Patent Description:
Further cited prior art documents are <CIT> showing systems and methods for beacon detection infrastructures,<NPL>) and <NPL>.

The following presents a simplified summary of the disclosed subject matter in order to provide a basic understanding of some aspects of the disclosed subject matter. This summary is not an exhaustive overview of the disclosed subject matter. It is not intended to identify key or critical elements of the disclosed subject matter or to delineate the scope of the disclosed subject matter. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later. In some embodiments, a spectrum access system (SAS), a method, and a non-transitory computer readable storage medium according to the respective claims are provided.

The present disclosure is better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings.

The Federal Communication Commission (FCC) has begun offering bands of spectrum owned by federal entities for sharing with commercial operations. For example, newly issued FCC rules in <NUM> Code of Federal Regulations (CFR) Part <NUM> allows sharing of the <NUM>-<NUM> Citizens Broadband Radio Service (CBRS) between incumbents and other operators. The CBRS operates according to a tiered access architecture that distinguishes between incumbents, operators that have received a priority access license (PAL) consistent with <NUM> CFR §<NUM>, et seq. , and general authorized access (GAA) operators that are authorized to implement one or more base stations, wireless devices, or wireless access devices such as Citizens Broadband radio Service Devices (CBSDs) consistent with <NUM> CFR §<NUM>, et seq. Incumbents, PAL licensees, and GAA operators are required to request access from a spectrum access system (SAS), which allocates frequency bands to the operators, e.g., for CBRS within the <NUM>-<NUM> band. The SAS is responsible for managing or controlling different types of CBSDs in the CBRS frequency bands.

In current deployments, the CBSD are categorized as:.

The SAS allocates frequency bands to the CBSDs associated with the operators within particular geographical areas and, in some cases, during particular time intervals. The SAS determines whether incumbents are present within corresponding geographical areas using an environmental sensing capability (ESC) that performs incumbent detection, e.g., using radar to detect the presence of a Navy ship in a port.

The tiered access architecture provides priority access to incumbents, which include Grandfathered Wireless Broadband Licensees that are authorized to operate on a primary basis on frequencies designated in <NUM> CFR §<NUM>. When an incumbent is present in a geographical area, the incumbent is granted exclusive access to a portion of the CBRS spectrum within the geographic area. For example, if a Navy ship enters a port, communication systems on the ship are granted exclusive access to a <NUM>-<NUM> band within the <NUM>-<NUM> band. Operators that have received a PAL and GAA operators are required to vacate the band allocated to the ship. A PAL license grants exclusive access to a portion of the <NUM>-<NUM> band within a predetermined geographical area as long as no incumbents have been allocated an overlapping portion of the <NUM>-<NUM> band within the predetermined geographical area. The GAA operators are given access to a portion of the <NUM>-<NUM> band within a geographic area as long as no incumbents or PAL licensees have been allocated an overlapping portion in the same geographic area during a concurrent time interval. The GAA operators are also required to share the allocated portion of the <NUM>-<NUM> band if other GAA operators are allocated the same portion.

The FCC and the National Telecommunications and Information Administration (NTIA) define protection areas that give priority to incumbents or other base stations or users. Examples of protection areas include, but are not limited to, areas associated with incumbents in a Fixed Satellite System (FSS), a grandfathered wireless protection zone (GWPZ), a region associated with a grandfathered wireless broadband license (GWBL), a region associated with a priority access license (PAL), a region associated with an ESC, and dynamic protection areas (DPAs).

The FCC and the NTIA also define a set of DPAs along the east, west, and Gulf coasts of the United States. A DPA is a pre-defined local protection area that is activated or deactivated as necessary to protect Department of Defense (DOD) radar systems. All outdoor (Category B) CBSD within an activated DPA are required to stop transmission or reduce transmission to below a threshold transmit power. One or more ESC sensors deployed within a DPA detect the presence or absence of an incumbent. In some cases, an ESC cloud gathers information from a set of ESC sensors within a DPA and uses this information to detect incumbents. An ESC sensor (or cloud) transmits a report to the SAS for the DPA in response to the ESC sensor (or cloud) detecting the presence of an incumbent. The report includes information identifying the portion (e.g., <NUM>-<NUM>) of the total <NUM> CBRS spectrum that is impacted by the presence of the incumbent. In response to receiving the report, the SAS performs interference management using all the CBSDs within the DPA that are operating within the impacted frequency range. For example, the SAS can move the CBSD to a different channel or instruct the CBSD to operate with a lower transmit power to keep the interference level in compliance with FCC regulations. Lowering the transmit power reduces the transmission coverage area for the CBSD. A DPA can only be deactivated by an operational ESC sensor. Thus, the SAS and the ESC sensor (or cloud) maintain a constant heartbeat exchange to verify that an operational ESC sensor is present within the DPA. If there are no operational ESC sensors deployed within a DPA, the DPA must be activated throughout the entire <NUM> CBRS spectrum. Moreover, no outdoor CBSDs (Category B) can be deployed in a DPA without an ESC sensor.

Technicians are sent into the field to install CBSDs. For example, the FCC requires certified professional installers (CPI) to perform the installation of outdoor (Category B) CBSDs and indoor (Category A) CBSDs that are deployed outside at a height above <NUM> meters (m). The CPI is responsible for installing the CBSD and verifying that the CBSD is operating correctly by performing a series of tests including a power check to verify that the CBSD can power up, a registration check to verify that the CBSD successfully registered with the SAS, a grant check to verify that the CBSD received a grant from the SAS, a radio grant check to verify that the CBSD is authorized for communication on the granted channel, and a walk-through check to verify that user equipment are receiving data transmitted by the CBSD.

Private enterprise networks would like to use high-speed cellular access capabilities to support vertical market segments such as industrial automation in locations including nuclear power plants, prisons are fortresses in the Federal prison system, package delivery companies, windfarms, ports, mines, hospitals, and the like. High-speed cellular access typically offers more reliable and superior QoS in comparison to Wi-Fi networks. Until recently, such capabilities were not possible as the spectrum needed to run private cellular networks has been in the form of statically licensed spectrum owned by mobile network operators and could not be easily accessed on the sites of interest. With emergence of shared spectrum, where the spectrum owned and used by e.g., US Federal Entities, the issue of availability of spectrum for the vertical market segment is no longer a hurdle and the dependence on the licensed spectrum that is owned by the MNOs for deploying cellular network for private enterprises has been broken.

The CBRS band has thus opened-up the possibility of an innovation band for new small entrants such as the digital automation verticals to deploy their own private cellular (LTE/<NUM>) Enterprise Network without any need to acquire the LTE/<NUM> service from their regional wireless providers. Smaller entrants can therefore architect a private cellular (LTE/<NUM>) enterprise network that meets their own specific mission critical needs for service and coverage. However, data isolation and security are critical requirements in some vertical market segments including the Federal prison system. Data remains localized/isolated within the premises of the private enterprise network and should not traverse the MNO/MSO core network. This requirement alone obviates the use of an MNO/MSO provided enterprise network deployments for such vertical market segment deployment as it is not private in terms of data isolation/security as all data traverse the MNO/MSO core network.

