Fig. 1. Front-end of a conventional 4-antenna wireless receiver.
Wireless receivers for Multiple-Input and Multiple-Output (MIMO) and Single-Input and Multiple-Output (SIMO) wireless communication systems use several antennas forming a multiple-port antenna array. The performances of multiple-antenna radio communication systems are often assessed using the assumption of uncoupled antennas. This is an approximation, which will fail if the antennas are close to each other. The physical size of the antenna array being often limited by the application (e.g. in the case of portable transceivers), there is a need to take into account antenna coupling.
Fig. 1 shows the block diagram of a conventional receiver using multiple antennas, comprising 4 antennas (100), 4 bandpass filters (200), 4 low-noise amplifiers (300), 4 analog processing and conversion circuits (400) and a multiple-input signal processing device (550), whose output is connected to the destination (600). Matching of this receiver with the antenna array cannot be achieved because the impedance matrix of coupled antennas is not diagonal.
Our new scheme for the front-end of wireless receivers using several antennas uses a single multiple-input-port and multiple-output-port (MIPMOP) low-noise amplifier (LNA) instead of multiple independent single-input-port and single-output-port LNAs in a conventional design. Such a MIPMOP LNA may provide hermitian matching with the multiple-port antenna array. In this case, maximum power transfer occurs. Detailed information on such a design has been provided in a published paper B68. An essential feature is that a low-noise MIPMOP amplifier requires no added circuit element compared to independent LNAs.
Fig. 2 shows the block diagram of a wireless receiver using a MIMOmatch front-end, comprising a MIPMOP low-noise amplifier (350), and the other blocks used in Fig. 1. As explained in B69, a good building block for this approach is the MIMO series-series feedback amplifier (MIMO-SSFA) initially introduced by Excem to obtain reduced crosstalk and echo in multiconductor interconnections using the ZXtalk method.
We refer to the wireless receiver front-end covered by the combination of our patent applications P30, P33 and P34 as a MIMOmatch front-end. The invention P41 is a recent improvement to P30 and P33. Note that the inventions P30, P41 and (to a lesser extent) P33 may also be applied to our ZXtalk method for the cancellation of echo and crosstalk in electrical interconnections.
Our published papers and Patent Cooperation Treaty (PCT) applications on the MIMOmatch can be reached in the Club Excem section of this web site.
Companies interested in the possibility of implementing the MIMOmatch should contact us.
Excem's senior research engineers have long experience in R&D in the field of radio transmission and propagation. They performed several studies concerning the reduction of interference in radio astronomy instruments like the Nançay radiotelescope, some of which led to published papers B25 B27 B42. They designed measuring instruments based on radio propagation, like the VIG3 systems presented in several articles B14 B16 B19 B26. They are also radio amateurs: Evelyne Clavelier is F1PHQ and Frédéric Broydé is F5OYE.
More recently, they worked on high efficiency amplifiers for wireless transmitters and introduced the MIMOmatch receiver front-end.
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