KR20150019835A - An energy efficient multimedia streaming method in WiMedia networks - Google Patents

Abstract

The present invention relates to an efficient energy multimedia streaming method on a WiMedia network, including the steps of: determining whether the fragment of a MAC service data unit (MSDU) is damaged when the fragment of multimedia data on WiMidia-based wireless networks; extracting a duration field from the received fragment in a case the fragment of the MSDU is damaged; and switching a power mode from an active mode to a low power mode during a time set in the duration field.

Description

An energy efficient multimedia streaming method in a WiMedia network,

The present invention relates to a WiMedia-based wireless network, and more particularly, to a method for reducing unnecessary power consumption of a Wimedia MAC device.

WiMedia Alliance has announced the UWB-based Distributed Medium Access Control (D-MAC) protocol for high-speed WPANs. The WiMedia D-MAC protocol provides low-power, high-speed data transmission, and a distributed medium access method, which can provide a suitable communication link for home network, military / medical field, and the like. In contrast to the centralized IEEE 802.15.3 protocol, the D-MAC protocol allows all devices to have the same functionality, form networks themselves, allocate channels to other devices, transmit data, Synchronization is performed. The characteristics of the D-MAC protocol can be applied to a wireless mesh network.

The data transmission period of the WiMedia MAC protocol is called DTP (Data Transfer Period), and is divided into two types. One is a competitive Priority Contention Access (PCA) section, which operates in a similar manner to IEEE 802.11e. And the other is a reserved reservation protocol DRP (Distributed Reservation Protocol) section.

Since WiMedia or wireless USB devices are portable devices, they are powered by batteries and power consumption is directly linked to the lifetime of the entire network. The WiMedia standard provides a low-power mode to reduce power consumption. The power mode of the device provided by Wimedia MAC standard is hibernation mode which consumes less power and active mode which consumes more power than hibernation mode. Generally, a Wimedia MAC device operates in an active mode when receiving a fragment of a MAC Service Data Unit (MSDU) transmitted from a transmitting Wimedia MAC device.

On the other hand, multimedia streaming data generally maintains a No-Ack policy due to the nature of isochronous services. The Wimedia MAC device operating in No ACK mode does not receive the MSDU if the fragment of the MSDU transmitted from the transmitting Wimedia MAC device is lost.

However, even if the Wimedia MAC device does not receive the fragment of the MSDU, the power mode must be kept in the active mode because the number of fragments of the MSDU transmitted from the transmitting Wimedia MAC device and the time taken to transmit the MSDU can not be known. That is, when a fragment of the MSDU is lost, the Wimedia MAC device maintains the active mode for a time period required for MSDU transmission, which causes a problem of unnecessary power consumption. Particularly, in a multimedia service application, most of the operations are performed in the No ACK mode, which causes a problem of power consumption due to fragment loss.

Therefore, there is a need for a technique whereby the transmitting Wimedia MAC device transmits time information about the MSDU transmission and the receiving Wimedia MAC device can control the power mode when the MSDU's fragment is lost.

An object of the present invention is to provide a technical solution for reducing unnecessary power consumption of a Wimedia MAC device when a fragment of multimedia data is lost in WiMedia-based wireless networks.

According to an aspect of the present invention, there is provided an efficient energy multimedia streaming method in a WiMedia network, which includes: receiving a fragment of multimedia data in a WiMedia-based wireless network; receiving a MAC Service Data Unit (MSDU) Determining if a fragment of the MSDU is lost, extracting a duration field from the previously received fragment if a fragment of the MSDU is lost, To a low power mode.

Comparing the sequence number of the received fragment and the sequence number of the expected fragment, and if the sequence number of the received fragment is greater than a sequence number of a predetermined expected fragment, the fragment of the MSDU And judging that it is lost.

