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Receiver for determining modulation type

A receiver and signal receiving technology, which is applied in the direction of modulation type identification, modulated carrier system, phase modulated carrier system, etc. It can solve the problems of unsuitable handling of adjacent channel interference and co-channel interference.

Inactive Publication Date: 2004-02-18
NOKIA NETWORKS OY
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AI Technical Summary

Problems solved by technology

[0013] However, when the two signal paths provide very small and equal variances, this method is still very poorly suited to handle adjacent and co-channel interference
For example, a loss of about 3.5dB can occur in the presence of adjacent channel interference compared to the case where the receiver is informed of the modulation method used

Method used

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  • Receiver for determining modulation type
  • Receiver for determining modulation type
  • Receiver for determining modulation type

Examples

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Embodiment Construction

[0030] Embodiments of the invention are described in a system conforming to the GSM standard, especially designed to process GPRS signals, where the modulation is performed using the 8psk modulation method or the GMSK modulation method. It should be understood, however, that embodiments of the present invention may be used with any communication system and with any modulation method. Embodiments of the present invention can be used in any receiver that receives signals with an unknown modulation method.

[0031] refer to Figure 4, which shows the basic structure of a time slot in the GSM standard. The first 3 symbols are the first trailer field 42 . This is followed by a data field 44 comprising 58 symbols of encrypted data. This is followed by a training sequence field 46 of length 26 symbols. The training sequence field is called "user midamble" because it is between the 2 data fields. The training sequence is a sequence of symbols known to the receiver. In general te...

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PUM

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Abstract

This invention relates to a method for determining a modulation method comprising demodulating said method comprising demodulating said received signal using at least two different modulation methods, determining for each demodulated signal an estimate of said channel, said estimate of said channel comprising m taps, selecting n of said taps for each channel estimate, a being less than m, estimating a variance for each demodulated signal based on said n taps, and comparing the estimated variances and based on said comparison making a determination as to the modulation method applied to the received signal.

Description

technical field [0001] The present invention relates to a method of determining the modulation used. The invention also relates to a receiver capable of determining the modulation that has been applied to received data. Embodiments of the present invention may be used in particular, but not limited to, in connection with the GSM standard. Background technique [0002] refer to figure 1 , where a schematic diagram of a known wireless communication network 2 is shown. The area covered by the network 2 is divided into a number of cells 4 . Each cell 4 has a base station 6 . Base stations 6 are used to communicate with mobile stations 8 within the cell. Various standards have been proposed for communication between base stations and mobile stations. One commonly used standard is the GSM (Global System for Mobile Communications) standard. In this standard, the available frequency band is divided into several channels. These channels are further divided into frames, and fr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/00H04L27/20
CPCH04L25/0212H04L27/2017H04L27/2067H04L27/0012
Inventor 沙天思兰·孙达拉林拉姆
Owner NOKIA NETWORKS OY
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