(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2010/0177759 A1
`(43) Pub. Date:
`Jul. 15, 2010
`Fischer et al.
`
`US 20100177759A1
`
`(54) SYSTEMS AND METHODS FOR IP
`COMMUNICATION OVERA DISTRIBUTED
`ANTENNASYSTEMI TRANSPORT
`
`(75) Inventors:
`
`Larry G. Fischer, Waseca, MN
`(US); Jeffrey J. Cannon, Victoria,
`MN (US); Steven B. Stuart, Eden
`Prairie, MN (US); John M. Hedin,
`Coon Rapids, MN (US)
`
`Correspondence Address:
`FOGG & POWERS LLC
`5810 W 78TH STREET, SUITE 100
`MINNEAPOLIS, MN 55439 (US)
`
`(73) Assignee:
`
`ADC
`TELECOMMUNICATIONS,
`INC. Eden Prairie, MN (US)
`
`(21) Appl. No.:
`
`12/555,912
`
`(22) Filed:
`
`Sep. 9, 2009
`
`Related U.S. Application Data
`(60) Provisional application No. 61/144.255, filed on Jan.
`13, 2009, provisional application No. 61/144,257,
`filed on Jan. 13, 2009.
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`HO4, 3/00
`(52) U.S. Cl. ........................................................ 370/345
`(57)
`ABSTRACT
`Systems and methods for IP communication over a distrib
`uted antenna system transport are provided. In one embodi
`ment, a method for providing Ethernet connectivity over a
`distributed antenna system comprises receiving internet pro
`tocol (IP) formatted data from an internet protocol device
`coupled to a remote unit of a distributed antenna system;
`sampling wireless radio frequency (RF) signals received at
`the remote unit to produce digitized RF samples; generating a
`serial data stream for output to a host unit of the distributed
`antenna system, the serial data stream further comprising a
`multiple-timeslot communication frame providing a first par
`tition of bandwidth for transporting the digitized RF samples
`and a second partition of bandwidth for implementing an
`Ethernet pipe for transporting the IP formatted data.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`REMOTE
`UNIT
`
`DIGITAL
`RF
`ETHERNET
`PIPE
`
`REMOTE
`UNIT
`
`DIGITAL
`RF
`ETHERNET
`PIPE
`
`REMOTE -3O6
`UNIT
`
`DIGITAL
`RF
`ETHERNET
`PIPE
`
`
`
`3OO
`//
`
`25O
`
`INTERNET
`PROTOCOL
`DEVICE
`
`HOST UNIT SeRF
`
`BASEBAND
`DIGITAL RF
`
`HOST UNIT DART
`
`BROADBAND
`RF
`
`TO BTS
`
`PPACKAGED
`DATA
`
`

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`Patent Application Publication
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`Jul. 15, 2010 Sheet 1 of 5
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`US 2010/0177759 A1
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`Patent Application Publication
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`Jul. 15, 2010 Sheet 2 of 5
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`US 2010/0177759 A1
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`| EMREHIE
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`Patent Application Publication
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`Jul. 15, 2010 Sheet 3 of 5
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`US 2010/0177759 A1
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`Patent Application Publication
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`Q
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`ll
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`Patent Application Publication
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`Jul. 15, 2010 Sheet 5 of 5
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`US 2010/0177759 A1
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`RECEIVING DATA FROMAN INTERNET PROTOCOL DEVICE THE DATA
`FORMATTED FORTRANSPORT VIA AN INTERNET PROTOCOLNETWORK (P/90
`DATA) AT AREMOTE UNIT OF A DISTRIBUTEDANTENNASYSTEM
`
`CONVERTING ANALOGRF SIGNALS RECEIVED
`AT THEREMOTE UNIT INTO DIGITIZEDRFSAMPLES
`
`52O
`
`
`
`
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`MULTIPLEXING THEPDATA WITH THE DIGITIZEDRFSAMPLES INTO
`FRAMES FORTRANSMISSION TO A HOST UNIT OF THE DISTRIBUTED
`ANTENNASYSTEM
`
`53O
`
`TRANSMITTING ASUPERFRAME TO THE HOSTUNIT, THE SUPERFRAME
`COMPRISINGTIMESLOTSCARRYING THEIPDATA WITH THE DIGITIZED --90
`RF SAMPLES
`
`F.G. 5
`
`

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`US 2010/0177759 A1
`
`Jul. 15, 2010
`
`SYSTEMIS AND METHODS FOR IP
`COMMUNICATION OVERA DISTRIBUTED
`ANTENNASYSTEMI TRANSPORT
`
`CROSS-REFERENCE TO RELATED CASES
`0001. This application claims the benefit of U.S. Provi
`sional Application No. 61/144.255 filed on Jan. 13, 2009
`which is incorporated herein by reference in its entirety.
