Abstract: During an exchange of communications between a client and a server, the state of communications is monitored to determine if the client has lost communication with the server prior to completion of the exchange. If a loss of communication is detected, a recovery message is transmitted to the client, wherein the recovery message is received by the client after client communications with the network are re-established. The recovery message causes the client to send a response message to a predetermined network location. Receipt of the response message is an indication that the client has re-established communication. In such a case, the exchange is returned to a state that existed prior to the loss of communication.

Abstract: At least one protection line is shared among SONET rings. Identification and availability information of the shared protection line is distributed among the switches of the SONET rings using K-byte data in the SONET overhead.

Abstract: A method for controlling switching in a bidirectional line-switched ring network configured by a plurality of optical fibers and a plurality of nodes, (i) having a first node receive as input an LP-S (or having the first node detect an SF-P) and having a second node adjacent to the first node across a span receive the LP-S (or receive the SF-P), and (ii) having the second node send an SF-R switch request to another node when the second node further detects an SF-R on said span under the above state (i), whereby a method for controlling switching in a bidirectional line-switched ring under conditions where ring switch and LP-S cannot co-exist, but ring switch and SF-P can, is realized, as a whole, in the ring network.

Abstract: A stackable switch supporting redundant link and backup management. The stackable switch includes a stacking module, a processor and a management module. Several stackable switches can be stacked together in the form of a closed-loop link topology via the stacking module. The stacking module has an uplink port, a downlink port, and preferably a manual control device. The processor instructs the stacking module to enable or disable a downlink control bus within the downlink port when receiving a reconnect/disconnect command. If a link status, generated from the processor, indicates that these switches are stacked into the closed-loop link topology, the management module issues the disconnect command. Otherwise, the management module issues the reconnect command to recover a redundant link. Provided that the manual control device is activated, the management module in the same switch has the highest priority to become a master agent for the switch stack.

Abstract: Disclosed is a method for checking for errors and problems in routing protocol modules through hello packet transmission in a distributed router that is mounted with a network processor, a system processor, a routing protocol module, and a switch module including at least two input/output processors which can be operated together with independent routers, a system processor, and a designate routing protocol module. The method including the steps of: checking hello packet transmission cycle; if the hello packet transmission cycle has expired, transmitting a hello packet to the adjacent routing protocol module; receiving a hello response packet from the adjacent routing module; if the adjacent routing protocol module does not send the hello response packet, concluding that the adjacent routing is malfunctioning; and transmitting information on the malfunctioning adjacent routing protocol module to the designate routing protocol module.

Abstract: A method and apparatus for concatenating and piggybacking data packets in a bi-directional communication device include, in response to a first transmission queue of the bi-directional communication device containing less than a threshold number of data packets, transferring a data packet from a second transmission queue in the bi-directional communication device to the first transmission queue, the transferred data packet comprising at least two concatenated data packets. The method and apparatus further include identifying the transferred data packet as a ready-to-send data packet in the first transmission queue after the transfer, and indicating the presence of a subsequent ready-to-send data packet in a primary ready-to-send data packet, the primary ready-to-send data packet and the subsequent ready-to-send data packet existing in a sequence of ready-to-send data packets in the first transmission queue.

Abstract: A data compression system that dynamically adapts the degree of compression used in response to the priority of the data to be compressed is provided by virtue of one embodiment of the present invention. In one embodiment, only low priority data is compressed while high priority data is passed through to the network in uncompressed form. Also, the compression ratio can be varied depending on the priority of the data to allocate a larger portion of available bandwidth to higher priority traffic while imposing greater compression related delay on lower priority traffic.

Abstract: A network system, enabling the quality of the data to be ensured and efficient use can be made of the network, including at least one network relay apparatus provided with a discriminating unit for discriminating the type of data transmitted, a selecting unit for selecting the optimal route for each string of data in accordance with the discriminated type and destination, and a holding unit for holding the optimal routing information for each type of data and destination and sending received data toward the optimal route.

Abstract: A system and method for transmitting and bundling network packets is provided. The incoming network packet size is determined and if the remote buffer space is sufficient to hold the network packet it is transmitted to the destination port. If the remote buffer space is not enough to hold the network packet it is discarded. The system includes an arbitration module that receives remote buffer space information and transmits the network packet if the remote buffer space has enough space to hold the packet. The arbitration module also determines if a second network packet is from a same source port having a same source virtual lane, and has the same destination virtual lane (bundling conditions). If the second network packet meets the bundling conditions, then it is transmitted after the first network packet, even if other packets were received before the second network packet.

