Abstract: The communication terminal includes: a receiving unit and a transmission unit which serve as a communication unit for signal exchange; a beacon processing unit as a first detection unit that detects, for each channel, the number of the other communication terminals performing wireless communication by receiving a terminal number notification signal from a control device; a data processing unit as a second detection unit that counts, for each channel, the number of the other communication terminals found by receiving acknowledgement signals transmitted from the other communication terminals; a channel control unit that selects a frequency channel having a least difference between the number detected by the beacon processing unit and the number counted by the data processing unit, and causes the receiving unit and the transmission unit to perform the signal exchange via the selected frequency channel.

Abstract: The present invention relates to a wireless communication system, More specifically, the present invention relates to a method and an apparatus for direct communication between terminals. The method for performing communication between terminals using a first terminal in a wireless communication system comprises the steps of: transmitting request information for communication between terminals to a base station; receiving, from the base station, control information necessary for setting a link for communication between the terminals after transmitting the request information; setting a direct link between the terminals for data flow between the first and second terminals using the control information; and the first and second terminals performing communication for data transmission using the direct link between the terminals when the control information is not transmitted from the base station.

Abstract: A system and method for managing resources in a heterogeneous network, which includes a primary system and a secondary system, and in which a communication coverage range of the primary system is divided into a plurality of regions, the system including: a heterogeneous network resource management module configured to collect and manage resource usage status within a managed region; and a secondary system resource management module configured to acquire the resource usage status of each region from the heterogeneous network resource management module and to allocate resources to the secondary system by utilizing the acquired resource usage status of each region in accordance with a priority determined based on an efficiency of resource multiplexing between the primary system and the secondary system in each region. The system and method improve resource usage efficiency.

Abstract: The present description relates to a method of using a terminal to adaptively feed back channel information relating to multi-cell cooperative communication includes: measuring an average signal-to-noise ratio of a virtual multi-antenna channel between a terminal and at least one cell to transmit same to a base station; receiving, from a base station, a number of allowable feedback bits determined on the basis of the average signal-to-noise ratio and cooperative communication information; selecting a codebook from a plurality of predetermined codebooks on the basis of the number of allowable feedback bits and the cooperative communication information; and quantizing channel information on a virtual multi-antenna channel using the selected codebook, and transmitting feedback information including the quantized channel information to a base station. The codebook may be selected to transmit the feedback information using the entire number of allowable feedback bits.

Abstract: A user's downlink component carriers DL-CCs are divided into groups. An aperiodic CQI/PMI report is triggered by signaling (for example one bit). There is a pattern that maps the signaled trigger to a particular DL-CC within a group of DL-CCs that are configured for a user equipment UE, and that mapped particular DL-CC is determined to be the subject of the aperiodic report. In various embodiments the pattern is implicit and points to the DL-CC for which an aperiodic report has not been sent for more than a threshold time interval; or to the DL-CC for which resources have not been allocated for a periodic report; or to every DL-CC in the group that are activated for the user equipment. Examples are detailed for apparatus, method and computer program from the perspective of the network and from the perspective of the UE.

Abstract: The invention provides a method and system for adaptive point to multipoint wireless communication. The wireless physical layer and the wireless media-access-control (MAC) layer collectively include a set of parameters, which are adaptively modified by a base station controller for communication with a plurality of customer premises equipment. The base station controller adjusts communication with each customer premises equipment individually and adaptively in response to changes in characteristics of communication, including physical characteristics, amount of communication traffic, and nature of application for the communication traffic.

Abstract: Provided is a radio communication device which can prevent interference between SRS and PUCCH when the PUCCH transmission bandwidth fluctuates and suppress degradation of CQI estimation accuracy by the band where no SRS is transmitted. The device includes: an SRS code generation unit (201) which generates an SRS (Sounding Reference Signal) for measuring uplink line data channel quality; an SRS arrangement unit (202) which frequency-multiplexes the SRS on the SR transmission band and arranges it; and an SRS arrangement control unit (208) which controls SRS frequency multiplex so as to be uniform in frequency without modifying the bandwidth of one SRS multiplex unit in accordance with the fluctuation of the reference signal transmission bandwidth according to the SRS arrangement information transmitted from the base station and furthermore controls the transmission interval of the frequency-multiplexed SRS.

