FIELD OF THE DISCLOSURE
[0001] The present disclosure relates to a transmitter and a corresponding meth¬
od for communicating data using at least two separate RF channels. The present disclosure
relates further to a receiver and a corresponding method for receiving data using at least
two separate RF channels.
DESCRIPTION OF RELATED ART
[0002] Channel bundling of multiple, separate RF channels to enable total ser¬
vice data rates that exceed the net capacity of a single RF channel is generally known. For
instance, channel bundling may be applied above the physical layer, i.e. upper layer
solutions take care to split the overall data stream on transmitter side into portions that fit
to the capacity of the different single RF channels. Upper layer signaling may be provided
that allows the data recombination of the different RF channels in a sorted and stream type
consistent way. Channel bundling is processed in a transparent way for all involved RF
channels, i.e. the output stream on receiver side is equal to the corresponding input stream
on transmitter side. RF channels can be located at any channel frequencies, not necessarily
adjacent to each other.
[0003] In an ATSC3.0 system it is proposed that each RF channel is handled as a
standalone ATSC 3.0 signal. There are no special measures required on the physical layer
for bundled channels such as additional guard bands, additional pilots, synchronization etc.
Especially the concept of RF channel bundling allows reusing multiple existing LDPC
encoder and decoder as well as standard RF tuners, which helps to reduce the overall
complexity and simplifies the introduction of high data rate services beyond the capacity of
a single RF channel.
[0004] In all proposed approaches stream partitioning on transmitter (Tx) side as
well as stream recombination (or also denoted as joint BB (baseband packet) de-framing in
some figures) on receiver (Rx) side is performed outside the physical layer. The known
solution has a significant drawback: As the different channels are completely decoupled,
the overall performance of the large input stream suffers from different channel conditions
on different RF channels. The main reason is that the transmitter as well as the receiver for
every allocated RF channel deploys an own, independent FEC (Forward Error Correction)
encoder and decoder. If one or several channels suffer from insufficient SNR or other
channel impairments for correct data decoding, the overall recombined stream would still
result in a corrupted data stream with errors.
[0005] The "background" description provided herein is for the purpose of
generally presenting the context of the disclosure. Work of the presently named
inventor(s), to the extent it is described in this background section, as well as aspects of the
description which may not otherwise qualify as prior art at the time of filing, are neither
expressly or impliedly admitted as prior art against the present disclosure.
SUMMARY
[0006] It is an object to provide a transmitter and a corresponding method for
communicating data using at least two separate RF channels which particularly allow a
relatively simple and scalable implementation, support bundling of distant and neighboring
channels, provide additional frequency diversity, provide SNR averaging and work for
single and multiple data streams. It is a further object to provide a corresponding receiver
and method for receiving data using at least two separate RF channels. It is a still further
object to provide a corresponding computer program and a non-transitory computerreadable
recording medium for implementing said methods.
[0007] According to an aspect there is provided a transmitter for communicating
data using at least two separate RF channels, said transmitter comprising:
a data stream partitioner configured to partition a data stream of data to be commu
nicated into two or more stream partitions,
two or more modulators configured to each receive a stream partition and to
generate modulated data from the received stream partition, and
an interleaver configured to assign the modulated data generated by a modulator
from a received stream partition to different RF channels for transmission.
[0008] According to a further aspect there is provided receiver and a correspond¬
ing method for receiving data using at least two separate RF channels, said receiver
comprising:
a deinterleaver configured to receive data of a received data stream via at least two
separate RF channels, wherein the data of stream partitions of the data stream are transmit
ted via the at least two RF channels, and to assign the data belonging to the same stream
partition transmitted via different RF channels to different demodulators,
two or more demodulators configured to each receive data of a stream partition and
to generate demodulated data from the received data of the stream partition,
a data stream combiner configured to combine the demodulated data of the two or
more demodulators into the data stream.
[0009] According to still further aspects corresponding methods, a computer
program comprising program means for causing a computer to carry out the steps of the
methods disclosed herein, when said computer program is carried out on a computer, as
well as a non-transitory computer-readable recording medium that stores therein a comput
er program product, which, when executed by a processor, causes the methods disclosed
herein to be performed are provided.
[0010] Example embodiments are defined in the dependent claims. It shall be
understood that the disclosed methods, the disclosed computer program and the disclosed
computer-readable recording medium have similar and/or identical example embodiments
as the claimed transmitter and receiver, respectively, and as defined in the dependent
claims.
[0011] One of the aspects of the disclosure is to use channel bundling based on
multiple RF channels, in particular with SNR averaging across different RF channels. The
present disclosure uses spreading of the output data from encoding across the available RF
channels. The spreading may take place in different stages of the transmitter and receiver.
Two example embodiments refer to spreading on OFDM symbol level and the spreading
based on PLP level.
(0012] The foregoing paragraphs have been provided by way of general intro
duction, and are not intended to limit the scope of the following claims. The described
embodiments, together with further advantages, will be best understood by reference to the
following detailed description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] A more complete appreciation of the disclosure and many of the at
tendant advantages thereof will be readily obtained as the same becomes better understood
by reference to the following detailed description when considered in connection with the
accompanying drawings, wherein:
Fig. 1 shows a schematic diagram of a current proposal of a channel bundling
architecture,
Fig. 2 shows a diagram of SNR variations of different terrestrial RF channels,
Fig. 3 shows a schematic diagram of channel bundling in DVB-C2,
Fig. 4 shows a schematic diagram of channel bundling in DVB-S2x,
Fig. 5 shows a schematic diagram of a multi tuner channel bundling receiver
architecture,
Fig. 6 shows a schematic diagram of a single tuner channel bundling receiver
architecture,
Fig. 7 shows a schematic diagram of a Tx side processing for channel bundling
on cell level with an OFDM symbol,
Fig. 8 shows a schematic diagram of the proposed hybrid dual tuner architec
ture (spreading on OFDM symbol level),
Fig. 9 shows a schematic diagram of the Tx side processing for channel
bundling on complete OFDM symbol level,
Fig. 10 shows a schematic diagram of the Tx side processing for channel bun¬
dling on PLP level,
Fig. 11 shows a schematic diagram of the proposed hybrid dual tuner architec¬
ture (spreading on PLP level),
Fig. 12 shows a schematic diagram of the stream partitioner with input and
output interfaces,
Fig. 13 shows a schematic diagram of the stream combiner for m = 2 with input
and output interfaces,
Fig. 14 shows a schematic diagram of the Selector/combiner stage for two RF
channels,
Fig. 15 shows a schematic diagram of an example for exchanging cells of an
OFDM symbol in a selector/combiner stage with two RF channels and
identical Cdata,
Fig. 16 shows a schematic diagram of an example for exchanging cells of an
OFDM symbol between a selector/combiner stage with 3 RF channels
and identical Cdata,
Fig. 17 shows a schematic diagram of two different approaches to interconnect
modulators,
Fig. 18 shows a schematic diagram of channel bundling with single BICM stage,
Fig. 1 shows a schematic diagram of a receiver for channel bundling with
single BICM stage,
Fig. 20 shows a schematic diagram of an architecture for channel bundling with
multiple PLPs,
Fig. 2 1 shows a schematic diagram of an architecture for channel bundling with
multiple PLPs using one broadband frequency interleaver,
Fig. 22 shows a schematic diagram of the basic TFS mechanism in terrestrial
broadcast systems,
Fig. 23 shows a schematic diagram of a Tx architecture for TFS,
Fig. 24 shows a schematic diagram of a common transmitter and receiver
architecture for use in different modes,
Fig. 25 shows a schematic diagram of the common transmitter and receiver
architecture in MIMO mode,
Fig. 26 shows a schematic diagram of the common transmitter and receiver
architecture in channel bonding mode, and
Fig. 27 shows a schematic diagram of the common transmitter and receiver
architecture in MRC mode.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0014] This disclosure describes an apparatus, method and system for transmit
ting and receiving data. In some embodiments the disclosure relates to broadcast transmis
sion and reception of data. In some embodiments the data may be audio/video data. Some
embodiments describe channel bundling based on multiple RF channels, in particular with
SNR averaging across different RF channels.
