KR101837197B1 - Method and apparatus for discontinuous reception in a wireless coummnication system - Google Patents

Abstract

A method for performing a discontinuous reception (DRX) operation in a wireless communication system according to an exemplary embodiment of the present invention includes performing a DRX operation from a base station Receiving an associated parameter; Calculating an extended DRX period based on the parameter; Calculating an extended DRX start offset according to the extended DRX period based on a set counter value shared with a base station; And performing the discontinuous reception based on the extended DRX start offset and the extended DRX period. According to the present invention, an extended DRX cycle is applied to a terminal, particularly, an MTC terminal, thereby reducing unnecessary power consumption due to a paging channel search.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for performing a discontinuous reception operation in a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for performing a discontinuous reception operation in a wireless communication system, and more particularly, to a method and apparatus for enabling a discontinuous reception operation having a period longer than a discontinuous reception operation period.

The LTE (Long Term Evolution) system proposed a Discontinuous Reception (DRX) technique to solve the power problem of the UE. In the DRX mode, when there is no data to transmit / receive, the UE switches from the RRC_CONNECTED mode to the RRC_IDLE mode listening to the downlink control channel (DCCH) in order to reduce power consumption. In the RRC_IDLE mode, the UE periodically monitors a paging channel in a physical downlink control channel (PDCCH) to receive a paging signal. This period is referred to as a DRX cycle.

Meanwhile, the base station distributes the interval in which each terminal monitors the PDCCH using an offset. For example, UE # 1 wakes up at 1ms, 11ms, 21ms and attempts to receive PDCCH, and UE # 2 wakes up at 2ms, 12ms, 22ms, and attempts to receive PDCCH.

The offset is referred to as a DRX start offset in the DRX mode. That is, the terminal and the base station use the DRX start offset to determine the on-duration start point, and the DRX start offset is a parameter used to distribute the on-duration start point of the terminals located in one cell as much as possible. For example, if different DRX start offsets are assigned to a plurality of terminals having the same Long DRX cycle or Short DRX cycle, the terminals start on-duration at different points in time.

1 is a view showing a conventional DRX cycle along a time axis.

The DRX start offset, which is a transition point from the RRC_IDLE mode to the monitoring state of the PDCCH, includes a DRX cycle 103 indicating a gap between a broadcast SFN (System Frame Number) received from the base station and two consecutive active modes 101 and 102, Is determined through the modulo operation.

In this case, the DRX cycle (T) is a smaller value among the default paging cycle (T _c ) received through the broadcast from the base station and the UE-specific paging cycle (T _ue ) received through the dedicated signaling for the individual paging cycle . This is shown in Equation (1).

On the other hand, the DRX start offset can be calculated based on the broadcast SFN received from the base station. That is, the DRX start offset can be calculated through the modulo operation of SFN and DRX cycle. In this case, SFN is the number of the system frame being broadcast from the base station through the MIB.

When the DRX start offset is calculated, a paging frame (PF) is calculated through which frame to perform paging. This is shown in Equation (2). 'mod' represents a modulo operation.

In this case, N denotes a number of PFs in the paging cycle T, and N can be expressed as Equation (3).

In this case, the number of the Phasing Subframe (nPS) means how many subframes are used as a paging frame in one frame. Meanwhile, SFN satisfies the condition of Equation (4), and MAX_SFN in Equation (4) represents the maximum value of SFN.

On the other hand, Paging Occasion (PO) indicating which subframe to be paged in the determined paging frame (PF) uses a predetermined value.

On the other hand, machine to machine (M2M, MTC, hereinafter referred to as M2M / MTC) refers to communication between an electronic device and an electronic device or communication between an electronic device and a data server using a wireless communication network . In a MTC communication, a MTC (Machine Type Communication) terminal has a relatively long period in transmitting and receiving information as compared with a normal terminal. In addition, unlike ordinary terminals that are sensitive to delays such as processing voice calls, the MTC terminal has a characteristic of being insensitive to delay in transmitting and receiving information.

