Radio transmission system

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a wireless transmission system in a wireless local area network (LAN) using a wired network.

【0002】

[Conventional technology]

FIG. 3 is an overall configuration diagram of a wireless LAN wireless transmission system using a wired network according to a conventional example. Conventionally, an access point AP that converts between wired communication and wireless communication is arranged so that cells in its communication area overlap each other, and as a wireless transmission method with mobile station I, a spread spectrum communication method is used. When is adopted, a different spreading sequence is selected in order to prevent radio wave interference with the cell which is the communication area of the adjacent access point AP.

【0003】

Spread spectrum communication methods can be broadly divided into two types: frequency hopping method (SS-FH) and direct spread light method (SS-DS). In the frequency hopping method, the frequencies used are sequentially changed over time to make the frequencies spread, and the access point AP and the mobile station I in the cell configured by the access point AP It is necessary to change the frequency in synchronization. Therefore, the access point AP transmits a beacon signal, which is a signal for synchronization, to the mobile station I existing in its own cell. This beacon signal includes hopping pattern information indicating a frequency change pattern used by itself and a hop time indicating the timing of frequency change, and even if it is a new mobile station I, it may be a new mobile station I. By receiving this beacon signal, wireless communication can be performed.

【0004】

The direct spreading method spreads frequency (spectrum) by superimposing a faster spreading code on the transmitted data, and the receiving side receives the data by removing it in synchronization with the spreading code. Is to do. In this method, the same spreading code is generally used in the same cell, and wireless communication is performed in synchronization with the spreading code, so that a beacon signal as in the frequency hopping method is not required. However, it is necessary to inform the new mobile station I of the diffusion code used in the cell, and even when there is no information communication, radio waves are emitted at regular intervals.

【0005】

Unlike the frequency hopping method, the direct spreading method is a method in which communication is separated by the difference in spreading code while using the same frequency. Therefore, as shown in FIG. 4, the peak of the cross-correlation of the spreading code used is used. It is appropriate to select the spreading code with the smallest value.

【0006】

[Problems to be Solved by the Invention]

However, in the wireless transmission system as described above, the access point AP stores a plurality of diffusion codes, and the installer determines the diffusion code used by the surrounding access point APs when the access point AP is installed. However, it took a lot of know-how and time to install it because the optimum one was set with a switch or the like.

【0007】

In addition, some access point APs can be monitored and set by remote control from a network management device connected to the wired network CN. In this case as well, the location of the access point AP can be determined. In consideration of this, setting the diffusion code in sequence still required experience and know-how.

【0008】

Furthermore, the access point APs operate at independent timings, and even if the time is measured using an accurate signal source, the individual timings are random during long-term operation. When selecting the diffusion code, it was necessary to consider the entire cycle of the diffusion code, and the options were limited.

【0009】

Further, the mobile station I has a problem that the synchronization work is required again because the timing of each cell is different when moving between cells.

【0010】

The present invention has been made in view of the above points, and an object of the present invention is to provide a wireless transmission system capable of automatically setting a spreading code of an access point in a direct spreading method. It is in.

【0011】

[Means for solving problems]

The invention according to claim 1 is a wired transmission / reception unit that transmits / receives a wired communication signal, a wireless transmission / reception unit that transmits / receives a wireless communication signal between a mobile station, and a diffusion for spreading the wireless communication signal. A plurality of access points having a storage unit for storing a code and a control unit for switching between wired communication and wireless communication are connected to a wired network, and the access point and its own communication area are connected. In a wireless transmission system in which wireless communication is performed with a mobile station existing in a certain cell by using a direct spreading method, a plurality of types of spreading codes are stored in the storage unit, and the access point is used for others. A signal that detects a signal receiving unit that receives a signal transmitted by the access point and a spreading code used in the signal received by the signal receiving unit, and selects a spreading code different from the spreading code from the storage unit. It is characterized in that a processing unit is added and a spreading code selected by the signal processing unit is used to spread a signal of its own wireless communication.

【0012】

According to the second aspect of the present invention, in the wireless transmission system according to the first aspect, the signal processing unit sets a priority based on the reception strength of the signal received by the signal receiving unit, and at least a high priority signal. It is characterized in that a diffusion code different from the diffusion code used in is selected.

【0013】

The invention according to claim 3 is the wireless transmission system according to claim 1 or 2, wherein when the signal error in wireless communication becomes a certain value or more, the signal processing unit determines the spreading code of itself. It is characterized by making settings.

【0014】

The invention according to claim 4 is the wireless transmission system according to claims 1 to 3, wherein the signal processing unit synchronizes with signals of other access points, and the wireless transmission / reception unit is the signal processing unit. It is characterized in that a signal is transmitted based on the synchronization taken in.

【0015】

The invention according to claim 5 is the wireless transmission system according to claim 4, wherein the wireless transmission / reception unit transmits an information signal including information of the diffusion code when wireless communication with the mobile station is not performed. The signal receiving unit receives the information signal, and the signal receiving unit synchronizes with the information signal.

