`
`USUUG31423931
`
`US 6,314,289 B1
`(10) Patent N0.:
`(12) United States Patent
`
`Eberlein ct al.
`(45} Date of Patent:
`Nov. 6, 2001
`
`(54) APPARATUS AND METHOD FOR
`TRANSMITTING INFORMATION AND
`APPARATUS AND METHOD FOR
`RECEIVING INFORMATION
`
`(75)
`
`Inventors: Ernst Eherleln, (irossenseehach;
`Marco Brelllng, triangen; Jan ‘_
`Stnessel. Numberg; Hetnz Gerhnuser.
`Wa'sch’nfeld. all of DE
`l
`L
`l‘
`)
`(73) Assignee: Fraunhofer—Gesellschaft zur
`Forderung der angewandten
`Forsehung e.V.. Munich (DE)
`
`( it ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b} by 0 days.
`
`(21) APPL N05
`
`092'201729
`
`(22
`(86)
`
`PCT Filed:
`PCT No.:
`
`Dec. 3’ 1998
`PCTIEI’98r‘07850
`
`§ 371 Date:
`
`May 17, 1999
`
`§ 102(9) D3193 M53 17, 1999
`
`(87)
`
`PCT Pub. No.: “(00036783
`9(1- Pub. Dale:Jl.In. 22, 2000
`
`ll'tt.CI.7 ....................................................... [-1040 Tim
`(51)
`(52) U.S. CI. ........................... 455(427; 4555.02; 455x10;
`714F746; 714E758; 375825
`Field of Search .................................... 455(427. 3.02.
`455i”), 111‘ 137; 714(701. 745‘ 764. 751‘
`752’ 758‘ 767. 703‘ 786; 3753290. 264.
`335. 350
`
`(58)
`
`St'
`))
`
`(
`
`43812“
`
`"ted
`References (J
`U.S. PATENT DOCUMENTS
`_
`”“989 Pon‘mler‘
`
`(List continued on next page.)
`
`FOREIGN PATENT DOCUMENTS
`
`” 572 ”1"“
`
`5’1"” (Em'
`OTHER PUBLICATIONS
`
`Samir Kallel. “Complementary Punctured Convolutional
`(CPC) Codes and Their Applications". IEEE Transactions
`on Communications. vol. 43. No. 6. Jun. 1999. pp
`2005—2009.
`
`‘
`‘
`(List continued on next page.)
`Primary Examiner—William Trost
`Assistant Exarrtirter—Congvan Tran
`(74} Attorney, Agent, or Finn—Daugherty & Clements
`LLP
`
`{57)
`
`ABSTRACT
`
`An apparatus for transmitting information comprises a bit-
`stream source for providing a bitstream representing the
`information, a redundancy adding encoder for generating an
`encoded bileream. which is arranged to output. for a first
`number of input hits, a second number of output hits, the
`second number of output bits having at least twice as many
`output hits as the first number of input bits. wherein the
`second number ofoutput bitsincludes two portions ofoutput
`bits. each portion of output bits individually allowing the
`retrieval of information represented by the first number of
`input bits. and the first portion of output bits being coded
`based on the bitstream in a different way with respect to the
`second portion of output bits. The apparatus further com-
`prises a partitioner for partitioning the Roond number of
`output bits into the two portions of output bits and a
`transmitter for transmitting the output bits ul‘the first portion
`via a first channel and the output bits of the second portion
`via a 50‘5““ channel. “1‘5 5‘59““ channel being spatially
`dill‘erent
`from the first channel. An inventive receiving
`apparatus combines the signals received via the first and
`second channels and uses boll"! channel signals for channel
`decoding by removing redundancy. Thus. the transmitting
`receiving system is suitable for provitling‘time and-“or space
`diverstty and.
`in the optimal case. provtdes a CrN value
`which is greater than 4.3 (”3 will) respect lo a two-channel
`system comprising a duplicator in the transmitter and a
`channel-controlled switch in the receiver.
`
`35 Claims, 4 Drawing Sheets
`
`
` tx——Transmtatng ———)t
`
`
`am
`
`|
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 1
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 1
`
`

