JP2024023636A - Transmission device and transmission method - Google Patents

Abstract

A method and communication apparatus for transmitting payload data using orthogonal frequency division multiplexing (OFDM) symbols is provided. [Solution] A transmitting device that transmits payload data using OFDM symbols, which receives payload data transmitted from a plurality of different channels, and transmits the payload data received from each channel in a plurality of time frames. A frame builder 26 configured to frame a trusted payload data frame and, for each of the plurality of payload data frames, frame synchronization OFDM symbols, one or more first signaling OFDM symbols and one or more first a modulator 30 that generates two signaling OFDM symbols and modulates one or more payload OFDM symbols with payload data received from each channel; and a transmitter 40 that transmits multiple payload data frames as multiple transmission frames. and. [Selection diagram] Figure 2

Description

The present disclosure relates to a transmitting apparatus and method for transmitting payload data using orthogonal frequency division multiplexing (OFDM) symbols.

This application claims priority under the Paris Convention of UK Patent Application No. 1611071.0, the entire contents of which are incorporated herein by reference.

There are many examples of wireless communication systems that use orthogonal frequency division multiplexing (OFDM) to communicate data. For example, television systems configured to operate according to the Digital Video Broadcasting (DVB) standard use OFDM for terrestrial and cable transmission. OFDM can generally be described as providing K narrowband subcarriers (where K is an integer) that are modulated in parallel. Each subcarrier communicates a modulated data symbol, such as a quadrature amplitude modulation (QAM) symbol or a quadrature phase shift keying (QPSK) symbol. The subcarriers are modulated in the frequency domain, transformed into the time domain, and then transmitted. Because the data symbols are communicated in parallel on the subcarriers, the same modulation symbol can be communicated on each subcarrier for a long time. The subcarriers are modulated simultaneously and in parallel so that the modulated carriers jointly constitute an OFDM symbol. Therefore, an OFDM symbol includes multiple subcarriers, each of which is modulated simultaneously and has a different modulation symbol. During transmission, the OFDM symbol is preceded by a guard interval inserted with a cyclic prefix of the OFDM symbol. The guard interval, if present, is provided to be a period of time that absorbs any echoes of the transmitted signal that may be caused by multipath.

As Advanced Television Systems Committee (ATSC) 3.0 in a publication entitled "ATSC Standard: A/321, System Discovery and Signaling" ^[1] It has been proposed for known television systems to include a preamble in a transmitted television signal carrying a broadcast digital television program. The preamble includes a so-called "bootstrap" signal. The bootstrap signal is intended to provide the receiving device with a portion of the transmitted signal that is more detectable and thus can serve as a signal for initial detection. This is because broadcast stations are expected to not only broadcast television, but also provide multiple services within the range of their broadcast signal.

However, ISDB-T, the current standard for broadcast networks that employs OFDM, where services are time division multiplexed (TDM) on a single channel, limits the capacity of mobile services once a tuner is configured. There is a problem. As demand for mobile TVs increases, these problems will become more apparent.

The next standard, ISDB-T3, proposes to design a frame structure that can be configured for frequency division multiplexing (FDM) or TDM. Such frame structures are proposed herein and defined with respect to embodiments of the present technology.

Further aspects and embodiments of the disclosure are provided in the appended claims, including a transmitting apparatus and method.

