Transmission Scheme for Text-Based Information
Description
The present application relates to a transmission scheme
for text-based information such as, for example, data-
carousel text-based information broadcasting an example for
which is the XML-based low-profile information service
Journaline (R).
Text-based information signals carrying text-based
information content distributed to information objects are
used, for example, in data-carousel text-based information
broadcasting systems, in data transmissions where the
textual information contents are transferred on demand, or
in address-based data transmissions directed to specified
addressees which may or may not ordered the transmission by
demand.
Data carousel text-based information broadcasting, for
example, enables text-based information to be distributed
to a huge amount of users while keeping the technical
overhead reasonably low. For example, no uplink or feedback
signals from the receivers to the broadcast transmitter is
necessary. In order to enable the users to individually
navigate through the information content provided by the
broadcast signal according to their personal preferences,
the whole information is divided-up into objects referring
to other objects, thereby enabling interactively navigating
through the resulting linked arrangement of objects. For
example, menu objects enable the user to select, among menu
items, in order to proceed from one object to the other.
When considering the transmission of a text-based
information signal, care should be taken to distinguish
between the transport layer on the one hand and the
application layer on the other hand. That is, the text-
based information service provides for the text information

objects into which the text-based information content is
distributed. Obviously, these information objects may have
different lengths. These information objects have to be
transmitted to the service recipients. This falls into the
responsibility of the transport layer system, i.e. the
system interfacing the service transmitter and the service
recipients/receivers. The transport layer defines the way
the data to be transmitted or transported is to be passed
on from the application layer to the transport layer and
how the data is then passed on from the transport layer to
the application layer at the recipient's side. For example,
the transport layer may expect to receive the data to be
transmitted in form of packets. Alternatively, the
transport layer may allow a stream of data to be passed on
to the transport layer at the transmission's side. In case
of text-based information transmission by way of
information objects, the service recipient expects to
receive the application layer data in units of information
objects. This, in turn, means that the transport layer has
to be able to cope with the maximum size of the information
objects, allowed by the text-based information service.
That is, the transport layer has to be defined such that
the information objects of maximum size fit into the
content section of the transport packet of the transport
layer, or the transport layer has to be able to handle
inbound information objects having a size greater than the
maximum size of the content section of the transport
packets with then, at the recipient's side, re-combining
the sub-portions of these information objects so that the
fragmented transport is transparent for the service
recipient.
This, however, means that the information service and the
respective service receivers are merely applicable in
connection with transport layer systems which comply with
the afore-mentioned requirements. This, however, restricts
the applicability of the respective service.

Thus, it is an object of the present invention to provide a
text-based information transmission scheme such that this
scheme harmonizes with a greater number of transport-layer
systems.
This object is achieved by a receiver according to claim 1,
a transmitter according to claim 3, a transport signal
according to claim 7, an application-layer unit according
to claim 5 or 6, a method according to claim 8 or 9 and a
computer-program according to claim 10.
The present invention is based on the finding that the
text-based information transmission complies with a greater
number of transport-layer systems when the fragmentation
and de-fragmentation of the information object is performed
at the application-layer side rather than at transport-
layer domain. By this manner, the text-based information
service is not restricted to transport-layer systems
accommodating the maximum size of the information objects.
Rather, it is possible to adjust the fragmentation size of
the fragments into which the information objects are
fragmented to the maximum transport packet content section
size offered by the transport layer within the application
layer. The fragment size may even vary in a time-varying
manner responsive to instructions from the transport layer
posed onto the transport layer in consequence of time-
varying transmission channel characteristics, for example.
Preferred embodiments of the present invention are
described in the following in more detail with regard to
the Figs. In particular:
Fig. la a schematic diagram of an illustrative
application-layer system;
Fig. lb a schematic diagram of a illustrative tree-
structure of information objects;

Fig. 2 a block diagram for a text-based information
signal according to an embodiment;
Fig. 3 a block diagram of a receiver for a text-based
information signal according to an embodiment;
and
Fig. 4a and b, schematic diagrams of exemplary ways of
transporting the fragment sections plus
associated fragment header.
Fig. la shows an application-layer system as an example
where the present invention may be utilized. The
application-layer system of Fig. la is a text-based
information service system where a text-based information
signal carrying text-based information content is provided
from a transmission side 10 to a receiving side 12. The
text-based information content may, for example, comprise
news, advertisements or other textual information. The
text-based information content is distributed to a
plurality of information objects 14. As shown in Fig. la,
each object may, for example, comprise an object header 15
and an object content section 18. Further, each object 14
may have associated therewith a unigue object ID among a
plurality of different object IDs. This object ID may, as
shown in Fig. la, be contained within the object header, as
shown at reference sign 20. The text-based content of the
respective object 14 is contained by the object content
section 18 as shown at 22. Some of the objects 14 may have
links to other objects. Such a link item is shown in Fig.
la at reference sign 24 as being included within the object
content section 18. The link item 24 comprises a pointer 26
pointing or referring to an object ID different from the
object ID 20 of the object to which pointer 26 belongs, as
well as a label 28. Both text portions 22 as well as labels
28 are dedicated for being presented to the user at the
receiving side 12. As it is described in more detail below,
the user at the receiving side 12 is given the opportunity