【0016】

The invention according to claim 6 is for managing and changing the spread code of the access point connected to the wired network in the wired network in the wireless transmission system according to claims 1 to 5. A network management device is added, and the access point is characterized in that its own spreading code is transmitted from the wired transmission / reception unit to the network management device.

【0017】

[Action]

According to the first aspect of the present invention, a plurality of types of spreading codes for spreading a signal of wireless communication are stored in a storage unit of an access point that converts wireless communication and wired communication, and another access is performed in the signal receiving unit. The signal received by the point is received, the signal processing unit detects the diffusion code used in the signal received by the signal reception unit, and a diffusion code different from the detected diffusion code is selected from the storage unit. In the wireless transmission / reception unit, its own signal is diffused by the diffusion code selected by the signal processing unit, and a cell having the least interference can be configured in the cell which is the communication area of the access point. it can.

【0018】

According to the second aspect of the present invention, in the wireless transmission system according to the first aspect, the signal processing unit sets a priority based on the reception strength of the signal received by the signal receiving unit, and at least a high priority signal. By selecting a diffusion code different from the diffusion code used in the above, it is possible to construct a cell having the least interference.

【0019】

The invention according to claim 3 is the wireless transmission system according to claim 1 or 2, wherein when the signal error in wireless communication becomes a certain value or more, the signal processing unit uses the spreading code of itself. The settings are made so that signal errors in wireless communication can be reduced.

【0020】

The invention according to claim 4 is the wireless transmission system according to claims 1 to 3, wherein the signal processing unit synchronizes with signals of other access points, and the wireless transmission / reception unit is the signal processing unit. The signal is transmitted based on the synchronization taken in the above, and the peak value of the cross-correlation of the diffusion code can be reduced.

【0021】

The invention according to claim 5 is the wireless transmission system according to claim 4, wherein the wireless transmission / reception unit transmits an information signal including information of the diffusion code when wireless communication with the mobile station is not performed. The signal receiving unit receives the information signal, and the signal processing unit resynchronizes with the information signal received by the signal receiving unit, and signals from other access points. When synchronizing with, the influence of the clock frequency used by the access point can be ignored.

【0022】

The invention according to claim 6 is for managing and changing the spread code of the access point connected to the wired network in the wired network in the wireless transmission system according to claims 1 to 5. A network management device is added so that the access point transmits its own spreading code from the wired transmission / reception unit to the network management device, and the network administrator can easily use the wired network. The spread code of the access point can be changed.

【0023】

[Example]

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an overall configuration of an access point AP when the direct diffusion method according to an embodiment of the present invention is used. Since the overall configuration of the wireless transmission system is the same as the configuration shown in FIG. 3 as a conventional example, the description thereof will be omitted here. The access point AP includes a wireless transmission / reception unit 1, a wired transmission / reception unit 2, a control unit 3, a storage unit 4, a signal reception unit 5, and a signal processing unit 6. The wireless transmission / reception unit 1 spreads and transmits a signal of wireless communication to mobile station I using a spreading code, receives a signal from mobile station I and removes the spreading code, and further uses a spreading code. An information signal for notifying is transmitted periodically. The wired transmission / reception unit 2 transmits / receives a signal via the wired network CN. The control unit 3 controls so that the signal received by the wireless transmission / reception unit 1 is transmitted from the wired transmission / reception unit 2 and the signal received by the wired transmission / reception unit 2 is transmitted from the wireless transmission / reception unit 1. The storage unit 4 stores a plurality of types of spreading codes for spreading the signal of wireless communication. The signal receiving unit 5 receives a signal and an information signal with and from the mobile station I transmitted by another access point. The signal processing unit 6 detects the diffusion code used in the signal received by the signal reception unit 5, selects a diffusion code different from the detected diffusion code from the storage unit 4, and selects the diffusion code different from the detected diffusion code from the storage unit 4 to the wireless transmission / reception unit 1. It outputs a signal indicating the selected diffusion code.

【0024】

Hereinafter, the operation of this embodiment will be described. The access point AP receives the signal transmitted by another access point AP in the signal receiving unit 5. The signal processing unit 6 detects the spreading code used in the received signal by sequentially multiplying the signal received by the signal receiving unit 5 by the spreading code stored in the storage unit 4. , A signal that selects the diffusion code having the smallest peak value of mutual correlation with the detected diffusion code from the diffusion codes stored in the storage unit 4 and informs the wireless transmission / reception unit 1 of the selected diffusion code. Is output.

【0025】

The wireless transmission / reception unit 1 diffuses and transmits a radio communication signal to the mobile station I existing in its own cell by using the diffusion code included in the signal input from the signal processing unit 6, and also newly transmits the signal. It periodically transmits an information signal to inform the mobile station I that has joined the cell in its own cell to inform the spreading code that it is using.

【0026】

Therefore, in this embodiment, the signal of the access point AP that exists close to the location is received, and the peak value of the cross-correlation is minimized based on the diffusion code used in the received signal. Since the self-diffusion code is set, the cell with the least interference can be configured in the mobile station I.

【0027】

A network management device for managing and changing the spread code of the access point AP is connected to the wired network CN, and each access point transfers the spread code used by itself from the wired transmission / reception unit 2 to the wired network. By transmitting to the network management device via the CN, the network administrator can easily know the spreading code used by the access point AP existing in the network by the network management device, and also. , The spread code used by the access point AP can be easily changed by using the wired network from the network management device.

