JP2009077287A - User device, base station device and method used in mobile communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely give a user device a chance to measure a different frequency. <P>SOLUTION: The user device in a mobile communication system has a means of receiving a down control signal at the frequency of an in-zone cell and a means of making a cell search at a frequency different from the frequency of the in-zone cell in intervals of the reception timing of the down control signal in response to occurrence of a predetermined event for different frequency measurement. When a reception timing interval of the down control signal is shorter than a threshold reported from a base station device and the predetermined event for different frequency measurement occurs, different frequency measurement is carried out in a period, different from, the reception timing interval, reported from the base station device. Or when a different frequency measurement indicator specified by the base station device indicates a predetermined value, different frequency measurement is carried out in timing determined with a device of its own in response to occurrence of the predetermined event and when the different frequency indicator indicates another predetermined value, different frequency measurement is carried out in timing, different from an intermittent reception period, specified by the base station device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a user apparatus, a base station apparatus and a method used in a mobile communication system.

  In this type of technical field, it has been proposed to enable handover of a plurality of radio access networks or mobile communication systems using the same or different radio access technologies (RAT). For example, during a call on a certain radio access network, a certain user apparatus may be handed over to another radio access network having a different frequency according to the propagation status or load status and continue the call. By doing so, when a certain wireless access network is congested, the load on the network can be distributed, and the accommodation number, throughput, and the like in the entire system can be improved.

FIG. 1 shows how handover between such homogeneous or heterogeneous RATs is performed. In the example shown in the figure, a third generation system (3G-RAT) including a radio access network of the first frequency f _{1 and} a radio access network of the second frequency f ₂ and a third frequency f ₃ are used separately from them. A second-generation system (2G-RAT) coexists in a similar geographical area. The 2G-RAT may include a system such as GSM or PDC. In the illustrated example, the user apparatus UE that has finished the call at the first frequency f ₁ enters a standby operation at the second frequency f ₂ or at 2G-RAT. A handover may be performed between a long term evolution (LTE) system and a UMTS system.

Non-patent documents 1 and 2 describe, for example, handover between the same type or different types of RATs.
3GPP, TS25.331 3GPP, TS25.304

  In order to perform handover to a cell with a different frequency and / or different RAT, it is necessary to perform a different frequency measurement including a cell search for the different frequency and / or different RAT before the handover. The term “different frequency measurement” in the present application is a concept including cell search at different frequencies and cell search at different RATs.

  Since the different frequency measurement is related to mobility control, it is desirable that the different frequency measurement is performed not only once but also a plurality of times periodically so that the instantaneous fluctuation component can be sufficiently averaged. Therefore, when the user apparatus enters the intermittent reception (DRX) mode and an event of different frequency measurement occurs, the user apparatus performs different frequency measurement between intermittent reception timings. In the different frequency measurement, it is necessary to tune to a frequency different from the frequency of the serving cell, perform cell search, acquire the synchronization channel, measure the reception level, etc., and tune to the frequency of the serving cell again. Become. Therefore, it is desirable that the intermittent reception period is long enough to do so (for example, 5 ms or more).

  On the other hand, the intermittent reception cycle is set mainly from the viewpoint of battery saving of the user apparatus. For example, when data to be transmitted / received does not exist for a certain time or longer, DRX can be performed to save the battery. For example, in a system such as UMTS, DRX is applied to paging channel reception in an idle state (standby state). However, in LTE, in the active state where the base station has the context of the user equipment and the radio bearer is set up Is also being considered to apply. By applying DRX while active, data transmission / reception can be resumed without requiring signaling with an upper node, and data transfer delay can be reduced. On the other hand, battery saving can be performed as long as the receiver is rested by DRX.

  Therefore, the intermittent reception period performed by the user apparatus may not be long enough to perform the different frequency measurement. When the intermittent reception cycle is short, it is not possible to sufficiently perform different frequency measurement, and handover to a different frequency cell becomes difficult, and there is a concern that it adversely affects data throughput, system capacity, and the like.

  An object of the present invention is to reliably give a user device an opportunity to measure different frequencies.

  In the present invention, a user apparatus in a mobile communication system is used. The user apparatus receives the downlink control signal in response to the means for receiving the downlink control signal at the frequency of the serving cell and the occurrence of a predetermined event for different frequency measurement in the user apparatus or the base station apparatus. Means for performing a cell search at a frequency different from the frequency of the serving cell between timings. The base station apparatus different from the reception timing interval when a predetermined event for different frequency measurement occurs according to a comparison result between the reception timing interval of the downlink control signal and the threshold value notified from the base station apparatus It is determined whether or not the different frequency measurement is performed with the period notified from.

  Alternatively, when the different frequency measurement indicator designated by the base station device indicates a predetermined value, when the predetermined event occurs, the different frequency measurement is performed at a timing determined by the own device, and the different frequency measurement indicator is separated. When the predetermined value is indicated, the different frequency measurement may be performed at a timing specified by the base station apparatus different from the intermittent reception cycle.

  ADVANTAGE OF THE INVENTION According to this invention, the opportunity of different frequency measurement can be given to a user apparatus reliably.

  For convenience of explanation, the present invention is described in several embodiments. However, the division of each embodiment is not essential to the present invention, and two or more embodiments may be used as necessary.

  FIG. 2 is a schematic block diagram of the base station apparatus 10 used in the embodiment of the present invention. In FIG. 2, a reception RF unit 101, a measurement unit 102, a control information generation unit 103, an RRC processing unit 105, a broadcast information generation unit 107, a scheduler 108, and a transmission RF unit 109 are depicted.

