(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2007/0008939 A1
`(43) Pub. Date:
`Jan. 11, 2007
`Fischer
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`US 20070008939A1
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`PROVIDING WIRELESS COVERAGE INTO
`SUBSTANTIALLY CLOSED ENVIRONMENTS
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`ABSTRACT
`
`Inventor: Larry G. Fischer, Waseca, MN (US)
`Correspondence Address:
`FOGG AND ASSOCIATES, LLC
`P.O. BOX 581339
`MINNEAPOLIS, MN 55458-1339 (US)
`Assignee: ADC Telecommunications, Inc., Eden
`Prairie, MN (US)
`Appl. No.:
`11/150,820
`
`Filed:
`
`Jun. 10, 2005
`
`Publication Classification
`
`Int. C.
`(2006.01)
`H04Q 7/24
`U.S. Cl. .............................................................. 370/338
`
`A communication system is provided. The communication
`system includes a master host unit that is adapted to com
`municate analog wireless signals with a plurality of service
`provider interfaces and that is adapted to send and receive
`digitized spectrum over a plurality of communication links.
`The master host unit includes circuitry for converting
`between analog wireless signals and digitized spectrum. The
`communication system further comprises at least one remote
`server unit that is communicatively coupled to the master
`host unit over a digital communication medium. The at least
`one remote server unit is adapted to convert between analog
`wireless signals and digitized spectrum and is adapted to
`amplify the analog wireless signals. The communication
`system further includes a plurality of remote units that are
`each communicatively coupled to one of the at least one
`remote server units over an analog communication medium.
`Each of the plurality of remote units is adapted to transmit
`and receive wireless signals over a plurality of air interfaces
`for the associated service provider interfaces.
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`102
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`114-1
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`unit
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`Remote
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`Patent Application Publication
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`Jan. 11, 2007 Sheet 1 of 5
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`US 2007/0008939 A1
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`Patent Application Publication Jan. 11, 2007 Sheet 2 of 5
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`US 2007/0008939 A1
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`Master Host Unit
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`Service
`provider
`interface
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`Power Supply
`(e.g., UPS)
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`210
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`Patent Application Publication Jan. 11, 2007 Sheet 3 of 5
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`US 2007/0008939 A1
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`Patent Application Publication
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`Jan. 11, 2007 Sheet 4 of 5
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`Patent Application Publication
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`Jan. 11, 2007 Sheet 5 of 5
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`US 2007/0008939 A1
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`Jan. 11, 2007
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`PROVIDING WIRELESS COVERAGE INTO
`SUBSTANTIALLY CLOSED ENVIRONMENTS
`
`BACKGROUND
`0001. In recent years, the telecommunications industry
`has experienced rapid growth by offering a variety of new
`and improved services to customers. This growth has been
`particularly notable in the area of wireless communications,
`e.g., cellular, personal communication services (PCS) and
`other mobile radio systems. One of the factors that has led
`to the rapid growth in the wireless arena is the objective of
`allowing a user to be reached any time, and anywhere.
`Unfortunately, the industry has not been able to reach this
`goal even though large and Small companies and various
`consortiums are frantically building vast networks in an
`effort to capture a share of this booming market.
`0002 Despite their efforts to provide seamless and blan
`ket coverage for wireless telecommunications, areas of
`limited wireless coverage still exist in heavily populated
`regions. One particular difficulty is communication within a
`Substantially closed environment, such as a building or other
`structure which can interfere with radio frequency transmis
`sions. In these situations, the structure itself acts as a barrier
`and significantly attenuates or reduces the signal strength of
`the radio waves to the point that transmission is virtually
`impossible at the frequency and power levels used in these
`systems.
`0003) The industry has developed a number of options to
`extend coverage into buildings and other Substantially
`closed environments. For example, one solution to this
`problem has been to distribute antennas within the building.
