Patent Application
20230058443
The present invention relates to a device and a method used in a wireless communication system, and more particularly, to a device and a method of handling a handover.
A long-term evolution (LTE) system supporting the 3rd Generation Partnership Project (3GPP) Rel-8 standard and/or the 3GPP Rel-9 standard is developed by the 3GPP as a successor of the universal mobile telecommunication system (UMTS) for further enhancing performance of the UMTS to satisfy increasing needs of users. The LTE system includes a new radio interface and a new radio network architecture that provides high data rate, low latency, packet optimization, and improved system capacity and coverage.
An LTE-advanced (LTE-A) system, as its name implies, is an evolution of the LTE system. The LTE-A system targets faster switching between power states, improves performance at the coverage edge of an evolved Node-B (eNB), increases peak data rate and throughput, and includes advanced techniques, such as carrier aggregation (CA), coordinated multipoint (CoMP) transmissions/reception, uplink (UL) multiple-input multiple-output (UL-MIMO), licensed-assisted access (LAA) (e.g., using LTE), etc.
A next generation radio access network (NG-RAN) is developed for further enhancing the LTE-A system. The NG-RAN includes one or more next generation Node-Bs (gNBs), and has properties of wider operation bands, different numerologies for different frequency ranges, massive MIMO, advanced channel codings, etc.
In the 3GPP Rel-16 standard, a dual active protocol stack (DAPS) handover is proposed to reduce a handover interruption time. The handover interruption time may approach 0 milliseconds. However, the DAPS handover cannot be performed in a high frequency (e.g., Frequency Range 2 (FR2)). The operators consider that it is required to perform the DAPS handover in the high frequency, because some services operated in the high frequency intend to achieve a consistent data rate with a low interruption time. Thus, how to perform a robust handover with the low interruption time in the high frequency is an important problem to be solved.
The present invention therefore provides a communication device and method for handling a handover to solve the abovementioned problem.
A method for handling a handover of a communication device, comprising: receiving a radio resource control (RRC) configuration message from a source network, wherein the RRC configuration message comprises at least one execution condition of at least one target network; transmitting a handover trigger message to the source network, when an execution condition of the at least one execution condition is satisfied; performing the handover from the source network to a target network of the at least one target network, wherein the target network is corresponding to the execution condition; and transmitting a handover complete message to the target network, after performing the handover.
A method for handling a handover of a communication device, comprising: receiving a radio resource control (RRC) configuration message from a source network, wherein the RRC configuration message comprises at least one execution condition of at least one target network; transmitting a handover trigger message to the source network, when an execution condition of the at least one execution condition is satisfied; starting a timer, after transmitting the handover trigger message to the source network; detecting a failure of the handover from the source network to a target network of the at least one target network, when the timer expires, wherein the target network is corresponding to the execution condition; and triggering a handover failure procedure according to the failure of the handover.
A method for handling a handover of a communication device, comprising: receiving a radio resource control (RRC) configuration message from a source network, wherein the RRC configuration message comprises at least one RRC configuration of at least one target network; triggering a handover from the source network to a suitable network, wherein the suitable network is one of the at least one target network; performing a dual active protocol stack (DAPS) handover from the source network to the suitable network, when an enable DAPS condition is satisfied and an RRC configuration of the suitable network comprises a DAPS configuration; and performing a first normal handover from the source network to the suitable network instead of the DAPS handover, when the enable DAPS condition is not satisfied.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
In
A new radio (NR) is a standard defined for a 5G system (or 5G network) to provide a unified air interface with better performance. gNBs are deployed to realize the 5G system, which supports advanced features such as enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communications (URLLC), massive Machine Type Communications (mMTC), etc. The eMBB provides broadband services with a greater bandwidth and a low/moderate latency. The URLLC provides applications (e.g., end-to-end communication) with properties of a higher reliability and a low latency. The examples of the applications include an industrial internet, smart grids, infrastructure protection, remote surgery and an intelligent transportation system (ITS). The mMTC is able to support internet-of-things (IoT) of the 5G system which include billions of connected devices and/or sensors.