Abstract: An apparatus for transmitting to a network comprises a queue, packetization logic, interface logic, and queue logic. The packetization logic is configured to packetize data into a plurality of data packets and to store, to the queue, entries pointing to the data packets. The interface logic is configured to read the entries from the queue. The interface logic, for each of the read entries, is configured to retrieve one of the packets pointed to by the read entry and to transmit the retrieved packet to a network socket. The queue logic is configured to limit, based on a number of retransmission requests detected by the queue logic, a number of entries that the packetization logic may store to the queue during a particular time period thereby controlling a transmission rate of the apparatus.

Abstract: Techniques for monitoring nodes in a network are provided. A circular list of bins is maintained and each bin stores identifiers to zero or more nodes to be monitored. At periodic intervals, the nodes specified by a bin are processed such as by sending a polling message to the node. Additionally, responses from polling messages can also be processed at periodic intervals.

Abstract: In a method of label selection for end-to-end transport of label switched traffic through a communications network between a source node and a destination node, a request message is launched toward the destination node from the source node. The request message includes a label list having one or more label identifiers indicative of respective corresponding labels available for use by the source node. The label list is revised, at a cross-connect service each successive hop between the source node and the destination node, based on labels available for use by each respective hop, to produce a reduced label list. The reduced label list includes label identifiers indicative of respective corresponding labels available for end-to-end transport of label switched traffic between the source node and the destination node.

Abstract: In a communications network, which may be a federated network such as the Internet, a tariff is distributed via the network to customer terminals. At each terminal a charge for use of the network is calculated by using the tariff. Different tariffs may be communicated for different services and a respective tariff may be varied depending upon the operational condition of the service. Different tariffs may be calculated for different customers and the tariffs may be varied in dependence upon the loading of network resources and different tariffs may have different volatilities. Part of the traffic from a user to the network may be sampled and the status of the user may be amended when a discrepancy is detected between the sampled parameters and the contracted parameters in the users contract.

Abstract: A method for communicating packets in a network environment is provided that includes receiving a packet at a network element and identifying a sequence number included in the packet that correlates to awareness information associated with one or more adjacent network elements. A table included in the network element may be updated in order to account for the awareness information included within the packet that has not been accounted for by the network element. In cases where the awareness information included in the packet has already been accounted for, the packet may be ignored.

Abstract: Systems and methods are provided wherein call-blocking probability of a telecommunications system is calculated based on consideration of over flow paths and alternate routes. Once the routes and overflow pathways are identified, the total number of call attempts and calls failed, due to congestion, is determined from statistical route data. Dividing the number of failed calls due to congestion by the number of attempted calls results in the blocking proportion for each route that is used by the methods disclosed herein to calculate the probability of blocking for that route.

Abstract: A general packet radio service (GPRS) system includes radio network controllers (RNC), support nodes (SGSN) and a gateway node (GGSN) connected in a hierarchical order for packet transmission between mobile stations in the system. Each of each RNC, each SGSN and GGSN has a communication path controller to return the request of coupling toward subordinate node or controller if the subordinate mobile stations include the destination mobile station. Accounting for the packet service is based on the return of the packets.

Abstract: A method enables the topology of an acyclic fully propagated network to be discovered. A list of switches that comprise the network is formed and the MAC address cache for each one of the switches is determined. For each pair of switches, from the MAC address caches the remaining switches that see the pair of switches are located. For each pair of switches the remaining switches are determined that see one of the pair of switches on a first port and the second one of the pair of switches on a second port. A list of insiders is formed for every pair of switches. It is determined whether the insider for each pair of switches is a graph edge and adjacent ones of the graph edges are determined. A symmetric adjacency matrix is formed from the graph edges to represent the topology of the data link network.

Abstract: A mobile terminal capable of carrying out communications while moving among a plurality of interconnected subnets is provided with a TCP/IP driver configured to carry out processing of communication packets; and a control related driver configured to carry out processing of control related packets that require urgency in communications, at higher priority than the communication packets, without using the TCP/IP driver. The control related packets may include Mobile IP packets and DHCP packets.

