JP2018191353A - Radio terminal, wireless communication system, base station and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio terminal capable of preventing degradation of measurement.SOLUTION: A radio terminal which performs radio communication with a base station comprises: a communication part for monitoring paging signal of a base station; and a control part configured to receive a piece of information relevant to a first segment from the base station by a NAS (Non-Access Stratum) message, control the communication part not to perform the monitoring in the first segment and control the communication part to perform the monitoring in a second segment different from the first segment. The control part is also configured to receive a message different from the NAS message from the base station and to control to perform the control of the second segment.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless terminal, a wireless communication system, a base station, and a wireless communication method for performing wireless communication.

  Cellular mobile communication has evolved from UMTS (Universal Mobile Telecommunication System) to LTE (Long Term Evolution). In LTE, a method based on OFDM (Orthogonal Frequency Division Multiplexing) is defined as a radio access technology, and high-speed wireless packet communication with a downlink peak transmission rate of 100 Mb / s or more and an uplink peak transmission rate of 50 Mb / s or more is possible. It becomes possible.

  The 3rd Generation Partnership Project (3GPP), which is an international standardization organization, is currently examining LTE-A (LTE-Advanced) based on LTE for realizing higher-speed communication. In LTE-A, the downstream peak transmission rate is 1 Gb / s and the upstream peak transmission rate is 500 Mb / s, and various new technologies such as a radio access system and a network architecture are being studied (for example, Non-patent documents 1 to 3). On the other hand, since LTE-A is a system based on LTE, it is important to maintain backward compatibility.

  In LTE or LTE-A, cell selection is defined as an operation of the wireless terminal in the idle mode. Specifically, cell selection and cell reselection are defined (for example, refer to Non-Patent Documents 4 and 5).

  Cell selection is performed when the wireless terminal is turned on and a PLMN (Public Land Mobile Network) is selected. Cell selection is further defined by cell selection (initial cell selection) performed by wireless terminals without knowing cell information, and cell selection (stored information cell selection) performed by mobile stations after knowing cell information. Has been.

  In cell selection, the radio terminal measures radio quality, selects a cell with good radio quality as a serving cell, and camps on the network. More specifically, if a cell selection criterion “S” defined by RSRP (Reference Signal Received Power) and RSRQ (Reference Signal Received Quality) is satisfied, the cell can be camped on (for example, non-patent literature). 4). The wireless terminal can make an incoming call by camping on the network. Cell reselection is performed to detect a cell with better radio quality, and when a better radio quality is detected, camp on is performed for the cell.

  In order to detect a cell with better radio quality, radio measurement in idle mode is defined (for example, see Non-Patent Document 5). In the idle mode, it is required to balance the power consumption of the wireless terminal and the accuracy of wireless measurement.

  For example, if the frequency of measurement is reduced in order to reduce power consumption, the accuracy of the measurement deteriorates, and there is a case where camping on an appropriate cell cannot be performed. On the other hand, if the frequency of the measurement is increased in order to increase the accuracy of the measurement, the power consumption increases. Considering such points, DRX (Discontinuous Reception) is defined (for example, see Non-Patent Document 5).

  The DRX cycle value of DRX may be acquired by broadcast information broadcast by a base station, or may be set by NAS (Non Access Stratum) that is a higher layer. The wireless terminal performs measurement at least once every DRX and samples the wireless quality. Then, the wireless terminal averages the wireless quality at the sampling interval defined by the DRX function, and calculates the measured value of the wireless quality.

  Also, the idle mode wireless terminal periodically monitors the paging signal in order to detect incoming calls. As in the case of the measurement described above, when the frequency of monitoring the paging signal is lowered, the wireless terminal generates a communication delay, and when the frequency of monitoring the paging signal is increased, the power consumption increases. Therefore, it is specified that the monitoring of the paging signal is performed only once within the DRX cycle (for example, see Non-Patent Document 4).

  As described above, the radio terminal can perform cell selection and incoming call detection taking power consumption into consideration by performing measurement and monitoring of the paging signal within the DRX cycle which is a measurement cycle.

3GPP TR36.913 V9.0.0 3GPP TR36.912 V9.3.0 3GPP TS36.300 V10.4.0 3GPP TS36.304 V10.2.0 3GPP TS36.133 V10.3.0

  By the way, it is stipulated that the determination as to whether or not to perform measurement and cell selection should be performed at least once every DRX cycle. In the measurement measurement value calculation, sample values of radio quality (specifically, RSRP and RSRQ values) obtained by the measurement are filtered and averaged with an interval of at least half of DRX. (For example, see Non-Patent Document 5).

  Therefore, if the DRX cycle is increased in order to suppress the power consumption of the wireless terminal, there is a problem that the measurement sampling interval becomes longer and the accuracy of the measurement is deteriorated.

  The present case has been made in view of such a point, and an object thereof is to provide a radio terminal, a radio communication system, a base station, and a radio communication method capable of suppressing deterioration of measurement.

  In order to solve the above-mentioned problem, in a wireless terminal that performs wireless communication with a base station, a communication unit that monitors a paging signal of the base station and a first NAS (Non-Access Stratum) message from the base station A control unit that receives information related to a section, controls the communication unit so that monitoring cannot be performed in the first section, and can control the communication unit to perform monitoring in a second section different from the first section The control unit is further provided with a wireless terminal that receives a message different from the first NAS message from the base station and performs control to perform control of the second section.

According to the disclosed apparatus and method, deterioration of the measurement can be suppressed.
These and other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings which illustrate preferred embodiments by way of example of the present invention.

