Abstract: A method of operation in a receive circuit is disclosed. The method comprises entering an initialization mode followed by receiving training data from a lossy signaling path. The training data originates from a transmit circuit. The received training data is sampled and minimax transmit equalizer coefficients are generated based on the sampled data. The minimax transmit equalizer coefficients are then transmitted back to the transmit circuit. The initialization mode is exited and an operating mode initiated, where transmit data precoded by the minimax transmit equalizer coefficients is received.

Abstract: In described embodiments, a transceiver includes a clock and data recovery module (CDR) with an eye monitor and a cycle slip monitor. The cycle slip detector monitors a CDR lock condition, which might be through detection of slips in sampling and/or transition timing detection. The cycle slip detector provides a check point to sense system divergence, allowing for a mechanism to recover CDR lock. In addition, when the CDR is out-of-lock, the various parameters that are adaptively set (e.g., equalizer parameters) might be invalid during system divergence. Consequently, these parameters might be declared invalid by the system and not used.

Abstract: As a digitized representation of an intermediate frequency television signal moves through a demodulator it undergoes a number of processes, including conversion from an analog signal to a digitized data, digital signal processing of the digitized data, and the like. The rate at which the digitized data moves through the digital signal processor of the demodulator for processing is referred to as the data rate of the DSP. The demodulator can vary the data rate based on a selected television channel, thereby reducing the level of interference at the demodulator resulting from noise.

Abstract: A method for receiving a signal having a succession of symbols, transmitted by a digital modulation, each symbol transmitted having a phase and an amplitude belonging to a set of values in finite number, the method includes evaluating a phase error (PHE) on a received symbol (S), resulting from a signal transmission noise, correcting the phase of the received symbol according to the phase error evaluated, demodulating the symbol corrected in phase, and modeling the transmission noise by a Gaussian component not correlated with the signal received and defined by a power and an interference component defined by an amplitude and which phase is substantially uniformly distributed, the phase error of the received symbol evaluated on the basis of the power of Gaussian component and the amplitude of the interference component.

Abstract: A method of performing a random access procedure in multiple component carrier system is provided. The method includes transmitting a random access preamble on an uplink component carrier, receiving a response to the random access preamble, transmitting an identity for the MS based on the response and monitoring a downlink component carrier linked to the uplink component carrier among a plurality of aggregated downlink component carriers. It is clear which downlink component carrier the MS needs to monitor for contention resolution.

Abstract: A collision avoidance method for subscribers to fight for a right to speak of a multi-party conversation in a digital intercommunication system includes: sending a frame of instructions from the transmitting subscriber to the receiving subscribers for declaring a beginning of a fight for phase; in a subset of frame moments during the fight-for phase, sending maintenance information by the transmitting subscriber to the receiving subscribers; in another subset of the frame moments during the fight-for phase, broadcasting a request for the right to speak by the receiving subscribers intending to obtain the right to speak in turn, the fight-for phase not closing until at least one of the receiving subscribers sends out a request message; hearing the request message, ceasing fighting for the right to speak by the other receiving subscribers; and the receiving subscriber obtaining the right to speak as a new transmitting subscriber and beginning to speak.

Abstract: According to one embodiment, a frequency offset compensation apparatus includes a first estimation unit, a second estimation unit, a setting unit, a synthesis unit and a compensation unit. The first estimation unit estimates a first rotation. The second estimation unit estimates a second rotation. The setting unit sets a weighting factor for the second rotation to a first value if a received power is less than a threshold value, and sets the weighting factor for the rotation to a second value being smaller than the first value if the received power is not less than the threshold value. The synthesis unit calculates a compensation value. The compensation unit compensates for a frequency offset.

Abstract: Systems and techniques relating to wireless communications are described. A described technique includes monitoring a group of wireless channels that are useable by at least a first wireless communication device for wireless communications, receiving one or more beacon signals from one or more second wireless communication devices, identifying, within the group of wireless channels, one or more primary channels on which the one or more beacon signals are received, estimating a traffic load for the one or more identified primary channels, determining, based on the estimated traffic load, whether to use as a primary channel for the first wireless communication device, a channel of the one or more identified primary channels or a channel of the group of wireless channels that is separate from the one or more identified primary channels; and selecting the primary channel for the first wireless communication device based on a result of the determining.

