Location”, “Mobility Pattern” and “Application Running on MN”; estimates the “Expected Mobility Zone” (EMZ) and selects an appropriate set of candidate APs corresponding to the MN's geo-location. The EMZ may comprise of APs belonging to “Intra-domain”, “Inter-domain” or “Inter-technology Networks” (e.g., WLAN, WiMAX, and Cellular etc). The system assumes that not only the Mobile Nodes but also the Fixed Nodes (APs or Base Stations) are capable of knowing their Geo-Location Coordinates X, Y, Z. This capability may come either by integrating GPS receiver or through any other alternate, state of the art or future positioning technologies in the APs.

A method and an apparatus ensure efficient handover in a wireless communication system even when a User Equipment (UE) moves at a high speed. A serving eNB receives interference power information of an uplink (UL) signal and interference increase / decrease information of the UL signal from at least one adjacent eNB. an adjacent eNB, for which the received interference power information indicates that interference power of the UL signal is equal to or greater than a threshold value, is selected as a target eNB for a User Equipment (UE) among the at least one adjacent eNB. Whether handover of the UE is delayed is determined based on the interference increase / decrease information received from the target eNB. And if the handover of the UE is delayed, a handover parameter is transmitted to the UE to perform handover to the target eNB.

Methods for transporting a media call between an IMS server and a User Equipment (UE) and of handing over the media call between a cellular network and a WLAN are provided. In an embodiment, the media call data and signaling are split such that the data is transported over the WLAN and the signaling is transported over the cellular network. In another embodiment, handover latency is reduced by using a dual registration process that registers the UE with an IMS server using both a WLAN-based contact and a cellular network-based contact. The media call can then be carried over the WLAN and / or the cellular network and can be handed over seamlessly from one to the other within minimal signaling.

An apparatus, system, and method are directed to managing connectivity in a network by expediting the ability of a mobile node to send Internet Protocol (IP) packets subsequent to a handover. The mobile node is configured to determine an unconfirmed address for use on an access router. Upon establishing a link-layer connection, and before establishing a network-layer connection with the access router, the mobile node employs the unconfirmed address to send an IP packet to the access router. Employing the unconfirmed address prior to network-layer connectivity enables the reduction of handover latencies. If the access router determines that the unconfirmed address conflicts with an existing address, the access router provides a message to the mobile node indicating the conflict in addresses. In response to the message, the mobile node performs actions to resolve the address conflict.

A method for forwarding packets in handover between base stations (eNBs) is provided. A source eNB confirming handover success sends control data indicating an EOD of a forwarding packet to a target eNB when there are no more packets to be forwarded to the target eNB, and the target eNB receiving the control data recognizes from the control data that there are no more packets to be forwarded from the source eNB, thus preventing delay in the handover between the eNBs.

The present invention relates to an interference cancellation receiving method in an OFDMA mobile communication system, and an apparatus using the same. For this purpose, the present invention provides an interference cancellation receiving method for outputting a data symbol from which an interfering signal is canceled by receiving subcarriers including a data signal from a serving base station, the data signal including interfering signals from a neighboring base station and a remote base station, estimating a channel response of the serving base station and the neighboring base station by using at least one adjacent pilot subcarrier in the frequency axis or time axis, computing a weight value for canceling the interfering signals, and combining at least one data subcarrier having a repeated identical data symbol among received subcarriers with the weight value. According to the present invention, performance of receiving serving base station signals is improved, and a success rate of handoff is increased and handoff delay time is reduced by successful decoding of signals from a serving base station and a neighboring base station when handoff occurs.

User equipment (UE), an enhanced NodeB (eNB) and method of reducing handover latency are generally described. The UE may transmit measurement feedback to the eNB based on control signals. The UE may receive a reconfiguration message from the eNB or another eNB to the UE is attached. The reconfiguration message may contain reconfiguration information indicating whether or not a physical layer or layer 2 of the UE is to be reconfigured and / or a security key is to be updated. The reconfiguration information may be dependent on whether the handover is between eNBs controlled by a same entity and / or whether the handover comprises an intra-frequency transition. The UE or eNB may initiate handover of the UE. During handover the UE may avoid physical layer or layer 2 reconfiguration or the security key update. The security key and data for the UE may be provided directly between the eNBs.