`

`
`
`37512011
`371143
`
`3751200
`
`411992 Cuilhouscn cl al.
`5,103,459 ‘
`5,258.98? “ 1111993 Wei
`5,319,673
`611094 Brislrman.
`5,435,435
`111996 Briskman.
`5.581.575 “ 1211996 Zehavi eta].
`$592,471
`111997 Briskman.
`5,617,333 "
`411997 Oyamada e1 :11.
`5.657.325
`811997 Lou ct al. .
`5,659,569 “
`811997 Padovani el al.
`5,841,813
`1111998 van Nee .
`...................... 3701335
`5,896,368 ‘
`411999 Dalman etal.
`..
`.
`3481385
`5,956,088 “
`911999 Sheri et al.
`
`6,134,696 * 10.12000 Morelos-Zaragoza e1 31.
`7141790
`...............
`6.144.711 ‘ 1112000 Raleigh et al.
`3751347
`
`6,163,577 “ 1212000 Ekudden elal.
`3751242
`
`............... 3641524A
`
`3701479
`
`OTHER PUBLICATIONS
`
`Brian Kroeger, “Robust Modern and Coding Techniques for
`FM Hybrid IBOC DAB”, USA Digital Radio Home Page,
`www.usadr.com. pp 1—14.
`
`US 6,314,289 Bl
`Page 2
`
`U .S. PATENT DOCUMENTS
`
`(3.. "Two New Coding Techniques for Diver:~‘.i13.r
`Benelli
`Communication Systems“, IEEE Transactions on Commu-
`nications, Sep. 1, 1990, pp. 1530—1538, vol. 38. No. 9. New
`York. US.
`
`Alamouli S M, A simple transmit diversity techique for
`wireless communications, IEEE Journal on Selected Areas
`in Communications, Oct. 1998, pp. 1451—1458, vol. 16 No.
`8.
`
`ETS 300 401, ETS l—European Telecommunications Stan-
`dards Institute Valbonne, France, Jan. 1997, pp 149—158.
`"Purlcturcd Convolutional Codes of Rate (n—l)n and Sim-
`plified Maximum Likelihood Decoding" J. Bihb Cain el 31,
`IEEE Transactions on Information Theory, vol. IT—25. No.
`1, Jan. 1979.
`
`“Channel Coding with Mu ltilevelfPhase Signals”, Gottfried
`Ungerboeck, IEEE Transactions on Information Theory, vol.
`IT—28, No. 1, pp 55—66, Jan. 1982.
`
`* cited by examiner
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 2
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 2
`
`

`

`US. Patent
`
`Nov. 6, 2001
`
`Sheet 1 of 4
`
`US 6,314,289 B1
`
`_____.
`
`______
`
`_.
`
`__8m
`
`\
`
`________
`
`.._
`
`__
`
`.._
`
`cow
`
`__E___
`
`___
`
`3.233.[[1
`
`
`
`
`
`_Della«353nm_o9maEmn—aw_III!
`
`r.E
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 3
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 3
`
`

`

`US. Patent
`
`Nov. 6, 2001
`
`Sheet 2 of 4
`
`US 6,314,289 B1
`
`Fig.2
`
`14Gb
`
`1400
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 4
`
`#1
`
`Q .
`
`79(II
`to
`
`240a
`
`1403
`
`/300
`
`Satellite
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 4
`
`

`

`US. Patent
`
`Nov. 6, 2001
`
`Sheet 3 of 4
`
`US 6,314,289 B1
`
`130
`125
`122
`121
`
`
`
`
`
`
`
`
`multiplex
`
`to 2
`
`bitstreams
`
` Channel 2
`encoder
`
`120
`123
`1400
`
`Parallel to
`serial and
`De-
`
`Channel 1
`
`Convolutional
`
`Fig. 3
`
`Input bit sequence:
`
`403
`
`401
`
`402
`
`———=.> time
`
`After ccnvcluticnal encoder:
`
`411
`
`412
`
`
`
`413
`E=Blt transmitted over early satellite
`L=Blt transmitted over late satellite
`X=not transmitted (punctured) bit
`
`“—9 time
`
`After parallel-to—serial converter:
`
`BEBE-Il-
`
`—'——i time
`
`After demulflptexer:
`
`41o
`
`BEBE
`—-———>- time
`
`Fig. 4
`
`420
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 5
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 5
`
`

