Detailed Description
The section headings used herein are for ease of understanding only and do not limit the scope of the embodiments to sections describing them. Furthermore, although embodiments are described with reference to the 5G example, the disclosed techniques may also be applied to wireless systems that use protocols other than the 5G or 3GPP protocols.
The development of New generation wireless communications, 5G New Radio (NR) communications, is part of the continuous mobile broadband evolution process to meet the increasing network demands. NR will provide greater throughput to allow more users to connect at the same time. Other aspects of energy consumption, equipment cost, spectral efficiency, and latency are also important to meet the needs of various communication scenarios.
In the current technology, if carrier aggregation is used for User Equipment (UE), a hybrid automatic repeat request acknowledgement (hybrid automatic repeat request acknowledgement, HARQ-ACK) physical uplink control channel (physical uplink control channel, PUCCH) may always be transmitted in an uplink primary carrier (Pcell). Thus, a UE using the current technology may not be able to dynamically trigger the carrier for the control channel.
Fig. 1 is an exemplary block diagram 100 illustrating a plurality of transmission carriers. However, in some cases, for example, as shown in fig. 1, CC0 and CC1 are aggregated, where CC0 is the primary carrier and CC1 is the secondary carrier. The slot configurations of CC0 and CC1 are shown in fig. 1, where D represents a downlink slot, S represents a flexible slot, and U represents an uplink slot. When a physical downlink shared channel (physical downlink SHARED CHANNEL, PDSCH) in the first downlink slot of CC0 is scheduled and HARQ-ACK needs to be fed back in the third slot, but the third slot in CC0 is a DL slot, HARQ-ACK PUCCH may not be transmitted. However, transmission of ultra-reliable low-delay communication (ultra-reliable and low latency communications, URLLC) services may not be delayed.
Thus, the HARQ-ACK PUCCH may be switched to CC1 for transmission because the HARQ-ACK PUCCH corresponds to the UL slot in CC 1. The method may also be used with other PUCCHs, such as channel state information (CHANNEL STATE information) PUCCHs and scheduling request (scheduling request, SR) PUCCHs.
Example embodiment 1
The next generation base station (gNode B) and the UE may agree to use the following rules to trigger the UE to dynamically select/switch (switch/hand over) PUCCH transport carriers.
PUCCH transmissions may be configured or defaulted in the first carrier (PUCCH defaults in UL Pcell in the prior art). The first carrier and the second carrier may be associated by configuration signaling and allow selection/switching of PUCCH transmission carriers between the first carrier and the second carrier. The PUCCH resources determined by the UE from the first carrier based on the PUCCH indication information in downlink control information (downlink control information, DCI) in the physical downlink control channel (physical downlink control channel, PDCCH) may be invalid. Then the UE may determine to select/switch the PUCCH transmission carrier to the second carrier. The PUCCH indication information may be automatically applied to the second carrier to determine valid PUCCH resources. For example, according to the configuration of the second carrier, PUCCH-related parameters such as k1 (PDSCH-to-harq_ feedback timing indicator, PDSCH-to-HARQ feedback timing indication), PRI (PUCCH resource indicator, PUCCH resource indication), TPC (transmit power control ) command for the scheduled PUCCH) and SCS (subcarrier spacing ) may be performed.
Here, the PUCCH may include any one of HARQ-ACK PUCCH, SR PUCCH, CSI PUCCH, negative acknowledgement only PUCCH (negative acknowledgement only PUCCH, NACK only PUCCH), acknowledgement only PUCCH (acknowledgement only PUCCH, ACK only PUCCH), and BFR (beam failure recovery, beam-failure recovery) PUCCH.
