Terminal, method, and wireless communication for power saving

Provided are a terminal for power saving, a power saving method of the terminal, and a wireless communication system for power saving. A receiving terminal may receive scheduling information associated with data transmission and reception of a transmitting terminal. The receiving terminal may directly communicate with the transmitting terminal by referring to the scheduling information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2010-0002482, filed on Jan. 12, 2010, Korean Patent Application No. 10-2010-0011211, filed on Feb. 5, 2010, and Korean Patent Application No. 10-2010-0131493, filed on Dec. 21, 2010, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to a terminal, method, and wireless communication system for power saving, and more particularly, a terminal for power saving that may save a power of a terminal enabling a wireless communication, a power saving method of the terminal, and a wireless communication system for power saving of the terminal.

2. Description of the Related Art

In a wireless communication system, terminals may directly communicate with each other without using a base station or an access point (AP). However, when the terminals directly communicate with each other, the terminals may be unaware of when a counter party terminal transmits data. Accordingly, in order to receive data, the terminals may need to wait in a wake-up state until the counter party terminal transmits the data. That is, in a direct communication mode, the terminals may not operate in a power saving manner.

SUMMARY

An aspect of the present invention provides a terminal, method, and wireless communication system for power saving that may perform direct communication by applying a power saving scheme and thereby reduce a power consumption when terminals directly communicate with each other.

According to an aspect of the present invention, there is a terminal for power saving, including: a communication unit to receive scheduling information for data transmission and reception of at least one external terminal; and a control unit to control the communication unit to directly communicate with the at least one external terminal by referring to the received scheduling information.

The scheduling information may include information associated with a transmission to interval for transmitting data, and the control unit may operate in a sleep mode in an interval excluding the transmission interval.

The control unit may operate in a receive mode in the transmission interval and may control the communication unit to receive the data from the at least one external terminal.

The communication unit may perform an initialization for a direct communication with the at least one external terminal by transmitting a request message for requesting the direct communication to a control apparatus controlling an operation of the at least one external terminal, and by receiving, from the control apparatus, a response message indicating that the at least one external terminal accepts the direct communication.

The scheduling information may be provided from the at least one external terminal.

The scheduling information may be provided from a base station or an access point.

The scheduling information may be provided from the control apparatus after authentication and association establishment with a control apparatus controlling an operation of the at least one external terminal is completed.

According to another aspect of the present invention, there is provided a power saving method of a terminal, the method including: receiving scheduling information for data transmission and reception of at least one external terminal; and directly communicating with the at least one external terminal by referring to the received scheduling information.

According to still another aspect of the present invention, there is provided a wireless communication system for power saving of a terminal, including: a first terminal to transmit data based on scheduling information for data transmission and reception; and a second terminal to share the scheduling information of the first terminal, and to receive the data through a direct communication with the first terminal by referring to the scheduling information.

The wireless communication system may further include a control apparatus to provide scheduling information of the first terminal to the first terminal and the second terminal.

According to embodiments of the present invention, when at least two terminals directly communicate with each other, the at least two terminals may operate by referring to scheduling information used for transmitting data, and thereby may reduce a power consumption.

According to embodiments of the present invention, a terminal may be aware in advance of information associated with a time when another terminal transmits data and thus, the terminal may operate in a sleep mode in a time interval where the other terminal does not transmit data and thereby may reduce a power consumption.

According to embodiments of the present invention, a control apparatus such as a base station may generate scheduling information associated with data transmission and reception.

DETAILED DESCRIPTION

When it is determined detailed description related to a related known function or configuration they may make the purpose of the present invention unnecessarily ambiguous in describing the present invention, the detailed description will be omitted here. Also, terms used herein are defined to appropriately describe the exemplary embodiments of the present invention and thus may be changed depending on a user, the intent of an operator, or a custom. Accordingly, the terms must be defined based on the following overall description of this specification.

FIG. 1is a diagram illustrating a wireless communication system for power saving of a terminal according to an embodiment of the present invention.

Referring toFIG. 1, the wireless communication system may include a control apparatus100, a first terminal200, and a second terminal300. Even though two terminals, for example, the first terminal200and the second terminal300are illustrated inFIG. 1, a number of terminals is not limited thereto.

The control apparatus100corresponds to an apparatus for controlling an operation of the first terminal200and the second terminal300, and may be, for example, a base station or an access point (AP).

