Implicit drx cycle length adjustment control in lte_active mode

Implicit Control method and device for adjusting the length of the DRX cycle in LTE_Active mode

FIELD OF THE INVENTION

[001] The present invention is found in the field of wireless communications. BACKGROUND

[002] An objective of the Long Term Evolution (LTE) program of the Third Generation Partnership Project (3GPP) is the development of new technology, new architecture and new methods of adjustments and configurations in wireless communication systems, in order to to improve spectrum efficiency, reduce latency and better use radio capabilities to bring faster user experiences, richer applications and services to lower-cost users.

[003] In a typical LTE network, a wireless transmission and reception unit (WTRU) can operate in a number of modes. While in LTE_ACTIVE mode, the WTRU can operate in a discontinuous reception mode (DRX). DRX mode allows the WTRU to operate in low power, or automatic shutdown mode for a predetermined time, and then switch to a full power mode, or awake, for a previously defined time in order to reduce the battery consumption. The lengths of XRD cycles are generally configured by the enhanced universal terrestrial radio access network (E-UTRAN), in such a way that an enhanced B-Node (eNB) and the WTRU are synchronized in a consistent cycle of turning off and waking up.

[004] Live traffic situations and WTRU mobility may require frequent adjustments of the DRX cycle period in order to balance system performance, WTRU performance and WTRU energy savings. Relying only on the WTRU / E-UTRAN signaling to perform the fine DRX cycle adjustment may, however, incur a heavy system and signaling load from the WTRU.

[005] Implicit rules for adjusting the XRD cycle length can be used for smooth LTE_ACTIVE XRD operations to reduce battery power consumption without affecting WTRU or system performance issues. Implicit rules can assist the implicit DRX cycle length transitions between the WTRU and the

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E-UTRAN without the use of excessive explicit signage.

[006] EP 1 613 107 A2 refers to a rest / sleep cycle of a mobile station, the sleep cycle of which may vary depending on one or more conditions related to the operation of the mobile station. Based on one or more of these conditions, a variable activation parameter is determined and used to establish the times when the mobile station automatically exits low energy mode and enters high energy mode to listen to content.

[007] EP 1 511 337 A1 describes a method of periodically intermittent activation of the receiving circuits of a mobile user terminal, in order to hear a paging channel. The period is selected depending on the time or hour of the day or what services are provided on the last call connection to the user's mobile terminal.

[008] EP 1 499 144 A1 describes the change of a first discontinuous reception cycle from a mobile communication terminal to a second discontinuous reception cycle, the second discontinuous reception cycle of which is greater than the first discontinuous reception cycle, in response to the determination that a measured stability of the quality of a detected reception exceeds a threshold value.

SUMMARY OF THE INVENTION

[009] A method and apparatus for controlling discontinuous reception in a WTRU are described. The method may include the definition of a series of XRD levels, where each XRD level includes a corresponding XRD cycle length and transition between the XRD levels based on a set of criteria. The transition can be triggered by implicit rules. The drive can be invoked by a measurement event, timer, counter or lower link command, for example. Transitions between states of XRD can occur without explicit signaling.

BRIEF DESCRIPTION OF THE FIGURES

[0010] A more detailed understanding can be obtained from the description below, provided as an example and to be understood together with the attached Figures, in which:

figure 1 shows a wireless communication system according to an embodiment;

Petition 870190118457, of 11/14/2019, p. 13/33 figure 2 is a functional block diagram of a WTRU and an eNode B (eNB) according to one embodiment;

figure 3 is an implicit XRD transition state diagram according to one embodiment;

figure 4 is a signal flow chart for implicit XRD transition according to an embodiment;

figure 5 is a flow chart of one according to one embodiment;

figure 6 is a flow chart of one according to another embodiment;

figure 7 is a flowchart of one according to an alternative embodiment; and

figure 8 is a flow chart of one according to another alternative embodiment.

