KR100730758B1 - Communications method and apparatus for a communications system employing a multiple of end devices - Google Patents

Abstract

A communication method in a communication system having plural lower nodes is provided to omit an association process during communication between upper nodes and lower nodes, thereby saving resources of the upper nodes required for managing the lower nodes and reducing power consumption. FFDs(Full Functional Devices)(R1-R3) transmit beacon frames. RFDs(Reduced Functional Devices)(E1-E6) receive the beacon frames, and decide whether data transceiving is necessary between the FFDs(R1-R3) and the RFDs(E1-E6). If so, the data transceiving is performed while association is not performed between the FFDs(R1-R3) and the RFDs(E1-E6), and the RFDs(E1-E6) are converted into a sleep mode. If the data transceiving is unnecessary, the RFDs(E1-E6) are immediately converted into the sleep mode.

Description

Communication Methods and Apparatus for a communications system employing a multiple of end devices}

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

2 is a diagram illustrating a signal frame format of an IEEE 802.15.4 based network.

3 is a configuration diagram of a network frame format in a WPAN network according to an embodiment of the present invention.

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

The present invention relates to a method and system for wireless communication in a wireless personal area network (WPAN) environment based on IEEE 802.15, and more particularly, communication between a higher node and a lower node in an environment in which a plurality of lower nodes frequently move. The present invention relates to a wireless communication method and system for saving resources and reducing power consumption of an upper node necessary to manage a lower node by omitting an association process.

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. RFD has no routing function, and there is no communication function between RFDs and is mainly used as an end device for simple applications that use only limited resources and memory. FFD has a multi-hop routing function using multiple frequencies. It can communicate with RFD and FFD, and can transmit beacon signal, so it can function as coordinator and router.

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 (E) 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 functions as a lower node having a minimum function.

Referring to the operation of the WPAN network, first, the coordinator 10 serving as the top node of the WPAN network periodically transmits a beacon to start a new WPAN network, thereby presenting its presence to the devices 20 and 30 of the lower node. When notifying, the routers 20 that have received the beacon join the WPAN generated by the coordinator 10 through an association process with the coordinator 10. After the association is successfully completed, data transmission and reception between the coordinator 10 and the routers 20 begins. Subsequently, when each router 20 subscribed to the WPAN transmits a beacon, the terminals 30 that receive the beacon join the WPAN through an association process with the router 20 corresponding to the higher node of the router 20 and the router 20. ) And data transmission and reception between the terminals 30 is started.

Some terminals E6 are directly associated with the coordinator 10 without passing through the router 20 to directly transmit / receive with the coordinator 10. Although not shown, the router 20 is arranged in two or more layers, and thus C → R. →… Association and data transmission and reception may be performed in a structure such as R → E. In any case, the association and communication process between the terminal 30, which is an RFD, and the FFDs 10, 20 of the upper node thereof may be performed in the following manner.

Looking at the association process between the FFD 20 and the RFD 30 in more detail, first, the RFD 30 as a lower node transmits an association request signal to the FFD 20 as an upper node, respectively, and the FFD correctly receives the signal. An optional acknowledgment signal indicating that the transmission is received is transmitted to the transmitting RFD. Subsequently, the FFD determines whether the available resources of the WPAN are sufficient for additional association for a predetermined time, and if the available resources are sufficient, an association response indicating success by allocating a 16-bit short address to be used as the address of the corresponding RFD in the WPAN. Send the signal to RFD. However, if there are insufficient resources available, an association response signal indicating an association failure is sent to the RFD. The RFD 30 joins the WPAN network through such an association process, and thereafter, may perform communication in the corresponding WPAN. In addition, during the communication, if the RFDs 30, which are the lower nodes, leave the WPAN for some reason, an association procedure for joining the WPAN is performed again.

2 illustrates a network frame format of devices of an IEEE 802.15.4 based network, which is a type of WPAN network.

The frame format of the network sublayer includes two octet (= 16 bit) frame control headers containing frame information, four or six octet routing fields containing routing information, and data information. It consists of a frame payload field of variable size. The routing field includes a destination address field containing a 16 bit short address of the target device and a source address field containing a 16 bit short address of the source device.

