JP2000333257A - System for setting path between mobile unit and radio base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To distribute a load of a radio base station onto which calls are concentrated, to enhance the speech quality and to effectively utilize a communication capacity of a radio base station with a few calls. SOLUTION: In this path setting system, a base station controller 1 periodically requests a traffic density of each radio base station and compares the received traffic density. When a difference between the traffic density is higher than a threshold value, the controller 1 discriminates that there is a deviation in the traffic density between neighboring base stations. In this case, the base station controller 1 calculates a difference of the received electric field strength between a radio base station 2 with large traffic density and a radio base station 3 with small traffic density, and confirms it that the difference is a threshold or over. When the base station controller 1 recognizes the difference from the received electric field strength, the base station controller 1 receives a frame error rate of a radio transmission channel 14 and discriminates whether or not a path can be set via a radio repeater 7. When discriminating the relay path, the base station controller 1 sets a path to a mobile unit 6 in an area with large traffic density extended to the adjacent radio base station 3 with small traffic density by using the radio repeater 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital cellular system using a CDMA system, and more particularly to a path setting system between a mobile station and a radio base station.

[0002]

2. Description of the Related Art In a CDMA system, a mobile station measures the electric field strength of a radio base station that can be handed off during a call, and among the radio base stations having a reception electric field strength level equal to or higher than a certain threshold value, A path is established with a plurality of wireless base stations in order from a wireless base station having a strong reception electric field strength. Further, when the received electric field strength becomes equal to or less than a certain threshold value, a process of cutting a stretched path is performed.

[0003]

The conventional path setting method in the digital cellular system using the CDMA method has the following problems.

[0004] The first problem is that the communication capacity is determined only within the area of the radio base station.
That is, the number of paths of one wireless base station is limited, and the frequency cannot be used efficiently.

[0005] The second problem is that since a radio base station that extends a path is determined based on the strength of a pilot signal, a path can be extended from a mobile station only to a nearby radio base station.

In the CDMA system, since a plurality of mobile stations use the same frequency, a weak transmission power is output from a mobile station near a radio base station and a strong transmission power is output from a mobile station far from the radio base station. By controlling the power so as to output the transmission power, both interferences at the wireless base station are suppressed. The CDMA system is a multipath in which each mobile device communicates with a plurality of radio base stations, and operates so as to maintain communication quality over the entire communication path. However, a mobile station located near a radio base station where calls are concentrated will increase the output in order to improve the communication quality in the presence of strong electric field strength that causes interference. Inevitably, the communication quality between the radio base station and each mobile unit is significantly degraded.

SUMMARY OF THE INVENTION An object of the present invention is to disperse the load of a radio base station where calls are concentrated, improve the communication quality, and effectively utilize the communication capacity of a radio base station with few calls. It is to provide a path setting method.

[0008]

According to the present invention, in a path setting method between a mobile station and a radio base station in a digital cellular system using a CDMA system, a radio repeater is interposed between radio base stations. , When a certain radio base station is more concentrated in call volume than an adjacent radio base station,
By extending a path to a mobile station of a radio base station having a high traffic volume through the radio repeater to a radio base station having a low traffic volume, the electric field strength at the radio base station having a high traffic volume is reduced. And

The present invention also provides a method for determining whether or not a path is established between a mobile unit of a radio base station having a high traffic volume and an adjacent radio base station having a low traffic volume through the radio repeater. The traffic intensity of each radio base station, the error rate of the radio transmission path between the mobile station and the radio base station, and the error rate of the radio transmission path between the mobile station and the radio repeater. And

[0010]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram for explaining an outline of a path setting method between a mobile station and a radio base station according to the present invention.
In FIG. 1, the base station control apparatus 1 checks a traffic difference between the base station and a neighboring base station, and sets a path for distributing the load using the wireless repeater 7.

The base station controller 1 has wireless base stations 2 and 3 under its control. The mobile device 6 is one of the mobile devices existing in the area of the wireless base station 2.

