Source: http://patents.com/us-9838235.html
Timestamp: 2017-12-18 07:19:27
Document Index: 383381963

Matched Legal Cases: ['art\n1819078', 'Application No. 62', 'Application No. 62', 'Application No. 62', 'Application No. 62', 'Application No. 62']

US Patent # 9,838,235. Apparatus and method for sending and receiving broadcast signals - Patents.com
United States Patent 9,838,235
A broadcast signal transmitter is disclosed. A broadcast signal transmitter according to the present invention comprises an input formatting module configured to de-multiplex an input stream into at least one PLP (Physical Layer Pipe); a BICM (Bit Interleaved Coded Modulation) module configured to perform error correction processing on the data of the least one PLP; a frame building module configured to generate a signal frame including the at least one PLP; a waveform generating module configured to generate the broadcast signal by inserting a preamble into the signal frame and performing OFDM modulation.
Kim; Jaehyung (Seoul, KR), Mun; Chulkyu (Seoul, KR), Ko; Woosuk (Seoul, KR), Baek; Jongseob (Seoul, KR), Hong; Sungryong (Seoul, KR)
Family ID: 1000002992086
14/918,350
US 20160286525 A1 Sep 29, 2016
62137800 Mar 24, 2015
62138962 Mar 26, 2015
62142487 Apr 3, 2015
62145456 Apr 9, 2015
62152050 Apr 24, 2015
Current CPC Class: H04L 27/265 (20130101); H04L 1/0042 (20130101); H04L 5/005 (20130101); H04L 5/0023 (20130101); H04L 27/2602 (20130101); H04L 27/2647 (20130101); H04L 27/2655 (20130101); H04L 27/2665 (20130101); H04W 72/005 (20130101); H04L 27/2611 (20130101); H04L 27/2613 (20130101); H04L 27/2607 (20130101)
Current International Class: H04W 72/00 (20090101); H04L 27/26 (20060101); H04L 1/00 (20060101); H04L 5/00 (20060101)
9219630 December 2015 Mun et al.
2007/0206692 September 2007 Kwon
2011/0002422 January 2011 Cheng et al.
2011/0317785 December 2011 Petrov
2014/0161209 June 2014 Limberg
2015/0358648 December 2015 Limberg
2016/0212451 July 2016 Stewart
1819078 Aug 2007 EP
4374023 Dec 2009 JP
2013-225755 Oct 2013 JP
WO 2011/099741 Aug 2011 WO
ETSI EN 302 755 v1.3.1 (Nov. 2011), Digital Video Broadcasting (DVB). cited by examiner .
ETSI, "Digital Video Broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital terrestrial television broadcasting system (DVB-T2)," ETSI EN 302 755 V1.3.1, Nov. 2011, 191 pages. cited by applicant.
This application claims the benefit under 35 U.S.C. .sctn.119(e) to U.S. Provisional Application No. 62/137,800 filed on Mar. 24, 2015, to U.S. Provisional Application No. 62/152,050 filed on Apr. 24, 2015, to U.S. Provisional Application No. 62/145,456 filed on Apr. 9, 2015, to U.S. Provisional Application No. 62/138,962 filed on Mar. 26, 2015, and to U.S. Provisional Application No. 62/142,487 filed on Apr. 3, 2015. The entire contents of all these applications are hereby incorporated by reference in its entirety.
1. A broadcast signal transmitter comprising: an input formatter configured to input-format an input stream and output at least one Physical Layer Pipe (PLP); a Bit Interleaved Coded Modulation (BICM) encoder configured to perform error correction processing on the data of the at least one PLP; a frame builder configured to generate a signal frame including the at least one PLP; and a waveform generator configured to perform Orthogonal Frequency Division Multiplexing (OFDM) modulation and to generate a broadcast signal, wherein the waveform generator further comprises a pilot insertion module configured to insert pilots including Continual Pilots (CPs) and Scattered Pilots (SPs) to the broadcast signal, wherein a number of carriers of the signal frame is determined as a maximum number of carriers or determined by reducing a unit from the maximum number of carriers, wherein the unit is obtained by multiplying a control unit value by a reducing coefficient, and wherein the control unit value corresponds to a predetermined number of carriers based on a Fast Fourier Transform (FFT) size.
2. The broadcast signal transmitter of claim 1, wherein the control unit value corresponds to 96 when an 8K FFT size is used, 192 when a 16K FFT size is used and 384 when a 32K FFT size is used.
3. The broadcast signal transmitter of claim 1, wherein the CPs include a common CP set and an additional CP set.
4. The broadcast signal transmitter of claim 3, wherein the common CP set includes a first CP set for 32K FFT mode, a second CP set for 16K FFT mode, and a third CP set for 8K FFT mode; and the first CP set, the second CP set, and the third CP set are generated by using a predetermined first reference CP set.
5. The broadcast signal transmitter of claim 4, wherein the first CP set is generated by adding a second reference CP set to the first reference CP set and the second reference CP set is generated by reversing and shifting the first reference CP set.
6. The broadcast signal transmitter of claim 5, wherein the second CP set is generated by using CPs of every second index from CPs included in the first CP set.
7. The broadcast signal transmitter of claim 5, wherein the third CP set is generated by using CPs of every fourth index from CPs included in the first CP set.
8. The broadcast signal transmitter of claim 3, wherein the additional CP set is added at carrier location of the SPs for ensuring a constant number of data carriers in every data symbol of the signal frame and the additional CP set depends on SP pattern and the FFT size.
9. The broadcast signal transmitter of claim 8, wherein the additional CP set for a specific SP pattern and a specific FFT size is added differently according to the reducing coefficient.
10. A method for transmitting a broadcast signal, comprising: input-formatting an input stream and outputting at least one Physical Layer Pipe (PLP); performing error correction processing on data of the least one PLP; generating a signal frame including the at least one PLP; and generating a broadcast signal by performing Orthogonal Frequency Division Multiplexing (OFDM), wherein the generating the broadcast signal further comprises inserting pilots including Continual Pilots (CPs) and Scattered Pilots (SPs) to the broadcast signal, wherein a number of carriers of the signal frame is determined as a maximum number of carriers or determined by reducing a unit from the maximum number of carriers, wherein the unit is obtained by multiplying a control unit value by a reducing coefficient, and wherein the control unit value corresponds to a predetermined number of carriers based on a Fast Fourier Transform (FFT) size.