Furthermore, the network 12 may also include at least one of the UTRAN/E-UTRAN/NG-RAN and a core network, wherein the core network may include network entities such as Mobility Management Entity (MME), Serving Gateway (S-GW), Packet Data Network (PDN) Gateway (P-GW), Self-Organizing Networks (SON) server and/or Radio Network Controller (RNC), etc. In one example, after the network 12 receives information transmitted by a communication device 14, the information may be processed only by the UTRAN/E-UTRAN/NG-RAN and decisions corresponding to the information are made at the UTRAN/E-UTRAN/NG-RAN. In one example, the UTRAN/E-UTRAN/NG-RAN may forward the information to the core network, and the decisions corresponding to the information are made at the core network after the core network processes the information. In one example, the information may be processed by both the UTRAN/E-UTRAN/NG-RAN and the core network, and the decisions are made after coordination and/or cooperation are performed by the UTRAN/E-UTRAN/NG-RAN and the core network.
A communication device 14 may be a user equipment (UE), a low cost device (e.g., machine type communication (MTC) device), a device-to-device (D2D) communication device, a narrow-band internet of things (IoT) (NB-IoT), a mobile phone, a laptop, a tablet computer, an electronic book, a portable computer system, or combination thereof. In addition, the network 12 and the communication device 14 can be seen as a transmitter or a receiver according to direction (i.e., transmission direction), e.g., for an uplink (UL), the communication device 14 is the transmitter and the network 12 is the receiver, and for a downlink (DL), the network 12 is the transmitter and the communication device 14 is the receiver.
Step 300: Start.
Step 302: Receive a radio resource control (RRC) configuration message from a source network, wherein the RRC configuration message comprises at least one execution condition of at least one target network.
Step 304: Transmit a first handover trigger message to the source network, when an execution condition of the at least one execution condition is satisfied.
Step 306: Perform the handover from the source network to a target network of the at least one target network, wherein the target network is corresponding to the execution condition.
Step 308: Transmit a handover complete message to the target network, after performing the handover.
Step 310: End.
According to the process 30, the communication device 20 receives an RRC configuration message from a source network. The RRC configuration message comprises at least one execution condition of at least one target network. The at least one execution condition is corresponding to the at least one target network, respectively. Then, the communication device 20 transmits a first handover trigger message to the source network, when an execution condition of the at least one execution condition is satisfied. The communication device 20 performs the handover (e.g., a dual active protocol stack (DAPS) handover) from the source network to a target network of the at least one target network, after transmitting the first handover trigger message. The target network is corresponding to the execution condition. The communication device 20 transmits a handover complete message to the target network, after performing the handover (successfully). Thus, the handover is performed robustly with the execution condition(s) in the high frequency, and the low handover interruption time can be achieved.
Realization of the process 30 is not limited to the above description. The following examples may be applied to realize the process 30.
In one example, the communication device 20 verifies the at least one execution condition in the RRC configuration message, after receiving the RRC configuration message. In one example, the communication device 20 transmits a measurement report (e.g., for the target network) as the first handover trigger message to the source network, when the execution condition is satisfied. That is, the communication device 20 informs the source network that the handover from the source network to the target network is triggered via the measurement report. In one example, the communication device 20 keeps connecting to the source network, when performing the handover.
In one example, the communication device 20 starts a first timer (e.g., a T304 timer), after transmitting the first handover trigger message to the source network. In one example, the communication device 20 stops the first timer, after transmitting the handover complete message to the target network (successfully). It should be noted that the communication device 20 determines whether a failure of the handover occurs according to (e.g., by maintaining) the first timer.
In one example, the source network transmits first downlink (DL) data to the target network, after transmitting the RRC configuration message to the communication device 20. In one example, the source network transmits the first DL data or a second handover trigger message to the target network in response to the first handover trigger message. That is, the source network informs the target network that the handover is triggered via the second DL data or the second handover trigger message. In one example, the second handover trigger message comprises the first handover trigger message. In one example, the second handover trigger message and the first handover trigger message are the same.
In one example, the target network processes the first DL data (e.g., compresses a header, ciphers and/or adds a packet data convergence protocol (PDCP) header), to generate second DL data. In one example, the target network transmits the second DL data to the communication device 20 (immediately), after receiving the handover complete message. In one example, the target network transmits a handover success message to the source network in response to the handover complete message.
