KR20050118650A - System and method for power asving in distributed wireless personal area networks - Google Patents

Abstract

Disclosed are a system and method having a power saving function in a decentralized personal wireless network. According to the present invention, in medium access control for wireless personal area networks based on a wireless mobile ad-hoc network, information on devices in hibernate mode is provided through a power saving information element. We present the PS Anchor (Power Save Anchor) to beacon group. This allows all devices in a given network to schedule their active and hibernate modes according to the hibernate intervals of the destination devices they wish to communicate with. This effectively reduces the need to wait for the destination device to exit hibernate mode while the device is idle. This effectively reduces the power of all devices in the network.

Description

System and method with power saving function in decentralized personal wireless network

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a decentralized personal wireless network that provides power saving media access control for wireless personal area networks based on wireless mobile ad-hoc networks. The present invention relates to a system and method having a power saving function.

Personal wireless networks are defined as operating in private areas around 10 meters. The Institute of Electrical and Electronics Engineers (IEEE) has been involved in setting standards for such personal wireless networks. Ultra Wide Band (UWB) communication technology can provide transfer rates in excess of hundreds of Mbps in this private domain. In a personal wireless network, the medium is shared between all devices for communication with each other. If possible, the devices attempt to be in a power saving state to save battery power.

This requires a media access control method for controlling the media access of the devices. It broadly describes how to access the network, how to transfer data to other devices at the desired rate, how best to use the medium, how to detect and resolve beacon collisions, and how Include whether the power source is optimally available.

Media access control for personal wireless networks can be designed in two approaches: centralized and distributed. In a centralized approach, one device operates for the entire network to manage and coordinate media access for all devices. All devices require the assistance of a centralized coordinator for media access, such as joining the network or allocating channel time. In the decentralized approach, the media access is evenly distributed to all devices in the network. And all devices share the burden of managing each other's media access. Although the IEEE standard is for centralized media access control, several decentralized media access control methods have been discussed for WPAN. Such a method provides flexibility for the mobility of the devices.

1 is a diagram illustrating a personal wireless network in a conventional decentralized approach.

Referring to Figure 1, it includes several devices indicated by dots. The circle drawn around each device represents the range in which the beacon of the device is received. The devices included in one circle form one beacon group.

Personal wireless networks based on a decentralized approach do not have any centralized coordinator. All devices in the network act as hard coordinators and do not include a separate dedicated coordinator. All devices cooperate with each other. In addition, each device shares information necessary for performing media access control such as channel time allocation, synchronization method, and power saving for data transmission to other devices. This is a decentralized personal wireless network system formed in an ad-hoc type. Each device periodically broadcasts information about its peripheral devices and information about the channel time assigned to its peripheral devices.

Decentralized media access control relies on a timing concept called "superframe." Superframes have a fixed length of time and are divided into a number of time windows called 'time slots'. Time slots are also referred to as Medium Access Slots (MAS).

Most time slots are used by devices to send beacons. The remaining slots are then used to send data. Slots to which beacons are sent are called 'beacon slots' and slots to which data is sent are called 'data slots'. The length of the beacon period (BP) may be smaller than the length of the data interval. Beacon slots may be distributed over the slots of the superframe, or may appear together at the beginning of the superframe. In addition, the number of beacons may be fixed and may vary as it is linked to other configurations of distributed media access control.

2 is a diagram illustrating an example of a structure of a conventional superframe.

The structure of the superframe shown in FIG. 2 is based on what is defined by Multiband Orthogonal Frequency Division Modulation (OFDM) Alliance draft v0.5. This includes several Medium Access Slots (MAS) (a, c). Some medium access slots (including a) consist of a beacon period b which consists of matching beacon slots in a plurality of devices. The remaining media access slots (including c) form a data interval d consisting of media access slots that can be used by other devices in the network to deliver data to other devices in the network.

