Abstract: A method for generating a complex amplitude in-line hologram and an image recording device using said method makes it possible to realize high-speed processing and high-speed recording from a single off-axis hologram without limiting the spatial frequency band and without creating errors from interpolation. The complex amplitude in-line hologram is generated by performing the following in order: the acquisition of data for one off-axis hologram obtained by way of off-axis holography, and for an off-axis reference light used for obtaining the hologram; the setting of a reconstruction in-line reference light; a modulation process for performing spatial heterodyne modulation on the hologram on the basis of the phases of the reference lights; and a filtering process for performing spatial frequency filtering on the hologram modulated by the modulation process. Because spatial sampling is not performed, the limits on the viewing angle are relaxed.

Abstract: An optical pickup device corresponding to an optical recording medium having a plurality of recording layers, and an optical drive using the device are provided. The optical pickup device includes a collimator lens disposed between an object lens and a light source. The collimator lens adjusts a focal length with respect to the optical recording medium, and the object lens focuses light passing through the collimator lens, on the optical recording medium. The object lens is optically optimized for an upper or second-upper recording layer of the optical recording medium.

Abstract: A recording apparatus for recording information on an optical recording medium includes a mode-locked laser unit that includes a semiconductor laser emitting a laser beam for recording the information on the optical recording medium, and an external resonator, an optical modulation unit that amplifies and modulates the laser beam emitted from the mode-locked laser unit, a recording signal generation unit that generates a recording signal based on a reference signal from a drive of the optical recording medium, and a modulation unit that generates a modulation signal for driving the optical modulation unit by latching the recording signal using a laser clock generated by an oscillation pulse of the laser beam emitted from the mode-locked laser unit.

Abstract: An optical pickup, photodetector, and optical drive adopting the optical pickup are provided. The optical pickup may include a light emitting system having a plurality of light sources corresponding to a plurality of mediums a light receiving system including a photodetector for converting light reflected from a medium into an electrical signal. The photodetector may include first and second light receiving sensors corresponding to the plurality of mediums, each of the first and second light receiving sensors comprising a plurality of regions, each region comprising a plurality of sectors. The plurality of regions of the first and second light receiving sensors may include shared sectors that are shared by the first and second light receiving sensors and exclusive sectors that are exclusively used in the first light receiving sensor or the second light receiving sensor.

Abstract: A method and system are described for canceling far end cross-talk in communication systems. A first transmitter transmits the first effective data source signals across the first channel. A second transmitter transmits the second effective data source signals across the second channel. In one embodiment, a receiver unit receives first and second effective data source signals across a first channel and a second channel, respectively, and also one or more cross-talk signals. A far end cross talk (FEXT) canceller located in the receiver unit receives second estimated effective data source signals based on the second effective data source signals. The receiver unit cancels the one or more cross-talk signals using the second estimated effective data source signals.

Abstract: A method and an apparatus for receiving a Minimum Mean-Squared-Error (MMSE) in a Single-Carrier Frequency Division Multiple Access (SC-FDMA) system is provided. The method includes, transforming a signal in a time domain received through an antenna into a signal in a frequency domain, and discriminating between bands respectively allocated to terminals in a frequency domain, estimating a channel and computing a weight value from the signal transformed into the frequency domain, and detecting an MMSE, computing a time-domain bias from the weight value and a channel estimation value of the signal transformed into the frequency domain, normalizing the detected MMSE by using the computed time-domain bias, and transforming the normalized signal into a normalized signal in a time domain, decoding the normalized signal transformed to the time domain, and transmitting the decoded normalized signal transformed into the time domain to each of the terminals.

Abstract: Embodiments of the present disclosure describe closed loop scheduled peak-to-average power (PAPR) reduction systems and methods to facilitate desired PAPR reduction. Other embodiments describe weighted tone reservation (WTR) methods and systems for PAPR reduction. Still other embodiments may be described and claimed.

Abstract: An apparatus for sampling clock recovery (SCO) and methods for estimating and compensating SCO are provided. The apparatus comprises a symbol timing adjustment module for shifting forward or backward symbol timing of the transmitted OFDM symbols; a discrete Fourier transform (DFT) processor for performing DFT to an output from the symbol timing adjustment module; a channel estimator for undertaking a channel frequency response estimation based on a channel estimation sequence; a SCO phase rotator for receiving and performing phase shift on the transmitted OFDM symbols of a frame header and a frame payload; an SCO estimation stage for undertaking an SCO estimation based on a pilot-subcarrier-related output of the SCO phase rotator and the CFR estimation; and an SCO compensation distributor for dividing the SCO estimation into integer and fractional portions and then distributing them into the symbol timing adjustment module and the SCO phase rotator, respectively.

