Antenna diversity arrangement and method

• US 8,228,840 B2
• Filed: 06/15/2004
• Issued: 07/24/2012
• Est. Priority Date: 06/15/2004
• Status: Expired due to Fees

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Skärby, Ulf
• Primary Examiner(s): Ferris, Derrick
• Assistant Examiner(s): ANWAR, MOHAMMAD S
• Application Number:
  US11/629,069
• Publication Number:
  US 20080119197A1
• Time in Patent Office: 2,961 Days
• Field of Search: 370/342, 370/343, 370/344, 370/328
• US Class Current: 370/328
• CPC Class Codes: H01Q 21/30 Combinations of separate antenna units operating in different wavebands and connected to a common feeder system
• CPC Class Codes: H04B 7/0848 Joint weighting

Abstract

An antenna diversity arrangement and a radio base station in a frequency divided mobile cellular system with sectorized cells are described. Space diversity or polarization diversity is provided by providing at least two branches. In accordance with the invention an operator frequency band is divided into a plurality of bands for transmitting and receiving. All sectors are branch wise combined in a respective tower mounted amplifier. TX signals within the TX bands belonging to a TMA are diplexed and simultaneously transmitted on the sectors. RF signals received on one branch of a sector are combined with RF signals received on the corresponding sector in the other branches. The RX signals so combined are fed to the radio base station on a single feeder together with the TX signals fed in the opposite direction from transceivers of the base station to the same TMA. A sector may be assigned two or more TX frequencies. Frequency hopping within each TX band may optionally be provided (synth hopping). If two or more TX frequencies are assigned to a sector synth hopping may be combined with frequency hopping between the TX bands assigned to the sector in the A branch as well as the TX bands assigned to the corresponding sector in the B branch.

Claims

1. A method for reducing the number of feeders between a radio base station and a diversity antenna system at a base station site of a frequency divided mobile cellular system with sectorized cells, the diversity antenna system comprising combinations of antennas for transmitting and receiving in a respective cell sector, each such antenna combination comprising at least two branches for providing diversity, an operator of said cellular system being assigned a predefined operator frequency band which in its turn is divided into a plurality of bands, each for transmitting and receiving, the method comprising:

assigning each sector one RX band and one TX band,

dividing the assigned TX bands into one or more sub bands so as to provide two or more diversity branches,

branch-wise diplexing the TX bands assigned to the sectors of a branch so that in each sector of a branch, signals are transmitted on the TX band assigned to this sector,

sector-wise combining signals received in a sector'"'"'s own assigned RX band with signals received in the other sectors at the same branch, and

transmitting the diplexed TX signals and receiving the combined RX signals in all sectors of a branch on a single feeder.

2. A method in accordance with claim 1, further comprising:

dividing said TX band into multiple TX sub-bands and dividing said RX band multiple RX sub-bands.

3. A method in accordance with claim 2, further comprising assigning some of the TX sub-bands and some of the RX sub-bands to a first radio base station and assigning others of the TX sub-bands and others of the RX sub-bands to a second radio base station.

4. A method in accordance with claim 2, wherein said TX sub-bands and RX sub-bands are associated with a single radio base station.

5. A method in accordance with claim 4, wherein a call with a mobile station present in a sector of the antenna system is subjected to a synthesizer frequency hopping within a TX frequency sub-band simultaneously as the cell is subjected to a base band frequency hopping among the TX frequency sub-bands assigned to this sector.

6. A method in accordance with claim 2, wherein first ones of the TX sub-bands assigned to the sectors of one branch are spaced apart in frequency by second ones of the TX sub-bands assigned to the corresponding sectors of another branch, the second TX sub-bands thereby acting as guard bands between the first TX sub-bands.

7. A method in accordance with claim 1, wherein each diplexed TX signal is filtered in an individual TX filter.

8. A method in accordance with claim 1, wherein the sector-wise combined RX signals of a branch are filtered, at the site of the antenna arrangement, in individual band pass filters, the band pass filter of an individual sector passing the RX frequency band assigned to this sector plus the RX frequency bands assigned to the same sector in the other branches.

