METHOD FOR A TRANSMISSION/RECEPTION POINT (TRP) SPECIFIC BEAM FAILURE RECOVERY (BFR) FOR A SINGLE DOWNLINK CONTROL INFORMATION (DCI) MODE

Aspects are described for a user equipment (UE) comprising a transceiver configured to enable wireless communication with a first transmission/reception point (TRP) and a second TRP and a processor communicatively coupled to the transceiver. The UE is in a multi-TRP mode. The processor is configured to perform a first beam failure detection (BFD) procedure for the first TRP and a second BFD procedure for the second TRP. The processor is further configured to perform a first beam failure recovery (BFR) procedure for the first TRP responsive to a result of the first BFD procedure and a second BFR for the second TRP responsive to a result of the second BFD procedure. The processor is further configured to receive a configuration message, a BFD configuration, and a BFR configuration. The UE switches to a single-TRP mode upon receiving the configuration message. The processor is further configured to update the first BFD procedure based on the BFD configuration and update the first BFR procedure based on the BFR configuration. Finally, the processor is configured to perform the updated first BFD procedure and the updated first BFR procedure for the first TRP responsive to a result of the updated first BFD procedure.

BACKGROUND

Field

The described aspects generally relate to an enhancement on a beam failure recovery for a single downlink control information (DCI) mode.

SUMMARY

Some aspects of this disclosure relate to apparatuses and methods for implementing a beam failure recovery (BFR) enhancement for a single downlink control information (DCI) mode for 3rd Generation Partnership Project (3GPP) release 15 (Rel-15), release 16 (Rel-16), release 17 (Rel-17), and/or other 3GPP releases that support the BFR. For example, systems and methods are provided for implementing a transmission/reception point (TRP) specific BFR.

Some aspects of this disclosure relate to a user equipment (UE) comprising a transceiver configured to enable wireless communication with a first transmission/reception point (TRP) and a second TRP and a processor communicatively coupled to the transceiver. The processor is configured to perform a first beam failure detection (BFD) procedure for the first TRP and second BFD procedure for the second TRP. The processor is further configured to perform a first beam failure recovery (BFR) procedure for the first TRP responsive to a result of the first BFD procedure and a second BFR procedure for the second TRP responsive to a result of the second BFD procedure. The processor is further configured to receive a configuration message, a BFD configuration, and a BFR configuration. The UE switches from a multi-TRP mode to a single-TRP mode upon receiving the configuration message. The processor is further configured to update the first BFD procedure based on the BFD configuration and update the first BFR procedure based on the BFR configuration. Finally, the processor is configured to perform the updated first BFD procedure and the updated first BFR procedure for the first TRP responsive to a result of the updated first BFD procedure.

Some aspects of this disclosure relate to a method of operating a UE to communicate with a first TRP and a second TRP. The method comprises performing a first BFD procedure for the first TRP and a second BFD for the second TRP. The method further comprises performing a first BFR procedure for the first TRP responsive to a result of the first BFD procedure and a second BFR procedure for the second TRP responsive to a result of the second BFD procedure. The method further comprises receiving a configuration message, a BFD configuration, and a BFR configuration, and switching from a multi-TRP mode to a single-TRP mode upon receiving the configuration message. The method further comprises updating the first BFD procedure based on the BFD configuration and updating the first BFR procedure based on the BFR configuration. Finally, the method comprises performing the updated first BFD procedure and the updated first BFR procedure for the first TRP responsive to a result of the updated first BFD procedure.

Some aspects of this disclosure relate to a base station comprising a transceiver configured to enable communication with a UE and a processor communicatively coupled to the transceiver. The processor is configured to generate a configuration message, a BFD configuration, and a BFR configuration. The processor is further configured to transmit the configuration message, the BFD configuration, and the BFR configuration to the UE.

This Summary is provided merely for purposes of illustrating some aspects to provide an understanding of the subject matter described herein. Accordingly, the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter in this disclosure. Other features, aspects, and advantages of this disclosure will become apparent from the following Detailed Description, Figures, and Claims.

DETAILED DESCRIPTION

Some aspects of this disclosure include apparatuses and methods for implementing a beam failure recovery (BFR) enhancement for a single downlink control information (DCI) mode for 3rd Generation Partnership Project (3GPP) release 15 (Rel-15), release 16 (Rel-16), release 17 (Rel-17), and/or other 3GPP releases. For example, systems and methods are provided for implementing designs for a transmission/reception point (TRP) specific BFR.

According to some aspects, a user equipment (UE) that operates according to Release 15 (Rel-15), Release 16 (Rel-16), and/or Release 17 (Rel-17) and/or New Radio (NR) of 5thgeneration (5G) wireless technology for digital cellular networks as defined by 3GPP, and the UE can support a UE-specific BFR. For example, the UE connects with a first TRP via one or more beams. The one or more beams correspond to one or more control resource sets (CORESETs). The UE performs a beam failure detection (BFD) procedure of the first TRP. For example, the UE monitors and detects conditions of the one or more beams by detecting block error rates (BLERs) of one or more BFD reference signals (RSs) that are quasi co-located (QCLed) with the one or more CORESETs. In some aspects, the BFD RSs include synchronization signal block (SSB) signals and/or channel state information reference signals (CSI-RS). If the BLERs corresponding to a beam fall below a threshold, the UE detects a beam failure occurrence. In some aspects, the UE determines that the beam fails after detecting a predetermined number of beam fail occurrences of the beam. In some aspects, the UE declares a beam failure event after determines that all of the one or more beams fail. In such a case, the UE identifies a new candidate beam whose layer one reference signal received power (L1-RSRP) is above a power threshold. In some aspects, the UE performs a BFR procedure of the first TRP. For example, upon detecting the beam failure event, the UE reports the beam failure event and the new candidate beam to a base station via a beam failure recovery request (BFRQ). In some aspects, the base station is the first TRP. The UE may transmit the BFRQ via a MAC control element (MAC CE) or via a contention-based random access (CBRA). The base station then sends a beam failure recovery response (BFRR) to the UE to reconnect with the first TRP based on the new candidate beam. In some aspects, the base station transmits the BFRR via a transmission scheduled via a physical downlink control channel (PDCCH) to the UE. The PDCCH uses a same hybrid automatic repeat request (HARM) process as a physical uplink shared channel (PUSCH) corresponding to the MAC CE. In some aspects, if the base station receives the BFRQ via the CBRA from the UE, the base station transmits the BFRR via the fourth message (Msg4) to the UE. In other words, the base station transmits the BFRR via a PDCCH that is associated with a cell-radio network temporary identifier (C-RNTI) corresponding to the UE.