Abstract: Messages transmitted between a receiver and a transmitter are used to maximize a communication data rate. In particular, a multicarrier modulation system uses messages that are sent from the receiver to the transmitter to exchange one or more sets of optimized communication parameters. The transmitter then stores these communication parameters and when transmitting to that particular receiver, the transmitter utilizes the stored parameters in an effort to maximize the data rate to that receiver. Likewise, when the receiver receives packets from that particular transmitter, the receiver can utilize the stored communication parameters for reception.

Abstract: A method of re-establishing a radio bearer in a wireless communication system is disclosed. The method of re-establishing a radio bearer of a user equipment in a wireless communication system comprises establishing a radio bearer; identifying whether an error has occurred in the radio bearer; and selectively re-establishing the radio bearer or all radio bearers of the user equipment in accordance with a type of the radio bearer if the error has occurred in the radio bearer.

Abstract: According to one embodiment, a method may include detecting an occurrence of a fault for a component of a network element having a maintenance entity provisioned thereon. The method may further include transmitting alarm indication suppression messages to components for which the maintenance entity was configured to transmit alarm indication suppression messages in response to detecting the occurrence of the fault.

Abstract: In a communication apparatus, a receive data processor receives data and retrieves a group data record corresponding to the received data out of a group data memory. A forwarding processor forwards the received data according to the group data record retrieved by the receive data processor. The group data memory stores group data records which associate protection group identifiers with path selection data. The protection group identifiers each identify a protection group that provides logical paths constituting a redundant logical path for transporting a group of data, and their corresponding path selection data specifies which logical path to use to forward data in that protection group.

Abstract: A network system having duplicate lines of a primary system and a backup system between a transmitter apparatus and a receiver apparatus is provided. Each of the transmitter apparatus and the receiver apparatus includes an arithmetic operator for conducting a BIP-8 arithmetic operation and a CRC arithmetic operation on an input signal and thereby detecting a bit error. The transmitter apparatus transmits data to both lines. The receiver apparatus includes a switcher. When a bit error is detected in received data of the primary system. the switcher switches control of the primary system and the backup system. Hitless protection switching of a VC path is executed.

Abstract: The present invention relates to a method and an implementing apparatus for cooperative multi-hop routing in a wireless network. According to the method the diversity gains and the interrupt probabilities in a cooperative communication manner between master nodes in the route are obtained, and the segmenting mode for sending packet data is determined accordingly, thus implementing cooperative communication in a multi-hop route, where signals having same information are sent through different paths, and multiple independently faded copies of data symbols may be obtained at a receiver end, thus obtaining higher reception reliability and higher transmission capacity, and improving performance of a communication process.

Abstract: The present invention discloses a method for protecting a data service in Metropolitan Area Transport Networks, a work path for services transport is established between a source node and a work destination node of the services in the Metropolitan Area Transport Network, and the method includes: setting a protection destination node using the nodes except the work destination node, and establishing a protection path between the source node and the protection destination node to protect the services of the work path; detecting by the source node the failure state of the links of the work path and the protection path, and the failure state of the nodes in the links; detecting by the work destination node and the protection destination node the failure state of the links connecting themselves with data devices, respectively, and notifying the source node when there is the failure state; switching the data services of the work path to the protection path after the source node detects the failure state of the link

Abstract: A non-transitory computer-readable medium includes instructions for receiving a message associated with a session with a user device; determining that a quantity of tokens, to be used to process the message, is less than another quantity of tokens stored in a memory; determining that a session time is less than a threshold based on the determination that the quantity of tokens is less than the other quantity of tokens; determining that a violation has occurred when a time interval is greater than an interval threshold based on the determination that the session time is less than the threshold, where the time interval is from a prior time when another message, associated with the session, was received to a time that the message was received, and where the determining includes incrementing a quantity of violations associated with the session; outputting the message when the quantity of violations is not greater than a violation threshold; and dropping the message when the quantity of violations is greater than

