CBRS BAND

RELATED APPLICATIONS

[0001] The application claims the benefits of priority of U.S. Provisional Patent Application No. 62/848,134, entitled“A clustering method and node for assigning TDD configuration in CBRS band” and filed at the United States Patent and Trademark Office (USPTO) on May 15, 2019, the content of which is incorporated herein by reference. The application also claims the benefits of priority of US Provisional Patent Application No. 62/857,541, entitled“Generalized clustering for TDD configuration assignment in CBRS” and filed at the USPTO on June 5, 2019, the content of which is incorporated herein by reference.

TECHNICAL FIELD

[0002] The present description generally relates to wireless communication systems and specifically to methods and apparatus for coexistence management in shared spectrum scenarios.

BACKGROUND

[0003] The advance of mobile cellular networks and the popularity of mobile devices combined with the constant growth in user throughput have created a huge demand for one resource: spectrum.

[0004] There are three main policy approaches to spectrum management that are relevant for commercial wireless broadband:

- License the spectrum to operators, who will pay significant fees for the privilege of using dedicated spectrum;

- Use of unlicensed spectrum where devices are sharing the same spectrum using a set of predetermined rules aimed at insuring fair spectrum access; and

Create opportunities for Shared spectrum resources, e.g., Licensed Shared Access (LSA) or Authorized shared access (ASA), usually proposing a division of rights of use, based on time of use or geographical constraints between mobile operators and possibly an incumbent user.

[0005] This disclosure is concerned with the third (last) approach, which proposes a shared spectrum approach. A typical use of this scenario is to enable use of a band that is available for licensed users in some markets, but is being restricted in others because of incumbents, such as radar or satellite systems. Incumbent systems can be protected around the area of deployment, while authorization for mobile infrastructure can be granted in such a way that aggregate interference from mobile systems towards the incumbent is limited to an acceptable level of noise rise or performance degradation. In LSA, the mobile operator is licensed to operate in permitted or authorized areas and is the reasonable regulatory approach to ASA.

[0006] The Federal Communications Commission (FCC) has defined the Citizens Broadband Radio Service (CBRS) in the 3550-3700 MHz band. The CBRS band has traditionally been used by naval radar and by the Fixed Satellite System (FSS) service, both constituting Tier 1 incumbent primary use. The two remaining tiers respectively allow the issue of Priority Access Licenses (PAL) and General Authorized Access (GAA) in the band for wireless broadband use. PAL users benefit from the priority to spectrum based on the acquired licensed area and bandwidth. In contrast, GAA users are allowed access to any spectrum not utilized by higher tiers based on authorized access. Radio devices are registered as Citizens Broadband Radio Service Devices (CBSD) based on their location and their operating parameters. A single eligible radio device may request access to PAL and GAA spectrum.

[0007] While the Wireless Innovation Forum (WinnForum) specifies technology agnostic protocols that are mostly geared towards regulatory compliance, the CBRS Alliance (CBRSA) is seeking to improve the performance of Long Term Evolution (LTE) networks operating in the CBRS.

[0008] The CBRS Alliance was chartered as an industry trade organization seeking to promote and improve the operation of LTE in the band. The Alliance is specifying changes to network architecture to allow both the traditional operator deployed operation and private network operation including neutral hosts and has provided a platform to establish the impetus for contributions in Third Generation Partnership Project (3 GPP) for defining frequency bands for LTE-Time Division Duplex (TDD) and LTE-enhanced Licensed Assisted Access (eLAA) operation in the band. The CBRS Alliance has also taken on the task to define guidelines and standards for coexistence solutions using the LTE-TDD technologies. These solutions are based on a logical component known as the Coexistence Manager (CxM). This will allow LTE-TDD networks to cooperate within a Coexistence Group (CxG), known as the CBRS Alliance CxG, by means of semi-static allocation of different frequency channels.

[0009] Furthermore, 3 GPP has defined the band B48 for the LTE TDD devices operating in CBRS band and it is working towards introducing band N48 for 5G New Radio (NR) devices.

[0010] The CBRS Alliance also advocates for the use of LTE and NR technology in the CBRS 3.5GHz band, as well as to specify methods of improving LTE performance in a shared spectrum deployment. The CBRS alliance has published a technical specification entitled“CBRS Alliance, CBRS Coexistence Technical Specification, CBRSA-TS-2001, V2.0.0, 6 January 2019” (see htps://wmv.cbrsdliance.Org/wp-content/upioads/2019/Q3/CBRSA- TS-2QQl-V2.0.0 Pubiished- March-1 l-2019.pdf) for co-existence of network and devices using LTE technology and is in the process of expanding the technical specification to include NR devices. The CxM will be in charge of assigning channels to a group of CBSDs that declare themselves as compatible with one another for the purposes of interference mitigation. The group is generally referred to as a CxG and may e.g. be composed of LTE CBSDs belonging to the CxG called“CBRS ALLIANCE CXG” that has passed compliance with certification by the CBRS Alliance. The CxM manages these CBSDs in a way that minimizes inter-CBSD interference as well as protects the incumbents and the higher tier users. The CBRS Alliance is also defining additional rules for the CxG CBRS ALLIANCE CXG, as follows:

[0011] - All TDD deployments in the band shall be cell phase synchronized and shall have frame timing derived from a common time reference.