`Typically, these antennas are connected to an RF signal
`Source by dedicated coaxial cable, optical fiber, and, more
`recently, unshielded twisted pair wires. In such systems,
`various methods of signal conditioning and processing are
`used, ranging from Straight bi-directional on-frequency
`amplification and band pass filtering to select which service
`or service provider to transport, to frequency conversion
`methods to move the signals to a more desirable segment of
`the frequency spectrum for transport. Some systems also use
`passive antenna methods and “leaky' coaxial cable to radi
`ate signals within the desired area without any signal con
`ditioning. Unfortunately, with the explosive growth in the
`wireless market, these solutions often are too limited in
`capacity to carry signals for the various services and service
`providers into the closed environment. Thus, the limited
`benefits of Such systems, at times, can be outweighed by the
`costs associated with the installation and maintenance of the
`systems.
`0004 For the reasons stated above, and for other reasons
`stated below which will become apparent to those skilled in
`the art upon reading and understanding the present specifi
`cation, there is a need in the art for an economically viable
`system and method for distributing wireless signals in a
`Substantially closed environment.
`
`SUMMARY
`0005 Embodiments of the present invention provide
`solutions to the problems identified above. In particular,
`embodiments of the present invention enable economical
`distribution of wireless signals in a Substantially closed
`environment.
`
`In one embodiment, a communication system is
`0006.
`provided. The communication system includes a master host
`unit that is adapted to communicate analog wireless signals
`with a plurality of service provider interfaces and that is
`adapted to send and receive digitized spectrum over a
`plurality of communication links. The master host unit
`includes circuitry for converting between analog wireless
`signals and digitized spectrum. The communication system
`further comprises at least one remote server unit that is
`communicatively coupled to the master host unit over a
`digital communication medium. The at least one remote
`server unit is adapted to convert between analog wireless
`signals and digitized spectrum and is adapted to amplify the
`analog wireless signals. The communication system further
`includes a plurality of remote units that are each communi
`catively coupled to one of the at least one remote server units
`over an analog communication medium. Each of the plural
`ity of remote units is adapted to transmit and receive
`wireless signals over a plurality of air interfaces for the
`associated service provider interfaces.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0007 FIG. 1 is a block diagram of one embodiment of a
`system for providing wireless coverage into a Substantially
`enclosed environment.
`0008 FIG. 2 is a block diagram of one embodiment of a
`master host unit for the system of FIG. 1.
`0009 FIG. 3 is a block diagram of one embodiment of a
`master expansion unit for the system of FIG. 1.
`0010 FIG. 4 is a block diagram of one embodiment of
`remote server unit for the system of FIG. 1.
`0011 FIG. 5 is a block diagram of one embodiment of a
`remote unit of FIG. 1.
`
`DETAILED DESCRIPTION
`0012. In the following detailed description, reference is
`made to the accompanying drawings which form a part
`hereof, and in which is shown by way of illustration specific
`illustrative embodiments in which the invention may be
`practiced. These embodiments are described in sufficient
`detail to enable those skilled in the art to practice the
`invention, and it is to be understood that other embodiments
`may be utilized and that logical, mechanical and electrical
`changes may be made without departing from the scope of
`the present invention. The following detailed description is,
`therefore, not to be taken in a limiting sense.
`
`I. Introduction
`0013 Embodiments of the present invention provide
`improved wireless coverage into Substantially closed envi
`ronments, e.g., in buildings or other structures. Section 11
`below provides an overview of one embodiment of a net
`work topology shown in FIG. I for extending wireless
`coverage into Substantially closed environments according
`to the teachings of the present invention. In this embodi
`ment, wireless coverage for multiple service providers is
`carried into one or more structures over a transport network.
`The transport network includes two main components: a
`digital transport component and an analog transport com
`ponent. First, the digital component transports wireless
`signals as digitized spectrum over, e.g., a fiber optic cable,
`
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`US 2007/0008939 A1
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`Jan. 11, 2007
`
`free space optics, high speed copper, millimeter wave radio
`link, or other appropriate wired or wireless link for carrying
`the digital representation of the wireless spectrum. The
`digital component transports the wireless signals between a
`service provider interface, e.g., a base station transceiver, a
`repeater, or other interface to a service provider network,
`and one or more buildings or other structures that adversely
`affect the transmission of wireless communication signals.
`Second, the analog component uses analog transmission,
`e.g., analog transmission over coax or fiber optic cable, to
`carry signals to and from antennas placed throughout the
`coverage area within the structure. In some embodiments, up
`or down conversion is used to move the wireless signals to
`a portion of the spectrum to provide improved transmission
`characteristics, e.g., lower frequency for longer transmission
`distance.