In one example, the target network starts a second timer (e.g., a timer for the target network to detect a failure of the handover, hereafter referred to as a T-HF timer) in response to the second DL data or the second handover trigger message. In one example, the target network stops the second timer in response to the handover complete message. In one example, a value of the second timer is not smaller than the value of the first timer.
In one example, the source network starts a third timer (e.g., a T304-like timer) in response to the first handover trigger message. In one example, the source network stops the third timer in response to the handover success message. In one example, a value of the third timer is greater than the value of the first timer. That is, the source network determines whether the failure of the handover occurs according to (e.g., by maintaining) the third timer.
In one example, the source network transmits a handover request message to the at least one target network. In one example, the at least one target network transmits at least one handover acknowledgement (ACK) message to the source network in response to the handover request message, respectively. In one example, the at least one handover ACK message comprises at least one RRC configuration of the at least one target network, respectively. In one example, the at least one ACK message comprises a value of the first timer. In one example, the first handover trigger message comprises the value of the first timer. In one example, the first handover trigger message comprises an identity (ID) information of the target network.
In one example, the RRC configuration message comprises an RRC configuration of the target network, and the RRC configuration comprises a DAPS configuration. It should be noted that the communication device 20 transmits the first handover trigger message to the source network, if the RRC configuration comprises the DAPS configuration. The communication device 20 does not (need to) transmit the first handover trigger message, if the RRC configuration does not comprise the DASP configuration. In one example, the RRC configuration message comprises the at least one RRC configuration of the at least one target network, and the at least one RRC configuration is corresponding to the at least one execution condition, respectively. In one example, the RRC configuration is one of the at least one RRC configuration.
Then, the communication device 62 starts the T304 timer after transmitting the handover trigger message to the source network 64 (Step 608), and performs a handover from the source network 64 to the target network 66 (Step 610). The source network 64 starts a T304-like timer and transmits first DL data, in response to the handover trigger message (Steps 612 and 614). The target network 66 processes the first DL data, to generate second DL data (Step 616). The communication device 62 transmits a handover complete message to the target network 66, after performing the handover (successfully) (Step 618). The communication device 62 stops the T304 timer, after transmitting the handover complete message to the target network 66 (successfully) (Step 620). The target network 66 transmits the second DL data to the communication device 62 and transmits a handover success message to the source network 64, in response to the handover complete message (Steps 622 and 624). Finally, the source network 64 stops the T304-like timer in response to the handover success message (Step 626).
Then, the communication device 72 starts the T304 timer, after transmitting the handover trigger message to the source network 74 (Step 712), and performs a handover from the source network 74 to the target network 76 (Step 714). The source network 74 starts a T304-like timer and transmits first DL data, in response to the handover trigger message (Steps 718 and 720). The target network 76 processes the first DL data, to generate second DL data (Step 722). The communication device 72 transmits a handover complete message to the target network 76, after performing the handover (successfully) (Step 724). The communication device 72 stops the T304 timer, after transmitting the handover complete message to the target network 76 (successfully) (Step 726). The target network 76 transmits the second DL data to the communication device 72 and transmits a handover success message to the source network 74, in response to the handover complete message (Steps 728 and 730). Finally, the source network 74 stops the T304-like timer in response to the handover success message (Step 732).
The processes 50-70 are the cases that the handover is performed successfully. In processes 60-70, the communication device 62/72 determines whether the failure of the handover occurs according to the T304 timer, and the source network 64/74 determines whether the failure of the handover occurs according to the T304-like timer. In the process 60, the communication device 62 informs the source network 64 of the value of the T304 timer via the handover trigger message. In the process 70, the target network 76 informs the source network 74 of the value of the T304 timer via the handover ACK message. In the process 70, the source network 74 transmits the handover request message to all target networks (e.g., the target networks TN1-TN3 in
Step 800: Start.
Step 802: Receive an RRC configuration message from a source network, wherein the RRC configuration message comprises at least one execution condition of at least one target network.
Step 804: Transmit a first handover trigger message to the source network, when an execution condition of the at least one execution condition is satisfied.
Step 806: Start a first timer, after transmitting the first handover trigger message to the source network.
Step 808: Detect a failure of the handover from the source network to a target network of the at least one target network, when the first timer expires, wherein the target network is corresponding to the execution condition.
Step 810: Trigger a handover failure procedure according to the failure of the handover.
