Title: Information data multiplex transmission system, its multiplexer and demultiplexer, and error correction encoder and decoder
Abstract: A multiplexing unit on the transmitting side estimates information amounts supplied from respective signal processing units, determines a multiplex code on the basis of respective information amounts, derives a parity of the first determined multiplex code to form a second multiplex code, adds a CRC to each of the multiplex codes to generate two headers H1 and H2, takes out information data of respective media according to the multiplex codes, incorporates the information data into a packet together with the two headers H1 and H2, and outputs the packet. If error correction of H1 is impossible on the receiving side, error correction decoding is conducted by using the header H2. If error correction of H2 is also impossible, error correction decoding is conducted collectively for H1 and H2.
Patent Number: 7,020,824 Issued on 03/28/2006 to Tanaka, et al.
| Inventors:
|
Tanaka; Hirokazu (Chiba, JP);
Yamasaki; Shoichiro (Tokyo, JP);
Saito; Tatsunori (Yokohama, JP)
|
| Assignee:
|
Kabushiki Kaisha Toshiba (Kawasaki, JP)
|
| Appl. No.:
|
199294 |
| Filed:
|
July 22, 2002 |
Foreign Application Priority Data
| Feb 03, 1997[JP] | 9-020815 |
| Jun 19, 1997[JP] | 9-178954 |
| Oct 22, 1997[JP] | 9-289753 |
| Current U.S. Class: |
714/755; 714/786 |
| Current Intern'l Class: |
H03M 13/00 (20060101); H03M 13/03 (20060101) |
| Field of Search: |
714/752,755,786
|
References Cited [Referenced By]
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| 5734962 | Mar., 1998 | Hladik et al.
| |
| 6134572 | Oct., 2000 | Wolf et al.
| |
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Other References
Partial Supplementary Search Report Under Rule 46(1) from European Patent Office
dated Apr. 22, 2005, in European Application No. EP98928591.
ITU-T H.223 (Mar. 1996)-Series H: Transmission of Non-Telephone Signals, Infrastructure
of Audio Visual Services-Transmission Multiplexing and Synchronization-"Multiplexing
Protocol for Low Bit Rate Multimedia Communication" (Geneva 1996).
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vol. 1, pp. 339-343 (1994).
J. Hagenauer, et al. "Iterative Decoding of Binary Block and Convolutional Codes,"
IEEE Transactions on Information Theory, 42(2): 429-445 (Mar. 1996).
Telecommunications Union International (ITU-T) White Book, "H Series Recommendations
(Part II)" pp. 22-43 and pp. 518-519 (May 27- Jun. 7, 1996) (in Japanese).
H. Tanaka, et al. "A Study on Multiplexing Scheme over Mobile Multimedia Networks"
Technical Research Report of Institute of Electronics information and Communications
Engineers, 97 (326):105-110 (Sep. 1997) (in Japanese).
S. Wicker and V. Bhargava, "Reed-Solomon Codes and Their Applications" IEEE Press,
pp. 8, 9, 76, 77 (1994).
E. Watanabe and S Kamiya, "MPEG 4 Technology for Mobile Multimedia Communation".
Toshiba Review 53(4):41-44 (1998) (in Japanese).
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for Mobile Communication" Technical Research Report of Institute of Electronics
Information and Communications Engineers, 97 (254):35-40 (Sep. 1997) (in Japanese).
K. Akihito, et al. "A Frame Transmission Scheme Adding Error Check Code for Header
Fields" Proceedings of the 1992 IEICE Spring Conference, Part 3(B697):264 (Mar.
24-27, 1992) (in Japanese).
*S. Hotani and T. Miki, "A Study on Variable Length Frame Synchronization for
MPEG-4 Audio RCS96-119" Technical Report of IEICE, 96(481): 35-42 (Jan. 23, 1997)
(in Japanese).
*An English abstract is being submitted with this document.
|
Primary Examiner: Lamarre; Guy
Assistant Examiner: Abraham; Esaw
Attorney, Agent or Firm: Finnegan, Henderson, Farabow, Garrett & Dunner, L.L.P.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a Rule 1.53(b) divisional application of U.S. patent application
Ser. No. 09/242,539, entitled "INFORMATION DATA MULTIPLEX TRANSMISSION SYSTEM,
ITS MULTIPLEXER AND DEMULTIPLEXER, AND ERROR CORRECTION ENCODER AND DECODER," filed
on Feb. 18, 1999, now U.S. Pat. No. 6,490,243 based on International Application
No. PCT/JP98/02749, filed on Jun. 19, 1998, and to which Applicants claim the benefit
of priority under 35 U.S.C. § 120. Applicants also claim foreign priority
benefits under 35 U.S.C. § 119 (a)-(d) or § 365 (a)-(b) based on Japanese
Patent Application No. 9-17954, filed Jun. 19, 1997, and Japanese Patent Application
No. 9-289753, filed Oct. 22, 1997. The contents of all of the above-identified
applications are expressly incorporated herein by reference in their entirety.