The present invention is a data transmission and power management method for reducing unnecessary power consumption of a WiMedia MAC device when a fragment of multimedia data is lost in WiMedia-based wireless networks. According to the present invention, in a WiMedia-based wireless networks, It is possible not only to reduce unnecessary power consumption occurring at the time of loss, but also to predict the reception time of the next fragment, thereby facilitating buffering of multimedia data.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration of a typical WiMedia network for performing multimedia streaming services; FIG.
2 is a diagram illustrating a structure of a WiMedia MAC header according to an embodiment of the present invention;
3 is a flowchart of an efficient energy multimedia streaming method in a WiMedia network according to an embodiment of the present invention.
FIG. 4 is a flowchart for determining whether a fragment of a Wimedia MAC device is lost according to the present invention. FIG.
5 illustrates an example of a power control method of a Wimedia MAC device according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and further aspects of the present invention will become more apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a general WiMedia network in which a multimedia streaming service is performed.

As shown in FIG. 1, the transmitter-side Wimedia MAC device and the receiver-side Wimedia MAC device operate in a No-ACK (Acknowledgment) mode. The transmitting Wimedia MAC device divides the MSDU into a plurality of fragments and transmits them to the receiving Wimedia MAC device. At this time, the transmitting-side Wimedia MAC device transmits the fragment of the MSDU to the receiving-side Wimedia MAC device by including the sequence control field of the fragment in the MAC header.

2 is a diagram illustrating a structure of a WiMedia MAC header according to an embodiment of the present invention. As shown in FIG. 2, the sequence control field includes a sequence number and a fragment number, and the sequence number field again includes an MSDU ID and a fragment sequence field. In addition, the Fragment Number field indicates the number of fragments included in the MSDU. Further, the MSDU ID is a component for identifying the MSDU, and the fragment sequence is a component for confirming the order of the divided fragments of the MSDU.

The fragment of the MSDU transmitted from the transmitting-side Wimedia MAC device to the receiving-side Wimedia MAC device includes a duration field in which the time from the fragment of the transmitting MSDU to the fragment of the MSDU having the last fragment sequence is set. The receiving-side Wimedia MAC device receives a fragment of the MSDU transmitted from the transmitting-side Wimedia MAC device and determines whether the fragment of the MSDU is lost based on the sequence number of the received MSDU fragment and the sequence number of the expected fragment. At this time, the receiving-side Wimedia MAC device judges that the fragment of the MSDU is lost if the fragment sequence of the received MSDU fragment is larger than the fragment sequence of the expected fragment.

The receiving-side Wimedia MAC device extracts the period field configured in the fragment of the received MSDU when the fragment of the MSDU is lost, confirms the time from the fragment time of the MSDU received from the duration field to the last fragment time of the MSDU, The power mode is switched from the active mode to the low power mode. At this time, the low power mode is selected in idle mode or sleep mode.

After receiving the MSDU fragment, the Wimedia MAC device switches the power mode of the Wimedia MAC device from the low power mode to the active mode when the time set in the duration field has elapsed. That is, the Wimedia MAC device can switch the power mode from the active mode to the low power mode for a period of time in which the fragments of the MSDUs with fragment are transmitted from the transmitting-side Wimedia MAC device, thereby reducing unnecessary power consumption.

3 is a flowchart of an efficient energy multimedia streaming method in a WiMedia network according to an embodiment of the present invention.

First, the Wimedia MAC device receives a fragment of the MSDU transmitted from the transmitting Wimedia MAC device. Upon receiving the fragment of the MSDU, the Wimedia MAC device determines whether the fragment of the MSDU is lost. That is, upon receiving the MSDU fragment, the Wimedia MAC device determines whether there is an MSDU fragment transmitted from the transmitting Wimedia MAC device between the previously received MSDU fragment and the currently received MSDU fragment. At this time, the Wimedia MAC device can determine whether the fragment of the MSDU is lost based on the sequence number of the expected fragment and the sequence number of the received MSDU fragment.

The Wimedia MAC device compares the MSDU ID of the received MSDU fragment with the MSDU ID of the expected fragment to determine whether the fragment of the MSDU is lost based on the fragment sequence of the received MSDU fragment and the fragment of the expected fragment, do.

As a result of the determination, if the fragment of the MSDU is lost, the Wimedia MAC device extracts the duration field from the fragment of the received MSDU. Here, the period field is a field in which the time from the fragment of the received MSDU to the last fragment of the MSDU having the same MSDU ID is set.