11. The method of claim 10, wherein the control unit value corresponds to 96 when an 8K FFT size is used, 192 when a 16K FFT size is used and 384 when a 32K FFT size is used.
12. The method of claim 10, wherein the CPs include a common CP set and an additional CP set.
13. The method of claim 12, wherein the common CP set includes a first CP set for 32K FFT mode, a second CP set for 16K FFT mode, and a third CP set for 8K FFT mode; and the first CP set, the second CP set, and the third CP set are generated by using a predetermined first reference CP set.
14. The method of claim 13, wherein the first CP set is generated by adding a second reference CP set to the first reference CP set and the second reference CP set is generated by reversing and shifting the first reference CP set.
15. The method of claim 14, wherein the second CP set is generated by using CPs of every second index from CPs included in the first CP set.
16. The method of claim 14, wherein the third CP set is generated by using CPs of every fourth index from CPs included in the first CP set.
17. The method of claim 12, wherein the additional CP set is added at carrier location of the SPs for ensuring a constant number of data carriers in every data symbol of the signal frame and the additional CP set depends on SP pattern and the FFT size.
18. The method of claim 17, wherein the additional CP set for a specific SP pattern and a specific FFT size is added differently according to the reducing coefficient.
To solve the technical problems above, a broadcast signal transmitter according to one embodiment of the present invention comprises an input formatting module configured to de-multiplex an input stream into at least one PLP (Physical Layer Pipe); a BICM (Bit Interleaved Coded Modulation) module configured to perform error correction processing on the data of the least one PLP; a frame building module configured to generate a signal frame including the at least one PLP; a waveform generating module configured to generate the broadcast signal by inserting a preamble into the signal frame and performing OFDM modulation, wherein the waveform generating module further comprises a pilot insertion module configured to insert pilots including CPs (Continual Pilots) and SPs (Scattered Pilots) to the broadcast signal and the CPs are inserted in every symbol of the signal frame and the number of the CPs is determined based on FFT (Fast Fourier Transform) size.
In a broadcast signal transmitter according to one embodiment of the present invention, the number of carriers included in the signal frame is reduced by a unit from a maximum number of carriers, the unit being obtained by multiplying a control unit value by a reducing coefficient, and the control unit value corresponds to the predetermined number of carriers which are determined based on the FFT size.
In a broadcast signal transmitter according to one embodiment of the present invention, the control unit value corresponds to 96 when the FFT size is 8, 192 when the FFT size is 16 and 384 when the FFT size is 32.
In a broadcast signal transmitter according to one embodiment of the present invention, the CPs include a common CP set and an additional CP set.
In a broadcast signal transmitter according to one embodiment of the present invention, the common CP set includes a first CP set for 32K FFT mode, a second CP set for 16K FFT mode, and a third CP set for 8K FFT mode; and the first CP set, the second CP set, and the third CP set are generated by using a predetermined first reference CP set.
In a broadcast signal transmitter according to one embodiment of the present invention, the first CP set is generated by adding a second reference CP set to the first reference CP set and the second reference CP set is generated by reversing and shifting the first reference CP set.
In a broadcast signal transmitter according to one embodiment of the present invention, the second CP set is generated by deriving CPs of every second index from CPs included in the first CP set.
In a broadcast signal transmitter according to one embodiment of the present invention, the third CP set is generated by deriving CPs of every fourth index from CPs included in the first CP set.
In a broadcast signal transmitter according to one embodiment of the present invention, the additional CP set is added at carrier locations SP for ensuring a constant number of data carriers in every data symbol of the signal frame, and the additional CP set depends on SP pattern and the FFT size.
In a broadcast signal transmitter according to one embodiment of the present invention, the number of carriers included in the signal frame is reduced by a unit from a maximum number of carriers, the unit being obtained by multiplying a control unit value by a reducing coefficient, and the control unit value corresponds to a predetermined number of carriers which are determined based on the FFT size, wherein the additional CP set for a specific SP pattern and a specific FFT size is added differently according to the reducing coefficient.
A method for transmitting a broadcast signal of a broadcast signal transmitter according to one embodiment of the present invention comprises demultiplexing an input stream into at least one PLP (Physical Layer Pipe); performing error correction processing on the data of the least one PLP; generating a signal frame including the at least one PLP; and generating a broadcast signal by inserting a preamble into the signal frame and performing OFDM modulation, wherein the generating a signal frame further comprises inserting pilots including CPs (Continual Pilots) and SPs (Scattered Pilots) to the broadcast signal, the CPs are inserted in every symbol of the signal frame, and the number of the CPs is determined based on FFT (Fast Fourier Transform) size.
FIG. 30 illustrates a block diagram of a synchronization & demodulation module of a broadcast signal receiver in detail according to one embodiment of the present invention.
FIGS. 31 to 33 illustrate embodiments of a flexible NoC structure of a broadcast signal according to the present invention.
FIGS. 34 to 37 illustrate cases according to one embodiment of the present invention, where constraints are generated to maintain a constant NoA when NoC is changed according to FFT size.
FIG. 38 illustrates a method for generating CP indices according to one embodiment of the present invention.
FIG. 39 illustrates a method for generating a CP set according to FFT size according to an embodiment of the present invention.
FIGS. 40 and 41 illustrate a method for generating a reference CP set and generating a CP pattern using the reference CP set according to one embodiment of the present invention.
FIGS. 42 to 45 illustrate a method for generating a reference CP set and generating a CP pattern using the reference CP set according to another one embodiment of the present invention.
FIGS. 46 to 51 illustrate performance and distribution of CP sets shown in FIGS. 42 to 45.
FIG. 52 illustrates additional CP sets according to an embodiment of the present invention.
FIG. 53 illustrates a method for positioning the index of an additional CP set of FIG. 52.
FIG. 54 illustrates a method for transmitting a broadcast signal of another broadcast signal transmitter according to an embodiment of the present invention.
FIG. 55 illustrates a method for receiving a broadcast signal according to one embodiment of the present invention.
