RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 120 of U.S. Application No. 13/948,536 filed on July 23, 2013, the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND

[0002] The disclosure relates generally to distributed antenna systems (DASs) and more particularly to monitoring non-supported wireless spectrum, which may be used in connection with coverage areas of DASs.

[0003] DASs can be used for providing, extending and enhancing wireless communications and other services within a building or other installation. One approach to deploying a DAS involves the use of radio frequency (RF) antenna coverage areas, also referred to as "antenna coverage areas." The antenna coverage areas are provided by remote units in the DAS. Remote units can provide antenna coverage areas having radii in the range from a few meters up to twenty (20) meters. If the antenna coverage areas provided each cover a small area, there are typically only a few users (clients) per antenna coverage area. This minimizes the amount of RF bandwidth shared among the wireless system users. It may be desirable to provide antenna coverage areas in a building or other facility to provide indoor DAS access to clients within the facility. An optical fiber-based DAS can be used to distribute RF communications signals via Radio-over-Fiber (RoF) distribution.

[0004] Remote units in a DAS can be configured to distribute RF communications signals in multiple radio bands (i.e., frequencies or ranges of frequencies), as opposed to a single radio band. Distributing RF communications signals in multiple radio bands in an antenna coverage area increases flexibility of the DAS. In this scenario, client devices configured to communicate in different radio bands are supported in a given antenna coverage area provided by the remote unit.

[0005] The wireless spectrum within the antenna coverage areas often contain wireless signals from other sources and ambient electromagnetic (EM) signals, and in radio bands not supported by the DAS. These EM signals sometimes include supported frequencies used by DAS clients, as well as non-supported wireless frequencies. It may be desirable to detect and monitor non-supported environmental frequencies in the remote locations associated with the DAS remote units. In addition, some add-on equipment, such as a small-cell module physically located away from the remote unit, receives environmental frequency information as part of its initialization and configuration process, for example, to avoid interference with downlink or other channels of the small cell from environmental and other sources. Thus, it may also be desirable to detect and monitor non-supported wireless frequencies when adding or configuring additional equipment connected to the DAS.

[0006] No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.

SUMMARY

[0007] Embodiments of the disclosure relate to monitoring non-supported wireless spectrum within coverage areas of a distributed antenna system (DAS). Related devices and methods are also disclosed. Non-supported wireless spectrum refers to wireless frequencies that do not correspond to the one or more wireless services of the DAS, and may also be referred to as out-of-band spectrum. In one embodiment, a listening module connected to a remote unit of the DAS is configured to receive electromagnetic signals via an antenna. The listening module is configured to pass received non-supported wireless frequencies different from supported frequencies of the DAS to an output of the listening module. In some examples, one or more filters are configured to also pass the non-supported frequencies, and may be configured to pass one or more supported frequencies to the output as well. In other examples, the antenna is a broadband antenna configured to pass all frequencies to the output. In other examples, the filter(s) are configured to prevent some or all supported frequencies, i.e., frequencies corresponding to the one or more wireless services of the DAS, from being passed to the output.

[0008] In this manner, a monitoring module, such as a module connected to head-end equipment (HEE) of the DAS, can use an existing DAS infrastructure to monitor portions of the wireless spectrum outside the supported radio bands of the DAS at one or more remote locations, such as at one or more remote units of the DAS. In addition to avoiding the need to run parallel infrastructure to remotely monitor wireless spectrum throughout an installation, embodiments described herein are also useful in shared spectrum environments and other enviroments where efficient spectrum utilization is desired. The embodiments disclosed herein can provide increased network visibility, network intelligence, and cost savings when integrated into and existing DAS infrastructure.

[0009] One embodiment of the disclosure relates to an apparatus connected to one or more of a plurality of remote units of a DAS for monitoring non-supported wireless spectrum within a coverage area of the DAS. The apparatus includes at least one antenna configured to receive one or more electromagnetic (EM) signals and a listening module connected to the at least one antenna. The listening module comprises at least one input configured to receive the electromagnetic signals from the antenna and at least one output configured to transmit the EM signals over at least one uplink path of the DAS to head end equipment (HEE). The listening module further includes at least one listening path disposed between the at least one input and the at least one output and configured to pass at least one non-supported radio band different than the at least one supported radio band of the DAS to the at least one output.

[0010] An additional embodiment of the disclosure relates to a system for monitoring nonsupported wireless spectrum within a coverage area of a DAS having HEE and a plurality of remote units. The system comprises a plurality of antennas configured to receive one or more electromagnetic signals, a listening module connected to at least one of the remote units connected to at least one of the antennas, and a monitoring module connected to the HEE. The listening module includes at least one input configured to receive the electromagnetic signals from the antenna and at least one output configured to transmit the electromagnetic signals over at least one uplink path of the DAS. The listening module further includes at least one listening path disposed between the at least one input and the at least one output and configured to pass a non-supported radio band different than a supported radio band of the DAS to the at least one output. The monitoring module includes at least one input configured to receive the non supported radio band passed by the filter of the listening module.

[0011] An additional embodiment of the disclosure relates to a a method of monitoring non-supported wireless spectrum within a coverage area of a DAS. The method comprises receiving, at a plurality of antennas, one or more EM signals and receiving, at a listening module connected to at least one of a plurality of remote units of the DAS, the one or more EM signals from at least one of the antennas. The method further comprises passing the one or more electromagnetic signals in a non-supported radio band different than a supported radio band of the DAS to an output of the listening module.

[0012] Additional features and advantages will be set forth in the detailed description which follows. It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understand the nature and character of the claims.