Claims
The invention claimed is:
1. An error correction encoding apparatus characterized in that said error correction
encoding apparatus comprises:
a first error correction encoding means for generating a first inspection signal
sequence for a first information signal sequence and a second information signal
sequence requiring more intense error protection than the first information signal sequence;
a transmitting interleaving means for changing element order of said second information
signal sequence;
a second error correction encoding means for generating a second inspection signal
sequence for the second information signal sequence changed in order by said transmitting
interleaving means; and
a transmitting means for transmitting an encoded signal including said first
and second information signal sequences and said first and second inspection signal
sequences onto a transmission channel.
2. An error correction decoding apparatus for receiving and decoding the encoded
signal transmitted from the error correction encoding apparatus according to claim
1, characterized in that said error correction decoding apparatus comprises:
a first error correction decoding means for conducting error correction decoding
on the first and second information signal sequences included in said received
encoded signal, on the basis of the first inspection signal sequence included in
said encoded signal, and outputting first and second decoded information signal sequences;
a receiving interleaving means for changing element order of the second decoded
information signal sequence output from said first error correction decoding means;
a second error correction decoding means for conducting error correction decoding
on the second decoded information signal sequence changed in order by said receiving
interleaving means, on the basis of the second inspection signal sequence included
in said received encoded signal, and outputting the second decoded information
signal sequence further subjected to the error correction; and
a receiving de-interleaving means for restoring the second decoded information
signal sequence output from said second error correction decoding means, to the
original element order.
3. An error correction decoding apparatus for receiving and decoding the encoded
signal transmitted from the error correction encoding apparatus according to claim
1, characterized in that said error correction decoding apparatus comprises:
a receiving interleaving means for changing element order of the second decoded
information signal sequence included in the received encoded signal;
a second error correction decoding means for conducting error correction decoding
on the second decoded information signal sequence changed in order by said receiving
interleaving means, on the basis of the second inspection signal sequence included
in said received encoded signal, and outputting the second decoded information
signal sequence;
a receiving de-interleaving means for restoring the second decoded information
signal sequence output from said second error correction decoding means, to the
original element order; and
a first error correction decoding means for conducting error correction decoding
on the second decoded information signal sequence output from said receiving de-interleaving
means and the first information signal sequence included in said received encoded
signal, on the basis of the first inspection signal sequence included in said received
encoded signal, and outputting the first decoded information signal sequence and
the second decoded information signal sequence further subjected to the error correction.
4. An error correction decoding apparatus according to 3, characterized in that
said first and second error correction decoding means has an iterative decoding
function of iterating the error correction decoding processing between them at
least once.
5. An error correction decoding apparatus according to claim 4, characterized
in that said error correction decoding apparatus further comprises an iteration
control means for determining number of times of iteration according to at least
one of a demanded error correction capability and a permitted processing delay
amount, and setting the determined number of times of iteration into said first
and second error correction decoding means.
6. An error correction decoding apparatus according to claim 4, characterized
in that said error correction decoding apparatus further comprises, on an input
side of said first and second error correction decoding means, a normalization
means for normalizing a signal level of each of signal sequences or signal blocks
to be input to said first and second error correction decoding means, on the basis
of a level of the received encoded signal.
7. An error correction decoding apparatus for receiving and decoding the encoded
signal transmitted from the error correction encoding apparatus according to claim
1, characterized in that said error correction decoding apparatus comprises:
a first error correction decoding means for conducting error correction decoding
on the first and second information signal sequences included in said received
encoded signal, on the basis of the first inspection signal sequence included in
said encoded signal, and outputting first and second decoded information signal sequences;
a second error correction decoding means for conducting interleaving on the second
decoded information signal sequence output from said first error correction decoding
means, then conducting error correction decoding on the second decoded information
signal sequence thus interleaved, on the basis of the second inspection signal
sequence included in said received encoded signal, thereby yielding the second
decoded information signal sequence further subjected to the error correction,
conducting de-interleaving on the second decoded information signal sequence, and
outputting the second decoded information signal sequence thus interleaved;
a third error correction decoding means for iterating error correction decoding
processing between said first error correction decoding means and said second error
correction decoding means at least once, and outputting the first and second decoded
information signal sequences thus subjected to iterative decoding; and
a selection means for causing the error correction decoding processing using
only the first error correction decoding means, the error correction decoding processing
using the first and second error correction decoding means, and the error correction
decoding processing using the first, second, and third error correction decoding
means to be selectively executed, on the basis of at least one of a transmission
channel state and a property of the transmitted information signal sequences.