Abstract: The invention relates to a method for reducing the latency in a GPRS network, via which information is transmitted between a data requesting unit, i.e. a client (1), and a data-providing unit, i.e. a server (9), in the form of data packets. In order to transmit the data packets from the client (1) to the server (9), at least one first communication channel (UL-TBF) is opened and then closed. At least a second communication channel (DL-TBF) is then opened and closed for transmitting information from the server (9) to the client (1). A not insignificant latency is thus produced between the request for information and the receipt of information, which can be reduced, according to the invention, by opening the second communication channel (DL TBF) before closing the first communication channel (UL-TBF). A radio channel is thus provided for preventive purposes, for the feedback of the requested data.

Abstract: A mobile communication system includes a medium access control (MAC) layer that supports an idle state in which no downlink and uplink dedicated control channel and dedicated traffic channel exists and also supports an active state in which the downlink and uplink dedicated control channel and dedicated traffic channel exist. The MAC layer controls transitioning to a contention state and then transitioning from the contention state to the active state through contention-based access, if there is transmission data in the idle state; transitioning to a fast access state or a slow access state according to priority of the data if there is no transmission data in the active state for a preset time; transitioning to the active state through contention-free-based access if there is transmission data in the fast access state; and transitioning to the active state through contention-free-based access if there is transmission data in the slow access state.

Abstract: An apparatus and method for securing media access control (MAC) addresses in a wireless local area network (LAN) environment are provided. In the method of securing MAC addresses, a cryptographically generated address (CGA) is generated using a predetermined cipher algorithm, a ciphered MAC address is extracted from the CGA, and communication is performed using the ciphered MAC address. Accordingly, it is possible to strengthen the security of MAC addresses.

Abstract: A method for wirelessly connecting a workstation, such as a computer, to a local area network includes selecting a LAN with which the workstation is to communicate. A wireless LAN access device that communicates with a processor of the workstation receives signals broadcast by wireless LAN ports. The signals are evaluated to identify those signals which originated from wireless LAN ports of the selected LAN. A connection protocol is then selected, based on a signal from one of the wireless LAN ports of the selected LAN, to establish a connection and, thus, communication between the wireless LAN access device of the workstation and that wireless LAN port. If such communication is established, one or more security identifiers may be provided from the workstation to the selected LAN. A connection program, which is embodied as instructions on one or more storage media, may be used to effect the method.

Abstract: In a radio base station (100) that communicates with a mobile station according to the PHS standards, a reception timing detection unit (55) measures the time when a UW signal of a signal separated by a signal regulating unit (51) for each mobile station is received with reference to the starting point of the time slot of a TDMA/TDD frame, as a reception timing signal. A control unit (80), when assigning a communication channel according to spatial multiplexing to a mobile station, allocates a communication channel in which a reception timing difference between the new mobile station and all mobile stations communicating is equal to or exceeds a threshold value.

Abstract: A system and method are provided for wireless communication. In one example, a wireless communication system that enhances total system throughput is provided. The system performs parallel data transmission from a plurality of access points to a plurality of user terminals. On terminals with power control function, their transmit power can be set to minimize interference. The wireless communication system comprises a management server which performs centralized management of time of access-point-to-terminal packet transmission, access points, and user terminals that perform data transmission, according to transmission time control information from the management server. Transmit queues for measuring downlink traffic and receive queues for measuring uplink traffic are provided on the access points or the management server. The system determines uplink and downlink periods from the transmit and receive queue lengths.

Abstract: A method for assigning a single frequency sub-channel to a plurality of MSs (Mobile Stations) in an OFDM (Orthogonal Frequency Division Multiplexing) system utilizing SDM (Spatial Division Multiplexing) with multiple transmit/receive antennas. In the method, a BS (Base Station) can effectively assign a pilot channel to estimate a downlink channel. The BS divides the single frequency sub-channel into a plurality of spatial channels, and sequentially assigns the plurality of spatial channels to the MSs having the maximum communication capacity, thereby transmitting signals of the MSs through the single frequency sub-channel.

Abstract: A method of timing in a multi-cell system requiring synchronization of frames in transmission is provided. Transceivers of a wired data interface between a central controller and multiple base stations are synchronized to a frame timing clock up to a difference in propagation delays between the central controller and multiple base stations. The propagation delays are considered as constants, are measured, and are stored in each base station. A unique word is regularly inserted in the data transmitted by the central controller, at a fixed interval. When this unique word is detected by the base station within a fixed period of the frame timing clock, a frame signal delay is initiated at the next rising edge of each frame timing clock. This frame signal delay is equal to the period of the frame timing clock minus the propagation delay. At the end of the frame delay, the frame data is transmitted, and all frames are simultaneously transmitted from different base stations.

