KR20070107494A - Method and apparatus for a managing end devices in a wireless personal area network - Google Patents

Abstract

A node management method and a node management device in a WPAN(Wireless Personal Area Network) are provided to prevent network mismatch by adding ID(Identification) of a lower node to a beacon frame transmitted from an upper node. A node management method in the beacon type WPAN environment for periodically transmitting a beacon frame from an upper node to a lower node includes steps for transmitting the beacon frame including ID information indicating the network connection state of all lower nodes, from the upper node to the lower node; judging whether the upper node recognizes that a user is connected to the network, or not by analyzing the ID information of the beacon frame, in all lower nodes included in the upper node; and trying connecting to the upper node again if the upper node recognizes that the user is not connected to the network according to the analysis result, in the lower node.

Description

Method and Apparatus for Managing Subnodes in Wireless Personal Area Networks {Method and Apparatus for a managing end devices in a wireless personal area network}

1 is a block diagram of a conventional beacon type WPAN network.

2 is a beacon signal configuration diagram of a WPAN network according to an embodiment of the present invention.

3 is a configuration diagram of management field and packet request field information of a beacon signal of FIG.

4 is a diagram illustrating a memory configuration of an upper node that generates the beacon signal of FIG. 3.

5 is an operation explanatory diagram of a WPAN network according to an embodiment of the present invention.

The present invention relates to a wireless communication method and system in a wireless personal area network (WPAN) environment based on IEEE 802.15.4. The present invention relates to a wireless communication method and system for a WPAN network that improves system stability by resolving network inconsistency in time.

The IEEE 802.15 Working Group defines WPAN as the standard for short-range wireless networks, with four Task Groups beneath it. IEEE 802.15.1 is a Bluetooth technology, IEEE 802.15.2 is for developing a coexistence model between short-range wireless network and WLAN, and IEEE 802.15.3 and IEEE 802.15.3a are for high speed WPAN and UWB. IEEE 802.15.4 is a Zigbee technology.

1 is a block diagram of a general beacon type WPAN network.

The plurality of devices 10, 20, and 30 constitute one WPAN network. Devices used in a WPAN network are classified into a reduced functional device (RFD) operating with only a minimum protocol that can operate in a WPAN network and a full functional device (FFD) operating with a complete protocol set of a WPAN network. The RFD is used as an end device 30 for simple applications that do not have a routing function and there is no communication function between the RFDs and mainly uses limited resources and memory. The FFD is a multi-hop using multiple frequencies. It has a routing function, can communicate with the RFD and FFD, and can transmit a beacon signal, thereby functioning as a coordinator 10 and a router 20.

In the WPAN network of FIG. 1, one FFD having a beacon transmission function is selected as a network coordinator (C) 10 serving as a coordinator of the WPAN network. The other FFDs act as a router (R) 20 that connects wireless communication between the coordinator 10 and the terminal (E) 30. A plurality of terminals 30 are wirelessly connected to the router 20 and the coordinator 10 to perform wireless communication. The coordinator 10 functions as an upper node for all other devices, and each router 20 functions as a lower node for the coordinator 10 and an upper node for the terminals 30. The terminal 30 cannot transmit a beacon signal, and typically functions as a lower node driven by a battery.

Referring to the operation of the beacon-type WPAN network, first the coordinator 10 periodically transmits a beacon to start the new WPAN network to inform the remaining devices 20, 30 of the beacon, the device receiving the beacon They join the WPAN generated by the coordinator 10 through an association process with the coordinator 10. After the WPAN association is successfully completed, data transmission and reception between the coordinator 10 and the devices 20 and 30 is started.

All devices 10, 20, 30 originally have a 64-bit extended address unique to each device. However, when the devices 10, 20, and 30 form the WPAN network through the above association procedure, each device is assigned a 16-bit short address during the association process. The short address means a relative address of each device in a given WPAN network. The short address of the coordinator 10 is "0", and the FFD serving as an upper node allocates a short address of an FFD or RFD serving as a lower node. To this end, the coordinator 10 or the router 20 generates a beacon signal containing its short address. Thereafter, routing of communication signals in the WPAN network is performed through a short address.

However, such a conventional beacon type WPAN system has the following problems.

In general, the coordinator 10 or the router 20 obtains, maintains and manages a list of subordinate nodes through association with itself and subordinate nodes, and always checks for changes such as movement of subordinate nodes. . However, if the parent node loses the list of the child nodes at any moment for some reason such as system instability, power off of the system, the parent node cannot generate the proper beacon signal for wireless communication, and the child node can know the situation. It is left unattended in a network mismatch environment.