According to some aspects, the UE also connects with a second TRP. In some aspects, the UE operates in a single-DCI mode, where the base station schedules physical downlink shared channels (PDSCHs) of both the first and second TRPs via a single DCI. The single-DCI mode is also referred to as a multi-TRP mode. In some aspects, the UE operates in a multi-DCI mode, where the base station schedules a PDSCH of the first TRP via a first DCI and schedules a PDSCH of the second TRP via a second DCI. In some aspects, the UE can perform a TRP-specific BFR for the first and the second TRPs. For example, the UE performs separate BFD and BFR procedures for the first and the second TRPs.

In some aspects, the UE can switch from the multi-TRP mode to a single-TRP mode. For example, the UE determines to drop the second TRP by refraining from communicating user data to and from the second TRP. The UE may determine to drop the second TRP based on a data traffic condition, such as a packet arrival rate. The UE may also determine to drop the second TRP for power efficiency or other reasons. In some aspects, the base station instructs the UE to switch between the multi-TRP mode and the single-TRP mode. For example, the base station transmits a MAC CE to the UE to instruct the UE which mode the UE should be in: the multi-TRP mode or the single-TRP mode. In some aspects, the MAC CE transmitted by the base station includes a transmission configuration indicator (TCI). The UE may determine that a code-point of the TCI maps to two TCI states and switch to the multi-TRP mode. On the other hand, the UE may determine that the code-point of the TCI maps to one TCI state and switch to the single-TRP mode.

FIG.1illustrates an example system100implementing designs of a TRP-specific BFR, according to some aspects of the disclosure. Example system100is provided for the purpose of illustration only and does not limit the disclosed aspects. System100may include, but is not limited to, a UE102, a TRP104, a TRP106, and a TRP108. The UE102may be implemented as electronic devices configured to operate based on a wide variety of wireless communication techniques. These techniques may include, but are not limited to, techniques based on 3rd Generation Partnership Project (3GPP) standards. For example, the UE102may include electronic devices configured to operate using one or more 3GPP releases, such as Release 15 (Rel-15), Release 16 (Rel-16), Release 17 (Rel-17), or other 3GPP releases. The UE102may include, but is not limited to, wireless communication devices, smartphones, laptops, desktops, tablets, personal assistants, monitors, televisions, wearable devices, Internet of Things (IoT) devices, vehicle communication devices, and the like. The TRPs104,106, and108may include one or more nodes configured to operate based on a wide variety of wireless communication techniques such as, but not limited to, techniques based on the 3GPP standards. For example, the TRPs104,106, and108may include nodes configured to operate using Rel-15, Rel-16, Rel-17, or other 3GPP releases. The TRPs104,106, and108may include, but not limited to, base stations, NodeBs, eNodeBs, gNBs, new radio base stations (NR BSs), access points (APs), remote radio heads, relay stations, and others.

In some aspects, the UE102connects with the TRP104via a communication link110and the TRP106via a communication link112. Each of the communication links110and112includes one or more beams. As discussed above, the UE102is in a multi-TRP mode. In some aspects, the UE102can perform a TRP-specific BFR, which includes a BFD procedure and a BFR procedure for each of connected TRPs, e.g., the TRP104and the TRP106. For example, the UE102performs a BFD procedure of the TRP104by monitoring the one or more beams of the communication link110. The UE102declares a beam failure event of the TRP104when the UE102detects that the one or more beams of the communication link110fail. After the UE102declares the beam failure event of the TRP104, the UE102performs a BFR procedure of the TRP104. For example, the UE102generates a BFRQ of the TRP104identifying one or more new candidate beams and transmits the BFRQ of the TRP104to a base station. In some aspects, the base station is the TRP108. The UE102transmits the BFRQ of the TRP104to the TRP108via a communication link114. In other aspects, the base station is the TRP104or the TRP106. For example, the UE102transmits the BFRQ of the TRP104to the TRP106via the communication link112. The UE102can also transmit the BFRQ of the TRP104to the TRP104via channels other than the communication link110after declaring the beam failure event of the TRP104. For example, the UE102can transmit the BFRQ of the TRP104to the TRP104via a contention-based random access procedure, such as a physical random access channel (PRACH). In some aspects, upon receiving the BFRQ of the TRP104, the base station generates a BFRR of the TRP104and transmits the BFRR of the TRP104to the UE102. The BFRR of the TRP104confirms the one or more new candidate beams. The BFRR of the TRP104may also deny the one or more new candidate beams and identify a different set of one or more new candidate beams. After receiving the BFRR of the TRP104, the UE102completes the BFR procedure of the TRP104by recovering the communication link110via the one or more new candidate beams. In some aspects, the UE102repeats the transmission of the BFRQ of the TRP104to the base station if the UE102does not receive the BFRR of the TRP104within a predetermined retransmission time period.

In some aspects, the UE102performs a BFD procedure and a BFR procedure of the TRP106similarly as described above regarding the TRP104. As discussed above, the UE102performs the TRP-specific BFR. Therefore, the UE102performs the BFD and BFR procedures of the TRP104regardless of conditions of the TRP106. For example, the UE102can declare the beam failure event of the TRP104even when the UE102still communicates with the TRP106via the communication link112. In other words, the TRP-specific BFR ensures that the UE102can communicate with both the TRP104and the TRP106. In some aspects, when both communication links110and112fail, the UE102generates the BFRQ of the TRP104and a BFRQ of the TRP106and transmits both of the BFRQs to the base station. The base station, upon receiving the BFRQs, generates and transmits the BFRR of the TRP104and a BFRR of the TRP106to the UE102to instruct recovery of the communication links110and112. The UE102performing the TRP-specific BFR is also referred to as in a TRP-specific mode.

