JP2005244269A - Wireless transmission device and power saving driving method for wireless transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless transmission apparatus capable of being in operation with power-saving, when transferring data at a prescribed rate over a long time. <P>SOLUTION: A transport layer 403 reports the remaining size of a reception buffer of a receiver side device to a power supply control section 405 and a session layer/application layer 404 reports the data transfer rate to the power supply control section 405. The power supply control section 405 controls the power-saving mode of a physical layer/data link layer 401, on the basis of the reception buffer size of a remote device and the transfer rate, to attain with power-saving operation for the wireless transmission apparatus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless transmission apparatus capable of power saving operation when performing data transmission / reception using wireless transmission.

2. Description of the Related Art Conventionally, devices that transmit and receive data using a wireless transmission scheme of the IEEE802.11 standard have been proposed for battery-powered mobile devices such as mobile phones / PDAs (Personal Digital Assistance). Among such devices, there are devices that transmit and receive media data such as video data and audio data in real time, and there are devices that transmit data for a long time at a constant transmission rate (for example, Patent Document 1).
JP 2002-33799 A

  However, the conventional battery-powered mobile device has a problem that the power consumption by the wireless function, particularly the physical layer / data link layer, has a great influence on the battery capacity of the device, and the usage time is limited.

  Also, in media data streams, a certain amount of stream data may be transmitted over a long period of time, and if the receiving device receives data exceeding the reception buffer limit, the received data is discarded. There was a problem that.

  In addition, there are devices with a built-in power saving mode that does not consume power when there is no data transmission / reception, but even if you try to use power saving activation, the device will return to the startup (active) mode from the power saving mode. There is a problem that time is required and the timing for changing to the power saving mode cannot be determined because it is not known when the next data transmission request is generated from the application layer.

  In order to solve the above problems, in the present invention, the power control unit on the transmission side monitors the reception capability of the receiver one by one, transmits data at a timing at which the receiver side can receive the stream transmission, and a time other than the transmission timing. Set the device to power saving mode.

  According to the wireless transmission device of the present invention, when data is transferred at a constant rate such as media data, the power consumption of the physical layer / data link layer can be reduced, and it is used in a battery-powered device or the like. You can extend the time.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram illustrating a relationship between wireless transmission apparatuses according to the present embodiment.

  As illustrated in FIG. 1, when the transmission device 501 receives a data transmission request from the reception device 502, the transmission device 501 transmits the requested data 503 to the reception device 502. The transmission side device 501 always receives a report 504 about the remaining size of the reception buffer held by the reception side device 502.

  FIG. 2 shows the configuration of the wireless transmission apparatus according to the embodiment of the present invention.

  FIG. 2 is a block diagram showing data transmitted / received between the hierarchies of the wireless transmission communication function according to the first embodiment of the present invention.

  In FIG. 2, the hierarchy is an upper layer as it goes from left to right, and the layer is divided into a physical layer / data link layer 101, a network layer 102, a transport layer 103, and a session layer / application layer 104 from the bottom. For example, IP (Internet Protocol) is used in the network layer, TCP (Transmission Control Protocol) or UDP (User Datagram Protocol) is used in the transport layer, and IEEE802.11 standard is used in the data link layer.

  Hereinafter, an operation when media data such as video data and audio data is received from a remote device (transmission side device) will be described with reference to FIG.

  The radio signal transmitted from the remote device is received / demodulated in the physical layer of the physical layer / data link layer 101. The demodulated data is passed to the data link layer of the physical layer / data link layer 101, an error is detected, it is determined whether the data is directed to the device, and passed to the network layer 102. As shown in FIG. 2, the data passed to the network layer 102 includes a network layer header 105, a transport layer header 106, and data 107. In the network layer 102, it is determined whether the received data is data to be passed to the transport layer 103 or control data for controlling the network layer 102. If the data is to be passed to the transport layer 103, the transport layer 103 The network layer header 105 is deleted and then passed.

  In the transport layer 103, the transport layer header 106 is deleted from the data passed from the network layer 102, and the data 107 is stored in an internal reception buffer. At this time, the transport layer 103 performs two operations. One notifies the upper session layer / application layer 104 that the data 107 has been received from the remote device. The other is to calculate the free space of the reception buffer, create the reception buffer free space report data 108, and transmit the data with the transport layer header 106 added thereto to the transport layer 103, so that the network layer 102 To request the remote device to transmit the reception buffer free space report data. The network layer 102 passes the data obtained by adding the network layer header 105 to the reception buffer free space report data received from the transport layer 103 to the physical layer / data link layer 101 and performs necessary processing in the physical layer / data link layer. And sent to the remote device.

  The session layer / application layer 104 notified of the arrival of the received data 107 requests the transport layer 103 for data long enough for the session layer / application layer 104 to receive. The transport layer 103 takes out the received data 109 for the length requested from the session layer / application layer 104 from the reception buffer and passes it to the session layer / application layer 104.

  Here, increase / decrease in the free capacity of the reception buffer in the transport layer will be described with reference to FIG.

  As shown in the upper part of FIG. 3, the free capacity of the reception buffer 204 in the transport layer 202 decreases when the reception data 205 is received from the network layer 201, and from the session layer / application layer 203 as shown in the lower part of FIG. Increased when received data 205 is passed in response to a received data read request.

  Next, the operation when transmitting media data such as video data and audio data will be described with reference to FIG. In FIG. 4, as in FIG. 2, the lower layers are from left to right.