`0014. The remainder of the detailed description describes
`an example implementation of the network topology to
`extend the coverage of the full 1.9 GHz PCS band and the
`800 MHz cellular band into a plurality of buildings as shown
`in FIGS. 2-5. It is understood that this embodiment is
`provided by way of example and not by way of limitation.
`The network topology described in this application is used
`in other embodiments to carry these and other wireless
`services into various environments that limit the penetration
`of standard wireless transmissions.
`0015 The example implementation shown in FIGS. 2-5
`is described in detail below. Section III describes an embodi
`ment of the master host unit of FIG. 2. Section IV describes
`an embodiment of the master expansion unit of FIG. 3.
`Section V describes an embodiment of the remote server unit
`shown in FIG. 4. Section VI describes an embodiment of a
`remote unit shown in FIG. 5.
`
`II. Network Topology
`0016 FIG. 1 is a block diagram of one embodiment of a
`system, indicated generally at 100, for providing wireless
`coverage into a Substantially enclosed environment. System
`100 transports wireless signals for a plurality of services
`offered by one or more service providers and extends the
`coverage of these systems into one or more Substantially
`enclosed environments, e.g., buildings or other structures. At
`one end of its transport architecture, system 100 includes
`service provider interface 102. Service provider interface
`102 comprises, for example, an interface to one or more of
`a base transceiver station (BTS), a repeater, a bi-directional
`amplifier, a base station hotel or other appropriate interface
`for one or more service provider networks. In one embodi
`ment, service provider interface 102 provides an interface to
`a plurality of services from one or more service providers,
`e.g., 800 MHz cellular service, 1.9 GHz personal commu
`nication services (PCS), Specialized Mobile Radio (SMR)
`services, two way paging services, video services or other
`appropriate communication service.
`0017 System 100 uses two main transport protocols to
`extend the coverage of the wireless services into the sub
`stantially enclosed environment. First, system 100 uses
`digital transport over an appropriate communication
`medium 105, e.g., optical fiber. Communication medium
`105 is represented as optical fiber in FIG. 1 by way of
`example and not by way of limitation. In other embodi
`ments, communication medium 105 comprises free space
`
`optics, high speed copper or other appropriate wired, wire
`less or optical communication medium. Advantageously, the
`use of this digital transport technology enables transport of
`the wireless signals over a significant distance. Thus, system
`100 may extend coverage for wireless services to buildings
`located at a significant distance from the interface to the
`service provider's network. Second, system 100 extends the
`reach of the digital transport into the substantially enclosed
`environment with a plurality of analog transport links to a
`plurality of remote antennas.
`0018 System 100 uses the digital transport technology
`for communication between master host unit 104 and remote
`server units 106, and 108-1 to 108-N. In one embodiment,
`master host unit 104 includes a plurality of ports to subtend
`remote server units. By way of example and not by way of
`limitation, master host unit 104, in one embodiment,
`includes up to six ports for Subtending remote server units.
`In a practical application, the number of ports that can be
`implemented in a master host unit 104 is primarily limited
`by the noise in the system. As shown in the example of FIG.
`1, the number of remote server units associated with a port
`of master host unit 104 is increased by interposing a master
`expansion unit 110 between the port of master host unit 104
`and the remote server units 108-1 to 108-N. The master
`expansion unit 110 digitally splits and Sums the signals
`transported between the master host unit 104 and the remote
`server units 106 and 108-1 to 108-N. In one embodiment, the
`master expansion unit 110 is adapted to Support up to 4
`remote server units. Again, the actual number of ports in a
`master expansion unit 110 is determined based on the needs
`of a given system and is primarily limited by the noise level
`in the system.
`0.019 Master host unit 104 and remote server units 106,
`and 108-1 to 108-N convert between analog wireless sig
`nals, e.g., analog RF signals, and digitized spectrum. In one
`embodiment, master host unit 104 includes a bank of indi
`vidual circuits, such as a bank of DigivanceTM Digital Host
`Units (DHUs) or FLX host unit commercially available from
`ADC Telecommunications, Inc. of Eden Prairie, Minn., that
`are each configured to operate on a selected portion of the
`wireless spectrum. In one embodiment, the DHUS convert
`between 25 MHz bands of wireless spectrum and digitized
`samples of the spectrum in the form of 20 bit words.
