JP3423107B2 - Network method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network system, and more particularly to a communication system using spread spectrum communication, and is applicable to, for example, indoor wireless communication, mobile communication and the like.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 6-29981 discloses a transmission control system for a wireless local area network station. This control system is a local area network that receives a signal on a wireless transmission channel. A receiver for receiving a signal and a transmitter for transmitting a signal, the receiver level determining device representing a signal level received by the receiver through a transmission channel, and a threshold level circuit device for providing a level indicating signal. And a transmission control device that controls the operation of the transmission device based on the level instruction signal are intended to realize high LAN performance. Thus, the invention described in this publication is CSMA.
The present invention relates to a control method and a circuit configuration thereof in a wireless LAN using (Carrier Sense Multiple Access), and is common to the present invention in that spread spectrum communication is used and CSMA is used.

Further, Japanese Laid-Open Patent Publication No. 4-138734 discloses a spread spectrum communication system, which adopts a multiple access system by CSMA and uses a network configuration of an even distribution type. Each transmitting station has a different spreading code, and calls the partner station with the spreading code of the partner station to be transmitted. ・ When calling the partner station, carrier sense with the spreading code of the partner station before transmission, that is, The present invention is common to the present invention in that CSMA is performed by the spreading code of the partner station.

The multiple access method using CSMA allows line multiplexing with simple hardware.
It is desirable because it has better line utilization efficiency than the A method. On the other hand, when this method is used for a wireless LAN using spread spectrum communication, the spread spectrum communication method uses a wide frequency band, so simply using CSMA is wasteful in terms of frequency utilization efficiency. . In this spread spectrum communication, CDMA is used as a unique multiple access method.
(Code Division Multiple Acces). This method is a method in which the same frequency band can be used simultaneously by changing the code sequence of spread codes used in spread spectrum communication. The frequency utilization efficiency can be improved by using CDMA, and the communication throughput can be improved as compared with the case of using CSMA.

[0005]

Conventionally, CDMA has not been widely used in a wireless LAN using a spread spectrum system because the radio wave received from a desired station is significantly smaller than the radio wave from an undesired station. This is because there was a near-far problem that the station could not demodulate the information signal from the desired station. Normally, to avoid this, the radio wave of the desired station received by the receiving station is not buried in the radio wave of the undesired station,
The transmission power has been controlled by the desired station and the undesired station.
However, even if the transmission power control is performed in this way, some stations cannot be connected depending on the arrangement of the wireless stations. Therefore, in the conventional wireless LAN system, a centralized control type network as shown in FIG. 8 is used. Consists of a master station 10 and slave stations 10 ₁ to 1
It has been proposed to perform transmission power control between 0 _n and a multiple access system.

In the present invention, the network is divided into several sub-networks, the lines between the sub-networks are separated by a code division method in spread spectrum communication, and CSMA is performed in the sub-networks. Accordingly, it is an object of the present invention to provide a network system that does not require complicated transmission power control, can configure a network of equal distribution type, and has high frequency utilization efficiency.

[0007]

In order to solve the above problems, the present invention uses (1) in a communication system using spread spectrum communication, multiple access by CSMA within a sub-network and use between sub-networks. The communication between sub-networks is separated by using different spreading codes, and the communication between sub-networks is characterized in that the transmitting sub-network performs communication by using the spreading code of the receiving sub-network. Further, in the network method of (1) above, (2) when a new network is entered, the spread code used by another sub-network is used by the spread code already used by another sub-network. , And after allocating available spreading codes after testing and adjusting transmission and reception. In addition, (3) when a new sub-network is opened, the station that wants to open it selects an unused spreading code with reference to the information on the use status of the spreading code in another sub-network. , After the transmission / reception test and adjustment, a sub-network is opened by a new spreading code, and (4) when a station belonging to one sub-network changes its affiliation to another sub-network, Changing the spreading code to the spreading code used in the sub-network, changing the sub-network affiliation after testing and adjusting transmission / reception, and (5) removing the sub-network when the sub-network is to be canceled Stations that belonged to the network should deviate to the neighboring sub-network with the best communication quality after testing and adjusting transmission and reception. (6) when the sub-network selects a spreading code is obtained by characterized by the use of spreading codes that are not used in neighboring subnetworks.