【0028】

Further, in an actual situation, the received signal is rarely one, and usually, signals from a plurality of adjacent access point APs are received. FIG. 2 is a flowchart showing a flow of processing for setting the diffusion code of the access point AP according to this embodiment. Since the diffusion code in the case of the direct diffusion method is regularly repeated at a fixed cycle, the reception state is first set with a specific diffusion code, and the observation time is set. Here, the observation time may be set to the time of one cycle of the diffusion code. Then, the diffusion code and the reception intensity used for all the signals received during the observation time are stored.

【0029】

When signals are received from a plurality of access point APs, the one with the stronger reception strength generally has the higher degree of interference, so weighting is performed according to the reception strength. As an example of this weighting, in this embodiment, the peak value of the cross-correlation between the candidate diffusion code and the diffusion code used by another access point AP is multiplied by the reception intensity for one cycle of the hopping pattern. The sum is used as an index. Then, by selecting the diffusion code having the smallest exponent as the best one, it is possible to construct the cell having the least interference in the mobile station I.

【0030】

Further, in the above two embodiments, when the signal is transmitted from the wireless transmission / reception unit 1, if the signal is synchronized with the signal from another access point AP, the diffusion code having the smallest cross-correlation peak value is obtained. It can be selected, and it can be set relatively easily even in the setting of the diffusion code.

【0031】

In addition, each access point can determine in the signal processing unit 6 a time zone in which communication in the cell managed by itself has a margin, and information on the diffusion code transmitted in this time zone. Resynchronization can be easily performed by using an information signal containing only the information signal, and the influence of the clock frequency used by each access point AP can be ignored.

【0032】

Further, in all the above-described embodiments, if an error in the wireless communication signal is detected in each access point AP and the diffusion code is set again when the error exceeds a certain value, the spread code can be set again. In mobile station I, cells with less interference can be configured.

【0033】

[Effect of the invention]

According to the first aspect of the present invention, a plurality of types of spreading codes for spreading a wireless communication signal are stored in a storage unit of an access point that converts wireless communication and wired communication, and another access is performed in the signal receiving unit. The signal received by the point is received, the signal processing unit detects the diffusion code used in the signal received by the signal reception unit, selects a diffusion code different from the detected diffusion code from the storage unit, and wirelessly operates. Since the transmission / reception unit diffuses its own signal by the diffusion code selected by the signal processing unit, it is possible to construct a cell having the least interference in the cell which is the communication area of the access point, and directly. In the spreading method, it has been possible to provide a wireless transmission system capable of automatically setting the spreading code of an access point.

【0034】

According to the second aspect of the present invention, in the wireless transmission system according to the first aspect, the signal processing unit sets a priority based on the reception strength of the signal received by the signal receiving unit, and uses the signal at least for a high priority signal. Since the diffusion code different from the diffusion code used is selected, the cell with the least interference can be constructed.

【0035】

According to the third aspect of the present invention, in the wireless transmission system according to the first or second aspect, the signal processing unit sets its own diffusion code when the signal error in the wireless communication becomes a certain value or more. Since this is done, it is possible to reduce signal errors in wireless communication and improve reliability.

【0036】

According to the fourth aspect of the present invention, in the wireless transmission system according to the first to third aspects, the signal processing unit synchronizes with the signals of other access points, and the wireless transmitting / receiving unit synchronizes with the signal processing unit. Since the signal is transmitted based on the above, the diffusion code having the smallest peak value of the cross-correlation can be set, and the diffusion code can be selected relatively easily.

【0037】

The invention according to claim 5 is such that in the wireless transmission system according to claim 4, the wireless transmitter / receiver transmits an information signal including information of a spreading code when wireless communication with a mobile station is not performed. The signal receiving unit receives the information signal, and the signal processing unit resynchronizes with the information signal received by the signal receiving unit. Therefore, when synchronizing with the signal of another access point, , The effect of the clock frequency used by the access point can be ignored.

【0038】

The invention according to claim 6 is a network management device for managing and changing the spread code of an access point connected to the wired network in the wired network in the wireless transmission system according to claims 1 to 5. Is added, and the access point transmits its own spreading code from the wired transmission / reception unit to the network management device. Therefore, the network administrator can easily use the wired network to transmit the spreading code of the access point. Can be changed.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram which shows the whole structure of the access point when the direct diffusion method which concerns on one Example of this invention is used.

[Figure 2]

It is a flowchart which shows the flow of the process of setting the diffusion code of the access point which concerns on this Example.

[Fig. 3]

It is an overall block diagram which shows the wireless transmission system of a wireless LAN using a wired network.

[Fig. 4]

It is a correlation characteristic diagram which shows an example of autocorrelation and cross-correlation in a direct diffusion method.

[Explanation of symbols]

AP access point CN Wired Network I mobile station 1 Wireless transmitter / receiver 2 Wired transmitter / receiver 3 Control unit 4 Memory 5 Signal receiver 6 Signal processing unit