(12) United States Patent
`US 7,133,697 B2
`(10) Patent No.:
`Judd et al.
`Nov.7, 2006
`(45) Date of Patent:
`
`
`US007133697B2
`
`8/1997 Dupuy oo... ASS/1L5
`9/1998 Grandfield et al.
`.. 455/20
`9/1998 Niki oe
`11/1998 Macdonald et al.
`.
`
`3/1999 Atkinson ..........
`370/279
`...
`». 455/16
`3/1999 Chuet al.
`
`4/2000 Wickman ......
`we 455/422
`
`10/2000 Wilson et al. we. 455/111
`6/2001 Elrefaie et al... 455/426
`1/2004 Karacaoglu et al.
`
`2/2004 Komara ct al... 370/342
`
`AA
`
`5,659,879
`5,802,452
`5,812,933 A
`5,835,128 A
`5,883,884
`5,890,055
`6,047,177
`6,141,533 A
`6,243,577 Bl
`6,684,058 B1*
`6,690,662 B1*
`
`AAA
`
`FOREIGN PATENT DOCUMENTS
`
`DE
`EP
`EP
`EP
`EP
`EP
`WO
`WO
`WO
`
`8/1991
`40 08 165
`0714218 Al * 11/1994
`0714218 Al
`5/1996
`0756392 A2* 7/1996
`0 756 392
`1/1997
`1 143 554
`10/2001
`W) 97/32442
`9/1997
`WO 97/3244? Al
`9/1997
`WO01/11797
`{2001
`
`*
`
`* cited by examiner
`
`Primary Examiner—Nay Maung
`Assistant Examiner—Angelica M. Perez
`(74) Attorney, Agent, or Firm—Wood, Herron & Evans,
`L.L.P.
`
`(57)
`
`ABSTRACT
`
`A translation unit for use in a wireless communications
`system compriscs translation circuitry configured to be
`interfaced between an RF antenna network and a backhaul
`network. The translation circuitry is operable fortranslating
`the frequencyof signals directly between an RF network and
`a backhaul network without conversion to audio in order to
`provide direct communications betweena base station and a
`backhaul destination.
`
`34 Claims, 11 Drawing Sheets
`
`16a
`
`(54)
`
`(75)
`
`TRANSLATION UNIT FOR WIRELESS
`COMMUNICATIONS SYSTEM
`
`Inventors: Mano D. Judd, Rockwall, TX (US);
`Kevin W. Ommeodt, Allen, TX (US);
`Johnsy C. Varghese, The Colony, TX
`(US)
`
`(73)
`
`Assignee: Andrew Corporation, Westchester, IL
`(US)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 450 days.
`
`(21)
`
`Appl. No.: 10/145,298
`
`(22)
`
`Tiled:
`
`May 14, 2002
`
`(65)
`
`Prior Publication Data
`
`US 2003/0036410 Al
`
`Feb. 20, 2003
`
`Related U.S. Application Data
`
`(60)
`
`Provisional application No. 60/290,882,filed on May
`14, 2001.
`
`Int. Cl.
`(2006.01)
`HO4B 138
`US. Che cece 455/561; 455/11.1; 455/560
`Field of Classification Search............... 455/11.1,
`455/561, 560, 7
`See application file for complete search history.
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,783,843 A
`4,941,200 A
`5,509,028 A
`5,604,789 A
`
`11/1988 Leff et al. ..... ee 455/22
`7/1990 Leslie et al.
`.....
`ee ASS/17
`. 375/211
`4/1996 Marque-Pucheu
`2/1997 Lerman wc. 379/59
`
`14a
`
`
`
`RF TO pW
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`uW TO RF
`
`AMPLIFIERS
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`
`
`
`
`80
`
`Page 1 of 20
`
`SAMSUNG EXHIBIT 1034
`
`Page 1 of 20
`
`SAMSUNG EXHIBIT 1034
`
`

`

`U.S. Patent
`
`Nov.7, 2006
`
`Sheet 1 of 11
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`US 7,133,697 B2
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`Page 2 of 20
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`U.S. Patent
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`Nov.7, 2006
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`Nov.7, 2006
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`US 7,133,697 B2
`
`2
`pression,it would be necessary to purchase a greater amount
`of expensive microwave backhaul bandwidth for the back-
`haul function.