[0013] The drawings are incorporated into and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIGS. 1A and IB are schematic views of an exemplary optical fiber-based distributed antenna system (DAS) according to the prior art;

[0015] FIG. 2 is a simplified schematic view of a DAS including an associated system for monitoring non-supported wireless spectrum within a coverage area of the DAS, according to an exemplary embodiment;

[0016] FIG. 3 is a detailed schematic view of a listening unit connected to a remote unit of a DAS having a listening module for monitoring non-supported wireless spectrum and an associated remote unit of the DAS of FIG. 2, according to an exemplary embodiment;

[0017] FIG. 4 is a flowchart diagram of an exemplary method of operation of the listening module connected to a remote unit of the DAS for monitoring non-supported wireless spectrum of FIG. 2, according to an exemplary embodiment;

[0018] FIG. 5 is a flowchart diagram of a method for operating a monitoring module of the DAS of FIG. 2, according to an alternative embodiment;

[0019] FIG. 6 is a general schematic view of an exemplary DAS building installation including the system for monitoring non-supported wireless spectrum of FIG. 2, according to an exemplary embodiment;

[0020] FIG. 7 is a general schematic view of an exemplary DAS configured to distribute digital and/or analog signals within a coverage area of the DAS, and which also includes an associated system for monitoring non-supported wireless spectrum in coverage areas of the DAS according to an exemplary embodiment; and

[0021] FIG. 8 is a schematic diagram view of a generalized representation of an exemplary computer system that can be included in or interface with any of the systems for monitoring non-supported wireless spectrum within coverage areas of a DAS.

DETAILED DESCRIPTION

[0022] Embodiments of the disclosure relate to monitoring non-supported wireless spectrum within coverage areas of a distributed antenna system (DAS). In one embodiment, a listening module connected to a remote unit of the DAS is configured to pass received nonsupported wireless frequencies different from supported frequencies of the DAS to an output of the listening module. In the manner, a centrally located monitoring module can use an existing DAS infrastructure to monitor portions of the wireless spectrum outside the supported radio bands of the DAS at one or more remote locations. Various embodiments will be further clarified by the following examples.

[0023] Before discussing monitoring non-supported wireless spectrum in connection with coverage areas of DASs starting at FIG. 2, FIGS. 1A and IB are examples of DASs that do not include support for monitoring non-supported wireless spectrum, but that can be configured to provide support for monitoring non-supported wireless spectrum in connection with coverage areas of a DAS, including according to the embodiments described herein.

[0024] FIG. 1A is a schematic diagram of an embodiment of a DAS. In this embodiment, the system is an optical fiber-based DAS 10. The optical-fiber based DAS 10 is configured to create one or more antenna coverage areas for establishing communications with wireless client devices located in the radio frequency (RF) range of the antenna coverage areas. The DAS 10 provides RF communications services (e.g., cellular services). In this embodiment, the DAS 10 includes HEE in the form of a HEU 12, one or more remote units 14, and an optical fiber 16 that optically couples the HEU 12 to the remote unit 14. The HEU 12 is configured to receive communications over downlink electrical RF communications signals 18D from a source or sources, such as a network or carrier as examples, and provide such communications to the remote unit 14. The HEU 12 is also configured to return communications received from the remote unit 14, via uplink electrical RF communications signals 18U, back to the source or sources. The optical fiber 16 includes at least one downlink optical fiber 16D to carry signals communicated from the HEU 12 to the remote unit 14 and at least one uplink optical fiber 16U to carry signals communicated from the remote unit 14 back to the HEU 12. One downlink optical fiber 16D and one uplink optical fiber 16U could be provided to support multiple channels, each using wavelength-division multiplexing (WDM), as discussed in U.S. Patent Application No. 12/892,424, entitled "Providing Digital Data Services in Optical Fiber-based Distributed Radio Frequency (RF) Communications Systems, And Related Components and Methods," incorporated herein by reference in its entirety. Other options for WDM and frequency-division multiplexing (FDM) are also disclosed in U.S. Patent Application No. 13/688,448, any of which can be employed in any of the embodiments disclosed herein. [0025] The DAS 10 has an antenna coverage area 20 that can be substantially centered about the remote unit 14. The remote unit 14 is configured to receive downlink optical RF communications signals 22D from the HEU 12 and transmit the content downlink optical RF communications signals 22D wirelessly within the coverage area 20. The HEU 12 is adapted to perform or to facilitate any one of a number of wireless applications, including but not limited to Radio-over-Fiber (RoF), radio frequency identification (RFID), wireless local-area network (WLAN) communication, public safety, cellular, telemetry, and other mobile or fixed services. Shown within the antenna coverage area 20 is a client device 24 in the form of a mobile device as an example, which may be a cellular telephone as an example. The client device 24 can be any device that is capable of receiving RF communication signals. The client device 24 includes an antenna 26 (e.g., a wireless card) adapted to receive and/or send electromagnetic RF communications signals. In a particular exemplary embodiment, this includes providing WLAN signal distribution as specified in the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, i.e., in the frequency range from 2.4 to 2.5 GigaHertz (GHz) and from 5.0 to 6.0 GHz. Any other electrical RF communications signal frequencies are possible.

[0026] With continuing reference to FIG. 1A, to communicate the electrical RF communications signals over the downlink optical fiber 16D to the remote unit 14, to in turn be communicated to the client device 24 in the antenna coverage area 20 formed by the remote unit 14, the HEU 12 includes an electrical-to-optical (E/O) converter 28. The E/O converter 28 converts the downlink electrical RF communications signals 18D to downlink optical RF communications signals 22D to be communicated over the downlink optical fiber 16D. The remote unit 14 includes an optical-to-electrical (O/E) converter 30 to convert received downlink optical RF communications signals 22D back to electrical RF communications signals to be communicated wirelessly through an antenna 32 of the remote unit 14 to client devices 24 located in the antenna coverage area 20.