It is a figure explaining the radio | wireless terminal which concerns on 1st Embodiment. It is the figure which showed the radio | wireless communications system which concerns on 2nd Embodiment. It is a functional block diagram of a wireless terminal. It is the figure which showed the hardware structural example of the radio | wireless terminal. It is a functional block diagram of a base station. It is the figure which showed the hardware structural example of the base station. It is the 1 of the timing chart of a radio | wireless terminal. It is the 2 of the timing chart of a radio | wireless terminal. It is a flowchart of a radio | wireless terminal. It is a flowchart of a base station. It is a timing chart of the radio | wireless terminal which concerns on 3rd Embodiment. It is a figure explaining the mask pattern of DRX. It is a flowchart of a radio | wireless terminal. It is a flowchart of a base station. It is a timing chart of the radio | wireless terminal which concerns on 4th Embodiment. It is a flowchart of a radio | wireless terminal. It is a flowchart of a base station. It is a timing chart of the radio | wireless terminal which concerns on 5th Embodiment. It is a flowchart of a radio | wireless terminal. It is a flowchart of a base station. It is a timing chart of the radio | wireless terminal which concerns on 6th Embodiment. It is a figure explaining operation | movement of a NAS attach procedure and a NAS detach procedure. It is a flowchart of a radio | wireless terminal. It is a flowchart of a base station.

Hereinafter, embodiments will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a diagram illustrating a radio terminal according to the first embodiment. As shown in FIG. 1, the wireless terminal 1 has a communication unit 1a and a control unit 1b. Arrows A <b> 1 to A <b> 3 illustrated in FIG. 1 indicate base station measurement (not shown) and timing of paging signal monitoring performed by the wireless terminal 1. In FIG. 1, m indicates the timing at which the wireless terminal 1 performs measurement of a base station (not shown), and p indicates the timing at which the paging signal is monitored.

The communication unit 1a intermittently performs measurement of a base station (not shown) and monitoring of a paging signal within a period T.
For example, T shown in FIG. 1 indicates DRX. The communication unit 1a intermittently monitors the measurement (m) of the base station and the paging signal (p) within the DRX cycle of DRX.

  In the section T, the control unit 1b controls the communication unit 1a so that the measurement is performed at an interval smaller than half of the section length of the section T. Furthermore, filtering of radio quality sample values (specifically RSRP and RSRQ values) obtained by measurement is performed at intervals smaller than half of the section length of section T.

  For example, the control unit 1b controls the communication unit 1a to perform measurement at an interval smaller than half of the section length of the section T as indicated by an arrow A1. Specifically, the control unit 1b controls the communication unit 1a so that the measurement is performed at intervals smaller than half of the DRX cycle.

  Note that an arrow A2 shows an example of timing of conventional measurement and paging signal monitoring. As described above, it is stipulated that the determination as to whether the measurement and the cell selection should be performed is performed at least at intervals of the DRX cycle. Here, in order to suppress the power consumption of the wireless terminal 1, the section length (DRX cycle) of the section T is increased as shown by an arrow A3.

  An arrow A3 indicates another example of the timing of monitoring the conventional measurement and the paging signal. In order not to violate the above-mentioned rule, the measurement is performed at intervals of half of the DRX cycle (DRX cycle / 2). Further, in the measurement measurement value calculation, the sample values of these measurements are averaged to obtain the measurement result of the radio quality of each cell. By executing the measurement and the measurement value calculation in this way, the accuracy of the measurement can be maintained even if the section length (DRX cycle) of the section T is increased. However, the conventional measurement interval becomes longer as the DRX cycle becomes longer, and the measurement averaging interval becomes longer, so that the accuracy of the measurement deteriorates.

  On the other hand, the control unit 1b controls the communication unit 1a so as to perform the measurement at an interval smaller than half of the section length of the section T as described above. Furthermore, filtering of radio quality sample values (specifically RSRP and RSRQ values) obtained by measurement is performed at intervals smaller than half of the section length. As a result, the wireless terminal 1 can suppress power consumption, shorten the measurement averaging interval, and suppress measurement deterioration.

  As described above, the communication unit 1a of the wireless terminal 1 performs the measurement of the base station and the monitoring of the paging signal within the period T. And the control part 1b was made to control the communication part 1a so that a measurement may be performed in the area T at intervals smaller than half of the area length of the area T. Thereby, even if the section length of the section T is lengthened in order to suppress power consumption, the wireless terminal 1 can suppress the extension of the measurement and suppress the deterioration of the measurement.

[Second Embodiment]
Next, a second embodiment will be described in detail with reference to the drawings.
FIG. 2 is a diagram illustrating a wireless communication system according to the second embodiment. FIG. 2 shows a base station 11 and a wireless terminal 12. The base station 11 and the wireless terminal 12 perform wireless communication using, for example, an LTE-A or LTE communication method.

  The wireless terminal 12 is built in, for example, a gas meter or an electric meter device. For example, the wireless terminal 12 transmits information such as an abnormality detected by a device such as a gas meter or an electric meter and a usage fee to the base station 11. The information transmitted to the base station 11 is transmitted to, for example, a gas company or an electric company.

  Such a device has communication characteristics different from those of a mobile phone or the like. For example, the device does not move and the amount of communication is small. Therefore, it is considered that the device is mostly in idle mode and rarely in connected mode.

  In addition, when a device is installed in an apartment etc., the base station 11 may be a home eNB (evolved Node B), for example. The device is not limited to the meter described above, and may be built in a sensor or a health meter that manages the health condition of a person.

  FIG. 3 is a functional block diagram of the wireless terminal. As illustrated in FIG. 3, the wireless terminal 12 includes a communication unit 21 and a control unit 22. The control unit 22 includes a radio control unit 22a, a control plane layer control unit 22b, and an application layer control unit 22c.

  The communication unit 21 controls wireless communication. For example, the communication unit 21 performs BB (Base Band) processing and RF (Radio Frequency) processing on a signal transmitted to and received from the base station 11. The communication unit 21 is turned on / off under the control of the wireless control unit 22a of the control unit 22.

The radio control unit 22a controls the BB process and the RF process of the communication unit 21. In addition, the wireless control unit 22 a performs power on / off control of the communication unit 21.
The control plane layer control unit 22b controls an RRC (Radio Resource Control) layer and a NAS layer.

The application layer control unit 22c controls the application layer.
Note that the communication unit 21 corresponds to, for example, the communication unit 1a in FIG. The radio control unit 22a and the control plane layer control unit 22b correspond to, for example, the control unit 1b in FIG.

