Patent Publication Number: US-2023156647-A1

Title: 5g small cell time synchronized networking

Description:
RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 63/278,781, titled “5G SMALL CELL TIME SYNCHRONIZED NETWORKING,” filed on Nov. 12, 2021, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     The techniques described herein relate generally to a time synchronized network, such as a 5G small cell time synchronized network. 
     BACKGROUND 
     A time synchronized network can provide a framework for coordinating a common time amongst different applications, different instances of an application, and/or different devices connected to the network. The common time coordinated among the different applications and/or devices using the time synchronized network can enable scheduling of actions, traffic, etc. across the different applications and devices to provide for a coordinated operation (e.g., so that the applications may operate in unison). 
     SUMMARY OF THE DISCLOSURE 
     In accordance with the disclosed subject matter, apparatus, systems, and methods are provided for a Time-Sensitive Networking synchronization protocol over a wireless channel of a cellular network. 
     Some embodiments relate to a computerized method to provide a Time-Sensitive Networking (TSN) synchronization protocol over a wireless channel of a cellular network. The method comprises performing, by a cellular network device: receiving, by the network device, timing information from a cellular network node, wherein the cellular network node is in wired communication with the network device, and the timing information is associated with a Network Clock Reference and a transmission time to the network device in accordance with a wired synchronization protocol; determining, by the network device, a timing adjustment based on the timing information; and adjusting, based on the timing adjustment, timing signals that are transmitted by the network device to a user device in cellular communication with the cellular network node through the network device, wherein the timing signals is used to adjust a timing system of the user device in accordance with the TSN synchronization protocol. 
     In some examples, the TSN synchronization protocol is a wireless synchronization protocol, and the wireless synchronization protocol comprises: transmitting, by the network device, downlink information of a radio frame, wherein the transmitting the downlink information comprises transmitting a pattern of reference synchronization signals as the timing signals to the user device; receiving, by the network device, uplink information of the radio frame, wherein the uplink information comprises response information corresponding to a time of arrival of the downlink information at the user device; and determining, by the network device, delay information associated with a travel time for the radio frame to wirelessly travel from the network device to the user device, wherein determining the delay information comprises comparing a first time associated with the network device transmitting the downlink information, to a second time associated with the network device receiving the uplink information. 
     In some examples, the receiving, by the network device, the uplink information further comprises using a Random-Access procedure between the network device and the user device, and the determining the delay information further comprises determining a timing advance. 
     In some examples, the radio frame comprises a plurality of subframes, wherein each of the plurality of subframes comprises a plurality of slots, wherein each of the plurality of slots comprises a plurality of symbols; and the transmitting the pattern of reference synchronization signals further comprises transmitting the pattern of reference synchronization signals as a sub-set of the plurality of symbols. 
     In some examples, the determining the timing adjustment further comprises: determining a synchronized time based on the timing information and the delay information; determining a target arrival time for a portion of the radio frame based on the synchronized time; and determining the timing adjustment based on the target arrival time, the timing information, and the delay information such that, when transmitted, the portion of the radio frame arrives at the user device at the target arrival time. 
     In some examples, the portion of the radio frame is a first slot of a first subframe of the radio frame, and the target arrival time that the radio frame arrives at the user device is at the start of a synchronized clock interval. 
     In some examples, the TSN synchronization protocol supports TSN in accordance with IEEE 802.1AS standard, the TSN synchronization protocol further comprising transmitting, by the network device, the synchronized time such that when the synchronized time arrives at the user device, the synchronized time is synchronized to within a predetermined threshold of a reference time. 
     In some examples, the predetermined threshold is within 1 nanosecond of the reference time, within 1 microsecond of the reference time, or some combination thereof. 
     In some examples, the predetermined threshold is within 250 nanoseconds of the reference time in dispersive channels with time-variant conditions. 
     In some examples, transmitting the pattern of reference synchronization signals further comprises transmitting a radio frame using subcarrier bandwidths from 15 kHz to 240 kHz. 
     In some examples, the receiving timing information from the cellular network comprises receiving a reference time, residence time, and link delay from the reference clock to the network node based on a generic Precision Time Protocol (g-PTP) of the cellular network. 
     In some examples, the network device is a base station. 
     In some examples, the base station is a gNodeB and the cellular network is a 5G network. 
     Some embodiments related to an apparatus configured to provide a TSN synchronization protocol over a wireless channel of a cellular network, the apparatus comprising a processor in communication with memory and a set of additional processing resources, the processor being configured to execute instructions stored in the memory that cause the processor to: receive, by the network device, timing information from a cellular network node, wherein the cellular network node is in wired communication with the network device, and the timing information is associated with a Network Clock Reference and a transmission time to the network device in accordance with a wired synchronization protocol; determine, by the network device, a timing adjustment based on the timing information; and adjust, based on the timing adjustment, timing signals that is transmitted by the network device to a user device in cellular communication with the cellular network node through the network device, wherein the timing signals is used to adjust a timing system of the user device in accordance with the TSN synchronization protocol. 
     In some examples, the TSN synchronization protocol is a wireless synchronization protocol, and wherein the instructions are further configured in accordance with the TSN synchronization protocol to cause the apparatus to: transmit, by the network device, downlink information of a radio frame, wherein the transmitting the downlink information comprises transmitting a pattern of reference synchronization signals as the timing signals to the user device; receive, by the network device, uplink information of the radio frame, wherein the uplink information comprises response information corresponding to a time of arrival of the downlink information at the user device; and determine, by the network device, delay information associated with a travel time for the radio frame to wirelessly travel from the network device to the user device, wherein determining the delay information comprises comparing a first time associated with the network device transmitting the downlink information, to a second time associated with the network device receiving the uplink information. 
     In some examples, the instructions are configured such that the radio frame comprises a plurality of subframes, wherein each of the plurality of subframes comprises a plurality of slots, wherein each of the plurality of slots comprises a plurality of symbols; and the instructions are further configured to cause the apparatus to transmit the pattern of reference synchronization signals further comprises transmitting the pattern of reference synchronization signals as a sub-set of the plurality of symbols. 
     In some examples, the instructions to cause the apparatus to determine the timing adjustment are further configured to: determine a synchronized time based on the timing information, and the delay information; determine a target arrival time for a portion of the radio frame based on the synchronized time; and determine the timing adjustment based on the target arrival time, the timing information, and the delay information such that, when transmitted, the portion of the radio frame arrives at the user device at the target arrival time. 
     In some examples, the instructions are further configured to execute actions sent from the cellular network that are time-synchronized with at least one user device action through a communication protocol that specifies an action type to be executed and the time when the action shall be executed. 
     Some embodiments related to at least one non-transitory computer-readable storage medium encoded with a plurality of computer-executable instructions that, when executed, perform a method to provide a TSN synchronization protocol over a wireless channel of a cellular network, the method comprising: receiving, by the network device, timing information from a cellular network node, wherein the cellular network node is in wired communication with the network device, and the timing information is associated with a Network Clock Reference and a transmission time to the network device in accordance with a wired synchronization protocol; determining, by the network device, a timing adjustment based on the timing information; and adjusting, based on the timing adjustment, timing signals that are transmitted by the network device to a user device in cellular communication with the cellular network node through the network device, wherein the timing signals is used to adjust a timing system of the user device in accordance with the TSN synchronization protocol. 
     In some examples, the synchronization protocol is a wireless synchronization protocol, and the wireless synchronization protocol comprises: transmitting, by the network device, downlink information of a radio frame, wherein the transmitting the downlink information comprises transmitting a pattern of reference synchronization signals as the timing signals to the user device; receiving, by the network device, uplink information of the radio frame, wherein the uplink information comprises response information corresponding to a time of arrival of the downlink information at the user device; and determining, by the network device, delay information associated with a travel time for the radio frame to wirelessly travel from the network device to the user device, wherein determining the delay information comprises comparing a first time associated with the network device transmitting the downlink information, to a second time associated with the network device receiving the uplink information. 
     In some examples, the determining the timing adjustment further comprises: determining a synchronized time based on the timing information and the delay information; determining a target arrival time for a portion of the radio frame based on the synchronized time; and determining the timing adjustment based on the target arrival time, the timing information, and the delay information such that, when transmitted, the portion of the radio frame arrives at the user device at the target arrival time. 
     Some embodiments relate to an apparatus configured to receive a synchronization protocol over a wireless channel of a cellular network, the apparatus comprising a processor in communication with memory and a set of additional processing resources, the processor being configured to execute instructions stored in the memory that cause the processor to: receive, by a user device, timing information from a network device, wherein: receiving, by the user device, comprises receiving downlink information of a radio frame, wherein the downlink information comprises frequency and phase synchronization signals configured as timing signals to the user device; the user device extracts, from a 5GNR Radio Resource Control System Information Block 9, a Timing Advance MAC control element and a time reference of the network device to adjust and discipline using the frequency and phase synchronization signals; the user device extracts a physical layer signal from a Slot Indication signal associated with the radio frame and/or a Symbol Boundary signal to adjust and discipline an internal clock of the user device to meet a time accuracy within a Virtual Clock Domain comprising TSN enabled user devices, network devices, network node and TSN controller. 
     In some examples, the TSN synchronization protocol is a wireless synchronization protocol, and wherein the instructions are further configured in accordance with the TSN synchronization protocol to cause the apparatus to: transmit, by the network device, downlink information of a radio frame, wherein the transmitting the downlink information comprises transmitting a pattern of reference synchronization signals as the timing signals to the user device; receive, by the network device, uplink information of the radio frame, wherein the uplink information comprises response information corresponding to a time of arrival of the downlink information at the user device; and determine, by the network device, delay information associated with a travel time for the radio frame to wirelessly travel from the network device to the user device, wherein determining the delay information comprises comparing a first time associated with the network device transmitting the downlink information, to a second time associated with the network device receiving the uplink information. 
