WO2025072091A1

WO2025072091A1 - Method and equipment for cell-free wireless communication

Info

Publication number: WO2025072091A1
Application number: PCT/US2024/047992
Authority: WO
Inventors: Firouz Behnamfar; Ayman F. Naguib; Danila Zaev; Onur Sahin
Original assignee: Apple Inc.
Priority date: 2023-09-28
Filing date: 2024-09-23
Publication date: 2025-04-03

Abstract

Methods and apparatus for cell-free wireless communication are discussed herein. For example, a cluster control entity (CCE) of a base station cluster that is serving a user equipment (UE) on a cell-free basis may receive, from the UE, feedback information, wherein the feedback information comprises base station measurement information, and adjusting a composition of the base station cluster based on the feedback information. In some cases, a UE may determine feedback information comprising criteria for a first base station to join a base station cluster that is serving the UE on a cell-free basis, and transmit, to the CCE of the base station cluster, the feedback information. In some instances, a base station may determine that it meets criteria to join or leave a base station cluster and join or leave the base station cluster respectfully.

Description

METHOD AND EQUIPMENT FOR CELL-FREE WIRELESS COMMUNICATION

TECHNICAL FIELD

[0001] This application relates generally to wireless communication systems, including cell-free wireless communication.

BACKGROUND

[0002] Wireless mobile communication technology uses various standards and protocols to transmit data between a base station and a wireless communication device. Wireless communication system standards and protocols can include, for example, 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) (e.g., 4G). 3GPP New Radio (NR) (e.g., 5G), and Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard for Wireless Local Area Networks (WLAN) (commonly known to industry groups as Wi-Fi®).

[0003] As contemplated by the 3GPP, different wireless communication systems' standards and protocols can use various radio access networks (RANs) for communicating between a base station of the RAN (which may also sometimes be referred to generally as a RAN node, a network node, or simply a node) and a wireless communication device known as a user equipment (UE). 3GPP RANs can include, for example, Global System for Mobile communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE) RAN (GERAN), Universal Terrestrial Radio Access Network (UTRAN). Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and/or Next-Generation Radio Access Network (NG-RAN).

[0004] Each RAN may use one or more radio access technologies (RATs) to perform communication between the base station and the UE. For example, the GERAN implements GSM and/or EDGE RAT. the UTRAN implements Universal Mobile Telecommunication System (UMTS) RAT or other 3GPP RAT, the E-UTRAN implements LTE RAT (sometimes simply referred to as LTE), and NG-RAN implements NR RAT (sometimes referred to herein as 5G RAT, 5G NR RAT, or simply NR). In certain deployments, the E-UTRAN may also implement NR RAT. In certain deployments, NG-RAN may also implement LTE RAT.

[0005] A base station used by a RAN may correspond to that RAN. One example of an E-UTRAN base station is an Evolved Universal Terrestrial Radio Access Network (E- UTRAN) Node B (also commonly denoted as evolved Node B, enhanced Node B, eNodeB, or eNB). One example of an NG-RAN base station is a next generation Node B (also sometimes referred to as a g Node B or gNB).

[0006] A RAN provides its communication services with external entities through its connection to a core network (CN). For example, E-UTRAN may utilize an Evolved Packet Core (EPC) while NG-RAN may utilize a 5G Core Network (5GC).

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0007] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

[0008] FIG. 1 illustrates a diagram of a network configuration with cells belonging to different base stations located at different physical locations.

[0009] FIG. 2 illustrates a diagram of a network configuration with a UE connected to a primary serving cell and, due to the mobility of the UE, the UE connects to secondary cells and a second primary cell.

[0010] FIG. 3 illustrates a diagram of a cell-free wireless communication configuration with various clusters of base stations, according to embodiments herein.

[0011] FIG. 4 illustrates a method of a CCE of a base station cluster that is serving a UE on a cell-free basis, according to embodiments herein.

[0012] FIG. 5 illustrates a method of a UE, according to embodiments herein.

[0013] FIG. 6 illustrates a method of a base station, according to embodiments herein.

[0014] FIG. 7 illustrates a method of a base station, according to embodiments herein.

[0015] FIG. 8 illustrates an example architecture of a wireless communication system, according to embodiments disclosed herein.

[0016] FIG. 9 illustrates a system for performing signaling between a wireless device and a network device, according to embodiments disclosed herein.

DETAILED DESCRIPTION

[0017] Various embodiments are described with regard to a UE. However, reference to a UE is merely provided for illustrative purposes. The example embodiments may be utilized with any electronic component that may establish a connection to a network and is configured with the hardware, software, and/or firmware to exchange information and data with the network. Therefore, the UE as described herein is used to represent any appropriate electronic component.

[0018] FIG. 1 illustrates a diagram 100 of a network configuration with cells belonging to different base stations located at different physical locations.

[0019] In certain wireless communication systems (e.g., 3GPP new radio (NR), 3GPP LTE), as long as a UE is in coverage, it is attached to a serving cell which is considered the UE's primary serving cell. In some cases, system information (SI), paging messages, and control signaling are initiated at and transmitted by the primary cell, regardless of the presence and/or number of other serving cells for the UE.

[0020] In dual connectivity, the same concept exists. For example, if a UE is in coverage (i.e., in dual connectivity) it is attached to a primary cell, and if the UE loses connection with that cell, it is considered out-of-coverage. It should be understood that the primary cell is the cell that transmits SI messages to the UE and configures the UE. As illustrated in diagram 100, the cells (e.g., that a UE 108 is in coverage of and/or is connected to) can belong to different base stations (e g., base station #1 102, base station #2 104, base station #3 106). The base stations may be located at different physical locations with reference to the UE 108. In such examples, the primary cell of the UE 108 is at a base station #1 102 and as a result base station #1 102 transmits SI to the UE 108 and configures the UE 108.

