Patent Description:
A Distributed Antenna System (DAS) typically includes one or more master units that are communicatively coupled with a plurality of remote antenna units, where each remote antenna unit can be coupled directly to one or more of the master units or indirectly via one or more other remote antenna units and/or via one or more intermediary or expansion units. A DAS is typically used to improve the coverage provided by one or more base stations that are coupled to the master units. These base stations can be coupled to the master units via one or more cables or via a wireless connection, for example, using one or more donor antennas. The wireless service provided by the base stations can included commercial cellular service and/or private or public safety wireless communications.

In such a safety application, the safety wireless capacity provided by the DAS and the associated base-station-related equipment during normal operations may not be sufficient in emergency situations (such as a fire or security event) due to the presence of many additional users of the safety wireless service. As a result, it is common to provision a DAS used for such safety applications with additional base-station-related and DAS equipment (base stations, repeaters, etc.) that operate in a standby mode during normal operations but can be activated in emergency situations in order to provide increased safety wireless service capacity when necessary.

When planning for coverage within public safety relevant facilities by emergency services providers, the signal distributing infrastructure of the DAS may be shared between private and public safety services, each operating on their own frequency bands. For example the assigned licensed bands for the German Public Safety Digital Radio (BDBOS) TETRA network in Germany are <NUM>-<NUM> for uplink communications and <NUM>-<NUM> in downlink communications. For private safety services, different bands are used. For example, <NUM>-<NUM> may be used for uplink communications and <NUM>-<NUM> may be used for downlink communications for private safety services. Public safety signals are usually used by government agencies, such as police or fire, and public safety coverage is available from base stations provided across large geographic regions (for example, nationwide coverage). Private safety signal coverage, in contrast, is usually found within specific facilities or other areas of private service responsibility, for example, for the use of facility operator.

Subways, and specifically subway tubes, are one example of a facility where the communication infrastructure for both public and private safety services are extended and distributed. It is understood that subway trains may operate on tracks in tunnels below ground, and also on tracks above ground. However, while coverage for private safety services may be desired throughout the subway facility, distributing public safety communications coverage to above ground segments may cause interference with public safety communications coverage provided by other base stations operating in that area. As such, it may be required by regulations that public safety communications coverage by the subway operator's DAS should extend only to the below ground segments of the subway system to avoid interference with the signals from local public safety communications base stations operating close to the above ground segments.

It is therefore highly desirable for remote antenna units operating in above ground segments to be able to switch "off" the public safety band. It is also desirable to be able to selectively switch "on" the public safety band for those same remote antenna units for some emergency cases where the local base station that normally provides coverage around an above ground segment of a subway tube fails and cannot provide public safety coverage in that area.

One standard solution to this problem is for each remote unit to have separately operated communication paths in each remote antenna unit for each band- one for public safety coverage and one for private safety coverage. Then, the power amplifier, low noise amplifier, and/or other electronics for uplink and downlink transport of the public safety communications band may be switched off for those remote units operating in above ground segments. This solution has a big disadvantage however in terms of price since two expensive power amplifier modules (in addition to other RF components) would be needed, one for each downlink safety band of the remote unit. For public safety operators, this redundant and expensive equipment remains dormant most of the time, except for when emergency situations require its operation.

In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize. Reference characters denote like elements throughout figures and text.

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 embodiments. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, 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 disclosure. The following detailed description is, therefore, not to be taken in a limiting sense.

Embodiments of the present disclosure provide solutions for DAS operators to selectively disable public safety bands at select remote units without the need to for remote antenna units to be equipped with expensive multiple independent signal paths. The embodiments illustrated herein present solutions that adopt a novel perspective as to what it means for an operating band of a DAS to be "switched off". More specifically, when it is desired to disable a specific operating band, as opposed to disconnecting a signal path or de-powering down electronics associated with that operating band, the embodiments presented herein selectively reconfigure a signal path to suppress signals in that operating band. For example, if the signals for a public safety operating band are sufficiently suppressed to a level at or below signal levels that would be considered a permitted spurious RF emissions (while the private safety operating band remains operable) then the public safety operating band has effectively been turned off without leaving expensive electronics components sitting idle and unutilized within the remote antenna unit.

For example, in the field of commercial cellular communications, a signal emission having a power level of -<NUM> dBm or less from a base station or remote antenna unit would be considered an acceptable spurious emission at the antenna. Other examples of acceptable maximum permitted levels of spurious emissions for different applications and radio frequency equipment may be found in International Telecommunications Union recommendation ITU-R SM. <NUM>-<NUM> which is herein incorporated by reference in its entirety.

Assuming a remote antenna unit is designed to transmit from its antenna a downlink signal (DL1) at the output power level of +<NUM> dBm per carrier in a first band, DL1, and that signal values below -<NUM> dBm at the antenna port are considered an acceptable spurious emission, then to suppress the DL1 frequencies, the DL1 band could attenuated by <NUM> dB or more (+<NUM> dBm - (-<NUM> dBm) = <NUM> dB) to reach values below -<NUM> dBm at the antenna port. Thus, if this example remote antenna unit includes a band suppression module that selectively applies an attenuation of <NUM> dB to the DL1 band, it can effectively suppressed and turn off the DL1 band.

<FIG> is block diagram of one exemplary embodiment of a distributed antenna system (DAS) <NUM> where the remote antenna units utilize band suppression modules as described herein. As shown in <FIG>, the DAS <NUM> comprises one or more master units <NUM> that are communicatively coupled to one or more remote antenna units <NUM> via one or more cables <NUM>. In some embodiments, the cables <NUM> discussed herein may each operate bidirectionally with downlink and uplink communications carried over the cable. It should also be understood, however, that in other embodiments, a cable <NUM> may itself further comprise a pair of cables including an uplink cable for uplink communication, and a downlink cable for downlink communication. Each remote antenna unit <NUM> can be communicatively coupled directly to one or more of the master units <NUM> or indirectly via one or more other remote antenna units <NUM> and/or via one or more intermediary or expansion units <NUM>.

