KR20000034002A - Sector antenna system of cdma mobile communication system - Google Patents

Abstract

PURPOSE: A sector antenna system of the CDMA(Code Division Multiple Access) mobile communication system is to provide a sector antenna system to proceed more efficient soft hand-off, by optimizing the cell structure divided into a plurality of sectors. CONSTITUTION: The cell structure divided into three sectors in the CDMA system is composed of four cells(A,B,C,D) and two mobile stations(100,101). Incident angles for each cell are same(alpha1 = alpha2 = alpha3) in a point(102) the boundary lines of three cells meet. But, in other boundary point(103), except for the boundary point(102), incident angles for each cell are all not in accord.

Description

Sectored antenna system of code division multiple access mobile communication system

The present invention relates to a sector antenna system, and more particularly, to a sector antenna system of a code division multiple access (CDMA) mobile communication system capable of increasing a soft handoff success rate and increasing antenna gain.

A digital cellular mobile communication system is a method of dividing a large area into a plurality of cells to enable communication between a base station in each cell and a plurality of mobile stations (MSs) in the vicinity thereof. The communication between the base station and the mobile station transmits and receives information signals in analog or digital form through a wireless communication channel.

In general, a radio channel for transmission from a base station to a mobile station is called a forward link, and a radio channel for transmission from a mobile station to a base station is called a reverse link. The base station must simultaneously transmit modulated signals to multiple mobile stations, and simultaneously receive signals from multiple mobile stations. To this end, a multiplexing or multiple access method is required.

Multiple-access methods include frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and the like. In particular, CDMA is known to be superior to other systems in terms of system capacity. On the capacity of a cellular CDMA, published by KSGilhousen, IMJacobs, R. Padovani, A. Viterbi, LAWeaver, C.Wheatly, IEEE Trans.Veh.Technol., Vol.40, No.2 system 'is described in detail.

The CDMA system transmits a spread spectrum signal by assigning a unique pseudo noise code (PN code) to each user. The receiver uses the same code as the PN code used when spreading the spread spectrum signal.

On the other hand, the CDMA system is a system whose capacity is determined according to the amount of interference received. Therefore, the Sectorization method is used to reduce the amount of interference received and increase system capacity. Sectorization is a method of receiving only signals from a limited range of directions by using a sector antenna at a base station. However, the increasing number of users and the demand for higher quality services require higher system capacity.

Meanwhile, in the mobile communication system, when the mobile station enters a new cell out of the service area of the governing base station, communication can be continued by the handoff function. Such handoff methods include a hard handoff method and a soft handoff method.

In an analog cellular system, a hard handoff method is used, in which a new base station and a mobile station disconnect a link with an existing base station before starting communication, and then connect with a new base station. Therefore, when the handoff occurs, the connection is disconnected for a short time and the voice quality is degraded.

Meanwhile, in a digital cellular system, when a mobile station enters a new cell out of an existing cell area, a link with a new base station is newly formed without breaking the link with the existing base station. In other words, a handoff procedure in a code division multiple access mobile communication system is performed in order of connection with an existing base station, simultaneous connection with both base stations, and then link disconnection with an existing base station. This kind of handoff is called a soft handoff method. This soft handoff is less likely to break the communication, and the user is not aware that a handoff has occurred since the communication link is not disconnected during communication.

1 shows a cell structure of a conventional CDMA system divided into three sectors, in which four A, B, C, and D cells and two mobile stations 90, 91 are shown.

As can be seen from FIG. 1, when the mobile stations exist in the cell and the boundary region of the cell, it can be seen that the angles of incidence of the respective mobile stations are the same. For example, if a mobile station is at position 90, which is the boundary region of cells A, B, and C, this position is the angle of incidence for the c sector of cell A, the a sector of cell B, and the b sector antenna of cell C. As a near zero point, the mobile station in this position is subjected to a soft handoff procedure from two of the above three sectors. Therefore, in this case, the relatively soft handoff process can proceed well.

However, when the mobile station is at position 91, the position of incidence angle is almost 60 degrees with respect to sectors a and c of cell A, sectors a and b of cell C, sectors b and c of cell D, i.e. Located in the border area. Therefore, since the present mobile station is in a poor orientation, there is a problem that the call drop probability increases when the soft handoff process is performed.

On the other hand, in the conventional cell structure configured as shown in FIG. 1, it can be seen that the incident angles to the adjacent sectors are equal to each other at any position of the boundary line between adjacent cells. That is, by looking at the (92) and (93) points arbitrarily, it can be seen that the incidence angles of the respective points are equal to each other ( α ₁ = α _2, β ₁ = β ₂ ). It can also be seen that the sector boundaries of a cell always meet the sector boundaries of adjacent cells.

