MA TAN
`THE MAIN TEA ETA ARTE MAI UTAMA MA MA MA
`US 20180287833A1
`( 19 ) United States
`( 12 ) Patent Application Publication ( 10 ) Pub . No . : US 2018 / 0287833 A1
`Kennedy
`Oct . 4 , 2018
`( 43 ) Pub . Date :
`
`( 54 ) SMALL CELL BASE STATIONS HAVING
`DRONE - MOUNTED RADIO UNITS AND
`RELATED SYSTEMS AND METHODS
`( 71 ) Applicant : CommScope Technologies LLC ,
`Hickory , NC ( US )
`( 72 ) Inventor : Bryan K . Kennedy , Norcross , GA ( US )
`
`( 21 ) Appl . No . : 15 / 936 , 539
`
`Mar . 27 , 2018
`( 22 ) Filed :
`Related U . S . Application Data
`( 60 ) Provisional application No . 62 / 478 , 064 , filed on Mar .
`29 , 2017 .
`
`, 60
`
`62
`
`534 /
`
`LIL
`
`02
`537
`so
`
`Publication Classification
`
`( 2006 . 01 )
`( 2006 . 01 )
`
`( 51 )
`
`2 )
`
`Int . Ci .
`H04L 25 / 26
`H04B 10 / 2575
`U . S . CI .
`CPC . . . . . . . . . . . . . . H04L 25 / 26 ( 2013 . 01 ) ; H04L 45 / 28
`( 2013 . 01 ) ; H04B 10 / 25754 ( 2013 . 01 )
`( 57 )
`ABSTRACT
`A base station system includes a central hub having a
`baseband controller and a backhaul connection to an exter
`nal network and a plurality of remote units that are con
`nected to the central hub by respective wired power and
`cabling connections , each remote unit including an associ
`ated drone unit that has an aerial drone and a radio unit
`mounted thereon . The radio units are operated under control
`of the baseband controller to form a super cell that appears
`as a single base station to the external network
`
`62
`
`53 - 1
`
`162
`
`LUS
`
`NETWORK
`GATEWAY
`16
`
`CORE
`NETWORK
`
`

`

`Patent Application Publication
`
`Oct . 4 , 2018 Sheet 1 of 10
`
`US 2018 / 0287833 A1
`
`70 |
`
`SS - ?
`
`? ?
`
`OL
`
`? 0?
`
`20
`
`70 | 53
`
`302
`
`CORE NETWORK 81 .
`
`(
`
`8
`
`FIG . IA ?
`
`NETWORK GATEWAY
`
`30
`
`

`

`Patent Application Publication
`
`Oct . 4 , 2018 Sheet 2 of 10
`
`US 2018 / 0287833 A1
`
`?
`CORE NETWORK
`
`NETWORK GATEWAY 16
`
`FIG . 1B
`
`ro
`
`09 _ n
`
`70
`
`to
`
`30
`
`14
`
`1
`
`.
`
`70
`
`70 53
`
`3
`
`

`

`Patent Application Publication
`
`Oct . 4 , 2018 Sheet 3 of 10
`
`US 2018 / 0287833 A1
`
`21 - curent
`
`BOOST
`CONVERTER
`54
`
`DRONE
`COMPARTMENT
`
`BACKHAUL
`EQUIPMENT
`
`BASEBAND
`CONTROLLER
`22 :
`
`ETHERNET
`SWITCH
`23
`
`POWER - OVER
`FIBER SYSTEM
`24
`
`POWER
`SUPPLY
`25
`
`266 TO NETWORK
`GATEWAY
`
`"
`
`TO TETHER
`?
`BOXES OR
`DRONE UNITS
`
`K
`
`K
`
`POWERSHIFT
`POWER SUPPLY
`
`25 - 1 BIET ?
`
`KA
`
`29
`427
`
`-
`
`?
`
`TO TETHER
`Dovr
`BOXES
`50
`GENERATOR
`
`FIG . 2
`
`

