JPH08205231A - Radio access control method - Google Patents

Abstract

PURPOSE: To reduce probability that all signals become unreceivable by classifying mobile stations into groups by reception levels at a base station and giving the permission of access while combining high-level groups with low-level groups satisfying a required desired signal/interference signal level radio (CIR). CONSTITUTION: The reception levels of signals transmitted from the base station to the mobile stations are measured in advance, and classified into level ranges more than three such as four level groups 41-44, for example, based on plural boundary values decided in advance. In this case, the boundary values are set separately by the value of the required CIR so that the bottom level of the level group 41 and the peak level of the level group 43 can satisfy the required CIR and both groups can be decided as access permitted level groups, for example. Namely, even when access signals are simultaneously transmitted from the group at the high reception level and the group at the low reception level to the base station, the signal from the group at the high level can be received. As a result, the number of signals to be transmitted from the mobile station belonging to the high-level group is decreased so that the access signal of the low-level group can be easily received as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system in which a plurality of mobile stations simultaneously transmit signals to a base station so that signals from the mobile stations interfere with each other.
The present invention relates to a radio access control method for suppressing that all signals cannot be received at a base station.

[0002]

2. Description of the Related Art After transmitting an access signal to a base station, each mobile station waits for an access acceptance signal to be responded by the base station when the signal is correctly received. Here, this waiting time is managed by a timer, and when the timer expires, the access signal is transmitted again to the base station. The access is completed by repeating this until it is correctly received by the base station.

In the above, when the number of mobile stations to be accessed increases, access signals from the mobile stations are simultaneously transmitted and often interfere with each other. Further, the number of retransmissions due to the interference also increases, so that the number of access signals further increases and the access signals become in a congestion state. In order to avoid such a situation, wireless access control that limits the number of mobile stations that can be accessed will be implemented.

In the conventional radio access control method, a base station determines a certain probability value and a mobile station trying to access is
Each decides whether or not to transmit according to its probability value and uses a method to access when transmission is possible, or a numerical value that can be specified by each mobile station such as the telephone number of the mobile station,
There is a method in which the base station specifies a group of numbers that can be transmitted or cannot be transmitted, and switches the group of numbers to be designated depending on time.

In any case, the control method aims to provide the same accessible probability regardless of the position of each mobile station in the radio zone and the reception level of the signal from each mobile station at the base station. Is.

[0006]

FIG. 1 is a diagram showing a state in which a plurality of mobile stations are transmitting access signals to a certain base station.

In FIG. 1, the base station 11 is a radio zone 1
Forming 2. Here, there are three mobile stations 13, 14, and 15 in the wireless zone 12, and when the access signal transmitted by each mobile station is received by the base station 11, the transmission signal 16 of the mobile station 13 is transmitted. It is assumed that the level is the highest, and the transmission signal 17 of the mobile station 14 and the transmission signal 18 of the mobile station 15 become lower in this order.

Generally, even when signals from a plurality of mobile stations are simultaneously transmitted to a base station, the difference between the reception levels of the signals at the time of receiving the base station must satisfy a desired desired signal-to-interference signal level ratio (hereinafter, required CIR). If so, the signal of the maximum reception level can be accurately received by the base station.

In FIG. 1, it is assumed that the transmission signal 16 satisfies the required CIR for the transmission signal 18, but does not satisfy the other transmission signals.

FIG. 2 is a diagram for explaining interference between access signals of each mobile station when the conventional radio access control is performed under the conditions described in FIG.

In the figure, the horizontal axis represents the passage of time, 4
Base station 11, mobile stations 13, 14 and 15 from above
7 shows the transmission / reception timing of a signal to / from. The base station 11 has three reception timings, and at this time, the operation of receiving an access signal from each mobile station is executed.
Here, as the radio access control, it is assumed that the above-described method in which the base station determines a certain probability value and each mobile station follows the probability value is performed.

When three mobile stations are permitted access to the reception timing 21-1, signal transmission 23-
Performing steps 1, 24-1 and 25-1 requires the required CI in the base station.
There is no signal that satisfies R, and all signals become non-received due to interference, and all three mobile stations will retransmit.
Next, when the mobile stations 14 and 15 are permitted to access the reception timing 21-2, signal transmission 24-2,
If 25-2 is carried out, similarly, interference causes non-reception.
Furthermore, when the mobile stations 13 and 14 are permitted to access the reception timing 21-3, signal transmission 23-
Nos. 2 and 24-3 are non-received due to interference, and eventually, when three reception timings of the base station 11 have passed, access to all mobile stations is incomplete.