Abstract: A wireless client station including a transmitter to transmit data, a receiver having a sensitivity, a signal strength module, and a control module. The sensitivity of the receiver corresponds to a minimum signal strength that the receiver is able to detect. The signal strength module is configured to estimate signal strengths of signals received from a plurality of access points. Each signal received from the plurality of access points respectively indicates a power being dissipated by access point that transmitted the signal. The control module is configured to, for each access point, determine a path loss based on i) the strength of the signal received from the access point, and ii) the power indicated as being dissipated by the access point, and to adjust a minimum transmit power level of the transmitter based on i) a lowest one of the path losses and ii) the sensitivity of the receiver.

Abstract: A method for performing delay locked looping upon a received signal which reduces the asymmetry of auto-correlation function resulting from sampling is provided. The received signal is a spread spectrum code signal, and the method includes: generating a plurality of replica spread spectrum code signals according to an estimated code phase delay and phase spacing, the replica spread spectrum code signals having phases respectively different from the phase of the received signal; calculating a spread spectrum code error statistics signal according to the replica spread spectrum code signals and the received signal; and adjusting the estimated code phase delay according to the spread spectrum code error statistics signal and a phase difference between a sampled point of at least one replica spread spectrum code signal and a corresponding signal transition point.

Abstract: A mobile data network includes a radio access network and a core network. A first service mechanism in the radio access network breaks out data coming from a basestation. When data is broken out by the first service mechanism, the data is delivered at the edge, which means the true activity of the channel is not visible to the core network. In order to maintain the high-speed channel, channel maintenance data packets are sent to and from the radio network controller on the network tunnel. The maintenance channel is also used to send cache miss data to a subscriber when a cache miss occurs at the edge of the mobile data network, without regard to a need for channel maintenance data packets.

Abstract: A base station apparatus includes a transmit diversity setting unit configured to set a transmit diversity mode to be applied to a user equipment terminal; a reception quality calculating unit configured to determine reception quality corresponding to the transmit diversity mode based on the transmit diversity mode set by the transmit diversity setting unit; a scheduling unit configured to determine a user equipment terminal to which a radio resource is to be allocated based on the reception quality determined by the reception quality calculating unit; and a notifying unit configured to notify the user equipment terminal to which the radio resource is allocated as determined by the scheduling unit of the transmit diversity mode to be applied.

Abstract: User Equipment (UE) transmits an acknowledgement signal in response to the reception of multiple Scheduling Assignments (SAs) transmitted by a base station. The SAs consist of Information Elements (IEs) including a Transmission Power Control (TPC) IE providing adjustments for the transmission power of the acknowledgement signal. The TPC IE in a first SA of the multiple SAs is used to provide the previous adjustments and the TPC IEs in the remaining of the multiple SAs are used to provide an indication of the resource used for the transmission of the acknowledgment signal.

Abstract: Apparatus and methods are disclosed, such as those involving deskewing serial data transmissions. One such apparatus includes a plurality of receivers, each of which is configured to receive a serial data stream. Each of the receivers includes a shift register including a plurality of stages arranged in sequence to propagate a stream of characters. Each of the stages is configured to store a character, and shift the character to a next stage in response to a clock signal. The receiver also includes a multiplexer having a plurality of inputs, each of the inputs being electrically coupled to a respective one of the stages of the shift register, and to select one of the stages to generate an output such that the outputs of the multiplexers in the receivers are deskewed.

Abstract: A communication terminal includes first and second transmitters, which are coupled to produce respective first and second Radio Frequency (RF) signals that are phase-shifted with respect to one another by a beamforming phase offset, and to transmit the RF signals toward a remote communication terminal. The terminal includes a reception subsystem including first and second receivers and a phase correction unit. The first and second receivers are respectively coupled to receive third and fourth RF signals from the remote communication terminal. The phase correction unit is coupled to produce, responsively to the third and fourth RF signals, a phase correction for correcting an error component in the beamforming phase offset.

Abstract: Apparatus and methods are disclosed, such as those involving deskewing serial data transmissions. One such apparatus includes a plurality of receivers, each of which is configured to receive a serial data stream. Each of the receivers includes a shift register including a plurality of stages arranged in sequence to propagate a stream of characters. Each of the stages is configured to store a character, and shift the character to a next stage in response to a clock signal. The receiver also includes a multiplexer having a plurality of inputs, each of the inputs being electrically coupled to a respective one of the stages of the shift register, and to select one of the stages to generate an output such that the outputs of the multiplexers in the receivers are deskewed.