[0021] FIG. 2 illustrates a diagram 200 of a network configuration with a UE connected to a first primary' serving cell and one or more secondary cells and where, due to the mobility of the UE, the UE performs handover from the first primary cell to a second primary cell.

[0022] In some examples, as illustrated in diagram 200, when a UE is at a first location (i.e., location one 202), it is connected to a primary cell (i.e., base station #1 204). Various cells (base station #2 206. base station #3 208. and base station #4 210) also exchange data with the UE as secondary cells. However, the UE receives SI, paging messages, and configuration from its primary cell (i.e., base station #1 204).

[0023] When the UE moves 224 to location two 212, the UE performs handover from the first primary cell (base station #1 204) to the second primary cell (i.e., base station #7 214). In some cases, the second primary cell (i.e., base station #7 214) may have better connectivity to the UE at location two 212 as it is in closer proximity to the UE and the original primary’ cell (base station #1 204) may not have optimal connectivity with the UE as it is further away from the UE. Accordingly, the UE at location two 212 with primary cell base station #7 214 exchanges data with secondary cells such as base station #6 216, base station #5 218, and base station #3 208 which are closer in proximity to the UE when it is at location two 212 in comparison to base station #2 206, base station #3 208 and base station #4 210. It should be understood that base station #1 204, base station #2 206, and base station #4 210 belong to a first MME 220 while base station #3 208, base station #7 214, base station #6 216 and base station #5 218 belong to a second MME 222.

[0024] When a UE intends to attach to a network, it selects a cell (i.e.. a primary cell) and acquires SI from it. The UE will then perform a random access procedure to that cell, which involves transmitting a random sequence and exchanging messages with that cell to receive dedicated configuration from that cell. Other cells can then be added as secondary cells.

[0025] In some instances, for mobility purposes, the UE performs measurements regularly. For example, the UE measures quantities based on the strength of the received signals from its serving and neighbor cells.

[0026] In certain wireless communications mechanisms, finding a serving cell, performing measurements regularly, and switching serving cells (e.g., due to mobility) results in the UE consuming a considerable amount of power (where battery' power of the UE may be limited). Additionally, the handover procedure between cells causes service interruptions for the UE and sometimes connection failure for the UE. In some examples, measurement overhead for the UE increases as the number of secondary' cells increases (e.g., due to the UE having to measure the secondary cells to determine, for each secondary cell, if the UE has a better connection to one of the secondary cells). Corresponding to such embodiments, it may further be that the UE may be handed over to the cell with a better connection and said cell becomes the primary cell of the UE and as a result possibly encountering service interruptions, as described.

[0027] Embodiments herein discuss the use of cell-free wireless communication systems that serve a UE without a using any serving cell, thus avoiding the need for handover, avoiding the need for cell-aware distributed multiple input multiple output (MIMO) communication (DMIMO) operations, and avoiding various other issues that may arise in wireless communication systems corresponding to the use of one or more serving cells. Additionally, embodiments herein discuss details for assigning responsibilities to UEs and base stations in such cell-free wireless communication systems.

[0028] FIG. 3 illustrates a diagram 300 of a cell-free wireless communication configuration with various clusters of base stations, according to embodiments herein.

[0029] In some embodiments, in cell-free wireless communication systems, there is no serving cell and accordingly no primary cell. For example, in radio resource control idle (RRC IDLE) and radio resource control inactive (RRC INACTIVE) states, the UE may receive SI messages from whatever base stations that, public land mobile network (PLMN)-wise and/or access-wise, are allowed in the cell-free wireless communication system. Additionally, in the radio resource control connected (RRC CONNECTED) state, it may be up to the network to choose the base station(s) of the base station cluster that transmit to and/or receive from the UE.

[0030] In cell-free wireless communication systems, the UE may communicate with a number of base stations, referred to herein as a base station cluster. Different base stations in a same cluster can belong to different MMEs.

[0031] For example, as illustrated in diagram 300, when a UE is at a first location 302 it may communicate in a first base station cluster 320 made up of base stations such as base station #1 308, base station #2 306. base station #4 310, and base station #3 312. When the UE moves to a second location 304, the UE may communicate in a second base station cluster 322 made up of base stations such as base station #3 312, base station #4 310, base station #7 314, base station #6 316, and base station #5 318.

[0032] Additionally, base stations of the first base station cluster 320 and base stations of the second base station cluster 322 may belong to either the first MME 324 or the second MME 326. For example, base station #3 312 and base station #4 310 may both be a part of the first base station cluster 320, but base station #3 312 may belong to the second MME 326 while base station #4 310 may belong to the first MME 324.

[0033] In various embodiments, a base station may operate in different clusters (either simultaneously or over time). For example, base station #3 312 and base station #4 310 may be included in both the first base station cluster 320 and the second base station cluster 322 and may be used to communicate with the UE as its moving from the first location 302 to the second location 304.

[0034] Note that no handover between primary cells is performed in cell-free wireless communication systems, as there are no serving cells in the first place. Instead, a base station may be added or removed from the base station cluster for the UE (or the base station may add or remove itself from the cluster for the UE) as the UE moves. For example, as the UE moves closer towards a candidate base station, that base station may be added to the cluster. As another example, as the base station moves further away from a base station, that base station may be removed from the cluster.

