Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1997-12-23
2001-03-20
Nguyen, Lee (Department: 2746)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S101000, C455S132000, C455S277100, C455S504000
Reexamination Certificate
active
06205341
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process and an implementation device for adjusting the transmission and reception chains of the paths formed by a multipath transmission/reception device of a base station of a radiocommunications system, using in particular a multipath transmission/reception technique known by the abbreviation SDMA standing for “Space-Division Multiple Access”.
2. Discussion of the Background
Systems for radiocommunication with mobiles are mostly based on the cellular network concept in which a base station communicates with a number of mobiles within the cell for which it is responsible.
For transmitting and receiving signals, base stations currently use only simple antenna systems, either of the single-sensor or multi-sensor type, with RF combination to ensure complete coverage, or else of the two-sensor type with selection to obtain space diversity in reception.
The concept of SDMA, now widely reported in the literature, is aimed at increasing the capacity of a base station by performing multipath transmission and reception in an adaptive and intelligent manner.
However, the setting up of this technique runs up against problems of implementation and of control of the distortions in the transmission and reception chains. In particular, the most disturbing phenomenon is the phase and amplitude dematching of the paths. During reception, this phenomenon will prevent a correct location fix on the mobile and hence the allocation of an SDMA frequency. During transmission, this problem may cause the transmission of a signal in an undesired direction.
The techniques for alleviating these problems are well known in respect of reception, since they are implemented in radio direction finders and consist in performing a calibration of the antenna base followed by frequent adjustment of the reception paths.
During transmission, the problem is more complex since it involves adjusting the transmission paths (after calibration of the antenna base) while being independent of the structure of the antenna base.
SUMMARY OF THE INVENTION
The aim of the invention is to alleviate the aforesaid drawbacks.
To this end, the subject of the invention is a process allowing the regular adjusting of the transmission and reception chain of each of the paths formed by a base station of a system for radio communication with mobiles, including a transmission/reception antenna base and a multipath transmission/reception device, characterized in that it consists after a step of calibration of the antenna base:
within a step for adjusting the reception chains relating to each path, in distributing a first specified adjustment signal, synchronously over each of the reception chains, in calculating an equalization filter inverting the transfer functions relating to each reception chain,
within a step for adjusting the transmission chains relating to each path, in distributing a second specified adjustment signal, synchronously over each of the transmission chains, in extracting from each of the paths a part of the transmission signal before it is sent to the antenna base so as to re-inject it into the reception chains, and in calculating an equalization filter inverting the transfer functions relating to each transmission chain,
in performing the reception of the signals originating from the antenna base via the equalization filters previously calculated for the reception chains, or the transmission of the signals originating from the multipath transmission/reception device via the equalization filters previously calculated for the transmission chains.
The present invention has the advantage of adjusting the transmission and reception paths of a radiocommunication system utilizing an SDMA technique, making it possible to ensure the control of the wavefront of the signals received and transmitted by the system by using adjustment signals which avoid the phenomena of coupling between antennas.
REFERENCES:
patent: 4903032 (1990-02-01), Multedo et al.
patent: 5515378 (1996-05-01), Roy et al.
Berranger Robert
Monot Jean-Jacques
Multedo Gilbert
"Thomson-CSF"
Nguyen Lee
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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