DETAILED DESCRIPTION DRX implicit signaling method DRX implicit signaling method DRX implicit signaling method DRX implicit signaling method

[0011] When indicated below, the terminology wireless transmission and reception unit (WTRU) includes, but is not limited to, user equipment (UE), mobile station (STA), fixed or mobile subscriber unit, pager , cell phone, personal digital assistant (PDA), computer or any other type of user device capable of operating in a wireless environment. When indicated below, the base station terminology includes, but is not limited to, a Node B, location controller, access point (AP) or any other type of interface device capable of operating in a wireless environment. [0012] Figure 1 shows a wireless communication system 100 as an embodiment. System 100 includes a series of WTRUs 110 and an eNB 120. As shown in figure 1, WTRUs 110 are in communication with eNB 120. Although three WTRUs 110 and one eNB 120 are shown in figure 1, it should be noted that any combination of wired and wireless devices can be included in the wireless communication system 100. The eNB 120 and WTRUs 110 can communicate up while in DRX mode and can have coordinated DRX cycles.

[0013] Figure 2 is a functional block diagram 200 of a WTRU 110 and the eNB

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120 of the wireless communication system 100 in figure 1. As shown in figure 1, the WTRU 110 is in communication with the eNB 120. The WTRU 110 and eNB 120 can operate in DRX mode.

[0014] In addition to the components that can be found in a typical WTRU, the WTRU 110 includes a processor 215, a receiver 216, a transmitter 217 and an antenna 218. Processor 215 can be configured to adjust the length of the DRX cycle as the necessary. Receiver 216 and transmitter 217 are in communication with processor 215. Antenna 218 is in communication with receiver 216 and transmitter 217 to facilitate wireless data transmission and reception.

[0015] In addition to the components that can be found in a typical eNB 120, the eNB 120 includes a processor 225, a receiver 226, a transmitter 227 and an antenna 228. Processor 225 is configured to communicate with receiver 226 and transmitter 227 to adjust DRX cycles as needed. Receiver 226 and transmitter 227 are in communication with processor 225. Antenna 228 is in communication with receiver 226 and transmitter 227 to facilitate wireless data transmission and reception.

[0016] In order to increase the battery life, but without limiting the performance of the eNB and WTRU 110, transitions between DRX cycle length states can be defined implicitly and not explicitly. The implicit rules can be implemented at the radio resource control (RRC) and media access control (MAC) levels while the WTRU 110 is in an LTE_ATIVO DRX state.

[0017] About half of the interaction from WTRU 110 to eNB 120 involves requests and reports from WTRU 110 and responses from eNB 110 while WTRU 110 is in LTE_ACTIVE DRX mode. When WTRU 110 measures a specific scenario, measurement events can be reported to eNB 120 and eNB 120 can respond to the situation by ordering WTRU 110 to start a new service, mobility activity and the like. If the transmission or reception of a lower link command is limited by a relatively long DRX cycle length, the system performance of the WTRU 110 and eNB 120 during LTE_ACTIVE DRX mode may be impaired. Certain measurement events

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5/14 can, however, be good candidates for the anticipated network lower link commands.

[0018] Figure 3 shows an DRX 300 implicit transition state machine as an embodiment. The state machine 300, as well as transition mechanisms and associated parameter values, can be configured by eNB (120 in figure 1). The state machine 300 can have a life span also configured by eNB 120. Each state can be applied to the WTRU (110 in figure 1) and eNB 120, so that the operation is consistent and synchronized. In each defined and configured DRX state, a different DRX cycle length is associated with the operations of the WTRU 110 and eNB 120.

[0019] The XRD cycle length transition rules can be based on experiences from WTRU 110 and eNB 120. Given a certain period of time or a given set of measurement values, WTRU 110 and eNB 120 can learn and predict traffic patterns. These learned and predicted traffic patterns can be superimposed on a general model for a state machine, which results in the DRX 300 state machine for a WTRU 110 and eNB 120 system that allows the implicit transition operation and consistent DRX actions for WTRU 110 and eNB 120. eNB 120 can prescribe XRD states for service and mobility conditions with the potential for continuous improvement and traffic patterns learned through each invocation.

