JP2012049824A - Radio communication system, interference prevention method - Google Patents

Abstract

Communication interference between two or more wireless communication networks having different physical layers is prevented.
When preventing communication interference between wireless communication networks 10a and 10b having different communication standards, a coordinator 3a in each wireless communication network 10 performs other wireless communication before the first superframe immediately after power-on. In addition to providing a scanning period for scanning the coexistence notification signal transmitted from the coordinator 3b in the network 10b over a predetermined period, the coexistence notification signal is negotiated with another wireless communication network 10b that can coexist in advance. When the coexistence notification signal transmitted from the coordinator 3b in the other wireless communication network 10b is acquired in the scanning period, the communication interference with the other wireless communication network 10b is prevented. Take control.
[Selection] Figure 3

Description

  An object of the present invention is to provide a radio communication system and an interference prevention method suitable for preventing communication interference between radio communication networks of different communication standards in radio communication networks that perform radio communication between a plurality of devices and a coordinator.

  A wireless LAN (Local Area Network) reduces the space for a cable as compared with a wired LAN, and portable terminals such as notebook personal computers (notebook PCs) impair portability. There are advantages such as being able to connect to a LAN without any problems. In addition, since the wireless LAN itself has become faster and cheaper, the practical use of the wireless LAN is further accelerated. Against this background, standardization of wireless LAN is being promoted by the Institute of Electrical and Electronics Engineering (IEEE).

  Particularly in a wireless packet communication system typified by a wireless LAN, contention of wireless resources among a plurality of terminals is regarded as a problem. In order to avoid the competition of radio resources, medium access control (MAC) is necessary. As a MAC protocol in this wireless LAN, a so-called carrier sense is performed in which a terminal detects a carrier wave of another terminal before transmitting a packet, and when the carrier cannot be captured, a CSMA (Carrier Sense Multiple Access) is transmitted. ) Method has been proposed. Also, a CSMA / CA scheme (Carrier Sense Multiple Access with Collision Avoidance) is proposed in which a mechanism for avoiding packet collision is added to the CSMA scheme.

  In this CSMA / CA system, when communication is started and a response of an ACK (Acknowledge) signal is received from the wireless node of the communication partner, it is considered that communication is successful, and when an ACK signal is not received In this system, it is assumed that a communication collision with another wireless node has occurred, and the packet data is retransmitted again with a back-off time.

  In particular, in recent years, the CSMA / CA system is increasingly compliant with the IEEE 802.15.3c standard. The IEEE 802.15.3c standard uses millimeter waves in the 60 GHz band. This millimeter wave has characteristics that it has a strong straight traveling property and a large spatial propagation loss compared to a microwave. In particular, in the 60 GHz band, the amount of attenuation is larger and the space can be easily divided, and the influence of interference on the other side of the wall or in a slightly separated place can be reduced, which is suitable for high-speed communication in a short-distance indoor space. IEEE 802.11ad is also a 60 GHz high-speed wireless network.

  In wireless communication based on the IEEE 802.15.3c standard, as shown in FIG. 7, an NC (Network-Coordinator) 71 capable of transmitting and receiving piconet data for controlling the network 7 and a plurality of EDs (End Devices) 72 are used. It is common to perform wireless communication. Incidentally, as an example of the network 7, various network forms such as a star type, a tree type, and a mesh type can be selected.

  In wireless communication based on the IEEE 802.15.3c standard, a so-called superframe structure using a beacon is used. In this superframe structure, a CAP (Contention Access Period) in which all EDs 72 can access the beacon interval, a CFP (Contention Free Period) that can be accessed exclusively by a specific ED 72, and an inactive period in which all EDs 72 are prohibited from accessing. It is divided into. Further, the CFP is divided into seven equal parts by a GTS (Guaranty time Slot) mechanism, and can be assigned to the ED 72 to which communication is preferentially performed.

  For example, Patent Documents 1 and 2 have been proposed as conventional wireless packet communication systems based on the IEEE 802.15.3c standard. As techniques for minimizing packet collisions in the CSMA / CA scheme, for example, disclosed techniques of Patent Documents 3 and 4 have been proposed.

JP-A-2005-102218 JP 2008-026310 A JP 2004-242204 A JP 2006-197177 A

  However, for example, as shown in FIG. 8, two or more networks 7, 7 ′ may coexist. The network 7 includes an NC 71 and a plurality of EDs 72. The network 7 ′ includes an NC 71 ′ and an ED 72 ′, and performs wireless communication via different communication standards.

