143 results about "Synchronous CDMA" patented technology

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).

The present invention provides an effective way to create a virtual MIMO transmission system using mobile terminals that have only one transmit path and antenna. This is accomplished by assigning mobile terminals to a group and assigning certain shared resources and user-specific resources to those mobile terminals in the group. In a synchronized fashion, the mobile terminals will provide uplink transmission in concert, as if they were a single entity having multiple transmission paths and antennas. Preferably, the shared resources bear on how the data is transmitted, and the user-specific resources relate to pilot signals. The data transmitted may be encoded in any number of ways, and in one embodiment, the mobile terminals may relay their information to each other, such that uplink transmissions can incorporate STTD decoding or other space-time codes. The invention is applicable to virtually any multiple access technology, including OFDM, TDMA, and CDMA, preferably synchronous CDMA.

A communications system employs the use of both synchronous CDMA and FDMA to provide a variable bandwidth waveform with multiple bonded transmitters and receivers that are agile in both frequency and PN code to permit a variable bandwidth and variable rate multiple access system. In a first aspect the teachings provide the use of both CDMA and FDMA together to enable an improved concentration efficiency by making a larger pool of bandwidth available to each user. In a second aspect these teachings enable channel bonding across both code space and frequency space, thus making the system capable of operating within a variable (not necessarily contiguous) bandwidth and at a finely variable rate.

A frequency calibration circuit for use in a spread spectrum receiver. The receiver includes circuitry for receiving a spread spectrum signal from a base station and for recovering a network clock signal therefrom, a low frequency oscillator for producing an oscillator clock signal, and a frequency comparator that takes as inputs the network clock signal and the oscillator clock signal and produces a calibration factor based on the difference between the clock signals. A controller coupled to the low frequency oscillator amd the frequency comparator utilizes the calibration factor together with the low frequency oscillator clock signal to output a accurate and precision timed signal thereby being able to accurately require the timing of the paging channel.

A method for automatically optimizing a neighbor list for processing handover in a synchronous CDMA (Code Division Multiple Access) network includes the steps of: collecting neighbor list data, call fault data, handover statistical data, base station location data and PN information data of each base station sector in a nationwide network; extracting all target sectors available for handover by analyzing the collected data; endowing a weighting factor to the extracted target sectors according to importance and then sorting the target sectors according to calculated results so as to determine priorities; and subsequently inputting the target sector information to the neighbor list according to the priorities.

Base on different types of service in each region of system, the method allows TD-SCDMA system configures different numbers of time slots for upward and downward services for the region smartly. The said method is only applied to adjacent sub zones in configuration area, where there are different numbers of time slots for upward and downward services. Based on link estimation of investigated user device, and result report for measured channel power of interference signal up or down link, network controller determines whether a time slot is assigned to the investigated user device in order to reduce mutual interference between adjacent sub zones with different service time slots being configured. The network controller also carries out periodic monitoring for switching number inside sub zone in the said two adjacent sub zones in order to overcome influence on channel allocation caused by time varying character of interference signal so as to optimize allocation and raise capacity.

The method and device for eliminating same frequency interference in parallel in TDS-CDMA system includes steps: based on matched filter or based on demodulation symbol generated from united detection to reconstruct interference signal of cell for each cell; superposing signals reconstructed from other interference cells; then removing superposed value of signal reconstructed from other interference cells from the received signal in order to eliminate influence on receiving signal of this cell by interference signals from adjacent cell, executing the steps repeatedly based on number of parallel stage. With lesser complexity of implementation, the method eliminates influence of signals from cells in same frequency to a considerable degree, especially, in malcondition that power of common frequency in adjacent cell is higher than this cell so as to raise performance for receiving signal of this signal.

A method for assigning codes in an uplink of a synchronous code division multiple access (CDMA) telecommunication system is disclosed. The method for assigning a code in a reverse channel of a synchronous wireless telecommunication system, comprising the steps of: a) at a mobile station, receiving time matching information of a scrambling code from a base station; b) at the mobile station, spreading data frame to be transmitted by an orthogonal code, thereby generating a spread data; and c) at the mobile station, multiplying the spread data by a scrambling code based on the time matching information of the scrambling code, thereby generating an encoded data.