     In some examples, the instructions are configured such that the radio frame comprises a plurality of subframes, wherein each of the plurality of subframes comprises a plurality of slots, wherein each of the plurality of slots comprises a plurality of symbols; and the instructions are further configured to cause the apparatus to transmit the pattern of reference synchronization signals further comprises transmitting the pattern of reference synchronization signals as a sub-set of the plurality of symbols. 
     In some examples, the instructions to cause the apparatus to determine the timing adjustment are further configured to: determine a synchronized time based on the timing information, and the delay information; determine a target arrival time for a portion of the radio frame based on the synchronized time; and determine the timing adjustment based on the target arrival time, the timing information, and the delay information such that, when transmitted, the portion of the radio frame arrives at the user device at the target arrival time. 
     In some examples, the instructions further comprise informing the network device about support of the synchronization protocol and an achievable time accuracy using the instructions that determine the timing adjustment. 
     In some examples, that include a clock disciplining subsystem to use the physical signals of Slot Indication signals and/or Symbol Boundary signals to discipline the internal clock that translates timing information into a computer-executable instruction that comprises the messages associated with the instructions that determine the timing adjustment. 
     The foregoing summary is not intended to be limiting. Moreover, various aspects of the present disclosure may be implemented alone or in combination with other aspects. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
       In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like reference character. For purposes of clarity, not every component may be labeled in every drawing. The drawings are not necessarily drawn to scale, with emphasis instead being placed on illustrating various aspects of the techniques and devices described herein. 
         FIG.  1    illustrates an exemplary Time Sensitive Networking (TSN) architecture configured with a 5G network and a dedicated TSN network. 
         FIG.  2 A  illustrates an exemplary network including a TSN system integrated into the reference 3GPP network architecture. 
         FIG.  2 B  illustrates an exemplary network configured for Time Sensitive Communication (TSC) using a small cell with a small cell integrated TSN Translator (SC-TT), in accordance with some embodiments. 
         FIG.  3    illustrates a private industrial network with a small cell that includes a Small Cell TSN translator, in accordance with some embodiments. 
         FIG.  4 A  illustrates a virtual clock domain including network components illustrated in  FIG.  3   . 
         FIG.  4 B  illustrates network including a dedicated virtual TSN slice, in accordance with some embodiments. 
         FIG.  5 A  illustrates end-to-end synchronization process, in accordance with some embodiments described herein. 
         FIG.  5 B  illustrates an exemplary process of synchronizing the internal clock of the user equipment (UE) with the virtual clock domain, in accordance with some embodiments. 
         FIG.  5 C  illustrates a computerized TSN synchronization protocol, in accordance with some embodiments. 
         FIG.  6 A  is a schematic of a radio frame that may be used in accordance with the embodiments described herein. 
         FIG.  6 B  illustrates a schematic of the timing between the small cell clock flank signal and subframes of the radio frame, in accordance with some embodiments. 
         FIG.  7    illustrates a process of adjusting the UE timing system based on the timing signal received by the UE, in accordance with some embodiments. 
         FIG.  8    illustrates a time locked loop feedback circuit, in accordance with some embodiments. 
         FIG.  9    illustrates an exemplary implementation of TSN network including a 5G small cell and UE, in accordance with some embodiments. 
         FIG.  10    illustrates an exemplary TSN registration and execution request, in accordance with some embodiments. 
         FIG.  11    illustrates an exemplary peer-to-peer TSN protocol, in accordance with some embodiments. 
         FIG.  12    illustrates one exemplary implementation of a computing device, in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     I. Introduction 
     The present application provides techniques for improving the timing and performance of wireless networks, including to provide Time Sensitive Networking (TSN). Some embodiments described herein provide TSN over a wireless network to synchronize a mobile user equipment (UE) with a virtual clock domain. In some applications, providing TSN over a wireless network can provide support for dynamic and flexible UE configurations. Additionally, or alternatively, providing a TSN to the UE can enable scheduling of signal transmission/delivery and/or the enforcement of instruction execution according to timestamps in the virtual clock domain. Such precise time alignment between the UE and the other equipment in the virtual clock domain can enable implementation of facilities that depend on TSN, such as an Industrial Internet of Things (IIOT). In some embodiments, the time alignment between the UE and the virtual clock domain uses a physical layer signal of a radio frame and a time stamp encoded in the radio frame to provide high precision synchronization. In some embodiments, the UE and the virtual clock domain may be synchronized within very small time windows, such as within 1.5 μs or faster. 
     Advances in robotics and automation have provided highly configurable equipment with advanced features, such as equipment capable of performing dexterous functions (e.g., robotic picking applications, robotic implementation of steps of a manufacturing process, etc.) and self-navigation (e.g., for mobile robotic applications). For example, such robotics can provide for the possibly of automated manufacturing, where multiple mobile robotic components work in concert to execute industrial processes. In some applications, coordination between highly configurable robotics may require large volumes of data to be exchanged with low latency within set timing constraints. Given such low latency requirements, wired connections have been used to provide high-precision synchronization between devices, such as between the local clocks of different network components. When the local clocks of different network components are synchronized, those components may implement a virtual clock domain. The virtual clock domain represents the common reference time that each local clock in synchronized to. The precision of the virtual clock domain is directly related to the uncertainty between the time measured on a local clock of a network component and the reference time of the virtual clock domain. 
     The inventors have recognized that in various applications, such as those that include dynamic and/or reconfigurable equipment that is mobile, wired communication may not be possible and/or it may limit the mobility and/or degree of flexibility for configuring the equipment (e.g., which can impact the use case scenarios). The inventors have appreciated that advancements in wireless technologies, such as 5G networks and beyond, may provide high bandwidths to handle high-volume data transfer that may be used to synchronize instructions between different robotic network components within a pre-defined time error constraint. However, wireless communication between network components often includes additional associated delays, relative to wired communication protocols, that may further complicate and prevent precise synchronization between different robotic network components. For example, wireless communications may be susceptible to delays in wireless transmission/delivery and delays in processing received data. The inventors have appreciated that such additional delays may compound synchronization deviations. For example, such delays may cause deviations between the local clock of the network component and the reference time of a virtual clock domain, thus decreasing the precision of the synchronization. For example, two components operating in concert to perform an industrial process may produce costly, damaging, and/or dangers errors when the two components operate too far out of synchronization. For example, in some applications, delays larger than 1.5 μs may result in errors during manufacturing or damage to the components themselves. Thus, the speed and complexity of components in an IIOT facility may be limited based on the precision of synchronization between the clocks of each component in the virtual clock domain. While wireless operation may be desirable, additional delays added through the use of wireless communications can render conventional techniques inadequate to provide sufficient synchronization among devices using wireless communications. 
     The inventors have further recognized that it can be desirable or necessary to use critical process data in synchronized networks, such as to coordinate scheduled events between different instances of robotic equipment and/or to monitor the status of ongoing process. In some applications, critical process data may rely on signals from various applications and/or devices, such as signals from sensors and actuators in an IIOT facility. However, the inventors have appreciated that as process complexity increases, so too does the complexity of real time data that may be relied on to monitor critical process data for industrial processes. For example, in addition to real-time data, other types of data such as energy data metrics and maintenance reports may also be used in process monitoring. 
     The inventors have therefore recognized and appreciated that providing wireless TSN and real-time enforceable communication for transmitting critical process data, is a challenge to enabling dynamic industrial automation. Examples of industrial automation processes include collaborative robotics applications, high-precision manufacturing automation, closed-loop control applications, robot manufacturing, product packaging, federated multi-agent systems deployed in physical systems, automated production processes, large-scale machine-to-machine communications that are integrated for automation, smart monitoring, improved communications (i.e., Industry 4.0), and other applications. It can be desirable to implement such industrial automation processes using wireless communications via an IIOT facility that leverages critical process data in real-time. For example, it can be desirable to use TSN enforceable communications to provide data in real-time that is used for event scheduling. Enforceable communications provide signals and/or process instructions on a reliable schedule, such that other signal transmissions and/or processes may rely upon timely receipt the communications. For example, Isochronous task execution may rely on enforceable communications implemented through a TSN to synchronize multiple IIOT applications with a dedicated or decentralized system controller. 
     Recognizing the above challenges, the inventors have developed techniques to provide a synchronization protocol that uses, in part, a wireless channel of a network (e.g., a cellular network). In some embodiments, the synchronization techniques can provide sufficient synchronization to support Time-Sensitive Networking according to the standard IEEE 802.1AS. In some embodiments, the techniques can leverage a first synchronization protocol for one or more wired portions of the network, and a second synchronization protocol between the wired network and the wireless devices (e.g., between small cells and UEs and/or other mobile devices). In some embodiments, for example, radio frames of the wireless network can be used to provide wireless synchronization. Such approaches can allow for implementing TSN over cellular networks, such as over 5G networks. As a result, highly sophisticated and closely coordinated architectures can be provided using the techniques described herein that are not otherwise available using conventional approaches. Accordingly, the TSN techniques described herein provide improvements over conventional synchronization technology by allowing for wireless TSN implementations. As described herein, such wireless implementations can address the problems that the inventors have appreciated with wired TSN approaches, including providing for TSN implementations with wireless components, as well as wireless TSN implementations that can leverage critical process data. 
     For example, a cellular network device may implement a computerized method including, receiving, by the cellular network device, timing information from a cellular network node. The cellular network node may be in wired communication with a network clock reference and the cellular network node may be in communication with the network device. The timing information associated with the network clock reference and the timing of the network device is in accordance with the synchronization protocol. The computerized method my further include, determining, by the network device, a timing adjustment based on the timing information, and adjusting, based on the timing adjustment, a timing signal that is transmitted by the network device to a user device in cellular communication with the cellular network node through the network device, where the timing signal is used to adjust a timing of the user device in accordance with the synchronization protocol. 
     II. Exemplary Network Configurations 
     Techniques described herein, such as techniques including a wireless TSN synchronization protocol, to synchronize user equipment with a reference clock over a wireless channel of a cellular network can be employed in various network configurations and utilizing various network protocols. A set of TSN standards devoted to the time-sensitive transmission over Ethernet networks provide for interoperability among different applications. Aspects of the technology described herein relate to improving TSN functionality on a wireless network to provide a wireless TSN. 