The thick concrete walls such as used in underground subterranean structures and fortresses pose serious performance and coverage challenges for a Wi-Fi based enterprise network deployment solution. Thick prison walls not only impede Wi-Fi signals that implement a contention based MAC layer and a much lower UL transmit power allowance on the UE side compared to the cellular (LTE/<NUM>) technologies, but the need for ruggedized/robust radio units to be installed on prison walls due to prisoners' tendency to damage/scavenge components from indoor units makes deployment even more challenging using Wi-Fi with coverage holes and inferior QOS compared to cellular (<NUM>/<NUM>) private enterprise networks.

The availability of spectrum was the biggest impediment in deploying the cellular (LTE/<NUM>) private enterprise networks. The availability of the shared spectrum as described below removed this impediment. However, unlike licensed spectrum, the channel in shared spectrum may be taken away at any given time due to the appearance of the incumbent. Switching the CBSDs from one channel to another may take up to <NUM>-<NUM> minutes of down time for the connected UEs.

All CBSDs operating in the shared spectrum are always under the direct control of the SAS that performs shared spectrum channel management, allocation, and incumbent protection. This is ensured by periodic heartbeat message exchanges between the operational CBSDs that are deployed on the edge cloud networks and the SAS that resides on the regional cloud. The periodicity of the heartbeat messages is tuneable, e.g., a heartbeat is exchanged every <NUM> seconds. If for any reason the connectivity between the SAS and the CBSD is lost (break in backhaul link, natural disaster in a geographic location where the SAS regional cloud datacentre is located, or SAS under DDOS (Distributed Denial of Service Attack) etc, for a period exceeding <NUM> seconds, under the rules defined for the use of the shared spectrum, the CBSDs have to immediately cease operation in the shared spectrum to protect the incumbents irrespective of whether any incumbents are present in the geographic vicinity of the deployed edge network in which the CBSD is operating. WINNForum has defined the notion of Geo redundant SAS instances to tackle such a situation. In those scenarios if connectivity with the primary SAS is lost, the CBSDs of an edge cloud network may switch their connectivity to the secondary SAS that is hosted on a different geographic datacentre, and thus may not be impacted by any natural disaster or connectivity issues that the primary SAS may have been impacted with. However, doing this primary SAS to secondary SAS switching will incur a System down time of around <NUM>-<NUM> minutes.

<FIG> disclose embodiments of a method and apparatus for a private cellular (<NUM>/<NUM>) enterprise network solution that uses the shared spectrum for vertical market segments involving subterranean structures and fortresses with thick concrete walls such as the federal prison system. Data isolation/security within the premises is ensured with far superior coverage and QOS that the current Wi-Fi based networks may offer, so that the inmates/prisoners may be allowed to use tablets in their cells to contact loved ones by video calling. Such a use case assists in rehabilitating the inmates by providing them with a mechanism to be in touch with their loved ones including their young children more often daily. In another embodiment, the network may allow the Federal correctional facility to offer online educational/vocational training programmes using the tablets in their cells to pave the way for a smoother productive reintegration into the society upon their release from the correctional facility.

<FIG> is a block diagram of a communication system <NUM> according to some embodiments. The communication system <NUM> operates in accordance with the FCC rules set forth in <NUM> Code of Federal Regulations (CFR) Part <NUM>, which allows sharing of the <NUM>-<NUM> Citizens Broadband Radio Service (CBRS) between incumbents and other operators. However, some embodiments of the communication system <NUM> operate in accordance with other rules, standards, or protocols that support sharing of a frequency band between incumbents and other devices such that the frequency band is available for exclusive allocation to an incumbent device if the incumbent device is present in a geographic area. For example, if the communication system <NUM> is deployed (at least in part) proximate a port and a Navy ship such as an aircraft carrier <NUM> arrives in the port, devices in a geographic area proximate the port that are providing wireless connectivity in a portion of the frequency band allocated to the aircraft carrier <NUM> are required to vacate the portion of the frequency band to provide the aircraft carrier <NUM> with exclusive access to the frequency band within the geographic area.

The communication system <NUM> includes a regional cloud <NUM> that provides cloud-based support for a private enterprise network <NUM>. Some embodiments of the regional cloud <NUM> include one or more servers that are configured to provide operations and maintenance (O&M) management, a customer portal, network analytics, software management, and central security for the private enterprise network <NUM>. The regional cloud <NUM> also includes an SAS instance <NUM> to allocate frequency bands to operators, e.g., to the private enterprise network <NUM> for CBRS within the <NUM>-<NUM> band. The communication system <NUM> also includes another regional cloud <NUM> that includes an SAS instance <NUM>. In the illustrated embodiment, the regional clouds <NUM>, <NUM> are located at different geographic locations and are therefore used to provide georedundancy. For example, the SAS instance <NUM> can be selected as a primary SAS and the SAS instance <NUM> can be selected as a secondary, geo-redundant SAS. The SASs <NUM>, <NUM> communicate with each other over an SAS-SAS interfaces (not shown in <FIG> in the interest of clarity). If additional SAS instances are present in the communication system <NUM>, the SAS instances communicate with each other over corresponding SAS-SAS interfaces. The SASs <NUM>, <NUM> can serve multiple private enterprise networks, although a single private enterprise network <NUM> is shown in <FIG> in the interest of clarity.

The regional clouds <NUM>, <NUM> are configured via user interface portals to one or more external computers <NUM>, only one of which is shown in <FIG> in the interest of clarity. For example, the external computer <NUM> can provide a customer user interface portal for service management, a digital automation cloud management user interface portal, and an SAS user interface portal that is used to configure the SASs <NUM>, <NUM>.

The private enterprise network <NUM> includes an edge cloud <NUM> that communicates with the regional clouds <NUM>, <NUM> to support a plug-and-play deployment of the private enterprise network <NUM>. Some embodiments of the edge cloud <NUM> support auto configuration and self-service, industrial protocols, local connectivity with low latency, LTE-based communication and local security, high availability, and other optional applications for the private enterprise network <NUM>. In the illustrated embodiment, the edge cloud <NUM> implements a domain proxy <NUM> that provides managed access and policy control to a set of CBSDs <NUM>, <NUM>, <NUM> that are implemented using base stations, base station routers, mini-macrocells, microcells, indoor/outdoor picocells, femtocells, or other wireless devices or wireless access devices. As used herein, the term "base station" refers to any device that provides wireless connectivity in the private enterprise network <NUM>. Some embodiments of the base station operate as a CBSD, e.g., as either category A CBSD (Indoor), Category B CBSD (outdoor), or customer premises equipment (CPE). The CBSDs <NUM>, <NUM>, <NUM> are therefore referred to herein as the base stations <NUM>, <NUM>, <NUM> and collectively as "the base stations <NUM>-<NUM>. " Some embodiments of the domain proxy <NUM> are implemented in one of the regional clouds <NUM>, <NUM>.

