WO2019136631A1 - Techniques d'accès aléatoire dans des réseaux sans fil - Google Patents

Techniques d'accès aléatoire dans des réseaux sans fil Download PDF

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Publication number
WO2019136631A1
WO2019136631A1 PCT/CN2018/072092 CN2018072092W WO2019136631A1 WO 2019136631 A1 WO2019136631 A1 WO 2019136631A1 CN 2018072092 W CN2018072092 W CN 2018072092W WO 2019136631 A1 WO2019136631 A1 WO 2019136631A1
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Prior art keywords
random access
timer
wireless communication
communication method
resource
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PCT/CN2018/072092
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English (en)
Inventor
Xiaojuan Shi
He Huang
Eswar Kalyan Vutukuri
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Zte Corporation
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Priority to PCT/CN2018/072092 priority Critical patent/WO2019136631A1/fr
Priority to CN201880080036.1A priority patent/CN111466149A/zh
Publication of WO2019136631A1 publication Critical patent/WO2019136631A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0833—Random access procedures, e.g. with 4-step access
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/20—Manipulation of established connections
    • H04W76/27—Transitions between radio resource control [RRC] states

Definitions

  • This disclosure is directed generally to digital wireless communications.
  • LTE Long-Term Evolution
  • 3GPP 3rd Generation Partnership Project
  • LTE-A LTE Advanced
  • 5G 5th generation of wireless system
  • 5G further advances the LTE and LTE-A wireless standards and is committed to supporting higher data-rates, large number of connections, ultra-low latency, high reliability and other emerging business needs.
  • An exemplary embodiment discloses a wireless communication method.
  • the exemplary method comprises starting a timer and initiating, by a user device, a random access procedure in response to a random access triggering event, wherein a time instance associated with the starting of the timer depends on the random access triggering event, and performing the random access procedure by detecting at least one Reference Signal (RS) while the timer is running.
  • RS Reference Signal
  • the performing of the random access procedure further comprises in response to determining an absence of the Reference Signal (RS) : applying a backoff time, and detecting, after applying the backoff time, at least one Reference Signal (RS) while the timer is running.
  • RS Reference Signal
  • the Reference Signal (RS) is a qualified Reference Signal (RS) .
  • the qualified Reference Signal (RS) is a synchronization signal (SS) resource or a channel state information reference signal (CSI-RS) resource.
  • the qualified Reference Signal (RS) includes a resource that satisfies a predetermined threshold or a resource that allows the user device to meet a target received power of a random access channel (RACH) preamble with a maximum transmit power of the user device.
  • RACH random access channel
  • the random access triggering event includes sending a scheduling request (SR) , requesting system information (SI) , performing initial access from RRC_IDLE to RRC_CONNECTED, performing RRC Connection Re-establishment, performing handover, perform RRC Connection Resume, or recovering from beam failure.
  • SR scheduling request
  • SI system information
  • wireless communication method further comprises determining an expiration of the timer, indicating, in response to the random access triggering event being the sending of the scheduling request (SR) , a random access problem by a Medium Access Control (MAC) entity to a first layer above the MAC entity, and indicating, in response to the random access triggering event being the requesting of the system information (SI) , a failed SI request.
  • the first layer is a Radio Resource Control (RRC) layer.
  • the second layer is a Non Access Stratum (NAS) layer or an application layer.
  • the random access triggering event being the requesting of the system information (SI) : initiating a connection re-establishment procedure.
  • the random access triggering event being the requesting of the system information (SI) : informing a second layer above a Radio Resource Control (RRC) layer of the failed SI request in response to the requesting of the system information (SI) being triggered by the second layer.
  • RRC Radio Resource Control
  • the time instance when the timer is started is before or at a same time as the initiating of the random access procedure by the random access triggering event.
  • the wireless communication method further comprises stopping the timer in response to determining a successful random access procedure.
  • a wireless communication method comprises initiating, by a user device, a random access resource selection procedure, starting a timer in response to the initiating of the random access resource selection procedure during a random access procedure, and stopping the timer in response to detecting a Reference Signal (RS) .
  • RS Reference Signal
  • a time instance associated with the starting of the timer is before or at a same time as the initiating of the random access resource selection procedure.