`Similarly, remote server units 106 and 108-1 to 108-N, in
`one embodiment, use a bank of DigivanceTM Digital Remote
`Units (DRUs) or FLX remote units, also available from
`ADC Telecommunications, Inc. to operate on the selected
`spectrum. In one embodiment, course wave division multi
`plexing (CWDM) or dense wave division multiplexing
`(DWDM) are used to aggregate the signals for the various
`services onto a single fiber between the master host unit 104
`and each of the remote server units 106, and 108-1 to 108-N.
`In one embodiment, master expansion unit 110 also includes
`a banks of individual expansion circuits such as a bank of
`DigivanceTM Digital Expansion Units (DEUs) commercially
`available from ADC Telecommunications, Inc.
`0020. The analog portion of system 100 provides com
`munication between the remote server units 106 and 108-1
`to 108-N and their respective remote units 112-1 to 112-M,
`113-1 to 113-S and 114-1 to 114-Q. The analog portion of
`system 100 uses one or more of various communication
`media, e.g., coaxial cable, fiber optic cable or the like, to
`carry the wireless signals in their native analog frequency
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`Jan. 11, 2007
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`spectrum, e.g., their assigned RF spectrum. In other embodi
`ments, the wireless signals are moved to other frequency
`spectrum for improved transport, e.g., up or down con
`verted. In one embodiment, remote server unit 106 is
`coupled to remote units 112-1 to 112-M over coaxial cable.
`In another example, signals from remote server unit 108-N
`are provided to remote units 114-1 to 114-Q over optical
`fiber in analog format.
`0021. Each remote unit includes one or more antennas
`116. In one embodiment, each remote unit Supports up to
`four antennas. In other embodiments, other appropriate
`numbers of antennas are used.
`0022. In one embodiment, remote server units provide
`power to their respective remote units. For example, remote
`server unit 106 is coupled to remote units 112-1 to 112-M
`over coaxial cable. In this embodiment, remote server unit
`106 injects power onto the coaxial cable for the circuitry of
`remote units 112-1 to 112-M. Further, remote units 112-1 to
`112-M are equipped with circuitry to extract power from the
`coaxial cable for the operation of remote units 112-1 to
`112-M.
`0023. In one embodiment, remote server units provide a
`telemetry signal to their respective remote units. The telem
`etry signal is used to adjust the gain applied to signals at the
`various remote units for the various services Supported in
`system 100. In one embodiment, the telemetry signal is
`communicated at a frequency between the spectrum for the
`various services, e.g., at a frequency of 1.4 to 1.6 GHz for
`a system running 800 MHz cellular and 1.9 GHz PCS
`services.
`0024. In one embodiment, master host unit 104 and the
`remote server units all include modems for communicating
`and transporting signals for operations, administration and
`maintenance (O.A&M) functions such as alarms and the
`like.
`0.025 The physical location of the various elements of
`system 100 varies based on the needs of a given implemen
`tation. For example, in some embodiments, the master host
`unit 104 is co-located with a base station or a base station
`hotel. In a system 100 that provides coverage into a number
`of buildings, one or more remote server terminals is pro
`vided, e.g., at a point of entry into each building. In other
`embodiments, a remote server terminal is located on each
`floor of the building. In yet other embodiments, a master
`expansion unit is provided at the point of entry into each
`building and a remote server unit is provided on each floor
`of the building. The exact location of each of the elements
`of system 100 is determined based on the specific layout and
`location of the area or areas to be covered by system 100.
`The examples provided here are not meant to be exhaustive
`and thus are not intended to be read in a limiting sense.
`0026.