These media access slots form a 65,536 ms superframe with 256 beacon slots, each media access slot being 256 ms. The information of the superframe may be broadcast in a beacon broadcast by each device. The start time of a superframe is determined by the start of a beacon period, which is defined as a beacon period start time (BPST).

Devices belonging to the same beacon group use the same beacon interval start time for the superframe. However, some devices may define their beacon start time as another time. In such a case, two or more beacon groups may exist simultaneously. Media access slots are serialized with respect to this start time.

The devices broadcast in all beacons the occupation status of the beacon slots in the beacon interval, including an information element (IE) such as a Beacon Period Occupancy Information Element (BPOIE). The beacon interval occupation information only includes beacon information of devices belonging to the same beaconing group.

Simultaneously with receiving the beacon frame, the device stores the sender's Device ID (DEVID) and the slot number where the beacon was received. The device then includes this information in the beacon section occupancy information transmitted in the next superframe. Information of beacons received during only one superframe is included in the beacon section occupancy information sent in the next superframe.

If the device ID of a device is not visible in the beacon section occupancy information of the neighboring device beacon for a predetermined successive superframe, it means that the device will change the beacon slot to the idle slot in the next superframe. If the beaconslot is changed, data reservations (DRP) can be maintained and need not be renegotiated.

In the conventional form, MBOA-MAC (Multiband OFDM Alliance Media Access Control) is defined as two modes of operation, active mode and hibernating mode. In the active mode, the device can be in either an awake state or a sleep state. In the awake state, the transmitter and receiver of the device operate at full power using more power, even if they are not currently transmitting or receiving. In the dormant state, the power to the transmitter and receiver circuits is reduced to use minimal power. In active mode, the devices switch between waking and dormant states according to data reservations already declared in the beacon section.

A second method of power saving is to declare that the devices will go into hibernate mode. Devices running in hibernate mode declare how many superframes they will be in hibernate mode via their beacons. The devices have been in a very deep sleep. Then they will not send or receive beacons.

Other devices in the beacon group will note this declaration and will continue to include information about hibernating devices in their beacon occupancy information until they wake up. In addition, devices in the beacon group will maintain information in their local database for devices that are hibernating, and will postpone communicating with them until the hibernating devices start operating and begin sending beacons.

However, as discussed in MBOA MAC v0.5, the prior art in the art to which the present invention pertains is that if there is a device that does not identify a beacon that declares its intention to proceed to hibernate mode of that device, then the device is hibernated. The problem is that the state device does not know when to return to active mode.

If such devices want to communicate with a hibernate device, they must stay awake for a long time to see in which superframe the hibernate device will wake up.

Conversely, a hibernate mode device wakes up from hibernating mode and switches to active mode, but does not know about other devices that have gone to sleep during that hibernation period. Thus, the device may remain in active mode for an indefinite period of time for communication with such devices. Thus, such a long standby state rapidly reduces the power of the device.

This situation may occur more frequently in the case of beacon groups with high mobility.

Accordingly, an object of the present invention is to provide a system by distributing a power saving information element of each device in a wideband (UWB) personal wireless network based on a wireless ad-hoc network of a decentralized network topology. It is to provide a system and method having a power saving function in a decentralized personal wireless network that saves power.

In order to achieve the above object, a power saving method in a wireless network based on wireless mobile ad-hoc networks according to the present invention includes at least one device P becoming a PS anchor by itself and a beacon group (beacon). broadcasting information about an operating state of devices in a group) into the beacon group and saving power until at least one device in the beacon group is able to identify and communicate with an operating state of a counterpart device to communicate with based on the information. Waiting in a state.

Preferably, the network is a Wide Wide Band Wireless Personal Area Networks.

Advantageously, the step of selecting, if there is no PS anchor already in operation in the beacon group and there is at least one other device, the device P selects the role of the PS anchor.

