Field

[001] The subj ect matter described herein relates to time sensitive communications over a cellular wireless system.

Background

[002] Time sensitive communications (TSC) may be used to support a variety of applications including applications such as ultra-reliable low-latency communications (UR-LLC), industrial verticals, and/or the like. In the case of industrial verticals including networks, there may be some requirements that are relatively unique, such as certain requirements for low latency, deterministic data transmission, and high reliability, when compared to other 5G cellular services. To that end, the IEEE provides a suite of Time Sensitive Network (TSN) specifications to allow synchronization of bridges to grand master clocks (see, e.g., IEEE-1588 and IEEE 802. IAS), link layer bridge discovery (IEEE 802.1AB), provisioning of streams including gate scheduling along the path between TSN endpoints (IEEE 802.1Qcc and IEEE 802.1Qbv), frame replication for reliability (IEEE 802.1CB), and other protocols to enable isochronous transmission to connect endpoints across Ethernet bridges.

Summary

[003] Methods and apparatus, including computer program products, are provided for time sensitive communications.

[004] In some example embodiments, there is provided a method including receiving a sync message for a time domain including at least an origin time stamp and a correction; and sending, based on the received sync message, a time information over a radio link to enable recovery of the origin time stamp and the correction, the radio link synchronized with a system clock, the time information including the received origin time stamp, a reference system frame number, and an offset within a system frame indicated by the reference frame number.

[005] In some variations, one or more features disclosed herein including the following features may optionally be included in any feasible combination. The origin time stamp may include a generalized precision time protocol origin time stamp generated by a grand master. The time information may be carried by a radio resource control message and/or a system information broadcast message. The sync message may include a rate ratio, and wherein the recovery of the origin time stamp includes recovering the rate ratio. The recovery of the rate ratio may be based on consecutive messages carrying time information. Based on the received sync message, generation of the time information may be performed by at least determining a time of the system clock related to the origin time stamp, wherein the system clock is from at least the cellular system. The reference system frame number and the offset reference may indicate a time of the system clock related to the origin time stamp. The sync message may be in accordance with IEEE 802.11AS. A gNB base station may perform the receiving, the generating, and the sending. A user equipment may perform the receiving, the generating, and the sending. The user equipment may include circuitry to enable coupling to a time-sensitive network. The sending may further include setting a SyncLocked variable to FALSE, when the sending at a master port do not comply with an expected periodicity of a slave port receiving the time information.

[006] The above-noted aspects and features may be implemented in systems, apparatus, methods, and/or articles depending on the desired configuration. The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. Description of Drawings

[007] In the drawings,

[008] FIG. 1 depicts examples of a portion of a 5G system configured to support time sensitive communications between end stations, in accordance with some example embodiments;

[009] FIG. 2 depicts an example of a messaging flow for transferring generalized precision time protocol origin time stamps over a 5G system, in accordance with some example embodiments;

[010] FIG. 3 depicts an example of a process for transferring generalized precision time protocol origin time stamps over a 5G system, in accordance with some example embodiments;

[Oil] FIG. 4 depicts an example of a network node, in accordance with some exemplary embodiments; and

[012] FIG. 5 depicts an example of an apparatus, in accordance with some exemplary embodiments.

[013] Like labels are used to refer to same or similar items in the drawings.

Detailed Description

[014] In 3GPP TS 22.104 there is a requirement for the 5G system to support the generalized precision time protocol (gPTP) as defined in, for example, IEEE802.1AS. In gPTP, a grand master provides an origin timestamp for each sync message which may be sent periodically. This origin time stamp is preserved in the gPTP sync messages, when conveyed along all of the gPTP hops through the network until a clock target is reached.

[015] In some example embodiments, there is provided a way to preserve, over the 5G system including the 5G radio access network (RAN), the gPTP origin time stamp from the grand master clock. When a gPTP origin time stamp is received, the gPTP origin timestamp may be transferred over the 5G system, such as the 5G RAN, through a radio link (which is synchronized with a 5G network, such as a system clock, called as a local clock of gPTP entity) towards a downstream entity, such as a user equipment (UE) or other type device needing the gPTP origin time stamp.

