Radio frequency transmitting device of mobile radio communication base station system in code division multiple access system

• US 7,058,037 B1
• Filed: 09/08/2000
• Issued: 06/06/2006
• Est. Priority Date: 09/13/1999
• Status: Expired due to Fees

• Current Assignee: Yamazaki Holdings LLC (Intellectual Ventures LLC)
• Original Assignee: UTStarcom Incorporated (UTStarcom Holdings Corp.)
• Inventors: Moon, Sung Bae
• Primary Examiner(s): Nguyen, Steven
• Assistant Examiner(s): HAN, CLEMENCE S
• Application Number:
  US09/658,696
• Time in Patent Office: 2,097 Days
• Field of Search: 370/342, 370/331, 370/335, 370/318, 455/561
• US Class Current: 370/335
• CPC Class Codes: H04B 1/04 Circuits
• CPC Class Codes: H04B 1/707 using direct sequence modulation

Abstract

Disclosed is an RF transmitting device of a mobile radio communication base station system in a CDMA system capable of digital-modulating baseband signals which are converted into band spread signals by using the same path which three frequency assignment frequency signals have for an RF in a multi-carrier mobile radio communication system supporting three frequency assignment, digital-coupling the modulated signals, and up-converting the digital-coupled signal into an IF signal and an RF signal in a sequential order, thereby transmitting the up-converted signal.

Claims

1. An RF transmitting device of a mobile radio communication base station system in a CDMA system having a plurality of channel cards providing baseband signals on I/Q channels for multi-frequency assignment and a transmitting antenna, said RF transmitting device comprising:

a plurality of digital modulators for digital modulating the baseband signals on the I/Q channels to frequencies according to a frequency assignment, wherein the baseband signals are provided from said plurality of channel cards, wherein each of said digital modulators comprises a digital local oscillator for outputting one of a plurality of local frequencies, and a digital mixer for generating mixed signals by mixing the baseband signals on the I/Q channels with respective ones of the plurality of local frequencies;

a digital adder for coupling the mixed signals;

a digital to analog converter for converting the coupled mixed signals into an analog-converted multi-frequency signal;

an analog frequency up-converting unit for up-converting the analog-converted multi-frequency signal in said digital unit into an IF signal and a secondarily up-converting the converted IF signal into an RF signal, wherein said analog frequency up-converting unit comprises a first frequency up-converter for up-converting the coupled multi-frequency assignment analog signal outputted from said digital unit into an arbitrary IF signal;

a band-pass filter for band-pass filtering the coupled multi-frequency assignment IF signal outputted from said first frequency up-converter to an arbitrary frequency bandwidth; and

a second frequency up-converter for converting the IF signal filtered in said band-pass filter into an RF signal to thereby output the converted RF signal to said transmitting unit, and wherein said band-pass filter is an SAW filter having the bandwidth of 3.75 MHz, in order to accurately pass the multi-frequency assignment coupled signal; and

a transmitting unit for amplifying the secondarily up-converted RF signal to an arbitrary transmitting output level and transmitting the amplified signal via said transmitting antenna.

2. The RF transmitting device as claimed in claim 1, wherein each of said plurality of digital modulators comprises:

a plurality of low-pass filters for low-pass filtering the baseband signals on the I/Q channels outputted from each of said plurality of channel cards by the frequency assignment; and

a plurality of interpolation filters for filtering the low-pass filtered baseband signals on the I/Q channels.

3. The RF transmitting device as claimed in claim 2, wherein said local frequencies generated from said digital local oscillator within each of said plurality of digital modulators are generated at frequency assignment intervals, that is, the frequency of 1.25 MHz intervals.

4. The RF transmitting device as claimed in claim 1, wherein the modulated signals in said digital unit are coupled serially in the same manner that the modulated signal in the Nth digital modulator of said plurality of digital modulators is outputted to the N−

1th digital modulator and primarily coupled to the modulated signal corresponding to the N−

1th frequency assignment in the N−

1th digital modulator, and the primarily coupled N+(N−

1)th frequency assignment modulated signal is outputted to the N−

2th digital modulator and secondarily coupled to the modulated signal corresponding to the N−

2th frequency assignment in the N−

2th digital modulator, whereby the secondarily coupled multi-frequency assignment modulated signal is outputted to said D/A converter.