8. An error correction decoding apparatus for receiving and decoding the encoded
signal transmitted from the error correction encoding apparatus according to claim
1, characterized in that said error correction decoding apparatus comprises:
a second error correction decoding means for conducting interleaving on the second
decoded information signal sequence included in the received encoded signal, then
conducting error correction decoding on the second information signal sequence
thus interleaved, on the basis of the second inspection signal sequence included
in the received encoded signal, thereby yielding a second decoded information signal
sequence, conducting de-interleaving on said second decoded information signal
sequence, and outputting the second decoded information signal sequence thus interleaved;
a first error correction decoding means for conducting error correction decoding
on the second decoded information signal sequence output from said second error
correction decoding means and the first information signal sequence included in
said received encoded signal, on the basis of the first inspection signal sequence
included in said received encoded signal, and outputting the first decoded information
signal sequence and the second decoded information signal sequence further subjected
to the error correction;
a third error correction decoding means for iterating error correction decoding
processing between said first error correction decoding means and said second error
correction decoding means at least once, and outputting the first and second decoded
information signal sequences thus subjected to iterative decoding; and
a selection means for causing the error correction decoding processing using
only the first error correction decoding means, the error correction decoding processing
using the first and second error correction decoding means, and the error correction
decoding processing using the first, second, and third error correction decoding
means to be selectively executed, on the basis of at least one of a transmission
channel state and a property of the transmitted information signal sequences.
9. An error correction encoding apparatus for conducting error correction encoding
on a first information signal sequence and a second information signal sequence
requiring more intense error protection than the first information signal sequence,
and transmitting the encoded first information signal sequence and second information
signal sequence, characterized in that said error correction encoding apparatus comprises:
a transmitting interleaving means for changing element order of said second information
signal sequence;
a first error correction encoding means for generating a first inspection signal
sequence for the second information signal sequence changed in order by said transmitting
interleaving means and said first information signal sequence;
a second error correction encoding means for generating a second inspection signal
sequence for said second information signal sequence; and
a transmitting means for transmitting an encoded signal including said first
and second information signal sequences and said first and second inspection signal
sequences onto a transmission channel.
10. An error correction decoding apparatus for receiving and decoding the encoded
signal transmitted from the error correction encoding apparatus according to claim
9, characterized in that said error correction decoding apparatus comprises:
a second error correction decoding means for conducting error correction decoding
on the second information signal sequence included in the received encoded signal,
on the basis of the second inspection signal sequence included in said encoded
signal, and outputting a second decoded information signal sequence;
a receiving interleaving means for changing element order of the second decoded
information signal sequence output from said second error correction decoding means;
a second error correction decoding means for conducting error correction decoding
on the second decoded information signal sequence changed in order by said receiving
interleaving means and the first information signal sequence included in said received
encoded signal, on the basis of the first inspection signal sequence included in
said received encoded signal, and outputting a first decoded information signal
sequence and the second decoded information signal sequence further subjected to
the error correction; and
a receiving de-interleaving means for restoring the second decoded information
signal sequence output from said second error correction decoding means, to the
original element order.
11. An error correction decoding apparatus for receiving and decoding the encoded
signal transmitted from the error correction encoding apparatus according to claim
9, characterized in that said error correction decoding apparatus comprises:
a receiving interleaving means for changing element order of the second information
signal sequence included in the received encoded signal;
a first error correction decoding means for conducting error correction decoding
on the second decoded information signal sequence changed in order by said receiving
interleaving means and the first information signal sequence included in said received
encoded signal, on the basis of the first inspection signal sequence included in
said received encoded signal, and outputting first and second decoded information
signal sequences;
a receiving de-interleaving means for restoring the second decoded information
signal sequence output from said first error correction decoding means, to the
original element order; and
a second error correction decoding means for conducting error correction decoding
on the second decoded information signal sequence output from said receiving de-interleaving
means, on the basis of the second inspection signal sequence included in said received
encoded signal, and outputting the second decoded information signal sequence further
subjected to the error correction.
12. An error correction decoding apparatus according to 11, characterized in
that said first and second error correction decoding means has an iterative decoding
function of iterating the error correction decoding processing between them at
least once.
13. An error correction decoding apparatus according to claim 12, characterized
in that said error correction decoding apparatus further comprises an iteration
control means for determining number of times of iteration according to at least
one of a demanded error correction capability and a permitted processing delay
amount, and setting the determined number of times of iteration into said first
and second error correction decoding means.
14. An error correction decoding apparatus for receiving and decoding the encoded
signal transmitted from the error correction encoding apparatus according to claim
9, characterized in that said error correction decoding apparatus comprises:
a first correction decoding means for conducting error correction decoding on
the second information signal sequences included in the received encoded signal,
on the basis of the second inspection signal sequence included in said encoded
signal, and outputting a second decoded information signal sequence;
a second correction decoding means for conducting error correction decoding on
a signal sequence obtained by conducting interleaving on the second decoded information
signal sequence output from said second error correction decoding means, and the
first information signal sequence included in said received encoded signal, on
the basis of the first inspection signal sequence included in said received encoded
signal, thereby yielding a first decoded information signal sequence and the second
decoded information signal sequence further subjected to the error correction,
conducting de-interleaving on the second decoded information signal sequence, and
outputting the first decoded information signal sequence and the second decoded
information signal sequence thus interleaved;
a third error correction decoding means for iterating error correction decoding
processing between said first error correction decoding means and said second error
correction decoding means at least once, and outputting the first and second decoded
information signal sequences thus subjected to iterative decoding; and
a selection means for causing the error correction decoding processing using
only the first error correction decoding means, the error correction decoding processing
using the first and second error correction decoding means, and the error correction
decoding processing using the first, second, and third error correction decoding
means to be selectively executed, on the basis of at least one of a transmission
channel state and a property of the transmitted information signal sequences.