Step 812: End.
According to the process 80, the communication device 20 receives an RRC configuration message from a source network. The RRC configuration message comprises at least one execution condition of at least one target network. The at least one execution condition is corresponding to the at least one target network, respectively. Then, the communication device 20 transmits a first handover trigger message to the source network, when an execution condition of the at least one execution condition is satisfied. The communication device 20 starts a first timer (e.g., a T304 timer), after transmitting the first handover trigger message to the source network. The communication device 20 detects a failure of the handover (e.g., a DAPS handover) from the source network to a target network of the at least one target network, when the first timer expires. The target network is corresponding to the execution condition. Then, the communication device 20 triggers a handover failure procedure according to the failure of the handover. That is, the communication device 20 determines whether the failure of the handover occurs according to (e.g., by maintaining) the first timer, to trigger the handover failure procedure when the failure of the handover occurs. Thus, the communication device 20 can handle the failed handover in the high frequency.
Realization of the process 80 is not limited to the above description. The following examples may be applied to realize the process 80.
In one example, the communication device 20 verifies the at least one execution condition in the RRC configuration message, after receiving the RRC configuration message. In one example, the communication device 20 transmits a measurement report as the first handover trigger message to the source network, when the execution condition is satisfied. That is, the communication device 20 informs the source network that the handover is triggered via the measurement report.
In one example, the source network transmits DL data to the target network, after transmitting the RRC configuration message to the communication device 20. In one example, the source network transmits the DL data or a second handover trigger message to the target network in response to the first handover trigger message. That is, the source network informs the target network that the handover is triggered via the second DL data or the second handover trigger message. In one example, the second handover trigger message comprises the first handover trigger message. In one example, the second handover trigger message and the first handover trigger message are the same.
There are various ways to trigger the handover failure procedure. In one example, the communication device 20 declares a radio link failure (RLF) between the communication device 20 and the source network, after starting the first timer. In one example, the communication device 20 triggers a reestablishment procedure, after declaring the RLF. That is, the communication device 20 detects the RLF after starting the first timer, and triggers the reestablishment procedure according to the RLF. In one example, the communication device 20 transmits a handover failure information indicating the failure of the handover to the source network, when the first timer expires and the communication device 20 does not declare the RLF between the communication device 20 and the source network.
In one example, the source network transmits a handover finish message to the target network in response to the handover failure information. In one example, the source network stops transmitting the DL data in response to the handover failure information.
In one example, the target network starts a second timer (e.g., a T-HF timer) in response to the DL data or the second handover trigger message. In one example, the target network transmits the handover finish message to the source network, when the second timer expires. That is, the target network determines that the failure of the handover occurs and informs the source network of the failure of the handover, when the second timer expires. In one example, the target network starts the second timer in response to the DL data or the second handover trigger message. In one example, the target network stops the second timer in response to the handover finish message. In one example, a value of the second timer is not smaller than the value of the first timer.
In one example, the source network starts a third timer (e.g., a T304-like timer) in response to the first handover trigger message. In one example, the source network stops transmitting the DL data and transmits the handover finish message to the target network, when the third timer expires. That is, the source network determines that the failure of the handover occurs and informs the target network of the failure of the handover, when the third timer expires. In one example, the source network stops the third timer in response to the handover failure information. In one example, a value of the third timer is greater than the value of the first timer.
In one example, the at least one target network receives a handover request message from the source network. In one example, the at least one target network transmits at least one handover ACK message to the source network in response to the handover request message, respectively. In one example, the at least one handover ACK message comprises at least one RRC configuration of the at least one target network, respectively. In one example, the at least one handover ACK message comprises a value of the first timer. In one example, the first handover trigger message comprises the value of the first timer. In one example, the first handover trigger message comprises an ID information of the target network.
In one example, the RRC configuration message comprises an RRC configuration of the target network, and the RRC configuration comprises a DAPS configuration. It should be noted that the communication device 20 transmits the first handover trigger message to the source network, if the RRC configuration comprises the DAPS configuration. The communication device 20 does not (need to) transmit the first handover trigger message, if the RRC configuration does not comprise the DASP configuration. In one example, the RRC configuration message comprises the at least one RRC configuration of the at least one target network, and the at least one RRC configuration is corresponding to the at least one execution condition, respectively. In one example, the RRC configuration is one of the at least one RRC configuration.