Abstract: A user equipment terminal for transmitting an uplink control channel to a base station according to a single carrier scheme includes a reception determining unit configured to determine reception of data, which are transmitted from the base station according to scheduling, and generate a reception determination result as first control information; and a control information multiplexing unit configured to assign the first control information to a first radio resource positioned at an end of a system band and assign second control information, which is transmitted with a radio resource dedicated to the user equipment terminal, to a predetermined position in a second radio resource adjacent to the first radio resource, to multiplex the first control information and the second control information into the uplink control channel. The present invention also relates to a base station and an uplink control channel configuration method.

Abstract: A node of a wireless network transmits information to a user equipment over an aggregated carrier that includes a primary carrier having a first set of primary carrier time/frequency resources and a secondary carrier having a second set of secondary carrier time/frequency resources. Synchronization signals and/or reference symbols are transmitted to the user equipment on the secondary carrier less often than on the primary carrier. An indication of when and/or how often the synchronization signals and/or reference symbols will be transmitted to the user equipment on the secondary carrier may also be transmitted to the user equipment over the primary carrier. By transmitting synchronization signals and/or reference symbols to the user equipment on the secondary carrier less often than on the primary carrier, resources of the secondary carrier may be conserved, energy efficiency of the secondary carrier may be increased, and/or interference with other cells may be reduced or prevented.

Abstract: A wireless transmit/receive unit (WTRU) receives a downlink transmission from an eNodeB including a plurality of spatial layers transmitted to a plurality of WTRUs paired for multi-user MIMO. The WTRU decodes the downlink transmission based on a corresponding WTRU-specific reference signal. WTRU-specific reference signals are multiplexed using a frequency and code division multiplexing. WTRU-specific reference signals for different sub-group of antenna ports are multiplexed onto different subcarriers in a frequency domain and the WTRU-specific reference signals of the same sub-group of antennas ports are multiplied by an orthogonal cover code. The resource elements used for the WTRU-specific reference signals on antenna ports in one sub-group may be muted on antenna ports in another sub-group. A WTRU may transmit the uplink demodulation reference signal without precoding.

Abstract: A method and system for minimizing the control overhead in a multi-carrier wireless communication network that utilizes a time-frequency resource is disclosed. In some embodiments, one or more zones in the time-frequency resource are designated for particular applications, such as a zone dedicated for voice-over-IP (VoIP) applications. By grouping applications of a similar type together within a zone, a reduction in the number of bits necessary for mapping a packet stream to a portion of the time-frequency resource can be achieved. In some embodiments, modular coding schemes associated with the packet streams may be selected that further reduce the amount of necessary control information. In some embodiments, packets may be classified for transmission in accordance with application type, QoS parameters, and other properties. In some embodiments, improved control messages may be constructed to facilitate the control process and minimize associated overhead.

Abstract: The present invention relates to a wireless communication system. More particularly, the present invention relates to a method for transmitting control information through a PUCCH in a wireless system and to a device therefore.

Abstract: Methods and systems for reusing macro cell resources in femto cell base stations or relay stations in a non-collaborative manner are disclosed. In addition, orthogonal resource allocation between a macro cell base station and femto cell base stations/relay stations may be dynamically adjusted by considering user-population variance. Moreover, an additional level of spatial reuse by femto cell base stations or relay stations can be provided by employing macro cell user location information.

Abstract: A method and a user equipment (“UE”), for High Speed Downlink Packet Access (“HSDPA”) de-activation, the method determining whether a number of serving HSDPA cell changes of the UE exceeds a threshold within a predetermined time period; and; sending a transition indication from the UE to a network node to deactivate HSDPA if the threshold is exceeded for within the predetermined time period. Also, a method and a network node, for High Speed Downlink Packet Access de-activation, the method determining whether a number of serving HSDPA cell changes of a user equipment communicating with the network node exceeds a threshold within a predetermined time period; and; deactivating HSDPA for the UE if the threshold is exceeded within the predetermined time period.

Abstract: Apparatus and method for seamless handoff of a service between different types of networks. The system may include a first user equipment, a second user equipment, a first network, a second network, and an application server. The first user equipment and the second user equipment may be configured to communicate with each other initially through a first data path of the service. The first network may be configured to determine whether the first user equipment should change its access network from the first network. The second network may be configured to allocate a new bearer and a second network IP address to the first user equipment when the first network requests the first user equipment to change its access network from the first network to the second network.

Abstract: In some implementations, a method includes identifying handover from a source eNodeB (eNB) to a target eNB or reestablishment with a subsequent eNB after losing connection with an initial eNB. Time-domain measurement resource restrictions for the UE are identified. The time-domain measurement resource restriction for the UE is released in connection with identifying the handover or the reestablishment.