15. An error correction decoding apparatus for receiving and decoding the encoded
signal transmitted from the error correction encoding apparatus according to claim
9, characterized in that said error correction decoding apparatus comprises:
a first error correction decoding means for conducting error correction decoding
on a signal sequence obtained by conducting interleaving on the second decoded
information signal sequence included in the received encoded signal, and the first
information signal sequence included in said received encoded signal, on the basis
of the first inspection signal sequence included in said received encoded signal,
and outputting first and second decoded information signal sequence;
a second error correction decoding means for conducting de-interleaving the second
decoded information signal sequence output from said first error correction decoding
means, then conducting error correction decoding on the second decoded information
signal sequence thus de-interleaved, on the basis of the second inspection signal
sequence included in said received encoded signal, and outputting the second decoded
information signal sequence further subjected to the error correction;
a third error correction decoding means for iterating error correction decoding
processing between said first error correction decoding means and said second error
correction decoding means at least once, and outputting the first and second decoded
information signal sequences thus subjected to iterative decoding; and
a selection means for causing the error correction decoding processing using
only the first error correction decoding means, the error correction decoding processing
using the first and second error correction decoding means, and the error correction
decoding processing using the first, second, and third error correction decoding
means to be selectively executed, on the basis of at least one of a transmission
channel state and a property of the transmitted information signal sequences.
16. An error correction encoding apparatus according to 9, characterized in that
unimportant information requiring a predetermined transmission quality is assigned
to the first information signal sequence, and important information requiring a
higher transmission quality than the first information signal sequence is assigned
to the second information signal sequence.
17. An error correction encoding apparatus according to 9, characterized in that
information transmitted by using a first transmission scheme having a predetermined
intensity against transmission errors is assigned to the first information signal
sequence, and information transmitted by using a second transmission scheme having
an intensity against transmission errors lower than that of the first transmission
scheme is assigned to the second information signal sequence.
Description
TECHNICAL FIELD
The present invention relates to a multimedia information data multiplex transmission
system for putting information data of a plurality of kinds each having an arbitrary
information content into a single packet and conducting multiplexed radio transmission,
and its multiplexer and demultiplexer. The present invention further relates to
an error correction encoder and decoder suitable for application to this system.
BACKGROUND ART
For implementing radio multimedia, it is necessary to multiplex and transmit
media information such as image data, voice data, additional data, and the like.
Especially for giving and taking these kinds of information by using a mobile communication
terminal, it is important that the information is made to be capable of being transmitted
in a poor environment such as a multi-path fading environment.
Heretofore, ITU-T recommendation H.223 has been standardized as a scheme
concerning multimedia multiplexing. This scheme implements multimedia multiplexing
of packet multiplexing type in an existing telephone network. An example of H.223
is shown in FIG. 13A. In FIG. 13A, LCN represents logical channel, AL adaptation
layer, PM packet marker, MUX and multiplexing.
Typically, in a MUX packet, a header is disposed at its head. In succession,
four voice bytes (LCN1), one data byte (LCN2), two image (video)
bytes (LCN3), one data byte (LCN2), and two image bytes (LCN3)
are disposed in the cited order. In the example of FIG. 13A, however, image data
finishes in the middle of a MUX packet, and consequently only one byte is accommodated
in a two-byte capacity in the last LCN3. This is indicated by setting a
PM bit in the next packet header to "1".
The format of the header is shown in FIG. 13B. With reference to FIG. 13B, by
referring to an entry of a multiplex table in a four-bit MC (multiplex code) field,
it is specified which media information is represented by each byte of an information
field. A three-bit HEC (header error control) field provides an error detection
function of the MC field using a three-bit CRC. (As for details, see "ITU-T Draft
recommendation H.223, for example.)
By the way, H.223 has been determined on condition that multimedia multiplexing
of packet multiplexing type is implemented in an existing telephone network having
a comparatively fine transmission quality as described above. In order to raise
the transmission efficiency, the header is protected by the three-bit CRC alone.
In radio multimedia communication, however, the transmission channel state is
made poor by fading or the like. If it is attempted to apply H.223 to radio multimedia
communication as it is, therefore, then such a situation cannot be coped with by
the CRC of three bits or so, and header errors frequently occur. This results in
a problem that contents of the multiplex table cannot be read and discard of MUX
packets frequently occurs.
Furthermore, the length of the MUX packets is not always constant, but
changes according to the information content of each media information as shown
in the example of FIG. 13A as well. If packets of such a variable length are transmitted
through a poor radio transmission channel, then packet synchronizing cannot be
attained or the packet length cannot be found on the receiving side, resulting
in frequent discard of MUX packets.
