Communication transmission with super-gaussian filtering in receiver

Abstract

In a transmission system, a transmission signal is generated from transmission data. The transmission signal has a series of shaped pulses, such as raised-cosine or root-raised-cosine shaped pulses, formed using a pulse-shaping filter. A reception signal, based on the transmission signal having passed through a transmission channel, is sampled to generate sampled digital data. The sampled digital data is filtered through a receiver filter to regenerate the transmission data, where the pulse shaping filter and the receiver filter are mismatched.

What is claimed is: 
     
         1 . A method comprising:
 receiving, by a transmitter, transmission data;   generating, by the transmitter, a transmission signal from the transmission data, the transmission signal having a series of shaped pulses;   transmitting, by the transmitter, the transmission signal;   receiving, by a receiver, a reception signal based on the transmission signal having passed through a transmission channel;   sampling, by the receiver, the reception signal to generate sampled digital data; and   filtering, by the receiver, the sampled digital data through a receiver filter to regenerate the transmission data   wherein:
 the transmitter generates the shaped pulses using a pulse shaping filter; and 
 the pulse shaping filter and the receiver filter are mismatched. 
   
     
     
         2 . The method of  claim 1 , wherein:
 the receiver filter is a super-Gaussian filter.   
     
     
         3 . The method of  claim 2 , wherein:
 the pulse shaping filter is selected from the group consisting of raised-cosine filter and root-raised-cosine filter families.   
     
     
         4 . The method of  claim 2 , wherein:
 the super-Gaussian filter in the receiver has excess bandwidth compared to the pulse shaping filter in the transmitter.   
     
     
         5 . The method of  claim 2 , wherein:
 the super-Gaussian filter operates with 4-16 sampling points to generate the sampled digital data.   
     
     
         6 . The method of  claim 2 , wherein:
 the super-Gaussian filter operates with a maximum of 4 sampling points to generate the sampled digital data.   
     
     
         7 . The method of  claim 2 , wherein:
 the super-Gaussian filter operates according to a super-Gaussian function having an exponent of 4 or more.   
     
     
         8 . The method of  claim 2 , wherein:
 the transmission signal is an optical signal; and   the transmission channel is a fiber-optic channel.   
     
     
         9 . The method of  claim 2 , wherein:
 the transmission signal is an RF signal; and   the transmission channel is air.   
     
     
         10 . The method of  claim 2 , wherein:
 the transmitter further generates the shaped pulses using a second pulse shaping filter that shapes the pulses operating according to a function G(ω); and   the filtering at the receiver further comprises filtering the sampled digital data using a filter operating according to a function 1/G(ω).   
     
     
         11 . A transmission system comprising:
 a transmitter having a pulse shaping filter with which the transmitter generates a transmission signal with a series of shaped pulses for transmission, the series of shaped pulses being generated from digital transmission data; and   a receiver having a receiver filter with which the receiver regenerates the digital transmission data from sampled digital data of a reception signal based on the transmission signal having passed through a transmission channel;   wherein the pulse shaping filter and the receiver filter are mismatched.   
     
     
         12 . The transmission system of  claim 11 , wherein:
 the receiver filter is a super-Gaussian filter.   
     
     
         13 . The transmission system of  claim 12 , wherein:
 the pulse shaping filter is selected from the group consisting of raised-cosine filter, or a root-raised-cosine filter.   
     
     
         14 . The transmission system of  claim 12 , wherein:
 the super-Gaussian filter in the receiver has excess bandwidth compared to the pulse shaping filter in the transmitter.   
     
     
         15 . The transmission system of  claim 12 , wherein:
 the super-Gaussian filter operates with 4-16 sampling points to generate the sampled digital data.   
     
     
         16 . The transmission system of  claim 12 , wherein:
 the super-Gaussian filter operates with a maximum of 4 sampling points to generate the sampled digital data.   
     
     
         17 . The transmission system of  claim 12 , wherein:
 the super-Gaussian filter operates according to a super-Gaussian function having an exponent of 4 or more.   
     
     
         18 . The transmission system of  claim 12 , wherein:
 the transmission signal is an optical signal; and   the transmission channel is an optical channel.   
     
     
         19 . The transmission system of  claim 12 , wherein:
 the transmission signal is an RF signal; and   the transmission channel is air.   
     
     
         20 . The transmission system of  claim 12 , wherein:
 the transmitter further comprises a second pulse shaping filter, wherein the second pulse shaping filter shapes the pulses operating according to a function G(ω); and   the receiver further comprises a filter operating according to a function 1/G(ω) which compensates for a departure of the transmitter and receiver overall transfer characteristic from a Nyquist condition for ISI-free communication.