US007286507B1
`
`(12) United States Patent
`Oh et al.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 7,286,507 B1
`Oct. 23, 2007
`
`(54) METHOD AND SYSTEM FOR
`DYNAMICALLY ROUTING BETWEEN A
`RADIO ACCESS NETWORK AND
`DISTRIBUTED ANTENNA SYSTEM REMOTE
`ANTENNA UNITS
`
`(75)
`
`Inventors: Dae-Sik Oh, Overland Park, KS (US);
`Timothy W. Sill, Platte City, MO (US)
`
`(73)
`
`Assignee: Sprint Spectrum L.P., Overland Park,
`KS (US)
`
`(*)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`USC 154(b) by 108 days.
`
`(21)
`
`(22)
`
`(51)
`
`(52)
`
`(58)
`
`(56)
`
`Appl. No.2 11/243,023
`
`Filed:
`
`Oct. 4, 2005
`
`Int. Cl.
`(2006.01)
`H04Q 7/20
`(2006.01)
`H04Q 7/22
`US. Cl. .................... .. 370/334; 370/329; 370/328;
`370/312; 370/313; 370/340; 370/341; 455/426.1;
`455/426.2; 455/466; 455/403; 455/422.1;
`455/500
`Field of Classi?cation Search .............. .. 370/334,
`370/329, 328, 338, 312, 313, 340, 341; 455/426.1,
`455/426.2, 422, 403, 466, 414.1, 445, 500,
`455/517, 561, 567.1, 560
`See application ?le for complete search history.
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`2001/0002198 A1* 5/2001 Lindgren et a1. ......... .. 370/466
`2003/0216140 A1* 11/2003 Chambert .............. .. 455/4261
`2004/0139201 A1* 7/2004 Chaudllary et al. ....... .. 709/229
`2005/0213555 A1 *
`9/2005 Eyuboglu et a1. ......... .. 370/349
`
`OTHER PUBLICATIONS
`
`LGC Wireless®, http://web.archive.org/web/20050207125302/
`http://wwwlgcwireless. .
`., dated 2005.
`Coverage Enhancement Solutions, Juni America, Inc., “Adding
`Value to the Mobile World!”, Jun. 2005.
`
`* cited by examiner
`
`Primary ExamineriKeith Ferguson
`
`(57)
`
`ABSTRACT
`
`An improved mechanism for routing communication traf?c
`between a radio access network and distributed antenna
`system (DAS) remote antenna units. In accordance with an
`exemplary embodiment of the invention, a DAS hub and
`each DAS antenna unit served by the DAS hub will sit as a
`respective node on a packet-switched network. Further, the
`DAS hub will maintain or otherwise have access to a set of
`mapping data that correlates one or more radio access
`network coverage segments (e.g., cell sectors) with one or
`more DAS antenna unit addresses on the packet-switched
`network (e.g., IP addresses). Advantageously, an adminis
`trator of the DAS can then con?gure or alter the mapping
`data whenever desired, to conveniently set the RAN-DAS
`correlations and to thereby distribute RAN coverage in a
`desired manner throughout the DAS.