The domain proxy <NUM> mediates between the SASs <NUM>, <NUM> and the base stations <NUM>-<NUM>. In order to utilize the shared spectrum, the base stations <NUM>-<NUM> transmit requests towards one of the SASs <NUM>, <NUM> to request allocation of a portion of a frequency band. The other one of the SASs <NUM>, <NUM> is used as a secondary SAS in case of a failure associated with the primary SAS. The requests include information identifying the portion of the frequency band such as one or more channels, a geographic area corresponding to a coverage area of the requesting base station, and, in some cases, a time interval that indicates when the requested portion of the frequency band is to be used for communication. In the illustrated embodiment, the coverage area of the base stations <NUM>-<NUM> corresponds to the area encompassed by the private enterprise network <NUM>. Some embodiments of the domain proxy <NUM> reduce the signal load between the domain proxy <NUM> and the SASs <NUM>, <NUM> by aggregating requests from multiple base stations <NUM>-<NUM> into a smaller number of messages that are transmitted from the domain proxy <NUM> to the SASs <NUM>, <NUM>. The base stations <NUM>-<NUM> provide wireless connectivity to corresponding user equipment <NUM>, <NUM>, <NUM> (collectively referred to herein as "the user equipment <NUM>-<NUM>") in response to the SASs <NUM>, <NUM> allocating portions of the frequency band to the base stations <NUM>-<NUM>.

The requests transmitted by the base stations <NUM>-<NUM> do not necessarily include the same information. Some embodiments of the requests from the base stations <NUM>-<NUM> include information indicating different portions of the frequency band, different geographic areas, or different time intervals. For example, the base stations <NUM>-<NUM> request portions of the frequency band for use in different time intervals if the private enterprise network <NUM> is deployed in a mine or prison and the base stations <NUM>-<NUM> are used to provide wireless connectivity within different locations that have different operating hours. The domain proxy <NUM> therefore manages the base stations <NUM>-<NUM> using separate (and potentially different) policies on a per-CBSD basis. In some embodiments, the domain proxy <NUM> accesses the policies for the base stations <NUM>-<NUM> in response to receiving a request from one of the base stations <NUM>-<NUM>. The domain proxy <NUM> determines whether the requesting base station from which the request is received is permitted to access the SAS instance <NUM> based on the policy, e.g., by comparing information in the policy to information in one or more mandatory fields of the request. The domain proxy <NUM> selectively provides the requests to the SASs <NUM>, <NUM> depending on whether the requesting base station is permitted to access the SASs <NUM>, <NUM>. If so, the request is transmitted to the SASs <NUM>, <NUM> or aggregated with other requests for transmission to the SASs <NUM>, <NUM>. Otherwise, the request is rejected.

As discussed herein, the FCC requires certified professional installers (CPI) to perform the installation of outdoor (Category B) CBSDs and indoor (Category A) CBSDs that are deployed outside at a height above <NUM> meters (m). A complete installation includes testing and verification of the newly installed base station (or CBSD) while the base station is authorized to transmit (and receive) signals over one or more channels. For example, the CPI performs testing and verification on the base station <NUM> in response to installing the base station <NUM>. In the illustrated embodiment, the SAS <NUM> (or, in other embodiments, the SAS <NUM>) receives a registration request from the base station <NUM> in response to the base station <NUM> being installed. The SAS <NUM> allocates to the base station <NUM> a channel in the shared spectrum and a transmission power to be used by the base station <NUM>. The SAS <NUM> transmits a test grant authorizing the base station <NUM> to transmit on the channel at the transmission power for a predetermined time interval such as <NUM> minutes or <NUM> minutes. The SAS <NUM> converts the test grant to a suspended grant following the predetermined time interval. In some cases, the SAS <NUM> receives the registration request from the base station <NUM> in response to the base station <NUM> being installed in the DPA <NUM>.

<FIG> is a block diagram of a network function virtualization (NFV) architecture <NUM> according to some embodiments. The NFV architecture <NUM> is used to implement some embodiments of the communication system <NUM> shown in <FIG>. The NFV architecture <NUM> includes hardware resources <NUM> including computing hardware <NUM> such as one or more processors or other processing units, storage hardware <NUM> such as one or more memories, and network hardware <NUM> such as one or more transmitters, receivers, or transceivers. A virtualization layer <NUM> provides an abstract representation of the hardware resources <NUM>. The abstract representation supported by the virtualization layer <NUM> can be managed using a virtualized infrastructure manager <NUM>, which is part of the NFV management and orchestration (M&O) module <NUM>. Some embodiments of the virtualized infrastructure manager <NUM> are configured to collect and forward performance measurements and events that may occur in the NFV architecture <NUM>. For example, performance measurements may be forwarded to an orchestrator (ORCH) <NUM> implemented in the NFV M&O <NUM>. The hardware resources <NUM> and the virtualization layer <NUM> may be used to implement virtual resources <NUM> including virtual computing <NUM>, virtual storage <NUM>, and virtual networking <NUM>.

Virtual networking functions (VNF1, VNF2, VNF3) run over the NFV infrastructure (e.g., the hardware resources <NUM>) and utilize the virtual resources <NUM>. For example, the virtual networking functions (VNF1, VNF2, VNF3) are implemented using virtual machines supported by the virtual computing resources <NUM>, virtual memory supported by the virtual storage resources <NUM>, or virtual networks supported by the virtual network resources <NUM>. Element management systems (EMS1, EMS2, EMS3) are responsible for managing the virtual networking functions (VNF1, VNF2, VNF3). For example, the element management systems (EMS1, EMS2, EMS3) may be responsible for fault and performance management. In some embodiments, each of the virtual networking functions (VNF1, VNF2, VNF3) is controlled by a corresponding VNF manager <NUM> that exchanges information and coordinates actions with the virtualized infrastructure manager <NUM> or the orchestrator <NUM>.

The NFV architecture <NUM> may include an operation support system (OSS)/business support system (BSS) <NUM>. The OSS/BSS <NUM> deals with network management including fault management using the OSS functionality. The OSS/BSS <NUM> also deals with customer and product management using the BSS functionality. Some embodiments of the NFV architecture <NUM> use a set of descriptors <NUM> for storing descriptions of services, virtual network functions, or infrastructure supported by the NFV architecture <NUM>. Information in the descriptors <NUM> may be updated or modified by the NFV M&O <NUM>.