[0012] - There are two TDD configurations that are mandated: TDD Config 2 and TDD Config 1

[0013] - Other TDD configurations can be used when the deployment is isolated or when all the operators in the area agree to use a particular configuration. Otherwise, the CxM will default to one of the mandated configurations.

[0014] - Connected sets offer a method to determine where the CBRS spectrum can be re-used and where it requires to be divided between different network deployments to ensure coexistence. Connected sets are built by evaluating if the CBSDs will interfere with each other, for example, two CBSDs or two networks of CBSDs that have overlapping coverage may be deemed to be connected. Independent connected sets may each access the entire CBRS spectrum, but within a connected set, the spectrum must be divided between different deployments.

[0015] - A different Connected Set is constructed by the CxM for the purpose of TDD configuration assignment.

[0016] - All LTE- TDD CBSDs that are part of the same LTE- TDD Connected Set will use the same uplink-downlink configuration and Special Subframe (SSF) configuration.

[0017] - Individual CBSDs specify the desired TDD configuration (uplink-downlink configuration and SSF configuration) and the TDD fallback configuration as attributes in the grouping parameter associated with the CBRS Alliance CxG. [0018] - Any 3GPP uplink-downlink configuration and SSF configuration defined in 3GPP may be used, provided all the LTE-TDD CBSDs in the LTE-TDD Connected Set use the same desired TDD configuration.

[0019] If LTE-TDD CBSDs belonging to the same LTE TDD Connected Set select differing desired TDD configurations, the CxM designates the use of one mandatory fallback TDD configuration from those listed in Table 1, which also requires the use of SSF Configuration 7. The TDD configuration shall be chosen by the majority vote among the fallback TDD configurations requested by CBSDs within the constructed baseline Connected Set, where ties are resolved by a pseudorandom draw.

TabSs 1: Mandatory E-UTRA TDD UL/DL Configurations for the C'BRSA CxG.

SUMMARY

[0020] The current solution for TDD Configuration assignment, specified in the CBRS Alliance Coexistence Technical Specification (TS) 2001 Release 2, requires that all the CBSDs within a connected set use the same TDD configuration. However, this approach could be unfavorable for operators that have a deployment use case that requires TDD configuration that is different from the TDD configuration chosen by the CxM.

[0021] Moreover, the current rules require the CxM to coordinate a change in the TDD configuration when the number of CBSDs requesting a different fallback TDD configuration has increased and that number becomes the majority of CBSDs within the connected set.

[0022] Some embodiments herein can overcome or mitigate the challenges as described above.

[0023] The embodiments introduce a clustering method that will allow a CBRS Coexistence Manager (CxM) to perform a more flexible LTE TDD configuration assignment within a Connected Set. The method can also be applied to NR TDD configuration assignment.

[0024] According to one aspect, some embodiments include a method performed by a controlling node. The controlling node can be a coexistence manager (CxM). The method may comprise: determining one or more first clusters of nodes based on a first configuration; determining one or more second clusters of nodes based on a second configuration; determining one or more third clusters of nodes that do not belong to any of the determined first and second clusters; and assigning the first configuration to the first clusters, assigning the second configuration to the second clusters and assigning a third configuration to the third clusters based on a rule. [0025] According to another aspect, some embodiments include a controlling node configured, or operable, to perform one or more functionalities (e.g. actions, operations, steps, etc.) as described herein. For example, it can perform the above method.

[0026] In some embodiments, the controlling node may comprise one or more communication interfaces configured to communicate with one or more network nodes, and processing circuitry operatively connected to the communication interface, the processing circuitry being configured to perform one or more functionalities as described herein.

[0027] In some embodiments, the processing circuitry may comprise at least one processor and at least one memory storing instructions which, upon being executed by the processor, configure the at least one processor to perform one or more functionalities as described herein.

[0028] In some embodiments, the controlling node may comprise one or more functional modules configured to perform one or more functionalities as described herein.

[0029] According to another aspect, some embodiments include a non-transitory computer- readable medium storing a computer program product comprising instructions which, upon being executed by processing circuitry (e.g., at least one processor) of the controlling node, configure the processing circuitry to perform one or more functionalities as described herein.

[0030] The advantages/technical benefits of the embodiments of the present disclosure are as follows: they allow the CBRS Alliance to support a wider range of use cases that require different TDD configurations.

[0031] It is to be noted that any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to the other embodiments, and vice versa. Certain embodiments may have some, or none of the above advantages. Other advantages will be apparent to persons of ordinary skill in the art. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following description.

[0032] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

[0033] This summary is not an extensive overview of all contemplated embodiments, and is not intended to identify key or critical aspects or features of any or all embodiments or to delineate the scope of any or all embodiments. In that sense, other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Exemplary embodiments will be described in more detail with reference to the following figures, in which:

[0035] Figure la and Figure lb illustrate an architecture for shared spectrum and co-existence management.

[0036] Figure 2 illustrates a flow chart of a method for determining configuration assignment, according to an embodiment.

[0037] Figure 3a and Figure 3b illustrate an example of a connected set for a first configuration and a second configuration, according to an embodiment.

[0038] Figure 4a and Figure 4b illustrate an example of determining different clusters in a connected set in which the method of Figure 2 is applied, according to an embodiment.

[0039] Figure 5 illustrates an example of configuration assignment, according to an embodiment.

[0040] Figure 6 illustrates an example of configuration assignment according to an existing method.

