KR100788903B1 - Method and mobile station supporting sleep mode - Google Patents

Abstract

A method for supporting sleep mode and a mobile terminal for the same are provided to minimize the time delay of data and maximize power-saving by adjusting the length of the initial sleep window in consideration of a burst traffic characteristic. A mobile terminal(100) for supporting sleep mode comprises a wireless transceiver part(140) and a control part(120). The wireless transceiver part(140) calculates an initial window value according to the burst arrival interval of received downlink data and sets up the sleep window value of the mobile terminal(100) according to the calculated initial window value. The control part(120) controls the mobile terminal's access to sleep mode according to the sleep window value received from the wireless transceiver part(140). The wireless transceiver part(140) comprises a MAC processing part(141). The MAC processing part(141) controls a sleep timer and measures elapsed time from when the downlink data are received. Based on the measured value, the MAC processing part(141) determines when to access sleep mode.

Description

Method and mobile station supporting sleep mode

1 is a structural diagram illustrating a mobile terminal supporting a sleep mode according to an embodiment of the present invention.

2 is a flowchart illustrating an exemplary embodiment of a mobile terminal transitioning from an active mode to a sleep mode and ending a sleep mode according to an embodiment of the present invention.

3 is a flowchart illustrating a method of supporting a sleep mode in a mobile terminal according to an embodiment of the present invention.

The present invention relates to a power saving method of a wideband radio access system, and more particularly, to a power saving mode or a sleep mode (hereinafter, sleep) in a broadband wireless access system. General term), and a mobile terminal.

The broadband wireless access system refers to a next-generation communication method that further supports mobility in a short-range data communication method using a fixed access point like a conventional wireless LAN.

Various standards have been proposed for such a broadband wireless access system, and international standardization of a broadband wireless access system is actively progressed in IEEE 802.16e.

The conventional wireless LAN method provides a data communication method capable of wireless communication within a short distance around a fixed access point, but this does not provide mobility of a subscriber station, but only supports short-range data communication by wireless rather than wired. It had a limit. On the other hand, the broadband wireless access system provides a data communication service that is not interrupted by guaranteeing mobility even when a subscriber station moves from a cell currently managed by a base station to another cell managed by another base station.

Accordingly, in the above-described broadband wireless access system, since the battery is mainly used as a power supply means of the subscriber station, the battery use time of the subscriber station in the broadband wireless access system is a large limiting factor of the service use time. Therefore, in the mobile broadband wireless access system, in order to minimize power consumption of the terminal, all devices in the terminal support a sleep mode in which there is no operation to save power when there is no up and down traffic.

That is, in the broadband wireless access system, if there is no data transmission and reception between the base station and the terminal, the terminal stays in the sleep mode during the sleep window previously promised with the base station. After that, when the sleep window passes, the terminal transitions to the active mode, which is the normal mode, to check whether there is downlink traffic data to be transmitted to the terminal itself. After entering the active mode, the terminal enters the sleep mode again if there is no previous downlink traffic data. In this case, the sleep window length of the newly entered sleep mode varies depending on the characteristics of the service. In the case of the BE (Best Effort) service, the sleep window has an exponentially increased sleep window than the length of the previous sleep window.

Meanwhile, as the length of the sleep window increases, the time for which the terminal stays in the sleep mode increases, so that the power gain increases. However, when downlink data from the base station to the terminal occurs, the base station should buffer the terminal until the terminal exits the sleep mode. The time delay until the downlink data is actually transmitted to the terminal is lengthened, thereby lowering the quality of service felt by the user. Therefore, the power gain according to the sleep mode and the quality of service thereof are in a trade-off relationship.

In the broadband wireless access system, the sleep window relation that increases exponentially with respect to the BE service is defined.In the wireless access protocol of the broadband wireless access system such as IEEE 802.16e, any nth (n = 1, 2, 3, ...) The sleep window is calculated as in the following equation (1).