The NFV architecture <NUM> can be used to implement network slices <NUM> that provide user plane or control plane functions. A network slice <NUM> is a complete logical network that provides communication services and network capabilities, which can vary from slice to slice. User equipment can concurrently access multiple network slices <NUM>. Some embodiments of user equipment provide Network Slice Selection Assistance Information (NSSAI) parameters to the network to assist in selection of a slice instance for the user equipment. A single NSSAI may lead to the selection of several network slices <NUM>. The NFV architecture <NUM> can also use device capabilities, subscription information and local operator policies to do the selection. An NSSAI is a collection of smaller components, Single-NSSAls (S-NSSAI), which each include a Slice Service Type (SST) and possibly a Slice Differentiator (SD). Slice service type refers to an expected network behavior in terms of features and services (e.g., specialized for broadband or massive loT), while the slice differentiator can help selecting among several network slice instances of the same type, e.g. to isolate traffic related to different services into different network slices <NUM>.

<FIG> is a block diagram illustrating an allocation <NUM> of frequency bands and an access priority <NUM> for incumbents, licensed users, and general access users according to some embodiments. The allocation <NUM> and the access priorities <NUM> are used to determine whether CBSDs such as the base stations <NUM>-<NUM> shown in <FIG> are given permission to establish a wireless communication links in portions of the frequency band. The frequency band extends from <NUM> to <NUM> and therefore corresponds to the spectrum allocated for CBRS. An SAS such as one of the SAS instances <NUM>, <NUM> shown in <FIG> allocates portions of the frequency band to devices for providing wireless connectivity within a geographic area. For example, the SAS can allocate <NUM>-<NUM> portions of the frequency band to different devices for use as communication channels.

Portions of the frequency band are allocated to incumbent federal radio location devices, such as Navy ships, from the block <NUM>, which corresponds to all the frequencies in the available frequency band. Portions of the frequency band are allocated to incumbent FSS receive-only earth stations from the block <NUM>. Portions of the frequency band are allocated to grandfathered incumbent wireless broadband services from the block <NUM>. As discussed herein, the portions of the frequency band are allocated from the blocks <NUM>, <NUM>, <NUM> for exclusive use by the incumbent.

Operators that have received a priority access license (PAL) consistent with <NUM> CFR §<NUM>, et seq. are able to request allocation of portions of the frequency band in the block <NUM>. The portion of the frequency band that is allocated to an operator holding a PAL is available for exclusive use by the operator in the absence of any incumbents in an overlapping frequency band and geographic area. For example, the SAS can allocate a PAL channel in any portion of the lower <NUM> of the CBRS band as long as it is not pre-empted by the presence of an incumbent. Portions of the frequency band within the block <NUM> are available for allocation to general authorized access (GAA) operators that are authorized to implement one or more CBSDs consistent with <NUM> CFR §<NUM>, et seq. The GAA operators provide wireless connectivity in the allocated portion in the absence of any incumbents or PAL licensees on an overlapping frequency band and geographic area. The GAA operators are also required to share the allocated portion with other GAA operators, if present. Portions of the frequency band within the block <NUM> are available to other users according to protocols defined by the Third Generation Partnership Project (3GPP).

The access priority <NUM> indicates that incumbents have the highest priority level <NUM>. Incumbents are therefore always granted exclusive access to a request to portion of the frequency band within a corresponding geographic area. Lower priority operators are required to vacate the portion of the frequency band allocated to the incumbents within the geographic area. The access priority <NUM> indicates that PAL licensees have the next highest priority level <NUM>, which indicates that PAL licensees receive exclusive access to an allocated portion of the frequency band in the absence of any incumbents. The PAL licensees are also entitled to protection from other PAL licensees within defined temporal, geographic, and frequency limits of their PAL. The GAA operators (and, in some cases, operators using other 3GPP protocols) received the lowest priority level <NUM>. The GAA operators are therefore required to vacate portions of the frequency band that overlap with portions of the frequency band allocated to either incumbents or PAL licensees within an overlapping geographic area.

<FIG> is a block diagram of a communication system <NUM> that implements tiered spectrum access according to some embodiments. In the illustrated embodiment, the communication system <NUM> implements tiered spectrum access in the <NUM>-<NUM> CBRS band via a WInnForum architecture. The communication system <NUM> includes an SAS instance <NUM> that performs operations including incumbent interference determination and channel assignment, e.g., for CBRS channels shown in <FIG>. In the illustrated embodiment, the SAS instance <NUM> is selected as a primary SAS. An FCC database <NUM> stores a table of frequency allocations that indicate frequencies allocated to incumbent users and PAL licensees. An informing incumbent <NUM> provides information indicating the presence of the incumbent (e.g., a coverage area associated with the incumbent, and allocated frequency range, a time interval, and the like) to the SAS instance <NUM>. The SAS instance <NUM> allocates other portions of the frequency range to provide exclusive access to the informing incumbent <NUM> within the coverage area. An environmental sensing capability (ESC) <NUM> performs incumbent detection to identify incumbents using a portion of a frequency range within the geographic area, e.g., using a radar sensing apparatus <NUM>. Some embodiments of the SAS instance <NUM> are connected to other SAS instance <NUM>, e.g., a secondary SAS instance <NUM>. The primary and secondary SAS instance <NUM>, <NUM> are connected via corresponding interfaces so that the SAS instance <NUM>, <NUM> coordinate allocation of portions of the frequency range in geographic areas or time intervals.

A domain proxy <NUM> mediates communication between the SAS instance <NUM> and one or more CBSDs <NUM>, <NUM>, <NUM> via corresponding interfaces. The domain proxy <NUM> receives channel access requests from the CBSDs <NUM>, <NUM>, <NUM> and verifies that the CBSDs <NUM>, <NUM>, <NUM> are permitted to request channel allocations from the SAS instance <NUM>. The domain proxy <NUM> forwards requests from the permitted CBSDs <NUM>, <NUM>, <NUM> to the SAS instance <NUM>. In some embodiments, the domain proxy <NUM> aggregates the requests from the permitted CBSDs <NUM>, <NUM>, <NUM> before providing the aggregated request to the SAS instance <NUM>. The domain proxy <NUM> aggregates requests based on an aggregation function that is a combination of two parameters: (<NUM>) a maximum number of requests that can be aggregated into a single message and (<NUM>) a maximum wait duration for arrival of requests that are to be aggregated into a single message. For example, if the wait duration is set to <NUM> and the maximum number of requests is <NUM>, the domain proxy accumulates receive requests until the wait duration reaches <NUM> or the number of accumulated requests which is <NUM>, whichever comes first. If only a single request arrives within the <NUM> wait duration, the "aggregated" message includes a single request.

