Patent Application
20240040625
Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for random access.
Wireless communications systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, or other similar types of services. These wireless communications systems may employ multiple-access technologies capable of supporting communications with multiple users by sharing available wireless communications system resources with those users
Although wireless communications systems have made great technological advancements over many years, challenges still exist. For example, complex and dynamic environments can still attenuate or block signals between wireless transmitters and wireless receivers. Accordingly, there is a continuous desire to improve the technical performance of wireless communications systems, including, for example: improving speed and data carrying capacity of communications, improving efficiency of the use of shared communications mediums, reducing power used by transmitters and receivers while performing communications, improving reliability of wireless communications, avoiding redundant transmissions and/or receptions and related processing, improving the coverage area of wireless communications, increasing the number and types of devices that can access wireless communications systems, increasing the ability for different types of devices to intercommunicate, increasing the number and type of wireless communications mediums available for use, and the like. Consequently, there exists a need for further improvements in wireless communications systems to overcome the aforementioned technical challenges and others.
In random access, UEs transmit a random access preamble as part of a random access procedure. Because there are a limited number of random access preambles and random access channel (RACH) resources, UEs may transmit random access preambles that collide. That is, the UEs may transmit identical random access preambles using the same RACH resources. When UEs transmit colliding random access preambles, the network transmission random access response message with a timing advance command, and both (or however many UEs transmit the colliding random access preambles) UEs receive the random access response message and transmit a physical uplink shared channel (PUSCH) payload to the network using the same TAC. Thus, the PUSCH transmissions from the UEs also collide at the network entity. The network entity may not be able to successfully decode one or more of the colliding PUSCH transmissions. In this case, the UEs may need to retransmit the PUSCH transmission and/or the random access preamble, thereby limiting the channel capacity.
According to aspects of the present disclosure, UEs may be configured to independently determine a second timing advance based on a first timing advance and transmit random access preamble using the second timing advance. When the network entity transmits a random access response message with a TAC, each UE can determine whether the random access response message is intended for itself based, for example, on the TAC, the first timing advance, and the second timing advance. For example, the UE may determine whether the random access response message is intended for itself based on a difference between the TAC and the difference between the first and second timing advances. The UE can then determine whether to send a PUSCH transmission to the network entity based on whether the random access response message was determined to be intended for that UE or not. Accordingly, PUSCH transmission collisions at the network entity can be avoided, thereby increasing the channel capacity.
One aspect provides a method for wireless communication by a user equipment (UE). The method includes determining a first timing advance (TA) for transmitting a random access channel (RACH) preamble. The method includes determining a second TA, different than the first TA, for transmitting the RACH preamble. The method includes transmitting the RACH preamble using the second TA. The method includes receiving a random access response (RAR) message including a timing advance command (TAC). The method includes determining whether the RAR is intended for the UE based on the TAC, the first TA, and the second TA. The method includes transmitting a physical uplink shared channel (PUSCH) transmission based on a determination that the RAR is intended for the UE.
Another aspect provides a method for wireless communication by a network entity. The method includes outputting a TA configuration for a first UE and a second UE. The method includes obtaining a first RACH preamble from the first UE using a first TA and a second RACH preamble from the second UE using a second TA. The first RACH preamble and the second RACH preamble comprise an identical RACH sequence. The method includes outputting a RAR message including a TAC. The method includes obtaining a PUSCH transmission from the UE or the second UE based on the TAC.
Other aspects provide: an apparatus operable, configured, or otherwise adapted to perform the aforementioned methods as well as those described elsewhere herein; a non-transitory, computer-readable media comprising instructions that, when executed by a processor of an apparatus, cause the apparatus to perform the aforementioned methods as well as those described elsewhere herein; a computer program product embodied on a computer-readable storage medium comprising code for performing the aforementioned methods as well as those described elsewhere herein; and an apparatus comprising means for performing the aforementioned methods as well as those described elsewhere herein. By way of example, an apparatus may comprise a processing system, a device with a processing system, or processing systems cooperating over one or more networks.
The following description and the appended figures set forth certain features for purposes of illustration.
The appended figures depict certain features of the various aspects described herein and are not to be considered limiting of the scope of this disclosure.
Aspects of the present disclosure provide apparatuses, methods, processing systems, and computer-readable mediums for timing advances in random access.
The techniques and methods described herein may be used for various wireless communications networks. While aspects may be described herein using terminology commonly associated with 3G, 4G, and/or 5G wireless technologies, aspects of the present disclosure may likewise be applicable to other communications systems and standards not explicitly mentioned herein.
Generally, wireless communications network 100 includes various network entities (alternatively, network elements or network nodes). A network entity is generally a communications device and/or a communications function performed by a communications device (e.g., a user equipment (UE), a base station (BS), a component of a BS, a server, etc.). For example, various functions of a network as well as various devices associated with and interacting with a network may be considered network entities. Further, wireless communications network 100 includes terrestrial aspects, such as ground-based network entities (e.g., BSs 102), and non-terrestrial aspects, such as satellite 140 and aircraft 145, which may include network entities on-board (e.g., one or more BSs) capable of communicating with other network elements (e.g., terrestrial BSs) and user equipments.
In the depicted example, wireless communications network 100 includes BSs 102, UEs 104, and one or more core networks, such as an Evolved Packet Core (EPC) 160 and 5G Core (5GC) network 190, which interoperate to provide communications services over various communications links, including wired and wireless links.