`

`US. Patent
`
`Nov. 6, 2001
`
`Sheet 4 0f 4
`
`US 6,314,289 Bl
`
`230a
`
`230b
`
`2203
`
`220b
`
`
`
`2400
`DI
`(M3,,
`
`240d
`
`240a
`
`Channel‘l
`
`Channel2
`
`Fig. 5
`
`.62
`
`IQ
`
`Ema Encoder
`
`-
`
`-
`
`Decoder
`
`62
`
`64
`
`66
`
`72
`
`74
`
`Fig. 6
`
`.65!
`
`7o
`
` Channelz
`
`66b
`
`72b
`
`Fig. 7
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 6
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 6
`
`

`

`US 6,314,289 B1
`
`1
`APPARATUS AND METHOD FOR
`TRANSMITTING INFORMATION AND
`APPARATUS AND METHOD FOR
`RECEIVING INFORMATION
`
`FIELD OF THE INVENTION
`
`invention relates to concepts for digital
`The present
`broadcasting and.
`in particular. concepts for digital broad-
`casting suited for fading channels for wireless communica-
`tion.
`
`ID
`
`BACKGROUND OF THE INVENTION
`
`2
`Bitstreams encoded by means of a convolutional encoder
`can be decoded by a decoder,
`in which the well-known
`Viterbi algorithm is implemented. This algorithm is capable
`of using the channel state information (see P. Hoeher "TCM
`on Frequency-Selective Length-Mobile Fading Channels”,
`Proc. Tirrenia International Workshop Digital
`Communication, Tirrenia. Italy. September 1991). The Vit-
`erbi algorithm can be modified to provide reliability esti-
`mates together with the decoded sequence. This enables soft
`decoding. By applying a soft-output Viterbi algorithm, an
`improvement of about 2 dB is obtained in comparison to
`systems that implement “hard" decision.
`DESCRIPTION OF PRIOR ART
`
`With reference to FIG. 6, a simplified overview of a
`transmitter receiver system described in the European DAB
`Standard is illustrated. The transmitter receiver system gen-
`erally comprises a transmitter section 60 and a receiver
`section 70. The transmitter section 60, in the simplest case,
`comprises a bitstream source 62, a channel encoder 64 and
`a transmitter 66. The receiver section 70, in the simplest
`case, comprises a receiver 72 and a channel decoder 74.
`FIG. 7 illustrates a transmitting receiving setup providing
`for time diversity as well as space diversity. The transmitter
`section 60‘ comprises the bitstream source 62 and the
`encoder 64 that have already been described with respect to
`FIG. 6. In addition, the receiver section 60' comprises a first
`transmitter 66a and a second transmitter 66!). Both trans-
`mitters 66aI and 66b are fed by the same signal output by the
`encoder 64 that is duplicated by a duplicator 67.
`To obtain time diversity, a delay element 68 is coupled
`between the duplicator 67 and the second transmitter 66!).
`In the case of satellite communication, the transmitters
`660 and 66!) are realised by two satellites that reside on
`diflerent orbital positions spaced apart from each other.
`The first channel is defined by the line of sight between
`the first transmitter and the receiver, for example. a car.
`whereas the second channel is defined by the line of sight
`between the second transmitter 66!) and the car that com-
`
`prises the reeeiving section 70'. In the scenario. in which the
`ear traVels on a street to the right and to the left ofwhich are
`high buildings, the possibility is increased that the car will
`receive the transmitted signal from at least one satellite.
`When the case is considered. in which the car is driving
`through a tunnel or under a bridge. the lines of sight to both
`transmitters 66a and 66!) are interrupted. The time diversity
`method implemented by this system shown in FIG. 7,
`however. ensures that the receiver will not be affected by the
`interrupted channel. since the transmission signal is delayed
`by the delay stage 68. Optimally, no transmission interrup-
`tion will result, when the delay time is equal to or greater
`than the travelling time ofthe car through the tunnel or under
`the bridge. Thus.
`the receiving section will. once again.
`receive the transmission signal sent by the transmitter 66:1.
`when it was under the bridge, via a channel 2. Naturally, the
