Abstract: The invention relates to a method for reducing the effects of noise and to a receiver comprising at least one sampling means (12) for forming sample signals from a received signal. The receiver also comprises a whitening means (30) for converting the noise in the sample signals to white noise and digital filters (41, 42, 43, 44) for filtering the sample signals comprising white noise. The receiver further comprises a computation means (80) for computing filter tap coefficients from a sample signal. Further still, the receiver comprises summers (51, 52), each one of which is arranged to receive a filtered signal from at least one filter and to sum the signals received from the filters to produce first summed signals. The receiver also comprises a detector (60) for summing the first summed signals to produce the actual summed signal and for detecting the actual summed signal.

Abstract: A method for improving the quality of data transmission in cellular radio systems utilizing time division multiple access, in which the strength of a signal received at a base station is measured and a decoder for soft decision-making is employed. The method comprises the steps of measuring the strength of the signal the base station receives in at least two consecutive time slots and determining a weighting coefficient by comparing the signal strengths and reducing by means of the determined weighting coefficient in soft bit decision-making the significance of at least one symbol at the beginning of the burst the base station receives in a time slot if the difference between the measured signal strengths is considerable.

Abstract: The present invention proposes a method for processing signals in order to remove waveform distortion by using an equalizer, said method comprising the steps of receiving an incoming signal, preprocessing said incoming signal, estimating a channel impulse response from said received signal estimating a noise energy from said received signal, calculating filter taps by using said estimated channel impulse response and said noise energy, filtering said received signal by using said calculated filter taps by a feedforward filter means, and supplying said received signal to an equalizer means which comprises a feedback filter, to obtain a resulting signal by a decision in said equalizer means, wherein said estimated channel impulse response is partitioned into at least two parts, in said calculating step of the filter taps one of said parts of said channel impulse response being used for calculating filter taps in said calculating step of the filter taps by using a weight function.

Abstract: The present invention proposes a method for estimating a signal variance of a received signal (y) transmitted via a transmission channel, said method comprising the steps of: estimating the energy (RSSI) of the received signal (y), estimating the energy (Emax) of channel impulse response (h) taps, and estimating said signal variance (VAR) of said received signal by subtracting said estimated energy of channel impulse response taps (Emax) from said estimated energy (RSSI) of said received signal, such that said signal variance is obtained as VAR=RSSI−Emax. The present invention also proposes a correspondingly adapted device.

Abstract: An error control apparatus and method is disclosed, wherein a control message is used to request a retransmission of a received erroneous digital signal transmitted in a first direction via a transmission medium. The control message is transmitted in a second direction of said transmission medium, wherein the transmission rate of the control method is controlled in dependence on a usage of the transmission medium in the second direction and/or an amount of available memory in a receiving means (5) for receiving said digital signal. Thereby, the overall data throughout in the first and second direction can be optimized by changing the rate of the control message.

Abstract: The invention relates to a method for estimating an impulse response, and a receiver whose received signal is formed of bursts comprising a training sequence and the receiver comprising analog-to-digital converter for sampling the received signal and signal processor for measuring a DC offset in the samples. To simplify the receiver structure, the receiver comprises a calculating device for calculating the impulse response by correlating the samples taken with the training sequence before removing the DC offset, and the signal processor for removing the DC offset effect from the calculated impulse response.

Abstract: The present invention relates to reception method and apparatus. The invention is characterized in that received symbols are function of bits which are determined by means of temporally successive trellis levels, which comprises a predetermined number of states, with a transition from each of the states to a state at the next level being performed on the basis of a received signal.

Abstract: A method for carrying out channel equalization in a radio receiver wherein an impulse response is estimated, noise power is determined by estimating a co-variance matrix of the noise contained in a received signal before prefiltering, and tap coefficients of prefilters and an equalizer are calculated. The method comprises determining the noise power after prefiltering by estimating a noise covariance matrix, after which input signals (416, 418) of the channel equalizer are weighted by weighting coefficients obtained from the noise covariance estimation.

Abstract: The invention relates to a data transmission method and a radio system implementing method. A transmitter has at least two modulation methods by which it can modulate a signal. One or more demodulators (106) of the receiver demodulates the received signal in a manner which corresponds to each modulation method used. The modulation method used for the signal is inferred in a reference block (110) from the impulse response estimate. The signal according to the inferred modulation method is detected in a detector (114).

Abstract: The invention relates to a method and arrangement for modulating a signal to be transmitted, the arrangement comprising an encoder and a frequency modulator. In order to enable high rate transmission in a flexible manner in a narrow frequency band, the encoder (104) is a differential encoder and before the frequency modulator, the arrangement comprises means for multiplying the signal to be transmitted by a factor of the form &pgr;/(2m), where m is a positive integer greater than one.

Abstract: The present invention proposes a signal processing device for processing received signals having been transmitted via a transmission channel, wherein said received signals (y) are supplied to an estimation means (2) adapted to estimated a channel impulse response function (h) of said transmission channel (1), with said estimation means being adapted to perform a Linear-Minimum-Mean-Square-Error-(LMMSE-) processing based on a training sequence (TR_SEQ) transmitted together with received samples contained in said received signals (y), and a noise and interference energy estimate represented by a noise and interference variance (&dgr;2) as well as an impulse response energy distribution estimate represented by an estimated parameter covariance matrix (Chh) for said channel (1). The present invention also proposes a corresponding method for signal processing.

