JPH0652885B2 - Wireless relay system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wireless relay system for a weak electric field area rescue agent in mobile communication according to the present invention.

(2) Conventional technology and its problems In mobile communication systems that provide large-capacity and wide-area services such as car phones, due to reasons such as reduction of mobile station transmission output and effective use of frequencies, As shown in FIG. 1, the service area 1 is divided into a plurality of wireless zones 2, 3, 4 and the like, and wireless bases in which wireless frequencies 5, 6, and 7 of different frequencies are assigned to the respective wireless zones. Station 8,
9 and 10 are installed. Each wireless base station has a wired line 11
Is connected to the control station 12 via the wired circuit 11, and the control station 12 controls the lines such as 8, 9 and 10 connected via the wired circuit 11.

When the mobile station 13 shifts the wireless zone during a call, it is necessary to determine the shift zone and switch the wireless channel in order to continue the call, which is generally called in-call channel switching. In the case of FIG. 1, the mobile station 13 is in the wireless zone 2 and is moving in the direction of the wireless zone 3. When the mobile station 13 crosses the zone boundary, the reception level of the radio frequency 5 from the mobile station 13 at the radio base station 8 decreases and falls below the specified value. The radio base station 8 notifies the control station 12 of the decrease in the level of the radio frequency 5. The control station 12 instructs the surrounding radio base stations to monitor the level of the radio frequency 5. Each radio base station reports the radio frequency 5 level to the control station 12. First
In the case of the figure, the reception level of the radio frequency 5 in the radio base station 9 is the highest, and the radio base station 8 instructs the mobile station 13 to switch the radio frequency to the radio frequency 6 by the command of the control station 12. Instruct. At the same time when the mobile station 13 switches the channel to the radio frequency 6 and the radio base station 9 starts to use the radio frequency 6, the control station 12 is connected to the radio frequency 5 through the wired line.
Switch 11 to a wired line 11 corresponding to radio frequency 6. As described above, a new wireless line is set up between the mobile station 13 and the wireless base station 9, and the corresponding wired line is connected to the communication partner at the control station 12, and the mobile station 13 continues the call. .

By the way, in mobile communication, a weak electric field region in which radio waves from a radio base station are hard to reach occurs due to the influence of features such as tunnels and buildings even within the service area. Conventionally, a method as shown in FIG. 2 has been taken as a measure for relieving the weak electric field region. That is, the wireless relay station 14 is provided between the wireless base station 8 and the mobile station 13.
Is provided to relieve the weak electric field region 15 generated in the wireless zone 2 of the wireless base station 8. Radio waves radiated from the radio base station 8 (hereinafter referred to as downlink radio waves) are received by the base station antenna 16 of the radio relay station 14, amplified by the radio repeater 17 to a required level, and then transmitted by the mobile station antenna 18. It is radiated toward the mobile station 13. On the other hand, the radio waves radiated from the mobile station 13 (hereinafter,
Uplink radio wave) is received by the mobile station antenna 18,
Similarly to the downlink radio wave, it is radiated toward the radio base station 8 through the radio repeater 17 and the antenna 16. In this way, the wireless zone 2 of the wireless base station 8 is expanded to the weak electric field region 15, the wireless link between the wireless base station 8 and the mobile station 13 is maintained, and the mobile station 13 is weak in the weak electric field region 15. It is possible to continue the call even if the call comes in and out, and even if the user enters the weak electric field region 15 during the call.

Now, the above-mentioned measures for relieving the weak electric field region have been conventionally applied when the weak electric field region 15 is included in one wireless zone as shown in FIG. In this case, even if the mobile station 13 goes out of the weak electric field area 15 during a call, the call can be continued because the outside is within the wireless zone 2 of the wireless base station 8. However, when the weak electric field region 15 exists across a plurality of wireless zones and the entrance / exit of the weak electric field region 15 is covered by the plurality of wireless zones, the mobile station 13 remains in the talking state and the weak electric field region 15 remains. From the outside or inside the weak electric field area 15 during a call,
It may not be possible to continue the call.