Thus, from the perspective of the SAS instance <NUM>, the domain proxy <NUM> operates as a single entity that hides or abstracts presence of the multiple CBSDs <NUM>, <NUM>, <NUM> and conveys communications between the SAS instance <NUM> and the CBSDs <NUM>, <NUM>, <NUM>. One or more CBSD <NUM> (only one shown in the interest of clarity) are connected directly to the SAS instance <NUM> and can therefore transmit channel access requests directly to the SAS instance <NUM>.

<FIG> is a block diagram of a communication system <NUM> that implements a spectrum controller cloud <NUM> to support deployment of private enterprise networks in a shared spectrum according to some embodiments. The spectrum controller cloud <NUM> instantiates multiple instances of domain proxies <NUM> that support one or more private enterprise networks. The spectrum controller cloud <NUM> also instantiates multiple SAS instances <NUM> that support one or more private enterprise networks. Although not shown in <FIG>, the SAS instances <NUM> can be connected to other SAS instances, e.g., in other clouds, via corresponding interfaces. Coexistence management (CXM) functions <NUM> and spectrum analytics (SA) functions <NUM> are also instantiated in the spectrum controller cloud <NUM>.

One or more ESC instances <NUM> are instantiated and used to detect the presence of incumbents. In the illustrated embodiment, standalone ESC sensors <NUM>, <NUM>, <NUM> (collectively referred to herein as "the sensors <NUM>-<NUM>") are used to monitor a frequency band to detect the presence of an incumbent such as a Navy ship. The ESC instances <NUM> notify the corresponding instance of the SAS instance <NUM> in response to detecting the presence of an incumbent in a corresponding geographic area. The SAS instance <NUM> is then able to instruct non-incumbent devices that serve the geographic area to vacate portions of the spectrum overlapping with the spectrum allocated to the incumbent, e.g., by defining a DPA. As discussed herein, some embodiments of the SAS instance <NUM> register with an ESC cloud to provide ESC services for the SAS instance <NUM> (or an SAS administrator for the SAS instance <NUM>). Thus, although <FIG> depicts the SAS instance <NUM> and the ESC instances <NUM> as part of the same spectrum controller cloud <NUM>, the ESC instances <NUM> are not necessarily deployed in the same location or controlled by the same vendor or provider as the SAS instances <NUM>.

One or more base stations <NUM>, <NUM>, <NUM> (collectively referred to herein as "the base stations <NUM>-<NUM>") in a private enterprise network communicate with one or more of the domain proxies <NUM> and the SAS instances <NUM> via an evolved packet core (EPC) cloud <NUM>. The base stations <NUM>-<NUM> have different operating characteristics. For example, the base station <NUM> operates according to a PAL in the <NUM> frequency band, the base station <NUM> operates according to GAA in the <NUM> frequency band, and the base station <NUM> operates according to a PAL and GAA in the <NUM> frequency band. The base stations <NUM>-<NUM> are configured as Category A (indoor operation with a maximum power of <NUM> dBm), Category B (outdoor operation with a maximum power of <NUM> dBm), or CPE. However, in other embodiments, one or more of the base stations <NUM>-<NUM> are configured as either Category A, Category B, or CPE. The EPC cloud <NUM> provides functionality including LTE EPC operation support system (OSS) functionality, analytics such as traffic analytics used to determine latencies, and the like.

The spectrum controller cloud <NUM> also includes a policy control and rules function (PCRF) <NUM> that creates policy rules and makes policy decisions for network subscribers in real-time. The PCRF <NUM> supports service data flow detection, policy enforcement, and flow-based charging. Some embodiments of the PCRF <NUM> determine the policy and charging records for SAS service to the CBRS RAN providers who sign up to receive the SAS service. Policies created or accessed by the PCRF <NUM> for network subscribers are stored in a corresponding database <NUM> in records associated with the different subscribers.

<FIG> is a block diagram of communication system <NUM> including interfaces between CBSDs and an SAS instance <NUM> according to some embodiments. The SAS instance <NUM> is used to implement some embodiments of the SAS instance <NUM> shown in <FIG>, the SAS instance <NUM>, <NUM> shown in <FIG>, and the instances of the SAS instance <NUM> shown in <FIG>. The SAS instance <NUM> includes ports <NUM>, <NUM>, <NUM>, <NUM>, <NUM> (collectively referred to herein as "the ports <NUM>-<NUM>") that provide access to the SAS instance <NUM>.

An interface <NUM> supports communication between the SAS instance <NUM> and CBSDs <NUM>, <NUM> via a network such as the Internet <NUM> and the ports <NUM>, <NUM>. The CBSD <NUM> is connected directly to the SAS instance <NUM> via the interface <NUM>. The CBSD <NUM> is connected to the SAS instance <NUM> via a domain proxy <NUM> that is connected to the SAS instance <NUM> by the interface <NUM>. The domain proxy <NUM> corresponds to some embodiments of the domain proxy <NUM> shown in <FIG>, the domain proxy <NUM> shown in <FIG>, and the instances of the domain proxy <NUM> shown in <FIG>. An interface <NUM> supports communication between the SAS instance <NUM> and one or more other SAS instances <NUM> (only one shown in <FIG> in the interest of clarity) via a network such as the Internet <NUM> and the port <NUM>. The SAS instance <NUM> can be owned and operated by other providers. An interface <NUM> supports communication between the SAS instance <NUM> and one or more other networks <NUM> (only one shown in <FIG> in the interest of clarity) via the port <NUM>. An interface <NUM> supports communication between the SAS instance <NUM> and an ESC cloud <NUM> that provides ESC services to the SAS instance <NUM>, e.g., within a DPA associated with the SAS instance <NUM>.

<FIG> is a map <NUM> of the borders of the United States that illustrates a set of DPAs defined at different geographic locations within the United States according to some embodiments. The DPAs <NUM> (only one indicated by a reference numeral in the interest of clarity) are typically, but not necessarily, defined near coastal regions to protect incumbents such as Navy ships. A DPA <NUM> can only be deactivated by an operational ESC sensor and consequently any communication system that uses the CBRS spectrum must include an ESC sensor, such as the ESC sensor <NUM>, to have full access to the CBRS spectrum. Each ESC sensor <NUM> is also required to maintain an exchange of heartbeat messages with the ESC cloud that in turn connects with one or more SAS instances to verify that the ESC sensors <NUM> within the DPA <NUM> are operational. If there are no operational ESC sensors deployed within a DPA, FCC rules require that the DPA must be activated throughout the entire <NUM> CBRS spectrum. Moreover, no outdoor CBSDs (Category B) can be deployed in a DPA <NUM> without an ESC sensor <NUM> in the DPA <NUM>.

<FIG> is a block diagram of a communication system <NUM> that provides wireless connectivity within a structure or location that has a large propagation loss from interior to exterior according to some embodiments. In the illustrated embodiment, the communication system <NUM> provides wireless connectivity to the interior of a structure <NUM> that is separated from an exterior environment by walls, rock, earth, or other materials that engender a significant propagation loss for signals that are transmitted within a predetermined frequency range such as radiofrequency signals or millimeter wave signals. Examples of structures <NUM> include, but are not limited to, prisons, fortresses, bunkers, minds, or other subterranean structures.