Abstract: In order to re-establish a suspended RRC connection, the mobile device (101) in one example sends a connection re-establishment request message to the RAN (102) to have the suspended RRC connection re-established. The RAN node may need to attempt to retrieve the RRC connection data (either from memory or if from another network element if stored elsewhere/if the RRC connection was suspended by another RAN node) and verifies whether the RRC connection is valid. When verified, the mobile device (101) receives, in response to the message, a connection re-establishment command message from the RAN (102). In response to the message, the mobile device (101) re-establishes the RRC connection with the RAN (102), using the stored RRC connection information, and sends a connection re-establishment complete message to the RAN (102). The mobile device (101) and RAN (102) may then resume user plane data communication with each other.

Abstract: A method, apparatus and system for resource allocation in redirection of data traffic are provided. The method includes receiving a message including a subscription identification, position information associated with the subscription and an action proposal associated with the subscription (200a), selecting at least one local area network based at least in part on the position information (222), mapping the at least one local area network to a local area network server (230), ensuring a valid unique task identification for the subscription in the local area network server, and sending an off -loading indication message including the action proposal, the valid task identification and an identifier of the local area network server to the subscription (200d).

Abstract: Disclosed are a device for controlling uplink transmission power and a method for the same. In a terminal device for controlling uplink transmission power according to the present invention, a receiving antenna receives a first message containing a power correction value from a base station. A processor determines the transmission power value which will be used in transmitting a second message, based on the power correction value. A sending antenna transmits the second message to the base station, using the determined transmission power value, and, at this time, the power correction value is a value for correcting the transmission-power value is a value for correcting the transmission-power value which was used during initial ranging by the terminal or handover ranging of the terminal.

Abstract: Embodiments herein relate to a method in a user equipment (10) for acquiring system information relating to a cell (11,14) in a radio communications network. The cell (11,14) is served by a network node (12,12?,15) and the user equipment (10) is capable of receiving signals on more than one downlink carrier simultaneously. The user equipment (10) creates autonomous gaps on a downlink carrier, which downlink carrier to use for creating autonomous gaps on is based on a received indication from the network node (12,12?,15) and/or a pre-determined rule. The indication or pre-determined rule specifies the downlink carrier. The user equipment (10) then acquires the system information of the cell (11,14) on the downlink carrier using the created autonomous gaps.

Abstract: A mobile wireless system includes a first gateway (L-PGW), a second gateway (PGW), a first access point (HeNB) capable of establishing a communication path simultaneously with the first and second gateways, and a second access point (eNB) capable of establishing a communication path only with the PGW. When a mobile terminal connected to the HeNB and communicating with a communication destination node using a first path through the L-PGW switches a connection destination to the eNB, the HeNB establishes a second path through the HeNB and the PGW, while maintaining the first path. The HeNB transmits data, which has been transmitted to the HeNB along the first path, to the eNB along the second path, until the UE is connected to the eNB, and a third path to the communication destination node through the PGW is established. Accordingly, an interruption time of data reception involved in handover is shortened.

Abstract: The present invention relates to a method for updating secondary carrier information for preemptively allocating secondary carriers during handover and an apparatus for carrying out the method. A method in which a terminal performs handover in a broadband access system that supports multiple carriers according to one embodiment of the present invention comprises: a step in which a target base station receives, from a serving base station, a first message including carrier allocation information on at least one secondary carrier preemptively allocated to the terminal; a step of performing network reentry with the target base station; and judging whether the multi-carrier configuration of the serving base station and the multi-carrier configuration of the target base station are the same, and, if the configurations are different from each other, transmitting, to the target base station, a second message for requesting multi-carrier capability negotiation.

Abstract: Apparatuses and methods for maintaining an optimal beam direction in a wireless communication system are provided. The method for operating a receiving node in a wireless communication system includes, determining a first transmission beam is determined as a preferred transmission beam using a plurality of reference signals transmitted by a transmitting node, generating preferred transmission beam information, transmitting the preferred transmission beam information to the transmitting node, receiving transmissions from the transmitting node via the first transmission beam, and determining whether a change of a transmission beam is necessary. When the change of the transmission beam is determined to be necessary, generating a beam change request and transmitting the beam change request to the transmitting node.

Abstract: A mobile device that operates in a wireless communication network is disclosed. The mobile device includes a transceiver that uses a first wireless communication technology, which can be Long Term Evolution (LTE) technology. The mobile device also includes a modem that coupled to the transceiver through a standard interface and uses a second wireless communication technology, which can be CDMA. The modem processes the received signal from the transceiver and processes a transmit signal for the transceiver. A first receiver first processing circuit has a matching filter to compensate for and resampling the received signal from the receiver so that that the received signal from the transceiver is compatible with the modem. A transmitter processing has a filter for resampling and adjusting a processed transmit signal for the transmitter.