     The inventors have appreciated that, to provide a TSN using a wireless network, delays introduced in wireless transmission protocols may decrease the precision of synchronization. To improve the precision of synchronization, in some conventional approaches a UE may include separate, dedicated precision timing equipment, such as GPS equipment, to receive precise timing signals from the dedicated TSN network. A TSN translator may use mobile signals, received through a primary wireless network, and the precise timing signals from the dedicated TSN network to calculate the scheduled timings associated with critical process data. 
       FIG.  1    illustrates an exemplary TSN architecture  100  configured with a 5G network and a dedicated TSN network. TSN architecture  100  includes TSN system  102  communicatively coupled to UE  112  through the Device side of the TSN bridge  110 . UE  112  is further communicatively coupled to network  104  through a logical TSN bridge  120 . Logical TSN bridge  120  provides TSN compatible communications with network  104 . Logical TSN bridge  120  includes device side TSN bridge  110 , (Radio) Access Network (RAN)  122 , User Plane Function (UPF)  124 , network side TSN translator (NW-TT)  126 , Access &amp; Mobility Management Function (AMF)  128 , Session Management Function (SMF)  130 , Unified Data Management (UDM)  132 , Network Exposure Function (NEF)  134 , Policy Control Function (PCF)  136 , and TSN Application Function (TSN AF)  138 . Device side TSN bridge  110  includes user equipment  112  and device side TSN translator  114 . 
     As shown in  FIG.  1   , network components are communicatively coupled by multiple network interfaces, including network interfaces N1, N2, N3, N4, N5, N7, N8, N9, N10, N11, N30, N33, and N52. In the exemplary network configuration shown in  FIG.  1   , UE  112  communicates with (R)AN  122  by exchanging radio frames. Network interface N1 provides connectivity between UE  112  and AMF  128 . Network interface N2 provides connectivity between (R)AN  122  and AMF  128 . Network interface N3 provides connectivity between (R)AN  122  and UPF  124 . Network interface N4 provides connectivity between UPF  124  and SMF  130 . Network interface N8 provides connectivity between AMF  128  and UDM  132 . Network interface N9 provides connectivity between two UPFs. Network interface N10 provides connectivity between SMF  130  and UDM  132 . Network interface N11 provides connectivity between AMF  128  and SMF  130 . Network interface N7 provides connectivity between SMF  130  and PCF  136 . Network interface N52 provides connectivity between UDM  132  and NEF  134 . Network interface N30 provides connectivity between PCF  136  and NEF  134 . Network interface N5 provides connectivity between PCF  136  and TSN AF  138 . Network interface N33 provides connectivity between TSN AF  138  and NEF  134 . The network interfaces are numbered in accordance with 3GPP standards for 5G networks. Although illustrated with reference to 5G network systems, other network configurations are also possible. For example, the techniques described herein could also be applied to other network systems such as 6G network systems or other network systems that could implement TSN, as the techniques described herein are not limited in this respect. 
     The UE  112  and DS-TT  114  are configured as the device side of the TSN bridge  110  to interface TSN system  102  with UE  112  to receive precise timing signals. UE  112  is also coupled to the primary 5G network components that provide C-plane and U-plane functionality. The 5G network components may transmit signals and/or instructions associated with a TSN process to UE  112 . For example, the TSN AF  138  translates control and management plane functions to interact with 5G network resources. The NW-TT ( 126 ) is integrated with the UPF and provides an interface between the 5G system and the internet that translates data plane functions to interact with 5G network resources. The DS-TT provides and interface between the TSN system  102  and UE  112  and is configured to use precise timing signals received from TSN system  102  to translate 5G messages received from the 5G network to UE  112  to implement TSN functionality. TSN translators NW-TT  126 , DS-TT  114 , and TSN AF  138  form a virtual clock domain such that TSN timestamps may be generated/interpreted with reference to a shared reference clock of the virtual clock domain. 
     The inventors have recognized and appreciated that including a TSN translator with the UE typically increases equipment cost and may utilize computationally expensive process to accurately synchronize TSN signals with the primary wireless network. To address these challenges, the inventors have developed techniques for separating the UE TSN facility from the UE by implementing a TSN translator at the wireless cell providing network connectivity to the UE. By implementing the TSN translator at the wireless cell, a high precision synchronization between the UE and the virtual clock domain may be maintained through the wireless network. Implementing the TSN translator at the wireless cell may provide TSN functionality to multiple instances of UE from a single TSN translator which reduces the number of TSN translators used, decreasing the cost and complexity of the UE. The wireless cell translator may use physical layer signals transmitted with the radio frame for synchronization which may increase the synchronization accuracy by reducing the number of signals/networks involved in providing TSN. For example, physical layer signals transmitted with the radio frame including the primary synchronization signal, secondary synchronization signal and extended synchronization signal may be utilized by the network cell to synchronize the UE clock with the virtual clock domain. Physical layer signals may provide for more accurate synchronization than application or transport layer signals/messages.  FIG.  2 A  and  FIG.  2 B  illustrate some of the differences between a network with device side TSN translators and a network with a wireless cell TSN translator. 
       FIG.  2 A  illustrates an exemplary network  200  including a TSN system integrated into a 3GPP network architecture. Network  200  includes controller  202 ; UPF  210 ; NW-TT  212 ; gNodeB (gNB)  220 ; UE  230 ,  232 , and  234 ; DS-TT  242 ,  244 , and  246 ; and equipment instances  250 ,  252 , and  254 . As illustrated in  FIG.  2 A , controller  202  may transmit, using the network provided through UPF  210  and gNB  220 , scheduled signals and/or instructions to UE  230 - 234 . Controller  202  may be implemented as an industrial controller configured to generate time sensitive instructions for UE  230 ,  232 , and  234  to execute automated industrial processes. Controller  202  is communicatively coupled to UPF  210 . UPF  210  includes NW-TT  212  to interface network  200  with the internet. NW-TT  212  is communicatively coupled to the internet and to a grandmaster clock. The NW-TT provides an entry gateway into the 5G network from other network protocols. For example, NW-TT  212  may send/receive packets from the internet through an Ethernet protocol and may transmit/receive packets, through the UPF, in accordance with a 5G packet protocol. To integrate a TSN system into the 3GPP network architecture, independent equipment instances  250 ,  252 , and  254  each have a dedicated UE and DS-TT to translate 5G messages for operating with TSN functionality. The 5G messages may be transmitted using a gPTP protocol. As shown in  FIG.  2 A , each UE  230 ,  232 , and  234  includes a DS-TT  242 ,  244 ,  246 , respectively. DS-TT  242 ,  242 , and  246  each decode 5G packets, transmitted from gNB  220 , and provide the corresponding messages to a listener of for their respective UEs  250 ,  252 , and  254 . 
     As described above, the inventors have appreciated that developing the support of a TSN client for UEs uses dedicated processing resources which may increase the overall complexity of the TSN system, or the costs associated with each instance of equipment. Referring again to the example in  FIG.  2 A , as the number of instances of equipment increases (e.g., adding additional robotic components) the number of mobile UE and DS-TT increases proportionally. Thus, controller  202  may provide instructions to multiple equipment instances to coordinate the execution of processes on different instances of equipment with a common understanding of time established by the virtual clock domain. The TSN system illustrated in  FIG.  2 A  includes n equipment instances of robotic assemblers. To coordinate the n instances of equipment each instance has a corresponding DS-TT, resulting in n DS-TTs. Thus, the cost of scaling additional equipment instances includes proportionally increasing the number of DS-TTs. The inventors have further appreciated that since each DS-TT determines its own local clock time, the jitter between different DS-TTs may compound uncertainties between the local clocks of each equipment instance. Thus, including more equipment instances into a coordinated process results in an increased uncertainty in the synchronization between the included equipment instances. 
     As discussed above, the inventors, having recognized this challenge, have developed techniques that implement the role of the TSN translation using a network cell. In some embodiments, the TSN translator is implemented using a small cell base station (SC) providing gNB functionality to UEs. By implanting the TSN translator using a small cell, the number of TSN translators used to synchronize the UEs may be reduced. Although embodiments described herein reference implementations using a SC, the technology described herein is not limited in this respect. In some embodiments, other network cells may also be used. For some applications small cells may provide increased synchronization precision relative to other network cells. 
       FIG.  2 B  illustrates an exemplary network  204  configured for time sensitive communication (TSC) using a small cell with a small cell integrated TSN Translator (SC-TT), in accordance with some embodiments. Network  204  includes controller  202 , UPF  210 , NW-TT  212 , small cell (SC)  220 , small cell TSN Translator (SC-TT)  240 , and robotic components  250 ,  252 , &amp;  254 . Controller  202 . Controller  202 , UPF  210 , and NW-TT  212  may be configured in accordance with the configuration in  FIG.  2 A . However, in contrast to network  200  in  FIG.  2 A , network  204  reduces the number of TSN translators used to synchronize the robotic components. A single SC configured with SC-TT  240  determines the local times for each equipment instance and transmits signals indicative of the local times for each equipment instance to the respective instance. 
     In some embodiments, controller  202  is configured to coordinate timestamps associated with the TSN facility. In some embodiments, controller  202  is configured to transmit a downlink timestamp to the TSN facility. The downlink timestamp may be associated with a process to be executed by the TSN facility. For example, the downlink timestamps may specify a portion of a process to be executed by one of robotic components  250 - 254  and a time for execution. 
     In some embodiments, controller  202  is configured to receive an uplink timestamp from the TSN facility. The uplink timestamp may be associated with data from sensors and/or manufacturing equipment associated with the TSN facility. For example, time stamped confirmation of process execution or scheduling of execution may be transmitted to controller  202  so that controller  202  may update or schedule subsequent instructions. As another example, sensors or smart monitors may transmit uplink data to controller  202 . Data from the sensors or smart monitors may be used to determine when portions of the process should be executed. 
     As described above, in connection with  FIG.  2 A , NW-TT  212  interfaces network  204  with the internet. For example, in a 5G TSC-enabled network architecture, NW-TT  212  is the interface between the 5G system and the internet. In other embodiments, the network may be a 6G TSC-enabled network architecture. In such embodiments, the NW-TT is the interface between the 6G system and the internet. 
     In  FIG.  2 B , incorporation of TSN synchronization into the SC provides synchronization of the UE with the virtual clock domain using physical layer signals of the wireless network transmitted between the SC and the UE. The SC also provides timestamps and related process information through data encoded within the data frame. Thus, the integration of the TSN functionality with the radio frame enables the UE to receive one signal that includes both the synchronization and reference times used in implementing TSN. In this sense, implementing the UE instance to have high accuracy time synchronization (1.5 μs or faster) may be accomplished by utilize existing low-cost local oscillators that may already be integrated within the electronic systems of the UE and the SC. In this sense, synchronization processes are handled by the small cell and the equipment instances extract the time and synchronization from the 5G radio frame as described in further detail below with reference to  FIGS.  5 - 8   . 
     Referring to  FIGS.  2 A and  2 B , the SC-TT, of  FIG.  2 B , may improve the synchronization precision, relative to the gPTP integration with a dedicated TSN network of  FIG.  2 A , both by providing precise synchronization signals and by reducing the impact of translation errors. As an example, in the 3GPP configuration of  FIG.  2 A , the gPTP protocol ends at each UE and transmits separate signals for each UE. From the perspective of the dedicated TSN network, each UE is an end station where the translation of the gPTP protocol to the TSN protocol is performed. By contrast, in  FIG.  2 B , the gPTP protocol terminates at the small cell. Thus, from the perspective of the TSN GM, the small cell is the end point of the gPTP protocol and a single TSN translator converts the gPTP protocols into TSN protocols for multiple UEs. This approach reduces the compounding of errors that may be present when translating between protocols. If there are any errors in translating between protocols, then each UE receiving signals from the same SC will be subject to the same error. Thus, the local clocks between each UE will still be synchronized together with a precision unaffected by the translation error. 