In some aspects, the UE102can perform a UE-specific BFR or be in a UE-specific mode. In such as case, the UE102performs a BFD procedure for both the TRP104and the TRP106. For example, UE102monitors the one or more beams of the communication link110and the one or more beams of the communication link112. The UE102declares a beam failure event of the UE102when the one or more beams of the communication link110and the one or more beams of the communication link112fail. In other words, the UE102would not declare the beam failure event of the UE102if the UE102can still communicate with the TRP104or the TRP106. For example, when the one or more beams of the communication link110fail but the one or more beams of the communication link112do not, the UE102would not declare the beam failure event of the UE102. In some aspects, after the UE102declares the beam failure event of the UE102, the UE102performs a BFR procedure of the UE102. For example, the UE102generates a BFRQ of the UE102and then transmits the BFRQ of the UE102to the base station. In some aspects, the BFRQ of the UE102indicates one or more new candidate beams of the UE102, which can be used to recover the communication link110, the communication link112, or both. The base station, upon receiving the BFRQ of the UE102, generates and transmits a BFRR of the UE102to the UE102. The BFRR of the UE102may confirm, deny, or indicate replacement of the one or more new candidate beams of the UE102as similarly discussed above. The BFRR of the UE102may also partially confirm the one or more new candidate beams of the UE102. For example, the BFRQ of the UE102indicates a first beam and a second beam. The UE102can recover the communication link110using the first beam and recover the communication link112using the second beam. The BFRR of the UE102can confirm the first beam but deny the second beam. In other words, based on the BFRR of the UE102, the UE102can recover the communication link110, but not the communication link112. In some aspects, the BFFR of the UE102confirms the second beam but denies the first beam, so that the UE102recovers the communication link112, but not the communication link110.

According to some aspects, the UE102switches from the multi-TRP mode to a single-TRP mode. For example, the UE102drops the TRP104by refraining from communicating user data to and from the TRP104. In some aspects, the UE102updates the BFD and BFR procedures for the TRPs104and106. For example, the UE102updates the BFD procedure of the TRP104to continue monitoring the communication link112but stop generating the BFRQ of the TRP104. The UE102can also update the BFR to stop transmitting additional BFRQ if no BFRR is received within the predetermined retransmission time period. Details of updating the BFD and BFR procedures are disclosed below inFIG.3. In some aspects, the UE102saves energy by updating the BFD and BFR procedures.

According to some aspects, the UE102can only be in one of the TRP-specific mode and the UE-specific mode at a given time for a component carrier. In other aspects, the UE102can be in both the TRP-specific mode and the UE-specific mode at the same time. In other words, the TRP-specific BFR and the UE-specific BFR may coexist. In some aspects, the UE102uses a set of BFD RSs for BFD procedures in both the TRP-specific mode and the UE-specific mode. In such a case, the UE102performs a constant BFD procedure based on the set of BFD RSs in both the multi-TRP mode and the single-TRP mode. For example, after the UE102switches to the single-TRP mode from the multi-TRP mode, the UE102continues the constant BFD procedure using the set of BFD RSs. In some aspects, the UE102detects a beam failure event based on the constant BFD procedure and determines a status of the beam failure event. For example, the communication link110includes a first and a second beams and the communication link112includes a third and a fourth beams. If the beam failure event indicates that the first and the second beams fail, the UE102determines that the status of the beam fail event to be a TRP-specific beam failure event of the TRP104. In such as case, the UE102ignores the beam failure event if the UE102is in the single-TRP mode after dropping the TRP104. On the other hand, the UE102performs a TRP-specific BFR of the TRP104if the UE102is in the multi-TRP mode. For example, the UE102generates and transmits the BFRQ of the TRP104to the base station. In some aspects, the beam failure event indicates that the first, the second, the third, and the fourth beams fail. The UE102determines that the status of the beam failure event to be a UE-specific beam failure event. In such a case, the UE102performs the BFR procedure of the UE102in the UE-specific mode or the BFR procedure of the TRP104and the BFR procedure of the TRP106in the TRP-specific mode. In some aspects, the base station instructs the UE102to perform the BFR procedure of the UE102or to perform the BFR procedure of the TRP104and the BFR procedure of the TRP106. For example, the base station instructs the UE102by transmitting the MAC CE to the UE102.

In some aspects, the UE102uses a first set of BFD RSs for the BFD procedures in the TRP-specific mode and a second set of BFD RSs for the BFD procedures in the UE-specific mode. In such a case, the UE102may detect a plurality of beam failure events. For example, the UE102may detect the UE-specific beam failure event of the UE102and the TRP-specific beam failure event of the TRP104. The UE102may trigger a BFRQ based on priorities. For example, the UE-specific beam failure event of UE102has a high priority; the TRP-specific beam failure event of the TRP104has a medium priority; and the TRP-specific beam failure event of the TRP106has a low priority. Therefore, the UE102triggers the BFRQ procedure of the UE102in this case. In some aspects, the UE102triggers a plurality of BFRQs based on a capability of the UE102.

FIG.2illustrates a block diagram of an example system200of an electronic device implementing the TRP specific BFR, according to some aspects of the disclosure. The system200may be any of the electronic devices (e.g., the UE102and the TRPs104,106, and108) of the system100. The system200includes a processor210, one or more transceivers220, a communication infrastructure240, a memory250, an operating system252, an application254, and one or more antennas260. Illustrated systems are provided as exemplary parts of system200, and system200may include other circuit(s) and subsystem(s). Also, although the systems of system200are illustrated as separate components, the aspects of this disclosure may include any combination of these, e.g., less, or more components.

The memory250may include random access memory (RAM) and/or cache, and may include control logic (e.g., computer software) and/or data. The memory250may include other storage devices or memory. According to some examples, the operating system252may be stored in the memory250. The operating system252may manage transfer of data from the memory250and/or the one or more applications254to the processor210and/or the one or more transceivers220. In some examples, the operating system252maintains one or more network protocol stacks (e.g., Internet protocol stack, cellular protocol stack, and the like) that may include a number of logical layers. At corresponding layers of the protocol stack, the operating system252includes control mechanisms and data structures to perform the functions associated with that layer.

According to some examples, the application254may be stored in the memory250. The application254may include applications (e.g., user applications) used by wireless system200and/or a user of wireless system200. The applications in the application254may include applications such as, but not limited to, Siri™, FaceTime™, radio streaming, video streaming, remote control, and/or other user applications.

The system200may also include the communication infrastructure240. The communication infrastructure240provides communication between, for example, the processor210, the one or more transceivers220, and the memory250. In some implementations, the communication infrastructure240may be a bus.

The processor210, alone, or together with instructions stored in the memory250performs operations enabling system200of the system100to implement mechanisms for the BFR enhancement for a single DCI mode, as described herein. Alternatively, or additionally, the processor210can be “hard coded” to implement mechanisms for the BFR enhancement for a single DCI mode, as described herein The one or more transceivers220transmit and receive communications signals support mechanisms for the BFR enhancement for a single DCI mode. Additionally, the one or more transceivers220transmit and receive communications signals that support mechanisms for measuring communication link(s), generating and transmitting system information, and receiving the system information. According to some aspects, the one or more transceivers220may be coupled to antenna260to wirelessly transmit and receive the communication signals. Antenna260may include one or more antennas that may be the same or different types. The one or more transceivers220allow system200to communicate with other devices that may be wired and/or wireless. In some examples, the one or more transceivers220may include processors, controllers, radios, sockets, plugs, buffers, and like circuits/devices used for connecting to and communication on networks. According to some examples, the one or more transceivers220include one or more circuits to connect to and communicate on wired and/or wireless networks.