5. The RF transmitting device as claimed in claim 1, wherein said first frequency up-converter comprises:

a first local oscillator for generating a fixed local frequency to convert the analog signal inputted into the IF signal; and

a first mixer for mixing the fixed local frequency signal generated from said first local oscillator and the analog signal inputted and converting the mixed result into the IF signal having a constant center frequency of the multi-frequency assignment band.

8. The RF transmitting device as claimed in claim 1, wherein said second frequency up-converter comprises:

a second local oscillator for generating a fixed local frequency to convert the filtered IF signal inputted into the RF signal; and

a second mixer for mixing the fixed local frequency signal generated from said second local oscillator and the IF signal and converting the mixed result into the RF signal having a constant center frequency of the multi-frequency assignment band.

6. An RF transmitting device of a mobile radio communication base station system in a CDMA system having a plurality of channel cards providing baseband signals on I/Q channels for multi-frequency assignment and a transmitting antenna, said RF transmitting device comprising:

a plurality of digital modulators for performing a QPSK modulation for each of the CDMA baseband signals outputted from the plurality of channel card by each frequency assignment, wherein each digital modulator comprises (i) a low-pass filter for low-pass filtering the baseband signals on the I/Q channels (ii) an interpolation filter for filtering the low-pass filtered baseband signals on the I/Q channels, (iii) a digital local oscillator for outputting local frequencies, (iv) a mixer for mixing each of the local frequencies from said local oscillator and each of the baseband signals on the I/Q channels which are sequentially passed through said low-pass filter and said interpolation filter;

a coupler for coupling the digital modulated signals;

a D/A converter for converting the coupled multi-frequency assignment QPSK modulated signal in said coupler into an analog signal and outputting the converted analog signal to an analog frequency up-converting unit;

said analog frequency up-converting unit comprising a first frequency up-converter for converting the multi-frequency assignment analog modulated signal outputted from said D/A converter into an arbitrary IF signal, a SAW band-pass filter having the bandwidth of 3.75 MHz for filtering the up-converted multi-frequency assignment IF signal in said first frequency up-converter to an arbitrary bandwidth, and a second frequency up-converter for converting the filtered multi-frequency assignment IF signal in said band-pass filter into an RF signal to thereby output the converted RF signal to a transmitting unit; and

said transmitting unit for amplifying the up-converted RF signal in said second frequency up-converter of said analog frequency up-converting unit to an arbitrary transmitting output level and transmitting the amplified signal via said transmitting antenna.

7. An RF transmitting device of a mobile radio communication base station system in a CDMA system having a plurality of channel cards providing baseband signals on I/Q channels for multi-frequency assignment and a transmitting antenna, said RF transmitting device comprising:

a plurality of digital modulators for executing a QPSK modulation for each of the CDMA baseband signals outputted by said plurality of channel cards and serially coupling the QPSK modulated signal in a most significant frequency assignment or a least significant frequency assignment with the QPSK modulated signal in a more significant frequency assignment or a less significant frequency assignment, in a sequential order, to thereby output a digital modulated signal in a multi-frequency assignment band, wherein each of said digital modulators comprises a digital local oscillator for outputting one of a plurality of local frequencies, and a digital mixer for generating mixed signals by mixing the baseband signals on the I/Q channels with respective ones of the plurality of local frequencies;

a coupler connected to the digital modulators for generating a coupled multi-frequency QPSK modulated signal;

a D/A converter for converting the coupled multi-frequency QPSK modulated signal outputted from the most significant frequency assignment or the least significant frequency assignment digital modulator into an analog signal to thereby output the converted analog signal to an analog frequency up-converting unit;

said analog frequency up-converting unit comprising a first frequency up-converter for up-converting the coupled multi-frequency assignment analog signal outputted from said D/A converter into an arbitrary IF signal, a SAW band-pass filter having the bandwidth of 3.75 MHz, for band-pass filtering the coupled multi-frequency assignment IF signal outputted from said first frequency up-converter to an arbitrary bandwidth, and a second frequency up-converter for converting the multi-frequency assignment IF signal filtered in said band-pass filter into an RF signal to thereby output the converted RF signal to a transmitting unit; and

said transmitting unit for amplifying the up-converted RF signal in said second frequency up-converter of said analog frequency up-converting unit to an arbitrary transmitting output level and transmitting the amplified signal via said transmitting antenna.