JPH07131459A - Communication equipment for radio lan - Google Patents

Abstract

PURPOSE:To provide a communication equipment in the radio LAN where radio terminals surely communicate with each other independently of arrangement of repeating means. CONSTITUTION:A TTL code (RTTL) (=0) which is included in the radio frame from a radio terminal received by a radio machine 34 and indicates the number of reception repeating installations is checked by the program stored in a ROM 36 of a repeating installation, and one is added (RTTL=1) when its value doesn' t reach two, and the repeated frame is transmitted to another repeating installation through a junction line interface 32. After reception of the repeated frame, one is added (RTTL=2), and the radio frame is transmitted from the radio machine 34 by radio. Further, the repeating installation checks RTTL (=2) included in the radio frame received from another repeating installation; and if its value reaches two, the radio frame is abandoned not to form 80 infinite loop.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device in a wireless LAN, and more particularly to a communication device in a wireless LAN capable of reliably performing communication between wireless terminals.

[0002]

2. Description of the Related Art FIG. 6 generally shows a wireless LAN and a wired LAN.
FIG. 2 is an overall configuration diagram in the case of connecting the systems 1 and 2 to construct one communication device.

Reference numeral 1 is a wired relay line that forms a part of the construction of a wireless LAN, 2 and 3 are wired information terminals connected to the relay line 1, and 4 and 5 are equipped with a wireless device and an information terminal. And mobile terminals 6 and 7 are relay devices,
A relay device having inter-LAN connecting devices 8 and 9 configured by a MAC bridge, a buffer repeater, etc. for connecting a plurality of LANs, and wireless devices 10 and 11 for communicating with the wireless terminals 4 and 5, respectively. Is. The wireless terminals 4 and 5 are connected to the wired information terminal 2 via the relay device 6 or the relay device 7,
3 can send and receive data. The wireless devices 10 and 11 can also perform wireless communication with the wireless devices of the other relay devices 6 and 7. Reference numerals 12 and 13 are cells that indicate the range of wireless services of the relay devices 6 and 7, respectively. Each of the cells 12 and 13 is within a communicable range with the radio set in each of the relay devices 6 and 7.

FIG. 7 is a diagram showing the structure of a wireless frame used in wireless communication in the above communication device (see Japanese Patent Application No. 5-84386). Wireless frame 20
Is a wireless preheat code 21, a frame synchronization code 22, a unique identification code 23, a cell identification code 24, a control code 2
5, a size 27 and a header portion 27, and data 28. The data 28 includes a destination code, a source code, a data length code, a wired LAN data code, a frame check sequence, etc. of a wired LAN frame (IEEE802.3, Ethernet, etc.). Wireless communication is possible only when the cell identification codes 24 are the same, but they are all the same in the following description.

The operation of the communication device will be described below. Only when the wireless terminals 4 and 5 are moving within the range of the cell 12 or the cell 13, the connection with the relay devices 6 and 7 is maintained and communication becomes possible. For example, in FIG. 6, since the wireless terminal 4 is moving within the range of the cell 12, it is possible to transmit / receive data to / from the wired information terminals 2 and 3 via the relay device 6 and the relay line 1. it can. Further, since the wireless terminal 5 moves within the range of the cell 13, the wireless terminal 4 can send and receive data to and from the wireless terminal 5 via the relay device 6, the relay line 1, and the relay device 7.

Here, the cells 12 and 13 have been described as the communicable range set for each of the relay devices 6 and 7, but as the communicable range, which is not illustrated in the wireless terminals 4 and 5, too. The cell is set. Therefore, each wireless terminal 4, 5
If there are other wireless terminals 5 and 4 within the range of each cell, the wireless terminals 4 and 5 can directly send and receive data without going through the relay devices 6 and 7. Therefore, the wireless terminals 4 and 5 can transmit and receive data through the relay devices 6 and 7 even when the wireless terminals 4 and 5 are out of the range of the cell they have and cannot communicate directly.

As described above, the wireless terminals 4 and 5 can communicate as long as they are moving within the range of the cells 12 and 13. On the contrary, the wireless terminals 4 and 5 go out from the cells 12 and 13. If that happens, communication will be lost.

Therefore, it is desirable to arrange the relay devices 6 and 7 so as not to create a region outside the range of the cells 12 and 13.

FIG. 8 shows the relay devices 6 and 7 and the cells 12 and 1.
3 is a diagram showing the positional relationship of No. 3 in the above case, but FIG.
This corresponds to the case where the cells 12 and 13 are provided so as not to overlap, as in (A). In contrast to FIG. 8A, in order to efficiently set the range of the cells 12 and 13, the discontinuous region of the cells 12 and 13 is not created as in FIG. 8B,
Moreover, it is desirable to arrange the relay devices 6 and 7 so as to minimize the overlapping portion of the cells 12 and 13.

However, normally, in a room where a LAN is constructed, the environment of radio wave propagation changes due to the shape of the room, the arrangement of desks, partitions, etc., and the relay devices 6, 7 are arranged as shown in FIG. 8B. It is extremely difficult to do.