     In some embodiments, the modem in the SC includes dynamic resource schedulers that take into account the link delay between the SC and each equipment instance. The dynamic resource schedulers may also account for the residence time between the NW-TT and the SC-TT. In this configuration, the time differences between equipment instances are monitored at the edge of the network, independent of residence time delays, providing more precise timing keeping. 
     In some embodiments, the individual signals for different UEs are broadcast together in a multiplexed configuration such that the signals configured for different UEs in the TSN do not interfere with each another. For example, a small cell may operate in Time-Domain Division (TDD) mode, such that the signals configured for different UEs do not interfere. In network configurations with multiple small cells operating in concert to provide a multi-SC TSN, the SCs may additionally configure signals such that the signals from different small cells do not interfere using techniques such as TDD, beam forming, beam steering, and/or beam switching. For example, the transmissions of the different cells in a TDD network may be synchronized to avoid intercell and inter-subframe interference. In some embodiments, a local and/or private industrial network may include multiple SCs to provide TSN of UEs across a large industrial network. For example, multi-SC networks may transmit signals according to 3GPP standards such as TS 38.104. 
     III. Synchronization Technique 
     As described above, the inventors have recognized and appreciated that providing a wireless TSN network provides challenges. Implementations that use a dedicated TSN system, separate from the primary wireless network, may increase complexity and cost of the UEs. To address the above-described challenges, the inventors have developed a physical-layer procedure which disciplines the device clock, using a timing signal extracted from the 5GNR radio frame slot or OFDM symbol to achieve the desired synchronization accuracy. In some embodiments, the SC-TT embedded in the small cell is a gPTP instance that guarantees the synchronization and the accuracy of the 5G NR radio frame to enforce the synchronization and the accuracy of the 5G NR radio frame to maintain enforcement of the synchronization across the 5G industrial network. 
       FIG.  3    illustrates a private industrial network  300  with a small cell that includes a TSN translator, in accordance with some embodiments. Private industrial network  300  includes multiple small TSC enabled small cells (TSC-SC), the first small cell  310 , second small cell  320 , and third small cell  330  each communicate with UPF  301  for access to the internet and industry controller  304 . Each TSC-SC may provide wireless connectivity to multiple equipment instances. NW-TT  305  provides an interface between the 5G system and the internet. Equipment instances  312 ,  314 ,  316 ,  324 , and  334  with UE clocks  313 ,  315 ,  317 ,  326 , and  336  wirelessly communicate with small cells  310 ,  320 , and  330 . 
     Network components have a local clock for local time keeping. The local clocks may all be synchronized to a reference clock to provide a common understanding of time across the different network components, forming a virtual clock domain. For example, a grand master clock  308  may provide a time from an atomic clock, such as atomic clock affiliated with the GPS system or with a national time keeping standards system. Controller clock  306  is synchronized with reference clock  302  and provides a controller with a local time which may be used in scheduling events or interpreting incoming signals. 
     As shown in  FIG.  3   , SC1 clock  312  and SC2 clock  322  are synchronized with reference clock  302 , and UE clocks  313  and  315  are synchronized with SC1 clock  311 . The synchronization of the UE clocks with a SC clock and synchronization between the SC clock and the reference clock provide synchronization between the UE clocks and the reference clock. In this way, each clock in the virtual clock domain has a common reference time. Thus, when the controller schedules instructions for Robot 1 and Robot 2 to coordinate an assembly process, both Robot 1 and Robot 2 will be able to execute their respective portions of the assembly process at the prescribed time without interfering with each another. In some embodiments, the virtual clock domain accuracy is better than 1 μs. In some embodiments, the virtual clock domain accuracy is better than 0.5 μs. In some embodiments, the virtual clock domain accuracy is better than 250 ns. 
     The SC that provides access for UEs to the core network may communicate with other network components through wired connections, and communicate with the UEs through wireless connections, in accordance with some embodiments. For example, the small cells  310 ,  320 , and  330  and industry controller  304  are each in wired connection to UPF  301 , as indicated with solid lines. Small cells  310 ,  320 , and  330  wireless communicate with equipment instances  312 ,  314 ,  316 ,  324 ,  334  as indicated by the three-arc wireless symbol. In some embodiments, the wired connection may communicate using an Ethernet protocol. 
     In some embodiments, the wireless connections may communicate through a 5G 3GPP protocol. In other embodiments, the wireless connections may communicate through a 6G 3GPP protocol. In yet other embodiments, the wireless connections may be compatible across generations of 3GPP protocols. For example, the wireless connections may communicate with some UEs using a 5G protocol and with other UEs using a 6G protocol. In some embodiments, the wireless connection used to communicate with UEs may depend on available resources, quality of service, and/or anticipated bandwidth requirements. In other embodiments, other wireless communication protocols capable of being integrated with a TSN system may be used, as aspects of the technology described herein are not limited in this respect. 
     Network components that communicate through wired connections may be synchronized through a first timing protocol, and network components that communicate through wireless connections may be synchronized through a second timing protocol. In some embodiments, the first timing protocol may be a gPTP protocol. In  FIG.  3   , Network components that communicate though the gPTP protocol are connected with dashed lines while clocks that are synchronized using a wireless TSN protocol are connected with dash-dot lines. 
     As a result of the synchronization techniques described in connection with  FIG.  3   , network components that communicate through wired connections and network components that communicate through wireless connections form a virtual clock domain.  FIG.  4 A  illustrates a virtual clock domain including network components illustrated in  FIG.  3   , in accordance with some embodiments. A virtual clock domain enables coordination of otherwise independent clocks across the nodes of the network to provide a distributed common timescale with a defined accuracy. The accuracy of a virtual clock domain is based on the uncertainty of each clock relative to the reference time. As shown in  FIG.  3   , grand master clock  308  provides a reference time to the UPF to maintain synchronization of reference clock  302 . Controller clock  306  is synchronized with reference clock  302  and provides a controller with a local time which may be used in scheduling events or interpreting incoming signals. SC1 clock  312  and SC2 clock  322  are synchronized with reference clock  302 . UE clocks  313  and  315  are synchronized with SC1 clock  312  and, by extension, reference clock  302 . In this way, each clock in the virtual clock domain has a common reference time. Thus, when the controller schedules instructions for Robot 1 and Robot 2 to coordinate an assembly process, both Robot 1 and Robot 2 will be able to execute their respective portions of the assembly process at the prescribed time without interfering with each another. In some embodiments, the virtual clock domain accuracy is better than 1.5 μs. In some embodiments, the virtual clock domain may have other accuracies, as described herein. 
     In some embodiments, the synchronization may have an accuracy of 1.5 μs. A synchronization accuracy of 1.5 μs may provide the timing between small cells in the network to be within 1.5 μs of the reference clock. In  FIG.  4 A , the time kept by reference clock  302  and the time kept by the first SC1 clock  311  may be within 1.5 μs of each other. Additionally, the time kept by SC1 clock  311  and the time kept by SC2 clock  322  may be within 1.5 μs of each other. The timing between UEs communicatively coupled to the same small cell may each be synchronized to within 1.5 μs. For example, the time kept by UEs clocks  313 ,  315 ,  317  communicatively coupled to SC  310  may be within 1.5 μs of SC1 clock  311 . Additionally, the timing between UEs that are communicatively coupled through different small cells may be synchronized to within 1.5 μs. For example, time kept by UE clock  326  may be within 1.5 μs of the time kept by UE clock  313 . 
     In connection with providing TSN functionality, the network should provide message delivery with guaranteed delivery of the time-constrained messages and/or signals. To provide the guarantee of message delivery, Quality of Service (QoS) policies may be implemented to prioritize the performance of different types of traffic and/or traffic coming from different UEs. In some embodiments, the QoS may be implemented through the deployment of a dedicated Network Slice. Network Slices are isolated, virtual end-to-end networks configured to fulfil specific parameters and/or requirements. For example, a network slice may be configured to provide specific QoS requirements in terms of latency and reliability of the TSN application. 
       FIG.  4 B  illustrates network  400  including a dedicated virtual TSN slice, in accordance with some embodiments. As shown in  FIG.  4 B , resources from the AMF and UPF may be dedicated to the virtual TSN slice. In some embodiments, network resources that provide access to the AMF and UPF may allocate dedicated resources to the separate network slices providing different services. Virtual network slices may be implemented by dedicating a portion of computing capacity to provide a dedicated function or service to devices communicating with the network slice. In some embodiments, the TSN slice  410  may be deployed together with a standard network slice  420  to support the standard 5G smartphones  422  and UEs  412  as shown in  FIG.  4 B . For example, the TSN slice  410  may include dedicated resources from the AMF  410 A and UPF  410 B to provide functionality to the UEs  412 . Additional AMF  420 A and UPF  420 B resources may be allocated to a virtual eMBB slice  420 . The eMBB slice  420  provides 5G network communication to smartphones  422 . In some embodiments, network  400  may include additional slices to provide different functionalities and/or quality of service. 
       FIG.  5 A  illustrates end-to-end synchronization process  500 , in accordance with some embodiments described herein. As shown in  FIG.  5 A , the end-to-end synchronization provides synchronization of an industrial internet of things (IIOT) UE  508  with a grand master (GM) clock  502 . Synchronization between the GM  502  and the UE  508  may use a first timing protocol for receiving a reference time and a second timing protocol for enforcing synchronization of UE  508 . For example, UPF  504  may include a NW-TT for encoding timing signals in accordance with a 5G network protocol. SC  506  may include SW-TT to decode timing signals from UPF  504  and to synchronize the first timing protocol with the second timing protocol. SC  506  may use the second timing protocol to synchronize UE  508  to the reference time of GM  502 . 
     In some embodiments, UPF  504  receives sync message  510  from GM  502 . Using sync message  510 , UPF  504  may implement a first timing protocol to synchronize UPF  504  with SC  506 , where NW-TT and SW-TT implement a synchronization protocol in accordance with a Precision Time Protocol. For example, NW-TT and SW-TT may implement synchronization using the IEEE 802.1AS standard. Implementation may be in accordance with the 3GPP TS 23.501 specification. The 5G network may be transparently integrated with the TSN network. In some embodiments, integration between the 5G network and the TSN network may be implemented as a bridge in accordance with IEEE 802.1 standards. 
     UPF  504  uses sync message  510  to update the local clock at the UPF. In some embodiments. NW-TT updates UPF timing  522  according to IEEE 802.1AS. In some embodiments, GM  502  may directly communicate with UPF  504 . In some embodiments, UPF  504  may indirectly receive sync message  510  from GM  502 . For example, network  500  may include multiple UPF facilities, and UPF  504  may receive sync message  510  from an intermediary UPF, where the intermediary UPF is in direct communication with GM  502 . In some embodiments, network  500  may include multiple intermediary UPFs, and UPF  504  may receive multiple sync messages to determine which intermediary UPF can provide sync message  510  with the shortest latency. 
     As described above in connection with  FIG.  2 B , the first timing protocol, implemented using the NW-TT and SW-TT, may treat the SC as the endpoint of the TSN timing domain. For example, the synchronized time at the SC in the first timing protocol may be represented by the following equation: 
       τ sc =τ 0 +δ link delay   +T   residence   Equation 1
 
