Multiplex communications – Communication over free space – Combining or distributing information via code word channels...
Reexamination Certificate
1999-06-16
2004-02-17
Maung, Nay (Department: 2684)
Multiplex communications
Communication over free space
Combining or distributing information via code word channels...
C370S335000, C375S347000, C714S790000
Reexamination Certificate
active
06693889
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a digital wireless transmission and reception system, a transmission and reception device, and a method of transmission and reception, in which quality of communication is improved.
BACKGROUND OF THE INVENTION
There are a number of methods for improving quality of communication in the digital wireless transmission such as an error-correction coding, a diversity transmission and reception, and a combination of them. A well-known method of error-correction coding among the above is a convolution coding having a superior -performance in the error correction. One example is a newly devised method which combines interleaving and puncturing with the convolution coding, as disclosed in Japanese Patent Laid-Open Publication No. H08-298466. A method of the prior art for improving quality of communication using a combination of the convolution coding, the puncturing and the time-diversity will be briefly described by referring to
FIGS. 8A and 8B
.
In a transmission device
800
of
FIG. 8A
, a series of information data
851
to be transmitted is punctured (thinning-out process) in a unit of a fixed amount of data block by a puncturing unit
802
in order to reduce an amount of communication traffic in a transmission pathway, after it is convolution-coded by a convolutional coding unit
801
. A puncturing (thinning-out) location within the data block is stored as a puncturing pattern in a puncturing pattern generator
803
, from where it is supplied to the puncturing unit
802
.
An example shown in
FIG. 8B
will be described now in detail. A series of input information data {a
0
, b
0
, c
0
, d
0
. . . } is converted into a series of convolution-coded data {a
1
, a
2
, b
1
, b
2
, c
1
, C
2
, d
1
, d
2
, . . . } by the convolutional coding unit
801
having a constraint length of 3 and a coding rate of 1/2. The puncturing unit
802
removes b
2
, d
1
, etc., and outputs a series of punctured data {a
1
, a
2
, b
1
, c
1
, C
2
, d
2
, . . . }, when a puncturing pattern
803
b
is supplied from the puncturing pattern generator
803
. This series of punctured data is a combination of a series of data {a
1
, b
1
, c
1
, e
1
, . . . }, which is obtained by deleting data corresponding to a
0
position in an upper row of the puncturing pattern
803
b
from a series of data {a
1
, b
1
, c
1
, d
1
, e
1
, . . . } corresponding to the upper row of the puncturing pattern
803
b
out of the foregoing series of convolution-coded data, and another series of data {a
2
, c
2
, d
2
, e
2
, . . . }, which is obtained by deleting data corresponding to a
0
position in a lower row of the puncturing pattern
803
b
from a series of data {a
2
, b
2
, c
2
, d
2
, e
2
, . . . } corresponding to the lower row of the puncturing pattern
803
b
out of the series of convolution-coded data.
A time-diversity modulator/transmitter
804
repeats modulation and transmission of the series of punctured data for a predetermined number of times in response to a diversity transmission timing control signal supplied by a diversity transmission timing controller
805
at intervals of a predetermined time.
In a receiving device
810
, the predetermined time for the transmission device
800
to repeat the time-diversity transmission is set in advance with a diversity reception timing controller
811
, so that the diversity reception timing controller
811
outputs a timing control signal for starting a time-diversity reception according to the set time. A time-diversity receiver/demodulator
812
receives and demodulates a signal transmitted repeatedly in response to the control signal of a time-diversity reception timing, and outputs a series of demodulated data of every diversity branch (every repeat time). In this example, description is being made on an assumption that a result of demodulation for each symbol in the series of demodulated data is a quantized data in a resolution of four bits, and a mark and a space have their respective values equivalent to −7 and +7 under the condition of no influence of noises.
A puncturing pattern generator
813
stores a puncturing pattern, which is identical to the puncturing pattern
803
b
used in the puncturing unit
802
of the transmission device. A depuncturing unit
814
uses this puncturing pattern to depuncture the series of demodulated data of every diversity branch, and outputs a series of depunctured data of every diversity branch. The depuncturing is a process in which the punctured position is filled with a dummy data such as a value of 0 corresponding to a middle value between the soft decision value of −7 corresponding to a mark and the soft decision value of +7 corresponding to a space, for example. In the case of the foregoing series of punctured data {a
1
, a
2
, b
1
, c
1
, c
2
, d
2
, . . . }, the depuncturing unit
814
outputs a series of depunctured data {a
1
, a
2
, b
1
,
0
, c
1
, c
2
,
0
, d
2
, . . . }.
The series of depunctured data of every diversity branch obtained here is combineed symbol by symbol in a unit of block by a combining unit
815
, and they are convolution-decoded with a method such as the Viterbi soft quantization by a convolutional decoding unit
816
, which in turn outputs a series of decoded information data. There may be a case where the depuncturing and the combining are reversed in their order of transaction.
The devices can thus achieve an improvement in quality of communication for both of the error-correction coding and diversity with the structure as described above, by performing punctured-convolution-coding and time-diversity transmission on the information data to be transmitted, and also combining and depunctured-convolution-decoding after time-diversity reception of the data at the receiving side.
However, the structure of
FIGS. 8A and 8B
punctures certain identical locations in the series of convolution-coded data (error-correction code word) in each of the repeated transmissions by way of the time-diversity transmission. Therefore, these certain punctured locations and vicinity of them become susceptible to noises, as they become low in likelihood when convolution-decoding them, since they are treated as values having a large length between codes from both of the mark and the space at the receiving side.
SUMMARY OF THE INVENTION
A transmission and reception system of the present invention comprise a transmission device, a receiving device, and a communication pathway between them. The transmission device includes the following elements:
(1) a convolutional coding unit for convolution-coding a series of input data, and outputting a series of convolution-coded data;
(2) a puncturing unit for puncturing the series of convolution-coded data by using a plural form of puncturing patterns individually, and outputting a plurality of series of punctured data; and
(3) a modulator/transmitter for modulating and transmitting the plurality of series of punctured data via at least one communication pathway.
And the receiving device includes the following elements:
(1) a receiver/demodulator for receiving and demodulating a signal transmitted by the transmission device through the communication pathway, and outputting a plural variety of series of demodulated data;
(2) a depuncturing unit for depuncturing the plural variety of series of demodulated data by using each of the plural form of puncturing patterns that is identical to the one used by the puncturing unit, and outputting a plural variety of series of depunctured data;
(3) a combining unit for combining the plural variety of series of depunctured data, and outputting a result of combining; and
(4) a convolutional decoding unit for convolution-decoding the result of combining, and outputting a decoded data. The transmission and reception system transmits and receives via at least one communication pathway each of the plural variety of series of error-correction coded data obtained by puncturing and convolution-c
Abe Katsuaki
Hasegawa Makoto
Yamamoto Naoyuki
Maung Nay
RatnerPrestia
Sobutka Philip J.
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