As shown in FIG. 3, one entrance of the weak electric field region 15 exists in the wireless zone 2 of the wireless base station 8 and the other entrance exists in the wireless zone 3 of the wireless base station 9, and the wireless zones 2 and 3 are connected. Cover only one of the entrances and exits of the weak electric field area 15, and the antenna 16 to the base station of the radio relay station 14 has directivity in the direction of the radio base station 8 and only the radio frequency 5 enters the weak electric field area 15. When amplified and relayed, the mobile station 13 enters the weak electric field region 15 from the entrance / exit of the radio base station 8 side during a call using the radio frequency 5 in the radio zone 2, and the radio base station 9 side remains in the call state. When the mobile station 13 exits from the doorway of the wireless base station 9 or goes out from the doorway of the wireless base station 9 side while keeping the call state while making a call in and out of the weak electric field area 15 and grabbing the radio frequency 5. Until reaching the entrance / exit on the station 9 side The reception signal level of the waves 5 good communication is performed at a specified value or higher, a radio frequency 5 amplified relayed by radio repeater 14 when the mobile station 13 leaves the weak electric field region 15
However, since the radio frequency 5 radiated from the radio base station 8 does not reach outside the entrance on the radio base station 9 side, the reception signal level of the radio frequency 5 at the radio base station 8 Below the specified value, radio frequency 5
Report a decrease in the level of. According to the in-call channel switching control procedure, the radio base station 8 instructs the mobile station 13 to switch to the radio frequency 6 by the radio frequency 5. Weak electric field region 15
If there is a tunnel, underground mall, underground parking lot, etc., wireless repeater
The radio frequency 5 amplified and relayed at 14 is rapidly attenuated outside the weak electric field region 15. In such a case, before the channel switching command signal from the wireless base station 8 reaches the mobile station 13, the radio frequency 5 becomes too weak to be received by the mobile station 13, and the channel switching is not performed and the call is continued. Cannot be done. In addition, when the mobile station 13 is in the radio zone 3, the radio frequency 6
When entering the weak electric field region 15 from the doorway on the side of the wireless base station 9 during a call using, the radio frequency 6 is not amplified and relayed in the weak electric field region 15, so the channel cannot be switched during the call. , I still can't continue the call.

As shown in FIGS. 4 (a) and (b), the entrance / exit of the weak electric field area 15 is entirely included in the wireless zone 2, but the wireless zone 3 is also included in the weak electric field area.
When 15 is included in its own zone or covers only the vicinity of the entrance / exit of the wireless base station 9, the directivity of the antenna 16 to the base station of the wireless relay station 14 is in the direction of the wireless base station 8 and only the radio frequency 5 is present. Is amplified and relayed to the weak electric field region 15, when the mobile station 13 moves from the wireless zone 2 to the wireless zone 3 through the weak electric field region 15 during a call by the radio frequency 5, the wireless base station 9 side Even if the user goes out of the weak electric field area 15 through the doorway, the wireless zone 2 of the wireless base station 8 extends to the outside so that the call can be continued, but the mobile station 13 is weak in the call by the radio frequency 6 in the wireless zone 3. When entering the electric field region 15 and proceeding toward the entrance / exit direction on the radio base station 8 side, since the radio frequency 6 is not amplified and relayed in the weak electric field region 15, channel switching cannot be performed during a call, and a call is not made. I can't continue.

As described above, in the conventional weak electric field region relief measures, when the weak electric field region exists over a plurality of wireless zones and the entrance / exit of the weak electric field region is covered by the plural wireless zones, the mobile station There is a drawback that if the call goes out of the weak electric field area in the call state or enters the weak electric field area during the call, the call cannot be continued.

(3) Object of the invention The object of the present invention is to use a wireless relay station to provide a weak electric field region across a plurality of wireless zones, and the electric field region has a plurality of wireless access points. When covered by a zone, when the mobile station leaves the weak electric field area while in a call or enters the weak electric field area during a call,
It is an object of the present invention to provide a wireless relay system that can solve the problem that a call cannot be continued without switching the channel during a call.