`

`Patent Application Publication
`
`Oct . 4 , 2018 Sheet 4 of 10
`
`US 2018 / 0287833 A1
`
`60
`
`TETHER
`RAPID
`SPOOL | SPOOL
`53A
`59
`
`-
`
`I
`
`.
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`TO CENTRAL
`HUB +
`20
`
`57 A
`
`ETHERNET
`SWITCH
`
`BOOST
`CONVERTER
`54
`
`LOCAL POWER
`SOURCE OR
`CENTRAL HUB
`
`?
`
`POWER SUPPLY
`35
`
`DRONE COMPARTMENT
`58
`
`FIG . 3A
`
`POWER
`SUPPLY
`55
`
`2260
`
`53 - 1
`RAPID | TETHER
`SPOOL
`SPOOL
`53A
`
`ETHERNET SWITCH
`
`MEDIA CONVERTER
`
`DRONE COMPARTMENT
`58
`
`FIG . 3B
`
`LOCAL POWER
`SOURCE OR
`CENTRAL HUB
`TO CENTRALA
`HUB 20
`??
`TEHTHER
`BOXES
`
`56
`
`| 5
`
`

`

`Patent Application Publication
`
`Oct . 4 , 2018 Sheet 5 of 10
`
`US 2018 / 0287833 A1
`
`100
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`ers
`
`-
`
`- -
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`80€
`io
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`- -
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`- ,
`
`-
`
`RADIO POINTS
`
`Il
`
`-
`
`-
`
`-
`
`-
`
`-
`
`Tha -
`
`-
`
`-
`
`-
`
`-
`
`-
`
`POE +
`
`-
`
`-
`
`-
`
`-
`
`-
`
`GIGE / CAT5
`ETHERNET
`ETHERNET
`SWITCH
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`d :
`
`3 : 38 lilild
`
`TOER SE HIT
`123
`
`123
`
`38 :
`
`: : : d : 1 : 8
`
`88 : : : : 88 : : 88
`
`123
`BASE
`BASEBAND CONTROLLER
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`- -
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`- -
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`118
`
`OPERATOR
`NETWORK
`
`FIG . 4
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`L
`
`

`

`Patent Application Publication
`
`Oct . 4 , 2018 Sheet 6 of 10
`
`US 2018 / 0287833 A1
`
`. l Terra
`m @
`2061
`
`( so
`+
`@
`
`FIG . 5
`
`( co
`
`(
`
`190
`
`(
`
`Elcio
`- fco
`
`er 001
`
`
`
`BASEBAND CONTROLLER
`
`
`
`RADIO POINTS
`
`

`

`Patent Application Publication
`
`Oct . 4 , 2018 Sheet 7 of 10
`10
`
`US 2018 / 0287833 A1
`
`??
`TETHER BOX
`150
`
`BUCK
`CONVERTER
`165
`
`ANTENNA I
`174 - 1
`
`ANTENNA 2
`174 - 2
`
`PCB
`176
`
`AERIAL DRONE
`162
`
`MEDIA
`CONVERTER
`166
`
`168
`
`RADIO
`172
`
`-
`
`-
`
`-
`
`-
`
`-
`
`EXTERNAL
`ANTENNAS
`178
`
`-
`
`-
`
`-
`
`- -
`
`-
`
`-
`
`-
`
`-
`
`1 . -
`
`-
`
`-
`
`RADIO POINT 170
`FIG . 6A
`
`AERIAL DRONE
`162
`
`RADIO
`172
`
`-
`
`- - - - - - I
`- - - -
`.
`EXTERNAL
`ANTENNAS
`178
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`RADIO POINT 170
`FIG . 6B
`
`ANTENNA 1
`174 - 1
`
`ANTENNA 2
`174 - 2
`
`PCB 176
`
`153
`
`TO TETHER BOX
`150
`
`

`

`Patent Application Publication
`
`Oct . 4 , 2018 Sheet 8 of 10
`
`US 2018 / 0287833 A1
`
`190
`
`? ? ? USER
`? ? ? , ??? 170
`? ? ?
`
`BUCK
`15
`160
`
`BUCK
`111111111
`15
`
`10
`
`BST
`154
`
`155
`150
`
`| 12
`
`140
`
`17 . 1
`
`POF
`124
`
`/ /
`150
`?130
`
`??? BBC
`
`122
`
`120
`
`FIG . 7
`
`