In addition, the MTC terminal should be characterized by extremely low power consumption. Since the DRX-related parameters used in the conventional LTE system are suitably set for the LTE terminal, if these setting values are directly applied to the MTC terminal, unnecessary power wastes.

Therefore, it is necessary to modify the DRX cycle used in the conventional LTE system so that the power consumption of the MTC terminal can be minimized.

Accordingly, the present invention provides a method and apparatus for performing a DRX operation with an extended DRX cycle than a conventional DRX cycle.

The present invention also provides DRX control method and apparatus using an extended DRX period applicable to MTC communication.

To this end, a method for performing a discontinuous reception (DRX) operation in a wireless communication system according to an embodiment of the present invention includes: receiving a DRX operation related parameter from a base station; Calculating an extended DRX period based on the parameter; Calculating an extended DRX start offset according to the extended DRX period based on a set counter value shared with a base station; And performing the discontinuous reception based on the extended DRX start offset and the extended DRX period.

A method for performing a discontinuous reception (DRX) in a wireless communication system according to another embodiment of the present invention includes receiving a DRX operation related parameter from a base station; Receiving an extended SFN consisting of upper N bits, which are set counter values shared by the base station, and lower M bits representing a frame number, from the base station; Calculating an extended DRX period based on the maximum value of the set SFN and the upper N bits; Calculating an extended DRX start offset according to the extended DRX period based on the extended DRX period and a maximum value of the set SFN; And performing the DRX operation based on the calculated DRX start offset and the extended DRX period.

A terminal for performing a discontinuous reception (DRX) operation in a wireless communication system according to an embodiment of the present invention includes a receiver for receiving a DRX operation related parameter from a base station; And calculating an extended DRX start offset based on the extended DRX period based on the set counter value shared with the base station, And a controller for performing the discontinuous reception operation based on the DRX period.

In a wireless communication system according to another embodiment of the present invention, a UE performing a discontinuous reception (DRX) operation may receive DRX operation related parameters from a base station and upper N bits and a frame number which are set counter values shared with the base station A receiver for receiving an extended SFN consisting of lower M bits; And an extended DRX start offset based on the extended DRX period based on the extended DRX period and a maximum value of the set SFN, And a controller for performing the DRX operation based on the calculated DRX start offset and the extended DRX period.

According to the present invention, an extended DRX cycle is applied to a terminal, particularly, an MTC terminal, thereby reducing unnecessary power consumption due to a paging channel search.

1 is a view showing a conventional DRX cycle along a time axis,
FIG. 2 is a diagram illustrating an extended DRX cycle according to an embodiment of the present invention along a time axis; FIG.
3 is a view for explaining a DRX mode operation principle using a counter according to an embodiment of the present invention;
FIG. 4 is a flow chart for explaining an operation procedure in a DRX mode using a counter according to an embodiment of the present invention; FIG.
FIG. 5 is a diagram for explaining Extended SFN when idle mobility is supported according to an embodiment of the present invention;
6 is a diagram for explaining a DRX mode operation principle using an Extended SFN according to an embodiment of the present invention.
FIG. 7 is a flowchart illustrating an operation in a DRX mode using an Extended SFN according to an embodiment of the present invention. FIG.
8 is a diagram for explaining a case where the MTC terminal having mobility moves from the serving base station to the target base station when the MTC mobile station is in the inactive mode;

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In the embodiment of the present invention, a DRX cycle is extended based on the LTE system and the DRX cycle is adapted to the characteristics of the MTC terminal, and the DRX cycle is enabled. However, the present invention is not limited to the LTE system, and can be applied in the same manner to various types of wireless communication systems to which the DRX operation can be applied.

Unlike ordinary communication terminals, the MTC terminal is relatively periodically transmitting and receiving data, and its period is also relatively long. Therefore, monitoring of the paging channel needs to be done with a long period.

Such a MTC terminal requires less power consumption than a normal communication terminal, and therefore needs to extend the DRX cycle in the RRC_IDLE mode.