  Examples of the different communication standards include those based on IEEE 802.11ad, 2.4 / 5 GHz WLAN, IEEE 802.15.3c WPAN, and the like.

  However, when two or more networks 7 and 7 ′ having different communication standards coexist, communication interference may occur between them. That is, communication between the NC 71 and the ED 72 in the network 7 may be interfered by communication performed between the NC 71 ′ and the ED 72 ′ in the other network 7 ′. This is because there is no exchange between the NCs 71 and NC 71 ′ serving as the central control unit in the respective networks 7 and 7 ′. This is because wireless communication is performed via the network.

  For this reason, in the wireless communication system in which two or more networks 7 and 7 ′ having different communication standards coexist, the necessity to devise an interference prevention method capable of preventing communication interference is increasing in recent years. there were.

  Therefore, the present invention has been devised in view of the above-described problems, and the object of the present invention is to coexist radio communication networks of different communication standards, and each of the radio communication networks includes a plurality of devices and a coordinator. An object of the present invention is to provide a radio communication system and an interference prevention method capable of preventing communication interference between such radio communication networks in a radio communication system that performs radio communication between them.

  In the wireless communication system according to the present invention, wireless communication networks of different communication standards coexist in order to solve the above-described problems, and each of the wireless communication networks is a wireless that performs wireless communication between one or more devices and a coordinator. In a communication system, a coordinator in each wireless communication network provides a scanning period for scanning a coexistence notification signal transmitted from a coordinator in another wireless communication network for a predetermined period before the first superframe immediately after power-on. At the same time, it transmits its own coexistence notification signal in a format determined in advance with other wireless communication networks that can coexist, and the coexistence notification signal transmitted from the coordinator in the other wireless communication network during the scanning period. When acquiring the is characterized in that for performing control to prevent communication interference between the other wireless communication network.

  In the wireless communication system according to the present invention, wireless communication networks of different communication standards coexist in order to solve the above-described problems, and each of the wireless communication networks is a wireless that performs wireless communication between one or more devices and a coordinator. In a communication system, a coordinator in each wireless communication network provides a scanning period for scanning a coexistence notification signal transmitted from a coordinator in another wireless communication network for a predetermined period before the first superframe immediately after power-on. At the same time, it sends out multiple types of its own coexistence notification signal for each format of communication standards adopted by other wireless communication networks that can coexist, and is transmitted from the coordinator in other wireless communication networks during the above scanning period. When acquiring the coexistence notification signal corresponding to the format, and performs control to prevent communication interference between the other wireless communication network.

  In order to solve the above-described problem, an interference prevention method according to the present invention prevents communication interference between wireless communication networks having different communication standards in wireless communication networks performing wireless communication between one or more devices and a coordinator. In the interference prevention method, the coordinator in each wireless communication network has a scanning period for scanning the coexistence notification signal transmitted from the coordinator in another wireless communication network for a predetermined period before the first superframe immediately after power-on. The coexistence notification signal transmitted from a coordinator in the other wireless communication network in the scanning period is transmitted in a predetermined format with other wireless communication networks that can coexist. The When obtained, and performs control to prevent communication interference between the other wireless communication network.

  In order to solve the above-described problem, an interference prevention method according to the present invention prevents communication interference between wireless communication networks having different communication standards in wireless communication networks performing wireless communication between one or more devices and a coordinator. In the interference prevention method, the coordinator in each wireless communication network has a scanning period for scanning the coexistence notification signal transmitted from the coordinator in another wireless communication network for a predetermined period before the first superframe immediately after power-on. In addition to providing multiple types of notification signals for each of the communication standards adopted by other wireless communication networks that can coexist with each other, and transmitting from the coordinator in the other wireless communication network during the above scanning period Standard When acquiring the coexistence notification signal corresponding to the formats it is characterized by performing control for preventing communication interference between the other wireless communication network.

  According to the present invention having the above-described configuration, the coordinator that has scanned the coexistence notification signal (CB) can identify the presence of another coordinator and the wireless communication network in the vicinity of the coordinator. . And the coordinator who acquired this CB can perform control for preventing communication interference with the other wireless communication network.

  In addition, when a CB is sent as described above, since the CB is originally described in a decipherable format decided in advance, the coordinator can decipher it even if it is a different communication standard. It becomes possible to know the existence of the other party's wireless communication system.

  Also, even if the other party's wireless communication networks that can coexist are unknown to each other, a plurality of types of CBs are created for each communication standard format of other wireless communication networks that may coexist. A plurality of types of CBs are transmitted. As a result, the coordinator of another newly entered wireless communication network can decode any CB and can know the existence of the counterpart wireless communication system.