Abstract: A mobile data network includes a radio access network and a core network. A first service mechanism in the radio access network breaks out data coming from a basestation. When data is broken out by the first service mechanism, the data is delivered at the edge, which means the true activity of the channel is not visible to the core network. In order to maintain the high-speed channel, channel maintenance data packets are sent to and from the radio network controller on the network tunnel. The maintenance channel is also used to send cache miss data to a subscriber when a cache miss occurs at the edge of the mobile data network, without regard to a need for channel maintenance data packets.

Abstract: A mobile communications device with a wireless module and a controller module is provided. The wireless module receives a connection release message for leaving a connected mode from a wireless network. The controller module in response to the connection release message, keeps radio resources of a multimedia broadcast and multicast services (MBMS) service unreleased and releases all radio resources other than the MBMS service. Thereafter, the controller module enters an idle mode.

Abstract: Methods and apparatus are provided for pseudo asynchronous testing of receive paths in serializer/deserializer (SerDes) devices. A SerDes device is tested by applying a source of serial data to a receive path of the SerDes device during a test mode. The receive path substantially aligns to incoming data using a bit clock. A phase is adjusted during the test mode of the bit clock relative to the source of serial data to evaluate the SerDes device. The source of serial data may be, for example, a reference clock used by a phase locked loop to generate the bit clock. The phase of the bit clock can be directly controlled during the test mode, for example, by a test phase control signal, such as a plurality of interpolation codes that are applied to an interpolator that alters a phase of the bit clock.

Abstract: Various embodiments are described to enable multiple, independent communication networks to share in an autonomous and dynamic manner unlicensed wireless resources. Generally, this involves determining that a first network node (122) is using at least a portion of a wireless resource to provide network service to at least one remote unit (102). A second network node (123), under the control of a different network operator than the first node and desiring to use the wireless resource, sends the first network node, a request to relinquish use of at least a portion of the wireless resource. The second network node sends this request wirelessly, perhaps using the wireless resource itself. If the first network node grants the request, the second node may then begin using at least a portion of the relinquished resource to provide network service.

Abstract: An entity, such as a base station, in a wireless communications network performs power control of a control channel based on one or more characteristics of a message in the control channel. For example, the control channel can be a paging channel. The one or more characteristics include, as examples, the size and/or the type of message in the control channel.

Abstract: A method and apparatus for determining multilevel scheduling of a reverse link communication. An embodiment includes estimating capacity on the reverse link based on the sector load. An embodiment includes estimating load contribution based on an estimated signal-to-noise ratio. An embodiment includes estimating capacity available to schedule based on a ratio of measured other-cell interference over thermal noise, and based on sector load. An embodiment includes a method of distributing sector capacity across a base station (BS) and a base station controller (BSC). An embodiment includes determining priority of a station based on the pilot energy over noise plus interference ratio, the soft handoff factor, the fairness value, and the fairness factor ?.

Abstract: Methods and apparatus for sensing features of a signal in a wireless communication system are disclosed. The disclosed methods and apparatus sense signal features by determining a number of spectral density estimates, where each estimate is derived based on reception of the signal by a respective antenna in a system with multiple sensing antennas. The spectral density estimates are then combined, and the signal features are sensed based on the combination of the spectral density estimates.

Abstract: A method for a user equipment to perform a random access to a network in a mobile communication system includes transmitting a random access preamble to the network; receiving a medium access control packet data unit (MAC PDU) via a downlink shared channel, wherein the MAC PDU comprises one or more sub headers in a first part of the MAC PDU and one or more random access responses in a second part of the MAC PDU subsequent to the first part, and wherein the random access responses include first uplink resource allocation information; transmitting a first uplink data based on the first uplink resource allocation information in one of the random access responses; and transmitting a second uplink data based on second uplink resource allocation information when the second uplink resource allocation information is received via a downlink control channel.