The BCH encoding/zero insertion block can perform outer encoding on the scrambled PLS1/2 data using the shortened BCH code for PLS protection and insert zero bits after the BCH encoding. For PLS1 data only, the output bits of the zero insertion may be permutted before LDPC encoding.
The LDPC encoding block can encode the output of the BCH encoding/zero insertion block using LDPC code. To generate a complete coded block, Cldpc, parity bits, Pldpc are encoded systematically from each zero-inserted PLS information block, Ildpc and appended after it. C.sub.ldpc=[I.sub.ldpcP.sub.ldpc]=[i.sub.0,i.sub.1, . . . i.sub.K.sub.ldpc.sub.-1,p.sub.0,p.sub.1,p.sub.N.sub.ldpc.sub.-K.sub.ldpc.- sub.-1] [Equation 1]
The bit interleaver 6010 can interleave the each shortened and punctured PLS1 data and PLS2 data. The constellation mapper 6020 can map the bit interleaved PLS1 data and PLS2 data onto constellations.
The synchronization & demodulation module 9000 can receive input signals through m Rx antennas, perform signal detection and synchronization with respect to a system corresponding to the apparatus for receiving broadcast signals and perform demodulation corresponding to a reverse procedure of the procedure performed by the apparatus for transmitting broadcast signals.
The frame parsing module 9010 can parse input signal frames and extract data through which a service selected by a user is transmitted. If the apparatus for transmitting broadcast signals performs interleaving, the frame parsing module 9010 can perform deinterleaving corresponding to a reverse procedure of interleaving. In this case, the positions of a signal and data that need to be extracted can be obtained by decoding data output from the signaling decoding module 9040 to restore scheduling information generated by the apparatus for transmitting broadcast signals.
TABLE-US-00008 TABLE 8 Current Current Current Current PHY_PROFILE = PHY_PROFILE = PHY_PROFILE = PHY_PROFILE = `000` `001` `010` `111` (base) (handheld) (advanced) (FEF) FRU_CONFIGURE = Only base Only handheld Only advanced Only FEF 000 profile present profile present profile present present FRU_CONFIGURE = Handheld Base Base Base 1XX profile present profile present profile present profile present FRU_CONFIGURE = Advanced Advanced Handheld Handheld X1X profile present profile present profile present profile present FRU_CONFIGURE = FEF present FEF present FEF present Advanced XX1 profile present
3) For the next 359 information bits, is, s=1, 2, . . . , 359 accumulate is at parity bit addresses using following Equation. {(x+(s mod 360).times.Q.sub.ldpc} mod(N.sub.ldpc-K.sub.ldpc) [Equation 6]
where x denotes the address of the parity bit accumulator corresponding to the first bit i0, and Qldpc is a code rate dependent constant specified in the addresses of parity check matrix. Continuing with the example, Qldpc=24 for rate 13/15, so for information bit i1, the following operations are performed: p.sub.1007=p.sub.1007.sym.i.sub.1 p.sub.2839=p.sub.2839.sym.i.sub.1 p.sub.4861=p.sub.4861.sym.i.sub.1 p.sub.5013=p.sub.5013.sym.i.sub.1 p.sub.6162=p.sub.6162.sym.i.sub.1 p.sub.6482=p.sub.6482.sym.i.sub.1 p.sub.6945=p.sub.6945.sym.i.sub.1 p.sub.6998=p.sub.6998.sym.i.sub.1 p.sub.7596=p.sub.7596.sym.i.sub.1 p.sub.8284=p.sub.8484.sym.i.sub.1 p.sub.8520=p.sub.8520.sym.i.sub.1 [Equation 7]
After QCB interleaving, inner-group interleaving is performed according to modulation type and order (mod) which is defined in the below table 32. The number of QC blocks for one inner-group, NQCB_IG, is also defined.
.times..times..times..function..times..function. ##EQU00001## where d.sub.n,s,r,q is the qth cell of the rth XFECBLOCK in the sth TI block of the nth TI group and represents the outputs of SSD and MIMO encodings as follows
.times..times..times..times..function..times. ##EQU00003## where h.sub.n,s,i is the ith output cell (for i=0, . . . N.sub.xBLOCK.sub._.sub.TI(n,s).times.N.sub.cells-1) in the sth TI block of the nth TI group.
FIG. 26A illustrates a writing operation in a time interleaver and FIG. 26B illustrates a reading operation in the time interleaver. As illustrated in FIG. 26A, a first XFECBLOCK is written in a first column of a time interleaving memory in a column direction and a second XFECBLOCK is written in a next column, and such an operation is continued. In addition, in an interleaving array, a cell is read in a diagonal direction. As illustrated in FIG. 26B, while the diagonal reading is in progress from a first row (to a right side along the row starting from a leftmost column) to a last row, N.sub.r cells are read. In detail, when it is assumed that z.sub.n,s,i (i=0, . . . N.sub.rN.sub.c) is a time interleaving memory cell position to be sequentially read, the reading operation in the interleaving array is executed by calculating a row index R.sub.n,s,i a column index C.sub.n,s,i and associated twist parameter T.sub.n,s,i as shown in an equation given below.
.function..function..function..times..function..times..times. ##EQU00004##
Where, S.sub.shift is a common shift value for a diagonal reading process regardless of N.sub.xBLOCK TI (n,s) and the shift value is decided by N.sub.xBLOCK TI MAX given in PLS2-STAT as shown in an equation given below.
.times..times..times.'.times..times..times..times..times..times..times..t- imes.'.times..times..times..times..times..times..times..times..times..time- s.'.times..times. ##EQU00005##
Consequently, the cell position to be read is calculated by a coordinate x.sub.n,s,i=N.sub.r C.sub.n,s,i+R.sub.n,s,i.
A variable N.sub.xBLOCK TI(n,s)=N, will be equal to or smaller than N'.sub.xBLOCK.sub._.sub.TI.sub._.sub.MAX. Accordingly, in order for a receiver to achieve single memory interleaving regardless of N.sub.xBLOCK.sub._.sub.TI (n,s), the size of the interleaving array for the twisted row-column block interleaver is set to a size of N.sub.r.times.N.sub.c=N.sub.cells.times.N'.sub.xBLOCK.sub._.sub.TI.sub._.- sub.MAX by inserting the virtual XFECBLOCK into the time interleaving memory and a reading process is achieved as shown in an equation given below.