[Equation 1]

의 결과값이다. 여기서 최대 슬립 윈도우의 범위는 무선 접속 규약에서 정의하고 있으며 그 값은 슬립 모드로 인한 최대 버퍼링 시간 지연 값이므로 시스템 설계시에 시스템이 허용 가능한 최악의 시간 지연을 고려하여 결정되는 값이다. 또한, 초기 윈도우 W ₁ 의 값은 규격에서 5msec 프레임 길이를 가질 때 최대 1.275 sec 가질 수 있도록 규정되어 있다. 상기 수학식 1을 살펴보면 W ₁ 의 값에 따라 n번째 슬립 윈도우 W _n 의 길이가 달라지므로 초기 윈도우 W ₁ 의 값 조절이 슬립 윈도우 길이 조절 효과를 거둠을 알 수 있다.That is, the length of the _nth sleep window W _n is the maximum sleep window, W _F , the maximum length of a predefined sleep window, W _F , an exponential function not exceeding the length.

Is the result of. In this case, the maximum sleep window range is defined in the wireless access protocol, and the value of the maximum sleep window is the maximum buffering time delay value due to the sleep mode. In addition, the value of the initial window W ₁ is specified in the specification to have a maximum of 1.275 sec when having a 5msec frame length. Referring to the formula (1) it may be so that the n-th sleep window length W _n depends on the value of W ₁ to know the value of the initial control window W ₁ sleep window length geodum the control effect.

If so any increase the sleep window length according to the value of the initial window W ₁ increases, the power saving effect becomes more time delay due to buffering in the base station, while larger gradually increases, on the contrary, the value of W ₁ decreases the power saving effect is While gradually smaller, the time delay is gradually reduced, so the value of the initial window W ₁ is an important parameter that must be determined considering the trade-offs of power savings and time delay.

That is, the larger the initial sleep window, which is the first sleep window, the larger the exponentially increasing sleep window sizes and the faster the maximum sleep window size specified by the broadband wireless access system. The power saving effect is greater. Of course, since the buffering time delay increases as the size of the sleep windows increases, a method of determining an initial sleep window in consideration of a trade-off thereof is required.

The technical problem to be achieved by the present invention is to minimize the time delay of the data by adjusting the initial sleep window length, that is, the initial window value in consideration of the burst traffic characteristics of the terminal in the broadband wireless access system, while the power saving effect It is to provide a method and a mobile terminal to support the sleep mode to obtain the maximum.

A mobile terminal supporting a sleep mode for power saving according to a feature of the present invention for achieving the above object,

Calculating an initial window value in response to a burst arrival interval of received downlink data, wherein the burst arrival interval is a time value from the last reception of the downlink data to the last sleep mode entry before the last sleep mode entry; A radio transmitter and receiver configured to set a sleep window value of the mobile terminal in response to the initial window value; And a controller configured to control the mobile terminal to enter a sleep mode in response to the sleep window value received from the radio transceiver.

In addition, the method for the mobile terminal to support the sleep mode for power saving according to another aspect of the present invention,

Calculating a burst arrival interval of downlink data transmitted to the mobile terminal, wherein the burst arrival interval is a time value from a last reception time of downlink data to a last sleep mode entry time before the last sleep mode entry time; Calculating different initial window values corresponding to the burst arrival intervals; And controlling entering of a sleep mode and switching to an active mode in response to the initial window value.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, except to exclude other components unless otherwise stated.

Hereinafter, a method and a mobile terminal supporting a sleep mode according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In particular, the present invention relates to a sleep mode support method applicable to a BE (Best Effort) service having a burst characteristic that appears intensively at a specific time or having a non-real-time traffic characteristic.

1 is a block diagram illustrating a configuration of a mobile terminal supporting a sleep mode in a broadband wireless access system according to an exemplary embodiment of the present invention.

As shown in FIG. 1, the terminal 100 includes an interface unit 110, a control unit 120, a power supply unit 130, and a wireless transmission / reception unit 140.

The user interface 110 may be connected to the controller 120 to receive various inputs from the user or finally provide information to the user, and may be formed of a device such as a liquid crystal display device or a keypad.

The control unit 120 is equipped with various application programs for the user in accordance with the user interface unit 110 and is matched with the wireless transmission and reception unit 140 through the wireless transmission and reception unit 140 for Internet data transmitted and received by the user application program. It is a part for controlling various power saving measures in response to the sleep window value by being notified from the MAC processing unit 141 of the radio transmitter / receiver 140 to transmit / receive with the base station or the terminal enters the sleep mode.

