CN101547501B

CN101547501B - Method and device for collocating discontinuous receiving cycle starting point

Info

Publication number: CN101547501B
Application number: CN2008101025706A
Authority: CN
Inventors: 谌丽; 李国庆; 高卓; 赵训威
Original assignee: China Academy of Telecommunications Technology CATT
Current assignee: China Academy of Telecommunications Technology CATT; Datang Mobile Communications Equipment Co Ltd
Priority date: 2008-03-24
Filing date: 2008-03-24
Publication date: 2012-05-23
Anticipated expiration: 2028-03-24
Also published as: CN101547501A

Abstract

The invention discloses a method for collocating a discontinuous receiving cycle starting point, including the following steps: offsets of the starting points of the DRX cycles of all users in a long-term evolution item time division multiplexing (LTE TDD) wireless frame are obtained, and the offsets of different users are distributed on a downlink subframe of the LTE TDD wireless frame; and the offsets of the starting points of the DRX cycles are sent to a corresponding user terminal. The invention also discloses a device for collocating a discontinuous receiving cycle starting point. The scheme of the invention enables the time for a plurality of terminals to start up the DRX to be evenly distributed on all downlink subframes in an LTE TDD system, thereby the equilibrium of the utilization ratio of downlink dispatching and downlink resources can be achieved.

Description

Method and device for configuring discontinuous reception cycle starting point

Technical Field

The present invention relates to the field of mobile communication technologies, and in particular, to a method and an apparatus for configuring a Discontinuous Reception (DRX) cycle start point.

Background

In a Long Term Evolution (LTE) system of 3GPP, a Discontinuous Reception (DRX) technique is introduced in a Radio Resource Control (RRC) connected state. DRX means that the terminal discontinuously receives downlink scheduling and downlink data, and when the downlink data does not need to be received, the terminal can be in a sleep state, and a radio frequency unit or even other processing units of the terminal can not work, thereby achieving the purpose of saving power.

The principle of the periodic configuration of DRX is shown in fig. 1. Each DRX cycle begins with entering a short continuous reception state, called an on duration, which typically lasts for one to several downlink subframes. In the monitoring period, the terminal continuously monitors a Physical Downlink Control Channel (PDCCH) to see whether there is a downlink scheduling signaling for the terminal, and receives downlink data according to the PDCCH. If the terminal receives downlink scheduling and downlink data during the monitoring period, starting other timers to carry out a subsequent scheduling process; but if the terminal does not receive the downlink scheduling and downlink data during the listening period, it will enter a sleep state, and will not receive the scheduling signaling and downlink data again until the listening period at the starting position of the next DRX cycle.

During the DRX cycle, the terminal has a first opportunity to receive downlink scheduling and downlink data during the listening period. If the starting point of the DRX cycle is not configured reasonably and the starting points of the DRX cycles of the multiple terminals coincide, the multiple terminals enter the monitoring period at the same time, the duration of the monitoring period is limited, and the base station is likely to be short of scheduling all the terminals, so that delay will be caused by data of part of the terminals. At other times, because all terminals are in a dormant state, the base station cannot schedule downlink data, which causes waste of downlink resources. Such resource utilization imbalance due to the unreasonable setting of the DRX cycle start point is shown in fig. 2. There are four terminals, UE1, UE2, UE3, and UE4, respectively, whose DRX cycle starts at the same point. The upper part of fig. 2 shows user data that has been stored in the Buffer (Buffer) of the base station (eNB) before the scheduling time, for example, before the first scheduling time, there are data blocks 1 to 4 in the Buffer, which are data of UEs 1 to 4, respectively. The middle part of fig. 2 is used to represent the actual scheduling capability of the base station, where the abscissa is time t, each interval represents one TTI, a listening period (on duration) occupies several TTIs, and the ordinate is frequency resources, where the time-frequency resources in the listening period in fig. 2 carry 3 Radio Bearers (RBs), and each radio bearer corresponds to data of one user terminal. Therefore, the base station can only schedule data of three terminals in the listening period, so that in the first DRX cycle, the UE4 does not receive downlink scheduling signaling, and its user data, i.e. data block 4, can only be scheduled with a delay until the next DRX cycle. When the second DRX cycle is reached, the UE3 cannot receive the downlink scheduling signaling, and the user data of the UE3 can be scheduled after delaying for only one DRX cycle.