`

`Patent Application Publication
`
`Oct . 4 , 2018 Sheet 9 of 10
`
`US 2018 / 0287833 A1
`
`1604
`
`162 NA
`
`FIG . 8
`
`200
`
`START
`
`RECEIVE RF SIGNAL
`AT DRONE RADIO
`
`TRANSMIT DATA TO
`REMOTE UNIT OVER
`
`TETHER CORD . .
`
`cute
`3
`.
`
`TRANSMIT DATA TO
`CENTRAL HUB OVER
`POWER - OVER - FIBER
`CABLE
`
`END
`
`FIG . 9
`
`

`

`Patent Application Publication
`
`Oct . 4 , 2018 Sheet 10 of 10 US 2018 / 0287833 A1
`
`320
`
`r 300
`
`320
`
`FIG . 10A
`
`r 300
`
`- 320
`
`FIG . 10B
`
`

`

`US 2018 / 0287833 A1
`
`Oct . 4 , 2018
`
`SMALL CELL BASE STATIONS HAVING
`DRONE - MOUNTED RADIO UNITS AND
`RELATED SYSTEMS AND METHODS
`CROSS - REFERENCE TO RELATED
`APPLICATION
`[ 0001 ] The present application claims priority under 35
`U . S . C . § 119 to U . S . Provisional Patent Application Ser . No .
`62 / 478 , 064 , filed Mar . 29 , 2017 , the entire content of which
`is incorporated herein by reference .
`FIELD
`[ 0002 ] The present invention relates to cellular commu
`nications systems and , more particularly , to small cell cel
`lular base stations .
`
`BACKGROUND
`0003 ] Cellular communications systems are well known
`in the art . In a typical cellular communications system , a
`geographic area is divided into a series of regions that are
`referred to as " cells , ” and each cell is served by a so - called
`“ macrocell ” base station . The base station may include
`baseband equipment , radios and antennas that are configured
`to provide two - way radio frequency ( “ RF ” ) communications
`with mobile and fixed subscribers ( " users ” ) that are located
`throughout the cell . The base station may also have backhaul
`equipment that enables communications between the base
`station and the core network of the wireless operator . The
`antennas are often mounted on a tower or other raised
`structure , with the radiation beam ( " antenna beam ” ) that is
`generated by each antenna directed outwardly to serve the
`entire cell or a portion of " sector ” of the cell such as a wedge
`shaped section of the cell in the azimuth plane .
`[ 0004 ]
`In order to increase capacity , so - called " small cell ”
`cellular base stations have been deployed in recent years . A
`small cell base station refers to a base station that typically
`operates at lower power levels and hence has a much smaller
`coverage area than a typical macrocell base station . Typi
`cally , a small cell base station is designed to serve users
`within a small area , such as , for example , within tens or
`hundreds of meters of the small cell base station .
`[ 0005 ] Small cell base stations typically employ an
`antenna that provides full 360 degree coverage ( omnidirec
`tional coverage ) in the azimuth plane and a suitable beam
`width in the elevation plane to cover the designed area of the
`small cell . The small cell antenna may be designed to have
`a small downtilt in the elevation plane to reduce spill - over
`of the antenna beam of the small cell antenna ( s ) into regions
`that are outside the small cell and also for reducing inter
`ference between the small cell and the overlaid macrocell .
`[ 0006 ] Small cell base stations may be deployed in a
`number of different environments . In some cases , small cell
`base stations are used to provide cellular coverage to high
`traffic areas within a macrocell , which allows the macrocell
`base station to offload much or all of the traffic in the vicinity
`of the small cell to the small cell base station . In other cases ,
`small cell base stations may be deployed within structures
`such as office buildings , shopping smalls , stadiums and the
`like to provide coverage within such buildings . Small cell
`base stations may be particularly effective in this environ