.times..times..times..times..times..times.<.times..times.'.times..time- s..times..times..function..times..times..times.<.times..function..times- ..times. ##EQU00006##
In more detail, FIG. 28 illustrates a diagonal reading pattern from respective interleaving arrays having parameters N'.sub.xBLOCK TI MAX=7 and Sshift=(7-1)/2=3. In this case, during a reading process expressed by a pseudo code given above, when V.sub.i.gtoreq.N.sub.cellsN.sub.xBLOCK.sub._.sub.TI (n,s), a value of Vi is omitted and a next calculation value of Vi is used.
FIG. 29 illustrates XFECBLOCK interleaved from each interleaving array having parameters N.sub.xBLOCK.sub._.sub.TI.sub._.sub.MAX=7 and Sshift=3 according to an exemplary embodiment of the present invention.
FIG. 30 illustrates a sub-modules included in the synchronization & demodulation module 9000 of FIG. 9.
The synchronization/demodulation module comprises a tuner 30010 for tuning to a broadcast signal, an ADC module 30020 for converting a received analog signal to a digital signal, a preamble detecting module 30030 for detecting a preamble included in a received signal, a guard sequence detecting module 30040 for detecting a guard sequence included in a received signal, a waveform transform module 30050 for performing FFT on a received signal, a reference signal detecting module 30060 for detecting a pilot signal included in a received signal; a channel equalizer 30070 for performing channel equalization by using an extracted guard sequence, an inverse waveform transform module 30100, a time domain reference signal detecting module 30090 for detecting a pilot signal in the time domain, and a time/frequency synchronization module 30100 for performing time/frequency synchronization of a received signal by using a preamble and a pilot signal. The inverse waveform transform module 30080 performs transformation with respect to the inverse FFT, which may be omitted according to a particular embodiment or replaced with a different module that performs the same or a similar function thereof.
FIG. 30 illustrates a case where the receiver processes a signal received by multiple antennas through multiple paths; identical modules are shown in parallel, descriptions of which are not provided.
In the present invention, the receiver can detect and utilize a pilot signal by using the reference signal detecting module 30060 and the time domain reference signal detecting module 30090. The reference signal detecting module 30060 can detect a pilot signal in the frequency domain, and the receiver can perform synchronization and channel estimation by using the characteristics of the detected pilot signal. The time domain reference signal detecting module 30090 can detect a pilot signal in the time domain of a received signal, and the receiver can perform synchronization and channel estimation by using the characteristics of the detected pilot signal. This document refers to at least one of the module 30060 detecting a pilot signal in the frequency domain and the module 30090 detecting a pilot signal in the time domain as a pilot signal detecting module. Also, in this document, a reference signal is referred to as a pilot signal.
The receiver can detect a CP pattern included in a received signal and perform synchronization through coarse Auto-Frequency Control (AFC), fine AFC, and Common Phase Error (CPE) correction by using the detected CP pattern. The receiver can detect pilot signals included in a received signal by using the pilot signal detecting module and perform time/frequency synchronization by comparing the detected pilot signals with those pilot signals known to the receiver.
The present invention attempts to design a CP pattern that achieves various goals and effects. First, the CP pattern according to the present invention attempts to reduce signaling information and simplify interaction in time interleaving and carrier mapping by maintaining the Number of Active data carrier (NoA) in each OFDM symbol with respect to the predetermined Number of active Carrier (NoC) and a predetermined SP pattern.
Also, the present invention attempts to change the NoC and the CP pattern according to the SP pattern to achieve the condition above. Also the CP pattern according to the present invention attempts to select SP-bearing CP and non-SP-bearing CP fairly so that roughly even distribution over spectrum and random position distribution over spectrum can be achieved to combat a frequency selective channel. And the CP pattern is composed so that the overall overhead of the CP can be preserved and the number of CP positions can be reduced according as the NoC is reduced. The SP-bearing CP and non-SP-bearing CP may be referred to as SP-bearing CP and non-SP-bearing CP. The SP-bearing CP represents the CP of which the position overlaps with the position of the SP, while the non-SP-bearing CP represents the CP of which the position does not overlap with the position of the SP.
The pattern or position information of a CP can be stored in the memory of a transmitter or a receiver in the form of an index table. However, since the SP pattern used in a broadcast system has been diversified and the mode of the NoC has been increased, the size of the index table has increased to occupy a large portion of the memory. Therefore, the present invention tries to solve the aforementioned problem and to provide a CP pattern that satisfies the goal and effects of the CP pattern described above.
In this document, the interval in the frequency domain among SPs included in an SP pattern is denoted by Dx, and the interval in the time domain is denoted by Dy. In other words, Dx represents separation among carriers bearing pilots along the frequency axis, while Dy represents the number of symbols forming one scattered pilot sequence along the time axis.
In the case of a broadcast system, spectrum masks may vary depending on countries and regions. Therefore, depending on the situation, bandwidth of a broadcast signal may have to be changed, and to this purpose, the present invention provides a flexible Number of Carriers (NoC) structure.
Two different methods can be used to compose a signal through the flexible NoC structure.
1) The minimum bandwidth and the minimum NoC according to the minimum bandwidth are determined, and by using the minimum bandwidth and the minimum NoC, NoC is extended by predetermined units. In this method, the non-SP-bearing CP designed according to the minimum NoC is not changed according as the NoC is extended, but since the extended bandwidth is not fully utilized, performance may be degraded. To this purpose, a table may have to be added to determine non-SP-bearing CP which is added as the NoC is increased.