  • the wireless communication method further comprises determining an expiration of the timer, and indicating a random access problem by a Medium Access Control (MAC) entity to a layer above the MAC entity
  • MAC Medium Access Control
  • the wireless communication method further comprises determining an expiration of the timer, increasing, after determining the timer expiration, a number of random access resource selection procedures by a predetermined value, re-initiating, after determining the timer expiration, the random access resource selection procedure in response to determining the number of random access resource selection procedures to be less than a maximum number of random access resource selection procedures, and indicating, after determining the timer expiration, a random access problem by a Medium Access Control (MAC) entity to a layer above the MAC entity in response to determining the number of random access resource selection procedures to be equal to the maximum number of random access resource selection procedures.
  • MAC Medium Access Control
  • the random access resource selection procedure is re-initiated after applying a backoff time.
  • the wireless communication method further comprises determining an expiration of the timer, indicating a random access resource selection failure to a layer above the MAC entity, and re-initiating, after determining the timer expiration , the random access resource selection procedure.
  • the wireless communication method further comprises declaring radio link failure, by the layer above MAC layer, in response to receiving a maximum number of random access resource selection failure.
  • the above-described methods are embodied in the form of processor-executable code and stored in a computer-readable program medium.
  • a device that is configured or operable to perform the above-described methods is disclosed.
  • FIG. 1 shows several user equipment and a base station operating within in a cell region of a wireless system.
  • FIG. 2 illustrates an exemplary random access procedure
  • FIG. 3 illustrates an exemplary reference signal resource selection procedure.
  • FIG. 4 illustrates an exemplary contention-based random access resource selection procedure using certain exemplary timer features.
  • FIG. 5 illustrates another exemplary contention free random access resource selection procedure using certain exemplary timer features.
  • FIG. 6 shows a block diagram for an exemplary user equipment to implement the random access and timer features.
  • next generation wireless systems will adopt high operating frequencies, such as up to 100GHz.
  • high operating frequencies such as up to 100GHz.
  • propagation loss can be high.
  • next generation wireless communication devices can employ antenna arrays and beamforming (BF) technologies using multiple-in-multiple-out (MIMO) techniques.
  • BF beamforming
  • MIMO multiple-in-multiple-out
  • 1024 antenna elements can be employed for one node to achieve beam alignment and obtain sufficiently high antenna gain.
  • UEs can use random access procedure to access networks in wireless systems such as Universal Terrestrial Radio Access Network (UTRAN) , E-UTRAN, or 5G New Radio (NR) .
  • UTRAN Universal Terrestrial Radio Access Network
  • NR 5G New Radio
  • the random access procedure can be triggered by a number of events, for instance:
  • RRC Radio Resource Control
  • the legacy random access procedure is designed for wireless systems without the adoption of BF technologies, such as UTRAN or E-UTRAN. With the introduction of BF technologies in 5G NR, the legacy random access procedure can be enhanced or redesigned to incorporate the BF property.
  • the random access channel (RACH) configurations associated with Reference Signal (RS) resources e.g. beams
  • RS Reference Signal
  • a RS resource can include, for example, a synchronization signal (SS) block or channel state information reference signal (CSI-RS) resource.
  • SS synchronization signal
  • CSI-RS channel state information reference signal
  • Legacy random access procedures can have certain drawbacks when implemented in a 5G NR wireless system. For example, taking the RACH configuration associated with SS blocks provided from the network, when a random access procedure is initiated, the UE selects the SS block (s) and corresponding PRACH resource (s) for path-loss estimation and (re) transmission based on SS blocks that satisfy the threshold given from the network. If no SS block that satisfies the given threshold is detected, the UE has the flexibility to select any SS block that allows UE to meet the target received power of the RACH preamble with its maximum transmit power.
  • wireless systems operating at high frequency ranges, for example above 6GHz are sensitive to the change of the wireless propagation environment.
  • the qualified resource may be a resource such as for example an SS block that satisfies the threshold given from the network or an SS block that allows UE to meet the target received power of the RACH preamble with the UE’s maximum transmit power. In such situations, it may be possible that no qualified RS resource is successfully detected. Or there may be situations where no qualified RS resource can be detected due to the movement or rotation of the UE in the RS selecting procedure.
  • the random access techniques described in the present document may be used by embodiments to address these situations, among others.
  • FIG. 1 shows several user equipment and a base station operating within in a cell region of a wireless system.
  • the base station BS1 (120a) can communicate with user equipment UE1 (110a) , UE2 (110b) , UE3 (110c) , or UE4 (110d) located within the cell region 130.