`It is therefore desirable to reduce, and even eliminate, the
`expensive modulation’ demodulation hardware associated
`with the base station and its backhaul functions. More
`specifically, it is desirable to eliminate the need for compli-
`cated DSP functions and associated hardware at the base
`station.
`
`It is further desirable to simplify the base station and
`reduceits overall construction and maintenancecosts, while
`still maintaining the convenient and desirable microwave
`backhaul function.
`It
`is further desirable to achicve these goals without
`having to purchase an increased amount of an expensive
`backhaul bandwidth from the traditional microwave back-
`
`haul spectrum.
`These goals and improvements, and other features, are
`addressed by the present invention.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`1
`TRANSLATION UNIT FOR WIRELESS
`COMMUNICATIONS SYSTEM
`
`RELATED APPLICATIONS
`
`This application claims the filing benefit of Provisional
`Application U.S. Ser. No. 60/290,882, filed May 14, 2001,
`entitled “Translation Unit for Wireless Communications
`System”, the disclosure of which is hereby incorporated
`herein byreference in its entirety.
`
`
`
`FIELD OF THE INVENTION
`
`‘This invention is directed generally to wireless commu-
`nications and moreparticularly to an improvementin cell
`tower electronics for such a communications system.
`
`BACKGROUND OF THE INVENTION
`
`In many wireless communication stations, such as cellu-
`lar/PCS base stations, RF communication signals are
`received by an antenna at the top of a tower, routed down to
`equipment at the base of a tower (“base station”), down-
`converted from RF, and demodulated to audio. For further
`processing, the signals are then routed back to a Mobile
`Switching Center (MSC), Central Office (CO), or other
`facility, using, another wireless communicationlink or using,
`a wired link, such as a T1 line. This routing back to the
`MSC/CO is referred to as backhaul.
`
`About 80% ofall base stations route the signals back to
`the MSC/CO via a microwave backhaul link. That is, the
`base station signals are converted to microwave backhaul.
`More specifically, at the base station, the audio signals are
`arranged or stacked and are upconverted to IF. The signals
`are then remadulated, usually using a different modulation
`scheme, and converted to a microwave frequency. They are
`then amplified and transmitted out via a microwave antenna
`or dish. The modulation and other signal processing is
`traditionally handled at the groundlevel of the tower, while
`the conversion to a microwave spectrum may be handled on
`the ground or on the tower. The primary reason for this
`whole complicated loop is that the RF Cellular/PCS signals
`are spread apart in the RF band, due to frequency re-use, and
`often occupy distinct bands, like a comb. For example, in a
`typical TDMAsystem, total comb bandwidth is around 12.5
`MHz. However, the microwave link bandwidths are often
`much narrower.
`In orderto limit the microwave bandwidth which must be
`purchased in order to facilitate the backhaul,
`the base
`stations have had to utilize expensive modulation/demodu-
`lation equipmentutilizing digital signal processing or DSP
`and other supporting circuitry at
`the base station. For
`example, the RF wireless communication signals have to be
`up/down converted and modulated/demodulated down to
`audio, and then again up/down converted and modulated/
`demodulated for the microwave backhaul and have to be
`multiplexed from the RF side with the microwave hardware.
`For microwavetransmissions, the multiplexed audio streams
`are modulated/demodulated with a different modulation
`scheme, such as QAM 256, and are up/down converted with
`respect to the microwave band. The modulation hardware
`and associated DSP functions are expensive and must be
`duplicated at all base stations using microwave backhaul.
`Because the base station hardware takes a larger RF band-
`width and backhauls it over a smaller microwave bandwidth,
`the base station hardware is considered to provide a spec-
`trum compression mechanism. Without such spectrum com-
`
`10
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`15
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`20
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`30
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`5
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`Page 13 of 20
`
`The accompanying drawings, which are incorporated in
`and constitute a part ofthis specification, illustrate embodi-
`ments of the invention and, together with a general descrip-
`tion of the invention given above, and the detailed descrip-
`tion of the embodiments given below, serve to explain the
`principles of the invention.