  FIG. 4 is a diagram illustrating a hardware configuration example of the wireless terminal. As illustrated in FIG. 4, the wireless terminal 12 includes a processor 31, a main memory 32, a ROM (Read Only Memory) 33, a storage 34, a communication interface 35, an input / output device 36, a display 37, and a bus 38. .

  A main memory 32, ROM 33, storage 34, communication interface 35, input / output device 36, and display 37 are connected to the processor 31 via a bus 38. The entire wireless terminal 12 is controlled by the processor 31. The processor 31 is, for example, a CPU (Central Processing Unit) or a DSP (Digital Signal Processor).

  In the main memory 32, data and programs used in various processes of the processor 31 are temporarily stored. The ROM 33 stores static information such as a protocol that defines the operation of the wireless terminal 12. For example, the ROM 33 stores information for the processor 31 to execute data plane processing, control plane processing, scheduling processing, or the like. The storage 34 stores data and programs used in various processes of the processor 31. The communication interface 35 performs wireless communication with the base station 11. For example, the communication interface 35 converts a baseband signal into a radio frequency and outputs it to an antenna (not shown). The communication interface 35 converts a radio signal received by an antenna (not shown) into a baseband signal.

  The input / output device 36 is, for example, a key, a speaker, and a microphone. For example, the key accepts characters and numbers input by the user. The speaker converts, for example, an audio signal received from the base station 11 into audio and outputs the audio. The microphone also converts the user's voice into an electrical signal. The display 37 is, for example, an LCD (Liquid Crystal Display). The display 37 displays data received from the base station 11, for example.

Note that the function of the communication unit 21 in FIG. 3 is realized by, for example, the communication interface 35. The function of the control unit 22 is realized by the processor 31, for example.
FIG. 5 is a functional block diagram of the base station. As illustrated in FIG. 5, the base station 11 includes a communication unit 41 and a control unit 42. The control unit 42 includes a radio control unit 42a and a control plane layer control unit 42b.

The communication unit 41 controls wireless communication. For example, the communication unit 41 performs BB processing and RF processing on a signal transmitted to and received from the wireless terminal 12.
The wireless control unit 42a controls the BB processing and the RF processing of the communication unit 41.

The control plane layer control unit 42b controls the RRC layer and the NAS layer.
FIG. 6 is a diagram illustrating a hardware configuration example of the base station. As illustrated in FIG. 6, the base station 11 includes a processor 51, a main memory 52, a ROM 53, a storage 54, a communication interface 55, and a bus 56.

  A main memory 52, a ROM 53, a storage 54, and a communication interface 55 are connected to the processor 51 via a bus 56. The entire base station 11 is controlled by the processor 51. The processor 51 is, for example, a CPU or a DSP.

  In the main memory 52, data and programs used in various processes of the processor 51 are temporarily stored. The ROM 53 stores static information such as a protocol that defines the operation of the base station 11. For example, the ROM 53 stores information for the processor 51 to execute data plane processing, control plane processing, scheduling processing, or the like. The storage 54 stores data and programs used in various processes of the processor 51. The communication interface 55 performs wireless communication with the wireless terminal 12. For example, the communication interface 55 converts a baseband signal into a radio frequency and outputs it to an antenna (not shown). The communication interface 55 converts the frequency of a radio signal received by an antenna (not shown) into a baseband signal. The communication interface 55 performs wired communication with a host device such as an S-GW (Serving-Gateway).

  FIG. 7 is part 1 of the timing chart of the wireless terminal. M in FIG. 7 indicates the measurement timing of the wireless terminal 12. p indicates the monitoring timing of the paging signal of the wireless terminal 12.

  In the example of FIG. 7, the timings of m and p are different before and after the event detected by the application layer. The event is generated, for example, by a charge report such as an electric meter or an abnormality report.

For example, the wireless terminal 12 uses a long DRX cycle longer than a normal DRX cycle in order to reduce power consumption.
Here, the measurement value of the conventional measurement is calculated by averaging at least samples of the measurement having an interval of “DRX cycle / 2”. Therefore, the measurement interval extends, for example, as indicated by an arrow A3 in FIG. 1, and the measurement measurement accuracy deteriorates.

  On the other hand, the wireless terminal 12 performs the measurement at least once at the DRX interval as in the prior art. Therefore, multiple measurements can be performed within a certain DRX section. However, the measurement value is calculated by filtering the measurement sample value at an interval of 'long DRX cycle / n' (n> 2). Accordingly, the wireless terminal 12 performs measurement at an interval of “X” shown in FIG.

  For example, the wireless terminal 12 averages two measurements and calculates a measurement value of the measurement. For example, in the long DRX cycle before the event occurrence illustrated in FIG. 7, the wireless terminal 12 calculates the measurement value using the measurement sample values for the left m and the right m. Further, in the long DRX cycle after the occurrence of the event, the wireless terminal 12 calculates a measurement value using the measurement sample values at the first m and the second m from the left. In addition, the wireless terminal 12 calculates a measurement value using the measurement sample values at the third m and the fourth m from the left.

  In addition, after the event occurs, the number of measurements in the long DRX cycle is greater than before the event occurs. For example, in FIG. 7, the number of measurements is 2 before the event occurs, but is 4 after the event occurs. This is because the number of measurements is increased and the accuracy of measurement evaluation is increased to camp on an appropriate cell so that event information can be appropriately notified to the base station. In addition, when the wireless terminal 12 determines that the connection to the previous cell cannot be made according to the measurement after the event occurrence, the wireless terminal 12 performs cell selection and tries to detect a new cell. Further, when transmitting the UL data for the event, the wireless terminal 12 returns to the operation before the event occurs.

  FIG. 8 is part 2 of the timing chart of the wireless terminal. In the timing chart of FIG. 8, the measurement interval after the occurrence of the event is shorter than the timing chart of FIG. That is, FIG. 8 has a greater measurement frequency than FIG. Thereby, although the power consumption of the radio | wireless terminal 12 rises from FIG. 7, since the space | interval which averages each sample becomes short in measurement value calculation of a measurement, a measurement precision improves.

