Abstract:
A receiver and a method for determining connection quality in a cellular radio system. Received signals are decoded with a Viterbi decoder. Decision variables, representing decisions, are converted into a float value format. The converted decision variables are stored in a memory unit. During a traceback step of a Viterbi algorithm, a sum of absolute values of stored ones of the decision variables, which are in a correct path, are calculated and a minimum value of the absolute values of the stored ones of the decision variables in the correct path is calculated. The sum of the absolute values is averaged over a desired measurement period and compared to a predetermined threshold to obtain a bit error rate over a connection. Faulty signal frames are detected based on the minimum value of the absolute values.
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:
There is provided a method of clipping a transmission signal. The method comprises: providing a residual signal of a complex envelope clipper based on the transmission signal to be clipped; providing a reference signal respective to the residual signal, the reference signal corresponding to an ideal residual signal; forming a clipping signal on the basis of the residual signal and the reference signal; subtracting the clipping signal from the residual signal for removing higher amplitudes of the residual signal; and subtracting the clipping signal from the reference signal for providing a reference signal respective to the clipped residual signal.
Abstract:
There is disclosed a technique for generating an improved estimate of the frequency error in a received signal, and more particularly the application of such a technique in the equalization circuitry of a wireless network element.
Abstract:
A method of simultaneously determining a DC offset and a channel impulse response from a received signal in a mobile communication system. The received signal Y comprising a set of training sequence bits that have been modulated prior to transmission. The modulated signals experience a certain phase shift and are rotated by a certain angle. The received signal may also comprise a DC offset component ADC that needs to be removed. By manipulation of the received signal samples with the knowledge of the original training sequence TRS and method of modulation used, it is possible to simultaneously estimate the communication channel's impulse response H and the DC offset ADC by finding the Least Square solution to a linear equation, such that the energy of the noise term introduced into the communication channel may be kept to a minimum.
Abstract:
The invention provides a data transmission solution in a telecommunication system. According to the invention, a data transmission scheme is selected for a first transceiver unit, which comprises a plurality of transmit antennas, on the basis of the quality of a communication link and transmit antenna correlation information associated with the first transceiver unit, from a list including at least the following data transmission schemes: transmitting different data from each antenna of the first transceiver unit, the data transmitted from one antenna being independent of the data transmitted from another antenna; and transmitting the same data from each antenna of the first transceiver unit and controlling the direction of the transmitted data according to the properties of a radio channel. The selection of the data transmission scheme is carried out during an active communication link between the first and a second transceiver unit.
Abstract:
A frequency error correction scheme applicable in a receiver of a mobile telecommunication system is presented. The present frequency error correction scheme is carried out in a time domain after an equalization process. The present frequency error correction scheme may be applied to a base station receiving signals transmitted according to a single-carrier frequency division multiple access communication scheme. The separation of different received signals for further processing is carried out in the frequency domain before the equalization and the frequency error correction.
Abstract:
A network element, a terminal and a method of allocating a radio channel to a connection between a terminal and a base station in a telecommunication system are provided. The number and properties of potential interferers in a plurality of available radio channels are determined, and channel allocation is performed on the basis of the determination.
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:
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.