`
`7,099,339 B1 *
`
`8/2006 Wang et a1. .............. .. 370/401
`
`17 Claims, 5 Drawing Sheets
`
`TRANSPORT
`NETWORNS)
`
`1,
`
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`
`I_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___l
`
`DISTRIBUTED ANTENNA SYSTEM
`
`

`

`U.S. Patent
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`0a. 23, 2007
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`Sheet 1 0f 5
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`U.S. Patent
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`Oct. 23, 2007
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`U.S. Patent
`U.S. Patent
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`0a. 23, 2007
`Oct. 23, 2007
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`Sheet 3 0f 5
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`U.S. Patent
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`Oct. 23, 2007
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`Sheet 4 of 5
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`U.S. Patent
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`0a. 23, 2007
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`Sheet 5 0f 5
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`US 7,286,507 B1
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`MAINTAIN AT A DAS A SET OF
`MAPPING DATA THAT
`CORRELATES IP ADDRESSES OF
`DAS ANTENNA UNITS WITH ONE \
`OR MORE COVERAGE SEGMENTS 90
`OF A RAN
`
`Y
`
`USE THE MAPPING DATA TO
`ROUTE COMMUNICATION
`TRAFFIC BETWEEN THE RAN \
`AND THE DAS ANTENNA UNIT
`92
`IP ADDRESSES
`
`l
`
`CHANGE THE MAPPING DATA
`SO AS TO ALTER
`CORRELATIONS BETWEEN THE
`RAN COVERAGE SEGMENTS
`AND DAS ANTENNA UNIT
`IP ADDRESSES, THEREBY
`ALTERING DISTRIBUTION OF
`RAN COVERAGE AMONG
`DAS ANTENNA UNITS
`
`-\
`94
`
`FIG. 5
`
`

`

`US 7,286,507 B1
`
`1
`METHOD AND SYSTEM FOR
`DYNAMICALLY ROUTING BETWEEN A
`RADIO ACCESS NETWORK AND
`DISTRIBUTED ANTENNA SYSTEM REMOTE
`ANTENNA UNITS
`
`FIELD OF THE INVENTION
`
`The present invention relates to wireless communications
`and more particularly to the arrangement and operation of
`distributed antenna systems.
`
`DESCRIPTION OF RELATED ART
`
`The art and popularity of wireless communications has
`grown signi?cantly over recent years. Indeed, millions of
`people are engaging in voice and data communications using
`wireless communication devices such as cellular telephones
`and Personal Digital Assistants (PDAs). In principle, a user
`can communicate over the Internet or call anyone over the
`Public Switched Telephone Network (PSTN) from any place
`inside the coverage area of a cellular wireless network.
`In a typical cellular wireless network, an area is divided
`geographically into a number of cells and cell sectors, each
`de?ned by a radio frequency (RF) radiation pattern from a
`respective base transceiver station (BTS) antenna. The base
`station antennae in the cells are in turn coupled to a base
`station controller (BSC), which is then coupled to a tele
`communications switch or gateway, such as a mobile switch
`ing center (MSC) or packet data serving node (PDSN) for
`instance. The switch or gateway may then be coupled with
`a transport network, such as the PSTN or a packet-switched
`network (e.g., the Internet). Conveniently with this arrange
`ment, when a wireless communication device is positioned
`within a given sector, the device can communicate with
`entities on the transport network via a communication path
`comprising the BTS, the BSC, the switch or gateway, and
`the transport network.
`To provide a high quality of wireless communication
`service, it is desirable for wireless coverage areas such as
`cells and cell sectors to be adjacent to one another, leaving
`no intermediate gaps in which service is unavailable. Like
`wise, it is desirable to arrange each wireless coverage area
`such that its corresponding BTS has the capacity to handle
`all the communication sessions carried out by users at peak
`times within the coverage area. Thus, a central business
`district in which many wireless devices are used during the
`business day is typically provided with a higher density of
`base stations, each producing smaller coverage areas than
`would be provided in outlying areas.
`Designing a cellular network for a high quality of service
`thus involves a number of issues. For example, to avoid gaps
`in service areas, or so-called “coverage holes,” it may appear
`desirable to design larger cells that are served by base
`stations with high-power antennas. However, a larger cell
`would encompass more subscribers and may cause calls to
`be dropped if the capacity of the BTS is exceeded. On the
`other hand, increasing the number (and, accordingly, the
`density) of base stations can be costly, not to mention the
`regulatory and architectural challenge of ?nding (and leas
`ing) a desirable location for each BTS and the task of
`arranging for backhaul communications from each new BTS
`to other network entities such as the BSC and MSC.
