JPH01206735A - Radio communication system - Google Patents

Abstract

PURPOSE:To continue satisfactory communication by supervising a burst signal from a subscriber in a radio base station while the radio base station and subscriber execute the communication and switching the transmission with another radio station according to an instruction from the radio base station when the level of the burst signal goes under a prescribed value. CONSTITUTION:A subscriber 1 executes the communication with a radio base station 8 by a radio line termination device 3, a transmitter and receiver 4 and a transmitting and receiving antenna 6 to be selected by an antenna switching device 5. The radio base station 8 executes the communication with using a 90 deg. sector-form beam antenna 9, a transmitting and receiving device 10 and a radio line termination device 11 and a line is connected through a network connecting device 12 to a network node 19 and the connection with an adjacent radio station 15 is executed with correcting 13 and 14 delay. During the communication, the radio base station 8 supervises 11 the burst signal from the subscriber 1 and when the signal goes under the prescribed level due to a rainfall, etc., the radio base station 8 gives the instruction to the subscriber 1 and an antenna is switched to an antenna 7. Then, the communication with the radio base station 15 is executed. Thus, a satisfactory communicating condition is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wireless communication system for realizing highly reliable lines in a wireless section of a subscriber wireless communication system.

[Conventional technology]

For an overview of the subscriber wireless communication system, which is the target field of the present invention, see, for example, the reference document Digital Subscriber Wireless System -26SS-D1 System~
Written by Akiaki Kichi 11 and Kazunori Tanaka NTT Facility 37-1. 1) I) 92-98 1
．． 985".

], OG +- (In subscriber wireless communication systems that use frequencies of 7 or higher, rain or the like causes attenuation of radio waves and deterioration of line quality.

In the conventional subscriber wireless communication system, as shown in Fig. 4, the wireless base station connected to each subscriber a, b--j is always the same wireless base station A or I3, and the The wireless line with the wireless base station is connected to each subscriber a, b - j.
There was only one tree per tree per year.

[Problem to be solved by the invention]

As mentioned above, in the past, each subscriber had only one wireless line, and as a result, if rain or other factors caused radio wave attenuation, the received field strength decreased and the wireless link became disconnected. However, there was a problem that individual subscribers would be unable to communicate and there would be no way to remedy the situation.

The wireless communication system of the present invention attempts to solve such conventional problems by changing the wireless base station to be connected when a wireless section is interrupted due to rain or the like.

[Means to solve the problem]

In the wireless communication system of the present invention, a plurality of subscriber equipment is connected to a wireless base station through a bidirectional communication line, and the wireless base station sends continuous signals to each subscriber, and each subscriber receives a time slot.

) In a time division multiple access communication system that sends out burst signals using The first and second wireless base stations are connected to each other by a wired or wireless transmission path, and a delay correction device is built in between the first and second wireless base stations. A network connection device with the function of connecting the first and second wireless base stations to the network nodes is installed at A dedicated antenna corresponding to each wireless base station and an antenna switching device that has the function of switching the antenna according to instructions from the first and second wireless base stations are installed, and a subscriber or time division multiplex access interface is installed. When connected to the first wireless base station and communicating, the first wireless base station monitors the reception level of the no-stop signal from the subscriber, and if it exceeds the specified level, After the burst signal is terminated by the wireless line termination device, the delay time is adjusted by the network connection device and connected to the network node, and radio wave attenuation due to rain occurs between the first wireless base station and the subscriber. When a drop in the reception level of the burst signal from the first wireless base station or the subscriber is detected, the wireless base station to be connected is switched to the second wireless base station according to an instruction from the subscriber or the first wireless base station. station, communicate with the second wireless base station, adjust the delay time using the Tburst connection device from the subscriber at the second wireless base station, and connect to the network notebook. It is characterized by

[Function] In the wireless communication system of the present invention, the wireless base station detects a decrease in the received electric field strength when radio waves are attenuated due to rain etc. between the subscriber and the wireless base station, and the received electric field strength is adjusted accordingly. When a drop in the wireless base station is detected, the subscriber's connection destination is changed to another wireless base station and communication is continued. This method differs from the conventional technology in that the number of wireless base stations connected to a subscriber is not limited to one, but the wireless base station to which the subscriber is connected is changed depending on the situation of the wireless section.

