2244results about "Code division multiplex" patented technology

A proximity measuring apparatus (70) comprises an interrogator (80) for generating an interrogation signal encoded with a reference signature code comprising concatenated codes and emitting it as interrogating radiation. It also incorporates a transponder (90) for receiving the interrogating radiation, demodulating it to extract its signature code and then remodulating it after a delay period to provide a signal for reemission as return radiation therefrom. The interrogator (80) receives return radiation at its antenna (260) and demodulates it to extract its signature code and then correlates the code with the reference code to determine mutual correlation thereof. The interrogator (80) incorporates a computer (290) for controlling a scan direction of the antenna (260) and for measuring time delay between emission of the interrogating radiation therefrom and receipt of corresponding return radiation. The computer (290) computes distance and relative bearing of a transponder (90) providing the return radiation from the scan direction and the time delay. The apparatus (70) may be used for improving road vehicle safety.

A system and method for initializing a system communication without previous reservations for random access channel (RACH) access includes a first step of defining at least one spread sequence derived from at least one constant amplitude zero autocorrelation sequence. A next step includes combining the spread sequence with a Walsh code to form an extended spread sequence. A next step includes using the extended spread sequence in a preamble for a RACH. A next step includes sending the preamble to a BTS for acquisition. A next step includes monitoring for a positive acquisition indicator from the BTS. A next step includes scheduling the sending of a RACH message. A next step includes sending the RACH message.

In a method for transmitting a contention free scheduling request in a cellular network, a set of N frequency opportunities is defined within a scheduling request slot. A set of R CAZAC root sequences is then defined per frequency opportunity. A set of C cyclic shifts is then defined per CAZAC root sequence. Within a given cell, a unique identification number is assigned to each user equipment (UE) that is in an uplink (UL) synchronized state. Each UL synchronized UE is mapped to a unique combination of one of the N frequency opportunities, one of the R CAZAC root sequences and one of the C cyclic shifts. A cyclic shifted preamble sequence for a given UE is transmitted as a scheduling request on the mapped frequency, CAZAC root sequence and cyclic shift opportunity, wherein the unique identification number of the given UE is encoded by the combination of the frequency opportunity, CAZAC root sequence opportunity, and amount of cyclic shift, such that up to all of the plurality of UE can transmit a schedule request (SR) in a non-contentious manner in one schedule request slot.

The present invention provides a method for realizing transmission of multiprotocol client signals in a distributed base station subsystem, comprising: encapsulating client signals by a GFP-T frame; and mapping said GFP-T frame into a lower-layer transmission link to realize the transmission of client signals. Said lower-layer transmission link is a common public radio interface CPRI link. Said client signals are one of the following: baseband I/Q signals of WCDMA supported by CPRI protocol, baseband I/Q signals of radio interface protocols other than WCDMA, structured signals of E1/T1, STM-1 and other constant-rate links, structured variable-rate link signals such as Ethernet MAC frame signals, PPP/HDLC frame signals, etc. This method is also applicable to other types of synchronous transmission links between a remote radio unit and a primary baseband processing unit, e.g., the links as specified by OBSAI (Open Base Station Architecture Initiative).

Techniques are provided to support fast frequency hopping with a code division multiplexed (CDM) pilot in a multi-carrier communication system (e.g., an OFDMA system). Each transmitter (e.g., each terminal) in the system transmits a wideband pilot on all subbands to allow a receiver (e.g., a base station) to estimate the entire channel response at the same time. The wideband pilot for each transmitter may be generated using direct sequence spread spectrum processing and based on a pseudo-random number (PN) code assigned to that transmitter. This allows the receiver to individually identify and recover multiple wideband pilots transmitted concurrently by multiple transmitters. For a time division multiplexed (TDM)/CDM pilot transmission scheme, each transmitter transmits the wideband pilot in bursts. For a continuous CDM pilot transmission scheme, each transmitter continuously transmits the wideband pilot, albeit at a low transmit power level. Any frequency hopping rate may be supported without impacting pilot overhead.