`To provide ?exibility in the design of mobile telephone
`networks, “distributed antenna systems,” also known as
`remote antenna systems, have been developed. Generally
`speaking, a distributed antenna system (DAS) functions to
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`extend the RF coverage of one or more BTSs into a desired
`area, such as a building or of?ce campus for instance. To
`accomplish this, a DAS typically includes a distribution hub
`unit (DHU) that engages in RF communication with a BTS
`and that is linked by ?ber, UTP, or coax cable connections
`with multiple remote antenna units positioned strategically
`throughout the area to be covered. The DHU may thus
`receive incoming RF communication traf?c from the BTS
`and pass the tra?ic over the various cable connections to the
`remote antenna units, which would then emit the incoming
`tra?ic wirelessly for receipt by devices operating in their
`localiZed antenna coverage areas. Similarly, the remote
`antenna units may receive outgoing RF communication
`tra?ic from devices operating in their coverage areas and
`may pass the traf?c over their various cable connections to
`the DHU, and the DHU may then transmit the outgoing
`tra?ic to the BTS.
`For instance, to provide improved wireless coverage
`within a high-rise building, a DHU could be installed in a
`basement of the building and could be set to communicate
`by a wireless, ?ber, and/ or or cable link with a cellular BTS.
`Further, one or more remote antenna units could be installed
`on each ?oor of the high-rise, and each antenna unit may be
`coupled by a respective ?ber, UTP, or coax cable connection
`with the DHU in the basement. In practice, users operating
`on any ?oor of the building can then conveniently engage in
`cellular wireless communication, via a communication path
`comprising (i) a remote antenna unit on their ?oor, (ii) the
`cable connection between the remote antenna unit and the
`DHU, and (iii) the RF link between the DHU and the BTS.
`
`SUMMARY
`
`The present invention provides an improved mechanism
`for routing communication traf?c between a radio access
`network and DAS remote antenna units. In accordance with
`an exemplary embodiment of the invention, a DHU and each
`DAS remote antenna unit served by the DHU will sit as a
`respective node on at least one packet-switched network
`(e.g., IP network, ATM network, etc.) Further, the DHU will
`maintain a set of mapping data that correlates one or more
`coverage segments of a cellular radio access network with
`one or more DAS antenna unit addresses on the packet
`switched network (e.g., DAS antenna unit IP addresses).
`Advantageously, an administrator of the DAS can then alter
`the mapping data whenever desired, to conveniently change
`the RAN-DAS correlations, so as to distribute RAN cover
`age in a desired manner among the DAS antenna units.
`In one respect, an exemplary embodiment of the invention
`may thus take the form of a DAS that includes a DAS hub
`that communicates with a cellular RAN on one or more
`RAN coverage segments de?ned by the RAN, and that
`includes a plurality of DAS antenna units. In accordance
`with the exemplary embodiment, a packet-switched network
`will connect the DAS hub with the DAS antenna units, with
`each DAS antenna unit having a respective IP address on the
`packet-switched network. Data storage, maintained by the
`DAS hub for instance, will then contain mapping data that
`correlates the DAS antenna units with the one or more RAN
`coverage segments, and the DAS hub will use the mapping
`data to route communication traf?c between the one or more
`RAN coverage segments and the IP addresses of the DAS
`antenna units.
`Each RAN coverage segment may take the form of a cell
`or cell sector de?ned in a particular way by the RAN. For
`instance, each coverage segment may be a CDMA sector
`having a respective PN-olTset to distinguish it from adjacent
`
`

`

`US 7,286,507 B1
`
`20
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`3
`sectors. As other examples, each coverage segment may be
`a cell or sector operating on a respective RF frequency
`channel or coverage areas produced by respective base
`stations. A given RAN coverage segment can further be a
`combination of sectors or other coverage areas.
`In operation, When the DAS hub of the exemplary system
`receives incoming communication traf?c (signaling and/or
`bearer data) in a source RAN coverage segment (e.g., traf?c
`transmitted in an RAN sector de?ning a particular PN
`olfset), the DAS hub may use the mapping data to identify
`at least one destination DAS antenna unit IP address corre
`sponding With the source RAN coverage segment. The DAS
`hub may then forWard the incoming communication traf?c
`via the packet-switched netWork to the identi?ed destination
`IP address(es).