`ment as concrete and steel structures may degrade the
`quality of service within the interior of such buildings when
`served by a macrocell base station .
`
`Traditional small cell base stations operate in much
`[ 0007 ]
`the same way as a macrocell base station , with each small
`cell base station including its own baseband equipment , one
`or more antennas connected thereto ( depending upon
`whether sectorization is used ) , and its own physical cell
`identifier and backhaul connection to the core network . This
`may create difficulties when dense deployment of small cells
`is required , as might be the case in a downtown urban area .
`For example , borders between adjacent small cells may
`experience interference and reduced performance . Hand - offs
`between small cells can become common , which complicate
`network control and may negatively impact the user expe
`rience . Complex radio planning may also be required to
`reduce interference between adjacent small cells and
`between the small cells and nearby or overlaid macrocell
`base stations .
`[ 0008 ] Enhanced small cell base stations have recently
`been introduced that can provide improved performance ,
`particularly when dense deployment is required . An example
`of such an enhanced small cell is the OneCell C - RAN
`Enterprise Small Cell system sold by CommScope , Inc . of
`Hickory , N . C . , which is referred to herein as the “ OneCell
`system . ” The OneCell system deploys a plurality of radio
`units in the area to be served by the small cell , and
`configures these radio units to operate as a so - called “ super
`cell ” so that to the core network the super cell appears like
`a traditional small cell that has a single physical identifier
`and a single connection to the core network despite deploy
`ing as many as 64 radio units . The OneCell system also uses
`virtual sectorization within the cell to provide capacity and
`coverage where it is needed and when it is needed . This
`approach can provide significantly enhanced data through
`puts while simplifying network planning and operation .
`SUMMARY
`0009 ] Pursuant to embodiments of the present invention ,
`base station systems are provided that include a central hub
`having a baseband controller and a backhaul connection to
`an external network and a plurality of remote units that are
`connected to the central hub by respective wired power and
`cabling connections . Each remote unit includes an associ
`ated drone unit that has an aerial drone and a radio unit
`mounted thereon . The radio units are operated under control
`of the baseband controller to form a super cell that appears
`as a single base station to the external network .
`[ 0010 ] .
`In some embodiments , the wired power and
`cabling connections may comprise power - over - fiber cabling
`connections .
`[ 0011 ]
`In some embodiments , at least some of the drone
`units may be connected to their associated remote units by
`tether cables . In such embodiments , each tether cable may
`comprise a power - over - fiber tether cable . At least some of
`the drone units may include a respective media converter
`that is configured to convert fiber optic data received over
`the respective power - over - fiber tethers cable into respective
`Ethernet data that is communicated to the respective radio
`units via respective Ethernet cables and to convert power
`signals received over the respective power - over - fiber tether
`cables into respective Power - over - Ethernet power signals
`that are supplied to the respective radio units over the
`respective Ethernet cables .
`[ 0012 ]
`In some embodiments , at least some of the remote
`units are powered by respective power cabling connections
`that extend between the central hub and the respective
`
`

