JP2002271262A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent radio wave interference between a slave station and a neighboring network, without affecting the communication of the slave station, where radio wave interference is not occurring. SOLUTION: In the radio communication system, where the slave stations A1-A3 communicate data, according to the frame timing in the radio space that the key station A0 controls, if the slave station A3 detects a wave interference with the neighboring radio communication system, the slave station A3 informs the key station A0 of that effect, so that the key station A0 controls the frame timing of only the slave station A3 where wave interference has occurred, so that the other slave stations may not be caused wave interference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-speed data communication such as a compressed moving image or audio data stream and asynchronous packet communication between one master station and one or more slave stations mainly in a home. The present invention relates to a wireless communication system suitable for performing the communication.

[0002]

2. Description of the Related Art Mainly at home, 5 GHz to 60 GH
2. Description of the Related Art A wireless communication system that performs high-speed data communication such as a compressed moving image or audio data stream and asynchronous packet communication between a master station and a slave station or between slave stations using a wireless band of z is known.

[0003]

When a wireless network using such a wireless communication system is constructed in two adjacent households, first, when there is no connection between the networks, one or both of the wireless networks are connected. When performing a new construction or reconfiguration of the mobile station, the distance between the two master stations is sufficiently large due to the carrier sense performed by the master station prior to determining the wireless channel, and without recognizing the existence of each wireless network, It is assumed that the same channel is selected.

However, even in such a case, a specific slave station among a plurality of slave stations belonging to the first wireless network must be close to the second wireless network of an adjacent household. In this case, there is a problem that a data error may occur because radio waves leaking from the second wireless network due to a wall or the like become interference waves. Also, as a method of preventing the radio wave interference between the slave station and the adjacent network that has occurred in this way, a method in which the slave station detecting the radio wave interference notifies the master station and the master station changes to a carrier of another frequency is considered. However, this method has a problem that it is necessary to suspend communication even in a slave station where no radio wave interference has occurred and to reconstruct communication with a carrier or the like.

The present invention has been made in view of the above-described problems of the prior art, and has been made in view of the above-described problems, and is capable of preventing radio interference between a slave station and an adjacent network without affecting communication between slave stations in which no radio interference occurs. The purpose is to provide.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a radio communication system in which, when radio interference occurs between a slave station (slave unit) and an adjacent wireless communication system, the radio interference is prevented from occurring. This is to manage the frame timing of only the slave station (slave) where the error occurs. That is, according to the present invention, in a wireless communication system in which a slave station performs data communication with the master station in accordance with a frame timing of a wireless space managed by the master station, the slave station is connected to another adjacent wireless station. If radio interference with the communication system is detected, the fact is notified to the master station, and only the slave station in which the radio interference has occurred so that the radio interference does not occur when the master station receives the notification. A wireless communication system characterized by managing the frame timing of the wireless communication.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of a wireless communication system according to the present invention.

First, a wireless communication system will be outlined with reference to FIG. 1 and FIG. FIG. 1 is a network model showing two stand-alone wireless networks (wireless communication systems) A and B that are not connected to each other. The wireless network A and the wireless network B have the same configuration, and their wireless service zones 1 and 2 are indicated by circles. In the wireless network A, slave stations A1, A2, and A3 are arranged around the master station A0, and similarly, in the wireless network B, slave stations B1, B2, and B3 are arranged around the master station B0. I have.

[0009] A circle 11 indicated by a broken line is a wireless network A.
3 schematically shows the radio wave reach range of the slave station A3, and shows that the master station A0 of the own wireless network and the slave station B3 of the adjacent wireless network B are within the wave reach range 11. Similarly, the master station B0 of the own wireless network B is located within the radio wave range 12 of the slave station B3 of the wireless network B.
Indicates that the slave station A3 of the adjacent wireless network A is located.

FIG. 2 schematically shows a frame structure applied in the wireless networks A and B. One frame unit (also simply referred to as a frame) 17 is from the first frame timing packet 20 to the first frame timing packet 21 and is defined as one cycle. Between the frame timing packet 20 and the following network management area 22, between the network management area 22 and the following data communication area 18, and between the data communication area 18 and the next frame timing of the next frame. A non-signal section 19 is provided between the packet 21.