`0002 This application is related to U.S. Provisional Appli
`cation No. 61/144,257 filed on Jan. 13, 2009 entitled “SYS
`TEMS AND METHODS FOR MOBILE PHONE LOCA
`TION WITH DIGITAL DISTRIBUTED ANTENNA
`SYSTEMS, attorney docket number 100.1075 USPR and
`which is incorporated herein by reference in its entirety.
`0003. This application is related to U.S. patent application
`Ser. No.
`, filed on even date herewith, entitled “SYS
`TEMS AND METHODS FOR MOBILE PHONE LOCA
`TION WITH DIGITAL DISTRIBUTED ANTENNA SYS
`TEMS, attorney docket number 100.1075US01 and which is
`referred to herein as the 1075. Application and is incorpo
`rated herein by reference in its entirety.
`
`BACKGROUND
`0004. A Distributed Antenna System, or DAS, is a net
`work of spatially separated antenna nodes connected to a
`common node via a transport medium that provides wireless
`service within a geographic area or structure. Common wire
`less communication system configurations employ a host unit
`as the common node, which is located at a centralized loca
`tion (for example, at a facility that is controlled by a wireless
`service provider). The antenna nodes and related broadcast
`ing and receiving equipment, located at a location that is
`remote from the host unit (for example, at a facility or site that
`is not controlled by the wireless service provider), are also
`referred to as “remote units.” Radio frequency (RF) signals
`are communicated between the host unit and one or more
`remote units. In Such a DAS, the host unit is typically com
`municatively coupled to one or more base stations (for
`example, via wired connection or via wireless connection)
`which allow bidirectional communications between wireless
`subscriber units within the DAS service area and communi
`cation networks such as, but not limited to, cellular phone
`networks, the public switch telephone network (PSTN) and
`the Internet. ADAS can thus provide, by its nature, an infra
`structure within a community that can scatter remote units
`across a geographic area thus providing wireless services
`across that area.
`0005 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 specification,
`there is a need in the art for systems and methods for facili
`tation of supplemental data communication over a distributed
`antenna system transport.
`
`DRAWINGS
`
`0006 Embodiments of the present invention can be more
`easily understood and further advantages and uses thereof
`more readily apparent, when considered in view of the
`description of the preferred embodiments and the following
`figures in which:
`0007 FIG. 1 is a block diagram of a distributed antenna
`system (DAS) of one embodiment of the present invention;
`
`0008 FIG. 2 is a block diagram of a remote unit of one
`embodiment of the present invention;
`0009 FIG. 3 is a block diagram of a host unit of one
`embodiment of the present invention;
`0010 FIG. 4 illustrates a superframe structure of one
`embodiment of the present invention; and
`0011
`FIG. 5 illustrates a method of one embodiment of
`the present invention.
`0012. In accordance with common practice, the various
`described features are not drawn to scale but are drawn to
`emphasize features relevant to the present invention. Refer
`ence characters denote like elements throughout figures and
`text.
`
`DETAILED DESCRIPTION
`0013. In the following detailed description, reference is
`made to the accompanying drawings that form a part hereof,
`and in which is shown by way of specific illustrative embodi
`ments 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 with
`out departing from the scope of the present invention. The
`following detailed description is, therefore, not to be taken in
`a limiting sense.
`0014 Embodiments of the present invention provide
`point-to-point Ethernet connections (100 Base-T, for
`example) between elements of a distributed antenna system
`by adapting the digital radio frequency (RF) transport
`medium to further carry internet protocol data traffic simul
`taneously with the RF traffic. Embodiments of the present
`invention enable installation of internet protocol devices at
`remote locations (for example, to extend a Local Area Net
`work (LAN)/IP network into remote areas, or establish vari
`ous services at remote locations that benefit from having IP
`network connectivity). Internet protocol devices may thus
`include networking devices Such as Switches, routers, and
`wireless access points (for WiFi, WiMAX, LTE, for example)
`or cameras, sensors, audio and/or video devices for security,
`distributing announcements, warnings or advertising. In one
`embodiment, the Internet Protocol device is a mobile phone
`locator such as described in the 1075 Application herein
`incorporated by reference. One of ordinary skill in the art
`after reading this specification would thus realize that Such
`internet connectivity allows utilization of the remote facilities
`of a distributed antenna system to provide functions beyond
`that related to the principal RF functions of the system.