  The reception RF unit 101 performs processing such as power amplification, band limitation, frequency conversion, analog-digital conversion, and demodulation on a signal received via an antenna and a duplexer.

  The measurement unit 102 measures uplink quality based on a sounding reference signal reported from the user apparatus. Signal quality is measured using desired signal power vs. interference signal power (SIR, SINR, etc.), reference signal received power (RSRP: Reference Signal Received Power), channel quality indicator (CQI: Channel Quality Indicator), path loss, etc. Good. The averaging of the quality measurement value is performed to such an extent that shadowing, distance attenuation, etc. are followed, although the influence of instantaneous fading is removed.

  The control information generation unit 103 creates information on the L1 / L2 control channel (PDCCH: Physical Downlink Control CHannel) according to the allocation result of the scheduler 108.

  The RRC processing unit 105 performs processing related to radio resource control (RRC). The RRC processing unit 105 monitors the occurrence of a predetermined event, creates a measurement control, creates a gap control signal (described later), creates a gap stop signal (described later), and performs it on the user device. Managing the threshold related to the intermittent reception cycle, managing DRX parameters such as the intermittent reception cycle executed in the user device (the DRX parameter may include the above threshold), managing the operation mode of the user device, Performs processing such as L3 control. A predetermined event is performed by comparing a measured value based on a received signal or a value reported from a user device with a predetermined threshold value, and confirming that those values are above or below the threshold value. It is common.

  The broadcast information generation unit 107 creates a broadcast channel (BCH) including information to be broadcast to the user equipment in the serving cell.

  The scheduler 108 schedules allocation of radio resources to user equipment.

  The transmission RF section 109 creates a downlink signal including a broadcast channel BCH, a control channel PDCCH, a downlink physical shared channel (PDSCH), and the like. The downlink signal is transmitted through the duplexer and the antenna through various processes in the transmission RF unit 109. Such processing includes processing such as digital-analog conversion, modulation, frequency conversion, band limitation, and power amplification.

  FIG. 3 shows a schematic block diagram of the user equipment 20 used in one embodiment of the present invention. In FIG. 3, a reception RF unit 201, an L1 / L2 processing unit 203, an RRC processing unit 205, a control unit 207, a measurement unit 209, and a transmission RF unit 211 are depicted.

  The reception RF unit 201 appropriately processes a radio reception signal, and extracts a reference signal (pilot signal), a broadcast channel, a control signal (PDCCH L1 / L2 control signal), a data signal, and the like. In order to simplify the illustration, functional elements relating to the data signal are omitted. In the intermittent reception mode, the reception RF unit 201 receives a control signal at intermittent reception timing. The intermittent reception information (DRX information) such as intermittent reception timing, intermittent period, intermittent reception period, and duty ratio may be determined in advance by the system or may be notified from the base station apparatus. The intermittent reception parameter is received by the L1 / L2 processing unit 203 (when the intermittent reception parameter is controlled by the MAC control PDU) or the RRC processing unit 205 (when controlled by the RRC message), and matches the value indicated by the parameter. Start and stop timings are set.

  The L1 / L2 processing unit 203 demodulates a low layer control signal (PDCCH L1 / L2 control signal) related to the physical layer, and allocates radio resource information and high layer control information (L3 control message, RRC measurement control message). Then, acknowledgment information (ACK / NACK) of the uplink data signal transmitted in the past is extracted. The L1 / L2 processing unit 203 may be called a MAC processing unit. In addition, retransmission control such as RLC and PDCP, falsification detection processing, and confidential processing may be included.

  The RRC processing unit 205 extracts information related to radio resource control (RRC). The RRC processing unit 205 is necessary for operations such as new establishment, re-establishment, maintenance and release of an RRC connection, radio bearer establishment, change, release, radio resource allocation, active and idle operation mode management, connection movement management, etc. Extract and prepare various information. For example, the RRC processing unit 205 prepares an RRC connection request signal according to a call (incoming call) on the paging channel or a user's call operation. In addition, after receiving the RRC release signal indicating the release of the connection, an RRC release complete signal corresponding thereto is prepared. In addition, the measurement necessary for the lower layer is set according to the measurement control signal designated by the base station apparatus, and a measurement report signal is prepared when an event to be reported to the base station apparatus occurs.

  The control unit 207 controls the operation of each functional element based on various information notified from the RRC processing unit 205.

  The measurement unit 209 performs cell search at a specified frequency. The specified frequency is not only the frequency used in the serving cell, but may be a different frequency. In cell search, the reception quality of reference signals from neighboring cells is measured. The different frequency measurement is performed when an event for different frequency measurement occurs in the intermittent reception timing interval of the control signal.

  The transmission RF unit 211 creates an uplink signal including an uplink control signal (PUCCH: Physical Uplink Control CHannel), an uplink shared data channel (PUSCH: Physical Uplink Shared Channel), and the like. The uplink signal is transmitted through the duplexer and the antenna through various processes in the transmission RF unit 211. Such processing includes processing such as digital-analog conversion, modulation, frequency conversion, band limitation, and power amplification.

  Among various processes performed by the RRC processing unit 205 and the measurement unit 209, as particularly related to the present invention, the instantaneous quality of the downlink reference signal is measured, and a plurality of instantaneous quality measurement values are averaged. And detection of occurrence of a predetermined event, and processing according to a comparison result between a threshold related to the intermittent reception cycle and the intermittent reception cycle currently set in the own device (described later).