[0041] Figure 7a and Figure 7b illustrate an example of a connected set for a first configuration and a second configuration.

[0042] Figure 8a, Figure 8b and Figure 8c illustrate an example of determining different clusters in a connected set in which the method of Figure 2 is applied.

[0043] Figure 9a illustrates an example of configuration assignment, according to an embodiment.

[0044] Figure 9b illustrates an example of configuration assignment according to an existing method.

[0045] Figure 10 illustrates an example of an interference matrix, according to an embodiment.

[0046] Figure 11 illustrates an example of a network deployment with different operators.

[0047] Figure 12 illustrates an example of an interference matrix for the example of Figure 11.

[0048] Figure 13 illustrates an exemplary flow chart of a method for assigning TDD configuration.

[0049] Figure 14 illustrates an exemplary flow chart of a method for assigning TDD configuration.

[0050] Figure 15 illustrates an exemplary flow chart of a method for assigning TDD configuration. [0051] Figures 16 and 17 are a schematic illustration of a controlling node, according to an embodiment.

DETAILED DESCRIPTION

[0052] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments. Upon reading the following description in light of the accompanying figures, those skilled in the art will understand the concepts of the description and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the description.

[0053] Various features and embodiments will now be described with reference to the figures to fully convey the scope of the disclosure to those skilled in the art.

[0054] Many aspects will be described in terms of sequences of actions or functions. It should be recognized that in some embodiments, some functions or actions could be performed by specialized circuits, by program instructions being executed by one or more processors, or by a combination of both.

[0055] Further, some embodiments can be partially or completely embodied in the form of computer readable carrier or carrier wave containing an appropriate set of computer instructions that would cause a processor to carry out the techniques described herein.

[0056] In some alternate embodiments, the functions/actions may occur out of the order noted in the sequence of actions. Furthermore, in some illustrations, some blocks, functions or actions may be optional and may or may not be executed; these are generally illustrated with dashed lines.

[0057] The shared spectrum and co-existence management architecture is depicted in Figure la, as proposed by the FCC for the 3.5 GHz band. The Spectrum Access System (SAS) is a central entity or system for coordinating, authorizing and managing use of the CBRS spectrum, protecting higher tier operations from interference, and maximizing frequency capacity for all CBRS operators. The SAS may be referred to as a controlling node. The SAS administrators will be permitted to charge CBRS operators fees for registration and frequency coordination services. There may be one or more SAS, such as SAS1 and SAS2 connected to each other.

[0058] As illustrated in Figure la, for example, the SAS is also connected to FCC databases, an Environmental Sensing Capability (ESC) system for incumbent detection, an informing incumbent system, a plurality of CBSDs, a domain proxy (DP) and a second SAS, such as SAS2. The Domain Proxy can be connected to a plurality of CBSDs. Furthermore, the SAS2 can be also connected to another ESC. [0059] The FCC requires that transmission equipment with specific, standardized capabilities be employed by CBRS operators for use in the 3.5 GHz band. This equipment is called CBSD. CBSDs are fixed base stations/access points, such as an LTE Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node Bs (also commonly denoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs). There are two types of CBDSs: Category A (a lower power CBSD) and Category B (a higher power CBSD). The CBSDs can only operate under the authority and management of a centralized SAS.

[0060] CBRS end user devices are controlled by an authorized CBSD. End User Devices (EUD) have the capability to receive and decode information from a CBSD. The users access a communication network through one or more CBSDs and, when granted permission from the SAS, use resources within the shared band.

[0061] The ESC can monitor for incumbent radar activity in coastal areas and near inland military bases. For example, the ESC can employ spectrum sensing technologies in conjunction with the SAS, in order to allow CBRS users to operate near coastlines on frequencies not being used by the federal radar systems. When incumbent activity is detected, the ESC communicates that information to SAS1. The SAS or SASs will reconfigure local devices to avoid interfering with the detected incumbent radars.

[0062] The FCC databases include information related to commercial users and corresponding licenses (e.g., site-based licensing information). SAS and SAS2 are capable of directly interfacing with the FCC databases to access information used for SAS operations.

[0063] The Domain Proxy is a managing intermediary. A Domain Proxy’s functions are to, for example:

•Accept a set of one or more available channels and select channels for use by specific CBSDs, or alternatively pass the available channels to the carrier EMS for CBSD channel selection;

•Receives confirmation of channel assignment from SAS;

•Perform bidirectional information processing and routing;

•Interference reporting, etc.

[0064] Figure la, as described above, shows an architecture, as supported by the specification for CBRS from the perspective of regulatory compliance. More specifically, Figure la shows the Wireless Innovation Forum (WinnForum) architecture that has been used by the FCC as baseline for certification of both CBSDs and SASes. [0065] Figure lb shows an architecture supported by the specification for CBRS from the perspective of regulatory compliance and coordination of GAA users within a Coexistence Group . More specifically, Figure lb shows a notional representation of how the CBRS Alliance Coexistence group policy agreements may be carried out, using the illustrated architecture.

[0066] Figure lb is similar to Figure la with the exception that the DP is absent, so that a plurality of CBSDs is connected to the SAS directly. Furthermore, a CxM is also connected to the SAS. The CxM can be regionally assigned to a particular SAS for centralized control of the CxG on a local basis or may be distributed with periodic reconciliation of state. The interface between the CxM and the SAS is not specified yet but mechanisms to communicate information to the CxM have been defined via the SAS-CBSD interface. Alternatively, the CxM could be integrated in the SAS as there is no specified direct interface to the CBSD and information transfer is via containers in SAS-CBSD messages. The CxM is charged with analyzing and mitigating interference among members of the Co-existence group operating on GAA spectrum, for example.