An apparatus and a method for handover in a broadband wireless communication system supporting a Mobile Relay Station (MRS) are provided. The method includes transmitting a Connection ID (CID) of Mobile Stations (MSs), the CIDs pre-allocated by a target BS, to the MSs; sending a resource allocation message comprising uplink resource allocation information for bandwidth request of the MSs, to the MSs; receiving a bandwidth request message which comprises security authentication information of each MS, from the MSs using an uplink resource allocated through the uplink resource allocation information; and aggregating bandwidth request messages of the MSs and sending a ranging request message comprising the security authentication information and bandwidth request information of the MSs to the target BS. Thus, the handover delay time, which is inevitable for the bandwidth request in the conventional connection set-up procedure, can be reduced, and the handover with the reliability guaranteed can be achieved by allowing the security related processing in the network re-entry procedure.

The present invention relates to a handover method of a mobile station in a wireless communication system, and a base station and a mobile station for the same. A list of neighboring base stations that can accept a handover of a mobile station is shared by the mobile station and a serving base station before the mobile station performs the handover so as to reduce handover delay time in a high speed environment through addition, the active base station set managed by the mobile station and the serving base station can be managed with consideration of radio signal quality and resource state of each of the neighboring base stations included in the active base station set, and thus when the mobile station attempts a network re-entry process to a target base station that is not ready for the handover of the mobile station due to a loss of a handover control message, a handover failure due to a lack of radio resources can be prevented, thereby increasing a handover success rate.

The embodiment of the invention discloses a method for reducing handover delay in LTE systems. The method comprises that: source eNB sends a handover request to alternative target eNB of all alternative target cells of which the management meets handover judgment conditions, agrees to allow the alternative target eNB to which the alternative target cells with the handover request to reserve resources for current handover, and stores context of user equipment UE performing the current handover; and the alternative target eNB informs the source eNB of the information of the alternative target cells agreeing to the handover request. The method can trigger all alternative target eNB to be reserved resources for the current handover so as to reduce the handover delay caused by a currently selected target eNB not agreeing to hand over. In addition, in the process of handover execution, the source eNB simultaneously forwards data to all the alternative target eNB returning response to the handover request, so data loss caused by handover failure can be avoided.

Provided is a probing method for handoff including constructing a group of neighbor access points of a current access point with which the station associated, generating subgroups of the neighbor access points by the channel assigned to the access points, probing the access points by subgroup in a subgroup selection order, and selecting the neighbor access point having best link quality as a target access point to handoff. The probing method of the present invention is implemented with a novel non-overlap graph for constructing the neighbor graph such that the probing latency is dramatically reduced, resulting in reduction of handoff delay.

A handoff method is provided in a communication network including a plurality of fixed nodes attached to a router connected to at least one external network, and at least one mobile node associated with a current fixed node. The method detects movement of a mobile node; prepares a handoff of the mobile node from a current fixed node to potential fixed nodes upon detecting movement of the mobile node; decides whether to handoff to one of the potential fixed nodes as a target fixed node; and performs the handoff from the current fixed node to the target fixed node. The handoff method enables the mobile station to quickly move its association from one access point to another by minimizing a probe delay which is a primary contributor to handoff delay.

An object of the present invention is to avoid packet loss and implement a seamless handover by minimizing the handover latency when a handover is implemented by a multihomed moving network (MN) or a mobile host (MH). The present invention is a mobile communication system that is constituted comprising an MN, a plurality of AI each constituting an interface for the connection to a core network at the MN, and a control device (MMF), wherein the MMF dynamically changes the AI adopted as the connection interface when a predetermined condition is satisfied on the basis of the connection status to the core network at each AI or the prediction information for a subsequent handover. In so doing, the control device continues the transmission and receipt of data with respect to an appropriate AI capable of maintaining a predetermined communication quality, and maintains the connection to the core network of another AI while causing this AI to enter a closed state in which the transmission and receipt of data is disabled.

This invention relates to cognitive radio based wireless communications of dynamic spectrum access networks, and in particular to a method of addressing zero-delay frequency switching for cognitive dynamic frequency hopping. The method combines regular (periodic) channel maintenance with dynamic frequency hopping over a cluster of vacated channels that are initially setup such that the switching delays for channel setup and channel availability check are eliminated.

Handoff of (i) a mobile wirelessly communicating device—a mobile—between (ii) a plurality of stationary base stations within cells within a domain of (iii) a stationary gateway router all within (iv) a communications network based on the Internet Protocol (IP) is without interchange of control, and responsive to the mobile, only. The gateway router assigns to the mobile at a time before the handoff IP addresses suitable for the mobile to connect to the gateway router through all the plurality of base stations of the domain. Unilaterally deriving a handoff decision to switch base stations, the mobile directs its wireless communications link to a new base station where signal level registration is performed. Responsive to a link layer trigger at the new base station, the gateway router is informed of the handoff, and both the router and the mobile independently construct the mobile's new IP address. Handoff latency is typically 40 ms.