`

`US 2018 / 0287833 A1
`
`Oct . 4 , 2018
`
`remote units . In such embodiments , the central hub may
`include a power supply that adjusts a voltage of a power
`signal that is provided over a first of the power cabling
`connections to a first of the remote units in response to
`variations in the current drawn by the load at the first of the
`remote units . The voltage of the power signal that is pro
`vided over the first of the power cabling connections to the
`first of the remote units may be adjusted , for example , so that
`a voltage of the power signal as measured at the first of the
`remote units remains substantially constant .
`[ 0013 ]
`In some embodiments , at least some of the remote
`units may include boost converters and at least some of the
`drone units may include buck converters .
`[ 00141 In some embodiments , a first of the remote units
`may include an Ethernet switch , and a power - over - fiber
`cabling connection may extend from the first of the remote
`units to a second of the remote units .
`[ 0015 ]
`In some embodiments , at least some of the remote
`units may include a respective motorized rapid spool sys
`tem .
`In some embodiments , at least some of the remote
`[ 0016 ]
`units may include a respective media converter that is
`configured to convert fiber optic data received over the
`respective power - over - fiber cabling connections into Ether
`net data that is communicated to the respective radio unit via
`respective Ethernet cables , where the Ethernet cables are
`also configured to function as tether cables for the respective
`drone units .
`[ 0017 ]
`In some embodiments , the radio units may be
`mounted on respective aerial drones of the drone units via
`motorized mounting structures that are configured to change
`a physical orientation of the radio units .
`[ 0018 ] Pursuant to further embodiments of the present
`invention , methods of operating a small cell base station are
`provided in which an RF communication is received from a
`user at a radio unit that is part of a drone unit that includes
`an aerial drone having the radio unit mounted thereon . Data
`contained in the received RF communication is transmitted
`from the radio unit to a remote unit over a tether cord . The
`data contained in the received RF communication is then
`transmitted from the remote unit to a central hub over a
`power - over - fiber system .
`[ 0019 ]
`In some embodiments , the electronic equipment in
`the remote unit may be powered by supplying a power signal
`to the remote unit over a power cabling connection that
`extends between the central hub and the remote unit . In such
`embodiments , the central hub may include a power supply
`that adjusts a voltage of the power signal in response to
`variations in the current drawn by the load at the remote unit .
`The voltage of the power signal that is provided over the
`power cabling connection to the remote unit may be adjusted
`so that a voltage of the power signal as measured at the
`remote unit remains substantially constant .
`10020 ]
`In some embodiments , the data contained in the
`received RF communication may be transmitted from the
`radio unit to the remote unit as a fiber optic signal .
`[ 0021 ]
`In some embodiments , the drone unit may be
`powered via a power signal that is supplied to the drone unit
`from the remote unit over the tether cord , where the remote
`unit includes a boost converter that steps up the voltage of
`the power signal to a voltage exceeding 300 volts . In such
`embodiments , the drone unit may include a buck converter
`that steps down a voltage of the power signal supplied to the
`drone unit over the tether cord .
`
`In some embodiments , electronic equipment
`[ 0022 ]
`included in the remote unit may be powered via a power
`cabling connection that extends between the central hub and
`the remote unit .
`[ 0023 ]
`In some embodiments , a plurality of remote units
`may be connected to the central hub , each remote unit
`having an associated drone unit with a radio unit mounted
`thereon , where the radio units all communicate through one
`or more baseband controllers at the central hub to form
`a
`super cell small cell base station .
`( 0024
`In some embodiments , the tether cord may include
`at least two power conductors and at least one fiber optic
`cable bound in a fiber web . In such embodiments , the tether
`cord may also include a protective coating that covers the
`fiber web , and / or where the fiber web may be a Kevlar web .
`BRIEF DESCRIPTION OF THE DRAWINGS
`10025 ] . FIG . 1A is a schematic diagram illustrating a
`drone - enabled small cell base station according to embodi
`ments of the present invention .
`[ 0026 ] FIG . 1B is a schematic diagram illustrating a
`drone - enabled small cell base station according to further
`embodiments of the present invention .
`[ 0027 ] FIG . 2 is a schematic block diagram illustrating a
`central hub of a drone - enabled small cell base station
`according to embodiments of the present invention .
`[ 0028 ] . FIG . 3A is a schematic block diagram illustrating a
`remote unit in the form of a tether box of a drone - enabled
`small cell base station according to embodiments of the
`present invention .
`[ 0029 ] FIG . 3B is a schematic block diagram illustrating a
`tether box of a drone - enabled small cell base station accord
`ing to further embodiments of the present invention .
`[ 0030 ] FIG . 4 is a schematic block diagram illustrating a
`super cell architecture that can be employed in the drone
`enabled small cell base stations according to certain embodi
`ments of the present invention .
`[ 0031 ]
`FIG . 5 is a schematic diagram that illustrates opera
`tion of the super cell of FIG . 4 .
`10032 ]
`FIG . 6A is a schematic block diagram illustrating a
`drone unit according to certain embodiments of the present
`invention .
`[ 0033 ]
`FIG . 6B is a schematic block diagram illustrating a
`drone unit according to further embodiments of the present
`invention .
`[ 0034 ]
`FIG . 7 is a schematic block diagram illustrating a
`OneCell system based drone - enhanced small cell base sta
`tion according to embodiments of the present invention .
`[ 0035 ] FIG . 8 is a schematic diagram illustrating how
`drone - mounted radio units may be mounted on mechanically
`tiltable mounting structures that can be used to adjust the
`pointing directions of the radio unit antennas .
`[ 0036 ] FIG . 9 is a flow chart illustrating a method of
`operating a small cell base station according to embodiments
`of the present invention .
`[ 0037 ] FIGS . 10A and 10B are schematic diagrams that
`illustrate how tether cables used in embodiments of the
`present invention may be formed using speed wrap tech
`niques .
`
`DETAILED DESCRIPTION
`[ 0038 ] Pursuant to embodiments of the present invention ,
`small cell base stations having radio units mounted on
`
`