Each master unit <NUM> is communicatively coupled to one or more base stations <NUM>. One or more of the base stations <NUM> can be co-located with the respective master units <NUM> to which it is coupled (for example, where the base station <NUM> is dedicated to providing base station capacity to the DAS <NUM> and is coupled to the respective master units <NUM>). Also, one or more of the base stations <NUM> can be located remotely from the respective master units <NUM> to which it is coupled (for example, where the base station <NUM> provides base station capacity to an area beyond the coverage area of the DAS <NUM>). In this latter case, the master unit <NUM> can be coupled to a donor antenna and repeater or bi-directional amplifier in order to wirelessly communicate with the remotely located base station <NUM>.

In this exemplary embodiment, the base stations <NUM> include one or more base stations that are used to provide public and/or private safety wireless services (for example, wireless communications used by emergency services organizations (such as police, fire and emergency medical services) to prevent or respond to incidents that harm or endanger persons or property). Such base stations are also referred to here as "safety wireless service base stations" or "safety base stations. " The base stations <NUM> also can include, in addition to safety base stations, one or more base stations that are used to provide commercial cellular wireless service. Such base stations are also referred to here as "commercial wireless service base stations" or "commercial base stations.

The base stations <NUM> can be coupled to the master units <NUM> using a network of attenuators, combiners, splitters, amplifiers, filters, cross-connects, etc., (sometimes referred to collectively as a "point-of-interface" or "POI"). This network can be included in the master units <NUM> and/or can be separate from the master units <NUM>. This is done so that, in the downlink, the desired set of RF channels output by the base stations <NUM> can be extracted, combined, and routed to the appropriate master units <NUM>, and so that, in the upstream, the desired set of carriers output by the master units <NUM> can be extracted, combined, and routed to the appropriate interface of each base station <NUM>. It is to be understood, however, that this is one example and that other embodiments can be implemented in other ways.

As shown in <FIG>, in general, each master unit <NUM> comprises downlink DAS circuitry <NUM> that is configured to receive one or more downlink signals from one or more base stations <NUM>. These signals are also referred to here as "base station downlink signals. " Each base station downlink signal includes one or more radio frequency channels used for communicating in the downlink direction with user equipment <NUM> (such as tablets or cellular telephone, for example) over the relevant wireless air interface. Typically, each base station downlink signal is received as an analog radio frequency signal, though in some embodiments one or more of the base station signals are received in a digital form (for example, in a digital baseband form complying with the Common Public Radio Interface ("CPRI") protocol, Open Radio Equipment Interface ("ORI") protocol, the Open Base Station Standard Initiative ("OBSAI") protocol, or other protocol). The downlink DAS circuitry <NUM> in each master unit <NUM> is also configured to generate one or more downlink transport signals derived from one or more base station downlink signals and to transmit one or more downlink transport signals to one or more of the remote antenna units <NUM>.

As shown in <FIG>, each remote antenna unit <NUM> comprises downlink DAS circuitry <NUM> that is configured to receive the downlink transport signals transmitted to it from one or more master units <NUM> and to use the received downlink transport signals to generate one or more downlink radio frequency signals that are radiated from one or more antennas <NUM> associated with that remote antenna unit <NUM> for reception by user equipment <NUM>. These downlink radio frequency signals are analog radio frequency signals and are also referred to here as "remote downlink radio frequency signals. " Each remote downlink radio frequency signal includes one or more of the downlink radio frequency channels used for communicating with user equipment <NUM> over the wireless air interface. In this way, the DAS <NUM> increases the coverage area for the downlink capacity provided by the base stations <NUM>.

Also, each remote antenna unit <NUM> comprises uplink DAS circuitry <NUM> that is configured to receive via antenna <NUM> one or more uplink radio frequency signals transmitted from the user equipment <NUM>. These signals are analog radio frequency signals and are also referred to here as "remote uplink radio frequency signals. " Each uplink radio frequency signal includes one or more radio frequency channels used for communicating in the uplink direction with user equipment <NUM> over the relevant wireless air interface. The uplink DAS circuitry <NUM> in each remote antenna unit <NUM> is also configured to generate one or more uplink transport signals derived from the one or more remote uplink radio frequency signals and to transmit one or more uplink transport signals to one or more of the master units <NUM>.

Each master unit <NUM> comprises uplink DAS circuitry <NUM> that is configured to receive the respective uplink transport signals transmitted to it from one or more remote antenna units <NUM> and to use the received uplink transport signals to generate one or more base station uplink radio frequency signals that are provided to the one or more base stations <NUM> associated with that master unit <NUM>. Typically, this involves, among other things, combining or summing uplink signals received from multiple remote antenna units <NUM> in order to produce the base station signal provided to each base station <NUM>. Each base station uplink signal includes one or more of the uplink radio frequency channels used for communicating with user equipment <NUM> over the wireless air interface. In this way, the DAS <NUM> increases the coverage area for the uplink capacity provided by the base stations <NUM>.

As shown in <FIG>, each expansion unit <NUM> comprises downlink DAS circuitry <NUM> that is configured to receive the downlink transport signals transmitted to it from the master unit <NUM> (or other expansion unit <NUM>) and transmits the downlink transport signals to one or more remote antenna units <NUM> or other downstream intermediary units <NUM>. Each expansion unit <NUM> comprises uplink DAS circuitry <NUM> that is configured to receive the respective uplink transport signals transmitted to it from one or more remote antenna units <NUM> or other downstream intermediary units <NUM>, combine or sum the received uplink transport signals, and transmit the combined uplink transport signals upstream to the master unit <NUM> or other expansion unit <NUM>. In some embodiments, one or more remote antenna units <NUM> may be coupled to the one or more master units <NUM> via one or more other remote antenna units <NUM> (for examples, where the remote antenna units <NUM> are coupled together in a daisy chain or ring topology). In such an embodiments, an expansion unit <NUM> may be implemented using a remote antenna units <NUM>.