`0015 FIG. 1 is a block diagram of a distributed antenna
`system (DAS) 100 of one embodiment of the present inven
`tion. DAS 100 includes a host unit 102 and a plurality of
`remote units 106. At the physical layer, host units 102 and
`remote units 106 are interconnected via fiber optic cable as
`indicated in FIG. 1 to form a bidirectional communication
`link network comprising a plurality of point-to-point commu
`nication links shown at 130. Optionally, host units 102 and
`remote units 106 may be interconnected via coaxial cable, or
`a combination of both coaxial cable and fiber optic cable.
`Further, host units 102 and remote units 106 may be intercon
`nected via wireless technology Such as, but not limited to,
`microwave and e-band communication.
`0016 Remote units 106 each house electronic devices and
`systems used for wirelessly transmitting and receiving modu
`lated radio frequency (RF) communications via antenna 107
`
`

`

`US 2010/0177759 A1
`
`Jul. 15, 2010
`
`with one or more mobile subscriber units 108. Host unit 102
`is coupled to at least one base transceiver station (BTS) 110
`often referred to as a base station. BTS 110 communicates
`Voice and other data signals between the respective host unit
`102 and a larger communication network via a gateway 124
`coupled to a telephone system network 122 (for example, the
`public switched telephone network and/or wireless service
`provider networks) and an internet protocol (IP) network 124,
`such as the Internet. In one embodiment, DAS100 comprises
`part of a cellular telephone network and subscriber units 108
`are cellular telephones.
`0017 Downlink RF signals are received from the BTS 110
`at the host unit 102, which the host unit 102 uses to generate
`one or more downlink transport signals for transmitting to one
`or more of the remote units 106. Each such remote unit 106
`receives at least one downlink transport signal and recon
`structs the downlink RF signals from the downlink transport
`signal and causes the reconstructed downlink RF signals to be
`radiated from a remote antenna 107 coupled to or included in
`that remote unit 106. A similar process is performed in the
`uplink direction. Uplink RF signals received at one or more
`remote units 106 from subscriber 108 are used to generate
`respective uplink transport signals that are transmitted from
`the respective remote units 106 to the host unit 102. The host
`unit 102 receives and combines the uplink transport signals
`transmitted from the multiple remote units 106. The host unit
`102 communicates the combined uplink RF signals to the
`BTS 110 over a broadband medium.
`0018 DAS 100 comprises a digital DAS transport mean
`ing that the downlink and uplink transport signals transmitted
`between host unit 102 and remote units 106 over communi
`cation links 130 are generated by digitizing the downlink and
`uplink RF signals, respectively. In other words, the downlink
`and uplink transport signals are not analog RF signals but
`instead are digital data signals representing digital RF
`samples of a modulated RF signal. For example, if aparticular
`communication signal destined for transmission to Subscriber
`unit 108 is a modulated RF signal in the 900 MHz band, then
`host unit 102 will generate baseband digital samples of the
`modulated 900 MHz. RF signal from BTS 110, which are then
`distributed by host unit 102 to the remote units 106. Alterna
`tively, an all-digital BTS may generate baseband digital
`samples directly. At the remote units, the digital samples of
`the modulated RF signal are converted from digital into an
`analog RF signal to be wirelessly radiated from the antennas
`107. In the uplink analog RF signals received at remote unit
`106 are sampled to generate RF data samples for the uplink
`transport signals. BTS 110, host unit 102 and remote units
`106 each accommodate processing communication signals
`for multiple bands and multiple modulate schemes simulta
`neously. In addition to communicating the downlink and
`uplink transport RF signals, the digital transport between host
`unit 102 and each remote units 106 includes sufficient band
`width (that is, in excess of what is necessary to transport the
`digitized RF data samples) to implement an Ethernet pipe
`(100 Base-T) between each remote unit 106 and the host unit
`102 for facilitating supplemental Internet Protocol formatted
`data communications. In one embodiment, the Ethernet pipe
`provides a bandwidth of at least 100Mbits/sec.
