541 results about "Soft handover" patented technology

A system and method for canceling interference present in a code-division multiple access (CDMA) channel signal received at a CDMA receiver that is caused by multipath components of a transmitted pilot channel signal or by soft handoff conditions is computationally efficient because it operates at symbol rates. The channel signal from which such multipath interference is canceled can be either a traffic (data) channel or the pilot channel itself. Interference signals are produced in groups corresponding to the fingers of the CDMA rake receiver. The interference signals corresponding to each finger are used to cancel interference in the other fingers.

The soft handoff in an OFDMA system. If the pilot signal strength for a base station exceeds the defined threshold, the base station is added to an active set list. Subcarriers in a plurality of orthogonal frequency division multiplexing (OFDM) symbols are divided and allocated into subchannels. The OFDM symbols are divided and multiplexed. A soft handoff zone with a first dimension of the subchannels and a second dimension of the divided and multiplexed OFDM symbols is defined. The soft handoff zone have subcarriers with a subchannel definition, for example, an identical permutation.

A mobile station according to the present invention that is capable of connecting simultaneously to a plurality of base stations comprises a reception radio portion and TPC bit detecting portions, for receiving and detecting TPC bits (transmission power control signals) from the plurality of base stations during soft handover; a combining portion, for combining the detected TPC bits to determine a combination signal; and a transmission power control deciding portion, for controlling the transmission power of the mobile station based on the combination signal determined by the combining portion. A method according to the present invention governs use of the mobile station hereof.

In a cellular system, each mobile station concurrently linked to plural link base stations in soft handover state and receiving packet from the packet-transmitting base station controls a transmission power of an up-link dedicated physical channel based on a first transmission power control information included in down-link dedicated physical channels of the link base stations. In other state, the mobile station controls the transmission power based on a second transmission power control information included in a down-link dedicated physical channel of the packet-transmitting base station. This accelerates the power increase up to a target power level causing that the measured signal-to-interference-ratio at the packet-transmitting base station reaches a target signal-to-interference-ratio, thereby improving receiving quality of control signal from the mobile station at the packet-transmitting base station.

A method of combining soft-handoff with a hybrid ARQ scheme to maximize throughput and gain in a communications system. After receiving a frame from the MS (110), the BTSs (104 and 106) will process the frame and communicate to the MS over a forward control channel whether the frame contained any errors. If all BTSs communicate that the frame contains errors, the MS will retransmit the same frame to all BTSs with a flush bit set to instruct the BTSs 104 and 106 to combine the retransmitted frame with the original frame. If only some BTSs communicate that the frame contains errors, the MS will transmit the next frame to all BTSs that successfully decoded the frame with the flush bit set to instruct the BTSs to erase the previous frame from memory and not to combine the previous frame with the current frame. The MS will retransmit the frame to the BTSs that did not successfully decode the frame with the flush bit set to instruct the BTSs to combine the previous frame with the retransmitted frame.

The invention relates to a mobile terminal communicating resource requests for dedicated uplink channel resources in a mobile communication system. Further, the invention also relates to a method for communicating resource requests for dedicated uplink channel resources in a mobile communication system. To allow the serving cell to detect “DOWN” commands from non-serving cells during soft handover the invention suggests a new definition of criteria for setting the “happy bit” in the control information associated to data transmitted on dedicated uplink channels. According to these criteria the mobile terminal may not indicate an unhappy condition while ramping up resource utilization. Only if resources equivalent to the maximum serving grant are utilized, the transmission buffer status requires to and the power status of the terminal allows for the happy bit is set to indicate a unhappy condition.

The invention relates to a method for scheduling mobile terminals within a mobile communication network and to a base station performing this method. Further, the invention relates to a method for acting upon the reception of scheduling grants in a mobile communication system and to a mobile terminal performing this method. To allow the serving cell to control resource utilization for uplink transmissions of UEs in soft-handover, without thereby decreasing the system throughput of UEs in the serving cell which are not in soft-handover, the invention proposes to use control information transmitted via a shared absolute grant channel to the UEs along with an absolute grant, wherein the control information indicate whether the absolute grant is valid for mobile terminals in soft-handover only.

The present invention relates to methods for controlling a plurality of base stations in a mobile communication system comprising a communication terminal, the plurality of base stations and a control unit connected to the plurality of base stations, wherein the communication terminal is in a soft handover. Further, the present invention relates to methods for signaling uplink channel quality characteristics, that are considered when controlling the plurality of base stations. Finally, the present invention relates to a base station, the control unit and the communication terminal which are specifically adapted to perform the control method and the signaling method respectively. To reduce the signaling load on the wired interface between a base station and a control unit the present invention selects a serving base station based on uplink channel quality characteristics and controls one or more of the base stations except the serving base station not to transmit data via the wired interface.

A base station inserts an overhead message into a broadcast stream transmitted to a mobile station. To support autonomous soft handoff by the mobile station, the base station inserting the overhead message sends a notification message to one or more of the base stations transmitting the same broadcast stream. The notification message indicates the time when the overhead message will be sent and the duration and/or length of the overhead message. The broadcast channel may be divided into multiple time slots to support mixed flows. Base stations supporting a mobile station in soft handoff can agree on the time slots allocated for a designated broadcast stream.

A method and apparatus selects serving scheduling Node B for efficiently controlling and scheduling uplink traffic transmission from user equipments (UEs) located in a soft handover region. The UE selects a serving scheduling cell among cells included in its active set and transmits information on the selected serving scheduling cell to a Node B through uplink signaling. A service scheduling cell and non-serving scheduling cells efficiently control uplink traffic from the UE through independent scheduling. The efficient use of uplink resources contributes to an increase in the entire system performance and system stability.