[0027] Similarly, the antenna 32 is also configured to receive wireless RF communications from client devices 24 in the antenna coverage area 20. In this regard, the antenna 32 receives wireless RF communications from client devices 24 and communicates electrical RF communications signals representing the wireless RF communications to an E/O converter 34 in the remote unit 14. The E/O converter 34 converts the electrical RF communications signals into uplink optical RF communications signals 22U to be communicated over the uplink optical fiber 16U. The E/O converter 34 and the O/E converter 30 constitute a "converter pair," as illustrated in FIG. 1A. In an exemplary embodiment, the E/O converter 28 includes a laser suitable for delivering sufficient dynamic range for the RoF applications described herein, and optionally includes a laser driver/amplifier electrically coupled to the laser. Examples of suitable lasers for the E/O converter 28 include, but are not limited to, laser diodes, distributed feedback (DFB) lasers, Fabry-Perot (FP) lasers, and vertical cavity surface emitting lasers (VCSELs).

[0028] An O/E converter 36 provided in the HEU 12 converts the uplink optical RF communications signals 22U into uplink electrical RF communications signals, which can then be communicated as uplink electrical RF communications signals 18U back to a network or other source. In an exemplary embodiment, the O/E converter 36 is a photodetector, or a photodetector electrically coupled to a linear amplifier. The E/O converter 28 and the O/E converter 36 also constitute a "converter pair," as illustrated in FIG. 1 A. The HEU 12 in this embodiment is only configured to receive supported uplink RF communications signals, i.e., uplink RF communications signals in supported radio bands. As used herein, the terms "supported wireless spectrum," "supported wireless frequency(s)," and/or "supported radio band(s)" refer to a frequency or group of frequencies corresponding to one or more active wireless services of a DAS, for example, a radio band used by a cellular communications provider. The terms "non-supported wireless spectrum," "non-supported wireless frequency(s)," and/or "non-supported radio band(s)" conversely refer to a frequency or group of frequencies that do not correspond to the one or more active wireless services of the DAS.

[0029] FIG. IB provides further exemplary illustration of how an optical fiber-based DAS 10 can be deployed indoors. FIG. IB is a partially schematic cut-away diagram of a building infrastructure 38 employing an optical fiber-based DAS. The system may be the optical fiber-based DAS 10 of FIG. 1A. The building infrastructure 38 generally represents any type of building in which the optical fiber-based DAS 10 can be deployed. As previously discussed with regard to FIG. 1A, the optical fiber-based DAS 10 incorporates the HEU 12 to provide various types of communication services to coverage areas within the building infrastructure 38, as an example. For example, as discussed in more detail below, the optical fiber-based DAS 10 in this embodiment is configured to receive wireless RF communications signals and convert the RF communications signals into RoF signals to be communicated over the optical fiber 16 to multiple remote units 14. The optical fiber-based DAS 10 in this embodiment can be, for example, an indoor distributed antenna system (IDAS) to provide wireless service inside the building infrastructure 38. These wireless signals can include, but are not limited to, cellular service, wireless services such as RFID tracking, Wireless Fidelity (WiFi), local area network (LAN), WLAN, and combinations thereof, as examples.

[0030] However, the DAS 10 of FIGS. 1A and IB only transmits frequencies corresponding to the uplink optical RF communications signals 22U back to the HEU 12. Thus, the DAS 10 of FIGS. 1A-1B has no spectrum monitoring capability for non-supported wireless frequencies, such as frequencies associated with third party and/or potential add-on services, as well as potential interference sources. In addition, these non-supported wireless frequencies may be present in different amounts throughout the building infrastructure 38. For example, a third party wireless service may have strong coverage at the perimeter of the building infrastructure 38 but may have little or no coverage in the interior of the building infrastructure 38. Likewise, wireless interference may vary at different locations throughout the building infrastructure 38. Thus, it may therefore be advantageous to use existing installed infrastructure of a DAS, such as DAS 10, to monitor non-supported wireless spectrum from a central location, such as a HEU 12 of DAS 10, to more effectively monitor a building infrastructure or other environment.

[0031] With continuing reference to FIG. IB, the building infrastructure 38 in this embodiment includes a first (ground) floor 40, a second floor 42, and a third floor 44. The floors 40, 42, 44 are serviced by the HEU 12 through a main distribution frame 46 to provide antenna coverage areas 48 in the building infrastructure 38. Only the ceilings of the floors 40, 42, 44 are shown in FIG. IB for simplicity of illustration. In the exemplary embodiment, a main cable 50 has a number of different sections that facilitate the placement of a large number of remote units 14 in the building infrastructure 38. Each remote unit 14 in turn services its own coverage area in the antenna coverage areas 48. The main cable 50 can include, for example, a riser cable 52 that carries all of the downlink and uplink optical fibers 16D, 16U to and from the HEU 12. The riser cable 52 may be routed through an interconnect unit (ICU) 54 to one or more optical fiber cables 56. The ICU 54 may also be configured to provide power to the remote units 14 via an electrical power line provided inside an array cable 58, or tail cable or home-run tether cable as other examples, and distributed with the downlink and uplink optical fibers 16D, 16U to the remote units 14. The main cable 50 can include one or more multi-cable (MC) connectors adapted to connect select downlink and uplink optical fibers 16D, 16U, along with an electrical power line, to a number of optical fiber cables 56.