Therefore, in order to prevent the discontinuous regions of the cells 12 and 13 from being formed, the relay devices 6 and 7 are arranged with some overlapped portions as shown in FIG. 8C.

By the way, in order to provide an overlapping portion as shown in FIG. 8C and arrange the cells 12 and 13 so that other relay devices 7 and 6 do not enter the overlapping area, trial and error is performed. It is necessary to repeat the above process to some extent to relocate the relay devices 6 and 7, and it takes a lot of time to complete the construction of the LAN. Therefore, in order to prevent the discontinuous area portion from being formed faster and more reliably, the relay devices 6 and 7 must be arranged close to each other, and as a result, the relay device 6 as shown in FIG. Both 6 and 7 are cells 12,
It is quite possible that they are arranged in 13 overlapping areas.

[0013]

The relay device 6,
7 is arranged as shown in FIG. 8D, the wireless terminal 4,
Paying attention to the cell which 5 has, as shown in FIG. 9, the relay devices 6 and 7 exist within the range of the cell 14 of the wireless terminal 4,
Similarly, the relay device 6, within the range of the cell 15 of the wireless terminal 5,
The case where there is 7 easily occurs.

However, in such a state,
In the conventional communication device, the
When the bridge is used, the relay devices 6 and 7 both determine that the wireless terminals 4 and 5 are on the wireless section side and do not operate to relay the wireless frame 20. Therefore, there is a problem that the wireless terminals 4 and 5 cannot communicate.

When a buffer repeater is used for the LAN-to-LAN connecting devices 8 and 9, once the relay devices 6 and 7 start relaying the wireless frame 20, an infinite loop of the wireless frame 20 occurs between the relay devices 6 and 7. Will be formed. Therefore, even in this case, there is a problem that the wireless terminals 4 and 5 cannot normally communicate.

Furthermore, it takes a lot of time and effort to construct the wireless LAN by arranging the relay devices 6 and 7 so as to avoid the above problems.

The present invention has been made to solve the above problems, and an object thereof is to use the first layer to the second layer of the OSI reference model and to perform wireless communication regardless of the arrangement of relay means. It is an object of the present invention to provide a communication device in a wireless LAN that enables reliable communication between terminals.

[0018]

In order to achieve the above object, a communication device in a wireless LAN according to the present invention transmits a wireless frame between wireless terminals via a relay means connected to a wire relay line. In a communication device in a wireless LAN that performs wireless communication by transmitting and receiving, the wireless frame includes a TTL code indicating the number of the relay units received.

Further, in the above invention, the relay means having received the radio frame discards the radio frame including the TTL code when the TTL code reaches a predetermined value.

[0020]

The wireless L according to the present invention having the above structure
In the communication device in the AN, the relay unit, when receiving the wireless frame from the wireless terminal, discards the wireless frame including the TTL code when the TTL code reaches a predetermined value.

As described above, since an unnecessary radio frame whose TTL code has reached a predetermined value is not sent to another relay means via a relay line, it is normal and reliable without forming an infinite loop. Wireless communication can be performed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. The same elements as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a diagram showing the configuration of a relay device in this embodiment. 30 is a CPU, 32 is a relay line interface, 34 is a wireless device, 36 is a ROM, 38 is a RAM
Is.

FIG. 2 is a diagram showing a wireless frame used for wireless communication in this embodiment. Wireless frame 4
0 is the TTL for the wireless LAN indicating the number of received relay devices in addition to the header part 27 and the data 28 shown in FIG.
It has a code (hereinafter referred to as RTTL) 42.

FIG. 3 is a diagram showing a relay frame 44 used for communication via a relay line in the present embodiment, in which header information dedicated to relay is added to the header portion 27 of the wireless frame 40 and relay is performed. The dedicated header portion 46 is formed.

A feature of this embodiment is that the RTTL 42 is added to each of the frames 40 and 44 used for communication, and the relay device according to the value of the RTTL 42.
This is to discard the wireless frame 40 including L42.
As a result, only the necessary one of the wireless frames 40 to be processed by the relay device can be reliably transmitted and received.

FIG. 4 is a flowchart showing a process when the relay device receives the wireless frame 40 by radio, and FIG. 5 is a flowchart showing a process when the relay device receives the relay frame 44 by wire. A program that executes each of the above processes is stored in the ROM 36.

Hereinafter, as shown in FIG. 9, the relay device 6,
Operation of the communication device of the present embodiment when both 7 are arranged in the overlapping range of the cells 14 and 15 of the wireless terminals 4 and 5 and the wireless frame 40 is transmitted from the wireless terminal 4 to the wireless terminal 5. Will be described with reference to FIGS. 4 and 5. Note that the LAN-to-LAN connecting device in this embodiment uses a buffer repeater.