BSs 102 wirelessly communicate with (e.g., transmit signals to or receive signals from) UEs 104 via communications links 120. The communications links 120 between BSs 102 and UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a BS 102 and/or downlink (DL) (also referred to as forward link) transmissions from a BS 102 to a UE 104. The communications links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity in various aspects.
BSs 102 may generally include: a NodeB, enhanced NodeB (eNB), next generation enhanced NodeB (ng-eNB), next generation NodeB (gNB or gNodeB), access point, base transceiver station, radio base station, radio transceiver, transceiver function, transmission reception point, and/or others. Each of BSs 102 may provide communications coverage for a respective geographic coverage area 110, which may sometimes be referred to as a cell, and which may overlap in some cases (e.g., small cell 102′ may have a coverage area 110′ that overlaps the coverage area 110 of a macro cell). A BS may, for example, provide communications coverage for a macro cell (covering relatively large geographic area), a pico cell (covering relatively smaller geographic area, such as a sports stadium), a femto cell (relatively smaller geographic area (e.g., a home)), and/or other types of cells.
While BSs 102 are depicted in various aspects as unitary communications devices, BSs 102 may be implemented in various configurations. For example, one or more components of a base station may be disaggregated, including a central unit (CU), one or more distributed units (DUs), one or more radio units (RUs), a Near-Real Time (Near-RT) RAN Intelligent Controller (RIC), or a Non-Real Time (Non-RT) RIC, to name a few examples. In another example, various aspects of a base station may be virtualized. More generally, a base station (e.g., BS 102) may include components that are located at a single physical location or components located at various physical locations. In examples in which a base station includes components that are located at various physical locations, the various components may each perform functions such that, collectively, the various components achieve functionality that is similar to a base station that is located at a single physical location. In some aspects, a base station including components that are located at various physical locations may be referred to as a disaggregated radio access network architecture, such as an Open RAN (O-RAN) or Virtualized RAN (VRAN) architecture.
Different BSs 102 within wireless communications network 100 may also be configured to support different radio access technologies, such as 3G, 4G, and/or 5G. For example, BSs 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC 160 through first backhaul links 132 (e.g., an S1 interface). BSs 102 configured for 5G (e.g., 5GNR or Next Generation RAN (NG-RAN)) may interface with 5GC 190 through second backhaul links 184. BSs 102 may communicate directly or indirectly (e.g., through the EPC 160 or 5GC 190) with each other over third backhaul links 134 (e.g., X2 interface), which may be wired or wireless.
Wireless communications network 100 may subdivide the electromagnetic spectrum into various classes, bands, channels, or other features. In some aspects, the subdivision is provided based on wavelength and frequency, where frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, or a subband. For example, 3GPP currently defines Frequency Range 1 (FR1) as including 410 MHz-7125 MHz, which is often referred to (interchangeably) as “Sub-6 GHz”. Similarly, 3GPP currently defines Frequency Range 2 (FR2) as including 24,250 MHz-52,600 MHz, which is sometimes referred to (interchangeably) as a “millimeter wave” (“mmW” or “mmWave”). A base station configured to communicate using mmWave/near mmWave radio frequency bands (e.g., a mmWave base station such as BS 180) may utilize beamforming (e.g., 182) with a UE (e.g., 104) to improve path loss and range.
The communications links 120 between BSs 102 and, for example, UEs 104, may be through one or more carriers, which may have different bandwidths (e.g., 5, 10, 15, 20, 100, 400, and/or other MHz), and which may be aggregated in various aspects. Carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL).
Communications using higher frequency bands may have higher path loss and a shorter range compared to lower frequency communications. Accordingly, certain base stations (e.g., 180 in
Wireless communications network 100 further includes a Wi-Fi AP 150 in communication with Wi-Fi stations (STAs) 152 via communications links 154 in, for example, a 2.4 GHz and/or 5 GHz unlicensed frequency spectrum.
Certain UEs 104 may communicate with each other using device-to-device (D2D) communications link 158. D2D communications link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), a physical sidelink control channel (PSCCH), and/or a physical sidelink feedback channel (PSFCH).
EPC 160 may include various functional components, including: a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and/or a Packet Data Network (PDN) Gateway 172, such as in the depicted example. MME 162 may be in communication with a Home Subscriber Server (HSS) 174. MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, MME 162 provides bearer and connection management.
Generally, user Internet protocol (IP) packets are transferred through Serving Gateway 166, which itself is connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation as well as other functions. PDN Gateway 172 and the BM-SC 170 are connected to IP Services 176, which may include, for example, the Internet, an intranet, an IP Multimedia Subsystem (IMS), a Packet Switched (PS) streaming service, and/or other IP services.
BM-SC 170 may provide functions for MBMS user service provisioning and delivery. BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and/or may be used to schedule MBMS transmissions. MBMS Gateway 168 may be used to distribute MBMS traffic to the BSs 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and/or may be responsible for session management (start/stop) and for collecting eMBMS related charging information.
5GC 190 may include various functional components, including: an Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. AMF 192 may be in communication with Unified Data Management (UDM) 196.
AMF 192 is a control node that processes signaling between UEs 104 and 5GC 190. AMF 192 provides, for example, quality of service (QoS) flow and session management.
Internet protocol (IP) packets are transferred through UPF 195, which is connected to the IP Services 197, and which provides UE IP address allocation as well as other functions for 5GC 190. IP Services 197 may include, for example, the Internet, an intranet, an IMS, a PS streaming service, and/or other IP services.