On the other hand, payloads containing information such as data, voice, and data
cannot be decoded correctly either regardless of the received result of header
information, if the radio transmission channel is brought into a poor state. Heretofore,
therefore, there has been proposed such a scheme as to protect the payload by applying
convolution encoding to information of each of image, voice, and data. (As for
details, see, for example, "Proposal for High Level Approach of H.324/Annex C Mode
1", Q11-A-11b, ITU-T Q11/WP2/SG16, June 1997.)
If it is attempted to securely protect the information of the payload, however,
it is necessary to encode all of the information to be protected, resulting in
a lowered transmission efficiency. This is a serious problem especially in a system
having a limited transmission band such as a mobile communication system.
As a scheme for putting information data of a plurality of kinds such as multimedia
information into a packet and conducting multiplex transmission, there is a scheme
standardized on condition that transmission is conducted via a wire telephone network
as heretofore described. If this standardized scheme is employed as it is in a
radio communication system, however, detection errors of header information are
frequently caused on the receiving side by the poor transmission channel state.
Since the multiplex table cannot be read, discard of packets frequently occur.
Especially in the case where the packet length is variable, there occurs such a
state that the packet synchronizing cannot be attained or the packet length cannot
be recognized, resulting in a substantially disabled state in communication.
On the other hand, for the payload, there has been proposed such a scheme as
to
protect it by using an error correction code such as a convolutional code. If it
is attempted to decode information securely on the receiving side by using a conventional
scheme, however, the transmission efficiency of the information significantly falls.
This poses an especially serious problem in a mobile communication system in which
it is difficult to secure a wide transmission band.
DISCLOSURE OF INVENTION
A first object of the present invention is to provide an information data multiplex
transmission system and its multiplexer and demultiplexer capable of reproducing
header information favorably even in the case where transmission is conducted via
a poor transmission channel, thereby reading the multiplex table accurately, and
lowering the packet discard rate.
A second object of the present invention is to provide an information multiplex
transmission system, its multiplexer and demultiplexer, an error correction encoder,
and an error correction decoder capable of decoding and reproducing payloads securely
without significantly deteriorating the transmission efficiency even in the case
where transmission is conducted via a poor transmission channel, and thereby having
a high transmission efficiency and excellent protection performance.
In order to achieve the above described first and second objects, the present
invention provides the following configurations.
(1) In an information transmission system for inserting information into a packet
and transmitting the packet, a transmitting side generates a plurality of error
correction data making the information independently restorable, inserts these
error correction data into a packet together with the information in a predetermined
position relation, and transmits the packet.
If on the receiving side at least one of a plurality of error correction data
can be received and reproduced, it becomes possible owing to such a configuration
to correct transmission errors of information on the basis of the error correction
data and reproduce the information. For example, even in a mobile communication
system having a poor transmission channel quality, therefore, highly reliable information
transmission can be conducted.
(2) In an information data multiplex transmission system for inserting a plurality
of kinds of information data into one packet and conducting multiplex transmission,
a transmitting side generates a plurality of header information pieces, each of
the plurality of header information pieces including a multiplex code indicating
disposition positions in the packet according to kinds of information data inserted
in the packet and including error detection bits for detecting a receiving error
of the multiplex code, causes each header information piece to include error correction
data making the header information piece independently restorable, inserts header
information pieces in predetermined positions of the packet, inserts the plurality
of kinds of information data in positions of the packet indicated by the multiplex
code, and transmits the packet.
In such a configuration, header are provided with an error correction capability.
Even in a mobile communication system having a poor transmission channel quality,
therefore, headers can be reproduced correctly. In addition, a plurality of headers
are transmitted. If at least one of a plurality of headers can be received and
reproduced, therefore, it becomes possible to correct transmission errors of information
on the basis of the header and reproduce the information. As a result, packets
discarded due to an unreadable multiplex table can be reduced. Even in a mobile
communication system or the like having a poor transmission channel quality, therefore,
highly reliable information transmission can be conducted.
(3) In the configuration of (2), multiplexing is effected while conducting processing
so as to make all packets have a predetermined length. In other words, the packet
length is made to be a fixed length. Owing to such a configuration, configuration
of the encoding and decoding means can be simplified.
(4) In the configuration of (2), a receiving side extracts one out of a plurality
of header information pieces inserted in a packet, conducts error detection and
error correction, and, if error correction is impossible, extracts another header
information piece and conducts error detection and error correction, and repetitively
executes processing of extracting another header information piece and conducting
error detection and error correction for all header information pieces until errorless
header information piece is reproduced.
By doing so, an errorless header information piece out of a plurality of header
information pieces can be reproduced.
(5) If all header information pieces cannot be corrected in error in the configuration
of (4), all header information pieces are subjected together to error correction
processing using a coupled code.
Even if all header information pieces cannot be individually reproduced, such
a configuration makes it possible to reproduce the header information by conducting
error correction on all header information pieces collectively.