It is a figure which shows the structural example of the radio | wireless communications system to which this invention is applied. It is a figure which shows the super-frame structure used for communication of the radio | wireless communications system to which this invention is applied. It is a figure for demonstrating the interference prevention method to which this invention is applied. It is another figure for demonstrating the interference prevention method to which this invention is applied. It is a flowchart which shows the process for actual interference prevention. It is a figure for demonstrating the other interference prevention method to which this invention is applied. It is a figure which shows the radio | wireless communications system which consists of conventional NC and several ED. It is a figure for demonstrating the problem of a prior art.

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

  FIG. 1 shows a configuration example of a wireless communication system 1 to which the present invention is applied. The wireless communication system 1 is composed of two wireless communication networks 10a and 10b. The wireless communication network 10a includes a plurality of devices 2a and a coordinator 3a that controls the entire network. The wireless communication network 10b includes a plurality of devices 2b and a coordinator 3b that controls the entire network.

  In the wireless communication system 1 illustrated in FIG. 1 described above, the case where the wireless communication network 1 is configured by two wireless communication networks 10a and 10b is illustrated. However, the present invention is not limited to this, and three or more wireless communication networks 10 are included. It may consist of.

  These wireless communication networks 10 perform communication between the device 2 and the coordinator 3 based on a communication standard such as IEEE 802.11ad, IEEE 802.15.3c WPAN, 2.4 / 5 GHz WLAN, or the like. The wireless communication network 10 is not limited to the star type as shown in FIG. 1, and any network form such as a tree type or a mesh type may be applied.

  The device 2 includes, for example, a notebook personal computer (notebook PC), various portable information terminals such as a mobile phone. The device 2 can perform wireless packet communication with the coordinator 3 at least in the WPAN, and further performs wireless packet communication with another device 2 via the coordinator 3.

  Similarly, the coordinator 3 may have the same configuration as the portable information terminal described above. The coordinator 3 plays a role as a central control unit. The coordinator 3 acquires a beacon transmitted from the device 2 and synchronizes them with each other to connect the device 2 to the WPAN.

  These two wireless communication networks 10a and 10b perform wireless communication between the coordinator 3 and the device 2 via their own communication standards (for example, one is IEEE802.11ad, the other is IEEE802.15.3c, etc.). . This means that the two wireless communication networks 10a and 10b are performing wireless communication between the coordinator 3 and the device 2 via different communication standards.

  The radio communication system 1 to which the present invention is applied uses a so-called superframe structure using a beacon 21 as shown in FIG. The superframe has a CAP (Contention Access Period) 22 and a CFP (Contention Free Period) 23 after the beacon 21. The time between the two beacons 21 is divided into a predetermined number of slots regardless of the period of the superframe. Incidentally, in this superframe structure, the number of slots constituting the CFP 23 is variable, and the number of slots constituting the CAP 22 is fixed. The CAP 22 is a period during which all the devices 2 can access, and the CFP 23 is a period during which the specific device 2 is exclusively accessible.

  Furthermore, in the radio communication system to which the present invention is applied, the coordinator 3 sequentially transmits a coexistence notification signal (CB) 27 for notifying its own existence. The CB 27 may be configured as a so-called beacon, or may be configured as a normal signal including a plurality of frames. The CB 27 may be based on, for example, WPAN 802.15.3c or WLAN 802.11ad or 2.4 / 5 GHz WLAN 802.11 a / b / g or a combination thereof as a physical layer. These specifications are examples, and any other physical layer specifications may be used.

  The CB 27 transmits at a predetermined interval or at a random interval, but it is necessary to transmit once per one or more superframes. Further, it is desirable to transmit the CB 27 at least once per super frame. This CB27 may belong to either CAP22 or CFP23. In addition, a scanning period 26 is provided before the first super frame immediately after power-on. The scanning period 26 is a period for scanning and capturing the CB 27 transmitted from the coordinator 3 in the other wireless communication network 10. The scanning period 26 may be at least a period between two adjacent CBs 27, or a period longer than the length of the superframe.

  Next, an interference prevention method for preventing communication interference between the wireless communication networks 2a and 2b having different communication standards by the wireless communication system 1 to which the present invention is applied will be described in detail.

  First, as shown in FIG. 3, it is assumed that the coordinator 3a in the wireless communication network 10a is operating and performing wireless communication with the device 2a under the above-described superframe structure. In addition, the coordinator 3a transmits the CB 27 once or more per one or a plurality of superframes. Thereafter, it is assumed that the power of the coordinator 3b of another wireless communication network 10b having a communication standard different from that of the wireless communication network 10a is turned on. As a result, in the coordinator 3b, the scanning period 26 starts before the first super frame immediately after the power is turned on.

