JPH0239638A - Method for searching vacant channel - Google Patents

Abstract

PURPOSE:To attain proper communication by making a storage in the memory of a vacant channel as it is when a channel channel-searched newly is vacant and erasing the storage in the memory of the vacant channel when it is not vacant. CONSTITUTION:A vacant channel S1 detected by channel-searching is stored in a memory 3. After that, among two channels adjoining to the vacant channel S1, the channel which is within the range of a assigned channel width is channel- searched. Then, when it is judged that the channel-searched channel is not vacant, the vacant channel S1 is not used for communication by erasing the vacant channel S1 from the memory 3. Besides, when it is judged that the channel-searched channel is vacant, a memory in the memory 3 of the vacant channel is made as it is, and the vacant channel is used for the communication. Thus, the proper communication can be executed rapidly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an empty channel search method for a multi-channel access wireless communication method.

(Prior art) When a base station and a mobile station communicate using radio waves,
A multi-channel access method is known that has a plurality of call channels and at least one dedicated control channel, and selects and sets one free call channel from among the call channels to start a call. . As such access, for example, JP-A-61-
As described in Japanese Patent No. 170152, it is known that each channel is searched in order and channels determined to be empty are stored as empty channels, or channels are scanned at random and only empty channels are stored. There is.

(Problem to be Solved by the Invention) However, as described above, if an empty channel is simply selected and set, adjacent channel interference will inevitably occur. That is, for example, in a wireless telephone device that employs a narrowband FM modulation method and operates as described above, if a radio wave that is stronger than that of the desired communication channel is received in a channel adjacent to the set communication channel, the nonlinearity of the amplifier circuit will occur. Adjacent channel interference occurs in that distortion and noise appear in the demodulated output due to the nature and selectivity of the IF filter.

In other words, when a channel is in use and an adjacent channel is searched for, it is determined to be empty based on the received field strength or demodulation noise level. However, the input to the receiver is only one wave, so the determination is made in a state where the influence of nonlinearity of the amplifier does not appear. Therefore, even if a call is started on this channel, if the input level of adjacent waves is high, there is a possibility that large amounts of distortion and noise will be output in the demodulated output. In such a case, it is necessary to reset the setting to another call channel. In this case, it is unavoidable that the time from the generation of a call to the connection of a communication channel becomes probabilistically long.

The present invention has been made in view of the above, and its purpose is to:
To provide an empty channel search method capable of searching for an empty channel that can prevent interference with adjacent channels.

(Means for Solving the Problems) In the vacant channel search method of the present invention, a base station and a mobile station each perform a channel search during standby to detect an unoccupied channel, store the detected unoccupied channel in a memory, and store the detected unoccupied channel in a memory. In a vacant channel search method for a multi-channel access type wireless communication method in which a call is made using one of the vacant channels stored in the
A channel search is further performed for the channel that needs to be searched among the two channels adjacent to each of the detected empty channels, and if the newly searched channel is empty, the empty channel is stored in the memory. is left as is, and if the newly searched channel is not vacant, the storage of the vacant channel in the memory is erased.

(Function) When an empty channel is detected by the channel search, the empty channel is stored in the memory. after that,
A channel search is performed for a channel that needs to be searched among two channels adjacent to the vacant channel, that is, one of the two channels that is within the range of the allocated channel width. If it is determined that the searched channel is not vacant, the vacant channel is deleted from the memory.

As a result, that empty channel will not be used for communication.Also, if the channel searched is determined to be empty, the storage of the empty channel in the memory will remain as it is. , this free channel is used for communication.In other words, among the free channels, only the free channels whose adjacent channels are also free are used for communication.

(Example) FIG. 1 is an overall configuration diagram of a base station A and a mobile station B.

In the figure, reference numeral 1 denotes an interface section with a telephone line, which is composed of a hybrid circuit and the like. 2 is a base station radio section, 3 is a base station control section, 4 is an antenna, 5 is a mobile station audio circuit section, 6 is a mobile station radio section, 7 is a mobile station control section, and 8 is an antenna. Further, in the figure, solid lines (-) represent control lines, and double lines (-) represent signal lines. The channel settings for the radio units 2 and 6 are performed by the CPU in the control unit 3.7.
This is done by controlling the oscillation frequency of the PLL frequency synthesizer in the radio section 4.6.

The embodiment shown in FIG. 1 will be described with reference to FIG. 3 assuming that the base station A searches for an empty channel, and the mobile station B intermittently monitors only the control channel.

First, the control unit 3 of base station A sets a randomly selected communication channel as 81 (step 1). A search is made to see if the channel S1 is vacant (step 2).

If it is determined that it is not free, the previously stored channel S
Delete 1. Then channel S1 is set to 81±m (
m is an integer greater than or equal to 2), then step 3) returns to step 2, and the search is repeated for channels S1±m.

That is, if channel S1 is not vacant, the next channel to be searched is S1+, as shown in FIG.
Adjacent channels S1+1 and 5l-1 are not searched for channels 2 or more and channels 51-2 and F below. However, it is natural that the upper aam is selected from among the values that do not exceed the maximum channel S to which the channel S1+m is allocated and the channel a+aX 51-m does not become negative.

In step 2, if the channel S1 is empty, the channel S1 is stored in the empty channel memory in the control unit 3 (step 4).

Next, change the channel to the adjacent channel 5l-1°S1+1
(Step 5). Those channels 51-
1. Search whether S1+1 is vacant (step 6
). If it is determined that the channel is not vacant, the stored channel S1 is deleted (step 7), and the channel is reset to S1 (n is an integer of 3 or more) (step 8). However, as in the case of n described above, m is the channel S
1+n does not exceed the maximum assigned channel S, and channels 5l-n do not become negative and lax. Then, as shown in FIG. 2, for the channels S1±n set in step 8, the process returns to step 2 and the above-described operations are repeated.

If channel S1±1 is determined to be empty in step 6, the process returns to step 1. In other words, channel S
If channel S1 and Sl±1 are both determined to be empty, channel S1 will be stored in the memory as an empty channel. However, channels 5l-1 and S1+1 are not stored as empty channels, although they are stored in the memory as empty channels. This means that if interference occurs during a call and you want to switch channels, channel 5l-1,
This is because there is a high probability that 81+1 cannot be used.

Therefore, according to the above embodiment, the following effects can be obtained. That is, during standby, it is possible to store vacant channels in memory so that the probability of receiving interference from adjacent channels is reduced, thereby reducing the failure rate during line connection and shortening the average line connection time.

(Effects of the Invention) According to the present invention, it is possible to use only the vacant channels among the vacant channels in which the adjacent channels are also vacant for communication, so that proper communication can be performed quickly.

The clear drawing and FIG. 3 are flowcharts showing an example of the operation of the present invention.

A: Base station, B: Mobile station, 3, 7: Control unit (memory).

Claims (1)

[Claims] Multi-channel access type wireless communication in which a base station and a mobile station each perform a channel search during standby to detect an empty channel, store the detected empty channel in a memory, and conduct a call using one of the empty channels stored in the memory. In the vacant channel search method of the method, a channel search is further performed for a channel that needs to be searched among two channels adjacent to each of the detected vacant channels, and if the newly searched channel is vacant, the above-mentioned A method for searching for an empty channel, characterized in that the storage of the empty channel in the memory is left unchanged, and if the newly searched channel is not empty, the storage of the empty channel in the memory is erased.