Abstract: Systems and methods for scheduling network communications in a managed network can include receiving in a Network Coordinator a submission from each of a plurality of network nodes requesting, for their respective flows, reservation of communication slots in a communication window, the submission including scheduling information such as latency tolerance maximum aggregation amount; the Network Coordinator checking available bandwidth in the communication window; and the Network Coordinator allocating the available bandwidth to a first flow from a first requesting node based on the first flow's scheduling information and the bandwidth availability, and deferring allocation of bandwidth to a second flow from a second requesting node until a later window based on the second flow's scheduling information and the bandwidth availability, thereby reallocating peak demand among the plurality of requesting nodes across a plurality of communication windows.

Abstract: A network device includes multiple packet processing engines implemented in parallel with one another. A spraying component distributes incoming packets to the packet processing engines using a spraying technique that load balances the packet processing engines. In particular, the spraying component distributes the incoming packets based on queue lengths associated with the packet processing engines and based on a random component. In one implementation, the random component is a random selection from all the candidate processing engines. In another implementation, the random component is a weighted random selection in which the weights are inversely proportional to the queue lengths.

Abstract: Various embodiments provide a way to adjust transmission rates of a medium access controller (MAC) to a physical layer (PHY) to accommodate for packet expansions due to encryption that takes place in the PHY. In at least some embodiments, a communication interface between different MACs in a system is re-purposed to allow the PHY to communicate to a system MAC to notify the system MAC to pause and then resume, at an appropriate time, its packet transmissions.

Abstract: A local area network includes computers and peripherals networked in a high-speed LAN with access to a WAN through a slower connection via a broadband modem. A LAN gateway device manages data traffic between the local computers and peripherals and between the LAN and the WAN. The LAN gateway device provides multiple features, such as wired or wireless links, security, firewall, NAT, DCHP, traffic management, and the like. Traffic management features include an automatic quality of service priority classification scheme. A quality of service module automatically assigns priorities to the data streams based on analysis of the data packets. A configuration access list can be provided with pre-configured priorities for some streams. Initially, all streams are given highest priority and subsequently the priority is automatically adapted to the results of the packet analysis.

Abstract: Example methods and apparatus for hierarchical bandwidth management are disclosed. An example method includes, using dual-token bucket meters (two-rate three-color meters) to meter bandwidth usage by individual microflows and associated macroflows (combinations of microflows). The dual-token bucket meters are used to locally and finally mark the packets using a three-color marking approach. In the example method, forwarding and discard decisions for packets processed using such techniques are made based on the final marking.

Abstract: A method, apparatus, and computer program product for responding to congestion levels in a communication system by rate adaptation. A congestion condition is indicated by marking data packets. In response to receiving an indication of congestion, a data rate is reduced. A rate reduction inhibit timer is started, and further rate reduction is initiated if congestion is indicated after the rate reduction inhibit timer has expired. A rate increase timer is used to initiate a rate increase if no indication of congestion is received during a rate increase time.

Abstract: Associating hosts with subscriber and service based requirements is disclosed. An identifier is extracted from a DHCP or other network address lease communication associated with a subscriber host. The identifier is used to associate the subscriber host with a requirement that is subscriber based, service based, or both subscriber and service based. The subscriber host is included in a set of one or more subscriber hosts associated with the subscriber, the service, or both, as applicable to the requirement, and the requirement is required to be enforced collectively to the one or more subscriber hosts comprising the set.

Abstract: The present application relates to network configurations and specifically to scalable load balancing network configurations. One implementation includes an external client coupled to a scalable load balancing system. The scalable load balancing system includes a load balancing layer that is configured to encapsulate individual incoming packets of a packet flow from the external client. The load balancing layer is further configured to route the incoming packets to target devices on the system. The target devices can span multiple IP subnets. The incoming packets can pass through one or more load balancers of the load balancing layer before reaching individual target devices. Individual target devices can be configured to route at least some outgoing packets of the packet flow to the external client without passing through any of the one or more load balancers.

Abstract: A variable data rate wireless transmitter configured to receive input of data from a plurality of input channels and transmit at least some of the data over a variable data rate wireless point-to-point communication link, wherein portions of the data are associated with priorities, and the wireless transmitter is configured to change transmission of at least some of the portions of the data, based, at least partly, on the priorities associated with the portions of the data, and on a data rate configured for transmitting the portions of the data over the variable data rate wireless communication link.