[0067] Terminology

[0068] A co-existence group (CxG) can be defined as a group of nodes (e.g. CBSDs) that may have interference with each other, but the CBSDs of the group can coordinate their own interference within the group according to a common interference management policy.

[0069] A Common Channel Group (CCG) can be defined as a group of CBSDs, that are part of the same Interference Coordination Group (ICG), requiring a common primary channel assignment. The common primary channel assignment will be fulfilled by the CxM only for the CBSDs that have overlapping coverage.

[0070] A Connected set can be defined as a set of CBSDs belonging to a connected component of a graph created at the SAS or CxM.

[0071] A CxM can be defined as a logical entity responsible for managing coexistence between GAA users within a CxG in coordination with SAS, according to the common interference management policy. More specifically, the CxM is associated with a SAS and represents an analytical engine that coordinates operations of CBSDs belonging to a CxG, for example.

[0072] The CBRS Alliance coexistence technical specification states that the Coexistence Manager shall build a connected set of CBSDs and shall use the connected set as an input to the TDD Configuration assignment. Two (2) CBSDs are deemed to be connected by an edge in the connected set, if there is a coverage overlap between the 2 CBSDs.

[0073] Individual CBSDs can specify the desired TDD configuration (uplink-downlink configuration and SSF configuration) and the TDD fallback configuration as attributes in the grouping parameter associated with CBRSA CxG. Only two fallback TDD configurations are allowed by the specification, TDD Configl and TDD Config 2 (as described in Table 1). The introduction of other TDD configurations is not precluded. Then, the present disclosure would be also applicable to these configurations.

[0074] The present disclosure proposes a new clustering method to increase flexibility of TDD configuration determination for CBSDs/nodes in a Connected Set. The method comprises identifying clusters of nodes in the connected set that only have connections to nodes for which CBSDs have requested the same TDD configuration.

[0075] Turning to Figure 2, a flow chart of a method 200 for clustering nodes (e.g. CBSDs) based on configurations, such as TDD configurations, is illustrated. The method can be implemented in the CxM. Method 200 comprises:

[0076] Step 210: Determining one or more first clusters of nodes/CBSDs based on a first (e.g. desired) configuration;

[0077] Step 220: Determining one or more second clusters of nodes/CBSDs based on a second (e.g. fallback) configuration;

[0078] Step 230: Determining one or more third (e.g. leftover/remaining) clusters of nodes, that do not belong to any of the determined first and second clusters.

[0079] Step 240: Assigning the first configuration to the first clusters, assigning the second configuration to the second clusters and assigning a third configuration to the third clusters based on a rule.

[0080] The order of the steps is not necessarily in the described order.

[0081] For example, in step 210, the CxM can identify/determine one or more (first) clusters of nodes in the graph that have a first desired configuration, such as TDD Config x and only have connections to nodes of the graph that also have the same first configuration (i.e. TDD Config x). For those first clusters of nodes, the desired first configuration, TDD Config x, can be granted.

[0082] For example, in step 220, for the remaining nodes of the Connected Set which are not part of a desired configured cluster, the CxM can further identify/determine one or more second clusters of nodes that have a specified second configuration, such as a fallback configuration TDD Config y and only have connections to nodes of the graph that also have the same second configuration (e.g. fallback TDD Config ).

[0083] For example, in step 230, the CxM can further identify/determine one or more leftover or third clusters, which are not part of the first clusters or second clusters. In each such (third) clusters, the CxM can determine a third configuration based on the majority of the CBSDs requesting the same fallback configuration. The determination of the 3 ^rd configuration can be based on other rules as well.

[0084] In some examples, the first configuration may comprise one or more desired configurations requested by the nodes in the first clusters. And the one or more first clusters of nodes may have only connections with nodes that have the first configuration.

[0085] In some examples, the second configuration may comprise one or more fallback configurations requested by the nodes in the second clusters. And the one or more second clusters of nodes may have only connections with nodes that have the second configuration.

[0086] In some examples, the first, second and third configurations are TDD configurations.

[0087] Furthermore, a special consideration should be given to the“link nodes”, i.e. the nodes that connect the different clusters, which are identified as the first (or desired) clusters, the second (or fallback) clusters and the third (or leftover) clusters with nodes belonging to other clusters.

[0088] As such, in some examples, the controlling node may identify the link nodes, which connect different clusters together and manage interference between the link nodes and adjacent nodes.

[0089] In some examples, the controlling node may build a connected set of nodes for the first configuration and a connected set of nodes for the second configuration.

[0090] Now, to illustrate the clustering method 200, two examples will be given below.

[0091] Connected Set Example 1

[0092] In this first example, it is assumed that there are 3 operators deploying CBSDs in a small city, operators A, B and C (see Figure 3a). The following is assumed for the 3 operators:

[0093] - Operator A’s desired TDD Configuration is TDD Config 1 and the fallback configuration is also TDD Config l;

[0094] - Operator B’s desired TDD Configuration is TDD Config 2 and the fallback configuration is also TDD Config 2;

[0095] - Operator C’s desired TDD Configuration is TDD Config 0 and the fallback configuration is TDD Config 1.