  However, in calculating measurement values of measurements, the shorter the averaging interval, the better. When the averaging interval is too short, there is a possibility that only the moment when the radio propagation condition is good is evaluated, or conversely, only the moment when the radio propagation condition is bad is evaluated. For this reason, it is necessary to keep a certain interval between samples. For example, in FIG. 7, the measurement filtering interval is ‘X / 2’, and in FIG. 8, the measurement filtering interval is ‘Y / 2’.

  The wireless terminal 12 may return to the conventional measurement interval after the event occurs. For example, the wireless terminal 12 may measure at an interval of “DRX cycle / 2” after an event occurs.

The acquisition of n for determining the measurement interval will be described. n is notified from the base station 11 by broadcast information, for example.
Specifically, after the power is turned on, the radio terminal 12 performs an initial cell search and camps on a cell having a good radio quality (suitable cell). At that time, the wireless terminal 12 performs a NAS attach procedure. When the radio terminal 12 camps on a cell, the radio terminal 12 acquires broadcast information of the cell from the base station 11 and acquires n from the acquired broadcast information. Thereby, the radio | wireless terminal 12 can calculate the space | interval of a measurement.

  As shown in FIG. 8, when changing the measurement interval before and after the occurrence of an event, the wireless terminal 12 notifies the base station 11 that the event has occurred, and the base station 11 sends a new n to the wireless terminal 12. You may make it notify. For example, the base station 11 can change n according to the type of event (for example, whether it is an emergency event).

  N may be determined in advance or may be calculated from the device ID. For example, the device ID is indicated by a 12-bit value. The wireless terminal 12 may divide its device ID by an appropriate value such as 4000, for example, and set the remainder as n.

  Also, the base station 11 can notify the radio terminal 12 of the number of measurements in the long DRX cycle using broadcast information. Further, when the base station 11 receives the event notification from the wireless terminal 12, the base station 11 can notify the number of measurements in the long DRX cycle.

FIG. 9 is a flowchart of the wireless terminal.
[Step S1] Assume that the wireless terminal 12 is turned on.
[Step S <b> 2] The control plane layer control unit 22 b receives broadcast information from the base station 11. That is, the control plane layer control unit 22b receives “n” for calculating the measurement interval.

[Step S3] The control plane layer control unit 22b performs a NAS attach procedure.
[Step S4] The control plane layer control unit 22b calculates a measurement interval from the received 'n'. The radio control unit 22a turns the communication unit 21 on and off so that the measurement is performed at intervals calculated by the control plane layer control unit 22b. The control plane layer control unit 22b averages the measured measurements and evaluates the quality.

Note that the control plane layer control unit 22b monitors paging at a timing satisfying the following expression, for example.
SFN mod T = (T div N) * (UE-ID mod N)
SFN is a system frame number. T is a DRX cycle (long DRX cycle). UE-ID is the ID of the wireless terminal. N is a value determined by the DRX cycle.

[Step S5] The application layer control unit 22c stands by for an event.
[Step S6] The application layer control unit 22c determines whether an event has occurred. If an event occurs, the application layer control unit 22c proceeds to step S7. If no event has occurred, the application layer control unit 22c proceeds to step S5.

  [Step S7] The control plane layer control unit 22b and the radio control unit 22a perform measurement with new settings and evaluate the quality. For example, as described with reference to FIG. 8, the control plane layer control unit 22b performs measurement with new settings. Note that the control plane layer control unit 22b may perform the measurement as illustrated in FIG.

FIG. 10 is a flowchart of the base station.
[Step S11] The control plane layer control unit 42b notifies the radio terminal 12 of the notification information via the radio control unit 42a. The broadcast information includes “n” for calculating the measurement interval.

[Step S12] The control plane layer control unit 42b performs a NAS attach procedure.
[Step S13] The control plane layer control unit 42b waits for an event report from the wireless terminal 12.

  [Step S14] The control plane layer control unit 42b determines whether an event report from the wireless terminal 12 has been received. When the control plane layer control unit 42b receives the event report from the wireless terminal 12, the process proceeds to step S15. If the control plane layer control unit 42b has not received an event report from the wireless terminal 12, the process proceeds to step S13.

[Step S15] The control plane layer control unit 42b notifies the wireless terminal 12 of a new “n”.
In this way, the control plane layer control unit 22b and the radio control unit 22a control the communication unit 21 to perform measurement filtering at intervals smaller than half the cycle length of the long DRX cycle in the long DRX cycle. I made it. Thereby, in order to suppress power consumption, even if it is a long DRX cycle, the radio | wireless terminal 12 can suppress the extension of a measurement, and can suppress the degradation of the accuracy of a measurement.

  In addition, after the occurrence of the event, the control plane layer control unit 22b and the radio control unit 22a increase the number of measurements in the long DRX cycle from before the event. Thereby, the radio | wireless terminal 12 can improve the quality of a measurement.

  In addition, the control plane layer control unit 22b and the radio control unit 22a are configured to make the measurement interval smaller after the event than before the event. Thereby, the radio | wireless terminal 12 can improve the quality of a measurement.

[Third Embodiment]
Next, a third embodiment will be described in detail with reference to the drawings. In the third embodiment, masking is performed on the conventional DRX, a section in which DRX is not performed is provided, and DRX is performed periodically. Conventional DRX may be performed in the section where DRX is performed. However, in order to improve the quality of the measurement, multiple measurements are performed within the DRX cycle, and measurement filtering is performed in the DRX cycle. It may be performed at intervals smaller than half the length.

  The wireless communication system according to the third embodiment is the same as that shown in FIG. The block of the wireless terminal 12 is the same as that in FIG. 3, but the function of the control plane layer control unit 22b is different. The hardware configuration of the wireless terminal 12 is the same as that in FIG. The block of the base station 11 is the same as that in FIG. 5, but the function of the control plane layer control unit 42b is different. The hardware configuration of the base station 11 is the same as that in FIG.