Abstract: Each wireless LAN base station comprises priority queue table, a header analyzing circuit determining a priority of data transmitted from a wireless terminal based on a header of the data and the priority queue table, priority queues for storing data, a control circuit for enqueueing the data transmitted from the wireless terminal to the priority queue and updating the priority queue table with priority information transmitted from the host apparatus, and a transmission control circuit for transmitting the data which have been stored in the priority queues and the priority queue table. A host apparatus comprises a queue information table containing the priority queue tables of the base stations, and a control circuit for determining a priority of data between wireless terminals on the basis of the queue information table and transmitting the priority information to the plurality of wireless LAN base stations via which the data route.

Abstract: A method for mobile communication includes arranging a plurality of access points in a wireless local area network (WLAN) to communicate on a common frequency channel with a mobile station, and linking the access points together by cables in a wired local area network (LAN), so as to convey frames of data to and from the mobile station via the LAN. When one or more of the access points receive an uplink signal transmitted over the WLAN by the mobile station on the common frequency channel, the access points send messages over the LAN by interleaving the messages in one or more of the frames of the data, and arbitrate among themselves based on the messages so as to select one of the access points to respond to the uplink signal.

Abstract: In infrastructure-based networks devices often move from one attachment point in the network or a sub-network thereof to another attachment point. Communications sessions may be established between Mobile Hosts attached to such nodes. Communications sessions between nodes established using Session Initiation Protocol (SIP), Mobile Internet Protocol with Location Registers (MIP-LR) or Mobile Internet Protocol version 6 (MIPv6) may fail if there is simultaneous mobility of two Mobile Hosts in an ongoing communication session. Stationary binding update proxies and stationary location proxies are introduced into such communications networks in order to provide a solution to the problem of simultaneous mobility of Mobile Hosts. Specific implementation for SIP, MIP-LR and MIPv6 are provided. IN SIP networks, the SIP server for the mobile hosts acts as the stationary binding update proxy and the stationary location proxy.

Abstract: Communication signal equalization methods and systems are disclosed. A CDMA signal having a data portion and a known portion including a known or repeated data sequence and received over a multipath communication channel represents a linear convolution between the multipath channel and a transmitted CDMA signal. A channel estimate of the communication channel is determined from the known portion, and the CDMA signal is translated into a new CDMA signal which is a cyclic convolution with the channel estimate. A frequency domain representation of the new CDMA signal is adjusted using the channel estimate to produce a frequency domain representation of an equalized signal.

Abstract: The invention discloses a method for providing guaranteed Quality of Services (QoS) in an IP network. In the invention, separated with the function of route selection for IP packets in IP bearer network, the same function for services with guaranteed QoS requirements is accomplished by bearer network resource managers in bearer control layer. After completing the route selection according to network resource occupation condition, the bearer network resource managers control the edge routers so that the traffic streams can be forwarded according to the path designated by the resource manager in the bearer network with multi-level label stack technology. The invention also discloses a system for providing guaranteed QoS in an IP network. The method and system according to the invention have good expansibility and little impact to the prior network.

Abstract: The present invention is directed to a telecommunications system 100 for routing a contact to a selected address, comprising (a) an input for receiving a contact message comprising a source address and a destination address of a subscriber communication device 116 associated with a subscriber and (b) mobility agent 160 for determining whether or not the source address in the contact message corresponds to a proxy server 128 and, when the source address corresponds to a proxy server 128, causing the contact not to be routed to a selected address and, when the source address does not correspond to a proxy server 128, causing the contact to be routed to the selected address.

Abstract: This invention discloses an integrated exchange system for the terminal edge network connections. The integrated exchange system, comprising an IP packet based switch system and a telephony executive engine, is capable to execute IP and non-IP communication protocols, which puts LAN, WAN, PSTN and POTS together to offer the data network functionalities of Ethernet switch, route, gateway, firewall, VPN tunnel, and voice communication functionalities of IP-PBX, voice mail box, computer telephony and call center.