  • the one or more UEs can perform the exemplary random access techniques described in this patent document.
  • FIG. 2 illustrates an exemplary random access procedure.
  • a user equipment can start a timer when a random access procedure is initiated by a random access triggering event.
  • a time instance associated with the starting of the timer depends on the random access triggering event.
  • the time instance when the timer is started can be before or at the same time as the initiating of the random access procedure by the random access triggering event.
  • a time instance when a timer is started can be t1 and a time when the random access trigger event initiates the random access procedure can be t2, where t1 ⁇ t2.
  • the timer can be configured by the network and sent to the UE using, for example, system information or RRC signaling.
  • the random access procedure can be performed by detecting at least one qualified RS resource while the timer is running.
  • the UE can keep performing detection of qualified RS resource until at least one qualified RS resource is detected.
  • the UE can perform qualified RS resource selection each time a random access resource selection procedure is initiated during the random access procedure.
  • a UE can also determine an absence of a detection of a qualified RS resource. For example, when a random access resource selection procedure is initiated, the UE can check the quantity of each RS resource available in UE. If no qualified RS resource is available, then the UE determines an absence of a detection of a qualified RS resource. If the UE detects an absence of a qualified RS resource and if the UE determines that the timer, such as a sr-RandomAccessTimer, is still running, then the UE can continue to perform qualified RS resource detection after a backoff time. Both the applying of the backoff time and then the continuing of the qualified RS resource detection procedure after the backoff time can be repeated until at least one qualified RS resource is detected or the sr-RandomAccessTimer timer expires.
  • the timer such as a sr-RandomAccessTimer
  • the random access procedure can be triggered by variety of events.
  • the random access trigger event can be either a random access triggered by the sending of a scheduling request (SR) or a random access triggered by the request of other system information (SI) .
  • SR scheduling request
  • SI system information
  • the details associated with the random access triggered by SR or SI will be further described in the sections I. (a) and I. (b) below.
  • the random access trigger event may also include performing initial access from RRC_IDLE to RRC_CONNECTED, performing RRC Connection Re-establishment, performing handover, perform RRC Connection Resume, or recovering from beam failure.
  • a MAC entity can indicate a random access problem to an upper layer, such as a RRC layer.
  • the SI request is considered failed and the UE may perform at least one of the following: (a) initiate the connection re-establishment procedure, or (b) if the SI request is triggered by an upper layer, inform the failure of SI acquisition to the corresponding upper layer that triggers the SI request.
  • the upper layer includes layers above the RRC layer, such as the Non Access Stratum (NAS) layer or the application layer.
  • a establish_timer for example, a T300 timer can be started when the RRCConnectionRequest message requesting for a connection setup is initiated for transmission.
  • a RRCConnectionRequest message can be issued from the RRC layer to the MAC entity for transmission.
  • a resume_timer can be started when the RRCConnectionResumeRequest message requesting for a connection resume is initiated for transmission.
  • a RRCConnectionResumeRequest message can be issued from the RRC layer to the MAC entity for transmission.
  • the resume_timer maybe reuse the T300 timer or use a new timer.
  • a reestablish_timer can be started when the RRCConnectionReestablishmentRequest message requesting for re-establishing a connection is initiated for transmission.
  • a RRCConnectionReestablishmentRequest message can be issued from the RRC layer to the MAC entity for transmission.
  • reestablish_timer may use a timer such as T301 or it may reuse T300.
  • a handover_timer can be started when the message for mobility, such as a handover command, is received.
  • the handover_timer can use, for example, T304 for Primary Cell (PCell) or T307 for Primary Secondary Cell (PSCell) .
  • a beamFailureRecoveryTimer can be started when the beam failure happens.
  • the corresponding establish_timer, resume_timer, reestablish_timer, handover_timer or beamFailureRecoveryTimer can be used to control the random access procedure.
  • the UE can performs qualified RS resource selection each time a random access resource selection procedure is initiated during the random access that is triggered by one of the above five triggering events.
  • the timer is running, the UE can keep performing detection of a qualified RS resource until at least one qualified RS resource is detected.
  • the UE can continue to perform qualified RS resource detection after a backoff time. Both the applying of the backoff time and then the continuing of the qualified RS resource detection procedure after the backoff time can be repeated until at least one qualified RS resource is detected or the sr-RandomAccessTimer timer expires.
