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AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsYutaka Murakami, Shinichiro Takabayashi, Masayuki Orihashi, Akihiko Matsuoka
Estimating the term…
In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.
A digital wireless communication apparatus comprising:
A digital wireless communication method comprising:
Dependencies are inferred from the claim text.
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Arrangements for synchronising receiver with transmitter: speed or phase control by synchronisation signals
Speed or phase control by synchronisation signals: the synchronisation signals differing from the information signals in amplitude, polarity or…
Modulated-carrier systems: arrangements for allowing a transmitter or receiver to use more than one type of modulation
Using more than one carrier, e.g. carriers with different phases: using a pair of orthogonal carriers, e.g. quadrature carriers
Term end not estimated
1. Field of the Invention
The present invention relates to an apparatus and method for digital wireless communications using a multivalue modulation type.
2. Description of the Related Art
The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one example is illustrated by way of example, in which;
FIG. 1 is a diagram showing a frame configuration example of a conventional digital wireless communication apparatus;
FIG. 2A is a diagram showing a relationship between the amplitude and time when a reception signal (I component) is received;
As shown in FIG. 2A and FIG. 2B, if a reception signal is detected at time 2 at which a time offset is generated, an error from signal point 3 of a pilot symbol occurs, and therefore amplitude errors XI and XQ may occur. Because of this, the accuracy in estimating the phase, amplitude variation and frequency offset on the I-Q plane deteriorates.
At this time, the simplest pilot symbol configuration is to have 3 consecutive pilot symbols as shown in FIG. 3. In such a configuration, even if a time offset occurs, the error from a pilot symbol signal point reduces because there are 3 consecutive pilot symbols.
However, since no pilot symbols are transmitted immediately before and after the pilot symbol to transmit information, this results in a problem in terms of the transmission efficiency. Thus, the present invention suppresses deterioration of the information transmission efficiency and suppresses errors from pilot symbol signal points when a time offset occurs by modulating symbols immediately before and after a pilot symbol according to a modulation type different from the pilot symbol modulation type. Thus, the present invention can suppress deterioration of the error rate by suppressing deterioration of the accuracy in estimating the phase, amplitude variation and frequency offset on the I-Q plane.