`0019. It is understood in the art that RF signals are often
`transported at intermediate frequencies (IF) or baseband.
`Therefore, within the context of this application, the terms
`“digital RF, “digitized RF data”, “digital RF signal”, “digital
`
`RF samples”, “digitized RF samples' and “digitized RF sig
`nals' are understood to include signals converted to IF and
`baseband frequencies.
`0020 FIG. 2 is a block diagram of a remote unit 200 of one
`embodiment of the present invention Such as the remote units
`106 discussed with respect to FIG. 1. Remote unit 200
`includes a serial radio frequency (SeRF) module 220, a digital
`to analog radio frequency transceiver (DART) module 208, a
`remote DART interface board (RDI) 224, a linear power
`amplifier 210, antenna 212, a duplexer 211, a low noise
`amplifier 214 and an Internet Protocol device (IPD) 216. In
`one embodiment, SeRF modules and DART modules and
`Internet Protocol (IP) devices described herein are realized
`using discrete RF components, FPGAs, ASICs, digital signal
`processing (DSP) boards, or similar devices.
`(0021 DART module 208 provides bi-directional conver
`sion between analog RF signals and digital sampled RF for
`the downlink and uplink transport signals transmitted
`between host unit 102 and remote units 106. In the uplink,
`DART module 208 receives an incoming analog RF signal
`from subscriber unit 108 and samples the analog RF signal to
`generate a digital data signal for use by SeRF module 220.
`Antenna 212 receives the wireless RF signal from subscriber
`108 which passes the RF signal to DART module 208 via low
`noise amplifier 214. In the downlink direction DART module
`208 receives digital sampled RF data from SeRF module 220,
`up converts the sampled RF data to abroadcast frequency, and
`converts the digital RF samples to analog RF for wireless
`transmission. After a signal is converted to an analog RF
`signal by DART module 208, the analog RF signal is sent to
`linear power amplifier 210 for broadcast via antenna 212.
`Linear power amplifier 210 amplifies the RF signal received
`from DART module 208 for output through duplexer 211 to
`antenna 212. Duplexer 211 provides duplexing of the signal
`which is necessary to connect transmit and receive signals to
`a common antenna 212. In one embodiment, low noise ampli
`fier 214 is integrated into duplexer 211. One of ordinary skill
`in the art upon reading this specification would appreciate that
`DART modules may function to optionally convert the digital
`RF samples into intermediate frequency (IF) samples instead
`of or in addition to, baseband digital samples.
`0022 DART modules in a remote unit are specific for a
`particular frequency band. A single DART module operates
`over a defined band regardless of the modulation technology
`being used. Thus frequency band adjustments in a remote unit
`can be made by replacing a DART module covering one
`frequency band with a DART module covering a different
`frequency band. For example, in one implementation DART
`module 208 is designed to transmit 850 MHz cellular trans
`missions. As another example, in another implementation
`DART module 208 transmits 1900 MHz PCS signals. Some
`of the other options for a DART module 208 include, but are
`not limited to, Nextel 800 band, Nextel 900 band, PCS full
`band, PCS half band, BRS, WiMax, Long Term Evolution
`(LTE), and the European GSM 900, GSM 1800, and UMTS
`2100. By allowing different varieties of DART modules 208
`to be plugged into RDI 224, remote unit 200 is configurable to
`any of the above frequency bands and technologies as well as
`any new technologies or frequency bands that are developed.
`Also, a single remote unit may be configured to operate over
`multiple bands by possessing multiple DART modules. The
`present discussion applies to Such multiple band remote units,
`even though the present examples focuses on a the operation
`of a single DART module for simplicity.