[016] In some example embodiments, the radio link carries the gPTP origin time stamp as well as information about a system frame number (SFN) and/or a time offset indicating a point in time of a local clock (e.g., a local system clock from the 5G system time domain) related to the gPTP origin timestamp obtained from received sync message. From this information, a receiver, such as the UE, may recover the synchronized time in the gPTP domain. And, with this recovered synchronized time information, a gPTP correction field and/or a gPTP rate ratio field may be determined and then inserted (along with the recovered gPTP origin time stamp) into another gPTP sync message and then forwarded over the time sensitive network to another device.

[017] Before providing additional examples regarding the gPTP origin time stamp preservation and transfer disclosed herein, FIG. 1 below provide an example of a time sensitive network (TSN) over which the gPTP origin time stamp preservation may be used.

[018] FIG. 1 depicts an example of a portion of a network 100, in accordance with some example embodiments. In this example, the end stations 102A-D include radio circuitry to transmit (e.g., in the case of a“talker”) and/or receive (e.g., in the case of a“listener”) using for example, TSN circuitry that enables communications over a local area time sensitive network as well. The end station may include, or be coupled to, a user equipment (UE) to enable transmission and/or reception to a 5G network. Although FIG. 1 depicts an example configuration of a 5G- TSC network, other configurations and topologies may be used as well.

[019] FIG. 1 also depicts 5G base stations 110A-B, such as a gNB, and other 5G nodes (e.g., a user plane function (UPF) 1 16A-B). In the example of FIG. 1, the network 100 includes aspects of the 5G network and a TSC network. The 5G-TSC network 100, as noted, includes gNB base stations 110A-B to provide coverage areas, which in this example cover a factory floor, although the network 100 may cover other types of areas to provide the TSC service. [020] In the example of FIG. 1, the end stations 102A-C are each associated with a robot, and the end station 102D is associated with a robot controller, although the end stations may be associated with other types of devices and carry other types of time sensitive traffic as well.

[021] The end stations 102A-B may transmit to end station 102D via a 5G radio access network to a base station, such as gNB 110A, while end station 102C may transmit via a wired connection to a user plane function 116B which is co-located with the gNB 110B to enable user plane traffic access associated with end station 102C. In 5G, the UPF may perform one or more of the following operations: packet routing and forwarding; packet inspection and QoS handling; connecting to the Internet point of presence; provide a mobility anchor for intra-radio access technology and inter radio-access technology handovers; user plane functionality for lawful intercept; and maintenance and reporting of traffic statistics.

[022] The end station 102D (which is associated with the robot controller in this example) may transmit to end stations 102A-B via a 5G radio access network provided by the gNB 110A, or may transmit to end station 102C via the 5G radio access network provided by the gNB 1 10A or gNB 110B (which is co-located with UPF 102C). In some example embodiments, the communication path between the end stations may be configured by the 5G network with QoS to provide gated scheduling (e.g., specific transmit times and a periodicity for the transmissions) at any nodes on the TSC communication path.

[023] As noted above, the 5G system may need to support gPTP and the preservation of the gPTP origin time stamp. For example, the gPTP origin time stamp may be present at end- station coupled robot 102C but need to be shared with the end-station coupled robot 102B (which as noted includes a UE for 5G RAN access). In this example, when the UPF 116B sends the gPTP origin time stamp to the gNB 110B, the gNB 110B transfers the gPTP origin timestamps through the downlink towards the UE-coupled robot 102B. However, rather than using a sync message as is usually the case with the transfer of the origin time stamp, the gNB 110B transmits the gPTP origin time stamp along with information about the system frame number (SFN) and/or a time offset indicating a point of system time related to the received gPTP origin timestamp. When this information is received via the 5G downlink at the robot-coupled UE 102B, the synchronized time as well as the gPTP correction field and/or gPTP rate ratio field may be recovered. If needed, the gPTP origin time stamp, the recovered gPTP correction field, and the recovered gPTP rate ratio field may be inserted into another gPTP sync message and forwarded over the time sensitive network to another clock slave, such as for example robot controller 102D.

[024] According to IEEE 802. IAS, the gPTP origin time stamp received at a slave port of time-aware system is copied to sync messages sent via a master port. When transmission of gPTP sync messages at the master port do not following the expected periodicity of the slave port, the SyncLocked variable is set FALSE. This option may allow timing and periodicity if transfer over Uu interface is independent of incoming sync messages, otherwise each incoming sync message needs to trigger a message over Uu. For example, if a gNB is transmitting the SIB messages (as described further below with respect to FIG. 2 at 212A-C), the SyncLocked variable may be set to FALSE. However, if RRC messages are used to carry the O, refSFN, and/or ref offset at at 212A-C, the periodicity may be maintained so the SyncLocked variable may be set to TRUE.