[0032] The main cable 50 enables the multiple optical fiber cables 56 to be distributed throughout the building infrastructure 38 (e.g., fixed to the ceilings or other support surfaces of each floor 40, 42, 44) to provide the antenna coverage areas 48 for the first, second and third floors 40, 42 and 44. In an exemplary embodiment, the HEU 12 is located within the building infrastructure 38 (e.g., in a closet or control room), while in another exemplary embodiment, the HEU 12 may be located outside of the building infrastructure 38 at a remote location. A base transceiver station (BTS) 60, which may be provided by a second party such as a cellular service provider, is connected to the HEU 12, and can be co-located or located remotely from the HEU 12. A BTS is any station or source that provides an input signal to the HEU 12 and can receive a return signal from the HEU 12. In a typical cellular system, for example, a plurality of BTSs are deployed at a plurality of remote locations to provide wireless telephone coverage. Each BTS serves a corresponding cell and when a mobile station enters the cell, the BTS communicates with the mobile station. Each BTS can include at least one radio transceiver for enabling communication with one or more subscriber units operating within the associated cell. Alternatively, radio input could be provided by a repeater or picocell as other examples.

[0033] The optical fiber-based DAS 10 in FIGS. 1A and IB described above provides point-to-point communications between the HEU 12 and the remote units 14. Each remote unit 14 communicates with the HEU 12 over a distinct downlink and uplink optical fiber pair 16D/16U to provide the point-to-point communications. Whenever a remote unit 14 is installed in the optical fiber-based DAS 10, the remote unit 14 is connected to a distinct downlink and uplink optical fiber pair connected to the HEU 12. The downlink and uplink optical fibers 16D/16U may be provided in the optical fiber 16. Multiple downlink and uplink optical fiber pairs 16D/16U can be provided in a fiber optic cable to service multiple remote units 14 from a common fiber optic cable. For example, with reference to FIG. IB, remote units 14 installed on a given floor 40, 42, or 44 may be serviced from the same optical fiber 16, which may have multiple nodes where distinct downlink and uplink optical fiber pairs 16D/16U are connected to a given remote unit 14.

[0034] It may be desirable to provide an optical fiber-based DAS that can support a wide variety of radio sources. For example, it may be desired to provide an optical fiber-based DAS that can support various radio types and sources, including but not limited to Long Term Evolution (LTE), US Cellular (CELL), Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Advanced Wireless Services (AWS), iDEN (e.g., 800 MegaHertz (MHz), 900 MHz, and 1.5 GHz), etc. These radios sources can range from 400 MHz to 2700 MHz as an example. To support a radio source, the HEU must contain lasers that are capable of modulating the radio signal into optical RF communications signals at the frequency of the radio signal for transmission over optical fiber. Likewise, lasers must be provided to convert the optical RF communications signals back into electrical RF communications signals at the frequencies of the radio band supported. It is costly to provide different conversion lasers for all possible radio sources that may be desired to be supported by an optical fiber-based DAS.

[0035] As noted above, the DAS 10 of FIGS. 1A and IB has no spectrum monitoring capability for non-supported wireless frequencies. Thus, it may be advantageous to use existing installed infrastructure of a DAS, such as DAS 10, to monitor non-supported wireless spectrum from a central location, such as a HEU 12 of DAS 10, to more effectively monitor a building infrastructure 38 or other environment.

[0036] FIG. 2 is a schematic diagram of such a DAS 64 that can support monitoring nonsupported wireless spectrum within a coverage area of the DAS 64. The DAS 64 includes a HEU 12, a plurality of remote units 14, a monitoring unit 86 connected to HEU 12, at least one listening unit 74 connected to one or more remote units 14. Each listening unit 74 includes a listening module 76 having a listening path that may include one or more filters (described in detail below with respect to FIG. 3) configured to pass received non-supported wireless frequencies different from supported frequencies of the DAS 64 to an output of the listening module. The non-supported frequencies are then transmitted to the HEU 12 via the DAS 64 infrastructure and routed to the monitoring unit 86. The monitoring unit 86 includes a monitoring module 88 that receives and processes the non-supported wireless frequencies via one or more inputs, thereby monitoring portions of the wireless spectrum outside the supported radio bands of the DAS 64 at one or more remote locations, such as at one or more remote units 14 of the DAS 64.

[0037] The DAS 64 will now be described in detail to illustrate how the monitoring unit 86 and listening unit(s) 74 are able to use the infrastructure of the DAS 64 to monitor nonsupported wireless frequencies. In this embodiment, the DAS 64 is an optical fiber-based DAS comprised of three main components. One or more radio interfaces provided in the form of radio interface modules (RIMs) 66(1)-66(M) in this embodiment are provided in HEU 12 to receive and process downlink electrical RF communications signals 18D(1)- 18D(R) prior to optical conversion into downlink optical RF communications signals 22D(1)- 22D(R). The processing of the downlink electrical RF communications signals 18D(1)- 18D(R) can include any of the processes previously described above in the HEU 12 in FIG. 2. The notations "1-R" and "1-M" indicate that any number of the referenced component, 1- R and 1-M, respectively, may be provided. As will be described in more detail below, the HEU 12 in this embodiment is configured to accept a plurality of RIMs 66(1)-66(M) as modular components that can be easily installed and removed or replaced in the HEU 12. In one embodiment, the HEU 12 is configured to support up to four (4) RIMs 66(1)-66(M).