`In operation, system 100 extends the coverage of at
`least two wireless services into a substantially enclosed
`environment. System 100 receives wireless signals for the
`services at service provider interface 102. Master host unit
`104 receives the wireless signals and converts the wireless
`signals to digitized form. Master host unit 104 also aggre
`gates the various services and passes these aggregated,
`digitized signals to a plurality of remote server units 106,
`and 108-1 to 108-N over a digital transport link. At each
`remote server unit, the signals for the two services are
`
`amplified and combined and transmitted over the analog link
`to a plurality of remote units. In one embodiment, telemetry
`and power are injected into the combined signal and trans
`mitted to the remote units. At the remote units, the gain of
`the signals for the services are again adjusted, e.g., based on
`the telemetry signal, and transmitted over a plurality of
`antennas in various broadcast areas in the Substantially
`enclosed environment.
`0027 Signals from wireless terminals, e.g., cell phones,
`are returned over system 100 in a similar fashion to the
`service provider interface 102.
`
`Ill. Master Host Unit
`0028 FIG. 2 is a block diagram of one embodiment of a
`master host unit, indicated generally at 200, for the system
`100 of FIG. 1. Master host unit 200 is one end of a digital
`transport link in system 100 of FIG. 1. In this embodiment,
`master host unit 200 is built around a plurality of circuits
`202-1 to 202-N that convert wireless signals between analog
`and digitized formats. In this example, the circuits 202-1 to
`202-N comprise DigivanceTM Digital Host Units or FLX
`host units commercially available from ADC Telecommu
`nications. Other circuits that perform a similar conversion
`are used in other embodiments.
`0029 Master host unit 200 communicates with a plurality
`of service providers at service provider interfaces 204-1 to
`204-M, e.g., interfaces to base transceiver stations, repeat
`ers, bi-directional amplifiers, or the like. These communi
`cations are in the form of analog wireless signals (also
`referred to herein as radio frequency (RF) signals). For
`purposes of this specification, the term “analog wireless
`signals' comprises signals in the frequency spectrum used to
`transport a wireless service, e.g., RF signals in the 800 MHz
`spectrum for cellular, RF signals in the 1.9 GHz spectrum for
`Personal Communication Services (PCS), and the like.
`These signals are referred to as analog signals even if the
`data for the service is in digital form, e.g., CDMA and
`TDMA signals, because the digital signals ride on an analog
`waveform. Advantageously, master host unit 200 enables the
`aggregation and transmission of a plurality of services to a
`plurality of buildings or other structures so as to extend the
`wireless coverage of multiple services into the structures on
`a single platform.
`0030 The interconnection of service provider interfaces
`204-1 to 204-M and DHUS 202-1 to 202-N is configured
`based on the needs of a particular system. In some embodi
`ments, multiple service provider interfaces 204-1 to 204-M
`are coupled to the same DHU 202-1 to 202-N by use of
`splitter/combiner circuits. In other embodiments, the same
`service provider interface 204-1 to 204-M is coupled to
`multiple DHUS 202-1 to 202-N. In one example, master host
`unit 200 enables the extension of both the 800 MHZ cellular
`band and the 1.9 GHz PCS band into a plurality of buildings
`over a single platform. In this embodiment, master host unit
`200 includes four DHUS 202-1 to 202-4. DHUS 202-1 to
`202-3 are dedicated to handling the three segments of the
`PCS band and DHU 202-4 is dedicated to the 800 MHZ
`band. Further, service provider interface 204-1 is a base
`transceiver station and is coupled to DHU 202-1 to provide
`the first segment of the 1.9 GHz band. Further, service
`provider interface 204-2 is also a base transceiver station
`and is coupled through splitter/combiner 206 to provide two
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`US 2007/0008939 A1
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`Jan. 11, 2007
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`PCS segments to DHUS 202-2 and 202-3. Finally, service
`provider interface 204-3 is a repeater and is coupled to
`provide 800 MHz service to DHU 202-4. The configuration
`shown in FIG. 2 is provided by way of example and not by
`way of limitation. Other configurations to Support other
`combinations of services and service providers are also
`supported by this architecture.