The invention provides a mechanism for automatically setting reverse link gain or power for a repeater (120) used in a communication system (100) through the use of the reverse link power control of a built-in wireless communications device. By embedding a wireless communication device (430, 630, 700) inside the repeater and injecting reverse link signals of the embedded device into the reverse link of the repeater (124A, 124B), the gain of the repeater is maintained relatively constant. The embedded WCD can also be activated on a periodic basis to make calls and utilize reverse link power-control to calibrate or re-calibrate the gain of the repeater, making it a power-controlled repeater.

A method and apparatus of transmitting a reference signal in a wireless communication system is provided. The method includes generating a precoded reference signal or a non-precoded reference signal in accordance with a rank, and transmitting the generated reference signal. Uplink transmission using multiple transmit antennas is supported through reference signal design and related control signaling.

Techniques to support independent power control of multiple channels in CDMA systems (e.g., a W-CDMA system) that define a single power control feedback stream on the uplink, which is to be used for downlink power control. In one aspect, the single feedback stream is "time shared" among multiple channels requiring individual power control. Various time-sharing schemes may be used to implement multiple (substantially parallel) feedback substreams based on the single feedback stream, and different combination of feedback rates may also be achieved for the substreams. Each feedback substream may be assigned to, and used for power control of, a respective channel. In another aspect, multiple feedback substreams are implemented based on multiple fields in newly defined slot formats.

A WCDMA system includes a Base Station (BS) transmitter, or forward transmitter and a pilot channel that transmits control signals between the BS and a Mobile Station (MS) to reconfigure their transmitter/receiver. Reconfiguration is performed according to the prediction of the channel attenuation and the threshold set at the BS or MS based on its channel power probability density function separated into three distinct equal probable regions. In one embodiment, Seamless Rate Change (SRC)/Transmitter Power Control (TPC) logic uses the predicted channel attenuation to signal both the transmitter and the receiver in a channel to reconfigure their transmit power level according to the power density function (pdf) of the channel power and threshold level. A transmission rate is reduced when the power level is below the threshold and increased when the channel power is above threshold. The pilot channel is used to signal the mobile station and the base station.

A radio network controller (RNC) transmits a power offset for controlling transmission power of an uplink high-speed dedicated physical control channel (HS-DPCCH) when a user equipment (UE) enters a handover region, in a mobile communication system including the RNC, a Node B connected to the RNC, and the UE located in one of at least two cell areas occupied by the Node B. The Node B transmits data to the UE over a high-speed downlink shared channel (HS-DSCH) and the UE transmits information indicating reception of the data to the Node B over the uplink HS-DPCCH. The RNC informs the UE of a power offset for determining a transmission power increment of the uplink HS-DPCCH, if it is determined that the UE is located in the handover region. The RNC informs the Node B of the power offset so that the Node B can determine a threshold value for determining information indicating reception of the data, depending on the power offset.

A method and an apparatus for data transmission in a mobile telecommunication system supporting an enhanced uplink service are provided. A Transport Format Combination (TFC) selector determines TF information for data to be transmitted through a first data channel not supporting Hybrid Automatic Repeat reQuest (HARQ) and a second data channel supporting HARQ, and determines gain factors for the first and second data channel, and first and second control channel carrying control information for the first and second data channel. The gain factors are input to a physical channel transmission controller, and the physical channel transmission controller reduces the gain factor for the second channel if total transmit power required for transmission of the channels exceeds the predetermined maximum allowed power. A gain scaler adjusts transmit powers of the channels using the scaled gain factor and gain factors for the first data channel, the first control channel and the second control channel.

Embodiments of the present invention include one or more wireless transmitting devices and an array of receiver units for receiving wireless communications from the transmitting devices. The transmitter devices and receiver units can be arranged in one, two or three dimensional configurations. Signals are transmitted from the devices for identification and accurate location determination. Spread spectrum techniques can be used, such as DSSS, FHSS, THSS, and pseudo-noise (PN) coding schemes, or combinations thereof. The transmitting devices can generate one or a plurality of data signals that are orthogonal-code modulated, to be decoded by the receiver units and a processor associated therewith. A plurality of transmitter signals can be received, identified, located, and data demodulated substantially simultaneously using embodiments of the invention. The combined use of array processing methods and diversity schemes can be used to reduce the effects of signal multi-path and occlusion.