2) The maximum bandwidth and the maximum NoC according to the maximum bandwidth are determined, and by using the maximum NoC, NoC is reduced by predetermined units. In this method, pilots which mask out the non-SP-bearing CP can be used by specifying a window corresponding to the maximum NoC. In this case, the number of CPs is designed to have a margin so that performance degradation due to NoC reduction can be prevented. In other words, the system is designed so that the minimum NoC reduced from the maximum NoC can have a particular number of non-SP-bearing CPs. Also, this method can be used to support such a case requiring additional narrow bandwidth or a smaller NoC. This method can be expressed by Eq. 12 below. NoC=NoC_Max-k*.DELTA. [Equation 12]
In Eq. 12, NoC represents the number of carriers, namely, the number of symbols included in one signal frame, which is the number of OFDM subcarriers. .DELTA. represents the control unit value, and k represents the coefficient multiplied to the control unit value to determine the number of carriers to be reduced. As shown in FIGS. 31 to 33, .DELTA. can be changed according to the FFT size: .DELTA._8K-FFT=96, .DELTA._16K-FFT=192, and .DELTA._32K-FFT=384, respectively. k can take on one value from 0 to 4. k can also be expressed by reduction coefficient (C_(red_coeff)). The maximum NoC (NoC_Max) differs by the FFT size, and as shown in FIGS. 31 to 33, the maximum NoC can be 6529 for 8K FFT, 13057 for 16K FFT, and 26113 for 23 k FFT.
Depending on embodiments, the number of non-SP-bearing CPs can be determined by the maximum NoC or the minimum NoC. As shown in FIG. 31, the system can be structured so that the number of non-SP-bearing CPs with respect to the maximum NoC is 45, and the number of non-SP-bearing CPs with respect to the minimum NoC where k=4 is 43. However, in this case, performance in transmission and reception may be degraded if the bandwidth of the broadcast system is taken into consideration. Therefore, as shown in FIG. 32, the system can be designed so that while the bandwidth window is masked out as NoC is reduced from the maximum NoC, the number of non-SP-bearing CPs with respect to the minimum NoC becomes 45, and inversely, the number of non-SP-bearing CPs with respect to the maximum NoC becomes 48 to prevent performance degradation. FIG. 33 illustrates an embodiment of a method as shown in FIG. 32, where, in the case of 8K FFT, the number of non-SP-bearing CPs changes from 45 to 48; in the embodiment, NoC and the estimated number of CPs vary according to FFT sizes and the values of k.
The present invention composes a system such that NoC can be reduced in multiples of .DELTA. according to the needs from the maximum NoC as shown in Eq. 12. Also, the system is further composed so that the number of non-SP-bearing CPs corresponds to 48 for 8K, 96 for 16K, and 192 for 96 according to the FFT size in the case of the maximum NoC; variation of the number of non-SP-bearing CPs according to the increase of k can be found from FIGS. 31 to 33.
In what follows, described will be a method for maintaining a constant NoA in case flexible NoC is used as described above.
In case flexible NoC is supported, NoC can be extended or reduced in units of Max (Dx); in this case, too, a constant on the number of SP-bearing CPs and positions thereof is generated in order to maintain constant NoA. In case NoC is extended or reduced in units of Dx, such a constraint can be changed according to the SP pattern, FFT size, and k value.
As described above, in case flexible NoC is supported, NoC is reduced by 96, 182, and 384 units according to k values and FFT sizes. However, the SP pattern is repeated by block units corresponding to Dx*Dy. Therefore, if the value of .DELTA. being reduced does not correspond to the multiple of the Dx*Dy block, the pilot pattern configured for a constant NoA is violated. This is so because the NoC may not correspond to the multiple of Dx*Dy since the NoC is reduced by the maximum Dx unit. This fact can be expressed by the following equation. MOD(NoC-1,Dx*Dy) [Equation 13]
In Eq. 13, if the result value for k ranging from 0 to 4 is 0, NoA is maintained, but in other cases, the pilot pattern needs to be changed since the NoA is not maintained. This case occurs when the SP pattern is (Dx, Dy)={(32, 2), (16, 4), (32, 4)} in the case of 8K FFT and the SP pattern is (Dx, Dy)=(32, 4) in the case of 16K FFT.
FIG. 34 illustrates a case where the pilot pattern needs to be changed to support the constant NoA in case 8K FFT is used and the SP pattern (Dx, Dy)=(32, 2). In FIG. 34, in case 8K FFT is used and the SP pattern (Dx, Dy)=(32, 2), the value of MOD(NoC-1, Dx*Dy) is 0 for k=0, 2, 4; and 32 for k=1, 3. Therefore, in case k=1, 3, the pilot pattern needs to be changed to have a constant NoA.
FIG. 35 illustrates a case where the pilot pattern needs to be changed to support the constant NoA in case 8K FFT is used and the SP pattern (Dx, Dy)=(16, 4). In FIG. 35, in case 8K FFT is used and the SP pattern (Dx, Dy)=(16, 4), the value of MOD(NoC-1, Dx*Dy) is 0 for k=0, 2, 3; and 32 for k=1, 3. Therefore, in case k=1, 3, the pilot pattern needs to be changed to have a constant NoA.
FIG. 36 illustrates a case where the pilot pattern needs to be changed to support the constant NoA in case 8K FFT is used and the SP pattern (Dx, Dy)=(32, 4). In FIG. 36, in case 8K FFT is used and the SP pattern (Dx, Dy) (32, 4), the value of MOD(NoC-1, Dx*Dy) is 0 for k=0, 4; 32 for k=1; 64 for k=2; and 96 for k=3. Therefore, in case k=1, 2, 3, the pilot pattern needs to be changed to have a constant NoA.
FIG. 37 illustrates a case where the pilot pattern needs to be changed to support the constant NoA in case 16K FFT is used and the SP pattern (Dx, Dy)=(32, 4). In FIG. 37, in case 16K FFT is used and the SP pattern (Dx, Dy) (32, 4), the value of MOD(NoC-1, Dx*Dy) is 0 for k=0, 2, 4; and 63 for k=1, 3. Therefore, in case k=1, 3, the pilot pattern needs to be changed to have a constant NoA.
Change of the pilot pattern can be used to support a constant NoA according to the change of NoC by using a method for selectively using one SP-bearing CP in case Dy=2 and 1 to 3 SP-bearing CPs in case Cy=4, which will be described again below.
In what follows, described will be a method for generating a common CP set and an additional CP set as a method for generating a CP pattern according to an embodiment of the present invention. A common CP set refers to a set of non-SP-bearing CPs not overlapping with the SP, and an additional CP set refers to a set of SP-bearing CPs overlapping with the SP.
