KR20000039225A - Base station supporting multi-sectors - Google Patents

Abstract

PURPOSE: A base station supporting multi-sectors is provided to minimize mutual interference between sectors and suitably maintain a handoff area by dividing a cell into six sectors. CONSTITUTION: An internal system of a base station sections a whole service area into six sectors to provide a mobile communication service. Six antennas are connected to the internal system of the base station and transmit radio frequency signal to each sector. The antenna has a beam width of less than 50 degree. A handoff area occupies 30 percent-40 percent of the whole service area of the base station.

Description

Multisector Base Stations

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellular radio telecommunication system. In particular, in a cellular system using code division multiple access (CDMA) technology, a cell is divided into six sectors and intersector-to-sector. A base station supporting multiple sectors, which minimizes interference and maintains a handoff area appropriately.

The cellular mobile communication system divides the entire service area into a plurality of base station areas to form cells, which are small service areas, and centrally controls these base stations with a mobile switching center (MSC). This allows the subscriber to continue the call while moving from cell to cell.

Cellular systems improve the insufficient frequency usage efficiency to be used by more users. The concept introduced to further increase the frequency efficiency is a cell division technique, and one of such cell division techniques is sectorization. The sector-cell divides the cell into three parts by separating the antenna having a beam width of 120 degrees from side to side. Each sector is divided into a unique pilot signal, and the mobile phone uses one sector antenna. Recognize it as a base station.

The mobile phone uses the pilot signal to identify each sector, and if the cellular system receives a new pilot signal from another cell in addition to the pilot signal currently being received by the mobile phone, the handoff function can continue the call. Make sure Therefore, the area where the mobile phone can receive two or more pilot signals is called a handoff area.

When splitting a cell into three sectors using an ideal 120-degree antenna, the capacity of the base station should be increased approximately three times, but the actual antenna pattern is not ideally formed and will interfere with other antennas. Dose increases about 2.5 times. Therefore, the base station supporting the sector-cell structure uses an antenna that can minimize the inter-sector interference and maintain the ratio of the handoff area to the entire service area of the base station at 30% to 40%. Table 1 compares the efficiency of the antennas used for the three sector-cells.

120 degree antenna 95 degree antenna Handoff incidence rate for 20 subscribers 60.9% 42.33% Rpwr (%) 92.44 91.37 Pant 2.77 2.73

In Table 1, Rpwr represents the ratio of the antenna gain within ± 60 range to the total antenna gain, based on the direction of the antenna main lobe, and Pant represents the sum of the gain ratios of the antenna main lobe for three sectors. . Rpwr and Pant are calculated by Equation 1, and FIG. 1 shows power distribution by a 120 degree antenna.

Pant = Rpwr × 3

here P Is the antenna power transmitted at a certain angle P _t Is the total power of the antenna.

As shown in Table 1, since a base station using a 120 degree antenna has a higher handoff incidence than a 95 degree antenna, a three sector base station according to the prior art generally uses a 95 degree antenna. .

However, in case of a base station in a densely populated area, if all available Frequency Assignment (FA) is used or the number of subscribers is further increased, three sectors may not be able to accommodate all subscribers. Therefore, a six-sector base station for providing a service by dividing the entire service area of one base station into six sectors has been created, but the characteristics of the antenna applicable to the six-sector base station are not defined.

In the six-sector base station according to the prior art operating as described above, there is a problem that an antenna capable of reducing interference between six sectors and minimizing a handoff area has not been provided.

Accordingly, an object of the present invention, which is designed to solve the problems of the prior art operating as described above, in a base station supporting six sectors, an antenna having a characteristic of reducing interference between sectors and minimizing a handoff area It is to provide a base station having an antenna for multi-sector with.

Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention and the accompanying drawings.

1 is a power distribution by a conventional 120 degree antenna.

Figure 2 is an embodiment of a base station configuration according to the present invention

3 is a radiation pattern of a six sector antenna;

4 is an antenna pattern of a six sector base station by a 65 degree antenna.

5 is an antenna pattern of a 6 sector base station by a 50 degree antenna.

6 is an antenna pattern of a 6 sector base station by a 40 degree antenna.

<Description of the code | symbol about the principal part of drawing>

10: internal system of the base station 11, 12, 13, 14, 15, 16: sector

1,2,3,4,5,6: Antenna

A preferred embodiment of a base station supporting multiple sectors according to the present invention, which was created to achieve the above object,

A base station internal system which provides a mobile communication service by dividing an entire service area into six sectors;

It is connected to the base station internal system and includes six antennas that transmit radio frequency signals to each sector.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification. Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention.