  As an example, the scanning period 26 in the coordinator 3b is longer than the length of the superframe as shown in FIG. Therefore, by sending the CB 27 from the coordinator 3a once per superframe, the coordinator 3b can scan the CB 27 and catch it.

  The coordinator 3b that has scanned the CB 27 can identify the presence of another coordinator 3a in the vicinity of the CB 27 and the wireless communication network 10a. When the CB 27 is acquired, the coordinator 3b performs control for preventing communication interference with the other wireless communication network 10b. The coordinator 3b may start synchronization, communication middle stage, or communication of another channel as control for preventing communication interference.

  Similarly, as an example, the coordinator 3b transmits the CB 27 at least once per superframe as shown in FIG. As a result, when another coordinator 3c is newly powered on in the interference area, the CB 27 is captured in the scanning period 26 by the other coordinator 3c. The coordinator 3c executes various controls for preventing communication interference with the other coordinator 3b based on the captured CB27.

  Here, the coordinator 3a existing in the wireless communication network 10a transmits the CB 27 in a format determined in advance with another wireless communication network 10b that can coexist. For example, consider a case where the wireless communication network 10a communicates based on the IEEE 802.15.3c WPAN communication standard and the wireless communication network 10b communicates based on the IEEE 802.11ad communication standard. In this state, the wireless communication network 10a and the wireless communication network 10b can coexist with each other. The coexistence state means that communication is being performed between the coordinator 3a and the device 2a in the wireless communication network 10a, and the wireless communication network 10b enters from the middle, and communication is performed between the coordinator 3b and the device 2b. Means that it can happen to start.

  It is assumed that the wireless communication network 10a has a known communication standard with the other wireless communication network 10b that can coexist. That is, the wireless communication network 10a knows in advance that the wireless communication network 10b communicates based on the IEEE802.11ad communication standard, and the wireless communication network 10b communicates with the IEEE 802.15.3c WPAN. It is assumed that the communication based on the standard is known in advance. At this time, the wireless communication network 10a transmits the CB 27 in a format that can be decoded even by the wireless communication network 10b that performs communication based on the IEEE 802.11ad communication standard. It is assumed that the formats included in the CB 27 are determined in advance between the wireless communication network 10a and the wireless communication network 10b so that they can be decoded.

  When such a CB27 is sent from the coordinator 3a to the coordinator 3b, the CB27 is originally described in a decipherable format decided in advance. It becomes possible to decipher and to know the existence of the wireless communication system 10a on the other side.

  Conversely, the same applies to the CB 27 sent from the coordinator 3b. Even if the coordinators 3c in other wireless communication networks 3 that can coexist are different communication standards, by creating the CB 27 in a format that can be read by each other, The acquired coordinator 3c can know the existence of the counterpart wireless communication system 10b.

  Each coordinator 3 operates based on the flowchart shown in FIG.

  First, in step S11, after the power of the coordinator 3 is turned on, scanning is performed in the scanning period 26 in step S12. As a result, in step S13, if CB can be captured from the other coordinator 3, the process proceeds to step S15. If not, the process proceeds to step S14.

  When the process proceeds to step S14, it means that no other coordinator 3 exists in the vicinity. In such a case, its own CB 27 is transmitted at a predetermined interval or at an arbitrary interval. At the same time, an area may be allocated to the super frame and communication may be performed with the device 2.

  When the process proceeds to step S15, it means that another coordinator 3 exists in the vicinity. In such a case, it is determined whether or not to start communication on another channel. If it is not determined to start communication on another channel, the process proceeds to step S16, and communication with the device 2 is started while synchronization with another coordinator is performed, or communication is stopped. . On the other hand, if it is not determined to start communication on another channel, the process proceeds to step S17, and communication with another device 2 is started on an empty channel.

  In this manner, even when two or more wireless communication networks 10 having different physical layers coexist, it is possible to prevent communication interference from occurring by performing negotiation between the coordinators 3.

  The present invention is not limited to the above-described embodiment. For example, as shown in FIG. 6, the communication standard adopted by another wireless communication network 10 that can coexist with its own coexistence notification signal CB27. A plurality of types may be transmitted for each format. FIG. 6 shows an example in which the counterpart wireless communication networks 10 that can coexist are not known to each other and are unknown.