`
`

`

`US 2010/0177759 A1
`
`Jul. 15, 2010
`
`0023 SeRF module 220 is coupled to RDI 224. RDI 224
`has a plurality of connectors each of which is configured to
`receive a pluggable DART module 208 and connect DART
`module 208 to SeRF module 220. RDI 224 is a common
`interface that is configured to allow communication between
`SeRF module 220 and different varieties of DART modules
`208. In this embodiment, RDI204 is a passive host backplane
`to which SeRF module 220 also connects. In another embodi
`ment, instead of being a hostbackplane, RDI224 is integrated
`with SeRF module 220. When a remote unit operates over
`multiple bands by possessing multiple DART modules, RDI
`224 provides separate connection interfaces allowing each
`DART module to communicate RF data samples with SeRF
`module 220. Although FIG. 2 illustrates a single SeRF mod
`ule connected to a single RDI, embodiments of the present
`invention are not limited to such. In alternate embodiments, a
`SeRF module may connect to multiple RDIs, each of which
`can connect to multiple DARTS. For example, in one embodi
`ment, a SeRF module can connect to up to 3 RDIs, each of
`which can connect to up to 2 DARTs. SeRF module 220
`provides bi-directional conversion between a serial stream of
`RF, IF or baseband data samples (a SeRF stream) and a high
`speed optical serial data stream. In the uplink direction, SeRF
`module 220 receives an incoming SeRF stream from DART
`modules 208 and sends a serial optical data stream over
`communication links 130 to host unit 102. In the downlink
`direction, SeRF module 220 receives an optical serial data
`stream from host unit 102 and provides a SeRF stream to
`DART modules 208.
`0024. Remote unit 200 further includes an internet proto
`col device (IPD) 216. IPD 216 is coupled to SeRF module 220
`via an interface 222 that provides bidirectional access to a
`point-to-point Ethernet pipe established between remote unit
`200 and the host unit 102 over the serial optical data stream.
`In one embodiment, interface 222 is a receptacle for a stan
`dard 8 Position 8 Contact (8P8C) modular plug and category
`5/5e cable.
`0025 IPD 216 may include any device designed to net
`work using an Ethernet connection. For example, IPD 216
`may comprise a networking devices Such a Switch, router,
`and/or wireless access point (for WiFi or WiMAX, for
`example). In another implementation, IPD 216 is a data col
`lection device Such as a weather station collecting weather
`related data Such as, but not limited to, temperature, relative
`humidity, wind speed and direction, precipitation, and the
`like. In still other implementations, IPD 216 may include any
`number of other data collection devices such as a Surveillance
`camera, a motion, heat or vibration sensor or a Subscriber unit
`locator. IPD 216 formats data it collects for transmission over
`an internet protocol (IP) connection and then outputs the data
`to the SeRF module 220 via interface 222 which in turn routes
`data over the Ethernet pipe to the host unit 102. In another
`implementation, IPD 216 is a data distribution device for
`distributing announcements, warnings or advertising. As
`such, IPD 216 may comprise a public announcement load
`speaker, sirens, or liquid crystal diode (LCD) display. Further
`IPD may support two way interactive messaging, chat, tele?
`Video conferencing applications, and the like.
`0026. Although FIG. 2 (discussed above) illustrates a
`single DART module coupled to a SeRF module, a single
`remote unit housing may operate over multiple bands and
`thus include multiple DART modules. In one such embodi
`ment, the systems illustrated in FIG. 2 would simply be rep
`licated once for each band. In one alternate embodiment, a
`
`SeRF module also allows multiple DART modules to operate
`in parallel to communicate high speed optical serial data
`streams over a communication link with the host unit. In one
`such embodiment a SeRF module actively multiplexes the
`signals from multiple DART modules (each DART module
`processing a different RF band) such that they are sent simul
`taneously over a single transport communication link. In one
`embodiment a SeRF module presents a clock signal to each
`DART module to which it is coupled to ensure synchroniza
`tion.
`0027 FIG. 3 is a block diagram illustrating a host unit
`(shown generally at 300) of one embodiment of the present
`invention such as the host unit 102 discussed with respect to
`FIG. 1. Multiple remote units 306 are coupled to host unit
`300, as described with respect to FIG. 1, to form a digital
`DAS. Host unit 300 includes a host unit digital to analog radio
`frequency transceiver (DART) module 308 and a host unit
`serial radio frequency (SeRF) module 320. SeRF module 320
`provides bi-directional conversion between a serial stream of
`RF data samples (a SeRF stream) and the multiple high speed
`optical serial data streams to and from the remote units 306.
`Each serial optical data stream includes a digital transport for
`communicating downlink and uplink transport RF signals as
`well as an Ethernet pipe between each remote unit 306 and
`host unit 300. In the uplink direction, SeRF module 320
`receives incoming serial optical data streams from a plurality
`of remote units and converts each into a serial stream of
`digitized baseband RF data samples, which are Summed into
`a broadband stream of RF data samples. DART module 308
`provides a bi-directional interface between SeRF module 320
`and one or more base stations, such as BTS 110. As with the
`remote units, when host unit 320 operates over multiple bands
`with multiple base stations, a separate DART module 308 is
`provided for each frequency band. In one embodiment, host
`unit 300 also maintains an Ethernet pipe with at least one base
`station (such as BTS 110) which provides access to at least
`one Internet gateway.