An edge cloud network <NUM> is implemented within or proximate to the structure <NUM>, e.g., using one or more processors, memories, or transceivers. In the illustrated embodiment, the edge cloud network <NUM> supports services including auto configuration, self-service, industrial protocols, local connectivity and low latency, LTE, local security, and high availability, as well as other applications. The edge cloud network <NUM> implements a domain proxy (DP) <NUM> that provides managed access and policy control to one or more CBSDs <NUM> (only one shown in <FIG> in the interest of clarity) that are implemented using base stations, base station routers, mini-macrocells, microcells, indoor/outdoor picocells, femtocells, or other wireless devices or wireless access devices. The CBSD <NUM> provides wireless connectivity to user equipment <NUM>, <NUM>, <NUM>, <NUM> (collectively referred to herein as "the user equipment <NUM>-<NUM>") within the structure <NUM>. The domain proxy <NUM> residing on the edge cloud network <NUM> may support CBSDs both category A (indoor), and category B (outdoor) that directly support the SAS-CBSD WINNFORUM protocol stack to be controlled by the SAS <NUM> for operation in the CBRS band. In the illustrated embodiment, the edge cloud network <NUM> is localized to the premises of the structure <NUM>.

The edge cloud network <NUM> is connected to a regional cloud network <NUM> that that supports functionality including O&M management, a customer portal, data analytics, software management, central security, as well as spectrum access systems (SAS) in some cases. In the illustrated embodiment, the edge cloud network <NUM> connects with the NDAC regional cloud network <NUM> to download the software generic including the core network and configuration information. Once operational, the edge cloud network <NUM> operates as fully functional cellular enterprise network. For improved performance and high network availability/reliability use case scenarios, the domain proxy <NUM> can be implemented as an integral part of the edge cloud infrastructure in the overall NDAC architecture to unlock the use of the shared spectrum. The Regional SAS communicates with an ESC cloud service to enable the use of the lower <NUM> of the CBRS shared spectrum along the U. S coastline in areas that are designated as Dynamic Protection Area (DPA). The regional cloud network <NUM> is accessed via portals implemented on one or more access devices <NUM>. Examples of the portals include, but are not limited to, a customer portal for service management, an NDAC management portal, and an NSC SAS portal. In the illustrated embodiment, the regional cloud network <NUM> is connected to an SAS <NUM>.

Instead of assuming a conventional path loss through the structure <NUM>, such as a <NUM> dBm path loss, the edge cloud network <NUM> and the CBSD <NUM> are configured to provide wireless connectivity based on a measured path loss due to propagation of signals from the interior of the structure <NUM> to the exterior of the structure <NUM>. In the illustrated embodiment, a measurement device <NUM> measures a signal strength of a signal <NUM> that is generated by the CBSD <NUM> and transmitted from the interior of the structure <NUM> to the measurement device <NUM>. The measurement device <NUM> determines a path loss for the signal <NUM>, e.g., based on a known or predetermined transmission power of the CBSD <NUM> and a received signal strength indicator that is measured at the measurement device <NUM>. Information <NUM> indicating the path loss or propagation loss of the signal <NUM> is provided to the SAS <NUM>.

The SAS <NUM> includes a transceiver that receives the information <NUM> indicating a path loss from an interior location of the structure <NUM> to an exterior location in response to the CBSD <NUM> being installed at the interior location of the structure <NUM>. The SAS <NUM> also includes a processor to determine an aggregate interference level for an incumbent proximate the exterior location based on the path loss. The SAS <NUM> then allocates one or more channels to the CBSD <NUM> based on the aggregate interference level. Due to the relatively high path loss from the interior to the exterior of the structure <NUM>, the SAS <NUM> can allocate or permit the CBSD <NUM> transmit at a higher power level than would be permitted based on the conventional assumption of a <NUM> dBm path loss, e.g., the CBSD <NUM> can be permitted to transmit at the maximum power level of <NUM> dBm.

<FIG> is a block diagram illustrating a spectrum allocation <NUM> according to some embodiments. A private enterprise network <NUM> aggregates different portions of spectrum including a licensed spectrum <NUM>, a shared spectrum <NUM>, and an unlicensed spectrum <NUM>. In the illustrated embodiment, the licensed spectrum <NUM> includes a sub-<NUM> licensed spectrum <NUM>, the shared spectrum <NUM> includes the <NUM> CBRS band <NUM>, and the unlicensed spectrum <NUM> includes the <NUM> CBRS band <NUM>.

<FIG> is a block diagram of a communication system <NUM> to reduce or eliminate radio access network service downtime according to some embodiments. The communication system <NUM> includes the regional cloud networks <NUM>, <NUM>, <NUM>, which are connected to a private enterprise network <NUM>. In the illustrated embodiment, the private enterprise network <NUM> includes an edge cloud network <NUM> (which implements a domain proxy, as discussed herein) and one or more CBSD including a picocell <NUM>, a microcell <NUM>, and a macrocell <NUM>.

The CBSDs <NUM>, <NUM>, <NUM> in indoor environments that are shielded from the external world by high path loss interfering objects, such as thick concrete walls, are nevertheless subject to the same usage constraints in DPA as CBSDs that create more interference over a wider area. The thick concrete walls such as used in underground subterranean structures and fortresses (such as the Federal prison system) pose serious performance and coverage challenges for a Wi-Fi based enterprise network deployment solution. Thick prison walls not only impede Wi-Fi signals that has contention based MAC layer and a much lower UL transmit power allowance on the UE side compared to the cellular (LTE/<NUM>) technologies, but the need to install ruggedized/robust radio units on prison walls due to prisoners' tendency to damage/scavenge components from indoor units makes deployment even more challenging using Wi-Fi with coverage holes and inferior QOS compared to cellular (<NUM>/<NUM>) private enterprise networks.

The CBSDs <NUM>, <NUM>, <NUM> can therefore be implemented as ruggedized/robust radio units. By mounting the ruggedized/robust LTE/<NUM> radio units <NUM>, <NUM>, <NUM> on prison walls, the communication system <NUM> can provide superior QOS and coverage solution compared to a conventional Wi-Fi system. In a prison setting, this allows the inmates to use a ruggedized tablet in their cell for video calling their loved ones more often daily saving them the family members the ignominy of travelling to the correctional/prison facility for a visit. The ruggedized/robust LTE/<NUM> radio units <NUM>, <NUM>, <NUM> also provide the Federal correctional facility with the ability to offer online educational/vocational training programs to the inmates using the tablets in their cells to pave the way for a smoother productive reintegration into the society upon their release from the correctional facility.