Advantageously, said selecting step comprises said PS anchor being already operating in said beacon group and all devices in said beacon group being unable to receive information about said operating state from said active PS anchor. Selects the role of the PS anchor.

Furthermore, when it is impossible to receive the information on the operation state, it is simultaneously identified by a beacon broadcasted by any one of the PS anchors in operation among a combination of any two devices in the beacon group. It is preferable that there is no combination.

It is preferable that the device P is one of a case of continuously receiving power for operation and a case of including a power device capable of supplying power for operation.

Preferably, the device P may have enough memory to store the operating state of all devices in the beacon group and at least one byte for the information in its beacon.

Preferably, the device P does not proceed to a state for power saving that does not transmit a beacon while operating as a PS anchor.

Preferably, the information about the operation state includes information on a device in a hibernating mode as a device in the beacon group and information on when to switch from the hibernation mode to an active mode. .

Preferably, the information about the operation state is in the form of an information element included in the beacon broadcasted by the PS anchor.

Preferably, the information element is a field indicating a device in the hibernate mode among the devices in the beacon group in at least one bit unit and the hibernate mode in the active mode in at least one byte unit corresponding to the bit. It includes a field containing information on when to switch.

Further, the information regarding the operation state is preferably obtained by receiving a beacon of a device in the beacon group and a beacon of another PS anchor in the beacon group during at least one superframe.

Preferably, the device P further includes the step of operating as the PS anchor and giving up the role as the PS anchor after a predetermined time.

Advantageously, said predetermined time is determined when there are no other devices in said beacon group, and there are other PS anchors in operation in said beacon group, and all devices in said beacon group are in said operating state from the other PS anchors in operation. It is when it is applicable to any one of the cases in which information can be received.

In addition, a system having a power saving function in a decentralized wireless network based on a wireless mobile ad-hoc network according to the present invention, information on the operation state of devices in its beacon group A device P which selects itself as a PS anchor to broadcast in the beacon group, and a neighboring device waiting for a power saving state until communication is possible according to an operation state of a counterpart device to communicate according to the information.

Preferably, the network is a Wide Wide Band Wireless Personal Area Networks.

Preferably, the device P, if there is no PS anchor already in operation in the beacon group and at least one other device, the device P can select the role of the PS anchor.

Preferably, the device P, if there is a PS anchor already in operation in the beacon group, and all the devices in the beacon group can not receive information about the operating state from the operating PS anchor in the beacon group The role of the PS anchor can be selected.

Preferably, when the information regarding the operation state cannot be received, simultaneously identified by a beacon broadcast by any one of the operating PS anchors in a combination consisting of any two devices in the beacon group. There is no combination.

Preferably, the device P is any one of a case of continuously receiving power for operation and a case of including a power device capable of supplying power for operation.

Advantageously, said device P has sufficient memory for storing the operating states of all devices in said beacon group and at least one byte for said information in its beacon.

Preferably, the device P does not proceed to a state for power saving that does not transmit a beacon while operating as a PS anchor.

Preferably, the information about the operation state includes information of a device in a hibernate mode as a device in the beacon group and information on a time of switching from the hibernation mode to an active mode.

Preferably, the information about the operation state is in the form of an information element included in the beacon broadcast by the PS anchor.

Preferably, the information element is a field indicating a device in the hibernate mode among the devices in the beacon group in at least one bit unit and the hibernate mode in the active mode in at least one byte unit corresponding to the bit. It includes a field containing information on when to switch.

Preferably, the information regarding the operation state is obtained by receiving a beacon of a device in the beacon group and a beacon of another PS anchor in the beacon group during at least one superframe.

Preferably, the device P may operate as the PS anchor and give up its role as the PS anchor after a predetermined time.

Advantageously, said predetermined time is determined when there are no other devices in said beacon group, and there are other PS anchors in operation in said beacon group, and all devices in said beacon group are in said operating state from the other PS anchors in operation. This is the case when any of the information can be received.