[025] Conveying of the gPTP sync messages with origin time stamp (which also requires under the PTP protocol the gPTP correction field, and gPTP rate ratio) and synchronized system time, such as the system frame number (SFN), through the Uu interface (which is the interface between a UE and a gNB) may introduce substantial signaling overhead compared to case were only synchronized system time is conveyed. Thus, there is a need for an improved way to send the gPTP over the 5G system including the RAN.

[026] FIG. 2 depicts an example flow of messages in which gPTP time is obtained from TSN sync messages 210A-D and carried over a 5G RAN using system information broadcast (SIB) messages 212A-C, in accordance with some example embodiments. Although FIG. 2 depicts the SIB messages 212A-C, other types of 5G cellular messages, such as RRC messages may be used over the 5G RAN.

[027] FIG. 2 depicts a time-aware system 205 including a master port (labeled“M”). The time-aware system 205 may represent a 5G base station, such as gNB 110B. FIG. 2 also depicts UE, such as UE 102B and another time-aware system 208.

[028] In the example of FIG. 2, the time-aware system 205 sends via it’s master port (M) gPTP sync messages 210A-D in accordance with IEEE 802. IAS towards a slave port at the gNB 110B. These sync messages 210A-D each include the grand master origin time stamp (labeled“O”), a gPTP correction field (labeled Ci-i), and a gPTP rate ratio field (labeled Ri-i) in accordance with IEEE 802. IAS.

[029] To optimize the signaling over the 5G RAN by avoiding conveying the gPTP correction field (Ci-i) and gPTP rate ratio field Ri-i, the gNB HOB may determine a local time in the 5G system time base when synchronized time in the gPTP time domain scale has been equal to the time indicated in the gPTP origin timestamp sent by grand master.

[030] As shown at messages 212A-C, the time information that conveys the gPTP origin time stamp over Uu interface and synchronized time at the gNB transmitter port towards the RAN and UE includes: (1) a reference system frame number (refSFN) which may be about, for example, 10 bits, (2) a reference time offset (ref offset) within reference the SFN of 10 ms with, for example, 10 nanosecond resolution (e.g., with 20 bits), and (3) the gPTP origin timestamp that is copied from the last received gPTP SYNC message (e.g., with 80 bits). Messages 212A-C depict SIB messages sent by the gNB 110B to the UE 102B. Each of the messages 212A-C include the gPTP origin time stamp (O) as well as the reference SFN (refSFN) and/or the time offset (ref_offset).

[031] When for example message 212A is received by UE 102B, UE 102B extracts the gPTP origin time stamp as well as the reference SFN (refSFN) and/or the time offset (ref offset). Next, the UE 102B recovers the gPTP correction field (labeled Ci-1) and a gPTP rate ratio field (labeled Ri-1) based on the extracted gPTP origin time stamp, the reference SFN (refSFN), and/or the time offset (ref offset) with propagation and residence time delays. The UE may determine the frequency offset between the 5G time base and the grand master by tracking a frequency offset from consecutive time information messages and can thus populate Rate ratio (Ri) field sent towards N60 time sensitive networking translator interface (see, e.g., 3 GPP TS 24.534). The UE may populate the sync message correction field (Ci) based on the difference between sync transmission time at master port related to the gPTP origin timestamp in the scale of synchronized time. The same applies also for two step sync mode with populating correction and rate ratio fields in sync follow-up message.

[032] The UE 102B may insert the recovered gPTP origin time stamp, the recovered gPTP correction field, and the recovered gPTP rate ratio field may be inserted into another gPTP sync message, such as sync message 216A. This message 216A may be forwarded to another time-aware system 208 over a TSN network.

[033] The reference system frame number (refSFN) and the reference time offset (ref offset) within the reference SFN determine the time in local system clock scale when synchronized time of gPTP domain has been equal to the time indicated by the origin time stamp.

[034] Although FIG. 2 depicts a downlink example from the gNB to the UE, the process may also be from the UE to the gNB as well using the same or similar process. For example, the UE 102B may receive at a slave port the sync messages from an upstream system and send, e.g., RRC messages, like 212A-C, to the gNB 110B, which may then recover the origin time stamp, correction, and rate ratio and forward them to another system in a sync message.