Even with the method of designating a group of radio access control numbers, mobile stations that have been granted access are evenly distributed in the radio zone, and therefore the signals transmitted by the mobile stations are received by the base station. The levels will have random values, which will result in similar results as above.

The present invention provides a radio access control method for reducing the probability that no signals satisfy the required CIR and all signals are not received when a plurality of access signals overlap at the base station reception timing. With the goal.

[0015]

According to the present invention, a mobile station measures in advance the reception level of a signal transmitted from a base station,
A combination of a group having a high level range and a group having a low level range, which are grouped into three or more level ranges by a plurality of predetermined boundary values and satisfy the required CIR that can be received by the base station, is predetermined as an access permission level group.

Also, the base station determines by broadcasting a plurality of boundary values and access permission level groups for grouping the reception levels.

Further, the base station sequentially switches the currently determined access permission level group to another group and notifies the newly determined access permission level group each time. Alternatively, a mobile station other than the currently defined access permission level group autonomously releases the non-permission after a certain period of time has elapsed after recognizing that the access is not permitted.

[0018]

The present invention is characterized in that mobile stations are grouped according to the reception level at the base station, and a group having a higher level is combined with a group having a lower level to satisfy the required CIR to give access permission. FIG. 3 is a diagram illustrating interference between access signals of mobile stations when the radio access control of the present invention is performed under the conditions described in FIG. The notation method in the figure is the same as that in FIG.

Now, the reception timings 21-1 to 21-2
During the period, the mobile station 13 having a high reception level and the mobile station 15 having a low reception level
Suppose you have been given permission to. Reception timing 2
The mobile stations 13 and 15 transmit signals 1 to 1-1 respectively.
When steps 3-1 and 25-1 are performed, the base station receives the signal of the mobile station 13 that satisfies the required CIR. The mobile station 15 retransmits by the signal transmission 33-2, but the reception timing 2
In 1-2, the signal of the mobile station 15 is received. Next, from the reception timing 21-3, the access disapproval for the mobile station 14 is released, and at the same time, the mobile stations 13 and 15 are disapproved. Signal transmission 24-3 is performed from the mobile station 14,
Since the mobile stations 13 and 15 have already completed the access, the signal of the mobile station 14 will be received alone.

That is, even if the access signals are simultaneously transmitted from the group having a high reception level and the group having a low reception level to the base station, the signals of the high group can be received. Because it is random access,
If there is no access signal from the high group, the signal of the low group is received by the base station during that time, but if the signal is transmitted from the high group, the access of the mobile station belonging to the high group is preferentially completed. It will be. As a result, by reducing the number of retransmission signals of mobile stations belonging to the high group, it becomes possible to easily receive access signals of the low group. In addition, mobile stations belonging to the level group that is not granted access permission
By autonomously releasing access prohibition after a certain time,
The procedure of notification from the base station can be omitted.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 4 is a diagram for explaining an embodiment for defining a boundary value and an access permission level group for grouping the level ranges of wireless access control according to the present invention.

In the figure, three boundary values are set and divided into four level groups 41, 42, 43 and 44. By setting the boundary values so that they are separated by the required CIR,
For example, the minimum level of the level group 41 and the maximum level of the level group 43 can satisfy the required CIR, and both groups can be defined as access permission level groups. An example of combination of other level groups is shown in the figure.

FIG. 5 shows a first radio access control of the present invention.
2 is a flowchart illustrating an example of the above. First, FIG.
The boundary value and the access permission level group are determined in advance by the method as described in (51), and the mobile station stores them.
When the mobile station tries to access the base station, the reception level of the base station transmission signal is measured in advance (52), and each mobile station recognizes the level group to which the mobile station belongs based on the measured value (5).
3). It is determined whether the group to which the group belongs is an access permission level group (54), and an access signal is transmitted to the base station (55). The above is repeated until the access to the base station is completed (56).

To group the level ranges so that the required CIR at the time of receiving the base station is satisfied, strictly speaking, it is necessary for each mobile station to know the base station reception level of the signal transmitted by itself. On the other hand, in the above, the belonging level group is determined by the mobile station reception level of the base station transmission. This is an embodiment in consideration of the fact that the reception levels of a specific base station and mobile station are the same.