`FIG. 1 is a schematic diagram showing a tower and base
`station in accordance with thetraditional backhaul capabili-
`ties;
`FIG. 2 is a block diagram of base station hardware for
`traditional backhaul capabilities.
`FIG. 3 is a schematic diagramof a tower and basestation,
`in accordance with one embodimentof the invention;
`FIG. 4 is a schematic diagram of an embodimentof the
`invention;
`FIGS.5, 6, and 7 are block diagrams showing electronics
`in accordance with several embodiments of the invention;
`FIG. 8 is a block diagram in accordance with another
`embodiment of the invention; and
`FIG. 9 is a block diagram of one embodimentofa three
`sector system configured in accordance with principles of
`the invention.
`TIG. 10 illustrates a block diagram of another embodi-
`ment of the invention.
`FIG. 11 illustrates a block diagram of another embodi-
`ment of the invention.
`FIG. 12 illustrates a block diagram of another embodi-
`ment of the invention.
`
`FIG. 13 illustrates a block diagram of another embodi-
`ment of the invention.
`
` DETAILED DESCRIPTION OF THI
`
`eal
`
`
`
`ILLUSTRATED EMBODIMENT
`
`Referring now to the drawings, and initially to FIG. 1, a
`cell tower or base station and towerinstallation in accor-
`dance with traditional backhaul capabilities is illustrated for
`the purposes of explaining the invention. Theinstallation 10
`includes a tower 12 or other suitable structure, for mounting,
`one or morebase station antennas 14, 15 (e.g. for transmit
`and receive) well above ground level. In accordance with
`traditional backhaul in such installations, communications
`with a switching center or central office (MSC/CO) are
`accommodated through a backhaul link which in FIG. 1 is
`illustrated as a microwave backhaul link, utilizing a micro-
`
`Page 13 of 20
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`

`

`US 7,133,697 B2
`
`3
`wave antenna 16, also mounted at or near the top of the
`tower or other structure 12. Respective cables 18 and 20
`connect the antennas 14, 15 and the backhaul link antenna
`16 to base station electronics 30 which provide the proper
`processing and interface between the RF side and the
`microwave backhaul.
`in the cellular/PCS base station
`As mentioned above,
`equipment of this type, an RF signal is utilized to commu-
`nicate with a plurality of mobile units or individual users 24.
`In this regard, the cellular or PCS signals are spread apart,
`often occupying relatively small or narrow bands in a
`comb-like fashion. To handlethetraffic, the entire comb-like
`bandwidth must be processed and backhauled, which
`includes around 12.5 MIIz of bandwidth. Typically,
`the
`bandwidth of the microwave backhaullink using the antenna
`16 is much narrowerthan the 12.5 MHz RF communication
`
`bandwidth. Accordingly, in order to utilize the backhaullink
`or antenna 16, the base station electronics 30 must perform
`all of the necessary and expensive digital signal processing
`(DSP). compression, and conversion between the RFsignals
`transmitted and reccived by antennas 14, 15 and the micro-
`wave backhaul signals transmitted and received by antenna
`16.
`
`Because of the difference in spectral efficiency between
`the RF spectrum and the microwave backhaul spectrum,
`service providers have found it necessary to maintain the
`expensive DSP hardware at each basestation site to handle
`the modulation/demodulation and compression between the
`RF and backhaul spectrums. An example maybeillustrative.