Abstract: A terminal (such as that belonging to or carried by an emergency first responder, for example) participates in a push to talk multicast group in either of two modes or levels. In a first mode or first level of participation, the terminal can join a multicast address for the push to talk multicast group as a passive recipient of transmissions and can thereby listen to the multicast address. In a second mode or second level of participation, the terminal becomes an active participant in the push to talk session. As an active participant in the push to talk session, the terminal can, e.g., receive sender identification (e.g., identification of other participants who may be talking in the push to talk multicast group) and send media bursts to the multicast group.

Abstract: An approach and apparatus for adaptive scanning for detection and classification of an RF signal. Time-domain and frequency-domain information are acquired and processed over a broad band of frequencies segmented into channels to produce signal features. The signal features are classified using a signal classifier into signal discriminants, from which a signal of interest is located and identified. Subsequent channel scans then place an increased relative or absolute dwell time on the channel believed to contain the signal of interest.

Abstract: A phase locked loop includes a voltage controlled oscillator operable to generate an output signal corresponding to a reference signal in response to a control voltage signal outputted by a filter in response to a current signal, and a variable frequency divider operable to perform frequency division on the output signal using a variable divisor so as to generate a divided feedback signal. A charge pump outputs the current signal in response to a phase detecting output from a phase/frequency detector indicating phases of the divided feedback signal and the reference signal. A phase error comparator outputs, in accordance with the phase detecting output, a digital output indicating whether the divided feedback signal lags or leads the reference signal and further indicating a phase difference between the divided feedback signal and the reference signal.

Abstract: A method and system of fine timing synchronization for an OFDM signal. The OFDM signal is coarse timing synchronized, generating a synchronization sequence and a CFR (Channel Frequency Response). The synchronization sequence is removed. A correlation coefficient of the correlation between the CFR applied to a number of carriers and the number of carriers with different window shifts is calculated. The largest window shift corresponding to a downsampling factor is indicated by the lowest correlation coefficient greater than a threshold. The CFR is downsampled by the downsampling factor, and an inverse FFT is performed on the downsampled CFR with a reduced number of calculations reduced by the downsampling factor, transforming the CFR into a CIR. A fine timing synchronization position is determined from the CIR and is utilized by an FFT unit within an OFDM receiver to accurately receive OFDM symbols of the OFDM signal.

Abstract: A clock and data recovery device recovers data from a sequential stream of data that includes bursts of data separated by gaps. Each burst of data arrives with its own phase and with its own deviation from a nominal frequency. The bursts of data begin with a preamble that is utilized to determine the timing of the burst. The clock and data recovery device determines the timing of a burst of data using signals from one or more demultiplexers or samplers. At the start of each burst of data, sampled input signals are analyzed by an edge detector to determine a sample phase for the burst. A selector utilizes the sample phase determined by the edge detector to choose which of the sampled input signals to use to produce output data signals from the clock and data recovery device.

Abstract: A neighbor cell list optimizing system according to the present invention is a neighbor cell list optimizing system that updates a neighbor cell list that is provided in a base station that manages a cell to which a mobile terminal establishes a connection and to which specific neighbor cells that are candidates of a handover destination cell for said mobile terminal of neighbor cells that are in the vicinity of said cell are registered, comprising: priority computation section that computes priorities of said neighbor cells to be registered to said neighbor cell list based on measurement information that represents radio communication qualities of neighbor cells in which the measured radio communication qualities exceed a threshold; and neighbor cell list updating section that registers neighbor cells in descending order of the priorities up to an upper limit of radio cells that can be registered to said neighbor cell list.

Abstract: A node may include a receiver configured to receive signals transmitted from a gateway and a logic device coupled to the receiver. The node may also include a memory configured to store label information identifying a data packet stored in the node. The logic device may be configured to receive a message from the gateway, where the message includes label information, and access the memory to identify a data packet based on the label information included in the message. The node may also include a transmitter configured to transmit the data packet to the gateway over a channel shared with a number of other nodes.

Abstract: A source synchronous signal synchronization system includes a differential signal receiver; a tunable input delay element coupled to the receiver; an input serializer/deserializer (ISerDes) coupled to the tunable input delay; an alignment unit coupled to the ISerDes; and a delay control unit coupled to the tunable input delay, the ISerDes, and the alignment unit.

Abstract: The present invention relates a method for implementing a business of communication service level based on a user request.