〔Example〕

FIG. 2 is a diagram showing the concept of the present invention, in which A is a first radio base station, B is a second radio base station, and a.

b, . . . , e are subscribers connected to the first radio base station, and r, g, -, j are subscribers connected to the second radio base station B.

The subscriber wireless communication system is designed with a large margin against rain, so if it is not raining, communications from subscribers outside the service area indicated by the circles in Figure 2 are possible. be. Therefore, for example, the first
A subscriber a connected to a normal radio base station A can also communicate with a second radio base station B.

Therefore, in the present invention, when rain occurs in the area between subscriber a and the first wireless base station A, the first wireless base station A lowers the reception level of the berth I signal from subscriber a. When the decrease is detected, the first radio base station A sends an antenna switching signal to the subscriber a, and the subscriber a switches the antenna to communicate with the second radio base station B.

FIG. 1 is a diagram showing an embodiment of the present invention, and 1 is a subscriber. In this subscriber 1, 2 is a terminal device, 3 is a terminating device, 4 is a transmitting/receiving device, 5 is an antenna switching device, and 6 is a terminal device.
, 7 is an antenna. The antenna switching device 5 switches the subscriber antenna 6.7 using a switch using, for example, a PIN diode. 8 is a first radio base station, and 15 is a second radio base station. In the first radio base station 8, 9 is a 90 degree fan beam antenna;
11 is a transmitting/receiving device, 11 is a wireless line termination device for a wireless base station,
12 is a network connection device with a built-in delay correction device, 13.14
is a delay correction device. Further, in the second wireless base station 15, 16 is a 90 degree fan beam antenna, 17 is a base station transmitting/receiving device, and -7=18 is a base station wireless line termination device. Further, 19 is a network node (dedicated line, public network).

Subscriber 1 is usually accommodated in radio base station 8 of tube 1 . The radio base stations 8, 15 continuously transmit signals to each subscriber. Each subscriber transmits a burst signal to the radio base station 8.15 in a determined time slot, and at that time, a subscriber identification code is inserted into a part of the burst signal. The wireless base stations 8 and 15 monitor the reception level of burst signals from each subscriber, and determine whether the subscriber is a subscriber accommodated in their own station based on the subscriber identification code.

Now, subscriber l uses antenna 6 to connect to first wireless base station 8.
Suppose that a burst signal is being sent to. If the received field strength at the first wireless base station 8 is equal to or higher than the minimum level that guarantees line quality, the signal is terminated at the wireless base station wireless line termination device 11, and the subscriber 1 returns to the first wireless base station. If it is determined that the subscriber is accommodated in network connection device 8, the signal enters delay correction device 13 in network connection device 12. The amount of delay time given by the delay correction device 13 is such that when the subscriber 1 is connected to the second wireless base station 15, the signal is transmitted from the subscriber 1 to the first wireless base station 15 via the second wireless base station 15. From the time required for propagation to the radio base station 8, if the subscriber 1 is connected to the first radio base station 8, the signal will be transmitted to the subscriber 1.
It is obtained by subtracting the time required for propagation to the first radio base station 8 from the delay time, and is calculated in advance and given to the delay correction device 13. Signals leaving the network connection device 12 enter the network nodes.

When rain occurs in the area between the first wireless base station 8 and subscriber 1, and the radio waves are attenuated, the first wireless base station 8
Detects a drop in the reception level of burst signals from. When the reception level falls below the minimum level that guarantees line quality, the first radio base station 8 sends an antenna switching signal to the subscriber 1, and at the same time sends an antenna switching signal to the second radio base station 15 when the subscriber 1 It sends a signal to the second wireless base station 15 indicating that it will be connected. Upon receiving the antenna switching request from the first radio base station 8, the subscriber 1 switches the antenna from 6 to 7 using the antenna switching device 5 using a PIN tie auto switch, for example, and switches the antenna to the second antenna. wireless base station 15
Receive signals from. The second radio base station 15 allocates to the subscriber 1 a time slot in a TDMA (time division multiple access) interface between the other station 15 and the subscriber 1, and transmits a burst signal toward the second radio base station 15 in the designated tight slot.The second radio base station 15, which has received the burst signal from the subscriber 1, transmits the burst signal to the first radio base station 8.
A reception confirmation signal is sent to.