According to some aspects of this disclosure, the one or more transceivers220may include a cellular subsystem, a WLAN subsystem, and/or a Bluetooth™ subsystem, each including its own radio transceiver and protocol(s) as will be understood by those skilled in the arts based on the discussion provided herein. In some implementations, the one or more transceivers220may include more or fewer systems for communicating with other devices.

In some examples, the one or more the transceivers220may include one or more circuits (including a WLAN transceiver) to enable connection(s) and communication over WLAN networks such as, but not limited to, networks based on standards described in IEEE 802.11.

Additionally, or alternatively, the one or more the transceivers220may include one or more circuits (including a Bluetooth™ transceiver) to enable connection(s) and communication based on, for example, Bluetooth™ protocol, the Bluetooth™ Low Energy protocol, or the Bluetooth™ Low Energy Long Range protocol. For example, the transceiver220may include a Bluetooth™ transceiver.

Additionally, the one or more the transceivers220may include one or more circuits (including a cellular transceiver) for connecting to and communicating on cellular networks. The cellular networks may include, but are not limited to, 3G/4G/5G networks such as Universal Mobile Telecommunications System (UMTS), Long-Term Evolution (LTE), and the like. For example, the one or more transceivers220may be configured to operate according to one or more of Rel-15, Rel-16, Rel-17, or other releases of 3GPP standard.

As discussed in more detail below with respect toFIGS.3-9, processor210may implement different mechanisms for the TRP specific BFR as discussed with respect to the system100ofFIG.1.

FIG.3illustrates an example method300for BFD and BFR procedures when switching between a multi-TRP mode and a single-TRP mode. As a convenience and not a limitation,FIG.3may be described with regard to elements ofFIGS.1,2, and9. Method300may represent the operation of electronic devices (for example, the UE102and the TRPs104,106, and108ofFIG.1) implementing the BFD and BFR procedures. The example method300may also be performed by system200ofFIG.2, controlled or implemented by processor210, and/or computer system900ofFIG.9. But method300is not limited to the specific aspects depicted in those figures and other systems may be used to perform the method, as will be understood by those skilled in the art. It is to be appreciated that not all operations may be needed, and the operations may not be performed in the same order as shown inFIG.3.

At302, the UE102connects with the TRP104and the TRP106. Therefore, the UE102is in the multi-TRP mode. In some aspects, the UE102enters the multi-TRP mode based on requests from applications of the UE102, such as the application254of theFIG.2. In some aspects, the UE102enters the multiple-TRP mode based on instructions from a base station, wherein the base station can be the TRP104, the TRP106, or the TRP108.

At304, the UE102performs a BFD procedure of the TRP104and a BFD procedure of the TRP106. As discussed above, the UE102monitors the communication links110and112. For example, the UE102monitors the one or more beams of the communication links110and the one or more beams of the communication112.

At306, the UE102determines and declares a beam failure event. For example, the UE102declares a beam failure event of the TRP104if the one or more beams of the communication link110fail. In such a case, the control moves to308. Similarly, a beam failure event can be declared for TRP106.

At308, the UE102performs a BFR procedure of the TRP104. For example, the UE102generates a BFRQ of the TRP104and transmits the BFRQ of the TRP104to the base station. In some aspects, the BFRQ of the TRP104identifies one or more new candidate beams for the communication link110. The UE102then receives a BFRR of the TRP104from the base station. The BFRR of the TRP104identifies one or more confirmed candidate beams. In some aspects, the one or more confirmed candidate beams are different from the one or more new candidate beams. The UE102, upon receiving the BFRR of the TRP104, uses the one or more confirmed candidate beams to recover the communication link110. The control then returns to304and the UE102continues to monitor the communication links110and112. Similarly, a BFR procedure can be implemented for TRP106.

Referring back to306, if the UE102does not declare a beam failure event, the control moves to310.

At310, the UE102determines whether to switch to the single-TRP mode. In some aspects, the UE102determines to switch based on instructions from the base station. For example, the base station transmits a configuration message via a MAC CE to the UE102. In some aspects, the configuration message is in a form of a TCI. For example, the UE102may determine that a code-point of the TCI maps to two TCI states and switch to the multi-TRP mode. On the other hand, the UE102may determine that the code-point of the TCI maps to one TCI state and switch to the single-TRP mode. In other aspects, the MAC CE includes a switch indicator. For example, the switch indicator is a binary bit that indicates the single-TRP mode or the multi-TRP mode. If the UE102determines not to switch to the single-TRP mode, the control moves back to302. On the other hand, if the UE102determines to switch to the single-TRP mode, the control moves to312.

At312, the UE102drops one TRP to switch to the single-TRP mode, such as the TRP104, by refraining from communicating user data to and from the TRP. In some aspects, the UE102continues to receive RSs from the TRP104after dropping the TRP104. The UE102use the RSs received from the TRP104to monitor the one or more beams of the communication link110. In other words, the UE102monitors the communication link110for future use after dropping the TRP104. In some aspects, the UE102refrains from communicating any data to and from the TRP104including the RSs. In such a case, the UE102monitors the one or more beams by receiving alternative RSs from a TRP other than the TRP104, wherein the alternative RSs QCLed with the one or more beams of the communication link110.

At314, the UE102updates BFD and BFR procedures. In some aspects, the UE102updates the BFD procedure of the TRP104and the TRP106to one of five BFD options disclosed below.

BFD option 1: the UE102stops the BFD procedure of the TRP104and resets a BFD counter of the TRP104. In other words, the UE102stops monitoring the communication link110when the TRP104is dropped. In some aspects, the UE102declares a bean failure event based on the BFD counter of the TRP104. For example, the BFD counter of the TRP104includes a number of failures for each of the one or more beams of the communication link110. The number of failures of a beam increases by 1 when the UE102detects a failure of the beam. When the number of failures of the beam reaches a predetermined failure threshold, the UE102determines that the beam fails. As discussed above, the UE102declares the beam failure event of the TRP104when all of the one or more beams of the communication link110fail. In such a case, each of the one or more beams has reached the predetermined failure threshold. Therefore, the UE102erases records of the one or more beams of the communication link110when dropping the TRP104.