[0038] Each RIM 66(1)-66(M) can be designed to support a particular type of radio source or range of radio sources (i.e., frequencies) to provide flexibility in configuring the HEU 12 and optical fiber-based DAS 64 to support the desired radio sources. For example, one RIM 66 may be configured to support the Personal Communication Services (PCS) radio band. Another RIM 66 may be configured to support the Long Term Evolution (LTE) 700 MHz radio band. In this example, by inclusion of these RIMs 66, the HEU 12 would be configured to support and distribute RF communications signals on both PCS and LTE 700 MHz radio bands. RIMs 66 may be provided in the HEU 12 that support any other radio bands and technologies desired, including but not limited to PCS, LTE, CELL, GSM, CDMA, CDMA2000, TDMA, AWS, iDEN (e.g., 800 MHz, 900 MHz, and 1.5 GHz), Enhanced Data GSM Environment, (EDGE), Evolution-Data Optimized (EV-DO), lxRTT (i.e., CDMA2000 IX (IS-2000)), High Speed Packet Access (HSPA), 3GGP1, 3GGP2, and Cellular Digital Packet Data (CDPD). More specific examples include, but are not limited to, radio bands between 400-2700 MHz including but not limited to 700 MHz (LTE), 698-716 MHz, 728- 757 MHz, 776-787 MHz, 806-824 MHz, 824-849 MHz (US Cellular), 851-869 MHz, 869- 894 MHz (US Cellular), 880-915 MHz (EU R), 925-960 MHz (TTE), 1930-1990 MHz (US PCS), 2110-2155 MHz (US AWS), 925-960 MHz (GSM 900), 1710-1755 MHz, 1850-1915 MHz, 1805-1880 MHz (GSM 1800), 1920-1995 MHz, and 2110-2170 MHz (GSM 2100).

[0039] The downlink electrical RF communications signals 18D(1)-18D(R) are provided to an optical interface unit (OIU) 68 having a plurality of optical interfaces provided in the form of optical interface modules (OIMs) 70(1)-70(N) in this embodiment to convert the downlink electrical RF communications signals 18D(1)-18D(N) into downlink optical RF communications signals 22D(1)-22D(R). The notation "1-N" indicates that any number of the referenced component 1-N may be provided. One downlink optical fiber 16D and one uplink optical fiber 16U could be provided to support multiple channels each using WDM or FDM.

[0040] In this embodiment, the OIMs 70(1)-70(N) are provided in a common housing provided for the HEU 12 with the RIMs 66(1)-66(M). Alternatively, the OIMs 70(1)-70(N) could be located in separately from the RIMs 66(1)-66(M). The OIMs 70 may be configured to provide one or more optical interface components (OICs) that contain O/E and E/O converters, as will be described in more detail below. The OIMs 70 support the radio bands that can be provided by the RIMs 66, including the examples previously described above. Thus, in this embodiment, the OIMs 70 may support a radio band range from 400 MHz to 2700 MHz, as an example, so providing different types or models of OIMs 70 for narrower radio bands to support possibilities for different radio band supported RIMs 66 provided in the HEU 12 is not required. Further, as an example, the OIMs 70 may be optimized for sub- bands within the 400 MHz to 2700 MHz frequency range, such as 400 - 700 MHz, 700 MHz - 1 GHz, 1 GHz - 1.6 GHz, and 1.6 GHz - 2.7 GHz, as examples.

[0041] The OIMs 70(1)-70(N) each include E/O converters to convert the downlink electrical RF communications signals 18D(1)-18D(R) to downlink optical RF communications signals 22D(1)-22D(R). The downlink optical RF communications signals 22D(1)-22D(R) are communicated over downlink optical fiber(s) 16D to a plurality of remote units 14(1)-14(P). The notation "1-P" indicates that any number of the referenced component 1-P may be provided. O-E converters provided in the remote units 14(1)-14(P) convert the downlink optical RF communications signals 22D(1)-22D(R) back into downlink electrical RF communications signals 18D(1)-18D(R), which are provided over links 72(1)-72(P) coupled to antennas 32(1)-32(P) in the remote units 14(1)-14(P) to client devices in the reception range of the antennas 32(1)-32(P).

[0042] In this embodiment, the listening unit 74 includes a listening module 76 having a link 78 to a dedicated antenna 80. The listening unit 74 in this example is part of a remote expansion unit (RXU) 81 that is a separate unit from the remote unit 14. In other embodiments, the listening unit 74 may be a separate unit from both the remote unit 14 and RXU 81. In another example, the listening module 76 may be an integrated component or a plug-in component of the remote unit 14. The antenna 80 may be a broadband or a narrowband antenna and is capable of receiving one or more non-supported wireless frequencies. The listening unit 74 is connected to the remote unit(s) 14 by a link 82 that transmits a monitor signal 84 containing the non-supported wireless frequencies to the remote unit(s) 14 where they can be combined with one or more of the uplink optical RF communications signals 22U for transmission back to the HEU 12. The monitoring module 88 of the monitoring unit 86 can then receive the monitor signal 84 from a link 90 from the RIM(s) 66 and/or a link 92 from the OIU 68. The monitoring unit 86 in this example is a separate unit from the HEU 12, and may be part of another device or component connected to the HEU 12. In another example, the monitoring module 88 may be an integrated component or a plug-in component of the HEU 12. In this embodiment, the link 90 to the RIM(s) 66 is configured to transmit narrowband signals corresponding to wireless frequencies near the supported radio band of the RIM(s) 66. Conversely, the link 92 to the OIU 68 in this embodiment is configured to transmit broadband signals corresponding to a large range of non-supported wireless frequencies and can also be used for narrow band monitoring, similar to link 90, as well. It should be understood that alternative methods of routing, such employing an RF matrix for routing signals between multiple links to a single monitoring unit, are contemplated as well.