to activate the link item 24 represented by the label 28,
thereby navigating from the current object with a current
object ID 20 to the object to which the pointer 26 of the
activated link item 24 refers. The latter aspect is
described in more detail below with respect to Fig. lb.
Of course, further syntax elements may be comprised by the
object header 16 and/or the object content section 18
and/or the object itself. For example, the object header 16
may comprise the syntax element 30 specifying the type or
structure of the object content section 18. For example,
manual objects, pure text objects, list objects and so
forth may be distinguished.
As shown in Fig. la, the transmission side 10 comprises a
provider 32 being configured to provide the objects 14 to
the receiving side. Provider 32 may be configured to
provide the object 14 to the receiving side 12 in a data-
carousel manner. That is, provider 32 may be configured to
cycle through the object IDs wherein the repetition rate at
which a certain object ID is visited, may be different
between the individual object IDs. Alternatively, provider
32 may be configured to provide the objects 14 to the
receiving side 12 on demand, i.e. responsive to a request
from the receiving side 12 to provide a certain object with
a determined object ID to the receiving side 12.
At the receiving side 12, a processor 34 is configured to
receive the information objects 14 provided by provider 32
and to parse them and handle them according to the
specification within the object header 16 as it is
described in more detail below. Several devices are
connected with processor 34. These devices comprise a
presentation device 36, an input device 38 and a memory 40.
In particular, processor 34 is configured to present the
textual content within the object content section 18 of an
object having a currently selected object ID 20 to the user
via the presentation device 36. The presentation device 36

may, for example, comprise a display, such as a graphical
display or text display. However, it is also possible that
the presentation device 36 comprises a loudspeaker with
processor 34 performing a text-to-speech conversion in
presenting the textual content of an object to the user. If
present, processor 34 presents the label 28 of link items
24 to the user. The user, in turn, is given the opportunity
to activate or select such link item 24 presented via
presentation device 36, by means of the input device 38.
For example, the input device 38 may comprise a toggle
switch such as, for example, a 4-toggle switch, or a
rotating knob or may comprise a touch screen capability, or
a combination thereof. Even a speech recognition input
capability enabling speech control would be feasible. In
particular, in case of more than one link item 24 being
present in the currently selected and presented object,
processor 34 may be configured to highlight an actually
selectable link item among these link items with the user
being able to, via the input device 38, change the
currently selectable link item and activate the currently
selectable link item, respectively. Responsive to a
selection of a link item, processor 34 appoints the object
ID referred to by the pointer 26 of the selected link item
24, as the newly-selected object ID and obtains an object
with that object ID and presents its textual content to the
user via the presentation device 36. In case of a data-
carousel, processor 34 may obtain the object having the
newly-selected object ID from the data-carousel text-based
information signal provided by provider 32 or a precached
version thereof stored within an object cache 42 within
memory 40. Alternatively, processor 34 may obtain the
information object 14 having the newly-selected object ID
by requesting same from provider 32.
In the above-described text-based information service
system, the user is given the opportunity to navigate
through the text-based information content of that service.
To illustrate this, reference is made to Fig. lb. Fig. lb

shows an illustrative tree structure of information objects
14, the tree structure being defined by the pointers 26 or
link items 24. In particular, Fig. lb distinguishes between
objects 50 comprising one or more link items 24 which are
illustrated by rectangles having rounded corners and being
marked with "M", and objects 52 having right-angled corners
being marked with "T". As already denoted above, each
object 14 is assigned a unique object ID. In other words,
the object 14 shown in Fig. lb each has a unique object ID
associated therewith, which is different from the object ID
of any other object 14 as shown in Fig. lb. One of the link
objects 50 may be associated with a specific object ID
which is, in case of Fig. lb, exemplarily the object ID
0x0000. This object 54 forms a root of the tree structure
56 into which the objects 14 are structured by the pointers
28. A specific object ID of the root object 54 may be known
at the receiving side 12 and may be initially presented to
the user by processor 34 upon, for example, switching on
processor 34. The root object 54 forms a first hierarchy
level of the hierarchical tree structure 56. The pointers
26 of the link items 24 of the root object 54 point to
objects 14 having different object IDs forming a second
hierarchy level as illustrated by arrows starting from root
object 54 and extending to objects 14 of the second
hierarchy level. Objects 50 of the second hierarchy level
in turn, have link items with pointers pointing to objects
having a respective different object ID and so forth. The
"hierarchy level" of an object 14 may be defined as the
shortest possible path from the root object 54 to the
respective object. Although the range of hierarchy levels
may be unrestricted, according to an embodiment, the number
of hierarchy levels may be restricted to a maximum value,
such as 20 hierarchy levels. Similarly, the number of link
items per object 50 may be unlimited or may be restricted
to some maximum value. As shown in Fig. lb, an object 14
may be referred to or pointed to by respective link items
of more than one object 50. Further, the pointer of the
link item of a certain object 50 is not restricted to point