  The transmission data 307 is created in the session layer / application layer 304 and passed to the transport layer 303. The transport layer 303 divides and combines the data 307 passed from the session layer / application layer 304 into the length determined by the transport layer 303, and adds a header 306 required by the transport layer 303 before and after the data. To the network layer 302. The network layer 302 divides and combines the data passed from the transport layer 303 into the length determined by the network layer 302, and adds a header 305 required by the network layer 302 before and after the data to the data link layer 301. hand over. The data link layer 301 secures a communication path with the data transmission destination remote device in the physical layer 301 and transfers data using the communication path. The physical layer 301 performs modulation and electrical conversion for sending data to the wireless transmission path, and transmits the data.

  The operation when receiving reception buffer free space report data from the receiving device will be described with reference to FIG.

  The reception buffer free space report data transmitted from the reception side device is processed in the physical layer / data link layer 401 and the network layer 402 in the same manner as the processing in the normal reception data described above, and passed to the transport layer 403. . The transport layer 403 determines that the received data is reception buffer free space report data of the remote device, and reports the reception buffer free space of the receiving device to the power control unit 405. In this case, in the case of wireless communication targeting a relatively short distance such as IEEE 802.11, transmission delay can be ignored, and the reception buffer free space report from the remote device can be considered to be almost real time. it can.

  The power supply control unit 405 receives a session from the reception buffer free space report data received from the transport layer 403 and the rate of data transmitted to the remote device such as AV data is constant. In accordance with the transfer rate of data received from the layer / application layer 404, the physical layer / data link layer is controlled to enter the power saving mode or the active mode. The power supply control unit 405 is preset with a standby time for the physical layer / data link layer 401 to shift from the power saving mode to the active mode.

  The power supply control unit 405 determines whether or not to set the physical layer / data link layer 401 to the power saving mode based on the reception buffer free space of the receiving side device and the transmission rate of the transmission data, and if so, determines the time.

  The reception buffer and the power saving mode will be described with reference to FIG.

  As shown in FIG. 6, when the reception buffer free capacity of the reception side device (reception device) increases, the transmission side device (transmission device) enters the active mode, transmits data to the reception side device, and the reception side device has a free reception buffer. When the capacity decreases, the transmitting device enters a power saving mode.

  Note that in this embodiment, the transport layer reports the free space report data of the reception buffer to the power supply control unit, but the window size in the transport layer 703 may be substituted as shown in FIG. Good. In this case, the control unit 705 controls the power saving mode of the physical layer / data link layer 701 and the transmission data amount of the session layer / application layer 704 according to the window size input from the transport layer 703.

  The wireless transmission device and the power saving driving method of the wireless transmission device of the present invention are useful as a power saving operation when performing data transmission / reception using wireless transmission.

The block diagram which shows the structure of the radio transmission apparatus in this invention The block diagram which shows the hierarchical structure of the communication function in this invention The figure explaining increase / decrease of the reception buffer of the transport layer in this invention The block diagram explaining the hierarchy structure of the communication function in this invention, and the operation | movement which transmits data The block diagram which shows the hierarchical structure of the communication function in this invention, and operation | movement of a power supply control part The figure which shows the relationship between the reception buffer and power saving mode in this invention The block diagram which shows other operation | movement of the hierarchical structure of the communication function in this invention, and a power supply control part

Explanation of symbols

101, 301, 401, 701 Physical layer / data link layer 102, 302, 402, 702 Network layer 103, 303, 403, 703 Transport layer 104, 304, 404, 704 Session layer / application layer 405, 705 Power control unit 501 Transmission side device 502 Reception side device

Claims (5)

A physical layer that performs electrical conversion for sending data to a wireless transmission path, and a data link layer that secures a physical communication path using the physical layer;
A network layer for passing data to the data link layer;
A transport layer for efficiently transmitting data using the network layer;
A wireless transmission device having a session layer / application layer that transmits and receives data using the transport layer and a power source control unit that manages power of the physical layer / data link layer;
The physical layer / data link layer has a power saving mode for reducing power consumption when there is no transmission data and an active mode for transmitting data,
When the session layer / application layer transfers data at a constant rate, it reports the transfer rate to the power control unit,
When the transport layer receives data, the transport layer sends the reception buffer free space for storing the received data to the transmission side device, and when data is transmitted, the reception buffer free space is transmitted from the reception side device. Receiving the capacity, reporting to the power control unit,
The wireless transmission apparatus, wherein the power control unit controls a power saving mode and an active mode of the physical layer / data link layer based on a free capacity of the reception buffer and the transfer rate. 2. The power saving drive method for a wireless transmission device according to claim 1, wherein IP is used in the network layer and TCP or UDP is used in the transport layer. The wireless transmission device according to claim 1, wherein the data link layer uses the IEEE802.11 standard. 3. The radio transmission apparatus according to claim 2, wherein in the network layer, the free space of the reception buffer reported to the transmission device is substituted by the window size in the transport layer. A power saving driving method of a wireless transmission device for transmitting and receiving data,
When receiving the data, the wireless transmission device transmits the reception buffer free space for storing the received data to the transmission side device, and when transmitting data, the reception buffer free space and the transfer of the data to be transmitted. A power-saving driving method for a wireless transmission device, wherein either a power-saving mode for reducing power consumption or an active mode for transmitting data is selected based on a rate.

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