[0035] In some embodiments, the UE may send feedback (e.g., metrics) extracted from downlink (DL) signals and physical channels to help the network determine/control for the members of the base station cluster. In some cases, feedback extracted from DL signals and physicals channels that may be so used includes a reference signal received power (RSRP), a synchronization signal block received power (SSBRP), a physical base station identifier, a base station a global identifier, and/or a beam identifier (BID).

[0036] In some other embodiments, the network may decide which base stations are in a base station cluster based on information extracted from uplink (UL) transmissions. Such transmissions may include a physical uplink shared channel (PUSCH) or a sounding reference signal (SRS). Further, in some embodiments, metrics such as DL and/or UL block error rate (BLER) may be utilized to decide which base stations are in a base station cluster. For example, if the BLER for a base station is above a certain threshold, the base station may not be added to the base station cluster.

[0037] Embodiments disclosed herein are not limited to one metric but rather may utilize any combination of the metrics described herein.

[0038] In order to avoid base stations from joining or leaving clusters of base stations too frequently (e.g., “ping-ponging” in and out as a member of the base station cluster), in some cases, the network can filter the instances of the metrics described herein. For example, a first-order infinite impulse response (HR) filter of the following form may be used:

is filter output at time index n, x[w] is the metric being monitored (e.g.,

RSRP or BLER) at time index n, and 0 < a < 1 is a real number filter coefficient.

[0039] Further, in some embodiments, base stations that meet the criteria described herein may take into account additional factors to join and/or leave a base station cluster (or be added or removed from a cluster). For example, a base station can decide not to join a cluster if its loading (e.g., loading value) is high or the base station may decide to join the cluster if its loading is low (or will soon be low). Alternatively, the network may decide to add the base station to the cluster or remove the base station from the cluster based on the base station's loading.

[0040] In some embodiments, base stations can use a combination of metrics to join and/or leave a cluster. For example, a base station k can join a cluster if the following conditions are met: i > p_r for no more than n cells,

• RSRPi i^s

filtered reported RSRP for base station i;

• Pr is some threshold RSRP, Pdeax is the minimum RSRP for decoding control and data messages;

• Lk is the loading of base station k; and

• A max is the maximum acceptable loading.

[0041] In some embodiments, in cell-free communication, all data exchange (e.g., userdata exchange as well as base station-specific-data exchange) can be done with a base station cluster. Moreover, UL transmissions are done with all base stations in the base station cluster, including all transmissions in the random access procedure such as the random access preamble transmission.

[0042] In some embodiments, a cluster control entity (CCE) (e.g., in the MME) of the base station cluster may keep track of the base stations in the base station cluster that serve each UE. When a base station leaves the base station cluster (or is removed from the cluster), the base station notifies the CCE. The CCE may then notify the remaining base stations of the base station cluster.

[0043] In some cases, if a base station notifies the CCE that it has left a cluster, the base station flushes all data associated with the UE (e.g., radio link control (RLC) and packet data convergence protocol (PDCP) data). In other cases, when the base station leaves a cluster, the CCE may notify and/or instruct the base station whether to flush UE data or forward the data to specific base stations. Further, in some other cases, when the base station leaves a cluster, the base station may forward the contents of its buffers to other (remaining) base stations in the cluster. This may be accomplished through the use of base station to base station communication (e.g., on an Xn interface) or via communication through the CCE.

[0044] In some embodiments, when a base station joins a cluster (or is added to the cluster), the newly added base station may start with empty' buffers. In some other cases, when a base station joins a cluster, a list of the base stations in the cluster is passed to the newly added base station by the CCE. Further, in some other cases, when a base station joins a cluster, the CCE notifies the base stations in the cluster of addition of the new base station. Other base stations may use, for example, an X2 interface and/or an SI interface to populate the buffers of the newly joined base station, if needed.

[0045] In current wireless communication systems, base stations negotiate handover between cells and may communicate through MMEs to complete such handover. In some examples of traditional handover, an interruption time and/or latency causes calls to drop. Further, the UE may change direction and not switching to the right or intended base stations.

[0046] However, in cell-free wireless communication systems as discussed herein, base stations add and/or remove themselves to the base station cluster, and/or are added/removed from the cluster by the network, according to the criteria disclosed herein, as the UE moves. In such embodiments, there is no serving cell-target cell negotiation to handover control of the UE. Thus, there is a reduction in interruption or, in some cases, no interruption time or call drop in such cell-free wireless communication.

[0047] Additional Example Embodiments

[004S] Certain embodiments disclosed herein establish a cell-UE relationship.

[0049] Certain embodiments disclosed herein introduce the use of multiple cell exchanges (as opposed to one as in current wireless communication systems) of UE- specific data and/or control messages with the UE. There is no primary cell, and many existing procedures, such as handover, become unnecessary. Furthermore, latencysensitive loads on the network interfaces such as an X2 interface and an SI interface will not be needed.

[0050] Certain embodiments disclosed herein introduce criteria for base stations to join clusters of base stations and information to handle data forwarding when base stations join clusters. [0051] Certain embodiments disclosed herein introduce criteria for base stations to leave clusters of base stations and information to handle data forwarding when base stations leave clusters.

[0052] Certain embodiments disclosed herein discuss aspects of one or both of control messaging and/or UE-specific data, are valid for both DL and UL. and are applicable to any number of transmit and receive antennas.

