JP3042482B2 - Transmission timing adjustment method in wireless communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a subscriber radio system, and more particularly, to a transmission timing adjustment system inside a subscriber home device.

[0002]

2. Description of the Related Art FIG. 2 shows a subscriber home device (hereinafter referred to as "WS").
U) is shown in a block diagram. In FIG. 2, reference numeral 20 denotes a WSU, 21
Is a transmission timing setting memory in the WSU, 22 and 23 are base stations, 24 is the distance between the base station 22 and the WSU 20, 25 is
Indicates the distance between the base station 23 and the WSU 20.

[0003] The base stations 22 and 23 open a reception window at a specific timing and receive a transmission signal from the WSU 20 irrespective of the distances 23 and 24 to the WSU 20. The timings at which the base stations 22 and 23 receive the transmission signal are different.

[0004] For this reason, in the WSU 20, it is necessary to presuppose a base station with which communication is to be performed, and perform transmission at a shifted timing so that a transmission signal from the WSU 20 enters a reception window of the base station in accordance with a distance from the base station. There is.

When the WSU 20 is installed at the subscriber's house, the WS
Assuming communication with the base station 22 closest to the U20, the transmission timing setting memory 21 of the WSU 20 stores
A transmission timing adjustment value N according to the distance 23 is set.
When performing communication with the base station, the WSU performs communication with the base station 22 by shifting the transmission timing by a value N.

[0006] When the WSU 20 attempts to communicate with the base station 22, the base station 22 notifies the WSU 20 that communication is impossible due to some failure such as a communication channel being buried or broken. May come. At this time, the WSU 20 performs communication with another base station whose radio wave reaches the WSU 20. Since the WSU 20 has been denied communication from the base station 22, when attempting to communicate with the base station 23, the distance 24 between the WSU 20 and the base station 23 is set and stored in advance in the transmission timing setting memory 21 of the WSU 20. When communication is possible with a certain transmission timing adjustment value N, the WSU 20 can perform communication with the base station 23.

However, the distance 24 between the WSU 20 and the base station 23 is determined in advance by the transmission timing setting memory 2 of the WSU 20.
When communication is impossible with the transmission timing adjustment value N set to 1, the base station 23 cannot receive the transmission signal transmitted from the WSU 20 to the base station 23, and the base station 23 , No response is received, and the WSU 20 cannot communicate with the base station 23.

Accordingly, the WSU 20 can only communicate with a base station within a communicable distance with the transmission timing adjustment value N stored and held in the transmission timing memory 21.

As a conventional transmission timing adjusting method for solving this problem, for example, Japanese Patent Laid-Open No. 3-12853 is disclosed.
No. 2) discloses a time-division multiple access wireless system for performing wireless communication using a burst signal between one master station and a plurality of slave stations. A timing adjustment signal is transmitted in the slot, and the master station detects the phase shift amounts of the received phase of the timing adjustment signal with respect to the normal reception phase of 0 ° and 180 °, respectively, and determines the smaller one of the phase shift amounts. As the detection amount, the information indicating the phase shift detection amount is notified to the slave station that has transmitted the timing adjustment signal, and the slave station sends the timing adjustment signal according to the information indicating the phase shift detection amount notified from the master station. The transmission phase of the own station is adjusted to reduce the phase shift detection amount to zero, and then a timing adjustment signal is transmitted from the slave station to the master station at the transmission timing after the phase shift adjustment, and the master station adjusts the timing. A bit shift amount of the signal reception timing with respect to the normal reception timing is detected in units of 1/2 bit, and information representing the bit shift detection amount is notified to the slave station that has transmitted the timing adjustment signal in the previous period. There has been proposed a transmission timing adjustment method for adjusting the transmission timing of its own station so as to reduce the bit shift amount to zero in accordance with the information indicating the bit shift amount.

Referring to FIG. 2, the conventional transmission timing adjustment method will be described. The base stations 22 and 23 detect a shift in transmission timing of a transmission signal from the WSU 20, and
The shift of the transmission timing from the SU 20 is
3 notifies the WSU 20. In the WSU 20, the base station 2
Referring to the notification of the transmission timing shift from 2, 23,
Adjust the transmission timing correctly.

However, in the above-mentioned conventional transmission timing adjustment method, a device for adjusting the transmission timing is required on both sides of the WSU 20 and the base stations 22 and 23 in order to correctly adjust the shift of the transmission timing. Size and price increase.