`For AMPS, cellular or TDMA (IS-136), the bandwidth
`requirement can be estimated as follows:
`the cell site
`In TDMA, using k—7 frequency re-use,
`spectral efficiency is around 7x0.8 bps/Hz=0.11 bps/Hz
`without spectrum compression. (bps=bits per second)
`For backhaul, the bps/Hz ratio, or spectral efficiency, is
`often much higher. For example, for 256 QAM modulation,
`the efficiency is around 8 bps/Hz, which is significantly
`more spectrally efficient. Using fixed wireless access (e.g.,
`MMDS), the spectral efficiency may be onthe order of 4-6
`bps/Hz, over a 6 MHz channel. A simple per cell site
`example then, for an FOMA(AMPS)arrangement, assuming
`about 8 kbps per channel, is set forth as:
`
`10
`
`15
`
`20
`
`30
`
`35
`
`40
`
`45
`
`FDMA(AMPS):
`
`K=7>
`K=4—>
`
`Full
`Site Spectrum
`
`60 ch (8 kbps/ch)/12.5 E6 = 0.0384 bps/IIz
`105 ch (8 kbps/ch)/12.5 E6 = 0.0672 bps/Hz
`
`Effective RF Spectrum
`
`Site bits
`
`Backhaul @
`6 bits/Hz
`
`k=712.5MHz
`
`60x (30 KHz)=1.8MHz
`
`480 kbps
`
`80 KHz
`
`Therefore, the RF spectrum requires about 156 times the
`bandwidth as necessary for a backhaul spectrum. Thus, it is
`usually considered better to demodulate and compressat the
`cell-site.
`
`TDMAwithout demodulation and compression provides
`somewhat more favorable efficiency in that the RI’ spectrum
`would require about 52 times the bandwidth as necessary for
`a backhaul spectrum.
`Tor 3G/CDMA systems, assuming a full multicarrier
`(simple translation), and about 0.5 bps/Hz and a backhaul
`efficiency of around 6 bps/Hz,
`the RF spectrum would
`require around 12 times the spectrum as necessary for a
`backhaul spectrum.
`
`60
`
`65
`
`the spectrum
`
`4
`For CDMA, assuming, adjacent carriers,
`efficiency is roughly:
`0.49 bits/Hz using all 64 signals/carrier
`0.25 bits/Hz using only 32 signals/carrier.
`For fixed wireless, the spectral efficiency will improve
`even more, and it is likely that a 1:1 bps/Hz efficiency may
`be achieved betweenthe RI’ system and backhaul spectrum.
`In accordance with one aspect of the present invention,
`the use of expensive modulation/demodulation and DSP
`hardware is reduced and even eliminated from the base
`station. Specifically, modulators and demodulators for con-
`verting from the RF communication bandto a digital audio
`stream, and the modulator/demodulator hardware for pro-
`viding the necessary compression and conversion between
`the RF band and the microwave backhaul spectrum are
`eliminated. In one aspect of the invention, conversion occurs
`directly between the RF spectrum and the backhaul spec-
`trum without modulation and demodulation. The conversion
`occurs completely at the base station and any modulation
`and demodulation involving expensive DSP hardware
`occurs after the backhaul, such as at a MSC. In that way, the
`DSPfunction (and cost) is centralized for a plurality of base
`stations at the MSC/CO.In an embodimentofthe invention,
`the conversion may occur on the tower without being routed
`to base station clectronics on the ground at the base of the
`tower. The present invention may utilize an inexpensive
`backhaul spectrum to handle the complete RF spectrum.
`Alternatively, newer CDMA/3G spectral efficiencies are
`utilized for reducing the required backhaul spectrum. With
`the allocation of the LMDS (Local Multipoint Distribution
`Services) 28 GHz band (some 1300 MHz total bandwidth),
`whichis mostly unused today, and for the foreseeable future,
`a Cellular/PCS provider can obtain 12.5 or 25 MIIz ofthis
`1300 MHz bandwidth, likely at the same price (or lower)
`than they currently pay for a smaller amount of the micro-
`wave backhaul spectrum. The invention recognizes that,
`using this approach, a simple RF to LMDS band (and
`visa-versa) converter at the top of the tower is the only
`significant piece of hardware that would be required. There-
`fore, the cost requirements to compress the spectrum at the
`base station location are removed.
`While one described embodiment may use the above-
`discussed PCS/cellular and LMDS bands, the invention may
`be used in other bands as well. For example, any unused
`(unlicensed) band with sufficient available bandwidth could
`be used in place of the LMDSband. Also, such a system
`could be used to facilitate a wireless backhaul
`link for
`communications systems other than PCS/cellular, i.e., using
`other RF bands.