The domain proxy on the edge cloud network <NUM> of the private cellular enterprise network <NUM> contains policy control features that enable the facility owners to define a policy per CBSD basis that determines the hours of operations of the CBSDs within a facility.

As discussed herein, the current CBRS standards as defined by the WINNF specification forces the SAS to add <NUM> dB to the computed loss irrespective of the building structure (class vs thick concrete walls, or subterranean etc) to account for attenuation due to building (penetration) loss for all CBSDS that are deployed indoors. The implication is that if the deployment facility falls in proximity to any type of incumbent, the SAS may perform incumbent protection and not grant the full <NUM> dBm Tx power to the indoor CBSDs <NUM>, <NUM>, <NUM> even though the building structure may be of thick concrete that will prevent any signals from the indoor CBSD <NUM>, <NUM>, <NUM> to be completely localized within the facility (such as subterranean structures, mines, fortresses including prison system, nuclear power plant etc). the lowered Tx power to the indoor CBSD would result in coverage loss that may result in coverage holes, and below par QOS compared to the deployment plans.

At least in part to address these drawbacks in the conventional practice, the penetration loss is measured and provided to the corresponding SAS, which uses the information for allocation, incumbent detection, and selectively disabling CBSDs <NUM>, <NUM>, <NUM> in the presence of an incumbent, as discussed herein. In some embodiments, a Certified Professional Installer (CPI) determines the actual observed signal strength outside the facility from the deployed indoor CBSDs <NUM>, <NUM>, <NUM> while transmitting at max allowed indoor Tx power level of <NUM> dBm. This information is then fed to the SAS that will use the accurate calculated value of path loss for the indoor CBSDs <NUM>, <NUM>, <NUM> in terms of computing the overall aggregate interference level to the nearby incumbent. This would result in SAS allocating a channel for indoor CBSDs <NUM>, <NUM>, <NUM> in these facilities where the CBSD signal never reaches outside the facility, with full allowed Tx power limit of <NUM> dBm as opposed to some lower Tx power level it would have allowed if it had taken the standards defined universal <NUM> dB penetration loss for indoor CBSDs <NUM>, <NUM>, <NUM> irrespective of the facility structure type.

<FIG> is a block diagram of a communication system <NUM> including an edge cloud <NUM> according to some embodiments. The edge cloud <NUM> is used to provide data security and isolation. The edge cloud <NUM> is therefore connected to a regional cloud network <NUM> via a firewall <NUM> or other secure access pathway. The edge cloud <NUM> also includes edge servers <NUM>, <NUM>, <NUM> that are connected to CBSD <NUM>, <NUM>, <NUM> that provide wireless connectivity. The edge cloud <NUM> also supports containers <NUM>, <NUM>, <NUM> for connectivity and selected digital automation enabler such as positioning, drones, push-to-talk, domain proxy, and third-party applications that are running locally on the edge cloud <NUM>. The edge cloud further supports a customer IP network <NUM>.

Customer network traffic is routed inside the customer network according to their IT security requirements, e.g., via the customer IP network <NUM>, which differentiates the communication system <NUM> from conventional NDAC solutions and the functionality provided by other MNO/MSOs to vertical market segment in terms of data protection and isolation. In the conventional case, data from all customer deployments traverses a core network, thereby leaving the customer premises. In contrast, in the illustrated embodiment, data remain localized to the customer edge network/premises that has a local EPC core running on the edge cloud network <NUM>. The NDAC is used to configure the edge cloud network <NUM> for providing the data security and isolation.

In some embodiments, calls such as <NUM> emergency voice over Internet protocol (VoIP) calls are provided in a manner that prevents interruption in the service provided by CBSDs deployed in DBAs. Anytime the private cellular enterprise network employs VoIP features (e.g. in a mine etc) preventing interruption of emergency calls becomes critical as unlike the MNO cellular network the private cellular enterpriser network has no access to licensed spectrum and therefore cannot use carrier aggregation features to continue the VoIP session active if the shared spectrum channel is suddenly taken away by the SAS to protect the incumbent.

The channels allocated to a CBSD that is deployed in a facility in a DPA along the U. coastline may be dynamically affected and taken away by the sudden appearance of the Federal incumbent (e.g., a naval cruiser). The ESC sensors that are deployed in the DPA notify the SAS of the incumbent presence and the amount of channel frequency in the lower <NUM> of the CBRS band that is impacted by it. As per the CBRS rules, the SAS must first and foremost protect the federal incumbent and vacate within <NUM> seconds of detecting the incumbent presence, all other users (CBSDs) if they happen to be operating within the impacted frequency band. The SAS first deauthorizes the current channel grant to the CBSD in the periodic heartbeat message that forces the CBSD to shut down its operation on its previously granted channel impacting all active call sessions that may be on-going including <NUM> emergency calls. The SAS then attempts to compute a backup operating channel for the CBSDs to operate and provide that information to the CBSDs in response to subsequent Spectrum Inquiry message sent by the CBSD. If another valid channel is found and reported back to the CBSD for operation, the cellular service in the impacted geographic area may then resume. This entire channel switching operation may take several minutes and will have serious consequence for an on-going emergency call that will get dropped during this channel switching operation as the enterprise network may not have another carrier to handover the emergency call during this channel switching process.

In some embodiments, emergency call continuation is ensured in a geographic enterprise cellular coverage area that falls within the DPA along the U. S coastline (east, west, and gulf coast). Upon the sudden appearance/detection of an incumbent (naval radar) in a DPA on the channels that were previously allocated by the SAS to a CBSD that is anchoring the <NUM> emergency call, the <NUM> emergency call will not get dropped while the SAS, in an attempt to protect the tier-<NUM> naval incumbent, revokes the current channel grant to the CBSD and forces the CBSD to switch to an alternate channel, a process that requires shutting down the current cellular carrier on the first channel frequency, and then bringing it up on the alternate second channel frequency. Dropping the <NUM> emergency call in the above-mentioned scenario, potentially leads to not only a bad outcome but could also result in liabilities for the CBRS network operator that deploys VoLTE service using the shared spectrum.

To address this problem and ensure emergency call continuation, dual (or multiple) carrier CBSDs are allocated to or more channels (acting as two logical CBSDs) to support the emergency call. The amount of spectrum that is typically impacted by the sudden appearance of the naval cruiser along the coastline is around <NUM>. The Domain Proxy on the Enterprise edge cloud will have policy control and management capabilities (an add-on feature of NDAC-NSC CBRS architecture solution). The DP will have a policy for emergency call continuation support that will ensure that the two carriers (e.g., the two logical CBSDs) on each physical deployed dual carrier eNB in the enterprise cellular network are spatially separated so that a single incumbent does not result in disabling both channels. For example, the channels allocated to the CBSD for the emergency call can be spatially separated by at least <NUM>. Thus, the CBSD1 operates using CBRS channel f1, and CBSD2 operates with a different CBRS channel f2, which ensures that both the carriers are not simultaneously (or concurrently) impacted by the sudden appearance of the incumbent. Since the Tx power, and antenna characteristic will be same for both the carriers on the same physical eNB, the cellular coverage area for the two carriers f1, and f2 will most likely be identical.