[0015] First, the background and existing architectures will be described.
[0016] A current proposal for the upcoming ATSC3.0 standard foresees channel
bundling of multiple, separate RF channels to enable total service data rates that exceed the
net capacity of a single RF channel. Channel bundling is applied above the physical layer
in this proposal, i.e. upper layer solutions take care to split the overall data stream on
transmitter side into portions that fit to the capacity of the different single RF channels.
Upper layer signaling is provided that allows the data recombination of the different RF
channels in a sorted and stream type consistent way. Channel bundling is processed in a
transparent way for all involved RF channels, i.e. the output stream on receiver side is
equal to the corresponding input stream on transmitter side. RF channels can be located at
any channel frequencies, not necessarily adjacent to each other.
[0017] Each RF channel is handled as a standalone ATSC 3.0 signal. There are
no special measures required on the physical layer for bundled channels such as additional
guard bands, additional pilots, synchronization etc. Especially the concept of RF channel
bundling allows reusing multiple existing LDPC encoder and decoder as well as standard
RF tuners, which helps to reduce the overall complexity and simplifies the introduction of
high data rate services beyond the capacity of a single RF channel.
[0018] In all proposed approaches stream partitioning on transmitter (Tx) side as
well as stream recombination (or also denoted as joint BB (baseband packet) de-framing in
some figures) on receiver (Rx) side is performed outside the physical layer.
[0019] In general the different approaches are explained in the following for two
RF channels. Of course it is straight forward to extend the principles to more than two
bundled RF channels.
[0020] Fig. 1 shows the principle of the currently proposed channel bundling
mechanism as described in a call for technologies response. PCT patent application
PCT/EP20 14/06 1467 and the priority applications on which it is based are hereby incorpo
rated by reference in their entirety.
[0021] On the transmitter (Tx) side a stream partitioner 10 partitions the input
stream into m TS/IP input streams, which are then separately modulated by m separate
modulators 11, 12 into m RF streams for transmission over the terrestrial channel. On the
receiver (Rx) side the received RF streams are separately demodulated by m demodulators
13, 14 into m demodulated streams, which are then re-combined by a stream re-combiner
15 into the output stream.
[0022] Although the above mentioned solution of the known proposal realizes
the simplest solution for channel bundling, it has a significant drawback. As the different
channels are completely decoupled, the overall performance of the large input stream
suffers from different channel conditions on different RF channels. The main reason is that
the transmitter as well as the receiver for every allocated RF channel deploys an own,
independent FEC (Forward Error Correction) encoder and decoder. If one or several
channels suffer from insufficient SNR or other channel impairments for correct data
decoding, the overall recombined stream would still result in a corrupted data stream with
errors.
[0023] As an example, the plots shown in Fig. 2 illustrate measured SNR varia¬
tions on different terrestrial RF channels from a Swedish operator (Teracom).
[0024] Next, existing channel bundling architectures without SNR averaging are
described. In particular, existing non terrestrial broadcast systems with channel bundling
will be described.
[0025] It should be noted first that the channel bundling concept has already
been introduced in other broadcasting systems, such as DVB-C2 and DVB-S2x. However
in cable and satellite channel no big amplitude changes across the involved RF channels or
Data Slices are expected. Therefore an exchange of data cells between the different Tx
signal streams for SNR averaging is not required. Nevertheless the principle of the C2 and
S2x channel bundling is briefly explained here.
[0026] A DVB-C2 system allows spreading data of a single PLP (Physical Layer
Pipe) connection over different data slices. This operation mode is intended for advanced
services that require throughput rates above the capacity of a single data slice.
[0027] All data packets of a bundled PLP connection pass the same input pro¬
cessing block. Inserting the ISSY timestamp in the mode adaptation block allows the
reordering of the packets from different data slices on receiver side. At the output of the
input processing block the BBFrames of the bundled PLP are spread over the different data
slices. Fig. 3 illustrates a schematic diagram of a system using channel bundling in DVBC2.
[0028] In DVB-S2x a similar approach (illustrated in Fig. 4) is followed as in
DVB-C2: A single input stream is carried in parallel over max 3 transponders. As in DVBC2
the data of a big input PLP passes the same input processing block 40, in 'High effi¬
ciency mode (HEM)' every BBFrame gets its own ISSY timestamp that allows reordering
on Rx side. Splitting is performed in splitter 4 1 after the BBFrame creation. Fig. 4 illus¬
trates channel bundling in DVB-S2x. Every RF channel can use its own PHY parameters,
such as symbol rate, modulation and coding settings.
[0029] Next, current proposals for terrestrial channel bundling mechanisms as
disclosed herein will be described. First, existing channel bundling approaches for terres¬
trial systems are described.
[0030] The transmitter processing is done as described above with respect to ex¬
isting architectures. For two separate RF channels the related dual tuner receiver architec¬
ture is shown in Fig. 5, which illustrates a multi tuner channel bundling receiver architec
ture 50.
[0031] It should be noted that decoding of every RF channel is performed inde
pendently by separate RF frontends 51, 52 and separate demodulators 53, 53 before joint
stream recombination in stream combiner 55 or baseband (BB) de-framing by de-framing
unit 56 at the very end of the processing chain. Accordingly a SNR averaging across the
two RF channels does not happen.
[0032] Some example advantages and disadvantages are stated below. The ad¬
vantages are:
Simple and scalable implementation
Complete reuse of separate decoder (tuner + demodulator)
• Supports bundling of distant and neighbored channels
Additional statistical multiplex gain across the overall bandwidth
The disadvantages are:
• No additional frequency diversity or SNR averaging
• No guard band removal possible for neighboring bundled channels (see
also below)
[0033] For completeness it shall be mentioned that channel bundling can be also
realized by an overall bigger, single RF channel. On Tx side the stream is processed by a
higher bandwidth input processing, BICM and time interleaver stages.
[0034] On Rx side a single broadband tuner can be used, as shown in Fig. 6 i l
lustrating a single tuner channel bundling receiver architecture 60 including an RF frontend
6 1 and a demodulator 62 (including a combined unit 63 for FFT, FDI (frequency domain
interleaving), deframing and TDI (time domain interleaving), a QAM-demapper 64, an
LDPC-decoder 65 and a BB-deframing unit 66).
[0035] Example advantages and disadvantages of this approach are listed below.
The advantages are:
• Additional frequency diversity
• TFS-like (time frequency slicing) SNR averaging
• Additional statistical multiplex gain across the overall bandwidth
Guard band between neighboring bundled channels can be removed
The disadvantages are:
• Complex implementation
No bundling of distant channels possible
[0036] Next, the proposed channel bundling with SNR averaging will be d e
scribed. A technology is proposed allowing for SNR averaging across all involved RF
channels. Most important element is the spreading of the output data from every FEC
encoder (LDPC encoder) across the available RF channels. The spreading may take place
in different stages of the TX and RX chain. Two options, namely the spreading on OFDM
symbol level and the spreading based on PLP level are described in the following.