`(0028. Host unit 300 further includes an Ethernet port inter
`face 324 for coupling an Internet Protocol Device (IPD) 330
`to SeRF module 320 via an Ethernet link 325. Ethernet link
`325 may include a local area network (LAN), wide area
`network (WAN) having at least one network switch for rout
`ing data between interface 324 and IPD 330. Alternatively,
`IPD 330 may be an internet switch, router, or any of the IP
`devices discussed above with respect to IPD 216. Ethernet
`port interface 324 provides access to the Ethernet Pipes estab
`lished between host unit 300 and one or more of the multiple
`remote units 306. In one embodiment, a single 8 Position 8
`Contact (8P8C) modular plug Ethernet port interface 324
`provides access for communication via a virtual Ethernet
`connection with each multiple remote unit’s Ethernet port
`interface (Such as interface 222). In an alternate embodiment,
`Ethernet port interface 324 provides multiple 8 Position 8
`Contact (8P8C) modular plug connection points which each
`form a point-to-point virtual Ethernet connection with a spe
`cific one of the multiple remote units 306.
`(0029 Referring back to FIG. 2, it can be seen that for
`upstream communications, IP data received via interface 222
`and digitized RF data from DART module 208 are both
`pushed into SeRF 220 which produces the uplink transport
`signal that is communicated to the host unit 120 via commu
`nication links 130. In doing so, SeRF 220 performs multi
`plexing in the time domain to route both the IP data and the RF
`data into time slots within frames communicated to host unit
`
`

`

`US 2010/0177759 A1
`
`Jul. 15, 2010
`
`120. In downstream communications, SeRF 220 de-multi
`plexes IP data and RF data from within frames received from
`host unit 120. RF data is routed to the DART module 208
`while IP data is routed to Ethernet interface 222. In the host
`unit 300 illustrated in FIG.3, the host unit SeRF320 similarly
`multiplexes and de-multiplexes IP data and RF data (via
`communication links 130) to route IP data to and from inter
`face 324 and RF data to and from the host unit DART 308.
`0030 FIG. 4 illustrates one embodiment of a superframe
`400, which may be used for either upstream or downstream
`communications between remote units 106 and host unit 102
`via communication links 130. The particular superframe 400
`shown comprises 12 frames (shown at 420-1 to 420-12) with
`each frame divided into 16 timeslots (shown generally at
`410). One of ordinary skill in the art upon reading this speci
`fication would appreciate that this particular configuration of
`12 frames of 16 timeslots is for illustrative purposes only and
`that embodiments of the present invention may be practiced
`with superframes having different numbers of frames and
`timeslots.
`0031. In the particular embodiment shown in FIG. 4, each
`RF data sample carried over the digital transport of the DAS
`utilizes 15 of 16 available bits within a single timeslot (shown
`generally at 412, for example). In one embodiment, the SeRF
`module 220 multiplexes IP data into the remaining bits of
`each time slot. That is, for each timeslot carrying RF data,
`SeRF fills the 16" bit with IP data. The SeRF module assem
`bling superframe 400 thus utilizes the remaining overhead in
`each time slot to transport the IP data along with the RF data
`sample. In other embodiments, the ratio and/or number of bits
`used to carry an RF data sample verses the total number of
`available bits per timeslot may vary. For example, in an alter
`nate embodiment, an RF data sample may utilize 17 of 18
`available bits in a timeslot. The SeRF may then fill the 18" bit
`with IP data. In another alternate embodiment, an RF data
`sample may utilize 15 of 18 available bits in a timeslot. The
`SeRF may then fill one orall of the 16', 17", and/or 18" bits
`with IP data.
`0032. At the receiving end of the communication link, the
`SeRF module receiving superframe 400 accordingly sepa
`rates the IP data from each timeslot to reassemble standard IP
`data packets. It is not necessary that every timeslot of every
`frame will carry RF data. In other words, in some implemen
`tations, some timeslot of superframe 400 will not be utilized
`to carry RF data. This may occur where the bandwidth capac
`ity of a particular communication link exceeds the bandwidth
`demand of a particular remote unit. In those cases, the SeRF
`module assembling superframe 400 may alternately multi
`plex IP data onto otherwise unutilized timeslots of super
`frame 400.