[0053] FIG. 4 illustrates a method 400 of a CCE of a base station cluster that is serving a UE on a cell-free basis, according to embodiments herein. The illustrated method 400 includes receiving 402, from the UE, feedback information, wherein the feedback information comprises base station measurement information. The method 400 further includes adjusting 404 a composition of the base station cluster, based on the feedback information.

[0054] In some embodiments of the method 400, adjusting the composition of the base station cluster comprises removing a base station from the base station cluster. Some such embodiments further comprise instructing the base station to flush UE data in a buffer of the removed base station. Some other such embodiments further comprise instructing the base station to forward UE data in a buffer of the removed base station.

[0055] In some embodiments of the method 400, adjusting the composition of the base station cluster comprises adding a base station to the base station cluster. Some such embodiments further comprise transmitting a list of one or more base stations of the cluster to the base station. Some other such embodiments further comprise informing one or more other base stations of the base station cluster of the base station.

[0056] In some embodiments, the method 400 further comprises determining that the UE is in an RRC_CONNECTED state, and assigning, based on determining that the UE is in an RRC_CONNECTED state, one or more base stations of the network as the base station cluster.

[0057] In some embodiments, the method 400 further comprises sending, to the UE, an instruction to use one or more base stations of the network as the base station cluster.

[0058] In some embodiments of the method 400, the base station measurement information comprises a RSRP of a base station

[0059] In some embodiments of the method 400, the base station measurement information comprises a SSBRP of a base station. [0060] In some embodiments of the method 400, the feedback information further includes one or more of a physical base station ID, a global base station ID and a beam ID corresponding to the base station measurement information.

[0061] In some embodiments of the method 400, the composition of the base station cluster is adjusted based on information extracted from an UL transmission comprising one of a PUSCH transmission and an SRS transmission.

[0062] In some embodiments of the method 400, the base station measurement information comprises a filtered metric corresponding to a candidate base station for the base station cluster. Some such embodiments further comprise generating the filtered metric corresponding to the candidate base station using a first-order IIR filter according is filter output at time index

n, x\n\ is the metric corresponding to the candidate base station at the time index n, and 0 < a < 1 is a filter coefficient

[0063] FIG. 5 illustrates a method 500 of a UE, according to embodiments herein. The illustrated method 500 includes determining 502 feedback information comprising criteria for a first base station to join a base station cluster that is serving the UE on a cell-free basis. The method 500 further includes transmitting 504, to a CCE of the base station cluster, the feedback information.

[0064] In some embodiments of the method 500, the feedback information comprises a RSRP measurement of a base station.

[0065] In some embodiments of the method 500, the feedback information comprises a SSBRP measurement of a base station.

[0066] In some embodiments, the method 500 further comprises receiving, from the CCE. an instruction to use one or more base stations of the network as the base station cluster.

[0067] FIG. 6 illustrates a method 600 of a base station, according to embodiments herein. The illustrated method 600 includes determining 602 that the base station meets criteria to join a base station cluster that is serving a UE on a cell free basis, wherein the criteria comprises one or more of base station based criteria and UE based criteria. The method 600 further includes joining 604 the base station cluster in response to determining that the base station meets the criteria. [0068] In some embodiments, the method 600 further comprises receiving a list of one or more base stations of the base station cluster.

[0069] In some embodiments, the method 600 further comprises receiving, in response to joining the base station cluster, buffer data from the base station cluster via a CCE of the base station cluster.

[0070] In some embodiments, the method 600 further comprises receiving, in response to joining the base station cluster, buffer data from the base station cluster via one or more communication interfaces between the base station and one or more base stations of the base station cluster.

[0071] In some embodiments of the method 600, the base station based criteria comprises one or more of a RSRP of the base station, a filtered RSRP of the base station, and a loading value of the base station.

[0072] In some embodiments of the method 600, the UE based criteria comprises one or more of a UE-based RSRP measurement of the base station, a UE-based SSBRP measurement of the base station, a physical base station ID, a global base station ID, and a beam ID corresponding to the base station measurement information.

[0073] FIG. 7 illustrates a method 700 of a base station, according to embodiments herein. The illustrated method 700 includes determining 702 that the base station meets criteria to leave a base station cluster that is serving a UE on a cell-free basis, wherein the criteria comprises one or more of base station based criteria and UE based criteria. The method 700 further includes leaving 704 the base station cluster in response to determining that the base station meets the criteria.

[0074] In some embodiments, the method 700 further comprises flushing, in response to leaving the base station cluster, data from a buffer of the base station.

[0075] In some embodiments, the method 700 further comprises receiving an indication from a CCE of the base station cluster to flush data from a buffer of the base station, and flushing the data from the buffer of the base station in response to the indication.

[0076] In some embodiments, the method 700 further comprises forwarding contents of a buffer of the base station to a one or more base stations of the base station cluster in response to leaving the base station cluster. [0077] In some embodiments of the method 700, the base station based criteria comprises one or more of a RSRP of the base station, a filtered RSRP of the base station, and a loading value of the base station.

[0078] In some embodiments of the method 700, the UE based criteria comprises one or more of a UE-based RSRP measurement of the base station, a UE-based SSBRP measurement of the base station, a physical base station ID, a global base station ID, and a beam ID corresponding to the base station measurement information.

[0079] FIG. 8 illustrates an example architecture of a wireless communication system 800, according to embodiments disclosed herein. The following description is provided for an example wireless communication system 800 that operates in conjunction with the LTE sy stem standards and/or 5G or NR system standards as provided by 3GPP technical specifications.

