Communication device having a wideband receiver and operating method therefor

• US 6,363,262 B1
• Filed: 12/22/1998
• Issued: 03/26/2002
• Est. Priority Date: 12/23/1997
• Status: Expired due to Term

• Current Assignee: Ericsson AB (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: McNicol, John Duncan
• Primary Examiner(s): Kincaid, Lester G.
• Application Number:
  US09/218,234
• Time in Patent Office: 1,190 Days
• Field of Search: 455/552, 455/553, 455/561, 455/562, 455/132, 455/133, 455/136, 455/137, 455/141, 455/254, 455/255, 455/256, 455/266, 455/303, 455/306, 455/307, 455/313, 455/317, 455/318, 455/323, 455/339, 455/340, 370/347
• US Class Current: 455/561
• CPC Class Codes: H04B 1/0003 Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00
• CPC Class Codes: H04B 1/001 Channel filtering, i.e. selecting a frequency channel within the SDR system multiplexing of multicarrier modulation signals being represented by different frequencies H04L5/06; multiplexing of multicarrier modulation signals H04L5/023
• CPC Class Codes: H04B 1/0017 Digital filtering H04B1/001 takes precedence; digital filters per se H03H17/00
• CPC Class Codes: H04B 1/26 for superheterodyne receivers multiple frequency-changing H03D7/16
• CPC Class Codes: H04B 1/707 using direct sequence modulation

Abstract

To accommodate for a release of uncleared spectrum in a wideband communication system (10) while improving isolation in a receiver (FIG. 4) between wideband carriers, a common intermediate frequency converter down-converts differing but relatively high frequency carriers, incident to the receiver, to corresponding differing but relatively low frequency carriers. Receiver chains (174-176) response to the plurality of relatively low frequency carriers each have a filter (140-144) arranged to isolate selected ones of the relatively low frequency carriers. In a radio frequency communication system having three or more frequency sequential carriers, the receiver chains (174-176) may include branches that have filters that further isolate carriers within the receiver by applying non-sequential carriers to the branches in each receiver chain.

Claims

1. A receiver circuit for a communication device, the receiver circuit arranged to receive a plurality of carriers having relatively high but differing frequencies, the receiver circuit comprising:

a frequency converter coupled to receive and arranged to down-convert the plurality of relatively high frequency carriers to a plurality of relatively low but differing frequency carriers; and

a plurality of receiver chain branches coupled to the output of the frequency converter, each receiver chain branch having a filter arranged to isolate selected ones of the plurality of relatively low frequency carriers thereby facilitating subsequent analog-to-digital conversion.

2. The receiver circuit of claim 1, wherein the plurality of branches contain filters that isolate carriers having a non-contiguous frequency band relationship therebetween.

3. The receiver circuit of claim 2, wherein the non-contiguous frequency band relationship is a next but one frequency band relationship.

4. The receiver circuit of claim 1, wherein each of the plurality of receiver chain branches further comprises a series combination of an analog-to-digital converter and a receiver demodulator for recovering information from selected ones of the plurality of relatively low frequency carriers.

5. The receiver circuit of claim 1, wherein each receiver chain has at least one programmable switch positioned next to the filter, the programmable switch selectively operational to isolate an associated carrier from the receiver circuit.

6. The receiver circuit of claim 1, wherein one of the plurality of receiver chains is allocated to a relatively high frequency carrier having an uncleared spectrum.

7. The receiver circuit of claim 1, wherein each of the plurality of branches contains an isolation means for isolating the branch from its receiver chain.

8. The receiver circuit of claim 7, wherein the isolation means is one of a variable attenuator and a switch.

9. The receiver circuit of claim 7, wherein said each of the plurality of branches shares a common digitizing circuit.

10. The receiver circuit of claim 1, wherein each carrier has a dedicated channel demodulator for recovering modulated information.

11. The receiver circuit of claim 1, wherein said each of the plurality receiver chains shares a common digitizing circuit.

12. The receiver circuit of claim 1, wherein each carrier has a dedicated channel demodulator for recovering modulated information.

13. The receiver circuit of claim 12, wherein each dedicated channel demodulator is coupled to the common digitizing circuit.

14. The receiver circuit of claim 1, wherein each receiver chain includes an intermediate frequency amplifier coupled to the filter and coupled to receive the relatively low frequency carriers.

15. The receiver circuit of claim 1, wherein the receiver circuit is in a transceiver.

16. The receiver circuit of claim 15, wherein the transceiver is a base station that preferably supports code division multiple access communication.

17. The receiver circuit of claim 1, wherein a number of the outputs of the plurality of receiver chain branches are coupled to a series combination of a combiner and an analog to digital converter.

18. A base station for a communication system having a universal frequency re-use scheme, the base station having a receiver circuit arranged to receive a plurality of modulated wideband carriers having relatively high but differing frequencies, the receiver circuit comprising:

a frequency converter coupled to receive the plurality of modulated wideband carriers and arranged to down-convert the relatively high frequencies to a plurality of relatively low but differing frequency carriers; and

a plurality of receiver chain branches coupled to the output of the frequency converter each receiver chain branch having a filter arranged to isolate selected ones of the plurality of relatively low frequency carriers, thereby facilitating subsequent analong-to-digital conversion.

19. The receiver circuit of claim 18, wherein the plurality of branches contain filters that isolate wideband carriers having a non-contiguous frequency band relationship therebetween.

20. The receiver circuit of claim 19, wherein the non-contiguous frequency band relationship is a next but one frequency band relationship.

21. The base station of claim 18, wherein a number of the outputs of the plurality of receiver chain branches are coupled to a series combination of a combiner and an analog to digital converter.

22. A method of isolating a plurality of carriers incident to a receiver of a radio frequency communication system having a universal frequency re-use pattern, the plurality of carriers having relatively high but differing frequencies, the method comprising the steps of:

applying the plurality of carriers to a common frequency converter arranged to down-convert the relatively high frequencies to a plurality of relatively low but differing frequency carriers; and

isolating selected ones of the plurality of relatively low frequency carriers by applying the plurality of relatively low frequency carriers to a plurality of receiver chain branches coupled to the output of the frequency converter, each branch having a dedicated band-pass filter, thereby facilitating subsequent analog-to-digital conversion.