JPH0213971B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a base station diversity receiving apparatus used for wireless communication, particularly mobile communication, which performs communication via a base station.

1. Configuration of a conventional example and its problems FIG. 1 shows the configuration of a receiving apparatus using a sector reception method used in conventional mobile communications. The configuration of a conventional example will be explained below with reference to FIG.

In FIG. 1, C indicates the standard service area of a wireless cell, and the radio waves transmitted by the base station provide the required reception level for communication to mobile stations within this range. The base station transmitter output can be freely selected from several watts to several 100 watts, but
Since it is practical for the transmission output of a mobile station, especially a portable radio, to be 1 W or less, there is a large difference in S/N between uplink and downlink. To remedy this, the base receiving antenna is given directivity, which narrows down the horizontal and vertical planes to reduce the effects of urban noise and balance the call quality of upstream and downstream lines. In addition, a radio cell is divided into a plurality of sectors using directional antennas, and a receiver is connected to each antenna to perform diversity reception, thereby improving call quality (S/N ratio).

In Figure 1, S ₁ to S ₃ are sectors formed by directional antennas (A ₁ to _{A 3} ), ML is a mobile station, and a ₁ to a ₃ are antennas (A ₁ to _{A 3} ) and an antenna switcher. The high frequency cable that connects the AS is shown here with the receiver duplexer and distributor omitted to avoid complication. RX ₁ and RX ₂ are base diversity receivers, DV is a voting device, AS is an antenna switcher, i ₁ and i ₂ are inputs of receivers RX ₁ and RX ₂ , V ₁ ,
V ₂ is the audio output terminal of the receivers RX ₁ and RX ₂ , I ₁ and I ₂ are the output terminals of the reception level display signal, and V ₀ is the audio output terminal of the voting device DV.

Sector S ₁ with directional antennas (A ₁ ~ A ₃ )
The shape of ~S ₃ is expressed as a geometric rhombus, but each sector has an overlapping area, and the base station receive diversity is Although there is an S/N improvement effect, the S/N improvement effect due to diversity is not so noticeable in front of the antenna, and the S/N improvement is mainly due to reduction of urban noise due to antenna directivity.

Portable wireless devices (hereinafter referred to as mobile stations) have low transmission output and antenna gain for use in vehicles, and are subject to even greater attenuation in buildings due to their propagation characteristics, so measures are needed to alleviate these losses. .

Purpose of the Invention The present invention eliminates the problems of the conventional example and provides sufficient S/N even in the front direction of the base station directional antenna.
It is an object of the present invention to provide an improved diversity system to extend the communication range of a mobile station, which has severe usage conditions, to the inside of a building at an apogee.

Composition of the Invention In order to achieve the above object, the present invention installs sector antennas with different antenna heights above or below to overlap the conventional sector antenna, thereby utilizing both angle and space diversity. This improves the S/N improvement effect in the front direction of the antenna, and provides a mobile station with the effect of securing a communication range to almost the same area as a vehicle-mounted station that does not use diversity reception.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In Fig. 2, 1, 2, and 3 are diversity radio receivers (hereinafter referred to as receivers);
1, 21, and 31 are instantaneous level signals of reception input (hereinafter referred to as instantaneous level); 12, 22, and 32 are signal and audio output terminals of receivers 1, 2, and 3; 4 is a reception mode controller; A time average value is obtained from the level signal, the order of the input level of each antenna and whether or not it is higher than the required input level P _th are determined, and the antenna changeover switch is controlled according to the flow described later. 5 is an antenna changeover switch, 51 is a switch control section, 52 is a high frequency switch section, and 6 is an instantaneous level comparator.Here, the receiver with the highest input is selected and the information is given from 61 to the voting section 7 to determine the reception output. The switch is being made. The diversity device formed by the above devices selects an antenna based on the average value of the received input, and switches the received output based on the instantaneous level of the received input. Each of the three directional antennas is provided separately into an upper antenna 8 and a lower antenna 9, and the two sets of antennas are appropriately separated vertically and installed so that they operate as independent antennas. It is known that if the antennas are separated from each other by 2λ or more, there will be almost no interference with each other, and the correlation between reception levels will be small. A _T is a high-gain omnidirectional antenna for base station transmission, and is used for downlink communication from the base station to the mobile station.
It covers the entire area of sectors S ₁ , S ₂ and S ₃ .