The master station A is controlled by the network management area 22.
0 and B0 transmit and receive packets for managing the slave stations A1 to A3 and B1 to B3 under the wireless networks A and B, respectively, and the slave stations A1 to A3 and B1 to B3 reserve slots for data communication. Send and receive packets. The period from the end of the network management area 22 to the start of the next frame timing packet 21 is the data communication area 18, and the data communication area 18 is divided into n + 1 slots # 0 to #n. A band (area) reserved for data communication is performed in slot units, and an integer multiple of one slot band is secured.

Next, the basic operation of the wireless networks A and B will be described. The radio frequency bands used by the radio networks A and B are divided into m channels with an equal bandwidth so as not to interfere with other radio networks using the same frequency band. Before constructing the wireless networks A and B, the master stations A0 and B0 first confirm by carrier sense that there is no other wireless network or device using the same channel. The work of building the networks A and B starts. The master stations A0 and B0 are connected to the frame timing packet 2
When transmitting 0, carrier sense is performed for each frame 17 to make an effort to avoid interference.

The wireless network A thus constructed,
The main work of master stations A0 and B0 in B is radio space 1,
2 and manages the subordinate stations A1 to A
3. A frame timing packet 20 serving as a guide of the frame timing is transmitted to each frame 17 toward B1 to B3.
Is transmitted at the beginning of Slave stations A1 to A3, B1
B3 receives the frame timing packet 20 and refers to the counter value of the reference clock in the frame timing packet 20, corrects the counter value by the reference clock oscillator built in the own station, and synchronizes. The slots # 0 to #n in the frame 17 are accurately grasped so that radio wave collision does not occur in the same wireless networks A and B.

Basic transmission and reception of data in the wireless networks A and B is performed by a master station A in the wireless networks A and B.
0, B0 and among the stations including the slave stations A1 to A3 and B1 to B3, the receiving station called the listener receives the data transmitted using the slot #k to which the transmitting station called the talker is assigned, The communication is directly performed between the stations that are the main parties of data communication without passing through the master stations A0 and B0. For the slot reservation, the talker or listener requests the master station A0, B0 or the management station (not shown) of the band resource as required,
If the slot #k has a free space, it is established by allocating it. Note that, like the master stations A0 and B0, the talker also performs carrier sense prior to sending the data stream, and refrain from sending if there is a user of the same channel.

[0015] Such two wireless networks A and B
Are constructed adjacent to each other, if the distance between the adjacent wireless networks A and B is sufficiently short, the presence of the adjacent network can be reliably detected by measuring the interference radio wave by the carrier sense. Not used. In addition, if all stations belonging to both wireless networks A and B are in a completely separated state in which no interfering radio wave arrives, no problem occurs even if the same channel is used.

However, if the distance between the master station A0 of the wireless network A and the master station B0 of the wireless network B is such that the mutual radio waves cannot reach each other, two adjacent wireless networks A using the same channel are used. , B are conceivably constructed. In this case, the master station A
0 and B0 could not detect the presence of each other by carrier sense, but the slave stations A3 and B3 located at the boundary of two adjacent wireless networks A and B operate on the same channel. Adjacent wireless networks B and A
It is also conceivable to receive radio interference.

Referring to FIG. 1, the process by which adjacent wireless networks A and B use the same channel will be described. As an example, when the master station A0 newly establishes a wireless network A in a state where the wireless network B has started operation as a wireless network that has already been established, the channel that the master station A0 intends to use is adjacent to the adjacent wireless network. Even if it is already used in B, the master station A0
, The transmitted radio waves from the master station B0 and the slave stations B1 to B3 of the wireless network B cannot be detected because there is a sufficient distance. With this process, even if the two wireless networks A and B using the same channel are adjacent to each other, the wireless network A and the wireless network A have been established by a correct process.

However, the radio wave transmitted from the slave station A3 of the wireless network A has reached the slave station B3 of the adjacent wireless network B as indicated by the radio coverage area 11, and similarly, the The radio wave transmitted from the station B3 reaches the child station A3 of the adjacent wireless network A. this is,
Child stations A3 and B at the border belonging to the wireless networks A and B
3 indicates that there is a possibility that interference will occur with radio waves of the adjacent wireless networks B and A.

