Method and system for economical beam forming in a radio communication system

Abstract

Individual RF cables span between element/transceiver pairs in traditional beam forming systems, and the number of elements in an array used for beam forming is thus restricted. To reduce the number of RF cables but maintain or increase the number of elements in an antenna array, an embodiment of the present invention includes electronics at the base of an antenna tower that apply digital multiplexing codes to signals communicated to electronics located at the top of the antenna tower. The electronics at the top demultiplex the signals and transmit them via the antenna array. Received RF signals are processed in a like manner in a reverse direction. Fewer transmission paths (e.g., RF or fiber optic cables) than the number of elements in the antenna array can be used. More antenna elements provide benefits, such as higher user capacity, more antenna beams, narrower antenna beams, and higher in-building penetration.

1 . Apparatus for beam forming in a radio communication system, comprising: 
 a first electronics assembly located distal from a plurality of elements in an antenna array used for beam forming;    a second electronics assembly, located proximal to the antenna array; and    transmission means spanning between said first and second electronics assemblies having fewer transmission paths than the number of elements in the antenna array being used in a beam-forming manner.    
   
   
       2 . The apparatus as claimed in  claim 1 , wherein the transmission means is a fiber optic cable.  
   
   
       3 . The apparatus as claimed in  claim 1 , wherein the transmission means is an RF cable.  
   
   
       4 . The apparatus as claimed in  claim 1 , wherein the transmission means includes wires supporting baseband signals.  
   
   
       5 . The apparatus as claimed in  claim 1 , wherein the transmission means is a wireless link.  
   
   
       6 . The apparatus as claimed in  claim 1 , wherein the transmission means is a single transmission path selected from link types composed of: wire, fiber optic, RF cabling, RF wireless or optical wireless.  
   
   
       7 . The apparatus as claimed in  claim 1 , wherein, in at least one of the electronics assemblies, to transmit a subset of signals to the elements of the antenna array, at least one code is applied to form at least one code division multiplexed signal composed of information corresponding to plural elements of the antenna array; and said at least one code is applied to said at least one code division multiplexed signal to decompose the de-multiplexed signal.  
   
   
       8 . The apparatus as claimed in  claim 7 , wherein the codes are applied in the first electronics assembly.  
   
   
       9 . The apparatus as claimed in  claim 7 , wherein the codes are applied once in the first electronics assembly and applied once in the second electronics assembly.  
   
   
       10 . The apparatus as claimed in  claim 7 , wherein, for more than one data signal, each data signal is multiplied by code division multiplexed weights, where the weights are specific to the respective data signal, and summed together to form a composite code division multiplexed signal.  
   
   
       11 . The apparatus as claimed in  claim 10 , wherein the composite code division multiplexed signal is transmitted across a single transmission path between the first and second electronics assemblies.  
   
   
       12 . The apparatus as claimed in  claim 7 , wherein the codes are orthogonal codes.  
   
   
       13 . The apparatus as claimed in  claim 12 , wherein the orthogonal codes are Walsh codes.  
   
   
       14 . The apparatus as claimed in  claim 1 , wherein an uncoded data signal is transmitted between the first and second electronic assemblies.  
   
   
       15 . The apparatus as claimed in  claim 1 , wherein a coded signal is transmitted between the first and second electronic assemblies.  
   
   
       16 . The apparatus as claimed in- Claim 15 , wherein the codes are orthogonal codes.  
   
   
       17 . The apparatus as claimed in  claim 16 , wherein the orthogonal codes are Walsh codes.  
   
   
       18 . The apparatus as claimed in  claim 1 , deployed in a base transceiver station.  
   
   
       19 . A method for beam forming in a radio communication system, comprising: 
 transceiving at least one respective representation of at least one data signal along fewer transmission paths than the number of elements in an antenna array being used in a beam forming manner; and    using the antenna array, transceiving respective RF representations of said at least one data signal to a mobile station in a beam forming manner.    
   
   
       20 . The method as claimed in  claim 19 , wherein transceiving said at least one representation uses fiber optic communications techniques.  
   
   
       21 . The method as claimed in  claim 19 , wherein transceiving said at least one representation uses RF communications techniques.  
   
   
       22 . The method as claimed in  claim 19 , wherein transceiving said at least one representation uses wire-supported communications techniques.  
   
   
       23 . The method as claimed in  claim 19 , wherein transceiving said at least one representation uses wireless communications techniques.  
   
   
       24 . The method as claimed in  claim 19 , wherein transceiving said at least one representation uses a single transmission path selected from link types composed of: wire, fiber optic, RF cabling, RF wireless or optical wireless.  
   
   
       25 . The method as claimed in  claim 19 , further including: 
 applying a code set to form at least one code division multiplexed signal composed of information corresponding to plural elements of the antenna array; and    applying said at least one code set to said at least one code division multiplexed signal to decompose the de-multiplexed signal.    
   
   
       26 . The method as claimed in  claim 25 , wherein the code set is applied at least twice proximal to the antenna array.  
   
   
       27 . The method as claimed in  claim 25 , wherein the code set is applied at least once proximal to the antenna array and at least once distal from the antenna array.  
   
   
       28 . The method as claimed in  claim 25 , further including, for more than one data signal, (i) multiplying each data signal by code division multiplexed weights, where the weights are specific to the respective data signal, and (ii) summing the resulting coded, weighted, data signals together to form a composite code division multiplexed signal.  
   
   
       29 . The method as claimed in  claim 28 , wherein the composite code division multiplexed signal is transceived across a single transmission path for accessing the antenna array.  
   
   
       30 . The method as claimed in  claim 25 , wherein the codes are orthogonal codes.  
   
   
       31 . The method as claimed in  claim 30 , wherein the orthogonal codes are Walsh codes.  
   
   
       32 . The method as claimed in  claim 19 , wherein said at least one data signal is uncoded.  
   
   
       33 . The method as claimed in  claim 19 , wherein said at least one data signal is coded.  
   
   
       34 . The method as claimed in  claim 33 , wherein the codes are orthogonal codes.  
   
   
       35 . The method as claimed in  claim 34 , wherein the orthogonal codes are Walsh codes.  
   
   
       36 . The method as claimed in  claim 19 , deployed in a base transceiver station.  
   
   
       37 . Apparatus for beam forming in a radio communication system, comprising: 
 means for transceiving at least one respective representation of at least one data signal along fewer transmission paths than the number of elements in an antenna array being used in a beam forming manner; and    using the antenna array, means for transceiving respective RF representations of said at least one data signal to a mobile station in a beam forming manner.