PUCCH resources may be available. If the PUCCH resource is valid, it may indicate that one PUCCH resource is located in an available uplink symbol and has available frequency domain resources. Otherwise, the PUCCH resource is invalid. For example, if a PUCCH resource determined based on PUCCH indication information in the first carrier overlaps one DL slot, the PUCCH resource is invalid. The effective PUCCH resource may also be a case where the resource corresponding to the determined PUCCH resource is an uplink resource, or the resource corresponding to the determined PUCCH resource is an uplink resource and transmission of the PUCCH resource is allowed, or the resource corresponding to the determined PUCCH resource does not overlap with a downlink resource, or the resource corresponding to the determined PUCCH resource is within a bandwidth range of the carrier.
The PUCCH indication information may include at least one of PDSCH to HARQ feedback timing indication (i.e., k 1) indicating a location of a slot where the PUCCH is located, PUCCH resource indication (i.e., PRI) indicating PUCCH resources from a PUCCH resource set, subcarrier spacing (i.e., SCS) indicating subcarrier spacing of a carrier where the PUCCH is located, and/or TPC command (i.e., TPC) for the scheduled PUCCH indicating power control information for PUCCH transmission.
If there are a plurality of second carriers, the UE may select one as the second carrier. If the second carriers are a plurality of carriers, the UE may attempt to determine PUCCH resources from each of the second carriers using at least one of the following rules until the first valid PUCCH is determined according to the PUCCH indication information. The second carrier where the first valid PUCCH resource is located is also referred to as a PUCCH transmission carrier.
The rule may include any one of a rule a attempting to determine the first valid PUCCH resource in ascending or descending order according to a secondary cell index (or a serving cell index) of the second carrier, or a rule B attempting to determine the first valid PUCCH resource in ascending or descending order according to a frequency point of the second carrier.
The rule may include one of attempting to determine an earliest and valid PUCCH resource from the plurality of second carriers. If several equally earliest and valid PUCCH resources are determined from several carriers of the plurality of second carriers, the final PUCCH resource may be determined from several carriers using either the a rule or the B rule.
GNodeB may configure the first carrier and the second carrier to be associated so as to switch PUCCH transmission carriers for the UE through radio resource control (Radio Resource Control, RRC) signaling or a medium access control-control element (MAC CE). The first carrier may include UL Pcell (PRIMARY CELL), and the second carrier may include UL Scell (secondary cell).
To achieve low UE cost, new signaling 1 may also be introduced to inform gNodeB that the UE has or does not have the capability to support carrier selection/handover for PUCCH transmission. For example, a new signaling 1 informs gNodeB that the UE can support selection/switching of the carrier for PUCCH transmission, gNodeB may instruct the UE to switch the PUCCH transmission carrier if gNodeB receives the new signaling 1, otherwise gNodeB cannot instruct the UE to switch the carrier for PUCCH transmission (which means PUCCH is transmitted in Pcell). For another example, a new signaling 1 informs gNodeB that the UE cannot support selection/switching of the carrier of PUCCH transmission, gNodeB may not instruct the UE to switch the carrier of PUCCH transmission if gNodeB receives the new signaling 1, otherwise gNodeB may instruct the UE to switch the carrier of PUCCH transmission.
To reduce the complexity of gNodeB scheduling, a new signaling 2 may be introduced to inform the UE that gNodeB allows (or does not allow) the UE to switch carriers for PUCCH transmission. The new signaling 2 may be configured to the UE by gNodeB through RRC or MAC CE signaling.
If multiple carriers are configured for handover of PUCCH transmission by the UE between the carriers, the bit size of the PUCCH-related parameter field (e.g. k1, PRI, TPC) in the DCI may be determined according to the configuration of the carrier yielding the largest bit size among the multiple carriers.
According to the method described in embodiment 1, the parameter fields in the DCI may not need to be modified.
Example embodiment 2
In embodiment 1, one PUCCH transmission carrier may always exist by default. After a predefined condition is met, the PUCCH transmission carrier may be switched to another carrier. In example 2, example 1 is further extended. For example, the default PUCCH transmission carrier is not required, but the PUCCH transmission carrier is always dynamically determined from a plurality of carriers associated with the handover PUCCH transmission carrier according to a predefined rule.