In various aspects, a network entity or network node can be implemented as an aggregated base station, as a disaggregated base station, a component of a base station, an integrated access and backhaul (IAB) node, a relay node, a sidelink node, to name a few examples.
Each of the units, e.g., the CUs 210, the DUs 230, the RUs 240, as well as the Near-RT RICs 225, the Non-RT RICs 215 and the SMO Framework 205, may include one or more interfaces or be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively, signals) via a wired or wireless transmission medium. Each of the units, or an associated processor or controller providing instructions to the communications interfaces of the units, can be configured to communicate with one or more of the other units via the transmission medium. For example, the units can include a wired interface configured to receive or transmit signals over a wired transmission medium to one or more of the other units. Additionally or alternatively, the units can include a wireless interface, which may include a receiver, a transmitter or transceiver (such as a radio frequency (RF) transceiver), configured to receive or transmit signals, or both, over a wireless transmission medium to one or more of the other units.
In some aspects, the CU 210 may host one or more higher layer control functions. Such control functions can include radio resource control (RRC), packet data convergence protocol (PDCP), service data adaptation protocol (SDAP), or the like. Each control function can be implemented with an interface configured to communicate signals with other control functions hosted by the CU 210. The CU 210 may be configured to handle user plane functionality (e.g., Central Unit—User Plane (CU-UP)), control plane functionality (e.g., Central Unit—Control Plane (CU-CP)), or a combination thereof. In some implementations, the CU 210 can be logically split into one or more CU-UP units and one or more CU-CP units. The CU-UP unit can communicate bidirectionally with the CU-CP unit via an interface, such as the E1 interface when implemented in an O-RAN configuration. The CU 210 can be implemented to communicate with the DU 230, as necessary, for network control and signaling.
The DU 230 may correspond to a logical unit that includes one or more base station functions to control the operation of one or more RUs 240. In some aspects, the DU 230 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, or the like) depending, at least in part, on a functional split, such as those defined by the 3rd Generation Partnership Project (3GPP). In some aspects, the DU 230 may further host one or more low PHY layers. Each layer (or module) can be implemented with an interface configured to communicate signals with other layers (and modules) hosted by the DU 230, or with the control functions hosted by the CU 210.
Lower-layer functionality can be implemented by one or more RUs 240. In some deployments, an RU 240, controlled by a DU 230, may correspond to a logical node that hosts RF processing functions, or low-PHY layer functions (such as performing fast Fourier transform (FFT), inverse FFT (iFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, or the like), or both, based at least in part on the functional split, such as a lower layer functional split. In such an architecture, the RU(s) 240 can be implemented to handle over the air (OTA) communications with one or more UEs 104. In some implementations, real-time and non-real-time aspects of control and user plane communications with the RU(s) 240 can be controlled by the corresponding DU 230. In some scenarios, this configuration can enable the DU(s) 230 and the CU 210 to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.
The SMO Framework 205 may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network elements. For non-virtualized network elements, the SMO Framework 205 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements which may be managed via an operations and maintenance interface (such as an O1 interface). For virtualized network elements, the SMO Framework 205 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 290) to perform network element life cycle management (such as to instantiate virtualized network elements) via a cloud computing platform interface (such as an O2 interface). Such virtualized network elements can include, but are not limited to, CUs 210, DUs 230, RUs 240 and Near-RT RICs 225. In some implementations, the SMO Framework 205 can communicate with a hardware aspect of a 4G RAN, such as an open eNB (O-eNB) 211, via an O1 interface. Additionally, in some implementations, the SMO Framework 205 can communicate directly with one or more RUs 240 via an O1 interface. The SMO Framework 205 also may include a Non-RT RIC 215 configured to support functionality of the SMO Framework 205.
The Non-RT RIC 215 may be configured to include a logical function that enables non-real-time control and optimization of RAN elements and resources, Artificial Intelligence/Machine Learning (AI/ML) workflows including model training and updates, or policy-based guidance of applications/features in the Near-RT RIC 225. The Non-RT RIC 215 may be coupled to or communicate with (such as via an A1 interface) the Near-RT RIC 225. The Near-RT RIC 225 may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (such as via an E2 interface) connecting one or more CUs 210, one or more DUs 230, or both, as well as an O-eNB, with the Near-RT RIC 225.
In some implementations, to generate AI/ML models to be deployed in the Near-RT RIC 225, the Non-RT RIC 215 may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC 225 and may be received at the SMO Framework 205 or the Non-RT RIC 215 from non-network data sources or from network functions. In some examples, the Non-RT RIC 215 or the Near-RT RIC 225 may be configured to tune RAN behavior or performance. For example, the Non-RT RIC 215 may monitor long-term trends and patterns for performance and employ AI/ML models to perform corrective actions through the SMO Framework 205 (such as reconfiguration via O1) or via creation of RAN management policies (such as A1 policies).
Generally, BS 102 includes various processors (e.g., 320, 330, 338, and 340), antennas 334a-t (collectively 334), transceivers 332a-t (collectively 332), which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., data source 312) and wireless reception of data (e.g., data sink 339). For example, BS 102 may send and receive data between BS 102 and UE 104. BS 102 includes controller/processor 340, which may be configured to implement various functions described herein related to wireless communications.
Generally, UE 104 includes various processors (e.g., 358, 364, 366, and 380), antennas 352a-r (collectively 352), transceivers 354a-r (collectively 354), which include modulators and demodulators, and other aspects, which enable wireless transmission of data (e.g., retrieved from data source 362) and wireless reception of data (e.g., provided to data sink 360). UE 104 includes controller/processor 380, which may be configured to implement various functions described herein related to wireless communications.