  At this time, a plurality of types of CBs 27a and 27b are transmitted from the coordinator 3a as shown in FIG. The plurality of types of CBs 27a and 27b are created in a format that can be decoded for each different communication standard. For example, the CB 27a is created in a format that can be decoded by the wireless communication network 10 according to the IEEE 802.15.3c WPAN communication standard, and the CB 27b can be decoded by the wireless communication network 10 according to the IEEE 802.11ad communication standard. Created in format.

  When another wireless communication network 10b is newly entered, the coordinator 3b can decode the CB27a if it communicates with the IEEE802.15.3c WPAN communication standard, and the IEEE802.11ad communication standard. CB27b can be decoded if there is anything to communicate with. Then, the coordinator 3b that has decoded either CB27a or CB27b can know the existence of the counterpart wireless communication system 10a.

  That is, even if the coexisting wireless communication networks 10 on the other side are unknown to each other, without interfering with each other between IEEE802.11ad and IEEE802.15.3c, or 2.4 / 5GHz WLAN, A plurality of types of CB 27a and CB 27b are created for each communication standard format of another wireless communication network that may coexist, and the plurality of types of CB 27a and CB 27b are transmitted. As a result, the coordinator 3b of another newly entered wireless communication network 10b can decode either the CB 27a or the CB 27b, and can know the existence of the counterpart wireless communication system 10a.

1 wireless communication system 2 device 3 coordinator 10 wireless communication network 21 beacon 22 CAP
23 CFP
26 Scanning period 27 CB

Claims (8)

Wireless communication networks of different communication standards coexist, and each of the wireless communication networks is a wireless communication system that performs wireless communication between one or more devices and a coordinator.
The coordinator in each wireless communication network provides a scanning period for scanning a coexistence notification signal transmitted from the coordinator in another wireless communication network for a predetermined period before the first superframe immediately after power-on, and When a coexistence notification signal is transmitted in a predetermined format with other wireless communication networks that can coexist, and the coexistence notification signal transmitted from the coordinator in the other wireless communication network is acquired during the scanning period. Is a wireless communication system characterized by performing control for preventing communication interference with the other wireless communication network. Wireless communication networks of different communication standards coexist, and each of the wireless communication networks is a wireless communication system that performs wireless communication between one or more devices and a coordinator.
The coordinator in each wireless communication network provides a scanning period for scanning a coexistence notification signal transmitted from the coordinator in another wireless communication network for a predetermined period before the first superframe immediately after power-on, and Multiple types of coexistence notification signals are transmitted for each format of communication standards adopted by other wireless communication networks that can coexist, and are transmitted from the coordinator in other wireless communication networks in accordance with the format of their own communication standards during the scanning period. In addition, when the coexistence notification signal is acquired, control for preventing communication interference with the other wireless communication network is performed. The wireless communication system according to claim 1 or 2, wherein the coordinator provides the scanning period having a length equal to or longer than the length of the superframe. Either one or both of the coordinator immediately after power-on and the coordinator in another wireless communication network start synchronization, communication middle stage, or communication of another channel as control for preventing communication interference. The wireless communication system according to any one of claims 1 to 3. In an interference prevention method for preventing communication interference between wireless communication networks of different communication standards in a wireless communication network that performs wireless communication between one or more devices and a coordinator,
The coordinator in each wireless communication network provides a scanning period for scanning the coexistence notification signal transmitted from the coordinator in the other wireless communication network for a predetermined period before the first superframe immediately after the power is turned on. When a coexistence notification signal is transmitted in a predetermined format with other wireless communication networks that can coexist, and the coexistence notification signal transmitted from the coordinator in the other wireless communication network is acquired during the scanning period. Is a control method for performing control for preventing communication interference with the other wireless communication network. In an interference prevention method for preventing communication interference between wireless communication networks of different communication standards in a wireless communication network that performs wireless communication between one or more devices and a coordinator,
The coordinator in each wireless communication network provides a scanning period for scanning the coexistence notification signal transmitted from the coordinator in the other wireless communication network for a predetermined period before the first superframe immediately after the power is turned on. Multiple types of coexistence notification signals are transmitted for each format of communication standards adopted by other wireless communication networks that can coexist, and are transmitted from the coordinator in other wireless communication networks in accordance with the format of their own communication standards during the scanning period. When the coexistence notification signal is acquired, control for preventing communication interference with the other wireless communication network is performed. The interference prevention method according to claim 5, wherein the scanning period is longer than the length of the superframe. Either one or both of the coordinator immediately after power-on and the coordinator in another wireless communication network perform synchronization, middle stage of communication, or start communication of another channel as control for preventing the communication interference. The interference prevention method according to any one of claims 5 to 7, wherein:

Images