Therefore, in the embodiment of the present invention, a method of adjusting the DRX cycle to suit the characteristics of the MTC terminal is proposed. The present invention also provides a method for adjusting the DRX period according to whether there is idle mobility of the MTC terminal.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the concept of the Extended DRX cycle according to the present invention will be described with reference to FIG. 2 is a diagram illustrating an extended DRX cycle according to an embodiment of the present invention along a time axis.

Referring to FIG. 2, the interval between the active periods 201 and 202 is represented by an extended DRX cycle 203, and the extended DRX cycle 203 is longer than the conventional DRX cycle 103 described with reference to FIG. Period. ≪ / RTI > Also, as shown in the figure, because the Extended DRX cycle 203 can be larger than the maximum value of the broadcast SFN (MAX_SFN = 10.24 sec), using the conventional method (SFN mod T) for calculating the DRX start offset DRX mode operation can not be performed. Therefore, it is necessary to implement a DRX mode operation according to an extended DRX cycle.

Hereinafter, embodiments of a DRX mode operation according to an Extended DRX cycle will be described with reference to the accompanying drawings.

First, a DRX mode operation related to an extended DRX cycle that can be applied in a situation where idle mobility is not supported will be described with reference to FIG. 3 and FIG. In an embodiment where idle mobility is not supported, a DRX mode is performed using a counter shared by the base station and the MTC terminal.

3 is a view for explaining a DRX mode operation principle using a counter according to an embodiment of the present invention.

Referring to FIG. 3, in order to perform a DRX mode operation according to an extended DRX cycle, the MTC terminal uses a DRX operation related parameter received from a base station. The DRX operation related parameters include DRX cycle, DRX start offset, and counter table index information. Counter Table Index information refers to Index value of preset Counter Table to efficiently transmit Counter value according to Extended DRX cycle. MTC terminal receives Counter Table Index through dedicated signaling and responds to Index in Counter Table The extended DRX cycle is enabled.

Extended DRX cycle can be calculated based on DRX cycle (T) and value (f _c (Index)) corresponding to counter table index. An example of calculating the Extended DRX cycle is shown in Equation (5).

On the other hand, the base station and the MTC terminal increase the MAX_SFN_Counter value initialized to 0 at the time of initial connection, one by one whenever the SFN is equal to the MAX_SFN set. The MAX_SFN_Counter value is a Counter value shared by the BS and the MS. That is, in one embodiment of the present invention, the DRX mode can be performed in the Extended DRX cycle in which the conventional DRX cycle is extended by using the MAX_SFN_Counter value.

Meanwhile, in order for the MTC terminal to perform paging, it is necessary to know how many paging frames (PF) are located in MAX_SFNs and how many frames in a corresponding MAX_SFN in which paging frames are located are paging frames. That is, it is necessary to know the extended DRX start offset in order to perform on-duration in the Extended DRX cycle. A method for calculating this is shown in Equation (6).

In Equation (6), a quotient is a parameter indicating how many paging frames are located in MAX_SFN units, and the remaining is a parameter indicating a number of frames in a corresponding MAX_SFN in which a paging frame is located, to be. That is, according to an embodiment of the present invention, a DRX mode can be performed using the extended DRX start offset calculated by Equation (6).

According to the method described with reference to FIG. 3, since the base station and the MTC terminal share the MAX_SFN_Counter value, the DRX mode operation can be performed according to the extended DRX cycle without modifying the SFN.

The operation in the DRX mode according to the Extended DRX cycle as shown in FIG. 3 will be described with reference to FIG.

4 is a flowchart illustrating an operation procedure in a DRX mode using a counter according to an embodiment of the present invention.

In step 401, if the DRX mode is set after the connection between the MTC terminal and the base station, the MTC terminal proceeds to step 403 and initializes the MAX_SFN_Counter value shared with the base station to 0. [ At this time, the base station initializes the MAX_SFN_Counter value shared with the MTC terminal to zero.

In step 405, the MTC terminal receives the SFN, and then proceeds to step 407. [

In step 407, the MTC terminal compares SFN and MAX_SFN. If the SFN and the MAX_SFN are equal to each other, the process proceeds to step 409. Otherwise, the process proceeds to step 405 to continue the SFN reception.