The power supply unit 130 is a power supply unit including a battery and supplies power to all parts of the entire terminal.

The wireless transmitter / receiver 140 modulates the data transmitted from the controller 120 into a wireless RF signal and transmits the data to the base station, or receives a wireless RF signal received from the base station, demodulates the RF signal, and then transmits the demodulated data to the controller 120. And to enter the sleep mode and the end of the sleep mode. In detail, the wireless transmitter / receiver 140 includes a MAC processor 141, a physical layer unit 142, and an RF unit 143.

The MAC processing unit 141 matches with the control unit 120 to exchange user data and control data, and performs key media access control (MAC) functions such as system access, bandwidth allocation request, connection setting, and connection management. This is where it is done.

Also, the sleep timer is a part of determining the transition to the sleep mode and the return to the active mode. The sleep timer measures the elapsed time from the last received downlink packet reception time to transition from the active mode to the sleep mode. Has The MAC processor 141 uses the sleep timer to control the terminal to enter the sleep mode when downlink data is not received during the sleep timer value τ. In addition, the sleep window value of the sleep mode is set to manage the entry point of the sleep mode and the switching time of the active mode.

On the other hand, the MAC processing unit receives the last received downlink packet reception time to estimate the burst inter-arrival time of the downlink data and the time of the last instant of transition from the active mode to the sleep mode. It has a memory to store The burst arrival interval stored in the memory is used to set the initial window value when the terminal enters the sleep mode after receiving the downlink data and no other downlink data is received. That is, the MAC processor reads the burst inter-arrival time and calculates an initial window value of a sleep mode to be currently entered corresponding to the initial window value of the previous sleep mode and the burst arrival interval.

The physical layer unit 142 is a portion that matches the MAC processing unit 141 and performs channel coding / decoding and modulation / demodulation to suit the wireless channel environment for packet data transmitted and received by the MAC processing unit.

The RF unit 143 receives downlink data from the base station or transmits uplink data. That is, a station for modulating a signal transmitted from the physical layer unit 142 into a wireless RF signal and transmitting the signal to a base station or receiving a wireless RF signal received from the base station and demodulating the RF signal and then transmitting the signal to the physical layer unit 142. Do it.

A method of supporting a sleep mode, that is, entering a sleep mode, determining a sleep interval length, and ending a sleep mode in a mobile terminal having such a configuration will be described in detail with reference to the accompanying drawings.

2 is a flowchart illustrating an embodiment of a mobile terminal switching from an active mode to a sleep mode and ending a sleep mode according to an embodiment of the present invention, and FIG. 3 is a flowchart of FIG. A flowchart illustrating a method of supporting a sleep mode in a mobile terminal.

As illustrated in FIG. 2, when there is no data received until the sleep timer value τ elapses after receiving the j th packet, the mobile station in the active state transitions from the active mode to the sleep mode. At this time, the sleep timer value τ is a time value determined at the time of system design. The larger the value, the longer the operating time in the active mode without entering the sleep mode, and thus the power saving effect is reduced. Reduction improves quality of service.

3 is a flowchart illustrating a sleep mode support method of a mobile terminal 100 according to an embodiment of the present invention. As shown in FIG. 3, an initial window value W ₁ is received after downlink data is received. Each time the device enters sleep mode, it can be set to a different value.

After receiving the downlink traffic from the base station (S100), the mobile terminal maintains the active mode and enters the sleep mode when the downlink traffic does not occur during the sleep timer value (τ) (S110). In this case, the time for not receiving the downlink traffic is checked by the sleep timer included in the wireless transmitter / receiver 140 of the mobile terminal.

Meanwhile, the mobile terminal entering the sleep mode maintains the sleep mode during the initial window W ₁ corresponding to the length of the first sleep window after receiving the downlink data. At this time, when the terminal enters the sleep mode for the first time after performing the initial connection process (initial window) ( W ₁ ) uses the value set in advance between the terminal and the base station as it is, and then, downlink data When entering the sleep mode again after reception, an adaptively calculated initial window W ₁ is used.

After the terminal maintains the sleep mode for the initial window value, the terminal enters the active mode to check the presence of the buffered data (S120). At this time, if there is buffered data, the terminal receives the downlink data while maintaining the active mode. Otherwise, the terminal maintains the active mode for a predetermined time and then reenters the sleep mode (S130).

