Pulse or digital communications – Testing
Reexamination Certificate
1999-08-25
2002-11-26
Corrielus, Jean (Department: 2631)
Pulse or digital communications
Testing
C455S067700
Reexamination Certificate
active
06487245
ABSTRACT:
BACKGROUND OF THE INVENTION
The field of the invention is that of systems of radiocommunications with mobiles.
The invention can be applied especially but not exclusively to radiocommunications systems such as the UMTS (Universal Mobile Telecommunication System), GSM 900 (Global System for Mobiles—900 MHz), DCS 1800 (Digital Cellular System—1800 MHz) or PCS 1900 (Personal Communication System—1900 MHz) type systems.
More specifically, the present invention relates to a method for the testing of a radiocommunications network that consists in detecting and elucidating the nature of the interference between at least two transmitters, namely one the one hand a mobile station emitting useful signals towards a base station and, on the other hand, at least one interference unit sending interference signals also towards the base station.
It may be recalled that a radiocommunications system generally comprises a plurality of base stations, each carrying out the radio coverage of a distinct geographical cell.
Hereinafter in the present description, the term <<interference unit>> (with respect to a given mobile station) is understood to mean any type of device that is sending a base station, with which a given mobile station is communicating., signals having at least certain characteristics that are identical or similar to those of the signals coming from the given mobile station.
Depending on the system, the mobile station is sometimes called a radiocommunications terminal, a portable radiotelephone, a portable telephone or again a mobile radiocommunications terminal. With a view to simplification, only one expression, <<mobile station>> will be used hereinafter in this patent document.
It will be recalled that a mobile station is a piece of physical equipment used by a user of a network of the radiocommunications system to obtain access, through a base station, to the telecommunications services on offer.
It will also be recalled that a base station covers a given geographical zone (or cell) in which a plurality of mobile stations, with which the base station can exchange signals, may move about. Conventionally, a base station comprises at least one antenna designed to receive and/or transmit signals from and/or to a plurality of mobile stations.
The signals exchanged between a mobile station and the base station may be subject to interference that could generate a partial or even total loss of the information conveyed. It may be recalled that interference phenomena are caused especially when signals having identical or similar characteristics are brought into play in the same propagation medium. The expression <<identical or similar>> characteristics is understood to mean one and the same frequency, one and the same code or one and the same time interval depending on whether the type of multiplexing used is the Frequency Division Multiple Access (FDMA), Coded Division Multiple Access (CDMA) or Time Division Multiple Access (TDMA) type of multiplexing. In other words, the interference phenomena are due to the presence of at least one interference unit sending signals (called <<interference>> signals) which disturb the signals (called <<useful>> signals) sent by a mobile station. It will be understood therefore that such disturbances may generate crucial problems in terms of quality of reception and exploitation of the signals sent by a mobile station and intended for a base station.
Now, it is not possible, in the prior art, to detect the presence of an interference unit or units. It will be understood, however, that in order to reduce or even eliminate the interference due to one or more interference units, it is necessary to know about their existence and, if necessary, their nature, in order to take appropriate measures in order to try and eliminate them.
The present invention is designed especially to overcome this drawback of the prior art.
More specifically, one of the goals of the present invention is to provide a method for the testing of a radiocommunications network enabling the detection of the presence of at least one interference unit.
It is an additional goal of the invention to provide a method of this kind making it possible to determine the possible nature of the interference unit or units.
Another goal of the invention is to provide a method of this kind that can be implemented without any modification of the signals exchanged between a mobile station and a base station.
Another goal of the invention is to provide a method of this kind that can be implemented without any hardware modification of the existing mobile stations or, as the case may be, of the base stations.
Another goal of the invention is to provide a device enabling the implementing of a method such as this for the testing of a radiocommunications network.
SUMMARY OF THE INVENTION
These different goals as well as others that shall appear hereinafter are achieved according to the invention by means of a method for the testing of a radiocommunications network consisting in detecting and elucidating the nature of the interference between at least two transmitters, namely on the one hand a mobile station sending useful signals towards a base station and, on the other hand, at least one interference unit sending interference signals also towards said base station, the method comprising the following steps:
downline from a first antenna, a first reception line is implemented and, downline from at least one second antenna, at least one second reception line is implemented distinct from said first reception line, each antenna comprising an array of radiating elements distributed in a matrix arrangement on a support;
said first reception line is assigned to the reception of first signals, in a first incoming direction;
said at least one second reception line is assigned to the reception of second signals, in at least one second incoming direction;
each reception line tries to decode the signals that it receives and, if the decoding can be done, it reads an identifier that is conveyed by the signals and is proper to the transmitter that has sent them, so as to determine firstly which of said first and second signals are said interference signals and, secondly, at least one of the pieces of information belonging to the group comprising:
the incoming direction of said interference signals
the identifier, if any, of said at least one interference unit sending said interference signals.
The general principle of the invention relies therefore on the simultaneous focusing of several RF reception radiating beams (one per antenna) respectively on different sources of signals (namely, a source of useful signals and one or more sources, if any, of interference signals. Thus, at least one reception line is allocated to the processing of possible interference signals.
In this way, it is possible not only to know if one or more interference units are present but also to locate their angular position and find out their nature as the case may be.
It must be noted that the terms <<first antenna>> and <<second antenna>> (known as a <<smart antenna>>) have been used to simplify the understanding of the invention. It is clear, however, that it is not obligatory that there should be as many antennas as there are reception lines. In other words, the first and second antennas may constitute a single antenna.
It is also possible to plan that at least certain radiating elements of one and the same support should be shared by several antennas.
Advantageously, said incoming direction is expressed as a function of at least one of the angles belonging to the group comprising:
the azimuth;
the elevation angle.
It is recalled that an antenna associated with a reception line forms an RF reception radiating beam that may be oriented in elevation angle (namely the angle formed between the line connecting the mobile station to the antenna and the horizontal plane containing the support of the antenna) and/or the azimuth, (namely the angle formed betwee
Corrielus Jean
Kinney & Lange , P.A.
Societe Francaise du Radiotelephone
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