`Similarly, When the DAS hub receives outgoing commu
`nication traf?c (signaling and/or bearer data) via the packet
`sWitched netWork from a source IP address of a DAS
`antenna unit, the DAS hub may use the mapping data to
`identify at least one destination RAN coverage segment
`corresponding With the source IP address, and the DAS hub
`may forWard the outgoing communication traf?c in the
`identi?ed destination RAN coverage segment(s) to the
`RAN.
`Preferably, the mapping data maintained in the DAS data
`storage Will be alterable, so as to alloW an administrator or
`automated system to modify the correlations betWeen RAN
`coverage segments and DAS antenna unit IP addresses. To
`30
`facilitate this, for instance, DAS hub may provide a Web
`based user-interface through Which an administrator can
`vieW and edit the mapping data. In this Way, the mapping
`data can be changed Whenever desired, so as to distribute
`coverage of the RAN in a desired manner throughout the
`DAS.
`In another respect, an exemplary embodiment of the
`invention may take the form of a method that involves
`maintaining and using mapping-data in a DAS. Such a
`method may involve (i) maintaining at the DAS a set of
`mapping data that correlates IP addresses of DAS antenna
`units With one or more RAN coverage segments, and (ii)
`using the mapping data to route communication traf?c
`betWeen the RAN and the DAS antenna unit IP addresses.
`Further, the method may involve changing the mapping
`data so as to alter correlations betWeen the RAN coverage
`segments and DAS antenna unit IP addresses, thereby modi
`fying distribution of RAN capacity among the various DAS
`antenna units. For example, the change in mapping data
`could involve establishing a correlation betWeen a given
`RAN coverage segment and a DAS antenna unit IP address
`With Which the RAN coverage segment Was not previously
`correlated. As another example, the change in mapping data
`could involve establishing a correlation betWeen a given
`DAS antenna unit IP address and a RAN coverage segment
`With Which the IP address Was not previously correlated. As
`yet another example, the change may involve removing one
`or more correlations that Were de?ned by the mapping data.
`These as Well as other aspects, advantages, and alterna
`tives Will become apparent to those of ordinary skill in the
`art by reading the folloWing detailed description With ref
`erence Where appropriate to the accompanying draWings.
`Further, it should be understood that the description pro
`vided in this summary and beloW is set forth by Way of
`example only.
`
`4
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a simpli?ed block diagram of a communication
`system arranged in accordance With the exemplary embodi
`ment.
`FIG. 2 is an illustration of an exemplary set of mapping
`data that a DAS hub can use to route communication traf?c
`betWeen a RAN and various DAS antenna unit IP addresses.
`FIG. 3 is a simpli?ed block diagram of a DAS hub
`arranged in accordance With the exemplary embodiment.
`FIG. 4 is a simpli?ed block diagram of a DAS antenna
`unit arranged in accordance With the exemplary embodi
`ment.
`FIG. 5 is a How chart depicting functions that can be
`carried out in accordance With the exemplary embodiment.
`
`DETAILED DESCRIPTION
`
`Referring to the draWings, FIG. 1 is a simpli?ed block
`diagram of a system arranged in accordance With an exem
`plary embodiment of the invention. It should be understood,
`of course, that this and other arrangements and functions
`described herein are provided by Way of example only and
`that numerous variations may be possible. For instance,
`elements can be added, omitted, combined, distributed,
`reordered, repositioned, or otherWise changed While remain
`ing Within the scope of the invention as de?ned by the
`claims. Further, it should be understood that various func
`tions described herein can be carried out by hardWare,
`?rmware, and/or softWare (e.g., one or more processors
`programmed With machine language instructions to carry
`out the functions).