Hereinafter, the present invention will be described in detail with reference to the drawings.

3 is a diagram illustrating a network including a system having a power saving function in a decentralized personal wireless network of the present invention.

The system of the present invention may be included in a broadband (WWAN) wireless personal area network (WPAN) based on mobile ad-hoc networks of a decentralized and decentralized method. Media access control (MAC).

The system of the present invention can make a decision as to when all devices will enter a power save (PS) mode and when to wake up for communication. In addition, information about devices in hibernating mode (hereinafter referred to as hibernating devices) and information on how many superframes each hibernate device will wake up after may be obtained. And for this purpose it can play a role as a 'PS-Anchor (PS-Anchor) (Power Save Anchor).

Furthermore, the present invention relates to a hibernation device and hibernation device in a beacon group, when a new device that does not have information about a previous hibernation device as it enters a new beacon group, or a device that does not have information about becoming a hibernation device while in hibernation mode. Provides a way for the superframe to switch to the active mode.

Referring to FIG. 3, two beacon groups are shown in the network as circles. Two beacon groups include several devices including PS anchors P1, P2 and P3, and hibernate devices H1 and H2.

PS anchors P1, P2 and P3 help to broadcast the power saving status of each device in the beacon group to the network. That is, information about hibernating devices among devices in the beacon group and when such hibernating devices wake up (hereinafter, referred to as 'power saving state') are broadcasted to the network.

All devices in the system of the present invention may perform a function as a PS anchor, and may include at least one PS anchor in one beacon group. Furthermore, even if a device is already operating as a PS anchor, it can be given up as a PS anchor if it is no longer needed.

The role selection and abandonment of the device as a PS anchor in a device in this network does not require any additional control messages to be exchanged with neighboring devices, and uses an information element broadcast through a beacon.

PS anchors P1, P2 and P3 shall have the following conditions.

First, it must be a continuous or stable power supply or a power device capable of supplying such power. Second, the PS anchor must have enough memory to store the state of hibernating devices in its beacon group. Third, the PS anchor must have enough spare bytes in its beacon to send information about hibernate devices. And finally, the PS anchor must voluntarily play its role as a PS anchor, and while operating as the PS anchor, there is a compulsion that the PS anchor should not proceed to the power saving mode.

The PS anchors P1, P2, and P3 include means for promoting information about hibernation devices H1 and H2 and how many superframes each hibernation device H1 and H2 will wake up after. To this end, PS anchors P1, P2, and P3 use information elements (PSIE) called power save information elements (PSIE) in their beacons to network the power savings of the devices in their beacon groups. Declare at.

Therefore, devices that want to communicate with hibernating devices H1 and H2 do not need to maintain the active mode, and can perform time management of the dormant state and the waking state according to the power saving state through the power saving information element. This allows power saving effects to occur for all devices.

4 is a diagram showing the structure of a power saving information element according to an embodiment of the present invention.

Referring to FIG. 4, the power saving information element includes a field of a wake-up interval (a), a power-saving beacon (PS-beacon) (b), a length (c), and an element ID (d).

The power saving information element includes a power saving state, which is information of hibernate devices and information on how many superframes each hibernate device wakes up. The length of the field is variable and depends on the number of hibernating devices in the beacon group of the corresponding PS anchor.

The PS anchor may check the information on the hibernation device to be included in the power saving information element through the beacon previously received from the hibernation device and the beacon received from the other PS anchor.

Wake-up interval (a) includes information on the interval at which hibernate devices wake up from hibernate mode. The length of the wake-up interval (a) is variable according to the number of hibernation devices, and a field of one byte unit corresponds to one device.

The power saving beacon b is a field indicating a hibernation device among the devices in the beacon group. The power saving beacon b is a 24-bit bitmap, which is a 3-byte long field. Each bit in the power saving beacon b is mapped to beacon slots in the beacon section.