In regards to an example downlink transmission, BS 102 includes a transmit processor 320 that may receive data from a data source 312 and control information from a controller/processor 340. The control information may be for the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical HARQ indicator channel (PHICH), physical downlink control channel (PDCCH), group common PDCCH (GC PDCCH), and/or others. The data may be for the physical downlink shared channel (PDSCH), in some examples.
Transmit processor 320 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. Transmit processor 320 may also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), PBCH demodulation reference signal (DMRS), and channel state information reference signal (CSI-RS).
Transmit (TX) multiple-input multiple-output (MIMO) processor 330 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) in transceivers 332a-332t. Each modulator in transceivers 332a-332t may process a respective output symbol stream to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from the modulators in transceivers 332a-332t may be transmitted via the antennas 334a-334t, respectively.
In order to receive the downlink transmission, UE 104 includes antennas 352a-352r that may receive the downlink signals from the BS 102 and may provide received signals to the demodulators (DEMODs) in transceivers 354a-354r, respectively. Each demodulator in transceivers 354a-354r may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples to obtain received symbols.
MIMO detector 356 may obtain received symbols from all the demodulators in transceivers 354a-354r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. Receive processor 358 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 104 to a data sink 360, and provide decoded control information to a controller/processor 380.
In regards to an example uplink transmission, UE 104 further includes a transmit processor 364 that may receive and process data (e.g., for the PUSCH) from a data source 362 and control information (e.g., for the physical uplink control channel (PUCCH)) from the controller/processor 380. Transmit processor 364 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS)). The symbols from the transmit processor 364 may be precoded by a TX MIMO processor 366 if applicable, further processed by the modulators in transceivers 354a-354r (e.g., for SC-FDM), and transmitted to BS 102.
At BS 102, the uplink signals from UE 104 may be received by antennas 334a-t, processed by the demodulators in transceivers 332a-332t, detected by a MIMO detector 336 if applicable, and further processed by a receive processor 338 to obtain decoded data and control information sent by UE 104. Receive processor 338 may provide the decoded data to a data sink 339 and the decoded control information to the controller/processor 340.
Memories 342 and 382 may store data and program codes for BS 102 and UE 104, respectively.
Scheduler 344 may schedule UEs for data transmission on the downlink and/or uplink.
In various aspects, BS 102 may be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” may refer to various mechanisms of outputting data, such as outputting data from data source 312, scheduler 344, memory 342, transmit processor 320, controller/processor 340, TX MIMO processor 330, transceivers 332a-t, antenna 334a-t, and/or other aspects described herein. Similarly, “receiving” may refer to various mechanisms of obtaining data, such as obtaining data from antennas 334a-t, transceivers 332a-t, RX MIMO detector 336, controller/processor 340, receive processor 338, scheduler 344, memory 342, and/or other aspects described herein.
In various aspects, UE 104 may likewise be described as transmitting and receiving various types of data associated with the methods described herein. In these contexts, “transmitting” may refer to various mechanisms of outputting data, such as outputting data from data source 362, memory 382, transmit processor 364, controller/processor 380, TX MIMO processor 366, transceivers 354a-t, antenna 352a-t, and/or other aspects described herein. Similarly, “receiving” may refer to various mechanisms of obtaining data, such as obtaining data from antennas 352a-t, transceivers 354a-t, RX MIMO detector 356, controller/processor 380, receive processor 358, memory 382, and/or other aspects described herein.
In some aspects, a processor may be configured to perform various operations, such as those associated with the methods described herein, and transmit (output) to or receive (obtain) data from another interface that is configured to transmit or receive, respectively, the data.
In particular,
Wireless communications systems may utilize orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on the uplink and downlink. Such systems may also support half-duplex operation using time division duplexing (TDD). OFDM and single-carrier frequency division multiplexing (SC-FDM) partition the system bandwidth (e.g., as depicted in
A wireless communications frame structure may be frequency division duplex (FDD), in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for either DL or UL. Wireless communications frame structures may also be time division duplex (TDD), in which, for a particular set of subcarriers, subframes within the set of subcarriers are dedicated for both DL and UL.
In
In certain aspects, the number of slots within a subframe is based on a slot configuration and a numerology. For example, for slot configuration 0, different numerologies (μ) 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology p, there are 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2μ×15 kHz, where is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing.
As depicted in
As illustrated in
A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE (e.g., 104 of
A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing.
Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI). Based on the PCI, the UE can determine the locations of the aforementioned DMRS. The physical broadcast channel (PBCH), which carries a master information block (MIB), may be logically grouped with the PSS and SSS to form a synchronization signal (SS)/PBCH block. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs), and/or paging messages.
As illustrated in
Aspects of the disclosure related to timing advances for random access. A random access channel is so named because it refers to a wireless channel (medium) that may be shared by multiple UEs (e.g., such as UE 104 of
Network entity 502 may respond with a RAR message (MSG 2) which may include the identifier (ID) of the RACH preamble, a timing advance command (TAC), an uplink grant, a temporary cell radio network temporary identifier (TC-RNTI), and a back off indicator.
In response to the MSG2, a MSG3 is transmitted from the UE 504 to network entity 502 on the PUSCH. The MSG3 may include one or more of a RRC connection request, a tracking area update (TAU) request, a system information request, a positioning fix or positioning signal request, UE-ID such as a C-RNTI, medium access control control element (MAC CE), or a scheduling request.