The present invention has been made to solve the problems of the prior art as described above, in the sector antenna system of a code division multiple access (CDMA) mobile communication system having a cell structure divided into a plurality of sectors, It is an object of the present invention to provide a sector antenna system capable of performing a more efficient soft handoff by optimizing a sector divided structure.

1 is a diagram illustrating a cell structure of a conventional CDMA system divided into three sectors.

2 is a diagram illustrating a cell structure of a CDMA system divided into three sectors according to an embodiment of the present invention.

According to the present invention for achieving the above object, in the sector antenna system of a code division multiple access (CDMA) mobile communication system having a cell structure divided into a plurality of sectors, the boundary lines of three or more cells are mutually Except for the point of meeting, a sector antenna system is provided which is installed such that the angle of incidence for each cell does not coincide with each other at the boundary line between each cell.

In addition, in the sector antenna system of a code division multiple access (CDMA) mobile communication system having a cell structure divided into a plurality of sectors, a sector characterized in that the cells adjacent to each other and the sector boundaries within the cell are installed so as not to meet each other. An antenna system is provided.

In addition, in a sector antenna system of a code division multiple access (CDMA) mobile communication system having a cell structure divided into a plurality of sectors, each cell and a cell between cells except for a point where boundary lines of three or more cells meet each other. The angles of incidence for each cell at the boundary of do not coincide with each other; A sector antenna system is provided so that adjacent cells and sector boundaries within a cell do not meet each other.

On the other hand, more preferably, the sector antenna system is characterized in that the cell is divided into three sectors.

In the following, with reference to the accompanying drawings, a preferred embodiment according to the present invention will be described in detail.

FIG. 2 is a diagram illustrating a cell structure of a CDMA system divided into three sectors according to an embodiment of the present invention, in which four A, B, C and D cells and two mobile stations 90 and 91 are shown. .

When the cells are configured as shown in Fig. 2, since there is no place where each sector and the boundary line of the sector meet each other, as in area 91 of Fig. 1, there is no area where the directivity is poor for each overlapping sector. do.

For example, in the region (100), the incident angle is about 30 degrees with respect to the c sector of the A cell, the a sector of the B cell, and the b sector of the C cell, and the region (101) has the incident angle with respect to the b and c sectors of the D cell. Since the angle of the b and c sector antennas is low because the angle of incidence is 0 degrees with respect to the sector a of cell A, since the gain of the sector a is the best, the soft handoff between the two cells It's done smoothly.

On the other hand, as can be seen in Figure 2, at the point 102 where the three cells meet, the angle of incidence for each cell is the same ( α ₁ = α ₂ = α ₃ ), The incident angle for each cell is different at the other boundary point 103 ( β ₁ ≠ β ₂ You can see that. It can also be seen that there is no point where the sector boundaries of each cell ever meet the sector boundaries of adjacent cells.

As described in detail above, the present invention is directed to a sector antenna system of a code division multiple access (CDMA) mobile communication system having a cell structure divided into a plurality of sectors, by optimizing the cell structure divided into a plurality of sectors. It has the effect of increasing the handoff success rate.

The technical spirit of the present invention has been described above with reference to the accompanying drawings. However, the present invention has been described by way of example only, and is not intended to limit the present invention. In addition, it is obvious that any person skilled in the art may make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (6)

In the sector antenna system of a code division multiple access (CDMA) mobile communication system having a cell structure divided into a plurality of sectors, A sector antenna system, characterized in that the angle of incidence for each cell does not coincide with each other at the boundary line between each cell except for the point where the boundary lines of three or more cells meet each other. The method of claim 1, And wherein the cell is a cell divided into three sectors. In the sector antenna system of a code division multiple access (CDMA) mobile communication system having a cell structure divided into a plurality of sectors, A sector antenna system, characterized in that the cells adjacent to each other and the sector boundaries within the cell are installed so as not to meet each other. The method of claim 3, wherein And wherein the cell is a cell divided into three sectors. In the sector antenna system of a code division multiple access (CDMA) mobile communication system having a cell structure divided into a plurality of sectors, The angle of incidence for each cell does not coincide with each other at the boundary line between each cell and the cell, except at the point where the boundary lines of the three or more cells meet each other; A sector antenna system, characterized in that the cells adjacent to each other and the sector boundaries within the cell are installed so as not to meet each other. The method of claim 5, And wherein the cell is a cell divided into three sectors.