The downlink DAS circuitry <NUM>, <NUM>, and <NUM> and uplink DAS circuitry <NUM>, <NUM>, and <NUM> in each master unit <NUM>, remote antenna unit <NUM>, and expansion unit <NUM>, respectively, can comprise one or more appropriate connectors, attenuators, combiners, splitters, amplifiers, filters, duplexers, analog-to-digital converters, digital-to-analog converters, mixers, field-programmable gate arrays (FPGAs), microprocessors, transceivers, framers, etc., to implement the features described above. Also, the downlink DAS circuitry <NUM>, <NUM>, and <NUM> and uplink DAS circuitry <NUM>, <NUM>, and <NUM> may share common circuitry and/or components. For example, some components (such as duplexers) by their nature are shared among the downlink DAS circuitry <NUM>, <NUM>, and <NUM> and uplink DAS circuitry <NUM>, <NUM>, and <NUM>.

The DAS <NUM> can use either digital transport, analog transport, or combinations of digital and analog transport for generating and communicating the transport signals between the master units <NUM>, the remote antenna units <NUM>, and any intermediary units <NUM>. For the purposes of illustration, some of the embodiments described here are implemented using analog transport over optical cables. However, it is to be understood that other embodiments can be implemented in other ways, for example, in DASs that use other types of analog transport (for example, using other types of cable and/or using analog transport that makes use of frequency shifting), digital transport (for example, where digital samples indicative of the analog base station radio frequency signals and analog remote radio frequency signals are generated and communicated between the master units <NUM> and the remote antenna units <NUM>), or combinations of analog and digital transport.

Each unit <NUM>, <NUM>, <NUM> in the DAS <NUM> can also comprises a respective controller <NUM>. The controller <NUM> is implemented using one or more programmable processors that execute software that is configured to implement the various features described here as being implemented by the controller <NUM>. The controller <NUM>, the various features described here as being implemented by the controller <NUM>, or portions thereof, can be implemented in other ways (for example, in a field programmable gate array (FPGA), application specific integrated circuit (ASIC), etc.).

Each controller <NUM> is configured to monitor and control the operation of the associated unit. Each controller <NUM> is also configured to send and receive management data over the DAS <NUM>. In one embodiment, each unit <NUM>, <NUM>, <NUM> in the DAS <NUM> also comprises a modem <NUM> that is configured to send and receive management data over the DAS <NUM> by modulating and demodulating one or more carrier frequencies that are used for the purpose of communicating management data. In some embodiments (for example, where digital transport is used in the DAS), a separate modem <NUM> for modulating and demodulating management data is not used and, instead, the management data is combined with the digital DAS transport data before being supplied to the transport transceiver or other physical layer device.

One or more of the units <NUM>, <NUM>, <NUM> in the DAS <NUM> also comprise an interface <NUM> to couple the controller <NUM> in that unit <NUM>, <NUM>, <NUM> to an operator control panel <NUM> that is deployed near that unit <NUM>, <NUM>, <NUM>. The interface <NUM> is therefore also referred to here as an "OCP interface <NUM>. " Each such unit <NUM>, <NUM>, <NUM> can include an appropriate connector to attach a cable <NUM> (also referred to here as an "OCP cable <NUM>") that is used to couple the unit <NUM>, <NUM>, <NUM> to the OCP <NUM>. In general, each OCP <NUM> can be connected to the nearest unit <NUM>, <NUM>, <NUM> of the DAS <NUM>.

As mentioned above, in addition to potentially providing commercial connectivity to users via consumer bands, DAS <NUM> also distributes public safety connectivity coverage and private safety communication coverage. In the exemplary embodiment shown in <FIG>, each remote unit <NUM> includes a band suppression module (BSM) <NUM> that selectively applies an attenuation to specific uplink and/or downlink bands to effectively turn off those bands.

<FIG> is a simplified diagram illustrating remote antenna unit <NUM> of one embodiment of the present disclosure that may be used to implement any one of the remote units <NUM> of the DAS <NUM> described above in connection with <FIG> and operate in conjunction with the master unit <NUM> shown in <FIG>. In the particular embodiment shown in <FIG>, remote antenna unit <NUM> comprises least one optical transceiver interface (OTRX) <NUM> for communicating via optical fiber with the master unit <NUM>. It should be appreciated that in other embodiments, the master unit <NUM> and remote unit <NUM> may communicate over other types of wiring or cables. Remote antenna unit <NUM> further comprises an RF power amplifier <NUM>, a downlink signal diplexer <NUM>, an antenna port <NUM> that is configured to couple to remote unit <NUM> to an antenna <NUM>, an uplink signal diplexer <NUM>, a low noise amplifier (LNA) <NUM>, and a band suppression module <NUM>. Power amplifier <NUM> power amplifies downlink signals to a desired power level and feeds it to antenna <NUM> to radiate to user equipment <NUM> (not shown in <FIG>) via diplexer <NUM>. Uplink radio frequency signals transmitted from user equipment <NUM> in the coverage area of the remote antenna unit <NUM> are received via the associated antenna <NUM> and provided to LNA <NUM>, which amplifies the received uplink signals. The downlink signal diplexer <NUM> comprises a first band filter <NUM> that filters out signals having a frequency outside of the first DL band (DL1) and a second band pass filter <NUM> that filters out signals having a frequency outside of the second DL band (DL2). For example, in one embodiment, the DL1 band may pass through only public safety coverage signals (e.g. in the <NUM>-<NUM> band) while the DL2 band may pass through only private safety coverage signals (e.g. in the <NUM>-<NUM> band). As such, though the power amplifier <NUM> may output a broad range of amplified signals, only those signals in frequency bands for which DAS <NUM> is authorized to transmit will pass to the antenna port <NUM> and radiate from antenna <NUM>. Similarly, the uplink signal diplexer <NUM> comprises a first band pass filter <NUM> and a second band pass filter <NUM>. In one embodiment, the UL1 band may pass through only public safety coverage signals (e.g. in the <NUM>-<NUM> band) while the UL2 band may pass through only private safety coverage signals (e.g. in the <NUM>-<NUM> band). As such, the UL1 and UL2 signals received by antenna <NUM> may pass to the low noise amplifier without high power downlink signals saturating the uplink path electronics of the remote antenna unit <NUM>.