Next, standby mode, diversity reception mode,
and antenna switching mode will be explained.

(A) Standby reception mode Figure 3A shows the connection method between each receiver and each antenna during standby reception. (a) In mode I, receiver 1 is connected to upper antenna A ₁ , receiver 2 is connected to antenna A ₂ , and receiver 3 is connected to antenna A ₃ , and it waits for reception input from wireless cells and all directions. ing. (b) In mode (), receiver 1 is
A ₁ , receiver 2 is A ₂ , receiver 3 is A ₃ , in (c) mode (), receiver 3 is A ₁ , receiver 1 is A ₂ ,
Receiver 2 is connected to _A3 . This may be fixed to one of (a) mode (I) to (c) mode (), but the combination of the above facilitates the isolation and discovery of receiver and antenna faults. . Further, a mode similar to the above may be additionally set for the lower antenna.

(B) Diversity reception mode Figure 3B shows a state of transition from standby reception to diversity reception. First, when receiving in standby mode in mode d, if information such that the reception input order is e is given, the reception input P _r is the antenna with the maximum reception input of the third receiver 1.
Switch to the lower antenna A ₂ ' of A ₂ and fix the three receivers 1, 2, and 3 to those antennas when the reception input Pr and required value P _th are Pr > P th to perform diversity reception. .

(C) Antenna switching mode In Fig. 3C, g connects receivers 1, 2, and 3 to antennas A ₂ , A ₃ , and A ₂ ', and during diversity reception, the reception level of antenna A ₃ is set to the required value Pth. The reduced state is shown below. On the other hand, the receiver 3 switches the antennas in the order of g', compares the reception levels, determines the antenna with the highest level, and determines that the level is the required value Pth.
Check whether the above is true or not. In this case, it is known that the antenna input is less than Pth, and the receiver 3 performs antenna switching until the reception input Pr becomes Pr>Pth. Of course, the designer can arbitrarily select, for example, searching several times and then performing further antenna searches at appropriate time intervals when the reception input is low. Further, at this time, the two receivers 2 and 1 are connected to the antennas A ₂ and A ₂ ' to perform diversity reception. Although an example has been described in which the antennas are switched while avoiding the antennas that are being used for diversity reception, it is possible to detect whether the receiver 3 is good or bad if the antennas are switched including those antennas.

At i in FIG. 3C, the receiver 3 checks and receives four antennas A ₁ , A ₃ ′, A ₁ ′, A ₃ ,
The antenna switching method is shown when all antenna inputs are sufficiently high as a result of checking whether the reception level is greater than or equal to the required value P _th . Antenna A ₂ by i
When it is determined that the antenna A 3 is the maximum, the receiver 3 switches the antenna A ₃ to A ₁ to perform diversity reception using three receivers.

FIG. 3D shows diversity reception in which receivers 2, 3, and 1 are connected to antennas A ₂ , A ₃ , and A ₂ '. Here, the reception input P _r of receivers 2, 3, and 1
The level ranking of A ₂ ′ is 1′, so the level of 1 is
Pr indicates a state of Pr<Pth. case m
Now, set receiver 1 to the antenna with the highest reception level.
Change the connection of A ₃ to the lower antenna A ₃ ′. In this case, the situation results of cases m' and m'' will be given, and in case n, the receiver 2 will move to antenna search according to the given timing and select the antennas A ₁ , A ₂ ′, A ₁ ′ , A ₂ to determine the order of reception levels. In case P, reception level Pr is greater than or equal to the required value Pth,
The antenna order is A ₁ , A _{1 ′} , A 2 , A 1 ′, A ₂ , depending on case P′.
This shows that A ₂ ′. In case P'', the receiver ₃ connected to the antenna A3 is switched to the antenna _A1 , and diversity reception is performed.