A broadcast system according to an embodiment of the present invention supports both 3 and 4 as a Dx basis value. Since the positions of the non-SP-bearing CP and the SP-bearing CP have to be indexed with predetermined values for all SP modes, the CP is designed with respect to the Dx basis value. Thus, design of the CP can be carried out by the following two methods for the Dx basis 3 and 4.
i) A CP set is designed independently for the Dx basis 3 and 4, and a CP index table is selected in association with selection of the SP mode. ii) One common CP set is selected by taking into account both of the Dx basis 3 and 4 of the selected SP mode, and only one CP index table is defined to be used independently of the SP mode selection.
Characteristics of the two methods above are as follows.
Since the method i) optimizes the position of a CP optimized for each Dx basis case, it provides a better performance than the method ii). Since the method ii) has the same CP index independently of the SP mode, there is no performance degradation due to discontinuity at the boundaries when sync tracking is required among the SP modes having different Dx bases. Also, the method ii) has the advantage that in case initial synchronization is required since the Dx basis is not known beforehand, the receiver can anyhow use an existing CP set compared with the case of using two CP sets. Therefore, in what follows, described will be a method for generating an SP pattern based on the method ii).
FIG. 38 illustrates a method for generating a common CP set, and according to the method, CP sets corresponding to various FFT sizes can be generated by using a reference CP set.
First of all, according to the present invention, a set of non-SP-bearing CPs not overlapping with an SP is generated by taking into account both of the aforementioned SP modes of Dx=3 and Dx=4, where the CP set can be called a reference CP set. The reference CP set can correspond to the left half of the 32K FFT mode CP set. In other words, since the number of CPs in the 32K FFT mode is 180 when k=0, the reference CP set can include 90 CPs. The reference CP set is generated to satisfy the condition that "CPs are positions to be distributed evenly and in random fashion over the predetermined spectrum". The reference CP set is extracted by taking into account various performances of a plurality of CP position patterns generated through a PN generator, which will be described later.
The CP set with respect to the 32K FFT mode (CP_32K) generates an additional right-half CP set (CP_32K,R) by reversing and shifting the reference CP set (CP_32K,L) and adding the right-half CP set to the reference CP set. The reversing operation may be called a mirroring operation, and the shifting operation may be called cycling shifting. The reversing and shifting operation may be regarded as the operation of reducing indices of the reference CP set at the reference carrier positions. The reference carrier position is determined with respect to the shifting value, which may be called a reference index or a reference index value. Generation of the right-half CP set of 32 K mode (CP_32K, R) and the method for generating a CP set of 32K FFT mode using the CP set may be expressed by the equation below. CP_32K,R=reference carrier index-CP_32K,L CP_32K=[CP_32K,L,CP_32K,R] [Equation 14]
A CP set for 16K FFT mode (CP_16) and a CP set for 8K FFT mode (CP_8) can be extracted respectively from the CP set for 32K FFT mode (CP_32). In this case, as shown in FIG. 38, the reference CP set is determined so that extracted CPs can be placed at the same position in the frequency domain.
According to the method, since the broadcast transmitter and the broadcast receiver only have to store the CP set corresponding to the half of the CP indices used in the 32K mode, size of the required memory can be reduced.
A plurality of conditions should be met to determine a reference CP set. For example, i) the position of an SP pattern having the largest Dx value that can be supported for each FFT mode should be avoided, ii) generation of a 16K and 8K CP set should be derived from the CP set of 32K FFT mode through a simple operation such as rounding, ceiling, or flooring, iii) continuity in absolute frequency for all FFT modes should be satisfied.
These CP indices are chosen in such a way to avoid the position of the SP as in FIG. 39, and in particular, the CP indices are also chosen to be positioned at the same position in the frequency domain for 16K and 8K modes. Among the indices chosen, those distributed as evenly and randomly as possible across the signal bandwidth are chosen to be included in the reference CP set.
As described above, if the CP set of 32K FFT mode (CP_32K) is generated by using the reference CP set, the CP set of 16K mode (CP_16K) and the CP set of 8K mode (CP_8K) can be obtained by using the CP set of 32 k FFT mode (CP_32K) and the equations below. In particular, if the condition for continuity in absolute frequency for all FFT modes is relieved, the number 18 can be applied. To achieve better precision of frequency position, more accurate channel estimation based on the more precise frequency position, and frequency/time synchronization, the present invention uses the ceiling operation of Eq. 15; however, operation of Eqs. 16 to 19 may be used depending on the needs. CP_16K=ceil((take every 2nd index of CP_32K)/2) CP_18K=ceil((take every 4th index of CP_32K)/4) [Equation 15]
Equation 15 represents generating a CP set of 16 K mode by applying the ceiling operation on every second index of the CP set of 32K mode divided by two and generating a CP set of 8K mode by applying the ceiling operation on every fourth index of the CP set of 32K mode divided by 4. The ceiling operation value represents the smallest integer among those numbers larger than or equal to the target value. CP_16K=floor((take every 2nd index of CP_32 K)/2)+1 CP_18K=floor((take every 4th index of CP_32K)/4)+1 [Equation 16]
Equation 16 represents generating a CP set of 16 K mode by applying the flooring operation on every second index of the CP set of 32K mode divided by two and generating a CP set of 8K mode by applying the flooring operation on every fourth index of the CP set of 32K mode divided by 4. The flooring operation value represents the largest integer among those numbers smaller than or equal to the target value. CP_16K=round((take every 2nd index of CP_32K)/2) CP_18K=round((take every 4th index of CP_32K)/4+1) [Equation 17] CP_16K=round((take every 2nd index of CP_32K)/2) CP_18K=round((take every 4th index of CP_32K)/4)+1 [Equation 18] CP_16K=round((take every 2nd index of CP_32K)/2) CP_18K=round((take every 4th index of CP_32K)/4) [Equation 19]
In Eqs. 17 to 19, the round operation returns an integer closest to the target value.