Abstract: A method and system is disclosed for enhanced Simultaneous Hybrid Dual Receive operation. A hybrid access terminal engaged in an IS-856 data communication in a hybrid IS-2000/IS-856 wireless communication system will use its high-gain antenna to conduct IS-2000 tuneaway scans when the access terminal determines that the IS-2000 signal received from its serving base station is below a level that can be reliably detected by its low-gain antenna. At the same time, the access terminal will continue to use its low-gain antenna to engage in the ongoing IS-856 communication, thereby avoiding interruption of the IS-856 communication by IS-2000 tuneaway scans, even when RF conditions are sub-optimal. The access terminal may apply a DRC offset to its DRC request when using just its low-gain antenna for IS-856 communications.

Abstract: A communications system includes remote stations coupled to a central station by a network. The system includes the network, the central station establishes a list of information about available network resources and publishes the list for the remote station. The system includes the remote stations, which identify a set of said published resources needed to establish the connection, notify the central station about the identified resources, and seize the set of identified resources to thereby establish the connection. The central station updates the list of available resources to thereby reflect the seizing of the set, and communicates the updated list to the remote stations.

Abstract: The present invention relates to a method for performing a ranging operation according to the priority order in a mobile communication system using a BWA (Broadcast Wireless Access) scheme. The method according to the invention for performing a range operation by a subscriber terminal in a mobile communication system using the BWA (Broadcast Wireless Access) scheme comprises steps of: receiving backoff domains having the start and end values of the backoff corresponding to each ranging operation, the backoff domains being determined from a base station according to the priority order of the ranging operations between the base station and subscriber terminals; performing a ranging operation and, if it is determined that the step of performing the ranging operation fails, selecting backoff domains among the received backoff domains according to the priority order of the performed ranging operations; and, re-performing the ranging operation according to the selected backoff domains.

Abstract: The present invention is directed to a system and method for providing an interoperable communications system including a plurality of otherwise disjunct communication systems each including at least one communications device. The system includes a plurality of system interface controllers each coupled to one of the communication systems and a common network for connecting the communication system and associated communications devices to the common network. A controller is coupled to each of the system interface controllers. The system interface controller being operable in response to commands from an authorized controller wherein the connection between each of the communication systems and the common network is controlled by a controller associated with, and authorized to control each communication system.

Abstract: Systems and techniques are disclosed relating to communications. The systems and techniques include an input device, generating a time period in response to a broadcast channel selection from the input device, generating a request to register the broadcast channel if the time period ends before receiving a second broadcast channel selection, and transmitting the request to an access network. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims.

Abstract: A system and method for low-cost performance and compliance testing of local oscillators and transmitters for wireless RF applications. A preferred embodiment comprises observing a digital signal from within an RF circuit, manipulating the signal with digital signal processing techniques, and determining if the RF circuit passes a test based upon results from the manipulating. Since the signal is clocked at a much lower frequency than an RF output of the RF circuit and the manipulation is performed digitally, testing can be performed at different stages of the production cycle and expensive test equipment can be eliminated.

Abstract: A clock and data recovery device receives a serial data stream and produces recovered clock and data signals. The clock and data recovery device operates over a range of frequencies and without use an external reference clock. A first loop supplies a first clock signal to a second loop. The second loop modifies the first clock signal to produce the recovered clock signal and uses the recover clock signal to produce the recovered data signal. The first loop changes the frequency of the first clock signal based on frequency comparison and data transition density metrics.

Abstract: A wireless client station includes a signal strength module configured to estimate signal strengths of signals received from a plurality of access points, wherein each of the signals includes a transmit power level signal. A control module is configured to determine path losses for each of the plurality of access points in response to the signal strengths and the transmit power level signals. The control module is configured to associate with one of the plurality of access points having a lowest one of the path losses. The control module is configured to adjust a minimum transmit power level of the wireless client station in response to the lowest one of the path losses and a receiver sensitivity of the wireless client station.

Abstract: Methods and apparatus are provided for pseudo asynchronous testing of receive paths in serializer/deserializer (SerDes) devices. A SerDes device is tested by applying a source of serial data to a receive path of the SerDes device during a test mode. The receive path substantially aligns to incoming data using a bit clock. A phase is adjusted during the test mode of the bit clock relative to the source of serial data to evaluate the SerDes device. The source of serial data may be, for example, a reference clock used by a phase locked loop to generate the bit clock. The phase of the bit clock can be directly controlled during the test mode, for example, by a test phase control signal, such as a plurality of interpolation codes that are applied to an interpolator that alters a phase of the bit clock.

