Basestation transmission system in mobile communication system and method for processing baseband signal using the same

A basestation transmission system in a mobile communication system, comprising:

• a channel card unit for band spread modulating a received voice signal into a baseband signal and transmitting the baseband signal in series;
• a digital combining unit for combining the baseband signal output from the channel card unit on a channel-by-channel basis for each of a plurality of sectors;
• a digital/analog converting unit for converting the serial baseband signal output from the digital combining unit into a parallel signal, and then converting the parallel signal into an analog signal;
• and
• a baseband signal processing unit for processing the baseband signal from the digital/analog converting unit to conform to a predetermined radio signal, wherein the channel card unit and the digital combining unit are integrated on a printed circuit board and the digital/analog converting unit and the baseband transmission unit are also integrated on a printed circuit board, and
• wherein the baseband signal processing unit includes:
• first low pass filters each for receiving a signal from the digital/analog converting unit and removing high frequency noise contained in the signal,
• differential amplifiers for removing dc offsets from the signals from the first low pass filters,
• phase equalizers each for providing a linear phase characteristic to a baseband signal output from a respective one of the differential amplifiers,
• second low pass filters each for removing unnecessary bands from the baseband signal output from a respective one of the phase equalizers,
• dc offset erasures each for removing unnecessary dc components output from the baseband signal from a respective one of the low pass filters, and
• amplitude equalizers each for amplifying the baseband signal output from a respective one of the dc offset erasures to an intended level.

A method for processing a baseband signal using a basestation transmission system in a mobile communication system, comprising the steps of:

• (1) band spread modulating a received voice signal into a baseband signal containing I signal portions and Q signal portions for each of a plurality of sectors, and for transmitting the baseband signal in series;
• (2) combining the I and Q signals portions of the base baseband signal generated in step (1) on a channel-by-channel basis for each of said sectors;
• (3) converting the serial baseband signal generated in step (2) into a parallel signal, and then converting the parallel signal into an analog signal;
• and
• (4) processing the analog signal to conform to a predetermined radio signal.

A method for processing a baseband signal using a basestation transmission system in a mobile communication system, comprising the steps of:

• (1) band spread modulating a received voice signal into a baseband signal and transmitting the baseband signal in series;
• (2) combining the base baseband signal generated in step (1) on a channel-by-channel basis for each of said sectors;
• (3) converting the serial baseband signal generated in step (2) into a parallel signal, and then converting the parallel signal into an analog signal;
• and
• (4) processing the analog signal to conform to a predetermined radio signal, wherein the step (4) includes the steps of:
• (41) removing high frequency noises contained in the signal from step (3),
• (42) removing dc offsets from the signal from the step (41),
• (43) removing the signal from the step (42) to be provided with a linear phase characteristic,
• (44) removing unnecessary bands from the signal from the step (43),
• (45) removing unnecessary dc components from the signal from the step (44), and
• (46) amplifying the signal from the step (45) to an intended level.

A baseband transmission system in a mobile communication system, comprising:

• a channel card unit for band spread modulating a digital voice signal into I signal portions and Q signal portions, said channel card unit including n modems connected to a single printed circuit board, where n>4;
• a digital combining unit for combining the I and Q signals output from the channel card unit on a channel-by-channel basis for each of a plurality of sectors;
• a digital/analog converting unit for converting a signal output from the digital combining unit into an analog signal;
• and
• a baseband signal processing unit for processing a signal output from the digital/analog converting unit to conform to a predetermined radio signal, wherein the digital combining unit separates the I signal portion into I+ and I− signal portions and the Q signal portion into Q+ and Q− signal portions.