JPS61139128A - Mobile communication system - Google Patents

Abstract

PURPOSE:To increase the number of channels without increasing the number of base stations by arranging directional antennas, which are directed to individual subregions from positions near a specific point, in the base station and reducing the interference of signals from mobile stations in subregions by interference wave canceling circuits. CONSTITUTION:If the division number of subregions is defined as K, the base station is installed in the center of a region, and K-number of directional antennas are used to perform the communication with mobile stations in semiregions. Each channel is divided to a maximum of K-m-number of parts by a channel signal branching circuit 13, and one of them is supplied to the main signal input of an interference wave canceling circuit 14 for the channel of the pertinent semiregion, and the others are supplied to receiving circuits for the other subregions using the same frequency. The pertinent frequency channel signal from the other subregions using the same frequency is supplied to the interference wave canceling circuit 14 as an auxiliary signal. The interference wave canceling operation is performed automatically in each interference wave canceling circuit 14, and a signal of high SIR obtained as the result is supplied to a demodulating circuit 15, and the signal is reproduced in this circuit 15.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to cellular communication technology (Cel-1
This is called a cellular communication method (hereinafter referred to as a cellular communication method). ) method, that is, a mobile communication method that reuses frequencies through regional division.

[Conventional technology]

Cellular communication systems can reuse frequencies, making it possible to significantly increase channel capacity with a small number of frequencies.
Furthermore, by dividing the area, interference can be reduced to a low level, making high-quality communication possible.

The structure of the area divided by this cellular communication method is explained in the fourth section.
As shown in the figure. The symbols A, B, and C in the figure represent the respective locations.
Indicates the type of frequency used in the area.

In this cellular communication system, as shown in Figure 4, areas are usually divided into honeycomb-like areas, different frequencies are used in adjacent areas to avoid interference, and the same frequency is repeatedly reused in areas that are sufficiently far apart. This allows for a dramatic increase in channel capacity. There is usually a base station in the center of each region, and mobile stations within this region communicate with this base station. A mobile station can communicate with mobile stations in other areas or with general home telephones, etc. via a base station. Furthermore, when a mobile station moves from one area to another, frequency switching is performed according to instructions from the base station, allowing communication to continue.

As described above, cellular communication systems are excellent systems, but when the demand in a particular region increases and the number of channels becomes insufficient, adding new frequencies to that region is difficult due to the limited frequency resources available. This is extremely difficult in relation to neighboring areas. In such cases, the conventional method would divide the area into smaller honeycomb-like sub-regions.

[Problem that the invention seeks to solve]

In the conventional lateral method of creating new honeycomb-like sub-regions, the number of sub-base stations required in each sub-region due to division and the associated increase in complexity of system operation are not enough.
The resulting increase in channel capacity is small. For example, doubling the total number of channels would require at least eight sub-regional divisions.

The present invention solves these problems and aims to provide a mobile communication system divided into sub-regions that allows the number of channels to be increased without increasing the number of base stations.

[Means for solving problems]

The present invention is a mobile communication system in which a communication area is divided into a plurality of honeycomb-shaped areas and a base station is placed in each of the honeycomb-shaped areas. , divided into sub-regions by straight lines connecting a specific point within this region and multiple points on the outer circumference of this region,
The base station is characterized by disposing a directional antenna that points toward each sub-region from the vicinity of the specific point, and reducing signal interference from mobile stations within the sub-region using an interference wave canceling circuit. shall be.

[For production]

The honeycomb-shaped region is divided into sub-regions, and the communication frequency from the mobile station to the base station is reused for every n sub-regions, and the communication frequency from the base station to the mobile station is reused for every 8 sub-regions. Frequency reuse increases the number of available channels by a factor of /(s+m).

The frequency utilization efficiency is improved by reducing the value of m as much as possible, but the mutual interference of harmonics of the base stations associated with this is reduced by the interference wave canceling circuit.

〔Example〕

Hereinafter, an embodiment of the present invention will be explained based on the drawings. Figure 1 is a schematic diagram showing a honeycomb-shaped area divided into sub-regions. FIG. 2 is a block diagram showing the configuration of the base station receiving circuit. FIG. 3 is a block configuration diagram showing the configuration of a base station receiving circuit provided for sub-region support.

First, the divided sub-regions constituting this embodiment will be explained based on FIG. 1.

Assuming that the number of divisions of a sub-region is K, a base station is installed at the center of the region and communicates with mobile stations in the sub-region using directional antennas. Furthermore, frequency reuse is performed for every m sub-regions for communication from mobile stations to base stations, and for every 8 sub-regions for communication from base stations to mobile stations, which reduces the number of channels. /(s+m) times.

