Baseband is a signal that has a near-zero frequency range, i.e. a spectral magnitude that is nonzero only for frequencies in the vicinity of the origin (termed f = 0) and negligible elsewhere. In telecommunications and signal processing, baseband signals are transmitted without modulation, that is, without any shift in the range of frequencies of the signal. Baseband has a low-frequency—contained within the bandwidth frequency close to 0 hertz up to a higher cut-off frequency. Baseband can be synonymous with lowpass or non-modulated, and is differentiated from passband, bandpass, carrier-modulated, intermediate frequency, or radio frequency (RF).
The present invention is a double-layer multi-carrier ultra-widebandwireless communication method, wherein the frequency band for ultra-wideband communication is divided into a plurality of sub-bands, then one or more sub-bands are used for data transmission, and the Orthogonal Frequency Division Multiplex (OFDM) multi-carrier transmission technology is used in each sub-band. In the transmitting party, the data symbols to be transmitted are allocated on M branches corresponding to the M sub-bands, and the OFDM modulation is implemented on the data symbols on each branch to obtain M branches of parallel data, then digital baseband multi-carrier modulation is implemented on the M branches of parallel data. Thereby, the spectrum of data on each branch is moved onto the digital sub-band corresponding to the radio sub-band one to one, so the digital basebandsignal of the radio signal to be transmitted is obtained. Then, the digital signal is converted to an analog signal with a D / A conversion and an up-conversion, and the signal spectrum is moved to the radio frequency band in use, then the analog signal is amplified, filtered and transmitted via an antenna, thus the task of modulating M branches of parallel data onto M sub-bands is completed.
ActiveCN103209070ALow costReduce power consumptionTransmitter/receiver shaping networksSynchronising arrangementMultiplexingDigital down converter
The invention discloses a digital interfaceradio frequencychip and an implementation method thereof. The digital interfaceradio frequencychip comprises a receiving antenna, a radio frequency analog front-end subsystem and an analog baseband subsystem, wherein the analog baseband subsystem comprises an oversampling analog-to-digital converter, an internal clock generating module, a digital signal processor and a multiplexing parallel module, an output end of the receiving antenna is connected with an input end of the multiplexing parallel module through the radio frequency analog front-end subsystem, the oversampling analog-to-digital converter and the digital signal processor sequentially, and an output end of the internal clock generating module is connected with a clock input end of the oversampling analog-to-digital converter and a clock input end of the multiplexing parallel module respectively. According to the digital interface radio frequency chip, clocks generated inside the radio frequency chip serve as reference clocks, so that the correctness of the baseband chip data collection can be guaranteed; and no complex first-in first-out (FIFO) structure is required, the structure is simple, the integration is easy, and the cost and the power consumption are reduced. The digital interface radio frequency chip and the implementation method thereof are widely applied in the technical field of communications.
ActiveCN104219020AAvoid weakening or even offsetting problemsImprove abilitiesError prevention/detection by diversity receptionData processing systemCarrier signal
The invention discloses a multi-antenna system interference rejection device and method. The method includes the following steps that S1, a basebandsignal vector ym is received according to a time domain, an intrinsic domain transformation matrix U is estimated, the received basebandsignal is transformed to obtain an interferential intrinsic domain representation rm of the received basebandsignal, and rm is equal to Uym; S2, as for each sampling moment, weighting merging is carried out on transformed values Uy1[n], Uy2[n],..., UyM[n] of M antennas to obtain an intrinsic domain estimated value; S3, inverse transformation is carried out on the intrinsic domain estimated value to obtain a desired signal estimated value. Compared with a traditional interference rejection combining algorithm, the device and method have the advantages that nonuniformity of narrow-band interference energy is made full use of in an intrinsic domain, interference and rejection are combined, and a better interference rejection effect is achieved.
InactiveUS20130322573A1Degraded performance and loss of performanceAdd settingsSpatial transmit diversityAmplitude-modulated carrier systemsEngineeringMulti stream
InactiveCN103957029AEasy to handleLower requirementModulated-carrier systemsTransmitter/receiver shaping networksFrequency spectrumIntermediate frequency
ActiveCN107517169AImprove data transfer efficiencyReduce overheadSite diversitySpatial transmit diversityChannel state informationAccess network
The invention discloses a half-blind channel estimation method for joint cooperative clustering of a cloud wirelessaccess network and belongs to the field of the cloud wirelessaccess network. The method comprises the specific steps that all users send pilot and data information to remote radio units; after the pilot and data information is amplified by the remote radio units, own pilot information of the remote radio units is superposed with the amplified information; the information is forwarded to a centralized basebandprocessing unit pool; the centralized basebandprocessing unit pool processes the information to obtain channel state information; cooperative clusters are divided for the remote radio units; combination-split operation is carried out; utility functions corresponding to different clustering modes are evaluated, thereby obtaining the optimum clustering mode; corresponding processing is carried out on the received information of various clusters in the centralized baseband processing unit pool through utilization of the half-blind channel estimation method, thereby obtaining independent channel state information of access links and forward links; and data information is demodulated. According to the method, the pilot cost required by channel estimation is effectively reduced, and the data transmission efficiency of the cloud wirelessaccess network is clearly improved.