FIG. 6 shows a second radio access control of the present invention.
2 is a flowchart illustrating an example of the above. The difference from the first embodiment in the figure is that the boundary value and the access permission level group are determined by the judgment of the base station, and the mobile station is notified (61), and the mobile station stores it (62). ) It is a point. As a result, it is possible to flexibly deal with the base station decision according to the congestion situation of the access signal, and thus it becomes possible to control the optimum access permission level group.

FIG. 7 shows a third example of the radio access control of the present invention.
2 is a flowchart illustrating an example of the above. In the figure,
In addition to the second embodiment, an embodiment is shown in which the access permission level group is switched during wireless access control. The relationship with the second embodiment in the figure is the same until the boundary value is determined by the base station judgment, the mobile station is notified (71), and the mobile station stores it (72). The access permission level group is adaptively switched at any time, and it is notified (7
3) and the mobile station recognizes and stores the switching (7).
4) Differences. As a result, it is possible to avoid that the stopped mobile station always corresponds to a group other than the access permission level group and is not permitted access forever.

FIG. 8 shows a fourth example of the radio access control of the present invention.
2 is a flowchart illustrating an example of the above. In the figure,
In addition to the first embodiment, an embodiment in which the mobile station autonomously releases the access disallowance during the radio access control is shown. The relationship with the first embodiment in the figure is the same as that of judging whether or not the group to which each mobile station belongs is the access permission level group (54). If the level group is other than the level group, an access signal is transmitted after a lapse of a certain time by using a timer or the like (81). As a result, the same effect as that of the third embodiment can be obtained, and further, in this embodiment, it is possible to perform the radio access control without requiring the operation of the base station at all.

[0028]

As described above, the present invention divides mobile stations into groups according to the reception level at the base station, and gives access permission to a group having a high level and a group having a high level satisfying the required CIR. Therefore, when an access signal is simultaneously transmitted from a plurality of mobile stations, it can be reduced as compared with the conventional method in which there is a high probability that all signals will not be received by the base station.

[Brief description of drawings]

FIG. 1 is a diagram showing how access signals are transmitted by a plurality of mobile stations.

FIG. 2 is a diagram illustrating interference between access signals of conventional radio access control.

FIG. 3 is a diagram illustrating interference between access signals of radio access control according to the present invention.

FIG. 4 is a diagram illustrating an example of defining a boundary value and an access permission level group for grouping level ranges according to the present invention.

FIG. 5 is a diagram illustrating a first embodiment of wireless access control according to the present invention.

FIG. 6 is a diagram illustrating a second embodiment of wireless access control according to the present invention.

FIG. 7 is a diagram illustrating a third embodiment of wireless access control according to the present invention.

FIG. 8 is a diagram illustrating a fourth embodiment of wireless access control according to the present invention.

[Explanation of symbols]

11 base station 13 to 15 mobile station 21-1 to 21-3 reception timing 23-1 to 23-2, 24-1 to 24-3, 25-1 to
25-2 signal transmission

Claims (4)

[Claims] 1. A base station forming a wireless zone and a plurality of mobile stations located in the wireless zone and trying to communicate with the base station, wherein the plurality of mobile stations are random with respect to the base station. In a radio access control method for a mobile communication system to access, each mobile station measures a reception level of a signal transmitted from the base station in advance, and the reception level is 3 or more depending on a plurality of predetermined boundary values. And a combination of a group having a high level range and a group having a low level range is predetermined as an access permission level group so that the base station can receive the desired signal-to-interference signal level ratio or more. A radio access control method, characterized in that only mobile stations in the permission level group are controlled so that radio signals can be transmitted to the base station. 2. The radio access control method according to claim 1, wherein the base station notifies the mobile station of the plurality of boundary values that divide the reception level into groups, and the access permission level group also includes the access permission level group. A radio access control method, characterized in that it is determined by reporting from a base station to a mobile station. 3. The wireless access control method according to claim 1, wherein the base station sequentially switches the currently determined access permission level group to another group, and newly determines each time. A wireless access control method, characterized in that the mobile station is notified of the access permission level group. 4. The wireless access control method according to claim 1, wherein the mobile stations other than the currently defined access permission level group recognize that access is not permitted, A wireless access control method characterized by autonomously releasing a disapproval after a lapse of a predetermined time.