`receiving section 70' comprises another delay stage 78.1% it
`is shown in FIG.
`'7.
`the delay stage 78 of the receiving
`section has to be in the channel that has not been delayed in
`the transmitter section. Thus, the signals at the output of the
`receivers 72:: and 72b are identical, when the delay values
`of the delay stages 78 and 68 are equal.
`A decision stage 79, which is symbol ised as a switch in
`FIG. 7, determines which channel provides the signal with
`the better signal to noise ratio. When it is determined that
`channel 1 provides the stronger signal, the decision stage 79
`is operative to conduct the signal received by the receiver
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 7
`
`15
`
`40
`
`45
`
`Satellite-based broadcasting systems provide an adequate
`communication link only in niral areas,
`in which only a
`small number of e.g. bridges exist. Additionally, rural areas
`usually do not have skyscrapers. Skyscrapers as well as
`bridges or, generally, dcnsly built-up areas are obstacles to
`satellite-based communication systems, since carrier fre-
`quencies used for such communication links involve that a
`channel between a sender. e.g.. a satellite, and a receiver. i.
`e. a mobile or stationary receiver. is characterised by the line
`of visual contact (line of sight) between the sender and the
`receiver. If a skyscraper comes into the line ofvisual contact,
`i.e., the transmission channel between the satellite and the
`receiver, which may be positioned in a car,
`the received
`signal power will decrease substantially.
`Generally, it can be stated that in wireless systems (radio
`systems), changes in the physical environment cause the
`channel to fade. These changes include both relative move-
`ment between transmitter and receiver and moving scatterst'
`reflectors in the surrounding space. In theoretical studies of
`wireless systems, the real channels are usually modelled so
`that they result in trackable analysis. The two major classes
`of fading characteristics are known as Rayleigh and Rician.
`A Rayleigh-fading environment assumes no line ol'sight and ‘
`no fitted reflectorst'scatters. The expected value of the fading
`is zero. If there is a line of sight. this can be modelled by
`Rician-fading. which has the same characteristics as the
`Rayleigh-fading. except for a non-zero expected radio.
`Modern digital broadcasting systems know several means
`for reducing the impact of a channel fading. These concepts
`comprise channel coding on the one hand and several kinds
`of diversity on the other hand. The European standard for
`digital audio broadcasting (DAB). set out in Radio Broad-
`casting Systems; Digital Audio Broadcasting (DAB) To
`Mobile, Portable and Fixed Receivers, ETS 300 401, E'I'S
`l—European Telecommunications Standards Institute,
`Valbonne, France, February 1995, uses difi'erential quadra-
`ture phase-shift keying (DQPSK) as modulation technique.
`The channel encoding process is based on punctured con-
`volutional coding, which allows both equal and unequal
`error protection. M a mother code, a convolutional code
`having a code rate of [#4. a constraint length 7. and octal
`polynominals is used. The puncturing procedure allows the
`effective code rate to vary between 8.9 and li4. Channel
`coding by means of punctured convolutional codes is
`described in “Punctured Convolutional Codes of Rate
`
`50
`
`_
`
`(n—an and Simplified Maximum Likelihood Decoding". J.
`Bibb Cain et al., IEEE Transactions on Information Theory,
`Vol. IT-25, No. 1, January 1979.
`Punctured convolutional codes can be used in connection
`
`with many modulation techniques, such as OFDM, BPSK,
`0AM, etc.
`Different channel encoding techniques are outlined in
`“Channel Coding with Multilevelr’Phase Signals", Gottfried
`Ungerboeck, IEEE Transactions on Information Theory, Vol.
`IT 28, No. 1, pages 55 to 66, January 1982.
`
`00
`
`.‘
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 7
`
`