Abstract: The present invention proposes a device for processing received signals (y) having been transmitted via a transmission channel (1), comprising: estimation means (2, 2a) adapted to obtain an estimated impulse response function (hk) of said channel (1) based on said received signals (y) which are received at a first time; derivation means (3; 3a-3f) adapted to derive history information (wink) based on at least one previously estimated impulse response function, calculation means (4; 4a, 4b) adapted to calculate modifying information (mwink) on the basis of said history information (wink), and modification means (5) adapted to modify said estimated impulse response function (hk) of said channel (1) obtained on the basis of said received signals (y), by applying said modifying information (mwink) to said estimated impulse response function (hk) of said channel obtained on the basis of said received signals (y), and adapted to output a modified impulse response function (hmk).

Abstract: The invention relates to a method and an apparatus for implementing automatic gain control in a system where an analog signal is converted into a digital signal. The apparatus comprises means (208) for performing automatic gain control of the adjustable signal in an analog manner using a gain control step of predetermined size and means (446, 448) for performing inverse gain control of the digitized signal in such a way that, after the digital adjustment, the power of the signal is the same as before the analog adjustment. To enable an accurate gain control, the apparatus further comprises means (410, 412, 214, 420) for determining the maximum energy of the signal during a predetermined measurement period, means (426, 428) for comparing the determined maximum energy to preset threshold values (430, 432), and means (436) for performing an automatic gain control of the analog signal and a compensation for the gain control to the digital signal, if the measured value exceeds the threshold.

Abstract: A method for estimating an impulse response and a receiver in a radio system where the signal to be sent comprises a known training sequence, which receiver comprises means for sampling the received signal, and means for calculating a first estimate for the impulse response by means of the known training sequence. To enable an accurate determination of impulse response, the receiver comprises means for making preliminary decisions of the received samples by means of the first impulse response estimate, means for calculating an error value of the estimated samples and the received samples calculated by means of the preliminary decisions, means for calculating a second estimate of the impulse response by minimizing said error value, and means for calculating a new estimate for the impulse response by combining the first and second estimates to one another.

Abstract: The invention relates to a receiving method in a digital cellular radio system. The invention further relates to a receiver of the cellular radio network. In computing the signal to noise ratio, a reference signal is utilized which is the convolution of the estimated impulse response of a channel and the predetermined sequence. The signal to noise ratio is obtained as a ratio between the variance of the reference signal and the predetermined sequence received from the channel. The signal to noise ratio is used for weighing the diversity branches of the diversity receiver.

Abstract: The invention relates to a decimation method and a decimation filter, which provide the transfer function of a CIC decimation filter. Decimation of the number of order N is performed by coefficient M, whereby FIR filtering is carried out in the main branch (100) of the decimation filter by M-tap FIR filters (20) N times in sequence, decimation is carried out by decimation means (21) by coefficient M and comb-filtering is carried out by means (22) N−1 times. The effect of sample cycles M preceding the sample cycle M to be processed is taken into account by using side branches (101, 102, 104) and additional branches (103, 105, 106, 107).

Abstract: The invention relates to a method for generating a signal amplitude behaving according to a desired function and to a converter implementing the method. In the method, a function that is used for controlling the behaviour of a signal amplitude is piecewise linearized to provide straight lines; a slope and a constant term of each straight line is stored in a memory (202 and 203); and a midpoint of each straight line is shifted to form an origin in a common coordinate system. Variable data (213) is used as address data, which is divided into an MSB (207) and an LSB part (208). The MSB part (207) is used for addressing from the memory (202 and 203) the slope and the constant term of the straight line. The LSB part (208) functions as a variable of a common coordinate system of the straight lines.

Abstract: A method of detecting a call set-up burst, and a receiver, in a digital radio system, the receiver comprising a converter (304) for sampling a signal received in a given time slot, means (400) for correlating digitalized samples with a known training sequence, and means (402) for computing the energy of the correlation results obtained, means (404) for looking for the maximum values of a string of samples of a given order from the computed energies, and means (408) for averaging the maximum values found per one sample. To improve reliability of detecting a call set-up burst, the receiver comprises means (410) for averaging the energy of the other samples of the time slot per one sample, and means (412) for comparing the averaged maximum energy values with the energy values of the other samples.

Abstract: A base station for a mobile communication system which has switching centers and base stations connected by telecommunication links, each base station transmitting radio signals divided into a plurality of time-slots in a frame structure, a controller unit for controlling the base station; a transmitter for generating a transmission signal, the transmitter being connected to the switch to supply the transmission signal to the antenna via the switch; a counter for counting the length of time-slots in a frame structure synchronized by a frame alignment signal, a programmable memory in which one or more delay values are each stored as a counter value, a selecting unit for selecting a delay value desired by the user, and a power level memory responsive to the counter and storing power level memory momentary power values corresponding to the parts of the time-slots in the frame structure, as well as information on whether the switch supplying the transmission signal of the transmitter to the antenna is switched of

Abstract: Many digital processors have an asynchronous bus controlled by two control signals. To interface a synchronous memory to an asynchronous bus, interface logic is required. In an interface for transferring data from an asynchronous circuit to a synchronous circuit, data to be written are written in an intermediate register while timing control signals are being synchronized to a system clock by means of flip-flops. Correspondingly, in an interface for transferring data from the synchronous circuit to the asynchronous circuit, a signal indicating a read transaction from the synchronous circuit is synchronized to the system clock by means of a flip-flop circuit.