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 in FIG. 2 means a relative address of each device within 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 FFD generates a beacon signal carrying its short address. Thereafter, routing of communication signals in the WPAN network is performed through a short address.

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

For a system with a large number of RFDs, the FFD manages the RFDs that join the network. If the number of RFDs is small, there is no problem, but as the number of RFDs increases, the FFD must use more resources to manage the RFDs. This means that FFDs must spend a significant portion of the resources required to manage the WPAN during the association process.

In addition, in a system in which RFDs move frequently, the positions of a plurality of RFDs are changed so that communication with the FFD is lost and communication with other FFDs, or RFDs that have lost communication with any FFD, attempt to resume communication with the FFD. As the case arises, an association process frequently occurs between the FFD and the RFD. Moreover, associations may not proceed smoothly when multiple RFDs move at once.

Meanwhile, in the case of a WPAN in which RFDs are battery operated, it is necessary to minimize power consumption of RFDs. However, if the association process is performed for each movement of the RFD, the entire system consumes a lot of power just to maintain the network. That is, even if there is no data transmission required by the user, the RFD undergoes an association process to maintain the network only when a change of location occurs, so that the association process may be a problem in a battery-based system.

An object of the present invention is to provide a wireless communication method and system that can prevent unnecessary resource waste and excessive power consumption by not requesting an association but tracking the beacon of the FFD.

Another object of the present invention is to provide a wireless communication method and system capable of minimizing resource waste and power consumption by accepting a communication request of an RFD in which the FFD has not undergone an association process.

It is another object of the present invention to provide a wireless communication method and system capable of wireless communication even in an environment where association is not made by giving an extended address to communication between the FFD and the RFD.

In accordance with the present invention, a series of communication procedures, omitting the association process is as follows.

The RFD receives the beacon signal for a predetermined time, and selects an appropriate one from the received beacon signals to track the beacon signal. Since the beacon signal is generated at a predetermined period, when one beacon signal is selected, the RFD wakes up from the sleep mode only when the beacon occurs, receives the beacon signal, and returns to the sleep mode to reduce power consumption. During this process, the RFD does not perform an association process with the FFD.

When the RFD wants to transmit data to the FFD, it transmits a data frame. In this case, a 64-bit extended address is used for a source address field included in a data frame.

When the FFD has data to transmit to the RFD, the beacon signal is loaded with the extension address of the RFD to cause the RFD to send a data request signal. Since the FFD does not know which RFD is listening to its beacon signal, if there is no response from the RFD after a certain time, the FFD assumes that the RFD does not exist and deletes the extended address from the beacon signal.

If the RFD moves, simply discard the old beacon signal and track the new beacon signal. Since the FFD does not store information about the RFD, the RFD can move freely by changing the beacon signal generated by the FFDs.

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

3 illustrates a new network frame format in a WPAN network according to an embodiment of the present invention.

In FIG. 3, the frame format of the network sublayer is an additional target carrying a 64-bit extended address and an Extra Address Type field indicating whether the target device and the source device are devices using an extended address in the frame payload. Contains an Extra Detination / Source Extended Address field.

The address type in the additional address type field is as follows.

Extra Address Type Explanation 0 none One If the target device is a device that is not associated 2 If the source device is a non-associative device 3 If both the source device and the target device are nonassociative devices

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

In FIG. 4, a typical wireless communication process using a short address between FFD devices R1, R2, and R3 that is associated with the WPAN network coordinator C is shown in solid lines, and non-assigned RFD devices, that is, terminals (eg, terminals). The wireless communication process using the extended addresses associated with E1, E2, E3, E4, E5, E6) is shown in dashed lines.

One WPAN network is formed while broadcasting the beacon frame in the coordinator (C) and associating with the routers (R). In the WPAN network, the router R also broadcasts a beacon frame. The terminals E receive the beacon frame from the higher node, but do not perform the association process.