In order to solve the above problem in an LTE Frequency Division Duplex (FDD) system, a DRX cycle start point is made uniform in each subframe, an initial position of a DRX cycle of a terminal is determined based on a subframe number, and the DRX cycle start point is set as a standard

[ (SFN × 10) + subframe number ] MOD (current DRX cycle value) ═ DRX cycle start offset (1)

Wherein,

SFN is system frame number, with one frame number every 10ms (i.e. one radio frame);

the offset of the starting point of the DRX period is a value special for each terminal, and the base station informs the terminal of the offset, wherein the value range is [0, DRX period ];

by the formula (1), the uniform distribution of all downlink subframes of the DRX period starting points of different users in the DRX period can be realized. Therefore, the balance of downlink scheduling and the balance of resource utilization rate are achieved, as shown in fig. 3, the monitoring time periods of the terminals are different from each other, and the base station can effectively configure the terminals.

However, the above-mentioned manner of configuring the DRX cycle start point is not suitable for the LTE Time Division Duplex (TDD) system. LTE TDD is a time division duplex system, and its frame structure is shown in fig. 4. A radio frame (radio frame) is 10ms long, and includes two half frames (half frames, each half frame includes 5 subframes (Subframe), each Subframe has a corresponding Subframe number, wherein, Subframe 1 is a special Subframe, and includes a downlink pilot sequence time slot (DwPTS), a guard time slot (GP), and an uplink pilot sequence time slot (UpPTS).

Fig. 5 shows a subframe configuration of a 5ms UL-DL subframe switching period of 2: 2. In the first half frame, subframe 0, subframe 4, and subframe 5 are downlink subframes and are indicated by downward arrows; subframe 1, subframe 2, and subframe 3 are uplink subframes and are indicated by upward arrows. According to the formula [ (SFN × 10) + subframe number ] MOD (current DRX cycle value) ═ DRX cycle start offset, the DRX cycle start of UE1 to UE4 may arrive uniformly between subframe 2 and subframe 5, and if the monitored duration is 1ms (1 subframe), one downlink subframe may schedule 2 users, then subframe 4 may only schedule two of UE1 to UE3, and the other UE data must be delayed to the next DRX cycle scheduling, and subframe 5 only needs to schedule downlink data of UE 4. It is obvious that the balance of resource utilization cannot be achieved.

Therefore, the existing DRX cycle starting point configuration method of the LTE FDD system is no longer applicable to the LTE tdd system.

Disclosure of Invention

In view of this, the embodiments of the present invention provide a method and an apparatus for configuring a DRX cycle starting point, which can be applied to an LTE TDD system.

The method for configuring the starting point of the DRX period provided by the embodiment of the invention comprises the following steps:

the base station acquires the offset of the starting point of the DRX period of each user in a long-term evolution project time division multiplexing LTETDD wireless frame, and the offsets of different users are uniformly distributed on a downlink subframe of the LTE TDD wireless frame;

and the base station sends the offset of the starting point of the DRX period to a corresponding user terminal.

The device for configuring the starting point of the DRX cycle, which is provided by the embodiment of the invention, is positioned at the side of a base station and comprises the following components:

the offset module is used for acquiring the offset of the starting point of the DRX period of each user in the LTE TDD wireless frame, and the offsets of different users are uniformly distributed on the downlink subframe of the LTE TDD wireless frame;

and a notification module for notifying the offset of the DRX period starting point obtained by the offset module to the corresponding user terminal.

According to the technical scheme, the starting point of the DRX period can only be configured on the downlink subframe, and the balance of downlink scheduling and downlink resource utilization rate of the LTE TDD system is achieved.

Drawings

FIG. 1 is a diagram of a DRX cycle of the prior art;

FIG. 2 is a diagram illustrating resource utilization imbalance caused by unreasonable DRX cycle start point settings;

fig. 3 is a diagram illustrating a DRX cycle start configuration of an LTE FDD system according to the prior art;

fig. 4 is a diagram of an LTE TDD frame structure;

fig. 5 is a schematic diagram of an uplink and downlink subframe switching period of an LTE TDD frame with UL: DL being 2: 2;

FIG. 6 is a flowchart illustrating a configuration of a starting point of a DRX cycle according to a first embodiment of the present invention;

FIG. 7 is a block diagram of an apparatus for configuring a starting point of a DRX cycle of a wireless frame according to a first embodiment of the present invention;

FIG. 8 is a flowchart illustrating a DRX cycle start configuration according to a second embodiment of the present invention;

FIG. 9 is a block diagram of an apparatus for configuring a starting point of a wireless frame DRX cycle according to a second embodiment of the present invention.