It is a kind of Midamble code sequence detection method and apparatus for TD-SCDMA mobile communication system. It can reach high detection probability and low missing probability under the condition of low signal-to-noise ratio and the under the environment of having frequency diffusion and time diffusion. It can also generate rejection mark and exclude a batch of wrong input incident, such as wrong code set sequence number input, wrong synchronous Information input and local oscillator has large frequency deviation, so to realize the reduction of initializing community research time in TD-SCDMA system. This invention includes the module and steps such as Midamble receives signal sample extraction, Midamble code sequence generation, slide association, delay envelope calculation, multi-frame combination, path selection, similar value calculation, maximum value detection, confidence level calculation and compare, the generation of detection rejection mark, and generation of detection Midamble code sequence number.

The apparatus comprises: a data exchanging interface used for intercommunication with external data; a FPGA module used for analyzing and giving out the received data, for packaging and giving out the transmitted data and for control the clock signal of the apparatus; a memory module used for buffering the data after the analyzing and before the packaging and relevant instruction data; a DSP used for reading out the data in the memory module and making relevant process, and for processing the transmitted data and transmitting it to the FPGA. The system completes the relevant testing based on the apparatus above. The invention can be used in TD=SCDMA, CDMA2000 and WCDMA system.

A method is disclosed for operating a synchronous space division multiple access, code division multiple access communications system, as is a system that operates in accordance with the method. The method operates, within a coverage area of a base station (BS), to assign the same spreading code to a plurality of subscriber stations (SSs) and to transmitting signals to, and receive signals from, the SSs using an antenna array having M elements, where M>1 and where the M elements are spaced apart by more than one-half wavelength from one another. The spacing is a function of a size of an aperture of the antenna array which is a function of a signal bandwidth to carrier frequency ratio. The antenna array aperture is preferably less than k=p/360*fc/B wavelengths, where p is a maximum acceptable phase variation over the signal bandwidth, where fc is the carrier frequency and where B is the signal bandwidth. The step of conducting communications includes steps of despreading a plurality of received signals; and beamforming the plurality of despread received signals. In a preferred embodiment individual ones of P orthogonal spreading codes are reused αM times within the coverage area, where 1/M<α≦1.

The invention discloses passing through stations in SCDMA mobile communication system and its controlling method in order to complete frequency translating transpondering function so as to solve the issue of covering blind zone for base stations in SCDMA system. The passing through station in SCDMA mobile communication includes a casing one interface for input power source, two radio frequency modules, one control module including a handset board, a digital signal processor, a field programmable gate array, a D/A and A/D converter. The controlling method of the passing through station is to control the operation of the radio frequency circuit in TDD mode controlled by DSP and FPGA.

The method includes following steps: configuring radio resources in each sector into two sorts: switching preserved resources, and not switching preserved resources, and making switching preserved resources between each adjacent sector inter orthogonal; when communicating on switching preserved resources of service sector, if terminal detects that SNR of receiving signal in adjacent sector is better than SNR at service sector, then reports the message to base station in service sector; the base station in service sector indicates the user to switch to switching preserved resources in adjacent sector, thus, the adjacent sector becomes service sector of the terminal, and the former service sector becomes adjacent sector so as to accomplish switching across sectors. The invention can reduce level of same frequency interference at edge of sector effectively so as to guarantee communication quality when mobile user is in switching procedure across sectors.

A multiplexer and a method for chip-synchronous code-division multiple access (CDMA) signals produces a constant envelope signal. The output signal of the multiplexer permits use of a saturating (Class C) high power amplifier (HPA) resulting in a net increase in effective transmitter power usage. This multiplexer applies to a variety of CDMA spread spectrum modulation formats and has many applications, such as the IS-95 forward link interface, and CDMA and CDMA/FDMA (frequency-division multiple access) applications, including general cellular base station forward traffic channels, cellular subscriber station multiple-channel reverse traffic channels (e.g. IS-95 subscriber Internet access) and satellite downlinks.