[0020] Figure 3 shows three defined DRX levels, 302, 304, 306 and one undefined DRX level 308. At DRX level 3 306, WTRU 110 operates in a normal DRX cycle. The actual length of the normal state can be defined by eNB 120. The DRX level 2 304 is a shorter cycle length than the DRX level 3 306 and is associated with more frequent activity than normal. The eNB 120 can also define the cycle length for the DRX level 2 304 and can also define a resumption period. A resume period is a period of time when there are no new transmissions and, after which, the WTRU 110 can return to DRX 3 level operation 306, unless the WTRU 110 is ordered to do something else.

[0021] The DRX level 1 302 has the shortest DRX cycle length and can be used by a WTRU 110 or eNB 120 to handle lower link commands

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6/14 predicted and when the upper link traffic patterns are recognized by the WTRU 110 and eNB 120 as requiring immediate lower link action, such as during a delivery event, for example.

[0022] An XRD level 308 can be configured with XRD cycles longer than that of the XRD level 3 306. The eNB 120 can redefine the XRD cycle lengths for each state at the end of the lifetime of the XRD configuration. DRX, but you can observe a DRX cycle length rule that lower level DRX states have shorter DRX lengths.

[0023] For a WTRU 110 at DRX level 3 306, a timer or counter trigger can be set to trigger a transition to DRX Level 2 304 if eNB 120 determines that WTRU 110 should periodically transition to a busy cycle to check lower link data. This can be considered a trigger based on a measurement event. Another trigger based on a measurement event can also be defined to transition a WTRU 110 from DRX Level 3 306 to DRX Level 1 when a traffic volume event on a certain radio carrier is reported accumulating a greater amount of higher link data than a threshold and an anticipated Radio Carrier Reconfiguration (RB) command is imminent.

[0024] If the WTRU 110 in the DRX Level 1 state 302 receives an RB Reset command, the current DRX Level 1 state has ended. If the WTRU 110 in the DRX Level 1 302 state does not receive the command in advance for the defined resume period, it can return to its original DRX state and resume the energy-saving DRX cycle. Regular timers and counters can be used during a DRX mode to trigger the implicit DRX cycle length transition. The selection between timers and counters and the values ​​of timers or counters can be based on patterns and traffic patterns learned with respect to the mobility and / or service status of the WTRU 110 at a specific time, while the WTRU 110 is in DRX mode LTE_ACTIVE. Timer or counter triggers can be used as transition triggers to increase the length of the DRX cycle, as well as reduce the length

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7/14 of the XRD cycle as the XRD state changes.

[0025] eNB 120 can configure DRX parameters based on an analysis and operation of network traffic monitoring. There are several methods for selecting parameter values, such as by including a set of standard system values ​​that is defined for the operation of the implicit DRX transition. Optionally, parameters can be published in system information transmissions or can be determined by eNB 120 periodically and loaded into a specific WTRU 110 by signaling upper layers before a desired DRX mode period.

[0026] Transitions between different states can be signaled in an information element. An example of an implicit DRX cycle transition signaling skeleton is shown in Table 1. As shown in Table 1, the Implicit DRX Transition List is mandatory and limited to a value that indicates a maximum number of DRX states.

[0027] The DRX cycle length IE is mandatory and is an integer. The triggering mechanisms are optional and can be a trigger for raising an XRD state level or moving an XRD state level down. The Lifetime IE configured by the Implicit DRX Transition is mandatory and defines the resumption period for abnormal states. The initial DRX status is optional and you can define the DRX status of the WTRU 110 at startup.

