Methods and apparatus for orthogonal stream spatial multiplexing

Abstract

Methods and apparatus for orthogonal stream spatial multiplexing. In one embodiment, a method includes splitting and modulating a data stream into n MIMO RF spatial streams and coupling them to corresponding switchable polarization antenna elements controlled via orthogonal binary codes for transmission. Each transmitted stream manifests as time-varying-polarization-orthogonal to the other n−1 spatial streams. The method includes reception of the streams at their destination using corresponding antenna elements controlled by the same set of orthogonal codes. Thus, each of the n transmitted spatial streams is polarization-match-filtered, unambiguously separated and individually recovered from all the others upon reception for subsequent demodulation and MIMO spatial recombination into the original data stream. Thus, n MIMO spatial streams emanating from a common source and featuring equal amplitude and bandwidth but bearing distinct data and exhibiting mutually orthogonal time varying polarization will propagate mutually interference-free on the same frequency channel to a single destination.

What is claimed is: 
     
         1 . A transmitter apparatus, comprising:
 a plurality of transmit antenna circuits that input a plurality of RF spatial streams and a plurality of polarization control signals, respectively, and output a plurality of binary switched polarization RF spatial streams, wherein each transmit antenna circuit comprises first and second orthogonally polarized antenna elements that are selectively connected to an RF spatial stream based on a polarization control signal.   
     
     
         2 . The apparatus of  claim 1 , wherein the first and second orthogonally polarized antenna elements are:
 configured to provide one of horizontal (H) and vertical (V) polarization orthogonality or right-hand circular (RHCP) and left-hand circular (LHCP) polarization orthogonality; and   selectively connected to the RF spatial stream by an RF switch toggled by the polarization control signal.   
     
     
         3 . The apparatus of  claim 1 , also comprising a MIMO transmitter that inputs a digital Data Stream and outputs the plurality of RF spatial streams and the plurality of polarization control signals, wherein the MIMO transmitter comprises:
 a digital serial to parallel converter; and   a plurality of radio modulators that generate the plurality of RF spatial streams from the Data Stream.   
     
     
         4 . The apparatus of  claim 3 , wherein the MIMO transmitter further comprises:
 a code generator that synthesizes the plurality of polarization control signals; and   sync logic that synchronizes the polarization control signals with the plurality of RF spatial streams.   
     
     
         5 . The apparatus of  claim 4 , wherein the code generator synthesizes distinct digital binary switching sequences for the polarization control signals. 
     
     
         6 . The apparatus of  claim 1 , wherein each transmit antenna circuit radiates an RF spatial stream comprising binary switched orthogonal polarization that is reciprocally distinct from that of RF spatial streams radiated by other transmit antenna circuits. 
     
     
         7 . The apparatus of  claim 6 , wherein the RF spatial stream radiated from any particular transmit antenna circuit comprises polarization that is switched H-V or RHCP-LHCP reciprocally distinct from the polarization of RF spatial streams radiated by-other transmit antenna circuits. 
     
     
         8 . A receiver apparatus, comprising:
 a plurality of receive antenna circuits that input a plurality of binary switched polarization RF spatial streams and a plurality of polarization control signals, respectively, and output a plurality of binary switched polarization matched-filtered RF spatial streams, wherein each receive antenna circuit comprises first and second orthogonally polarized antenna elements that are selectively connected to a MIMO receiver based on a polarization control signal.   
     
     
         9 . The apparatus of  claim 8 , wherein the first and second antenna elements are:
 configured to provide one of horizontal (H) and vertical (V) polarization orthogonality or right-hand circular (RHCP) and left-hand circular (LHCP) polarization orthogonality; and   selectively connected to the MIMO receiver by an RF switch toggled by the polarization control signal.   
     
     
         10 . The apparatus of  claim 8 , wherein the MIMO receiver inputs the plurality of binary switched polarization matched-filtered RF spatial streams from the receive antenna circuits and outputs a received Data Stream, and comprises:
 a plurality of demodulators that output a plurality of digital streams from the plurality of switched polarization matched-filtered RF spatial streams; and   a digital parallel to serial converter that combines the plurality of digital streams to generate an output Data Stream.   
     
     
         11 . The apparatus of  claim 10 , wherein the MIMO receiver also comprises:
 a code generator that synthesizes the plurality of polarization control signals; and   sync logic that synchronizes the binary switched polarization RF spatial streams with the polarization control signals.   
     
     
         12 . The apparatus of  claim 11 , wherein the MIMO receiver code generator synthesizes distinct digital binary switching sequences identical to those generated by a MIMO transmitter code generator. 
     
     
         13 . The apparatus of  claim 8 , wherein each of the receive antenna circuits binary switched polarization matched-filters its received plurality of binary switched polarization RF spatial streams according to a polarization control signal that is reciprocally distinct from polarization control signals of other receive antenna circuits. 
     
     
         14 . A method for transmitting and receiving RF spatial streams, comprising:
 transmitting multiple distinct, concurrent, co-channel RF spatial streams by differently polarizing the RF spatial streams according to different polarization control signals, each control signal associated with and synchronized to a particular RF spatial stream; and   receiving multiple distinct, concurrent, co-channel RF spatial streams from a plurality of differently polarized RF spatial streams by polarization-matched-filtering the differently polarized RF spatial streams according to different polarization control signals, each control signal associated with and synchronized to a particular RF spatial stream.   
     
     
         15 . The method of  claim 14 , wherein said transmitting comprises employing a pair of orthogonally polarized antenna elements to transmit each differently polarized RF spatial stream, wherein the orthogonally polarized antenna elements are configured to provide one of vertical (V) and horizontal (H) polarization or right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP). 
     
     
         16 . The method of  claim 15 , wherein said transmitting comprises radiating differently polarized RF spatial streams by connecting selected RF spatial streams to selected pairs of orthogonally polarized antenna elements based on different polarization control signals. 
     
     
         17 . The method of  claim 15 , wherein said transmitting further comprises:
 MIMO processing that generates a plurality of RF spatial streams from an input Data Stream; and   code generation that synthesizes a plurality of different polarization control signals, wherein each polarization control signal is binary sequenced reciprocally distinct from the other polarization control signals and is synchronized with one of the RF spatial streams.   
     
     
         18 . The method of  claim 14 , wherein said receiving comprises employing a pair of orthogonally polarized antenna elements to receive each differently polarized RF spatial stream, wherein the antenna elements are configured to provide one of vertical (V) and horizontal (H) polarization or right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP). 
     
     
         19 . The method of  claim 18 , wherein said receiving comprises recovering the RF spatial streams by polarization-matched filtering the differently polarized RF spatial streams by connecting them to selected pairs of orthogonally polarized antenna elements based on different polarization control signals. 
     
     
         20 . The method of  claim 19 , wherein said receiving further comprises:
 MIMO processing that generates an output Data Stream from the recovered RF spatial streams; and   code generation that synthesizes an identical set of polarization control signals generated in the process for transmitting and synchronizes them with the differently polarized RF spatial streams.