Detailed Description

The reason that the existing DRX cycle starting point configuration method for LTE FDD cannot be applied to the LTE TDD system is that the configuration method does not consider the downlink subframe distribution characteristics of the LTE TDD system, and configures part of DRX cycle starting points of the UE in uplink subframes, where downlink scheduling signaling obviously cannot be issued, so that the configuration of the part can be considered as invalid.

Aiming at the distribution characteristics of downlink subframes of an LTE TDD system, the embodiment of the invention provides a configuration method of a DRX period starting point, wherein the DRX period starting point can only be positioned in the downlink subframes; preferably, the DRX cycle start points of different users are uniformly distributed in each downlink subframe. It should be noted that the DwPTS in the special subframe may schedule downlink transmission, and therefore the DwPTS may be regarded as a downlink subframe.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. In the following embodiments, the radio frames are radio frames of an LTE TDD system.

The essential gist of the first embodiment of the present invention comprises: the method comprises the steps that an uplink subframe and a downlink subframe in an existing wireless frame are numbered together, the uplink subframe and the downlink subframe are numbered independently, and the result of independent numbering is called as downlink subframe numbering; setting a DRX period according to the number of the downlink subframes, namely setting the DRX period as the number of the downlink subframes included in the DRX period instead of absolute time; and determining the offset of the starting point of the DRX period of each UE according to the downlink subframe number and the DRX period.

A first embodiment of the present invention provides a procedure for implementing DRX cycle start configuration, as shown in fig. 6, including the following steps:

step 601: acquiring the number of downlink subframes in a wireless frame, and renumbering the downlink subframes in the wireless frame to obtain the downlink subframe number of each downlink subframe in the wireless frame; for example, subframes 0, 4, 5, and 9 in fig. 1 should be

downlink subframes

0, 1, 2, and 3 after renumbering.

Step 602: and for the current user to be scheduled, multiplying the frame number of a wireless frame by the number of downlink subframes of the wireless frame, and adding the downlink subframe number corresponding to the DRX starting point of the user to obtain the DRX absolute offset.

Step 603: and taking the modulus of the DRX absolute offset to the number of the downlink subframes in the DRX period to obtain the offset of the starting point of the DRX period.

Step 604: and sending the offset of the starting point of the DRX period to the user terminal.

Fig. 7 shows an apparatus for configuring a starting point of a wireless frame DRX cycle according to a first embodiment of the present invention, where the apparatus has a module structure that includes:

an offset module 701, configured to obtain an offset of a starting point of a DRX cycle of each user;

a notification module 706, configured to notify the corresponding ue of the DRX offset obtained by the offset module 701.

The offset module 701 includes:

a downlink subframe number counting unit 702, configured to count the number of downlink subframes in the radio frame, which is determined by downlink subframe configuration;

a downlink subframe number renumbering unit 703, configured to renumber downlink subframes in the radio frame, and allocate a consecutive downlink subframe number to each downlink subframe in the radio frame, where the downlink subframe number starts from 0, and the maximum value is the number of downlink subframes minus 1.

A DRX absolute offset unit 704, which, for a user to be currently scheduled, multiplies the number of downlink subframes obtained by the downlink subframe number counting unit 702 by the frame number of the radio frame, adds the product to the downlink subframe number of the downlink subframe corresponding to the DRX start point of the user obtained by the downlink subframe number renumbering unit 703, and takes the sum as the DRX absolute offset of the user;

a module taking unit 705, which takes the module of the DRX absolute offset obtained by the DRX absolute offset unit 704 to the number of downlink subframes in the DRX cycle, to obtain the offset of the starting point of the DRX cycle of the user.

The second embodiment of the present invention provides another method for implementing DRX cycle start configuration, where the following prerequisites are necessary for implementing the method: the DRX period can only be integral multiple of 10ms, namely integral multiple of the length of a wireless frame. The downlink subframe number and the DRX period are consistent with the meaning of LTE FDD.

The implementation flow of the method is shown in fig. 8, and includes the following steps:

step 801: for a user to be scheduled currently, multiplying the frame number of a current wireless frame by 10, and summing the product with the number of a downlink subframe corresponding to the DRX starting point of the user; the numbering of the downlink subframes is the result of numbering all subframes in the radio frame, such as downlink subframes 0, 4, and 5 in fig. 5. Since the length of each subframe is 1ms, the number of downlink subframes is practically equal to the time length of the downlink subframes. And the probability of being distributed on each downlink subframe is the same, so that the probability of being distributed on the downlink subframes is uniform.

