JPH10248086A - Access channel arranging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce interference by receiving the request of communication from a terminal station in whole directions so as to execute communication through the use of a sector antenna and permitting an access channel to shift timing with the other radio base station. SOLUTION: Communication is executed between the radio base station and a radio terminal with a specified directional antenna at the same frequency and time. Since a control channel and a user channel spatially differ when the direction of the directional antenna differs even if the frequency and timing, which are equal to those of the other adjacent radio base station, are used, interference does not occur. The control channel and the user channel can effectively be used. Since the access channel transmits data in the whole directions by using all the sector antennas, sector effect cannot be expected. Thus, is hourly executed between the radio base stations while the frequencies similar to those of the control channel and user channel are used. Consequently, the access channel without interference can be set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time division multiple access (T
In a system that performs mobile communication by the DMA (DMA) method,
The present invention relates to a method for allocating an access channel for dividing a radio base station.

[0002]

2. Description of the Related Art When a plurality of radio base stations share a control channel such as an access channel on the same frequency, FIG.
As shown in FIG. 7, a method is used in which wireless base stations autonomously shift transmission / reception time slots. As a result, it is possible to avoid a situation in which transmission and reception timings of the respective radio base stations overlap and a call is lost. This method is called autonomous decentralized base station.

On the other hand, in recent years, broadband communication such as image communication has been studied. When such a broadband communication is realized by radio, the frequency bandwidth occupied by each radio base station is widened, and it is difficult to secure many frequency channels. In addition, providing one or more different types of frequency channels for one access base station and one for a control channel or a user channel requires a synthesizer switching time accompanying a frequency switching time, thereby significantly reducing frame efficiency. I do. Therefore, it is desirable that the access channel, the control channel, and the user channel use the same frequency.

[0004]

In the broadband wireless transmission system, as shown in FIG. 18, the amplitude, phase, and delay of a radio wave are applied to a direct wave path between the radio base station 1 and the radio terminal 4 facing each other. Paths of reflected waves at different times exist due to the nearby reflector 2. For this reason, the receiving side receives them at the same time, causing multipath interference, and significantly deteriorating the communication quality.

[0005] In order to eliminate the influence of the multipath, a sector antenna is effective. The sector antenna covers all directions by a plurality of directional antennas. That is, unlike the method of covering an omnidirectional service area with a single omnidirectional antenna as shown in FIG. 19A, radio waves are radiated in a specific direction of the directional antenna as shown in FIG. Use features. By combining several directional antennas, a sector antenna covering all directions as shown in FIG.

According to the present invention, in the division of a radio base station using a sector antenna, the signals transmitted by the respective radio base stations are distributed autonomously so that the signals transmitted from the respective radio base stations do not interfere with each other. An object of the present invention is to provide an access channel allocation method that enables transmission of bidirectional information while maintaining synchronization.

[0007]

According to the access channel allocation method of the present invention, the directional antennas of the sector antennas are sequentially switched in order for the radio base station and a neighboring radio base station to perform synchronization. Thereby, the access channel is transmitted and received in all directions. As shown in FIG. 1 (1), the control channel and the user channel communicate at the same frequency and time between the radio base station and the radio terminal using a specific directional antenna.
Even if the control channel and the user channel use the same frequency and the same timing as other adjacent radio base stations, if the direction of the directional antenna is different, they are spatially different, so that no interference occurs. If we expect this sector effect,
As for the control channel and the user channel, the channels can be effectively used.

On the other hand, as shown in FIG. 1 (2), since an access channel is transmitted in all directions using all sector antennas, no sector effect can be expected. Therefore, while using the same frequency as the control channel and the user channel, it is temporally divided between the radio base stations. In other words, the access channels can be set without interference by shifting the timing between the wireless base stations and sorting them in time.

