Communication station having an improved antenna system

Abstract

A communication station includes an antenna system having multiple antennas and delay units for receiving a transmitted signal and outputting a combined signal having a known distortion imparted by the antenna system. The combined signal is in turn processed by a modem, which compensates for the known distortion in a manner which provides improved signal gain. The improved signal gain permits a reduction in transmit power and, accordingly, increased capacity of the communication station. Where the antenna system is to be remotely located from related signal processing equipment, separate units for the RF receiver/transmitter and the other signal processing equipment are provided so that the RF receiver/transmitter may also be remotely located along with the antenna system.

1 . A base station comprising: 
 (a) an antenna system including a plurality of antennas, wherein the antenna system generates a combined signal based on signals received by the plurality of antennas;    (b) a radio frequency (RF) receiver which generates a baseband signal based on the combined signal; and    (c) at least one modem configured to process the baseband signal, the modem comprising: 
 (i) an analog to digital converter for converting the baseband signal into a digital signal;  
 (ii) a tracker which directs the analog to digital converter to sample the strongest analog representation of data being transmitted to the base station to provide an accurate digital signal which includes a digital data signal and a digital pilot signal;  
 (iii) a phase lock loop; and  
 (iv) a vector correlator which determines, in conjunction with the phase lock loop, filter coefficients based on a distortion of the pilot signal, wherein the filter coefficients are associated with both natural multipath distortion and artificially introduced distortions imparted by the antenna system.  
   
   
   
       2 . The base station of  claim 1  wherein the antenna system comprises: 
 (a1) a summer;    (a2) a first antenna electrically coupled to a first input of the summer;    (a3) a second antenna;    (a4) a third antenna;    (a5) a first delay unit electrically coupled between the second antenna and a second input of the summer;    (a6) a second delay unit electrically coupled between the third antenna and a third input of the summer, wherein the summer adds signals received from the first antenna, the first delay unit and the second delay unit to generate the combined signal.    
   
   
       3 . The base station of  claim 2  wherein the antennas are spaced at least six wavelengths apart.  
   
   
       4 . The base station of  claim 2  wherein the antennas are located so as to receive code division multiple access (CDMA) communication signals from independent propagation paths.  
   
   
       5 . The base station of  claim 4  wherein the first delay unit imparts a delay of three chips relative to a signal received by the summer from the first antenna.  
   
   
       6 . The base station of  claim 5  wherein the second delay unit imparts a delay of seven chips relative to a signal received by the summer from the first antenna.  
   
   
       7 . The base station of  claim 1  wherein the antenna system comprises: 
 (a1) a first antenna;    (a2) a second antenna;    (a3) a third antenna;    (a4) a first summer;    (a5) a first bandpass filter electrically coupled to the first antenna;    (a6) a first low noise amplifier electrically coupled to the first bandpass filter;    (a7) a first delay unit electrically coupled between the first low noise amplifier and a first input of the first summer;    (a8) a second bandpass filter electrically coupled to the first antenna;    (a9) a second low noise amplifier electrically coupled to the second bandpass filter;    (a10) a first attenuator electrically coupled between the second low noise amplifier and a second input of the first summer;    (a11) a second summer;    (a12) a third bandpass filter electrically coupled to the third antenna;    (a13) a third low noise amplifier electrically coupled to the third bandpass filter;    (a14) a second attenuator electrically coupled between the third low noise amplifier and a first input of the second summer; and    (a15) a second delay unit coupled to an output of the first summer and a second input of the second summer, wherein the second summer outputs the combined signal.    
   
   
       8 . The base station of  claim 7  wherein the antennas are spaced at least six wavelengths apart.  
   
   
       9 . The base station of  claim 7  wherein the antennas are located so as to receive code division multiple access (CDMA) communication signals from independent propagation paths.  
   
   
       10 . A subscriber unit comprising: 
 (a) an antenna system including a plurality of antennas, wherein the antenna system generates a combined signal based on signals received by the plurality of antennas;    (b) a radio frequency (RF) receiver which generates a baseband signal based on the combined signal; and    (c) at least one modem configured to process the baseband signal, the modem comprising: 
 (i) an analog to digital converter for converting the baseband signal into a digital signal;  
 (ii) a tracker which directs the analog to digital converter to sample the strongest analog representation of data being transmitted to the subscriber station to provide an accurate digital signal which includes a digital data signal and a digital pilot signal;  
 (iii) a phase lock loop; and  
 (iv) a vector correlator which determines, in conjunction with the phase lock loop, filter coefficients based on a distortion of the pilot signal, wherein the filter coefficients are associated with both natural multipath distortion and artificially introduced distortions imparted by the antenna system.  
   
   
   
       11 . The subscriber unit of  claim 10  wherein the antenna system comprises: 
 (a1) a summer;    (a2) a first antenna electrically coupled to a first input of the summer;    (a3) a second antenna;    (a4) a third antenna;    (a5) a first delay unit electrically coupled between the second antenna and a second input of the summer;    (a6) a second delay unit electrically coupled between the third antenna and a third input of the summer, wherein the summer adds signals received from the first antenna, the first delay unit and the second delay unit to generate the combined signal.    
   
   
       12 . The subscriber unit of  claim 11  wherein the antennas are spaced at least six wavelengths apart.  
   
   
       13 . The subscriber unit of  claim 11  wherein the antennas are located so as to receive code division multiple access (CDMA) communication signals from independent propagation paths.  
   
   
       14 . The subscriber unit of  claim 13  wherein the first delay unit imparts a delay of three chips relative to a signal received by the summer from the first antenna.  
   
   
       15 . The subscriber unit of  claim 14  wherein the second delay unit imparts a delay of seven chips relative to a signal received by the summer from the first antenna.  
   
   
       16 . The subscriber unit of  claim 10  wherein the antenna system comprises: 
 (a1) a first antenna;    (a2) a second antenna;    (a3) a third antenna;    (a4) a first summer;    (a5) a first bandpass filter electrically coupled to the first antenna;    (a6) a first low noise amplifier electrically coupled to the first bandpass filter;    (a7) a first delay unit electrically coupled between the first low noise amplifier and a first input of the first summer;    (a8) a second bandpass filter electrically coupled to the first antenna;    (a9) a second low noise amplifier electrically coupled to the second bandpass filter;    (a10) a first attenuator electrically coupled between the second low noise amplifier and a second input of the first summer;    (a11) a second summer;    (a12) a third bandpass filter electrically coupled to the third antenna;    (a13) a third low noise amplifier electrically coupled to the third bandpass filter;    (a14) a second attenuator electrically coupled between the third low noise amplifier and a first input of the second summer; and    (a15) a second delay unit coupled to an output of the first summer and a second input of the second summer, wherein the second summer outputs the combined signal.    
   
   
       17 . The subscriber unit of  claim 16  wherein the antennas are spaced at least six wavelengths apart.  
   
   
       18 . The subscriber unit of  claim 16  wherein the antennas are located so as to receive code division multiple access (CDMA) communication signals from independent propagation paths.