[0037] First, spreading based on OFDM symbol level will be described. Fig. 7
shows an example embodiment 70 of the principle on Tx side for single PLP with channel
bundling on two RF channels on cell level within an OFDM symbol. In case of PLP
bundling the large input stream is, after input processing in the input processing unit 71,
divided in the stream partitioner 72 into different partial streams, each of them allocated to
a PLP. These PLPs are then fed into the different modulators 73, 74 and can have the same
or different PLP IDs. At least a single partial stream allocated to a single PLP # 1 is provid
ed to each modulator. It should be noted in this context that the number of PLPs per RF
channel does not necessarily have to be the same. For instance, the first RF channel RF1
might carry n PLPs, while the second RF channel RF2 might carry p PLPs with n p.
However, in case of a single PLP, the dashed boxes shown in Fig. 7 are in fact inactive.
[0038] In typical architectures such as DVB-T2, DVB-NGH and most likely
ATSC3.0, different PLPs are passing different input processing BICM stages as well as
individual time interleaver. The BICM (Bit interleaved coded modulation) stage 731, 741
consists of FEC encoder (BCH and LDPC), bit interleaver and QAM mapper. After time
interleaving by time interleaver 732, 742 the time interleaved QAM cells of every PLP are
then scheduled by scheduler 733, 743 onto different OFDM symbols within a frame.
[0039] In a regular case, the output of the scheduler 733, 743 is fed directly to
the frequency interleaver and OFDM modulator of the related RF channel. In contrast to
current solutions it is proposed to exchange (e.g. equally) the scheduled cells of one
OFDM symbol across selected or all involved RF channels. This is performed by selectors
734, 735 and combiner 736 in the modulator 73 and the selectors 744, 745 and the combin¬
er 746 in the modulator 74. Subsequently, frequency interleaving by frequency interleavers
737, 747 and OFDM modulation by OFDM modulators 738, 748 is performed to obtain the
RF output streams.
[0040] It should be noted that instead of the shown cell exchange stage and fol
lowing RF channel frequency interleaver a single frequency interleaver that spans across
the overall sum of OFDM subcarriers or resulting bandwidth of all RF channels (example:
single 12 MHz frequency interleaver instead of cell exchange and two separate 6MHz
frequency interleavers, see e.g. Fig. 21).
[0041] Generally, the proposed transmitter comprises the following elements:
i) a data stream partitioner (in the embodiment 70 realized by the stream partitioner
71) configured to partition a data stream of data to be communicated into two or more
stream partitions;
ii) two or more modulators (in the embodiment 70 realized by the modulators 73, 74)
configured to each receive a stream partition and to generate modulated data from the
received stream partition; and
iii) an interleaver (in the embodiment 70 realized by the selectors 734, 735, 744, 745,
the combiners 736, 746 and the frequency interleavers 737, 747; in other embodiments
realized by cell exchange circuitry, i.e. the exchange of cells may also be understood as
one embodiment of interleaving in the context of the present disclosure) configured to
assign the modulated data generated by a modulator from a received stream partition to
different RF channels for transmission.
[0042] On Rx side, the carrier exchange from Tx side obviously needs to be re¬
versed before the decoding. Fig. 8 shows an example embodiment 80 of the receiver
architecture for two RF channels, in particular a proposed hybrid dual tuner architecture
(spreading on OFDM symbol level). The disclosure is not limited to two RF channels. The
receiver 80 comprises two frontends 81, 82, two demodulators 83, 84, a stream combiner
85 and a de-framing unit 86. Each of said demodulators 83, 84 comprises an FFT and FDI
unit 831, 841, a deframing and TDI unit 832, 842, a QAM-demapper 833, 843 and an
LDPC-decoder 834, 844. The receiver typically only decodes a single PLP. This is at least
the case if one PLP represents one service (e.g. a video stream). In the case that a PLP
carries only a service component (e.g. only video or only audio), all PLPs comprising the
service need to be decoded.
[0043] Generally, the proposed receiver comprises the following elements:
i) a deinterleaver (in the embodiment 80 realized by the FFT and FDI units 8 11, 821
and the deframing and TDI units 8 12, 822; in other embodiments realized by cell reexchange
circuitry, i.e. the re-exchange of cells may also be understood as one embodi¬
ment of deinterleaving in the context of the present disclosure) configured to receive data
of a received data stream via at least two separate RF channels, wherein the data of stream
partitions of the data stream are transmitted via the at least two RF channels, and to assign
the data belonging to the same stream partition transmitted via different RF channels to
different demodulators,
ii) two or more demodulators (in the embodiment 80 realized by the QAM-demappers
8 13, 823 and the LDPC-decoders 8 14, 824) configured to each receive data of a stream
partition and to generate demodulated data from the received data of the stream partition,
and
iii) a data stream combiner (in the embodiment 80 realized by the stream combiner 82)
configured to combine the demodulated data of the two or more demodulators into the data
stream.
[0044] It is mentioned that the data exchange between the different RF changes
can also take place on complete OFDM symbols rather than the above mechanism of cell
exchange within an OFDM symbol. Effectively this means that single OFDM symbols out
of the L OFDM symbols of a frame (typically data symbols only, excluding preamble and
signalling symbols) are exchanged between the different modulators. The related block
diagram of such an embodiment 90 of the transmitter is shown in Fig. 9 , showing Tx side
processing for channel bundling on complete OFDM symbol level. It should be noted that
the so far cell specific selectors (within an OFDM symbol) 734', 735', 744', 745' are now
working on OFDM symbols within a frame, i.e. the granularity of the selectors 734', 735' ,
744' , 745 ' is different compared to the selectors 734, 735, 744, 745 of the embodiment
shown in Fig. 7 , which is denoted by the index in the selectors (Lf instead of Cdata)-
[0045] Of course exchange of any form of multiple OFDM symbols is also pos
sible, but comes with less diversity. The exchange of OFDM symbols is seen as important
scenario as it allows for a simple combined architecture of channel bundling with TFS with
two tuners. It should be noted that the exchange of OFDM symbols may similarly take
place after the frequency interleaver.
[0046] Next, spreading based on PLP level will be described.
[0047] So far it has been assumed that the spreading takes place on OFDM sym
bol level. This allows for a simple TX and RX implementation but has some disad
vantages. The exchanged data rate of the spread OFDM symbols is quite high, since the
whole OFDM symbols need to be exchanged, even though the PLP of interest is only
transmitted in a subset of the cells of the OFDM symbols. This disadvantage can be
overcome by spreading the cells on PLP level, as depicted in Fig. 10, showing an embodi¬
ment 100 of the Tx side processing for channel bundling on PLP level.
[0048] The selection of data cells in the different selector blocks 1021, 1022,
1031, 1032 is for example defined by the partitioning rate in the stream partitioner 101, i.e.
the relation of the BB Frames for this PLP that are fed into the different modulator chains
102, 103. In this embodiment the schedulers 1024, 1034 are provided after the combiners
1023, 1033.
[0049] In this embodiment it is also shown that separate input streams can be
handled by separate input processing units and separate stream partitioners. Alternatively,
separate input streams may be handled by a common input processing unit 7 1 and a
common stream partitioner 101. The proposed idea can thus be applied to handling sep a
rate input streams in parallel as well.