[0012]

As described above, the conventional system has the following problems.

The first problem is that the WSU 20 can communicate only with a base station within a communicable distance with the transmission timing value N stored in the transmission timing adjustment memory 21 in advance.

The reason is that the transmission timing adjustment value written in the transmission timing adjustment memory 21 of the WSU 20 is fixed and cannot be changed to the transmission timing adjustment value necessary for communication with a base station having a different distance. is there.

As a second problem, the above-mentioned Japanese Patent Laid-Open Publication No.
In the transmission timing adjustment method described in JP-A-8532, the size and cost of the base station are increased.

The reason is that the base station requires an apparatus for adjusting the transmission timing.

Therefore, the present invention has been made in view of the above-mentioned problems, and has as its object to make a transmission timing adjustment value set in a WSU used in a WLL system variable and to enable a base station with which the WSU can communicate. It is an object of the present invention to provide a transmission timing adjustment method in a wireless communication system, which makes it possible to expand the area of the transmission timing.

[0018]

SUMMARY OF THE INVENTION In order to achieve the above object, a transmission timing adjusting method in a wireless communication system according to the present invention is directed to a subscriber wireless system in which a subscriber faces a base station and transmits data by wireless signals. In a wireless communication system such as a wireless local loop (also referred to as "WLL"), a subscriber home device ("WSU") used at a subscriber home is transmitted to a desired base station from the subscriber home device side. Means for attempting to establish a communication connection with the base station by changing a transmission timing adjustment value in a predetermined time unit when making a communication connection with a station, and a base station different from the base station corresponding to a preset transmission timing value. It is characterized by being able to communicate with stations.

In the present invention, there is provided means for determining that a change in a transmission timing set value is necessary for communication with the base station when there is no response from the base station which attempted communication. If there is no response from the base station that attempted communication, change the transmission timing set value, try communication with the base station with the changed transmission timing value, and obtain a response from the base station. The transmission timing setting value is repeatedly changed.

[Summary of the Invention] In the present invention, when a transmission timing value change determination means in a WSU attempts to communicate with a base station having radio waves reaching the WSU, if there is a response from the base station, Judge that the transmission timing setting is correct and do not change the transmission timing setting value. On the other hand, when there is no response from the base station, it is determined that the transmission timing setting value needs to be changed to perform communication with the base station, and the transmission timing setting value set in the transmission timing setting memory is changed. change. The transmission timing set value is repeatedly changed until a response from the base station is obtained.
As a result, the WSU can communicate with a base station that requires a transmission timing setting value different from the value set in the WSU in advance.

[0021]

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

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In FIG. 1, 10 is WSU, 1
1 is a transmission timing setting memory in the WSU, 12 is a transmission timing value change determination circuit, 13 and 14 are base stations, 1
5 is the distance between the base station 13 and the WSU 10, and 16 is the base station 1.
4 and the distance between WSU 10 are shown.

When the WSU 10 is installed at the subscriber's house, the WSU 10 assumes communication with the base station 13 and
The transmission timing adjustment value N required for communication between 0 and the base station 13 at the distance 15 is written in the transmission timing setting memory 11 of the WSU 10.

When attempting to communicate with the base station 13, the WSU 10 performs communication with the base station 13 by shifting the transmission timing adjustment value N stored and held in the transmission timing setting memory 11.

The base station 13 adjusts the timing of the transmission signal from the WSU 10 to an appropriate value.
0 can be received, and the WSU 10 and the base station 13 can communicate with each other.

In this case, the transmission timing value change determination circuit 12 does nothing to the transmission timing setting memory 12 because the communication between the WSU 10 and the base station 13 has been performed normally.

After the communication between the WSU 10 and the base station 13 becomes possible, the base station 13 may notify the WSU 10 of refusal of communication with the WSU 10 for some reason such as a failure. At this time, when the WSU 10 receives the rejection of communication with the base station 13, it tries to communicate with another base station.
Hereinafter, a description will be given assuming that the WSU 10 attempts to communicate with the base station 14.

The WSU 10 attempts communication with the base station 14 by shifting the transmission timing by the adjustment value N stored in the transmission timing value setting memory 11 in advance. WSU10
When communication is possible with the transmission timing adjustment value N at a distance 16 between the base station 14 and the base station 14, the base station 14 can receive a transmission signal from the WSU 10, and the WSU 10 and the base station 14 can perform communication. In this case, the WSU 10 is
Since the communication is normally performed with the transmission timing value change determination circuit 12, the transmission timing value change determination circuit 12 does nothing.