BFD option 2: the UE102stops the BFD procedure of the TRP104but keeps the BFD counter of the TRP104. Therefore, the UE102stops monitoring the communication link110. However, the UE102can use the BFD counter of the TRP104when the UE102switches back to the multi-TRP mode.

BFD option 3: the UE102continues the BFD procedure of the TRP104but pauses the BFRQ of the TRP104. For example, the UE102continues to monitor the communication link110and may declare the beam failure event of the TRP104if the one or more beams of the communication link110fail. However, the UE102does not generate or transmit the BFRQ of the TRP104. The UE102generates and transmits the BFRQ of the TRP104when switching back to the multi-TRP mode. In other words, the UE102holds the BFRQ procedure of the TRP104until the UE102switches back to the multi-TRP mode.

BFD option 4: the UE102continues the BFD procedure of the TRP104with no restriction on the BFRQ procedure of the TRP104. For example, the UE102continues to monitor the communication link110and triggers the BFRQ of the TRP104to initiate the BFR procedure of the TRP104when needed.

BFD option 5: the UE102performs the BFD option 3 or the BFD option 4 disclosed above within a first time period after switching to the single-TRP mode. In some aspects, the first time period is a transition period. The UE102monitors the communication link110in case that the UE102switches back to the multi-TRP mode within the transition period. When the first time period expires, the UE102performs the BFD option 2 above within a second time period. When the second time period expires, the UE102performs the BFD option 1 above. In some aspects, the UE102switches back to the multi-TRP mode before the first time period expires. In such a case, the UE102can update the first time period to be a remaining time of the first time period. Similarly, the UE102can update the second time period to be a remaining time of the second time period if the UE102switches back to the multi-TRP mode before the second time period expires.

In some aspects, the UE102updates the BFD procedure of the TRP104as instructed by the base station. For example, the base station transmits a BFD configuration to the UE102. The BFD configuration indicates a selected BFD option. The BFD configuration also includes the first and the second time periods. In some aspects, the base station transmits the BFD configuration via higher layer signaling. For example, the base station transmits the BFD configuration via an RRC signaling or a MAC CE. In some aspects, the MAC CE includes a field for TCI activation to indicate the selected BFD option. The UE102can also determine the selected BFD option based on whether the TCI states of CORESETs change after switching to the single-TRP mode. For example, a CORESET corresponds to the TRP104. After the UE102switches to the single-TRP mode by dropping the TRP104, if a TCI state of the CORESET changes, the UE102selects the BFD option 1. If the TCI state of the CORESET does not change, the UE102selects the BFD option 4. In some aspects, the base station can transmit the BFD configuration via DCI that indicates the selected BFD option. For example, the DCI can be format 1_1 DCI or format 1_2 DCI that includes a field to indicate the selected BFD option.

In some aspects, the UE102updates the BFD procedure of the TRP106to be the same as the BFD procedure of the TRP104. In other aspects, the UE102updates the BFD procedure of the TRP106similarly as the BFD procedure of the TRP104as disclosed above. For example, the BFD configuration includes the selected BFD of the TRP104and a selected BFD option of the TRP106. In some aspects, the BFD configuration can set the first and the second time periods, disclosed in the BFD option 5 above, of the TRP106to be different from those of the TRP104. In some aspects, the UE102can report to the base station a maximum duration of the first and the second time periods it supports.

In some aspects, the UE102updates the BFR procedure of the TRP104to one of four BFR options disclosed below.

BFR option 1: the UE102stops the BFR procedure of the TRP104. If the UE102has initiated the BFR procedure of the TRP104before switching to the single-TRP mode, the UE102terminates the BFR procedure of the TRP104and considers the BFR procedure of the TRP104complete. For example, the UE102has transmitted the BFRQ of the TRP104to the base station before switching to the single-TRP mode, the UE102ignores the BFRR of the TRP104received from the base station.

BFR option 2: the UE102partially stops the BFR procedure of the TRP104. For example, if the UE102has transmitted the BFRQ of the TRP104to the base station before switching to the single-TRP mode, the UE102processes the BFRR of the TRP104received from the base station. However, the UE102does not transmit any additional BFRQs of the TRP104before switching back to the multi-TRP mode. For example, the UE102does not retransmit the BFRQ of the TRP104if the UE102does not receive the BFRR of the TRP104from the base station within a predetermined retransmission time period.

BFR option 3: the UE102continues the BFR procedure of the TRP104. For example, the UE102transmits the BFRQ of the TRP104to the base station after the UE102declares the beam failure event of the TRP104. The UE102retransmits the BFRQ of the TRP104if the UE102does not receive the BFRR of the TRP104from the base station within the predetermined retransmission time period.

BFR option 4: the UE102performs the BFR option 2 or the BFR option 3 disclosed above within a third time period after switching to the single-TRP mode. When the third time period expires, the UE102performs the BFR option 1 disclosed above.

In some aspects, the UE102updates the BFR procedure of the TRP104as instructed by the base station. For example, the base station transmits a BFR configuration to the UE102. The BFR configuration indicates a selected BFR option. In some aspects, the BFR configuration also indicates, when selecting the BFR option 4, whether to perform the BFR option 2 or the BFR option 3 within the third time period. The BFR configuration also includes the third time period. In some aspects, the base station transmits the BFR configuration via the higher layer signaling. For example, the base station transmits the BFR configuration via the RRC signaling or the MAC CE. In some aspects, the MAC CE includes a field for TCI activation to indicate the selected BFR option. The UE102can also determine the selected BFR option based on whether the TCI states of CORESETs change after switching to the single-TRP mode. For example, a CORESET corresponds to the TRP104. After the UE102switches to the single-TRP mode by dropping the TRP104, if a TCI state of the CORESET changes, the UE102selects the BFR option 1. If the TCI state of the CORESET does not change, the UE102selects the BFR option 3. In some aspects, the base station can transmit the BFR configuration via DCI that indicates the selected BFR option. For example, the DCI can be format 1_1 DCI or format 1_2 DCI that includes a field to indicate the selected BFR option.

In some aspects, the UE102updates the BFR procedure of the TRP106to be the same as the BFR procedure of the TRP104. In other aspects, the UE102updates the BFR procedure of the TRP106similarly as the BFR procedure of the TRP104disclosed above. For example, the BFR configuration includes the selected BFR of the TRP104and a selected BFR option of the TRP106. In some aspects, the BFR configuration can set the third time period, disclosed in the BFR option 4 above, of the TRP106to be different from that of the TRP104. In some aspects, the UE102can report to the base station a maximum duration of the third time period it supports.