[0009]

FIG. 2 shows a configuration example of a radio base station using a sector antenna. In the figure, the radio base station includes 12 directional antennas 12a to 12p, 13a to 1
3p, and a radio base station apparatus 11 to which the sector antennas 12 and 13 are connected. Here, the two sector antennas 12 and 13 are for space diversity.

FIG. 3 shows a frame format of a signal transmitted and received by the radio base station. In the figure, a basic frame 3 is composed of two access channel (Ach) frames 31 and 32 of uplink and downlink. Here, the Ach basic frame is defined as an Ach frame in a state where network synchronization has been established in the radio base station but Ach arrangement has not been completed.
Use them as ch frames.

[0011] The heads of the individual Ach basic frames 31 and 32 are Achs 31a and 32a, which are used to broadcast control information from the radio base station to the radio terminal and synchronize the base stations with other adjacent radio base stations. Is a bidirectional channel between point and multipoint. Control channel (C
ch) 31b and 32b are bidirectional point-to-point bidirectional channels for transmitting control information required for connection between the radio base station and the radio terminal. User channel (U
ch) 31c and 32c are point-to-point one-way or two-way channels for transmitting user information between the wireless base station and the wireless terminal, and can store several Uch bursts.

Achs 31a and 32a are a radio signal time guard time (GT) 33a, a clock recovery code bit timing recovery (BTR) 33b, and a synchronization word provided to prevent burst signal collision. It is composed of a unique word (UW) 33c and a message (ME) 33d storing control information of Ach.

(First Embodiment) FIG. 4 shows a procedure in which a radio base station sequentially transmits Ach from a plurality of sector antennas. First, when power is supplied to the wireless base station, a timing clock from a communication network connected by an optical fiber cable or the like is extracted to perform subordinate synchronization, thereby establishing network synchronization with the communication network. Next, in the Ach structure setting for determining the timing and frequency of the access channel used by the radio base station, the number of B-CS sectors (total of directional antennas of the radio base station) and the number of B-CS antennas (radio base station , The number of Ach transmission sectors (total of directional antennas actually used by the radio base station for communication), the number of Ach transmission antennas (total of sector antennas actually used by the radio base station for communication), Ach An interval value (the product of the number of Ach transmission sectors and the number of Ach transmission antennas) is set.

After setting the Ach structure, the arrangement frequency is determined. In deciding the arrangement frequency, the radio base station receives a plurality of sector antennas 12 and 13 for each of the directional antennas by “Ach interval value × number of times of measurement of the same sector (same directional antenna)” as shown in FIG. The UW of Ach is detected from the Ach basic frame. Since this is performed by the omnidirectional antennas of all the sector antennas of the radio base station, Ach
Will be known.

The radio base station makes a determination by detecting UW of Ach for all available frequencies. As a result, the Ach and Cch of the wireless base station can be arranged without overlapping the Ach and Cch of the adjacent wireless base station in terms of timing, and a frequency with the most usable Uch slots is selected. When there are a plurality of selectable frequencies, the lowest frequency is selected.

The preconditions for determining the arrangement frequency are as follows. Ach 31a, 32a, Cch 31b, 32b, Uch31
Since c and 32c use the same frequency, if the frequency of Ach is determined, the frequencies of Cch and Uch are also determined. Slots other than those in which Ach and Cch are arranged are Uch slots.
In the case where the wireless base station has already been arranged, Uch of the wireless base station is closed at a portion where the Ach slots of the adjacent wireless base stations overlap with each other, because the Uch interferes. This will be described as a third embodiment.