One terminal E may receive beacon frames from a plurality of upper nodes R. At this time, the terminal E selects an appropriate one among the beacon frames received through the channel evaluation process and tracks the corresponding beacon frame. Done. Since the beacon frame from the upper node R is generated at a predetermined period, when one beacon frame is selected, the terminal E wakes up from the sleep mode only when the beacon is generated, receives the beacon signal, and goes back to the sleep mode. The power consumption can be reduced by returning. If there is data to be transmitted from the upper node R to the terminal E through the analysis of the beacon signal, or there is data to be transmitted from the terminal E to the upper node R, the terminal E for the time required for the transmission. ) Operates in active mode, after which it returns to sleep mode to reduce power consumption.

Meanwhile, when the terminal E moves out of the WPAN to another WPAN area or moves between multiple routers R within one WPAN, the terminal E discards the existing beacon signal and a new beacon signal. Just track At this time, since the upper node R does not store information on the terminal E, each terminal E may move freely by changing beacon signals generated by the upper nodes.

Now, a communication method in which an association process is omitted according to an embodiment of the present invention will be described with reference to FIG. 4.

First, consider a case where the upper node of the terminal E1 is the router R1 and wants to transmit data to the router R3. The terminal E1 receives the beacon signal for a predetermined time and selects an appropriate one of the received beacon signals to track the corresponding beacon signal. The terminal E1 identifies the WPAN through the beacon signal from the router R1 and grasps the short addresses of the routers R1, R2, and R3 belonging to the WPAN. When transmitting data to the router R3, the terminal E1 inserts the short address of the router R3 into a destination address in its network frame format, and the WPAN as its upper node in the source address. Enter the short address of the associated router R1. The additional address type is " 2 " and the additional source extension address is its own extension address. Then, the data is transmitted in the order of the terminal E1 → router R1 → router R3 (processes ① and ②), and the router R3 receiving the data from the terminal E1 has an additional address type field and an additional address. The source sender address field can be analyzed to determine the signal sender.

Next, consider a case where the router R3 sends a response to the data received from the terminal E1. When sending a response to the terminal E1, the router R3 puts the short address of the router R1 associated with the WPAN as a higher node of the terminal to the target address in its network frame format, and its short address in the source address. Put it. Then, " 1 " is put in the additional address type, and the extension address of the terminal E1 is put in the additional target extension address. Then, the data is transmitted from the router R3 to the router R1 using the short address (process ③), and the router R1 sends the data to the terminal E1 by looking at the additional address type and the additional target extended address. (Step ④).

Also, consider a process of data transmission and reception between two devices that are not associated with the WPAN, such as transmission from the terminal E1 to the terminal E5. The terminal E1 inserts the short address of the router R1, which is the upper node of the target terminal E5, into the target address in its network frame format. In the additional address type, " 3 " is put in the additional source extension address, and the extension address of the target terminal E5 is put in the additional target extension address. Then, the data is transmitted in the order of the terminal E1 → router R1 → router R3 → terminal E5 (processes ①, ②, ⑤).

Now, let's look at each process of transferring data from the upper node to the lower node. In order to transmit data from the coordinator (C), which is an upper node, to the router (R), which is a lower node, the lower node first sends a data request signal by transmitting a short address of the lower node in the beacon signal. When the lower node is a terminal E not associated with the WPAN, the upper node R transmits the beacon signal with the extended address of the lower node, and the terminal E responds with data to the upper node R. Will send a request signal. At this time, since the upper node R does not know which lower node is listening to its beacon signal, if there is no response of the lower node after a certain time, the lower node is considered not to be the lower node and the corresponding extended address is deleted from the beacon signal. do.

On the other hand, since terminals E1, E2, E3, E4, E5, and E6 are not associated with the network, the terminal E1 does not know the short address of the upper node of the target terminal E5. In this case, the terminal E1 requests the coordinator C to find the target terminal E5 via the router R1. The coordinator C broadcasts the extended address of the target terminal E5 to the WPAN. In response, the target terminal E5 transmits the short address of the router R3, which is an upper node, from the coder C to the router R1. ) Is transmitted to the source terminal E1. When the upper node is the coordinator C as in the target terminal E6, the short address "0" of the coder C is transmitted to the source terminal E1.

On the other hand, some terminals E6 can directly receive and track the beacon of the coordinator (C) without passing through the router (R), the router (R) is arranged in two or more floors C → R →. As described above, communication may be performed in a structure such as? R → E. In this case, the present principles made between the FFD and the RFD are equally applicable.