[0080] As shown by FIG. 8, the wireless communication system 800 includes UE 802 and UE 804 (although any number of UEs may be used). In this example, the UE 802 and the UE 804 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks), but may also comprise any mobile or non-mobile computing device configured for wireless communication.

[0081] The UE 802 and UE 804 may be configured to communicatively couple with a RAN 806. In embodiments, the RAN 806 may be NG-RAN. E-UTRAN, etc. The UE 802 and UE 804 utilize connections (or channels) (shown as connection 808 and connection 810, respectively) with the RAN 806, each of which comprises a physical communications interface. The RAN 806 can include one or more base stations (such as base station 812 and base station 814) that enable the connection 808 and connection 810.

[0082] In this example, the connection 808 and connection 810 are air interfaces to enable such communicative coupling, and may be consistent with RAT(s) used by the RAN 806, such as, for example, an LTE and/or NR.

[0083] In some embodiments, the UE 802 and UE 804 may also directly exchange communication data via a sidelink interface 816. The UE 804 is shown to be configured to access an access point (shown as AP 818) via connection 820. By way of example, the connection 820 can comprise a local wireless connection, such as a connection consistent with any IEEE 802.11 protocol, wherein the AP 818 may comprise a Wi-Fi® router. In this example, the AP 818 may be connected to another network (for example, the Internet) without going through a CN 824.

[0084] In embodiments, the UE 802 and UE 804 can be configured to communicate using orthogonal frequency division multiplexing (OFDM) communication signals with each other or with the base station 812 and/or the base station 814 over a multicarrier communication channel in accordance with various communication techniques, such as, but not limited to, an orthogonal frequency division multiple access (OFDMA) communication technique (e.g., for downlink communications) or a single carrier frequency division multiple access (SC-FDMA) communication technique (e g., for uplink and ProSe or sidelink communications), although the scope of the embodiments is not limited in this respect. The OFDM signals can comprise a plurality of orthogonal subcarriers.

[0085] In some embodiments, all or parts of the base station 812 or base station 814 may be implemented as one or more software entities running on server computers as part of a virtual network. In addition, or in other embodiments, the base station 812 or base station 814 may be configured to communicate with one another via interface 822. In embodiments where the wireless communication system 800 is an LTE system (e.g., when the CN 824 is an EPC), the interface 822 may be an X2 interface. The X2 interface may be defined between two or more base stations (e.g., two or more eNBs and the like) that connect to an EPC, and/or between two eNBs connecting to the EPC. In embodiments where the wireless communication system 800 is an NR system (e.g., when CN 824 is a 5GC), the interface 822 may be an Xn interface. The Xn interface is defined between two or more base stations (e.g., two or more gNBs and the like) that connect to 5GC, between a base station 812 (e.g., a gNB) connecting to 5GC and an eNB, and/or between two eNBs connecting to 5GC (e.g.. CN 824).

[0086] The RAN 806 is shown to be communicatively coupled to the CN 824. The CN 824 may comprise one or more network elements 826, which are configured to offer various data and telecommunications services to customers/subscribers (e.g., users of UE 802 and UE 804) who are connected to the CN 824 via the RAN 806. The components of the CN 824 may be implemented in one physical device or separate physical devices including components to read and execute instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium). [0087] In embodiments, the CN 824 may be an EPC, and the RAN 806 may be connected with the CN 824 via an S I interface 828. In embodiments, the S I interface 828 may be split into two parts, an SI user plane (Sl-U) interface, which carries traffic data between the base station 812 or base station 814 and a serving gateway (S-GW), and the SI -MME interface, which is a signaling interface between the base station 812 or base station 814 and mobility management entities (MMEs).

[0088] In embodiments, the CN 824 may be a 5GC, and the RAN 806 may be connected with the CN 824 via an NG interface 828. In embodiments, the NG interface 828 may be split into two parts, an NG user plane (NG-U) interface, which carries traffic data between the base station 812 or base station 814 and a user plane function (UPF). and the SI control plane (NG-C) interface, which is a signaling interface between the base station 812 or base station 814 and access and mobility management functions (AMFs).

[0089] Generally, an application server 830 may be an element offering applications that use internet protocol (IP) bearer resources with the CN 824 (e.g., packet switched data services). The application server 830 can also be configured to support one or more communication services (e.g., VoIP sessions, group communication sessions, etc.) for the UE 802 and UE 804 via the CN 824. The application server 830 may communicate with the CN 824 through an IP communications interface 832.

[0090] FIG. 9 illustrates a system 900 for performing signaling 934 between a wireless device 902 and a network device 918, according to embodiments disclosed herein. The system 900 may be a portion of a wireless communications system as herein described. The wireless device 902 may be, for example, a UE of a wireless communication system. The network device 918 may be, for example, a base station (e.g., an eNB or a gNB) of a wireless communication system.

[0091] The wireless device 902 may include one or more processor(s) 904. The processor(s) 904 may execute instructions such that various operations of the wireless device 902 are performed, as described herein. The processor(s) 904 may include one or more baseband processors implemented using, for example, a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein. [0092] The wireless device 902 may include a memory 906. The memory 906 may be a non-transitory computer-readable storage medium that stores instructions 908 (which may include, for example, the instructions being executed by the processor(s) 904). The instructions 908 may also be referred to as program code or a computer program. The memory 906 may also store data used by, and results computed by, the processor(s) 904. [0093] The wireless device 902 may include one or more transceiver(s) 910 that may include radio frequency (RF) transmitter circuitry and/or receiver circuitry that use the antenna(s) 912 of the wireless device 902 to facilitate signaling (e.g., the signaling 934) to and/or from the wireless device 902 with other devices (e.g., the network device 918) according to corresponding RATs.