Since the Domain proxy receives all traffic to/from the CBSDs to the SAS, it will intercept the Spectrum grant request from the CBSDs and evaluate to see that the grant request for the two carriers of each physical eNB (two logical CBSDs, one for each carrier) are as spatially apart as possible. If DP determines that not enough frequency separation is requested by the two logical CBSDs on the same physical eNB, the DP rejects the grant request without forwarding it to the SAS for one of them, forcing the impacted CBSD to choose a different channel f. The logical CBSD whose previous channel grant was rejected may then choose another channel from the Spectrum Inquiry response, and DP using its intelligence will ensure that it will only let the grant request pass through to the SAS if it meets the emergency call continuation policy criteria.

Assuming the emergency call happens to be on a carrier f1 in the above example, and if the incumbent suddenly appears in the DPA, and channel f1 is taken away to protect the incumbent, the SAS forces the CBSD to shut down its operation on channel f1. Due to the overlapping cell coverage area between f1, and f2, when carrier f1 is powered down to protect the incumbent, all call sessions including the emergency call session on f1 will then automatically get handoff to carrier f2 using standard LTE/<NUM> call/session handover process. This will thus ensure that while protecting the incumbent within the DPA there is no outage is continuing to support the <NUM> emergency call that may be dealing with some life-threatening situation.

In some embodiments, the architecture disclosed herein supports mission control for Internet-of-things (IoT) devices. Several wireless IOT devices and sensors (smoke and radiation detectors, wireless camera) are connected to a private cellular enterprise network using LTE eNBs or <NUM> gNb. The <NUM> system provides the low latency air interface for controlling mission control IOT devices and sensors such as deployed in Nuclear power plants etc while the large bandwidth makes supporting the wireless video surveillance camera with Al machine learning based feature detection capability, a reality.

<FIG> is a flow diagram of a method <NUM> of configuring a CBSD based on a measured path loss according to some embodiments. At block <NUM>, an indoor CBSD is operated at a predetermined transmission power level such as a maximum transmission power for the CBSD. At block <NUM>, a signal is received from the indoor CBSD is measured at a location external to a structure that includes the indoor CBSD. A signal strength of the received signal is measured at the external location. A measured path loss is determined by comparing the received signal strength to the known/predetermined transmission power. At block <NUM>, an indication of the measured path loss from the internal to the external location is provided to the SAS. At block <NUM>, the SAS determines an aggregate interference level to an incumbent based on the measured path loss or other indication of the received signal strength. At block <NUM>, the SAS allocates one or more channels and corresponding power levels to the CBSD based on the aggregate interference level.

As discussed herein, the current CBRS standards as defined by the WINNF specification forces the SAS to add <NUM> dB to the computed loss irrespective of the building structure (class vs thick concrete walls, sub terranean structures or enclosures, and the like) to account for attenuation due to penetration loss for all CBSDs that are deployed within the structure. Consequently, if the deployment facility falls in proximity to any type of incumbent, the SAS may perform incumbent protection and not grant the full <NUM> dBm Tx power to the indoor CBSDs even though the building structure may be thick enough to prevent any signals from the indoor CBSD from leaking out of the structure. The CBSD signals would therefore be substantially localized within the facility (such as sub terranean structures, mines, fortresses including prison system, nuclear power plant, and the like). The reduction in the Tx power allocated to the indoor CBSD would cause coverage loss that may result in coverage holes and below par QOS compared to the deployment plans.

To address this drawback in the conventional practice, a Certified Professional Installer (CPI) determines the actual observed signal strength outside the facility from the deployed indoor CBSDs while transmitting at max allowed indoor Tx power level of <NUM> dBm. This information is then fed to the SAS, which uses the accurate calculated value of path loss for the indoor CBSDs to compute the overall aggregate interference level to the nearby incumbent. The SAS allocates the full allowed Tx power limit of <NUM> dBm to one or more channels for indoor CBSDs operating in these facilities if the penetration loss limits the signal strength of the CBSD signal outside the facility to a value below a threshold. This power allocation can be significantly higher than the Tx power level that the SAS would have allocated if it had used the standards-defined universal <NUM> dB penetration loss for indoor CBSDs irrespective of the facility structure type.

<FIG> is a flow diagram of a method <NUM> of allocating widely spaced channels to support emergency calling in a DPA according to some embodiments. At block <NUM>, an SAS receives a request to allocated to channels to a CBSD. The two channels include a primary channel and a secondary channel that is used as a backup in the event that an emergency call on the primary channel is disrupted by rival of an incumbent. At decision block <NUM>, the SAS determines whether the frequency spacing of the two channels is sufficient to ensure that at least one of the two channels is available when an incumbent is present. If the spacing between the two channels is sufficiently wide, the method <NUM> flows to the block <NUM> and the SAS allocates the two channels. If the spacing between the two channels is not sufficiently wide, the method <NUM> flows to the block <NUM> and the SAS denies the requested allocation of the two channels. The method <NUM> then flows back to the block <NUM> so that the CBSD has an opportunity to request a different pair of channels.

<FIG> is a flow diagram of a method <NUM> of selectively handing off an emergency call in response to arrival of an incumbent according to some embodiments. At block <NUM>, an SAS allocates two channels to a CBSD to provide redundancy in the event that an incumbent arrives and disables one of the channels during an emergency call. In some embodiments, the SAS allocates the two channels according to the method <NUM> shown in <FIG>. At block <NUM>, an emergency call is placed by a user via the CBSD on one of the allocated channels. At block <NUM>, an ESC system monitors the channels to detect arrival of an incumbent. At decision block <NUM>, the ESC system determines whether an arriving incumbent has been detected. As long as no incumbent has been detected, the emergency call and monitoring continue at block <NUM>, <NUM>. If an incumbent is detected by the ESC system, the method <NUM> flows to the block <NUM> and the emergency call is handed off to the second channel allocated to the CBSD.

Claim 1:
A spectrum access system, SAS, (<NUM>) comprising:
a transceiver configured to receive (<NUM>) information (<NUM>) indicating a path loss from an interior location of a structure (<NUM>) to an exterior location in response to a first base station (<NUM>) being installed at the interior location;
a processor configured to determine (<NUM>) an aggregate interference level for an incumbent proximate the exterior location based on the path loss and to allocate (<NUM>) at least one channel to the first base station (<NUM>) based on the aggregate interference level,
characterized in that
the processor is configured to allocate two carriers to the at least one channel, wherein the two carriers are separated by a predetermined bandwidth associated with the incumbent so that an occurrence of the incumbent does not impact both carriers simultaneously.