If the frequency of the adjacent radio base station on which Ach has been arranged and the frequency to be selected by the radio base station are only the same frequency, Ach and Cch of the adjacent radio base station are replaced with Ach and Cch of the radio base station. Cch is arranged so as not to overlap in terms of timing. About this, 4th
An embodiment will be described. After determining the optimal arrangement frequency, the arrangement timing is determined. In the Ach basic frames 31 and 32 at the allocation frequency, it is determined whether or not there is interference in a slot that allows allocation of Ach and Cch of the radio base station by performing reception with the size of Ach. . If there is no interference, Ach is arranged with the arrangement timing of the first slot in which Ach and Cch of the radio base station can be arranged. When there is a plurality of Ach arrangement timings without interference, the slot with the lowest number is used. If there is interference in all the slots that can be arranged and there is no Ach arrangement timing for the radio base station, it is determined again whether or not there is an arrangement timing after a certain time has elapsed.

A series of operations up to the above-described Ach structure setting, arrangement frequency determination, and arrangement timing determination are referred to as Ach arrangement processing. The radio base station that has completed the Ach arrangement processing is
Since the frequency of use and the timing of Ach arrangement with the other adjacent wireless base station are in a state, the transmission of the radio wave does not cause interference to the other wireless base station. Therefore, the processing of Ach transmission (or Ach notification) is performed last.

First, the basic structure of Ach (the number of B-CS sectors,
After specifying the number of B-VS antennas, the number of Ach transmission sectors, the number of Ach transmission antennas, and the Ach interval value, transmission of Ach is started. In that case, the transmission of Ach is continued by designating the mode to repeat the start of Ach transmission. Therefore, in the radio base station, a plurality of sector antennas composed of a plurality of directional antennas are used for the Ach frame cycle (2
While switching the directional antenna every ms), Ach is transmitted (broadcast) to other wireless base stations 1 and wireless terminals 4 adjacent to the wireless base station 1 in all directions.

(Second Embodiment) FIG. 5 shows a procedure for selecting a timing by a radio base station. In the figure, when the power is turned on to the radio base station, the radio base station generates a timing clock dependently synchronized with the communication network. Next, Ach transmission is started, and processing for determining the timing and frequency of Ach used by the radio base station (herein, referred to as Ach arrangement processing) is started. The Ach arrangement processing includes Ach structure designation processing, arrangement frequency determination processing, and arrangement timing determination processing.
There are stages, and Ach arrangement processing is performed in this order.

First, in the Ach basic structure designation, the number of B-CS sectors, the number of B-CS antennas, the number of Ach transmission sectors, the Ach
The number of transmitting antennas and the Ach interval value are designated, and the timing clock is reset / started. After the Ach structure designation processing is completed, the transmission / reception frequency of the wireless base station is provisionally set to the lowest frequency. In the allocation frequency determination process, the UW of Ach transmitted by the surrounding wireless base station is detected,
A peripheral zone table that records the presence or absence of UW detection is created. Here, frequencies to be received are selected in ascending order, and Ach appearing in the cycle of Ach basic frames 31 and 32 is selected.
Based on the presence or absence of UW 33c detection of 31a and 32a, a peripheral zone table of Ach detection presence / absence is created. This work,
This is performed for all frequencies that can be received by the wireless base station.

The procedure is determined by the directional antennas 12a to 12p and 13a to 13p of the sector antennas 12 and 13 as to whether or not the UW 33c sequentially received in the cycle of the Ach basic frames 31 and 32 is detected. According to the determination result of the presence / absence of Ach detection, when Ach received from another adjacent radio base station is not detected, the lowest frequency is used, and when Ach is detected, the radio base station uses it. As a result of performing all possible frequencies, the arrangement frequency of the radio base station is determined by selecting the lowest frequency without interference. The method of UW detection is as follows.
"Ach interval value" x "Same sector measurement count"
UW about the time multiplied by the time of "Ach frame"
Is detected, and the Ach basic slot in which the Ach downlink UW 33c is detected is stored as a memory.

FIG. 6 shows the relationship between the UW detection timing and the detected Ach basic slot. For example, A
Each of the 210 obtained by dividing the ch basic frame (2 ms, 80640 symbols) by the Ach size (384 symbols) is called an Ach basic slot, and the detected UW is Δn as shown in the example in the figure.
If it is detected within 188 symbols of n or 196 symbols of ♯n + 1, it is assumed that it is detected in the Ach basic slot of ♯n.