Abstract: An apparatus for transferring data in a non-spread domain to a spread domain. The apparatus comprises a first-in-first-out (FIFO) memory; a write pointer generator adapted to generate a write pointer for writing data into the FIFO memory in response to a non-spread clock signal; a spread-clock generator adapted to generate a spread clock signal based on the non-spread clock signal; a read pointer generator adapted to generate a read pointer for reading data from the FIFO memory in response to the spread clock signal; and a controller adapted to control the spread-clock generator in response to the read and write pointers indicating predetermined potential data overflow or underflow of the FIFO memory.

Abstract: Certain embodiments of the present disclosure relate to a method for tracking of a carrier frequency offset. A soft combined frequency tracking discriminator is proposed as a part of the closed loop structure that can provide fast tracking of the frequency offset in an initial pull-in mode, and can also track small residual frequency variance in a fine-tracking mode.

Abstract: A system and method for pausing communications from a transmitting radio for a certain period of time in order to allow transmission of other messages. When a first radio determines that a message needs to be transmitted either to a second radio or the transmitting radio, the first radio determines whether there are any available forward channels to transmit the call. If no forward channel is available, the first radio determines a period of time required to transmit the message and sends, on a reverse channel, a “request to pause” signal to the transmitting radio identifying that period of time. Upon receiving the “request to pause” signal, the transmitting radio ceases transmission on the forward channel for the specified period of time, during which time the first radio transmits the message.

Abstract: A receiving method and apparatus for increasing coherent integration length while receiving a positioning signal from transmitters such as GPS satellites. In order to compensate for frequency drifts that may occur in the positioning signal, a hypothesis is made as to the frequency drift, which is inserted into the receiving algorithm. Advantageously, the length of coherent integration can be increased at the expense of reducing the length of incoherent integration while keeping the total integration length the same, the net effect of which is an increase in signal detection sensitivity. The frequency drift hypothesis has any appropriate waveform; for example, approximately linear or exponential.

Abstract: Methods and computer-readable mediums for processing push-to-talk voice messages are provided. According to one method, a first mobile station receives a push-to-talk voice message from a second mobile station, determines that a data object is attached to the push-to-talk voice message, determines a type of the data object, and stores the data object in a PTT attachment queue of the first mobile station, based upon the determined type of the data object, which may be a picture, video data, audio data, e-mail, document, contact, or the like.

Abstract: A method for transmitting radio resources in a mobile communication system is disclosed. The method includes receiving a random access channel (RACH) preamble from a plurality of UEs and transmitting response information associated with the received preambles over a common channel wherein the plurality UEs can access the common channel and receive corresponding information. If a HARQ scheme is used when a UE transmits data to the eNode-B using uplink radio resources allocated over the RACH, the eNode-B does not pre-allocate uplink radio resources required for re-transmission and performs allocation of radio resources for a first transmission of HARQ. If the re-transmission is required, the eNode-B allocates the radio resources required for the re-transmission with the NACK signal. If re-transmission is not required, the present invention can reduce an amount of wasted radio resources.

Abstract: A communication terminal includes first and second transmitters, which are coupled to produce respective first and second Radio Frequency (RF) signals that are phase-shifted with respect to one another by a beamforming phase offset, and to transmit the RF signals toward a remote communication terminal. The terminal includes a reception subsystem including first and second receivers and a phase correction unit. The first and second receivers are respectively coupled to receive third and fourth RF signals from the remote communication terminal. The phase correction unit is coupled to produce, responsively to the third and fourth RF signals, a phase correction for correcting an error component in the beamforming phase offset.

Abstract: A differential transmitter and an auto-adjustment method of data strobe thereof are provided. The differential transmitter includes a phase-detecting unit, a switching unit, a rising edge strobe unit, and a falling edge strobe unit. The phase-detecting unit detects a phase relation between a clock signal and a data signal to outputs a detection result. The rising edge strobe unit latches the data signal at a rising edge of the clock signal, and converts a latching result to a first differential output signal. The falling-edge-strobe unit latches the data signal at a falling edge of the clock signal, and converts a latching result to a second differential output signal. The switching unit determines whether to switch the clock signal and data signal to the rising edge strobe unit or to the falling edge strobe unit according to the detection result.