Band suppression module <NUM> switches between two or more modes. For example, in a first mode, band suppression module <NUM> may be switched to selectively apply an attenuation to suppress the DL1 and UL1 bands (which may be associated with public safety coverage signals, for example) while allowing the DL2 and UL2 bands (which may be associated with the private safety coverage signals, for example) to pass. In a second mode, band suppression module <NUM> may be switched to allow DL1 and UL1 bands and the DL2 and UL2 bands to pass. In some embodiments, a third mode may optionally be provided to selectively apply an attenuation to suppress the DL2 and UL2 bands while allowing the DL1 and UL1 bands to pass.

Band suppression module <NUM>, the various features described here as being implemented by the band suppression module <NUM>, or portions thereof, can be implemented by RF electronics in combination with for example, control circuitry and/or code executed in a processor, in a field programmable gate array (FPGA), application specific integrated circuit (ASIC), etc. In the embodiment shown in <FIG>, the band suppression module <NUM> includes at least one switchable RF downlink band suppression element <NUM>, at least one switchable RF uplink band suppression element <NUM>, and a band suppression controller <NUM>. In some embodiments, the band suppression controller <NUM> may be implemented with electronics responsive to signals from the remote unit controller <NUM>. In some embodiments, the band suppression controller <NUM> may be implemented at least in part as a software application executed by the controller <NUM>. The downlink and uplink band suppression elements <NUM> and <NUM> may be implemented in varies ways, for example by switchable notch filters or band pass filters, or using hybrid couplers or circulators with switchable loads.

For example, <FIG> illustrates an example embodiment of the remote antenna unit <NUM> where the band suppression elements <NUM> and <NUM> of the band suppression module <NUM> are implemented using an RF network element <NUM> (such as a circulator or hybrid coupler, for example) with at least one switchable load <NUM> that may be selected or deselect by band suppression controller <NUM>. For example, in one embodiment, a downlink signal having DL1 and DL2 band components is received at band suppression element <NUM>. When suppression of public safety coverage signals is needed, band suppression controller <NUM> switches in the switchable load <NUM> so that the band suppression element <NUM> transmits the downlink signal having DL1 and DL2 into the switchable load <NUM>. Switchable load <NUM> is tuned to absorb RF signals in the DL1 band so that any component of DL1 exiting out from switchable load <NUM> is attenuated below a threshold power level (for example, a level at which the signal would be considered a spurious emission). For the Example discussed above where the power amplifier <NUM> nominally delivers a +30dBm signal per carrier to the antenna <NUM>, the switchable load <NUM> attenuates the DL1 signal it receives by <NUM> dB so that the when attenuated DL1 signal is provided to the power amplifier <NUM> and then radiated by antenna <NUM>, the transmitted power of the DL1 signal is at or below -<NUM> dBm at the antenna port <NUM>. These attenuation values are provided as illustrative examples only. One of ordinary skill in the art would be able to determine the threshold power level for the signal to be considered negligible (e.g. at or below a level of a spurious emission). It also should be appreciated that switchable load <NUM> may comprise multiple load elements coupled together in order to achieve the attenuation desired. In one embodiment, when suppression of public safety coverage signals is not desired, band suppression controller <NUM> can switch out the switchable load <NUM> so that the band suppression element <NUM> bypasses switchable load <NUM> and thus transmits the downlink signal having both DL1 and DL2 to power amplifier <NUM> so that DL1 and DL2 signals are provided to the power amplifier <NUM> and then radiated by antenna <NUM> at full nominal power (e.g. +30dBm signal per carrier).

Similarly, in one embodiment, an uplink signal having UL1 and UL2 band components is received at band suppression element <NUM>. When suppression of public safety coverage signals is needed, band suppression controller <NUM> switches in the switchable load <NUM> so that the band suppression element <NUM> transmits the uplink signal having UL1 and UL2 into the switchable load <NUM>. Switchable load <NUM> is tuned to absorb RF signals in the UL1 band so that any component of UL1 exiting out from switchable load <NUM> is attenuated below a threshold power level (for example, a level at which the signal would be considered a spurious emission). One of ordinary skill in the art would be able to determine the threshold power level for the signal to be considered negligible (e.g. at or below a level of a spurious emission). It also should be appreciated that switchable load <NUM> may comprise multiple load elements coupled together in order to achieve the attenuation desired. When suppression of public safety coverage signals is not desired, band suppression controller <NUM> switches out the switchable load <NUM> so that the band suppression element <NUM> bypasses switchable load <NUM> and thus transmits the uplink signal having both UL1 and UL2 to the master unit <NUM>, which then proceeds up to base station <NUM>.

<FIG> illustrates another example embodiment of the remote antenna unit <NUM> where the band suppression elements <NUM> and <NUM> of the band suppression module <NUM> are implemented using RF band pass filters. In this example embodiment, band suppression module <NUM> comprises a downlink signal path that includes a downlink band pass filter element <NUM>, a first matching attenuator <NUM> having an insertion loss equivalent to the insertion loss of the downlink band pass filter element <NUM>, and one or more downlink suppression selection switches <NUM> coupled to and operated by the band suppression controller <NUM>. Band suppression module <NUM> further comprises an uplink signal path that includes an uplink band pass filter element <NUM>, a second matching attenuator <NUM> having an insertion loss equivalent to the insertion loss of the uplink band pass filter element <NUM>, and one or more uplink suppression selection switches <NUM> coupled to an operated by the band suppression controller <NUM>.