Abstract: A receiver resource administrator coordinates uplink transmissions from a mobile terminal in order to reduce the RAKE resources required to support the mobile terminal and to provide greater predictability in the uplink transmissions. The reduction of RAKE resources and the increased predictability of the uplink transmissions enable multiplexing of multiple mobile terminals using the same RAKE resources.

Abstract: Downlink control information (DCI) extensions to support 3GPP Rel-10 functionalities comprise minimal extensions of DCI format 2B. In some embodiments, only two extra bits (20) are introduced to signal rank up to eight, by reusing the Scrambling Identity bit (16) while at the same time supporting different MU-MIMO dimensioning for the important cases of rank-1 and rank-2. This new DCI format can potentially support not only single cell downlink transmission but also some other Rel-10 functionalities, e.g. CoMP or relaying/HetNet.

Abstract: An apparatus and method for feedback solutions that function in conjunction with CoMP transmissions. The feedback solutions are applicable to joint transmission (JT) as well as coordinated scheduling (CS) and coordinated beamforming (CB). Embodiments of the present disclosure are described herein in the context of a wireless network in compliance with LTE standards.

Abstract: A method and a device for managing resources in a wireless communication network are provided. In one embodiment, a Medium Access Control (MAC) superframe format for a wireless communication network includes a beacon frame including beacon information for synchronizing devices in the wireless communication network and for defining structure of the MAC superframe, where the beacon information includes superframe structure information and synchronization information. The MAC superframe format also includes at least one multi-node connection frame substantially following the beacon frame and including device specific information and network specific information for allocating resources to one or more of the devices and/or providing network configuration parameters to the devices.

Abstract: Briefly, in accordance with one embodiment of the invention, an access point may provide multiple access to a single medium by providing time division multiple access to the medium. During a first phase to communicate with devices of a first type, the access point may transmit a beacon to indicate to devices of a second type not to communicate during the first phase. During a second phase to communicate with devices of the second type, the access point may transmit a beacon to indicate to devices of the first type not to communicate during the second phase. In one particular embodiment, the access point may transmit a medium reservation packet to indicate reservation of the medium for affected devices.

Abstract: A wireless network interface of an apparatus is configured to operate in an infrastructure client mode if at least one predetermined wireless access point is detected via the wireless network interface. Otherwise, the wireless network interface is configured to operate in an infrastructure access point mode. A network service of the apparatus is provided via the configured wireless network interface.

Abstract: An apparatus, a method and a computer program product for seamless transition between WiFi networks (including in particular WiFi Internet networks) includes within a mobile communication apparatus a mobility layer that is tunneled to a mobility server within a network infrastructure. The mobile communications apparatus includes a wireless network capability, a global positioning system capability, an internal network protocol address and a routing capability. The apparatus, the method and the computer program product also provide that the mobility layer is programmed to sequentially and automatically tunnel to the mobility server at an available geographically defined WiFi network access location predicated upon a global positioning system determined position of the mobile communication apparatus. Embodiments also provide seamless transitions between WiFi networks and cellular networks.

Abstract: First and second wireless transmission protocol uplink channels are available for use by a wireless device in transmitting data to a network. In various examples, the device selects between the first and second wireless transmission protocol uplink channels according to various different criteria. Examples include selecting between the first and second wireless transmission protocol uplink channels according to the type of data to be transmitted and according to the identity of the device, and various combinations of these.

Abstract: A plurality of different radio modules is provided for a wireless network access device to provide a modular, configurable and performance scalable wireless network. The radio modules include a radio board having a size and shape with a common form factor for the wireless network access device. A radio board connector mates with any one of multiple connectors on the wireless network access device. The radio board connector includes an electrical interface that conforms to a predefined interface on the wireless network access device. The radio board includes a radio board processor that communicates with a wireless network access device controller as a single radio instance for the radio module. The radio board includes a radio chain to communicate radio signals with corresponding antennas. The radio chain, antennas, and radio board processor operate in accordance with one of a plurality of different radio module types.