  The signal quality may be measured using desired signal power versus interference signal power (SIR, SINR, etc.), reference signal received power (RSRP), channel quality indicator (CQI), path loss, and the like. The averaging of the quality measurement value is performed to such an extent that it follows shadowing and the like, although the influence of instantaneous fading is removed. The predetermined event is performed by comparing the measured value based on the received signal with a predetermined threshold value and confirming that those values are above or below the threshold value.

  FIG. 4 shows a timing chart (part 1) for explaining an operation example of the present invention. The user apparatus receives the control signal intermittently in the idle mode as well as the control signal intermittently according to the data activity even in the active mode. The user apparatus performs different frequency measurement as necessary between reception timings of the control signals (PDCCH downlink L1 / L2 control signals). The different frequency measurement is performed in response to the occurrence of a predetermined event, tuned to a frequency different from the frequency of the serving cell, performs a cell search, acquires a synchronization channel, measures the reception level, etc. Again tune to the frequency of the serving cell. Thereby, it is confirmed whether or not there is a different frequency cell that can be connected in the vicinity of the serving cell.

  In the mobile communication system according to the present embodiment, depending on whether the reception timing interval (DRX cycle) of the control signal in the user apparatus is longer than a threshold value (DRX threshold) specified by the base station apparatus, the DRX cycle is Used as is or modified. The example shown in FIG. 4 shows an operation example when the DRX cycle of the user apparatus is longer than the DRX threshold (the case where it is not long will be described in FIG. 5). As an example, the DRX threshold is 10 ms, and the DRX cycle in FIG. 4 is 100 ms. Information indicating the value of the DRX threshold and how the event for different frequency measurement should be determined is based on, for example, the measurement control message of the RRC protocol layer transmitted on the broadcast channel or the dedicated channel by the base station The device notifies the user device.

  FIG. 4 shows nine activation timings of the user equipment in order, and the time interval between the activation timings is the intermittent transmission period (DTX period) of the control signal from the base station apparatus or the intermittent reception of the control signal at the user apparatus. It corresponds to the period (DRX period). At each activation timing, the user apparatus checks whether or not an event of different frequency measurement has occurred. Such an event does not occur at the first and second activation timings. However, an event for different frequency measurement occurs between the second and third activation timings, and the user apparatus starts the different frequency measurement accordingly. The different frequency measurement is performed between activation timings. Further, when an event for stopping the different frequency measurement occurs, the user apparatus stops measuring the different frequency during the intermittent reception period. In FIG. 4, such an event occurs between the seventh and eighth activation timings, and the user apparatus stops the different frequency measurement. Events for starting or stopping different frequency measurement include, for example, the desired signal power ratio of the downlink reference signal to the undesired signal power (RS-SIR, etc.), the received power of the downlink reference signal (RS-RP), and the average value of CQI Or you may determine by the comparison result of a path loss and a predetermined threshold value. As an example, the different frequency measurement may be started in response to the SIR (RS-SIR) of the reference signal in the serving cell being lower than the threshold value. This is likely to occur when the user equipment approaches the cell edge. Also, the different frequency measurement may be stopped in response to the RS-SIR in the serving cell exceeding the threshold. This is likely to occur when the user apparatus approaches the base station apparatus. The measurement start threshold and the stop threshold may be the same or different. For example, when RS-SIR is used for the determination, it is desirable to set the stop threshold higher than the start threshold. As a result, frequent measurement start / stop switching can be prevented.

  The intermittent transmission cycle (DTX cycle) of the control signal of the base station device and the intermittent reception cycle (DRX cycle) of the user device need to match each other. In the example shown in FIG. 4, the DRX cycle of the user apparatus known by the base station apparatus is longer than the DRX threshold and is used as it is by the user apparatus. The base station apparatus does not need to know what the user apparatus is doing between the timings when the user apparatus is intermittently activated. Therefore, the base station apparatus does not need to know that an event for different frequency measurement has occurred in the user apparatus. This means that a signal such as a measurement report indicating that an event of different frequency measurement has occurred from the user apparatus to the base station apparatus is not essential (may be transmitted, but is omitted from the viewpoint of resource saving etc. It may be). As described above, the fact that events that do not require reporting to the base station apparatus are defined in the RRC layer is one of the differences from the conventional processing. In the illustrated example, the user apparatus autonomously performs different frequency measurement in response to the occurrence of an event for different frequency measurement, and autonomously stops the different frequency measurement in response to the occurrence of an event that stops the user apparatus. In addition, when the event for the hand-over to a different frequency cell generate | occur | produces following different frequency measurement, the measurement report which notifies that is transmitted from a user apparatus to a base station apparatus. An event for handover to a different frequency cell is, for example, an event in response to the measured RS-SIR of the different frequency cell exceeding a predetermined threshold, or the RS-SIR of the different frequency cell becomes the RS-SIR of the serving cell. It may be an event or the like in response to becoming a predetermined threshold or more.

  FIG. 5 shows a timing chart (No. 2) for explaining an operation example of the present invention. The example illustrated in FIG. 5 illustrates an operation example when the reception timing interval of the user apparatus is not longer than the DRX threshold. The case where the reception timing interval of the user device is not longer than the DRX threshold is not only when the intermittent reception cycle (for example, 3 ms) is set shorter than the DRX threshold (for example, 10 ms), but also intermittent reception is performed in the first place. This includes cases where there is no A typical example of the latter is a case where the user apparatus continuously receives a downlink control signal (PDCCH), for example, every subframe (for example, every 1 ms) and communicates a downlink or uplink data signal. The reception timing interval of the L1 / L2 control signal (PDCCH) for each subframe is clearly shorter than the DRX threshold. Even in such a case, for example, when the user apparatus approaches the cell edge, an event for measuring different frequencies may occur. In order to perform different frequency measurement in the user apparatus, the user apparatus needs to communicate intermittently with a sufficiently long DRX cycle, and in addition, the DRX cycle needs to be known to the base station apparatus.