Next, a description will be given of a process in which radio interference occurs in the slave stations A3 and B3 at the boundary between the wireless networks A and B with reference to FIGS. FIG. 3 shows the flows of the data streams 30, 31, 32, and 33 in the example of the frame structure described with reference to FIG. 4 based on the network model of FIG. In FIG. 3 (and FIG. 4), in the wireless network A, the data stream 32 transmitted by the slave station A3 as a talker and received by the slave station A1 as a listener, and the data stream 32 transmitted by the slave station A1 as a talker are transmitted by the listener. A data stream 33 received by a certain slave station A3 has been established. In the wireless network B, a data stream 30 transmitted by the slave station B3 as a talker and received by the slave station B2 as a listener, and a data stream transmitted by the slave station B2 as a talker and received by the parent station B0 as a listener 31 have been established.

FIG. 4 shows the data stream 3 described in FIG.
The relationship between 0 to 33 and the frame structure is shown. In FIG. 4, the time axis 24 of the wireless network B and the time axis 25 of the wireless network A are drawn based on the same time series. The frame unit 26 of the wireless network B and the frame unit 28 of the wireless network A are obviously not synchronized. The reason for this is that the two wireless networks A and B are constructed as a stand-alone without connection between the networks. Time axis 24 of wireless network B
In the upper data communication area 27, each band for the data stream 30 and the data stream 31 shown in FIG.
In the data communication area 29 on the time axis 25, the bands for the data stream 32 and the data stream 33 shown in FIG.

In FIG. 4, when the data communication area 27 of the wireless network B and the data communication area 29 of the wireless network A are compared with the areas reserved as the data streams of the two areas 27 and 29, the data stream 30 of the wireless network B is Part of the data stream 33 of the wireless network A overlaps, indicating that interference has occurred. Note that the data stream 31 of the wireless network B partially overlaps the data stream 32 of the wireless network A, but as shown in FIG.
2 to the master station B0, and as shown in FIG. 1, it is outside the radio wave range 11 of the slave station A3 of the adjacent wireless network A, and does not receive interference.

The wireless networks A and B exemplified in the present invention
In the above, the talker performs carrier sense even before transmitting the data stream to avoid radio wave interference. Here, as shown on the time axis of FIG. 4, the carrier sense is performed immediately before the slave station A1 of the wireless network A sends out the data stream 33. At this point, the data stream 30 sent by the slave station B3 of the wireless network B is sent. Is not transmitted, and the slave station B3 of the wireless network B also performs carrier sense before sending the data stream 30, but the radio wave output intensity of the slave station A3 of the wireless network A causes unnecessary radio wave emission. The condition is that the result of the output control by the power control for suppressing is small, and it cannot be detected. In addition, in the case of a wireless network, the higher the frequency band is, the higher the directivity is. Therefore, it is conceivable that the reception radio field intensity becomes unbalanced between stations due to various factors.

As a means for solving the problem of the interference generated in this way, the channel of the wireless network A in which the failure has occurred is changed to the adjacent wireless network B.
In order to change to a different channel, a means of reconstructing the wireless network A has been considered. However, according to this means, by reconstructing the wireless network A, the data stream between slave stations not affected by radio wave interference is interrupted for the time required for the reconstruction work. In the case where the data stream is interrupted in this way, if there is no built-in means for storing the data from the interruption to the resumption, or for assuring the continuity of the data stream by means of retransmission or the like, the data stream without any problem is completely completed. As a result, the impact is enormous. In view of such a problem, in the present invention, only a station in which an error occurs in received data due to interference is dealt with so as not to affect a data stream in which interference does not occur.

The procedure of the interference avoidance system according to the present invention will be described with reference to FIG. FIG. 5 shows a sequence of a master station A0 that manages the wireless network A, a slave station A3 that receives the data stream 33, and events in the slave station A3. As described above, the slave station A3, which is receiving interference from the slave station B3 at the boundary with the adjacent wireless network B, generates a large number of packet CRC errors during communication (see FIG. 49) (see FIG. 49). 50). Here, any of the slave stations A1 to A1 belonging to the wireless networks A and B
A3 and B1 to B3 are also programmed so that the number of occurrences of CRC errors is limited in advance, and the occurrence of CRC errors more than a specified number is treated as a poor radio wave condition.