Abstract: A network feedback method and appropriate devices are described, in which a node connected to a link can perform a remote flow control adjustment procedure for adjusting the flow control of a sender of data units being forwarded by node over the link.

Abstract: A method, a device, and a system for network interception are provided. The method for network interception includes the following steps. A matching rule obtained by parsing an interception policy. Received data are selected by adopting a deep packet inspection (DPI) according to the matching rule so as to obtain an interception result, in which the received data are obtained by adopting data preprocessing to filter packet data according to a service customizing rule obtained by parsing the interception policy. The system for network interception includes a service probe server (SPS) and a service analyze server (SAS). Thus, various packet data services transmitted over an Internet protocol (IP) network can be intercepted.

Abstract: In one embodiment, an aggregation device operating in a computer network may have a down maintenance end point (MEP) configured on certain of its user-to-network interface (UNI) ports. These down MEPs may then receive continuity check messages (CCMs) from down MEPs configured on customer edge (CE) devices, where each CCM has a media access control (MAC) address of a corresponding CE device UNI port from which the CCM is transmitted. In response to detecting conflicting MAC addresses between CE device UNI ports based on the CCMs, the aggregation device may notify the CE devices corresponding to the conflicting MAC addresses of the conflict.

Abstract: An apparatus, method, and system are provided for determining a location of an error source. Equalization coefficients may be retrieved and an average period of time between localized peak amplitudes may be determined. The average period of time may be multiplied by a velocity of propagation associated with a communication channel to determine an approximate location of the error source. The equalization coefficients may correspond to the inverse of the frequency response associated with the communication channel and may be updated over time using replacement or combination (e.g., convolution) techniques.

Abstract: Serial networking dedicated fiber optic inflight entertainment (IFE) systems, methods therefor and components thereof, that exhibit improved configuration and failover attributes through implementation of novel network configuration protocols. In some aspects of the invention, such an IFE system comprises a plurality of head end line replaceable units (HE-LRUs) and a plurality of serial networking line replaceable units (SN-LRUs), wherein each of the SN-LRUs individually detects that a closed system network has been formed between the plurality of HE-LRUs and the plurality of SN-LRUs based on a plurality of packets sourced by at least one of the HE-LRUs and received on a plurality of ports of each of the SN-LRUs, and wherein in response to detecting that the closed system network has been formed one of the SN-LRUs blocks one of its ports based on further detecting that the SN-LRU is a middle SN-LRU.

Abstract: A physical layer device for a network interface, in which the physical layer device includes a cable-test module and a data processing module. The physical layer module is configured to selectively test a cable connected to the physical layer device and to generate test data. The data processing module includes a first processor configured to process the test data and to generate test results indicating a cable status of the cable. The first processor is configured to selectively communicate the cable status to a second processor of a medium access controller.

Abstract: A method of diagnosing a transmission loop in an Internet protocol television (IPTV) network includes configuring the loop as an open loop and performing a single-ended loop test (SELT), configuring the loop as a terminated-loop and performing another SELT, subtracting a trace of the first SELT from a trace of the second SELT, and determining the length of the loop from the result. A service assurance system in an IPTV network includes a test module and a DSLAM coupled to a residential gateway by a transmission loop. The test module operates to determine that a fault condition on the IPTV network is caused by a fault in the loop, direct the DSLAM to perform an open loop SELT and a terminated-loop SELT on the loop, receive the results of the SELTs, and determine a location of a tap on the loop based upon the results.

Abstract: A system and method for updating forwarding tables in a blade packet manager is provided. The blade packet manager may include master and slave blades. A master management module on the master blade monitors the slave blades. Network address entry forwarding tables are maintained on the slave blades. A periodic sweep of slave blades for activity information is performed and reports are forwarded to the master blade. The master blade propagates the reported information from the master blade to each of the slave blades to update forwarding tables on each of the slave blades.

Abstract: A transfer path of a multicast packet is set to an output port, from among a plurality of outputs each associated with a plurality of input ports, which is specified to output the multicast packet. The number of completed path setting processes which is the number of processes for which path setting has been completed, is counted. It is determined whether or not the number of completed processes counted is identical with the number of processes for executing the multicast communication. When it is determined that the numbers are identical with each other, it is recognized that the transfer path setting of the multicast communication has been completed.