An efficient communications apparatus is described for a vector signaling code to transport data and optionally a clocking signal between integrated circuit devices. Methods of designing such apparatus and their associated codes based on a new metric herein called the “ISI Ratio” are described which permit higher communications speed, lower system power consumption, and reduced implementation complexity.

A hierarchical cell structure (HCS) cellular communications system includes a macro cell encompassing a smaller micro cell that employ the same frequency band. The macro cell includes a macro cell base station, and the micro cell includes a micro cell base station. An uplink communication cell boundary between the macro cell and the micro cell is established, and a downlink communication cell boundary between the macro cell and the micro cell is established. A radio network controller determines whether a condition exists in the HCS system which indicates that the uplink and downlink micro cell boundaries should be unbalanced. If the condition is met or exists, the power and/or antenna beam tilt of a downlink transmission from the micro cell base station is reduced to unbalance the uplink and downlink micro cell boundaries. Alternatively, the radio network controller may employ an offset value to mathematically reduce mobile detected pilot power levels associated with the micro base station.

Methods and apparatus for supporting and using multiple communications channels corresponding to different transmit technologies and/or access technologies in parallel within a cell of a wireless communications system are described. Mobile nodes support multiple technologies and can switch between the technology being used at a particular point in time, e.g., from a first channel corresponding to a first technology to a second channel corresponding to a different technology which provides better transmission characteristics, e.g., a better perceived channel quality. Mobiles maintain at least two sets of channel quality information at any one point in time. Mobiles select the better channel and communicate the channel selection to the base station or communicate channel quality information for multiple channels to the basestation and allow the base station to select the channel corresponding to the technology providing the better conditions for the mobile. Different mobiles in the same cell may support different technologies.

Low-cost intelligent control and communication devices are arranged to communicate with one another over one or more shared physical media, such as a powerline or a radio frequency band. No network controller is needed, because any device can act as a master, slave, or repeater. Adding more devices makes the system more robust, by virtue of a simple protocol for communication retransmissions and retries.

In an adaptive modulation and coding method one or more adjustable values are created (S1), each corresponding to at least one of a plurality of available modulation and coding levels applicable to a signal transmitted from a transmitter to a receiver, and each representing a change to the level(s) to which it corresponds. One or more of said adjustable values is/are adjusted in dependence upon whether or not the signal is received successfully by the receiver (S2-S5). One of said available modulation and coding levels is selected (S6-S8) to apply to the signal based on such an adjustable value. Such a method can enable the appropriate modulation and coding level to be selected even when the path and channel conditions vary. The method is applicable to selecting modulation and coding levels in a high-speed downlink packet access system of a wireless communication network.

An adaptive transmission scheme provides multiple levels of adaptation. At a first level, a selection is made between a limited feedback or open loop scheme and a rich feedback or closed loop scheme. At a second level of adaptation, a diversity mode is selected. Additional levels of adaptation could be employed.

Obtaining channel quality information in a wireless communication network is described. A base station allocates a resource to remote stations in order to receive channel quality information back from remote stations. The resource allocated to a remote station contains no higher layer data. A scheduler in the base station uses the channel quality information in order to schedule remote stations and/or to decide on the channel coding and/or modulation to be applied to the data transmission. A mechanism is provided to ensure that data transmitted on HS-DSCH is not transmitted to higher layers. This may provide a convenient method of obtaining channel quality information allowing for improved scheduling and thus improved performance of the communication system.

A multistage interference canceller and method for removing interference between users and multipath interference from received signals in multiple stages includes a plurality of despreading units which produce a received symbol vector and an estimated channel value, a synthesis unit which synthesizes the received symbol vector, an amplitude of the received symbol vector and the amplitude of the estimated value from each reverse spreading unit, and a decision unit which executes a hard decision and a soft decision according to a result of comparing the total amplitude of the received symbol vector and the total amplitude of the estimated channel value.