  In the operation example of FIG. 5, the base station apparatus transmits a gap control signal (Gap ctrl) to the user apparatus so that appropriate intermittent communication is performed in response to the occurrence of an event for different frequency measurement. .

  The event for the different frequency measurement may be (1) confirmed by the user apparatus and reported to the base station apparatus, or (2) confirmed by the base station apparatus without such a report. . In the former case, the occurrence of such an event can be confirmed by performing the processing described in FIG. However, when an event for different frequency measurement is confirmed by the method (1), a measurement report indicating that must be notified from the user apparatus to the base station apparatus. In the case of the latter (2), the quality of the uplink reference signal (RS-SIR, etc.), the received power of the uplink reference signal (RS-RP), the average value and the path loss of the downlink CQI (reported from the user equipment), The base station apparatus may determine whether an event has occurred based on a comparison result with a predetermined threshold. Furthermore, downlink transmission power, communication signal error rate, number of retransmissions, MCS (combination of data modulation scheme and channel coding rate), and the like may be added to the event determination. When the event for different frequency measurement is confirmed by the method (2), it is not essential that the measurement report indicating that is notified from the user apparatus to the base station apparatus.

  The gap control signal (Gap ctrl) may include various parameter values specifically indicating the intermittent reception method to be performed by the user apparatus. The parameter value may include, for example, an intermittent reception cycle (DRX cycle), a duty ratio, an intermittent period, an activation period, and the like. Alternatively, these parameter values may not be included in the gap control signal, but may be commonly used in the system or in the cell, and the gap control signal may represent only whether or not predetermined intermittent reception should be performed ( In this case, the gap control signal is basically 1 bit). As an example, intermittent communication performed in response to an instruction (gap control signal) from the base station apparatus has an intermittent period of 10 ms and an activation period of 10 ms. Further, the gap control signal may be transmitted as an RRC message, or may be transmitted as a MAC control PDU. For example, assuming LTE, discontinuous reception affects radio resource allocation in the base station, that is, scheduling, and therefore, gap control may be processed in the MAC protocol layer that manages scheduling. On the other hand, when the RRC message is used, the retransmission function and security function of the RLC and PDCP protocol layers can be used.

  In the figure, data communication is performed in the 10 ms startup period indicated by 1, 2, 3, and 4, and different frequency measurement is performed in the intermittent period between them. In the example shown in the upper part of FIG. 5, a handover event occurs after the different frequency measurement, and a handover measurement report is transmitted to the base station apparatus in the fourth activation period. In response to this, the base station apparatus notifies the user apparatus of a handover command. In accordance with the handover command, the user apparatus connects to the cell found by the different frequency measurement and resumes continuous data communication.

  In the example shown in the lower part of FIG. 5, an event for stopping the different frequency measurement occurs (no handover event has occurred), and a measurement report indicating that fact is notified to the base station apparatus. The base station apparatus transmits a gap stop signal so that the user apparatus stops the different frequency measurement. In response, continuous data communication is resumed in the user apparatus. The situation shown in the lower side of FIG. 5 is likely to occur when the user apparatus approaches the base station apparatus again after approaching the cell edge.

  Even if the DRX cycle of the user apparatus is not longer than the DRX threshold, the user apparatus may perform intermittent reception with a DRX period shorter than the DRX threshold if an event for different frequency measurement has not occurred.

  In the above description, the DRX cycle is an interval of timing for receiving a control signal. However, the DRX cycle is defined as a gap period from the timing at which reception of a control signal is completed to the timing at which reception of the next control signal is started. Even so, the present invention can be similarly applied.

  In addition, even when the user equipment autonomously updates the DRX cycle according to a predetermined rule (specified by the base station device) according to the data activity, the updated DRX cycle is compared with the DRX threshold. The present invention can be similarly applied.

  Further, the case where a single value is designated as the DRX threshold has been described above, but a DRX threshold may be designated for each different frequency or different RAT to be measured. This is because the gap interval and gap amount required for measurement differ depending on the RAT.

  Since the different frequency measurement is performed between the time when the user apparatus receives the control signal (gap interval), the synchronization channel of the different frequency cell needs to be appropriately acquired within the gap interval.

  FIG. 6 shows an example of the relationship between the transmission timing of the synchronization channel SCH of the cells A and B that use different frequencies, the activation period and the gap interval in the user apparatus. In the case of the illustrated example, the user apparatus can appropriately capture the synchronization channel SCH of the different frequency cell A by performing the different frequency measurement during the gap interval. However, since the synchronization channel SCH of another different frequency cell B is not transmitted during the gap interval of the user equipment, it cannot be captured. In the example shown in FIG. 6, cell A can be found by different frequency measurement, but cell B cannot be found. In the figure, it is shown that the synchronization channel indicated by a thick frame can be captured by the user apparatus. Even if the cell B is the optimum handover destination for the user apparatus, it cannot move to the cell B, which is not preferable from the viewpoint of the system capacity and the like.

  When the gap interval is sufficiently long, the above problem can be avoided, but when it is short or when data communication is performed, the above problem is concerned.