In one embodiment, a downlink signal having DL1 and DL2 band components is received at band suppression element <NUM>. When suppression of public safety coverage signals is needed, band suppression controller <NUM> switches the one or more downlink suppression selection switches <NUM> so that the downlink signal having DL1 and DL2 band components is transmitted into the downlink band pass filter element <NUM>.

Downlink band pass filter <NUM> is tuned to pass the DL2 band but filter out RF signals in the DL1 band so that any component of DL1 exiting out from downlink band pass filter <NUM> is attenuated below a threshold power level (for example, a level at which the signal would be considered a spurious emission). One of ordinary skill in the art would be able to determine the threshold power level for the signal to be considered negligible (e.g. at the level of a spurious emission). When suppression of public safety coverage signals is not desired, band suppression controller <NUM> switches the one or more downlink suppression selection switches <NUM> so that the downlink signal having DL1 and DL2 band components is instead transmitted through the first matching attenuator <NUM> to the power amplifier <NUM> so that DL1 and DL2 signals are provided to the power amplifier <NUM> and then radiated by antenna <NUM> at full nominal power (e.g. +30dBm signal per carrier). Because the first matching attenuator <NUM> comprises an insertion loss equivalent to the insertion loss of the downlink band pass filter <NUM>, there is no change in the power level of the DL2 (private safety cover signal) transmitted by remote antenna unit <NUM> due to the switching the DL1 band between the on (i.e. full nominal power) or off (i.e. suppressed) states.

In one embodiment, an uplink signal having UL1 and UL2 band components is received at band suppression element <NUM>. When suppression of public safety coverage signals is needed, band suppression controller <NUM> switches the one or more uplink suppression selection switches <NUM> so that the uplink signal having UL1 and UL2 band components is transmitted into the uplink band pass filter <NUM>.

Uplink band pass filter <NUM> is tuned to pass the UL2 band but filter out RF signals in the UL1 band so that any component of UL1 exiting out from uplink band pass filter <NUM> is attenuated below a threshold power level (for example, a level at which the signal would be considered a spurious emission). One of ordinary skill in the art would be able to determine the threshold power level for the signal to be considered negligible (e.g. at the level of a spurious emission). When suppression of public safety coverage signals is not desired, band suppression controller <NUM> switches the one or more uplink suppression selection switches <NUM> so that the uplink signal having UL1 and UL2 band components is instead transmitted through the second matching attenuator <NUM> so that UL1 and UL2 signals are provided from the LNA <NUM> to the OTRX <NUM> and then transmitted to the master unit <NUM>. Because the second matching attenuator <NUM> comprises an insertion loss equivalent to the insertion loss of the uplink band pass filter <NUM>, there is no change in the power level of the UL2 (private safety cover signal) received by the master unit <NUM> due to the switching the UL1 band between on (i.e. nominal power) or off (i.e. suppressed) states.

In one embodiment, band suppression controller <NUM> responds to management data which may be received by DAS <NUM> is multiple different ways. For example, in one embodiment, DAS <NUM> receives management data for activating or deactivating the UL1 and DL1 bands for select RAUs <NUM> through input entered by an operator into one of the OCP <NUM> coupled to the master unit <NUM> via OCP interface <NUM>, an RAU <NUM>, or an expansion unit <NUM>. Alternatively, management data for activating or deactivating the UL1 and DL1 bands may be communicated via one of the modems <NUM> used for the purpose of communicating management data. As another alternative, management data for activating or deactivating the UL1 and DL1 bands may be received by the master unit <NUM> from one of the base stations <NUM>. Management data comprising instruction to activate/deactivate the UL1 and DL1 bands may then be transmitted to the affected RAU <NUM> where the controller <NUM> responds by suppressing the UL1 and DL1 bands (for example, in any manner discussed above).

In some embodiments, instruction to activate/deactivate the UL1 and DL1 bands are addressed to specific RAU <NUM> of the DAS <NUM> so that only those RAU <NUM> respond to the instructions. In other embodiments, the band suppression module <NUM> in one or more of the RAU <NUM> may be programmed with a default and one or more emergency event configurations that depend on their physical location. For example, a first RAU <NUM> of DAS <NUM> may be physically located inside a facility, but at a location where one or more of its operating bands can potentially interfere with those of local base stations outside of the facility (for example, the first RAU <NUM> is located in an above ground segment of a subway system). The band suppression controller <NUM> may have stored in a memory <NUM> a default first configuration with settings that configure BSM <NUM> to suppress UL1 and DL1 under nominal default conditions, and a second configuration with settings that configured BSM <NUM> to pass UL1 and DL1 without suppression under a specified event condition. At the same time, a second RAU <NUM> of DAS <NUM> may be physically located inside a facility at a position where it cannot interfere with those of local base stations outside of the facility (for example, the second RAU <NUM> is located in an underground segment of a subway system). The band suppression controller <NUM> for this second RAU <NUM> may have stored in memory <NUM> a default first configuration with setting that configure its BSM <NUM> to pass UL1 and DL1 without suppression under nominal default conditions, and a second configuration with setting that also configure BSM <NUM> to pass UL1 and DL1 without suppression under the specified event condition. In this way, the DAS <NUM> may simply communicate blanket message to all RAU <NUM> to either enter an event configuration state, or return to their default configuration state, and each RAU <NUM> will respond accordingly and consistent with how the default configuration and event configuration are particularly defined within their specific BSM <NUM>. It should also be understood that more than one event configuration may be defined within each RAU <NUM> and the RAU <NUM> could therefor configure itself based on which event is identified in the activate/deactivate instruction it receives.

<FIG> illustrates another example embodiment of the remote antenna unit <NUM> where the band suppression module <NUM> can be switched into multiple alternate modes where either the UL1 & DL1 bands are suppressed, the UL2 & DL2 bands are suppressed, or neither set of bands are suppressed.

