Method and apparatus for reducing combiner loss in a multi-sector, omni-base station

• US 8,706,165 B2
• Filed: 12/01/2006
• Issued: 04/22/2014
• Est. Priority Date: 01/25/2006
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Skrby, Ulf, Staudte, Donald
• Primary Examiner(s): Ghebretinsae, Temesghen
• Assistant Examiner(s): Bilodeau, David
• Application Number:
  US11/607,082
• Publication Number:
  US 20070173288A1
• Time in Patent Office: 2,699 Days
• Field of Search: 455/562.1, 455/561, 455272-2791, 343/751
• US Class Current: 455/562.1
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

An omni-radio base station with multiple sector antenna units uses frequency division of sector signals to achieve increased coverage or capacity at reduced cost. Each sector antenna unit has an antenna for receiving a carrier signal associated with an antenna frequency in an available frequency band. At least one of the antenna units has an associated frequency converter that converts the carrier signal received by that antenna unit from the antenna frequency to a different respective frequency. Even though each sector receives the same carrier signal, an output carrier signal associated with each sector is at a different frequency band. A combiner combines the antenna unit carrier signals at different frequencies to create a composite signal for communication to the omni-radio base station. Because the antenna unit signals combined are at different frequencies, they do not interfere as much as they would if they were at the same antenna frequency, which results in less signal loss and degradation in the combiner. The carrier signals are then restored in the base station transceiver from the different respective frequencies to intermediate frequency for further processing.

Claims

1. An apparatus for use in a multi-sector omni-radio base station providing radio communications coverage for a geographic site area that is divided into a plurality of sectors, comprising:

multiple sector antenna units, each sector antenna unit providing radio communications coverage for a particular sector that differs from the sectors covered by others of the multiple sector antenna units, and each of the multiple sector antenna units having an antenna for transmitting downlink transmissions and for receiving a carrier signal associated with a receive antenna frequency in an available frequency band;

a frequency converter for frequency converting the carrier signal received by one of the multiple sector antenna units from the receive antenna frequency to a respective frequency different from the receive antenna frequency; and

a splitter/combiner for;

receiving a downlink signal with a total transmission power and splitting the downlink signal into a plurality of identical split signals to be transmitted by the multiple sector antenna units, each of the split signals having a respective portion of the total transmission power of the received downlink signal, where each of the sector antenna units transmits its respective split signal at a same base station transmit frequency with the respective portion of the total transmit power; and

combining in the uplink direction carrier signals received from multiple different sectors by corresponding ones of the multiple sector antenna units to create a composite signal containing information received from multiple different sectors for communication to the multi-sector omni-radio base station,

wherein at least two of the carrier signals associated with the multiple sector antenna units and combined in the combiner are at a different frequency.

2. The apparatus in claim 1, wherein the number of multiple sector antenna units having a corresponding frequency converter is less than the number of multiple sector antenna units.

3. The apparatus in claim 1, wherein the number of multiple sector antenna units having a corresponding frequency converter is the same as the number of multiple sector antenna units.

4. The apparatus in claim 1, wherein the splitter/combiner is configured to combine carrier signals associated with each of the multiple sector antenna units to create a composite signal in which all of the carrier signals combined are associated with a different frequency.

5. The apparatus in claim 1, wherein the splitter/combiner is configured to combine received carrier signals associated with each of the multiple sector antenna units to create a composite signal in which some of the carrier signals to be combined are at a different frequency.

6. The apparatus in claim 1, wherein the frequency converter includes:

a first local oscillator (LO) for providing a first LO frequency signal;

a first mixer for frequency converting the carrier signal using the first LO frequency signal to an intermediate frequency (IF) signal;

a narrowband IF filter for filtering the IF signal;

a second local oscillator for providing a second LO frequency signal corresponding to the respective frequency band;

a second mixer for mixing the second LO frequency signal and the intermediate frequency signal to generate a frequency converted output; and

a filter for filtering the frequency converted output to the respective frequency.

7. The apparatus in claim 1, wherein the frequency converter includes:

a first local oscillator (LO) for providing a first LO frequency signal corresponding to the respective frequency;

a first mixer for frequency converting the associated carrier signal using the first LO frequency signal; and

a narrowband filter for filtering an output of the first mixer to the respective frequency.

