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Radio transmission system,radio relay system and communication device

A technology for communication devices and wireless relays, applied in the field of wireless relay systems, communication devices, and wireless transmission systems, capable of solving problems such as reduced transmission efficiency and degradation of symbol reception characteristics, to prevent degradation of reception characteristics and reduction of transmission efficiency Effect

Inactive Publication Date: 2005-10-19
NTT DOCOMO INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0027] Therefore, when the retransmission signal is started to be transmitted from the wireless relay device, the reception characteristic of the symbol transmitted before the guard interval length is reset is greatly degraded.
[0028] In addition, when the transmission from the wireless relay device is stopped, the transmission efficiency is reduced because the data transmission is performed using a guard interval longer than necessary until the guard interval length is reset.

Method used

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  • Radio transmission system,radio relay system and communication device
  • Radio transmission system,radio relay system and communication device
  • Radio transmission system,radio relay system and communication device

Examples

Experimental program
Comparison scheme
Effect test

no. 1 Embodiment approach

[0068] The wireless transmission system according to the first embodiment of the present invention is configured as shown in FIG. 1, for example. As shown in the figure, the wireless transmission system is composed of a plurality of transmitting devices (transmitting device 1 and transmitting device 2 ) and receiving device 3 . In the wireless transmission system of this embodiment, signals are transmitted by the OFDM (Orthogonal Frequency Division Multiplexing) method, which is one of the multi-carrier methods, and the same transmission signal (OFDM signal) is transmitted from the transmission device 1 and the transmission device 2 to the reception device 3. ). In this embodiment, the transmitting devices 1 and 2 and the receiving device 3 correspond to communication devices that are connected to a predetermined line and transmit and receive data. In addition, in order to simplify the description below, the description will be made using 'transmitter' and 'receiver'.

[006...

Deformed example 1

[0096] Modification 1 is a form in which the reception device 3 determines the start of data transmission by the transmission device 2 . At this time, it is only necessary to determine the start of data transmission by the transmission device 2 based on the received signal power of the signal transmitted from the transmission device 1, and to notify the transmission device 1 and the transmission device 2 with a new transmission device application notification signal.

Deformed example 2

[0098] Modification 2 is a method in which the transmission device 1 determines the start of data transmission by the transmission device 2 . At this time, as long as the transmitting device 1 receives the feedback of the received signal power information from the receiving device 3, it determines the data transmission start of the transmitting device 2 according to the received signal power of the feedback, and notifies the transmitting device 2 of the new transmitting device application notification signal It can be connected with the receiving device 3.

[0099] In addition, the above-mentioned modified examples 1 and 2 can be similarly applied to the embodiment in which the transmitting device stops reporting the signal during operation.

[0100] In addition, in the above-mentioned embodiment, each transmitting and receiving device changes the length of the guard interval according to the new sending device application report signal / the operating sending device stop report...

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Abstract

The invention provides a wireless transmission system capable of preventing the deterioration in the reception characteristics, caused by transmitting the same transmission signal from a plurality of transmitters, and reduction in the transmission efficiency, caused by stopping the transmission a signal from a certain transmitter. In a wireless transmission system, wherein the same transmission signals transmitted from a plurality of transmitters are received by a receiver, each of the transmitters and the receiver comprise a detection means for detecting the start and stop of data transmission from the transmitter, and a guard interval length control means for controlling a guard interval length, based on the result of the detection in the detection means.

Description

technical field [0001] The present invention relates to a wireless transmission system, a wireless relay system and a communication device that use two or more communication devices to transmit and receive the same OFDM signal. Background technique [0002] In mobile communications, an OFDM (Orthogonal Frequency Division Multiplexing: Orthogonal Frequency Division Multiple Access) transmission scheme has been studied as a technique capable of reducing characteristic degradation due to the influence of delayed waves. The OFDM transmission method transmits data using a plurality of sub-carriers (sub-carriers), and can increase the symbol length of each sub-carrier, thereby reducing characteristic degradation due to the influence of delay waves. [0003] In addition, by using a guard interval that copies a part of the OFDM modulated signal and adds it to a data symbol, it is possible to further reduce characteristic degradation due to the influence of a delay wave. [0004] Fi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04J11/00H04B7/26H04L27/26H04W16/24H04W16/26H04W72/04H04W88/02
CPCH04L27/2605H04L27/2602H04L27/26025
Inventor 浅井孝浩藤井启正田中哲须田博人
Owner NTT DOCOMO INC
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