Length (c) is the total length of the power saving information element, and Element ID (d) is the ID of the power saving information element.

The power saving information element used by the PS anchor to declare power saving states of various devices of the beacon group to the network will be described with reference to FIG. 5.

5 is a diagram illustrating individual fields of a power saving information element according to an embodiment of the present invention.

The power saving beacon (e) of FIG. 5 shows an example of the power saving beacon and corresponds to the power saving beacon (b) of FIG. 4, and the wakeup-interval (f) shows an example of the wakeup-interval. Corresponds to Wakeup-interval (a) of FIG.

The power saving beacon e is a bitmap including at least one bit. The power saving beacon e may be represented as a bitmap having a bit number corresponding to the total number of devices that can be included in the beacon group, and is preferably a 3-byte long field shown as a 24-bit bitmap. Each bit in the power saving beacon e maps to a beacon slot in the beacon section. If a bit of the power saving beacon e is set to 1, it indicates that the device sending the beacon in the slot corresponding to that bit is a hibernating device.

Wakeup-interval (f) is a contiguous field of one byte unit, the size of which is variable and determined by the number of hibernate devices. Each byte of Wakeup-interval (f) contains information about the hibernation mode of the hibernation device.

The value of the first byte of wakeup-interval (f) corresponds to the first entry among the entries having 1 in the bitmap of the power saving beacon e. Similarly, the second byte corresponds to the second occurrence of the entry having 1 in the bit field of the power saving beacon e. Accordingly, each byte of Wakeup-interval (f) corresponds to hibernation device, which is a device having 1 in the bitmap of the power saving beacon e, and includes information on hibernation mode of the hibernation device corresponding to each byte. .

According to Figure 5, it can be seen through the power-saving beacon (e) that the device sending the beacon through the first, fourth and 16th beacon slot is in the hibernation state, the device in the hibernation state wakes up from the hibernation state Information about the interval is broadcast to the beacon group on the first to third bytes of Wakeup-interval (f).

Each device in the beacon group can know about the hibernation device through the power saving information element received from the PS anchor. Thus, a device wishing to communicate with a hibernating device can determine when to switch to a long power saving mode and when to wake up to an active mode. This kind of scheduled sleep and wake up not only saves battery power but also increases the ad-hoc network's duration.

Hereinafter, a method in which one device in the network selects itself as a PS anchor and a method of giving up the role as a PS anchor will be described.

As described above, a device having a feature as a PS anchor (hereinafter referred to as 'device P') must first determine whether there is a PS anchor already operating in the beacon group of the device P in order to operate as a PS anchor. . Depending on whether or not the PS anchor is already operating, the device P has a different determination method on whether to select the role of the PS anchor.

To this end, the device P receives a beacon from neighboring devices, and determines whether the PS anchor is present in the beacon group from the beacon.

FIG. 6 is a flowchart illustrating a method in which the device P operates as a PS anchor when no PS anchor is present in the beacon group.

If the device P determines that no PS anchor is present in the beacon group, the device P should examine whether it can provide a power saving information element for at least one neighboring device in the beacon group. In other words, it is determined whether there is an operating device in its beacon group.

The device P receives the beacon from the neighbor device in the beacon group (S601), and determines whether there are other devices in its beacon group. This state can be easily determined using the Beacon Period Occupancy Information Element (BPOIE) individually received from the neighbor device of the device P (S603).

If it is determined that such a device exists, it is useful for the network that the device P operates as a PS anchor, and the device P may itself be a PS anchor (S605).

Hereinafter, a method in which the device P operates as a PS anchor when the PS anchor is already operating in the beacon group will be described with reference to FIGS. 7 and 8.

If there is a PS anchor in the beacon group of device P, then it is necessary to evaluate whether all neighboring devices of device P are being served by the PS anchors.

Any two devices in the beacon group of device P may attempt to communicate with each other, one of which may be a hibernating device. Therefore, these two devices must be identified simultaneously by any one of the PS anchors in operation. If not, it means that the two devices cannot see each other's status.