  FIG. 11 is a timing chart of the wireless terminal according to the third embodiment. In FIG. 11, the long DRX cycle is a DRX cycle compared to FIG. The other parts of FIG. 11 are the same as those of FIG.

  Prior to the occurrence of an event, the wireless terminal 12 applies a mask in a DRX cycle in which no measurement is performed, and performs DRX periodically (thick line in FIG. 11). The radio terminal 12 monitors the measurement and the paging signal in the DRX cycle where no mask is applied.

  As shown in FIG. 11, the wireless terminal 12 performs measurement at an interval of “DRX cycle / n” (n> 2) in the section where the mask is not applied. Therefore, the wireless terminal 12 performs measurement filtering at the interval of “X” shown in FIG.

  The wireless terminal 12 does not mask the DRX cycle after the event occurs. That is, as shown in FIG. 11, the radio terminal 12 performs measurement and monitoring of the paging signal in each DRX cycle.

  FIG. 12 is a diagram for explaining a DRX mask pattern. The control plane layer control unit 22b of the wireless terminal 12 cancels the DRX mask in synchronization with a BCCH (Broadcasting Control Channel) modification period, which is a period for confirming the change of broadcast information.

  Double arrows A11 and A12 shown in FIG. 12 indicate BCCH modification period. The control plane layer control unit 22b releases the DRX mask at the timings of dotted lines A13 and A14 shown in FIG. For example, the control plane layer control unit 22b controls the radio control unit 22a to turn on the communication unit 21 (perform DRX) at the timings of dotted lines A13 and A14.

  Note that the alternate long and short dash line in FIG. 12 indicates a period during which the DRX cycle mask is released (period in which DRX is performed). In addition, a square and a hatched square in FIG. 12 indicate broadcast information (SIB: System Information Block) notified from the base station 11 to the radio terminal 12.

  The control plane layer control unit 22b monitors SIB1 (the diagonally upper right square in FIG. 12) or the paging signal in order to confirm whether there is a change in the broadcast information. The control plane layer control unit 22b turns on the communication unit 21 to monitor them. The control plane layer control unit 22b monitors the measurement and the paging signal using this timing. Note that the diagonally upper left diagonal square indicates the SIB whose information has been changed.

  The period for canceling the mask may be notified by broadcast information, for example, or may be determined in advance. Further, it may be calculated from the device ID of the wireless terminal 12. In addition, the wireless terminal 12 may be implemented freely.

In the above description, the mask pattern is synchronized with the BCCH modification period, but another mask pattern setting example will be described.
Example 1: The base station 11 broadcasts a masking pattern using broadcast information. For example, the base station 11 informs which DRX cycle the DRX is performed by using the broadcast information. The control plane layer control unit 22b of the radio terminal 12 releases the mask and monitors the measurement and the paging signal in the DRX cycle included in the received broadcast information. The mask release period may be notified by notification information, for example, or may be determined in advance. Further, it may be calculated from the device ID of the wireless terminal 12.

  Example 2: A masking pattern is notified by a paging signal. For example, when the radio terminal 12 camps on, the base station 11 notifies the DRX masking pattern with a paging signal.

  Example 3: When the wireless terminal 12 camps on, the location is registered in an MME (Mobility Management Entity). Location registration is performed at the NAS layer, and a NAS attach procedure is performed. The wireless terminal 12 receives the masking pattern by NAS attach accept of the NAS message transmitted / received by the NAS attach procedure.

  Example 4: Unmask DRX every time DRX is masked N times. N may be notified from the base station 11 by broadcast information, or may be determined in advance by the base station 11 and the wireless terminal 12. Further, it may be calculated from the device ID of the wireless terminal 12.

  Example 5: Based on an IMSI (International Mobile Subscriber Identity) which is an identifier of a wireless terminal, a wireless frame for canceling the DRX mask is determined. For example, the DRX mask is canceled in a radio frame in which SFN mod DRX cycle is equal to func (IMSI). func () is an appropriate function, for example, a function that outputs some value by IMSI.

FIG. 13 is a flowchart of the wireless terminal.
[Step S21] Assume that the wireless terminal 12 is turned on.
[Step S22] The control plane layer control unit 22b receives broadcast information from the base station 11.

[Step S23] The control plane layer control unit 22b performs a NAS attach procedure.
[Step S24] The control plane layer control unit 22b receives the DRX mask pattern by performing the NAS attach procedure. Note that the flowchart in FIG. 13 illustrates a processing example in the case of Example 3 described above.

  [Step S25] The control plane layer control unit 22b controls the radio control unit 22a so as to implement DRX using the received mask pattern. The radio control unit 22a turns on and off the communication unit 21 according to the control of the control plane layer control unit 22b so that the measurement and the paging signal are monitored. The control plane layer control unit 22b averages the measured measurements and evaluates the quality.

[Step S26] The application layer control unit 22c stands by for an event.
[Step S27] The application layer control unit 22c determines whether an event has occurred. If an event occurs, the application layer control unit 22c proceeds to step S28. If no event has occurred, the application layer control unit 22c proceeds to step S26.

  [Step S28] The control plane layer control unit 22b releases all masks. For example, the control plane layer control unit 22b controls the radio control unit 22a so that the measurement and the monitoring of the paging signal are performed in each DRX cycle, as shown after the event occurrence in FIG.

FIG. 14 is a flowchart of the base station.
[Step S31] The control plane layer control unit 42b notifies the radio terminal 12 of broadcast information via the radio control unit 42a.

[Step S32] The control plane layer control unit 42b performs a NAS attach procedure.
[Step S33] The control plane layer control unit 42b transmits a DRX mask pattern in accordance with the NAS attach procedure. Note that the flowchart of FIG. 14 shows an example of processing in the case of Example 3 described above.