In this example embodiment, band suppression module <NUM> comprises a downlink signal path that includes a first downlink band pass filter element <NUM>-<NUM>, a second downlink band pass filter element <NUM>-<NUM>, a first matching attenuator <NUM> having an insertion loss equivalent to the insertion loss of the downlink band pass filter elements <NUM>-<NUM> and <NUM>-<NUM>, and one or more downlink suppression selection switches <NUM> coupled to and operated by the band suppression controller <NUM>. Band suppression module <NUM> further comprises an uplink signal path that includes a first uplink band pass filter element <NUM>-<NUM>, a second uplink band pass filter element <NUM>-<NUM>, a second matching attenuator <NUM> having an insertion loss equivalent to the insertion loss of the uplink band pass filter elements <NUM>-<NUM> and <NUM>-<NUM>, and one or more uplink suppression selection switches <NUM> coupled to an operated by the band suppression controller <NUM>.

In one embodiment, a downlink signal having DL1 and DL2 band components is received at band suppression element <NUM>. When suppression of the DL1 band is needed, band suppression controller <NUM> switches the one or more downlink suppression selection switches <NUM> so that the downlink signal having DL1 and DL2 band components is transmitted into the downlink band pass filter element <NUM>-<NUM>. Downlink band pass filter <NUM>-<NUM> is tuned to pass the DL2 band but filter out RF signals in the DL1 band so that any component of DL1 exiting out from downlink band pass filter <NUM> is attenuated below a threshold power level (for example, a level at which the signal would be considered a spurious emission). When suppression of the DL2 band is needed, band suppression controller <NUM> switches the one or more downlink suppression selection switches <NUM> so that the downlink signal having DL1 and DL2 band components is transmitted into the downlink band pass filter element <NUM>-<NUM>. Downlink band pass filter <NUM>-<NUM> is tuned to pass the DL1 band but filter out RF signals in the DL2 band so that any component of DL2 exiting out from downlink band pass filter <NUM> is attenuated below a threshold power level (for example, a level at which the signal would be considered a spurious emission). One of ordinary skill in the art would be able to determine the threshold power level for the signal to be considered negligible (e.g. at the level of a spurious emission).

When suppression of neither DL1 nor DL2 is desired, band suppression controller <NUM> switches the one or more downlink suppression selection switches <NUM> so that the downlink signal having DL1 and DL2 band components is instead transmitted through the first matching attenuator <NUM> to the power amplifier <NUM> so that DL1 and DL2 signals are provided to the power amplifier <NUM> and then radiated by antenna <NUM> at full nominal power (e.g. +30dBm signal per carrier). Because the first matching attenuator <NUM> comprises an insertion loss equivalent to the insertion loss of the downlink band pass filter <NUM>-<NUM> and/or downlink band pass filter <NUM>-<NUM>, there is no change in the power level of the DL1 or DL2 signals transmitted by remote antenna unit <NUM> due to the switching.

In one embodiment, an uplink signal having UL1 and UL2 band components is received at band suppression element <NUM>. When suppression of the UL1 band is needed, band suppression controller <NUM> switches the one or more uplink suppression selection switches <NUM> so that the uplink signal having UL1 and UL2 band components is transmitted into the uplink band pass filter <NUM>-<NUM>. Uplink band pass filter <NUM>-<NUM> is tuned to pass the UL2 band but filter out RF signals in the UL1 band so that any component of UL1 exiting out from uplink band pass filter <NUM>-<NUM> is attenuated below a threshold power level (for example, a level at which the signal would be considered a spurious emission). When suppression of the UL2 band is needed, band suppression controller <NUM> switches the one or more uplink suppression selection switches <NUM> so that the uplink signal having UL1 and UL2 band components is transmitted into the uplink band pass filter <NUM>-<NUM>. Uplink band pass filter <NUM>-<NUM> is tuned to pass the UL1 band but filter out RF signals in the UL2 band so that any component of UL2 exiting out from uplink band pass filter <NUM>-<NUM> is attenuated below a threshold power level. One of ordinary skill in the art would be able to determine the threshold power level for the signal to be considered negligible (e.g. at the level of a spurious emission).

When suppression of neither UL1 or UL2 is desired, band suppression controller <NUM> switches the one or more uplink suppression selection switches <NUM> so that the uplink signal having UL1 and UL2 band components is instead transmitted through the second matching attenuator <NUM> so that UL1 and UL2 signals are provided from the LNA <NUM> to the OTRX <NUM> and then transmitted to the master unit <NUM>. Because the second matching attenuator <NUM> comprises an insertion loss equivalent to the insertion loss of the uplink band pass filter <NUM>-<NUM> and/or uplink band pass filter <NUM>-<NUM>, there is no change in the power level of the UL1 or UL2 signals transmitted by remote antenna unit <NUM> due to the switching.

It should also be appreciated that other network architectures may be implemented that still functionally operate in the same manner as described in any of the embodiments described herein. It should also be understood that for any of the embodiments described herein, while the communication links connecting master units and remote antenna units may comprise optical fiber, in other embodiments other wired or wireless communication links, or combinations thereof, may be utilized instead of, or in combination with, optical fiber communication links.

As used herein, DAS related terms such as "master unit", "remote unit", "remote antenna unit" and "control unit" and "controller" refer to hardware elements that would be immediately recognized and understood by those of skill in the art of wireless communications and are not used herein as nonce words or nonce terms for the purpose of invoking <NUM> USC <NUM>(f).

Example <NUM> includes a distributed antenna system, the system comprising: at least one master unit configured to receive a base station downlink radio frequency signal and to transmit a base station uplink radio frequency signal; at least one remote antenna unit that is communicatively coupled to the at least one master unit, the remote antenna unit comprising a power amplifier and configured to radiate a remote downlink radio frequency signal from at least one antenna associated with the remote antenna unit, the remote antenna unit further configured to receive a remote uplink radio frequency signal from at least one antenna associated with the remote antenna unit, wherein the remote downlink radio frequency signal comprises a first downlink frequency band and a second downlink frequency band and wherein the remote uplink radio frequency signal comprises a first uplink frequency band and a second uplink frequency band; a band suppression module comprising: a band suppression controller; an uplink band suppression element controlled by the band suppression controller, wherein the uplink band suppression element is configured to apply an attenuation to suppress the first uplink frequency band in response to a signal from the band suppression controller; and a downlink band suppression element controlled by the band suppression controller, wherein the downlink band suppression element is configured to apply an attenuation to suppress the first downlink frequency band in response to the signal from the band suppression controller.