Abstract: Dominated nodes A, B and C equip only with lower layers 1a, 2a and 3a, and upper layers for the lower layers are not equipped. Each of the lower layers 1a, 2a and 3a comprises a preset device, and managing information for managing a communication function of the lower layer is read from the preset device and set to a function device of the lower layer. The dominated nodes A, B and C can execute isochronous transmission without a dominating node equipped with an upper layer for managing the lower layers. The dominating node is not always necessary on an IEEE1394 bus.

Abstract: Roughly described, a striping algorithm selects a route on which to transmit each next data segment, pseudorandomly from among a subset of eligible routes, the subset being chosen in dependence upon relative channel loading so far. Preferably each ingress node to a switching system chooses an outgoing route for each given next data segment, according to a pseudorandom algorithm, from among a respective given subset containing only those routes via which the amount of data sent from the ingress node during a respective prior time period is no greater than an average of the amount of data sent from the ingress node via any of its outgoing routes during the same prior time period.

Abstract: In a communication system, a first communication apparatus includes: an application data generating unit for generating application data including data at an application level and a priority at the application level; and a lower-level packet generating unit disposed therein for generating a packet by adding to the application data a header including a destination address and a source address at a level lower than the application level. A first relay apparatus includes: a priority identifying unit disposed therein for determining whether or not a priority is set in the application data of the packet received by the first relay apparatus, and thereby identifying a first priority at the application level; and a priority control unit disposed therein for renewing a TOS field value in the header of the packet, the header being at the level lower than the application level, on the basis of the first priority.

Abstract: The present invention relates to a communicating data system comprising devices (11, 12, 13, 14) for routing said data that are interconnected by communication links, the data being transmitted in packets and a packet comprising a header. A transmitting part of a first routing device (12) comprises first storage means suitable for storing a value of at least one parameter from said header and for transmitting a coded value corresponding thereto, and first entropy coding compression means which are suitable for recoding the uncoded value, the recoded value being stored instead of the coded value after the latter is transmitted along a communication link (15).

Abstract: A receiver including: a data regeneration mechanism that receives and regenerates data transmitted in units of a packet; a storage device in which received data is stored; a packet ID extraction unit that extracts a packet ID indicating a packet to be re-received; and a retransmission request unit that transmits retransmission request information, which requests retransmission of a packet to be re-received, to a transmitter. The transmitter retransmits only a packet, which is identified with a packet ID specified in the retransmission request information sent from the receiver, to the receiver. The receiver overwrites data, which is stored in the storage device, with data contained in a packet retransmitted from the transmitter. There is thus provided a recovery system for restoring data, which is preserved in the storage device, while regenerating data without stopping a motion picture irrespective of whether a lost packet is present.

Abstract: Improved scalability and performance for label switched routers are provided. Large numbers of interfaces may be readily accommodated. In one implementation, label imposition is divided between ingress and egress linecards so that the interface supporting a given service can be the one to impose any needed corresponding label.

Abstract: Path determination constraints may be encoded in the form of a program having one or more instructions. Each of instructions may include an operation code, and operands (or pointers to locations where operands are stored). In this way, an extensible, interoperable way for a nodes (e.g., label-switching routers) to communicate constraints within a network is provided. Such constraints may be inserted (e.g., as one or more CONSTRAINT objects) into signaling messages (e.g., a PATH RSVP message). By enabling the signaling of constraints, the determination of constraint-based (label-switched) paths can be distributed among a number of (label-switching) routers or other nodes. Upon receiving a message with constraints (e.g.

Abstract: Minimized Wave-zone Buoyancy is a new approach to oil and gas platform design with superior construction and performance characteristics compared to state-of-art off-shore drilling and production platforms. Minimized Wave-zone Buoyancy platforms capitalize on low cross sectional area of the portion of the platform exposed to waves. The low cross sectional area reduces buoyancy forces that result from vertical platform movement, enabling the platform to oscillate at a low natural frequency. The low cross sectional area also minimizes the cyclical vertical forces induced by waves. Compare to current designs, application of the Minimized Wave-zone Buoyancy concept will result in a lower natural frequency of oscillation, lower overall weight of platform, or both. Minimized Wave-zone Buoyancy offers an attractive alternative with improved platform stability, fatigue considerations, lower construction and installation costs, and shorter implementation schedule.