[Step S34] The control plane layer control unit 42b waits for an event report from the wireless terminal 12.
[Step S35] The control plane layer control unit 42b determines whether or not an event report from the wireless terminal 12 has been received. When receiving an event report from the wireless terminal 12, the control plane layer control unit 42b ends the process. When the event report from the wireless terminal 12 has not been received, the control plane layer control unit 42b proceeds to step S34.

  In this way, the control plane layer control unit 42b provides a section in which DRX is not performed, and performs DRX periodically. Then, the control plane layer control unit 42b and the radio control unit 42a perform measurement filtering at intervals smaller than half the cycle length of the DRX cycle in the DRX cycle of DRX that is periodically performed. Thereby, in order to suppress power consumption, the radio | wireless terminal 12 can suppress the extension of a measurement within the DRX cycle of DRX performed periodically, and can suppress degradation of a measurement.

[Fourth Embodiment]
Next, a fourth embodiment will be described in detail with reference to the drawings. In the fourth embodiment, the base station instructs DRX to be performed next.

  The radio communication system according to the fourth embodiment is the same as that shown in FIG. The block of the wireless terminal 12 is the same as that in FIG. 3, but the function of the control plane layer control unit 22b is different. The hardware configuration of the wireless terminal 12 is the same as that in FIG. The block of the base station 11 is the same as that in FIG. 5, but the function of the control plane layer control unit 42b is different. The hardware configuration of the base station 11 is the same as that in FIG.

  FIG. 15 is a timing chart of the wireless terminal according to the fourth embodiment. FIG. 15 indicates, with respect to FIG. 11, DRX to be executed next by a paging signal. The other parts in FIG. 15 are the same as those in FIG.

  When the control plane layer control unit 22b of the radio terminal 12 camps on the cell of the base station 11, the control plane layer control unit 22b monitors the measurement and the paging signal. The base station 11 uses the paging signal to specify which DRX the wireless terminal 12 should next perform measurement and monitoring of the paging signal. The control plane layer control unit 22b performs measurement and monitoring of the paging signal with the designated DRX.

  The period during which DRX is performed may be specified by the paging signal, or may be notified by broadcast information. Further, it may be determined in advance or may be calculated from the device ID of the wireless terminal 12. Furthermore, it may be determined by implementation of the wireless terminal. For example, the base station 11 designates the start of DRX with the broadcast information, and the radio terminal 12 is implemented during the DRX period.

  Note that the base station 11 may designate the implementation of DRX by NAS. For example, the location of the wireless terminal 12 is registered with the MME when camping on. Location registration is performed at the NAS layer, and a NAS attach procedure is performed. The base station 11 designates DRX to be executed next by NAS attach accept of the NAS message transmitted / received by the NAS attach procedure. The period during which DRX is performed may be notified by the NAS attach accept or may be notified by broadcast information. Further, it may be determined in advance or may be determined by the device ID of the wireless terminal 12.

FIG. 16 is a flowchart of the wireless terminal.
[Step S41] Assume that the wireless terminal 12 is turned on.
[Step S42] The control plane layer control unit 22b receives broadcast information from the base station 11.

[Step S43] The control plane layer control unit 22b performs a NAS attach procedure.
[Step S44] The control plane layer control unit 22b receives the DRX to be executed next by executing the paging signal or the NAS attach procedure.

  [Step S45] The control plane layer control unit 22b controls the radio control unit 22a so as to implement DRX specified by the base station 11 (step S44). The control plane layer control unit 22b performs measurement by DRX and evaluates the measurement.

[Step S46] The application layer control unit 22c stands by for an event.
[Step S47] The application layer control unit 22c determines whether an event has occurred. If an event occurs, the application layer control unit 22c proceeds to step S48. If no event has occurred, the application layer control unit 22c proceeds to step S46.

  [Step S48] The control plane layer control unit 22b performs all DRX. For example, the control plane layer control unit 22b controls the radio control unit 22a so that measurement and paging signal monitoring are performed in each DRX cycle, as shown after the event occurrence in FIG.

FIG. 17 is a flowchart of the base station.
[Step S51] The control plane layer control unit 42b notifies the radio terminal 12 of the broadcast information via the radio control unit 42a.

[Step S52] The control plane layer control unit 42b performs a NAS attach procedure.
[Step S53] The control plane layer control unit 42b transmits a DRX to be executed next by executing a paging signal or a NAS attach procedure.

[Step S54] The control plane layer control unit 42b waits for an event report from the wireless terminal 12.
[Step S55] The control plane layer control unit 42b determines whether or not an event report from the wireless terminal 12 has been received. When receiving an event report from the wireless terminal 12, the control plane layer control unit 42b ends the process. When the event report from the wireless terminal 12 has not been received, the control plane layer control unit 42b proceeds to step S54.

  As described above, the control plane layer control unit 42b receives the DRX to be executed next by the paging signal or the NAS. Then, the control plane layer control unit 42b and the radio control unit 42a perform measurement filtering at intervals smaller than half the cycle length of the DRX cycle in the DRX cycle of DRX to be executed next. Thereby, the radio | wireless terminal 12 can suppress degradation of a measurement while suppressing power consumption.

[Fifth Embodiment]
Next, a fifth embodiment will be described in detail with reference to the drawings. In the fifth embodiment, two DRX cycles are set to monitor the measurement and the paging signal.

  The wireless communication system according to the fifth embodiment is the same as that shown in FIG. The block of the wireless terminal 12 is the same as that in FIG. 3, but the function of the control plane layer control unit 22b is different. The hardware configuration of the wireless terminal 12 is the same as that in FIG. The block of the base station 11 is the same as that in FIG. 5, but the function of the control plane layer control unit 42b is different. The hardware configuration of the base station 11 is the same as that in FIG.

  FIG. 18 is a timing chart of the wireless terminal according to the fifth embodiment. FIG. 18 shows a short DRX cycle and a long DRX cycle having a longer period than the short DRX cycle. The short DRX cycle is, for example, a conventional DRX cycle, and the long DRX cycle is longer than the short DRX cycle in order to suppress the power consumption of the wireless terminal 12.