[0050] The respective receiver architecture 110 is shown in Fig. 11 showing the
proposed hybrid dual tuner architecture (spreading on PLP level) comprising two demodulators
113, 114. The demodulators 113, 14 only exchange the LLR values of the QAM
demappers 833, 843, resulting in a smaller data rate compared to the exchange of OFDM
symbols as provided in the receiver architecture 80 shown in Fig. 8. Note that different
possibilities exist for the exchange of data cells on reception side: On top to the illustrated
exchange of LLR values after the QAM demappers 833, 843 per bit, it is also possible to
exchange I and Q values as well as the channel state information (CSI) by the common
units 1131, 1141 for FFT, FDI, demapping and TDI before the QAM demappers 833, 843.
[0051] Another advantage of exchanging the data on PLP level is the increased
flexibility in case of channel bundling with different RF bandwidths, which leads to
different OFDM symbol durations. While there are difficulties exchanging OFDM sym¬
bols, due to the different OFDM symbol timing, this causes no problems in case of ex
changing cells on PLP level. It should however be ensured that the number of exchanged
cells between the different RF channels is adapted according to the capacity of the different
channels.
[0052] Next, a comparison of channel bundling with SNR averaging with state
of the art channel bundling approaches will be made. Example advantages are:
• Relatively simple and scalable implementation
• Reuse of existing tuners and almost completely existing demodulators
• Supports bundling of distant and neighbored channels
• Additional frequency diversity
TFS-like (time frequency slicing) SNR averaging
Works for single PLP as well as for multiple PLPs across multiple RF chan
nels
Example disadvantages are:
• Requires high data rate interface between demodulator chips (received
QAM cells + channel state information or LLR values after QAM demapping for
PLP(s) of interest)
No guard band removal possible for neighboring bundled channels
[0053] The skilled person will appreciate that in some systems received signals
from different reception antennas and tuners are combined into a single decoder chip.
[0054] Next, a detailed description of example embodiments of the stream partitioner,
the stream combiner and the selector will be provided.
[0055] The input streams of the stream partitioner 120, as depicted in Fig. 12
showing an embodiment of a stream partitioner 120 with input and output interfaces,
consist of baseband frames (BB-Frames) of the n different PLPs. Each PLP may have a
different input stream format, such as TS, IP or GSE. The corresponding input stream
packets are packetized to BB-Frames with a suitable timestamp such as an ISSY timestamp
in the input processing blocks 121, 122 before the stream partitioner 120. The task of the
stream partitioner 120 is to distribute the BB-Frames of the n PLPs to m streams in such a
way, that the output data rate of the streams designated for the m modulators matches the
available capacity of the corresponding RF channel. In the simplest case with m = 2
modulators with the same capacity, the stream partitioner equally partitions the input
streams to both modulators. In case of different transmission parameters or RF channel
bandwidths of the m RF channels, the capacity of the m RF channels may however be
different, requiring an uneven output stream capacity distribution at the stream partitioner
output.
[0056] The task of the stream combiner 30 in the receiver, depicted in Fig. 3
showing an embodiment of a stream combiner 130 for m = 2 with input and output inter¬
faces, is to revert the process of the stream partitioner. For a given PLP that is being
decoded the m streams of the m demodulators 131, 132 are joined according to the ISSY
timestamps available in the BB-Frames. The stream combiner 130 comprises a buffer to
store the BB-Frames from the different streams, whose size depends on the maximum
difference decoding delay of the m demodulators. In case of identical decoding delay a
buffer size of some BB-Frames is sufficient. The processing of the partitioner and combin¬
er is transparent, i.e. the stream of BB-Frames at the output of the stream combiner 130 is
identical to the input of the stream partitioner. After the stream combining the initial
TS/IP/GSE stream is restored by the BB deframer 133.
[0057] The task of the selector and combiner stage 140, depicted in Fig. 14
showing an embodiment of a selector/combiner stage 140 for two RF channels, is to
equally distribute the modulated symbols (so called cells in DVB) at the output of the m
schedulers 141, 142 across all m RF channels. This way the frequency diversity is in
creased from the bandwidth of a single channel by a factor of m to the overall bandwidth
of all bundled channels. In particular in case of different SNR levels of the RF channels, an
SNR averaging takes place across all RF channels. It should be noted that selector(s) 143,
144, 145, 146 provided in each modulator may be implemented as separate selector blocks
as e.g. shown in Fig. 9, i.e. one selector block per modulator so that for m modulators each
modulator comprises m selector blocks. In another embodiment each modulator comprises
a single selector unit performing the functions of the selector blocks. The data received
from the selectors 143, 144, 145, 146 are combined by combiners 147, 148.
[0058] The simplest way of applying such a distribution is the exchange of each
m-th cell (of all Cdata cells) of each OFDM symbol between all involved RF channels. For
the simplest case of m = 2 with the same RF bandwidth (i.e. Cdata identical for all RF
channels), all cells of the OFDM symbols with even index (index 2:2: C ata according to
MATLAB syntax) remain in the current RF channel, while all cells of the OFDM symbols
with odd index (index 1:2: C data according to MATLAB syntax) are exchanged between
both RF channels. The block diagram of such a selector/combiner stage 140 is shown in
Fig. 14. The impact to an OFDM symbol is depicted in Fig. 15. Fig. 15 shows an example
for exchanging cells of an OFDM symbol in a selector/combiner stage with two RF
channels and identical Cdata- A similar example with three RF channels is shown in Fig. 16
showing an example for exchanging cells of an OFDM symbol between a selec
tor/combiner stage with 3 RF channels and identical Cdata[
0059] In the more general case of m RF channels with different bandwidths and
hence different OFDM symbol durations and number of cells C ata the amount of ex¬
changed cells is not equal and must be calculated according to the ratio of Cdata of the
different RF channels as well as the different OFDM symbol durations. Further, the order
of the combining operation of the cells from the different RF channels must be defined.
Both numbers have to be defined in a deterministic way using rounding operations to avoid
unambiguities between the modulator and demodulator implementation. To ensure a
random distribution of the cells per RF channel after the combining stage, a frequency
interleaver is applied individually for each RF channel.
[0060] Next, the number of required communication links between modula
tors/demodulators will be discussed.
[0061] In case of m = 2, four unidirectional communication links, or two bidi¬
rectional communication links are necessary to exchange the data between the m selec
tor/combiner stages. With increasing number of m, the number of required communication
links grows quite fast. This holds for both the transmitter (comprising m modulators) and
receiver (comprising m demodulators). To avoid a large number of dedicated transmission
links or better logical representation, a communication bus between the m demos may be
used. The two approaches of using dedicated links or a communication bus are exemplarily
shown in Fig. 17. Fig. 17 shows two different approaches to interconnect several modula
tors 171, 172, 173, 174 (Fig. 17(a) shows dedicated links, Fig. 17(b) shows a communica¬
tion bus). The BB-Frame input and output streams of the selector/combiner stages are
omitted for simplicity.
[0062] Next, channel bundling with single BICM stage will be described.
[0063] It will be described briefly how channel bundling is realized with a single
BICM encoding and decoding stage (i.e. FEC encoding (BCH/LDPC), bit interleaving and
QAM mapping). In contrast to the previous solutions that focus on reusing existing functional
blocks or even existing whole demodulator architectures, this option requires that the
BICM stages can handle data rates beyond the capacity of a single RF channel, however
the architecture for the transmitter and receiver gets more simple.