to an object of the subsequent hierarchy level. Rather, the
object 50 of a certain hierarchy level may have a link item
pointing to an object having a different object ID within a
lower hierarchy level as it is illustrated by dotted lines
in Fig. lb.
With additional reference to Fig. la, processor 34 is
configured to assist the user in navigating through the
tree 56 of objects. In particular, processor 34 may be
configured to monitor a data-carousel signal provided by
provider 32 or may look-up in the object cache 42, to
detect an object 14 having a currently selected object ID
associated therewith and to render a presentation to the
user representing the content of this information object
via presentation device 36. If the currently presented
object comprises a link item 24, the user is prompted to
select this or to select one of the link items 24 of the
currently presented object. In particular, the user is able
to select one of several link items by use of the input
device 38. Upon the selection of a certain link item by the
user, processor 34 appoints the object ID referred to by
this link item 24 as a newly-selected object ID, whereupon
processor 34 monitors, for example, a data-carousel signal
provided by provider 32 or a cached version thereof stored
in cache 32, in order to present the textual content of
this object to the user and so forth. As outlined before,
according to an alternative embodiment, processor 34
requests a newly-selected object ID from provider 32
instead of using a data-carousel signal.
Processor 34 may use the memory 40 in order to keep track
of the recently visited object IDs in their visiting order.
In other words, processor 34 may store a path history 58 in
memory 40, the path history 58 comprising a list of
traversed object IDs when navigating from the route object
54 to any other object 14. The path history 58 may be
restricted to a certain number of object IDs, with this
number being, for example, equal to the maximum number of

hierarchy levels or greater than the latter. Processor 34
may use the path history 58 in order to obtain the object
ID of the object 50 from where the user reached the
currently-displayed object, upon the user requesting
returning to this previous object 50 by use of, for
example, input device 38. Processor 34 may be configured to
shorten the history path 58 in case a newly-selected object
ID is already present in the path history 58. Further,
processor 34 may be configured to remove the oldest or any
other object ID from the path history 58 upon the number of
different object IDs in the path history exceeding the
maximum number.
The description above was restricted to the application-
layer system. That is, the above description was restricted
to the structure and the handling of the information object
into which the text-based information content is
distributed. Figs. 2 and 3 show examples for a transmitter
and receiver, respectively, which are configured to
implement a text-based information service as described
above with respect to Figs, la and lb, with the transmitter
and receiver also comprising components concerning the
transport layer. Thus, Figs. 2 and 3 also show the
interface between application layer on the one hand and
transport layer on the other hand.
Fig. 2 shows an example of a transmitter 70. The
transmitter 70 comprises an application layer unit 72 and a
transport layer unit 74. The application layer unit
comprises an object provider 74, which corresponds to or is
functionally identical with provider 32 of Fig. la.
Further, application layer unit 72 comprises a fragmenter
76 and a header adder 78. Object provider 74, fragmenter 76
and header adder 78 are connected in series to transport
layer unit 74, in the order mentioned.
As already described above with respect to Fig. la, object
provider 74 provides objects 14 and outputs them to

fragmenter 76. In the example of Fig. 2, each object
comprises in addition to object header 16 and object
content section 18 additional data, namely an additional
header 80 and redundancy data 82. Object 14 may be, for
example, a MSC data group with the additional header 80
being an MSC data group header, the redundancy data 82
being an redundancy code word determined from and enabling
error detection or, alternatively, even error correction of
MSC data group header 80, as well as the MSC data group
field consisting of object header 16 and object content
section 18. In addition to the information contained in
object header 16, MSC data group header 80 may identify the
text-based information service to which the textual content
within the object content section 18 belongs, in order to
enable to distinguish information object 14 from objects
belonging to another service. It should, however, be
emphasized that the just-mentioned portions 80 and 82 are
merely optional and may be left off. Further, although in
Fig. 2 portions 80 and 82 are described to be included
within the information object 14, it would also be possible
to interpret the information object 14 to be restricted to
the data group field of an MSC data group only with the
reference sign 14 of Fig. 2 then, denoting an MSC data
group. As, however, sections 80 and 82 are merely optional,
the units provided by object provider 74 are denoted
information objects 14 as a whole.
Thus, fragmenter 76 receives data from object provider 74
in units of information objects 14. In particular,
fragmenter 76 receives a sequence of information objects 14
from object provider 74. The fragmenter 76 is responsible
for guaranteeing that the transport layer unit 71 is able
to handle the transport and packetizing of the information
objects 14. To this end, fragmenter 76 checks as to whether
the information object 14 exceeds a predetermined length
which, in turn, may be predetermined or may be, in a time-
varying manner, prescribed by the transport layer unit 74
depending on physical circumstances such as a current