[0094] The wireless device 902 may include one or more antenna(s) 912 (e.g., one, two, four, or more). For embodiments with multiple antenna(s) 912, the wireless device 902 may leverage the spatial diversity of such multiple antenna(s) 912 to send and/or receive multiple different data streams on the same time and frequency resources.

[0095] In certain embodiments having multiple antennas, the wireless device 902 may implement analog beamforming techniques, whereby phases of the signals sent by the antenna(s) 912 are relatively adjusted such that the (joint) transmission of the antenna(s) 912 can be directed (this is sometimes referred to as beam steering).

[0096] The wireless device 902 may include one or more interface(s) 914. The interface(s) 914 may be used to provide input to or output from the wireless device 902. For example, a wireless device 902 that is a UE may include interface(s) 914 such as microphones, speakers, a touchscreen, buttons, and the like in order to allow for input and/or output to the UE by a user of the UE. Other interfaces of such a UE may be made up of transmitters, receivers, and other circuitry (e.g., other than the transceiver(s) 910/antenna(s) 912 already described) that allow for communication between the UE and other devices and may operate according to known protocols (e.g., Wi-Fi®, Bluetooth®, and the like).

[0097] The wireless device 902 may include a cell-free communication module 916. The cell-free communication module 916 may be implemented via hardware, softw are, or combinations thereof. For example, the cell-free communication module 916 may be implemented as a processor, circuit, and/or instructions 908 stored in the memory 906 and executed by the processor(s) 904. In some examples, the cell-free communication module 916 may be integrated within the processor(s) 904 and/or the transceiver(s) 910. For example, the cell-free communication module 916 may be implemented by a combination of software components (e.g., executed by a DSP or a general processor) and hardware components (e.g., logic gates and circuitry) within the processor(s) 904 or the transceiver(s) 910.

[0098] The cell-free communication module 916 may be used for various aspects of the present disclosure, for example, aspects of FIG. 1, FIG. 2, FIG. 3 and FIG. 5. The cell- free communication module 916 is configured to determine feedback information comprising criteria for a first network device 918 to join a network device 918 cluster that is serving the wireless device 902 on a cell-free basis. The cell-free communication module 916 is further configured to transmit, to a CCE of the network device 918 cluster, the feedback information.

[0099] The network device 918 may include one or more processor(s) 920. The processor(s) 920 may execute instructions such that various operations of the network device 918 are performed, as described herein. The processor(s) 920 may include one or more baseband processors implemented using, for example, a CPU, a DSP, an ASIC, a controller, an FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein.

[0100] The network device 918 may include a memory 922. The memory⁷ 922 may be a non-transitory computer-readable storage medium that stores instructions 924 (which may include, for example, the instructions being executed by the processor(s) 920). The instructions 924 may also be referred to as program code or a computer program. The memory 922 may also store data used by, and results computed by, the processor(s) 920.

[0101] The network device 918 may include one or more transceiver(s) 926 that may include RF transmitter circuitry and/or receiver circuitry that use the antenna(s) 928 of the network device 918 to facilitate signaling (e.g., the signaling 934) to and/or from the network device 918 with other devices (e.g., the wireless device 902) according to corresponding RATs.

[0102] The network device 918 may include one or more antenna(s) 928 (e.g., one, two, four, or more). In embodiments having multiple antenna(s) 928, the network device 918 may perform MIMO, digital beamforming, analog beamforming, beam steering, etc., as has been described.

[0103] The network device 918 may include one or more interface(s) 930. The interface(s) 930 may be used to provide input to or output from the network device 918. For example, a network device 918 that is a base station may include interface(s) 930 made up of transmitters, receivers, and other circuitry (e.g., other than the transceiver(s) 926/antenna(s) 928 already described) that enables the base station to communicate with other equipment in a core network, and/or that enables the base station to communicate with external networks, computers, databases, and the like for purposes of operations, administration, and maintenance of the base station or other equipment operably connected thereto.

[0104] The network device 918 may include a cell-free communication module 932. The cell-free communication module 932 may be implemented via hardware, software, or combinations thereof. For example, the cell-free communication module 932 may be implemented as a processor, circuit, and/or instructions 924 stored in the memory 922 and executed by the processor(s) 920. In some examples, the cell-free communication module 932 may be integrated within the processor(s) 920 and/or the transceiver(s) 926. For example, the cell-free communication module 932 may be implemented by a combination of software components (e.g., executed by a DSP or a general processor) and hardware components (e.g., logic gates and circuitry) within the processor(s) 920 or the transceiver(s) 926.

[0105] The cell-free communication module 932 may be used for various aspects of the present disclosure, for example, aspects of FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 6 and FIG. 7. The cell-free communication module 932 is configured to determine that the network device 918 meets criteria to leave a network device 918 cluster that is serving a wireless device 902 on a cell-free basis, wherein the criteria comprises one or more of network device 918 based criteria and wireless device 902 based criteria. The cell-free communication module 932 is further configured to leave the network device 918 cluster in response to determining that the network device 918 meets the criteria.

[0106] In some cases, the cell-free communication module 932 is configured to determine that the network device 918 meets criteria to join a network device 918 cluster that is serving a wireless device 902 on a cell free basis, wherein the criteria comprises one or more of network device 918 based criteria and wireless device 902 based criteria. In such cases, the cell-free communication module 932 is further configured to join the network device 918 cluster in response to determining that the network device 918 meets the criteria. [0107] Embodiments contemplated herein include an apparatus comprising means to perform one or more elements of the method 500. This apparatus may be. for example, an apparatus of a UE (such as a wireless device 902 that is a UE, as described herein).