  • the timer such as a sr-RandomAccessTimer
  • the user equipment can stop the timer when the random access is considered successfully completed.
  • the random access procedure control is described for the random access procedure that may be triggered by the sending of SR or triggered by the request of other SI.
  • the example headings for the various sections below are used to facilitate the understanding of the disclosed subject matter and do not limit the scope of the claimed subject matter in any way. Accordingly, one or more features of one example section can be combined with one or more features of another example section.
  • a SR may be triggered.
  • a buffer status report (BSR) will be triggered to indicate the new uplink (UL) data available to the network when (i) the MAC entity has new UL data available for a logical channel which belongs to an logical channel group (LCG) , and when either (ii. a) the new UL data belongs to a logical channel with higher priority than the priority of any logical channel containing available UL data which belong to any LCG or (ii. b) none of the logical channels which belong to an LCG contains any available UL data.
  • a SR will be triggered to request UL scheduling since there is neither uplink shared channel (UL-SCH) resources available for a new immediate transmission nor configured UL grant at that time.
  • UL-SCH uplink shared channel
  • SR can be transmitted on the PUCCH resources that are configured for SR transmission.
  • the configuration of the dedicated PUCCH resources for SR transmission are decided by the network. So there are cases that when a SR is triggered, there is no valid PUCCH resource configured for the sending of the SR. In such a case, a random access procedure is triggered. But even if there is a valid PUCCH resource configured for SR, when the number of transmission for this SR has reached to the network configured maximum times, a random access procedure is triggered.
  • a UE can start a sr-RandomAccessTimer when the random access procedure is initiated.
  • the UE can performs qualified RS resource selection.
  • the UE can keep performing detection of qualified RS resource until at least one qualified RS resource is detected.
  • the UE if the UE detects an absence of a qualified RS resource, then the UE can keep performing detection of a qualified RS resource until the UE detects at least one qualified RS resource or the UE determines that the sr-RandomAccessTimer timer has expired.
  • the UE can continues the qualified RS resource detection process after a backoff time. Both the applying of the backoff time and then the continuing of the qualified RS resource detection procedure after the backoff time can be repeated until at least one qualified RS resource is detected or the sr-RandomAccessTimer timer expires.
  • the UE can select a random backoff time according to a uniform distribution between 0 and a constant provided by the network.
  • the UE select one of the detected RS resources and the corresponding PRACH resource (s) associated with the selected RS resource for path-loss estimation and (re) transmission.
  • the above qualified RS resource detection behavior can be applied for each random access resource selection procedure during the random access procedure.
  • the above qualified RS resource detection behavior is not only applied for the random access resource selection procedure when the random access procedure is initially initiated, such as the first random access attempt of the random access procedure, but it is also applied for the random access resource selection procedure for each following random access attempts. For instance, after the transmission of the random access preamble (Msg1) , the UE can monitor the network’s response for Msg1, e.g., the random access response (RAR) . If the UE fails to receive a correct response for Msg1 within a configured time window, the UE can initiate another random access attempt.
  • Msg1 the random access response for Msg1
  • RAR random access response
  • the UE can initiate another random access attempt.
  • the UE can start from the random access resource selection procedure.
  • the above qualified RS resource detection behavior can also apply to the random access resource selection procedure in the succeeding random access attempts.
  • the UE can stop the sr-RandomAccessTimer when the random access is considered successfully completed.
  • a contention based random access can be performed for the random access triggered by the sending of SR. With the completion of the contention resolution, the random access is considered successfully completed.
  • the MAC entity can indicate a random access problem to the upper layer, such as a RRC layer.
  • the RRC layer can initiate the RRC Connection re-establishment procedure.
  • system information are classified into two types, one is essential SI, including MIB and SIB1, and the other is other SI.
  • the essential SI is proactively broadcasted by the network. For example, a standalone cell broadcasts the essential SI periodically.
  • the other SI will be broadcasted by the network only if it is requested by at least one UE.
  • the other SI may be requested by the RRC layer, NAS layer, or application layer in UE or the other SI may be requested by the user.
  • the RRC layer triggers the MAC entity to initiate the random access procedure and can starts a timer known as a si-RandomAccessTimer.
  • the UE For the purpose of path-loss estimation and the following (re) transmission for the random access, the UE performs qualified RS resource selection.