physical channel situation or the like. If the fragmenter
76 determines that the length of a current information
object 14 exceeds the threshold length, then fragmenter 76
splits-up the information object into a sequence of
fragments 14a and 14b so as to be, for example, as long as
possible as allowed by the threshold length, thus forming a
sub-sequence of a sequence of fragment sections at the
output of fragmenter 76 for this information object 14. As
just mentioned, the fragments sections belonging to the
same object may have different lengths - not only the last
one relative to the preceding ones but also the fragment
sections preceding the last one, may differ in length among
each other.
Header adder 78 receives the sequence of fragment sections
and provides each fragment section with an associated
fragment header 84a and 84b, respectively, enabling, by
solely relying on the fragment headers 84a and 84b, a de-
fragmentation of fragment sections 14a, 14b to reconstruct
the sequence of information objects 14 from the sequence of
fragment sections 14a and 14b. In particular, the fragment
headers 84a, 84b may be determined such that same indicate
as to whether the fragment section they belong to, is the
first fragment section of a sub-sequence of fragment
sections forming, together, an information object, as to
whether the fragment section it belongs to, is the last
fragment section of a sub-sequence of fragment sections
forming, together, an information object, and enable to
check, solely based on the fragment headers, as to whether
the fragment sections completely reconstruct the
information object or as to whether a fragment section is
missing.
As shown in Fig. 2, each fragment header 84a, 84b may, for
example, comprise a first-flag, a last-flag 88 and a
continuity index 90. The first flag 86 may be enabled if
the fragment section 14a comprises a first fragment of an
information object 14 with, otherwise being disabled.

Similarly, the last-flag 88 may be enabled if the fragment
section 14a associated with fragment header 84a comprises a
last fragment of an information object, with, otherwise,
being disabled. A continuity index 90, in turn, may
comprise a counter that starts from zero at fragment
sections 14a comprising the first fragment of an
information object and is incremented by one for each
subsequent fragment section 14b comprising a fragment of
this information object. The first-flag 86 and last-flag 88
may be one-bit symbols. The continuity index 90 may, for
example, be a six-bit counter value. If an information
object is fragmented in more than 26 = 64 fragment
sections, the counter may overflow or re-start at zero
which could be regarded as normal behaviour at the
receiving side as will be described in more detail below.
In the following, an example for a sequence of fragment
headers is listed for the illustrative case that three
consecutive information objects are fragmented into one,
four and two fragments, respectively.

The transport layer unit 74 receives the sequence of
fragment sections 14a and 14b each having associated
therewith a fragment header 84a and 84b, respectively, and
assumes responsibility for the transportation to the
receiving side. Due to the fragmentation performed by the
fragmenter 76 and header adder 78, the transport layer unit
74 is not restricted to one being able to cope with the

maximum length of the information objects 14. Rather, a
transport layer unit 74 may use any transport layer scheme
available. For example, the size limit for the information
object 14, such as in form of MSC data groups, may be 4 kb.
Thus, without fragmenter 7 6 and header adder 78, a
transport layer unit 74 would have to be able to cope with
objects of that size. Due to the fragmentation, however,
the transport layer unit 74 is not restricted to such a
transport layer scheme. For example, the transport layer
unit 74 may, in this case, use any of the DAB, DRM, HD
radio, Worldspace or any other transport layer system. In
fact, the transport layer unit 74 forms a transport signal
92 out of the sequence of fragment sections 14a, 14b with
the associated fragment headers 84a, 84b in any possible
way with, however, logically maintaining the structure of
this incoming sequence into the units or fragment section
plus fragment header. For example, as shown in Fig. 4a, a
transport layer unit 74 may packetize each fragment section
plus as associated fragment header, i.e. each transport
unit, individually into one transport packet content
section 94 having, itself, a transport packet header 96
associated therewith. Alternatively, the transport layer
unit 92 transports the sequence of fragment sections plus
fragment headers as a stream with synchronization headers
indicating the borders between consecutive pairs of
fragment section and associated fragment header. Even
alternatively, the transport layer unit 74 may be able to
transport a pair of fragment section plus fragment header
distributed to more than one transport packets as
illustrated in Fig. 4b. The data transfer itself, may be
performed in any way such as in form of a terrestrial
signal 92 or a satellite signal or the like. Moreover, as
already denoted above, the data transmission 92 may be a
broadcast signal such as, for example, a wireless
transmission broadcast signal, or the transmission aims to
specific recipients indicated by a respective address such
as, for example, in case of sending the objects on demand.

