摘要:
A symbol synchronizer (100) is provided for a software-defined communications system (10). The symbol synchronizer (100), when integrated into either a pre- or post-detection diversity signal combiner (108, 208), enables highly accurate signal synchronization with minimal added system complexity. The symbol synchronizer (100) includes a single complex sliding window matched filter (102) for filtering an input digital signal with a match filtering function based on predetermined signal transfer function characteristics to average out receiver noise from the signal. A signal delay bank (84) includes a plurality of delay blocks each for delaying the digital signal filtered by the single matched filter for a predetermined number of samples. A complex correlator (88) correlates the digital signal filtered by the single complex sliding window matched filter (102) and delayed by the complex correlator (88) with a correlator reference signal, and selects an index of a path having a peak correlator value. As a result of such a configuration, the symbol synchronizer (100) is capable of determining symbol boundaries of channel signals in a multi-channel communications system to enable system signal measurement statistics and demodulated to be more accurately generated.
摘要:
Information encoded in a spread spectrum signal transmitted in a communications medium is recovered. A composite signal including a spread spectrum signal is received from the communications medium, and correlated with a spreading sequence to generate time-offset correlations. Respective first and second groups of the correlations are combined, e.g., according to estimated channel coefficients, to produce respective first and second combined values. The first and second combined values are then combined in a manner that compensates for correlated impairment in the composite signal to generate an estimate information in the transmitted spread spectrum signal, e.g., using weighting factors generated from an estimated composite channel response and an estimated impairment correlation, or adaptively generated weighting factors. Related apparatus are also described.
摘要:
Techniques for processing symbols received for a (transport) channel in a (W-CDMA) communication system. According to the W-CDMA standard, the coded bits of a transport channel are first rate-matched, then first de-interleaved, and then segmented to form X radio frames, where X is the transmission time interval (TTI) of the transport channel. The radio frames can be processed in various manners. In one aspect, the rate-matching and first interleaving can be applied to the coded bits of the transport channel X times to generate a radio frame with each application. In accordance with a method, the correspondence between the coded bit xm and the rate-matched bits yn, and between the rate-matched bits yn and the interleaved bits zk, can be computed based on direct or iterative computations. In another aspects, the first de-interleaving and inverse rate-matching can be applied onto each rad it is received, without having to wait for the remaining radio frames in the TTI to be received. The correspondences between the received symbols zk′, de-interleaved symbols yn′ and de-rate-matched symbols xm′ can be computed. Reduced buffering requirement and reduced processing delays may be achieved based on the above.
摘要:
This invention provides a spread spectrum signal demodulator in which a noise component included in respective demodulation symbols is reduced and an effect of interference removal is further improved. Symbol decorrelating means detect correlations between spread codes allocated to spread spectrum signals to be removed and a receiving signal. A symbol deciding means 121 synthesizes one or the plurality of one symbol correlation values b1 to bk in common phase, namely, diversity-synthesizes them so as to decide a symbol. As the symbol decision, hard decision or soft decision can be used. Correlation modification means input the one symbol correlation values b1 to bk output from the symbol decorrelating means and the symbol decided result output from the symbol deciding means 121 thereinto, and modify the symbol correlation values b1 to bk. The modified symbol correlation values d1 to dk are transmitted into interference replicating means so as to be spectrum-spread by corresponding spread codes.
摘要:
A direct sequence spread spectrum (DS-SS) communications modem for low signal to noise ratio applications and secure communications systems (10). The modulator (22) implements a quadrature-phase shift keying (QPSK) modulation scheme in which a pseudonoise code is supplied to one channel and a pseudonoise code is combined with data to define the other channel. The demodulator (34) receives the modulated signal and utilizes a signal acquisition processor (92) in order to detect the pseudonoise code applied to the first channel. Upon detection and acquisition of the first pseudonoise code, the second pseudonoise code may be determined in order to demodulate the second channel to yield the modulated data. The signal acquisition processor (92) provides numerous parametric measurements to enable fine demodulator tuning and robust acquisition of the pseudonoise spreading codes on the I and Q channels.
摘要:
A User Equipment (UE) has a circuit that performs the acquisition for the low chip rate option of the Universal Mobile Telecommunication System (UMTS) Time Division Duplex (TDD) standard as formulated by the Third Generation Partnership Project (3GPP). The present invention implements the detection of the basic SYNC code; the determination of the midamble used and the detection of the superframe timing based on SYNC code modulation sequence. This enables reading of a full Broadcast Channel (BCH) message.
摘要:
A multi-carrier filter for a wireless communications system employing a multi-carrier signal. The multi-carrier filter includes a first mechanism for receiving the multi-carrier signal and extracting carrier signal components of the multi-carrier signal in response thereto. A second mechanism filters the carrier signal components and outputs a demodulated and filtered multi-bandwidth signal in response thereto. In the specific embodiment, the first mechanism includes a rotator. The multi-carrier signal is a 3× bandwidth multi-carrier signal having three carrier components. The three carrier components include a center carrier, a left carrier, and a right carrier. The center carrier, the left carrier, and the right carrier are separated by approximately 1.25 MHz. The rotator is a lookup table rotator that includes a mechanism for selectively rotating the multi-carrier-signal clockwise or counter clockwise and outputting the left carrier or the right carrier, respectively, in response thereto.
摘要:
An improved multi-antenna receiver is realized for detecting signals transmitted by a multi-antenna transmitter by summing signals received at the plurality of receiver antennas after multiplying each by a respective constant. The summed signal is applied to a maximum likelihood detector. The respective constants, &lgr;j, where j is an index designating a particular receiver antenna, are determined by evaluating the largest eigenvector of the matrix A, where &Lgr; is a vector containing the values &lgr;j, and A is a matrix containing elements &agr;ij, which is the transfer function between the ith transmitter antenna to the jth receiver antenna. The &agr;ij terms are determined in the receiver in conventional ways.
摘要:
A transmission power control method of measuring an Eb/N0 after weighted signals are combined is disclosed. A plurality of rake receivers detect respective received signals for respective paths, delay demodulated data which are the detection result based on a set delay time, and then combine and output the demodulated data. A multipath searcher acquires reception delay information which is information on a delay time among the respective paths contained in the received signals. A rake receiver control unit sets the delay times for the rake receivers based on the reception delay information acquired by the multipath searcher. A plurality of first weighting units weight the demodulated data output from the respective rake receivers. A first combining unit combines the signals weighted by the first weighting units into one signal. An Eb/N0 measuring unit measures an Eb/N0 of the demodulated data combined by the first combining unit.
摘要:
A correlator can stop correlation computation on the basis of the value of a despreading code, and decreases the operation ratio of a section operated in accordance with a despreading code pattern to ½ that of a conventional scheme (when spreading is performed by BPSK). This correlator reduces the current consumption to about ½ that of the conventional scheme (when spreading is performed by BPSK) in a case of a sufficiently high spreading ratio by using a common total adder regardless of the despreading code pattern, thereby realizing lower current consumption than the conventional correlator without decreasing the operation speed.