(4) Configuration of the invention (4-1) Differences between the features of the invention and the prior art The present invention is based on the fact that each entrance / exit of a weak electric field region in which the entrance / exit is covered by a plurality of radio zones is wirelessly associated with each radio zone. A relay station is installed, and the mobile station antennas of each wireless relay station are simultaneously installed in the weak electric field area to form a plurality of wireless zones in the weak electric field area, and a plurality of wireless zones are formed in the weak electric field area. By setting the electric field level at the portion where the wireless zones of (1) overlap each other to the wireless channel switching level, the wireless channel switching is performed within the weak electric field region.

Conventionally, even if the entrance / exit of the weak electric field area is covered with multiple wireless zones, a wireless relay station is installed in one of the entrances / exits,
Only the radio waves of one radio zone covering the doorway were amplified and relayed to the weak electric field.

(4-2) Example FIGS. 5 to 7 are views for explaining an example of the present invention.

[Embodiment-1] In FIG. 5, 1 to 18 are the same as those in FIG. Reference numeral 19 denotes a wireless relay station provided at the entrance of the weak electric field region 15 on the side of the wireless base station 9 and has a radio frequency 6 of the wireless base station 9.
Is amplified and relayed to the weak electric field region 15. Reference numeral 20 denotes an antenna for the base station, which has directivity in the direction of the radio base station 9. Reference numeral 21 is a wireless relay station, and 22 is a mobile station antenna of the wireless relay station 19.
Linear antennas such as the Yagi antenna are used for the mobile station antennas 18 and 22. Radio frequencies 5 and 6 are amplified and relayed in the weak electric field region 15 by radio relays 17 and 19.
The radio frequency 5 attenuates as it goes from the entrance on the side of the radio base station 8 to the entrance on the side of the radio base station 9. On the other hand, the radio frequency 6 is attenuated as it goes from the entrance on the side of the radio base station 9 to the entrance on the side of the radio base station 8. Here, the amplification gains of the wireless repeaters 17 and 21 are set so that the electric field level of the radio frequencies 5 and 6 in the weak electric field region 15 becomes the channel switching level in the vicinity C of the center of the weak electric field region 15. The electric field level of the radio frequency 5 is below the channel switching level, and the electric field level of the radio frequency 6 is above the channel switching level on the entrance / exit side from the center C of the weak electric field region 15 to the radio base station 9. The opposite is true on the entrance / exit side of the wireless base station 8 from the vicinity of the center of the weak electric field region 15. By doing this,
When the mobile station 13 in a call using the radio frequency 5 in the radio zone 2 moves to the radio zone 3 through the weak electric field region 15, the radio base station 8 of the radio frequency 5 in the vicinity C of the weak electric field region 15 , The radio base station 8 notifies the control station 12 that the radio frequency 5 is low. The control station 12 instructs the surrounding radio base stations to monitor the level of the radio frequency 5, but the radio frequency 5 reported to the control station 12
Since the reception level at the radio base station 9 is the highest, the mobile station 13 switches to the radio frequency 6 by the channel switching command sent from the radio base station 8 through the radio frequency 5, and the call of the mobile station 13 continues. To be done. Similarly,
The mobile station 13 that has entered the weak electric field region 15 during a call from the wireless zone 3 using the radio frequency 6 switches to the radio frequency 5 inside the weak electric field region 15 and goes out to the radio zone 2. The mobile station
When 13 makes a call after entering the weak electric field area 15 instead of entering the weak electric field area 15 during a call, the call is started by using either radio frequency 5 or 6, whichever has a higher electric field level, and uses it. When going to the entrance on the opposite side of the inside radio frequency zone, the channel is switched during the call and the weak electric field area 15
Go out more.

Example-2 In Example-1 of FIG. 5, a linear antenna such as a Yagi antenna was used as the antenna for the mobile station, but in the present example shown in FIG. 6, a leaky coaxial cable is used as the antenna for the mobile station. Use an antenna that has both an antenna and a power supply line, such as a parallel two-wire cable. The mobile station antenna 18 is extended from the entrance / exit of the foot of the radio base station 8 to the entrance / exit of the radio base station 9 side, and the mobile station antenna 22 is extended in the opposite direction along the weak electric field region 15 to form the weak electric field region. Make it overlap at C near the center of 15. The electric field levels of the radio frequencies 5 and 6 amplified and relayed to the weak electric field region 15 through the mobile station antennas 18 and 22 are C near the center of the weak electric field region 15 as in the first embodiment.
The wireless repeater 17 and
Set the amplification gain of 21. The length for duplicating the antennas 18 and 22 for the mobile station may be the distance that the mobile station 13 moves within the time required for the channel switching control. Weak electric field region 15
The switching of channels during a call in a room is performed in the same manner as in the first embodiment.