Fig. 3 shows a possible receiver for receiving a transport
signal 92. The receiver of Fig. 3 comprises a transport
layer unit 110 and an application layer unit 112 with the
latter comprising an extractor 114, a de-fragmenter 116 and
an object handler 118 with the object handler comprising,
for example, processor 34 or processor 34 of Fig. la and
one or more of the elements connected therewith, as shown
in Fig. la.
The transport layer unit 110 receives a transport signal
and reconstructs therefrom a sequence of transport units
with each transport unit corresponding or being equal to a
pair of fragment headers plus fragment section. The
application layer unit 112 of the receiver of Fig. 3 has
the de-fragmenter 116 being connected between the extractor
114 and the object handler 118. Extractor 114 receives from
the transport layer unit 110 the sequence of transport
units and extracts therefrom for each transport unit a
respective fragment header 120 and fragment section 122.
The de-fragmenter 116, in turn, de-fragments the forwarded
sequence of the fragment sections by use of the fragment
headers to obtain the information objects with, at least,
for a part of the information objects, composing the
respective information object 14 from the respective sub-
sequence of fragment sections. The object handler 118, in
turn, uses the thus obtained information objects 14 in the
way already discussed above with respect to Figs, la and
lb.
In particular, the fragmenter 116 uses the fragment headers
in order to check as to whether a fragment of a fragmented
information object 14 has become lost somewhere between the
transport layer unit 74 of the transmitter and the
transport layer unit 110 of the receiver. To this end, the
de-fragmenter 116 firstly checks the fragment header of a
current fragment section of a current transport unit
received from transport layer unit 110 as to whether the
associated fragment section comprises a first fragment of

an information object. If so, the fragmenter 116 checks the
fragment header of the current fragment section as well as
the fragment headers associated with a run of fragment
sections immediately succeeding the current fragment
section as to whether there is a discontinuity indicating
that a fragment is missing thereby preventing rebuilding or
composing an information object having been fragmented. The
afore-mentioned run of consecutive fragment sections is
determined to end either at a fragment section preceding a
fragment section with a fragment header indicating that its
fragment section comprises a first fragment of an
information object, or at a fragment section having a
fragment header associated therewith which indicates that
the respective fragment section comprises a last fragment
of an information object, whatever occurs first in the
sequence of fragment sections. Both conditions normally
apply as can be seen, for example, from the fifth and sixth
fragment headers in the above table among which the fifth
fragment header belongs to fragment section forming the
just-mentioned run end.
In order to illustrate this in more detail, reference is
made to the above exemplified list of fragment headers.
Imagine, for example, the current fragment section is the
one having the second fragment header in this table, if
none of the fragment sections with associated fragment
header is lost, the run of consecutive fragment sections
extends from the third to fifth fragment header/fragment
section pair as the fifth fragment header has the last-flag
enabled. If, however, the fifth fragment header plus
fragment section would have been lost in transmission, for
example, the run of consecutive fragment sections mentioned
before would end at the fourth fragment section as this
fragment section precedes the immediately following sixth
fragment header having the first-flag enabled, and since
the first fragment header having the last-flag enabled
follows even later.

If the check reveals that some intermediate fragment
section has been lost of the afore-mentioned run or the run
ends at a fragment section that immediately precedes a
fragment section having a fragment header with the first-
flag being enabled, but that has a fragment header the
last-flag of which is not enabled, the fragmenter 116
discards the current fragment section plus the run of
immediately following fragment sections and resumes the de-
fragmentation of the fragment section immediately following
the run of fragment sections.
If, however, the check result is that no fragment is
missing, the fragmenter 116 composes the information object
from the current fragment section and the run of
immediately following fragment sections. Optionally, the
fragmenter 116 checks the redundancy information 82 in
order to determine as to whether the information object re-
composed is correct.
As a further escape mechanism, the fragmenter 116 may limit
the length of run of consecutive fragment sections such
that the maximum size for information objects is still
fulfilled. If, for example, the fragment section having a
fragment header having the first-flag being enabled, is
followed by a run of fragment sections ending as defined
above, has a sum of the length of these fragment sections
exceeding the maximum length for the information objects,
it is clear that these fragments must belong to different
information objects and that any fragment section must have
been lost. In this case, the fragmenter stops the assembly
of fragments at this maximum size, such as at 4 kb, and
discards the fragment sections processed so far to resume
the processing as denoted above with the next fragment
section with a fragment header having the first-flag
enabled.
In particular, when using the type of fragment header
having a first-flag, a last-flag and a continuity index 90,