[035] FIG. 3 depicts an example of a process 300 for preserving the gPTP origin stamp over the 5G RAN, in accordance with some example embodiments.

[036] At 305, a gPTP sync message may be received with the gPTP origin time stamp, in accordance with some example embodiments. For example, gNB 110B may receive sync message 210A including the gPTP origin time stamp, and this message 210A may be received from a master (M) upstream port at upstream system 205.

[037] At 310, the gNB may determine synchronized time related to the 5G time base, in accordance with some example embodiments. For example, the gNB may determine the reference system frame number and a reference offset within that reference system frame number that are equal to the time indicated in gPTP origin time stamp (O) sent by the grand master clock.

[038] At 315, the gPTP origin time stamp including its determined relations in the 5G time domain, such as the determined reference system frame number and the determined reference offset, are inserted into a 5G message such as a SIB message (or RRC messages) as shown at 212A. These SIB or RRC messages 212A-B are sent over the Uu interface over the RAN.

[039] At 320, recovery is performed for the time of time domain called then as a synchronized time. For example, the UE 102B may extract the gPTP origin time stamp, the reference SFN (refSFN) and the time offset (ref_offset). Next, the UE 102B recovers the gPTP correction field (labeled Ci-1), and a gPTP rate ratio field (labeled Ri-1) based on the extracted gPTP origin time stamp, the reference SFN (refSFN), and the time offset (ref offset). Recovering of correction Ci and for the time of ongoing sync message: Ci = t _{s -} O, where t _s is the time of sending in the grand master scale and O is the origin timestamp. Rate ratio Ri is a ratio of grand master frequency and system clock frequency. It can be estimated from consecutive messages, such as Ri = [(refSFN(n-l) - refSFN(n-l)) MOD 1024)* 10ms + ref_offset(n) - ref_offset(n-l)] / (O(n) - O(n-l) ) , where n indicates current message and n-1 indicates preceding message.

[040] At 325, the UE 102B may insert the gPTP information and the recovered gPTP correction field (labeled Ci), and a gPTP rate ratio (Ri) into a sync message as sown at 216A and transmit that sync message to a downstream slave port (S) at system 208.

[041] FIG. 4 depicts a block diagram of a network node 400, in accordance with some example embodiments. The network node 400 may be configured as a gNB base station, UPF, and/or the like. The network node 400 may include a network interface 402, a processor 420, and a memory 404, in accordance with some example embodiments. The network interface 402 may couple to backhaul links to other nodes. These backhaul links may be wired and/or wireless. In the case of the gNB, it includes 5G radio access technology transceivers to provide a 5G radio access network. The memory 404 may comprise volatile and/or non-volatile memory including program code, which when executed by at least one processor 420 provides, among other things, the processes disclosed herein with respect to the base station.

[042] FIG. 5 illustrates a block diagram of an apparatus 10, in accordance with some example embodiments. The apparatus 10 (or portions thereof) may be configured to provide an end station including cellular radio access technology. The user equipment may comprise or may be comprised in an end station. The end station including user equipment may be configured to transmit and receive (listener and talker), configured to only receive (e.g., listener), and/or configured to only transmit (talker).

[043] The apparatus 10 may include at least one antenna 12 in communication with a transmitter 14 and a receiver 16. Alternatively transmit and receive antennas may be separate. The apparatus 10 may also include a processor 20 configured to provide signals to and receive signals from the transmitter and receiver, respectively, and to control the functioning of the apparatus. Processor 20 may be configured to control the functioning of the transmitter and receiver by effecting control signaling via electrical leads to the transmitter and receiver. Likewise, processor 20 may be configured to control other elements of apparatus 10 by effecting control signaling via electrical leads connecting processor 20 to the other elements, such as a display or a memory. The processor 20 may, for example, be embodied in a variety of ways including circuitry, at least one processing core, one or more microprocessors with accompanying digital signal processor(s), one or more processor(s) without an accompanying digital signal processor, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits (for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), and/or the like), or some combination thereof. Accordingly, although illustrated in FIG. 5 as a single processor, in some example embodiments the processor 20 may comprise a plurality of processors or processing cores.

[044] Signals sent and received by the processor 20 may include signaling information in accordance with an air interface standard of an applicable cellular system, and/or any number of different wireline or wireless networking techniques, comprising but not limited to Wi-Fi, wireless local access network (WLAN) techniques, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, 802.16, and/or the like. In addition, these signals may include speech data, user generated data, user requested data, and/or the like.