At316, the UE102performs the updated BFD procedure of the TRP104and the updated BFD procedure of the TRP106. The control may move to322directed based on the selected BFD option. For example, if the updated BFD procedures of the TRP104and the updated BFD procedure of the TRP106correspond to the BFD option 1 or the BFD option 2, the control moves to322directly because the UE102would not declare a beam failure event in this case. Otherwise, the control moves to318.

At318, the UE102determines whether there is a beam failure event based on the updated BFD procedures of the TRP104and the updated BFD procedure of the TRP106. If the UE102declares a beam failure event of the TRP104or the TRP106, the control moves to320. Otherwise, the control moves to322.

At320, the UE102performs the updated BFR procedures of the TRP104or the TRP106. For example, if the UE102declares the beam failure event of the TRP104at318, the UE102performs the updated BFR procedure of the TRP104to recover the communication link110. The control then moves back to316.

At322, the UE102determines whether to switch back to the multi-TRP mode. Similar to310, the UE102determines to switch based on instructions from the base station. If the UE102determines to switch, the control moves to302. Otherwise, the control moves to316.

FIG.4illustrates an example method for an updated BFD procedure. As a convenience and not a limitation,FIG.4may be described with regard to elements ofFIGS.1,2, and9. Method400may represent the operation of electronic devices (for example, the UE102and the TRPs104,106, and108ofFIG.1) implementing the BFD procedure. The example method400may also be performed by system200ofFIG.2, controlled or implemented by processor210, and/or computer system900ofFIG.9. But method400is not limited to the specific aspects depicted in those figures and other systems may be used to perform the method, as will be understood by those skilled in the art. It is to be appreciated that not all operations may be needed, and the operations may not be performed in the same order as shown inFIG.4. In some aspects, the method400describes details of the BFD option 5 of314inFIG.3.

At402, the UE102switches to the single-TRP mode by dropping one TRP, such as the TRP104. In some aspects, the UE102switches to the single-TRP mode based on instructions received from the base station. For example, the base station transmits the MAC CE to the UE102to instruct the UE102to switch to the single-TRP mode. The UE102continues to monitor the one or more beams of the communication link110.

At404, the UE102stops a BFD procedure, such as the BFD procedure of the TRP104. In some aspects, the UE102continues to monitor the one or more beams of the communication link110during a first time period408, which is also referred to as a BFD transitional period. In some aspects, a length of the first time period408is predetermined. In other aspects, the base station can configure the length of the first time period408by transmitting a BFD configuration to the UE102. The UE102may also adjust the length of the first time period408based on requests received from applications of the UE102, such as the application254of theFIG.2.

At406, the UE102resets a BFD counter of the TRP104after a second time period410. In some aspects, a length of the second time period410is predetermined. In other aspects, the base station can configure the length of the second time period410by transmitting a BFD configuration to the UE102. The UE102may also adjust the length of the second time period410based on requests received from applications of the UE102, such as the application254of theFIG.2.

At412, the UE102switches back to the multi-TRP mode. At414, the UE102resumes the BFD procedure of the TRP104. In some aspects,412co-locates with414. In other words, the UE102resumes the BFD procedure of the TRP104when switching back to the multi-TRP mode. In some aspects,412can be triggered any time after402. For example,412can be triggered after402and before404. In such a case, the UE102does not stop the BFD procedure of the TRP104because the UE102would be in the BFD transitional period408before switching back to the multi-TRP mode. Furthermore,404and406would not be triggered.412can also be triggered after404and before406. In such a case,406would not be triggered. In other words, the UE102would not rest the BFD counter. In such a case,414can use the BFD counter that includes information before402. For example, the UE102determines that a beam fails if the UE102detects that a BLER corresponding to the beam falls below a threshold 10 times. The UE102detects that the BLER corresponding to the beam falls below the threshold 9 times before402. In such as case, after switching back to the multi-TRP mode, the UE102would determine that the beam fails if the UE102detects that the BLER corresponding to the beam falls below the threshold once.

FIG.5illustrates an example method for an updated BFR procedure. As a convenience and not a limitation,FIG.5may be described with regard to elements ofFIGS.1,2, and9. Method500may represent the operation of electronic devices (for example, the UE102and the TRPs104,106, and108ofFIG.1) implementing the BFD procedure. The example method500may also be performed by system200ofFIG.2, controlled or implemented by processor210, and/or computer system900ofFIG.9. But method500is not limited to the specific aspects depicted in those figures and other systems may be used to perform the method, as will be understood by those skilled in the art. It is to be appreciated that not all operations may be needed, and the operations may not be performed in the same order as shown inFIG.5. In some aspects, the method500describes details of the BFR option 4 of314inFIG.3.

At502, the UE102switches to the single-TRP mode by dropping one TRP, such as the TRP104. In some aspects, the UE102switches to the single-TRP mode based on instructions received from the base station. For example, the base station transmits the MAC CE to the UE102to instruct the UE102to switch to the single-TRP mode. The UE102continues to monitor the one or more beams of the communication link110.

At504, the UE102stops a BFD procedure, such as the BFD procedure of the TRP104. In some aspects, the UE102continues to perform the BFR procedure of the TRP104during a third time period506, which is also referred to as a BFR transitional period. In some aspects, a length of the third time period506is predetermined. In other aspects, the base station can configure the length of the third time period506by transmitting a BFR configuration to the UE102. The UE102may also adjust the length of the third time period506based on requests received from the applications of the UE102, such as the application254of theFIG.2. In some aspects, the UE102initiates the BFR procedure of the TRP104before504, the UE102terminates the BFR procedure of the TRP104at504. For example, before504, the UE102transmits a BFRQ of the TRP104to the base station but does not receive a BFRR of the TRP104from the base station before504. The UE102terminates the BFR procedure of the TRP104and disregards the BFRR of the TRP104received after504.

At510, the UE102switches back to the multi-TRP mode. At512, the UE102resumes the BFR procedure of the TRP104. In some aspects,510co-locates with512. In other words, the UE102resumes the BFR procedure of the TRP104when switching back to the multi-TRP mode. In some aspects,510can be triggered any time after502. For example,510can be triggered after502and before504. In such a case, the UE102continues the BFR procedure of the TRP104if it is initiated before510. For example, before510, the UE102initiates the BFR procedure of the TRP104by transmitting the BFRQ of the TRP104to the base station, but does not receive the BFRR of the TRP104. The UE102waits until a predetermined retransmission time period expires to retransmit the BFRQ of the TRP104.