[0096] More specifically, Figures 3a and 3b illustrate the TDD Connected Sets that are built by the CxM for this example. In Figure 3a, the connected set for the first configuration, e.g. desired TDD configuration, is built by the CxM, for example. In Figure 3b, the connected set for the second configuration, e.g. fallback TDD configuration, is built by the CxM.

[0097] Applying step 210 in this example, the CxM identifies/determines the clusters having the first/desired configurations. For example, Figure 4a illustrates the result of step 210, i.e. three clusters have been identified/determined as the first clusters: Ci, C2 and C3, each of the first clusters is based on a first configuration. For example, Ci is based on TDD Config 1, C2 is based on TDD Config 2, and C3 is based on TDD Config 0.

[0098] Applying step 220 in this example, the CxM does not identify/determine any clusters for the fallback configuration.

[0099] Appling 230 in this example, the CxM identifies/determines the leftover clusters C4, as shown in Figure 4b.

[0100] Figure 5 illustrates the final TDD Configuration assignment done by the CxM, in this example. After the CBSDs of the different operators are grouped into clusters as identified by method 200, the CxM assigns TDD Config 1 to Ci, TDD Config 2 to C2 and TDD Config 0 to C3. For C4, the majority of nodes has requested TDD Config 1 as the fallback configuration (i.e. two nodes have requested TDD Config 1 against one node requesting TDD Config 2). As such, the CxM assigns TDD Config 1 to C4. Furthermore, Figure 5 shows some specific nodes. The nodes in light grey shade have some interference. However, the interference is at a low level because the light grey shaded nodes are using the same TDD configuration as their neighbor nodes. The dark grey shaded nodes are neighbor nodes using different TDD configuration. As such, their level of interference is higher. In this case, the dark grey shaded nodes, that are also link nodes, need interference management within the network of each operator. More specifically, the interference between some of the link nodes (e.g. dark grey shaded nodes) can be managed by the CxM. The interfering nodes (using different TDD configurations) belong to the same network (of the same operator). Different techniques can be used to manage this interference, including using collaborative schedulers, radio planning, addition of physical barriers or orienting of coverage. There may also be some scheduling features that can mitigate interference by allowing two networks to reduce the probability of use of the spectrum simultaneously, etc. These techniques are beyond the scope of this disclosure.

[0101] Figure 5 also highlights that several nodes will be allowed to operate using their desired (or first) TDD configuration. These nodes are marked without shading.

[0102] For comparison purposes, Figure 6 describes the TDD configuration assignment done by the CxM according to the rules captured in Release 2 of the CBR Alliance Coexistence Technical Specification. Figure 6 shows that all the nodes in the connected set are required to use a same configuration, e.g. TDD Config 1. This is in contrast with Figure 5, which shows that most of the nodes can use their own desired configuration, such as TDD Config 1, TDD Config 2 or TDD Config 0. [0103] Connected Set Example 2

[0104] In this second example, it is assumed that there are 3 operators deploying CBSDs in a small city, operators A, B and C. The following is assumed for the 3 operators:

[0105] - Operator A’s desired TDD Configuration is TDD Config 2 and the fallback configuration is also TDD Config 2;

[0106] - Operator B’s desired TDD Configuration is TDD Config 1 and, due to an agreement between operator A and operator B, the fallback configuration is TDD Config 2;

[0107] - Operator C’s desired TDD Configuration is TDD Config 0 and the fallback configuration is TDD Config 1.

[0108] Figures 7a and 7b illustrate the TDD Connected Set that is built by the CxM. More specifically, Figure 7a illustrates the connected set for the desired TDD configuration. Figure 7b illustrates the connected set for the fallback TDD configuration.

[0109] Applying step 210 in this example, the CxM identifies/determines the desired clusters as depicted in Figure 8a. As shown in Figure 8a, the CxM identifies/ determines 2 clusters, Ci and C2, with Ci being based on TDD Config 2 and with C2 being based on TDD Config 0, for example.

[0110] Applying step 220 in this example, the CxM identifies/ determines the fallback clusters, as depicted in Figure 8b. Figure 8b shows C3 as the fallback cluster, with C3 being based on TDD Config _2, for example.

[0111] Applying step 230 in this example, the CxM identifies/ determines the leftover clusters, as depicted in Figure 8c. In Figure 8c, C4 is identified as the leftover cluster.

[0112] The final TDD configuration assignment done by the CxM is illustrated in Figure 9a. The CxM assigns TDD Config 2 to Ci, and TDD Config 0 to C2. The CxM asisgns TDD Config 2 to C _3. Regarding C4, the majority of the nodes in C4 has requested TDD Config 2 as their fallback configuration (e.g. 2 nodes have requested TDD Config 2 against one node requesting TDD Config 1). As such, TDD Config 2 is chosen to the be the configuration for C4. Therefore, the CxM assigns TDD Config 2 to C4. As a note, other rules to decide what configuration to choose for C4 can be considered.