The device P determines this situation by using the beacon interval occupation information of the neighboring devices and the beacon interval occupation information of the PS anchors found in the beacon group of the device P.

7 is a diagram illustrating a network including a PS anchor in operation.

Referring to FIG. 7, the beacon group of device P includes PS anchors P1, P2, and P3 that are already operating. The device P at the center wants to be a PS anchor.

Device H is a hibernate device, and device Y intends to communicate with hibernate device H.

The device Y may receive the power saving information element from the PS anchor P3, but may not receive the power saving information element from the PS anchor P1. Therefore, it is not possible to confirm whether the hibernation device H is in hibernation mode. Therefore, if the device P operates as a PS anchor, the device Y needs to make unnecessary attempts to communicate with the hibernate device H.

Thus, if there is any one pair of devices (devices Y and H) not simultaneously identified from one PS anchor in the beacon group, the device P is useful to operate as a PS anchor.

8 is a flowchart illustrating a method in which a device P operates as a PS anchor when a PS anchor is present in a beacon group.

The device P receives the beacon from the neighboring devices in the beacon group, and receives the power saving information element from the PS anchors P1, P2, and P3 (S801).

The device P determines whether all device pairs in the beacon group of the device P can receive the power saving information element from the PS anchor already in operation. This creates a pair of neighboring devices in the beacon section occupancy information of device P, and checks whether they are in the beacon section occupancy information of another PS anchor in the beacon group of device P. It is determined (S803).

The device P determines that if all device pairs satisfy S803, all device pairs in the beacon group of the device P may receive the power saving information element from the operating PS anchors, and thus there is no usefulness to become a PS anchor. If some device pairs are out of the range of the operating PS anchors, it is determined that the device P is useful to be a PS anchor (S805).

If the device P is useful as a PS anchor, it may be a PS anchor (S807).

The above algorithm is performed by a future PS anchor after hearing the beacons of the beacon interval for several superframes. Therefore, be sure to have enough information about the other PS anchors in the beacon group. The decision to become a PS anchor is made by this information and declared in the next beacon in the form of a power saving information element. A field of beacons that also reflect the characteristics of one device may be used to indicate that the device is a PS anchor.

Hereinafter, a method in which a device operating as a PS anchor gives up its role as a PS anchor will be described. Even a device operating as a PS anchor can give up its role as a PS anchor.

A device operating as a PS anchor must periodically check whether it needs to continue to operate as a PS anchor. It can be determined using the method described in FIGS. 6 and 8 as two different determination methods depending on whether other PS anchors are present. If it is determined that the PS anchor is not satisfied with either of the two determination methods, the PS anchor may be abandoned.

According to the present invention, the device for switching from the active mode to the hibernate mode operates as follows.

The operation performed by the device in the hibernate mode is the same as described in the prior art. A device going into hibernate mode must declare information about going into hibernate mode through its beacon. This information is noted by all PS anchors and is included in the power saving information element broadcasted later. Hibernation devices do not need to send or listen to beacons for the number of superframes declared in their beacons. A device waking up in hibernate mode must read all beacons and the entire superframe in order to get a snapshot of the network and reserve the Data Reservation Protocol (DRP).

Hereinafter, a case where one device wants to communicate with another hibernate device will be described.

For example, suppose device Y wants to communicate with device H. Device P is a PS anchor in the beacon group of H and Y. There may be two situations for device Y.

In the first case, device Y was in the network when device H declared to go into hibernate mode, and it has information about when device H wakes up.

In the second case, when device Y moves to the beacon group of device H, it is found that device H is in a hibernating state through the power saving information element of PS anchor P. From that information, device Y knows how many more superframes device H will be in hibernate mode.

