System and method for distinguishing between antennas in hybrid mimo rdn systems

Abstract

A system for distinguishing between any one of a plurality of antennas in a multiple-input-multiple-output (MIMO) system having an augmented number of antennas is provided herein. The system includes a MIMO receiving system having N branches and configured to operate in accordance with a channel estimation MIMO receiving scheme; a radio distribution network (RDN) connected to the MIMO receiving system, the RDN comprising at least one beamformer, being fed by two or more antennas, so that a total number of antennas in the system is M, wherein M is greater than N, wherein each one of the beamformers include a combiner configured to combine signals coming from the antennas into a single signal; and at least one antenna distinguishing circuitry, each associated with a respective beamformer, wherein the antenna distinguishing circuitry is configured to distinguish between the signals coming from the antennas which feed the respective beamformer.

We claim: 
     
         1 . A system comprising:
 a multiple-input-multiple-output (MIMO) receiving system having N branches and configured to operate in accordance with a channel estimation MIMO receiving scheme; and   a radio distribution network (RDN) connected to the MIMO receiving system, the RDN comprising at least one beamformer, being fed by two or more antennas, so that a total number of antennas in the system is M, wherein M is greater than N and wherein N is an integer greater than 1, wherein at least one of the beamformers includes antenna distinguishing circuitry,   wherein the antenna distinguishing circuitry is configured to isolate individual contributions of the signals feeding the beamformer.   
     
     
         2 . The system according to  claim 1 , further comprising an RF control module configured to control the antenna distinguishing circuitry in accordance with a corresponding antenna distinguishing scheme. 
     
     
         3 . The system according to  claim 1 , wherein the MIMO receiving system is further configured to derive at least one of: phase and amplitude of each one of the distinguished signals, wherein the derived phase or amplitude is usable for applying appropriate weights to the RDN. 
     
     
         4 . The system according to  claim 1 , wherein the beamformer with the antenna distinguishing circuitry comprises radio frequency (RF) elements including at least one of: a phase shifter, a switch, a terminator, and an amplifier. 
     
     
         5 . The system according to  claim 1 , wherein the beamformer with the antenna distinguishing circuitry comprises a combiner configured to combine signals coming from a plurality of antennas associated with the beamformer into a single signal, and wherein selectable bypass for each antenna configured to bypass the combiner in the beamformer and convey the signal from the antenna to an output selector, and wherein the output selector is configured to deliver to the MIMO receiving system the signal from only one antenna at a time. 
     
     
         6 . The system according to  claim 5 , further comprising a calibration element for each one of the selectable bypass units, wherein the calibration element is configured to identify and take into account phase and amplitude difference between the combiner and the selectable bypass unit. 
     
     
         7 . The system according to  claim 5 , wherein the beamformer with antenna distinguishing circuitry is configured to selectively disconnect and terminate all but one of the antennas so that only one signal coming from the antennas is conveyed to the combiner output, at a time. 
     
     
         8 . The system according to  claim 1 , wherein the beamformer with antenna distinguishing circuitry comprises a phase shifter for each antenna, wherein the phase shifters are configured to change the phase of only one signal coming from the antennas at a time, and wherein the MIMO receiving system is configured to derive phase and/or amplitude of the signal coming from the antenna with the shifted phase by comparing the combined signals at two different phases. 
     
     
         9 . The system according to  claim 1 , wherein the beamformer with the antenna distinguishing circuitry comprises an amplifier for each antenna, wherein the amplifiers are configured to change the gain of only one signal coming from the antenna at a time, and wherein the MIMO receiving system is configured to derive phase and/or amplitude of the signal coming from the amplified antenna by comparing the combined signals at two different amplifications of the signal.