`

`US 6,314,289 B1
`
`3
`72a into the channel decoder 74 When it is determined in
`block 79 that the signal transmitted over the other channel
`(channel 2) is the stronger one. the decision stage 79 is
`operative to conduct the signal received by the receiver 72b
`to the channel decoder 74.
`
`To summarise. the system illustrated in FIG. 7 comprises
`the following emotial features:
`the signal output by the encoder 64 is duplicated by the
`duplicator 67;
`exactly the same signals, whether delayed or not, are
`transmitted via both channels;
`the signals transmitted over both channels are derived
`from the bitstream output by the bitstream source 62 in
`exactly the same way by means of the encoding process
`carried out
`in the redundancy adding encoder 64
`(repetition code);
`the decision stage '79 compares the signal to noise ratio of
`both channels and selects the channel in which the
`
`ID
`
`15
`
`signal having the better signal to noise ratio is trans-
`mitted;
`the signal transmitted via the other channel is discarded;
`and
`
`TJ U!
`
`the channel decoder 74 only uses one channel, i.e., the
`channel determined by the decision stage 79, for chan-
`nel decoding.
`Besides the technique of channel encoding using a redun-
`dancy adding encoder like a convolutional encoder, different
`types of diversity, e.g., time diversity and space diversity,
`can be implemented to ease the impact of fading channels.
`The bitstream source 62 can be implemented as an audio
`encoder as defined by ISO-MPEG. It provides a bitstream
`comprising useful information. i.e.. encoded spectral values
`of a block of audio samples, and side information. To
`enhance the robustness of the communication link, a for-
`ward error correction encoding is performed by the convo- .
`Iutional encoder 64. In general, the convolutional encoding
`procedure generates redundancy in the transmitted datas-
`tream in order to provide ruggedness against transmission
`distortion.
`Usually. convolutional encoders consist of a specific
`number of shift registers and a number of XOR gates. The
`convolutional encoder described in the E'l‘S Standard is a
`
`40
`
`4
`signal output by the receiver is input in the decoder 74. The
`decoder 74 is operative to decode the encoded biLstream
`output by the receiver 72.
`In modern communication
`systems.
`the decoder 74 implements the above-outlined
`soft-input Viterbi algorithm. As it has already been outlined.
`the Viterbi decoder performs a maximum likelihmd decod-
`ing using the channel state information, which is also called
`“metric". Different algorithms are known for Rician and
`Rayleigh channels.
`Especially in satellite-based communication systems.
`design engineers are confronted with strong demands for
`reducing transmitter power. Reduced transmitter power
`directly translates into system costs. Generally, the costs for
`designing and transporting the satellite(s) into its (their)
`orbital position(s) are directly proportional to the power
`supply needed on board of the satellite. Higher transmitter
`power on board of the satellite also means higher energy
`producing capabilities of the satellite. Thus, it can be stated
`that, under costs aspects, reducing transmitter power is
`essential.
`
`Therefore, the system described in FIG. 7 is disadvanta-
`geous in that. in the receiver, only one channel is used for
`retrieving information, whereas the other channel is dis-
`carded. In extreme situations, in which one channel has
`faded totally, no transmitter power from one transmitter, i.e.,
`one satellite, will reach the receiver. Normally, however, the
`channels will not fade totally. Instead, both channels will
`fade more or less. Thus, the decision stage 79 has to select