An antenna having strong directivity and an antenna having no directivity are provided between the radio base stations 2 and 3, and the antenna having strong directivity is directed to the radio base station to communicate with the base station. At the same time, there is a wireless repeater 7 that can communicate with a nearby mobile device using an omnidirectional antenna and relay wireless radio waves.

In FIG. 1, a base station control device 1 transmits, through a radio repeater 7, a mobile station 6 located in an area of a radio base station 2 having a high traffic volume Cl2 and a radio base station 3 having a low traffic volume Cl3.
The communication quality of the mobile device 6 is improved by setting a path that can communicate with the mobile device 6. By reducing the output power of the mobile device 6, interference with other mobile devices is reduced.

The base station control device 1 controls each of the radio base stations 2 and 3
, And the error rate Er of the wireless transmission path. A wireless base station 2 having a larger traffic volume than a neighboring wireless base station is detected, and a wireless base station 3 having the least traffic volume near the wireless base station is detected.

The communication between the radio base station 3 and the radio repeater 7 confirms how much the communication in the area of the radio base station 3 is affected by transmitting and receiving test signals. The difference between the electric field strength at the wireless base station 3 after the test signal transmission and the electric field strength at the wireless base station 2 is calculated.

A specific signal is transmitted by the radio repeater 7 so that the radio base station 3 and the mobile station 6 having a small traffic can establish a path. From the mobile station 6 passing through the radio repeater 7 to the base station controller 1
If the wireless transmission path error rate is found to be more effective than Er11, it will be used until the electric field strength in the wireless repeater 7 falls below the threshold for disconnecting the path.

As described above, in this embodiment, the base station controller checks the traffic difference between the base station and the neighboring base station, and sets a path for distributing the load using a radio repeater. Therefore, it is possible to reduce the electric field strength in the area of the radio base station where the load is concentrated, and to improve the communication quality.

FIG. 2 is a specific configuration diagram showing an embodiment of a path setting method between a mobile station and a radio base station according to the present invention. In FIG. 2, the base station control device 1 checks a traffic difference between the base station and a neighboring base station, and sets a path such that a load is distributed using a wireless repeater.

The base station controller 1 has wireless base stations 2, 3, 4, and 5 under its control. The mobile device 6 is one of the mobile devices existing in the area of the wireless base stations 2 and 3.

Between the radio base stations 2 and 4, an antenna having a strong directivity and an antenna having no directivity are provided, and the antenna having a strong directivity is directed to the radio base station to communicate with the base station. At the same time, there is a wireless repeater 7 that can communicate with a nearby mobile device using an omnidirectional antenna and relay wireless radio waves.

The wireless base station 2 and the mobile device 6 communicate with each other via the wireless transmission channel 11, and the wireless base station 3 and the mobile device 6 communicate with each other via the wireless transmission channel 12.

The base station control device 1 requests each radio base station for the received electric field strength, the traffic volume of the radio base station, and the frame error rate in the radio transmission path, and receives the received electric field strength R2 from each radio base station. , R3, R4, R5, the traffic volume Cl2, Cl3, Cl4, Cl5 of the radio base station, and the uplink frame error rates Er11, Er1 of each radio transmission path.
2 reports can be received. Also, by setting the communication radio base station 5 in the radio repeater 7, the radio base station 5
And a specific communication signal, and communicate with the mobile device 6 near the wireless repeater 7.

In this embodiment, the radio base stations 2, 3, 4, 5 exist under the control of the base station control device 1, and the radio relay device 7 exists in the area of the radio base station 3.
Further, the traffic Cl3 of the wireless base station 3 is large, and accordingly, the received electric field strength R3 at the wireless base station 3 is also increased. On the other hand, the radio base station 5 having a low level for both the traffic and the received
Exists near the wireless base station 3.

The base station controller 1 periodically requests each radio base station to report the traffic, and compares the maximum traffic (Cl3) and the minimum traffic (Cl5) based on the received report. When the difference (Cl3-Cl5) between the two traffic levels is larger than the threshold value (ΔCl) held in the base station controller 1, it is determined that there is a bias in the traffic levels between nearby wireless base stations. In that case, the base station control device 1
Request to report the received electric field strength of Upon receiving the request, the radio base stations 3 and 5 measure the received electric field strengths (R3 and R5),
The value is reported to the base station controller 1.