[0008]

The spreading code is provided for each sub-network, and the spreading code used in the other sub-network is used when a station in one sub-network works on another sub-network. To avoid. According to the invention of claim 1, one network is constituted by a collection of sub-networks (in this case, the transmission control used in the conventional network cannot cope with this). The invention of claim 2 realizes a method of entry into a network by simpler transmission control by introducing a spreading code table as a method of entry of a new station into the network.

According to the invention of claim 3, like the invention of claim 2, by using the spread code table, transmission control is facilitated when a sub-network is opened.

According to a fourth aspect of the present invention, similarly to the second aspect of the present invention, by using the spread code table, transmission control is facilitated when the affiliation of stations between sub-networks is changed.

According to a fifth aspect of the present invention, when a sub-network is canceled, a station belonging to the sub-network to be canceled is made to belong to another sub-network having good communication quality, so that a network with good line efficiency can be obtained. provide.

According to a sixth aspect of the present invention, in spread spectrum communication, if the length of the period of the spread code is lengthened, it takes time to supplement the synchronization of the spread signal. Therefore, when the spread spectrum communication is used for a wireless LAN application, In order to increase the throughput, the cycle of the spreading code becomes short to some extent. If the cycle of the spreading code becomes short, the number of types of spreading code will decrease, and the spreading code that can be assigned to the sub-network will run short. Therefore, the invention of claim 6 solves the shortage of the spreading code by reusing the spreading code used in the sub-network where radio waves do not reach in the wireless network.

[0013]

【Example】

(Invention of Claim 1) FIG. 1 shows an example of a conceptual diagram of the present invention. FIG. 1 shows the entire network.
2, G3 are sub-networks, and G4 is an example in which one station constitutes one sub-network. At this time, the sub-networks G1, G2, G3 and G4 perform spread spectrum communication using the spread codes PN1, PN2, PN3 and PN4, respectively. Also, in each sub-network, CSMA multiplexes the lines within the sub-network. In this way, by changing the spreading code used in each sub-network, the interference given to the communication of each sub-network is reduced, so that the communication of each sub-network can be independent. If the distance between the two subgroups is too close to each other, mutual communication will be hindered even if code division is performed. In this case, the transmission power control is performed to avoid it by reducing the transmission power of each other, and if the failure still remains, the configurations of the stations belonging to the two sub-networks are changed.

Next, communication between sub-networks will be described. Communication between sub-networks is accessed using the spreading code of the other sub-network. For example, in the case of accessing from G1 to G2 in FIG. 1, the station in G1 uses PN1 and advises all stations belonging to G1 to use PN2. G1
All stations belonging to switch the spreading code used to PN2,
The sub-network G1 to G2 becomes one sub-group that uses PM2 (see FIG. 2). In this state, communication is performed between the G1 station and the G2 station, and after the communication is completed, the stations belonging to the group G1 are again in the spreading code PN.
1 is used to return to the state of FIG.

Although the basic operation of the present invention has been described above, the present invention may be performed even more dynamically. In the case of a wireless LAN, the stations frequently move, and the reception status of radio waves also changes depending on the movement of people and things around them. Further, when a group using a new spreading code is constructed or when a wireless station moves, it approaches another group, which causes a near-far problem. In such a case, the channel quality is improved by dynamically changing the stations forming the subgroup or reducing the transmission powers according to the situation change. Next, the operation of the network will be specifically described.