This invention relates to a method for reducing reference among cells in TD-SCDMA access system. It contains respectively distributing different number up and down service time slot to different cells according to different service types, in adjacent cells with different service time slot, stopping any cell to use said service time slot and keeping another cell up and down service time slot to be unchanged. Said invention can optimize TD-SCDMA access system configuration and raise system capacity.

The invention provides a mobile terminal for an antenna shared by a mobile phone television and a mobile communication module, including a time-division synchronous CDMA access RF transmit-receive module and a China mobile digital multimedia broadcast S waveband RF receive module. The apparatus also including an antennae and a low pass filter; the input terminal of the low pass filter being connected with the time-division synchronous CDMA access RF transmit-receive module, the output terminal of the low-pass filter being connecting with the antennae, and the China mobile digital multimedia broadcast S waveband RF receive module being connected with the antennae. By means of the technical scheme of the present invention, the time-division synchronous CDMA access frequency band and the China mobile digital multimedia broadcast S waveband can share one antennae, which reduces structure difficulty and hardware cost, at the same time two RF systems can work simultaneously, and the time-division synchronous CDMA access frequency band having non interference to the China mobile digital multimedia broadcast S waveband.

A method for dynamically configuring channel bandwidth of synchronous CDMA system includes measuring service amount of data packet service and time preact of user terminal, confirming distance restricted state between base station and user terminal according to measured time preact, reconfiguring up link or down link channel bandwidth according to said distance restricted state and said service amount.

The invention discloses a modulating processing method for sending data in a multi-carrier system. The method comprises the steps that: A. TX burst data is sent for each radio unit RU, different phase rotation is carried out to the TX burst data corresponding to the RU in a same carrier but belonging to different training sequence offset as well as the TX burst data corresponding to the RU in different carriers but belonging to same training sequence offset; B. all TX burst data corresponding to each carrier and after the phase rotation is superimposed and then variable frequency modulation processing is carried out to the superimposed result. The invention also discloses a sending terminal device used for sending data modulation processing. The device comprises at least one training sequence offset data processing module and a to-be-sent data generation module. The technical proposal of the invention can effectively reduce peak-to-mean ratio in the TDD-synchronous CDMA MC system.

In the invention, the method of establishing uplink synchronization by the mobile terminal in the system comprises: a) based on preact of the predetermined sending time, the mobile terminal sends the uplink pilot frequency signals; b) if the mobile terminal is not able to access, the physical layer of the mobile terminal resets the preact of the sending time, and returning to step a. The invention has the following advantages: 1)realizing the wide coverage at all kinds of scenes; 2) no need to scarifying the TS1 time slot as the extra protection time slot; 3) no need to modify the currently-used base station, and only need to make slight modification for the mobile terminal 4) no need to amend the criteria and rule.

Disclosed is a method for transmitting information in a CDMA communication system, the method including steps of (a) multiplexing data and control information into a data stream; (b) encoding the data stream to form a stream of encoded I/Q symbol pairs; (c) inserting synchronization information into the stream of encoded I/Q symbol pairs; and (d) spreading the encoded I/Q symbol pairs and the inserted synchronization information using a same pseudonoise (pn) spreading code prior to transmission as a frame. The preferred frame structure includes an unencoded synchronization field followed by a plurality of multi-byte data fields. Individual ones of the plurality of data fields are separated by a control message field. Individual ones of the control message fields contain a single byte of a multi-byte control message frame.

The related energy saving method for TD-SCDMA direct station comprises: starting direct station for signal synchronization, detecting every time slot power and the exact position of two switch points; then, using RF switch in direct station fro link circuit conversion; comparing the detected time slot power with threshold, real-time setting the business time slot into power supplying state if the slot power over threshold, or else closing power for the free time slot; re-controlling up-down switch time, and continual tracking to detect business occupancy condition. This invention reduces cost for provider and saves the direct station consumption mostly.