The base station controller 1 calculates the difference (R3-R5) between the received electric field strength at the radio base station with a large traffic and the received electric field strength at the radio base station with a small traffic, and calculates a threshold ( Δ
R) Check if it is more than. When a difference is also found in the received electric field, the base station control device 1 requests the wireless repeater 7 to perform a relay setting, sets the antenna in the wireless repeater 7, and relays the radio wave of the wireless base station 5. To

First, test data is transmitted from the radio base station 5 in response to a request from the base station controller 1. The wireless repeater 7 returns the received test data to the wireless base station 5. The base station control device 1 receives the report of the frame error rate of the test data on the wireless transmission path 14 and the electric field strength at the wireless base station 5 at the time of executing the test data transmission and reception from the wireless base station 5, and passes the report via the wireless repeater 7. Make a decision whether or not to be able to stretch.

When it is determined that relay is to be performed, the base station control device 1 uses the wireless repeater 7 to route the path between the adjacent wireless base station 5 with a small traffic and the mobile device 6 in an area with a large traffic. Stretch.

As a result, it is possible to reduce the electric field strength at the radio base station 3 having a large traffic volume and to improve the communication quality of the whole under the control of the base station controller 1.

FIG. 3 is a detailed block diagram of the base station controller 1 and the radio repeater 7 shown in FIG.

In the base station controller 1 of FIG.
The data communication processing unit 1a performs voice / data communication processing so as to connect the wireless section and the wired section,
b performs communication control of the base station controller 1 itself and processing of control performed from the base station controller 1 to subordinate devices.
The path setting control unit 1c is to perform a path setting process. In this embodiment, a relay path setting control unit 1d and a wireless repeater setting control unit 1e are added to set a path via the wireless repeater.

The relay path setting control unit 1d periodically refers to the traffic data of each base station, retrieves and holds data necessary for determining the path setting, and uses these data to perform the relay path setting. A process is performed to determine whether or not to implement.

The radio repeater setting control unit 1e holds data of all the radio repeaters existing under the base station controller 1, and manages the settings and operation states of the subordinate radio repeaters.

The radio repeater 7 shown in FIG. 3 includes an antenna 7a having strong directivity for communicating with the radio base station, and a rotator 7b for directing the antenna toward the radio base station to be relayed.
, A transceiver 7c with the radio base station 5, an antenna 7d equivalent to each radio base station, a transceiver 7e with the mobile station, and a loopback for returning data received from the radio base station to the radio base station. A control unit 7f for controlling the antenna direction to the wireless base station to be set and relayed, and controlling the output in the same manner as the mobile station in response to a request from the base station controller.

Although the embodiment of the present invention has been described in detail, the radio base station and the mobile station shown in FIGS. 2 and 3 are existing ones and are well known to those skilled in the art. Since it does not directly relate to the invention, a detailed description thereof will be omitted.

Next, the path setting operation of FIG. 2 will be described with reference to the flowchart shown in FIG.

ΔCl, ΔR previously possessed by the base station controller 1
Are determined, ΔCl = 200, ΔR =
2 (mW).

In step F1, the traffic volume Cl2, Cl3, Cl is periodically transmitted from the radio base station to the base station controller 1.
Receive a report of 4, Cl5. The call volume for 5 minutes is Cl2 = 2
00, Cl3 = 350, Cl4 = 150, Cl5 = 50
Assume that

In step F2, the maximum traffic (Clm
ax), and when there is a wireless repeater in standby in the Clmax wireless base station area, the minimum traffic (Clmin) is extracted from the wireless base stations capable of relaying. Cl
max = Cl3 = 350 and Clmin = Cl5 = 50.