  • the UE can keep performing detection of a qualified RS resource until at least one qualified RS resource is detected.
  • the UE if the UE detects an absence of a qualified RS resource, the UE can keep performing detection of a qualified RS resource detection until at least one qualified RS resource is detected or the UE determines that the si-RandomAccessTimer timer has expired.
  • the UE can continue the qualified RS resource detection after a backoff time. Both the applying of the backoff time and then the continuing of the qualified RS resource detection procedure after the backoff time can be repeated until at least one qualified RS resource is detected or the si-RandomAccessTimer timer expires.
  • the UE can select a random backoff time according to a uniform distribution between 0 and a constant provided by the network.
  • UE select one of the detected RS resources and the corresponding PRACH resource (s) associated with the selected RS resource for path-loss estimation and (re) transmission.
  • the above qualified RS resource detection behavior can be applied for each random access resource selection procedure during the random access procedure.
  • the si-RandomAccessTimer is stopped when the random access is considered successfully completed.
  • the network may provide dedicated RACH configuration associated with SS Blocks.
  • a contention free random access procedure can be performed, using the PRACH preamble and PRACH resource (s) indicted in the dedicated RACH configuration.
  • the random access is considered successfully completed.
  • a contention based random access can be performed. In this case, with the completion of the contention resolution, the random access is considered successfully completed.
  • the UE may also perform at least one of the following: (i) Initiate the connection re-establishment procedure; or (ii) if the SI request is triggered by the upper layer, inform the failure of SI acquisition to the corresponding upper layer that triggers the SI request.
  • FIG. 3 illustrates an exemplary reference signal resource selection procedure.
  • the user equipment can initiate a random access resource selection procedure.
  • the random access resource selection procedure is a sub-procedure within the random access procedure.
  • a user equipment can start a timer, for example, a ra-ResourceSelectionTimer, when a random access resource selection procedure is initiated.
  • a timer for example, a ra-ResourceSelectionTimer
  • the UE keep detecting a qualified RS resource.
  • the timer can be configured by the network and sent to the UE using, for example, system information or RRC signaling.
  • a time instance associated with the starting of the timer can be before or at the same time as the initiating of the random access resource selection procedure.
  • the exemplary timer may be started every time the random access resource selection procedure is initiated.
  • the timer can be stopped when performing the Random Access Preamble transmission procedure. In some embodiments, the timer is stopped when a qualified RS resource can be selected or detected by the user equipment.
  • the exemplary process of FIG. 3 can further implement features associated with the expiration of the timer.
  • the features from the following exemplary options can be implemented by a user equipment:
  • Exemplary Option 1 In this embodiment, if a user equipment determines that the timer has expired, the MAC entity can indicate random access problem to an upper layer, for example, a RRC layer. If the random access is performed on a Secondary Cell (SCell) and if the random access is not a random access trigger by beam failure, then the MAC entity can consider the random access procedure to be unsuccessfully completed.
  • SCell Secondary Cell
  • the indication of the random access problem or the unsuccessful completion of the random access procedure can be performed as discussed in the exemplary option 1 when the user equipment determines that no qualified RS resource is detected.
  • the features associated with exemplary option 1 can be performed in both a contention resolution and a contention-free process.
  • Exemplary Option 2 In this embodiment, if a user equipment determines that the timer has expired, the user equipment can increase the number of random access resource selection procedure by a predetermined value, such as 1, and if the user equipment determines that the number of the random access resource selection has not reached to a maximum number of random access resource selection procedure, then the MAC entity can consider that the random access resource selection procedure has failed and can initiate another random access resource selection procedure.
  • a predetermined value such as 1
  • the number of random access resource selection procedure can be set to 1 when a random access preamble transmission, such a random access attempt, is initiated.
  • the maximum number of random access resource selection procedure can be equal to a constant to control the maximum number of random access resource selection procedure plus 1. For example, if the constant is denoted as ra-ResourceSelection-Max, then the maximum number of random access resource selection procedure can be equal to ra-ResourceSelection-Max + 1. The following example further illustrates the relationship between the number of random access selection procedure and the maximum number of random access resource selection procedure in some embodiments.
  • the UE can perform a total of five random access resource selection procedures each time the timer expires.
  • the UE when the UE performs the fifth random access resource selection procedure (e.g., when the number of random access resource selection procedure reaches to 5) and the timer expires, then the UE increases the number of random access selection procedure to 6 and determines that the number of random access selection has reached to the maximum number of random access selection procedure (e.g., ra-ResourceSelection-Max + 1) .