Finally, a placement timing determination process is performed. After determining the usable frequency, in order to determine the Ach arrangement position of the radio base station in the Ach basic frames 31 and 32, after specifying the usable frequency, interference is detected for each basic Uch. A basic Uch slot including a basic Ach slot in which interference has been detected cannot be used, and thus an interference detection table is created to make it impossible to arrange. First, the reception level at the Ach size is detected. As a result, it is determined whether the Ach is larger or smaller than the interference detection threshold. Deploy. If the interference detection threshold is exceeded, after the time specified by the Ach arrangement processing suspension time elapses, the determination is again performed using the interference detection threshold to determine the arrangement timing.

(Third Embodiment) FIG. 7 shows a case where the Ach of the preceding radio base station on which the Ach is arranged and the Uch of the later radio base station using the same frequency overlap. An example in which Uch is closed will be described. When a subsequent radio base station using the same frequency performs Ach allocation processing on a preceding radio base station on which Ach has been allocated, the timing of Ach of the preceding radio base station is Uch of the subsequent radio base station. Causes overlapping interference. The arrow in FIG. 7 indicates that Ach interferes with Uch at the same timing. In order to avoid this, a method is adopted in which Uch is closed and not used in the later radio base station.

FIG. 8 shows a procedure in which the subsequent radio base station blocks Uch when the subsequent radio base station is interfered by Ach of the preceding radio base station on which Ach is arranged. The procedures from power-on, network synchronization establishment, Ach structure setting, and arrangement frequency determination are the same as those described above. Next, the subsequent radio base station transmits Ach in the Ach basic frames 31 and 32.
To determine the arrangement position, the Ach size (= GT33a + BTR33b + UW33) on the Ach basic frames 31 and 32
The reception level at c + ME 33d) is measured. As a result, it is determined whether the value is larger or smaller than the interference detection threshold.
Ach is arranged with the first slot in which a and 32a can be arranged as the arrangement timing.

The later wireless base station is the A of the earlier wireless base station.
The slot numbers where the UW of ch is detected on the Ach basic frame are, for example, slots 3 and 23 as shown in FIG. In this example, the Ach frame is
This is a case where 210 slots are equally divided. In addition, U of Ach
As a method of determining the Uch slot in which W has been detected, the modulo 6 of each detected slot number determines the basic Uch slot for each of the six basic Ach slots starting with the most slot number. If a plurality is the same, the younger one has priority. Also,
If UW of Ach is not detected, 1 is set as the head. For example, the slot number at which the UW of Ach is detected is 3,23,45.
And 48. When modulo 6 is calculated for each slot number, 3 mod 6 = 3 23 mod 6 = 5 45 mod 6 = 3 48 mod 6 = 0. Based on this calculation result, the subsequent wireless base station configures the basic Uch slot starting with the basic Ach slot number 3.

Next, as shown in FIG. 9 (2), in the peripheral zone table of the subsequent radio base station, from the basic Ach slot numbers 3 and 23 for which UW has been detected, three basic Ach slots can be respectively arranged. ”To“ closed ”, and updates the peripheral zone table. Here, the reason why Uch for three basic Ach slots is blocked is that Ach has two slots of downlink and uplink as shown in FIG. 3, and one slot is added as a margin to this slot. After that, as shown in FIG. 9 (3), a blockage table is generated with the Uch slot including the basic Ach slot to be blocked from the peripheral zone table as the blockage basic Uch slot.