FIG.6illustrates an example method for coexistence of UE-specific BFR and TRP-specific BFR for a beam failure event. As a convenience and not a limitation,FIG.6may be described with regard to elements ofFIGS.1,2, and9. Method600may represent the operation of electronic devices (for example, the UE102and the TRPs104,106, and108ofFIG.1) implementing the BFD procedure. The example method600may also be performed by system200ofFIG.2, controlled or implemented by processor210, and/or computer system900ofFIG.9. But method600is not limited to the specific aspects depicted in those figures and other systems may be used to perform the method, as will be understood by those skilled in the art. It is to be appreciated that not all operations may be needed, and the operations may not be performed in the same order as shown inFIG.6.

At602, the UE102detects a beam failure event. In some aspects, the UE102performs a UE-specific BFD procedure and a TRP-specific BFD procedure because the UE102is in both the TRP-specific mode and the UE-specific mode. Therefore, the UE102detects the beam failure event based on either the UE-specific BFD procedure or the TRP-specific BFD procedure.

At604, the UE102determines a status of the beam failure event. In some aspects, the UE102determines that the beam failure event is a TRP-specific beam failure event if the beam failure event indicates that one or more beams of a TRP fail, e.g., the one or more beams of the communication link110. In such a case, the control moves to606. The UE102determines that the beam failure event is a UE-specific beam failure event if the beam failure event indicates that all beams corresponding to the UE102fail. In such a case, the control moves to612.

At606, the UE102determines whether the UE102is in the single-TRP mode or the multi-TRP mode. In some aspects, upon determining the single-TRP mode, the UE102also determines whether the UE102is in the BFD transition period. If the UE102is in the single-TRP mode, the control moves to608. Otherwise, the control moves to610.

At608, the UE102ignores the beam failure event and continues a BFD procedure, such as the BFD procedure of the TRP104. For example, the TRP104is dropped and the beam failure event indicates that the one or more beams of the communication link110fail. In such a case, the UE102continues the BFD procedure of the TRP104. In some aspects, the UE102resets the BFD counter of the TRP104. In some aspects, the UE102ignores the beam failure event and stops the BFD procedure if the UE102detects the beam failure event after the BFD transition period.

At610, the UE102performs a TRP-specific BFR corresponding to the beam failure event. For example, the beam failure event corresponds to the TRP104. The UE102performs the BFR procedure of the TRP104to recover the communication link110.

At612, the UE determines whether the UE102is in the single-TRP mode or the multi-TRP mode similarly as disclosed in606. The control moves to614if the UE102is in the single-TRP mode. Otherwise, the control moves to616. In some aspects, the UE102determines to perform a UE-specific BFR or a TRP-specific BFR based on instructions from the base station. For example, the base station transmits a configuration message to the UE102via an RRC signaling, a MAC CE, or DCI. If the configuration message indicates the UE102to select the UE-specific BFR, the control moves to614. If the configuration message indicates the UE102to select the TRP-specific BFR, the control moves to616.

At614, the UE102performs a UE-specific BFR. As disclosed above, the UE-specific BFR recovers at least one beam of the UE102. For example, the TRP104is dropped. The UE102may recover a beam of the communication link112to recover the communication link112.

At616, the UE102performs the TRP-specific BFR. For example, the UE102generates and transmits both the BFRQ of the TRP104and the BFRQ of the TRP106. Upon receiving the BFRRs of the TRP104and the TRP106, the UE102recovers the communication links110and112. In some aspects, the UE102performs the TRP-specific BFR based on instructions of the baes station. For example, the UE102generates a multiple BFR capability report and transmits the multiple BFR capability report to the base station. The multiple BFR capability report indicates that the UE102is capable of generating and transmitting more than one BFRQs. The base station then transmits a multiple BFR configuration to the UE102to allow the UE102to generate and transmit more than one BFRQs. In some aspects, the UE102can generate and transmit more than one BFRQs after transmitting the multiple BFR capability report to the base station without receiving the multiple BFR configuration from the base station.

FIG.7illustrates an example method for the coexistence of the UE-specific BFR and the TRP-specific BFR for a plurality of beam failure events. As a convenience and not a limitation,FIG.7may be described with regard to elements ofFIGS.1,2, and9. Method700may represent the operation of electronic devices (for example, the UE102and the TRPs104,106, and108ofFIG.1) implementing the BFD procedure. The example method700may also be performed by system200ofFIG.2, controlled or implemented by processor210, and/or computer system900ofFIG.9. But method700is not limited to the specific aspects depicted in those figures and other systems may be used to perform the method, as will be understood by those skilled in the art. It is to be appreciated that not all operations may be needed, and the operations may not be performed in the same order as shown inFIG.7.

At702, the UE102detects a plurality of beam failure events. In some aspects, the UE102performs the UE-specific BFD procedure and the TRP-specific BFD procedure because the UE102is in both the TRP-specific mode and the UE-specific mode. In addition, the UE102uses different sets of RSs for the UE-specific BFD procedure and the TRP-specific BFD procedure. Therefore, the UE102may detect the plurality of beam failure events at the same time based on the UE-specific BFD procedure and the TRP-specific BFD procedure.

At704, the UE102determines if a multiple BFR procedure is enabled. Similar to discussed above, the UE102enables the multiple BFR procedure by transmitting the multiple BFR capability report to the base station and receiving the multiple BFR configuration from the base station. In some aspects, the UE102enables the multiple BFR procedures by transmitting the multiple BFR capability report to the base station without receiving the multiple BFR configuration from the base station. If the multiple BFR procedure is enabled, the control moves to706. Otherwise, the control moves to708.

At706, the UE102triggers a plurality of BFRQs corresponding to the plurality of beam failure events. In some aspects, the UE102processes a plurality of BFRRs corresponding to the plurality of BFRQs to recover one or more communication links, such as the communication links110and112.

At708, the UE102determines statuses of the plurality of beam failure events. For example, the plurality of beam failure events include a first, a second, and a third beam failure events. The UE102determines the first beam failure event to be an event of the TRP104if the first beam failure event indicates that the one or more beams of the communication link110fail. The UE102also determines the second beam failure event to be an event of the TRP106if the second beam failure event indicates that the one or more beams of the communication link112fail and the third beam failure event to an event of the UE102if the third beam failure event indicates that all beams of the UE102fail.