`one out of two useful signals. When the case is considered
`that both signals output by the receivers 72a and 72b have
`identical signal to noise ratios, only one signal is selected.
`whereby the transmitter power from the satellite transmitting
`via the other channel is wasted totally.
`SUMMARY OF THE INVENTION
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 8
`
`45
`
`50
`
`convolutional encoder having a code rate of U4. This means
`that the convolutional enCoder produces four output bits for
`one input bit. As it is well known in the art. each output bit
`is derived from the current input bit and a specific combi»
`nation of a certain number of preceding input bits stored in
`the shift registers. The specific combination of the current
`input bit and certain preceding input bits for each encoder
`output bit is defined by the so-called generator polynomi-
`nals. The octal forms of the generator polynominals defined
`in the ETS 300 401 are 133, 171, 145 and 133.
`The encoded bitstream can be punctured for raising the
`code rate from U4 to another code rate. e.g.. 819. "Punctur-
`ing" means that certain bits in the convolutional encoder .
`output bits are discarded and not forwarded to the transmit-
`ter 66. Thus, puncturing operates to again reduce redun-
`dancy in an encoded bitstream, which has been added by the
`convolutional encoder.
`
`00
`
`transmitter
`The transmitter 66 may comprise usual
`elements, such as a QPSK modulator, an IFFT block (lFFT:
`Inverse Fast Fourier Transform) for performing orthogonal
`frequency division multiplexing. a guard interval inserter, a
`synchronisation sequence inserter and modulation means for
`modulating the signal onto a high frequency carrier.
`Analogously, the receiver 72 comprises an HF front end,
`an analogtdigital converter, and a QPSK demodulator. The
`
`is the object of the present invention to provide an
`It
`apparatus and method of transmitting information and an
`apparatus and method of receiving information, which result
`in better receiver output signal quality andr'or reduced trans-
`mitter power demands.
`In accordance with a first aspect ofthe present invention,
`this object
`is attained by an apparatus for transmitting
`information, comprising a bitstream source for providing a
`bitstream representing the information; a redundancy adding
`encoder for generating an encoded bitstream based on the
`biLstream provided by the bitstream source wherein the
`encoder is arranged to on tpu l, for a first number of input bits,
`3 second numberof output bike, the second number ofoutput
`bits having at least twice as many output bits as the first
`number of input bits. and wherein the second number of
`output bits includes two portions of output bits, each portion
`of output bits individually allowing the retrieval of infor-
`mation represented by the first number of input bits, and the
`first portion of output bits being coded based on the bit-
`stream in a different way with respect to the second portion
`of output hits; a partitioner for partitioning the second
`number of output bits into the two portions of output bits;
`and a transmitter for transmitting the output bits of the first
`portion via a first channel and the output bits of the second
`portion via a second channel,
`the second channel being
`spatially diflerent from the first channel.
`In accordance with a second aspect of the present
`invention, this object is attained by an apparatus for receiv-
`ing information, the information being represented by an
`.‘ encoded biLstream,
`the encoded bitstream being encoded
`such that its redundancy is at least doubled with respect to
`a bitstream from which the encoded bitstream is derived, and
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 8
`
`

