Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
2000-03-21
2004-08-03
Gary, Erika (Department: 2681)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S562100
Reexamination Certificate
active
06771984
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a base station apparatus and radio communication method in a radio communication system with, for example, portable telephones.
BACKGROUND ART
A conventional base station apparatus in a radio communication system is explained.
FIG. 1
is a block diagram illustrating a configuration of the conventional base station apparatus. Signals received from antennas
1
to
3
are input as received signals to radio reception section
10
respectively through duplexers
4
to
6
.
The received signals
7
to
9
are subjected to amplification, frequency conversion, and A/D conversion in radio reception section
10
, and output as baseband signals or IF signals
11
to
13
to timing detection section
16
, respectively. Timing detection section
16
detects an optimal timing from the signals, and outputs detected signal
17
to adaptive array antenna receiver
14
. Further, baseband signals or IF signals
11
to
13
are combined in adaptive array antenna receiver
14
, and the resultant signal is output to radiation pattern forming section
21
as combined signal
15
. Radiation pattern forming section
21
forms a radiation pattern for transmission.
Meanwhile, transmission signal
18
is modulated in modulation section
19
, input to radiation pattern forming section
21
, and output therefrom as signals
22
to
24
. Signals
22
to
24
are subjected to D/A conversion and frequency conversion in radio transmission section
25
, output to duplexers
4
to
6
as transmission signals
26
to
28
, and then transmitted from antennas
1
to
3
. At this time, transmission timing control section
29
outputs transmission timing control signal
30
to modulation section
19
, radiation pattern forming section
21
and radio transmission section
25
, in each of which the transmission timing is controlled.
The propagation model in a radio communication is explained using the base station apparatus with the above-mentioned configuration. As an example, it is assumed that the number of antennas of each of base station apparatuses
41
and
50
is three. As illustrated in
FIG. 2A
, in an uplink (transmission from a terminal to a base station), a signal transmitted from terminal apparatus
45
through antenna
46
arrives at antennas
42
to
44
of base station apparatus
41
while being reflected by, for example, mountain
47
. Further, as illustrated in
FIG. 2B
, in a downlink (transmission from the base station to the terminal), a signal transmitted from base station apparatus
50
through antennas
51
to
53
arrives at antenna
55
of terminal apparatus
54
while being reflected by, for example, mountain
56
.
The thus obtained propagation paths
48
,
49
,
57
and
58
are called multipath propagation path, and a technique for compensating the multipath propagation is called equalizing. The communication quality generally deteriorates when the multipath propagation cannot be compensated. To suppress the multipath propagation, it is desired to transmit a signal with either of propagation paths
57
or
58
.
Further, in the multipath propagation, the communication quality varies in propagation paths
57
and
58
respectively as the terminal moves. Accordingly, in the multipath propagation, it is important to detect a direction (path) in which an optimal communication quality is obtained.
However, in the conventional base station apparatus, since the weight for transmission is not selected based on the received level of the desired signal of the received signal obtained by adaptive array antenna combining, a signal cannot be transmitted with an optimal weight, resulting in the problem that the apparatus does not recognize whether the level of the desired signal for a communication partner is increased.
Further, in the case where an optimal propagation path, in other words, a transmission weight, is selected to transmit a signal, the timing arriving at the communication partner varies each time the transmission timing is selected, resulting in the problem that the timing detection at the communication partner becomes difficult.
Furthermore, in a spread spectrum communication system, when a residual left after the transmission timing is adjusted within a unit chip, the orthogonality of codes of the spread spectrum transmission signals deteriorates, resulting in the problem that the received quality deteriorates.
DISCLOSURE OF INVENTION
An object of the present invention is to achieve a base station apparatus capable of recognizing a state of power of a desired signal of a communication partner, and facilitating timing detection of the communication partner.
The inventors of the present invention pay attention to that a radiation pattern is formed by controlling weights in adaptive array antenna processing, and thereby an unnecessary signal is cancelled and the received quality is improved, found out that the transmission quality can be improved by performing transmission to the direction in which high received quality is obtained, and achieved the present invention.
The main point of the present invention is to detect a timing for each incoming signal, perform adaptive array antenna reception with the timing for each incoming signal, calculate a received level of a desired signal using power of adaptive array antenna received result for each incoming signal, select a weight for the adaptive array antenna received result of the desired signal with a higher received level, select a timing of the desired signal with the higher received level, control the transmission timing based on the selected timing, and transmit a signal with the selected weight.
Thus, since the base station apparatus of the present invention determines a transmission direction from a direction of arrival of the desired signal, the apparatus can transmit a signal only to the direction in which the desired signal comes, thus enabling the transmission side to compensate the multipath propagation.
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patent: 5396256 (1995-03-01), Chiba et al.
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patent: 5854612 (1998-12-01), Kamiya et al.
patent: 6064338 (2000-05-01), Kobayakawa et al.
patent: 6122260 (2000-09-01), Liu et al.
patent: 6188915 (2001-02-01), Martin et al.
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PCT International Search Report dated Nov. 2, 1999.
Takeo Ohgane, “Spectral efficiency improvement by base station antenna pattern control for land mobile cellular systems,”Technical Report of IEICE, MW93-25, RCS93-8 (May 1993), pp. 55-60 (in Japanese w/abstract in English); together with Takeo Ohgane, “Spectral Efficiency Improvement by Base Station Antenna Pattern Control for Land Mobile Cellular Systems,” IEICE Trans. Commun., vol. E77-B, No. 5, May 1994, pp. 598-605 (in English).
Gregory G. Raleigh et al., “A Blind Adaptive Transmit Antenna Algorithm for Wireless Communication,” IEEE, 0-7803-2486-2/95, pp. 1494-1499 (in English).
Tadashi Matsumoto et al., “A Technical Survey and Future Prospects of Adaptive Array Antennas in Mobile Communications,” New Technical Report, NTT DoCoMo, vol. 5, No. 4, pp. 25-34 (in Japanese w/abstract in English).
Hiramatsu Katsuhiko
Miya Kazuyuki
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