[0064] An embodiment of the transmitter side architecture 180 with single
BICM stage and multiple bundled RF channels is shown in Fig. 18 for an example configu
ration of two RF channels. An embodiment of the related receiver block diagram 1 0 is
shown in Fig. 19 for channel bundling with single BICM stage.
[0065] The transmitter 180 comprises two modulators 181, 182, wherein the
modulator 181 comprises a splitter 183 rather than selectors and a combiner as the provid¬
ed in the embodiment of the transmitter 100 shown in Fig. 10. Thus, rather than using the
same complete BICM chain another option is provided: If the splitter is located after the
same FEC (LDPC) encoder, every partial bitstream into the different modulator chains can
be modulated by separate QAM modulators and allow therefore for different robustness
levels on the different RF channels. On receiver side the combination then takes place after
passing separate QAM demappers. For this purpose the receiver 190 comprises separate
frontends 81, 82, separate units 191, 192 for FFT, FDI and deframing and a single combin¬
er 193, a single time deinterleaver 194, a single QAM demapper 195, a single LDPC
decoder 196 and a single deframing unit 86.
[0066] Next, the generic architecture for multiple PLP and the relation to time
frequency slicing will be described.
[0067] A proposed enhancement focuses on channel bundling for very high data
rate single PLPs. However, in general the exchange of the subcamers from different
encoding chains is also applicable to a multiple PLP scenario. Of course mixed scenario
with a high data rate PLP allocating almost the overall capacity and other PLPs to fill the
remaining capacity are possible. The Tx structure for M-PLP with n PLPs and m RF
channels is shown in Fig. 20 depicting a transmitter architecture 200 for channel bundling
with multiple (i.e. n) PLPs. Compared to the transmitter architecture 70 shown in Fig. 7 n
input processing units 71a, 7 1n are provided for separate input processing of the n
PLPs. Further, each of the m modulators 73a, 73m comprises n BICM units 731a,
73 In and 741a, 74 In, n time interleavers 732a, 732n and 742a, 742n, a sched
uler 733, 743, selectors 734, 735, 744, 745, a combiner 736, 746, a frequency interleaver
737, 747 and an OFDM modulator 738, 748.
[0068] Instead of the cell exchange stage and following RF channel frequency
interleaver, a single frequency interleaver spanning across the resulting bandwidth of all
RF channels can be used, obviously still requiring an interface between the m modulators.
This is shown in Fig. 2 1 depicting a transmitter architecture 210 for channel bundling with
multiple PLPs using one broadband frequency interleaver 212 for all modulators 2 11a, . . .,
2 1In and separate input processing units 213a, 213n, 214a, 214n for each PLP in
said modulators 2 11a, . .., 211n.
[0069] One drawback of the proposed channel bundling approach is the manda
tory usage of several tuners. It should be mentioned that there is another proposal in DVB
and ATSC3.0 that allows for a single tuner reception of several RF channels, the so called
"Time Frequency Slicing (TFS)". TFS also spreads data from different PLPs to different
RF channels (up to 6 frequencies) to make a single 'virtual' channel to allow efficient
statistical multiplexing. PLPs are scheduled that they appear only at one RF channel at one
point of time. Some guard band between different PLP portions on different RF channels is
provided to enable channel change. Fig. 22 shows the basic TFS mechanism in terrestrial
broadcast systems (DVB, ATSC3.0).
[0070] However, there are also drawbacks and constraints in using TFS, such as
the mandatory usage of a sufficient number of PLPs to allow for enough time for RF
channel hopping. Moreover it is not possible that a PLP allocates the majority of the
available capacity as this would not allow to have this PLP scheduled to a single RF
channel at all possible times. This results in constraints regarding the maximum capacity of
one PLP, which is significantly below the capacity of a single RF channel. Fig. 23 shows a
Tx architecture 230 for TFS which may be compared to the Tx architecture 180 for chan¬
nel bundling shown in Fig. 18. This transmitter 230 comprises n processing chains for
processing the n PLPs, each processing chain comprises an input processing unit 231a, . ..,
2 In, a BICM 232a, 232n and a time interleaver 233a, 233n. Further, a common
scheduler 234 is provided. The output of the scheduler 234 is provided to m separate
OFDM units 235a, 235m, each including a frequency interleaver and an OFDM
modulator.
[0071] Generally speaking TFS cannot transmit at data rates above the capacity
of a single channel. This is extended by channel bundling, using for example the methods
and apparatus described.
[0072] In other embodiments of the present disclosure, the proposed transmitter
and receiver architecture is used and may be embodied as a unified architecture, in other
scenarios in which two tuners are used in the receiver architecture. Such other scenarios
include - in addition to the above explained scenario using channel bundling (also called
channel bonding) - MIMO architectures and MRC (Maximum Ratio Combining) architec¬
tures used in diversity receivers. This does not preclude use adaptation for other scenarios.
In some embodiments, standard blocks from a standard SISO receiver, including BICM
stages, shall be reused. The proposed architectures use a joint processing / cell exchange
stage across two (or more) transmitter modules and across two (or more) receiver modules,
respectively. The proposed architectures provide the advantages of a lower implementation
and development effort, lower costs because of reused blocks and therefore higher success
chances in the market.
[0073] It should be noted that LDPC decoders as most complex elements of the
receiver are implemented in parallel structures: Logically two separate LDPC decoders
with processing speed x could be also handled by a single LDPC decoder operated at
processing speed 2x. In other words: Implementing with two standard speed LDPC decod¬
ers or double speed single decoder is functionally equivalent.
[0074] A common architecture of a transmitter 300 and of a receiver 400 is
shown in Fig. 24. Elements that are already explained above with reference to other
embodiments will be provided with the same reference numerals as in those other embod¬
iments. In the transmitter 300, a unified precoding and cell exchange unit 301 is provided;
in the receiver 400 a unified decoding and cell re-exchange unit 401 is provided. Further,
in the receiver 400 OFDM demodulators 402, 404 and common units 403, 405 for FDI,
PLP selection and TDI are provided.
[0075] As can be derived from the schematic diagram, the processing will be
made on symbol level (e.g. on the level of QAM symbols), which is common to all appli¬
cations of this common architecture. Further, an interface for requesting and/or obtaining
redundancy data (e.g. redundancy data on demand via a separate channel) may be provided
based on the same processing level.
[0076] Since the transmitter can be operated in different modes (i.e. MRC mode,
MIMO mode and channel bonding mode) a control unit 302 is provided in some embodi¬
ments to control the unified precoding and cell exchange unit 301 accordingly to work in
the desired mode. This control unit 302 may be operated by the operator of the transmitter.
The control unit may select MIMO operation for a certain RF channel if the transmitter is
equipped with several antennas or may operate in channel bonding mode for other two RF
frequencies. The operation may depend on the network design and anticipated receiver
capabilities and are selected by the network operator. Further, some signaling is included
into the transmitted data streams identifying the respective mode in which the transmitter
300 is operated for use by the receiver 400 so that the receiver 400 can operate the unified
decoding and cell re-exchange unit 401 in the same mode. The signaling may be embedded
for example in layer 1 signaling which may be carried in a preamble or signaling symbols
at the beginning of each frame defining the mode of operation and is used by the receiver
to decode the following data part depending of the mode of operation.
[0077] Fig. 25 shows the transmitter 310, corresponding to transmitter 300, and
the receiver 410, corresponding to receiver 400, when operated in the MIMO mode. In this
case the unified precoding and cell exchange unit 301 functions as MIMO encoder 3 11 and
the unified decoding and cell re-exchange unit 401 functions as MIMO decoder 4 11.