GNodeB and the UE may agree to determine the PUCCH transmission carrier according to the following predefined rule. For a UE, the plurality of carriers are configured to allow a PUCCH transmission carrier to be determined between the plurality of carriers. gNodeB may transmit PUCCH indication information. The UE may attempt to determine PUCCH resources from the plurality of carriers until the first valid PUCCH resource is determined according to the PUCCH indication information and one of the following predefined rules. The carrier on which the first valid PUCCH resource is located is used for transmitting PUCCH.
The predefined rule may include any one of a C rule that attempts to determine the first valid PUCCH resource in an ascending or descending order according to serving cell indexes of the plurality of carriers, or a D rule that attempts to determine the first valid PUCCH resource in an ascending or descending order according to frequency points of the plurality of carriers.
The rule may include attempting to determine the earliest and valid PUCCH resource from the plurality of carriers. If several equally earliest and valid PUCCH resources are determined from several carriers of the multiple carriers, the final PUCCH resource may be determined from several carriers using a C rule or a D rule.
Here, the PUCCH includes any one of HARQ-ACK PUCCH, SR PUCCH, CSI PUCCH, negative acknowledgement only PUCCH (NACK only PUCCH), acknowledgement only PUCCH (ACK only PUCCH), and BFR PUCCH.
If the PUCCH resource is valid, it may indicate that one PUCCH resource is located in an available uplink symbol and has available frequency domain resources. Otherwise, the PUCCH resource is invalid. For example, if PUCCCH resources determined based on PUCCH indication information in the first carrier overlap one DL slot, the PUCCH resources are invalid. The valid PUCCH resource may also be a case where the resource corresponding to the determined PUCCH resource may be an uplink resource, or the resource corresponding to the determined PUCCH resource is an uplink resource and is allowed to transmit the PUCCH resource, or the resource corresponding to the determined PUCCH resource does not overlap with a downlink resource, or the resource corresponding to the determined PUCCH resource is within a bandwidth range of the carrier.
The PUCCH indication information may include at least one of PDSCH to HARQ feedback timing indication (i.e., k 1) indicating a location of a slot where the PUCCH is located, PUCCH resource indication (i.e., PRI) indicating PUCCH resources from a PUCCH resource set, subcarrier spacing (i.e., SCS) indicating subcarrier spacing of a carrier where the PUCCH is located, and/or TPC command (i.e., TPC) for a scheduled PUCCH indicating power control information for PUCCH transmission.
To achieve low UE cost, new signaling 1 may also be introduced to inform gNodeB that the UE has or does not have the capability to support selection/handover of the carrier for PUCCH transmission. For example, a new signaling 1 informs gNodeB that the UE can support selection/switching of the carrier of PUCCH transmission, gNodeB may instruct the UE to switch the carrier of PUCCH transmission if gNodeB receives the new signaling 1, otherwise gNodeB cannot instruct the UE to switch the carrier of PUCCH transmission (which means PUCCH is transmitted in Pcell). For another example, a new signaling 1 informs gNodeB that the UE cannot support selection/switching of the carrier for PUCCH transmission, gNodeB cannot instruct the UE to switch the carrier for PUCCH transmission if gNodeB receives the new signaling 1, otherwise gNodeB may instruct the UE to switch the carrier for PUCCH transmission.
To reduce the complexity of gNodeB scheduling, a new signaling 2 may be introduced to inform the UE that gNodeB allows (or does not allow) the UE to switch carriers for PUCCH transmission. The new signaling 2 may be configured to the UE by gNodeB through RRC or MAC CE signaling.
If multiple carriers are configured for PUCCH transmission switching by the UE between the carriers, the bit size of the PUCCH-related parameter field (e.g. k1, PRI, TPC) in the DCI may be determined according to the configuration of the carrier yielding the largest bit size among the multiple carriers.