[0028] To assist in the easier transition of DRX cycle length and to maintain the synchronization of DRX cycle lengths between WTRU 110 and eNB 120, the definition of DRX cycle length can be provided depending on the base number Shorter XRD (L). Thus, the various XRD length values ​​can be: XRD cycle length = L x 2n Equation (1) where n = 0, 1, 2, ..., such that the resulting XRD cycle length do not exceed a maximum DRX cycle length. The shortest possible XRD cycle length occurs when n = 0 and is a fraction of a longest XRD cycle length.

[0029] The use of XRD cycle lengths that are multiple of each other reduces the

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8/14 probability that the XRD periods may be mismatched and provides an efficient mechanism for resynchronizing XRD periods between the WTRU 110 and the eNB 120. When XRD periods are defined as multiple of each other and when XRD periods are not coincident between WTRU 110 and eNB 120, each entity can determine the period of the other by increasing or decreasing the cycle length to determine the period being used by the other entity and resynchronize the entities accordingly.

[0030] Typically, a WTRU 110 at DRX Level 1 302 can count n times before transitioning back to the original DRX state. The standard can be provided as: n = (level X DRX cycle length or original DRX cycle length) / level 1 DRX cycle length;

where the length of the k-level cycle is the length of the DRX cycle before the WTRU 110 enters DRX Level 1 302. Alternatively, the network can configure n for the resume method.

Table 1

<td>Group name / information element</td><td>Need</td><td>Multi</td><td>Type and reference</td><td>Semantic description</td>

<td>Implied transition list of XRD</td><td>MP</td><td>Maximum XRD (TBD) states</td><td></td><td></td>

<td>&gt; XRD cycle length</td><td>MP</td><td></td><td>Number whole (TBD)</td><td></td>

<td>&gt; Trigger up 1</td><td>OP</td><td></td><td>Trigger mechanism A B C D</td><td>For the next top-level XRD state</td>

<td>&gt; Trigger up 2</td><td>OP</td><td></td><td>Trigger mechanism A B C D</td><td>Used by Level 1 to resume</td>

<td>&gt; Trigger for</td><td>OP</td><td></td><td>Trigger mechanism</td><td>To the next state</td>

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<td>low 1</td><td></td><td></td><td>A B C D</td><td>low-level XRD</td>

<td>&gt; Down trigger 2</td><td>OP</td><td></td><td>Trigger mechanism A B C D</td><td>For the Level 1</td>

<td>Lifetime configured for implicit XRD transition</td><td>MP</td><td></td><td>TBD</td><td>Time in seconds</td>

<td>Initial XRD status</td><td>OP</td><td></td><td>TBD</td><td></td>

[0031] Transitions from one state to another can be initiated by a trigger. Table 2 shows an example of these transition triggers. Each of the lEs is mandatory, except for the resumption period. The Transition Trigger is mandatory and is specified by the network if specified as shown in Table 1. The SELECT mechanism allows the network to configure the WTRU 110 for DRX implicit operational triggers. The Timer Value trigger can be presented in absolute time units, LTE frames or transmission time intervals (TTIs) and is used to monitor or regulate ON and OFF periods for network signaling channel activities or channel activities data for WTRU 110. Counter values ​​can be an integer value used to check for occurrences of certain triggering events. The measurement event can enumerate the event that causes the trigger. The resume period can be a period of time provided in seconds, XRD cycles or some other value that indicates the total time that a WTRU 110 can remain in an elevated state without receiving a command to move back to the state normal.

Table 2

<td>Group name / information element</td><td>Need</td><td>Multi</td><td>Type and reference</td><td>Semantic description</td>

<td>Trigger</td><td>MP</td><td></td><td></td><td></td>

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<td>transition</td><td></td><td></td><td></td><td></td>

<td>Mechanism SELECTION</td><td>MP</td><td></td><td></td><td></td>

<td>&gt; Timer</td><td></td><td></td><td></td><td></td>

<td>»Timer value</td><td>MP</td><td></td><td>Whole TBD</td><td></td>

<td>&gt; Accountant</td><td></td><td></td><td></td><td></td>

<td>»Counts</td><td>MP</td><td></td><td>Whole TBD</td><td></td>

<td>&gt; Measurement event</td><td></td><td></td><td></td><td></td>

<td>»Measurement event ID</td><td>MP</td><td></td><td>Enumerated (TBD)</td><td></td>