The burst signal from the subscriber 1 received by the second radio base station 15 is terminated by the radio line termination device 18 for the radio base station, and the burst signal is terminated by the wired or The signal passes through a wireless transmission path and enters the delay correction device 14 in the network connection device 12 of the first wireless base station 8, and after the delay time is corrected, it enters the software node 19.

By using this method, if the transmission path condition between the first radio base station 8 and the subscriber 1 deteriorates, the subscriber 1 changes the connection to another second radio base station 15, It is possible to continue communication.

Of course, the number of wireless base stations that are switched and connected to the subscriber 1 is not limited to only two, the first and second wireless base stations 8 and 15, and may be three or more. good. The first and second radio base stations 8 and 15 are used solely for convenience of explanation.

Note that when there are multiple wireless base stations, the method of configuring the transmission path between the wireless base station and the network node is as shown in Figure 1. How to connect to another wireless base station and connect to the work notebook via the wireless base station.
Alternatively, as shown in FIG. 2, a common network notebook is used for each wireless base station Δ and B. FIG. 3 is an example of the results of implementing the present invention, and is the result of an mul-ray computation performed by a computer. The horizontal axis is the frequency, and the vertical axis is the number of rainfalls that cause line failures when approximately 1,000 rainfalls occur for each of 100 subscribers within a circular service area with a radius of 7km centered on the wireless base station. It shows. In the same figure, (a
) is the case when the conventional method without line switching is used, and (b) is the case when line switching is performed according to the method of the present invention.If the radio section is changed by antenna switching during rain at each frequency, the line can be changed. It is clear that high reliability can be achieved.

[Effects of the Invention] As explained above, the wireless communication system of the present invention is designed to reduce the decrease in received field strength when radio waves are attenuated due to rain etc. between a subscriber and a wireless base station. When the station detects a drop in the received field strength, it changes the subscriber's connection destination to another wireless base station and continues communication.
It is possible to improve the reliability of the line by relieving deterioration of line quality due to rain or the like and unreliable JIT-+ signals.

[Brief explanation of the drawing]

FIG. 1 shows a system for explaining one embodiment of the present invention.
FIG. 2 is a conceptual diagram of the present invention, and FIG. 3 is a diagram for explaining the present invention in detail. FIG. 4 is a conceptual diagram of a conventional subscriber wireless communication system. 1. Subscriber, 2. Terminal device, 3. Radio line termination device for subscriber, 4. Transmission/reception device for subscriber, 5. Antenna switching device, 6, 7 Cassegrain antenna, 8, 15 Radio base station, 9 , 16... 90fffi fan beam antenna, 1
0, 1.7 Base station transmitting/receiving device, 1, 1. , 18
・・Radio line termination device for base station, 12 Network connection device, 1, 3, 1.4 Delay correction device, 19... ・Network Note applicant To Hon Telegraph and Telephone Co., Ltd.

Claims (1)

[Claims] A plurality of subscriber facilities are connected to a radio base station by a two-way communication line, and the radio base station transmits a continuous signal to each subscriber, and each subscriber uses a time slot. In a time division multiple access communication system that sends out burst signals, the first and second wireless base stations are equipped with transmitting/receiving equipment and wireless line termination equipment to monitor the reception level of burst signals from each subscriber. The first and second wireless base stations are connected to each other by a wired or wireless transmission path, and a delay correction device is built in between the first and second wireless base stations. A network connection device with the function of connecting the second wireless base station to the network node is installed, and each subscriber equipment includes a terminal device, a wireless line termination device, a transmitting/receiving device, and a network connection device for connecting the first and second wireless base stations. A dedicated antenna corresponding to each base station and an antenna switching device having a function of switching the antenna according to instructions from the first and second wireless base stations are installed, and the subscriber can connect to the first wireless base station using a time division multiplex access interface. When connected to a base station and communicating, the first wireless base station monitors the reception level of burst signals from the subscriber, and if it is above a specified level, the burst signal is terminated at the wireless line termination device. After that, the network connection device adjusts the delay time and connects to the network node, and if radio waves are attenuated due to rain between the first wireless base station and the subscriber, the first wireless base station is connected to the network node. When the subscriber detects a decrease in the reception level of the burst signal, the subscriber changes the wireless base station to be connected to the second wireless base station according to instructions from the first wireless base station, and connects to the second wireless base station. and after terminating the burst signal from the subscriber at the second wireless base station with a wireless line termination device, the network connection device adjusts the delay time and connects to the network node. Characteristic wireless communication method.