Abstract: A computer program product comprises computer-readable instructions that cause a network management device (selected from one or more devices including one or more configured devices to which usage parameters necessary for using functions available via a network have already been set) to execute a process for managing the usage parameters comprising: a parameter acquisition step of acquiring one or more usage parameters already set to one of the configured devices from the configured device; and a candidate reporting step of reporting the usage parameters acquired in the parameter acquisition step as candidates for one or more usage parameters to be set to a setting target device which is connected to the network management device to be capable of data communication via a network and needing the setting of the usage parameters.

Abstract: A radio communication system of a frequency hopping system, which carries out time division multiplex by TDMA and carries out communications while changing over two or more frequencies with respect to a radio link, wherein radio resources are efficiently utilized by establishing a plurality of radio links. A first communication apparatus periodically transmits control data by a frame cycle and a second communication apparatus which is a communication partner thereof receives the above-described control information during standby and secures synchronization in timing of frames and slots and timing of frequency hopping. Communication signals between both communication apparatuses and control information are overlapped in a slot to establish radio links. Once radio links are established in a plurality of slots other than a slot for transmitting control information, control is performed such that the control information is overlapped in the slots in which a radio link is established.

Abstract: Embodiments herein relate to associating an account of a user of a handheld computer with at least a second computer. A request is sent by the second computer to associate the second computer with the account of the user. Whether the second computer is authorized to be associated with the account is determined. The second computer is allowed to access resources on a network if the second computer is authorized to be associated with the account.

Abstract: A method, an apparatus, and a computer program product for wireless communication are provided in which a plurality of uplink carriers are utilized in a cellular communications system. In an aspect of the disclosure, a wireless terminal configured for use in a cellular network transmits an uplink with a plurality of uplink carriers including an anchor carrier and a secondary carrier, and receives a downlink with a plurality of downlink carriers. Here, the wireless terminal provides feedback information, such as a channel quality indicator and an acknowledgment, corresponding to the plurality of downlink carriers, on an uplink channel on each of respective carriers in a subset of the plurality of uplink carriers.

Abstract: A method is provided for determining a transmission rate of a control response frame for acknowledging data receipt in a wireless local area network. The method includes obtaining transmission parameters of a transmitting station from a data transmission frame received from the transmitting station, searching a receiving station for transmission parameters which correspond to the transmission parameters of the transmitting station, determining the transmission rate of the control response frame according to transmission parameters of the receiving station if the transmission parameters corresponding to the transmission parameters of the transmitting station are found in the receiving station, and determining a maximum rate among a set of basic transmission rates to be the transmission rate of the control response frame if the transmission parameters corresponding to the transmission parameters of the transmitting station are not found in the receiving station.

Abstract: A PT (e.g., Push-To-Talk, Push-To-View or Push-To-Data) service, and more particularly, to a method and device for controlling a floor (talk burst authority, permission to send media burst, etc.) in a PT service, are discussed. According to an embodiment, the method for controlling a state of a Push-To (PT) server, includes starting, by a PT server, a stop talking (T2) timer which is a type of media burst control timer that operates with respect to a terminal having permission to send a media burst; checking, by the PT server on expiry of the T2 timer, whether a media burst release message was already received while the T2 timer was running; and entering, by the PT server, a media burst idle state if the media burst release message was already received as a result of the checking step.

Abstract: Network computing systems may implement data loss prevention (DLP) techniques to reduce or prevent unauthorized use or transmission of confidential information or to implement information controls mandated by statute, regulation, or industry standard. Implementations of network data transmission analysis systems and methods are disclosed that can use contextual information in a DLP policy to monitor data transmitted via the network. The contextual information may include information based on a network user's organizational structure or services or network infrastructure. Some implementations may detect bank card information in network data transmissions. Some of the systems and methods may be implemented on a virtual network overlaid on one or more intermediate physical networks that are used as a substrate network.

Abstract: System(s) and method(s) are provided to collect network operation data within a confined indoor wireless environment for generation of competitive intelligence and strategic network planning. Scanner component(s) survey and compare signals transported in a set of electromagnetic frequency bands, and in accordance with a set of radio technologies associated with competing networks. Collected data can be aggregated and delivered to femto gateway node(s), which can supply the data to an analysis component that generates network operations NetOp intelligence. A report component can manage received and aggregated network operation data and convey a portion thereof to planning tool(s) that can produce competitive intelligence and develop strategic network planning. Planning tool(s) can request specific network operation data or NetOp intelligence.