`

`US 2018 / 0287833 A1
`
`Oct . 4 , 2018
`
`unmanned aerial vehicles are provided that may be quickly
`deployed to provide cellular coverage in a defined area . The
`unmanned aerial vehicle may comprise any appropriate
`unmanned flying object onto which a radio unit of a small
`cell base station may be mounted . Such unmanned aerial
`vehicles are referred to herein as “ aerial drones ” or “ drones . ”
`Small cell base stations that include at least one unmanned
`aerial vehicle with a radio unit mounted thereon are referred
`to herein as " drone - enabled small cell base stations . ” The
`drone - enabled small cell base stations according to embodi
`ments of the present invention may be ideal for use in
`emergency situations and / or for special events and various
`other applications in which it may be necessary or desirable
`to quickly provide increased cellular coverage and / or to
`provide cellular coverage for a limited amount of time . The
`drone - enabled small cell base stations according to embodi
`ments of the present invention deploy one or more aerial
`drones that each have a radio unit mounted thereon . The
`combination of an aerial drone and a radio unit is referred to
`herein as a " drone unit . ” The radio unit may comprise , for
`example , a OneCell radio point , a WiFi access point or any
`other radio unit including a radio and one or more associated
`antennas that can transmit and receive RF signals . Each
`drone unit may be flown to a desired height above the
`ground at a pre - selected position within the coverage area of
`the small cell . In many cases , the maximum height at which
`the drone unit may be flown may be limited by regulation .
`For example , in the United States , Federal Aviation Admin
`istration regulations may place a 400 foot maximum flying
`height on the drone units . Typically , the drone units are
`spread throughout the geographic region covered by the
`drone - enabled small cell base station . By mounting the radio
`units on drones that may be , for example , flown to a height
`of 100 meters above the ground , the coverage area and / or
`capacity of the drone - enabled small cell base station may be
`significantly increased .
`10039 ]
`The drone - enabled small cell base station may
`include a central hub . In some embodiments , the drone
`enabled small cell base station may further include one or
`more remote units in the form of ground - based tether boxes .
`A tether box may be provided for each drone unit and each
`drone unit may be connected to its respective tether box by
`a tether cable . The tether cable may carry power , data and / or
`control signals to the drone unit . One or more data cables
`and power cables may be connected between the central unit
`and the ground - based tether boxes to provide power to the
`drone units and / or to the tether boxes and to carry data
`between the central hub and the tether boxes / drone units .
`0040 ]
`In some embodiments , the central hub of the drone
`enabled small cell base station may comprise a rugged ,
`hardened case that houses baseband and backhaul equip
`ment , a power supply system , a power - over - fiber system and
`switching equipment . The central hub may also include one
`or more external hardened power connectors for power
`inputs from an external generator or other external power
`source . The central hub may also include external hardened
`connectors for connection to a backhaul network and for the
`cabling connections to the tether boxes . Each tether box may
`comprises a smaller rugged , hardened case which may
`include power and data transmission equipment for support
`ing power and data connectivity with the drone unit .
`[ 0041 ]
`In some embodiments , each tether box may be
`powered locally by a generator or an available connection to
`the power grid . Local powering of the tether boxes may be