In this case, in communication from the base station to the mobile station, the value of S is set as large as possible to prevent interference, and the mobile station also uses a directional antenna to reduce interference. On the other hand, in communication from a mobile station to a base station, the value of m is made as small as possible to improve frequency usage efficiency, and the resulting interference is reduced by an interference wave canceling circuit.

Next, the configuration of the base station receiving circuit used in this embodiment will be explained based on FIGS. 2 and 3.

In FIG. 2, reference numeral 1 receives mobile station signals from each sub-region,
This figure shows a subregional receiving circuit that separates each channel in frequency.

Reference numeral 2 indicates a channel signal branching circuit that branches each channel into a maximum of K/m outputs.

Reference numeral 3 indicates a cable connection circuit. Reference numeral 4 indicates an interference wave cancellation circuit for reducing interference from other sub-regions for each channel.

Next, the configuration of the semi-region corresponding portion of FIG. 2 will be explained based on FIG. 3.

This embodiment circuit includes a received signal branch circuit 11, a frequency separation circuit 12, a channel signal branch circuit 13, an interference wave cancellation circuit 14, and a demodulation circuit 15. A received signal from a mobile station is input, the output of the received signal branch circuit 11 is connected to the input of the corresponding frequency separation circuit 12, and the output of the frequency branch circuit 12 is connected to the input of the corresponding channel signal branch circuit 13. . One output of the channel signal branching circuit 13 is connected to one input of the corresponding interference wave cancellation circuit 14, and the other output of the channel signal branching circuit 12 is connected to one input of the corresponding interference wave canceling circuit 14, and the other output of the channel signal branching circuit 12 is connected to the interference wave canceling circuit of the reference station of another sub-region (not shown). connected to a wave cancellation circuit. The other input of the interference wave canceling circuit 14 is connected to the output of a channel signal branching circuit of a reference station in another sub-region not shown, and the output of the interference wave canceling circuit 14 is connected to the power of the demodulating circuit 15. next,
The operation of this embodiment circuit will be explained based on FIG.

Reference numeral 11 indicates a received signal branching circuit, and reference numeral 12 indicates a frequency separation circuit that selects each channel by frequency separation. Each channel is divided into a maximum of K/m by the channel signal branching circuit 13, one of which is The signal is supplied to the main signal input of the interference wave canceling circuit 14 for the corresponding channel of the corresponding sub-region, and the others are supplied to the receiving circuits for other sub-regions using the same frequency.

On the other hand, a corresponding frequency channel signal is received from another sub-region using the same frequency, and is supplied to the interference wave canceling circuit 14 as an auxiliary signal. Each interference wave canceling circuit 14 is
Interference wave cancellation operation is performed automatically, resulting in high SIR (Signal to Inter-feed)
The signal (Rence Power Ratio) is supplied to the demodulation circuit 15, and this circuit reproduces the signal.

〔Effect of the invention〕

As explained above, the present invention makes it possible to increase the channel capacity of each cell without increasing the number of reference stations.For example, if the base station is also used as an earth station for satellite communication, mobile stations can This has the effect of making it possible to connect not only to domestic telephone lines but also to international telephone lines using satellite communication without having to equip expensive satellite communication equipment.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the structure of a honeycomb-shaped area divided into sub-regions related to the present invention. FIG. 2 is a block configuration diagram showing the configuration of an embodiment base station receiving circuit according to the present invention. FIG. 3 is a block configuration diagram showing the configuration of the sub-region corresponding portion of FIG. 2. FIG. 4 is a schematic diagram showing the structure of a honeycomb-shaped area related to cellular communication systems. 1...Semi-regional reception circuit, 2.13...Channel signal branch circuit, 3...Cable connection circuit, 4.14...
・Interference wave cancellation circuit, 11... Received signal branch circuit, 12
... Frequency separation circuit, 15... Demodulation circuit.

Claims (1)

[Claims] (1) In a mobile communication system in which the communication area is divided into multiple honeycomb-shaped areas and a base station is placed in each of the honeycomb-shaped areas, the honeycomb-shaped areas are defined as specific points within this area and the outer periphery of this area. The sub-regions are divided into sub-regions by straight lines connecting the multiple points above, and the base station is equipped with a directional antenna that directs each of the sub-regions from the vicinity of the specific point. A mobile communication system characterized by reducing signal interference from stations using an interference wave canceling circuit.