`0031) Each DHU 202-1 to 202-N is coupled to each of a
`plurality of multiplexer (MUX) circuits 206-1 to 206-P. The
`DHUS 202-1 to 202-N communicate digitized spectrum for
`their assigned band with MUX circuits 206-1 to 206-P. The
`number of MUX circuits 206-1 to 206-P, in one embodi
`ment, is related to the number of ports available on the
`DHUS 202-1 to 202-N. In one embodiment, the DHUs
`provide six ports, and thus a maximum of six MUX circuits
`206-I to 206-P are provided. Each MUX circuit 206-1 to
`206-P provides a port for communicating aggregated, digi
`tized signals with a remote building or other Substantially
`closed structure. In one embodiment, MUX circuits 206-1 to
`206-P comprise optical multiplexer circuits built on course
`wave division multiplexing (CWDM) or dense wave divi
`sion multiplexing (DWDM) technology. For example, in one
`embodiment, MUX circuits 206-1 to 206-P comprise OptE
`net optical multiplexers commercially available from ADC.
`Telecommunications, Inc. of Eden Prairie, Minn. In one
`embodiment, MUX circuits 206-1 to 206-P comprise passive
`multiplexer modules. In yet other embodiments, MUX cir
`cuits 206-1 to 206-P comprise electrical multiplexercircuits.
`0032 Master host unit 200 also includes circuitry for
`providing an Operations, Administration and Maintenance
`(O. A & M) channel that provides, among other things, a
`mechanism for passing alarm information in System 100 of
`FIG. 1. Master host unit 200 includes a bank of modems
`208-1 to 208-P. In one embodiment, modems 208-1 to 208-P
`are optical modems. In other embodiments, wireless or
`wired modems are used. Each modem 208-1 to 208-P is
`coupled to a corresponding MUX 206-1 to 206-P. The
`signals to and from modem 208-1 to 208-Pride on a separate
`optical carrier of the associated multiplexercircuit. Modems
`208-1 to 208-P are coupled to alarm concentrator 210.
`0033 Master host unit 200 also includes a computer 212
`that is coupled to alarm concentrator 210. In one embodi
`ment, computer 212 runs a network management system for
`system 100 of FIG.1. In one embodiment, the computer 212
`runs a network management program Such as the StarGazer
`program commercially available from ADC telecommuni
`cations, Inc. of Eden Prairie, Minn. The network manage
`ment program running on computer 212 tracks to location
`and identification of the parts of system 100. For example,
`computer 212 assigns a name and an associated location to
`each part of system 100 at system set-up.
`0034 Alarm concentrator 210 communicates and con
`centrates alarm messages and control messages for system
`100. In one embodiment, alarm concentrator 210 receives
`and concentrates alarm messages from remote units 112-1 to
`112-M, 113-1 to 113-S, and 114-1 to 114-Q in system 100.
`These alarm messages, in one embodiment, include an
`identification number for the remote unit and a status or
`alarm message. In other embodiments, other appropriate
`alarm messages are provided Such as messages reporting
`changes in the attenuation levels applied at a remote unit.
`
`0035). Power for master host unit 200 is provided through
`power Supply 214, e.g., an uninterrupted power Supply
`(UPS).
`0036). In operation, master host unit 200 communicates
`signals between a service provider interface and a number of
`remote buildings or structures. In the downstream direction,
`the master host unit 200 receives analog wireless signals
`from service provider interfaces 204-1 to 204-M. These
`analog signals are digitized in DHUS 202-1 to 202-N. Each
`DHU 202-1 to 202-N provides its output to each of MUX
`circuits 206-1 to 206-P. The MUX circuits 206-1 to 206-P
`multiplex the signals on, for example, a plurality of optical
`carriers. Each MUX circuit 206-1 to 206-P provides its
`output to, for example, a digital optical cable to transport the
`aggregated, digitized signals to a plurality of buildings or
`other enclosed structures. In the upstream direction, the
`MUX circuits 206-1 to 206-P direct the appropriate digitized
`spectrum to the associated DHUS 202-1 to 202-N for con
`version to analog wireless signals for the associated service
`provider interface 204-1 to 204-M. Modems 208-1 to 208-P
`process alarm messages for their assigned MUX circuit
`206-1 to 206-P.
`
`IV. Master Expansion Unit
`0037 FIG. 3 is a block diagram of one embodiment of a
`master expansion unit, indicated generally at 300, for the
`system 100 of FIG. 1. Master host unit 300 enables point
`to-multipoint communication in the digital transport link of
`system 100 by digitally splitting and Summing signals
`transmitted between the master host unit and the remote
`server units. In this embodiment, master expansion unit 300
`is built around a plurality of circuits 302-1 to 302-N that
`digitally split and Sum wireless signals in digitized format.