`

`US 6,314,289 B1
`
`5
`that, for a first number of bits of the bitstream, the encoded
`bitstream] comprises a second number of bits.
`the second
`number of bits having at least twice as many bits as the first
`number. and wherein the second number ofbits includes two
`portions of bits, each portion of bits individually allowing
`the retrieval of information represented by the first number
`of bits, and the first portion of the bits being encoded in a
`different way with respect to the second portion of bits. the
`apparatus comprising a receiver for receiving the first por-
`tion of bits via a first channel and the second portion of bits
`via a second channel. the first and the second channels being
`spatially different from each other; a combiner for combin-
`ing the first and the second portions; and a decoder for
`decoding the coded bitstream by removing redundancy from
`the coded bitstream. the decoder using the first and second
`portions of bits combined by the combiner.
`In accordance with a third aspect of the present invention.
`this object
`is attained by a method of transmitting
`information, comprising the following steps: providing a
`bitstream representing the information; generating a redun-
`dancy added encoded bitstream based on the bitstream
`provided in the step of providing, wherein for a first number
`of input bits, 3 second number of output bits is generated, the
`second number of output bits having at least twice as many
`output hits as the first number of input bits. and wherein the
`second number of output bits includes two portions of output
`bits, each portion of output bits individually allowing the
`retrieval of information represented by the first number of
`input bits, and the first portion of output bits being coded
`based on the bitstream in a different way with respect to the
`second portion of output bits; partitioning the second num-
`ber of output bits into the two portions of output bits; and
`transmitting the output bits of the first portion via a first
`channel and the output bits of the second portion via a
`second channel, the second channel being spatially different
`from the first channel.
`
`In accordance with a fourth aspect of the present
`invention. this object is attained by a method of receiving
`information.
`the information being represented by an
`encoded bitstream.
`the encoded bitstream being encoded
`such that its redundancy is at least doubled with respect to
`a bitstream from which the encoded bitstream is derived. and
`that, for a first number of bits of the bitstream, the encoded
`bitstream comprises a second number of bits.
`the second
`number of bits having at least twice as many biLs as the first
`number. and wherein the second number ofbits includes two
`portions of bits. each portion of bits individually allowing
`the retrieval of information represented by the first number
`of bits. and the first portion of the bits being encoded in a
`different way with respect to the second portion of hits, the
`method comprising the following steps: receiving the first
`portion of bits via a first channel and the second portion of
`bits via a second channel, the first and the second channels
`being spatially different from each other; combining the first
`and the second portions; and decoding the coded bitstream
`by removing redundancy from the coded bitstream. wherein
`the first and second portions of bits combined in the step of
`combining are used in the step of decoding.
`The present
`invention is based on the finding that,
`although there are two physically different channels both
`channels are considered as one single channel from the
`viewpoint of the channel decoder located in the receiving
`section. This means that the channel decoder in the receiving
`section does not know that the signals it decodes stem from
`two physically. i. e. spatially. different channels. However.
`the inventive system, in fact, provides two different physical
`channels to allow for time andfor space diversity.
`
`ID
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`The space diversity can be obtained by two terrestrial
`transmitters. by two satellite transmitters or by one satellite
`transmitter and one terrestrial transmitter.
`
`In accordance with the present invention. an apparatus for
`transmitting information comprises a bitstream source for
`providing a bitstream representing the information. A redun-
`dancy adding encoder for generating an encoded bitstream
`based on the bitstream provided by the bitstream source is
`arranged to output. for a first number of input bits. a second
`number of output bits. the second number of output bits
`having at least twice as many output hits as the first number
`of input bits. and wherein the second number of output bits
`includes two portions of output bits, each portion of output
`bits individually allowing the retrieval of information rep-
`resented by the first number of input bits, and the first
`portion of output bits being coded based on the bitstream in
`a different way with respect to the second portion of output
`bits. Ameans for partitioning. i.e., a partitioner, receives the
`output of the redundancy adding encoder and partitions the
`second number of output bits into the two portions of output
`bits. Means for transmitting transmit the output bits of the
`first portion via a first channel and the output biLs of the
`second portion via a second channel. wherein the second
`channel is spatially different from the first channel.
`In accordance with another aspect of the present
`invention, an apparatus for receiving information comprises
`a receiver for receiving the first portion of bits via a first
`channel and the second portion ofbiLs via a second channel.
`a combiner for combining the first and the second portions
`and a decoder for decoding the coded bitstream by removing
`redundancy from the coded bitstream. the decoder using the
`first and second portions of bin: combined by the combiner.
`This inventive transmitter receiver concept provides the
`following advantages:
`two channels allow time andior Space diversity:
`the partitioner partitions rather than duplicates the output
`signal of the encoder into two portions of output hits;
`the combiner in the receiver combines rather than selects
`the signals received from both channels and feeds the
`combined signal into the channel decoder;
`the signals from both channels are used for decoding all
`the time;
`in the best case, in which the signal powers in both
`channels are identical. transmitter power used for trans-
`mitting via each channel can be halved at least. thus,
`halving system costs with respect to the system illus-
`trated in FIG. 7; and
`when the transmitter powers are not changed, the signal
`quality output by the channel decoder can be consid-
`erably improved.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The foregoing and other objects, features and advantages
`of the invention will become more readily apparent from the
`following detailed description of preferred embodiments
`which proceeds with reference to the drawings.
`FIG. 1 shows a principle overview of a transmiwion
`receiving system in accordance with the present invention.
`comprising an inventive transmitter and an inventive
`receiver.
`
`FIG. 2 shows a more detailed block diagram of the
`transmission receiving system shown in FIG. 1. in which
`time and space diversity are embodied.
`FIG. 3 shows a detailed block diagram of an inventive
`transmitter section.
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 9
`
`Petitioner Sirius XM Radio Inc. - Ex. 1001, p. 9
`
`