An advantage of embodiment 2 is that signaling indicating PUCCH transmission carriers may be avoided. Embodiment 2 may also be compatible with existing mechanisms, for example, with the method of transmitting PUCCH on PCell.
Fig. 2 is a block diagram of an exemplary method 200 of dynamically triggering carriers for a control channel. The method may include a terminal receiving resource information from a network node to determine transmission resources for transmitting control information to the network node (block 202).
The method may also include the terminal determining a final transmission resource from the first transmission resource and the second transmission resource using the resource information from the network node according to a predefined rule (block 204). The final transmission resources may include PUCCH transmission carriers as described herein.
The method may also include the terminal transmitting control information using the final transmission resource (block 206). The control information transmission may include a PUCCH transmission as described herein.
In some embodiments, the final transmission resource is determined by default from the first transmission resource, wherein in response to determining that the first transmission resource is invalid, the final transmission resource is determined from the second transmission resource according to a predefined rule.
In some embodiments, the first transmission resource is a default carrier including uplink Pell and the first transmission resource and the second transmission resource are associated by configuration signaling to switch a Physical Uplink Control Channel (PUCCH) transmission carrier between the first transmission resource and the second transmission resource.
In some embodiments, the final transmission resources comprise Physical Uplink Control Channel (PUCCH) resources and the resource information comprises PUCCH indication information located in Downlink Control Information (DCI) in a downlink message from the network node.
In some embodiments, based on determining that the PUCCH indication information corresponds to an active PUCCH resource in a second transmission resource associated with the first transmission resource to transmit control information on the second transmission resource.
In some embodiments, the control information includes any of a hybrid automatic repeat request (HARQ) Acknowledgement (ACK) PUCCH (HARQ-ACK PUCCH) message, a Scheduling Request (SR) PUCCH message, a Channel State Information (CSI) PUCCH message, a Negative Acknowledgement (NACK) only PUCCH message, an Acknowledgement (ACK) only PUCCH message, and a Beam Failure Recovery (BFR) PUCCH message.
In some embodiments, determining the final transmission resource includes determining that the PUCCH resource for control information transmission is invalid, wherein the invalid PUCCH resource includes a PUCCH resource that is not located in the available uplink symbols and/or frequency domain resources.
In some embodiments, the PUCCH indication information includes any of a Physical Downlink Shared Channel (PDSCH) to HARQ feedback timing indication (PDSCH-to-HARQ_ feedback timing indicator), a PUCCH Resource Indication (PRI), a sub-carrier spacing (SCS), and a Transmit Power Control (TPC) command for the scheduled PUCCH.
In some embodiments, the predefined rule includes determining valid PUCCH resources in ascending or descending order according to secondary cell indexes or serving cell indexes of the first transmission resources and/or the second transmission resources, wherein the valid PUCCH resources include PUCCH resources located in available uplink symbols and/or frequency domain resources.
In some embodiments, the predefined rule includes determining valid PUCCH resources in ascending or descending order according to frequency points of the first transmission resource and/or the second transmission resource, wherein the valid PUCCH resources include PUCCH resources located in available uplink symbols and/or frequency domain resources.
In some embodiments, the predefined rule includes determining a PUCCH resource from the first transmission resource and/or the second transmission resource based on an effective and earliest transmitted PUCCH resource, wherein the effective PUCCH resource includes a PUCCH resource located in the available uplink symbols and/or frequency domain resources.
In some embodiments, the method includes the terminal receiving a first signaling message from the network node, the first signaling message indicating whether to switch from the first transmission resource to the second transmission resource.
In some embodiments, the method includes the network node sending a second signaling message to the terminal, the second signaling message for instructing the network node to allow the terminal to switch carriers for PUCCH transmission, wherein the terminal is configured to determine carriers for PUCCH transmission between the associated first transmission resource and second transmission resource to allow switching of PUCCH transmission carriers.