`In describing the invention, a brief description of a
`traditional backhaul scenario is helpful.
`Referring to FIG. 2,
`the base station electronics 30
`typically include circuitry 32 for downconverting RF signals
`from the antenna 14 to an IF frequency, as well as circuitry
`34 for digitizing the signals and demodulating to audio. In
`the downlink path, signals received by antenna 14 are routed
`on line 18 to an amplifier, such as an LNA 19, before being,
`downconverted to IF. Also, appropriate filters (not shown)
`might be utilized for filtering the individual RF channels
`received al antenna 14 prior to downconverting each channel
`to IF. Demodulatorcircuitry 34 also may include digitizing
`circuitry for digitizing each channel. A digital audio data
`stream is then created for each channel and is multiplexed
`with a multiplexer (MUX) 56 to form a high speed data
`stream. Downlinked signals are then routed on line 62 to
`modulator circuitry 36 where the high speed digitized data
`stream is again modulated (usually with a different modu-
`
`Page 14 of 20
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`US 7,133,697 B2
`
`5
`lation scheme) and upconverted to IF. The IF signals are then
`upconverted to a microwave spectrum with appropriate
`conversion circuitry 38 wherein they are amplified, such as
`with a power amp 40. A diplexer 58 is necessary for
`separating backhaul uplink/downlink signals. Utilizing
`diplexer 58,
`the signals are routed via cable 20 to the
`backhaul antenna 16 for backhauling to a MSC/COorother
`switching center. All the circuitry for up/down conversion
`and modulation/demodulation may be located at the bottom
`ofthe tower. Alternatively, someof the hardware, such as the
`up/down conversion circuitry and the amplifiers might be
`located at the top of the tower proximate the antenna.
`Signals arriving from the central office (CO) via the
`backhaul link antenna 16 would be fed to the basestation
`electronics by the cable 20, through diplexer 58 where they
`are amplified, such as with an LNA 44, and then downcon-
`verted with appropriate circuitry 42 to IF frequencies.
`Appropriate demodulator circuitry demodulates and digi-
`tizes the signals which are then routed, via line 63,
`to be
`demultiplexed by the multiplexer circuitry 56 for transmis-
`sion through antenna 15. The digitized stream of the audio
`base bandis then modulated and converted to appropriate IF
`signals by modulator circuitry 46. The signals are then
`upconverted to an RF band by appropriate conversion cir-
`cuitry 48 for transmission. The signals are amplified, such as
`with a power amplifier 50, and then routed on line 18 to be
`transmitted to customers or mobile units 24.
`Asnoted above, the various modulation circuitry utilized
`incorporates digital
`signal processing (DSP), which is
`expensive and, for a traditional backhaul, must be incorpo-
`rated with each base station. Also, such circuitry is necessary
`for both the RF side and the backhaul side of the system.
`Lines 63 and 62 may be T1 lines, or other high capacity
`lines, which may also be utilized to route the high speed
`stream directly to an MSC/CO, as well as to a backhaul link
`16. In the present invention, the use of wireless backhaul is
`addressed. For use of the microwave antenna backhaullink
`16, the base station modulator circuitry 36 might contain
`circuitry to remodulate the signal, with a high bps/Hertz rate
`such as QAM 256, prior to upconverting the signal
`to
`microwave 38.
`Referring now to FIG.3, in accordance with one embodi-
`ment ofthe invention, the expensive modulation/demodu-
`lation and DSPcircuitryis eliminated from the base station.
`Asystem 10a includes a tower or other structure 12a which
`mounts a base station antenna 14a for an RF wireless
`communication system and a microwave antenna or dish
`16a for a backhaul
`link to a MSC/CO. In the present
`invention,the use of the terms “switching center”or “central
`office” for indicating a destination for the backhaul is not
`meant to be limiting to a particular type of destination. For
`example, multiple base stations might backhaul to another
`base station where DSP and modulation circuitry is present.