     In Equation 1, τ sc  is the synchronized time of the SC; τ 0  is the reference time, received from the grandmaster clock; δ link delay  is the propagation time of the packet, including the sync message, through the cable from the GM to NW-TT; and T residence  is the residence time between the UPF and the SC expressed in GM time base. The link delay may be calculated according to the IEEE 802.1AS standard. The residence time is measured using ingress timestamps (t si ) and egress timestamps (t se ). For example, the t si  is recorded when sync message  510  is received at UPF  504 , and t se , is recorded when sync message  512  is received at SC  506 . The residence time may be represented by the following equation: 
         T   residence   =t   se   −t   si ×RateRatio  Equation 2
 
     In Equation 2, the rate ratio is the ratio between the frequency of the GM clock to the local clock of the SC. The RateRatio may be determined according to the IEEE 802.1AS standard. 
     Referring again to  FIG.  5 A , SC  506  uses sync message  512  to update the local clock at the SC. In some embodiments, SC-TT updates the SC timing according to IEEE 802.1AS. Following the update of the SC clock by the SC-TT, GM  502 , UPF  504  and SC  506  are synchronized. In some embodiments, GM  502 , UPF  504 , and SC  506  are synchronized according to 3GPP 23.501 release  16  for downlink synchronization and 3GPP 23.501 release  17  for uplink synchronization. 
     The second timing protocol  532  synchronizes SC  506  and UE  508 . The second timing protocol may be implemented using physical layer signals of the 5G NR radio frame to enforce relative synchronization between SC  506  and UE  508 . Once synchronized, SC  506  may use time information encoded in the 5G NR radio frame to determine the actual synchronization time. In some embodiments, the time that the radio frame is received may be synchronized with the timing interval of the virtual clock domain such that the UE may use the arrival of the radio frame and the time information to determine a synchronization time. In some embodiments, the time information encoded in the 5G NR radio frame may include System information block 9 (SIB9) that includes Coordinated Universal Time (UTC) data. In some embodiments, the 5GNR radio frame is transmitted using the Radio Resource Control (RRC) protocol with the timing information encoded in SIB9. 
     In some embodiments, the UE may perform the Random-Access Procedure to register with the SC to initiate data transmission. The SC may use the Random-Access Procedure to determine the timing advance (i.e., the time it takes for signals to travel between the SC and the UE). The timing advance may be used in connection with determining the synchronization time, as described herein. 
     The internal clock cycle of UE  508  may be adjusted based on the arrival time of the radio frame and the decoded UTC data such that the UE  508  will be synchronized with the arrival time of the radio frame. Additionally, the arrival time may be used as a reference relative to the time encoded in the information block. For example, by synchronization of the discrete time periods of the UE, with timing intervals of the virtual clock domain, the UE may precisely determine when the reference time, encoded in the information block, was counted. In discrete time, the time incrementally jumps from one time period to the next. If the time period for a clock is 1 μs, then time would incrementally count in 1 μs increments. Clocks may use a periodic signal, such as a square wave, with a periodicity corresponding to the desired time period to count incrementally. At each falling edge of the square signal, the clock adds one increment to the current time of the clock. When the virtual clock domain and the UE  508  clock have unsynchronized time periods, the offset between the falling edge of the UE clock and the incrementing of time in the virtual clock domain introduces additional uncertainty into the synchronization. However, when the falling edge of the UE clock is synchronized with the incrementing of time in the virtual clock domain, UE  508  may precisely determine when a time occurs in the virtual clock domain. In some embodiments, the virtual clock domain and the UE may increment time on the same interval. In some embodiments, the virtual clock domain and the UE may increment time on different intervals and may synchronize on a common multiple of the two intervals. 
     Although the synchronization of the internal clock described herein uses the example of the falling edge for counting, other counting schemes may be used, as aspects of the technology described herein are not limited in this respect. For example, the rising edge of the periodic signal may be used. As another example, both the rising edge and the falling edge of the periodic signal may be used. 
       FIG.  5 B  illustrates process  545  of synchronizing the internal clock of the UE with the virtual clock domain, in accordance with some embodiments. Prior to the start of process  545 , UE may be in a searching state. While searching, the UE may be on standby, the UE scans for synchronization signals transmitted from a wireless network. In some embodiments, the UE scans New Radio Absolute Radio-Frequency Channel Numbers (NR-ARFCNs) for synchronization signals. 
     Process  545  begins at block  546 , where a UE identifies a synchronization signal associated with an NR-ARFCN for receiving downlink synchronization signals from a small cell, in accordance with some embodiments. The UE may include a 5GNR modem configured to communicate with a 5G network. In some embodiments the 5GNR modem may identify wireless synchronization signals associated with the 5G network. For example, the 5GNR modem may identify the Primary Synchronization Signals (PSS), the Secondary Synchronization Signal (SSS), and/or the Extended Synchronization Signals (ESS) in the Synchronization Signal Block (SSB) of the Radio Frame. 
     In other embodiments, the UE may include a modem configured to identify synchronization signals of other mobile networks, such as a 6G wireless network. In some embodiments, the modem may be configured to communicate with any wireless network that is compatible with implementing TSN, as aspects of technology described herein are not limited in this respect. 
     At block  547 , once the 5GNR modem has identified the SSB, the modem executes a downlink synchronization process, in accordance with some embodiments. The downlink synchronization process synchronizes the frequency and the phase of the UE&#39;s radio transmitter and receiver with the SC. This procedure may use a Time Locked Loop (TLL) circuit to synchronize the UE&#39;s radio transmitter and receiver with the SC&#39;s radio transmitter and receiver. After the synchronization between the RF signal components of the UE and SC, the frequency and phase are synchronized. 
     At block  548 , the UE determines the reference time, in accordance with some embodiments. To determine the reference time, the UE decodes System Information Block 9, which contains the information elements that may be used to determine the reference time at the SC clock. For example, the information elements decoded from System Information Block 9 may include the UTC reference time, leap seconds, and the UTC local time offset. 
     At block  549 , the 5GNR modem determines the timing advance from the SC, in accordance with some embodiments. To determine the timing advance from the SC, the 5GNR modem initiates a connection process to the 5G network. For example, the 5GNR modem may initiate a connection through the Random-Access procedure on a random-access channel (RACH) of the network. Using the Random-Access procedure, the TSN-enabled SC determines the Timing Advance. The Timing Advance is the time that the radio signal takes to be transmitted from the UE to the TSN-enabled SC, as described herein. The TSN-enabled SC extracts the Timing Advance from the RACH response. The Timing Advance may be updated by the SC as the UE moves, transmission path changes, and/or the connection is interrupted. The UE may transmit a MAC Control Element, to indicate that the Timing Advance should be updated. 
     At block  550 , the SC executes synchronization protocols of the UE clock using physical layer signals and subframe data, in accordance with some embodiments. The SC executes synchronization by transmitting physical layer signals of the radio frame, synchronized with the virtual clock domain, and transmitting timing data encoded in the radio frame. In some embodiments, physical layer signals associated with subframes of the radio frame may be used to synchronize the UE clock to the virtual clock domain of the TSN network by adjusting the transmission of the slot indication signal to correspond with the time of the virtual clock domain. For example, the first slot (Slot #0) of the first subframe (Subframe #0) of a radio frame will be coincident with a timing interval of the virtual time domain. The coincident arrival of the radio frame combined with the UTC time information decoded from the radio packet provides synchronization between the UE and SC that supports TSN. In some embodiments, a boundary signal associated with a symbol of the radio frame may be used to indicate the time of the virtual clock domain. The synchronization protocol is discussed in further detail below, with respect to  FIG.  5 C . 
     At block  551 , following the synchronization of the UE clock to the virtual clock domain, the UE clock uses subsequent physical layer signals to keep the system synchronized in a loop operation, in accordance with some embodiments. The UE clock uses the physical layer signals to keep the frequency and phase synchronized during downlink and uplink transmissions. For example, when the UE receives subsequent slot indication signals, the UE may check and/or update the synchronization of the UE clock with the virtual clock domain. As another example, when the UE receives subsequent boundary signals associated with symbols of the radio frame, the UE may check and/or update the synchronization of the UE clock with the virtual clock domain. 
     As described above, enforcing scheduled events through a TSN is limited by the synchronization of the virtual clock domain that includes the UE performing the scheduled events. The internal clock signals used to transmit and receive wireless signals are very precise and may utilize picosecond, or even sub-picosecond precision for sampling frequencies to receive and transmit signals of a 5G network. The timing of these internal clocks, used for frequency sampling, may be adjusted frequently to account for changes in pathlength between the signal transmitter and receiver, multi-path transmission, and the time-variant conditions of the propagating radio frames. Thus, the timing of internal clocks may change relative to the time of a virtual clock domain. The inventors have recognized and appreciated the precise internal clocks, used to maintain the frequency and phase of the wireless signals, may be used to provide precise time keeping when provided with a reference time for translating the clock signals into a local time. 
     The inventors, having recognized that physical layer signals are faster than application or transport layer signals, have developed synchronization protocols that use physical layer signals as reference times, that reference the encoded times transmitted in the radio frame, to synchronize the local clock on a UE with the virtual clock domain. In some embodiments, the synchronization of the local clock on the UE with the virtual clock domain supports TSN functionality. 
       FIG.  5 C  illustrates a computerized TSN synchronization protocol, in accordance with some embodiments. Prior to the start of process  550 , a UE may synchronize with a SC, as described above in connection with blocks  546 - 549  of process  545  above. In some embodiments, process  550  may be configured to support TSN according to the IEEE 802.1AS standard. Other standards that support TSN with sub-millisecond synchronization of components in the virtual clock domain may also be used, as aspects of the technology described herein are not limited in this respect. 
     Process  550  begins at block  561  where a SC receives timing information from a cellular network node, in accordance with some embodiments. The cellular network node may be in wired communication with the network reference clock. Through the wired connection between the cellular network node and the network reference clock, the cellular network node receives timing signals indicative of a reference time of the reference clock. The cellular network node is also in wired communication with the SC. The SC receives timing signals, through the wired communication with the cellular network node, indicative of the reference time from the network reference clock. 
     In some embodiments, the timing information, received by the SC, is associated with the network clock reference and the timing of the SC in accordance with the synchronization protocol. For example, the timing information may be a gPTP message that includes the residence time and transmission delays of the signal as it is transmitted to the SC. 
     In some embodiments, the SC may be a TSN-enabled SC. The TSN-enabled SC may be configured to provide wireless network access to UEs through wireless protocols. The wireless protocols may include any wireless protocol capable of providing TSN. For example, the wireless protocols may include a 5G wireless protocol. As another example, the wireless protocol may include a 6G wireless protocol. 
     In some embodiments, the cellular network node may be a UPF network component. The UPF network component may use Ethernet protocols to communicate through the wired connections to the reference clock and the UE. In some embodiments, the UPF network component may include multiple UPF network components as part of a network topology. 
     Next at block  562 , the SC determines a timing adjustment based on the timing information, in accordance with some embodiments. The timing information includes the reference time and residence time of the packets as they are transmitted from a grandmaster clock to the SC. The residence time is further described above in connection with  FIG.  5 A . In some embodiments, the timing information also includes a timing advance (i.e., the time for the RF signal to travel from the SC to the UE&#39;s receiver). From the timing information, a virtual clock domain time is determined at which the UE will receive the radio frame transmitted from the SC. The synchronization time represents the time, in the virtual clock domain when the radio frame will arrive at the UE. The synchronization time is further described below, in connection with  FIG.  7   . 
     In some embodiments, the timing advance may be determined prior to the start of process  550 . For example, the timing advance may be determined in connection with the initial synchronization between the 5GNR modem and the network, where the frequency and phase of the UE modem are synchronized with the frequency and phase of the transmit/receive components of the SC. The timing advance may be determined using the random-access process described above, in connection with  FIG.  5 B . 
     In some embodiments, the timing advance may be determined during the synchronization protocol to account for any changes in beam path, beam propagation, and/or movement of the UE relative to the SC. In some embodiments, the timing advance may be recalculated whenever the UE moves or there is a disruption in communication between the SC and the UE. 
     Next at block  563 , the SC adjusts the timing signal that is transmitted to the UE, in accordance with some embodiments. The SC adjusts a timing signal of the radio frame to adjust the timing of the UE clock. In some embodiments, the timing signal of the radio frame may be a physical layer signal. For example, the timing signal may be a slot indication signal, as described herein. As another example, the timing signal may be a symbol boundary signal, as described herein. 
     In some embodiments, the timing signal received by the UE is used in combination with a timing feedback circuit to adjust the internal clock flank of the UE. The feedback circuit is configured to adjust the timing of the internal clock flank such that the flank is coincident with subsequent timing signals. The synchronization of the UE clock to the virtual clock domain using a physical layer signal of the wireless network is discussed in further detail below in reference to  FIG.  6 A — FIG.  8   . 
       FIG.  6 A  is a schematic of a radio frame  600  that may be used in accordance with the embodiments described herein.  FIG.  6 A  illustrates a radio frame that is subdivided into 10 subframes  602 ,  604 ,  606 ,  608 ,  610 ,  612 ,  614 ,  616 ,  618 , and  620 . Each of the subframes includes one or more slots. In radio frame  600 , each subframe  602 - 620  includes two slots. The two illustrated slots  631  and  632  correspond to subframe  602 . Each slot includes 14 symbols, as indicated by symbols  642 ,  644 ,  646 ,  648 ,  650 , and  652  that each correspond to slot  631  in  FIG.  6 A . 
     The number of slots in a subframe is determined by the subcarrier spacing (i.e., subcarrier bandwidth). In the illustrated exemplary radio frame  600 , the subcarrier spacing is 30 kHz. However, other common subcarrier spacings that would be supported by a wireless network may be used. For example, subcarrier spacings of 15 kHz, 60 kHz, 120 kHz, and 240 kHz may be used. When a subcarrier spacing of 15 kHz is used, each subframe includes a single slot. When a 60 kHz, 120 kHz, or 240 kHz subcarrier spacing is used, the respective subframes will have 4, 8, or 16 slots. 
     The duration of radio frame  600  is 10 ms and includes 10 subframes. Each subframe includes a variable number of slots and each slot, regardless of the subcarrier spacing, includes 14 symbols. Therefore, as the number of slots per subframes increases, the symbol duration decreases, because the subframe duration is constant. The number of slots and the slot duration depends the on subcarrier spacing. For example, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz correspond to 1 slot per subframe, 2 slots per subframe, 4 slots per subframe, 8 slots per subframe, and 16 slots per subframe with slot durations of 1 ms, 0.5 ms, 0.25 ms, 0.125 ms, and 0.0625 ms respectively, that have symbol durations of 71.42 μs, 35.71 μs, 17.86 μs, 8.93 μs, and 4.46 μs respectively. 
     The configuration of symbols within a slot may be configured as downlink, uplink, or flexible (i.e., either uplink or downlink) symbols. A slot indicator signal may be transmitted to the UE to specify the symbol allocation within each slot. In some embodiments, the slot indicator may be transmitted using a DCI protocol. The slot indicator may include an indication of the periodicity of the symbols configured in a downlink-uplink pattern, a number of consecutive full downlink slots at the beginning of each downlink-uplink pattern, a number of consecutive downlink symbols in the beginning of a partially-filled slot, a number of consecutive full uplink slots at the end of each downlink-uplink pattern, and/or a number of consecutive uplink symbols at the end of a partially-filled slot. In some embodiments, the slot indicator may be configured in accordance with other formats which are configured to provide the UE with an indication of slot and/or symbol usage. 
     In some embodiments, a slot indication signal may be transmitted, by the SC, such that the arrival of the slot indication signal corresponds with a flank signal of the SC clock.  FIG.  6 B  illustrates a schematic of the timing between the SC clock flank signal and subframes of the radio frame, in accordance with some embodiments.  FIG.  6 B  illustrates slots  631 ,  632 ,  633 ,  634 , and  635  that are the first five slots of radio frame  600 . Prior to transmitting the payload of each slot, indication signals  661 ,  662 ,  663 ,  664 , and  665  are each transmitted to the UE. The timing of the UE clock flank signals  671 ,  672 ,  673 ,  674 , and  675  are illustrated by vertical dashed lines. 
     In  FIG.  6 B  time progresses along the x-axis, increasing from left to right. The first five subframes of a radio frame are transmitted to a UE and the position of the slots indicate the arrival time of each respective slot at the UE. As indicated by the vertical alignment of the slots, slot indication signals, and the flank signal of the UE clock, each are synchronized in time. Thus, the slot indication signals may act as a reference time for translating the clock signals into a local time when the arrival of the slot indication signal corresponds to the time data encoded in the time information block of the radio frame. To provide synchronization with the reference time, the SC transmits the slot indication such that it arrives at an even timing interval of the reference time. In the illustrated embodiments of  FIGS.  6 A &amp;  6 B , the subcarrier spacing is 30 kHz. Thus, the slot duration is 500 μs, and a new slot indicator is transmitted every 500 μs. In the illustrated example of  FIG.  6 B , the time format is hours:minutes:seconds:milliseconds microseconds nanoseconds. The slot indicators are transmitted such that they arrive at the UE when the reference time is integer multiple of 500 μs. Slot indication signal  661  arrives at the UE when reference time is 16:30:23:000 000 000. Slot indication signal  662  arrives at the UE when the reference time is 16:30:23:000 500 000. Slot indication signal  663  arrives at the UE when the reference time is 16:30:23:001 000 000. Slot indication signal  664  arrives at the UE when the reference time is 16:30:23:001 500 000. Slot indication signal  665  arrives at the UE when the reference time is 16:30:23:002 000 000. 
     The enforcement of the arrival time of the indication signals enables the UE to maintain precise synchronization with the reference clock between slot indication signals by using the precise internal clock, used to maintain frequency and phase synchronization. In some embodiments, the UE may use every slot indication signal to check and/or adjust the synchronization of the UE clock. In some embodiments, the UE may only check and/or adjust the synchronization of the UE clock using one or more slot indication signals per radio frame. The UE may check and/or adjust the synchronization of the UE clock using any number of slot indication signals that provides the degree of synchronization required for a given process. The degree of drift of the UE clock relative to the reference time, the distance from the UE to the SC, the velocity of UE, and the particular process being executed by the UE may factor into determining how frequently to check and/or adjust the synchronization of the UE clock using one or more indication signals. 
     As described above, the slot indication signal is a physical layer signal. In some embodiments, other physical layer signals may be used to indicate for the synchronization between the SC and UE. The system can implement an OFDM symbol-based synchronization to improve synchronization accuracy. Each slot includes 14 OFDM symbols and by using the symbol boundary, as the synchronization signal, the deviation between the disciplining signal (i.e., the symbol boundary) and the reference clock is reduced. For example, a Time-Locked Loop (TLL) system may implement the synchronization with the reference clock of the virtual clock domain. In some embodiments, the minimum precision of the synchronization achievable when using the symbol boundary, as the synchronization signal, depends on the subcarrier spacing that is used. In some embodiments, signals encoded in a subset of the symbols of the data frame, such as a pattern of synchronization signals, may be used as the synchronization signal. For example, the PSS and/or SSS may be used as the synchronization signal. 
     The subcarrier spacing determines the symbol duration, and in the event that the signals get disrupted or an error occurs, and the symbol synchronization is lost, the subsequent symbol will reestablish synchronization. In such cases, the synchronization procedure may provide a minimum precision that is comparable with the symbol duration. For example, when using a subcarrier spacing of 15 kHz, the symbol duration is provided by the following equation. 
     