`The system of FIG. 1 includes at its center a radio access
`netWork (RAN) 12, Which functions in a generally knoWn
`manner to engage in radio frequency (RF) communication
`With one or more client devices and to provide the client
`devices With connectivity to one or more transport netWorks
`14, such as the PSTN or the Internet for instance. RAN 12
`can take various forms, the details of Which are not particu
`larly signi?cant. As shoWn by Way of example, for instance,
`RAN 12 may include a BSC 16 and one or more BTSs 18,
`With each BTS having radio equipment and an antenna
`structure (not shoWn) for engaging in RF air interface
`communication With Wireless client devices 20, 22, such as
`cell phones or Wirelessly-equipped personal digital assis
`tants (PDAs) or computers.
`Generally speaking, RAN 12 de?nes one or more RAN
`coverage segments, each of Which constitutes a mechanism
`in or through Which the RAN communicates With client
`devices that it serves. A RAN coverage segment may be a
`cell, cell sector, or other coverage area of the RAN, de?ned
`by a directional radiation pattern from a BTS of the RAN for
`instance. Further, or alternatively, a RAN coverage segment
`may be de?ned as the portion of RAN coverage that uses a
`particular carrier frequency and/or a particular spreading
`code or other parameter to characteriZe communications.
`For instance, in a system operating according to the Well
`knoWn CDMA protocol, an example RAN coverage seg
`ment may be a cell sector in Which communications occur on
`a 1.25 MHZ channel centered around a particular carrier
`frequency and are modulated using a PN-olfset code locally
`unique to the sector and/or using one or more particular
`Walsh codes. Other examples of RAN coverage segments
`are possible as Well.
`The system of FIG. 1 further includes a distributed
`antenna system (DAS) 24, Which functions advantageously
`to extend coverage of RAN 12 into a building, campus, or
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`US 7,286,507 B1
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`5
`other designated area. DAS 24 includes a DAS hub 26,
`Which communicates With RAN 12 over one or more
`physical-layer connections 28. Generally, each physical
`layer connection betWeen RAN 12 and DAS hub 26 facili
`tates an exchange of RF traf?c (bearer and/or signaling)
`betWeen the RAN 12 and the DAS hub 26. As such, each
`physical-layer connection can take various forms, examples
`of Which include an RF-over-air connection, an RF-over
`?ber connection, and an RF-over-cable (or hybrid ?ber/
`cable) connection. Further, a given physical-layer connec
`tion can be a combination of these or other types of links,
`and RF signals can be converted to and from other forms
`throughout each connection if desired.
`To provide an RF-over-air connection betWeen RAN 12
`and DAS hub 26, for example, DAS hub 26 may be
`equipped With one or more antennas (such as a ?xed antenna
`structure or a dynamically con?gurable smart-antenna, for
`example), to facilitate air interface communication With the
`RAN 12. The antenna(s) may facilitate directional commu
`nication With one or more BTSs of the RAN and/or With a
`single BTS of the RAN. In practice, the DAS hub 26 may be
`situated in a basement and/ or equipment room of a building
`or campus that is to be served by the DAS, and the DAS hub
`26 may be coupled by an RF cable connection With an
`antenna structure on a roof or external Wall, to enable
`optimal Wireless communication betWeen the antenna(s) and
`the RAN.
`To provide an RF-over-?ber connection betWeen the RAN
`12 and the DAS hub 26, as another example, BTS radio
`equipment of the RAN can be connected by one or more
`?ber-optic cables in a Well knoWn manner With the DAS hub
`26. In this Way, signals that are to be communicated from the
`RAN 12 to the DAS hub 26 Would be converted to optical
`pulses if necessary and sent over the ?ber-optic cable(s)
`from the RAN to the DAS hub 26, Where the signals may
`then be converted to a form suitable for handling by the DAS
`24. Similarly, signals that are to be communicated from the
`DAS hub 26 to the RAN 12 Would be converted to optical
`pulses at the DAS hub 26 if necessary and sent over the
`?ber-optic cable(s) from the DAS hub 26 to the BTS radio
`equipment, Where the signals may then be converted to a
`form suitable for handling by the RAN 12.