the fragmenter 116 may operate as follows. Firstly, the de-
fragmenter 116 may wait for the first-flag being enabled.
Then, the fragmenter 116 starts collecting the fragment
sections. Continuously, the fragmenter 116 checks the
continuity index of the following fragment headers in order
to check as to whether there is a discontinuity in the
counter indicated by the continuity index 90. If there is a
discontinuity detected, the fragmenter 116 discards all
fragments and restarts the operation with the next fragment
header having a first-flag enabled. If there is a first-
flag detected, the fragmenter 116 knows that a fragment
header with the last-flag being enabled has been missed,
and therefore, the fragmenter 116 discards the fragment
sections collected so far and restarts with the next
fragment header having a first-flag being enabled. If,
however, the fragmenter 116 reaches the fragment header
having a last-flag being enabled before the first
occurrence of a fragment header with the first-flag being
enabled, the fragmenter 116 passes on the information
object 14 composed from the collected fragment sections to
the object handler which, in turn, checks, optionally, the
redundancy information 82 and, if correct, further
processes the information object according to application
layer preferences as briefly described above. As indicated
above, the collection may be interrupted as soon as the sum
of currently collected fragment section lengths exceeds the
limit for information objects.
It is noted that the present invention is neither
restricted to carousel based data transmission nor
broadcasting. Rather, as was already indicated above,
differing from the above outlined description, the
embodiments outlined above may also be applied to data
transmissions where the data objects are transferred on
demand. Similarly, differing from the above outlined
description, the above embodiments may be transferred to
address-based data transmissions directed to specified

addressees which may or may not ordered the transmission by
demand.
In other words, in accordance with an embodiment of the
present invention, a receiver for a text-information signal
carrying text-based information content being distributed
to information objects, may comprise a transport-layer unit
for receiving a transport signal so as to obtain a sequence
of transport units and an application-layer unit. The
application-layer unit comprises an extractor for
inspecting each transport unit and extracting a fragment
header and a corresponding fragment section therefrom so as
to obtain a sequence of fragment sections with associated
fragment headers, a de-fragmenter for de-fragmenting the
sequence of fragment sections by use of the fragment
headers to obtain the information objects with, at least
for a part of the information objects, composing the
respective information object from a sub-sequence of
fragment sections of the sequence of fragment sections, and
an information object handler for parsing the information
object to obtain an object header and an object content
section and processing the information objects according to
the object header. Optionally, the transport signal may
have each transport unit contained therein in a packetized
form distributed to one or more than one transport packet,
each transport packet comprising a transport packet header
and a transport packet data section, wherein the transport-
layer unit may be configured to inspect, for each transport
packet, the transport packet header in order to obtain a
payload extraction information on a length of the transport
content section or on a payload portion within the
transport packet section and to extract and forward, by use
of the payload extraction information, merely bits of the
transport packet to the application-level unit, which
concern at least one of the fragment header and the
fragment section.

Similarly, in accordance with an embodiment of the present
invention, a transmitter for a text-based information
signal carrying text-based information content being
distributed to information objects, may comprise an
application-layer unit and a transport-layer unit. The
application-layer unit may comprise a fragmenter for
fragmenting the information objects into a sequence of
fragment sections with, at least for a part of the
information objects, fragmentising the respective
information objects into a sub-sequence of fragment
sections of the sequence of fragment sections, and a header
adder for providing each fragment section with a fragment
header allowing a de-fragmentation of the fragment sections
to obtain the information objects, each fragment section
and the fragment header the respective fragment section is
associated with, forming a transport unit. The transport-
layer unit is responsible for transmitting, transport unit-
wise, the sequence of transport units within a transport
signal. Optionally, the transport-layer unit may be
configured to transmit the sequence of transport units
within the transport signal such that the transport signal
has each transport unit contained therein in a packetized
form distributed to one or more than one transport packet,
each transport packet comprising a transport packet header
and a transport packet data section, the transport packet
header comprising a payload extraction information on a
length of the transport content section or on a payload
portion within the transport packet section indicating the
bits of the transport packet which concern at least one of
the fragment header and the fragment section.
Depending on an actual implementation, the inventive
broadcast concept can be implemented in hardware or in
software. Therefore, the present invention also relates to
a computer program, which can be stored on a computer-
readable medium such as a CD, a disk, DVD, a memory stick,
a memory card or a memory chip. The present invention is,

therefore, also a computer program having a program code
which, when executed on a computer, performs the inventive
method described in connection with the above figures.
While this invention has been described in terms of several
preferred embodiments, there are alterations, permutations,
and equivalents which fall within the scope of this
invention. It should also be noted that there are many
alternative ways of implementing the methods and
compositions of the present invention. It is therefore
intended that the following appended claims be interpreted
as including all such alterations, permutations, and
equivalents as fall within the true spirit and scope of the
present invention.
Furthermore, it is noted that all steps indicated in the
flow diagrams are implemented by respective means in the
receiver, transmitter and units, respectively, and that the
implementations may comprise subroutines running on a CPU,
circuit parts of an ASIC or the like.