The network entity 502 then responds with MSG 4 which may include a contention resolution message and/or a DCI.
In some cases, to speed up access, a two-step RACH procedure may be supported. As the name implies, the two-step RACH procedure effectively “collapses” the four messages of the four-step RACH procedure into two messages.
Network entity 602 may respond with a RAR message (MSGB) which may effectively combine the MSG2 and MSG4 described above. For example, MSGB may include the ID of the RACH preamble, a TAC, a back off indicator, a contention resolution message, UL/DL grant, and transmit power control (TPC) commands.
In some cases, RACH preambles from multiple UEs may “collide.”
At 712, in response to receiving the MSG 1, the network entity 702 sends a MSG 2 RAR with a resource allocation, MCS, and TAC for a MSG 3. Because the RACH preambles are identical, the UE 704 and the UE 706 receive the same MSG 2.
In response to receiving the same MSG 2, both the UE 704 and the UE 704 transmit MSG 3 to the network entity 702 in the same resource, at 714 and 716, respectively. The MSG 3 transmissions from the UE 704 and the UE 706, thus, may collide at the network entity 702 resulting in a reduced signal to interference noise ratio (SINR), for example, an SINR below 0 dB. The low SINR may result in the network entity 702 failing to successfully receive and decode one or both of the MSG3 transmissions from the one or both UEs and, thus, the network entity 702 may fail to transmit a response (e.g. a MSG4 and/or a DCI) to acknowledge the MSG3 reception to the one or both UEs. When the MSG3 transmission is not successfully received by the network entity 702, the UEs may need to retransmit the MSG3 or may need to transmit both the MSG1 and the MSG3. Accordingly, the system capacity may be limited due to the collision happened during the random access.
It should be noted that while
As discussed above, wireless communications network 100 may include terrestrial aspects, such as ground-based network entities (e.g., BSs 102), and non-terrestrial aspects, such as satellite 140 and aircraft 145, which may include network entities on-board (e.g., at least part of one or more BSs) capable of communicating with other network elements (e.g., terrestrial BSs and/or non-terrestrial BSs) and UEs.
Satellite 140 may communicate with the BS 102 and UE 104 as part of wireless communications in an NTN. The UE 104 may communicate with the BS 102 over a communication link 814. Satellite 140 may be a serving cell for the UE 104 via a communication link 816 referred to as a service link. In certain aspects, the satellite 140 may act as a relay (or a remote radio head) for the BS 102 and the UE 104. For example, the BS 102 may communicate with the satellite 140 via a communication link 818 (referred to as a feeder link), and the non-terrestrial network entity may relay signaling between the BS 102 and UE 104 via the communication links 816 and 818.
An NTN may serve UEs in a rural area. The satellite 140 (or other NTN entity) can serve a very large coverage area 110b. In some cases, UEs in the NTN coverage area 110b communicate using small message, such as using NB Internet-of-Things (IoT). In some cases, these UEs can send a small message in the MSG3/MSGB during random access, referred to as an early data transmission (EDT) or small data transmission (SDT). Because the NTN coverage area 110b is large, there may be many UEs served within the NTN coverage area 110b. Thus, there may be a higher likelihood of RACH preamble collision and missed EDTs.
Accordingly, techniques for random access procedures with reduced collision rates are desirable.
Aspects of the present disclosure provide techniques, apparatus, and computer readable media for random access with reduced collisions.
As shown, the network entity 902 may configure the UE 904 and the UE 906 with a timing advance configuration. In some aspects, the TA configuration configures a range of timing advances, a range of TA offsets (a) and/or its distribution, a TA value, and/or one or more thresholds. The TA configuration is discussed in more detail below with respect to 916, 918, 926, and 928 of the process flow 900. In some examples, the network entity 902 determines the range of TA offsets and/or its distribution to configure based on a capability of the network entity 902 to decode a RACH preamble. In some examples, the TA configuration configures the range of the second difference between the first and the second TAs or the range of offsets according to uniform distribution. In some examples, the TA configuration may be broadcast, e.g. in SIB, to the UEs or provided to the UEs in RRC signaling.
Although the configuration at 908 and 910 is shown at the same time in
In some aspects, the TA configuration, or a portion of the TA configuration may be pre-configured, such as hardcoded at the UE 904 and the UE 906, and/or specified in a wireless standard (e.g., a 3GPP technical standard).
The UE 904 determines a first TA, at 912, and the UE 906 determines a first TA at 914. The UE 904 and the UE 906 may determine the first TA according to known TA determination techniques specified the 3GPP wireless standards, e.g. in TS 38.211 and/or TS 38.213. The UE 904 and the UE 906 may determine the first TA based on a location of the UE, ephemeris information associated with an NTN entity (in an NTN network), location of the network entity 902, received TA command(s), and/or one or more common TA parameters. The UE 904 and the UE 906 may determine the first TA to compensate for a round trip time (RTT) between the UE and an uplink synchronization reference point. The uplink synchronization reference point may be determined by the network.
The UE 904 determines a second TA, at 916, and the UE 906 determines a second TA at 918. The UE 904 and the UE 906 may determine their respective second TA based on the configured, or preconfigured, TA configuration. The UE 904 and the UE 906 independently determine a second TA. That is, the UE 904 and the UE 906 may determine different second TAs.