       
         
           
             
               
                 slot 
                 ⁢ 
                     
                 duration 
               
               
                 number 
                 ⁢ 
                     
                 of 
                 ⁢ 
                     
                 symbols 
                 ⁢ 
                    
                 per 
                 ⁢ 
                     
                 slot 
               
             
             = 
             
               
                 
                   1 
                   ⁢ 
                       
                   ms 
                 
                 
                   1 
                   ⁢ 
                   4 
                 
               
               ≈ 
               
                 71 
                 ⁢ 
                     
                 μs 
               
             
           
         
       
     
     As another example, when using a subcarrier spacing of 30 kHz or 60 kHz the minimum precision is approximately 36 μs and 18 μs respectively. 
     For transmitting radio frames between the SC and a UE, the transmitter and receiver are synchronized in frequency and phase. In some embodiments, the radio frame is transmitted over frequencies smaller than 3 GHz. In some embodiments, the radio frame is transmitted over frequencies between 3 GHz and 6 GHz. In some embodiments, the radio frame is transmitted at frequencies larger than 6 GHz. The period of frequencies greater than or equal to 1 GHz correspond to a period of oscillation of less than or equal to 1 ns. Thus, the synchronization of the frequency and phase, used for transmitting and receiving, may be within 1 ns. In some embodiments, the synchronization in frequency and phase is used to count local time of the UE clock from the last synchronizing signal. In some embodiments, the precision of synchronization between the UE clock and the SC clock are synchronized to within 100 ns, 10 ns, or 1 ns. 
     In some embodiments, the timing signals may be used to continuously adjust the UE clock to enforce synchronization between the UE and the SC. In some embodiments, the periodicity of adjusting the UE clock is based on a desired accuracy associated with process instructions, as described herein, and/or a set QoS. In some embodiments, the periodicity of adjusting the UE clock based on received timing signals may vary according to a set of instructions associated with a process performed by the UE. 
       FIG.  7    illustrates process  700  of adjusting the UE timing system based on the timing signal received by the UE, in accordance with some embodiments. The UE determines an offset, A, between the timing signal and an internal clock flank of the UE timing system (i.e., internal clock). In the illustrated embodiment, the offset  702  between slot indication  661  and the internal clock flank  671  is determined by the UE. To determine the synchronized time of the UE, that would synchronize the UE with the virtual clock domain, the UE uses the reference time, the timing advance, and the offset, as described by the following equation: 
       τ Synchronized Time =τ Reference Time +τ Timing Advance ±Δ Timing Signal   Equation 3
 