Abstract: A wireless communication terminal may include a storage unit that stores an identifier of the proxy terminal in the wireless network, a wireless communication unit that performs wireless communication with another wireless communication terminal, an event receiving unit that receives a predetermined event, a processing unit that starts a participation setup process of causing the non-participating terminal that has wirelessly transmitted a participation setup process request for the wireless network to participate in the wireless network when a participation request for the wireless network and the participation setup process request for the wireless network are received after the event is received by the event receiving unit, and a control unit that causes the wireless communication unit to wirelessly transmit the event request of requesting the proxy terminal corresponding to the identifier stored in the storage unit to receive the event when a new participation request is received during a time.

Abstract: In a communication control apparatus wirelessly communicable with a plurality of wireless communication units respectively installed in a plurality of vehicles, a first determiner determines at least one wireless communication unit in a number of wireless communication units in the plurality of wireless communication units as a first enabling unit that enables wireless communications with the communication control apparatus if information transmitted from the at least one wireless communication unit is second type information including a piece of vehicle information that includes at least the identifier of the corresponding vehicle. A second determiner determines a wireless communication unit in the remaining one or more wireless communication units as a second enabling unit, which enables wireless communications with the communication control apparatus, if information transmitted from the wireless communication unit is not included in the information transmitted from the first enabling unit.

Abstract: A wireless communication device constitutes a wireless network which includes plural wireless communication devices and which is for performing communications between the plural wireless communication devices. The wireless communication device has a base station index based on which the wireless communication device functions as a base station of the wireless network. The base station index expresses a degree to which the wireless communication device functions as the base station. The wireless communication device includes a base station transfer unit configured to perform a transfer process of transferring a function of the base station of the wireless network from a first wireless communication device functioning as the base station of the wireless network already formed to a second wireless communication device that is newly joining the wireless network, when the base station index of the second wireless communication device is higher than that of the first wireless communication device.

Abstract: In certain embodiments, a slave clock node in a wireless packet network achieves time synchronization with a master clock node by implementing a packet-layer synchronization procedure, such as the IEEE1588 precision timing protocol (PTP), to set the slave's local time based on the master's time. The slave's local time is then maintained by implementing a physical-layer syntonization procedure, such as synchronous Ethernet, without relying on the packet-layer synchronization procedure. The packet-layer synchronization procedure may be selectively employed to adjust the slave's local time (if needed) after significant periods of time (e.g., substantially greater than one second). Both the packet-layer synchronization procedure and the physical-layer syntonization procedure are traceable to a common reference timescale (e.g., UTC). Depending on the implementation, the packet-layer synchronization procedure can be, but does not have to be, terminated when not being employed to adjust the slave's local time.

Abstract: A hybrid Unified Communications (UC) telephony deployment includes users of a tenant that are hosted between a UC cloud deployment and a UC on-premise deployment that offers PSTN connectivity for the users. An identity of a tenant and its' users are maintained consistently between the on-premise and cloud based UC deployment (e.g. telephone numbers, dialing preferences, voice mail . . . ). Each user of the tenant can register with the UC service from one or more locations (e.g. on-premise, off-premise . . . ) whether or not they are hosted by the on-premise deployment or the cloud based UC deployment. Functionality of the UC deployment may also be maintained at one or more locations within the hybrid UC deployment. For example, some services (e.g. voicemail, or other services) can be hosted in the cloud while the remaining services are hosted on-premise. Different Telco providers may be chosen by the tenant to provide PSTN services for one or more users of the tenant.

Abstract: User equipment and method for executing an application, which uses application data, and which is executed in an Application Server in a VoIP based telecommunications network. The method comprises providing a user equipment including a database having the data stored therein, wherein the user equipment further includes an Application Server. The method further comprises invoking the SIP-AS included in the user equipment by a network node of the telecommunications network, providing, within the user equipment, the data to the Application Server included in the user equipment, executing the application, using the data, by the Application Server included in the user equipment, and communicating a result of executing the application from the Application Server included in the user equipment to the network.

Abstract: A system and method for coupling a communications device to a primary communications network having a first communications format and to a secondary communications network having a second communications format. The system and method can comprise a first port configured for connecting to the communications device, a second port configured for connecting to the primary communications network and facilitating the communication of the data between the primary communications network and the communications device through the first port.

Abstract: Generally, this disclosure describes an energy-efficient Ethernet communications approach. In at least one embodiment described herein, an Ethernet controller may be configured to operate in an active power state to transmit or receive data packets at a maximum available link speed. The maximum available link speed may be determined by a negotiation between the Ethernet controller and a link partner coupled to the Ethernet controller. Once the data packets are transmitted or received, the Ethernet controller may be configured to operate in an idle power state to reduce energy consumption.