On the other hand, the lower node of the present invention is preferably a battery operated terminal, the battery may be provided as a separate battery that is built in the terminal or connected to the terminal. When the present invention is applied to an IEEE 802.14.5 based Zigbee network mainly used in a sensor network, the lower node or the terminal of the present invention may be used in a form attached to an object to be sensed or a packaging material of the object.

According to the present invention, there is provided a wireless communication method and system that can prevent unnecessary resource waste and excessive power consumption by the RFD tracks the beacons of the FFD but does not request association.

In addition, according to the present invention, there is provided a wireless communication method and system capable of minimizing resource waste and power consumption by accepting a communication request of an RFD for which the FFD has not undergone an association process.

In addition, according to the present invention, there is provided a wireless communication method and system capable of wireless communication even in an environment where association is not made by giving an extended address to communication between the FFD and RFD.

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 (10)

In a wireless communication method in a wireless personal area network environment having a plurality of RFDs, Transmitting a beacon frame in the FFD; Determining the necessity of transmitting and receiving data between the FFD and the RFD after receiving the beacon frame in an RFD; If it is necessary to transmit and receive data, the RFD switches to a sleep mode after performing data transmission and reception without an association between the FFD and the RFD; And when the data transmission and reception is unnecessary as a result of the determination, the RFD immediately switches to a sleep mode. In a wireless communication method in a wireless personal area network environment having a coordinator, one or more routers, and a plurality of terminals, Transmitting a beacon frame at the coordinator; After receiving the beacon frame at a router, performing an association between the coordinator and the router; Transmitting the beacon frame at the router; And Performing necessary data communication between the coordinator, the router, and the terminals; And the terminals receiving the beacon frame from the coordinator or the router do not associate with the coordinator or the router. In the wireless communication method in a wireless personal area network environment having a plurality of sub-nodes, Transmitting a beacon frame at an upper node; Receiving the beacon frame at a lower node; And And a lower node having a routing function performs an association process with the upper node, and a lower node having no routing function does not perform the association process. In a wireless communication method in a wireless personal area network environment having a coordinator, one or more routers, and a plurality of terminals, Transmitting a beacon frame at the coordinator; After receiving the beacon frame at a router, performing an association between the coordinator and the router; Transmitting the beacon frame at the router; And Each terminal receiving the beacon frame includes a step of switching to the sleep mode after the data transmission and reception is completed if data transmission and reception is required, and immediately switching to a sleep mode when the data transmission and reception is not required. Communication method. A wireless communication method of a transmitting device in a wireless personal area network (WPAN) environment having a network frame structure comprising a source address field, a target address field, an additional source extended address field, and an additional target extended address field, If the transmitting device is associated with the WPAN, the transmitting device includes inserting its short address into the source address field, If the transmitting device is not associated with the WPAN, the transmitting device includes inserting a short address of its upper node into the source address field and inserting its extended address into the additional source extended address field, When transmitting to a receiving device associated with the WPAN, the transmitting device includes inserting a short address of the receiving device into the target address field, When transmitting to a receiving device not associated with the WPAN, the transmitting device inserts a short address of an upper node of the receiving device into the target address field and inserts an extension address of the receiving device into the additional target extended address field. Wireless communication method comprising a. The method according to any one of claims 1 to 5, The wireless personal area network (WPAN) is an IEEE 802.15.4 based network. In a wireless communication system of a wireless personal area network environment including a coordinator, one or more routers, and a plurality of terminals, The terminals track beacons from the coordinator or the router but do not transmit a signal requesting an association, and the coordinator and the router accept a communication request from the unassociated terminal. The method of claim 7, wherein The communication between the coordinator and the terminal, and the communication between the router and the terminal is performed using the extension address of the terminal. The method according to claim 7 or 8, The network frame format of the wireless personal area network includes a source address field, a target address field, an additional address type field, an additional source determined address field, and an additional target extended address field. The method of claim 9, The wireless personal area network is a wireless communication system, characterized in that the IEEE 802.15.4 based network.

Images