  • the constant of ra-ResourceSelection-Max can be provided by the network.
  • the another random access resource selection procedure can be initiated immediately when the timer expires. In some other embodiments, the another random access resource selection procedure can be initiated after applying a backoff time when the timer expires. In some embodiments, if the timer is not configured or if the timer is configured with the timer length set to zero, the another random access resource selection procedure is initiated after a backoff time when the user equipment determines that no qualified RS resource is detected.
  • the MAC entity when a user equipment determines that the number of random access resource selection procedure reaches the maximum, the MAC entity indicate random access problem to upper layer (e.g. RRC layer) .
  • RRC layer e.g. RRC layer
  • exemplary option 2 if the timer is not configured or if the timer is configured with the length set to zero, then the determining of the number of the random access resource selection procedure compared to a maximum value, the considering of the failure of the random access resource selection procedure, and the initiating of another random access resource selection procedure can be performed as discussed in the exemplary option 2 when the user equipment determines that no qualified RS resource is detected.
  • the features associated with exemplary option 2 can be performed in both a contention resolution and a contention-free process.
  • Exemplary Option 3 In this embodiment, if a user equipment determines that the timer has expired, the MAC entity can consider that the random access resource selection procedure has failed, can indicate the random access resource selection failure to an upper layer, such as a RRC layer, and can initiate another random access resource selection procedure.
  • an upper layer such as a RRC layer
  • the another random access resource selection procedure can be initiated immediately when the timer expires. In some other embodiments, the another random access resource selection procedure can be initiated after applying a backoff time when the timer expires. In some embodiments, if the timer is not configured or if the timer is configured with the timer length set to zero, the another random access resource selection procedure is initiated after a backoff time when the user equipment determines that no qualified RS resource is detected.
  • the upper layer can declare a radio link failure if a certain number or a maximum number of random access resource selection failure indication is received by the upper layer, such as a RRC layer.
  • the MAC entity can consider that the random access resource selection procedure has failed, can indicate the random access resource selection failure to an upper layer, such as a RRC layer, and can initiate another random access resource selection procedure, as discussed in the exemplary option 3 when the user equipment determines that no qualified RS resource is detected.
  • the features associated with exemplary option 3 can be performed in both a contention resolution and a contention-free process.
  • Example 1 illustrates an example of a contention based random access for the features described for exemplary option 1 as described above.
  • Example 2 illustrates an example of a contention free random access for exemplary option 2 as described above.
  • any of exemplary options 1, 2, or 3 can be used for a contention or contention free based random access.
  • Example 1 a UE performs initial access from RRC_IDLE, and a contention based random access is initiated.
  • the UE performs random access according to the information acquired from the system information, such as the RACH configuration associated to SS blocks.
  • FIG. 4 illustrates an exemplary contention-based random access resource selection procedure using certain timer features of exemplary option 1.
  • a random access procedure can be initiated in MAC entity when the UE performs initial access from RRC_IDLE.
  • the MAC entity can initiate the random access resource selection procedure and can start a timer, for example, the ra-ResourceSelection timer.
  • the MAC entity determines whether a qualified RS resource is selected while the timer is running.
  • the UE performs qualified RS resource selection.
  • an example of the RS resource can include a SS block.
  • the UE can detect whether there is any SS block that satisfy the threshold provided in the system information in the first priority. If no SS block satisfies the threshold is detected, the UE can then detects whether there is any SS block that allows UE to meet the target received power of the RACH preamble with its maximum transmit power.
  • the actual behavior of performing RS resource selection can be left to UE to implement.
  • the UE select preamble and PRACH occasion associated with the selected RS resource and goes to the stopping operation 403.
  • the UE can keep on qualified RS resource detection until at least one qualified RS resource is detected or the ra-ResourceSelectionTimer expires. If the user equipment determines that the ra-ResourceSelectionTimer expires, then at the indicating operation 409, the MAC entity indicates random access problem to upper layer and the procedure ends.
  • UE select one of the detected RS resources and the corresponding PRACH resource (s) , including preamble and PRACH occasion, associated with the selected RS resource for path-loss estimation and (re) transmission.
  • the MAC entity can stop the ra-ResourceSelectionTimer.