The Wimedia MAC device switches the power mode from the active mode to the low power mode for the time set in the Duration field when the Duration field is extracted.

Thereafter, the Wimedia MAC device determines whether the time set in the duration field has elapsed, and switches the power mode from the low power mode back to the active mode when the time set in the duration field has elapsed. In other words, the Wimedia MAC device switches to the low power mode for the MSDU transmission time with the lost fragment to reduce power consumption, and when the MSDU transmission time with the missing fragment elapses, the power mode is switched to the active mode Switch.

FIG. 4 is a flowchart for determining whether a fragment of a Wimedia MAC device according to the present invention is lost.

First, the Wimedia MAC device extracts the MAC header from the fragment of the received MSDU to determine whether the MSDU has lost the fragment. The Wimedia MAC device then compares the sequence number of the fragment included in the MAC header with the sequence number of the expected fragment to be received by the Wimedia MAC device. At this time, the Wimedia MAC device compares the MSDU ID of the received MSDU fragment with the MSDU ID of the expected fragment to determine whether the two IDs are the same. As a result of the determination, if the MSDU ID of the received MSDU fragment is equal to the MSDU ID of the expected fragment, the Wimedia MAC device determines whether the fragment sequence of the received MSDU fragment is larger than the fragment sequence of the expected fragment. Thereafter, if the fragment number of the received MSDU fragment is larger than the fragment number of the expected fragment, the Wimedia MAC device determines that the fragment of the MSDU is lost.

5 is a diagram illustrating an example of a power control method of a Wimedia MAC device according to the present invention.

As shown in FIG. 5, an MSDU has an MSDU ID of 10, and is divided into seven fragments having a fragment number from 0 to 6. FIG.

In accordance with the present invention, a Wimedia MAC device includes a fragment with a (MSDU ID, fragment sequence) of (10, 0) transmitted from a transmitting Wimedia MAC device and a fragment sequence within a fragment up to (10, 1) It is judged that the fragment of the MSDU is not lost because it is the same as the fragment sequence.

On the other hand, the Wimedia MAC device receives a fragment whose (MSDU ID, fragment sequence) is (10, 3) because a fragment whose MSDU ID, fragment sequence, is (10, 2) is lost. At this time, since the Wimedia MAC device has received a fragment whose (MSDU ID, fragment sequence) is (10, 1), the sequence sequence of the expected fragment (MSDU ID, fragment sequence) becomes (10, 2).

The Wimedia MAC device extracts the MAC header from the fragment of the received MSDU and verifies the sequence number of the MSDU fragment received from the MAC header. It is determined whether the fragment of the MSDU is lost based on the sequence number (10, 3) of the received MSDU fragment and the sequence number (10, 2) of the expected fragment. The Wimedia MAC device determines that the fragment of the MSDU with the MSDU ID of "10" is lost because the fragment sequence "3" of the received MSDU fragment is larger than the fragment sequence "2" of the expected fragment.

After that, the Wimedia MAC device extracts the duration field from the fragment of the received MSDU because the fragment of the MSDU is lost and confirms the time information D3 set in the duration field.

The Wimedia MAC device switches power mode from active mode to low power mode for D3 hours, reducing unnecessary power consumption. In addition, the Wimedia MAC device switches the power mode from the low power mode back to the active mode to receive the next MSDU after D3 time elapses.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (2)

Determining whether a fragment of a MAC Service Data Unit (MSDU) is lost when receiving a fragment of multimedia data in WiMedia-based wireless networks;
If a fragment of the MSDU is lost, extracting a duration field from the previously received fragment; And
Switching a power mode from an active mode to a low power mode for a time set in the period field;
The method comprising the steps of: 2. The method of claim 1, wherein the determining comprises:
Comparing a sequence number of the received fragment with a sequence number of an expected fragment;
Determining that a fragment of the MSDU is lost if a sequence number of the received fragment is greater than a sequence number of a predetermined expected fragment;
The method comprising the steps of:

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