  For example, the radio terminal 12 performs DRX of a short DRX cycle for a predetermined period, and then performs DRX of a long DRX cycle for a predetermined period. The wireless terminal 12 repeats these operations. The period during which DRX of the short DRX cycle and DRX of the long DRX cycle are performed is notified by broadcast information, for example.

  If the DRX cycle is simply lengthened, the interval at which the measurement is performed is also extended. Therefore, in the long DRX cycle, the control plane layer control unit 22b of the wireless terminal 12 performs the measurement at least once in the DRX interval as in the prior art. To implement. Therefore, multiple measurements can be performed within a certain DRX section. However, measurement is performed at intervals of 'long DRX cycle / n' (n> 2). Accordingly, the wireless terminal 12 performs control so that the measurement is filtered with at least an interval of “X” as shown in FIG. In addition, the control plane layer control unit 22b may perform measurement in the short DRX cycle as in the past, but at least an interval of 'short DRX cycle / 2' is provided to improve measurement accuracy. Make measurement filtering.

  For example, the wireless terminal 12 averages two measurements and calculates a measurement value of the measurement. For example, in the long DRX cycle shown in FIG. 18, the radio terminal 12 performs filtering of two sample values, m on the left side and m on the right side.

  Further, as a modification, it is obvious that the interval for performing the measurement is extended if the DRX cycle is simply lengthened. Therefore, in the long DRX cycle, neither measurement nor paging monitoring is performed at all.

In the above description, the period for performing DRX of the short DRX cycle and DRX of the long DRX cycle is notified by the broadcast information, but another example will be described.
Example 1: When the radio terminal 12 camps on, the base station 11 notifies a period for performing DRX with a paging signal.

  Example 2: The location of the wireless terminal 12 is registered with the MME when camping. Location registration is performed at the NAS layer, and a NAS attach procedure is performed. The wireless terminal 12 receives a period during which DRX is performed by NAS attach accept of a NAS message transmitted / received by the NAS attach procedure.

  Example 3: The control plane layer control unit 22b performs DRX of the short DRX cycle N times and then performs DRX of the long DRX cycle M times. The values of N and M may be notified by broadcast information, or predetermined values may be used. The control plane layer control unit 22b may calculate N and M values from the device ID of the wireless terminal 12.

  Example 4: The control plane layer control unit 22b switches the DRX cycle in conjunction with the BCCH modification period described in FIG. For example, the control plane layer control unit 22b performs DRX of a short DRX cycle every N modification boundaries (dotted lines A13 and A14 in FIG. 12). The period for performing DRX of the short DRX cycle may be notified by broadcast information, for example, or a predetermined value may be used. Further, the control plane layer control unit 22b may calculate a period for performing DRX of the short DRX cycle from the device ID of the wireless terminal 12.

  Example 5: The control plane layer control unit 22b starts DRX of a short DRX cycle with a radio frame in which SFN mod DRX cycle is equal to func (IMSI). The control plane layer control unit 22b performs DRX of a short DRX cycle in consecutive N radio frames. N may be notified by broadcast information, for example, or a predetermined value may be used. Further, the control plane layer control unit 22b may calculate N from the device ID of the wireless terminal 12. When the DRX of the short DRX cycle ends, the control plane layer control unit 22b performs the DRX of the long DRX cycle.

FIG. 19 is a flowchart of the wireless terminal.
[Step S61] Assume that the wireless terminal 12 is turned on.
[Step S62] The control plane layer control unit 22b receives broadcast information from the base station 11.

[Step S63] The control plane layer control unit 22b performs a NAS attach procedure.
[Step S64] The control plane layer control unit 22b acquires a period for performing DRX of a short DRX cycle and DRX of a long DRX cycle, for example, by NAS attach accept. Note that the control plane layer control unit 22b may acquire a period for performing DRX of the short DRX cycle and DRX of the long DRX cycle from the broadcast information.

  [Step S65] The control plane layer control unit 22b controls the radio control unit 22a to perform DRX in the short DRX cycle and the long DRX cycle specified by the base station 11 (step S64). The control plane layer control unit 22b performs measurement by DRX and evaluates the measurement.

FIG. 20 is a flowchart of the base station.
[Step S71] The control plane layer control unit 42b notifies the radio terminal 12 of the broadcast information via the radio control unit 42a.

[Step S72] The control plane layer control unit 42b performs a NAS attach procedure.
[Step S73] The control plane layer control unit 42b transmits a period in which DRX of the short DRX cycle and DRX of the long DRX cycle are performed, for example, by performing the broadcast information or the NAS attach procedure.

  As described above, the control plane layer control unit 42b performs DRX in the short DRX cycle and the long DRX cycle. As a result, the radio terminal 12 can suppress power consumption by the long DRX cycle and improve the accuracy of the measurement by the short DRX cycle.

[Sixth Embodiment]
Next, a sixth embodiment will be described in detail with reference to the drawings. In the sixth embodiment, after the wireless terminal 12 is turned on, the NAS attach procedure and the NAS detach procedure are performed. Thereafter, the wireless terminal 12 turns off the power of the communication unit 21. Thereafter, when an event is detected in the application layer, the radio terminal 12 performs measurement and monitoring of the paging signal by DRX, and transmits event information to the base station 11 by UL, for example.

  The radio communication system according to the sixth embodiment is the same as that shown in FIG. The block of the wireless terminal 12 is the same as that in FIG. 3, but the function of the control plane layer control unit 22b is different. The hardware configuration of the wireless terminal 12 is the same as that in FIG. The block of the base station 11 is the same as that in FIG. 5, but the function of the control plane layer control unit 42b is different. The hardware configuration of the base station 11 is the same as that in FIG.

  FIG. 21 is a timing chart of the wireless terminal according to the sixth embodiment. An arrow A21 in FIG. 21 indicates execution of the NAS attach procedure, and an arrow A22 indicates execution of the NAS detach procedure. When the power is turned on, the wireless terminal 12 performs a cell search, and performs a NAS attach procedure to perform location registration as indicated by an arrow A21. Then, the wireless terminal 12 executes the NAS detach procedure as indicated by an arrow A22 and turns off the power of the communication unit 21.