Slave station A3 receiving the data stream 33
Is the CRC of the received data stream 33 packet.
If the error occurs more than the specified number of times (shown in FIG. 50), it is determined that the radio wave state is poor due to interference, and a “data stream 33 temporary stop request” is transmitted to the master station A0 (shown in FIG. 51). The master station A0 receives this and processes necessary procedures. Although not shown, “Data stream 3
When the master station A0 receives the "3 suspend request", the master station A0 instructs the slave station A3, which is the talker of the data stream 33, to suspend the data stream transmission, and the master station A0 and the slave stations A1 to A1 in the wireless network A. The item relating to the data stream 33 is set to “pause” from the link list including the data link status between all the stations including A3. Then, the parent station A0 notifies the slave station A3 of a "data stream 33 suspension notification" as a notification to the received "data stream 33 suspension request" (see FIG. 52).

Next, after confirming that the data stream 33 has been temporarily stopped, the slave station A3 obtains a link list by means of obtaining a link list (FIG. 53). Next, the slave station A3 starts carrier sensing in an area that is not reserved on the link list as a data stream in its own wireless network A in the data communication area 29 shown in FIG. In the example of FIGS. 3 and 4, two wireless networks A in the wireless network B,
Data stream 3 occurring in a space near the boundary of B
A 0 carrier should be detectable.

The slave station A3 assigns the area where the unnecessary carrier has been detected in this way to the slot of the data communication area 29 in the wireless network A, and sets the slot information corresponding to the interference as a "prohibited slot setting request". A
0 (shown in FIG. 55). The master station A0 receives this and processes necessary procedures. The master station A0 records the slot requested by the “prohibited slot setting request” in association with the slave station A3. Then, the master station A0 notifies the slave station A3 of a "prohibited slot setting notification" as a notification to the requested "prohibited slot setting request" (FIG. 56). Next, the slave station A3 issues a “request for re-reservation of the data stream 33” in order to resume the temporarily stopped data stream 33.
To the master station A0 (see FIG. 57).

The master station A0, having received the "request for re-reserving the data stream 33", allocates a slot corresponding to the requested bandwidth if it is vacant, and temporarily stops the talker on the link list. The link list is updated with the new slot information in the data stream 33 from the slave station A1 as the listener to the slave station A3 as the listener. next,
The slave station A1 is notified to restart the transmission of the data stream 33 (not shown). Master station A that has completed the processing up to this point
0 is a request from the slave station A3 “data stream 3
As a notification to the request for re-reservation of "3," a notice of re-reservation of the data stream 33 is sent to the slave station A3 (FIG.
8). The slave station A3 resumes receiving the data stream 33 from the next frame in which the data stream becomes valid, and returns to the state of communication (59 in the figure).

[0029]

Since the present invention is configured as described above, the following effects can be obtained. 1. Regarding the problem of interference with an adjacent wireless network using the same channel, which may occur when the wireless network is applied in a home, a slave station located at the boundary of the wireless network and experiencing problems such as interference. Can be remedied. 2. Further, the process of rescuing a slave station from the above-described problem such as interference is performed without affecting other slave stations that do not cause interference.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a wireless communication system according to the present invention.

FIG. 2 is an explanatory diagram showing a frame structure of the wireless network shown in FIG. 1;

FIG. 3 is an explanatory diagram illustrating a link state in the configuration diagram of the wireless network illustrated in FIG. 1;

FIG. 4 is an explanatory diagram showing a link state and an interference state of the two wireless networks shown in FIG. 3;

FIG. 5 is an explanatory diagram showing a sequence for avoiding interference between the two wireless networks shown in FIG. 4;

[Explanation of symbols]

 A, B wireless network (wireless communication system) A0, B0 master station A1-A3, B1-B3 slave station

Claims (1)

[Claims] 1. A wireless communication system in which a slave station performs data communication with the master station according to a frame timing of a wireless space managed by the master station, wherein the slave station is adjacent to another wireless communication system. When the radio interference is detected, the fact is notified to the master station, and when the master station receives the notification, only the slave station in which the radio interference has occurred so that the radio interference does not occur. A wireless communication system for managing timing.