Over time, the system will recover and this network inconsistency may be resolved, but the elapsed time may take a long time. Also, depending on the system, even if this condition persists for a short time, it may cause a great loss due to instability of the entire system.

On the other hand, the coordinator 10 can form a new WPAN network by re-executing the WPAN network start procedure to terminate the network mismatch situation, but this process is not only time-consuming but also ensures the sameness of the new WPAN and the old WPAN. Since it can not be done, it is still not possible to eliminate the malfunction of the system.

It is an object of the present invention to provide a wireless communication method and system for a WPAN network that improves the stability of a system by resolving network inconsistency in a minimum time when network information inconsistency occurs between an upper node and a lower node.

It is an object of the present invention to provide a wireless communication method and system for a WPAN network that simply prevents network inconsistency by loading an ID of a lower node in a beacon frame transmitted from an upper node.

The present invention relates to a wireless communication method in a beacon-type wireless personal area network environment in which a beacon frame is periodically transmitted from an upper node to a lower node, the ID indicating a network connection state of all lower nodes belonging to the upper node. Transmitting a beacon frame including information to a lower node; Analyzing, at all lower nodes belonging to the upper node, ID information of the beacon frame to determine whether the upper node is recognized as being connected to the network; And in the lower node, attempting to reconnect to the upper node when it is determined that the analysis result is recognized by the upper node as not being connected to the network.

In addition, the present invention is a wireless communication system in a beacon type wireless personal area network environment in which beacon frames are periodically transmitted from an upper node to a plurality of lower nodes, the upper node including a list of lower nodes belonging to the child And a beacon frame, wherein the beacon frame includes ID information of lower nodes recorded in the child list table, wherein each lower node transmits a signal packet to the upper node in synchronization with the beacon frame. The node may determine that the corresponding lower node is not included in the network when the signal packet reception from the lower node is poor.

Hereinafter, with reference to the accompanying drawings showing a preferred embodiment of the present invention will be described in detail the present invention.

2 is a beacon signal configuration diagram in a WPAN network according to an embodiment of the present invention. The WPAN network of FIG. 2 is based on the IEEE 802.15.4 standard.

In FIG. 2, a PHY protocol data unit (PPDU) is a signal packet unit transmitted / received in a physical layer (Physical Layer or PHY Layer) including an RF terminal and a related control mechanism of a device, and includes a SHR (Synchronization Header) and a PHY Layer Header (PHR). ) And MPDU (MAC Protocl Data Unit). The MPDU is a protocol data unit in a media access control layer (MAC layer) that provides a connection function with a physical layer for transmitting and receiving signals of all kinds, and MHR (MAC header) and NPDU (NWK protocol data unit). And MFR (MAC Footer). NPDU contains network configuration, operation and message routing information and consists of NHR header and NWK payload. Since the above is given by the IEEE 802.15.4 standard, a detailed description thereof will be omitted.

A beacon signal frame according to an embodiment of the present invention includes an n-bit management field and an n-bit packet request field provided for managing n subnodes in a network payload.

FIG. 3 exemplarily illustrates management field and packet request field information of a beacon signal according to an embodiment of the present invention, and FIG. 4 illustrates a memory configuration of an upper node generating the beacon signal of FIG. FIG. 5 is a diagram illustrating operation of a WPAN network according to an embodiment of the present invention with reference to FIGS. 3 and 4.

In FIG. 4, a device (Parent Device, hereinafter referred to as "parent") corresponding to an upper node includes a table of a list of devices (Child Device, hereinafter referred to as "child") corresponding to a lower node in its memory. do. In FIG. 5, the coordinator 10 becomes a parent for all routers 20, and each router 20 becomes a child for the coordinator 10 and a parent for the terminal 30 corresponding to its subordinate node. Becomes

The chart list table stored in the memory of the parent includes an extended address, a short address, and a packet reception timer field of each child. The extended address is a 64 bit (or 8 byte) address unique to each device, and the short address consists of 16 bits (2 bytes) as the relative address of each device within a given WPAN. Once the configuration of the WPAN is determined, the short address for each device is determined, and the coordinator 10 assigns the short address to the devices of the lower node through an association process with the devices of the lower node.

The short address of the child may be given as follows.

Short Address of nth child = p + 1 + (n-1) * q, n = 1, 2 ...

Here, p denotes a short address of the parent, q is a constant determined by the number of children the parent can have when the WPAN is set, and the q value is determined when the structure of the WPAN is determined. The child depth is information on how many layers the children are configured. In FIG. 5, the child is composed of two layers of a router and a terminal. Depending on the WPAN, routers may be configured in two or more layers.