`Then, after processing and modulation/demodulation, the
`signals might be further backhauled to a traditional MSC/
`CO. Therefore, for the purposes of the invention, the terms
`“switching center”or “backhaul destination” may also mean
`another base station or some other destination. A translation
`unit 80 is provided at or near the tower top for providing
`bi-directional upconversion and downconversion respec-
`tively between the RF band and a backhaul band (e.g.,
`microwave) used by the backhaul link antenna 16a and
`associated equipment at the MSC/CO.
`In accordance with one aspect of the present invention,
`RF signals from antenna 14a are translated directly to a
`microwave spectrum for backhaul. In one embodiment of
`the invention, a low cost microwave spectrum bandwidthis
`
`40
`
`45
`
`5
`
`6
`used which is similar in size to the bandwidth of the RF
`
`spectrum. In such an embodiment, the difference in spectral
`efficiency between the RF side and the backhaulside is not
`an issue, and expensive DSP circuitry for spectrum com-
`pression is not required. For example, bandwidth from a
`band, such as the I,.MDS band, could be utilized which
`would equal
`the spectrum or bandwidth of the signals
`handled by the RF antenna 14a. The present invention is
`particularly desirable for 3G/CDMAtechnology wherein the
`spectral efficiency is greater and less backhaul bandwidth
`would be necessary.
`In one embodiment, by providing essentially the same
`backhaul bandwidth, in the presently largely unused and low
`cost LMDSband,as is required for the total bandwidth of
`the RF channels, such as cellular/PCS channels, the require-
`ment for compression is eliminated and simple LMDS-to-
`RI and RI'-to-LMDS frequency converters
`are used
`between the two antennas 14a and 16a, thus eliminating the
`need for base station DSP and modulation/demodulation
`
`electronics. Having eliminated the need at the base station
`for processing the signals between the antenna 14a and the
`backhaul
`link antenna 16a, digital processing and other
`processing of the signals for multiple base stations may be
`performed at the MSC/COrather than at cach basestation.
`This significantly reduces the complexity and costs of the
`base station hardware and the costs of the overall systems.
`While one described embodiment
`focuses upon the
`above-discussed PCS/cellular and T.MDS bands, the inven-
`tion may be used in other bands as well. For example, an
`unused (unlicensed) band with sufficient available band-
`width could be used in place ofthe LMDSbandfor backhaul
`purposes. Also, such a system could be used to facilitate a
`wireless backhaul link for communications systems other
`than PCS/cellular, ie., using other RI' bands. The chart
`below lists other bands, for example and without limitation,
`which might be substituted for the RF band (band A), and
`backhaul band (band B), in the embodiment described in
`detail herein:
`
`band A
`
`band B
`
`PCS 1900
`PCS 1900
`3G 1900
`Cellular 800
`Cellular 800
`4G
`WCS 2300
`PCS 1900
`Cell 800
`PCS 1900
`Cell 800
`PCS-1900
`PCS-1900
`Cell 800
`Cell 800
`2400 Unlicensed
`2400 Unlicensed
`5.1 UNII band
`5.1 UNII band
`5.8 UNII band
`5.8 UNII band
`PCS 1900 band
`Cell 800 band
`UMTSband 1900/2100
`UMISband 1900/2100
`UMTSband 1900/2100
`UMTSband 1900/2100
`UMTSband 1900/2100
`
`MMDS 2500
`MMDS2100
`MMDS2500
`PCS 1900
`MMDS2500
`MMDS2500, 2100
`MMDS2500, 2100
`WCS 2300
`WCS 2300
`2400 Unlicensed (802.11 b band)
`2400 Unlicensed (802.11 b band)
`5.1 GHz UNII band
`5.8 GHz UNII band
`5.1 GHZ UNIT band
`5.8 GHz UNII band
`MMDS2100 band
`MMDS2500 band
`MMDS2100 band
`MMDS 2500 band
`MMDS2100 band
`MMDS 2500 band
`Unlicensed 900 band (U.S.)