[0113] For comparison purposes, Figure 9b describes the TDD configuration assignment done by the CxM according to the rules captured in Release 2 CBRS Alliance Coexistence Technical Specification. It can be seen in Figure 9a that not all the nodes have the same TDD configuration. In contrast, in Figure 9b, all the nodes have the same configuration, e.g. the TDD Config 2. [0114] Now, in order to define a generalized clustering algorithm for identifying non-interfering clusters within a connected set, the following framework will be employed. Assume that there is a total of“N” CBSDs (numbered n = 1 to N) in a multiple operator network and denote the interference seen at CBSD k from any other CBSD j in the network as ijk _. With this notation, one can create a generalized interference matrix I as illustrated in Figure 10 In / the diagonal terms ikk are defined as zero (i.e. assuming a given CBSD does not interfere with itself). In addition, it can be noted that:

[0115] 1. Summing along any column k gives the total aggregate interference level seen at CBSD kfrom all other CBSDs.

[0116] 2. Summing along any row j gives the total interference from CBSD j as aggregated over all other CBSDs.

[0117] In general, the interference term ijk may be insignificant (i.e. well below the noise floor of the channel in the network) if CBSD j and CBSD k are not physically adjacent to each other in the network, or equivalently in the connected set graph. If a threshold T1 is defined for interference between adjacent or non-adjacent CBSDs below which ijk is set to be zero, the only remaining non-zero elements will represent interference between adjacent CBSDs or non-adjacent CBSDs (these will possibly be CBSDs within one additional degree of separation) that cause significant interference between the given pair of CBSDs. A typical value of the threshold T1 may be in the range of the noise floor receive sensitivity of the CBRS band (e.g. around -96 dBm) currently in use by the SAS, or a higher threshold value, for example in the range of -60 to -70 dBm for indoor users for which the desired received signal strength is well above the receive sensitivity noise floor. Note that for any row j in the interference matrix /, a different TDD configuration can be safely assigned to another CBSD kif the entry ijk is zero.

[0118] In order to further illustrate the teachings of this disclosure, consider the network deployment illustrated in Figure 11. The network is comprised of three different operators A, B and C with 11 different CBSDs in the network, numbered 1 through 11. The interference levels above the threshold T1 between any two different CBSDs is illustrated by a solid line, whereas interference below the threshold T1 between any two CBSDs is illustrated by a dashed line. These interference relationships can be represented by the interference matrix provided in Figure 12. In the illustrated interference matrix, interference relationships with a level above the threshold Tl, are indicated with a solid bold type (i.e. hi), whereas interference relationships with a level below the threshold Tl are indicated by a greyed out type (i.e 114). From Figure 11, it can be seen that operator A comprises CBSDs 1 - 4, operator B comprises CBSDs 5 - 8 and operator C comprise CBSDs 9 to 11. In the context of the interference matrix in Figure 12, the interference from CBSDs in a given network corresponds to entries in rows 1-4 for operator A, rows 5-8 for operator B and rows 9 - 11 for operator C respectively. Correspondingly, interference received by CBSDs in a given network translates to entries in columns 1-4 for operator A, columns 5-8 for operator B and columns 9 - 11 for operator C respectively. This partitioning of the rows and columns in the matrix between operators provides both a visualization and a representation of interference between the different operators as illustrated in Figure 12. For operator A, the entries across rows 1 - 4 illustrate that in terms of interference to operator B, only CBSDs 5 and 7 (i.e. 145 and 137) are impacted with interference above the threshold Tl, and for operator C only CBSD 9 (i.e. 149) is impacted. Furthermore, it can be seen that for rows 1 and 2 none of the CBSDs in columns 5 - 8 for operator B or columns 9 -11 for operator C are above the threshold Tl . As such, CBSDs 1 and 2 could use any TDD configuration without impacting any CBSDs of operator B or C, e.g. CBSDs 1 and 2 could use a different TDD configuration from the TDD configuration for CBSDs of operators B and C and not impact any of the CBSDs of operators B and C.

[0119] Furthermore, it can be noted that interference values above Tl in the section of the matrix spanned by rows 1-4 and columns 1-4 represent interference between CBSDs within the network of operator A. As such, no TDD coordination between operators is required to manage these interference impacts, but they can be managed within the network of operator A itself - i.e. if any non-zero values of ijk represents interference between CBSDs in the same operator network, the interference between these CBSDs can be managed within the network, by choosing the same TDD configurations for example or employing other interference mitigation strategies, if different TDD configurations are chosen.

[0120] As an illustrative example of TDD configuration assignment with the interference matrix /of Figure 12, suppose the desired TDD configurations of operators A, B, and C are configurations 0, 2, and 1 with fallback TDD configurations of 1, 1 and 1 respectively. Since CSBDs 1 and 2 of operator A are not interfering with operator B or C (i.e. all the entries in rows 1 and 2 in Figure 12 are below the threshold Tl for all columns of CBSDs of operator B and C), operator A could assign TDD configuration 0 to CBSDs 1 and 2, and assign TDD configuration 1 to CBSDs 3 and 4, and manage the interference between CBSDs 1/2 and 3/4 internal to its own network. Another alternative for operator A would be to assign TDD configuration 0 to all of CBSDS 1, 2, 3, and 4. This would require mitigating the interference between CBSD 3 of operator A and CBSD 7 of operator B, as well as CBSD 4 of operator A and CBSDs 5 and 9 of operator B. Since this interference is between operators, it would require an inter-operator agreement to mitigate the interference with some other approach, such as Listen Before Talk (LBT).