[045] The apparatus 10 may be capable of operating with one or more air interface standards, communication protocols, modulation types, access types, and/or the like. For example, the apparatus 10 and/or a cellular modem therein may be capable of operating in accordance with various first generation (1G) communication protocols, second generation (2G or 2.5G) communication protocols, third-generation (3G) communication protocols, fourth- generation (4G) communication protocols, fifth generation (5G), Internet Protocol Multimedia Subsystem (IMS) communication protocols (for example, session initiation protocol (SIP) and/or the like. For example, the apparatus 10 may be capable of operating in accordance with 2G wireless communication protocols IS-136, Time Division Multiple Access TDMA, Global System for Mobile communications, GSM, IS-95, Code Division Multiple Access, CDMA, and/or the like. In addition, for example, the apparatus 10 may be capable of operating in accordance with 2.5G wireless communication protocols General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), and/or the like. Further, for example, the apparatus 10 may be capable of operating in accordance with 3G wireless communication protocols, such as Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA2000), Wideband Code Division Multiple Access (WCDMA), Time Division- Synchronous Code Division Multiple Access (TD-SCDMA), and/or the like. The apparatus 10 may be additionally capable of operating in accordance with 3.9G wireless communication protocols, such as Long Term Evolution (LTE), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and/or the like. Additionally, for example, the apparatus 10 may be capable of operating in accordance with 4G wireless communication protocols, such as LTE. For example, the apparatus 10 may be capable of operating in accordance with 5G wireless communication protocols, such as 3GPP NR, NG-RAN, and/or the like. Advanced, 5G, and/or the like as well as similar wireless communication protocols that may be subsequently developed.

[046] It is understood that the processor 20 may include circuitry for implementing audio/video and logic functions of apparatus 10. For example, the processor 20 may comprise a digital signal processor device, a microprocessor device, an analog-to-digital converter, a digital- to-analog converter, and/or the like. Control and signal processing functions of the apparatus 10 may be allocated between these devices according to their respective capabilities. The processor 20 may additionally comprise an internal voice coder (VC) 20a, an internal data modem (DM) 20b, and/or the like. Further, the processor 20 may include functionality to operate one or more software programs, which may be stored in memory. In general, processor 20 and stored software instructions may be configured to cause apparatus 10 to perform actions. For example, processor 20 may be capable of operating a connectivity program, such as a web browser. The connectivity program may allow the apparatus 10 to transmit and receive web content, such as location-based content, according to a protocol, such as wireless application protocol, WAP, hypertext transfer protocol, HTTP, and/or the like.

[047] Apparatus 112 may also comprise a user interface including, for example, an earphone or speaker 24, a ringer 22, a microphone 26, a display 28, a user input interface, and/or the like, which may be operationally coupled to the processor 20. The display 28 may, as noted above, include a touch sensitive display, where a user may touch and/or gesture to make selections, enter values, and/or the like. The processor 20 may also include user interface circuitry configured to control at least some functions of one or more elements of the user interface, such as the speaker 24, the ringer 22, the microphone 26, the display 28, and/or the like. The processor 20 and/or user interface circuitry comprising the processor 20 may be configured to control one or more functions of one or more elements of the user interface through computer program instructions, for example, software and/or firmware, stored on a memory accessible to the processor 20, for example, volatile memory 40, non-volatile memory 42, and/or the like. The apparatus 10 may include a battery for powering various circuits related to the mobile terminal, for example, a circuit to provide mechanical vibration as a detectable output. The user input interface may comprise devices allowing the apparatus 20 to receive data, such as a keypad 30 (which can be a virtual keyboard presented on display 28 or an externally coupled keyboard) and/or other input devices.