Further, in order to make it impossible to arrange Uch from the basic Ach slot where the UW is detected to 18 basic Ach slots from the possible arrangement, the peripheral zone table is further arranged as shown in FIG. 9 (4).
Update as follows. Here, U for 18 basic Ach slots
The reason why a channel cannot be placed is as follows. As shown in FIG. 3, Ach is composed of two slots of downlink and uplink, and the symbol length per slot is 384 symbols. Cch is composed of 16 slots, and the symbol length per slot is the same as Ach. Therefore, A
This is because the sum of ch and Cch is composed of 18 slots having the same symbol length. Here, Ach in which the sector effect of the antenna cannot be expected is called occlusion,
Cch, which can be expected to have a sector effect, is properly used so that it cannot be arranged.

Then, as shown in FIG. 9 (5), a non-arrangeable basic Uch slot including a non-arrangeable basic Ach slot is used as an unarrangeable basic Uch slot to generate an unarrangeable table. Accordingly, when the subsequent wireless base station performs the Ach allocation process on the advanced wireless base station that has already been allocated the Ach, the subsequent wireless base station that overlaps the Ach of the advanced wireless base station on the timing and causes interference. Block Uch of the base station.

(Fourth Embodiment) FIG. 10 shows a case where the Uch of the preceding radio base station on which Ach is arranged and the Ach of the later radio base station using the same frequency overlap. An example in which Uch is closed will be described. After the establishment of Ach and Cch, the starting radio base station detects the interference caused by Ach from an adjacent subsequent radio base station using the same frequency with respect to Uch detected by Uch empty level measurement during Uch allocation processing. Check, if interference occurs, block the Uch and remove it from the channels to be allocated thereafter. Also, as shown in FIG. 3, the frame 3 of 4 ms is a repetition of the Ach frames 31 and 32 of 2 ms, and the interference received by the Ach frame 31 is also received by the Ach frame 32 2 ms later. Therefore, when closing the Ach frame 31, the Ach frame 32 is also closed at the same time.

FIG. 11 shows Uch in the advanced radio base station.
1 shows a first block addition procedure. As a result of starting the Ach block addition process and searching the block table for whether there is an Ach search target Uch, if there is a target channel, a candidate channel slt (n) is determined. However, as shown in FIG. 12, the UW search range of Ach is B symbols +
A symbol + C symbol is set, and it is determined whether the previous and next channels including the search target channel are in use. If it is in use, wait until it is released. slt (n-1),
If slt (n) and slt (n + 1) are not in use, the process proceeds to Ach search processing. In the Ach search process, Ach downlink UW detection is performed for all sectors that transmit Ach in the specified channel slt (n). As a result, Ach in slt (n)
Upon detection of the downstream UW, slt (n) is closed and the process ends.

FIG. 13 shows Uch in the advanced radio base station.
2 shows a second blockage addition procedure. In this procedure, after the candidate channel slt (n) is determined, slt (n-1), slt (n), slt
This is a method of pre-closing (n + 1). As a result, the time required for the block addition processing can be shortened, but on the other hand, there is a demerit that the number of slots serving as Uch allocation candidates is reduced by performing pre-blocking.

Therefore, when priority is given to securing the Uch slot, the first block addition procedure shown in FIG. 11 is used, and when priority is given to shortening the block addition processing time, the second block addition procedure shown in FIG. 13 is used. . How to release the blockage addition
Slt that performs additional blockage processing when communication is closed or at midnight
Ach detection processing is performed for (n), and if Ach down UW is not detected, blockage release of slt (n) is performed.

(Fifth Embodiment) When the radio base stations in adjacent service areas use the same frequency, interference can be avoided by transmitting Ach at different timings. The method will be described below. As a precondition, it is assumed that each wireless base station is synchronized with the network and the clocks between the wireless base stations are synchronized. The radio base station selects the timing according to the method described in the second embodiment.