[0121] In summary, the generalized clustering method involves partitioning the interference matrix /into the intersection of rows corresponding to CBSD numbers or labels j of a first operator and columns corresponding to the CBSDs numbers or labels k of a second operator, the intersection of rows and columns are referred to as an intersection set. If for any row j of the intersection set, there are no interference terms ijk that exceed the threshold Tl, then CBSD j may employ a TDD configuration independent of that employed by CBSD k of the second operator. If there are elements ijk in the intersection area of the rows j of the first operator and columns k of the second operator that exceed the threshold Tl, then the corresponding CBSD j from the first operator and CBSD k from the second operator must either employ the same TDD configurations or employ a mutually agreed upon interference mitigation strategy.

[0122] One possible approach to managing the interference, when different TDD configurations are employed between adjacent CBSDs, is to use a LBT approach between those CBSDs. For the exemplary matrix in Figure 12, this could apply to communications for CBSDs 3 and 7 as well as 4 and 5 or 4 and 9.

[0123] The details of the method are provided in Figure 13. For example, method 300 as detailed in Figure 13 comprises:

[0124] Step 310: Generating an interference matrix /for all“N” CBSDs in the network with each entry ijk corresponding to the interference to CBSD k from CBSD j .

[0125] Step 320: Partitioning the interference matrix / into intersecting sets among different operators in the network such that a row j of the intersection set corresponds to a CBSD j of a first operator and a column k of the intersection set corresponds to a CBSD k of a second operator.

[0126] Step 330: for any row j of the intersection set, determining if the interference terms ijk exceeds the threshold TL

[0127] Step 340: if it is determined that the terms ijk do not exceed the threshold Tl (i.e. the terms ijk are inferior to the threshold Tl), employing/assigning a TDD configuration for CBSD j that is independent of the TDD configuration employed by CBSD k of the second operator.

[0128] Step 350: if it is determined that the terms ijk exceed the threshold Tl, either assigning the same TDD configuration for CBSD j from operator 1 and CBSD k from operator 2 or employing a mutually agreed upon interference mitigation strategy.

[0129] As an additional extension of this exemplary method, one may also consider a second higher threshold T2 (such as -60 dBm) for the entries ijk of the matrix. For any entries ijk exceeding this threshold T2, the respective CBSDs j and k would be mandated to employ the same TDD configuration.

[0130] In some embodiments, the entries ijk of the interference matrix I can be changed from an interference level to a measure of the SINR in dB as seen at the CBSD k in the presence of transmissions from CBSD j . This may be more appropriate particularly for indoor deployments. When using an SINR metric, appropriate thresholds T1 and T2 may be for example on the order of 15-20 dB for T1 and 0-5 dB for T2.

[0131] In some embodiments, link adaptation can be applied to the entries ijk of the interference matrix I that exceed the threshold Tl . Link adaptation will be applied to CBSDs j and k corresponding to element ijk exceeding the threshold Tl, in order to increase the robustness of the communication at both CBSD j and CBSD k to interference (i.e. choose link adaptation with a lower code rate and/or lower modulation order). For ijk exceeding the threshold T2, a second more robust link adaptation setting may be chosen.

[0132] In some embodiments, machine learning can be first applied to the transmission levels of each CBSD in the network to minimize the number of interference entries exceeding the threshold Tl while maintaining a target SINR for communication by a CBSD with the EUDs it is serving.

[0133] Turning to Figure 14, a flow chart of a method 600 for assigning TDD configurations in different nodes of different operators will be described. The method can be implemented in a controlling node, such as the CxM, for example. Method 600 comprises:

[0134] Step 610: Determining based on an interference matrix, a plurality of sets of nodes from different operators.

[0135] Step 620: for a first node in a first set, determining whether an interference value between the first node of a first operator and a second node of a second operator is inferior to a threshold value.

[0136] Step 630: in response to determining that the interference value between the first node and the second node is inferior to the threshold value, assigning a first time division duplex (TDD) configuration to the first node and assigning a second TDD configuration to the second node.

[0137] The order of the steps is not necessarily in the described order.

[0138] In some examples, the first TDD configuration may different from the second TDD configuration.

[0139] In some examples, in response to determining that the interference value between the first node and the second node exceeds the threshold value, the controlling node may assign a same TDD configuration to the first node and the second node. [0140] In some examples, in response to determining that the interference between the first node and the second node exceeds the threshold value, the controlling node may apply an interference mitigation strategy on the first node and second node.

[0141] In some examples, the controlling node may compare an interference value with the threshold value for each node of the first set.

[0142] In some examples, the controlling node may compare an interference value with a second threshold value for each node of the interference matrix.

[0143] In some examples, the interference matrix can be generated by calculating interference between all nodes of the different operators in a network.

[0144] In some examples, the controlling node may partition the interference matrix into intersecting sets among different operators such that a row j of the intersection set corresponds to a node j of a first operator and a column k of the intersection set corresponds to a node k of a second operator.

[0145] In some examples, the entries of the interference matrix may comprise an interference level or a signal to interference plus noise ratio (SINR).

[0146] In some examples, the controlling node may apply link adaptation to the first node and the second node, for increasing robustness of communications at the first and second nodes.

[0147] In some examples, the interference matrix can be generated based on transmissions between all the nodes of the different operators, the transmissions being associated with machine learning for minimizing interference between the nodes.

[0148] In some examples, the plurality of sets of nodes can show interference between nodes of different operators.