Abstract: A method and apparatus for facilitating communication between client computers is provided. The method provides for the use of ping probing by a server to determine the types of NAT devices and/or firewalls protecting the client computers. Once these are determined, the server can predict the response to communications from the client computers and instruct the client computers to contact each other. Once a session or tunnel is established it can be maintained through the use of a flag, even if contact with the server is lost.

Abstract: An address translation apparatus translates an address included in a packet to relay the packet. The packet is transmitted between an external network and an internal network. The address translation apparatus includes a processor. The processor receives a packet transmitted from the internal network. The processor determines, based on a given condition, whether to perform address translation on the received packet. The processor translates, upon determining to perform address translation, a source address of the received packet from an internal address into an external address to obtain a translated packet and relays the translated packet. The processor relays, upon determining not to perform address translation, the received packet to an alternate translation apparatus without performing address translation.

Abstract: A packet classification system, methods, and corresponding apparatus are provided for enabling packet classification. A processor of a security appliance coupled to a network uses a classifier table having a plurality of rules, the plurality of rules having at least one field, to build a decision tree structure including a plurality of nodes, the plurality of nodes including a subset of the plurality of rules. The methods may produce wider, shallower trees that result in shorter search times and reduced memory requirements for storing the trees.

Abstract: Peer-to-Peer traffic switching that allows gateway traversal is accomplished using a traffic switch that receives packets from each of the nodes, accommodates synchronization flags, as well as sequence numbering and packet acknowledgements. Avoiding a complex and cumbersome registration process allows two peer nodes to communicate with each other while traversing network address translation gateways, and allows for a process that provides a transparent experience to both nodes so that they do not necessarily perceive that they are communicating through a gateway.

Abstract: In accordance with some embodiments of the present disclosure, a method may include determining a range of frequencies allocated to resource blocks to be transmitted during a subsequent sub-frame slot or sounding reference symbol sub-slot. The method may also include determining an approximate center frequency of the range of frequencies. The method may additionally include modulating resource blocks of the sub-frame or sounding reference symbol sub-slot at the approximate center frequency. The method may further include transmitting the modulated resource blocks at the approximate center frequency.

Abstract: In a data transmission system, a first node (100) receives at least two sets of input data signals (d-in1, d-in2) including at least two signals being based on different synchronization sources. The first node (100) extracts a respective clock signal (CLKex1, CLKex2) representing the embedded clock signals from said sources, samples and then formats these signals (CLKsp1, CLKsp2) for transmission according to a TDM structure. The TDM formatted signals are transmitted as at least one bit stream (bs1, bs2) over a transmission medium (L1, L2) to at least one second node (201, 202), where the bit stream (bs1, bs2) is demultiplexed into at least two sets of output data signals (d-out1, d-out2, d-out3, d-out4) respective demultiplexed clock signals (CLKdm1, CLKdm2) representing the sampled clock signals.

Abstract: A method of controlling a wavelength-tunable laser selecting an oscillation wavelength with a combination of a plurality of wavelength selection portions of which wavelength peak is different from each other, comprising: a first step of confirming a control direction of the wavelength selection portion in a case where a setting value is changed from a first setting value for achieving the first wavelength to a second setting value for achieving the second wavelength; a second step of setting a setting value that is shifted from the second setting value in a direction that is opposite of a pre-determined changing direction on the wavelength selection portion as a prepared setting value, when the control direction confirmed in the first step is opposite to the pre-determined changing direction; and a third step of changing the prepared setting value set in the second step to the second setting value.

Abstract: A tunable laser, including: a laser resonant cavity including first and second total reflection mirrors within a laser spectral range; first and second wavelength-adjustable laser gain mediums disposed in the laser resonant cavity; first and second intra-cavity collimating lenses; an acousto-optic tunable filter; a device exciting sound waves in an acousto-optic crystal and including a sound wave energy transducer bonded on a selected surface of the crystal; a radio frequency signal source; an optical phase modulator; an optical etalon disposed between the optical phase modulator and the laser gain medium; a wavelength locker disposed at one of zero-order diffraction optical paths of intra-cavity light; a pigtailed collimator coupling laser output light to an optical fiber; first and second pumping devices exciting the first and second laser gain mediums respectively; an optical phase modulator driver for driving the phase modulator; and a signal control processing circuit.

Abstract: A wavelength conversion device may include a wavelength conversion element that converts an entering first laser beam into a second laser beam by wavelength conversion, and a cooling mechanism that cools the wavelength conversion element from at least one surface of the wavelength conversion element.