FIG. 7 shows one way to address such a problem. When the base station apparatus transmits a gap control signal and causes the user apparatus to perform intermittent reception, the gap interval is set so that all synchronization channels SCH of different frequency cells around the serving cell can be captured. The synchronization channel indicated by a thick frame in FIG. 7 can be confirmed by the user apparatus. Specifically, the synchronization channel SCH of the different frequency cell A at timings ta1, ta4, ta5 and the synchronization channel SCH of the different frequency cell B at timings tb2, tb3, tb4 can be confirmed by the user apparatus. The base station device of the serving cell or its host device determines the gap interval so that the relationship between the transmission timing of the synchronization channel SCH of the different frequency cell around the serving cell and the gap interval in the serving cell is appropriate. To do. Specifically, the transmission timing t of the synchronization channel to be detected in the different frequency measurement is expressed by (t = N × T _SCH + b) (N is an integer, and T _SCH is the transmission of the synchronization channel. Period, b is offset). The activation period is set so that these timings are included in the gap interval or so as to avoid these timings. In the example of FIG. 7, the gap interval is set so that both (N × T _SCH-A + b _A ) and (M × T _SCH-B + b _B ) timings are included in the gap interval, or these timings are set. The activation period is set to avoid. N and M are integers, T _SCH-A and T _SCH-B are transmission periods of synchronization channels of different frequency cells A and B, and b _A and b _B are offsets.

  As shown in FIG. 8, a channel that is considered so as to be surely captured within the gap interval may include not only the synchronization channel SCH but also the broadcast channel BCH, and other channels may be considered. Also good. In the illustrated example, the synchronization channel SCH and broadcast channel BCH of the different frequency cell A transmitted at timing ta1, the synchronization channel SCH of the different frequency cell B transmitted at timing tb3, and the different frequency cell B transmitted at timing tb4. Synchronization channel SCH and broadcast channel BCH, synchronization channel SCH of different frequency cell A transmitted at timing ta4, synchronization channel SCH and broadcast channel BCH of different frequency cell A transmitted at timing ta5 can be appropriately confirmed by different frequency measurement It is.

  In the first embodiment, according to the comparison result between the DRX cycle and the DRX threshold, the different frequency measurement timing of the user apparatus is different. When the DRX cycle is long, the DRX cycle is changed when the DRX cycle is short at a timing autonomously determined by the user apparatus, and different frequency measurement is performed at the changed cycle. The comparison between the DRX cycle and the DRX threshold may be performed by the base station apparatus or the user apparatus. Alternatively, the comparison result may be notified to the user device.

In the third embodiment of the present invention, information corresponding to the comparison result is notified to the user device as a different frequency measurement indicator. The different frequency measurement indicator may be notified to the user apparatus as a DRX parameter when the radio bearer is set or changed. The change of the radio bearer includes addition and deletion. The DRX parameters include a group of parameters indicating what kind of discontinuous reception operation should be performed when the user apparatus performs discontinuous reception operation. The DRX parameters are set according to the service type, QoS class, etc., and more generally may be set for each radio bearer. Alternatively, an optimum set of DRX parameters may be designated for each user device in consideration of service types, QoS classes, and the like of a plurality of radio bearers set for the user device. Therefore, typically, the DRX parameter is notified to the user apparatus when a new radio bearer is added, added, deleted, or the like. As an example, DRX parameters include the following information items:
・ DRX interval
・ On duration
・ Inactivity time
-Different frequency measurement indicator.

  FIG. 9 shows the relationship between the DRX cycle, the activation period, and the gap interval.

  The DRX cycle indicates an interval at which intermittent reception is performed, and may take a value such as 5 ms, 10 ms, or 100 ms, for example.

  The activation period indicates a period during which the downlink physical control channel (PDCCH: Physical Downlink Control CHannel) is continuously received in the DRX cycle, and may take a value such as 1 ms or 3 ms, for example. “Continuously receive” means that the PDCCH is received most frequently in the same manner as in the active state, and as an example means that it is received every subframe (for example, 1 ms). The different frequency measurement is performed during a gap interval between the start period and the next start period.

  The inactivity period is used for determination when shifting from the operation mode in which PDCCH is continuously received to the intermittent reception mode. When the period during which radio resources are not allocated to PDSCH or PUSCH for a certain user apparatus reaches the inactivity period, the operation mode of the user apparatus is changed from the continuous reception mode to the intermittent reception mode. The inactivity period may be expressed by any appropriate numerical value associated with such time, and may be specified by a specific time, for example, or may be specified by the number of receptions of PDCCH. By setting the inactivity period as a DRX parameter, it is possible to make the base station apparatus and the user apparatus recognize the same operation mode without requiring any signaling for changing the operation mode of the user apparatus. Alternatively, the change in the operation mode of the user apparatus may be explicitly signaled by some signaling so that it is not essential to notify the user apparatus in advance of the inactivity period.

  The different frequency measurement indicator indicates whether the DRX cycle (more precisely, the gap interval) is longer than a predetermined DRX threshold. Therefore, the different frequency measurement indicator is typically represented by 1 bit. However, when expressing not only the magnitude relationship between the DRX cycle (or gap interval) and the DRX threshold, but also the relationship between them, it may be better to express the different frequency measurement indicator with multiple bits. . For example, when 6 ms is required for different frequency measurement, it is assumed that the gap interval is 20 ms. In this case, different different frequency measurements can be performed three times during the gap interval of 20 ms. In other words, three different RATs can be searched during one gap interval. Thus, from the viewpoint of notifying the user apparatus of information indicating how many different RATs can be measured during a given gap interval, it is preferable to express the different frequency measurement indicator with multiple bits. From this point of view, a different frequency measurement indicator may be designated for each different frequency and different RAT to be measured.