FIG. 14 shows the concept of the presence or absence of interference between the radio base station A and the radio base station B. In FIG. 14 (1), the radio base station A and the radio base station B have Ach 31a or 32a and Cch 31b in their respective Ach basic frames 31 or 32.
Or, 32b indicates that there is an area overlapping with each other on the timing, so that it causes interference. The arrows in the figure indicate the directions in which Ach 31a, 32a and Cch 31b, 32b give interference to adjacent wireless base stations. FIG.
4 (2), Ach31 of the radio base station A and the radio base station B
No interference occurs because a, 32a and Cch 31b, 32b are not in the region where they overlap with each other on the timing. FIG.
In a state where the radio base stations are synchronized as shown in (2), A
The transmission timings of ch and Cch are different from each other.

FIG. 15 shows a simplified concept of synchronization between radio base stations. FIG. 15A shows an example in which synchronization between base stations is accurately performed, and FIG. 15B shows an example in which synchronization between base stations is loosely performed. In the case of FIG. 15A, Ach 31a or 32a of wireless base station A, and Ach 31a or 32a of wireless base station B, Cch31
b or 32b is a synchronization method. In such a case, the timing requirements for the radio base station apparatus become strict.

In the case of FIG. 15B, Ach of the radio base station A
An access channel synchronization accuracy range 31e is provided immediately after 31a or 32a, Cch 31b or 32b, and Ach 31a or 32a, Cch
This is a method in which a margin is provided in terms of timing with respect to 31b or 32b. With this method, synchronization control between base stations can be easily performed.

First, assume that the symbols of the Ach basic frame 31 or 32 are 80640 symbols. Also, suppose Ach
If 31a or 32a and Cch 31b or 32b have a size of 384 symbols per burst, Ach has 2 bursts and Cch has 16 bursts, the arrangement width of Ach and Cch is (2Ach × 384 symbols) + (16Cch × 384 symbols). ) =
6912 symbols. When 384 symbols of 1 Ach symbol length are given to the Ach and Cch arrangement widths as the access channel synchronization accuracy range 31e, respectively, as shown in FIG.
It can be seen that blocks can be accommodated. This indicates that up to 11 radio base stations can coexist on the Ach basic frame 31 or 32 in synchronization with each other.

Generally, the Ach basic frame length is L _F , A
Assuming that the arrangement width of ch and Cch is L _AC , the number B of radio base stations capable of synchronization between base stations is

[0041]

(Equation 1)

Is as follows. Here, [X] indicates the largest integer not exceeding X. The left side of this equation is the worst case synchronization condition between base stations as shown in FIG.
This is the best condition for synchronization between base stations as shown in (3).
During this time, the number B of wireless base stations capable of synchronizing between base stations exists. Thus, it can be seen that if the synchronization accuracy range is equal to or less than a certain value, the same number of synchronizations between base stations can be easily realized as in the case where ideal synchronization is achieved.

[0043]

As described above, according to the access channel allocation method of the present invention, communication can be performed by receiving a communication request from a terminal station in all directions while using a sector antenna. In addition, interference other than the access channel can be reduced by the sector effect. On the other hand, interference can be reduced by shifting the access channel timing with respect to other radio base stations.

In addition, interference from the user channel to the access channel can be reduced by blocking processing. Synchronization between radio base stations can be easily performed by dividing a frame into slots in units of access channels and detecting a unique word in each lot.

[Brief description of the drawings]

FIG. 1 is a diagram showing a usage of a sector antenna by a channel.

FIG. 2 is a diagram showing a configuration example of a wireless base station using a sector antenna.

FIG. 3 is a diagram showing a frame format of a signal transmitted and received by a wireless base station.

FIG. 4 shows a case where a radio base station sequentially sets A
7 is a flowchart showing a procedure for transmitting a ch.

FIG. 5 is a flowchart showing a procedure in which a radio base station selects a timing.

FIG. 6 is a diagram showing a relationship between a timing at which UW is detected and an Ach basic slot which is assumed to be detected.

FIG. 7 is a diagram illustrating an example in which Uch of a later-occurring wireless base station using the same frequency is blocked when Uch of a later-existing wireless base station that uses the same frequency overlaps with Ach of an earlier-arranged wireless base station.

