2048 results about "Frame synchronization" patented technology

In an OFDMA-based cellular system, a frame of a downlink signal includes a common slot and traffic slots. The common slot includes a synchronization preamble and a cell search preamble. The synchronization preamble has a structure for synchronizing time and frequency, and the cell search preamble has a cell search structure. The traffic slot includes pilot symbols provided on the time and frequency axes. A cyclic prefix is used to estimate initial symbol synchronization, and the initial symbol synchronization and the synchronization preamble are used to synchronize the frame. The synchronization frame and the cell search preamble are used to estimate time and frequency synchronization. The cell search preamble is used to search cells. When the initial synchronization is performed, the cyclic prefix is used to track the frequency, the synchronization preamble is used to track symbol synchronization, and the cell search preamble is used to track fine frequency synchronization.

The frame words of the preferred embodiment are especially suitable for frame synchronization and/or channel estimation. By adding the autocorrelation and cross-correlation functions of frame words, double maximum values equal in magnitude and opposite polarity at zero and middle shifts are obtained. This property can be used to slot-by-slot, double-check frame synchronization timing, single frame synchronization and/or channel estimation and allows reduction of the synchronization search time. Further, the present invention allows a simpler construction of a correlator circuit for a receiver. A frame synchronization apparatus and method using an optimal pilot pattern is used in a wide band code division multiple Access (W-CDMA) next generation mobile communication system. This method includes the steps of storing column sequences demodulated and inputted by slots, in a frame unit, in detecting frame synchronization for upward and downward link channels; converting the stored column sequences according to a pattern characteristic related to each sequence by using the pattern characteristic obtained from the relation between the column sequences; adding the converted column sequences by slots; and performing a correlation process of the added result to a previously designated code column.

A method for coexistence radio communication systems is presented. In one embodiment, the method includes receiving a realtime frame synchronization signal and receiving one or more frame parameters. The method further includes determining, based at least on the frame synchronization signal and the frame parameters, estimated frame timing information and scheduling transmission based on the estimated frame timing information to avoid collision of the transmission and reception.

A method and apparatus for transmitting a preamble for frame synchronization and channel estimation in a MIMO-OFDM communication system are provided. An OFDM communication system using Q transmit antennas generates a base preamble sequence including a CP and an orthogonal sequence. If Q≦a predetermined number M, a preamble sequence for a kth antenna is S(t−(k−1)T/Q). If Q>M and k≦M, the preamble sequence transmitted for the kth antenna is S(t−(k−1)T/Q). If Q>M and k>M, the preamble sequence for the kth antenna is (−1)^(ps−1)S(t−(k−1)T/Q). Here, S(t) is the orthogonal sequence, T is the period of the orthogonal sequence, and PS is an index indicating a transmission period of the preamble sequence. The preamble sequences are at least twice transmitted from the Q transmit antennas.

An apparatus and a method for overlaying parts of a displayed presentation of a video by using graphic content rendered by a receiving device such as a set top box or television to complete a displayed presentation of the video. The apparatus receiving frame synchronizing information from a content provider and then conveying the frame synchronizing information as a graphic overlay to the video. The frame synchronizing information comprises frame starting identifier data, frame ending identifier and positional information for describing frame locations and frame timing for overlaying the graphic content and positional information to indicate were to place the graphic content to be overlaid. The frame synchronizing information provides the information necessary to place graphic content, such as a graphic image or graphic animation, at specified positions that are synchronized to the displayed presentation. The same method also enables audio information to be synchronized. The graphic content supplied may include a block of pixel data, an image, an animation or an audio clip.

The invention provides a reference signal configuring method and system, an apparatus with a base station function, a reference signal receiving method, a reference signal receiving system, and a terminal. The reference signal configuring method comprises: setting at least one discovery reference signal (DRS) in DMTC (DRS measurement timing configuration); configuring a sending parameter for the at least one DRS; and sending the sending parameter to a terminal served by the apparatus with a base station function in order that the terminal receives the at least one DRS according to the sending parameter. The reference signal configuring method may reduce DRS detection complexity for UE while increasing DRS sending probability in order to enable the terminal to accurately receive the DRS and achieve frame synchronization and subframe synchronization.