Generally, the higher the antenna installation location, the higher the average reception level of the receiving antenna, so during standby, three receivers are connected to the upper antenna A ₁ ,
The lower antenna of the antenna that connects to A ₂ , A ₃ and stands by, indicating its highest level (A ₃ ′ in this case)
The receiver with the lowest reception level (1 in this case) is connected to the receiver.

To summarize the above, during standby, three receivers are connected to the three antennas on the top to perform standby reception, detect the reception level, rank it,
Angle and space diversity reception is achieved by keeping the receiver with the highest reception level and the second receiver and antenna fixed, and changing the connection of the receiver with the lowest reception level to the lower antenna of the antenna with the highest reception level. This is what we do.

Also, at this time, using the receiver with the second highest reception level, switch the unused antennas in a predetermined order to receive reception, compare the reception levels, and select the second antenna with the highest reception level. The receivers are connected to perform diversity reception using three receivers.

Effects of the Invention The present invention has the above-described configuration, and provides the following effects.

(a) A wireless cell is connected by three 120° directional antennas.
Since reception is divided into three sectors and diversity reception is performed, an improvement in S/N corresponding to antenna gain and an improvement due to the space diversity effect of the upper and lower antennas can be obtained, and this improvement gain is due to the difference between base transmission and mobile station. Since it sufficiently compensates for small power consumption, low antenna gain, and propagation loss inside buildings, it has the advantage of ensuring communication both in mobile stations and within the service area of conventional vehicle-mounted stations.

(b) Since three receivers are connected to three upper antennas for standby reception, it is possible to instantly determine the main communication antenna even when a call is made from a station with low transmission power such as a mobile station, which is different from the conventional reception method. It is superior to .

(c) After selecting the highest receiving antenna as the upper antenna, sufficient diversity reception is possible by connecting the lowest level receiver to the lower antenna directly below the antenna, and the logic is simple.

(d) If the input of a particular antenna decreases during diversity reception, simply switch said receiver to the antenna directly below or directly above the higher input of the other two receivers when it is not in use. All you need to do is use a program that
It has the advantage of easy switching operation and short switching time.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional diversity receiving device with three antennas and two receivers, FIGS. Figures A to D are diagrams showing a procedure for switching between an antenna and a receiver. 1, 2, 3...Receiver, 4...Receiving mode controller, 5...Antenna switching device, 6...Momentary level comparator, 7...Boating section, 8...Upper antenna
A ₁ , A ₂ , A ₃ , 9...lower antenna A ₁ ′, A ₂ ′,
A ₃ ′, 10...Transmission antenna, P...Mobile station.

[Claims]

1. A first directional antenna group used in a mobile communication or rural communication base station having a communication area represented by an omnidirectional antenna, and for dividing the communication area into three or more fan-shaped areas for reception;
Provided above or below this first directional antenna group, with the same number as the first directional antenna group,
and a second directional antenna group whose main directional direction is different from the main directional direction of each antenna of the first directional antenna group, and three antennas per communication channel.
a wireless receiver that outputs a reception level signal and a demodulated signal, respectively, and an antenna switch circuit that can connect and switch the three wireless receivers to each antenna of the first and second directional antenna groups. Then, during standby, the three wireless receivers are connected to one set of the directional antenna group, and the three wireless receivers and the two sets of directional antennas are connected based on the determination result of the reception level information. an antenna switching control unit that connects the group of antennas according to a predetermined law;
Based on the reception level signals of the three radio receivers above.

Claims (1)

Two receivers are connected to the antenna direction with the highest reception level, and while selecting and receiving the reception output, the remaining receiver measures the reception level of each antenna in the other direction, and the reception input is higher than before the measurement. If there is an antenna, connect the receiver to that antenna, and from then on, control the output of the three receivers to be selectively output. Three antennas with horizontal directionality are made into one set. Two antenna groups, three receivers, an antenna switching controller that switches and connects the antenna output to the three receivers, and an instantaneous value comparator that compares the instantaneous reception levels of each of the three receivers. , a voting section that selects and outputs the receiver output with the highest reception level using the instantaneous value comparator, and a reception mode controller that sends information to the antenna switching controller according to the reception level. Device.