A method is disclosed that a Mobile Station MS performs at switch-on to search the most favorable target cell in UMTS systems like the 3GPP CDMA—LCR (Low Chip Rate) option at 1.28 Mcps—TDD (Time Division Duplex) mode and the equivalent TD-SCDMA (Time Division—Synchronous CDMA). Signal at the MS antenna is the sum of different RF downlink frames coming from different carriers in the assigned frequency ranges. A DL synchronization timeslot and a BCCH TS0 are both transmitted with full power in the frames, the first one includes one out of 32 SYNC codes assigned on cell basis. Following a conventional approach the absence of a common downlink pilot and without prior knowledge of the used frequencies would force the MS, for all the frequencies of the channel raster stored in the SIM card, the correlation of the received frame with all the 32 SYNCs stored in the MS, in order to detect the BSIC of a cell to which associate the power measures. Following the two-step method of the invention the power measures are performed in two-step scan of the PLMN band without interleaved correlation steps; once a final frequency is selected the respective frame is the only correlated one. At least one frame duration about 5 ms long of the whole 15 MHz bandwidth is acquired, IF converted, A/D converted and the digital set is stored. A rough scan is performed multiplying the digital set by a digital IF tuned in steps wide as the channel band (1.6 MHz) along the 15 MHz band, and filtering the baseband signal with a Root Raise Cosine low-pass filter. The 5 ms baseband signal is subdivided into 15 blocks of half timeslot (337.5 μs) and the power of each block is measured. The power of the strongest block indicates the priority of the respective frequency. The strongest power values are put in a Spectral Table together with respective frame load indicators. The load indicator is the percentage of timeslots in a frame almost equally loaded as the strongest block. The three strongest frequencies are selected for the successive scan. The second step search is performed like the first one but the IF steps are now 200 kHz wide and cover the only 1.6 MHz spectrum around a selected frequency. A final frequency is selected for the successive correlation step. Then the frequency error of the MS reference oscillator is corrected with data-aided techniques and a calibration value stored for successive connections (FIG. 9).

In an embodiment of the method, uplink reference signals are assigned to users in a group of cells. For example, a first constant amplitude sequence having low cyclic cross correlation is assigned to each user in a first cell of the group of cells. Here, each user is assigned the first sequence. Also, simultaneously transmitting users in the first cell are assigned to different sub-carriers. A second constant amplitude sequence having low cyclic cross correlation is assigned to each user in a second cell of the group of cells. Here, each user in the second cell is assigned the second sequence. The first sequence and the second sequence are different sequences, and the first cell and the second cell are adjacent. Also, simultaneously transmitting users in the second cell are assigned to different sub-carriers. The sub-carriers to which the simultaneously transmitting users of the second cell are assigned overlap in frequency with the sub-carriers to which the simultaneously transmitting users of the first cell are assigned.

Access to a wireless communication system (100) by a subscriber station (101-103) is facilitated by selecting (705) an access sequence from a set of sequences that have been identified to have a low average of peak-to-average-power-ratios of access signals generated by the set of sequences and also based on a good cross-correlation of the access signals; forming (714) the access waveform by generating an access signal using the access sequence and appending in the time domain a cyclic prefix to the access signal; and transmitting (715) the access waveform. In some implementations, the access waveform is cyclically shifted (820) before the cyclic prefix is appended, and in some implementations, the signal is transmitted (710, 810) in a randomly selected sub-band of an access interval.

A method for broadcasting channel information, available channel and data rate of a base station in a CDMA communication system. The base station receives information indicating that a mobile station has data to transmit, over an access preamble channel. The base station transmits use status information of physical channels and maximum available data rate information on a status indicator channel. The mobile station receives the use status information of physical channels and the maximum available data rate information through the status indicator channel from a base station. The mobile station transmits to the base station an access preamble for requesting allocation of a given physical channel determined depending on the use status information and the maximum available data rate information.