`In a preferred embodiment, DAS hub 26 may include an
`RF communication chipset such as a “mobile station
`modem” (MSM) of the type available from Qualcomm
`Incorporated, Which comes in various models to facilitate
`RF communication according to various radio-link proto
`cols. Such a chipset may, for instance, include a rake
`receiver and/or other circuitry that is adapted to receive and
`resolve incoming signals based on characteristics such as
`carrier-frequency, spreading-code, and so forth, and to trans
`mit outgoing signals With similar characteristics as desired.
`That Way, the DAS hub 26 may discern the RAN coverage
`segment of traf?c arriving from RAN 12, and the DAS hub
`26 may transmit outgoing tra?ic in a desired RAN coverage
`segment to RAN 12.
`As shoWn in FIG. 1, DAS 24 further includes a plurality
`of DAS remote antenna units 28, 30, 32, one or more of
`Which may situated respectively in each of a plurality of
`Zones of the DAS 24 coverage area so as to provide RF
`coverage in each Zone and to facilitate air interface com
`munication With Wireless client devices 34, 36, 38, such as
`cell phones or Wirelessly-equipped PDAs or computers
`operating in the Zones. In practice, for example, one or more
`DAS antenna units may be situated in each of a plurality of
`rooms or ?oors of a building or campus, to provide RF
`coverage respectively in each room or ?oor. Although only
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`three DAS antenna units are shoWn in FIG. 1, it should be
`understood that more or feWer DAS antenna units could be
`provided. Preferably, hoWever, the DAS 24 Will include at
`least tWo DAS antenna units, facilitating distribution of RF
`signals among at least tWo Zones of the DAS coverage area.
`In accordance With the exemplary embodiment, the DAS
`hub 26 and each DAS antenna unit Will sit as a respective
`node on a common packet-switched netWork (or plurality of
`packet-switched netWorks) 40, to facilitate packet-data com
`munication betWeen the DAS hub and each DAS antenna
`unit. The packet-switched netWork 40 is preferably a con
`ventional IP netWork of the type commonly used in many
`of?ces and homes. More generally, the packet-switched
`netWork can be a local area netWork (LAN), Wireless local
`area netWork (WLAN) (e.g., an IEEE 802.11 Wireless exten
`sion of a LAN), metropolitan area netWork (MAN), or any
`combination of these or other packet-switched netWorks,
`possibly comprising all or part of the Internet, Whether
`private and/ or public. As such, the packet-switched netWork
`40 may include one or more routers, sWitches, and/or hubs
`42 arranged to route or pass packet-data traf?c through the
`netWork from one point to another.
`Conveniently, the DAS 24 (including the hub and antenna
`units) may be installed in a building, campus, or other area
`that is already equipped (e.g., Wired) With the packet
`sWitched netWork 40. Thus, the packet-switched netWork 40
`may be an existing packet-switched netWork that is used for
`purposes other than distribution of DAS traf?c (such as a
`home or corporate computer netWork for instance). Alter
`natively, the packet-switched netWork 40 may be installed at
`the time the DAS 24 is installed, to facilitate operation of the
`DAS in the manner presently described.
`DAS hub 26 and each of the DAS antenna units 28, 30,
`32 respectively include a mechanism for connecting With the
`packet-switched netWork, for acquiring an IP address on the
`packet-switched netWork, and for sending and receiving IP
`data packets (e.g., TCP/IP or UDP/IP) over the packet
`sWitched netWork. By Way of example, the DAS hub 26 and
`each DAS antenna unit may include a respective built-in
`netWork interface module such as an Ethernet netWork
`interface card (NIC) that provides an RJ-45 jack suitable for
`coupling With an Ethernet cable tied to the router/sWitch and
`that can be programmatically con?gured to use a particular
`IP address as its IP address on netWork 40.