Example <NUM> includes the system of example <NUM>, wherein the first downlink frequency band and the first uplink frequency band define a public safety communications band, and where the second downlink frequency band and the second uplink frequency band define a private safety communications band.

Example <NUM> includes the system of any of examples <NUM>-<NUM>, wherein the band suppression controller comprises electronics responsive to a management signal received by the distributed antenna system, wherein the band suppression controller controls one or both of the uplink band suppression element and the downlink band suppression element in response to the management signal.

Example <NUM> includes the system of any of examples <NUM>-<NUM>, wherein the band suppression module further comprises a memory coupled to the band suppression controller, the memory storing a plurality of configuration setting; wherein the band suppression controller selectively reads a configuration setting from the memory to control the uplink band suppression element and the downlink band suppression element.

Example <NUM> includes the system of any of examples <NUM>-<NUM>, wherein the uplink band suppression element and the downlink band suppression element each further comprise: an RF network element; and at least one switchable load coupled to the RF network element; wherein the band suppression controller is configured to control application of the at least one switchable load to suppress one of the first uplink signal or the first downlink signal.

Example <NUM> includes the system of example <NUM>, wherein the RF network element comprises either a circulator or a hybrid coupler.

Example <NUM> includes the system of any of examples <NUM>-<NUM>, wherein the uplink band suppression element and the downlink band suppression element each further comprise: a band pass filter; a matching attenuator having an insertion loss equivalent to an insertion loss of the band pass filter; and one or more suppression selection switches coupled to the band pass filter and the matching attenuator, wherein the band suppression controller is configured to control the one or more suppression selection switches to toggle between the band pass filter and the matching attenuator.

Example <NUM> includes the system of any of examples <NUM>-<NUM>, wherein the uplink band suppression element is further configured to pass the second uplink frequency band and the downlink band suppression element is further configured to pass the second downlink frequency band.

Example <NUM> includes the system of any of examples <NUM>-<NUM>, wherein the uplink band suppression element and the downlink band suppression element each further comprise: a first band pass filter; a second band pass filter; a matching attenuator having an insertion loss equivalent to an insertion loss of either the first band pass filter or the second band pass filter; and one or more suppression selection switches coupled to the band pass filter and the matching attenuator, wherein the band suppression controller is configured to control the one or more suppression selection switches to switch between selection of the first band pass filter, the second band pass filter, of the matching attenuator, in response to the signal from the band suppression controller.

Example <NUM> includes a method for selectable band suppression for a distributed antenna system comprising at least one master unit and at least one remote antenna unit that is communicatively coupled to the at least one master unit, the at least one remote antenna unit carrying a remote downlink radio frequency signal comprising a first downlink frequency band and a second downlink frequency band, and a remote uplink radio frequency signal comprising a first uplink frequency band and a second uplink frequency band, the method comprising: determining whether the distributed antenna system is operating under a first status condition or a second status condition; when the distributed antenna system is determined to be operating under the first status condition, controlling at least one radio frequency (RF) band suppression element to suppress the first downlink frequency band and the first uplink frequency band while passing the second downlink frequency band and the second uplink frequency band; when the distributed antenna system is determined to be operating under the second status condition, controlling at least one radio frequency (RF) band suppression element to pass the first downlink frequency band, the first uplink frequency band, the second downlink frequency band and the second uplink frequency band.

Example <NUM> includes the method of example <NUM>, wherein the first downlink frequency band and the first uplink frequency band define a public safety communications band, and where the second downlink frequency band and the second uplink frequency band define a private safety communications band.

Example <NUM> includes the method of any of examples <NUM>-<NUM>, wherein the at least one remote antenna unit comprises a band suppression module comprising: a band suppression controller; an uplink band suppression element controlled by the band suppression controller, wherein the uplink band suppression element is configured to apply an attenuation to suppress the first uplink frequency band in response to a signal from the band suppression controller; and a downlink band suppression element controlled by the band suppression controller, wherein the downlink band suppression element is configured to apply an attenuation to suppress the first downlink frequency band in response to the signal from the band suppression controller.

Example <NUM> includes the method of example <NUM>, further comprising: generating the signal from the in response to a management signal received by the band suppression controller.

Example <NUM> includes the method of any of examples <NUM>-<NUM>, further comprising: in response to determining whether the distributed antenna system is operating under a first status condition or a second status condition, reading a configuration setting from a memory; and controlling the uplink band suppression element and the downlink band suppression element based on the configuration setting.

Example <NUM> includes the method of any of examples <NUM>-<NUM>, wherein the uplink band suppression element and the downlink band suppression element each further comprise: an RF network element; and at least one switchable load coupled to the RF network element; wherein the band suppression controller is configured to control application of the at least one switchable load to suppress one of the first uplink signal or the first downlink signal.

Example <NUM> includes the method of example <NUM>, wherein the RF network element comprises either a circulator or a hybrid coupler.

Example <NUM> includes the method of any of examples <NUM>-<NUM>, wherein the uplink band suppression element and the downlink band suppression element each further comprise: a band pass filter; a matching attenuator having an insertion loss equivalent to an insertion loss of the band pass filter; and one or more suppression selection switches coupled to the band pass filter and the matching attenuator, wherein the band suppression controller is configured to control the one or more suppression selection switches to toggle between the band pass filter and the matching attenuator.