The present invention consists of a base station that provides mobile communication services to a mobile phone in a cell divided into six sectors, and six antennas that reduce interference between sectors and minimize handoff areas. 2 is a block diagram of a base station according to the present invention. As shown, an internal system 10 of a base station for providing mobile communication service by dividing an entire service area into six sectors; Six antennas (1) (2) (3) (4), which are connected to the internal system of the base station and transmit radio frequency signals to each sector (11) (12) (13) (14) (15) (16) (5) (6), wherein the antenna has a beam width of less than 50 degrees.

The base station internal system 10, which is designed with a six sector structure, converts a baseband voice signal into a plurality of radio frequency signals, and converts the converted radio frequency signals through six paths corresponding to six sectors. (2) (3) (4) (5) (6), and the antenna transmits the received radio frequency signal to each sector (11) (12) (13) (14) (15) (16). do.

Ideally, a six-sector base station should service each sector using a 60-degree antenna, but in practice the antennas interfere with each other and create an affected area, or handoff area, from both antennas, so the handoff area and the antenna An antenna should be selected to optimize the gain ratio (Rpwr) of the main lobe.

In the present invention, the ratio of the handoff area to the entire service area of the base station as a reference for providing a mobile communication service is 30% to 40%, and the gain ratio Rpwr of the antenna main leaf is 90% or more, Six sector antennas satisfying the above criteria are selected. In order to select an optimal six-sector antenna, the characteristics of the antennas having beam widths of 65 degrees, 50 degrees, and 40 degrees are compared as follows.

Table 2 compares the efficiency of the six sector antenna. However, Table 2 assumes that the loading factor of the base station is 0.5, the number of subscribers is 20, the power ratio of the pilot signal to the total power of the base station is 20.5%, and the handoff area is the pilot signal of each sector at any point. The strength is calculated and defined as two or more points receiving at least -15dB of pilot signal.

65 degree antenna 50 degree antenna 40 degree antenna Handoff incidence rate for 20 subscribers 67.2 66.7 18.7 Rpwr (%) 69.67 66.12 90.16 Pant 4.18 3.96 5.44

In Table 1, Rpwr is the gain ratio of the antenna main lobe expressed as the ratio of the antenna gain within ± 30 to the total antenna gain, based on the direction of the antenna main lobe, and Pant is the antenna main lobe for 6 sectors. It is the sum of gain ratios. Rpwr and Pant are calculated by equation (2).

Pant = Rpwr × 6

here P Is the power of the six-sector antenna transmitted at a certain angle P _t Is the total power of the 6 sector antenna. FIG. 3 shows a radiation pattern of six sector antennas. As shown, a side lobe pattern of a 65 degree or 50 degree antenna is larger than a 40 degree antenna. These side lobes interfere with other sectors and cause an increase in the handoff area.

4 to 6 show antenna patterns of a 6 sector base station using 6 antennas. Referring to Table 2, characteristics of each antenna, in particular, the handoff area ratio, gain ratio of antenna main lobe, and capacity increase according to sectorization are shown. The ratio is explained.

4 and 5 show the antenna pattern of the six-sector base station by the 65 degrees and 50 degrees antenna, the base station has a handoff area ratio of 30% to 40% and the gain ratio of the antenna main lobe is 90% or less. In particular, in the case of a six-sector base station using a 50 degree antenna, the rate of increase of capacity according to sectorization is about 3.94 times. When the ideal antenna is used, the capacity increase rate should be 6 times, but due to the interference between sectors, the increase rate of the actual capacity is lower than expected.

However, the 40-degree antenna shown in FIG. 6 has a gain ratio of 90% or more of the antenna main lobe. Therefore, an antenna suitable for a 6 sector base station is an antenna having a gain ratio of 90% or more antenna main lobe, that is, an antenna having a beam width of less than 50 degrees.

The present invention can be variously modified and can take various forms and only the specific embodiments thereof are described in the detailed description of the invention. It is to be understood, however, that the present invention is not limited to the specific forms mentioned in the detailed description of the invention, but rather includes all modifications, equivalents, and substitutions within the spirit and scope of the invention as defined by the appended claims. It should be understood to do.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

In the present invention, when the service area of the base station is divided into six sectors, a sector antenna having a beam width of less than 50 degrees is used, thereby reducing interference between antennas, reducing handoff area of the base station, and improving system capacity and performance. It can be effected.

Claims (4)

A base station internal system which provides a mobile communication service by dividing an entire service area into six sectors; A base station having antennas for multiple sectors, coupled to a base station internal system, comprising six antennas for transmitting radio frequency signals to each sector. The method of claim 1, wherein the antenna, A base station having an antenna for multiple sectors, with a beamwidth of less than 50 degrees. The method of claim 1, wherein the antenna, A base station having an antenna for multiple sectors, wherein the ratio of the handoff area to the entire service area of the base station is 30% to 40%. The method of claim 1, wherein the antenna, A base station having an antenna for multiple sectors, wherein the ratio of the antenna gain within a range of ± 30 degrees relative to the main lobe's total gain to the total gain of the antenna is 90%.