[0078] In the MIMO encoder 3 11 linear precoding matrix may be used. Fur¬
ther, a different precoding matrix may be applied per subcarrier k. The precoding may use
eSM (enhanced Spatial Multiplexing) and PH (Phase Hopping) which may have the
following precoding matrix per subcarrier k
0 i simp cos
Additional precoding elements, like power allocation or stream-based phase hopping may
be used additionally. Precoding at the transmitter increases diversity and improves the
overall system performance. In another embodiment plain spatial multiplexing may be
applied with
V( ) = [1
0
In this case, no precoding is applied and the precoder can be considered to be transparent.
[0079] The R channels RFl and RF2 are defined in the spatial domain, and the
two tuners are connected to two antennas For performing MIMO transmission at least two
transmit antennas and at least two receive antennas are provided, i.e. a first transmit
antenna transmits data on RFl and a second transmit antenna transmits data on RF2. There
may be interference between the transmit antennas and the receive antennas. The channel
matrix may be represented as
[0080] In the receiver 410 ZF (Zero Forcing) or MMSE (Minimum Mean Square
Error) detection may be used for decoupling the two received data streams. Alternatively, a
ML (Maximum Likelihood) demapper may be used, for example a joint MIMO decoder
and QAM demapper 412.
[0081] Fig. 26 shows the transmitter 320, corresponding to transmitter 300, and
the receiver 420, corresponding to receiver 400, when operated in the channel bonding
mode. In this case the unified precoding and cell exchange unit 301 functions as cell
exchange unit 321, representing another embodiment of the disclosed interleaver, and the
unified decoding and cell re-exchange unit 401 functions as cell re-exchange unit 421,
representing another embodiment of the disclosed deinterleaver,. This case may also be
seen functionally as a subset of the MIMO case.
[0082] In the cell exchange unit 321 SNR averaging may be described in matrix
notation to highlight the analogy to the MIMO description
1 r 1 1 V( n) = and V{ dd =
.0 1 - .1 ft '
Hereby, even and odd refer to OFDM carrier numbers, but could also map to other granu¬
larities (OFDM symbols, ...). In another embodiment any precoding (similar to MIMO)
may be applied providing increased diversity. However, unitary precoding, similar to the
MIMO precoding described above, is preferred, but not essential to the disclosure. Com¬
pared to the simple cell exchange described by the matrices above, precoding further
improves the performance. If the precoding block is already available for the MIMO
operation mode, the precoding block may be used for the channel bonding mode without
additional complexity. The improved performance by applying precoding may be ex
plained as follows: precoding overlaps the two symbols generated by the two BICM
chains, i.e. a superposition of both symbols is transmitted in each RF channel. If the two
RF channels experience very different fading or attenuation, the information of the two
symbols may be recovered more reliably at the receiver (in an extreme scenario, the
information of both symbols may be recovered from only RF channel; if no precoding is
applied, the second symbol may be lost if one the two RF channels is attenuated very
strongly).
[0083] The RF channels RF1 and RF2 are described in the frequency domain.
There is no co-channel interference. The channel matrix may be represented as
\h
H =
0
0 hwhere
h i 1 and h22 correspond to the fading coefficients of the RF channels RF1 and RF2,
respectively. This description is intended to highlight the analogy to the MIMO mode
above.
[0084] In the receiver 420 cell re-exchange is performed, e.g. by use of reorder¬
ing of SNR averaging or inverse precoding.
[0085] Fig. 27 shows the transmitter 330, corresponding to transmitter 300, and
the receiver 430, corresponding to receiver 400, when operated in the MRC combining
mode providing a diversity receiver. In this case the transmitter 330 uses only a single path
(modulator), i.e. there is only a single data stream processed. The unified precoding and
cell exchange unit 301 is disabled. In the receiver the unified decoding and cell reexchange
unit 401 functions as cell re-exchange unit 431 (representing still another
embodiment of the disclosed deinterleaver), but issues a single data stream as well so that
only one path after the cell re-exchange unit 431 is activated. This case may also be seen as
a subset of the MIMO case.
[0086] The RF channel between the transmission path and each receiving path
may be represented as
[0087] In the receiver 430 maximum ratio combining may be performed, e.g. by
use of coherent addition of the two received signals following the algorithm of maximum
ratio combining (MRC). More advanced combing algorithms may be used as well, e.g.
optimum combining.
[0088] In summary, in the combined transmitter and receiver architecture ex
plained above with reference to Figs. 24 to 27 the transmitter and the receiver, respective
ly, may generally be defined as follows:
[0089] A transmitter for communicating data using at least two separate RF
channels, the transmitter comprising:
a data stream partitioner configured to partition a data stream of data to be commu¬
nicated into two or more stream partitions,
two or more modulators configured to each receive a stream partition and to
generate modulated data from the received stream partition,
a unified precoding and cell exchange unit configured to operate in different modes,
and
an optional controller configured to control the unified precoding and cell exchange
unit to operate in a desired mode.
Said modes may include i) a MIMO mode in which it operates to separately encode the
two or more stream partitions, ii) a channel bonding mode in which it operates to assign
the modulated data generated by a modulator from a received stream partition to different
RF channels for transmission, and iii) an MRC mode in which the data stream partitioner
and the unified precoding and cell exchange unit are disabled and in which only one
modulator operates.
[0090] A receiver for receiving data of a data stream via at least two separate RF
channels (which may be separate in frequency (channel bonding) or achieved by spatial or
polarization diversity), the receiver comprising:
means for deriving a mode information from the received data,
a unified decoding and cell re-exchange unit configured to operate in one of
different modes according to the derived mode information,
two or more demodulators configured to each receive data of a stream partition and
to generate demodulated data from the received data of the stream partition, and
a data stream combiner configured to combine the demodulated data of the two or
more demodulators into the data stream.
Said modes may include i) a MIMO mode in which it operates to separately decode data of
two or more stream partitions received via at least two separate antennas, ii) a channel
bonding mode in which it operates to receive data of a data stream via at least two separate
RF channels, wherein the data of stream partitions of the data stream are transmitted via
the at least two RF channels, and to assign the data belonging to the same stream partition
transmitted via different RF channels to different demodulators, and iii) an MRC mode in
which only one demodulator is activated to demodulate the received data.
[0091] Thus, the foregoing discussion discloses and describes merely exemplary
embodiments of the present disclosure. As will be understood by those skilled in the art,
the present disclosure may be embodied in other specific forms without departing from the
spirit or essential characteristics thereof. Accordingly, the disclosure of the present disclo¬
sure is intended to be illustrative, but not limiting of the scope of the disclosure, as well as
other claims. The disclosure, including any readily discernible variants of the teachings
herein, defines, in part, the scope of the foregoing claim terminology such that no inventive
subject matter is dedicated to the public.
[0092] In the claims, the word "comprising" does not exclude other elements or
steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or
other unit may fulfill the functions of several items recited in the claims. The mere fact that
certain measures are recited in mutually different dependent claims does not indicate that a
combination of these measures cannot be used to advantage.
[0093] In so far as embodiments of the disclosure have been described as being
implemented, at least in part, by software-controlled data processing apparatus, it will be
appreciated that a non-transitory machine-readable medium carrying such software, such
as an optical disk, a magnetic disk, semiconductor memory or the like, is also considered to
represent an embodiment of the present disclosure. Further, such a software may also be
distributed in other forms, such as via the Internet or other wired or wireless telecommuni¬
cation systems.