On the other hand, the time for holding the entire active mode to enter the sleep mode when the downlink traffic to the terminal is not present corresponds to the listening window (Listening Window) (W _L) of time, the length of the listening window system design Use a predetermined value for.

Meanwhile, the terminal reentering the sleep mode stays in the sleep mode for W ₂ hours, the length of the second sleep window. Thereafter, the terminal repeatedly enters the sleep mode and enters the active mode until downlink data for the terminal occurs. At this time, the value of the listening window is the same even if the active mode is repeated, but the value of the sleep window increases exponentially as the sleep mode is repeated, as shown in Equation 1 above.

Subsequently, when downlink data is transmitted to the mobile terminal entering the sleep mode, the base station buffers it (S140) and waits for the corresponding terminal to switch from the sleep mode to the active mode. After the UE switches from the sleep mode to the active mode (S150) and determines whether there is downlink data buffered by the base station, the terminal receives the downlink data through the wireless transmitter / receiver 140 without switching to the sleep mode (S160).

Thereafter, the terminal receiving the packet stays in the active state until the sleep timer value τ is exceeded, and again until the downlink packet arrives if no downlink data occurs until the sleep timer value is exceeded. One sleep mode operation is repeated (S170, S180, S190, and S200).

At this time, after the sleep timer value τ is exceeded, a new initial window value W ₁ of the mobile terminal W _{, New} Is calculated by the adaptive method as shown in Equation 2 below.

[Equation 2]

Here, W _{1, Old} means the initial initial window value, and the immediately initial initial window value means an initial window setting value before entering the current sleep mode. That is, it means the initial window value that the terminal had before receiving the downlink data last. In addition, W _{1, Max} is the maximum value of the initial window using the value defined in the radio standard. That is, W _{1, Max} is a maximum of 1.275 sec when the 5msec frame length. T _B is a burst inter-arrival time of downlink data, as shown in FIG. 2, and is the last sleep mode from the last reception time of downlink data received before finally entering the sleep mode. The time value until the entry point of.

값은 버퍼링 시간의 지연 없이 가질 수 있는 이상적인 슬립 윈도우의 길이를 의미한다. α는 가중치(0.0 ≤ α≤ 1.0)로서 이동 단말이나 이동 단말이 제공하는 서비스의 종류에 따라 다르게 설정이 가능하다. 즉, 버스트 데이터의 버스트 도착 간격 (burst inter-arrival time)의 변화가 클 경우 가중치 α를 작게 하고, 반대로 변화가 작을 경우 가중치 α의 값을 크게 함으로써 트래픽이 가지는 버스트 데이터의 버스트 도착 간격 특성의 반영이 가능하다. therefore,

The value means the ideal sleep window length that can be obtained without a delay in the buffering time. α is a weight (0.0 ≦ α ≦ 1.0) and can be set differently according to the type of service provided by the mobile terminal or the mobile terminal. In other words, when the change in burst inter-arrival time of burst data is large, the weight α is decreased, and when the change is small, the weight α is increased to reflect the burst arrival interval characteristic of the burst data of traffic. This is possible.

값과 유사한 값을 가지는 경향을 가지게 된다. 만약 가중치 α의 값이 1.0일 경우 초기 윈도우의 값은 적응형(adaptive) 값이 아닌 항상 일정한 상수 값을 가지게 된다.On the other hand, if the value of α is large, the new initial window value W _{1 , New} Has a value similar to the previously used initial window values W _{1 , Old,} and if the values are small, W _{1 , New} Measured ideal slip window length

It will tend to have a value similar to the value. If the value of the weight α is 1.0, the initial window value is always a constant value, not an adaptive value.

The method for obtaining the initial window value by Equation 2 described above is particularly suitable for web browsing, which is a typical service of the BE service. This means that when web browsing traffic downloads a web page designated by a user, the down data is received to the terminal bursty, and when one web page is downloaded, the time when the user reads the loaded data. This is because no further downlink data is generated during the reading time.