(6) In an information data multiplexing apparatus of a transmitting apparatus
used in an information data multiplex transmission system for inserting a plurality
of kinds of information data into one packet and conducting multiplex transmission,
the information data multiplexing apparatus includes: an information content
estimation means for estimating information amounts respectively of the plurality
of kinds of information data; a multiplex code generation means for generating
a first multiplex code indicating disposition positions in the packet on the basis
of the information amounts of respective information data estimated by the information
content estimation means, and further generating a second multiplex code having
a fixed relation with the first multiplex code; a header information generation
means for adding error detection and correction code data for detecting and correcting
receiving errors to each of the first and second multiplex codes generated by the
multiplex code generation means and thereby generating first and second header
information; and a packet generation means for storing the information data to
be transmitted in the packet together with the first and second header information
on the basis of the multiplex codes.
The apparatus of the transmitting side has such a configuration. Even if in the
apparatus of the receiving side the first multiplex code cannot be reproduced by
itself, therefore, it becomes possible to reproduce the first multiplex code on
the basis of the second multiplex code. On the basis of the reproduced multiplex
code, each information data can be taken out from the packet.
(7) In the configuration of (6), a parity of the first multiplex code is used
as the second multiplex code. In other words, a concatenated code with respect
to the first multiplex code is used as the second multiplex code.
(8) and (9) As a concrete example of the concatenated code, a convolutional code
and a Hamming code can be mentioned. If a convolutional code is used, the most
likelihood decoding scheme can be used. As a result, the error correction capability
can be raised. If a Hamming code is used, decoding means complying with H.223 already
has an error detection function using the Hamming code, and hence existing decoding
means complying with H.223 advantageously need only to be provided with an error
correction function.
(10) and (11) As the configuration of the packet generation means, such a configuration
as to store the first and second header information in an identical packet, and
such a configuration as to store the first and second header information in different
packets are conceivable. The former one has an advantage that the insertion and
reproduction of header information can be simplified. The latter one has an advantage
that the error correction capability against burst errors can be kept high by making
time distance between the header information pieces long and thereby providing
an interleaving effect.
(12) In the configuration of (6), it is desirable that the multiplex code generation
means determines the multiplex codes so as to make all packets have a predetermined
length. By doing so, fixed-length packets can be transmitted. In a mobile communication
system, highly reliable packet transmission can be effected.
(13) In an information data demultiplexing apparatus of a receiving apparatus
used in an information data multiplex transmission system for inserting a plurality
of kinds of information data having arbitrary information amounts into one packet
and conducting multiplex transmission,
it is now assumed that first and second header information pieces having a multiplex
code indicating disposition positions in the packet according to the plurality
of kinds of information data and error detection and correction code data for detecting
and correcting receiving errors of the multiplex code are stored in the packet,
and the plurality of information data are stored in positions of the packet indicated
by the multiplex code.
At this time, an information data demultiplexing apparatus of a receiving apparatus
includes a header information extraction means for selectively extracting the first
and second information pieces from the packet, and first, second, and third demultiplexing means.
First, the first demultiplexing means conducts error detection on the first
header information piece. If there are no errors, the first demultiplexing means
demultiplexes and outputs the plurality of information data from the packet on
the basis of the multiplex code included in the header information piece. When
an error is detected by the first demultiplexing means, a second demultiplexing
means conducts error correction of the first header information piece and then
conducts error detection again. If there are no errors, the second demultiplexing
means demultiplexes and outputs the plurality of information data from the packet
on the basis of the multiplex code included in the header information piece corrected
in error. Furthermore, when an error is detected by the second demultiplexing means
as well, the third demultiplexing means conducts error detection of the second
header information piece. If there are no errors, the third demultiplexing means
demultiplexes and outputs the plurality of information data from the packet on
the basis of the multiplex code included in the header information piece.
According to the error occurrence state, the first, second and third demultiplexing
means are thus used by stages in order to demultiplex the information data. For
example, in such a state that the transmission channel quality is poor, therefore,
all of the first to third demultiplexing means are used, and the error detection
and error correction of three stages are conducted, accurate information data demultiplexing
being made possible. On the other hand, in such a state that the transmission quality
is comparatively fine, demultiplexing of the information data can be conducted
in a short time.
(14) In the configuration of (13), a fourth demultiplexing means is provided.
When an error is detected by the third demultiplexing means, the fourth demultiplexing
means conducts error correction of the second header information piece and then
conducts error detection again. If there are no errors, the fourth demultiplexing
means demultiplexes and outputs the plurality of information data from the packet
on the basis of the multiplex code included in the header information piece corrected
in error.
(15) In the configuration of (14), a fifth demultiplexing means is further provided.
When an error is detected by the fourth demultiplexing means, the fifth demultiplexing
means conducts error correction of the first header information piece and the second
header information piece collectively and then conducts error detection again.
If there are no errors, the fifth demultiplexing means demultiplexes and outputs
the plurality of information data from the packet on the basis of the multiplex
code included in the first or second header information piece corrected in error.