However, if the distance 16 between the WSU 10 and the base station 14 cannot communicate with the transmission timing adjustment value N, the base station 14 cannot receive the transmission signal from the WSU 10 and, therefore, Does not respond to WSU10.

The transmission timing value change determination circuit 12
If there is no response from the base station 14, it is determined that the transmission timing adjustment value needs to be changed, and the transmission timing setting memory 1
The transmission timing value written in 1 is changed.

After the WSU 10 and the transmission timing value are changed, communication with the base station 14 is attempted again.

When there is a response from the base station 14 to the WSU 10, it is determined that the transmission timing adjustment value is correct, and the communication is continued as it is. On the other hand, if there is no response from the base station 14, the procedure for changing the transmission timing adjustment value again is repeated.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to explain the above-mentioned embodiment in more detail, an embodiment of the present invention will be described with reference to FIG. The configuration shown in the block diagram of FIG. 1 is the same as that described in the above embodiment.

When the WSU 10 is installed at the subscriber's house, communication with the base station 13 is assumed. WSU1
The distance 15 between 0 and the base station 13 is 1000 meters. Then, it is assumed that when the distance between the WSU and the base station is 1000 meters, the transmission timing needs to be earlier by 2 μsec than when the distance between the WSU and the base station is 0 meters.

Transmission timing setting memory 1 of WSU 10
1 is set to a numerical value of 2 μs. When attempting to communicate with the base station 13, the WSU 10 transmits a transmission signal to the base station 13 earlier by the transmission timing adjustment value 2 μs set and held in the transmission timing setting memory 21.

The base station 13 adjusts the timing of the transmission signal from the WSU 10 for a proper time,
A transmission signal from U10 can be received, and WSU1
0 and the base station 13 can perform communication. The determination circuit 12 for changing the transmission timing value includes the WSU 10 and the base station 13
Since the communication with has been performed normally, nothing is performed on the transmission timing setting memory 12.

After the communication between the WSU 10 and the base station 13 becomes possible, the base station 13 may notify the WSU 10 of refusal of communication with the WSU 10 for some reason. At that time, when the WSU 10 receives the rejection of communication with the base station 13, it tries to communicate with another base station. WSU 10 attempts to communicate with base station 14. The WSU 10 attempts to communicate with the base station 14 by transmitting a transmission signal by advancing the transmission timing by 2 μs previously written in the transmission timing value setting memory 11.

The distance 16 between the WSU 10 and the base station 14 is 1
It is assumed that the transmission timing needs to be 2 μsec earlier than when the distance between the WSU and the base station is 0 meters. Since the transmission timing setting memory 11 of the WSU 10 has set a numerical value of 2 μs, the WSU 10 sets the transmission timing adjustment value held in the transmission timing setting memory 11 when attempting to communicate with the base station 14. Base station 1 early 2 μs
4 is transmitted.

Since the base station 14 adjusts the timing of the transmission signal from the WSU 10 for a proper time, the base station 14
A transmission signal from U10 can be received, and WSU1
0 and the base station 14 can communicate.

Next, the distance 1 between the WSU 10 and the base station 14
When 6 is 2000 meters, it is assumed that the transmission timing needs to be advanced by 4 μs as compared with the case where the distance between the WSU and the base station is 0 meters.

In this case, since a value of 2 μs is set in the transmission timing setting memory 11 of the WSU 10, the WSU 10 is stored in the transmission timing setting memory when trying to communicate with the base station 14. The transmission signal is transmitted to the base station 14 earlier by the transmission timing adjustment value 2 μsec. Since the transmission signal from the WSU 10 is not correctly adjusted in timing, the base station 14
10 cannot receive the transmission signal from the base station 1
No. 4 makes WSU 10 and does not respond.

The transmission timing value change determination circuit 12
If there is no response from the base station 14, it is determined that the transmission timing adjustment value needs to be changed, and the transmission timing setting memory 1
Increase the transmission timing value written in 1 by 1 μs,
Change that value to 3 μs.