`0033 FIG. 5 is a flow chart illustrating a method of one
`embodiment of the present invention. The method begins at
`510 with receiving data from an internet protocol device, the
`data formatted for transport via an internet protocol network
`(IP data) at a remote unit of a distributed antenna system. The
`method proceeds to 520 with converting analog RF signals
`received at the remote unit into digitized RF samples. The
`method proceeds to 530 with multiplexing the IP data with the
`digitized RF samples into frames for transmission to a host
`unit of the distributed antenna system. In one embodiment,
`multiplexing the IP data with the digitized RF samples into
`frames is achieved by inserting digitized RF samples into
`timeslots and then multiplexing the IP data into remaining
`bits within each time slot. For example, where each RF data
`
`sample is 15 bits and each timeslot has a capacity of 16 bits,
`the method utilizes 15 of 16 available bits within a timeslot to
`carry the RF data sample and multiplexes IP data into the
`remaining 16" bits of each timeslot. The method then pro
`ceeds to 540 with transmitting a superframe to the host unit,
`the Superframe comprising timeslots carrying the IP data with
`the digitized RF samples.
`0034 Several means are available to implement the sys
`tems and methods of the current invention as discussed in this
`specification. In addition to any means discussed above, these
`means include, but are not limited to, digital computer sys
`tems, microprocessors, programmable controllers, field pro
`grammable gate arrays (FPGAs) and application-specific
`integrated circuits (ASICs). Therefore other embodiments of
`the present invention are program instructions resident on
`computer readable media which when implemented by such
`controllers, enable the controllers to implement embodiments
`of the present invention. Computer readable media include
`devices Such as any physical form of computer memory,
`including but not limited to punch cards, magnetic disk or
`tape, any optical data storage system, flash read only memory
`(ROM), non-volatile ROM, programmable ROM (PROM),
`erasable-programmable ROM (E-PROM), random access
`memory (RAM), or any other form of permanent, semi-per
`manent, or temporary memory storage system or device. Pro
`gram instructions include, but are not limited to computer
`executable instructions executed by computer system
`processors and hardware description languages such as Very
`High Speed Integrated Circuit (VHSIC) Hardware Descrip
`tion Language (VHDL).
`0035 Although specific embodiments have been illus
`trated and described herein, it will be appreciated by those of
`ordinary skill in the art that any arrangement, which is calcu
`lated to achieve the same purpose, may be substituted for the
`specific embodiment shown. This application is intended to
`cover any adaptations or variations of the present invention.
`Therefore, it is manifestly intended that this invention be
`limited only by the claims and the equivalents thereof.
`
`We claim:
`1. A distributed antenna system, the system comprising:
`a host unit;
`at least one remote unit for wirelessly communicating with
`one or more Subscriber units, the at least one remote unit
`coupled to the host unit over a point-to-point communi
`cation link, wherein the at least one remote unit receives
`uplink radio frequency (RF) signals from the one or
`more Subscriber units and samples the uplink radio fre
`quency signals to generate digitized RF data, the at least
`one remote unit further comprising an Ethernet interface
`for receiving Internet Protocol (IP) formatted data; and
`an internet protocol device coupled to the Ethernet inter
`face;
`wherein the at least one remote unit outputs a serial data
`stream to the host unit, the serial data stream comprising
`a bandwidth having a first partition for transporting the
`digitized RF data to the host unit and a second partition
`implementing an Ethernet pipe for transporting the IP
`formatted data received via the Ethernet interface;
`wherein the serial data stream comprises a multiple
`timeslot communication frame, the first partition for
`transporting the digitized RF data to the host unit com
`prises a first partition of bits within a timeslot of the
`multiple-timeslot communication frame and the second
`
`

`

`US 2010/0177759 A1
`
`Jul. 15, 2010
`
`partition implementing an Ethernet pipe comprises a
`second partition of bits within the timeslot.
`2. The distributed antenna system of claim 1, wherein the at
`least one remote unit multiplexes the IP formatted data
`received via the Ethernet interface and the digitized RF data
`into timeslots of the serial data stream.
`3. The distributed antenna system of claim 1, the at least
`one remote unit further comprising
`at least one digital to analog radio frequency transceiver
`module for generating a digital radio frequency signal
`from an analog radio frequency signal received from the
`one or more subscriber units; and
`a serial radio frequency module coupled to receive the