Even in a case where the transmission channel quality is very poor and the first
to third demultiplexing means cannot demultiplex the information data, it becomes
possible in the configuration heretofore described to restore the header information
by using the fourth and fifth demultiplexing means. As a result, accurate demultiplexing
of the information data becomes possible.
(16) When in the configuration of (2) the header information piece includes
a packet marker representing a continuation state between packets, a multiplex
code field specifying kinds of information data inserted in the packet, and a header
error control field having an error detection function, the transmitting side includes
means for inserting a plurality of the packet markers in the header information
piece repetitively. The receiving side includes means for conducting a majority
decision on the plurality of packet markers and reproducing one correct packet marker.
Owing to such a configuration, it becomes possible on the receiving side to
reproduce a correct packet marker by using such an extremely simple configuration
that a plurality of packet markers are inserted. Even under such a condition that
the transmission quality is poor, therefore, packets can be recognized correctly
and packet discard ratio can be reduced.
(17) In an information data multiplex transmission system for inserting a plurality
of kinds of information data having arbitrary information amounts into one packet,
inserting header information including at least a multiplex code indicating disposition
positions of the plurality of kinds of informations data within the packet into
the packet, and conducting multiplex transmission,
the transmitting side includes a means for adding an error correction code formed
of a Reed-Solomon code to at least one of the plurality of kinds of information data.
The receiving side includes a means for conducting error correction decoding
processing on the plurality of kinds of information data which have been received,
on the basis of error correction codes added to the information data and thereby
reproducing the plurality of kinds of information data.
(18) An information data transmitting apparatus includes an error detection
code addition means for adding an error detection code to first information data
to be transmitted and outputting second information data; an error correction encoding
means for encoding the second information data output from the error detection
code addition means, by using an error correction code formed of a Reed-Solomon
code and outputting third information data; and a header addition means for adding
a control header having control information representing a transmission form of
the information data inserted therein to the third information data output from
the error correction encoding means.
In such a configuration, error correction can be conducted on the information
data while taking a symbol as the unit by using an error correction code formed
of a Reed-Solomon code. As a result, it becomes possible to effectively protect
the information data from burst errors.
(19) In the configuration of (18), the error correction encoding means conducts
error correction encoding on the second information data by using a Reed-Solomon
code over GF(2
8).
This configuration is effective in the case where the information data length
is a fixed length. Furthermore, by using a Reed-Solomon code over GF(2
8),
error correction encoding and decoding processing taking 8 bits as the unit becomes
possible. Therefore, it is also possible to assure the conformity with H.223 which
is an existing scheme.
(20) In the configuration of (18), the error correction encoding means conducts
error correction encoding on the second information data by using a shortened Reed-Solomon code.
By using a shortened Reed-Solomon code, the present invention can be applied
to
variable-length information data as well. In other words, in multimedia communication
including images, a variable-length encoding scheme is typically adopted as the
image encoding scheme. Therefore, the information data length varies from frame
to frame. By conducting error correction encoding by using a shortened Reed-Solomon
code, however, the length variation of the information data can also be coped with.
(21) In the configuration of (20), the error correction encoding means includes:
an encoder main body for conducting error correction encoding processing on the
second information data which has been shift-input by using a shortened Reed-Solomon
code; and an order reversal means for shift-inputting a plurality of information
elements forming the second information data to the encoder main body in descending
order of term degree of an information polynomial and causing the information elements
to be subjected to error correction encoding processing.
Owing to such a configuration, a shortened Reed-Solomon encoding processing
can be implemented while using a general purpose Reed-Solomon encoder as it is.
(22) In the configuration of (20), the error correction encoding means includes
an encoder main body for conducting error correction encoding processing on the
second information data which has been shift-input by using a Reed-Solomon code;
a comparison means for comparing a length of the second information data with a
predetermined fixed length; a null code addition means; and a null code deletion
means. If the length of the second information data is judged to be shorter than
the fixed length by the comparison means, the null code addition means adds a null
code sequence having a length corresponding to a difference to the second information
data, shift-inputs the second information data having the null code sequence thus
added thereto to the encoder main body, and causes the error correction encoding
processing. The null code deletion means deletes a null code sequence corresponding
to the null code sequence added by the null code addition means from the information
data subjected to error correction decoding in the encoder main body, and outputting
a shortened third information data.
Owing to such a configuration, error correction encoding using a shortened
Reed-Solomon code can be implemented.
(23) In an information data multiplex transmission system for inserting a plurality
of kinds of information data into one packet, inserting header information including
at least a multiplex code indicating disposition positions of the plurality of
kinds of informations data within the packet into the packet, and conducting multiplex transmission,
the transmitting side includes a means for adding an error correction code to
first information data to be transmitted, then adding an error correction code
formed of a shortened Reed-Solomon code over GF(2
8) to the information
data having the error correction code thus added thereto, further adding a control
header having control information representing a transmission form of the information
data inserted therein to the information data thus output, and transmitting resultant
information data.