At710, the UE102triggers a BFRQ procedure corresponding to one of the plurality of beam failure events based on their priorities. For example, the third beam failure event has a high priority; the first beam failure event has a medium priority; and the second beam failure event has a low priority. Therefore, when the UE102detects the first, the second, and the third beam failure events, the UE102triggers the BFRQ of the UE102, which corresponds to the third beam failure event. Similarly, if the UE102detects the first and the second beam failure events, the UE102triggers the BFRQ of the TRP104. In some aspects, the priorities of the first, the second, and the third beam failure events are configured by the base station. For example, the configuration message transmitted by the base station indicates the priorities of the first, the second, and the third beam failure events.

FIG.8illustrates an example method for the base station configuring the TRP-specific BFR. As a convenience and not a limitation,FIG.8may be described with regard to elements ofFIGS.1,2, and9. Method800may represent the operation of electronic devices (for example, the TRPs104,106, and108ofFIG.1) configuring the TRP-specific BFR. The example method800may also be performed by system200ofFIG.2, controlled or implemented by processor210, and/or computer system900ofFIG.9. But method800is not limited to the specific aspects depicted in those figures and other systems may be used to perform the method, as will be understood by those skilled in the art. It is to be appreciated that not all operations may be needed, and the operations may not be performed in the same order as shown inFIG.8.

At802, the base station generates a configuration message. In some aspects, the configuration message instructs the UE102to be in the multi-TRP mode or the single-TRP mode. For example, if the configuration message indicates the single-TRP mode and the UE102is in the multi-TRP mode. The UE102, upon receiving the configuration message, switches from the multi-TRP mode to the single-TRP mode.

At804, the base station generates a BFD configuration. In some aspects, the BFD configuration indicates a selected BFD option as disclosed inFIG.3. For example, if the BFD configuration indicates the BFD option 5 to be the selected BFD option, the UE102, upon receiving the BFD configuration, updates the BFD procedure based on the BFD option 5. In some aspects, the BFD configuration also includes the lengths of the first and the second time periods of the BFD option 5 disclosed inFIG.3.

At806, the base station generates a BFR configuration. In some aspects, the BFR configuration indicates a selected BFR option as disclosed inFIG.3. For example, if the BFR configuration indicates the BFR option 4 to be the selected BFR option, the UE102, upon receiving the BFR configuration, updates the BFR procedure based on the BFR option 4. In some aspects, the BFR configuration also includes the length of the third time period of the BFR option 4 disclosed inFIG.3.

At808, the base station transmits the configuration message, the BFD configuration, and the BFR configuration to the UE102. In some aspects, the base station transmits the configuration message, the BFD configuration, and the BFR configuration via a radio resource control (RRC) signaling, a MAC Control Element (MAC CE), or downlink control information (DCI). In some aspects, the base station transmits the BFD configuration and the BFR configuration before transmitting the configuration message.

Various aspects may be implemented, for example, using one or more computer systems, such as computer system900shown inFIG.9. Computer system900may be any well-known computer capable of performing the functions described herein such as electronic devices102,104,106, and108ofFIG.1, or200ofFIG.2. Computer system900includes one or more processors (also called central processing units, or CPUs), such as a processor904. Processor904is connected to a communication infrastructure906(e.g., a bus.) Computer system900also includes user input/output device(s)903, such as monitors, keyboards, pointing devices, etc., that communicate with communication infrastructure906through user input/output interface(s)902. Computer system900also includes a main or primary memory908, such as random access memory (RAM). Main memory908may include one or more levels of cache. Main memory908has stored therein control logic (e.g., computer software) and/or data.

Computer system900may also include one or more secondary storage devices or memory910. Secondary memory910may include, for example, a hard disk drive912and/or a removable storage device or drive914. Removable storage drive914may be a floppy disk drive, a magnetic tape drive, a compact disk drive, an optical storage device, tape backup device, and/or any other storage device/drive.

Removable storage drive914may interact with a removable storage unit918. Removable storage unit918includes a computer usable or readable storage device having stored thereon computer software (control logic) and/or data. Removable storage unit918may be a floppy disk, magnetic tape, compact disk, DVD, optical storage disk, and/any other computer data storage device. Removable storage drive914reads from and/or writes to removable storage unit918in a well-known manner.

According to some aspects, secondary memory910may include other means, instrumentalities or other approaches for allowing computer programs and/or other instructions and/or data to be accessed by computer system900. Such means, instrumentalities or other approaches may include, for example, a removable storage unit922and an interface920. Examples of the removable storage unit922and the interface920may include a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an EPROM or PROM) and associated socket, a memory stick and USB port, a memory card and associated memory card slot, and/or any other removable storage unit and associated interface.

Computer system900may further include a communication or network interface924. Communication interface924enables computer system900to communicate and interact with any combination of remote devices, remote networks, remote entities, etc. (individually and collectively referenced by reference number928). For example, communication interface924may allow computer system900to communicate with remote devices928over communications path926, which may be wired and/or wireless, and which may include any combination of LANs, WANs, the Internet, etc. Control logic and/or data may be transmitted to and from computer system900via communication path926.

The operations in the preceding aspects may be implemented in a wide variety of configurations and architectures. Therefore, some or all of the operations in the preceding aspects may be performed in hardware, in software or both. In some aspects, a tangible, non-transitory apparatus or article of manufacture includes a tangible, non-transitory computer useable or readable medium having control logic (software) stored thereon is also referred to herein as a computer program product or program storage device. This includes, but is not limited to, computer system900, main memory908, secondary memory910and removable storage units918and922, as well as tangible articles of manufacture embodying any combination of the foregoing. Such control logic, when executed by one or more data processing devices (such as computer system900), causes such data processing devices to operate as described herein.

While the disclosure has been described herein with reference to exemplary aspects for exemplary fields and applications, it should be understood that the disclosure is not limited thereto. Other aspects and modifications thereto are possible, and are within the scope and spirit of the disclosure. For example, and without limiting the generality of this paragraph, aspects are not limited to the software, hardware, firmware, and/or entities illustrated in the figures and/or described herein. Further, aspects (whether or not explicitly described herein) have significant utility to fields and applications beyond the examples described herein.

Aspects have been described herein with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined as long as the specified functions and relationships (or equivalents thereof) are appropriately performed. In addition, alternative aspects may perform functional blocks, steps, operations, methods, etc. using orderings different from those described herein.

The breadth and scope of the disclosure should not be limited by any of the above-described exemplary aspects, but should be defined only in accordance with the following claims and their equivalents.