Device Y should defer sending the frame until device H wakes up. In the superframe in which device H wakes up, device Y must listen to the beacon of device H, determine if it is still in the beacon group, and then transmit the frame. This allows device Y to remain active or communicate with device H, thus saving power to the entire system.

According to the PS anchor of the present invention, a device waking up from hibernation mode can obtain information about another device that has gone into hibernation mode during its hibernation mode. Thus, there is no need to stay in active mode or attempt to communicate with the devices. This greatly contributes to the power savings of the entire system.

In addition, even when there are highly mobile devices whose configuration of the beacon group changes frequently, information about devices in hibernation mode and devices outside the beacon group can be obtained and coped with.

In this way, the operation of a system having a power saving function in a decentralized personal wireless network is performed.

As described above, according to the present invention, a method of operating a device by itself as a PS anchor and a method of giving up its role as a PS anchor are presented.

In addition, according to the present invention, devices in the network can know information about the device in hibernate mode.

In addition, even if the device does not obtain the information on the hibernation mode directly from the device going to the hibernation mode, the information on the hibernation device can be obtained.

In addition, the present invention proposes a method of knowing a superframe that a hibernating device converts into an active mode.

Accordingly, all devices in a given Wireless Personal Area Networks can schedule their active and hibernating modes according to the hibernating intervals of the destination devices they wish to communicate with. have. This effectively reduces the need to wait for the destination device to exit hibernate mode while the device is idle. This effectively reduces the power of all devices in the network.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the specific embodiments described above, but the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1 illustrates a personal wireless network in a conventional decentralized approach;

2 is a diagram illustrating an example of a structure of a conventional superframe;

3 illustrates a network including a system having a power saving function in a distributed personal wireless network of the present invention;

4 is a diagram showing the structure of a power saving information element according to an embodiment of the present invention;

5 is a view showing individual fields of a power saving information element according to an embodiment of the present invention;

6 is a flowchart illustrating a method in which a device P operates as a PS anchor when no PS anchor is present in a beacon group;

7 shows a network comprising a PS anchor in operation, and

8 is a flowchart illustrating a method in which a device P operates as a PS anchor when a PS anchor is present in a beacon group.

Claims (28)