`Unlicensed 900 band
`MMDS2100 band
`MMDS 2500 band
`Unlicensed 2400 band
`Unlicensed 5.1 UNII band
`Unlicensed 5.8 UNII band
`
`Page 15 of 20
`
`Page 15 of 20
`
`

`

`US 7,133,697 B2
`
`7
`
`-continued
`
`band A
`
`band B
`
`8
`filed Oct. 21, 1999. The antenna 146 may include separate
`transmit and receive radiating elements, or a single set of
`radiating element with a diplexer. Respective power ampli-
`fiers and low noise amplifiers for the transmit and receive
`PCS-1900 band (use the existing U.S. 3G
`UMTSband 1900/2100
`functions are incorporated with the antenna and are located
`infrastructure to translate Euro/Asia frequencies
`closely adjacent
`the radiating elements. Uplink signals
`UMTSband 1900/2100=Cell-800 band
`received at the antenna 14d are RI’ filtered by filter 92 and
`UMTS 1900/2100
`3.5 GHz band (this is a license hand; the
`are fed through an RF-to-microwave upconverter 202 which
`European MMDSband)
`DCS-1800
`3.5 GHz
`converts directly from RF to microwave. The signal is then
`3.5 GHz
`DCS-900
`amplified by a power amplifier 100 which feeds the signal to
`DCS-1800
`2400 Unlicensed (this band is unlicensed
`the microwave backhaul antenna 16a by wayof a frequency
`throughout the world: 83 MHz wide)
`DCS-900
`2400 Unlicensed
`diplexer 102, as described above with reference to FIG. 5.
`5.1 GHz UNII
`DCS-1800
`Downlink signals received at the backhaul link antenna 16a
`DCS-900
`5.1 Gllz UNII
`are directed through an LNA 104 to a microwave-to-RF
`DCS-1800
`5.8 UNII
`downconverter 204 which downconverts from the micro-
`DCS-900
`5.8 UNII
`wave backhaul spectrum directly to RF. The signals are
`filtered by RF filter 112 and forwardedto the active antenna
`146.
`In yet another embodiment, shownin FIG.7, a distributed
`active antenna 146 (DAA)is also utilized in much the same
`fashion as described above with reference to FIG. 6, but the
`hardwareutilizes a conversion step to IF before converting
`to the RF or microwave spectrum, somewhatsimilar to FIG.
`5. Signals from RF antenna 144 are RFfiltered through filter
`92 and are delivered to an RF-to-IF downconverter 94 which
`feeds the resultant IF signal to an IF filter 96 and thento an
`IF-to-microwave converter 98. The signal from the con-
`verter 98 is routed to the diplexer 102 through a power
`amplifier 100 to be transmitted by the microwave backhaul
`antenna 16a. Working, in the downlink direction, the signals
`received by the backhaullike antenna 16a are directed by the
`frequency diplexer 102 to a low noise amplifier 104 which
`amplifies the signal and feeds it
`to a microwave-to-II'
`downconverter 106. The down-converted IF signalisfiltered
`through an IF filter 107, and is directed to the IF-to-RF
`upconverter 108. The signals are filtered through RFfilter
`112 and forwarded to the active antenna 148.
`Referring to FIG. 8, a modular electronics package
`including the basic elements of any of the embodiments of
`FIGS. 5—7 is shown. In the embodiment of FIG. 8, use of a
`single passive antenna element 14a is contemplated,
`wherebya diplexer 90 is provided. As explained above with
`reference to FIGS. 5-7, when separate transmit and receive
`antenna elementsare utilized, a diplexer 90 may be omitted.
`The remaining components include a frequency diplexer 102
`for the microwave backhaul link antenna 16a, power ampli-
`fiers 110 and 100, low noise amplifiers 93 and 104. Respec-
`tive upconverter and downconvertercircuitry 302, 304 may
`take the form ofthe up/down convertercircuits shown in any
`of FIGS. 5, 6 and 7. That is, conversion may be achieved
`through an IF stage, or directly between RF and microwave.
`Advantageously, this modular electronics package may be
`conveniently mounted on the tower, eliminating a need for
`expensive DSP and modulator/demodulator electronics in a
`ground unit and associated coaxial cable running up and
`downthe tower both for the RF side and the backhaul side.
`Only a relatively simple DC power cable for DC power to
`the electronics package need be provided, and this in turn
`may be eliminated if onboard power in the form ofbatteries,
`rechargeable batteries, solar power, or the like is provided.