  • the MAC entity can perform the random access preamble transmission procedure. In some embodiments, the performing operation 404 can be performed together or at the same time as the stopping operation 403. In some other embodiments, the performing operation 404 can be performed before the stopping operation 403.
  • the MAC entity can start to receive RAR within the RAR window. The length of the RAR window is acquired by the UE from the system information.
  • the process can continue with the transmitting operation 406. Or else, if a UE determines that a correct RAR corresponding to the preamble transmitted in the performing operation 404 is not received within the RAR window, then the MAC entity can add a predetermined value, such as 1, to the number of the random access preamble transmission, such as a number of random access attempt, and can determine whether the number of random access attempt, has reached a maximum number.
  • a predetermined value such as 1, to the number of the random access preamble transmission, such as a number of random access attempt, and can determine whether the number of random access attempt, has reached a maximum number.
  • the MAC entity can go back to the second initiating operation 401 to initiate another random access resource selection procedure and restart, for example, reset and start, the ra-ResourceSelectionTimer. If the UE determines that the number of the random access preamble transmission has reached the maximum number, then the MAC entity consider the random access unsuccessful and indicate the random access problem to upper layer and the procedure ends.
  • a Msg3 can be transmitted according to the UL grant acquired in the RAR.
  • the MAC entity can start to receive Msg4 which is transmitted by the network.
  • the MAC entity can determines whether the contention resolution is resolved. If a correct Msg4 corresponding to the Msg3 transmitted in transmitting operation 406 is successfully received, the contention resolution is considered resolved and UE goes to the completion operation 408. Or else, if no correct Msg4 is received within a contention_resolution time during, the MAC entity can add a predetermined value, such as 1, to the number of the random access preamble transmission, such as a number of random access attempt and can determines whether the number of random access attempt, has reached a maximum.
  • a predetermined value such as 1, to the number of the random access preamble transmission, such as a number of random access attempt and can determines whether the number of random access attempt, has reached a maximum.
  • the MAC entity can go back to the second initiating operation 401 to initiate another random access resource selection procedure and restart the ra-ResourceSelectionTimer . If the number of the random access preamble transmission has reached to the maximum number, the MAC entity consider the random access unsuccessful and indicate the random access problem to upper layer and the procedure ends.
  • the MAC entity At the completion operation 408, the MAC entity consider the random access successfully completed and the procedure ends.
  • a UE receives a handover command from the network, and a contention free RACH resources are provided in the handover command.
  • a contention free RACH resources are provided in the handover command.
  • dedicated RACH configuration associated to CSI-RS resources can be provided in the handover command.
  • the UE performs contention free random access according to the information acquired in the handover command.
  • FIG. 5 illustrates an exemplary contention free random access resource selection procedure using certain timer features of exemplary option 2.
  • a random access procedure can be initiated in MAC entity when the UE performs handover.
  • the MAC entity can set the number of random access resource selection procedure to be, for example, 1.
  • the MAC entity can initiate the random access resource selection procedure and starts the ra-ResourceSelection Timer.
  • the MAC entity can determine whether a qualified RS resource is selected.
  • the UE performs qualified RS resource selection.
  • an example of the RS resource can include a CSI-RS resource.
  • the UE can detect whether there is any CSI-RS resource that satisfy the threshold provided in the handover command in the first priority. If no CSI-RS resource satisfies the threshold is detected, the UE can then detects whether there is any CSI-RS resource that allows UE to meet the target received power of the RACH preamble with its maximum transmit power.
  • the actual behavior of performing RS resource selection can left to UE to implement.
  • the UE select preamble and PRACH occasion associated with the selected RS resource and goes to the stopping operation 503, where the MAC entity stops the ra-ResourceSelectionTimer.
  • the UE can keep on qualified RS resource detection until at least one qualified RS resource is detected or the ra-ResourceSelectionTimer expires. If the user equipment determines that the ra-ResourceSelectionTimer expires, then at the second determining operation 507, a predetermined value, such as 1, can be added to the number of random access resource selection procedure and the MAC entity determines whether the number of random access resource selection procedure has reached the maximum. If the number of random access resource selection procedure has reached the maximum value, then at the indicating operation 508, the MAC entity can indicate a random access problem to an upper layer and the procedure ends.
  • a predetermined value such as 1
  • the MAC entity initiates another random access resource selection procedure and restart, for example, reset and start, the ra-ResourceSelectionTimer.