According to embodiments of the present disclosure, a transmitter transmits payload data using orthogonal frequency division multiplexed OFDM symbols, the transmitter receives the payload data transmitted from a plurality of different channels, and receives the payload data transmitted from a plurality of different channels. a frame builder configured to frame payload data received from each of said channels for a time frame into a plurality of payload data frames for transmission; and for each of said plurality of payload data frames, one or more frame synchronization OFDM symbols; and configured to generate a plurality of first signaling OFDM symbols, one or more second signaling OFDM symbols, and modulate the one or more payload OFDM symbols with payload data received from each of the channels. a modulation section; and a transmission section that transmits the plurality of payload data frames as a plurality of transmission frames, each of the plurality of transmission frames including one or more payload OFDM symbols, and one or more of the one or more payload data frames. The payload OFDM symbol is preceded by a frame synchronization OFDM symbol, followed by said one or more first signaling OFDM symbols, followed by said one or more second signaling OFDM symbols, and said frame synchronization The OFDM symbol and the one or more first signaling OFDM symbols are transmitted with a bandwidth equal to the radio frequency transmission bandwidth, the one or more second signaling OFDM symbols and the one or more payloads. OFDM symbols are transmitted in the radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more payload OFDM symbols are each frequency divided to provide multiple frequency segments. and the plurality of frequency segments each transmit payload data from a different channel, and the one or more second signaling OFDM symbols in each frequency segment are different from the one or more payload OFDM symbols. transmitting one instance of a plurality of instances of physical layer signaling for channel-by-channel detection and recovery of said payload data transmitted over a plurality of frequency segments; said one or more first signaling OFDM symbols; Provided is a transmitting device that transmits first signaling data for detecting the second signaling OFDM symbol.

This disclosure relates to co-pending patent applications no. No. 7, US14/226937, PCT/GB2014/050870, GB1305795.5, PCT/GB2014/050954, GB1312048.0, TW103121570, PCT/GB2014/051679, EP13170706 .9, PCT/ Supported by EP2014/061467, GB1403392.2, GB1405037.1, TW103121568, PCT/GB2014/051922 and GB1420117.2.

In the appended claims, various further aspects and features of the disclosure are defined, including a method of transmitting payload data.

FIG. 1 is a schematic diagram showing the configuration of a broadcast transmission network. FIG. 2 is a schematic block diagram illustrating an exemplary transmission chain for transmitting broadcast data over the transmission network of FIG. FIG. 3 is a schematic diagram illustrating an OFDM symbol in the time domain including a guard interval. FIG. 4 is a schematic block diagram illustrating an exemplary receiving apparatus for receiving data broadcast by the broadcast transmission network of FIG. 1 using OFDM. FIG. 5 is a schematic diagram illustrating a transmission frame for simultaneously transmitting payload data including multiple services in multiple segments separated in the frequency domain according to an embodiment of the present technology. FIG. 6 is a schematic block diagram illustrating a portion of the transmitting apparatus shown in FIG. 2 for transmitting frame-synchronized OFDM symbols according to an embodiment of the present technology. FIG. 7 is a schematic diagram illustrating a pseudo-noise sequence generation circuit used to generate frame-synchronized OFDM symbols according to an embodiment of the present technology. FIG. 8 is a schematic diagram illustrating a frame synchronization OFDM symbol in the frequency domain according to an embodiment of the present technology. FIG. 9 is a flowchart illustrating exemplary operations of a transmitting device in generating one or more frame-synchronized OFDM symbols by cyclically shifting a time-domain symbol sequence according to an embodiment of the present technology. FIG. 10 is a schematic diagram illustrating a time-domain structure of a frame-synchronized OFDM symbol according to an embodiment of the present technology. FIG. 11 is a schematic diagram illustrating a second time domain of a first signaling OFDM symbol according to an embodiment of the present technology. FIG. 12 is a schematic block diagram illustrating an example receiving apparatus for detecting and recovering signaling from one or more frame-aligned OFDM symbols. FIG. 13 is a schematic block diagram illustrating a receiving apparatus for detecting a frame-synchronized OFDM symbol including identifying a trigger time for performing a forward Fourier transform on an OFDM symbol according to an embodiment of the present technology. FIG. 14 is a schematic block diagram illustrating a correlator configured to detect frame-aligned OFDM symbols according to an embodiment of the present technology. FIG. 15 is a flowchart illustrating detection of a used sequence and frequency offset in a receiving device when generating a frame synchronization OFDM symbol and a first signaling OFDM symbol according to an embodiment of the present technology. FIG. 16 is a schematic block diagram illustrating a portion of a receiving apparatus, such as the example shown in FIG. 4, configured to detect a relative cyclic shift of a signature sequence according to an embodiment of the present technology. FIG. 17 is a schematic block diagram illustrating a portion of a receiving apparatus, such as the example shown in FIG. 4, configured to detect a relative cyclic shift of a signature sequence according to an embodiment of the present technology. FIG. 18 shows the block error rate versus symbol-to-noise ratio showing the difference in performance between a method using conjugate multiplication and a frequency domain decoding algorithm using division as shown in FIGS. 16 and 17 according to an embodiment of the present technology. It is a graph. FIG. 19 is a diagram illustrating segmented OFDM reception according to an embodiment of the present technology. FIG. 20 is a schematic block diagram illustrating a portion of a narrowband receiver configured to detect a relative cyclic shift of a signature sequence according to an embodiment of the present technology.