Then, the communication device 92 declares an RLF between the communication device 92 and the source network 94 and releases a radio link (RL) between the communication device 92 and the source network 94, after starting the T304 timer (Step 910). The communication device 92 determines that the T304 timer expires (Step 912). The communication device 92 detects a failure of a handover from the source network 94 to the target network 96, when the T304 timer expires (Step 914). The communication device 92 triggers a reestablishment procedure (Step 916). The source network 94 transmits DL data to the target network 96 in response to the handover trigger message (Step 918). The target network 96 starts a T-HF timer in response to the DL data (Step 920). The target network 96 determines that the T-HF timer expires (Step 922), and transmits a handover finish message to the source network 94 when the T-HF timer expires (Step 924). Finally, the source network 94 stops transmitting the DL data in response to the handover finish message (Step 926).
Then, the source network 104 transmits DL data to the target network 106 in response to the handover trigger message (Step 1008), and the target network 106 starts a T-HF timer in response to the DL data (Step 1010). The communication device 102 starts a T304 timer, after transmitting the handover trigger message to the source network 104 (Step 1012). The communication device 102 determines that the T304 timer expires (Step 1014). The communication device 102 detects a failure of a handover from the source network 104 to the target network 106, when the T304 timer expires (Step 1016). The communication device 102 transmits a handover failure information to the source network 104, when the T304 timer expires and the communication device 102 does not declare the RLF between the communication device 102 and the source network 104 (Step 1018). The source network 104 stops transmitting the DL data to the target network 106 and transmits a handover finish message to the source network 104, in response to the handover failure information (Steps 1020 and 1022). Finally, the target network 106 stops the T-HF timer in response to the handover finish message (Step 1024).
Then, the communication device 112 starts a T304 timer, after transmitting the handover trigger message to the source network 114 (Step 1110). The source network 114 transmits a second handover trigger message to the target network 116 in response to the handover trigger message (Step 1112), and the target network 116 starts a T-HF timer in response to the second handover trigger message (Step 1114). That is, the source network 114 transmits the DL data to the target network 116 in advance, so that the target network 116 may process the DL data early. The following operations in the process 110 can be referred to the processes 90 and 100, and are not narrated herein for brevity.
Then, the communication device 122 starts the T304 timer, after transmitting the handover trigger message to the source network 124 (Step 1208). The communication device 122 declares an RLF between the communication device 122 and the source network 124 and releases an RL between the communication device 122 and the source network 124, after starting the T304 timer (Step 1210). The communication device 122 determines that the T304 timer expires (Step 1212). The communication device 122 detects a failure of a handover from the source network 124 to the target network 126, when the T304 timer expires (Step 1214). The communication device 122 triggers a reestablishment procedure (Step 1216). The source network 124 starts a T304-like timer and transmits DL data to the target network 126, in response to the handover trigger message (Steps 1218 and 1220). The source network 124 determines that the T304-like timer expires (Step 1222). Finally, the source network 124 stops transmitting the DL data and transmits a handover finish message to the target network 126, when the T304-like timer expires (Steps 1224 and 1226).
Then, the source network 134 starts a T304-like timer and transmits DL data to the target network 136, in response to the handover trigger message (Steps 1308 and 1310). The communication device 132 starts the T304 timer, after transmitting the handover trigger message to the source network 134 (Step 1312). The communication device 132 determines that the T304 timer expires (Step 1314). The communication device 132 detects a failure of a handover from the source network 134 to the target network 136, when the T304 timer expires (Step 1316). The communication device 132 transmits a handover failure information to the source network 134, when the T304 timer expires and the communication device 132 does not declare the RLF between the communication device 132 and the source network 134 (Step 1318). Finally, the source network 134 stops the T304-like timer, stops transmitting the DL data to the target network 136 and transmits a handover finish message to the source network 134, in response to the handover failure message (Steps 1320, 1322 and 1324).