A telecommunications system has a source base station (BS_S) and a destination base station (BS_D), and a handover unit (100) having a dynamic offset threshold determination unit (102) which establishes a dynamic offset threshold for starting soft handover. When the dynamic offset threshold for soft handover is exceeded, a preliminary portion of a handover sequence is initiated at the destination base station. The preliminary portion of the handover sequence is initiated so that a time-critical handover sequence activity (such as L1 uplink synchronization) is well underway, if not completed, by the time the soft handover is actually needed. The dynamic offset threshold for starting handover is based on a probability that the mobile station will engage in the handover. The probability is a statistical probability that handover will actually occur based on handover history of other mobile stations previously and similarly traveling and of the same signal strength. Another portion of the soft handover sequence (e.g., a remaining portion of the soft handover sequence) is initiated when the signal strength from the destination base station as received at the specified mobile station has a predetermined relationship to a fixed offset threshold.

A system and method for implementing soft handoffs in a cellular communications system on a mobile platform. The system employs an antenna controller in communication with a beam forming network that generates two independently aimable lobes from a single beam. The single beam is radiated by a phased array antenna on the mobile platform. In an Air-to-Ground implementation involving an aircraft, a base transceiver station (BTS) look-up position table is utilized to provide the locations of a plurality of BTS sites within a given region that the aircraft is traversing. The antenna controller controls the beam forming network to generate dual lobes from the single beam that facilitate making a soft handoff from one BTS site to another. In a ground-based application, one lobe of the beam is used to maintain a communications link with one BTS site while a second lobe of the beam is continuously scanned about a predetermined arc to receive RF signals from other BTS sites and to determine when a new BTS site has become available that will provide a higher quality link than the link presently made with the one BTS site. A soft handoff is then implemented from the one BTS site to the new BTS site.

A system and method for transmitting packet data from a user equipment (UE) in a soft handover region to Node Bs in a code division multiple access (CDMA) mobile communication system. Scheduling is performed such that although the UE using an Enhanced Uplink Dedicated transport Channel (EUDCH) service in a soft handover region receives different scheduling commands from a plurality of active Node Bs, the EUDCH service can be performed in an optimal radio environment, contributing to improvement in data reception performance.

A communications network which is capable of effectively and efficiently handling mobility of wireless user terminals between access point nodes of a packet-switched network with minimal overhead and packet loss, and a method for using the same. The communications network employs a packet-switched core network and a plurality of access points coupled to the core network. Each access point is adapted to provide any user terminal with wireless communications access to the core network when that user terminal becomes affiliated with that access point. The system and method further employ ad-hoc routing techniques during handoff of a wireless user terminal between access point nodes of the core network to enable the network to maintain multiple paths via which data packets are provided to the user terminal during handoff to substantially eliminate packet loss during handoff.

Soft-handoff methods involve receiving an uplink signal from a user equipment at more than one basestation. The uplink signals are processed at each basestation before being backhauled to a common point for use to derive a single signal from the user equipment. One problem with previous types of soft-handoff methods is that relatively complex processing is required at each basestation in order to demodulate and decode the signals. It is also desired to further increase uplink capacity as compared with known types of soft-handoff methods. This is achieved by backhauling signals without carrying out any decoding of the uplink signal at the basestation. The backhauled signals are combined at a common point using maximal ratio combining before being fully demodulated and decoded. As a result capacity is increased and required user equipment transmit power is reduced.

A radio network controller 3 is so constructed as to divide a plurality of base stations 2 into a group of base stations included in an E-DCH active set and a group of base stations included in an active set for soft handovers (i.e., a prior art active set) according to a status of reception of data in each of the plurality of base stations 2.

A method and apparatus for scheduling uplink data transmission for a UE in a mobile communication system supporting an uplink packet data service are provided. A serving Node B and at least one non-serving Node B are included in an active set of a UE located in a soft handover region. The UE receives a dedicated scheduling grant from the serving Node B by dedicated scheduling and a common scheduling grant from the at least one non-serving Node B, controls an uplink data rate not to exceed a previous uplink data rate during a predetermined validity duration, if the common scheduling grant indicates a rate-down, and transmits uplink data at the controlled uplink data rate.

A method of uplink transmission scheduling for a network including at least one radio network controller (RNC), at least one user equipment (UE), and a plurality of Node Bs, with the steps of determining a parameter to be used in uplink transmission scheduling by considering uplink noise rise of the plurality of Node Bs, and performing the uplink transmission scheduling in accordance with the determined parameter. By determining the parameter upon considering the effects of the transmit power or transmit rate for a particular UE in soft handover with a scheduling Node B on the uplink noise rise of other neighboring Node Bs that are in soft handover but not scheduled with that particular UE, uplink transmission scheduling performance degradation can be prevented and more effective control of uplink noise rise at each Node B is possible.

A method and system of retransmitting uplink packet data from a user equipment (UE) in a handover region to Node Bs. The UE transmits packet data to the Node Bs on an enhanced uplink dedicated transport channel (EUDCH). The Node Bs transmit to the UE first response fields indicating whether the Node Bs have received good packet data or bad packet data, and second response fields that the Node Bs received from an RNC indicating whether a radio network controller (RNC) has received good packet data or bad packet data. The UE then detects the first and second response fields and retransmits the uplink packet data according to the values of the response fields in the UE.