8. The apparatus in claim 7, further comprising:

a feeder coupled to the splitter/combiner for transporting the composite signal, and

a base station unit coupled to the feeder for extracting each of the carrier signals corresponding to the multiple sector antenna units from the composite signal, the base station unit including one or more base station mixers, each base station mixer is configured to frequency convert a corresponding one of the respective carrier signals associated with a different frequency to an intermediate frequency or to baseband for further processing.

9. The apparatus in claim 8, wherein a first base station mixer is configured to receive a local oscillator signal to facilitate downconverting to intermediate frequency or baseband of one of the subbands of the feeder and a second base station mixer is configured to receive another local oscillator signal to facilitate downconverting to intermediate frequency or baseband of another of the subbands of the feeder.

10. The apparatus in claim 1, wherein one or more frequency converters are included in a corresponding one or more of the multiple sector antenna units.

11. The apparatus in claim 1, wherein one or more frequency converters each corresponding one of the multiple sector antenna units is included in the splitter/combiner.

12. The apparatus in claim 1, wherein if there are multiple respective different frequency bands, those respective different frequencies are distributed over the available frequency band.

13. The apparatus in claim 12, wherein those respective frequency bands are evenly distributed over the available frequency band.

14. The apparatus in claim 1, wherein each antenna unit is a tower mounted amplifier (TMA) unit including a receiver filter corresponding to the available bandwidth coupled to an amplifier for amplifying the received signal.

15. The apparatus in claim 1, wherein the frequency converter and the splitter/combiner are combined into a single unit or are separate units.

16. The apparatus in claim 1, further comprising:

a feeder coupled to the splitter/combiner for transporting the composite signal, and

a base station unit coupled to the feeder for extracting each of the carrier signals from the composite signal.

17. The apparatus in claim 16, wherein the base station unit includes a transceiver having one or more mixers each of which is configured to frequency convert a respective carrier signal to an intermediate frequency or to baseband for further processing.

18. The apparatus in claim 1, wherein each sector includes a first diversity antenna unit and a second diversity antenna unit.

19. The apparatus in claim 18, wherein the splitter/combiner includes:

a first splitter/combiner for combining carrier signals associated with each of the first diversity antenna units to create a first composite signal for communication to the multi-sector omni-radio base station, and

a second splitter/combiner for combining carrier signals associated with each of the second diversity antenna units to create a second composite signal for communication to the multi-sector omni-radio base station.

20. The apparatus in claim 19, further comprising:

a first feeder coupled to the first splitter/combiner for transporting the first composite signal;

a second feeder coupled to the second splitter/combiner for transporting the second composite signal; and

a base station unit coupled to the first and second feeders for extracting each of the carrier signals corresponding to the multiple sector antenna units from the first and second composite signals, the base station unit including one or more base station mixers, each base station mixer is configured to frequency convert a corresponding one of the respective carrier signals associated with a different frequency to an intermediate frequency or baseband for further processing.

21. The apparatus in claim 18, wherein the splitter/combiner is configured to combine carrier signals associated with each of the first and second diversity antenna units to create the composite signal for communication to the multi-sector omni-radio base station.

22. The apparatus in claim 21, further comprising:

a feeder coupled to the splitter/combiner for transporting the composite signal, and

a base station unit coupled to the feeder for extracting each of the received carrier signals corresponding to the multiple sector antenna units from the composite signal, the base station unit including one or more base station mixers, each base station mixer is configured to frequency convert a corresponding one of the respective received carrier signals associated with a different frequency to an intermediate frequency or baseband for further processing.