[Embodiment 3] In the present embodiment shown in FIG. 7, an antenna having both an antenna and a feed line, such as a leaky coaxial cable or a parallel two-wire cable, is used as an antenna for a mobile station. While the mobile station antennas are individually extended from the wireless repeaters 14 and 19 in the weak electric field region 15, the wireless repeaters 14 and 19 are provided.
Commonly used antennas for mobile stations. The electric field levels of the radio frequencies 5 and 6 amplified and relayed to the weak electric field region 15 through the pair of mobile station antennas 18, which are commonly used by the wireless repeaters 14 and 19, are set to the channel switching level near the center of the weak electric field region 15. If the amplification gains of the wireless repeaters 17 and 21 are set, the channel switching during communication in the weak electric field region 15 is performed in the same manner as in the second embodiment.

(5) Effects of the Invention As described above, according to the present invention, a weak electric field region for which a relief measure is applied using a wireless relay station exists across a plurality of wireless zones, and the weak electric field region When an entrance is covered by multiple wireless zones, a wireless relay station is installed near each entrance in the weak electric field area to cover the entrance and exit, and multiple wireless zones are created within the weak electric field area. Since it is configured, the mobile station can continue the call when it enters the weak electric field area during a call, and the electric field level at the portion where the multiple wireless zones configured in the weak electric field area overlap. If the mobile station goes out of the weak electric field area during a call by setting the radio channel switching level to the radio channel switching level within the weak electric field area, the mobile station Zo Since received by always required field intensity radio frequency used in down, there is an advantage that it is possible to continue the call even after leaving the weak electric field region.

[Brief description of drawings]

FIG. 1 is a block diagram of a mobile communication system in which a service area is composed of a plurality of radio zones and radio frequencies of different frequencies are assigned to the respective radio zones, and FIG. Figures and 4 (a) and (b) show the configuration of the conventional weak electric field area countermeasure example when the weak electric field area is covered by a plurality of wireless zones, FIG. 5, FIG. 6 and FIG. It is a block diagram of the system of the present invention, respectively. 1 ... Mobile communication service area, 2, 3, 4 ...
Wireless zones that make up the service area, 5, 6, 7 ...
Radio frequencies assigned to radio zones 2, 3, and 4,
8, 9, 10 ... Wireless base stations that make up the wireless zones 2, 3 and 4, 11 ... Wired lines that connect each wireless base station to the control station, 12 ... Control station, 13 ... Mobile station, 14 ...... Wireless relay station for weak electric field area, 15 ...... Weak electric field area generated in service area of mobile communication system, 16 ...... Antenna for base station of wireless relay station 14, 17 ...... Wireless relay station 14 wireless Repeater, 18 ……
Antenna for mobile station of radio relay station 14, 19 ... radio relay station,
20 ... Antenna for base station of radio relay station 19, 21 ... Radio repeater for radio relay station 19, 22 ... Antenna for mobile station of radio relay station 19.

Claims (1)

[Claims] 1. A service area is divided into a plurality of wireless zones so that wireless channels of different frequencies are used in adjacent wireless zones, a wireless base station is provided in each wireless zone, and a weak electric field region in each wireless zone. Is provided with a wireless relay station, and performs the wireless channel switching control when the received electric field level of the wireless base station in communication by the movement of the mobile station reaches a predetermined wireless channel switching level for communication. In the wireless relay method of mobile wireless communication for continuing the wireless relay station, the wireless relay station is provided corresponding to a wireless zone that covers the weak electric field region, and a relay wireless zone corresponding to a wireless zone is configured in the weak electric field region, and the relay The transmission level of the wireless relay station is set so that the received electric field level at the position where the wireless zones overlap becomes the wireless channel switching level. Wireless relay system, characterized by being.