we claim:
1. Application-layer unit (112) for receiving a text-information signal carrying text-
based information content being distributed to information objects (14) in form
of a sequence of transport units comprising:
an extractor (114) for inspecting each transport unit and extracting a fragment
header (84a) and a corresponding fragment section (14a) therefrom so as to
obtain a sequence of fragment sections with associated fragment headers;
a de-fragmenter (116) for de-fragmenting the sequence of fragment sections
(14a) by use of the fragment headers (84a) to obtain the information objects (14)
with, at least for a part of the information objects (14), composing the respective
information object (14) from a sub-sequence of fragment sections (14a) of the
sequence of fragment sections; and
an information object handler (118) for parsing the information object to obtain
an object header (16) and an object content section (18) and processing the
information objects according to the object header (16).
wherein the fragment headers (84a) associated with the sequence of the fragment
sections (14a) are configured such
that the fragment headers reveal as to whether the associated fragment
section is the first fragment section of a sub-sequence of fragment
sections into which an information object is fragmented;
the fragment headers reveal as to whether the associated fragment section
is the last fragment section of a sub-sequence of fragment sections into
which an information object is fragmented; and
the fragment headers of a sub-sequence of fragment sections into which
an information object is fragmented have a continuity index continuously
changing from the first to the last fragment section of the sub-sequence
of fragment sections,

wherein the de-fragmenter is configured to perform the de-fragmentation by
a) checking the fragment header with which a current fragment section is
associated as to whether the current fragment section is the first fragment
section of a sub-sequence of fragment sections,
b) if so, check the fragment header of the current fragment section and the
fragment headers associated with a run of fragment sections immediately
following the current fragment section and ending at the fragment section
immediately preceding a fragment section having a fragment header
associated therewith which indicates that its fragment section is the first
fragment section of a sub-sequence of fragment sections, or at a fragment
section that has a fragment header associated therewith that indicates that
its fragment section is the last fragment section of a sub-sequence of
fragment sections, whatever occurs first in the sequence of fragment
sections, as to whether there is a discontinuity in the continuity index of
these fragment headers;
c) if there is a discontinuity in the continuity index of these fragment
headers or if the run ends at a fragment section that has a fragment
header associated therewith that does not indicate that its fragment
section is the last fragment section of a sub-sequence of fragment
sections, discarding the current fragment section on the run of fragment
sections and resuming the de-frequentation at step a) with the fragment
section immediately following the run of fragment sections as the current
fragment section; and
d) otherwise, composing the information object from the current fragment
section and the run of fragment sections.
2. Receiver for a text-information signal carrying text-based information content
being distributed to information objects (14), comprising:
a transport-layer unit (110) for receiving a transport signal (92) so as to obtain a
sequence of transport units;
an application-layer unit (112) according to claim 1.

3. Application-layer unit (72) for transmitting a text-based information signal
carrying text-based information content being distributed to information objects
in form of a sequence of transport units within a transport signal (92),
comprising:
a fragmenter (76) for fragmenting the information objects (14) into a sequence
of fragment sections (14a) with, at least for a part of the information objects
(14), fragmentising the respective information objects into a sub-sequence of
fragment sections (14a) of the sequence of fragment sections; and
a header adder (78) for providing each fragment section (14a) with a fragment
header (84a) allowing a de-fragmentation of the fragment sections (14a) to
obtain the information objects (14), each fragment section (14a) and the
fragment header (84a) the respective fragment section (14a) is associated with,
forming a transport unit,
wherein the header adder (78) is configured such that fragment headers (84a)
associated with the sequence of the fragment sections (14a) are configured such
that the fragment headers reveal as to whether the associated fragment
section is the first fragment section of a sub-sequence of fragment
sections into which an information object is fragmented;
the fragment headers reveal as to whether the associated fragment section
is the last fragment section of a sub-sequence of fragment sections into
which an information object is fragmented; and
the fragment headers of a sub-sequence of fragment sections into which
an information object is fragmented have a continuity index continuously
changing from the first to the last fragment section of the sub-sequence
of fragment sections.
4. Transmitter for a text-based information signal carrying text-based information
content being distributed to information objects, comprising:
an application-layer unit (72)according to claim 3; and