[048] As shown in FIG. 5, apparatus 10 may also include one or more mechanisms for sharing and/or obtaining data. For example, the apparatus 10 may include a short-range radio frequency (RF) transceiver and/or interrogator 64, so data may be shared with and/or obtained from electronic devices in accordance with RF techniques. The apparatus 10 may include other short-range transceivers, such as an infrared (IR) transceiver 66, a Bluetooth™ (BT) transceiver 68 operating using Bluetooth™ wireless technology, a wireless universal serial bus (USB) transceiver 70, a Bluetooth™ Low Energy transceiver, a ZigBee transceiver, an ANT transceiver, a cellular device-to-device transceiver, a wireless local area link transceiver, and/or any other short-range radio technology. Apparatus 1 12 and, in particular, the short-range transceiver may be capable of transmitting data to and/or receiving data from electronic devices within the proximity of the apparatus, such as within 10 meters, for example. The apparatus 10 including the Wi-Fi or wireless local area networking modem may also be capable of transmitting and/or receiving data from electronic devices according to various wireless networking techniques, including 6LoWpan, Wi-Fi, Wi-Fi low power, WLAN techniques such as IEEE 802.11 techniques, IEEE 802.15 techniques, IEEE 802.16 techniques, and/or the like.

[049] The apparatus 10 may comprise memory, such as a subscriber identity module (SIM) 38, a removable user identity module (R-UIM), an eUICC, an UICC, and/or the like, which may store information elements related to a mobile subscriber. In addition to the SIM, the apparatus 10 may include other removable and/or fixed memory. The apparatus 10 may include volatile memory 40 and/or non-volatile memory 42. For example, volatile memory 40 may include Random Access Memory (RAM) including dynamic and/or static RAM, on-chip or off- chip cache memory, and/or the like. Non-volatile memory 42, which may be embedded and/or removable, may include, for example, read-only memory, flash memory, magnetic storage devices, for example, hard disks, floppy disk drives, magnetic tape, optical disc drives and/or media, non-volatile random access memory (NVRAM), and/or the like. Like volatile memory 40, non-volatile memory 42 may include a cache area for temporary storage of data. At least part of the volatile and/or non-volatile memory may be embedded in processor 20. The memories may store one or more software programs, instructions, pieces of information, data, and/or the like which may be used by the apparatus for performing operations disclosed herein with respect to the end stations/user equipment. The memories may comprise an identifier, such as an international mobile equipment identification (IMEI) code, capable of uniquely identifying apparatus 10. The memories may comprise an identifier, such as an international mobile equipment identification (IMEI) code, capable of uniquely identifying apparatus 10. In the example embodiment, the processor 20 may be configured using computer code stored at memory 40 and/or 42 to perform one or more of the operations disclosed herein with respect to the UE or other nodes or devices.

[050] Some of the embodiments disclosed herein may be implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. The software, application logic, and/or hardware may reside on memory 40, the control apparatus 20, or electronic components, for example.

[051] In the context of this document, a“computer-readable medium” may be any non- transitory media that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer or data processor circuitry, with examples depicted at FIG. 4, computer-readable medium may comprise a non-transitory computer-readable storage medium that may be any media that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[052] Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodiments disclosed herein is improved 5G support for time sensitive communications.

[053] The subject matter described herein may be embodied in systems, apparatus, methods, and/or articles depending on the desired configuration. For example, the base stations and user equipment (or one or more components therein) and/or the processes described herein can be implemented using one or more of the following: a processor executing program code, an application-specific integrated circuit (ASIC), a digital signal processor (DSP), an embedded processor, a field programmable gate array (FPGA), and/or combinations thereof. These various implementations may include implementation in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device. These computer programs (also known as programs, software, software applications, applications, components, program code, or code) include machine instructions for a programmable processor, and may be implemented in a high-level procedural and/or object- oriented programming language, and/or in assembly/machine language. As used herein, the term “computer-readable medium” refers to any computer program product, machine-readable medium, computer-readable storage medium, apparatus and/or device (for example, magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and/or data to a programmable processor, including a machine-readable medium that receives machine instructions. Similarly, systems are also described herein that may include a processor and a memory coupled to the processor. The memory may include one or more programs that cause the processor to perform one or more of the operations described herein.

[054] Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and/or variations may be provided in addition to those set forth herein. Moreover, the implementations described above may be directed to various combinations and subcombinations of the disclosed features and/or combinations and subcombinations of several further features disclosed above. Other embodiments may be within the scope of the following claims.

[055] If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined. Although various aspects of some of the embodiments are set out in the independent claims, other aspects of some of the embodiments comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims. It is also noted herein that while the above describes example embodiments, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications that may be made without departing from the scope of some of the embodiments as defined in the appended claims. Other embodiments may be within the scope of the following claims. The term“based on” includes“based on at least.” The use of the phase“such as” means“such as for example” unless otherwise indicated.