Communications: directive radio wave systems and devices (e.g. – Directive – Including a steerable array
Reexamination Certificate
2001-12-07
2003-12-09
Blum, Theodore M. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a steerable array
C342S368000, C342S373000, C342S374000
Reexamination Certificate
active
06661374
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a base transceiver station in a radio communication system; and, more particularly, to a base transceiver station having a multi-beam controllable antenna system in a radio communication system, which varies a horizontal/vertical angle and a tilting angle according to variation in an amount of traffic within a sector.
DESCRIPTION OF THE PRIOR ART
From now on, a radio communication should support not only a voice service but also a high speed multimedia service including a data communication, a video transmission service, etc. However, radio resources necessary for the radio communication are limited. Therefore, various methods for effectively reusing the radio resources are being developed.
In general, a radio communication system includes a mobile switching center (MSC), a base station controller (BSC), a plurality of base transceiver stations (BTS) and a plurality of mobile stations (MS).
The MSC controls a plurality of the BSCs each controlling a plurality of the BTSs.
A signal radiated from the MS located in a service coverage of the BTS is transmitted to the MSC through the BTS and the BSC. On the contrary, a signal from the MSC is transmitted to the MS through the BSC and the BTS. Here, the BTS communicates with the MS through the radio resource and does with the BSC through the wired resource.
The BSC performs a connection between the BTS and the MSC and a signal processing for a communication between the BTS and the MSC.
The MSC performs a call processing of a subscriber, a call setup/release and functions for providing value added services.
FIG. 1
shows a conventional base transceiver station.
Referring to
FIG. 1
, the conventional base transceiver station includes fixed combiners
101
-
1
to
101
-
3
, fixed dividers
103
-
1
to
103
-
3
, amplifiers
105
-
11
to
105
-
34
, combiners
107
-
1
to
107
-
3
and duplexers
109
-
1
to
109
-
3
.
A service area of the BTS is divided into multiple sectors, and frequency assignments assigned to the BTS are re-assigned to the multiple sectors. The frequency assignment assigned to each sector is fixed in order to be used only for the sector.
In general, a beam pattern of an antenna is set to be wider than the service area as shown in FIG.
2
A.
Referring to
FIG. 2B
, the FAs in each of the sectors are overlapped with each other, efficiency of frequency is considerably decreased in the overlapped region (denoted by oblique lines).
Since the mobile station always moves, distribution of subscribers in the service areas, i.e., a cell or a sector, always varies. However, a horizontal half-power beam width and a tilting angle of an antenna system located in the BTS are fixed and cannot be varied.
Therefore, though traffics in a certain sector is temporarily increased, the frequency assignments cannot be changed, thereby decreasing efficiency in use of the frequency resources.
In general, the antenna is located on a high location, which is remote from the BTS, and the antenna is coupled to the BTS by using a radio frequency (RF) cable. There is a transmission loss in the long RF cable. As the RF cable is longer, the transmission loss becomes larger.
There are a conventional mechanical down-tilting antenna system and a conventional electrical down-tilting antenna system. The mechanical down-tilting antenna system being capable of mechanically down-tilting a beam radiated from an antenna incorporated into the antenna system. The antenna is mounted atop a mast at a height above ground, e.g., in many cases about 200 feet.
In case when the orientation of a radiation beam is steered downward, the antenna must be mechanically down tilted. One of the major shortcomings is that this approach is generally regarded as too rigid and too expensive. There is an approach that electrically down-tilting the radiation beam is performed by steering the relative phases of the radiation associated with each of several radiators of an antenna.
The conventional electrical down-tilting antenna being capable of electrically down-tilting a beam
406
radiated from an antenna array incorporated into the antenna system. In the antenna system, the antenna array incorporates therein an array of radiators and a single point signal feed network provided with a scan network to couple the single point signal feed network to the antenna array of radiators. The scan network includes a plurality of transmission lines between the feed network and each radiator. Among these electrical down tilting method is a capacitive coupling method, in which an adjustable capacitance is placed in series with the transmission lines to provide a plurality of signals to each radiator of the antenna array, thus causing the desired phase shifts. A phase shifter is associated with each radiator of the antenna array such that the phase shifted beam from each radiator constructively interferes with the beam from every other radiator to produce a composite beam radiating at an angle from a line normal to the surface of the antenna. By changing the phase shift provided by each phase shifter, the beam can be scanned across the antenna surface. Another such approach is to use different lengths of transmission lines for feeding the different elements to produce a permanent electrical down tilting.
There are a number of problems associated with the above-described antenna systems. First of all, both of the antenna systems cannot steer a radiation beam in horizontal direction.
Another problem of the conventional antenna system is that it requires a number of phase shifters corresponding to the number of the transmission lines in the conventional antenna systems.
In addition, in the conventional antenna systems, it requires a mechanically complex, for example using a rack and pinion assembly or a number of phase shifters corresponding to the number of radiators, for providing the desired phase shift.
Further, the conventional antenna systems cannot steer a beam width in horizontal and in vertical,
Finally, because a beam is scanned in vertical and in horizontal by utilizing the conventional antenna systems, it has too much scan loss.
Therefore, in order to keep an output power of a signal radiated from the antenna constant, an output power of a multi channel power amplifier (MCPA) in the BTS should be increased.
Since the MCPA is an expensive device, a high capacity MCPA makes the cost for the BTS increased.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an antenna system capable of controlling multi beams of frequency assignments by independently varying a half-power beam width and a tilting angle in vertical and horizontal direction.
It is another object of the present invention to provide a method and a base transceiver station for controlling multi beams of frequency assignments by independently varying a half-power beam width and a tilting angle in vertical and horizontal direction.
It is another object of the present invention to provide an antenna system for electrically steering a beam emitted therefrom in horizontal by using a multi-line phase shifter.
It is another object of the present invention to provide an antenna system for selectively switching a beam width in horizontal by using a switchable divider.
It is another object of the present invention to provide an antenna system for minimizing interference and maximizing cell capacity.
It is another object of the present invention to provide an antenna system for providing an optimal cell planning and meeting the real world of diverse environments.
It is another object of the present invention to provide an antenna system capable of harmonizing with communication environment.
It is another object of the present invention to provide an antenna system with a stable installation.
In accordance with an aspect of the present invention, there is provided an antenna system for controlling multi beams of a transmission signal, comprising; at least one first dividing unit for dividing an input signal into a plurality of first divided signal
Kil Yong-Sup
Kim Duk-Yong
Lee Yoon-Bae
Moon Young-Chan
Blum Theodore M.
Greenblum & Bernstein P.L.C.
KMW Inc.
LandOfFree
Base transceiver station having multibeam controllable... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Base transceiver station having multibeam controllable..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Base transceiver station having multibeam controllable... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3097487