Abstract: A communication system, method and client program for communicating via a first network. The system comprises a first network and a router coupling the second network to the first network, the router comprising an address translator configured to map second-network addresses to a lesser number of first-network addresses identifying the second user nodes collectively to the first network. Each of the second user nodes is installed with a communication client configured so as when executed on the second user nodes to: compare the first-network addresses of two of the user nodes, and, if their first-network addresses match such that both are nodes of the second network, communicate an availability status of one of the two user nodes between the two user nodes directly over the second network without routing via the first network.

Abstract: A method and device for installing and distributing routes are disclosed. The routes are classified and installed respectively according to route types. Therefore, the distributed storage of a Forwarding Information Base (FIB) is automated, massive manual configuration work is avoided, and the problem of oversized FIB of the router as a result of fast growth of the routing table is solved.

Abstract: A computer algorithm (36) employing decision trees in order to assign wireless communication nodes (12-19,39-43) in a derived spatial arrangement. In a first embodiment, the algorithm (36) assigns nodes to an array of positions corresponding to the positions of luminaires (2-9) in a lighting array (1) to enable the lighting array (1) to be commissioned automatically. In a second embodiment, the algorithm (36) assigns nodes to control groups (49-51) such that the member nodes of a particular control group (49-51) may be controlled by a single switch or sensor (46-48). The use of decision trees allows the final assignment of nodes to be delayed until more information has been taken into account, thus, the algorithm (36) is able to select the best overall configuration.

Abstract: Multimodal teleconferencing including receiving, by a multimodal teleconferencing module, a speech utterance from one of a plurality of participants in the multimodal teleconference; identifying the participant making the speech utterance as a current speaker; retrieving, by the multimodal teleconferencing module from accounts for the current speaker, content for display to the current speaker; retrieving, by the multimodal teleconferencing module from accounts for the current speaker, content for display to one or more other participants in the multimodal teleconference; providing, by the multimodal teleconferencing module to a multimodal teleconferencing client for display to the current speaker, an identification of the speaker and the content retrieved for the speaker; and providing, by the multimodal teleconferencing module to one or more of multimodal teleconferencing clients for display to the other participants, an identification of the current speaker with the content retrieved for the one or more ot

Abstract: Gaze tracking or other interest indications are used during a video conference to determine one or more audio sources that are of interest to one or more participants to the video conference, such as by determining a conversation from among multiple conversations that a subset of participants are participating in or listening to, for enhancing the audio experience of one or more of the participants.

Abstract: A communication device and method using a cooperative transmission and network coding transmission scheme are provided. A mobile station (MS) includes a data receiving unit to receive network coding data transmitted from at least one relay station (RS) and downlink data transmitted from a base station (BS), and a data transmission unit to transmit uplink data to the BS and the at least one RS, wherein the BS transmits the downlink data to the at least one RS.

Abstract: A signal communication apparatus comprising first and second channels for communicating signals between two electronic devices; each of said first and second channels has a transmitter for transmitting signals, a receiver for receiving signals and an interface arranged between the transmitter and the receiver. The transmitters code the signals in the form of a frame of H bits, with H being an integer, and adapted to serially transmit said frame of H bits through said interface, and the receivers decode the frames of H bits, a frame of H bits having P data bits, K redundancy bits and a sequence of L control bits adapted to identify the type of frame to be transmitted, with L, P and K being integers.

Abstract: A transmitting method of a signal on a random access channel in a wireless communication system, comprises the steps that: a terminal transmits a preamble on the random access channel with a set time length ahead of the end position of an uplink pilot time slot, and the length of the preamble is the length of two symbols without a cyclic prefix. Another transmitting method of a signal on a random access channel in a wireless communication system, comprises the steps that: a terminal transmits a cyclic prefix and a preamble on the random access channel with a set time length ahead of the end position of an uplink pilot time slot, and the length of the preamble is the length of two symbols without a cyclic prefix. The methods can avoid the interference of the preamble to the data of the uplink subframe, and can improve the coverage area of the random access channel and the work efficiency of the time division duplex system.