Receiving method and receiver
First Claim
1. A receiving method for a receiver (10-13) of a digital cellular radio system, the receiver employing Viterbi detection and diversity reception, the method involving forming an estimated impulse response of a channel, and the estimated impulse response of the channel as well as the predetermined sequence (53) comprised in the signal being symbol sequences, characterized by the steps offorming a reference signal from the estimated impulse response of the channel and the predetermined sequence (53) within the signal, computing as a variance type computation the energy of noise associated with the signal from the reference signal and the predetermined sequence (53) received from the channel, computing the SNR as a ratio between the reference signal energy and the noise energy, and combining the diversity branch symbols which temporally correspond with one another, and weighting the outputs of the adapted filters (25) in each branch and the autocorrelation taps in the impulse response by the SNR of each branch.
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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.
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Citations
13 Claims
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1. A receiving method for a receiver (10-13) of a digital cellular radio system, the receiver employing Viterbi detection and diversity reception, the method involving forming an estimated impulse response of a channel, and the estimated impulse response of the channel as well as the predetermined sequence (53) comprised in the signal being symbol sequences, characterized by the steps of
forming a reference signal from the estimated impulse response of the channel and the predetermined sequence (53) within the signal, computing as a variance type computation the energy of noise associated with the signal from the reference signal and the predetermined sequence (53) received from the channel, computing the SNR as a ratio between the reference signal energy and the noise energy, and combining the diversity branch symbols which temporally correspond with one another, and weighting the outputs of the adapted filters (25) in each branch and the autocorrelation taps in the impulse response by the SNR of each branch.
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10. A receiver (10-13) of a digital radio system, the receiver comprising a Viterbi detection means (29), diversity branches and a means (26) for forming an estimated impulse response of the channel, characterized in that, in order to compute the SNR, the receiver (10-13) comprises
a means (28a) used for forming the reference signal from the estimated impulse response of the channel and the predetermined sequence (53) within the signal, a means (28b) for computing the channel noise energy from the reference signal and the received predetermined sequence (53) as a variance type computation, a means (28c) for computing the SNR as a ratio between the reference signal energy and the energy of the noise, and diversity branches combining means (45, 46) which combine the temporally corresponding symbols of the different branches, and a means (28) for weighting the outputs of the adapted filters (25) in each branch and the autocorrelation taps in the impulse response by the SNR of each branch.
Specification