[0094] The elements of the disclosed devices, apparatus and systems may be
implemented by corresponding hardware and/or software elements, for instance appropri¬
ated circuits. A circuit is a structural assemblage of electronic components including
conventional circuit elements, integrated circuits including application specific integrated
circuits, standard integrated circuits, application specific standard products, and field
programmable gate arrays. Further a circuit includes central processing units, graphics
processing units, and microprocessors which are programmed or configured according to
software code. A circuit does not include pure software, although a circuit includes the
above-described hardware executing software.
[0095] It follows a list of further embodiments of the disclosed subject matter:
1. A transmitter for communicating data using at least two separate RF channels, the
transmitter comprising:
a data stream partitioner configured to partition a data stream of data to be commu¬
nicated into two or more stream partitions,
two or more modulators configured to each receive a stream partition and to
generate modulated data from the received stream partition, and
an interleaver configured to assign the modulated data generated by a modulator
from a received stream partition to different RF channels for transmission.
2. The transmitter as defined in embodiment 1,
wherein said data stream partitioner is configured to partition the data stream into N stream
partitions and
wherein the transmitter comprises N modulators, each being configured to receive a single
stream partition.
3. The transmitter as defined in embodiment 1 or 2,
wherein said data stream partitioner is configured to receive at least two data streams of
data to be communicated and to partition said data streams into two or more respective
stream partitions and
wherein said two or more modulators are configured to each receive at least one stream
partition from at least two different data streams.
4. The transmitter as defined in embodiment 3,
wherein said two or more modulators are configured to each receive one stream partition
from each data stream.
5. The transmitter as defined in embodiment 3,
wherein said interleaver further comprises a combiner configured to combine modulated
data generated by different modulators from different stream partitions of the same data
stream and assigned for transmission by the same RF channel.
6. The transmitter as defined in any preceding embodiment,
wherein said transmitter is configured to communicate the data on OFDM subcarriers of
OFDM symbols and wherein said interleaver is configured to assign the modulated data to
OFDM subcarriers of OFDM symbols of different RF channels for transmission.
7. The transmitter as defined in any preceding embodiment,
wherein said two or more modulators are configured to each generate OFDM symbols
comprising a plurality of cells from the received stream partition and
wherein said interleaver is configured to assign the OFDM symbols or cells of OFDM
symbols generated by a modulator from a received stream partition to different RF ch an
nels for transmission.
8. The transmitter as defined in any preceding embodiment, wherein said interleaver
comprises
a selector per modulator configured to select and assign modulated data of the
respective modulator to the different RF channels,
a combiner per RF channel configured to combine modulated data assigned to the
respective RF channel, and
a frequency interleaver per RF channel for frequency interleaving of the combined
modulated data of the respective RF channel.
9. The transmitter as defined in any preceding embodiment,
wherein said data stream partitioner is configured to equally partition a data stream of data
to be communicated into two or more stream partitions.
10. The transmitter as defined in any preceding embodiment,
wherein said interleaver is configured to equally assign the modulated data to different RF
channels for transmission.
11. The transmitter as defined in any preceding embodiment,
wherein said interleaver is configured to assign the modulated data to different RF chan
nels for transmission proportional to the bandwidth of the different RF channels.
12. The transmitter as defined in any preceding embodiment,
wherein said interleaver comprises cell exchange circuitry.
13. The transmitter as defined in embodiment 12,
wherein said cell exchange circuitry is configured to operate in different modes.
14. The transmitter as defined in embodiment 1 or 13,
wherein said cell exchange circuitry is configured to operate in a channel bonding mode in
which it operates to assign the modulated data generated by a modulator from a received
stream partition to different RF channels for transmission.
15. The transmitter as defined in embodiment 12, 13 or 14,
wherein said cell exchange circuitry is configured to apply a matrix V(even) for multiplica
tion with an input vector of two OFDM carriers or symbols or cells of even index from two
different stream partitions and a matrix V(odd) for multiplication with an input vector of
two OFDM carriers or symbols or cells of odd index from two different stream partitions,
wherein
Yieven)
16. A transmission method for communicating data using at least two separate RF
channels, the transmission method comprising:
partitioning a data stream of data to be communicated into two or more stream
partitions,
receiving a stream partition by each of two or more modulators,
generating modulated data from the received stream partition, and
assigning the modulated data generated by a modulator from a received stream
partition to different RF channels for transmission
17. A receiver for receiving data of a data stream via at least two separate RF channels,
the receiver comprising:
a deinterleaver configured to receive data of a data stream via at least two separate
RF channels, wherein the data of stream partitions of the data stream are transmitted via
the at least two RF channels, and to assign the data belonging to the same stream partition
transmitted via different RF channels to different demodulators,
two or more demodulators configured to each receive data of a stream partition and
to generate demodulated data from the received data of the stream partition,
a data stream combiner configured to combine the demodulated data of the two or
more demodulators into the data stream.
18. The receiver as defined in embodiment 17,
wherein the receiver comprises N demodulators, each being configured to receive data
from N stream partitions, and
wherein said data stream combiner is configured to combine the demodulated data from
the N demodulators into the data stream.
19. The receiver as defined in embodiment 17 or 18,
wherein said deinterleaver is configured to assign OFDM symbols or OFDM subcarriers of
OFDM symbols belonging to the same stream partition transmitted via different RF
channels to different demodulators.
20. The receiver as defined in any one of embodiments 17 to 19,
further comprising a demapper for demapping of the received data,
wherein said deinterleaver is configured to assign channel state information before dmapping
and/or either LLR values of the demapped data or I and Q values of the data before
demapping belonging to the same stream partition transmitted via different RF channels to
different demodulators.
2 1. The receiver as defined in any one of embodiments 17 to 20,
wherein said receiver is configured to receive the data on OFDM subcarriers of OFDM
symbols and wherein said deinterleaver is configured to assign the received data from
OFDM subcarriers of OFDM symbols or from OFDM symbols transmitted via different
RF channels to different demodulators.
22. The receiver defined in any one of embodiments 17 to 21,
wherein said deinterleaver comprises cell re-exchange circuitry.
23. The receiver as defined in embodiment 22,
wherein said cell re-exchange circuitry is configured to operate in different modes.
24. The receiver as defined in embodiment claim 22 or 23,
wherein said cell re-exchange circuitry is configured to operate in a channel bonding mode
in which it operates to assign the data belonging to the same stream partition transmitted
via different RF channels to different demodulators.
25. A receiving method for receiving data of a data stream via at least two separate RF
channels, the receiving method comprising:
receiving data of a data stream via at least two separate RF channels, wherein the
data of stream partitions of the data stream are transmitted via the at least two RF channels,
assigning the data belonging to the same stream partition transmitted via different
RF channels to different demodulators,
receiving data of a stream partition by each of two or more demodulators
generating demodulated data from the received data of the stream partition, and
combining the demodulated data of the two or more demodulators into the data
stream.
26. A non-transitory computer-readable recording medium that stores therein a computer
program product, which, when executed by a processor, causes the method according to
embodiment 16 or 25 to be performed.
27. A system for communicating data using at least two separate RF channels, said
system comprising:
at least one transmitter as defined in embodiment 1 and
at least one receiver as defined in embodiment 16.
28. A computer program comprising program code means for causing a computer to
perform the steps of said method according to embodiment 16 or 25 when said computer
program is carried out on a computer.