The invention discloses a continuous variable quantum key distribution system and a synchronous realization method thereof. The continuous quantum key distribution system consists of a light path part and a circuit control part, wherein the light path part mainly consists of a laser, an attenuator, a beam splitter, a polarization controller, am amplitude controller, a phase controller and a coupler. A control part is a transmission end controller module and consists of a true random key generator, an analog voltage output and a trigger clock output. The synchronous method comprises a bit synchronizing step and a frame synchronizing step. The invention provides a completely novel synchronous realization scheme based on properties of continuous variable quantum in an optical fiber, the practical orientation of the continuous variable quantum key distribution system is promoted, and the interference that the continuous variable quantum on the synchronous realization in the optical communication process also can be effectively overcome.

The frame synchronizing circuit establishes frame synchronization by detecting a sync pattern laid in an incoming frame. The frame synchronization circuit comprises a first frame synchronizing unit and a second frame synchronizing unit. The first and second synchronizing units synchronize with a first pattern, a second pattern at a first position and a second position, respectively. Thereafter, when the first position used for the synchronization by the first frame synchronizing unit is found to be in error, the first frame synchronizing unit synchronizes with the second pattern at the second position used by the second frame synchronization unit.

An apparatus for performing initial synchronization and frame synchronization in a mobile communications system and method thereof are disclosed. First of all, a method and apparatus for performing frame synchronization in a mobile communications system using a correlation value between a received signal and a reference vector for a phase according to one embodiment of the present invention are disclosed. Secondly, a method and apparatus for performing frame synchronization by considering all phase modulation possibility and frequency offsets according to another embodiment of the present invention are disclosed. Thirdly, a method and apparatus for performing initial estimation in a manner of dividing at least one subframe received from a base station by a UE in the course of cell search into at least two areas, calculating a correlation for each of the at least two areas and using a maximum value of the calculated correlation value per area are disclosed.

The invention requests to protect a time synchronization method applicable to a wireless sensor network and relates to a wireless network communication technology. The time synchronization method comprises the steps: time source equipment generates beacon frames and broadcasts and sends the beacon frames periodically; non-time source equipment obtains time stamps in the transmitting and receiving process of the beacon frames, obtains frequency deviation and time deviation of an equipment clock and a time source equipment clock according to calculation of a plurality of collected time stamps, compensates a local clock and realizes synchronization with a time source; and time synchronization is carried out step by step, and finally the time synchronization of the whole network is realized. Considering the application environment of the equipment and different requirements for time synchronization, a multi-stage and multilevel synchronization mechanism for combining broadcast synchronization, matching synchronization and monitoring synchronization is adopted. The non-time source equipment can apply synchronization of time synchronization command frames according to different requirements, the equipment without applying the time synchronization command frames can monitor and receive the time synchronization command frames similarly and finish synchronization, so that the whole communication overhead and energy consumption of the network are reduced and the normal operation of the network is guaranteed.

A radio communication apparatus includes a receiving section, a power supply section and a control section. The receiving section receives a radio signal when electric power is supplied, and the radio signal has a preamble field for storing a preamble pattern. The power supply section supplies the electrical power to the receiving section and stopping the supply of the electrical power in response to a supply stop signal. The control section generates the supply stop signal when presence of the preamble pattern can not be detected from the radio signal received by the receiving section, in a state in which a frame synchronization is established.

Intercell handover method in UMTS mobile systems in TDMA-SCDMA technique (and also FDMS-SDMA) with full duplexing of the TDD type. The complexity of the technique adopted requires a frame synchronization mechanism employing a downlink pilot signal, broadcasting transmitted by the base station, echoed by signature sequences transmitted by the single Mobile units in the procedures foreseeing an uplink access. The above, together with the high cipher speed (1.28 Mchip) imposed by the CDMA technique, makes inappropriate the addition of other fields to the sequence of the downlink pilot, which shall remain a pure synchronization sequence. Contrarily to the GSM, a field is missing in the synchronism burst for the transport of the system frame number FSN, absolutely necessary for the iperframe synchronism and the starting of ciphering on the channel. The information on SFN is included in the common signalling channel as other broadcasting information.