  As described above, the DRX threshold is set to a period that is long enough to perform the different frequency measurement. Therefore, in setting the DRX threshold, the time for changing the tuning frequency of the user equipment from the frequency of the serving cell to another frequency (for example, 0.5 ms), the time for performing a cell search for different frequencies (for example, a synchronization channel such as 5 ms) And the time for returning the tuning frequency (for example, 0.5 ms) should be considered at least.

  The operation will be described with reference to the timing chart of FIG. First, it is assumed that the user apparatus continuously receives the PDCCH in the active state. For simplicity of illustration, the activation period is drawn as short as one subframe (for example, 1 ms), but this is not essential, and the activation period may be set to any appropriate value. The user apparatus demodulates and decodes the PDCCH, and confirms whether or not radio resources are allocated to the PDSCH or PUSCH with respect to the own apparatus. When radio resources are allocated to the PDSCH, the user apparatus identifies the resource specified by the downlink scheduling information and receives the downlink physical shared channel PDSCH. When the radio resource is allocated to the PUSCH, the user apparatus identifies the resource specified by the uplink scheduling information, and transmits the uplink physical shared channel PUSCH at an appropriate timing thereafter using the resource. If radio resources are not allocated to either PUSCH or PDSCH, the system waits for the next subframe and receives the next PDCCH.

  When the period during which no radio resource is allocated to either PDSCH or PUSCH reaches the above inactivity period, the operation mode of the user apparatus is switched from the continuous reception mode to the intermittent reception mode. Thereafter, the user apparatus is activated for a designated activation period (on duration) every DRX cycle, and continuously receives the PDCCH during the activation period. When radio resources are allocated to the uplink or downlink, the operation mode is switched to the continuous reception mode again. The state transition from the continuous reception mode to the intermittent reception mode (or vice versa) may or may not be explicitly notified from the user apparatus to the base station apparatus by some signaling signal. . This is because the base station apparatus knows the contents of uplink and downlink scheduling information.

  When the user apparatus enters the intermittent reception mode and an event for different frequency measurement occurs, the different frequency measurement is executed according to the value indicated by the different frequency measurement indicator. The different frequency measurement indicator is typically represented by 1 bit. When the DRX period (more precisely, the gap interval) is longer than the DRX threshold (eg, when the different frequency measurement indicator indicates “1”), as described with respect to FIG. 4 of the first embodiment, The user apparatus performs different frequency measurement at a timing determined by itself during the gap interval. When the DRX period (more precisely, the gap interval) is shorter than the DRX threshold (eg, when the different frequency measurement indicator indicates “0”), as described with reference to FIG. 5 of the first embodiment, The base station apparatus notifies the user apparatus of a gap control signal (Gap Ctrl), and a DRX parameter that provides a gap interval wider than the gap interval is notified. The user apparatus performs different frequency measurement during the gap interval according to the DRX parameter designated anew.

  Regarding how to set the DRX threshold value and thus the value of the different frequency measurement indicator, whether or not the gap interval is sufficiently long to allow the user apparatus to perform the different frequency measurement as described above should be considered. It is. Since the performance (in particular, the signal processing speed) of the user apparatus is not uniformly the same, the value of the different frequency measurement indicator can also be set individually for each user apparatus. Alternatively, the value of the different frequency measurement indicator may be determined based on the minimum performance required for all user apparatuses in the mobile communication system.

  DRX parameters including a DRX cycle, a startup period, an inactivity period, a different frequency measurement indicator, and the like can be set for each radio bearer. When such a DRX parameter is set as a radio bearer, individual information items may be notified to the user apparatus as they are. Alternatively, from the viewpoint of saving signaling overhead, an index may be prepared for each of various DRX parameters, and only the index may be notified to the user apparatus. This is because if the correspondence between the DRX parameter and the index is known in advance, necessary information can be appropriately extracted from the index.

  As described above, various DRX parameters may be set for each radio bearer. Furthermore, a plurality of DRX parameters may be associated with the same radio bearer. In the fourth embodiment of the present invention, a short DRX parameter that defines a short DRX cycle and a long DRX parameter that defines a long DRX cycle are prepared. The operation modes of the user apparatus include a continuous reception mode, a short DRX mode, and a short DRX mode. Long DRX mode is included. The present invention can also be applied to such a case.

  The operation will be described with reference to the timing chart of FIG. Similarly to the example shown in FIG. 10, first, it is assumed that the user apparatus is continuously receiving PDCCH in an active state. When the radio bearer is set up, the short DRX parameter and the long DRX parameter are notified to the user apparatus.

Short DRX parameters are
Short DRX period (for example, 20ms),
Startup period (e.g. 3ms),
Including a first inactivity period (eg, 5 ms) and a first different frequency measurement indicator.

Long DRX parameters are
Long DRX period (e.g. 100ms),
Startup period (for example, 6ms),
A second inactivity period (eg, 500 ms) and a second different frequency measurement indicator.

  The user apparatus decodes and demodulates the PDCCH, and confirms whether or not radio resources are allocated to the PDSCH or PUSCH for the own apparatus. When radio resources are allocated to the PDSCH, the user apparatus identifies the resource specified by the downlink scheduling information and receives the downlink physical shared channel PDSCH. When the radio resource is allocated to the PUSCH, the user apparatus identifies the resource specified by the uplink scheduling information, and transmits the uplink physical shared channel PUSCH at an appropriate timing thereafter using the resource. If no radio resource is assigned to either PDSCH or PUSCH, the system waits for the next subframe and receives the next PDCCH.