The first terminal200and the second terminal300correspond to apparatuses for transmitting and receiving of data by means of a wireless communication. Accordingly, the first terminal200and the second terminal300may directly communicate with each other without using the control apparatus100. The direct communication corresponds to a communication where the first terminal200and the second terminal300directly transmit and receive data without an intervention of the control apparatus100.

Hereinafter, an initialization process for the direct communication will be described.

For the direct communication, the first terminal200may transmit, to the control apparatus100, a request message for requesting the direct communication with the second terminal300. When the first terminal200performs the direct communication, the request message may include capability information notifying whether a support for power saving is available.

The control apparatus100may transmit, to the second terminal300, the request message received from the first terminal200. Based on the capability information included in the received request message, the control apparatus100may generate a new request message requesting the direct communication. The request messages may include details of the first terminal200requesting the direct communication with the second terminal200. The control apparatus100may transmit one of the request messages to the second terminal300.

The second terminal300may transmit, to the control apparatus100, a response message with respect to the request message received from the control apparatus100. The control apparatus100may transmit, to the first terminal200, the response message received from the second terminal300. The response message corresponds to a message responding to the request for the direct communication, and may include capability information indicating whether the direct communication is available.

When the capability information indicating whether the second terminal300may perform the direct communication is included in the response message, the initialization process for the direct communication may be completed. Accordingly, the first terminal200and the second terminal300may operate in a direct communication mode where the first terminal200and the second terminal300may perform the direct communication, and may operate in a sleep mode or in a transmit mode based on scheduling information.

As described above with reference toFIG. 1, while performing the direct communication, the first terminal200and the second terminal300participating into the direct communication during the initialization process may exchange capability information indicating whether support for the power saving is available. When the first terminal200and the second terminal300are verified to support the power saving through exchange of the capability information, the first terminal200and the second terminal300may apply a power saving scheme according to an embodiment of the present invention while performing the direct communication.

FIG. 2is a block diagram illustrating the first terminal200ofFIG. 2.

Referring toFIG. 2, the first terminal200may include a communication unit210and a control unit220.

The communication unit210may transmit a request message for requesting a direct communication with at least one external terminal to the control apparatus100controlling an operation of the at least one external terminal. Also, the communication unit210may receive, from the control apparatus100, a response message indicating that the at least one external terminal accepts the direct communication. Through this, an initialization for the direct communication may be completed.

The communication unit210may receive scheduling information for transmission and reception of data with the at least one external terminal through a wireless communication. Hereinafter, descriptions will be made using the second terminal300as the at least one external terminal. The communication unit210may receive scheduling information of the second terminal300via the control apparatus100, or may directly receive the scheduling information from the second terminal300.

The control unit220may control the communication unit210to communicate with the second terminal300by referring to the received scheduling information.

Scheduling information of the second terminal300may include information associated with a transmission interval where the second terminal300transmits data. That is, the scheduling information may include a transmission point in time of the data and a point in time when the transmission is terminated. In the transmission interval, the control unit220may operate in a receive mode for receiving data from the second terminal300. In an interval excluding the transmission interval, that is, in a sleep interval by verifying the scheduling information of the second terminal300, the control unit220may operate in a sleep mode. Accordingly, in the transmission interval, the control unit220may control the communication unit210to receive the data from the second terminal300. Scheduling information of the second terminal300may further include information associated with the sleep interval where the data is not transmitted.

The control unit220may control the communication unit210to provide, to the second terminal300, scheduling information for data transmission and reception of the first terminal200.

As described above, for power saving, the first terminal200and the second terminal300may share in advance mutual scheduling information while operating in a direct communication mode. For example, the first terminal200and the second terminal300may mutually notify information regarding a transmission point in time when each of the first terminal200and the second terminal300transmits data. At a point in time when the second terminal300transmits data, the first terminal200may be woken up to receive the data. Also, in a time interval when the second terminal300does not transmit data, the second terminal300may enter a sleep mode to minimize a power consumption.

Scheduling information of the second terminal300may be directly transmitted from the second terminal300to the first terminal200. Scheduling information of the second terminal300may be transmitted to the first terminal200via the control apparatus100. The control apparatus100may generate scheduling information of the first terminal200or the second terminal300, and may transmit the generated scheduling information to the first terminal200and the second terminal300.