In some examples, both the UE 904 and the UE 906 randomly select the second TA from a configured, or preconfigured, range of TAs. In some examples, both the UE 904 and the UE 906 randomly select an offset (a) value from a configured, or preconfigured, range of offset values. The UE 904 and the UE 906 can each apply the selected offset value to the determined first TA in order to determine the respective second TA. The second TA has a second difference of a with respect to the first TA (e.g., second TA=first TA−σ). Since the first TA is applied by the UE such that the timing of its uplink transmission arriving at the uplink synchronization reference point may align with the uplink slot timing at the uplink synchronization reference point, a effectively contributes to the offset between the timing of the UE's uplink transmission arriving at the uplink synchronization reference point and the uplink slot timing at the uplink synchronization reference point. Thus, if two UEs applies different values of a to transmit their uplinks in the same uplink slot, the signal would arrive at the network entity at different times.
In some examples, the second TA is equal to or smaller than the first TA. A second TA smaller than the first TA may ensure that the TAC, provided by the network entity 902 in the RAR (e.g., in the MSG2 discussed in more detail below with respect to 924 of the process flow 900) is a unipolar value.
At 920, the UE 904 sends a RACH preamble transmission (e.g., MSG1) to the network entity 902 using the second TA determined by the UE 904 at 916. At 922, the UE 906 sends a RACH preamble transmission (e.g., MSG1) to the network entity 902 using the second TA determined by the UE 906 at 918. The RACH preambles transmitted to the network entity 902 by the UE 904 and the UE 906 may collide. That is, as discussed above, the RACH preamble transmitted by the UE 904 and the RACH preamble transmitted by the UE 906 may be identical, having the same RACH preamble sequence and in the same RACH occasion. However, the RACH preambles arrive at the network entity at different times due to the different second TAs determined by the UE 904 and the UE 906. More specifically, the RACH preambles arrive at the network entity at different times due to the different values of a determined by the UE 904 and the UE 906. Accordingly, as discussed in more detail below, the use of the second TA may enable avoidance of a MSG3 collision even where the RACH preambles are identical.
Upon receiving the multiple RACH preambles replicas with a time difference, the network entity 902 determines a TAC based on one of the RACH preambles. At 924, the network entity 902 transmits a MSG2 to the UE 904 and the UE 906 with the TAC. The MSG2 may also include any of the information discussed above with respect to the MSG2 in
Both the UE 904 and the UE 906 may receive the MSG2 transmission. Upon receiving the MSG2 with the TAC, the UE 904 may determine whether the MSG2 is intended for the UE 904 based on the TAC received at 924, the first TA determined at 912, and the second TA determined at 916. For example, the UE 904 may determine whether the MSG2 is intended for the UE 904 based on a first difference of the TA indicated by the received TAC and a second difference between the first TA and the second TA (e.g., TAC−σ, where σ=first TA−second TA). In some examples, the UE 904 determines that the MSG2 is intended for the UE 904 when the first difference is smaller than a threshold, e.g., as shown at 926. Similarly, the UE 906 may determine whether the MSG2 is intended for the UE 906 based on the TAC received at 924, the first TA determined at 914, and the second TA determined at 918. In some examples, the UE 906 determines that the MSG2 is not intended for the UE 906 when the first difference is equal to or larger than the threshold, e.g., as shown at 928.
In some examples, the threshold is configured or preconfigured. For example, the threshold may be configured with the TA configuration at 908 and 910.
In some examples, the threshold may depend on the accuracy of the first TA, determined at 912 and 914. For example, if an orbit propagator model or global navigation satellite system (GNSS) model used by the UE 904 and/or the UE 906 has a low accuracy, the timing advance determined by the UE, e.g. the first TA, which is based on location information of the UE and the satellite, will be less accurate. The model used by the UE may be less accurate, for example, for a low cost UE or a low complexity UE. In this case, the TAC in the MSG2 from the network entity 902 may contain a TA value located within a large range statistically, because the time difference between the RACH preamble arriving at the network entity 902 and the uplink slot timing at the network entity is located within a large range due to the inaccuracy of the TA. Thus, a larger threshold may be used when the TA determined by the UEs is less accurate. In this case, use of the larger threshold may lessen the probability of false detection, where the MSG2 is intended for a UE but the UE considers MSG2 is not intended for the UE due to the first difference between the TA indicated by the received TAC and the second difference between the first TA and the second TA being equal or larger than the threshold (TAC−σ≥threshold).
In some examples, the UE 904, the UE 906, or the network entity 902 may adjust the threshold based on a number of random access attempts. For example, if the UE 904 or the UE 906 performs MSG1 transmission for a threshold (e.g., a configured or preconfigured threshold) number of times and the corresponding MSG2 transmissions are determined as not intended for the UE, then the UE may adjust the threshold. The adjusted threshold may be a larger threshold. In some examples, the UE adjusts the threshold by a configured, or preconfigured, offset from the current threshold.
When the UE 904 determines, at 926, that the MSG2 is intended for the UE 904, then the UE 904 transmits the MSG3 at 930, as shown. The MSG3 may include any of the information discussed above with respect to the MSG3 in
At 932, network entity 902 transmit a MSG4 to the UE 904. The MSG4 may include any of the information discussed above with respect to the MSG4 in
According to certain aspects, the network entity 902 can transmit multiple MSG2 transmissions when the network entity 902 detects identical RACH preambles but with a time difference (e.g., due to different second TAs and/or a values used for the RACH preambles, as described herein), as illustrated in the process flow 1000 in
The UE 904 and the 906 monitor and receive both the first MSG2 transmission at 924 and the second MSG2 transmission at 1015 and determine whether the MSG2 transmissions are intended for the UEs as described above with respect to
As shown, the UE 904 determines, at 926, that the first MSG2 RAR is intended for the UE 904. The UE 904 determines (not shown) that the second MSG2 RAR is not intended for the UE 904. Accordingly, the UE 904 transmits the first MSG3 PUSCH at 930 using the information (e.g. TAC and uplink grant) indicated in the first MSG2 RAR and monitors the first MSG4 from the network entity at 921 based on the information indicated in the first MSG2 RAR, e.g. TC-RNTI in the first MSG2 RAR.