<td>&gt; Period of resumption</td><td>Upward drive 2</td><td></td><td>TBD</td><td>It can be standard in level 1 state. The standard is that Level 1 cycles remain, so that the total length is equivalent to your original DRX state DRX length.</td>

[0032] Figure 4 is a flow chart of DRX 400 implicit transition signal as an embodiment. A WTRU 402 can receive an RRC or IE 406 message from EUTRAN 404 that triggers the WTRU 402 to enter DRX mode. The WTRU 402 can enter DRX 408 mode at a standard level which can be a normal cycle length DRX level 3 (306 of figure 3). WTRU 402 and E-UTRAN 404 enter DRX mode (408, 410, respectively). The WTRU 402 can receive another RRC or IE 412 message that triggers the WTRU 402 to enter a faster DRX cycle mode (DRX level 1 302 in figure 3). The WTRU 402 and E-UTRAN 404 enter the DRX 1 level (414, 416, respectively). A WTRU 418 timer, synchronized with an E-UTRAN timer (not shown), ends. Since the timers are synchronized, there is no need to terminate the timer. The end of timer 418 triggers WTRU 402 and E-UTRAN 404 to return to the

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11/14 normal XRD level. The WTRU 402 returns 422 to the DRX 3 306 level at the same time as the E-UTRAN 404 returns 424 to the DRX 3 306 level.

[0033] Figure 5 is a flow chart of an implicit signaling method 500 as an embodiment. In step 502, the WTRU is in normal operating mode, or Level 3. In step 504, the WTRU checks whether the timer has ended or if a trigger has been received that would force the WTRU to move to another DRX state. . Otherwise, in step 506, the WTRU remains in the normal state. If the WTRU detects an end timer or trigger signal in step 504, in step 508, the WTRU determines whether to move to DRX level 1 or DRX level 2. If the WTRU determines that the trigger is a trigger from level 2, in step 510, the WTRU moves to DRX Level 2. In step 512, the WTRU determines that the resumption period has ended and returns to DRX level 3. If, however, the WTRU, in step 508, determines that it has received a level 1 trigger, in step 514, the WTRU moves to DRX level 1. In step 516, the WTRU determines whether it has received a Carrier Reset message Radio. Otherwise, the WTRU, in step 518, waits for the resumption period to end and returns to normal operation in step 522. If, however, in step 518, the WTRU receives a radio carrier reset message, in step 520, the WTRU returns to normal DRX cycle operation.

[0034] Figure 6 is a flow diagram of an implicit DRX 600 method according to another embodiment. In step 602, the WTRU is in normal mode or DRX Level 3. In step 604, the WTRU conducts a traffic volume measurement. In step 606, the WTRU compares the measurement of traffic volume with a threshold. If the volume is below the limit, in step 608, the WTRU takes no action and remains in DRX Level 3 mode. If, in step 606, the WTRU determines that the traffic is above a limit, however, in step 610, the WTRU changes its mode to a shorter DRX cycle. Based on traffic, the new DRX mode can be either DRX level 2 or DRX level 1. In step 612, the WTRU determines whether a command or message has been received. If so, in step 614, the WTRU returns to Level 3 mode. Otherwise, the WTRU, in step 616, waits for the recovery period before returning to

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12/14 the level 3 mode in step 618. Optionally, the E-UTRAN can determine the limit level of report of measurement of traffic volume for triggering state transition of DRX. When the defined traffic volume measurement event occurs, the DRX state transition is triggered.

