Telecommunications – Transmitter and receiver at separate stations – Having measuring – testing – or monitoring of system or part
Patent
1996-12-18
1998-05-12
Eisenzopf, Reinhard J.
Telecommunications
Transmitter and receiver at separate stations
Having measuring, testing, or monitoring of system or part
455 676, 4552261, 455 65, 455506, 324 7621, 324 7626, 324617, 375224, H04B 1700
Patent
active
057521670
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of simulating a multi-path propagation of a radio (electromagnetic) wave in premises and street spaces which is required, for example, for practical use of a high speed wireless LAN, and to a method of inferring at various places a strength of a wave which is radiated from a wave source such as a radio wave, an acoustic (sound) wave, or the like, and to a method of inferring a three-dimensional spread of multi-path delay waves.
In order to construct a high speed wireless communication network, it is necessary to accurately know the three-dimensional radio wave propagation environment, i.e., radio wave multi-path propagation, state of frequency selective fading and field strength/delay spread at various places.
A conventional simulation method for multi-path propagation of an in-premise wireless LAN has been a ray-tracing method as shown in J. W. Mcknown and R. L. Hamilton, Jr.: "Ray Tracing as a Design Tool for Radio Networks", IEEE Network Magazine, pp. 27-30, November 1991. In this method, at a certain receiving point, based on the light receiving directions of direct lights and various reflected lights, each transmitting source from where each light reaches the receiving point without reflection is assumed and then, attenuations and delays are obtained from the distances between these transmitting sources and the receiving point and then interferogram states are obtained.
In the ray tracing method, since reflection surfaces are assumed for respective reflections by various objects in the premises, it is difficult to accurately assume each transmitting source for actual complex reflections, and thus, a proper simulation cannot be performed. In addition to the difficulty of accurate assumption of such complex reflection surfaces, the reflection state is different between a metal and a wood. Therefore, it is also difficult to accurately assume the materials of the reflection surfaces. Consequently, the inference error of the delay wave is in the range of 1 ns-100 ps. Because of such reasons, a direct simulation of quality of transmission channels under multi-path fading in high speed data communication has not been possible. That is, in the conventional method, a statistical inference of bit error rate based on the interference simulation and delay spreads for 2-3 waves at the best has only been possible and thus, only exceptional cases could be applied to the actual environment.
Further, a field strength has been measured under a three-dimensional radio propagation environment by placing a receiver at an observation point. As mentioned above, it is necessary to place a receiver every time at each observation point in a direct measuring method. Therefore, this method is time and work load consuming. Also, in this method, it is actually difficult to measure a wide three-dimensional space with short distance intervals.
Delay spread is utilized for evaluation of communication quality. For example, a maximum bit rate for the communication is determined from a delay spread value. In the conventional method, for example, as shown in IEEE Transactions on Antennas and Propagation, Vol. 42, No. 10, October, 1994, PP. 1369-1376 "A New Approach for Estimating Indoor Radio Propagation Characteristics", a radio wave modulated by a PN code is transmitted and the transmitted radio wave is received by a receiver provided at a measuring position and then is measured. Since, in this case, a receiver is also placed at each position to be measured and a direct measurement is performed, a large work load and a long time are necessary. Since a radio wave modulated by PN code is transmitted, a short delay cannot be separated unless the modulation frequency band width is wide enough and thus, the measuring accuracy is low.
It is an object of the present invention to provide a radio propagation simulation method by which a radio propagation can be simulated in a relatively simple arrangement even if many complex reflection objects are placed in a complex manner, and thus e
REFERENCES:
patent: 5381444 (1995-01-01), Tajima
patent: 5563909 (1996-10-01), Nakazawa
patent: 5656932 (1997-08-01), Kitayoshi
Advantest Corporation
Eisenzopf Reinhard J.
To Doris
LandOfFree
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