23. The apparatus in claim 1, wherein one or more narrowband filters are included in the splitter/combiner.

24. A method for use in multi-sector omni-radio base station including multiple sector antenna units each having an antenna, the multi-sector omni-radio base station providing radio communications coverage for a geographic site area that is divided into a plurality of sectors, and comprising:

each of the multiple sector antenna units providing radio communications coverage for a particular sector that differs from the sectors covered by others of the multiple sector antenna units by transmitting downlink transmissions and receiving a carrier signal associated with a receive antenna frequency in an available frequency band;

frequency converting the carrier signal received by one of the multiple sector antenna units from the receive antenna frequency to a respective frequency different from the receive antenna frequency;

combining in the uplink direction in a splitter/combiner carrier signals received from multiple different sectors by corresponding ones of the multiple sector antenna units to create a composite signal containing information received from multiple different sectors for communication to the multi-sector omni-radio base station;

receiving a downlink signal with a total transmission power at the splitter/combiner; and

splitting in the splitter/combiner the downlink signal into a plurality of identical split signals to be transmitted by the multiple sector antenna units, each of the split signals having a respective portion of the total transmission power of the received downlink signal, where each of the sector antenna units transmits its respective split signal at a same base station transmit frequency with the respective portion of the total transmit power,

wherein at least two of the carrier signals associated with the multiple sector antenna units and combined in the splitter/combiner are at a different frequency.

25. The method in claim 24, wherein the number of multiple sector antenna units for which a corresponding frequency conversion is performed is less than the number of multiple sector antenna units.

26. The method in claim 24, wherein the number of multiple sector antenna units for which a corresponding frequency conversion is performed is the same as the number of multiple sector antenna units.

27. The method in claim 24, wherein the combining includes combining carrier signals associated with each of the multiple sector antenna units to create a composite signal in which all of the carrier signals to be combined are at a different frequency.

28. The method in claim 24, wherein the combining includes combining carrier signals associated with each of the multiple sector antenna units to create a composite signal in which some of the carrier signals to be combined are at a different frequency.

29. The method in claim 24, wherein the frequency converting includes:

providing a first local oscillator (LO) frequency signal;

frequency converting the carrier signal using the first LO frequency signal to an intermediate frequency signal;

using a narrowband intermediate frequency to filter the intermediate frequency signal;

providing a second LO frequency signal corresponding to the respective frequency band;

mixing the second LO frequency signal and the filtered intermediate frequency signal and mixing them to generate a frequency converted output; and

bandpass filtering the frequency converted output to the respective frequency.

30. The method in claim 24, wherein the frequency converter includes:

providing a first local oscillator (LO) frequency signal corresponding to the respective frequency;

frequency converting the associated carrier signal using the first LO frequency signal to generate a frequency converted output; and

narrowband filtering the frequency converted output to the respective frequency.

31. The method in claim 30, further comprising:

transporting the composite signal over a feeder to a base station unit, and

extracting at the base station unit each of the carrier signals corresponding to the multiple sector antenna units from the composite signal including frequency converting at least one respective carrier signal associated with a different frequency to an intermediate frequency or baseband for further processing.

32. The method in claim 31, wherein at least two base station mixers in the base station unit each receives a different local oscillator signal.

33. The method in claim 24, wherein if there are multiple respective different frequencies, those respective different frequencies are distributed over the available frequency band.

34. The method in claim 33, wherein those respective frequencies are evenly distributed over the available frequency band.

35. The method in claim 24, further comprising:

transporting the composite signal over a feeder to a base station unit, and

extracting each of the carrier signals from the composite signal at the base station unit.

36. The method in claim 35, wherein each sector includes a first diversity antenna unit and a second diversity antenna unit.

37. The method in claim 36, wherein the combining includes:

combining in a first splitter/combiner carrier signals associated with each of the first diversity antenna units to create a first composite signal for communication to the multi-sector omni-radio base station, and

combining in a second splitter/combiner carrier signals associated with each of the second diversity antenna units to create a second composite signal for communication to the multi-sector omni-radio base station.

38. The method in claim 37, further comprising:

transporting the first composite signal over a first feeder;

transporting the second composite signal over a second feeder; and

extracting at the base station unit each of the carrier signals corresponding to the multiple sector antenna units from the first and second composite signals including frequency converting at least one respective carrier signal associated with a different frequency to an intermediate frequency or baseband for further processing.

39. The method in claim 36, wherein the combining includes combining carrier signals associated with each of the first and second diversity antenna units to create the composite signal for communication to the multi-sector omni-radio base station.

40. The method in claim 39, further comprising:

transporting the composite signal over a feeder, and

extracting at the base station unit each of the carrier signals corresponding to the multiple sector antenna units from the composite signal including frequency converting at least one respective carrier signal associated with a different frequency to an intermediate frequency or baseband for further processing.