(Invention of Claim 2) <Entry into Network> In the case of a wireless network, particularly when a portable wireless terminal is a station, the station moves frequently, and it is introduced into or removed from the network. It can happen. When installing on a network, when installing on an existing subnetwork existing in the network, refer to FIG.
The flow chart shown in (a) may be followed. When the types of spreading codes are PN ₁ to PN _N , the spreading codes PN ₁ are used in order, carrier inquiries are performed to other sub-networks, an inquiry is made, and this is repeated until a reply is received. If there is a reply to the inquiry, it belongs to the subgroup using this spreading code. Inquiries are made using all spreading codes, and if there is no reply, it is considered that there is no other subgroup, and a new subnetwork is established using an arbitrary one (PN _{1 in} FIG. ₁ ). At this time, the order of spreading codes to be inquired may be random or may be used in a predetermined order.

The behavior of the station of the existing sub-network when there is an inquiry from the station newly entering is shown in FIG.
It suffices to follow (b). Inquiries from newly joining stations are received in packets from stations belonging to their own subnetwork. Therefore, it is not particularly necessary to monitor communication from outside the subnet, and it is only necessary to receive a packet and distribute the communication processing of the own sub-network and the communication processing from outside the sub-network according to the content of the packet. The station that responds in the sub-network may be the representative station or all stations in the sub-network.

As a response to the inquiry, a table (hereinafter referred to as a spreading code table) having information on the spreading code used and the sub-network is returned. Also,
Further, the number of the spreading code to be used by the inquiring station may be added and transmitted. The spreading code table has, for example, information about the usage status of each sub-network for the items listed below as information about each subnet.・ Spreading code used ・ Spreading code used sub-network ・ Spreading code used station name (station number) ・ Routing map After determining the spreading code used by the inquiring station, stations belonging to the existing sub-network are Distribute the fact that the number of new stations has increased to the network, and prompt the update of the spreading code table of each sub-network.

(Invention of Claim 3) <Opening of Sub-Network> FIG. 4 shows a flowchart for opening a sub-network. When a station that already belongs to one of the sub-networks opens a new sub-network, it suffices to refer to the spreading code table and select an unused spreading code to use. And
The spread code is used to test the packet transmission and reception to check whether it affects other sub-networks.
If it affects, try transmission power control, and if that doesn't work, give up opening the sub-network. When a sub-network can be opened, the fact that a new sub-network is to be opened and the spreading code to be used are announced to all stations forming the network. In particular, when newly entering a network and opening a new sub-network, it is possible to easily open a spreading code to be used by using an unused spreading code when entering the network.

(Invention of Claim 4) <Changing Subnetwork> FIG. 5 shows a flowchart for changing a subnetwork. When a station belonging to one sub-network changes to another sub-network, each station has a spreading code table, so refer to this and change to the spreading code used in the target sub-network. Be seen. Then, after confirming that the spread code can be used for communication, the subnetwork is changed and the fact is transmitted to other stations.

(Invention of Claim 5) <Removal of Sub-Network> FIG. 6 shows a flowchart in the case of resolving a sub-network. In the case of eliminating a sub-network, stations belonging to the sub-network to be eliminated are distributed to the sub-network having the best communication quality. Then, the fact is transmitted to the stations belonging to all the other sub-networks.
In addition, a part or the whole of the sub-network may be disconnected from the other sub-network due to power interruption or movement. In order to deal with this, it is possible to periodically communicate between the sub-networks so that the spreading code table always keeps track of the latest network status.

(Invention of Claim 6) In the invention of Claim 2,
The case has been described in which all stations belonging to the network have tables of spreading codes used in all sub-networks. In practice, the number of sub-networks divided by code division is limited by the type of spreading code. For example, in the case of M-sequence random numbers, there are only six types of random number sequences for 31-cycle random numbers, so the upper limit is six sub-networks. in this case,
The shortage of spreading codes is dealt with by reusing the spreading codes that are not used in neighboring sub-networks. In this case, sub-networks that use the same spreading code are allowed to use the same spreading code when they are at a distance that does not interfere with communication with each other. Then, when accessing a distant subnetwork, it may be performed via a neighboring subnetwork.