In step F3, it is determined whether or not (maximum traffic volume-minimum traffic volume) exceeds the threshold value of the base station controller. If it does, the relay path setting process is continued. It is determined that the difference between the radio base station having the traffic volume and the radio base station having the minimum traffic volume that can be relayed is not sufficiently large, and that the relay path setting is unnecessary. Therefore, ΔCl
Is larger, the relay path setting becomes more difficult to function, but if ΔCl is loose, the number of times that the relay path setting is determined to be necessary at this stage increases, and enormous processing is required for relay determination. Then, when the relay is started, the traffic disparity immediately decreases, and in some cases, the disparity may be reversed. Since Clmax−Clmin = 300> ΔCl = 200, it is necessary to set a relay path.

In step F4, the electric field strengths R of the radio base stations 3 and 5, which are to be the radio relay source and the radio relay destination, are set.
The base station controller 1 requests max and Rmin, and receives a report of these electric field strengths. Rcmax = 20 (m
W), Rcmin = 15 (mW).

In step F5, it is determined whether or not the wireless base station of the wireless relay destination has a sufficient communication capacity as compared with the wireless base station of the wireless relay source based on the threshold value of ΔR. Rcmax−Rcmix = 5 (mW) In step F6, the base station control device 1 requests the wireless repeater 7 to relay the control signal of the wireless base station 5, and based on this request, the wireless repeater 7 The direction of the antenna is changed and synchronization is performed so that the signal of the wireless base station 5 can be received.

In step F7, the base station controller 1
Requests the wireless relay device 7 to return the received signal to the wireless base station, and after completing the return setting, the wireless base station 5
The test data is transmitted through and the returned data is received.

In step F8, the radio base station 5 reports the radio transmission line frame error rate Ert of the test data to the radio network controller 1 and the received electric field strength Rcmin 'at the radio base station 5 at the time of executing the test data reception. . Ert = 0.01 (%), Rcmin '= 16 (m
W).

In step F9, it is determined whether or not the difference between the electric field strength of the radio base station 3 having a large traffic volume and the electric field strength of the radio base station 5 having a small traffic volume exceeds a threshold value. Rcmax−Rcmix = 4 (mW)> Δ
It is assumed that R = 2 (mW).

In step F10, the control signal of the radio base station 5 is relayed by the radio repeater 7 so that the radio base station 5 can be handed off to the radio relay destination. The difference between the frame error rate of the signal sent to the wireless base station 5 via the wireless repeater 7 and the frame data at the time of receiving the test data is the difference between the wireless transmission path frames of the wireless base stations 2 and 3 with which communication is currently being performed. If the error rate is lower than the error rate, it is determined that the relay path is not very effective, and the relay path is not set. It is assumed that the wireless transmission line frame error rate between the mobile device 6 and the wireless repeater 7 is lower than the wireless transmission line frame error rate between the mobile device 6 and the wireless base stations 2 and 3.

In step F11, it is checked whether there is a mobile device 6 that can be handed off via the wireless repeater 7.

In step F12, the base station controller 1 performs path setting control so that the mobile station 6 and the wireless base station 5 in the area of the wireless base station 3 can establish a path via the wireless repeater 7.

In step F3, when the traffic difference between the radio base station having a large traffic and the radio base station capable of relaying and having a small traffic is small, that is, even if the base station has a large traffic, the traffic is not so large. If the traffic volume is not large or the traffic volume of the base station capable of relaying is large, in step F13, it is not necessary to set a relay path for this radio base station having a large traffic volume.
Or, it is determined that it is impossible.

In steps F5 and F9, when the difference in electric field strength between the radio base station having a high traffic and the radio base station capable of relaying and having a low traffic is small, that is, a relay path is set to the radio base station having a low traffic. However, if the base station also has a high electric field strength, or if power control is sufficiently performed in the wireless base station with a large traffic volume and the wireless base station has sufficient communication quality, a relay path should be established. If it is determined that the effect obtained in the step cannot be expected so much, steps F10 and F1
In item 1, when the quality of the radio transmission path between the mobile station and the radio repeater is poor or when there are no mobile stations around, or when there are several radio base stations near the radio relay station, it is listed as a handoff candidate for the mobile station. If it is determined that there is not much point in setting a path using a wireless repeater when there is no
In 14, the setting is changed to the next wireless base station having the next smaller traffic, and the processing is started again by comparing the traffic.

