Method and apparatus for providing elevation plane spatial beamforming

Abstract

In one embodiment, the present disclosure provides a method and apparatus for spatially filtering inter-cell co-channel interference in the elevation plane, which in turn will improve network spectral efficiency.

What is claimed is: 
     
         1 . A base station system, comprising:
 a precoding stage for mapping of baseband data symbols associated with a mobile terminal into two baseband signal branches and pre-coding the two baseband signal branches via a multiplication of the two baseband signal branches with complex pre-coding weights to impart a phase difference between the two baseband signal branches for generating pre-coded signals;   an allocation stage for allocating resources to the pre-coded signals;   a modulation stage for modulating the pre-coded signals into modulated signals;   a baseband to radio frequency (RF) up-conversion stage for up-converting the modulated signals into RF signals; and   a passive RF antenna assembly comprising a beamforming network having two ports for receiving the RF signals, and for creating a spatially coherent main beam with a variable elevation plane beam tilt in response to differentially phased signals across the two ports.   
     
     
         2 . The base station system of  claim 1 , wherein the passive RF antenna assembly comprises a plurality of antenna elements, wherein the plurality of antenna elements comprises at least five antenna elements. 
     
     
         3 . The base station system of  claim 1 , wherein the baseband to radio (RF) up-conversion stage further functions as a RF to baseband down conversion stage, for processing receive RF signals into receive baseband signals, the receive RF signals comprising differentially phased signals or differentially amplitude weighted signals from the passive RF antenna assembly. 
     
     
         4 . The base station system of  claim 3 , further comprising:
 a receiver combining stage for performing a vector summation on the receive baseband signals.   
     
     
         5 . The base station system of  claim 4 , wherein the vector summation comprises a maximal ratio combining process. 
     
     
         6 . The base station system of  claim 5 , wherein the maximal ratio combining process comprises a post-detection maximal ratio combining process. 
     
     
         7 . A method, comprising:
 mapping baseband data symbols associated with a mobile terminal into two baseband signal branches and pre-coding the two baseband signal branches via a multiplication of the two baseband signal branches with complex pre-coding weights to impart a phase difference between the two baseband signal branches for generating pre-coded signals;   allocating resources to the pre-coded signals;   modulating the pre-coded signals into modulated signals;   up-converting the modulated signals into RF signals;   receiving the RF signals via two ports of a beamforming network of a passive RF antenna assembly; and   creating a spatially coherent main beam with a variable elevation plane beam tilt in response to differentially phased signals across the two ports.   
     
     
         8 . The method of  claim 7 , wherein the passive RF antenna assembly comprises a plurality of antenna elements, wherein the plurality of antenna elements comprises at least five antenna elements. 
     
     
         9 . The method of  claim 7 , wherein the baseband to radio (RF) up-conversion stage further functions as a RF to baseband down conversion stage, for processing receive RF signals into receive baseband signals, the receive RF signals comprising differentially phased signals or differentially amplitude weighted signals from the passive RF antenna assembly. 
     
     
         10 . The method of  claim 9 , further comprising:
 performing a vector summation on the receive baseband signals.   
     
     
         11 . The method of  claim 10 , wherein the vector summation comprises a maximal ratio combining process. 
     
     
         12 . The method of  claim 11 , wherein the maximal ratio combining process comprises a post-detection maximal ratio combining process.