Then, the communication device 142 starts the T304 timer, after transmitting the handover trigger message to the source network 144 (Step 1412). The communication device 142 declares an RLF between the communication device 142 and the source network 144 and releases an RL between the communication device 142 and the source network 144, after starting the T304 timer (Step 1414). The communication device 142 determines that the T304 timer expires (Step 1416). The communication device 142 detects a failure of a handover from the source network 144 to the target network 146, when the T304 timer expires (Step 1418). The communication device 142 triggers a reestablishment procedure (Step 1420). The source network 144 starts a T304-like timer and transmits DL data to the target network 146, in response to the handover trigger message (Steps 1422 and 1424). The source network 144 determines that the T304-like timer expires (Step 1426). Finally, the source network 144 stops transmitting the DL data and transmits a handover finish message to the target network 146, when the T304-like timer expires (Steps 1428 and 1430).
Then, the source network 154 starts a T304-like timer and transmits DL data to the target network 156, in response to the handover trigger message (Steps 1512 and 1514). The communication device 152 starts the T304 timer, after transmitting the handover trigger message to the source network 154 (Step 1516). The communication device 152 determines that the T304 timer expires (Step 1518). The communication device 152 detects a failure of a handover from the source network 154 to the target network 156, when the T304 timer expires (Step 1520). The communication device 152 transmits a handover failure information to the source network 154, when the T304 timer expires and the communication device 152 does not declare the RLF between the communication device 152 and the source network 154 (Step 1522). Finally, the source network 154 stops the T304-like timer, stops transmitting the DL data to the target network 156 and transmits a handover finish message to the source network 154, in response to the handover failure message (Steps 1524, 1526 and 1528).
The processes 90, 120 and 140 are the cases that the failure of the handover and the RLF occur, while the processes 100, 130 and 150 are the cases that the failure of the handover occurs but the RLF does not occur. In the processes 90-150, the communication device 92/102/112/122/132/142/152 determines whether the failure of the handover occurs according to the T304 timer. In the processes 90-110, the target network 96/106/116 determines whether the failure of the handover occurs according to the T-HF timer. In the processes 120-150, the source network 124/134/144/154 determines whether the failure of the handover occurs according to the T304-like timer.
In the processes 120-130, the communication device 122/132 informs the source network 124/134 of the value of the T304 timer via the handover trigger message. In the processes 140-150, the target network 146/156 informs the source network 144/154 of the value of the T304 timer via the handover ACK message. In the processes 140-150, the source network 144/154 transmits the handover request message to all target networks (e.g., the target networks TN1-TN3 in
Step 1600: Start.
Step 1602: Receive an RRC configuration message from a source network, wherein the RRC configuration message comprises at least one RRC configuration of at least one target network.
Step 1604: Trigger a handover from the source network to a suitable network, wherein the suitable network is one of the at least one target network.
Step 1606: Perform a DAPS handover from the source network to the suitable network, when an enable DAPS condition is satisfied and an RRC configuration of the suitable network comprises a DAPS configuration.
Step 1608: Perform a first normal handover from the source network to the suitable network, when the enable DAPS condition is not satisfied.
Step 1610: End.
According to the process 160, the communication device 20 receives an RRC configuration message from a source network. The RRC configuration message comprises at least one RRC configuration of at least one target network. The at least one RRC configuration is corresponding to the at least one target network, respectively. Then, the communication device 20 triggers a handover from the source network to a suitable network. The suitable network is one of the at least one target network. The communication device 20 performs a DAPS handover from the source network to the suitable network, when an enable DAPS condition is satisfied and an RRC configuration of the suitable network comprises a DAPS configuration. The RRC configuration of the suitable network is one of the at least one RRC configuration. The communication device 20 performs a first normal handover from the source network to the suitable network, when the enable DAPS condition is not satisfied. That is, the handover may be the DAPS handover, when the enable DAPS condition is satisfied and the RRC configuration of the suitable network comprises the DAPS configuration. The handover may be the first normal handover, when the enable DAPS condition is not satisfied. Thus, the handover is performed flexibly according to the enable DAPS condition.
Realization of the process 160 is not limited to the above description. The following examples may be applied to realize the process 160.
In one example, the communication device 20 detects (or declares) a communication failure between the communication device 20 and the source network, and triggers a reestablishment procedure according to the communication failure. Then, the communication device 20 selects the suitable network (e.g., during the reestablishment procedure), after triggering the reestablishment procedure. The communication device 20 sets a flag according to the communication failure. In one example, the flag indicates that the DAPS handover is disabled. In one example, the communication failure comprises at least one of a failure of a second normal handover, a failure of a conditional handover or an RLF.