`
`particularly advantageous when the tether boxes are located
`at relatively large distances from the central hub , as it may
`help reduce power losses that occurs in the cabling and avoid
`the need to run power cables over long distances . In other
`embodiments , each tether box may be powered via a power
`cable that extends between the tether box and the central hub
`( or a power source that is co - located with the central hub ) .
`In such embodiments , so - called “ PowerShift ” techniques for
`delivering power to the tether boxes may be used which may
`reduce power losses along the cabling connections . These
`PowerShift techniques , which will be described in greater
`detail herein , increase the voltages of the power signals
`output from the power supply to maintain the voltages of the
`power signals received at each tether box at , for example , a
`substantially constant voltage that is near a maximum power
`supply voltage that the tether box can receive without
`potentially damaging the electronics included in the tether
`box .
`[ 0042 ] The OneCell radio points that are mounted on the
`drone units may be powered from their respective tether
`boxes by , for example , power - over - fiber cables or Ethernet
`cables . These cables may also be used to power the aerial
`drones , at least in some embodiments . The power - over - fiber
`cable or Ethernet cable may also serve as a tether cable for
`the drone unit . In embodiments where the OneCell radio
`points on the drone units are powered by respective power
`over - fiber cables , a media converter may be provided in each
`drone unit . The media converter may convert the power
`signal that is received over the power - over - fiber cable into a
`Power - over - Ethernet ( “ PoE ” ) power signal for powering the
`radio unit . The media converter also converts the fiber optic
`data signal that is output from the power - over - fiber cable
`into an Ethernet data signal that may be transmitted over a
`copper Ethernet cable . Thus , the media converter may
`provide the power and data conversions necessary to supply
`the radio unit with power and data in the correct formats .
`The aerial drone may also be powered via the power signal
`output by the media converter or via a separate power signal .
`100431 In embodiments where the drones are powered
`using power - over - fiber cables , each tether box may option
`ally include a boost converter for increasing the voltage of
`a power signal delivered from the tether box to the drone
`unit over the power - over - fiber cable , and each drone unit
`may include a buck converter for decreasing the voltage of
`the power signal received at the drone unit . The boost
`converter may increase the voltage of the power signal to ,
`for example between 300 - 600 volts AC and the buck con
`verter may reduce the voltage to , for example , about 48 volts
`DC . By increasing the voltage of the power signal , smaller
`diameter power conductors may be included in the tether
`cable in order to decrease the weight of the tether cable .
`10044 ] .
`In an example embodiment , the drone unit may
`climb to an elevation of about 100 meters and provide
`coverage for a circular coverage area having a radius of
`about 300 meters . By deploying multiple drone units with
`slightly overlapping coverage areas , a " super cell ” can be
`created so that the drone - enabled small cell base station may
`provide coverage over a significant area . This super cell
`includes a plurality of distributed radio units that act in a
`coordinated fashion as a single cell in the cellular network .
`This approach may , for example , leverage off of the virtual
`sectorization provided by OneCell radio points to provide a
`single small cell with improved coverage and capacity that
`could be quickly deployed and / or deployed on a temporary
`
`