FIG. 7 shows an embodiment of claim 6. G1-G
6 is a sub-network, G1 to G4 use spreading codes PN1, PN2, PN3, PN4, and since sub-networks G5 and G6 are separated from each other, the same spreading code PN5 is used. The spreading code table held by each station may contain information about spreading codes used in all sub-networks, or may only contain information about spreading codes used in neighboring sub-networks. Is also good. When the information about the neighboring sub-networks is held, the information about the spreading code will differ depending on the sub-networks. Therefore, the method of joining the station network described in claim 2 is different. In this case, inquiries are made using the spreading codes that can be used in order, all accessible sub-networks are searched, and the connection status of neighboring sub-networks is obtained.

[0024]

As is apparent from the above description, the present invention has the following effects. Effect corresponding to claim 1: A network is divided into a number of sub-networks, lines are separated between the sub-networks by a code division method in spread spectrum communication, and CSMA is performed in the sub-networks. It is possible to configure a network of equal distribution type without requiring transmission power control and to provide a network system with good frequency utilization efficiency. Effect corresponding to claim 2: By introducing a spreading code table as a method for a new station to join the network,
It has become possible to realize an introduction method to a network by simpler transmission control. Effect corresponding to claim 3: Similar to claim 2, by using the spreading code table, transmission control can be facilitated when a sub-network is opened. Effect corresponding to claim 4: Similar to claim 2, by using the spread code table, transmission control can be facilitated when the station affiliation between sub-networks is changed. Effect corresponding to claim 5: When a sub-network is canceled, a station belonging to the sub-network to be canceled is made to belong to another sub-network with good communication quality, thereby providing a network with good line efficiency. I was able to do it. Effect corresponding to claim 6: By reusing the spreading code used in the sub-network where radio waves do not reach in the wireless network, it is possible to eliminate the shortage of the spreading code.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a conceptual configuration of the present invention.

FIG. 2 is a diagram showing an example of traffic between sub-networks according to the present invention.

FIG. 3 is a flowchart for explaining a procedure for introducing a network.

FIG. 4 is a flowchart for explaining an example of a subnetwork opening procedure.

FIG. 5 is a flowchart for explaining an example of a subnetwork changing procedure.

FIG. 6 is a flowchart for explaining an example of a subnetwork resolution procedure.

FIG. 7 is a diagram for explaining an embodiment of the invention described in claim 6;

FIG. 8 is a diagram for explaining an example of a conventional wireless LAN system.

[Explanation of symbols]

G ₁ ~G ₆ ... subnetwork, PN ₁ to PN ₅ ... spreading code, 10 ... master station, 10 ₁ to 10 ₃ ... slave station.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04L 12/28

Claims (6)

(57) [Claims] 1. In a communication system using spread spectrum communication, CSMA multiple access is performed within a sub-network, and the spread codes used between the sub-networks are made different to separate communication between the sub-networks. Communication between networks is a network method characterized in that the transmitting sub-network communicates by using the spreading code of the receiving sub-network. 2. The network system according to claim 1, wherein
When entering a new network, the spreading code already used by another sub-network is used to inquire the usage status of the spreading code to another sub-network, and after the transmission / reception test and adjustment, the available spreading code can be used. A network method characterized by receiving the assignment of. 3. The network system according to claim 1, wherein
When opening a new sub-network, the station attempting to open selects an unused spreading code with reference to the information on the usage status of the spreading code in other sub-networks,
A network method characterized by opening a sub-network with a new spreading code after transmission and reception tests and adjustments. 4. The network system according to claim 1, wherein
When a station belonging to a certain sub-network changes its affiliation to another sub-network, the spreading code is changed to the spreading code used in the sub-network to which the affiliation is changed, and after the transmission / reception test and adjustment, the sub-network's A network method characterized by making changes. 5. The network system according to claim 1, wherein
A network method characterized in that when a sub-network is to be resolved, stations that belonged to the sub-network to be resolved are subjected to transmission / reception testing and adjustment, and then to neighboring sub-networks with the best communication quality. 6. The network system according to claim 1, wherein
A network method characterized in that when a subnetwork selects a spreading code, a spreading code that is not used by a neighboring subnetwork is used.