`Referring to FIG. 9, a multiple sector system for the
`receive or uplink path is shown. Respective sector antennas
`314, 316, etc. are provided (one for each of the three or more
`sectors). Each antenna is provided with a low noise amplifier
`318, 320. This system supports a total of M code division
`multiple access (CDMA)carriers per sector, with N chan-
`nels per carrier. Accordingly, multiple downconverter blocks
`
`Band A frequencies are embeddedin the current/original
`base station modulation and transceiver hardware, as well as
`the terminal equipment.
`DCS-1800 is currently the world GSM standard, migrat-
`
`ing to GPRS, then EDGE, then W-CDMA.
`Returning to FIG. 3, the electronics module 80, located at
`the tower top, mayalso include amplifiers for amplifying the
`signals to be respectively transmitted by the RF antenna 14a
`and the microwave backhaul antenna 16a, respectively, in
`addition to hardware for RF-to-LMDS and LMDS-to-RF
`frequency conversion. Module 80 is also shownin FIG.4,
`wherein the RF-to-LMDSconverter, the LMDS-to-RF con-
`verter and the amplifiers are indicated as a part of the
`electronics module 80.
`FIGS. 5-7 show various embodiments of the electronics
`module 80 which may be used betweenthe RF link antennas
`14a and a microwave backhaul antenna 16a.
`In FIG. 5, a single RF antenna 14a is used for both
`transmit and receive functions, and is a passive antenna.
`Antenna 14a is coupled with a frequency diplexer 90 for
`separating the transmit and receive signals. The receive or
`uplink signals from the antenna 14a are fed through diplexer
`90 to RF-to-microwave converter circuitry which includes
`an RF filter 92, an amplifier, such as an LNA 93, RF-to-IF
`downconverter or downconversion circuitry 94, an IF filter
`96, an IF-to-microwave upconverter or upconversion cir-
`cuitry 98, and a power amplifier 100. The signal is routed
`through diplexer 102 which serves to separate receive and
`transmit signals at the microwave backhaul antenna 16a.
`The signal is then backhauled to an appropriate switching
`center directly to be processed and demodulated at the
`switching center, rather than at the base station. In that way,
`modulation and demodulation circuitry and other DSP func-
`tions may be centralized at a switching center or office,
`rather than at eachbasestation. This results in a significant
`cost savings per base station and overall.
`The reverse, or downlink, path from the diplexer 102
`directs signals received by the backhaul antenna 16a from
`the switching center through a low noise amplifier 104, to
`microwave-to-IF downconverter circuitry 106, which places
`the signal in a form to be converted to RF and transmitted
`from the tower. An IFfilter 107 filters the signal before it is
`routed to an IF-to-RF upconverter, or upconversion circuitry
`108. The RF signal is amplified by a power amplifier 110 and
`filtered by an RF filter 112 before passing through the
`frequency diplexer 90 to the RI’ antenna 14a.
`Another version of the electronics package 80a is illus-
`trated in FIG. 6 for use with antenna 144, which is a
`distributed active antenna DAA, for example, of the type
`described in the co-pending application Ser. No. 09/422,418,
`
`10
`
`15
`
`20
`
`30
`
`35
`
`40
`
`45
`
`5
`
`60
`
`65
`
`Page 16 of 20
`
`Page 16 of 20
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`

`

`US 7,133,697 B2
`
`9
`330 are provided with down converter subcircuits 332 for
`each of the Mcarriers in the sector. ‘That is, M downcon-
`verter circuits 332 are associated with each sector antenna
`314, 316, etc. Splitter circuits 321 route the carriers to their
`respective down converter circuits 332. The downconverter
`circuits 332 may also be provided with analog-to-digital
`conversion or converters 333. Thus, a digital signal is fed to
`a digital signal processor (DSP)/demodulator block 340. In
`the system of FIG. 9, a total of MxN of the DSP/demodu-
`lator blocks 340 will be provided for each sector for han-
`dling the N channels per M carriers. All of the demodulator
`outputs are fed to a high speed digital multiplexer 350