[0043] In this embodiment, the listening module 76 can also be connected via a link 94 to one or more of the antennas 32(1)-32(P) connected to the remote units 14(1)-14(P). As will be discussed in detail below with respect to FIG. 3, the listening module can include different modes that employ one or more of the different antennas 32, 80. These and other functions can be controlled via a control link 96. In this embodiment, a control signal, received at the HEU 12 via another control link 97, is embedded within one or more downlink optical RF communications signals 22D and delivered to the listening module 76 from the remote unit(s) 14 via the control link 96. In other embodiments, a separate control signal may be employed.

[0044] In some embodiments, the above described components may have a wide range of capabilities. For example, the listening module 76 may be capable of providing spectrum monitoring over a wide range of RF frequencies, e.g., 10 MHz - 6 GHz. In another example, the listening module 76 and/or monitoring module 88 may be self-optimized and/or self configurable, thereby permitting advanced integration and interoperability with small cells and other radio sources that may be connected to a DAS.

[0045] To illustrate the functionality and operation of the listening module 76, the internal components of the listening unit 74 and an exemplary remote unit 14 will be described. In this regard, FIG. 3 illustrates a detailed schematic view of the listening unit 74 and associated remote unit 14 of the DAS 64 of FIG. 2. In this embodiment, the remote unit 14 includes a broadband antenna 32 connected to a multiplexer/demultiplexer 98 which sends the received signal to one or more uplink frequency band paths 99. In this embodiment, the remote unit 14 includes two uplink frequency band paths 99(l)-99(2), but more or fewer uplink frequency band paths 99 are possible as well. As will be described in greater detail below, each uplink frequency band path 99 filters and passes a predetermined supported upload frequency band to a frequency mux/combiner 100, which combines the outputs of the uplink frequency band paths 99 into a combined signal and outputs one or more uplink electrical RF communications signals 18U. E/O converter 34(1) converts the uplink electrical RF communications signal 18U to an optical signal for transmission to the HEU 12 (not shown).

[0046] Meanwhile, the listening module 76 of the listening unit 74 forms a spectrum monitoring path for monitoring non-supported wireless frequencies. As discussed above, the listening module 76 receives EM radiation via the antenna 80 (or, alternatively, via a broadband antenna 32) and outputs the monitor signal 84 into an E/O converter 34(2), which converts the monitor signal 84 into an optical signal. The outputs of both E/O converters 34(1) and 34(2) are received by a wave division multiplexer 102, and are multiplexed into one or more uplink optical RF communications signals 22U.

[0047] In this manner, the monitor signal 84 may be carried over the existing infrastructure of a DAS, such as DAS 64, and delivered to a centrally located monitoring module, such as monitoring module 88. One advantage of this arrangement is that a number of third party and other non-supported wireless components, such as small-cell or femtocell components (not shown), can be installed in a central location, such as in proximity to HEU 12. Some of these components employ a listening mode to gather information about the transmission environment as part of their initialization and configuration process. Therefore, this arrangement permits these components to receive accurate information about the transmission environment, i.e., the remote unit 14 locations, while remaining physically located proximate to the HEU 12. As discussed above, in addition to avoiding the need to run parallel infrastructure to remotely monitor wireless spectrum throughout an installation, embodiments described herein are also useful in shared spectrum environments and other environments where efficient spectrum utilization is desired.

[0048] The internal components of the uplink frequency band paths 99(1) and 99(2) of the remote unit 14 and the spectrum monitoring path of the listening module 76 are analogous to each other in many respects. In this example, each uplink frequency band path 99 includes a limiter/detector 104 that receives a signal output from multiplexer 98. A parallel low noise amplifier 106 and filter 108 next pass the signal through a variable gain amplifier 110 and into filter 112. Each filter 112 is tuned to pass a specific supported frequency band through the variable attenuator 118 to gain amplifier 120 and outputs the signal to frequency mux/combiner 100, thereby preventing non-supported frequencies from being passed to the output of the uplink frequency band path 99.

[0049] In a similar arrangement, the spectrum monitoring path, also referred to as a listening path, of the listening module 76 includes a limiter/detector 122 that receives a signal from one of antenna 80 or antenna 32. In this example, a selectable low noise amplifier 124 and optional attenuator 126 next pass the signal through a variable gain amplifier 128 and into a selectable filter 130 and/or mixer 132. The mixer 132 permits selective tuning of the passed frequencies, while the filter 130 permits passing a fixed frequency or frequencies. The filter 130 and mixer 132 can also be bypassed entirely, thereby passing the entire range of frequencies received by antenna 80 and/or antenna 32. The passed wireless frequencies are next passed through the variable attenuator 134 to gain amplifier 136 and analog/digital converter 138, finally outputting the signal to E/O converter 34(2), likewise preventing non- tuned wireless frequencies, which may include both supported and non-supported radio bands, from being passed to the output of the uplink frequency band path. In an alternative embodiment, the mixer 132 and other components permitting selectable tuning can be omitted, such that the spectrum monitoring path is tuned to a fixed frequency band. It should also be understood that the wave division multiplexer 102 and analog/digital converter 138 are also optional and are not required for a DAS that does not include digital signal distribution. In an alternative, analog-only embodiment, for example, the output signal from gain amplifier 136 can be combined directly with the output of mux/combiner 100 and output to a single E/O converter 34(1).