`Alternatively, an 802.11 or other WLAN connection can
`be provided, assuming one or more suitably positioned
`802.11 access points are provided, in Which case the DAS
`hub 26 and/or one or more of the DAS antenna units could
`be equipped With 802.11 client modules and antennas for
`communicating With the 802.11 access point(s) and for
`acquiring an IP address for communication on netWork 40
`(possibly through use of netWork address translation). Such
`an 802.11 or other WLAN link could thus provide a mecha
`nism for communication of RF signals over netWork 40
`betWeen the DAS hub 26 and each DAS antenna unit.
`Still alternatively, a DAS hub or DAS antenna unit that
`does not have a built-in netWork interface but that has an
`input/output port of another type (e.g., a ?ber or RF cable
`interface) could be retro?tted to Work With the present
`invention, by coupling the input/output port (through an
`appropriate signal converter, such as an electro-optic cou
`pler) With a device such as a computer that is equipped With
`a mechanism suitable for connecting With netWork 40 and
`for using a particular IP address for communicating on the
`netWork. With such an arrangement, the external netWork
`connection mechanism Would be considered to be function
`ally part of the hub or antenna unit, and thus the hub or
`
`

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`US 7,286,507 B1
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`7
`antenna unit Would be considered to have the IP address that
`the external netWork-connection mechanism has on network
`40
`In a preferred embodiment, IP addresses Will be statically
`assigned to the DAS hub 26 and each DAS antenna unit 28,
`30, 32. To facilitate this, the DAS hub and each DAS
`antenna unit may be programmed With respective Web server
`logic and a respective Web-based setup interface With Which
`a user can interact via a Web broWser on an user terminal
`(e.g., PC) 44 connected With netWork 40. For this purpose,
`the DAS hub and each DAS antenna unit may have a
`respective prede?ned IP address at Which their setup inter
`faces can be accessed. Thus, a user operating terminal 44
`may broWse to the setup interface of the DAS hub 26 and
`assign the DAS hub 26 a particular IP address on netWork 40
`for purposes of communicating With the DAS antenna units,
`and the user may broWse to the setup interface of each DAS
`antenna unit and assign the DAS antenna another IP address
`on netWork 40 for purposes of communicating With DAS
`hub 26. Preferably, the IP addresses assigned to the DAS hub
`and to each DAS antenna unit Will be on a common IP
`subnet, in order to facilitate IP communication betWeen the
`DAS hub 26 and each DAS antenna unit.
`In an alternative embodiment, IP addresses can be
`assigned dynamically to the DAS hub 26 and to each DAS
`antenna unit, using the Dynamic Host Control Protocol
`(DHCP) or another dynamic IP address assignment mecha
`nism. To use DHCP, a DHCP server or DHCP server
`function (not shoWn) Would be provided on netWork 40,
`such as in sWitch/router 42 for instance, or even as part of
`DAS hub 26 itself. While dynamic IP address assignment is
`feasible, hoWever, static assignment of IP addresses is pre
`ferred, in order to maintain the integrity of mapping data in
`the DAS hub 26, as Will be described next.
`In accordance With the exemplary embodiment, as shoWn
`generally in FIG. 1, DAS hub 26 Will maintain in data
`storage a set of mapping data 46. Mapping data 46 serves to
`correlate one or more RAN coverage segments of RAN 12
`With one or more IP addresses of the various DAS antenna
`units in DAS 24, to thereby indicate hoW DAS hub 26 should
`distribute capacity of RAN 12 among the various Zones of
`the DAS 24 via packet-sWitched netWork 40. In operation,
`When DAS hub 26 receives incoming traf?c in a particular
`RAN coverage segment from RAN 12, DAS hub 26 may
`automatically consult the mapping data 46 to determine one
`or more DAS antenna unit IP addresses to Which it should
`route that incoming traf?c via packet-sWitched netWork 40.