[0149] In some examples, the assigned TDD configuration can be used by the first and second nodes for transmissions of data.

[0150] Now turning to Figure 15, a method 700 for assigning TDD configurations to different nodes of different operators will be described. Method 700 can be implemented in a controlling node, such as a CxM. Method 700 comprises:

[0151] Step 710: generating an interference matrix between all nodes of a plurality of operators in a network.

[0152] Step 720: partitioning the interference matrix into a plurality of intersecting sets corresponding to interference between different operators. [0153] Step 730: for a first node in a first intersecting set, determining whether an interference value between the first node from a first operator and a second node from a second operator is inferior to a threshold value.

[0154] Step 740: in response to determining that the interference value between the first node and the second node is inferior to the threshold value, assigning a first TDD configuration to the first node and assigning a second TDD configuration to the second node.

[0155] Figure 16 is a block diagram of an exemplary controlling node 1000, such as CxM, that may be used to determine a configuration assignment based on the method described hereinabove. The controlling node 1000 includes a processing circuitry 1010, and a network interface 1020. The circuitry 1010 may include one or more (node) processors 1030, and memory 1040. In some embodiments, the one or more processors 1030 executes the method 200 and all embodiments as described above. The memory 1040 stores the instructions for execution by the one or more processors 1030, and the network interface 1020 communicates signals to the other elements, such as the SAS.

[0156] The one or more processors 1030 may include any suitable combination of hardware and software implemented in one or more modules to execute instructions and manipulate data to perform some or all of the described functions of the CxM, such as those described above. In some embodiments, the one or more processors 1030 may include, for example, one or more computers, one or more central processing units (CPUs), one or more microprocessors, one or more applications, one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs) and/or other logic. In certain embodiments, the one or more processors 1030 may comprise one or more of the modules discussed below with respect to Figure 16.

[0157] The memory 1040 is generally operable to store instructions, such as a computer program, software, an application including one or more of logic, rules, algorithms, code, tables, etc. and/or other instructions capable of being executed by one or more processors 1030. Examples of memory 1040 include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or or any other volatile or non-volatile, non-transitory computer-readable and/or computer-executable memory devices that store information.

[0158] In some embodiments, the network interface 1020 is communicatively coupled to the one or more processors 1030 and may refer to any suitable device operable to receive input for the controlling node 1000, send output from the controlling node 1000, perform suitable processing of the input or output or both, communicate to other devices, or any combination of the preceding. The network interface 1020 may include appropriate hardware (e.g., port, modem, network interface card, etc.) and software, including protocol conversion and data processing capabilities, to communicate through a network.

[0159] Other embodiments of the controlling node 1000 may include additional components beyond those shown in Figure 16 that may be responsible for providing certain aspects of a CxM functionality, including any of the functionality described above and/or any additional functionality (including any functionality necessary to support the solutions described above).

[0160] Processors, interfaces, and memory similar to those described with respect to Figure 10 may be included in other network nodes. Other network nodes may optionally include or not include a wireless interface. Functionalities described could reside within the same node or could be distributed across a plurality of nodes and network nodes.

[0161] Figure 17 illustrates an example of a controlling node 1100 in accordance with another embodiment. The controlling node 1100 could be a CxM. The controlling node 1100 may include some modules 1110, such as a determining module, an assigning module, a generating module and a partitioning module. The determining module is configured to perform at least steps 210, 220 and 230 of Figure 2 and steps 610, 620 of Figure 14 and step 730 of Figure 15. The assigning module is configured to perform at least steps 240 of Figure 2 and step 630 of Figure 14 and step 740 of Figure 15. The generating module is configured to perform at least step 710 of Figure 15. The partitioning module is configured to perform at least steps 720 of Figure 15.

[0162] In certain embodiments, the determining module and the assigning module may be implemented using one or more processors, such as described with respect to Figure 10. The modules may be integrated or separated in any manner suitable for performing the described functionality.

[0163] It should be noted that according to some embodiments, virtualized implementations of the controlling node of Figures 16 and 17 and of the CBSDs are possible. As used herein, a “virtualized” network node or controlling node (e.g., a virtualized base station or a virtualized radio access node or a SAS) is an implementation of the network node or controlling node in which at least a portion of the functionality of the network node/controlling node is implemented as a virtual component (e.g., via a virtual machine(s) or container(s) executing on a physical processing node(s) in a network(s)). As such, the functions of the controlling nodes 1000 and 1100 (described hereinabove) could be distributed across a cloud computing system. [0164] Any steps or features described herein are merely illustrative of certain embodiments. It is not required that all embodiments incorporate all the steps or features disclosed nor that the steps be performed in the exact order depicted or described herein. Furthermore, some embodiments may include steps or features not illustrated or described herein, including steps inherent to one or more of the steps disclosed herein.

[0165] Any two or more embodiments described in this document may be combined in any way with each other.

[0166] Modifications, additions, or omissions may be made to the systems and apparatuses described herein without departing from the scope of the disclosure. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. Additionally, operations of the systems and apparatuses may be performed using any suitable logic comprising software, hardware, and/or other logic. As used in this document,“each” refers to each member of a set or each member of a subset of a set.

[0167] Modifications, additions, or omissions may be made to the methods described herein without departing from the scope of the disclosure. The methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

[0168] Although this disclosure has been described in terms of certain embodiments, alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the spirit and scope of this disclosure.