9. An antenna diversity arrangement for a radio base station of a frequency divided mobile cellular system with sectorized cells, the antenna diversity arrangement comprising:

combinations of antennas for transmitting and receiving in a respective cell sector, each such antenna combination comprising at least two branches for providing diversity, an operator of said cellular system being assigned a predefined operator frequency band which in its turn is divided into a plurality of bands for transmitting and receiving, each sector being assigned one RX band and one TX band;

multiple TX-filters in each diversity branch, each of the TX-filters corresponding to a respective TX band and a respective sector;

multiple RX-filters in each diversity branch, each of the RX-filters coupled to a respective low noise amplifier corresponding to a respective sector;

a tower mounted amplifier provided for each branch, the tower-mounted amplifier for an individual branch including;

a splitter for splitting TX signals and sending the split TX signals to the multiple TX-filters corresponding to the sectors of said branch, and a combiner for combining the signals received in a sector'"'"'s assigned RX band with signals received in the other sectors at the same branch; and

a single feeder connected to a respective tower-mounted amplifier for transmission of all TX and RX signals of the branch to which the tower-mounted amplifier belongs.

10. An antenna diversity arrangement in accordance with claim 9, wherein in addition to said one TX band and one RX band, each sector in each branch is assigned one or more further TX bands and one or more further RX bands, and wherein each sector of a branch is provided with one or more further TX filters and one or more further RX filters passing the one or more further RX bands.

11. An antenna diversity arrangement in accordance with claim 10, wherein said one TX filter and said one or more further TX filters are consolidated into one single TX filter passing the respective frequencies associated with the various TX filters.

12. An antenna diversity arrangement in accordance with claim 10, wherein said one or more further TX filters and said one or more further RX filters are associated with a respective individual radio base station.

13. An antenna diversity arrangement in accordance with claim 9, wherein the TX filters associated with the sectors of one branch are spaced apart in frequency by the TX bands of the TX filters associated with the corresponding sectors of another branch, the latter TX bands thus acting as guard bands between the TX frequencies of the TX filters associated with the sectors of said one branch.

14. An antenna diversity arrangement in accordance with claim 9, wherein the combiner and splitter are an integrated unit in the form of a rail which is connected to the feeder.

15. An antenna diversity arrangement in accordance with claim 9, wherein the combiner is a separate unit to which RX signals received in all of the sectors of a tower mounted amplifier are fed via respective RF amplifiers and RX filters, the combiner being connected to a rail, and the rail being connected to the single feeder of the tower mounted amplifier.

16. A radio base station system at a base station site with sectorized cells for use in a frequency divided mobile cellular system, an operator of said cellular system assigned a predefined operator frequency band which in its turn is divided into a plurality of bands, each for transmitting and receiving, the radio base station system comprising:

a radio base station,

a diversity antenna system, coupled to the radio base station, including combinations of antennas for transmitting and receiving in a respective cell sector, each such antenna combination comprising at least two branches for providing diversity,

feeders extending between the diversity antenna system and the radio base station, each sector being assigned one TX band and one RX band,

wherein each branch includes a tower mounted amplifier that includes;

multiple TX filters and multiple RX filters, one TX filter and one RX for each one of the sectors,

a splitter for splitting the respective TX bands assigned to the sectors of said branch, and

a combiner for combining the signals received in a sector'"'"'s assigned RX band with signals received in the other sectors at the same branch, and

a single feeder connected to a respective tower mounted amplifier for transmission of all TX and RX signals of the branch to which the tower mounted amplifier belongs.

17. A radio base station in accordance with claim 16, wherein each sector is assigned one or more additional TX bands and one or more additional RX bands, each additional TX and RX band being associated with a respective additional radio base station, each RBS filter unit connected to the radio base station further comprising a TX filter for each further TX band, each additional RX band being associated with a respective additional band pass RX filter passing at least the operator'"'"'s frequency band, the received RX signal in the feeder to which the RBS filter unit of a branch is connected first passing the band pass RX filter and from there into a duplex TX/RX filter, an amplifier and a coupler from which the RX signal is connected to the additional band pass RX filter the output of which is connected to the additional radio base station.

18. A radio base station in accordance with claim 16, further comprising means providing synthesizer frequency hopping within each assigned TX band and means providing base band frequency hopping among the TX frequencies assigned to an individual sector.

19. A radio base station system in accordance with claim 16, further comprising multiple radio base station (RBS) filter units, one RBS filter unit provided for each branch, the RBS filter units being connected to respective feeders as well as to transceivers provided in the radio base station, an RBS filter unit of a branch comprising a band pass RX filter passing at least the operator'"'"'s frequency band and individual TX filters, each TX filter being associated with a respective sector of the branch to which the RBS filter unit belongs.