[0050] In this example, the listening module has a number of different antenna modes. In a disabled mode, an antenna switch 144 is set to fifty ohm (50Ω) termination (or terminated) mode 146, thereby turning off the listening module 76. In first broadband listening mode, the switch 144 connects the listening module 76 to antenna 80, thereby permitting reception of all frequencies capable of being received by antenna 80. In a second listening mode, the switch 144 connects the listening module 76 to one or more of the broadband antennas 32 of the remote unit(s) 14, thereby permitting reception of all frequencies capable of being received by broadband antenna(s) 32, for example, by bypassing the filter 130 and or mixer 132, or by omitting the filter 130 and mixer 132 entirely.

[0051] These components allow for configurable spectrum bandwidth support and signal level sensitivity. For example, the listening module 76 of FIG. 3 may be configured for broad band spectrum monitoring (e.g., 10 MHz-6 GHz, etc.), narrow band spectrum monitoring (e.g., 450 MHz, 700 MHz, 850 MHz, 1900 MHz, etc.), or a combination of the two. Likewise, the listening module of FIG. 4 may also be configured to operate in a high level sensitivity mode employing amplification to optimize for monitoring weak signals, a low level sensitivity mode employing attenuation to optimize for monitoring strong signals, or a mixed mode employing a combination of the two. The various functions of the listening module may be controlled manually, automatically or remotely, for example via one or more control links 96 connected to the remote units 14. In the same manner, referring back to FIG. 2, the RIM(s) 66 and/or OIU 68 can also include complementary components (not shown) for demuxing, demultiplexing, or otherwise extracting the monitor signal 84 from the uplink optical RF communications signal 22U.

[0052] An exemplary method of operation of the listening module 76 of FIGS. 2 and 3 are now described. In this regard, FIG. 4 is a flowchart of an exemplary method 150 of monitoring non-supported wireless spectrum within a coverage area of a DAS. The method 150 includes receiving, at an antenna, one or more EM signals (block 152). For example, receiving EM signals could be performed by the antenna 80 of FIG. 3. The method 150 further includes receiving, at a listening module, such as listening module 76, the one or more EM signals from the antenna (block 154). The method 150 further comprises filtering the one or more EM signals (block 156) to pass a non-supported radio band different than a supported radio band of the DAS to an output of the listening module. In one example, the filtering could be performed by filter 130 of FIG. 3.

[0053] FIG. 5 is a flowchart of an exemplary method 158 of operating a monitoring module according to another embodiment. The method 158 includes directing, at a monitoring module, such as monitoring module 88 of FIG. 2, a listening module, such as the listening module 76, to receive EM signals corresponding to a non-supported radio band different than a supported radio band of the DAS (block 160). The method 158 further includes receiving the EM signals corresponding to the non-supported radio bands at the monitoring module via the infrastructure of a DAS, such as DAS 64 (block 162). In one example, the infrastructure of the DAS that delivers the EM signals may be one or more OIM 70 or RIM 66 of the DAS 64 of FIG. 2. The method 158 further includes processing, interpreting or otherwise utilizing the EM signals corresponding to the non-supported radio bands by the monitoring module (block 164).

[0054] In this manner, the above described methods can monitor non-supported wireless spectrum throughout an installation, such as the building infrastructure 38 of FIG. IB, using the installed DAS infrastructure. In this regard, FIG. 6 illustrates the building infrastructure 38 of FIG. IB having the DAS 64 and additional associated spectrum monitoring components of FIGS. 2 and 3. In this example, monitoring unit 86 is connected to HEU 12, and a number of remote units 14 on different floors and in different locations are connected to respective listening units 74. In this manner, the monitoring unit 86 is able to monitor nonsupported wireless spectrum in a variety of different locations within a building infrastructure 38 using the existing infrastructure of the DAS 64.

[0055] As discussed above, the embodiments of FIGS. 2, 3, and 6 relate to spectrum monitoring using an RF-based DAS 64. However, spectrum monitoring in accordance with the present disclosure may be employed using DASs that include digital signal distribution as well. In this regard, FIG. 7 is a schematic diagram of an alternative DAS 166 that includes the a DAS 64' similar to DAS 64 in FIG. 3 in combination with a wireless local access network (WLAN) system 168 for providing digital data services. In this regard, the DAS 166 includes the HEU 12 previously described above with regard to FIG. 2.

[0056] The HEU 12 is configured to receive the downlink electrical RF communications signals 18D through downlink interfaces 170 from one or more base stations 172(1)-172(N), wherein N can be any number. The HEU 12 can be configured receive RF communications services from multiple base stations 172(1 )-172(N) to support multiple RF radio bands in the DAS 166. The HEU 12 is also configured to provide the downlink optical RF communication signals 22D to the remote units 14(1)-14(N) and receive the uplink optical RF communications signals 22U from remote units 14(1)-14(N) over a communications medium. M number of remote units 14 signifies that any number, M number, of remote units 14 could be communicatively coupled to the HEU 12, as desired. Similar to the embodiments of FIGS. 2, 3, and 6, the DAS 166 also includes additional associated spectrum monitoring components described in detail with respect to FIGS. 2 and 3. In this example, monitoring unit 86 is connected to HEU 12, and a number of remote units 14 are connected to respective listening units 74. In this manner, the monitoring unit 86 is able to monitor nonsupported wireless spectrum in a variety of different locations using the existing infrastructure of the DAS 64.

[0057] With continuing reference to FIG. 7, a digital data switch 174 may also be provided in the WLAN system 168. The digital data switch 174 may be provided in the WLAN system 176 for providing digital data signals, such as for WLAN services for example, to remote units 176(1)-176(P) configured to support digital data services, wherein P signifies that any number of the remote units 176 may be provided and supported by the WLAN system 168. Similar to the remote units 14 above, a number of remote units 176 in this embodiment are also connected to respective listening units 74. In this manner, the monitoring unit 86 is able to monitor non-supported wireless spectrum at the locations of digitally based remote units 176 as well.