  • the maximum value of the random access resource selection procedure can be equals to ra-ResourceSelection-Max + 1.
  • the ra-ResourceSelection-Max can be a constant provided by the network.
  • UE select one of the detected RS resources and the corresponding PRACH resource (s) (including preamble and PRACH occasion) associated with the selected RS resource for path-loss estimation and (re) transmission.
  • the MAC entity can perform the random access preamble transmission procedure.
  • the performing operation 504 can be performed together or at the same time as the stopping operation 503. In some other embodiments, the performing operation 504 can be performed before the stopping operation 503.
  • the MAC entity can start to receive RAR within the RAR window.
  • the length of the RAR window is provided in the handover command.
  • the MAC entity At the receiving operation 505, if a correct RAR corresponding to the preamble transmitted in performing operation 504 is successfully received within the RAR window, the MAC entity consider the random access procedure successfully completed and the procedure ends at operation 506. Or else, if a UE determines that a correct RAR corresponding to the preamble transmitted in the performing operation 504 is not received within the RAR window, then a predetermined value, such as 1, can be added to the number of random access preamble transmission, such as the number of random access attempt and the MAC entity determines whether the number of the random access preamble transmission has reached the maximum.
  • a predetermined value such as 1, can be added to the number of random access preamble transmission, such as the number of random access attempt and the MAC entity determines whether the number of the random access preamble transmission has reached the maximum.
  • the MAC entity can reset the number of random access resource selection procedure to, for example, 1, and can go back to the second initiating operation 501 to initiate another random access resource selection procedure and restart, for example, reset and start, the ra-ResourceSelectionTimer. If the number of the random access preamble transmission has reached to the maximum number, the MAC entity consider the random access unsuccessful and indicate the random access problem to upper layer and the procedure ends.
  • FIG. 6 shows a block diagram for an exemplary user equipment to implement the random access and timer features.
  • the user equipment includes one or more processors 610 that can reads code from the memory 605, and perform operations associated with the other blocks of the user device 600.
  • the user device includes a transmitter 615 that can transmit to a base station an access signal to initiate a random access procedure as described in this patent document.
  • the user device also includes a receiver 620 that can receive signals from the base station.
  • the module for random access 625 can initiate or perform the random access resource selection procedure or the random access procedure as described in this patent document.
  • the timer 630 can be used by the user equipment to start or stop the timer or to determine whether a timer is running or has expired, as further described in this patent document.
  • a computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM) , Random Access Memory (RAM) , compact discs (CDs) , digital versatile discs (DVD) , etc. Therefore, the computer-readable media can include a non-transitory storage media.
  • program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types.
  • Computer-or processor-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.
  • modules and blocks can be implemented as devices or modules using hardware circuits, software, or combinations thereof.
  • a hardware circuit implementation can include discrete analog and/or digital components that are, for example, integrated as part of a printed circuit board.
  • the disclosed components or modules can be implemented as an Application Specific Integrated Circuit (ASIC) and/or as a Field Programmable Gate Array (FPGA) device.
  • ASIC Application Specific Integrated Circuit
  • FPGA Field Programmable Gate Array
  • DSP digital signal processor
  • the various components or sub-components within each module may be implemented in software, hardware or firmware.
  • the connectivity between the modules and/or components within the modules may be provided using any one of the connectivity methods and media that is known in the art, including, but not limited to, communications over the Internet, wired, or wireless networks using the appropriate protocols.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

Selon la présente invention, un procédé de communication sans fil implémenté dans un équipement d'utilisateur peut démarrer un temporisateur et initier une procédure d'accès aléatoire. La procédure d'accès aléatoire est déclenchée en réponse à un événement de déclenchement d'accès aléatoire. En outre, une instance temporelle associée au démarrage du temporisateur dépend de l'événement de déclenchement d'accès aléatoire. Dans certains modes de réalisation, la procédure d'accès aléatoire peut être réalisée via la détection d'au moins un signal de référence (RS) pendant que le temporisateur fonctionne.
PCT/CN2018/072092 2018-01-10 2018-01-10 Techniques d'accès aléatoire dans des réseaux sans fil WO2019136631A1 (fr)

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CN201880080036.1A CN111466149A (zh) 2018-01-10 2018-01-10 无线网络中的随机接入技术

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CN114616885A (zh) * 2019-11-04 2022-06-10 苹果公司 辅小区的故障处理
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