In some embodiments, the terminal is configured to attempt to determine a PUCCH resource from the first transmission resource and the second transmission resource until a first valid PUCCH resource is determined, wherein the control information is transmitted on a carrier associated with the first valid PUCCH resource or associated with an earliest and valid PUCCH resource.
In another exemplary aspect, a method of wireless communication is disclosed. The method includes the network node transmitting resource information to determine transmission resources for transmitting control information to the terminal. The method further comprises the network node determining a final transmission resource from the first transmission resource and the second transmission resource using the resource information from the network node according to a predefined rule. The method further comprises the network node receiving control information from the terminal using the final transmission resource.
In some embodiments, the default final transmission resource is determined from the first transmission resource, wherein in response to determining that the first transmission resource is not valid, the final transmission resource is determined from the second transmission resource according to a predefined rule.
In some embodiments, the first transmission resource is a default carrier comprising an uplink primary cell (Pcell) and the second transmission resource comprises a secondary cell (Scell), wherein the first transmission resource and the second transmission resource are associated by configuration signaling for switching of Physical Uplink Control Channel (PUCCH) transmission carriers.
In some embodiments, the transmission resources comprise Physical Uplink Control Channel (PUCCH) resources and the resource information comprises PUCCH indication information located in Downlink Control Information (DCI) in a downlink message from the network node.
In some embodiments, the control information includes any of a hybrid automatic repeat request (HARQ) Acknowledgement (ACK) PUCCH (HARQ-ACK PUCCH) message, a Scheduling Request (SR) PUCCH message, a Channel State Information (CSI) PUCCH message, a Negative Acknowledgement (NACK) only PUCCH message, an Acknowledgement (ACK) only PUCCH message, and a Beam Failure Recovery (BFR) PUCCH message.
In some embodiments, based on determining that the PUCCH indication information corresponds to an active PUCCH resource in a second transmission resource associated with the first transmission resource to transmit control information on the second transmission resource.
In some embodiments, determining the final transmission resource includes determining that the PUCCH resource for control information transmission is invalid, wherein the invalid PUCCH resource includes a PUCCH resource that is not located in the available uplink symbols and/or frequency domain resources.
In some embodiments, the PUCCH indication information includes any of a Physical Downlink Shared Channel (PDSCH) to HARQ feedback timing indication (PDSCH-to-HARQ_ feedback timing indicator), a PUCCH Resource Indication (PRI), a sub-carrier spacing (SCS), and a Transmit Power Control (TPC) command for the scheduled PUCCH.
In some embodiments, the predefined rule includes determining valid PUCCH resources in ascending or descending order according to secondary cell indexes or serving cell indexes of the first transmission resources and/or the second transmission resources, wherein the valid PUCCH resources include PUCCH resources located in available uplink symbols and/or frequency domain resources.
In some embodiments, the predefined rule includes determining valid PUCCH resources in ascending or descending order according to frequency points of the first transmission resource and/or the second transmission resource, wherein the valid PUCCH resources include PUCCH resources located in available uplink symbols and/or frequency domain resources.
In some embodiments, the predefined rule includes determining a PUCCH resource from the first transmission resource and/or the second transmission resource based on an effective and earliest transmitted PUCCH resource, wherein the effective PUCCH resource includes a PUCCH resource located in the available uplink symbols and/or frequency domain resources.
In some embodiments, the method includes the network node sending a first signaling message to the terminal, the first signaling message indicating whether to switch from the first transmission resource to the second transmission resource.
In some embodiments, the method includes the network node sending a second signaling message to the terminal, the second signaling message for instructing the network node to allow the terminal to switch carriers for PUCCH transmission, wherein the terminal is configured to determine carriers for PUCCH transmission between the associated first transmission resource and second transmission resource to allow switching of PUCCH transmission carriers.