After the transmission timing value is changed, WSU 10 transmits the transmission signal to base station 14 earlier by the current transmission timing adjustment value 3 μs stored in the transmission timing setting memory. Since the base station 14 has not correctly adjusted the timing of the transmission signal from the WSU 10,
The transmission signal from WSU 10 cannot be received, and base station 14 does not respond with WSU 10.

The transmission timing value change determination circuit 12
If there is no response from the base station 14, it is determined that the transmission timing adjustment value needs to be changed, and the current transmission timing value stored in the transmission timing setting memory 11 is increased by 1 μs, and the value is increased by 4 μm. Change to seconds.

After the transmission timing value is changed, the WSU 10 sets the base station 14 ahead of the transmission timing adjustment value 4 μs set in the transmission timing setting memory 11 earlier.
Send the transmission signal to.

Since the base station 14 adjusts the timing of the transmission signal from the WSU 10 for a proper time, the base station 14
A transmission signal from U10 can be received, and WSU1
0 and the base station 14 can communicate.

According to the above procedure, the WSU 10 repeats the change of the transmission timing value until it can receive the response from the base station.

[0048]

As described above, according to the present invention, the following effects can be obtained.

A first advantage of the present invention is that the transmission timing adjustment value set in the WSU used in the WLL system can be variably set, so that the area of the base station with which the WSU can communicate can be expanded. That's what it means.

The reason is that, in the present invention, the transmission timing value change determination circuit in the WSU determines the transmission timing value in order to perform communication with the base station when there is no response from the base station. This is because it is determined that a change is necessary, and the transmission timing value stored in the transmission timing setting memory is changed, thereby enabling communication with the base station.

A second effect of the present invention is that the WSU enables communication with a base station requiring a transmission timing value other than the transmission timing value preset in the transmission timing setting memory. .

The reason is that in the present invention, the first
The reason is that the transmission timing value change determination circuit changes the transmission timing value preset in the transmission timing value setting memory, similarly to the reason for the effect of (1).

A third effect of the present invention is to avoid an increase in size and cost in the base station.

The reason is that, in the present invention, the setting of the transmission timing adjustment is all performed in the WSU, and it is not necessary to provide a device for adjusting the transmission timing on the base station side.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram for explaining a conventional method.

[Explanation of symbols]

 Reference Signs List 10 WSU 11 Transmission timing set value memory in WSU 12 Circuit for determining change of transmission timing value in WSU 13 Base station 14 Base station 15 Distance between WSU and base station 13 16 Distance between WSU and base station 14 20 WSU 21 Transmission timing setting value memory in WSU 22 Base station 23 Base station 24 Distance between WSU and base station 22 25 Distance between WSU and base station 23

Claims (4)

(57) [Claims] A wireless communication system, such as a wireless local loop (also referred to as "WLL"), which is a subscriber wireless system in which a subscriber transmits data by wireless signals in opposition to a base station. When the subscriber home device to be used makes a communication connection with a desired base station from the subscriber home device side, the transmission timing adjustment value is sequentially varied in a predetermined time unit, so that the connection with the base station can be changed. A transmission timing adjustment method in a wireless communication system, comprising means for attempting communication connection, and enabling communication with a base station different from a base station corresponding to a preset transmission timing value. Means for determining that a change in a transmission timing set value is necessary for communication with the base station when there is no response from the base station which attempted communication; If there is no response from the base station, the current transmission timing setting value is changed, communication with the base station is retried with the changed transmission timing value, and a response from the base station can be obtained. 2. The transmission timing adjustment method in a wireless communication system according to claim 1, wherein the change of the transmission timing set value is repeated according to the above procedure. 3. A wireless communication system, such as a wireless local loop (hereinafter, referred to as "WLL"), which is a subscriber wireless system in which a subscriber transmits data by wireless signals in opposition to a base station. A storage unit for setting a transmission timing value on a subscriber home device (hereinafter, referred to as "WSU") used, and communication with the base station when there is no response from the base station that attempted communication. Determine that it is necessary to change the transmission timing set value, change the transmission timing set value stored in the storage means, try communication with the base station with the changed transmission timing value, Means for repeatedly changing the transmission timing setting value until a response from the base station is obtained, comprising: a transmission timing adjustment method in a wireless communication system. 4. When there is a response from the base station that attempted communication, it is determined that a change in the transmission timing set value is not necessary for communication with the base station, and the change is stored in the storage unit. 4. The transmission timing adjustment method in a wireless communication system according to claim 3, wherein communication with the base station is performed using a transmission timing set value.