Example <NUM> includes the method of any of examples <NUM>-<NUM>, further comprising determining whether the distributed antenna system is operating under the first status condition, the second status condition, or a third condition; when the distributed antenna system is determined to be operating under the third status condition, controlling at least one radio frequency (RF) band suppression element to suppress the second downlink frequency band and the second uplink frequency band while passing the first downlink frequency band and the first uplink frequency band.

Example <NUM> includes the method of example <NUM>, wherein the at least one remote antenna unit comprises a band suppression module comprising: a band suppression controller; an uplink band suppression element controlled by the band suppression controller, wherein the uplink band suppression element is configured to apply an attenuation to selectively suppress either the first uplink frequency band or the second uplink frequency band in response to a signal from the band suppression controller; and a downlink band suppression element controlled by the band suppression controller, wherein the downlink band suppression element is configured to apply an attenuation to selectively suppress either the first downlink frequency band or the second downlink frequency band in response to the signal from the band suppression controller.

Example <NUM> includes the method of example <NUM>, wherein the uplink band suppression element and the downlink band suppression element each further comprise: a first band pass filter; a second band pass filter; a matching attenuator having an insertion loss equivalent to an insertion loss of either the first band pass filter or the second band pass filter; and one or more suppression selection switches coupled to the first band pass filter, the second band pass filter, and the matching attenuator, wherein the band suppression controller is configured to control the one or more suppression selection switches to switch between selection of the first band pass filter, the second band pass filter, or the matching attenuator, in response to the signal from the band suppression controller.

Example <NUM> includes a band suppression module for a distributed antenna system, the module comprising: a band suppression controller; an uplink radio frequency band suppression element controlled by the band suppression controller, wherein the uplink band suppression element is configured to apply an attenuation to suppress a first downlink frequency band in response to a signal from the band suppression controller while passing a second downlink frequency band; and a downlink radio frequency band suppression element controlled by the band suppression controller, wherein the uplink band suppression element is configured to apply an attenuation to suppress the first downlink frequency band in response to the signal from the band suppression controller while passing a second uplink frequency band.

Example <NUM> includes the module of example <NUM>, wherein the band suppression controller comprises electronics responsive to a management signal received by the distributed antenna system, wherein the band suppression controller controls one or both of the uplink band suppression element and the downlink band suppression element in response to the management signal.

Example <NUM> includes the module of any of examples <NUM>-<NUM>, wherein the band suppression module further comprises a memory coupled to the band suppression controller, the memory storing a plurality of configuration setting; wherein the band suppression controller selectively reads a configuration setting from the memory to control the uplink band suppression element and the downlink band suppression element.

Example <NUM> includes the module of any of examples <NUM>-<NUM>, wherein the uplink band suppression element and the downlink band suppression element each further comprise: an RF network element; and at least one switchable load coupled to the RF network element; wherein the band suppression controller is configured to control application of the at least one switchable load to suppress one of the first uplink signal or the first downlink signal.

Example <NUM> includes the module of example <NUM>, wherein the RF network element comprises either a circulator or a hybrid coupler.

Example <NUM> includes the module of any of examples <NUM>-<NUM>, wherein the uplink band suppression element and the downlink band suppression element each further comprise: a band pass filter; a matching attenuator having an insertion loss equivalent to an insertion loss of the band pass filter; and one or more suppression selection switches coupled to the band pass filter and the matching attenuator, wherein the band suppression controller is configured to control the one or more suppression selection switches to toggle between the band pass filter and the matching attenuator.

Example <NUM> includes the module of any of examples <NUM>-<NUM>, wherein the uplink band suppression element and the downlink band suppression element each further comprise: a first band pass filter; a second band pass filter; a matching attenuator having an insertion loss equivalent to an insertion loss of either the first band pass filter or the second band pass filter; and one or more suppression selection switches coupled to the first band pass filter, the second band pass filter, and the matching attenuator, wherein the band suppression controller is configured to control the one or more suppression selection switches to switch between selection of the first band pass filter, the second band pass filter, or the matching attenuator, in response to the signal from the band suppression controller.

In various alternative embodiments, system and/or device elements, method steps, or example implementations described throughout this disclosure (such as any of the master units, remote antenna units, controllers, circuitry, band suppression module, control units or sub-parts thereof, for example) may be implemented at least in part using one or more computer systems, field programmable gate arrays (FPGAs), or similar devices comprising a processor coupled to a memory and executing code to realize those elements, processes, or examples, said code stored on a non-transient data storage device. Therefore other embodiments of the present disclosure may include elements comprising program instructions resident on computer readable media which when implemented by such computer systems, enable them to implement the embodiments described herein. As used herein, the term "computer readable media" refers to tangible memory storage devices having non-transient physical forms. Such non-transient physical forms may include computer memory devices, such as 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-permanent, or temporary memory storage system or device having a physical, tangible form. Program 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 Description Language (VHDL).

Claim 1:
A method for selectable band suppression for a distributed antenna system (<NUM>) comprising at least one master unit (<NUM>) and at least one remote antenna unit (<NUM>) that is communicatively coupled to the at least one master unit (<NUM>), the at least one remote antenna unit (<NUM>) carrying a remote downlink radio frequency signal comprising a first downlink frequency band and a second downlink frequency band, and a remote uplink radio frequency signal comprising a first uplink frequency band and a second uplink frequency band, the method comprising:
determining whether the distributed antenna system (<NUM>) is operating under a first status condition or a second status condition;
when the distributed antenna system (<NUM>) is determined to be operating under the first status condition, controlling at least one radio frequency, RF, band suppression element (<NUM>, <NUM>) to suppress the first downlink frequency band while passing the second downlink frequency band along a downlink signal path and to suppress the first uplink frequency band while passing the second uplink frequency band along an uplink signal path;
when the distributed antenna system (<NUM>) is determined to be operating under the second status condition, controlling the at least one RF band suppression element (<NUM>, <NUM>) to pass the first downlink frequency band and the second downlink frequency band along the downlink signal path and to pass the first uplink frequency band and the second uplink frequency band along the uplink signal path.