a transport-layer unit (74) for transmitting, transport unit-wise, the sequence of
transport units within a transport signal (92).
5. A transport signal including a text-based information signal carrying text-based
information content being distributed to information objects in form of a
sequence of transport units, each transport unit being comprising a fragment
header (84a) and a corresponding fragment section (14a), the fragment headers
(84a) allowing a de-fragmentation of the sequence of fragment sections (14a) to
obtain the information objects (14) therefrom, wherein, at least for a part of the
information objects (14), the respective information object (14) is distributed to a
sub-sequence of fragment sections (14a) of the sequence of fragment sections,
wherein the fragment headers (84a) associated with the sequence of the fragment
sections (14a) are configured such
that the fragment headers reveal as to whether the associated fragment
section is the first fragment section of a sub-sequence of fragment
sections into which an information object is fragmented;
the fragment headers reveal as to whether the associated fragment section
is the last fragment section of a sub-sequence of fragment sections into
which an information object is fragmented; and
the fragment headers of a sub-sequence of fragment sections into which
an information object is fragmented have a continuity index continuously
changing from the first to the last fragment section of the sub-sequence
of fragment sections.
6. Method for, at an application layer, receiving a text-information signal carrying
text-based information content being distributed to information objects (14) in
form of a sequence of transport units comprising:
inspecting each transport unit and extracting a fragment header (84a) and a
corresponding fragment section (14a) therefrom so as to obtain a sequence of
fragment sections with associated fragment headers;
de-fragmenting the sequence of fragment sections (14a) by use of the fragment
headers (84a) to obtain the information objects (14) with, at least for a part of the
information objects (14), composing the respective information object (14) from

a sub-sequence of fragment sections (14a) of the sequence of fragment sections;
and
parsing the information object to obtain an object header (16) and an object
content section (18) and processing the information objects according to the
object header (16),
wherein the fragment headers (84a) associated with the sequence of the fragment
sections (14a) are configured such
that the fragment headers reveal as to whether the associated fragment
section is the first fragment section of a sub-sequence of fragment
sections into which an information object is fragmented;
the fragment headers reveal as to whether the associated fragment section
is the last fragment section of a sub-sequence of fragment sections into
which an information object is fragmented; and
the fragment headers of a sub-sequence of fragment sections into which
an information object is fragmented have a continuity index continuously
changing from the first to the last fragment section of the sub-sequence
of fragment sections,
wherein the de-fragmentation is performed by
a) checking the fragment header with which a current fragment section is
associated as to whether the current fragment section is the first fragment
section of a sub-sequence of fragment sections,
b) if so, check the fragment header of the current fragment section and the
fragment headers associated with a run of fragment sections immediately
following the current fragment section and ending at the fragment section
immediately preceding a fragment section having a fragment header
associated therewith which indicates that its fragment section is the first
fragment section of a sub-sequence of fragment sections, or at a fragment
section that has a fragment header associated therewith that indicates that
its fragment section is the last fragment section of a sub-sequence of
fragment sections, whatever occurs first in the sequence of fragment

sections, as to whether there is a discontinuity in the continuity index of
these fragment headers;
c) if there is a discontinuity in the continuity index of these fragment
headers or if the run ends at a fragment section that has a fragment
header associated therewith that does not indicate that its fragment
section is the last fragment section of a sub-sequence of fragment
sections, discarding the current fragment section on the run of fragment
sections and resuming the de-frequentation at step a) with the fragment
section immediately following the run of fragment sections as the current
fragment section; and
d) otherwise, composing the information object from the current fragment
section and the run of fragment sections.
7. Method for, at an application layer, transmitting a text-based information signal
carrying text-based information content being distributed to information objects
in form of a sequence of transport units within a transport signal (92),
comprising:
fragmenting the information objects (14) into a sequence of fragment sections
(14a) with, at least for a part of the information objects (14), fragmentising the
respective information objects into a sub-sequence of fragment sections (14a) of
the sequence of fragment sections; and
providing each fragment section (14a) with a fragment header (84a) allowing a
de-fragmentation of the fragment sections (14a) to obtain the information objects
(14), each fragment section (14a) and the fragment header (84a) the respective
fragment section (14a) is associated with, forming a transport unit,
wherein the provision of each fragment section (14a) with a fragment header
(84a) is performed such that fragment headers (84a) associated with the
sequence of the fragment sections (14a) are configured such
that the fragment headers reveal as to whether the associated fragment
section is the first fragment section of a sub-sequence of fragment
sections into which an information object is fragmented;

the fragment headers reveal as to whether the associated fragment section
is the last fragment section of a sub-sequence of fragment sections into
which an information object is fragmented; and
the fragment headers of a sub-sequence of fragment sections into which
an information object is fragmented have a continuity index continuously
changing from the first to the last fragment section of the sub-sequence
of fragment sections.
8. Computer program having instructions for performing, when running on a
computer, a method according to claim 6 or 7.

A text-based information transmission is made complying
with a greater number of transport-layer systems by
performing the fragmentation and de-fragmentation of the
information object at the application-layer side rather
than at transport-layer domain. By this manner, the text-
based information service is not restricted to transport-
layer systems accommodating the maximum size of the
information objects. Rather, it is possible to adjust the
fragmentation size of the fragments into which the
information objects are fragmented to the maximum transport
packet content section size offered by the transport layer
within the application layer. The fragment size may even
vary in a time-varying manner responsive to instructions
from the transport layer posed onto the transport layer in
consequence of time-varying transmission channel
characteristics, for example.