The receiving side includes a means for conducting error correction decoding
processing on the information data which has been received, on the basis of error
correction code formed of the shortened Reed-Solomon code over GF(2
8)
added to the information data and thereby reproducing the information data.
(24) An information data transmitting apparatus includes: an error detection
code addition means for adding an error detection code to first information data
to be transmitted and outputting second information data; an error correction encoding
means for encoding the second information data output from the error detection
code addition means, by using an error correction code formed of a shortened Reed-Solomon
code over GF(2
8) and outputting third information data; and a header
addition means for adding a control header having control information representing
a transmission form of the information data inserted therein to the third information
data output from the error correction encoding means.
In the configuration of (23) and (24), the information data can be effectively
protected from burst errors by using a Reed-Solomon code. In addition, since a-shortened
Reed-Solomon code is used, the configuration can be applied to variable-length
Reed-Solomon code as well. Furthermore, by using a Reed-Solomon code over GF(2
8),
error correction encoding and decoding processing while taking 8 bits as the unit
becomes possible. As a result, the conformity with H.223 which is an existing scheme
can be ensured.
(25) In a receiving apparatus for communicating with a transmitting apparatus,
the transmitting apparatus generating a first parity signal formed of arbitrary
elements according to a first encoding rule with respect to a transmitting signal
formed of an arbitrary number of elements, generating a second parity signal formed
of an arbitrary number of elements according to a second encoding rule with respect
to at least a part of the transmitting signal and the first parity signal, and
generating and transmitting a transmitting encoded signal by combining the transmitting
signal and the first and second parity signals,
the receiving apparatus includes: a means for receiving the transmitting encoded
signal and outputting a received encoded signal including the first and second
parity signals; a first decoding means for conducting most likelihood decoding
on the received encoded signal including the first parity signal; a second decoding
means for conducting most likelihood decoding on a received encoded signal including
the first parity signal; a second decoding means for conducting most likelihood
decoding on a received encoded signal including the second parity signal; and a
means for calculating distance values respectively between decoded signals obtained
by the first and second decoding means and the received signal, and reproducing
the transmitting encoded signal on the basis of the decoded signal corresponding
to a shorter distance.
Owing to such a configuration, the received encoded signal including the first
parity signal and the received encoded signal including the second parity signal
are decoded by using the most likelihood decoding scheme having a high error correction
capability. In addition, on the basis of a decoded signal having higher reliability
out of the two decoded signals thus obtained, the transmitted encoded signal is
reproduced. As a result, highly reliable signal reproduction can be conducted.
(26) In a receiving apparatus for communicating with a transmitting apparatus,
the transmitting apparatus generating a first parity signal formed of arbitrary
elements according to a first encoding rule with respect to a transmitting signal
formed of an arbitrary number of elements, generating a second parity signal formed
of an arbitrary number of elements according to a second encoding rule with respect
to at least a part of the transmitting signal and the first parity signal, and
generating and transmitting a transmitting encoded signal by combining the transmitting
signal and the first and second parity signals,
the receiving apparatus includes: a means for receiving the transmitting encoded
signal and outputting a received encoded signal including the first and second
parity signals; a first amending and decoding means for amending the received encoded
signal including the first parity signal on the basis of a first amending signal,
then conducting most likelihood decoding on a resultant signal, outputting a decoded
signal together with information representing reliability of the decoded signal,
and using the reliability information as the first amending signal; a second amending
and decoding means for amending the received encoded signal including the second
parity signal on the basis of a second amending signal, then conducting most likelihood
decoding on a resultant signal, outputting a decoded signal together with information
representing reliability of the decoded signal, and using the reliability information
as the second amending signal; and a control means for causing the amending and
decoding processing to be repetitively conducted by the first amending and decoding
means a predetermined number of times and causing the amending and decoding processing
to be repetitively conducted by the second amending and decoding means a predetermined
number of times, and reproducing the transmitting encoded signal on the basis of
the received encoded signal, the first amendment, and the second amendment.
Owing to such a configuration, the received encoded signal including the first
parity signal and the received encoded signal including the second parity signal
are decoded by using the most likelihood decoding scheme having an input amending
function according to the reliability information. As compared with the case where
the most likelihood decoding is simply conducted, further highly reliable signal
reproduction can be implemented.
(27) In an information data multiplex transmission system for inserting a plurality
of kinds of information data having arbitrary information amounts into one packet
and conducting multiplex transmission,
the transmitting side includes: a first encoding means for generating a first
parity signal formed of arbitrary elements according to a first encoding rule with
respect to a first transmitting signal formed of an arbitrary number of elements;
a first interleaving means for altering order of elements of the first transmitting
signal; a second encoding means for generating a second parity signal formed of
arbitrary elements according to a second encoding rule with respect to a second
transmitting signal altered in element order by the first interleaving means; and
a means for generating and transmitting a transmitting encoded signal including
the first transmitting signal and the first and second parity