[0058] The digital data switch 174 may be coupled to a network 178, such as the Internet. Downlink digital data signals 180D from the network 178 can be provided to the digital data switch 174. The downlink digital data signals 180D can then be provided to the remote units 176(1)-176(P) through slave central units 182(1)-182(Q), wherein Q can be any number desired. The digital data switch 174 can also receive uplink digital data signals 180U from the remote units 176(1)-176(P) to be provided back to the network 178. The slave central units 182(1)-182(Q) also receive the downlink optical RF communications signals 22D and provide uplink optical RF communications signals 22U from the remote units 176(1)-176(P) to the HEU 12 in this embodiment. In this regard, the remote units 176(1)-176(P), by being communicatively coupled to a slave central unit 182(1) that supports both the RF communications services and the digital data services, is included in both the distributed antenna system 64' and the WLAN system 168 to support RF communication services and digital data services, respectively, with client devices 184(1)-184(P). For example, such remote unit 176 may be configured to communicate wirelessly with the WLAN user equipment (e.g., a laptop) and Wide Area Wireless service user equipment (e.g., a cellular phone).

[0059] A number of different digital data devices may also be included, such as WLAN access points, femtocells, gateways, baseband units (BBU), remote radio heads (RRH), and wired and wireless servers. Digital data services may also be provided via connected desktop computers, hubs, switches, and other devices. Any of these digital data devices may include hardware and/or software for remotely monitoring non-supported spectrum via the DAS.

[0060] In addition, any of the DASs and other components disclosed herein, including the monitoring unit 86, monitoring module 88, listening unit 74, and/or listening module 76 of FIGS. 2, 3, 6 and 7, can include a computer system. In this regard, FIG. 8 is a schematic diagram representation of additional detail regarding an exemplary form of an exemplary computer system 186 that is adapted to execute instructions. In this regard, the computer system 186 includes a set of instructions for causing the DAS component(s) to provide its designed functionality. The DAS component(s) may be connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. The DAS component(s) may operate in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. While only a single device is illustrated, the term "device" shall also be taken to include any collection of devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. The DAS component(s) may be a circuit or circuits included in an electronic board card, such as a printed circuit board (PCB) as an example, a server, a personal computer, a desktop computer, a laptop computer, a personal digital assistant (PDA), a computing pad, a mobile device, or any other device, and may represent, for example, a server or a user's computer. The exemplary computer system 184 in this embodiment includes a processing device or processor 188, a main memory 190 (e.g., readonly memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM), etc.), and a static memory 192 (e.g., flash memory, static random access memory (SRAM), etc.), which may communicate with each other via a data bus 194. Alternatively, the processing device 188 may be connected to the main memory 190 and/or static memory 192 directly or via some other connectivity means. The processing device 188 may be a controller, and the main memory 190 or static memory 192 may be any type of memory, each of which can be included in the monitoring unit, monitoring module #, listening unit #, and/or listening module # of FIGS. 2, 3, 6 and 7, for example.

[0061] The processing device 188 represents one or more general-purpose processing devices such as a microprocessor, central processing unit, or the like. More particularly, the processing device 188 may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or processors implementing a combination of instruction sets. The processing device 188 is configured to execute processing logic in instructions 196 (located in the processing device 188 and/or the main memory 190) for performing the operations and steps discussed herein.

[0062] The computer system 186 may further include a network interface device 198. The computer system 186 also may or may not include an input 200 to receive input and selections to be communicated to the computer system 186 when executing instructions. The computer system 186 also may or may not include an output 202, including but not limited to a display, a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)), an alphanumeric input device (e.g., a keyboard), and/or a cursor control device (e.g., a mouse). [0063] The computer system 186 may or may not include a data storage device 204 that includes instructions 206 stored in a computer-readable medium 208. The instructions 206 may also reside, completely or at least partially, within the main memory 190 and/or within the processing device 188 during execution thereof by the computer system 186, the main memory 190 and the processing device 188 also constituting the computer-readable medium 208. The instructions 196, 206 may further be transmitted or received over a network 178 via the network interface device 198.

[0064] While the computer-readable medium 208 is shown in an exemplary embodiment to be a single medium, the term "computer-readable medium" should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term "computer- readable medium" shall also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by the processing device and that cause the processing device to perform any one or more of the methodologies of the embodiments disclosed herein. The term "computer-readable medium" shall accordingly be taken to include, but not be limited to, solid-state memories, optical and magnetic medium, and carrier wave signals.

[0065] The embodiments disclosed herein include various steps that may be performed by hardware components or may be embodied in machine-executable instructions, which may be used to cause a general-purpose or special-purpose processor programmed with the instructions to perform the steps. Alternatively, the steps may be performed by a combination of hardware and software.

[0066] The embodiments disclosed herein may be provided as a computer program product, or software, that may include a machine-readable medium (or computer-readable medium) having stored thereon instructions, which may be used to program a computer system (or other electronic devices) to perform a process according to the embodiments disclosed herein. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable medium includes a machine-readable storage medium (e.g., read only memory ("ROM"), random access memory ("RAM"), magnetic disk storage medium, optical storage medium, flash memory devices, etc.).

[0067] The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A controller may be a processor. A processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0068] The embodiments disclosed herein may be embodied in hardware and in instructions that are stored in hardware, and may reside, for example, in Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, a hard disk, a removable disk, a CD-ROM, or any other form of computer-readable medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a remote station. In the alternative, the processor and the storage medium may reside as discrete components in a remote station, base station, or server.

[0069] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.

[0070] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the invention. Since modifications combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and their equivalents.