In the case of the WPAN of FIG. 5, the short address of the coordinator is "0", and the short addresses of the routers are sa _R1 = 1, sa _R2 = 7, sa _R3 = 13, sa _R4 = 19, ..., sa _Rn = 1+ (n-1) * 6. The short address of each device in the WPAN of FIG. 5 is shown, where q value for the short address of the routers is 6 and q value for the short address of the terminals is 1. FIG.

Referring to FIG. 3, each bit of a management field of a network payload of a beacon frame transmitted from a parent corresponds to an n value. That is, when a child whose short address is p + 1 + (n-1) q is connected by mapping the n value related to the child with the nth bit of the management field, the parent pays the network payload of the beacon frame transmitted by the parent. Set the nth bit of the management field of to 1. On the contrary, the parent, which has determined that the nth number is not connected, sets the nth bit of the management field to zero.

When the child receives the beacon signal from the parent, the child checks whether the bit corresponding to its short address is set to 1, and if it is set to 1, it is regarded as a normal connection and performs necessary data communication. It assumes that the parent is not recognized and attempts to reconnect to the parent. The reconnection process is performed according to the normal network joining procedure such as synchronization acquisition and association.

On the other hand, when a parent receives a signal packet from a child, the parent sets a packet reception timer, and if the time from receiving one packet to receiving the next packet exceeds a predetermined time t (eg, 10 seconds), the child Request a packet from. To request a packet, obtain n through the relation of p + 1 + (n-1) q from the short address of the child, and set the nth bit of the packet request field of the network payload of the beacon frame to 1 to beacon signal. Send.

Thereafter, the parent clears the nth bit of the packet request field to zero when the child sends the packet and resets the timer, and if the child does not transmit the packet for an additional time t '(e.g. 5 seconds), Clear the n th bit of the packet request field to 0 and delete the data associated with the child.

In FIG. 5, a case where the coordinator (C) 10 is a parent and n routers (R1... Rn) 20 are children will be described as an example. In the case of communication between the parent C and the first child R1, the short address of the first child R1 becomes 1 since the short address sa _c = 0 of the parent in the child list table of FIG. 4, and the packet reception timer is Currently 12 seconds.

Since the first bit of the management field of FIG. 3 is "1", the parent determines that the first child is currently subscribed to the WPAN, but since the packet reception timer has passed the set time of t = 10 seconds, the packet is requested to the corresponding child. To do this, the first field of the packet request field is set to "1". If the child sends a response packet within an additional time (t '= 5 seconds), i.e., until the packet reception timer is 15sec, the parent will only clear the first bit of the packet request field to "0", but until then the response packet If this is not sent, the parent will clear the corresponding bits in both the management field and the packet request field to "0" and determine that the child is no longer subscribed to the WPAN and delete the relevant data from the child list table. Then, when the child receives the beacon signal from the parent, the child checks that the corresponding bit is set to 0 in the management field and attempts to reconnect to the parent.

On the other hand, in the case of communication between the parent C and the second child R2, the short address of the second child R2 is 1 + q = 7 since the short address sa _c = 0 of the parent in the child list table of FIG. The packet reception timer is currently 6 seconds. Since the second bit of the management field and the packet request field of FIG. The situation is judged to be no problem.

On the other hand, in the case of communication between the parent C and the third child R3, since the third bits of the management field and the packet request field of FIG. 3 are all "0", this means that the parent has no data transmission and reception with the corresponding child. It is determined that the child leaves or withdraws from WPAN and deletes the relevant data (ie, packet reception timer information of FIG. 4). In this case, when the child receives the beacon signal from the parent, the child checks that the corresponding bit is set to "0" in the management field and attempts to reconnect to the parent.

The fourth child R4 is in the same state as the first child R1, and the nth child Rn is the same as the second child R2. Overall, the routers currently recognized as parent by the coordinator (C) are R1, R2, R4, and Rn, and the parent sends R1 and R4 a packet request signal to confirm the WPAN subscription status. The router R3 deleted from the child list of the coordinator C will perform the procedure for newly joining the WPAN.

In the above description, although an embodiment of the present invention has been described on the premise of communication between a coordinator and a router, it is apparent that an operation for resolving network inconsistency may be performed in the same manner between a parent and a child having a child relationship. .

In addition, the short address allocation method, the time limit of the packet reception timer, the entire configuration of the WPAN, the configuration of the management field and the packet request field are exemplary and can be changed by those skilled in the art.

