Wireless transmission system, wireless transmission method, and wireless station and transmitting station used therein

Abstract

A wireless transmission system is provided with a feature in which a combination of a plurality of symbol waveforms brings about the maximum path diversity effect even in the case that the number of the most effective branches is limited to a small number. A transmission timing control unit (23) determines transmission start timing to be timing delayed by a prescribed delay amount from standard timing. A modulating unit (21) uses one from a plurality of symbol waveform candidates to modulate a signal in accordance with a modulation system in which a symbol waveform once demodulated on a receiving side exhibits anti-multiple path characteristics and its phase transition is a changing waveform, and transmits the same at transmission start timing. The prescribed delay amount is such magnitude that the number of receiving timing at which a receiving station (12) receives the signal per symbol waveform is plural and not larger than the number of the maximum effective branches, and that a difference between receiving timing is not less than a prescribed delay resolution and not larger than the upper limit of a prescribed delay.

Description

technical field [0001] The present invention relates to a wireless transmission system and a wireless transmission method for transmitting and receiving signals by a plurality of wireless transmission apparatuses using a transmission method with multipath resistance, and a radio station and a transmitting station used therein. Background technique [0002] In the field of wireless communication, there is a method for improving transmission characteristics, which is to artificially form a plurality of signals by using a modulation-demodulation method that is resistant to multipath, by causing a plurality of transmitting stations to transmit at the same time. path, and the effect of path diversity (or, also referred to as transmit diversity) is obtained by synthesizing a plurality of received arrival waves on the receiving side. [0003] Modulation-demodulation methods that are tolerant to multipath include methods that consider various modulation methods, and methods that use...

AI Technical Summary

Problems solved by technology

However, there is a problem that in this conventional transmission diversity, from the standpoint of tolerance (delay tolerance) to the delay dispersion that occurs in the propagation path, due to the The original ability of the way, it is necessary to insert a large delay τ on the sending side in advance s , thus resulting in a significant reduction in the amount of resistance to delay

like Figure 59 As shown in , it is known that the bit error rate deteriorates when a third wave is inserted between two waves compared to when there are two received waves

It can be confirmed that when there are 3 waves, the 3rd wave will not separate the two waves on both sides, bring the same interference, or increase the correlation value, resulting in deterioration

That is, if Figure 55 As shown, there is such a problem that although the transmission wave with up to two delays is ideal, when the third transmission wave is added, the characteristics will deteriorate on the contrary.

[0037] Like this, there is such a problem that when the delay resolution capable of separating delayed wave components and the delay upper limit are intentionally approached, since the maximum number of effective branches that contribute to the path diversity effect is limited to a small number, if a path with a delay is unintentionally added , it will lead to deterioration of transfer characteristics

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