Several mobile station identifiers are allocated to one mobile station, one for each of a plurality of possible signalling channel structures, parameters, or both. When receiving the signalling channels, the mobile station searches for all identifiers allocated for it in the received signalling channels. When it finds one that matches, it may for instance check a mapping table (agreed at the connection setup between mobile station and the network by RRC signalling) to determine what this identifier means. The signalling channel structure, parameters, or both, used in the transmission may be implicitly or explicitly indicated by the identifier. The mobile station (User Equipment) should monitor the signalling channels in the normal way. Instead of looking for only one identifier, however, the mobile station should monitor several identifiers belonging to it.

A signaling method between a MAC (Medium Access Control) layer entity of a transmission apparatus and a MAC layer entity of a reception apparatus in a packet communication system including the transmission apparatus and the reception apparatus wherein upon receiving a signaling request, the MAC layer entity of the transmission apparatus transmits a MAC signaling message including control information and a signaling indication indicating transmission of the control information and the MAC layer entity of the reception apparatus determines whether the MAC signaling message includes the signaling indication, and receives the control information included in the MAC signaling message, if the MAC signaling message includes the signaling indication.

A method, system and apparatus for setting a transmit power control level in a wireless communication system. Aspects of both open loop and closed loop transmit power control schemes are used to determine a transmit power level. A method includes measuring a power level of a received signal, receiving a transmit power control (TPC) command, and calculating a transmit power level based on the power level of the received signal and the TPC command.

An impulse radio communications system using one or more subcarriers to communicate information from an impulse radio transmitter to an impulse radio receiver. The impulse radio communication system is an ultrawide-band time domain system. The use of subcarriers provides impulse radio transmissions added channelization, smoothing and fidelity. Subcarriers of different frequencies or waveforms can be used to add channelization of impulse radio signals. Thus, an impulse radio link can communicate many independent channels simultaneously by employing different subcarriers for each channel. The impulse radio uses modulated subcarrier(s) for time positioning a periodic timing signal or a coded timing signal. Alternatively, the coded timing signal can be summed or mixed with the modulated subcarrier(s) and the resultant signal is used to time modulate the periodic timing signal. Direct digital modulation of data is another form of subcarrier modulation for impulse radio signals. Direct digital modulation can be used alone to time modulate the periodic timing signal or the direct digitally modulated the periodic timing signal can be further modulated with one or more modulated subcarrier signals. Linearization of a time modulator permits the impulse radio transmitter and receiver to generate time delays having the necessary accuracy for impulse radio communications.

A cellular radio system in which a base station receiver can receive, on the reverse link, data from a mobile terminal in one of four control modes. In the first mode, the mobile terminal sends an independent user pilot, not synchronized with the base station, on the reverse link and the user data channel is synchronized to this independent user pilot. In the second mode, the mobile terminal slaves its user pilot to the pilot it receives from the base station and the user data channel is synchronized with this slaved user pilot. This second mode allows the user terminal to receive round trip delay information for purposes of geolocation and rapid reacquisition. In the third mode, the mobile terminal slaves its user pilot to the incoming base station pilot, as in the case of mode two, but the user data channel operates in the orthogonal mode using the ranging information received from the base station. The phase relationship between the user pilot channel and the user data channel is calibrated. The user pilot carrier is also the carrier for the user data channel and can be used as the carrier reference for detecting the user data channel. In the fourth mode, the slaved pilot implementation of mode three is used for acquisition but, after acquisition, the user pilot code is phase shifted to be synchronous with the user data channel, thus also making it an orthogonal channel. In this mode, the pilots no longer contribute interference to the user data channels, within the cell, and can be transmitted at higher power levels.

A power calculating and amplitude limitation judging portion 13 calculates the power value x of the digital quadrature baseband signal I, Q from a transmission data generator 1, and compares the power value x with a power threshold value y set by a threshold value setting portion 14 to judge whether amplitude limitation is needed or not. An amplitude maximum limiting portion 12 subjects the quadrature baseband signal from the transmission data generator 1 to the amplitude maximum value limitation based on the judgment result in the power calculating and amplitude limitation judging portion 13. Thereafter, the digital quadrature baseband signal which has been subjected to the amplitude maximum value limitation by the amplitude maximum value limiting portion 12 is subjected to the distortion compensation using complex multiplication based on the distortion compensation data by a non-linear distortion compensation calculator 2.