As shown, the UE 906 determines, at 1027, that the second MSG2 RAR is intended for the UE 906. The UE 906 determines (not shown) that the first MSG2 RAR is not intended for the UE 906. Accordingly, the UE 906 transmits the second MSG3 PUSCH at 1031 using the information (e.g. TAC and uplink grant) indicated in the second MSG2 RAR and monitors the second MSG4 from the network entity at 1031 based on the information indicated in the second MSG2 RAR, e.g. TC-RNTI in the second MSG2 RAR.
Accordingly, the MSG3 transmissions by the UE 904 and the UE 906, at 930 and 1031, respectively, do not collide at the network entity 902 due to the different uplink grants in the two MSG2 transmissions.
According to certain aspects, the UE 904 and the UE 906 monitors an entire response window, even after the UE receives a MSG2 for the preamble and the RA-RNTI associated to the transmitted RACH preamble in MSG1 during the response window. The response window may be configured (e.g., via an RRC parameter, ra-Response Window) or preconfigured.
According to certain aspects, if the network entity 902 does not receive a MSG3, in response to a resource allocation contained in a MSG2 for one of the UEs, the network entity 902 may or may not schedule a MSG3 retransmission.
It should be understood that while
According to certain aspects, the UE 904 and the UE 906 monitors an entire response window for receiving MSGB, even after the UE receives a MSGB for the preamble and the RA-RNTI associated to the transmitted RACH preamble in MSGA during the response window. The response window may be configured (e.g., via an RRC parameter, msgB-Response Window) or preconfigured.
The UE 904 and the UE 906 determine whether the first and second RAR are intended for the UEs, at 926 and 1027, respectively, as described above with respect to
It should be understood that while
Method 1200 begins at 1202 with determining a first TA for transmitting a RACH preamble.
Method 1200 then proceeds to step 1204 with determining a second TA, different than the first TA, for transmitting the RACH preamble.
Method 1200 then proceeds to step 1206 with transmitting the RACH preamble using the second TA.
Method 1200 then proceeds to step 1208 with receiving a RAR message including a TAC.
Method 1200 then proceeds to step 1210 with determining whether the RAR is intended for the UE based on the TAC, the first TA, and the second TA.
Method 1200 then proceeds to step 1212 with transmitting a PUSCH transmission based on a determination that the RAR is intended for the UE.
In one aspect, method 1200 further includes refraining from transmitting a PUSCH based on a determining that the RAR is not intended for the UE.
In one aspect, determining the second TA, at 1204, includes receiving a configuration or preconfiguration for determining the second TA and determining the second TA based on the configuration or preconfiguration. In one aspect, the configuration for determining the second TA comprises a range of offsets and determining the second TA based on the configuration includes selecting an offset from the range of offsets and applying the offset to the first TA to determine the second TA. In one aspect, selecting the offset from the range of offsets comprises randomly selecting the offset from the range of offsets.
In one aspect, the second TA is equal to or smaller than the first TA.
In one aspect, determining whether the RAR is intended for the UE, at 1210, includes determining the RAR is intended for the UE when a first difference is smaller than a threshold. The first difference is a difference between the TAC and a second difference. The second difference is a difference between the first TA and the second TA. Determining whether the RAR is intended for the UE, at 1210, includes determining the RAR is not intended for the UE when the first difference is equal to or greater than the threshold.
In one aspect, method 1200 further includes receiving signaling configuring the threshold at the UE.
In one aspect, method 1200 further includes determining the threshold based on a character associated to the first TA.
In one aspect, method 1200 further includes adjusting the threshold based on a number of random access attempts.
In one aspect, adjusting the threshold based on the number of random access attempts includes adjusting the threshold after determining a configured threshold number of RARs are not intended for the UE.
In one aspect, method 1200 further includes receiving a second RAR, after transmitting the RACH preamble and before transmitting the PUSCH, including a second TAC. In one aspect, the method 1200 further includes determining the second RAR is not intended for the UE based on a third difference between the second TAC and the second difference between the first TA and the second TA.
In one aspect, the RAR includes a RA-RNTI, a RAPID, or both and the second RAR includes the same RA-RNTI, the same RAPID, or both.
In one aspect, transmitting the RACH preamble, at 1206, includes transmitting a RACH message and a PUSCH. In one aspect, receiving the RAR, at 1208, includes receiving a fallback RAR in a RACH message.
In one aspect, method 1200 further includes monitoring an entire configured RAR window, wherein one or multiple RAR is received in the RAR window.
In one aspect, determining the first TA includes determining the first TA based on a location of the UE, ephemeris information, one or more configured common TA parameters, or a combination thereof.
In one aspect, the RACH preamble transmission and the PUSCH transmission includes a NB-IoT EDT or SDT.
In one aspect, the UE performs a RACH procedure with a NTN.
In one aspect, method 1200, or any aspect related to it, may be performed by an apparatus, such as communications device 1400 of
Note that
Method 1300 begins at 1302 with outputting a timing advance (TA) configuration for a first UE and a second UE.