In addition, although the parent uses the management field and the packet request field as means for informing the child of the child's acknowledgment status, other information related to the child that the parent recognizes as being connected to the network, that is, the ID of the child. Any information including a method of transmitting information in a beacon signal frame from the parent may be included in the scope of the present invention.

According to the present invention, there is provided a wireless communication method and system for a WPAN network that improves the stability of the system by eliminating network inconsistency in a minimum amount of time.

According to the present invention, there is provided a wireless communication method and system for a WPAN network that simply prevents network inconsistency by putting an ID of a lower node in a beacon frame transmitted from an upper node.

Although the present invention has been described above according to a preferred embodiment of the present invention, the scope of the present invention is not limited to the above embodiments or the accompanying drawings, and is not limited to the scope of the present invention as set forth in the appended claims. Various variations are possible in.

Claims (14)

A wireless communication method in a beacon type wireless personal area network environment in which a beacon frame is periodically transmitted from an upper node to a lower node, Transmitting, by the upper node, a beacon frame including ID information indicating network connection status of all lower nodes belonging to the lower node to the lower node; Analyzing, at all lower nodes belonging to the upper node, ID information of the beacon frame to determine whether the upper node is recognized as being connected to the network; And And in the lower node, attempting to reconnect to the upper node when it is determined that the analysis result is recognized by the upper node as not being connected to the network. The method of claim 1, The ID information includes a management field for indicating the network connection status of the lower nodes in binary. The method of claim 2, In the upper node, the bit of the management field corresponding to the lower node determined to be connected to the network by the upper node is set to "1", and is determined to be not connected to the network by the upper node. And setting the bit of the management field corresponding to the lower node to be "0". The method of claim 3, wherein The ID information further includes a packet request field for requesting packet transmission to a lower node. Receiving a signal packet from the lower nodes at the upper node; The beacon frame transmission step, In the upper node, the bit of the packet request field corresponding to the lower node having no packet transmission for the first predetermined time is set to "1", and corresponds to the lower node for which packet transmission is made within the first predetermined time. And setting the bit of the packet request field to “0”. The method of claim 4, wherein If the higher node set the bit of the packet request field to "1", The beacon frame transmission step, Determining whether a response packet is received from a lower node corresponding to the bit within a second predetermined time; Setting a bit of the management field to "0" if the response packet is not received within the second predetermined time, and setting a bit of the management field to "1" if the response packet is received; And And setting a bit of the packet request field corresponding to the lower node to "0". The method of claim 5, Analyzing ID information of the beacon frame in the lower node, And determining whether a bit of the management field corresponding to the lower node is "1" or "0". The method according to any one of claims 1 to 6, The wireless personal area network is an IEEE 802.15.4 based network, the upper node is a coordinator, and the lower node is a router. The method according to any one of claims 1 to 6, The wireless personal area network is an IEEE 802.15.4 based network, the upper node is a coordinator or a router, and the lower node is a terminal. A wireless communication method in a beacon type wireless personal area network environment in which a beacon frame is periodically transmitted from an upper node to a lower node, Transmitting, by the upper node, a beacon frame including ID information of the lower node, which is recognized by the upper node, to the lower node; Analyzing, at all lower nodes belonging to the upper node, ID information of the beacon frame to determine whether its ID information is included; And And attempting to reconnect to a higher node from a lower node that does not include its ID information as a result of the analysis. The method of claim 2, And the ID information is a short address of a lower node recognized as being connected to a network by the upper node. A wireless communication system in a beacon-type wireless personal area network environment in which beacon frames are periodically transmitted from an upper node to a plurality of lower nodes, The upper node has a child list table including a list of lower nodes belonging to the upper node. The beacon frame includes ID information of lower nodes recorded in the child list table, Wherein each lower node transmits a signal packet to the upper node in synchronization with the beacon frame, And the upper node determines that the lower node is not included in the network when signal packet reception from the lower node is poor. The method of claim 11, The ID information includes a management field indicating a network connection state of the lower nodes in binary and a packet request field for requesting packet transmission to a lower node, wherein each bit of the management field and the packet request field is the respective lower node. Wireless communication system, characterized in that corresponding to. The method of claim 12, The upper node performs a packet request to the specific lower node by changing bit information of the packet request field corresponding to the specific lower node when signal packet reception from a specific lower node is poor. And setting bit information of the management field according to whether a response packet is transmitted. The method of claim 13, The child list table further includes a packet reception timer field for checking a packet transmission time from all lower nodes. When the response packet transmission from the specific lower node is not performed within a predetermined time, the specific lower node Determine not to be included in the network, and delete the specific lower node information from the child list table.

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