In some embodiments, the terminal is configured to attempt to determine a PUCCH resource from the first transmission resource and the second transmission resource until a first valid PUCCH resource is determined, wherein the control information is transmitted on a carrier associated with the first valid PUCCH resource or associated with an earliest and valid PUCCH resource.
Exemplary Wireless System
Fig. 3 illustrates an example of a wireless communication system that may employ techniques in accordance with one or more embodiments of the present technology. The wireless communication system 300 may include one or more Base Stations (BSs) 305a, 305b, one or more wireless devices or terminals 310a, 310b, 310c, 310d, and a core network (core network) 325. The base stations 305a, 305b may provide wireless services to wireless devices 310a, 310b, 310c, and 310d in one or more wireless sectors. In some implementations, the base stations 305a, 305b include directional antennas to generate two or more directional beams to provide wireless coverage in different sectors. As described herein, a base station may implement the functionality of a scheduling cell or candidate cell.
The core network 325 may communicate with one or more base stations 305a, 305 b. The core network 325 provides connectivity to other wireless communication systems and to wired communication systems. The core network may include one or more service subscription databases to store information related to subscribed wireless devices 310a, 310b, 310c, and 310 d. The first base station 305a may provide wireless services based on a first radio access technology and the second base station 305b may provide wireless services based on a second radio access technology. Depending on the deployment scenario, base stations 305a and 305b may be co-located or installed separately on site. Wireless devices 310a, 310b, 310c, and 310d may support a variety of different radio access technologies.
In some implementations, a wireless communication system may include multiple networks using different wireless technologies. Dual or multi-mode wireless devices include two or more wireless technologies that may be used to connect different wireless networks.
FIG. 4 is a block diagram representing a portion of a hardware platform. The hardware platform 405, e.g., a network node, or base station, or terminal, or wireless device (or UE), may include processor electronics 410. Processor electronics 410 is, for example, a microprocessor that implements one or more of the techniques presented herein. The hardware platform 405 may include transceiver electronics 415 to transmit and/or receive wired or wireless signals over one or more communication interfaces (e.g., antenna 420 or a wired interface). The hardware platform 405 may implement other communication interfaces having protocols defined for sending and receiving data. The hardware platform 405 may include one or more memories (not explicitly shown) configured to store information such as data and/or instructions. In some implementations, the processor electronics 410 may include at least a portion of the transceiver electronics 415. In some embodiments, at least a portion of the disclosed techniques, modules, or functions are implemented using hardware platform 405.
Conclusion(s)
The embodiments, modules, and functional operations disclosed in the description of this document and others may be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments may be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer-readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a storage device, a combination of materials that affect a machine-readable propagated signal, or a combination of one or more of them. The term "data processing apparatus" includes all apparatuses, devices and machines for processing data, including for example a programmable processor, a computer, or multiple processors or multiple computers. In addition to hardware, the data processing apparatus may include code that creates an execution environment for the computer program concerned, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.
A computer program (also known as a program, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. The computer program does not necessarily correspond to a file in a file system. A program may be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub-programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.
The processes and logic flows described in this document can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry. The dedicated logic circuit is, for example, a field programmable gate array (field programmable GATE ARRAY, FPGA) or an application-specific integrated circuit (ASIC).
Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Typically, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data (e.g., magnetic, magneto-optical disks, or optical disks). However, the computer need not have such a device. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and storage devices, including by way of example semiconductor memory devices such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY, EEPROM) and flash memory devices, magnetic disks such as internal hard disks or removable disks, magneto-optical disks, and compact disc-read-only memory (CD-ROM) and digital video disks (digital video disc-read only memory, DVD-ROM). The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.
Although this patent document contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features specific to particular embodiments of particular inventions. In this patent document, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
Similarly, although operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Furthermore, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.
Only a few implementations and examples are described in this patent document, and other implementations, modifications, and variations are possible in light of the description and illustration of this patent document.