`Similarly, When DAS hub 26 receives outgoing tra?ic from
`a particular DAS antenna unit IP address on packet-sWitched
`netWork 40, DAS hub 26 may automatically consult the
`mapping data 46 to determine one or more RAN coverage
`segments in Which it should transmit the outgoing data to
`RAN 12.
`In a preferred embodiment, the mapping data Will provide
`symmetric correlations for incoming and outgoing traf?c, in
`order to alloW RAN 12 to communicate With a Wireless
`device in both directions on a common RAN coverage
`segment. For example, the mapping data may correlate a
`given RAN coverage segment symmetrically With tWo par
`ticular DAS antenna unit IP addresses, so as to indicate that
`(i) When the DAS hub receives incoming traf?c in the given
`RAN coverage segment, the DAS hub should route the
`incoming traf?c via netWork 40 to both DAS antenna unit IP
`addresses and (ii) When the DAS hub receives outgoing
`traf?c from either of the tWo DAS antenna unit IP addresses,
`the DAS hub should transmit the outgoing traf?c to RAN in
`the given RAN coverage segment.
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`Applying that example in practice, When the DAS hub 26
`receives incoming traf?c in the given RAN coverage seg
`ment, the DAS hub 26 may refer to the mapping data to
`determine that the given RAN coverage segment corre
`sponds With the tWo particular DAS antenna unit IP
`addresses. In response, the DAS hub 26 may then convert
`the incoming traf?c to a digitiZed bit stream if necessary,
`packetiZe the bit stream into a sequence of IP packets, and
`transmit those IP packets via netWork 40 to each one of the
`tWo corresponding DAS antenna unit IP addresses. Upon
`receipt of those IP packets at the DAS antenna units having
`the destination IP addresses, each recipient DAS antenna
`unit may then depacketiZe the digitiZed bit stream, convert
`the bit stream to an RF signal, and emit the RF signal via its
`antenna for receipt by any Wireless client devices operating
`in its local coverage area.
`Conversely, When either of the tWo DAS antenna units
`receives outgoing tra?ic from a Wireless client device oper
`ating in its local coverage area, the DAS antenna unit may
`convert the outgoing traf?c to a digitiZed bit stream if
`necessary, packetiZe the bit stream into a sequence of IP
`packets, and transmit those IP packets via netWork 40 from
`its IP address to the IP address of the DAS hub 26. Upon
`receipt of those IP packets, the DAS hub 26 may then refer
`to the mapping data to determine that the source IP address
`of the packets corresponds With the given RAN coverage
`segment. Thus, the DAS hub 26 may depacketiZe the digi
`tiZed bit stream, convert the bit stream to an RF signal, and
`transmit the RF signal in the given RAN coverage segment
`to the RAN 12.
`In an alternative embodiment, the mapping data 46 could
`de?ne asymmetric correlations betWeen RAN coverage seg
`ments and DAS antenna unit IP addresses. For instance, the
`mapping data 46 could specify that (i) incoming traf?c in a
`particular RAN coverage segment A should be routed to
`DAS antenna unit IP addresses 1, 2, and 3, but that (ii)
`outgoing traf?c from DAS antenna unit IP address 1 should
`be routed in another RAN coverage segment B, and (iii)
`outgoing traffic from DAS antenna unit IP addresses 2 and
`3 should be routed in yet another RAN coverage segment C.
`Such asymmetric mapping could give rise to greater com
`plexity and may thus be undesirable in many situations.
`HoWever, in some situations, such as Where a reason exists
`to treat forWard link and reverse link communications sepa
`rately, asymmetric mapping could be desirable.
`Mapping data 46 can take various forms, the speci?cs of
`Which are not critical. As a simple example, for instance, the
`mapping data may take the form of a data table that lists
`RAN coverage segments in one column and corresponding
`DAS unit IP addresses in another column. When the DAS
`hub 26 receives incoming tra?ic in a given RAN coverage
`segmen