In step 409, the MTC terminal compares the MAX_SFN_Counter value with the Quotient value of Equation (6). If the MAX_SFN_Counter value and the Quotient value are equal to each other, the process proceeds to step 411. Otherwise, the process proceeds to step 417, where the MAX_SFN_Counter value is incremented by 1, for example, and then proceeds to step 405 to continue SFN reception. Here, the MAX_SFN_Counter value is incremented by 1 for each of the MTC terminal and the base station.

In step 411, the MTC terminal calculates a DRX start offset for paging channel monitoring. That is, after calculating the SFN mod T, the process proceeds to step 413.

In step 413, the MTC terminal compares the SFN mod T value with the Reminder value in Equation (6). If the SFN mod T value and the Reminder value are equal to each other, the MTC terminal proceeds to step 415, . That is, the frame is determined as the extended DRX start offset period.

On the other hand, if it is determined in step 413 that there is no frame having the same SFN mod T value and Reminder value, the flow advances to step 405 to continue SFN reception.

Table 1 shows the operation principle of the Extended DRX cycle using the MAX_SFN_Counter as described with reference to FIG. 3 and FIG. 4 as a pseudo code.

if (SFN = MAX_SFN) then
if (MAX_SFN_Counter ≠ Quotient) then
MAX_SFN_Counter ++
elseif (MAX_SFN_Counter == Quotient) then
break
endif
endif
if (SFN mod T == Reminder) & (MAX_SFN_Counter == Quotient)
MTC Device mode = Listen
MAX_SFN_Counter = 0
else
MTC Device mode = Idle
endif

In the above, an extended DRX cycle that can be applied in a situation where idle mobility is not supported has been discussed. Hereinafter, an extended DRX cycle that can be applied in a situation supporting idle mobility will be described with reference to FIGs. 5 to 8. FIG.

In one embodiment of the present invention supporting idle mobility, an extended SFN is formed by extending a conventional SFN, and a DRX mode is performed using an extended SFN configured.

5 is a view for explaining Extended SFN when supporting idle mobility according to an embodiment of the present invention.

5, the lower 10 bits 502 of the Extended SFN are the same as the broadcast SFN used in the conventional UE. In order to implement the Extended DRX cycle, N bits 501 of the reserved bits of the MIB are used to provide a total of 10 + N bits of the SFN 503 in FIG. That is, in an embodiment supporting idle mobility, an extended SFN is formed by extending SFN conventionally used in an embodiment of the present invention, and an extended DRX cycle is implemented using the extended SFN.

The principle of operation of the Extended DRX cycle using the Extended SFN configured as shown in FIG. 5 will be described below with reference to the related drawings.

FIG. 6 is a diagram for explaining a DRX mode operation principle using an Extended SFN according to an embodiment of the present invention. Referring to FIG.

Referring to FIG. 6, the MTC terminal uses DRX operation related parameters received from the base station. The DRX operation related parameters include a DRX cycle and a DRX start offset. Meanwhile, the MTC terminal receives Extended SFN from the base station.

The extreded DRX cycle (T _ext ) can be selected within a range having a maximum value of a product of MAX_SFN, which is the maximum value expressed by SFN, and the upper N bits (MSB), of the extended SFN. This is shown in Equation (7).

On the other hand, for the DRX mode operation, the MTC terminal needs to know how many paging frames (PF) are located in MAX_SFN units and how many frames in the corresponding MAX_SFNs in which paging frames are located are paging frames. That is, it is necessary to know the extended DRX start offset in order to perform on-duration in the Extended DRX cycle. A method for calculating this is shown in Equation (8).

In Equation (8), Quotient is a parameter indicating how many paging frames are located in MAX_SFN units, and Reminder is a parameter indicating how many frames are paging frames in a corresponding MAX_SFN in which a paging frame is located.

An operation method in the DRX mode according to the Extended DRX cycle as shown in FIG. 6 will be described below with reference to FIG.