  When the application layer control unit 22c of the wireless terminal 12 detects an event that has occurred in the application layer, the application layer control unit 22c notifies the control plane layer control unit 22b accordingly. The control plane layer control unit 22b controls the radio control unit 22a so as to turn on the communication unit 21.

  The control plane layer control unit 22b performs the NAS attach procedure and performs location registration as indicated by an arrow A23. The control plane layer control unit 22b performs DRX in a short DRX cycle, and performs measurement and monitoring of the paging signal.

  The control plane layer control unit 22b transmits the event information as UL data to the base station 11, and performs the NAS detach procedure as indicated by an arrow A24. Then, the control plane layer control unit 22b turns off the power of the communication unit 21.

The control plane layer control unit 22b performs the same operation as described above when an event is detected by the application layer control unit 22c.
FIG. 22 is a diagram for explaining operations of the NAS attach procedure and the NAS detach procedure.

[Step S81] The control plane layer control unit 22b of the wireless terminal 12 transmits a NAS attach request to the base station 11.
[Step S82] The control plane layer control unit 42b of the base station 11 transmits a NAS attach accept to the wireless terminal 12.

[Step S83] The control plane layer control unit 22b of the wireless terminal 12 transmits NAS attach complete to the base station 11.
[Step S84] The control plane layer control unit 22b of the wireless terminal 12 transmits a NAS detach request to the base station 11.

[Step S85] The control plane layer control unit 42b of the base station 11 transmits a NAS detach accept to the wireless terminal 12.
FIG. 23 is a flowchart of the wireless terminal.

[Step S91] Assume that the wireless terminal 12 is turned on.
[Step S92] The control plane layer control unit 22b performs a NAS attach procedure and a NAS detach procedure. For example, arrows A21 and A22 shown in FIG. 21 are performed.

[Step S93] The application layer control unit 22c stands by for an event.
[Step S94] The application layer control unit 22c determines whether an event has occurred. If an event occurs, the application layer control unit 22c proceeds to step S95. If no event has occurred, the application layer control unit 22c proceeds to step S93.

[Step S95] The radio control unit 22a turns on the communication unit 21 according to the control of the control plane layer control unit 22b.
[Step S96] The control plane layer control unit 22b operates DRX.

[Step S97] The control plane layer control unit 22b performs a NAS attach procedure.
[Step S98] The communication unit 21 transmits event information to the base station 11 in the UL.

[Step S99] The control plane layer control unit 22b performs a NAS detach procedure.
FIG. 24 is a flowchart of the base station.

[Step S101] The control plane layer control unit 42b performs a NAS attach procedure.
[Step S102] The control plane layer control unit 42b communicates with the radio terminal 12 via the radio control unit 42a and the communication unit 41.

[Step S103] The control plane layer control unit 42b performs a NAS detach procedure. The above process is the same before and after the event.
In this manner, the control plane layer control unit 42b controls the radio control unit 22a to perform DRX in conjunction with event detection of the application layer control unit 22c. Thereby, the radio | wireless terminal 12 can suppress the power consumption before event generation | occurrence | production.

  The above merely illustrates the principle of the present invention. In addition, many modifications and changes can be made by those skilled in the art, and the present invention is not limited to the precise configuration and application shown and described above, and all corresponding modifications and equivalents may be And the equivalents thereof are considered to be within the scope of the invention.

1 wireless terminal 1a communication unit 1b control unit

Claims (8)

In a wireless terminal that performs wireless communication with a base station,
A communication unit for monitoring the paging signal of the base station;
The first NAS (Non-Access Stratum) message is used to receive information about the first section from the base station, and the communication unit is controlled so that the monitoring cannot be performed in the first section. A control unit capable of controlling the communication unit to perform the monitoring in a second section different from the first section,
The control unit further receives a message different from the first NAS message from the base station, and performs control to implement the control of the second section.
A wireless terminal characterized by that. The communication unit is capable of performing radio measurement of a signal from the base station,
2. The control unit according to claim 1, wherein the control unit performs control so that the wireless measurement cannot be performed in the first section, and performs control so as to perform the wireless measurement in the second section. The wireless terminal described in 1.   The wireless terminal according to claim 1, wherein the message is a second NAS message different from the first NAS message or the paging signal.   The wireless terminal according to any one of claims 1 to 3, wherein the information about the first section is information about a length of the first section.   The wireless terminal according to any one of claims 1 to 4, wherein the first NAS message is an accept message that responds to a request message of a NAS layer. In a wireless communication system including a wireless terminal and a base station that performs wireless communication with the wireless terminal,
The wireless terminal is
A communication unit for monitoring the paging signal of the base station;
The information on the first section is received from the base station by a NAS (Non-Access Stratum) message, and the communication unit is controlled so that the monitoring cannot be performed in the first section. A control unit capable of controlling the communication unit to perform the monitoring in a second section different from the section;
The control unit further receives a message different from the NAS message from the base station, and controls to perform the control of the second section.
A wireless communication system. In a base station that performs wireless communication with a wireless terminal,
A communication unit that transmits information on the first section set in the wireless terminal to the wireless terminal by a NAS (Non-Access Stratum) message;
The first section is a section in which communication can be controlled so that the wireless terminal does not monitor a paging signal, and a second section different from the first section is the monitor in the wireless terminal. In addition, the wireless terminal that transmits and receives a message different from the NAS message performs control of the second section.
A base station characterized by that. In a wireless communication method in a wireless terminal and a base station that performs wireless communication with the wireless terminal,
The wireless terminal is
The first section is set according to the information received from the base station in a NAS (Non-Access Stratum) message, and the paging signal of the base station is not monitored in the first section. In a second section different from the first section, the communication is controlled to perform the monitoring,
Receiving a message different from the NAS message from the base station, and controlling communication so as to implement the control of the second interval;
A wireless communication method.

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