Through the above process, the first terminal200and the second terminal300may share mutual scheduling information. Scheduling information of each of the first terminal200and the second terminal300participating in the direct communication may be the same.

FIG. 3is a diagram to describe an example of a power saving scheme according to an embodiment of the present invention.

The control apparatus100may generate scheduling information of each of the first terminal200and the second terminal300, and may transmit the scheduling information to each of the first terminal200and the second terminal300. The scheduling information may include transmission time information of data or transmission interval information.

Accordingly, each of the first terminal200and the second terminal300may be aware of when a counter party terminal performing the direct communication, that is, the second terminal300and the first terminal200transmits data to a corresponding counter party terminal. For example, the first terminal200may be ware of a time when the second terminal300transmits data to the first terminal200, by referring to scheduling information of the second terminal300.

Accordingly, in a time interval where the second terminal300transmits data, the first terminal200may be woken up to directly receive the data from the second terminal300. In an interval excluding the transmission interval for the direct communication, the first terminal200may operate in a sleep mode. InFIG. 3, during a time period indicated by the sleep mode, the first terminal200and the second terminal300may not perform the direct communication and thus, operate in the sleep mode, saving the power consumption.

FIG. 4is a diagram to describe an example of additionally allocating a transmission interval for a direct communication to the first terminal200and the second terminal300according to an embodiment of the present invention.

When a direct communication mode is maintained, the control apparatus100may continuously transmit scheduling information to the first terminal200and the second terminal300. The first terminal200and the second terminal300may be additionally allocated with time information of an available transmission interval from the control apparatus100.

Referring toFIG. 1throughFIG. 4, the control apparatus100may schedule a data transmission time with respect to the first terminal200or the second terminal300. The first terminal200and the second terminal300may access a radio channel in a scheduled interval to transmit and receive the data.

The first terminal200and the second terminal300may employ a scheme of accessing a radio channel through a contention, and transmitting data. When employing the above scheme, a time interval for the radio communication may be classified into a time interval for accessing the radio channel through the contention and a time interval for accessing the radio channel based on scheduling instead of the contention.

When the direct communication scheme is applied, the control apparatus100may notify the first terminal200and the second terminal300about scheduling information of each of the first terminal200and the second terminal300, and information associated with the time interval where the radio channel access through the contention is available. Accordingly, the first terminal200and the second terminal300may access the radio channel through the contention, and may directly participate into the direct communication. In this example, the first terminal200and the second terminal300may operate in a wake-up state at all times, and may wait for data transmission from an external terminal.

In addition to the method described above with reference toFIG. 1, the initialization process for the direct communication may be performed through a connection establishment between the control apparatus100and a terminal. For example, in an Institute of Electrical and Electronics Engineers (IEEE) 802.x standard, each of the first terminal200and the second terminal300, and the control apparatus100may perform a connection establishment through an authentication and association process. When the connection establishment is performed, the first terminal200and the second terminal300may receive, from the control apparatus100, control information associated with a point in time when data transmission and reception is available, and may participate into transmission and reception of data. When the first terminal200and the second terminal300operates in a direct communication mode, the first terminal200and the second terminal300may operate in a sleep mode using information received from the control apparatus100.

FIG. 5is a flowchart illustrating a power saving method of a terminal according to an embodiment of the present invention.

The power saving method of the terminal shown inFIG. 5may be performed by the wireless communication system described above with reference toFIG. 1throughFIG. 4.

In operation510, a first terminal and a second terminal may perform an initialization process required for a direct communication. The initialization process may include a process of transmitting, by the first terminal to the second terminal via a control apparatus, a request message requesting the direct communication, and receiving, from the second terminal, a response message with respect to the direct communication request.

In operation520, the first terminal may receive scheduling information for data transmission and reception of the second terminal. Scheduling information of the second terminal may be received from the control apparatus or the second terminal.

In operation530, the first terminal may perform the direct communication with the second terminal by referring to the received scheduling information of the second terminal. For example, in a transmission interval included in the scheduling information, the first terminal may operate in a receive mode for receiving the data from the second terminal. While operating in the receive mode, the first terminal may directly receive data from the to second terminal.

When the transmission interval is terminated in operation540, the first terminal may operate in a sleep mode in an interval excluding the transmission interval included in the scheduling information in operation550.