[0108] Embodiments contemplated herein include one or more non -transitory computer-readable media comprising instructions to cause an electronic device, upon execution of the instructions by one or more processors of the electronic device, to perform one or more elements of the method 500. This non-transitory computer-readable media may be, for example, a memory of a UE (such as a memory 906 of a wireless device 902 that is a UE, as described herein).

[0109] Embodiments contemplated herein include an apparatus comprising logic, modules, or circuitry to perform one or more elements of the method 500. This apparatus may be, for example, an apparatus of a UE (such as a wireless device 902 that is a UE, as described herein).

[0110] Embodiments contemplated herein include an apparatus comprising: one or more processors and one or more computer-readable media comprising instructions that, when executed by the one or more processors, cause the one or more processors to perform one or more elements of the method 500. This apparatus may be, for example, an apparatus of a UE (such as a wireless device 902 that is a UE, as described herein).

[0111] Embodiments contemplated herein include a signal as described in or related to one or more elements of the method 500.

[0112] Embodiments contemplated herein include a computer program or computer program product comprising instructions, wherein execution of the program by a processor is to cause the processor to carry out one or more elements of the method 500. The processor may be a processor of a UE (such as a processor(s) 904 of a wireless device 902 that is a UE, as described herein). These instructions may be, for example, located in the processor and/or on a memory of the UE (such as a memory 906 of a wireless device 902 that is a UE, as described herein).

[0113] Embodiments contemplated herein include an apparatus comprising means to perform one or more elements of any of the method 400. method 600 and/or method 700. This apparatus may be, for example, an apparatus of a base station (such as a network device 918 that is a base station, as described herein).

[0114] Embodiments contemplated herein include one or more non-transitory computer-readable media comprising instructions to cause an electronic device, upon execution of the instructions by one or more processors of the electronic device, to perform one or more elements of any of the method 400. method 600 and/or method 700. This non-transitory computer-readable media may be, for example, a memory of a base station (such as a memory 922 of a network device 918 that is a base station, as described herein).

[0115] Embodiments contemplated herein include an apparatus comprising logic, modules, or circuitry to perform one or more elements of any of the method 400, method 600 and/or method 700. This apparatus may be, for example, an apparatus of a base station (such as a network device 918 that is a base station, as described herein).

[0116] Embodiments contemplated herein include an apparatus comprising: one or more processors and one or more computer-readable media comprising instructions that, when executed by the one or more processors, cause the one or more processors to perform one or more elements of any of the method 400. method 600 and/or method 700. This apparatus may be, for example, an apparatus of a base station (such as a network device 918 that is a base station, as described herein).

[0117] Embodiments contemplated herein include a signal as described in or related to one or more elements of any of the method 400, method 600 and/or method 700.

[0118] Embodiments contemplated herein include a computer program or computer program product comprising instructions, wherein execution of the program by a processing element is to cause the processing element to carry out one or more elements of any of the method 400, method 600 and/or method 700. The processor may be a processor of a base station (such as a processor(s) 920 of a network device 918 that is a base station, as described herein). These instructions may be, for example, located in the processor and/or on a memory of the base station (such as a memory 922 of a network device 918 that is a base station, as described herein).

[0119] For one or more embodiments, at least one of the components set forth in one or more of the preceding figures may be configured to perform one or more operations, techniques, processes, and/or methods as set forth herein. For example, a baseband processor as described herein in connection with one or more of the preceding figures may be configured to operate in accordance with one or more of the examples set forth herein. For another example, circuitry associated with a UE, base station, network element, etc. as described above in connection with one or more of the preceding figures may be configured to operate in accordance with one or more of the examples set forth herein.

[0120] Any of the above described embodiments may be combined with any other embodiment (or combination of embodiments), unless explicitly stated otherwise. The foregoing description of one or more implementations provides illustration and description, but is not intended to be exhaustive or to limit the scope of embodiments to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of various embodiments.

[0121] Embodiments and implementations of the systems and methods described herein may include various operations, which may be embodied in machine-executable instructions to be executed by a computer system. A computer system may include one or more general-purpose or special-purpose computers (or other electronic devices). The computer system may include hardware components that include specific logic for performing the operations or may include a combination of hardware, software, and/or firmware.

[0122] It should be recognized that the systems described herein include descriptions of specific embodiments. These embodiments can be combined into single systems, partially combined into other systems, split into multiple systems or divided or combined in other ways. In addition, it is contemplated that parameters, attributes, aspects, etc. of one embodiment can be used in another embodiment. The parameters, attributes, aspects, etc. are merely described in one or more embodiments for clarity, and it is recognized that the parameters, attributes, aspects, etc. can be combined with or substituted for parameters, attributes, aspects, etc. of another embodiment unless specifically disclaimed herein.

[0123] It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

[0124] Although the foregoing has been described in some detail for purposes of clarity, it will be apparent that certain changes and modifications may be made without departing from the principles thereof. It should be noted that there are many alternative ways of implementing both the processes and apparatuses described herein. Accordingly, the present embodiments are to be considered illustrative and not restrictive, and the description is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

Claims

1. A method of a cluster control entity (CCE) of a base station cluster that is serving a user equipment (UE) on a cell-free basis, comprising: receiving, from the UE, feedback information, wherein the feedback information comprises base station measurement information; and adjusting a composition of the base station cluster based on the feedback information.