This invention provides a method and apparatus that uses a mobility management server (MMS) device for supporting mobility management in wireless networks. With the MMS device for services of resource management and packet relay, this invention speeds up the handover procedure for a mobile device switching from a first network domain to a second network domain in a wireless network environment having a session initiation protocol (SIP) server. When the mobile device needs to switch to the second network domain, the MMS allocates the required resources for packet relay, provides the related information for the second network domain, and takes care of the packet relay. This invention shortens the inter-domain handover latency and reduces the number of lost packets during the handover procedure. Thereby, the transmission efficiency of the present invention meets the requirement for real-time multimedia applications.

A method for providing a reverse link handoff mechanism includes, with respect to communication between a mobile station and a first cell, initiating a start of a cell switch delay by transmitting a request that a new data channel be established with a second cell. The method further includes communicating with the first cell during the cell switch delay and upon an end of the cell switch delay, switching data transmission to the second cell. The cell switch delay is a time interval extending from a time that the request is transmitted until startig of reception of data packets via the new data channel by the second cell. The application of the cell switch delay is determined based on a location of the first cell and the second cell.

A base station (109) of a cellular communication system (100) comprises an RNC interface (301) which receives a radio link handover initiation message for a radio link from a radio network controller (113). A switch delay processor (309) determines a handover switch delay and a characteristics processor (311) sets a characteristic of a radio link handover acknowledge message in response to the handover switch delay. A message generator (313) generates a radio link handover acknowledge message and transmits this to the radio network controller (113). The radio network controller (113) comprises an RNC handover controller (125) which determines a radio link handover switch time in response to the characteristic. A better timing of the radio link handover may be achieved. The invention may e.g. be applicable to an HSDPA (High Speed Downlink Packet Access) service of a UMTS (Universal Mobile Telecommunication System) cellular communication system and may reduce the amount of data discarded from buffers during an HSDPA handover.

In the public WLAN systems, reliable user re-authentication for mobility support is an essential step. However, re-authentication during handoff procedures causes long handoff latency which deteriorates the quality of service specifically for real-time multimedia applications. One possible solution is to authenticate the Mobile Node (MN) in advance with all the neighboring Access Points (APs) and distribute the Session Keys to them. However, the key issue is how to optimally and efficiently select the neighboring APs. In the preferred embodiments, we propose a system that takes into account the user current “Geo-Location”, “Mobility Pattern” and “Application Running on MN”; estimates the “Expected Mobility Zone” (EMZ) and selects an appropriate set of candidate APs corresponding to the MN's geo-location. The EMZ may comprise of APs belonging to “Intra-domain”, “Inter-domain” or “Inter-technology Networks” (e.g., WLAN, WiMAX, and Cellular etc). The system assumes that not only the Mobile Nodes but also the Fixed Nodes (APs or Base Stations) are capable of knowing their Geo-Location Coordinates X, Y, Z. This capability may come either by integrating GPS receiver or through any other alternate, state of the art or future positioning technologies in the APs.

This invention discloses a method to manage multicast business in access device, which comprises: creating one or more independent fundamental virtual LAN; creating module according to the said LAN and one or a plurality of pieces of information opposite to the said LAN; creating control list and control rule for every user port by visiting control module; receiving IGMP protocol message, the control module traverses user's control list according to control rule and returns result; if visiting the control by group, it sends the said message and information to treatment module for corresponding treatment; the set module adds or deletes the user's port according to multicast transposition table item. The invention overcomes the shortcoming in existing technique, such as security hidden trouble and hard to control switch delay and business quality.

Through technique for interpreting multicast groups, by using regional multicast agent router as loot node, and by using regional multicast routers as branch nodes, multicast tree is built in domain in regional network. Thus, regional multicast agent manages multicast application in whole regional domain as well as switching mobile nodes in domain is shielded outside domain. Based on mobile IPv6 fast switch over protocol, through expanding use of option of multicast groups, the method realizes fast multicast switching mobile nodes inside and outside domain. Switching between domains is based on remote join mode in IPv6 protocol so as to guarantee approximative optimality of path for forwarding multicast. Meanwhile advantages including fast multicast switching, reducing switching delay and switching packet loss are realized.

Provided is a method and apparatus for decreasing a handover latency time using a context exchange between a mobile terminal (MT) and a Media Independent Handover Server (MIHS). The method used by the MT for decreasing handover latency between a first network and a second network includes when a handover is performed from the first network to the second network, transmitting to the MIHS information required for first network communication as context; and when a handover is performed from the second network to the first network, receiving from the MIHS first network access information comprising the context through the currently used second network. Accordingly, the MT can reduce a Vertical Handover (VHO) latency time and simultaneously consume almost the same power as a single mode terminal.