값 참조의 비율을 조절한다. 즉, 버스트 도착 간격의 변화율이 커지면 초기 윈도우 값의 버스트 도착 간격에 대한 의존도를 높이고, 버스트 도착 간격의 변화율이 작은 경우에는 사전에 설정된 초기 윈도우 값과 유사한 초기 윈도우 값을 가지도록 설정한다.Ideally, when the mobile terminal enters the sleep mode during the reading time, if the mobile terminal has the initial size of the maximum size, the maximum sleep window W _F may be reached in the shortest time, thereby increasing the time to stay in the sleep mode. In addition, by determining the current initial window value by adjusting the weight α, the value of the previous initial window and the measured ideal sleep window length

Adjust the ratio of value references. That is, when the change rate of the burst arrival interval increases, the dependence of the initial arrival window value on the burst arrival interval is increased, and when the change rate of the burst arrival interval is small, the initial window value similar to the preset initial window value is set.

Through such characteristics, the sleep mode support apparatus and method reflecting the burst arrival interval characteristics of burst data can adjust the sleep window according to the burst traffic characteristics, thereby minimizing the transmission time delay of the downlink data and increasing the power saving effect. In addition, since the sleep mode of the terminal is not centrally managed by the base station, each terminal separately manages its own sleep window value, etc., so that difficulties in centralized management and complicated base station structure can be avoided. have.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

According to an embodiment of the present invention, a method for supporting a sleep mode reflecting a burst arrival interval characteristic of burst data and a mobile terminal adjusts an initial window value according to the burst traffic characteristic, thereby minimizing a transmission time delay of downlink data and saving power. The effect can be enhanced.

In addition, since it is a distributed method of computing each terminal separately from the centralized type managed by one base station, it is possible to avoid the difficulty of the centralized management and the complexity of the base station structure.

Claims (10)

In a mobile terminal supporting a sleep mode for power saving, Calculating an initial window value in response to a burst arrival interval of received downlink data, wherein the burst arrival interval is a time value from the last reception of the downlink data to the last sleep mode entry before the last sleep mode entry; A radio transmitter and receiver configured to set a sleep window value of the mobile terminal in response to the initial window value; And Control unit for controlling the mobile terminal to enter the sleep mode in response to the sleep window value received from the radio transmitter and receiver A mobile terminal comprising a. The method of claim 1, The wireless transmission and reception unit includes a MAC processing unit, The MAC processing unit, And a time elapsed since the reception of the downlink data by using a sleep timer, and determines the entry time of the sleep mode in response to a sleep timer value. The method of claim 2, And if downlink data is not received, the radio transmitter / receiver increases exponentially a sleep window value when the mobile station needs to repeat entering the sleep mode. In the method for the mobile terminal to support the sleep mode for power saving, Calculating a burst arrival interval of downlink data transmitted to the mobile terminal, wherein the burst arrival interval is a time value from a last reception time of downlink data to a last sleep mode entry time before the last sleep mode entry time; Calculating different initial window values corresponding to the burst arrival intervals; And Controlling entering into a sleep mode and switching to an active mode in response to the initial window value Sleep mode support method comprising a. The method of claim 4, wherein After receiving the downlink data, the mobile station enters a sleep mode when no other downlink data is received during a sleep timer value, and the first sleep window value of the sleep mode is the same as the initial window value. How to support the mode. The method of claim 5, The controlling of entering the sleep mode and switching to the active mode may include: Maintaining a sleep mode corresponding to the initial window value; Switching from the sleep mode to an active mode; And Re-entering the sleep mode if there is no transmission of downlink data to the mobile terminal; Including, The sleep window value when re-entering the sleep mode increases exponentially in response to the initial window value. The method of claim 6, In calculating the initial window value, And the initial window value is calculated by updating a previous initial window value set in correspondence to the burst arrival interval until the current initial window value is calculated. The method of claim 4, wherein And the downlink data has a burst traffic characteristic. The method of claim 7, wherein The initial window value is a sleep mode support method, characterized in that as the rate of change of the burst arrival interval increases, the dependency of the burst arrival interval increases. The method of claim 9, The initial window value is expressed as

Determined by Where W _{1, Old} is the previous initial window value, W _{1, Max} is the maximum value of the initial window value, T _B is the burst arrival interval, τ is the sleep timer value, α is a sleep mode support Way.

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