The wireless terminal 4 sets the RTTL 42 to 0 and transmits the wireless frame 40. Since each of the relay devices 6 and 7 is within the range of the cell 14, each of the wireless devices 34 and
Thus, the wireless frame 40 from the wireless terminal 4 is received.

Upon receiving the radio frame 40 (step 101), each of the relay devices 6 and 7 checks the RTTL 42 in the radio frame 40 (step 102). Where R
If the TTL 42 has a value of 2 or more, which is a predetermined value, the received wireless frame 40 is determined to be invalid and is discarded (step 103). Since the RTTL 42 in this case is 0, it is not discarded. Next, the RTTL 42 is incremented by 1 (step 104) and the relay frame 44 is created (step 10).
5) Sending to the trunk line 1 through the trunk line interface 32 (step 106).

Each of the relay devices 6 and 7 receives the relay frame 44 sent by the other (step 20).
1) and increase RTTL42 by 1 (step 202),
The wireless frame 40 is created (step 203). In this case, the RTTL 42 when received by each of the relay devices 6 and 7
Since R is 1, the RTL 42 becomes 2 as a result of the increase. Then, each of the relay devices 6 and 7 wirelessly transmits the wireless frame 40 whose RTTL 42 is 2 to the wireless terminal 5 (step 204).

In this way, the wireless terminal 5 can receive the wireless frame 40 from the wireless terminal 4.

By the way, the wireless terminal 5 receives the same wireless frame 40 from each of the relay devices 6 and 7 in a duplicated manner as described above, but the upper layer of the wireless terminal 5 normally performs processing such as discarding. There is no problem because it is done. In addition, the wireless terminal 4
Although he himself will receive the wireless frame 40 wirelessly,
In this case as well, processing such as discarding is normally performed in the upper layer of the wireless terminal 4.

Further, each relay device 6, 7 also receives the radio frame 40 sent from the other relay device 7, 6. Here, the processing shown in FIG. 4, which is a feature of this embodiment, is executed again. As described above, when each of the relay devices 6 and 7 receives the radio frame 40 (step 101), it checks the RTTL 42 in the radio frame 40 (step 102). Since the RTTL 42 in the received radio frame 40 is 2 as described above, the radio frame 40 is discarded (step 1).
03).

As described above, since the wireless frame 40 including the RTTL 42 that has reached the predetermined value of 2 is discarded, wireless communication can be normally performed without causing an infinite loop.

In the above embodiment, RTTL4
2 is set to 0 when it is emitted from the wireless terminals 4 and 5, and is added in the relay devices 6 and 7, and the wireless frame 40 is discarded when it reaches 2, but it is not limited to this. Any method of using the RTTL 42 is conceivable, such as subtraction, subtraction, or expressing the RTTL 42 with a bit or a flag.

[0037]

As described above, the TTL code for the wireless LAN is provided in the wireless frame for wireless communication, and this TTL code is used.
Since the validity or invalidity of the wireless frame is determined based on the code value and discarded, it is possible to reliably perform communication between wireless terminals without forming an infinite loop or the like.

Therefore, since it is not necessary to consider the overlapping of cells due to the arrangement of the relay means in the wireless LAN, it is possible to construct the wireless LAN faster and more reliably.

In addition, the first layer and the second layer of the OSI reference model
Since the above problem can be solved by changing only the layers,
It is possible to easily realize reliable wireless communication.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a relay device in an embodiment of a communication device according to the present invention.

FIG. 2 is a diagram showing a wireless frame used for wireless communication in the present embodiment.

FIG. 3 is a diagram showing a relay frame used for communication via a relay line in the present embodiment.

FIG. 4 is a flowchart showing processing when a relay device wirelessly receives a wireless frame in the present embodiment.

FIG. 5 is a flowchart showing processing when a relay device receives a relay frame by wire in the present embodiment.

FIG. 6 is an overall configuration diagram showing a communication device in a general wireless LAN.

FIG. 7 is a diagram showing a wireless frame used in wireless communication in a communication device in a general wireless LAN.

FIG. 8 is a diagram showing a positional relationship between each relay device and a cell.

FIG. 9 is a diagram showing a positional relationship between a relay device and a cell included in a wireless terminal.

[Explanation of symbols]

 1 relay line 2, 3 wired information terminal 4, 5 wireless terminal 6, 7 relay device 8, 9 LAN connection device 10, 11 wireless device 12, 13, 14, 15 cell 20, 40 wireless frame 30 CPU 32 relay line interface 34 Radio Equipment 36 ROM 38 RAM 42 RTTL 44 Relay Frame

Claims (2)

[Claims] 1. A communication device in a wireless LAN that performs wireless communication by transmitting and receiving a wireless frame between wireless terminals via a relay unit connected to a wired relay line, wherein the wireless frame receives the received relay. A communication device in a wireless LAN, comprising a TTL code indicating the number of means. 2. The communication device in the wireless LAN according to claim 1, wherein the relay unit that receives the wireless frame is the TT.
A communication device in a wireless LAN, wherein the wireless frame including the TTL code is discarded when the L code reaches a predetermined value.