  When the period during which no radio resource is allocated to either PDSCH or PUSCH reaches the first inactivity period, the operation mode of the user apparatus is switched from the continuous reception mode to the short intermittent reception mode. Thereafter, the user apparatus is activated for a specified activation period every short DRX cycle, and continuously receives the PDCCH during the activation period. When radio resources are allocated to the uplink or downlink, the operation mode is switched to the continuous reception mode again. The state transition from the continuous reception mode to the intermittent reception mode (or vice versa) may or may not be explicitly notified from the user apparatus to the base station apparatus by some signaling signal. .

  When the user apparatus enters the short intermittent reception mode and an event for different frequency measurement occurs, the different frequency measurement is executed according to the value indicated by the first different frequency measurement indicator. The different frequency measurement indicator is typically represented by 1 bit. When the first different frequency measurement indicator indicates “1”, for example, as described with reference to FIG. 4 of the first embodiment, the user apparatus measures the different frequency at the timing determined by itself during the gap interval. Is done. When the first different frequency measurement indicator indicates “0”, the base station apparatus notifies the user apparatus of a gap control signal (Gap Ctrl) as described with reference to FIG. A DRX parameter is reported that results in a gap spacing wider than the gap spacing. The user apparatus performs different frequency measurement during the gap interval according to the DRX parameter designated anew.

  Even after entering the short intermittent reception mode, radio resources are still not allocated to the PDSCH or PUSCH, and when the period reaches the second inactivity period, the operation mode of the user equipment is changed from the short intermittent reception mode to the long intermittent. Switch to reception mode. Thereafter, the user apparatus is activated for a specified activation period every long DRX cycle, and continuously receives the PDCCH during the activation period. When radio resources are allocated to the uplink or downlink, the operation mode is switched to the continuous reception mode again. Also in this case, the state transition may be explicitly notified from the user apparatus to the base station apparatus with some signaling signal, or may not be notified.

  When the user apparatus enters the long intermittent reception mode and an event for different frequency measurement occurs, the different frequency measurement is executed according to the value indicated by the second different frequency measurement indicator. The second different frequency measurement indicator is also typically represented by 1 bit. When the second different frequency measurement indicator indicates, for example, “1”, the user apparatus measures the different frequency at the timing determined by itself during the gap interval as described with reference to FIG. 4 of the first embodiment. Is done. When the second different frequency measurement indicator indicates “0”, the base station apparatus notifies the user apparatus of a gap control signal (Gap Ctrl) as described with reference to FIG. A DRX parameter is reported that results in a gap spacing wider than the gap spacing. The user apparatus performs different frequency measurement during the gap interval according to the DRX parameter designated anew.

  As in the above numerical example, the length of the DRX cycle may be directly associated with the length of the gap period. In this case, if the different frequency measurement indicator for the DRX parameter of the short DRX cycle indicates 1 (indicating that different frequency measurement is possible without changing the DRX parameter), the case of the DRX parameter of the long DRX cycle The different frequency measurement indicator should be 1. However, the length of the DRX cycle is not always directly linked to the length of the gap period. As described above, the DRX parameter may be different for each radio bearer, and may take various values. The gap period depends not only on the DRX cycle but also on the value of the startup period. Therefore, the value of the different frequency measurement indicator in the short DRX parameter and the value of the different frequency measurement indicator in the long DRX parameter are preferably set separately.

  Although the present invention has been described above with reference to specific embodiments, each embodiment is merely illustrative, and those skilled in the art will appreciate various variations, modifications, alternatives, substitutions, and the like. Let's go. Although specific numerical examples have been described in order to facilitate understanding of the invention, these numerical values are merely examples and any appropriate values may be used unless otherwise specified. The division of each embodiment is not essential to the present invention, and two or more embodiments may be used as necessary. For convenience of explanation, an apparatus according to an embodiment of the present invention has been described using a functional block diagram, but such an apparatus may be realized by hardware, software, or a combination thereof. The present invention is not limited to the above embodiments, and various modifications, modifications, alternatives, substitutions, and the like are included in the present invention without departing from the spirit of the present invention.

A conceptual diagram of multi-RAT handover is shown. The schematic block diagram of the base station apparatus used by one Example of this invention is shown. FIG. 2 shows a schematic block diagram of a user equipment used in an embodiment of the present invention. The timing chart (the 1) for demonstrating the operation example of this invention is shown. The timing chart (the 2) for demonstrating the operation example of this invention is shown. It is a figure which shows a mode that a gap space | interval is not appropriate. It is a figure (1) which shows a mode that a gap space | interval is appropriate. It is a figure (the 2) which shows a mode that a gap space | interval is appropriate. It is a figure which shows the relationship between a DRX period, a starting period, and a gap space | interval. It is a figure for demonstrating the operation | movement in 3rd Example. It is a figure for demonstrating the operation | movement in 4th Example.

Explanation of symbols

101 reception RF unit 103 control information generation unit 105 RRC processing unit 107 broadcast information generation unit 109 transmission RF unit 201 reception RF unit 203 L1 / L2 processing unit 205 RRC processing unit 207 control unit 209 measurement unit 211 transmission RF unit

Claims (17)

