Duplex outdoor base station transceiver subsystem utilizing...

Details Duplex outdoor base station transceiver subsystem utilizing... Duplex outdoor base station transceiver subsystem utilizing...

1998-08-14

2001-10-30

Negash, Kinfe-Michael (Department: 2633)

Optical: systems and elements

Deflection using a moving element

Using a periodically moving element

C359S199200, C379S056100, C455S073000, C455S562100

Reexamination Certificate

active

06310705

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a duplex outdoor base station transceiver subsystem utilizing a hybrid system including a High Power Amplifier (HPA) and an Optic Antenna (OA). More particularly, the duplex outdoor base station transceiver subsystem is designed for combined use transmitting/receiving both radio and optical communication signals and is able to provide a communication service to shadowing areas or non-heavy traffic areas.
DESCRIPTION OF THE RELATED ART
A cellular communication system, such as a Personal Communication Service (PCS) and a Code Division Multiple Access (CDMA), includes a plurality of Base station Transceiver Subsystem (BTS) which provide communication service to mobile stations, a plurality of Base Station Controller (BSC), a Base Station Manager system (BSM), a Mobile Switching Center (MSC) and a Location Registering System (LRS).
The term “cellular system” refers to a communication system having a “cell” as one unit of communication coverage. The term “cell” refers to an area where each base station provides service. Typically, each cell is divided into 3 sectors, and the cell coverage is expanded into a BTS area, a BSC area and a MSC area. Data, which is transmitted from a MSC, for instance, voice, is transmitted through a BSC to a transceiver unit of each cell. A base station transceiver subsystem (BTS), for serving mobile telephone subscribers, includes an out-door system having an antenna and coaxial cable installed outside and an indoor system having RF transmit/receive equipment installed inside.
The indoor system generally includes: a RF front End Unit for transmitting receiving a RF signal; a transceiver unit for converting between a RF signal and an intermediate frequency signal; an intermediate frequency amplifier for amplifying an intermediate frequency; a digital unit for modulating and demodulating a transmit/receive signal; and a BTS Test Unit (BTU) for performing a self-diagnosis of a BTS. The RF front end unit further includes: a Directional Coupler (D/C) for connection with an antenna; a band pass filter (BPF) for filtering a signal; a low noise amplifier (LNA) for amplifying the signal; and a power divider and combiner (PD/PC) respectively for dividing and combining the signal to and from a transmitting/receiving antenna.
A BTS test unit is coupled to a transceiver unit by using two ports of a directional coupler in a RF front end unit, one of which is a forward signal port and the other is a reflected signal port. An out-door BTS is proposed to provide a service to a shadowing area, which may include an area blocked from a conventional radio wave by obstacles such as high buildings, the inside of a building, a highway edge and the vicinity of a golf course.
FIG. 1
is a schematic diagram illustrating an out-door base station transceiver subsystem (BTS)
2
. As illustrated in
FIG. 1
, a base station transceiver subsystem (BTS) generally includes: a RF unit
4
for transmitting/receiving a RF signal via an antenna; a digital unit (DU)
6
for modulating/demodulating a digital signal; and a rectifier unit
8
for transmitting a converted signal after converting an alternating current (AC) signal into a direct current (DC) signal.
The RF unit
4
is connected to three external antennas, two of which are receiving antennas
10
,
12
and one of which is a transmitting antenna
14
. Also, the RF unit
14
is connected to a leakage coaxial cable (LCX)
16
via a LCX interface unit in order to provide a service to an underground region such as a highway or subway tunnel, e.g., where signals propagated from antennas
10
,
12
,
14
cannot reach and where an additional antenna cannot easily be installed. The base station transceiver subsystem (BTS)
2
directly transmits and receives signals to and from a mobile station.
The out-door BTS is structured to use a high power amplifier (WHPA), and provides all functions of a conventional base station transceiver subsystem. That is, the out-door BTS provides a function for connection with a base station controller (BSC) through a cable, a function for wireless connection with mobile stations, a function for processing calls from mobile stations, and a function for providing information regarding a base station controller (BSC) and mobile stations.
FIG. 2
is a block diagram illustrating an out-door base station transceiver subsystem. The out-door base station transceiver subsystem (BTS) generally includes: a receiver front end unit (RXFEU)
20
for providing a RF signal to a transceiver unit after amplifying the RF signal; a transceiver front end unit (TXFEU)
24
for providing the RF signal to a transmitting antenna; a high power amplifier (HPA)
26
for amplifying a signal for transmission; a transceiver unit (XCVR)
22
for converting a RF signal into an intermediate frequency signal; a Transceiver Master Control Unit (TMCU)
28
for controlling the transceiver unit; an Analog Common Card (ACC)
30
for transmitting the sampled signal to a modulator/demodulator after sampling an analog intermediate frequency signal into a digital signal; a modulator/demodulator
32
for modulating /demodulating the digitized signal; and an interface unit (IFU)
34
for interfacing the units such as the analog common card (ACC) and the transceiver master control unit (TMCU) with a base station controller (BSC).
The aforementioned out-door BTS uses one Frequency Assignment (FA) per sector to provide a service. As a result, the out-door BTS is unable to cover the whole area within a building or in a subway station, or for instance, a boundary between service areas. To cover non-served areas, another BTS must be established. However, in many cases it is impossible, or at least very costly, to establish an additional BTS. Additionally, a coaxial cable used as a transmission line between a base station transceiver subsystem and an antenna results in significant, undesirable signal transmission loss.
An object of the conventional out-door base station transceiver subsystem is to remove a shadowing area and to enhance speech quality. However, limited space and high costs are burdens which often interfere with achieving this objective using conventional out-door BTS.
U.S. Pat. No. 5,339,184 discloses a communication link interconnecting a base station to a plurality of remote antenna cells. The '184 patent discloses base station transceiver means for optically transmitting RF transmit signals and for receiving an optical uplink channel, so optical transmission is included in a micro cellular network.
U.S. Pat. No. 5,479,595 discloses a mobile telephony system for transmitting signals via two ways. Such a system utilizes an optic antenna tonsure a shadowing area where a RF signal can not reach, for instance, inside office buildings, factories, hospitals, etc.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an out-door base station transceiver subsystem which utilizes a hybrid system of a high power amplifier supplying an RF antenna and an optic antenna. The out-door BTS. includes an interface unit and a duplex RF front end unit in order to distribute a signal transmitted from a high power amplifier to both a standard RF antenna and an optic antenna According to a preferred embodiment of the present invention, a duplex out-door base station transceiver subsystem utilizing a hybrid system of a high power amplifier and an optic antenna, includes a RF front end unit interfaced to an optic antenna; a receiver interface unit for transmitting a signal from an optic antenna to the RF front end unit; a transceiver unit for transmitting a transmit/receive signal to the RF front end unit; a BTS test unit coupled to the RF front end unit for performing a self-diagnosis of a BTS; and an optic antenna interface unit for connecting an optic antenna system with the receiver interface unit.


REFERENCES:
patent: 5339184 (1994-08-01), Tang
patent: 5404572 (1995-04-01), Ishii
patent: 5457557 (1995-10-01), Zarem et al.
patent: 5479595 (1995-12-01), Isrealsson
patent: 5689355 (1997

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