In the power saving method in a decentralized wireless network, At least one device P becoming a PS anchor by itself and broadcasting information in the beacon group about the operating state of the devices in the beacon group; And Determining, by the at least one device in the beacon group, the operating state of the counterpart device to communicate with and waiting in a power saving state until communication is possible, based on the information. Way. The method of claim 1, The network is a power saving method in a decentralized wireless network, characterized in that the Wireless Personal Area Networks (Wireless Personal Area Networks) based on the broadband (Ultra Wide Band) ad-hoc network. The method of claim 1, The selecting step, And if there are no PS anchors already in the beacon group and at least one other device is present, the device P selects the role of the PS anchors. The method of claim 1, The selecting step, The device selects the role of the PS anchor when there is already a PS anchor in operation in the beacon group, and all devices in the beacon group cannot receive information on the operation state from the operating PS anchor. A power saving method in a decentralized wireless network. The method of claim 4, wherein If it is not possible to receive the information on the operation state, it is not simultaneously checked by a beacon broadcasted by any one of the PS anchors in operation among a combination of any two devices in the beacon group. Power saving method in a decentralized wireless network, characterized in that there is a combination. The method of claim 1, The device P is a power saving method in a decentralized wireless network, characterized in that any one of the case of continuously receiving power supply for operation, including a power supply device that can supply the power required for operation. The method of claim 1, The device P has a sufficient memory for storing the operating state of all devices in the beacon group and at least one byte for the information in its beacon, power saving method in a distributed wireless network. . The method of claim 1 And the device P does not proceed to a state for power saving that does not transmit a beacon while operating as a PS anchor. The method of claim 1, The information on the operation state includes information on a device in a hibernating mode as a device in the beacon group, and information on a time point for switching from the hibernation mode to an active mode. A power saving method in a decentralized wireless network. The method of claim 9, The information on the operation state, the power saving method in a decentralized wireless network, characterized in that the PS element in the form of an information element (Information Element) included in the beacon broadcasts. The method of claim 10, The information element is a field indicating a device in the hibernate mode among the devices in the beacon group in at least one bit unit and at the time of switching from the hibernate mode to an active mode in at least one byte unit corresponding to the bit. And a field including information on the power saving method in a distributed wireless network. The method of claim 9, The information on the operation state is obtained by receiving a beacon of a device in the beacon group and a beacon of another PS anchor in the beacon group during at least one superframe. . The method of claim 1, And abandoning the device P as the PS anchor after a predetermined time when the device P operates as the PS anchor. The method of claim 13, The predetermined time is when there are no other devices in the beacon group, and there are other PS anchors in operation in the beacon group, and all devices in the beacon group receive information about the operation state from the other PS anchors in operation. A method for reducing power in a distributed wireless network, characterized in that when one of the possible cases. In a system having a power saving function in a decentralized wireless network based on a wireless mobile ad-hoc network, A device P which selects itself a role as a PS anchor that broadcasts information on the operation status of devices in its beacon group in the beacon group; And At least one neighboring device belonging to the beacon group and waiting for a power saving state until communication is possible according to an operation state of a counterpart device to communicate according to the information; and a power saving function in a decentralized wireless network. Equipped system. The method of claim 15, The network is a system having a power saving function in a decentralized wireless network, characterized in that the Ultra Wide Band Wireless Personal Area Networks (Wireless Personal Area Networks). The method of claim 15, The device P, when it is determined that there is no PS anchor already operating in the beacon group and the at least one neighboring device is present, the device P selects the role of the PS anchor. System with. The method of claim 15, The device P selects the role of the PS anchor when the PS anchor is already operating in the beacon group and all the neighboring devices cannot receive the information on the operation state from the operating PS anchor. A system having a power saving function in a distributed wireless network, characterized in that. The method of claim 18, If it is not possible to receive the information on the operation state, a combination consisting of any two devices in the beacon group that is not simultaneously identified by a beacon broadcast by any one of the PS anchors in operation A system having a power saving function in a distributed wireless network, characterized in that the case. The method of claim 15, The device P is a system having a power saving function in a decentralized wireless network, characterized in that any one of the case of continuously receiving the power required for operation, including a power device capable of supplying the power required for operation. The method of claim 15, The device P has a sufficient memory for storing the operation state of all devices in the beacon group and at least one byte for the information in its beacon, power saving function in a distributed wireless network System with. The method of claim 15 And the device P does not proceed to a state for power saving that does not transmit a beacon while operating as a PS anchor. The method of claim 15, The information on the operation state includes information on a device in a hibernating mode as a device in the beacon group, and information on a time point for switching from the hibernation mode to an active mode. System with power saving function in decentralized wireless network. The method of claim 23, wherein And the information regarding the operation state has a form of an information element included in a beacon broadcasted by the PS anchor. The method of claim 24, The information element is a field indicating a device in the hibernate mode among the devices in the beacon group in at least one bit unit and at the time of switching from the hibernate mode to an active mode in at least one byte unit corresponding to the bit. A system having a power saving function in a decentralized wireless network, comprising: a field containing information about the information. The method of claim 23, wherein The information on the operation state is obtained by receiving a beacon of a device in the beacon group and a beacon of another PS anchor in the beacon group during at least one superframe. System with. The method of claim 15, And said device (P) acts as said PS anchor and relinquishes its role as said PS anchor after a predetermined period of time. The method of claim 27, The predetermined time is when there are no other devices in the beacon group, and there are other PS anchors in operation in the beacon group, and all devices in the beacon group receive information about the operation state from the other PS anchors in operation. A system having a power saving function in a decentralized wireless network, characterized in that when one of the possible cases.