2. The method of claim 1, wherein adjusting the composition of the base station cluster comprises removing a base station from the base station cluster.

3. The method of claim 2 further comprising: instructing the base station to flush UE data in a buffer of the removed base station.

4. The method of claim 2, further comprising: instructing the base station to forward UE data in a buffer of the removed base station.

5. The method of claim 1, wherein adjusting the composition of the base station cluster comprises adding a base station to the base station cluster.

6. The method of claim 5 further comprising: transmitting a list of one or more base stations of the cluster to the base station.

7. The method of claim 5 further comprising: informing one or more other base stations of the base station cluster of the base station.

8. The method of claim 1 further comprising: determining that the UE is in an RRC_CONNECTED state; and assigning, based on determining that the UE is in the RRC_CONNECTED state, one or more base stations of a network as the base station cluster.

9. The method of claim 1 further comprising: sending, to the UE, an instruction to use one or more base stations of a network as the base station cluster.

10. The method of claim 1, wherein the base station measurement information comprises a reference signal received power (RSRP) of a base station.

11. The method of claim 1, wherein the base station measurement information comprises a synchronization signal block received power (SSBRP) of a base station.

12. The method of claim 1, wherein the feedback information further includes one or more of a physical base station identifier (ID), a global base station ID and a beam ID corresponding to the base station measurement information.

13. The method of claim 1, wherein the composition of the base station cluster is adjusted based on information extracted from an uplink (UL) transmission comprising one of a physical uplink shared channel (PUSCH) transmission and a sounding reference signal (SRS) transmission.

14. The method of claim 1, wherein the base station measurement information comprises a filtered metric corresponding to a candidate base station for the base station cluster.

15. The method of claim 14, further comprising generating the filtered metric corresponding to the candidate base station using a first-order infinite impulse response (HR) filter according to:

is a filter output at time index n, x[n ] is the metric corresponding to

the candidate base station at the time index n, and 0 < a < 1 is a filter coefficient.

16. A method of a user equipment (UE) comprising: determining feedback information comprising criteria for a first base station to join a base station cluster that is serving the UE on a cell-free basis; and transmitting, to a cluster control entity (CCE) of the base station cluster, the feedback information.

17. The method of claim 16, wherein the feedback information comprises a reference signal received power (RSRP) measurement of a base station.

18. The method of claim 16, wherein the feedback information comprises a synchronization signal block received power (SSBRP) measurement of a base station.

19. The method of claim 16 further comprising: receiving, from the CCE, an instruction to use one or more base stations of a network as the base station cluster.

20. A method of a base station comprising: determining that the base station meets criteria to join a base station cluster that is serving a user equipment (UE) on a cell free basis, wherein the criteria comprises one or more of base station based criteria and UE based criteria; and joining the base station cluster in response to determining that the base station meets the criteria.

21. The method of claim 20 further comprising: receiving a list of one or more base stations of the base station cluster.

22. The method of claim 20, further comprising: receiving, in response to joining the base station cluster, buffer data from the base station cluster via a cluster control entity (CCE) of the base station cluster.

23. The method of claim 20, further comprising: receiving, in response to joining the base station cluster, buffer data from the base station cluster via one or more communication interfaces between the base station and one or more base stations of the base station cluster.

24. The method of claim 20, wherein the base station based criteria comprises one or more of a reference signal received power (RSRP) of the base station, a filtered RSRP of the base station, and a loading value of the base station.

25. The method of claim 20, wherein the UE based criteria comprises one or more of a UE-based reference signal received power (RSRP) measurement of the base station, a UE-based synchronization signal block received power (SSBRP) measurement of the base station, a physical base station identifier (ID), a global base station ID, and a beam ID corresponding to the base station measurement information.

26. A method of a base station comprising: determining that the base station meets criteria to leave a base station cluster that is serving a user equipment (UE) on a cell-free basis, wherein the criteria comprises one or more of base station based criteria and UE based criteria; and leaving the base station cluster in response to determining that the base station meets the criteria.

27. The method of claim 26 further comprising: flushing, in response to leaving the base station cluster, data from a buffer of the base station.

28. The method of claim 26 further comprising: receiving an indication from a cluster control entity (CCE) of the base station cluster to flush data from a buffer of the base station; and flushing the data from the buffer of the base station in response to the indication.

29. The method of claim 26 further comprising: forwarding contents of a buffer of the base station to a one or more base stations of the base station cluster in response to leaving the base station cluster.

30. The method of claim 26, wherein the base station based criteria comprises one or more of a reference signal received power (RSRP) of the base station, a filtered RSRP of the base station, and a loading value of the base station.

31 . The method of claim 26, wherein the UE based criteria comprises one or more of a UE-based reference signal received power (RSRP) measurement of the base station, a UE-based synchronization signal block received power (SSBRP) measurement of the base station, a physical base station identifier (ID), a global base station ID, and a beam ID corresponding to the base station measurement information.

32. An apparatus comprising means to perform the method of any of claim 1 to claim 31.

33. A computer-readable media comprising instructions to cause an electronic device, upon execution of the instructions by one or more processors of the electronic device, to perform the method of any of claim 1 to claim 31.

34. An apparatus comprising logic, modules, or circuitry to perform the method of any of claim 1 to claim 31.

35. A baseband processor for a user equipment (UE) that is configured to cause the UE to perform one or more elements of any one of claim 16 to claim 25.

36. A baseband processor for a base station that is configured to cause the base station to perform one or more elements of any one of claim 1 to claim 15 and claim 26 to claim 31.