     In Equation 3 T Reference Time is the time of the virtual clock domain at the time of transmission, τ Timing Advance  is the time for a signal to travel between the SC and the UE, and Δ Timing Signal  is the time between the arrival of the physical layer signal at the UE and the next clock flank. The offset Δ Timing Signal  may also be used to by a timing feedback circuit to adjust the internal clock flank to be coincident with subsequent timing signals. 
       FIG.  8    illustrates a time locked loop feedback circuit  800 , in accordance with some embodiments. In some embodiments, time locked loop  800  uses the time output for feedback, instead of using the phase. The Time Locked Loop maintains the phase alignment between the transmitted and received signals while providing adjustments to the clock signal. In some embodiments, timing feedback circuit functions like a PLL (Phase Locked Loop) that operates in the time domain instead of the phase domain. For example, the time locked loop includes controlled oscillator  802 , real-time clock (counter)  804 , time comparator  806 , and loop filter  808 . In some embodiments, controlled oscillator  802  generates periodic timing signals. The periodic timing signals are used by real-time counter  804  to count time and produce a time-out signal. The time-out signal is provided as feedback to time comparator  806  that compares the computed time-out with a reference time-in signal. Time comparator  806  result is filtered by loop filter  808  and provided as input to controlled oscillator  802 . 
       FIG.  9    illustrates an exemplary implementation of TSN network  900  including a 5G small cell and UE, in accordance with some embodiments. TSN network  900  includes a TSN-enabled small cell (TESC)  902  configured to provide 5G network connectivity to UE  910 . TESC  902  transmits radio frame  912  to UE modem  914  with timing advance  904  such that the arrival of the physical layer signals, of the radio frame  912 , correspond to the time encoded within the timing block of radio frame  912 . The interface between modem  914  and main processor  916  includes the Clock Signal, which is network synchronized, and the Network Time in the form of a timestamp that includes the timing advance. Main processor  916  can use the Network Time to schedule the real time actions to be performed by actuator  918 . 
     In some embodiments, modem  914  extracts PSS and SSS, from the 5GNR Frame  912 , to generate the signals for synchronizing the local clock with the Network Time. This solution enables implementation of a Virtual Clock Domain or TSN network between the UE  910 , the 5G SC base station  902  and a reference clock of the system. The TSN network guarantees that the clock accuracy will be better than 1.5 μs, in accordance with some embodiments described herein. 
       FIG.  10    illustrates an exemplary TSN registration and execution request, in accordance with some embodiments. In the embodiment illustrated in the  FIG.  3   , the application implements a client-server architecture. The client-server architecture includes a dedicated controller  1004  that is an industrial controller. As shown in  FIG.  10   , the UE  1002  may establish an application-layer communication with the controller. To establish an application layer communication, UE  1002  transmits device registration request  1010  to controller  1004  to register the UE on the system that receives instructions from the controller. Device registration request  1010  may signal a device user ID (UID) and if the device supports the 5g-radio-frame-based-synchronization (i.e., wireless TSN capable) and a synchronization accuracy. As discussed above, for some applications, the synchronization accuracy will be impacted by the numerology (i.e., subcarrier spacing). Controller  1004  responds with device registration response  1012 . After the registration, controller  1004  can send, to the UE  1002 , action execution requests that are time-aligned and include an execution timestamp, action ID, and any optional parameters. For example, Controller  1004  may transmit action execution request  1020  to UE  1002  specifying the time for execution of the action by UE  1002 . In response, UE  1002  may respond by transmitting action execution response  1022 , confirming execution of the scheduled action. Controller  1004  may transmit additional action execution requests specifying subsequent actions for execution by UE  1002 . In some embodiments, controller  1004  may send action execution requests sequentially, as shown in  FIG.  10   . Controller  1004  transmits subsequent action execution request  1024  to UE  1002 , after action execution request  1022  has been received by controller  1004 . UE  1002  may respond to action execution request  1022  by transmitting action execution response  1026 . Action execution response  1026  may specify that the action has been performed, or the action execution response  1026  may confirm that the scheduled action request has been received and confirm the scheduled time of execution with an upcoming timestamp. In other embodiments, controller  1004  may transmit multiple action execution requests in a non-sequential configuration. 
       FIG.  11    illustrates an exemplary peer-to-peer TSN protocol  1100 , in accordance with some embodiments. The TSN protocol may implement a network without a centralized controller using a peer-to-peer application. In the peer-to-peer application, the same architecture as illustrated in  FIG.  3    may be used, but device registration and action scheduling may be executed without the use of a centralized controller. In the peer-to-peer application, the edge devices, such as multiple UEs, negotiate and agree to the actions to be performed collectively. In this way, the peer-to-peer application implements a Collaborative Robot deployment, of a Multi-Agent system, deployed in physical devices. The peers participating in the TSN protocol are capable of adapting the scheduled actions to the real-time needs or characteristics of the environment. 
       FIG.  11    illustrates UEs  1102 ,  1104 ,  1106 ,  1108  and  1110  as components of peer-to-peer network  1100 . UE  1202  is illustrated performing auto-discovery and action execution processes, in accordance with some embodiments. The auto-discovery process begins by broadcasting a device identifier to broadcasting facility to register UE  1102  with the peer-to-peer network. The device identifier and capabilities of the newly deployed UE, such as an indication that the device supports 5g-radio-frame-based-synchronization and an accuracy that may be included with device registration message  1120 . The broadcasting message is forwarded to the UEs of the peer-to-peer network through subsequent device registration messages  1122 ,  1124 , and  1126  corresponding to UEs  1106 ,  1108 , and  1110  respectively. 
     Following UE registration, action execution requests may be transmitted between the peers of network  1100 . For example, UE  1102  may transmit action execution request  1130  including a timestamp, action ID, and optional parameters to UE  1106 . UE  1106  may respond by transmitting action execution response, confirming the scheduling of the action execution request, as described herein. Additional action execution requests may be transmitted concurrently, and/or subsequently by other UEs of network  1100 . For example, UE  1108  may transmit an action execution request  1140  to UE  1110 , which may respond by transmitting action execution response  1142 , as described herein. 
       FIG.  12    illustrates one exemplary implementation of a computing device in the form of computing device  1200  that may be used in a system implementing techniques described herein, although others are possible. It should be appreciated that  FIG.  12    is intended neither to be a description of necessary components for a computing device to operate as a IIOT or TSN facility, in accordance with the techniques described herein, nor a comprehensive depiction. 
     Computing device  1200  may include at least one processor  1202 , a network adapter  1204 , and a non-volatile computer-readable storage media  1206 . Computing device  1200  may be, for example a desktop or laptop personal computer, a personal digital assistant, a smart mobile phone, IIOT equipment, or any other suitable computing device. Network adapter  1204  may be any suitable hardware and/or software to enable the computing device  1200  to communicate through wired and/or wireless connections with any other suitable computing device over any suitable computing network and using any suitable networking protocol, as described herein. The computing network may include switches, routers, gateways, access points, and/or other networking equipment as well as any suitable wired and/or wireless communication medium or media for exchanging data between two or more computers, including the Internet. Non-volatile computer readable storage media  1206  may be adapted to store data to be processed and/or instructions to be executed by processor  1202 . Processor  1202  enables processing of data and execution of instructions. The data instructions may be stored on the computer-readable storage media  1206 . The processor  1202  may control writing data to and reading data from the non-volatile computer-readable storage media  1206  and memory  1210  in any suitable manner, as the aspects of the disclosure provided herein are not limited in this respect. 
     The data and instructions stored on computer-readable storage media  1206  may include computer-executable instructions implementing techniques which operate according to the techniques described herein. In the example of  FIG.  12   , non-volatile computer-readable storage media  1206  stores computer-executable instructions implementing various facilities and storing various information as described above. Non-volatile computer-readable storage media  1206  may store an IIOT or TSN facility, in accordance with some embodiments described herein. 
     While not illustrated in  FIG.  12   , a computing device may additionally have one or more components and peripherals, including input and output devices. These devices can be used, among other things to present a user interface. Examples, of output devices that can be used to provide a user interface include printers or display screens for visual presentation of output and speakers or other sound generating devices for audible presentation of output. Example of input devices that can be used for a user interface include keyboards, and pointing devices, such as mice, touch pads, and digitizing tablets. As another example, a computing device may receive input information through speech recognition or in other audible format. 
     Techniques operating according to the principles described herein may be implemented in any suitable manner. The processing and decision blocks of the flowcharts above represent steps and acts that may be included in algorithms that carry out these various processes. Algorithms derived from these processes may be implemented as software integrated with and directing the operation of one or more single- or multi-purpose processors, may be implemented as functionally equivalent circuits such as a Digital Signal Processing (DSP) circuit or an Application-Specific Integrated Circuit (ASIC), or may be implemented in any other suitable manner. It should be appreciated that the flowcharts included herein do not depict the syntax or operation of any particular circuit or of any particular programming language or type of programming language. Rather, the flowcharts illustrate the functional information one skilled in the art may use to fabricate circuits or to implement computer software algorithms to perform the processing of a particular apparatus carrying out the types of techniques described herein. It should also be appreciated that, unless otherwise indicated herein, the particular sequence of steps and/or acts described in each flowchart is merely illustrative of the algorithms that may be implemented and can be varied in implementations and embodiments of the principles described herein. 
     Accordingly, in some embodiments, the techniques described herein may be embodied in computer-executable instructions implemented as software, including as application software, system software, firmware, middleware, embedded code, or any other suitable type of computer code. Such computer-executable instructions may be written using any of a number of suitable programming languages and/or programming or scripting tools, and also may be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine. 
     When techniques described herein are embodied as computer-executable instructions, these computer-executable instructions may be implemented in any suitable manner, including as a number of functional facilities, each providing one or more operations to complete execution of algorithms operating according to these techniques. A “functional facility,” however instantiated, is a structural component of a computer system that, when integrated with and executed by one or more computers, causes the one or more computers to perform a specific operational role. A functional facility may be a portion of or an entire software element. For example, a functional facility may be implemented as a function of a process, or as a discrete process, or as any other suitable unit of processing. If techniques described herein are implemented as multiple functional facilities, each functional facility may be implemented in its own way; all need not be implemented the same way. Additionally, these functional facilities may be executed in parallel and/or serially, as appropriate, and may pass information between one another using a shared memory on the computer(s) on which they are executing, using a message passing protocol, or in any other suitable way. 
     Generally, functional facilities include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically, the functionality of the functional facilities may be combined or distributed as desired in the systems in which they operate. In some implementations, one or more functional facilities carrying out techniques herein may together form a complete software package. These functional facilities may, in alternative embodiments, be adapted to interact with other, unrelated functional facilities and/or processes, to implement a software program application. 
     Some exemplary functional facilities have been described herein for carrying out one or more tasks. It should be appreciated, though, that the functional facilities and division of tasks described is merely illustrative of the type of functional facilities that may implement using the exemplary techniques described herein, and that embodiments are not limited to being implemented in any specific number, division, or type of functional facilities. In some implementations, all functionalities may be implemented in a single functional facility. It should also be appreciated that, in some implementations, some of the functional facilities described herein may be implemented together with or separately from others (i.e., as a single unit or separate units), or some of these functional facilities may not be implemented. 
     Computer-executable instructions implementing the techniques described herein (when implemented as one or more functional facilities or in any other manner) may, in some embodiments, be encoded on one or more computer-readable media to provide functionality to the media. Computer-readable media include magnetic media such as a hard disk drive, optical media such as a Compact Disk (CD) or a Digital Versatile Disk (DVD), a persistent or non-persistent solid-state memory (e.g., Flash memory, Magnetic RAM, etc.), or any other suitable storage media. Such a computer-readable medium may be implemented in any suitable manner. As used herein, “computer-readable media” (also called “computer-readable storage media”) refers to tangible storage media. Tangible storage media are non-transitory and have at least one physical, structural component. In a “computer-readable medium,” as used herein, at least one physical, structural component has at least one physical property that may be altered in some way during a process of creating the medium with embedded information, a process of recording information thereon, or any other process of encoding the medium with information. For example, a magnetization state of a portion of a physical structure of a computer-readable medium may be altered during a recording process. 