In one example, the RRC configuration message comprises at least one execution condition of the at least one target network. In one example, the at least one execution condition is corresponding to the at least one RRC configuration, respectively.
In one example, the communication device 20 determines whether the enable DAPS condition is satisfied, after triggering the DAPS handover. There are various ways to determine whether the enable DAPS condition is satisfied. In one example, the communication device 20 determines that the enable DAPS condition is satisfied, when the handover is triggered by a satisfied execution condition of the at least one execution condition (i.e., one of the at least one execution condition is satisfied). In one example, the communication device 20 determines that the enable DAPS condition is not satisfied, when the handover is not triggered by the at least one execution condition (i.e., all of the at least one execution condition is not satisfied). In one example, the communication device 20 determines that the enable DAPS condition is satisfied, when the flag is not set. In one example, the communication device 20 determines that the enable DAPS condition is not satisfied, when the flag is set.
In one example, the communication device 20 detaches from the source network, when performing the first normal handover. In one example, the communication device 20 keeps connecting to the source network, when performing the DAPS handover. In one example, the communication device 20 releases the flag, if the suitable network is not the one of the at least one target network. In one example, the communication device 20 performs the reestablishment procedure with the suitable network, if the suitable network is not the one of the at least one target network.
The examples of the processes 30 and 80 may be applied to the process 160, and are not narrated herein for brevity.
The detail of the DAPS handover procedure can be referred to the processes 30 and 80, and not narrated herein for brevity.
The operation of “determine” described above may be replaced by the operation of “compute”, “calculate”, “obtain”, “generate”, “output, “use”, “choose/select”, “decide” or “is configured to”. The operation of “detect” described above may be replaced by the operation of “monitor”, “receive”, “sense” or “obtain”. The phrase of “according to” described above may be replaced by “in response to”. The phrase of “corresponding to” described above may be replaced by “of” or “associated with”. The term of “via” described above may be replaced by “on”, “in” or “at”. The term of “when” described above may be replaced by “in response to”.
Those skilled in the art should readily make combinations, modifications and/or alterations on the abovementioned description and examples. The abovementioned description, steps and/or processes including suggested steps can be realized by means that could be hardware, software, firmware (known as a combination of a hardware device and computer instructions and data that reside as read-only software on the hardware device), an electronic system, or combination thereof. An example of the means may be the communication device 20.
Examples of the hardware may include analog circuit(s), digital circuit(s) and/or mixed circuit(s). For example, the hardware may include ASIC(s), field programmable gate array(s) (FPGA(s)), programmable logic device(s), coupled hardware components or combination thereof. In another example, the hardware may include general-purpose processor(s), microprocessor(s), controller(s), digital signal processor(s) (DSP(s)) or combination thereof.
Examples of the software may include set(s) of codes, set(s) of instructions and/or set(s) of functions retained (e.g., stored) in a storage unit, e.g., a computer-readable medium. The computer-readable medium may include SIM, ROM, flash memory, RAM, CD-ROM/DVD-ROM/BD-ROM, magnetic tape, hard disk, optical data storage device, non-volatile storage unit, or combination thereof. The computer-readable medium (e.g., storage unit) may be coupled to at least one processor internally (e.g., integrated) or externally (e.g., separated). The at least one processor which may include one or more modules may (e.g., be configured to) execute the software in the computer-readable medium. The set(s) of codes, the set(s) of instructions and/or the set(s) of functions may cause the at least one processor, the module(s), the hardware and/or the electronic system to perform the related steps.
Examples of the electronic system may include a system on chip (SoC), system in package (SiP), a computer on module (CoM), a computer program product, an apparatus, a mobile phone, a laptop, a tablet computer, an electronic book or a portable computer system, and the communication device 20.
To sum up, embodiments of the present invention provide a communication device and method for handling a handover. The handover is performed robustly with the execution condition(s), and/or is performed flexibly according to the enable DAPS condition. Thus, the communication device can handle a robust handover with the low interruption time in the high frequency.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
This application claims the benefit of U.S. Provisional Application No. 63/235,176, filed on Aug. 20, 2021. The content of the application is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63235176 | Aug 2021 | US |