FIG. 7 is a flowchart illustrating an operation procedure in a DRX mode using an Extended SFN according to an embodiment of the present invention. Referring to FIG.

In step 701, when the DRX mode is set after the connection between the MTC terminal and the base station, the MTC terminal proceeds to step 703 and receives Extended SFN.

In step 705, the MTC terminal monitors the upper N bits value (N bits MSB) ₁₀ of the Extended SFN received from the base station and outputs N bits (N bits MSB) ₁₀ 0 ".

In step 707, the MTC terminal continues receiving Extended SFN.

In step 709, the MTC terminal compares the upper N bits value (N bits MSB) ₁₀ of the Extended SFN with the Quotient value. If, proceeding to a higher value of N bits (N bits MSB) it not, proceeds to step 711, if the ₁₀ and Quotient values are equal, and otherwise step 707 of Extended SFN to continue receiving the Extended SFN.

In step 711, the MTC terminal computes the lower 10 bits value (10 bits LSB) ₁₀ of the Extended SFN, and then proceeds to step 713.

In step 713, the MTC terminal compares the lower 10 bits (10 bits LSB) ₁₀ of the calculated Extended SFN with the Reminder value. If the lower 10 bits (10 bits LSB) ₁₀ of the extended SFN is equal to the reminder value, the process proceeds to step 715 to perform a paging channel search in the corresponding frame. That is, the frame is determined as the extended DRX start offset period.

On the other hand, the comparison result of step 713, if the lower 10 bits value (10 bits LSB) of the SFN ₁₀ and Extended Reminder value is the same frame as the process goes to step 707 and continues to receive the Extended SFN.

For the MRX mode operation in the MTC terminal, if the lower 10 bits (10 bits LSB) ₁₀ of the extended SFN is equal to the MAX_SFN at the time of the Extended SFN transmission for the MRX mode operation, MSB) ₁₀ is incremented by one and then transmitted.

Table 2 shows the operation principle of the extended DRX cycle using the Extended SFN as described with reference to FIGS. 5 to 7 by the pseudo code.

if ((10 bits LSB) 10 == Reminder) & ((N bits MSB) 10 == Quotient)
MTC Device mode = Listen
else
MTC device mode = Idle
endif

8 is a diagram for explaining a case where the MTC terminal having mobility moves from the serving base station to the target base station when the mobile terminal is in the inactive mode.

When the MTC terminal 802 having mobility is in the inactive mode and moves from the serving base station 801 to the target base station 803 (804), a new MIB is received from the target base station instead of the MIB received from the serving base station .

In order to determine whether a parameter received from the serving BS, that is, a DRX cycle or a DRX start offset, or a parameter for a DRX operation from the target BS is newly allocated when the Extended DRX cycle used for each BS is different, Value. Hereinafter, the set value is referred to as wrap around window. The size of the wrap around windows can be adjusted to the state and traffic characteristics of the MTC service system.

If the difference between the two SFNs, that is, the difference between the SFNs of the serving BS and the target BS, is greater than the wrap around windows, the MTC mobile station reallocates the DRX cycle, offset, and Extended SFN from the target BS. Equation (9) represents this operation.

then, receive new parameter from target eNB

Here, the new SFN means the maximum period that can be expressed by the SFN to be received from the target base station in the idle mobility. The new SFN can be represented by 2 ^ (the number of bits of the SFN received from the target base station) since the size of the period that can be extended is determined according to the number of bits of the Extended SFN. The expected SFN means the maximum period that can be expressed as SFN that can be received from the serving base station in the idle mobility. The expected SFN can be expressed as 2 ^ (the number of bits of the extended SFN received from the serving base station).

On the other hand, if the difference between the two SFNs, that is, the difference between the serving BS and the SFN of the target BS is smaller than or equal to the wrap around windows, the MTC UE does not need to allocate the DRX cycle, And can operate using the received DRX cycle, offset, and Extended SFN. Equation (10) represents this operation.

then, using parameter received from serving eNB

The terminal and the base station apparatus according to the embodiments of the present invention respectively include a transmitter / receiver for transmitting / receiving various parameters for controlling the DRX mode operation, a controller for controlling the DRX mode operation described with reference to FIGS. 2 to 8 May be implemented.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention.