CLAIMS
1. A transmitter for communicating data using at least two separate RF channels, the
transmitter comprising:
a data stream partitioner (72, 101, 120) configured to partition a data stream of data
to be communicated into two or more stream partitions,
two or more modulators (73, 74, 102, 103, 181, 182, 211a, 2 1In) configured to
each receive a stream partition and to generate modulated data from the received stream
partition, and
an interleaver (734, 735, 736, 737, 744, 745, 746, 747, 1021, 1022, 1023, 1031,
1032, 1033, 140, 183, 212, 321) configured to assign the modulated data generated by a
modulator from a received stream partition to different RF channels for transmission.
2. The transmitter as claimed in claim 1,
wherein said data stream partitioner (72) is configured to partition the data stream into N
stream partitions and
wherein the transmitter comprises N modulators (211a, .. ., 2 1In), each being configured to
receive a single stream partition.
3. The transmitter as claimed in claim 1,
wherein said data stream partitioner (72, 101, 120) is configured to receive at least two
data streams of data to be communicated and to partition said data streams into two or
more respective stream partitions and
wherein said two or more modulators (73, 74, 102, 103, 181, 182, 211a, 2 1In) are
configured to each receive at least one stream partition from at least two different data
streams.
4. The transmitter as claimed in claim 3,
wherein said two or more modulators (73, 74, 102, 103, 181, 182, 2 11a, 2 1In) are
configured to each receive one stream partition from each data stream.
5. The transmitter as claimed in claim 3,
wherein said interleaver further comprises a combiner (736, 746, 1023, 1033, 147, 148)
configured to combine modulated data generated by different modulators from different
stream partitions of the same data stream and assigned for transmission by the same RF
channel.
6. The transmitter as claimed in claim 1,
wherein said transmitter is configured to communicate the data on OFDM subcarriers of
OFDM symbols and wherein said interleaver is configured to assign the modulated data to
OFDM subcarriers of OFDM symbols of different RF channels for transmission.
7. The transmitter as claimed in claim 1,
wherein said two or more modulators (73, 74, 102, 103) are configured to each generate
OFDM symbols comprising a plurality of cells from the received stream partition and
wherein said interleaver is configured to assign the OFDM symbols or cells of OFDM
symbols generated by a modulator from a received stream partition to different RF chan¬
nels for transmission.
8. The transmitter as claimed in claim 1, wherein said interleaver comprises
a selector (734, 735, 744, 745, 1021, 1022, 1031, 1032) per modulator configured
to select and assign modulated data of the respective modulator to the different RF chan¬
nels,
a combiner (736, 746, 1023, 1033) per RF channel configured to combine modulat
ed data assigned to the respective RF channel, and
a frequency interleaver (737, 747) per RF channel for frequency interleaving of the
combined modulated data of the respective RF channel.
9. The transmitter as claimed in claim 1,
wherein said data stream partitioner (72, 101, 120) is configured to equally partition a data
stream of data to be communicated into two or more stream partitions.
10. The transmitter as claimed in claim 1,
wherein said interleaver is configured to equally assign the modulated data to different RF
channels for transmission.
11. The transmitter as claimed in claim 1,
wherein said interleaver is configured to assign the modulated data to different RF chan¬
nels for transmission proportional to the bandwidth of the different RF channels.
12. The transmitter as claimed in claim 1,
wherein said interleaver comprises cell exchange circuitry.
13. The transmitter as claimed in claim 12,
wherein said cell exchange circuitry is configured to operate in different modes.
14. The transmitter as claimed in claim 12,
wherein said cell exchange circuitry is configured to operate in a channel bonding mode in
which it operates to assign the modulated data generated by a modulator from a received
stream partition to different RF channels for transmission.
15. The transmitter as claimed in claim 12,
wherein said cell exchange circuitry is configured to apply a matrix V(even) for multiplica¬
tion with an input vector of two OFDM carriers or symbols or cells of even index from two
different stream partitions and a matrix V(odd) for multiplication with an input vector of
two OFDM carriers or symbols or cells of odd index from two different stream partitions,
wherein
0 V( n ) = and V( P
0
16. A transmission method for communicating data using at least two separate RF
channels, the transmission method comprising:
partitioning a data stream of data to be communicated into two or more stream
partitions,
receiving a stream partition by each of two or more modulators,
generating modulated data from the received stream partition, and
assigning the modulated data generated by a modulator from a received stream
partition to different RF channels for transmission
17. A receiver for receiving data of a data stream via at least two separate RF channels,
the receiver comprising:
a deinterleaver (831, 832, 833, 834, 841, 842, 843, 844, 191, 192, 193, 421, 431)
configured to receive data of a received data stream via at least two separate RF channels,
wherein the data of stream partitions of the data stream are transmitted via the at least two
RF channels, and to assign the data belonging to the same stream partition transmitted via
different RF channels to different demodulators,
two or more demodulators (83, 84, 113, 114) configured to each receive data of a
stream partition and to generate demodulated data from the received data of the stream
partition,
a data stream combiner (85, 183) configured to combine the demodulated data of
the two or more demodulators into the data stream.
18. The receiver as claimed in claim 17,
wherein the receiver comprises N demodulators (83, 84, 113, 114), each being configured
to receive data from N stream partitions, and
wherein said data stream combiner (85, 183) is configured to combine the demodulated
data from the N demodulators into the data stream.
19. The receiver as claimed in claim 17,
wherein said deinterleaver is configured to assign OFDM symbols or OFDM subcarriers of
OFDM symbols belonging to the same stream partition transmitted via different RF
channels to different demodulators.
20. The receiver as claimed in claim 17,
further comprising a demapper (195) for demapping of the received data,
wherein said deinterleaver is configured to assign i) LLR values of the demapped data or I
and Q values of the data before demapping and/or ii) channel state information before
demapping belonging to the same stream partition transmitted via different RF channels to
different demodulators.
21. The receiver as claimed in claim 17,
wherein said receiver is configured to receive the data on OFDM subcarriers of OFDM
symbols and wherein said deinterleaver is configured to assign the received data from
OFDM subcarriers of OFDM symbols or from OFDM symbols transmitted via different
RF channels to different demodulators.
22. The receiver as claimed in claim 17,
wherein said deinterleaver comprises cell re-exchange circuitry.
23. The receiver as claimed in claim 22,
wherein said cell re-exchange circuitry is configured to operate in different modes.
24. The receiver as claimed in claim 22,
wherein said cell re-exchange circuitry is configured to operate in a channel bonding mode
in which it operates to assign the data belonging to the same stream partition transmitted
via different RF channels to different demodulators.
25. A receiving method for receiving data of a data stream via at least two separate RF
channels, the receiving method comprising:
receiving data of a data stream via at least two separate RF channels, wherein the
data of stream partitions of the data stream are transmitted via the at least two RF channels,
assigning the data belonging to the same stream partition transmitted via different
RF channels to different demodulators,
receiving data of a stream partition by each of two or more demodulators
generating demodulated data from the received data of the stream partition, and
combining the demodulated data of the two or more demodulators into the data
stream.
26. A non-transitory computer-readable recording medium that stores therein a computer
program product, which, when executed by a processor, causes the method according to
claim 16 or 25 to be performed.
27. A system for communicating data using at least two separate RF channels, said
system comprising:
at least one transmitter (70, 90, 100, 180, 190, 200, 210, 230) as claimed in claim 1
and
at least one receiver (80, 110, 190) as claimed in claim 17.