`Each circuit 302-1 to 302-N is associated with a portion of
`the wireless spectrum transported by the system. Each
`circuit 302-1 to 302-N digitally splits its assigned spectrum
`in the downstream so that the spectrum is provided to a
`plurality of remote server units. In the upstream, each circuit
`302-1 to 302-N digitally sums signals from all of the remote
`server units for its assigned spectrum. In this example, the
`circuits 302-1 to 302-N comprise DigivanceTM Digital
`Expansion Units commercially available from ADC Tele
`communications. Other circuits that perform a similar digital
`splitting and Summing are used in other embodiments.
`0038 Master expansion unit 300 communicates with a
`master host unit, e.g., master host unit 200 of FIG. 2. These
`communications are in the form of digitized spectrum for a
`plurality of services. In one embodiment, master expansion
`unit 300 is coupled to the master host unit over a fiber optic
`cable that carries the plurality of services as digitized
`spectrum with each service (digitized spectrum) associated
`with a different wavelength on the optical fiber. The number
`of services and the association of a service with a selected
`wavelength is determined based on the needs of a particular
`application. In one example, master expansion unit 300 is
`associated with a system that enables the extension of both
`the 800 MHZ cellular band and the 1.9 GHZ, PCS band into
`a plurality of buildings over a single platform. In this
`embodiment, master expansion unit 300 includes four DEUs
`302-1 to 302-4. DEUS 302-1 to 302-3 are dedicated to
`handling the three segments of the PCS band and DEU
`302-4 is dedicated to the 800 MHz band. Further, multi
`plexer (MUX) circuit 305 is coupled to DEUs 302-1 to
`
`

`

`US 2007/0008939 A1
`
`Jan. 11, 2007
`
`302-N to provide the appropriate digitized spectrum to and
`from each DEU. In one embodiment, MUX circuit 305
`comprises an optical multiplexer circuit built on course
`wave division multiplexing (CWDM) or dense wave divi
`sion multiplexing (DWDM) technology, using, e.g., an
`OptEnet optical multiplexer commercially available from
`ADC Telecommunications. In one embodiment, MUX cir
`cuit 305 comprises passive multiplexer modules. In yet other
`embodiments, MUX circuit 305 comprises electrical multi
`plexer circuits.
`0039 Each DEU 302-1 to 302-N is coupled to each of a
`plurality of multiplexer (MUX) circuits 306-1 to 306-T. The
`DEUs 302-1 to 302-N communicate digitized spectrum for
`their assigned band with MUX circuits 306-1 to 306-T. The
`number of MUX circuits 306-1 to 306-T, in one embodi
`ment, is related to the number of ports available on the DEUs
`302-1 to 302-N. In one embodiment, the DEUs provide six
`ports, and thus a maximum of six MUX circuits 306-1 to
`306-T are provided. Each MUX circuit 3.06-1 to 306-T
`provides a port for communicating aggregated, digitized
`signals for all of the Supported services with a remote
`building or other substantially closed structure. In one
`embodiment, MUX circuits 306-1 to 306-T comprise optical
`multiplexercircuits built on course wave division multiplex
`ing (CWDM) or dense wave division multiplexing
`(DWDM) technology. For example, in one embodiment,
`MUX circuits 306-1 to 306-T comprise OptEnet optical
`multiplexers commercially available from ADC Telecom
`munications, Inc. of Eden Prairie, Minn. In one embodi
`ment, MUX circuits 306-1 to 306-T comprise passive mul
`tiplexer modules. In yet other embodiments, MUX circuits
`306-1 to 306-T comprise electrical multiplexer circuits.
`0040 Master expansion unit 300 also includes circuitry
`for providing an Operations, Administration and Mainte
`nance (O. A & M) channel that provides, among other
`things, a mechanism for passing alarm information in Sys
`tem 100 of FIG.1. Master expansion unit 300 includes a first
`modem 309 that is coupled to MUX circuit 306. Modem 309
`is also coupled to alarm control unit 310. Alarm control unit
`310 is also coupled to a bank