`

`US 6,314,289 B1
`
`7
`FIG. 4 shows an input bit sequence and an output bit
`pattern of a convolutional encoder used in an inventive
`transmitter section.
`FIG. 5 shows a detailed view of an inventive receiver
`section.
`
`FIG. 6 shows a generalised block diagram of a prior art
`transmitting receiving system.
`FIG. 7 shows a block diagram of a transmitter receiver
`system implementing time and space diversity, in which the
`output of the transmitter encoder is duplicated and a channel
`selection is performed in the receiver.
`DESCRIPTION OF PREFERRED
`EMBODIMENTS
`
`In FIG. 1 a general block diagram of an inventive appa-
`ratus for transmitting 100 and an inventive apparatus for
`receiving 200 is illustrated. The transmitting apparatus 100
`comprises a bitstream source 110. a redundancy adding
`encoder 120 and a partitioner 130. The bitstream source 110
`may be an MPEG encoder as described above. The encoder
`120 is generally a redundancy adding encoder for generating
`an encoded bitstream on its output, wherein the encoder 120
`is arranged to output. for a first number of input hits. a
`second number of output hits. the second number of output
`bits having at
`least twice as many output hits as the first
`number of input bits. This means that
`the encoder 120
`implements a code rate equal to or less than 112. As it is
`known in the art, the code rate is defined by the number of
`input bits divided by the number of output biLs produced by
`the encoder based on the number of input bits.
`In other
`words. a code rate 113 means that for each input bit, two
`output bits are produced. Analogously. a code rate of 113
`means that for each input bit. three output bits are produced.
`Similarly. a code rate of 3!}? means that for three input bits.
`eight output bits are produced.
`The code rate of the encoder 120 is set to be smaller than
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`10
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`rJ III
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`the second number of output bits can be
`U2, such that
`sub-divided into two portions of output hits, such that each
`portion of output bits individually allows the retrieval of
`information represented by the first number of input bits
`This means that a decoder 220 located in the receiving
`apparatus is able to retrieve information represented by the
`bitstream output by the bitstream source 110 when only one
`channel,
`i.e.. channel
`1 300 or channel 2 400 provides a
`useful signal. whereas the other channel has faded totally.
`Another feature of the encoder 120 is that the first portion
`of output bit is coded based on the bitstream in a different
`way with respect to the Second portion of output bits. In
`contrast to a simple repetition code in which redundancy is
`doubled by simply duplicating a signal to transmitted coded.
`the channel decoder 220 capabilities are enhanced, since the
`signal
`is transmitted over the channels 300 and 400 are
`derived from the bitstream output by the bitstream source
`110 independently of each other. The partitioner 130 feeds
`means for transmitting, i.e., a transmitter, 140 for transmit- _
`ting the first portion of output bits via the first channel 300
`and the second portion of output bits via the second channel
`400. It is to be noted that both channels 300 and 400 are
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`the transmitting means 140 may comprise one
`Thus,
`transmitter. cg. one satellite and a delay stage, such that two
`different channels are created between the single transmitter
`and a mobile receiver. when the mobile receiver is at a first
`position and between the single transmitter and the mobile
`receiver when the mobile receiver has moved to a second
`
`position after the period defined by the delay stage in the
`transmitter. This concept is called time diversity for mobile
`receivers. Naturally, it is not possible to create two channels
`different from each other between a single stationary trans-
`mitter and a stationary receiver.
`Alternatively. as it is described with reference to FIG. 2,
`the transmitting means 140 comprise two tr