[0051]

As described above, according to the present invention, a setting is made so that a path to another radio base station can be established through a radio repeater for a mobile unit of a radio base station having a traffic volume greater than that of a neighboring base station. Therefore, the output power of the mobile station close to the wireless repeater can be suppressed, and the electric field strength at the wireless base station having a large traffic can be reduced, so that the communication quality can be improved.

Further, according to the present invention, since a path is set up through a radio relay to a radio base station having a small traffic, the communication capacity of the radio base station having a small traffic can be effectively used.

Further, according to the present invention, a relay path can be established for a radio base station to which a path cannot be established directly from a mobile station through a radio repeater, so that more mobile stations can establish a path to the base station. , Communication quality can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an outline of a path setting method between a mobile station and a radio base station according to the present invention.

FIG. 2 is a specific configuration diagram showing an embodiment of a path setting method between a mobile station and a radio base station according to the present invention.

FIG. 3 is a detailed configuration diagram of a base station control device and a wireless repeater.

FIG. 4 is a flowchart illustrating a path setting operation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 base station control device 1a voice / data communication processing unit 1b communication control processing unit 1c path setting control unit 1d relay path setting control unit 1e wireless repeater setting control unit 2, 3, 4, 5 wireless base station 6 mobile unit 7 wireless Repeater 7a, 7d Antenna 7b Rotator 7c, 7e Transceiver 7f Controller

Claims (6)

[Claims] In a path setting method between a mobile station and a radio base station in a digital cellular system using a CDMA system, a radio repeater is sandwiched between radio base stations,
When a certain radio base station has a concentrated call volume in comparison with an adjacent radio base station, a radio having a small traffic volume adjacent to the mobile unit of the radio base station having a high traffic volume through the radio repeater. A path setting method between a mobile station and a wireless base station, wherein a path is provided to the base station to reduce the electric field strength at the wireless base station having a large traffic volume. 2. A method for determining whether to establish a path to a mobile station of a radio base station having a high traffic volume through a radio repeater to an adjacent radio base station having a low traffic volume, comprising:
The method according to claim 1, wherein the reception electric field strength of each radio base station, the error rate of the radio transmission path between the mobile station and the radio base station, and the error rate of the radio transmission path between the mobile station and the radio repeater are compared. 2. A path setting method between a mobile station and a radio base station according to 1. 3. When the difference in electric field strength between a radio base station having a large traffic volume and a radio base station capable of relaying and having a small traffic volume is small, the setting is changed to the radio base station to be relayed having the next smaller traffic volume. 3. The path setting method between a mobile station and a radio base station according to claim 1, wherein the processing is started again from the comparison of the traffic. 4. The method according to claim 1, wherein a determination is made periodically as to whether or not a path is established between the mobile unit of the radio base station having a high traffic and the adjacent radio base station having a low traffic through the radio repeater. A path setting method between a mobile station and a radio base station according to claim 1. 5. The radio repeater includes an antenna having a strong directivity and an antenna having no directivity, and directs an antenna having a strong directivity to a radio base station to communicate with the base station. The path setting method according to any one of claims 1 to 4, wherein the antenna communicates with a nearby mobile device using an antenna having no directivity, and relays radio waves. 6. A path setting method between a mobile station and a radio base station in a digital cellular system using a CDMA system, wherein a radio repeater is interposed between the radio base stations.
Compare the traffic volume of each radio base station, the received electric field strength of each radio base station, the error rate of the radio transmission path between the mobile station and the radio base station, and the error rate of the radio transmission path between the mobile station and the radio repeater. When the traffic is concentrated in a concentrated manner, a path is established between the mobile unit of the radio base station having a high traffic and the adjacent radio base station having a low traffic through the radio repeater. A path setting method between a mobile station and a radio base station, characterized in that the electric field strength at the base station is reduced.