Abstract: A data aligner aligns a data segment having a granularity of less than a width of an internal data path. The data aligner aligns a fragment of data for alignment with a current segment or delay the fragment to combine with a next segment for alignment of data. A buffer receives the aligned data from the data aligner for interim storage and subsequent output onto an internal data path.

Abstract: Circuitry, embodied in a media subsystem (10A), reproduces a speech or other type of audio signal, and is operable when playing back audio data for reducing synchronization delay. A method operates by, when a frame containing audio data is sent to a decoder (20), measuring the synchronization delay; determining by how much the synchronization delay should be adjusted; and adjusting the synchronization delay in a content-aware manner by adding or removing one or more audio samples in a selected current frame or in a selected subsequent frame so as not to significantly degrade the quality of the played back audio data. When the synchronization delay is adjusted by more than one audio sample, the adjustment can be made by all of the determined audio samples in one adjustment, or the adjustment is made by less than all of the determined audio samples by a plurality of adjustments. The step of adjusting selects, if possible, an unvoiced frame and discriminates against a transient frame.

Abstract: A device capable of correcting time stamp value according to an embodiment of the present invention including an original time counter configured to generate and output an original time value, a subtracter configured to receive a network time value from the outside and the original time value from the original time counter, subtract the original time value from the network time value, and output the difference as a cycle-time difference value, and a first adder configured to receive an original time-stamp value generated from the original time value and the cycle-time difference value from the subtracter, add the cycle-time difference value to the original time-stamp value, and output the sum as a time-stamp value.

Abstract: A high-speed serial ATA physical layer transmits data over a communications medium using a serial ATA protocol. A serial ATA control circuit controls operation of the serial ATA physical layer. A serial ATA multiplexer outputs a serial ATA signal and has a plurality of input lines for receiving input data and a control input that communicates with the serial ATA control circuit. A serial ATA analog front end includes a first differential driver that communicates with the serial ATA multiplexer and provides a first gain to the serial ATA signal and a serial ATA pre-emphasis circuit that provides pre-emphasis to the serial ATA signal to alter a transmission characteristic of the serial ATA signal.

Abstract: The present invention provides a high speed bit stream data conversion circuit that includes input ports to receive first bit streams at a first bit rate. Data conversion circuits receive the first bit streams and produce second bit stream(s), wherein the number and bit rate of the first and second bit stream(s) differ. Symmetrical pathways transport the first bit streams from the input ports to the data conversion circuits, wherein their transmission time(s) are substantially equal. A clock distribution circuit receives and symmetrically distributes a clock signal to data conversion circuits. A central trunk coupled to the clock port and located between a first pair of circuit pathways with paired branches that extend from the trunk and that couple to the data conversion circuits make up the clock distribution circuit. The distributed data clock signal latches data in data conversion circuits from the first to the second bit stream(s).

Abstract: An L-band light source is provided that has improved amplifying efficiency and stabilized output power. The L-band light source comprises: a gain medium having first and second sides, and configured to generate an L-band amplified spontaneous emission (ASE); a first pump light source to generate first pumping light; a first wavelength selective coupler to supply the first pumping light to the gain medium; and a first reflector to reflect a part of ASE outputted to the fist side of the gain medium, the first reflector having a predetermined reflection.

Abstract: A passive Q-switch element is disclosed that permits operating a laser with a variable pulse repetition frequency (PRF). The Q-switch comprises two wedges of material, one made from saturable absorber material, the other from transparent material, with the two wedges mounted together to form a constant optical thickness block. By translating the block transversely to a laser beam the amount of saturable absorber material seen by the laser beam is altered and as a result the PRF of the laser is varied.

Abstract: A narrow linewidth fluorescent emitter can incorporate a chromophore into a microcavity that can support low-order optical modes.

Abstract: The present invention relates to a microdisk laser with a unidirectional generation property, and more particularly, to a microdisk laser designed in the form of a triangle, wherein the incident angles of portions of a laser beam at two upper sides of the triangle are greater than a critical angle to cause total reflection, so that the laser beam generates with directionality toward the base of the triangle. To this end, in the microdisk laser with the unidirectional generation property, the laser takes the shape of a triangle with two upper sides and the base and the two upper sides have their lengths greater than or equal to that of the base. Respective vertexes of the triangle or some of the vertexes are curved, and incident angles of portions of a laser beam at the two upper sides of the triangle are greater than a critical angle to cause total reflection, so that the laser beam generates with directionality toward the base of the triangle.