FIG. 8 is a flowchart showing a procedure for blocking Uch of a subsequent radio base station when the subsequent radio base station is interfered by Ach of the preceding radio base station on which Ach is arranged.

FIG. 9 is a diagram showing a generation image of a blockage / placement impossible table.

FIG. 10 shows Uch of the advanced wireless base station in which Ach has been arranged,
The figure which shows the example which closes Uch of a starting radio base station when Ach of a succeeding radio base station using the same frequency overlaps.

FIG. 11 is a flowchart showing a first blocking addition procedure of Uch in a starting radio base station.

FIG. 12 is a diagram showing a UW search range.

FIG. 13 is a flowchart showing a second blocking addition procedure of Uch in a starting radio base station.

FIG. 14 is a view showing the concept of the presence or absence of interference between the radio base station A and the radio base station B.

FIG. 15 is a diagram showing a concept of simplified synchronization between wireless base stations.

FIG. 16 is a diagram showing the concept of the number of wireless base stations that can be used by simplified synchronization between wireless base stations.

FIG. 17 is a diagram illustrating the concept of autonomous distributed control.

FIG. 18 is an explanatory diagram of a multipath.

FIG. 19 is a diagram showing an example of a radio wave radiation pattern.

[Explanation of symbols]

 Reference Signs List 1 radio base station 11 radio base station apparatus 12, 13 directional antenna 2 reflector 3 frame 31, 32 access channel (Ach) frame 31a, 32a access channel (Ach) 31b, 32b control channel (Cch) 31c, 32c user channel (Uch) 31e Access channel synchronization accuracy range 33a Guard time (GT) 33b Bit timing recovery (BTR) 33c Unique word (UW) 33d Message (ME) 4 Wireless terminal

Claims (5)

[Claims] 1. A method for arranging access channels of a radio base station that transmits and receives radio waves using a plurality of sector antennas composed of a plurality of directional antennas, wherein the directional antenna and the sector antenna are sequentially switched to perform reception. Performing, detecting the unique word for each frequency of the access channel transmitted from the adjacent wireless base station in all directions, at a timing other than the timing when the unique word of the adjacent wireless base station is detected,
An access channel allocating method characterized by determining a transmission timing of an access channel of the radio base station. 2. A method for arranging access channels of a radio base station for transmitting and receiving radio waves using a plurality of sector antennas composed of a plurality of directional antennas, comprising the steps of: Sequentially, and receives the access channels transmitted by the surrounding radio base stations, detects the unique word for each frequency of the access channel transmitted by each of the radio base stations, and detects the adjacent radio base station from the detection of the unique word. Detects the presence or absence of an access channel from, selects a predetermined frequency without interference, determines the allocation frequency of the radio base station, and for each of the basic user channels with respect to the allocation frequency,
When the reception level at the access channel size is detected and the value is smaller than the interference detection threshold, the access channel arrangement position of the radio base station is determined using the first slot in which the access channel can be arranged as the arrangement timing. A method for arranging access channels. 3. An access channel allocation method in which a subsequent wireless base station using the same frequency allocates an access channel to a preceding wireless base station on which an access channel has been allocated. An access channel allocation method comprising: detecting a reception level based on a channel size; and blocking a user channel when the level is greater than an interference detection threshold. 4. An access channel allocation method for allocating a user channel to a radio base station having an access channel allocated thereto, wherein the subsequent radio base station uses the same frequency when the radio base station measures the idle level of the user channel. An access channel allocation method characterized by blocking a user channel when an empty level is not detected due to interference from the access channel. 5. An access channel allocating method in which a plurality of radio base stations synchronize for autonomously allocating an access channel, wherein an access channel frame is divided into a plurality of slots according to the size of an access channel and a control channel. Detecting a unique word of an access channel in each slot, and synchronizing between the radio base stations so as not to arrange more than one radio base station in one slot. .