Step 802: and taking the modulus of the time length of the DRX period by the summation value obtained in the step 801 to obtain the offset of the starting point of the DRX period of the user.

Step 803: and sending the offset of the starting point of the DRX period to the user terminal.

Fig. 9 shows an apparatus for configuring a starting point of a wireless frame DRX cycle according to the second embodiment, the apparatus comprising:

an offset module 901, configured to obtain an offset of a starting point of DRX of each user in an LTE TDD radio frame, where the offsets of different users are uniformly distributed on downlink subframes of the LTE TDD radio frame;

a notifying module 902, configured to notify the corresponding ue of the offset of the DRX cycle start point obtained by the offset module 901.

The offset module 901 includes:

a summing unit 902, configured to multiply, by 10, a frame number of a current radio frame by a number of a downlink subframe corresponding to a user for the user to be currently scheduled, sum the obtained product with the number of the downlink subframe corresponding to the user, and output an obtained sum result;

a modulus unit 903, which modulizes the summation result from the summation unit 902 with the time length of the DRX cycle to obtain the offset of the DRX cycle start point of the user.

The scheme of the invention can achieve the following beneficial effects: according to the characteristics of LTE TDD, a configuration scheme of starting a DRX period is redesigned on the prior basis, so that the time for starting DRX by a plurality of terminals in an LTE TDD system is uniformly distributed in all downlink subframes, and the balance of downlink scheduling and downlink resource utilization rate is achieved.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A method for configuring a starting point of a Discontinuous Reception (DRX) cycle, comprising the steps of:

acquiring the number of downlink subframes in a long term evolution project time division multiplexing LTE TDD wireless frame, and renumbering the downlink subframes in the wireless frame to obtain the downlink subframe number of each downlink subframe in the wireless frame;

for a user to be scheduled at present, multiplying the frame number of a wireless frame by the number of downlink subframes of the wireless frame, and adding the downlink subframe number corresponding to the starting point of the DRX period of the user to obtain the DRX absolute offset;

taking the modulus of the DRX absolute offset to the number of downlink subframes in the DRX period to obtain the offset of the starting point of the DRX period;

and sending the offset of the starting point of the DRX period to a corresponding user terminal.

2. The method for configuring DRX cycle start according to claim 1, wherein the downlink subframe comprises a downlink pilot sequence time slot DwPTS for scheduling downlink transmission.

3. A method of configuring a Discontinuous Reception (DRX) cycle start point,

the method is characterized in that the DRX period length is integral multiple of 10ms, and the method comprises the following steps:

for a user to be scheduled currently, multiplying the frame number of a current LTE TDD wireless frame by 10, and summing the obtained product with the number of a downlink subframe corresponding to the DRX starting point of the user;

the obtained summation value is taken to be a module of the time length of the DRX period, and the offset of the starting point of the DRX period of the user is obtained;

4. The method for configuring DRX cycle start point of claim 3 wherein said downlink sub-frame includes a downlink pilot sequence time slot DwPTS for schedulable downlink transmission.

5. An apparatus for configuring a Discontinuous Reception (DRX) cycle start point, comprising:

a notification module, configured to notify the offset of the DRX cycle starting point obtained by the offset module to a corresponding user equipment;

the offset module includes:

the downlink subframe number counting unit is used for receiving an LTE TDD wireless frame and counting the number of downlink subframes in the wireless frame;

a downlink subframe number renumbering unit, configured to renumber downlink subframes in the radio frame, and allocate a continuous downlink subframe number to each downlink subframe in the radio frame;

a DRX absolute offset unit, for the current user to be scheduled, multiplying the number of the downlink subframes obtained by the downlink subframe number counting unit by the frame number of the wireless frame, adding the product with the downlink subframe number of the downlink subframe corresponding to the starting point of the DRX period of the user obtained by the downlink subframe number renumbering unit, and taking the sum as the DRX absolute offset of the user;

and the module taking unit is used for taking the module of the DRX absolute offset obtained by the DRX absolute offset unit to the number of the downlink subframes in the DRX period to obtain the offset of the starting point of the DRX period of the user.

6. An apparatus for configuring a Discontinuous Reception (DRX) cycle start point, comprising:

the offset module includes:

the summation unit is used for multiplying the frame number of the current wireless frame by 10 for the current user to be scheduled, summing the obtained product with the number of the downlink sub-frame corresponding to the starting point of the DRX period of the user, and outputting the obtained summation result;

and the module taking unit is used for taking the module of the summation result from the summation unit to the time length of the DRX period to obtain the offset of the starting point of the DRX period of the user.