Claims (13)

A method for performing a discontinuous reception (DRX) operation in a wireless communication system,
Receiving a DRX operation related parameter from a base station;
Calculating an extended DRX period based on the parameter;
Determining a frame to perform the discontinuous reception operation on the basis of the extended DRX period and a maximum value of the SFN,
Wherein determining the frame comprises:
Dividing the extended DRX period by a maximum value of the SFN to obtain a first specific value and a second specific value corresponding to the quotient and the remainder,
And determining the frame by the obtained first specific value and second specific value. 2. The method of claim 1, wherein the DRX operation-
At least one of the DRX cycle, the DRX start offset, and the counter table index information
/ RTI > 3. The method of claim 2, wherein calculating the extended DRX period comprises:
Calculating the extended DRX period based on the DRX period and the counter table index information
/ RTI > 2. The method of claim 1, wherein obtaining the first specific value and the second specific value comprises:
Modulating the extended DRX period with a maximum value of the SFN to obtain the first specific value (Reminder)
And subtracting the first specific value from the extended DRX period and dividing the result by the maximum value of the SFN, as the second specific value. delete A method for performing a discontinuous reception (DRX) operation in a wireless communication system,
Receiving a DRX operation related parameter from a base station;
Receiving an extended SFN consisting of upper N bits, which are set counter values shared by the base station, and lower M bits representing a frame number, from the base station;
Calculating an extended DRX period based on the maximum value of the SFN and the upper N bits;
Calculating an extended DRX start offset according to the extended DRX period based on the extended DRX period and a maximum value of the SFN; And
And performing the DRX operation based on the calculated DRX start offset and the extended DRX period. 7. The method of claim 6, wherein the DRX operation-
A DRX period, and a DRX start offset. 7. The method of claim 6, wherein calculating the extended DRX period comprises:
Calculating the extended DRX period based on the maximum value of the SFN and the upper N bits of the extended SFN
/ RTI > 8. The method of claim 7, wherein calculating the extended DRX start offset comprises:
Comparing a first specific value and a second specific value calculated based on the extended DRX period and the maximum value of the SFN with higher N bits and lower M bits of the extended SFN; And
Determining the DRX start offset as the extended DRX start offset if the first specific value is equal to a lower M bits value of the extended SFN and the second specific value is equal to an upper N bits value of the extended SFN / RTI > 10. The method of claim 9, wherein the first specific value and the second specific value are calculated according to the following equation.
≪ Equation &
The first specific value = Text mod MAX_SFN,
Second specific value = (Text - Text mod MAX_SFN) / MAX_SFN.
(Where Text is the extended DRX period and MAX_SFN is the maximum value of the SFN) The method according to claim 6,
A DRX cycle, a DRX start offset, and an extended SFN from the target BS when the difference between the SFN provided from the serving BS and the expected SFN provided from the target BS is greater than a predetermined value,
Further comprising the step of: A terminal for performing a discontinuous reception (DRX) operation in a wireless communication system,
A receiver for receiving a DRX operation related parameter from a base station; And
And a controller for calculating an extended DRX period based on the parameter and determining a frame to perform the discontinuous reception operation based on the extended DRX period and a maximum value of the SFN,
The controller comprising:
Dividing the extended DRX period by a maximum value of the SFN to obtain a first specific value and a second specific value corresponding to the quotient and the remainder,
And determines the frame by the obtained first specific value and the second specific value. A terminal for performing a discontinuous reception (DRX) operation in a wireless communication system,
A receiver for receiving an extended SFN consisting of DRX operation related parameters from the base station and lower M bits representing upper N bits and a frame number which are set counter values shared with the base station; And
Calculates an extended DRX start offset based on the extended DRX period based on the extended DRX period and a maximum value of the SFN, And a controller for performing the DRX operation based on the calculated DRX start offset and the extended DRX period.

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