`

`US 2018 / 0287833 A1
`
`Oct . 4 , 2018
`
`basis . In other embodiments , traditional small cell base
`stations , WiFi access points or other technologies may be
`used to implement a drone - enabled small cell base station .
`[ 0045 ]
`In other embodiments , media converters may be
`included in each tether box , and the radio units may be
`powered over PoE connections carried over respective cop
`per Ethernet tether cables . Such embodiments may be par
`ticularly useful in deployments where the drone units are
`flown at lower heights above the ground , as the increased
`weight associated with using an Ethernet tether cable may be
`offset by the decrease in weight resulting from the reduced
`length of the tether cable required to support drone units
`flown at lower heights above the ground .
`[ 0046 ] Example embodiments of the invention will now
`be discussed in more detail with reference to the attached
`drawings .
`[ 0047 ] FIG . 1A is a schematic diagram of a drone - enabled
`small cell base station 10 according to certain embodiments
`of the present invention . As shown in FIG . 1A , the drone
`enabled small cell base station 10 includes a central hub 20
`and a plurality of tether boxes 50 . Each tether box 50 may
`have an associated drone unit 60 . Each drone unit 60 may
`include an aerial drone 62 that has a radio unit 70 mounted
`thereon , and may be tethered to a respective one of the tether
`boxes 50 by a tether cable 53 . The tether cables 53 may serve
`as a transmission path for power and data signals between
`the tether boxes 50 and their associated drone units 60 .
`Power - over - fiber cables 30 extend between the central hub
`20 and each tether box 50 . Power cables 40 also extend
`between the central hub 20 and each tether box 50 . A
`generator 12 may be connected to the central hub 20 and
`may provide power to the central hub 20 . A backhaul
`connection 14 may connect the central hub 20 to a network
`gateway 16 of a core network 18 run by a mobile operator .
`[ 0048 ] As the central hub 20 may provide the only con
`nection to the network gateway 16 of the core network 18 ,
`data may be transmitted between the radio units 70 and the
`central hub 20 . It is also necessary to power the tether boxes
`50 and the drone units 60 . As shown in FIG . 1A , in some
`embodiments , the tether boxes 50 may be powered via the
`power cables 40 that extend from the central hub 20 to each
`respective tether box 50 . A power supply 25 ( see FIG . 2 ) in
`the central hub 20 may receive , for example , alternating
`current ( " AC " ) power from the generator 12 and convert the
`AC power into DC power signals . These DC power signals
`may be used to power electronic components in the central
`hub 20 and to supply power to the respective tether boxes 50
`over the power cables 40 . AC ( as opposed to DC ) power
`signals may be transmitted between the central hub 20 and
`the tether boxes 50 in other embodiments .
`[ 0049 ] FIG . 1B is a schematic diagram of a drone - enabled
`small cell base station 10 ' according to certain embodiments
`of the present invention . As is readily apparent , the drone
`enabled small cell base station 10 ' of FIG . 1B is similar to
`the drone - enabled small cell base station 10 of FIG . 1A ,
`except that the power cables 40 are omitted in the drone
`enabled small cell base station 10 ' of FIG . 1B and are
`replaced with local power sources 42 that are provided at
`each tether box 50 . As the drone - enabled small cell base
`station 10 ' of FIG . 1B is otherwise identical to the drone
`enabled small cell base station 10 of FIG . 1A , further
`description thereof will be omitted here .
`10050 ]
`FIG . 2 is a schematic diagram illustrating a central
`hub 20 according to certain embodiments of the present
`
`invention . As shown in FIG . 2 , the central hub 20 includes
`backhaul equipment 21 , one or more baseband controllers
`22 , an Ethernet switch 23 , a power over - fiber system 24 and
`a power supply 25 that are mounted within a rugged ,
`hardened case . The hardened case includes a plurality of
`external hardened connectors including a backhaul connec
`tor 26 for connection to the network gateway 16 , a power
`connector 27 that is configured to receive a power cable
`from the external generator 12 or other external power
`source , a plurality of power - over - fiber connectors 28 for
`power - over - fiber cabling connections 30 that extend
`between the central hub 20 and the tether boxes 50 , and a
`plurality of power connectors 29 that may be used to supply
`power to the tether boxes 50 in some embodiments over the
`power cables 40 .
`[ 0051 ] The backhaul equipment 21 may be coupled to the
`baseband controller 22 . The backhaul equipment 21 may
`receive data that is to be transmitted over the drone - enabled
`small cell base station 10 from the core network 18 via the
`network gateway 16 and provide this data to the baseband
`controller 22 , and may receive via the baseband controller
`22 data that is received by the drone units 60 and transmit
`this data to the core network 18 via the network gateway 16 .
`[ 0052 ] The baseband controller 22 may perform various
`operations including formatting data for transmission and
`controlling operation of the radio units 70 , as will be
`described in greater detail below . The baseband unit 22 may
`be coupled to the power - over - fiber system 24 through an
`Ethernet switch 23 that performs routing of data packets .
`[ 0053 ] The power - over - fiber system 24 may be used to
`transmit power signals and data signals from the central hub
`20 to the drone units 60 via the tether boxes 50 . A respective
`fiber optic ca