A system and method are provided for determining a position of a Global Positioning System (GPS) receiver prior to bit and frame synchronization. As such, the time-to-first-fix is substantially reduced. More specifically, pseudoranges to five GPS satellites are measured by correlating locally generated Pseudo-Random Number (PRN) codes with signals received from the GPS satellites. After correlation, the pseudorange measurements are correct with an unknown integer number of milliseconds error, which is different for each of the pseudorange measurements. Using the measurements of the pseudoranges and a mathematical model where each of the pseudorange measurements is forced to have a common channel time error, the user position and the common channel time error are determined prior to bit and frame synchronization.

A coherent optical receiver for a data-frame format in which a data frame has two or more pilot-symbol blocks, each having a cyclic prefix or suffix, and one or more payload-symbol blocks, each of which is concatenated with at least one adjacent block without a guard interval between them. The receiver uses optical signals corresponding to the pilot-symbol blocks to perform data-frame synchronization, frequency-offset correction, and channel-estimation procedures, which are robust even in the presence of certain transmission impairments. The receiver applies block-overlap processing with a sliding window to recover the payload data in a manner that substantially cancels the adverse effects of inter-block interference caused by the absence of guard intervals in the payload portion of the data frame. In one embodiment, the receiver performs channel-estimation and block-overlap processing for polarization-division-multiplexed signals in a manner that enables a combined, intertwined application of channel-response-compensation and polarization-demultiplexing procedures.

A mobile terminal identifies a cell boundary of a mobile communication network supporting an asynchronous scheme for handover between different communication systems. For this, a boundary indication base station newly defines boundary indication codewords distinguished from existing codewords used for acquisition of frame synchronization, and transmits one of the boundary indication codewords over a secondary synchronization channel every frame. Upon receiving the boundary indication codeword over the secondary synchronization channel, the mobile terminal recognizes that it is located in a boundary of the mobile communication network supporting the asynchronous scheme, and performs handover to a mobile communication network supporting a synchronization scheme.

A timing error compensation system in an OFMD/CDMA communication system includes an analog-to-digital converter for converting an OFDM signal, comprised of a data symbol stream in which a pilot symbol is inserted at intervals of a prescribed number of data symbols, received from a transmitter, to a digital OFDM symbol stream by prescribed sampling synchronization, a guard interval remover for removing a guard interval inserted in the OFDM symbol by prescribed frame synchronization, and a fast Fourier transform (FFT) device for performing fast Fourier transform on the guard interval-removed OFDM symbol and outputting a data symbol stream. In the time error compensation system, a pilot symbol detector receives the data symbol stream and detects the pilot symbols inserted in the data symbol stream at prescribed intervals. A timing compensator determines a linear phase difference line for the detected pilot symbol, generates a timing error estimation signal according to the determined linear phase difference line, and provides the timing error estimation signal to the analog-to-digital converter and the guard interval remover so as to determine the sampling synchronization and the frame synchronization.

When one video image (e.g., second video image) is blended or synthesized to video image (e.g., main video image), time base correction is made between both video data. A video data processing apparatus comprising a first video generator generating a first video data having an arbitrary frame rate, a second video generator generating a second video data having an arbitrary frame rate different from the first video data, and a synchronization controller using video reproduction time managed by the first video generator as a reference time, and correcting video reproduction time of the second video generator shifted from the reference time by repeatedly using the second video data to obtain frame synchronization.

The invention provides a synchronized method of an orthogonal frequency division multiplexing (OFDM) system. The invention discloses an associated synchronized method of frame synchronization, carrier frequency synchronization and sampling clock synchronization. Carrier frequency offset estimation, channel estimation and fine estimation of symbol timing offset are performed again after sampling clock offset correction is finished, thereby avoiding influences of sampling clock offset on the carrier frequency offset estimation, the channel estimation and the fine estimation of the symbol timing offset, compensating phase deflection caused by the residual carrier frequency offset and the sampling clock offset simultaneously, greatly improving the synchronized performance, and meeting the demands of a high-order modulated system. In addition, due to aiming at a low time-varying channel, the channel estimation is required to be performed once only, thereby reliving the complexity of the system.