Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1999-06-21
2003-07-29
Chin, Vivian (Department: 2681)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S101000, C455S069000
Reexamination Certificate
active
06600934
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to data communication device and method in a mobile communication system, and in particular, a device and method for communicating data with selection transmit diversity (STD).
2. Description of the Related Art
Transmit diversity technology offers the advantage of receiver diversity without increasing receiver complexity. STD also makes the advantage of receiver diversity possible without requiring a great modification to the structure of a terminal, and thus increases the capacity of a reverse link in digital cellular mobile communication. Implementation of STD in mobile communications requires the use of plural antennas for a base station as well as the following.
The STD function in a mobile communication system requires a terminal that measures the channel qualities of signals received from antennas of a base station, as well as receives data, and notifies the base station of the measurement result. For this purpose, the base station has forward link common channels assigned to the respective antennas, which are mutually orthogonal. The terminal compares the channel qualities of the antennas by the forward common channels assigned t the respective antenna, and transmits an antenna selection message to the base station to tell the base station to send data through the best channel quality antenna.
In operation, the terminal measures the channel qualities of the antennas for a predetermined time, and sends the base station the antenna selection message for selecting a transmission antenna on the basis of the measurement. Here, the predetermined time is an integer multiple of a power control group (PCG). The base station sends the terminal an antenna reference signal indicative of an antenna in current use for transmission. Then, the terminal can detect the transmission quality of the antenna selection message by comparing the base station antenna used for current transmission data with the antenna selected by the terminal.
FIG. 1
is a block diagram of a conventional STD transmitting device in which a common channel signal is transmitted through each transmission antenna and data is transmitted through a transmission antenna selected based on an antenna selection message received from a terminal. In this example, two transmission antennas are associated with a base station.
FIG. 2
illustrates the operation of the conventional STD transmitting device of
FIG. 1
, in which common channel signals are transmitted consistently through corresponding transmission antennas
151
and
153
, and data is transmitted through a transmission antenna selected based on an antenna selection message received at a predetermined rate.
Referring to
FIGS. 1 and 2
, first and second common channel transmitters
11
and
12
are of the same configuration. They generate common channel signals to be transmitted via the first and second antennas
151
and
153
, respectively. The first common channel transmitter
11
is comprised of a multiplexer
111
for multiplexing a pilot signal and data and a channel transmitter
113
for subjecting a common channel signal received from the multiplexer
111
to channel coding, rate matching, channel interleaving, orthogonal code modulation, and PN (Pseudo-Noise) sequence spreading. The second common channel transmitter
12
is comprised of a multiplexer
121
for multiplexing a pilot signal and data and a channel transmitter
123
for subjecting a common channel signal received from the multiplexer
121
to channel coding, rate matching, channel interleaving, orthogonal code modulation, and PN sequence spreading.
A traffic channel transmitter
13
generates traffic data to be transmitted from the STD transmitting device. In the traffic channel transmitter
13
, a pilot selector
135
generates a corresponding pilot signal in response to an antenna selection message AS fed back from the terminal. A multiplexer
131
multiplexes the pilot signal received from the pilot selector
135
and traffic channel data. A channel transmitter
133
subjects the traffic channel signal received from the multiplexer
131
to orthogonal code modulation and PN sequence spreading.
A switch
141
switches the traffic channel signal based on the antenna selection message AS, and has an input terminal coupled to the output terminal of the traffic channel transmitter
13
, a first output terminal directed toward the first antenna
151
, and a second output terminal directed toward the second antenna
153
. Hence, the switch
141
switches the traffic channel signal to the first or second antenna
151
or
153
according to the antenna selection message AS. An adder
143
adds a signal received from the first output terminal of the switch
141
and a signal received from the first common channel transmitter
11
to provide a signal indicated by
214
in FIG.
2
. An adder
145
adds a signal received from the second output terminal of the switch
141
and a signal received from the second common channel transmitter
12
to provide a signal indicated by
216
in
FIG. 2. A
first RF (Radio Frequency) transmitter
147
is coupled between the adder
143
and the first antenna
151
, and a second RF transmitter
149
between the adder
145
and the second antenna
153
, for converting their corresponding transmit signals to RF signals.
In the conventional STD operation, common channel signals to be transmitted through the antennas
151
and
153
are generated by multiplexing pilot symbols and data and subjecting the multiplexed signals to spectrum spreading. A traffic channel signal is generated by multiplexing a pilot symbol and data selected based on message AS and subjecting the multiplexed signals to spectrum spreading. The resulting traffic channel signal and a corresponding common channel signal are added into the signal as indicated by
214
or
216
of
FIG. 2
to be transmitted via an antenna selected by the antenna selection message AS indicated by
212
of FIG.
2
. The unselected antenna sends a common channel signal
214
or
216
alone.
The above conventional technology, however, has the shortcoming that a base station always sends common channel signals through corresponding plural antennas. Since all the users in a cell do not own terminals adapted to STD, continuous transmission of the common channel signals for some STD terminals results in a waste of forward code resources and transmit power.
SUMMARY OF THE INVENTION
An object of the present invention, therefore, is to provide a STD communicating device and method in a mobile communication system.
Another object of the present invention is to provide a STD transmitting device and method in a mobile communication system, in which a common channel signal is transmitted through a transmission antenna and a traffic channel signal is transmitted through a transmission antenna selected based on an antenna selection message, to thereby enable efficient use of forward code resources and transmit power.
To achieve these and other objects, there is provided a STD communication device and method. In a STD communication method according to the present invention, a base station selects a transmission antenna corresponding to an antenna selection signal received from a terminal, transmits a traffic channel signal through the selected antenna, and transmits a predetermined part of the traffic channel signal through an unselected antenna.
REFERENCES:
patent: 4242538 (1980-12-01), Ito
patent: 5097484 (1992-03-01), Akaiwa
patent: 5465269 (1995-11-01), Schaffner
patent: 6097711 (2000-08-01), Okawa
Ahn Jae-Min
Jeong Joong-Ho
Kim Young-Ky
Yoon Soon-Young
Yun Yu-Suk
Chin Vivian
Dilworth & Barrese, L.L.P.
Moore J
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