Method 1300 then proceeds to step 1304 with obtaining a first RACH preamble from the first UE using a first TA and a second RACH preamble from the second UE using a second TA. The first RACH preamble and the second RACH preamble comprise an identical RACH sequence.
Method 1300 then proceeds to step 1306 with outputting a RAR message including a TAC.
Method 1300 then proceeds to step 1308 with obtaining a PUSCH transmission from the first UE or the second UE based on the TAC.
In one aspect, the first RACH preamble and the second RACH preamble are obtained at different times.
In one aspect, the TA configuration comprises a range of offsets or a range of TA values.
In one aspect, method 1300 further includes determining the range of offsets or the range of TA values based on a capability of the network entity to decode a RACH preamble.
In one aspect, method 1300 further includes outputting a threshold, wherein the threshold comprises a threshold difference for each of the first UE and the second UE to determine whether the RAR message is intended for the UE. The threshold difference is between a first difference and a second difference. The first difference is a difference between the TAC and the second difference. The second difference is a TA difference. The TA difference is a difference between the first TA and a third TA of the first UE and a difference between the second TA and a fourth TA of the second UE.
In one aspect, method 1300 further includes determining the threshold based on a character associated to the first TA.
In one aspect, method 1300 further includes outputting a second RAR, after obtaining the RACH preamble and before obtaining the PUSCH, including a second TAC, different than the TAC.
In one aspect, the RAR comprises a access radio network temporary identifier (RA-RNTI), a random access preamble identifier (RAPID), or both and the second RAR comprises the same RA-RNTI, the same RAPID, or both.
In one aspect, obtaining the RACH preamble, at 1304, comprises obtaining a RACH message further comprising a PUSCH and outputting the RAR, at 1306, comprises outputting a fallback RAR in a RACH message.
In one aspect, the RACH preamble transmission and the PUSCH transmission comprises a NB-IoT EDT or SDT.
In one aspect, the network entity is a NTN entity or communicates with the NTN entity.
In one aspect, method 1300, or any aspect related to it, may be performed by an apparatus, such as communications device 1500 of
Note that
The communications device 1400 includes a processing system 1402 coupled to a transceiver 1408 (e.g., a transmitter and/or a receiver). The transceiver 1408 is configured to transmit and receive signals for the communications device 1400 via an antenna 1410, such as the various signals as described herein. The processing system 1402 may be configured to perform processing functions for the communications device 1400, including processing signals received and/or to be transmitted by the communications device 1400.
The processing system 1402 includes one or more processors 1420. In various aspects, the one or more processors 1420 may be representative of one or more of receive processor 358, transmit processor 364, TX MIMO processor 366, and/or controller/processor 380, as described with respect to
In the depicted example, computer-readable medium/memory 1430 stores code (e.g., executable instructions) for determining 1431, code for transmitting 1432, code for receiving 1433, code for refraining 1434, code for selecting 1435, code for applying 1436, code for adjusting 1437, and code for monitoring 1438. Processing of the code 1431-1438 may cause the communications device 1400 to perform the method 1200 described with respect to
The one or more processors 1420 include circuitry configured to implement (e.g., execute) the code stored in the computer-readable medium/memory 1430, including circuitry for determining 1421, circuitry for transmitting 1422, circuitry for receiving 1423, circuitry for refraining 1424, circuitry for selecting 1425, circuitry for applying 1426, circuitry for adjusting 1427, and circuitry for monitoring 1428. Processing with circuitry 1421-1428 may cause the communications device 1400 to perform the method 1200 described with respect to
Various components of the communications device 1400 may provide means for performing the method 1200 described with respect to
The communications device 1500 includes a processing system 1502 coupled to a transceiver 1508 (e.g., a transmitter and/or a receiver) and/or a network interface 1512. The transceiver 1508 is configured to transmit and receive signals for the communications device 1500 via an antenna 1510, such as the various signals as described herein. The network interface 1512 is configured to obtain and send signals for the communications device 1500 via communications link(s), such as a backhaul link, midhaul link, and/or fronthaul link as described herein, such as with respect to
The processing system 1502 includes one or more processors 1520. In various aspects, one or more processors 1520 may be representative of one or more of receive processor 338, transmit processor 320, TX MIMO processor 330, and/or controller/processor 340, as described with respect to
In the depicted example, the computer-readable medium/memory 1530 stores code (e.g., executable instructions) for outputting 1531, code for obtaining 1532, and code for determining 1533. Processing of the code 1531-1533 may cause the communications device 1500 to perform the method 1300 described with respect to
The one or more processors 1520 include circuitry configured to implement (e.g., execute) the code stored in the computer-readable medium/memory 1530, including circuitry for outputting 1521, circuitry for obtaining 1522, and circuitry for determining 1523. Processing with circuitry 1521-1523 may cause the communications device 1500 to perform the method 1300 as described with respect to
Various components of the communications device 1500 may provide means for performing the method 1300 as described with respect to
Implementation examples are described in the following numbered clauses:
The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein are not limiting of the scope, applicability, or aspects set forth in the claims. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. For example, changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various actions may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.
The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an ASIC, a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, a system on a chip (SoC), or any other such configuration.
As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).
As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.
The methods disclosed herein comprise one or more actions for achieving the methods. The method actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of actions is specified, the order and/or use of specific actions may be modified without departing from the scope of the claims. Further, the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor.
The following claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims. Within a claim, reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. No claim element is to be construed under the provisions of 35 U.S.C. § 112(f) unless the element is expressly recited using the phrase “means for”. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.