A user equipment used in a mobile communication system,
Means for receiving the downlink control signal at the frequency of the serving cell at an intermittent reception period specified by the base station device;
When a predetermined event for different frequency measurement is confirmed by the user apparatus or the base station, a cell search is performed at a frequency different from the frequency of the serving cell between reception timings of the downlink control signal. Means,
When the different frequency measurement indicator designated by the base station device indicates a predetermined value, when the predetermined event occurs, the different frequency measurement is performed at a timing determined by the own device,
When the different frequency measurement indicator indicates another predetermined value, the user apparatus is configured to perform different frequency measurement at a timing specified by the base station apparatus different from the intermittent reception cycle.   The user apparatus according to claim 1, wherein the different frequency measurement indicator is expressed by one bit.   The said different frequency measurement indicator is a user apparatus of Claim 1 notified from the said base station apparatus with the information which shows the said intermittent reception period.   The user apparatus according to claim 1, wherein the different frequency measurement indicator is notified from the base station apparatus when a radio bearer is newly installed or changed.   The operation mode of the user apparatus includes a continuous reception mode for continuously receiving the downlink control signal, a short intermittent reception mode for receiving with a short intermittent reception cycle, and a long intermittent reception mode for receiving with a long intermittent reception cycle. The user device according to claim 1 included. In the short intermittent reception mode, when the first different frequency measurement indicator notified from the base station device indicates a predetermined value, when the predetermined event occurs, the different frequency measurement is performed at a timing determined by the own device. When the first different frequency measurement indicator shows another predetermined value, different frequency measurement is performed at a timing specified by the base station device different from the intermittent reception cycle,
In the long intermittent reception mode, when the second different frequency measurement indicator notified from the base station device indicates a predetermined value, when the predetermined event occurs, the different frequency measurement is performed at a timing determined by the own device. The user apparatus according to claim 5, wherein when the second different frequency measurement indicator indicates another predetermined value, the different frequency measurement is performed at a timing specified by the base station apparatus different from the intermittent reception cycle.   6. The user according to claim 5, wherein the operation mode transits from the continuous reception mode to the short intermittent reception mode when operating in the continuous reception mode and a physical shared channel is not communicated for a predetermined period. apparatus.   The operation mode transitions from the short intermittent reception mode to the long intermittent reception mode when operating in the short intermittent reception mode and a physical shared channel is not communicated over a predetermined period. User equipment. A method used in a user equipment in a mobile communication system, comprising:
Receiving a downlink control signal at a frequency of the serving cell at an intermittent reception period designated by the base station device;
When a predetermined event for different frequency measurement is confirmed by the user apparatus or the base station, a cell search is performed at a frequency different from the frequency of the serving cell between reception timings of the downlink control signal. Steps,
When the different frequency measurement indicator designated by the base station device indicates a predetermined value, when the predetermined event occurs, the different frequency measurement is performed at a timing determined by the own device,
A method in which different frequency measurement is performed at a timing specified by the base station apparatus different from the intermittent reception cycle when the different frequency measurement indicator shows another predetermined value. A base station apparatus used in a mobile communication system,
Means for notifying the user apparatus of intermittent reception information including at least the intermittent reception period of the downlink control signal;
Means for transmitting the downlink control signal to the user equipment;
The intermittent reception information further includes a different frequency measurement indicator,
When the predetermined event for different frequency measurement is confirmed by the user apparatus or the base station apparatus, and the different frequency measurement should be performed at the timing determined by the user apparatus, the different frequency measurement indicator Is set to a predetermined value, and the different frequency measurement indicator is set to another predetermined value when different frequency measurement should be performed at a period specified by the base station apparatus longer than the intermittent reception period. Base station device.   The base station apparatus according to claim 10, wherein the different frequency measurement indicator is expressed by 1 bit.   The base station apparatus according to claim 10, wherein the different frequency measurement indicator is notified to the user apparatus when a radio bearer is newly installed or changed. The operation mode of the user apparatus includes a continuous reception mode for continuously receiving the downlink control signal, a short intermittent reception mode for receiving with a short intermittent reception cycle, and a long intermittent reception mode for receiving with a long intermittent reception cycle. Included,
The base station apparatus according to claim 10, wherein a first different frequency measurement indicator is notified to the user apparatus for the short intermittent reception mode, and a second different frequency measurement indicator is notified to the user apparatus for the long intermittent reception mode. When a predetermined event for different frequency measurement is confirmed in the user apparatus or the base station apparatus, the different frequency measurement is performed at a timing determined by the user apparatus operating in the short reception mode. In the case where power should be measured, the first different frequency measurement indicator is set to a predetermined value, and in the case where the different frequency measurement should be performed in a cycle specified by the base station apparatus longer than the short intermittent reception cycle, the first different frequency measurement is performed. The frequency measurement indicator is set to another predetermined value,
When the different frequency measurement should be performed at a timing determined by the user apparatus operating in the long intermittent reception mode, the second different frequency measurement indicator is set to a predetermined value and is longer than the long intermittent reception cycle. The base station apparatus according to claim 34, wherein the second different frequency measurement indicator is set to another predetermined value when the different frequency measurement is to be performed at a period specified by the base station apparatus.   When the user apparatus is operating in the continuous reception mode and the physical shared channel is not communicated for a predetermined period, the operation mode is changed from the continuous reception mode to the short intermittent reception mode. The base station apparatus according to claim 13, which is determined.   When the user apparatus is operating in the short intermittent reception mode and the physical shared channel is not communicated for a predetermined period, the operation mode is changed from the short intermittent reception mode to the long intermittent reception mode. The base station apparatus according to claim 13, wherein the base station apparatus judges that the base station apparatus is. A method used in a base station apparatus in a mobile communication system,
Notifying the user apparatus of intermittent reception information including at least the intermittent reception period of the downlink control signal;
Transmitting the downlink control signal to the user equipment;
The intermittent reception information further includes a different frequency measurement indicator,
When the predetermined event for different frequency measurement is confirmed by the user apparatus or the base station apparatus, and the different frequency measurement should be performed at the timing determined by the user apparatus, the different frequency measurement indicator Is set to a predetermined value, and the different frequency measurement indicator is set to another predetermined value when different frequency measurement should be performed at a period specified by the base station apparatus longer than the intermittent reception period. Method.

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