The condition for continuity in absolute frequency for all FFT modes should be satisfied in order to perform channel estimation more accurately even if the FFT size is changed. Since pilots are positioned at the same position even if the FFT size is changed, the broadcast receiver can estimate the channel more accurately and compensate the time/frequency offset by using the pilot positions of a preceding and following signal. In other words, it can be more effective particularly in such a case where FFT sizes are different from each other for each segment of a signal in one frame.
FIG. 40 illustrates common CP sets, each of which is a set of CPs not including an SP.
FIG. 40 illustrates a reference CP set generated by taking into account the aforementioned conditions (CP_ref); and a method for generating a CP set when the FFT size is 32 K (CP_32K), a CP set when the FFT size is 16K (CP_16K) and a CP set when the FFT size is 8K (CP_8K)
In FIG. 40, CP_ref represents the reference CP set (CP_32K, L), including pilot indices corresponding to the first half of the 32K mode CP set (CP_32K). The 32K_mode CP set (CP_32K) is generated by using Eq. 14, of which the reference carrier index is 27649. The 16K mode CP set (CP_16K) and the 8K mode CP set (CP_8K) are generated individually by using Eq. 15.
FIG. 41 illustrates CP indices of 32K mode CP set, 16K mode CP set, and 8K mode CP set generated by using the reference CP set of FIG. 40.
FIG. 42 illustrates common CP sets, each of which is a set of CPs not including an SP.
FIG. 42 illustrates a different reference CP set generated by taking into account the aforementioned conditions (CP_32K, L or CP_ref); and a method for generating a CP set when the FFT size is 32 K (CP_32K), a CP set when the FFT size is 16K (CP_16K), and a CP set when the FFT size is 8K (CP_8K)
In FIG. 42, the reference CP set (CP_32K, L) includes pilot indices corresponding to the first half of the 32K mode CP set (CP_32K). The 32K mode CP set (CP_32K) is generated by using Eq. 14 (CP_32K, R=reference index value-CP_32K, L; and CP_32K=[CP_32K, L, CP_32K, R]), and the reference carrier index is 27648. The 16K mode CP set (CP_16K) and the 8K mode CP set (CP_8K) are generated by using Eq. 15 (CP_16K=ceil ((take every 2nd index of CP32K)/2) and CP_16K=ceil (take every 2nd index of CP32K)/4), respectively. In other words, the 16K FFT CP set (CP_16K) can comprise the index values obtained by dividing the first, third, fifth index, and so on of the 32K FFT CP set (CP_32K) by 2 and applying the ceiling function to the division result, while the 8K FFT CP set (CP_8K) can comprise the index values obtained by dividing the first, fifth, ninth index, and so on of the 32K FFT CP set (CP_32K) by 4 and applying the ceiling function to the division result.
FIGS. 43 to 45 illustrate CP sets generated by using the reference CP set of FIG. 43, where FIG. 43 illustrates CP indices of 32K CP set, FIG. 44 illustrates CP indices of 16K CP set, and FIG. 45 illustrates CP indices of 8K CP set.
FIG. 46 illustrates an Average Mutual Information (AMI) plot showing a performance test result with respect to the AWGN channel, FIG. 47 illustrates an AMI plot showing a performance test result with respect to the 2-way Rayleigh channel, and FIG. 48 illustrates an AMI plot showing a performance test result with respect to Tu-6 200 Hz channel. And FIG. 49 illustrates a relationship between the Average Mutual Information (AMI)/bit and distribution index for each channel. The embodiments of FIGS. 42 to 45 correspond to the CP indices generated by taking into account the performance in various channels as shown in FIGS. 46 to 51, compared with the embodiments of FIGS. 40 and 41.
FIG. 50 illustrates that indices of the 32K mode CP set (CP_32K), 16K mode CP set (CP_16K), and 8K mode CP set (CP_8K) exhibit random and even distribution performance.
FIG. 51 is a magnified view of a part of the CP sets of FIG. 50. In FIG. 51, the 8K mode CPs are positioned at the same positions with the 16K mode and 32K mode CPs; and illustrates that the 16K mode CPs are also positioned at the same positions with the 32K mode CPs. Therefore, it can be understood from the descriptions above that performance of channel estimation and frequency synchronization can be improved.
As described above, a CP set includes a common CP set and an additional CP set; and the additional CP set required to retain a constant NoA according to an SP pattern and FFT size (mode) is inserted additionally. The additional CP set is an SP-bearing CP, where fewer than 3 CPs can be inserted if Dy is 4, and one or zero CP can be inserted if Dy is 2.
Since the number of carriers is reduced by a multiple of the control unit value according as the flexible NoC is used as described with respect to FIGS. 34 to 37, the additional CP set has to be changed according to the NoC to retain constant NoA. In FIG. 52, the additional CP set changed in this sense is denoted by parentheses.
In the example of FIG. 52, the additional CP set is changed when the FFT mode is 16K and 8K and the SP mode is SP32-4; when the FFT mode is 8K and the SP mode is SP32-2; and when the FFT mode is 8K and the SP mode is SP16-4. The pilot indices in parentheses may not be used if k cannot be divided by 2, namely, in case k is an odd number (k mod 2=1 where k=1 or 3) in Eq. 12. Each case will be described later.
First, in case the SP pattern is SP32-2 and the FFT mode is 8K, the additional CP set can be changed. In other words, if k is an odd number (for example, k=1 or 3) in the case of flexible NoC, the SP-bearing CP of the CP index 1696 may not be used and the additional SP-bearing CP may not be defined at all.
In case the SP pattern is SP16-4 and the FFT mode is 8K, the additional CP set can be changed. In other words, if k is an odd number (for example, k=1 or 3) in the case of flexible NoC, the CP of index 2912 and the CP of index 5744 may not be used, but only the SP-bearing CP of index 1744 can be added.
In case the SP pattern is SP32-4 and the FFT mode is 16K, the additional CP set can be changed. In other words, if k is an odd number (for example, k=1 or 3) in the case of flexible NoC, the CP of index 5824 and the CP of index 11488 may not be used, but only the SP-bearing CP of index 3488 can be added.