[0035] While in LTE_ACTIVE DRX mode, a WTRU can perform traffic volume measurements for higher link traffic. E-UTRAN can configure the WTRU to report events about crossing limits. Based on the learned traffic patterns, E-UTRAN determines that there is a major change in volume, which may mean that a command to add RB, reconfigure RB or release RB is imminent. Traffic volume event reporting can therefore be used as an implicit DRX transition driver. A large change in volume can be used, for example, to trigger the WTRU in the smallest DRX cycle (DRX level 1, 302 in figure 3, for example), in order to receive the network command. The network, upon receiving the predetermined measurement event, can determine the DRX status of the WTRU using implicit DRX transition rules and either send the advance command to the WTRU or wait for the WTRU to return to its previous DRX state with the specified resume period.

[0036] As a form of another example, the WTRU, while in LTE_ACTIVE mode, can use configured delivery measurements. Certain measurement event reports may indicate that a delivery command (HO) is imminent for delivery between inter-radio access technology (RAT), inter-frequency or intra-frequency. Depending on delivery measurement events, certain different measurement events can act as triggers for XRD transition control. Figure 7 is a flow diagram of an DRX 700 implicit signaling method according to an alternative embodiment. In step 702, the WTRU is in the normal DRX 3 level state. In step 704, the WTRU determines that a measurement of cells in service is below a threshold. The WTRU can then determine that a measurement between frequencies is high 706, which indicates that an intra-frequency neighbor is measuring as the best cell. Alternatively, the WTRU may determine that an inter-frequency band measures as the best 708. As another alternative, the WTRU may determine that a

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13/14 non-LTE system measures the best 710.

[0037] In step 712, the WTRU, due to the measurements, can anticipate a delivery command. In step 714, the WTRU reports the measurement event. It can invoke, in step 716, an implicit DRX transition trigger that causes the WTRU to enter a DRX level 1 state in order to receive the possible delivery command from the network. In step 718, the WTRU receives the delivery command. In step 720, the WTRU transitions back to its original DRX state.

[0038] Figure 8 is a flowchart of an implicit DRX 800 cycle signaling method as yet another embodiment. In step 802, the WTRU is in level 1 mode. In step 804, the WTRU starts monitoring a Level 1 / Level 2 control channel to intercept anticipated lower link commands. In step 806, the WTRU determines whether an early network command is received. If received, in step 808, the WTRU will follow the command to end DRX mode or receive instruction on the next DRX activity with the command. If the command is not received, in step 810, the WTRU transitions back to its original DRX state before entering the Level 1 state.

[0039] Although the characteristics and elements are described in the realizations in specific combinations, each characteristic or element can be used alone, without the other characteristics and elements or in various combinations with or without other characteristics and elements. The methods or flowcharts provided can be implemented in a computer program, software or firmware in tangible realization on a computer-readable storage medium for execution by a general purpose computer or processor. Examples of computer-readable storage media include read-only memory (ROM), random access memory (RAM), registry, cache memory, semiconductor memory devices, magnetic media such as internal hard drives and removable disks, magnet media. optical and optical media such as CD-ROM discs and digital versatile discs (DVDs).

[0040] Appropriate processors include, for example, a general purpose processor, special purpose processor, conventional processor, digital signal processor (DSP), a series of microprocessors, one or more microprocessors in

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14/14 association with a DSP core, controller, microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Portal Sets (FPGAs), any other type of integrated circuit (IC) and / or state machine .

[0041] A processor in association with software can be used to implement a radio frequency transceiver for use in a wireless transmission and reception unit (WTRU), user equipment (UE), terminal, base station, network controller, radio (RNC) or any host computer. The WTRU can be used in conjunction with modules, implemented in hardware and / or software, such as a camera, video camera module, videophone, headset, vibrating device, speaker, microphone, television transceiver, headset handsfree headset, keyboard, Bluetooth® module, frequency modulated radio (FM) unit, liquid crystal display (LCD) unit, organic light-emitting diode (OLED) unit, digital music device, media player, video game module, Internet browser and / or any wireless local area network (WLAN) module.