     Further, some techniques described above comprise acts of storing information (e.g., data and/or instructions) in certain ways for use by these techniques. In some implementations of these techniques—such as implementations where the techniques are implemented as computer-executable instructions—the information may be encoded on a computer-readable storage media. Where specific structures are described herein as advantageous formats in which to store this information, these structures may be used to impart a physical organization of the information when encoded on the storage medium. These advantageous structures may then provide functionality to the storage medium by affecting operations of one or more processors interacting with the information; for example, by increasing the efficiency of computer operations performed by the processor(s). 
     In some, but not all, implementations in which the techniques may be embodied as computer-executable instructions, these instructions may be executed on one or more suitable computing device(s) operating in any suitable computer system, or one or more computing devices (or one or more processors of one or more computing devices) may be programmed to execute the computer-executable instructions. A computing device or processor may be programmed to execute instructions when the instructions are stored in a manner accessible to the computing device or processor, such as in a data store (e.g., an on-chip cache or instruction register, a computer-readable storage medium accessible via a bus, a computer-readable storage medium accessible via one or more networks and accessible by the device/processor, etc.). Functional facilities comprising these computer-executable instructions may be integrated with and direct the operation of a single multi-purpose programmable digital computing device, a coordinated system of two or more multi-purpose computing device sharing processing power and jointly carrying out the techniques described herein, a single computing device or coordinated system of computing device (co-located or geographically distributed) dedicated to executing the techniques described herein, one or more Field-Programmable Gate Arrays (FPGAs) for carrying out the techniques described herein, or any other suitable system. 
     Embodiments have been described where the techniques are implemented in circuitry and/or computer-executable instructions. It should be appreciated that some embodiments may be in the form of a method, of which at least one example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments. 
     Various aspects of the embodiments described above may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments. 
     The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both,” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
     As used herein in the specification and in the claims, the phrase, “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently, “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, at least one, optionally including more than one, B (and optionally including other elements); etc. 
     Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements. 
     Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
     The word “exemplary” is used herein to mean serving as an example, instance, or illustration. Any embodiment, implementation, process, feature, etc. described herein as exemplary should therefore be understood to be an illustrative example and should not be understood to be a preferred or advantageous example unless otherwise indicated. 
     Having thus described several aspects of at least one embodiment, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the spirit and scope of the principles described herein. Accordingly, the foregoing description and drawings are by way of example only. 
     Various aspects are described in this disclosure, which include, but are not limited to, the following aspects: 
     1. A computerized method to provide a Time-Sensitive Networking (TSN) synchronization protocol over a wireless channel of a cellular network, the method comprising performing, by a cellular network device: receiving, by the network device, timing information from a cellular network node, wherein: the cellular network node is in wired communication with the network device; and the timing information is associated with a Network Clock Reference and a transmission time to the network device in accordance with a wired synchronization protocol; determining, by the network device, a timing adjustment based on the timing information; and adjusting, based on the timing adjustment, timing signals that are transmitted by the network device to a user device in cellular communication with the cellular network node through the network device, wherein the timing signals is used to adjust a timing system of the user device in accordance with the TSN synchronization protocol. 
     2. The computerized method of aspect 1, wherein the TSN synchronization protocol is a wireless synchronization protocol, and the wireless synchronization protocol comprises: transmitting, by the network device, downlink information of a radio frame, wherein the transmitting the downlink information comprises transmitting a pattern of reference synchronization signals as the timing signals to the user device; receiving, by the network device, uplink information of the radio frame, wherein the uplink information comprises response information corresponding to a time of arrival of the downlink information at the user device; and determining, by the network device, delay information associated with a travel time for the radio frame to wirelessly travel from the network device to the user device, wherein determining the delay information comprises comparing a first time associated with the network device transmitting the downlink information, to a second time associated with the network device receiving the uplink information. 
     3. The computerized method of aspect 2, wherein the receiving, by the network device, the uplink information further comprises using a Random-Access procedure between the network device and the user device, and the determining the delay information further comprises determining a timing advance. 
     4. The computerized method of aspect 2, wherein: the radio frame comprises a plurality of subframes, wherein each of the plurality of subframes comprises a plurality of slots, wherein each of the plurality of slots comprises a plurality of symbols; and the transmitting the pattern of reference synchronization signals further comprises transmitting the pattern of reference synchronization signals as a sub-set of the plurality of symbols. 
     5. The computerized method of aspect 4, wherein the determining the timing adjustment further comprises: determining a synchronized time based on the timing information and the delay information; determining a target arrival time for a portion of the radio frame based on the synchronized time; and determining the timing adjustment based on the target arrival time, the timing information, and the delay information such that, when transmitted, the portion of the radio frame arrives at the user device at the target arrival time. 
     6. The computerized method of aspect 5, wherein the portion of the radio frame is a first slot of a first subframe of the radio frame, and the target arrival time that the radio frame arrives at the user device is at the start of a synchronized clock interval. 
     7. The computerized method of any of aspects 5-6, wherein the TSN synchronization protocol supports TSN in accordance with IEEE 802.1AS standard, the TSN synchronization protocol further comprising transmitting, by the network device, the synchronized time such that when the synchronized time arrives at the user device, the synchronized time is synchronized to within a predetermined threshold of a reference time. 
     8. The computerized method of aspect 7, wherein the predetermined threshold is within 1 nanosecond of the reference time, within 1 microsecond of the reference time, or some combination thereof. 
     9. The computerized method of aspect 7, wherein the predetermined threshold is within 250 nanoseconds of the reference time in dispersive channels with time-variant conditions. 
     10. The computerized method of any of aspects 2-9, wherein transmitting the pattern of reference synchronization signals further comprises transmitting a radio frame using subcarrier bandwidths from 15 kHz to 240 kHz. 
     11. The computerized method of any of aspects 1-10, wherein the receiving timing information from the cellular network comprises receiving a reference time, residence time, and link delay from the reference clock to the network node based on a generic Precision Time Protocol (g-PTP) of the cellular network. 
     12. The computerized method of any of aspects 1-11, wherein the network device is a base station. 
     13. The computerized method of aspect 12, wherein the base station is a gNodeB and the cellular network is a 5G network. 
     14. An apparatus configured to provide a TSN synchronization protocol over a wireless channel of a cellular network, the apparatus comprising a processor in communication with memory and a set of additional processing resources, the processor being configured to execute instructions stored in the memory that cause the processor to: receive, by the network device, timing information from a cellular network node, wherein: the cellular network node is in wired communication with the network device; and the timing information is associated with a Network Clock Reference and a transmission time to the network device in accordance with a wired synchronization protocol; determine, by the network device, a timing adjustment based on the timing information; and adjust, based on the timing adjustment, timing signals that is transmitted by the network device to a user device in cellular communication with the cellular network node through the network device, wherein the timing signals is used to adjust a timing system of the user device in accordance with the TSN synchronization protocol. 
     15. The apparatus of aspect 14, wherein the TSN synchronization protocol is a wireless synchronization protocol, and wherein the instructions are further configured in accordance with the TSN synchronization protocol to cause the apparatus to: transmit, by the network device, downlink information of a radio frame, wherein the transmitting the downlink information comprises transmitting a pattern of reference synchronization signals as the timing signals to the user device; receive, by the network device, uplink information of the radio frame, wherein the uplink information comprises response information corresponding to a time of arrival of the downlink information at the user device; and determine, by the network device, delay information associated with a travel time for the radio frame to wirelessly travel from the network device to the user device, wherein determining the delay information comprises comparing a first time associated with the network device transmitting the downlink information, to a second time associated with the network device receiving the uplink information. 
     16. The apparatus of aspect 15, wherein the instructions are configured such that the radio frame comprises a plurality of subframes, wherein each of the plurality of subframes comprises a plurality of slots, wherein each of the plurality of slots comprises a plurality of symbols; and the instructions are further configured to cause the apparatus to transmit the pattern of reference synchronization signals further comprises transmitting the pattern of reference synchronization signals as a sub-set of the plurality of symbols. 
     17. The apparatus of aspect 16, the instructions to cause the apparatus to determine the timing adjustment are further configured to: determine a synchronized time based on the timing information, and the delay information; determine a target arrival time for a portion of the radio frame based on the synchronized time; and determine the timing adjustment based on the target arrival time, the timing information, and the delay information such that, when transmitted, the portion of the radio frame arrives at the user device at the target arrival time. 
     18. The apparatus of aspect 15-17, wherein the instructions are further configured to execute actions sent from the cellular network that are time-synchronized with at least one user device action through a communication protocol that specifies an action type to be executed and the time when the action shall be executed. 
     19. At least one non-transitory computer-readable storage medium encoded with a plurality of computer-executable instructions that, when executed, perform a method to provide a TSN synchronization protocol over a wireless channel of a cellular network, the method comprising: receiving, by the network device, timing information from a cellular network node, wherein: the cellular network node is in wired communication with the network device; and the timing information is associated with a Network Clock Reference and a transmission time to the network device in accordance with a wired synchronization protocol; determining, by the network device, a timing adjustment based on the timing information; and adjusting, based on the timing adjustment, timing signals that are transmitted by the network device to a user device in cellular communication with the cellular network node through the network device, wherein the timing signals is used to adjust a timing system of the user device in accordance with the TSN synchronization protocol. 
     20. The at least one non-transitory computer-readable storage medium of aspect 19, wherein the synchronization protocol is a wireless synchronization protocol, and the wireless synchronization protocol comprises: transmitting, by the network device, downlink information of a radio frame, wherein the transmitting the downlink information comprises transmitting a pattern of reference synchronization signals as the timing signals to the user device; receiving, by the network device, uplink information of the radio frame, wherein the uplink information comprises response information corresponding to a time of arrival of the downlink information at the user device; and determining, by the network device, delay information associated with a travel time for the radio frame to wirelessly travel from the network device to the user device, wherein determining the delay information comprises comparing a first time associated with the network device transmitting the downlink information, to a second time associated with the network device receiving the uplink information. 
     21. The at least one non-transitory computer-readable storage medium of aspect 20, wherein the determining the timing adjustment further comprises: determining a synchronized time based on the timing information and the delay information; determining a target arrival time for a portion of the radio frame based on the synchronized time; and determining the timing adjustment based on the target arrival time, the timing information, and the delay information such that, when transmitted, the portion of the radio frame arrives at the user device at the target arrival time. 
     22. An apparatus configured to receive a synchronization protocol over a wireless channel of a cellular network, the apparatus comprising a processor in communication with memory and a set of additional processing resources, the processor being configured to execute instructions stored in the memory that cause the processor to: receive, by a user device, timing information from a network device, wherein: receiving, by the user device, comprises receiving downlink information of a radio frame, wherein the downlink information comprises frequency and phase synchronization signals configured as timing signals to the user device; the user device extracts, from a 5GNR Radio Resource Control System Information Block 9, a Timing Advance MAC control element and a time reference of the network device to adjust and discipline using the frequency and phase synchronization signals; the user device extracts a physical layer signal from a Slot Indication signal associated with the radio frame and/or a Symbol Boundary signal to adjust and discipline an internal clock of the user device to meet a time accuracy within a Virtual Clock Domain comprising TSN enabled user devices, network devices, network node and TSN controller. 
     23. The apparatus of aspect 22, wherein the instructions further comprise informing the network device about support of the synchronization protocol and an achievable time accuracy using the instructions described in aspect 17. 
     24. The apparatus of aspect 22, that includes a clock disciplining subsystem to use the physical signals of Slot Indication signals and/or Symbol Boundary signals to discipline the internal clock that translates timing information into a computer-executable instruction that comprises the messages associated with the instructions described in aspect 17.