In case the SP pattern is SP32-4 and the FFT mode is 8K, the additional CP set can be changed, and in this case the additional CP set can be inserted differently according to the k value. In other words, if k=1 in the case of flexible NoC, all of the CP of index 1696, CP of index 2880, and CP of index 5728 may not be used nor may the additional CP set be inserted additionally. In case k=2, the CP of index 2880 and the CP of index 5728 may not be used, but only the SP-bearing CP of index 1697 can be added. In case k=3, the CP of index 5728 may not be used, but the SP-bearing CP of index 1697 and the SP-bearing CP of index 2880 can be added. And in case k=0 or k=4, the SP-bearing CPs of index 1696, index 2880, and index 5728 can be added.
In this way, a CP set can be constructed so that a constant NoA can be retained even if bandwidth is masked out as the NoC is formed in a flexible manner.
As described above, in case Dy=2 and Dy=4, 1 and 3 SP-bearing CPs can be added respectively. The SP-bearing CPs are defined at such positions to satisfy the constant NoA, and among those positions, the SP-bearing CPs are inserted to where the CPs can be distributed more evenly and randomly as in FIG. 53.
As described above with respect to the broadcast signal transmitter and its operation, the broadcast signal transmitter can demultiplex input streams into at least one Data Pipe (DP), namely, Physical Layer Pipe (PLP) by using the input formatting module S54010. And the broadcast signal transmitter can perform error correction processing or FEC encoding on the data included in at least one DP (PLP) by using the BICM module S54020. The broadcast signal transmitter can generate a signal frame by mapping the data within the PLP by using the frame building module S54030. The broadcast signal transmitter can insert a preamble into a transmission signal and perform OFDM modulation by using the OFDM generation module S54040. Insertion of a pilot by the broadcast signal transmitter can be carried out by using the methods of FIG. 8 and FIGS. 30 to 53.
The OFDM generation module further comprises a pilot signal insertion module and the performing OFDM modulation S54040 can further comprise inserting a pilot signal including CP and SP into the transmission signal. The CP is inserted into every symbol of the signal frame, and the position of and the number for the CP may be determined based on the FFT size/mode. However, the CP may not be inserted into the preamble symbol part or the bootstrap symbol part.
The broadcast signal transmitter can generate a signal frame by using the frame building module, and in this case, configure the NoC to be flexible, and generate a signal frame according to the configured NoC. In other words, the number of carriers included in the signal frame can be reduced by the unit of multiplication of the control unit value and a predetermined coefficient from the number of the maximum carriers, where the control unit value can correspond to the predetermined number of carriers based on the FFT size. At this time, the control unit value can correspond to 96 in case the FFT size is 8, 192 in case the FFT size is 16, and 384 in case the FFT size is 32. The number of NoC may be transmitted or received being included in the preamble as signaling information. For example, the information representing the coefficient of NoC reduction, k, may be transmitted or received being included in the preamble.
CPs can include a common CP set and an additional CP set. The CPs belonging to a common CP set can be disposed at the positions not overlapping with the SP, while the CPs of an additional CP set can be disposed at the positions overlapping with the SP.
The common CP set can be determined as in FIGS. 31 to 33 and FIGS. 38 to 45. In other words, the reference CP set corresponding to the first half of the 32K FFT mode CP set is stored in the broadcast signal transmitter, and by using the reference CP set, the broadcast signal transmitter can generate and insert 32K, 16K, and 8K mode CP sets respectively as described. In other words, the 32K mode CP set can be generated by adding a right-end CP set generated by reversing and shifting the reference CP into the reference CP set. The 16K mode CP set can be generated by extracting CPs of every second index from among the CPs belonging to the 32K mode CP set, while the 8K mode CP set can be generated by extracting CPs of every fourth index from among the CPs belonging to the 32K mode CP set.
The additional CP set can be inserted into a broadcast signal as shown in FIG. 52. In other words, in case NoC is reduced, a specific FFT size and an additional CP set with respect to a specific SP pattern can be added as different CP indices according to predetermined coefficients.
FIG. 55 illustrates a method for receiving a broadcast signal according to one
As described above with respect to the broadcast signal receiver and its operation, the broadcast signal receiver can perform signal detection and OFDM demodulation on a received broadcast signal by using the synchronization/demodulation module S55010. The broadcast receiver can extract service data by parsing a signal frame of a received broadcast signal by using the frame parsing module S55020. The broadcast signal receiver can convert service data extracted from the received broadcast signal into the bit domain and perform deinterleaving on the converted service data by using the demapping and decoding module S55030. And the broadcast signal receiver can output service data processed by the output processing module into a data stream S55040.
The synchronization/demodulation module further comprises a pilot signal detecting module, and the performing OFDM demodulation S55010 can further comprise detecting a pilot signal such as the CP and SP from a transmission signal. The CP is inserted into every symbol of the signal frame, and the position of and the number for the CP may be determined based on the FFT size/mode.
The frame parsing module of the broadcast signal receiver can parse the signal frame according to the NoC, and information of the NoC intended for the parsing may be transmitted or received being included in the preamble as signaling information. For example, the information representing the coefficient of NoC reduction, k, may be transmitted or received being included in the preamble.
The synchronization/demodulation module of the broadcast signal receiver can further comprise the time/frequency synchronization module and can perform time/frequency synchronization by using pilot signals detected by the pilot detecting module. Since the pilot signals of the aforementioned received signal have the structure/characteristics of the pilot signal inserted by the broadcast signal transmitter described above, the characteristics about the pilot signals of the transmitter can be applied the same to the received broadcast signal. In other words, descriptions of the signal structure, pilot structure, and so on related to FIG. 54 can all be applied to the broadcast signal received by the broadcast receiver of FIG. 55.
The broadcast signal receiver can perform time/frequency synchronization by comparing the pilot signal detected by the time/frequency synchronization module with the predetermined pilot signal position. In this case, the broadcast signal receiver may perform time/frequency synchronization by obtaining the position of the common CP set and the additional CP set as described with respect to the transmitter and comparing the obtained pilot signals with the pilot signals detected from a received signal.
In this document, the DP refers to as the Physical Layer Pipe (PLP), and PLS1 information may be called Layer 1 (L1) static information, and PLS2 information may be called L1 dynamic information.
Previous Patent US 9,838,234 | Next Patent US 9,838,236