Hereinafter, embodiments of the present disclosure will be described by way of example with reference to the accompanying drawings. In each figure, similar parts are given corresponding reference numerals.

Embodiments of the present disclosure can form a transmission network for transmitting signals representing video and audio data, such as forming a broadcast network for transmitting television signals to a television receiving device. It can be configured as follows. In some examples, a device for receiving audio/video of a television signal may be a mobile device that receives the television signal while on the move. In other examples, the audio/video data may be received by a conventional television receiving device. The television receiving device may be of a fixed type and may be connected to one or more fixed antennas.

The television receiving device may or may not include an integrated display for television images and may be a recorder device including a plurality of tuners and demodulators. The antenna may be built into the television receiver. A connected or built-in antenna may be used to facilitate reception of different signals as well as television signals. Accordingly, embodiments of the present disclosure are configured to facilitate different types of devices in different environments receiving audio/video data representing television programming.

It will be appreciated that receiving television signals using a mobile device while on the move can be more difficult because the wireless reception conditions differ considerably from those of conventional television receiving devices that receive input from a fixed antenna.

An example of a television broadcast system is shown in FIG. A broadcast television base station 1 shown in FIG. 1 is connected to a broadcast transmitter 2. The broadcast television base station 1 shown in FIG. The broadcast transmitting device 2 transmits the signal received from the broadcast television base station 1 within the coverage area of the broadcast network. The television broadcast network shown in FIG. 1 can operate as a so-called multi-frequency network. In a multi-frequency network, each broadcast television base station 1 transmits a signal at a frequency different from that of other adjacent broadcast television base stations 1. The television broadcast network shown in FIG. 1 can also operate as a so-called single frequency network. In a single frequency network, each broadcast television base station 1 transmits a radio signal carrying audio/video data simultaneously so that it can be received by television receiving devices 4 and mobile devices 6 within the coverage area of the broadcast network. In the example shown in FIG. 1, the signal transmitted from the broadcast television base station 1 is transmitted using orthogonal frequency division multiplexing (OFDM), so that even if the signal is transmitted from a different broadcast television base station 1, , each broadcast transmitting device 2 can be configured to transmit the same signal that can be synthesized by the television receiving device. The spacing between broadcast television base stations 1 is such that the propagation time between signals transmitted by different broadcast television base stations 1 is less than or does not substantially exceed the guard interval preceding the transmission of each OFDM symbol. In some cases, the receiving device 4 and the mobile device 6 may receive an OFDM symbol and may further recover data from the OFDM symbol by combining signals transmitted from different broadcast television base stations 1. can. Examples of broadcast network standards that employ OFDM in this way include DVB-T, DVB-T2, and ISDB-T.

FIG. 2 is an exemplary block diagram illustrating a transmitting device forming part of a broadcast television base station 1 for transmitting data from audio/video sources. In FIG. 2, different audio/video channels 20, 22, and 24 produce different audio/video data representing television programs or content. The audio/video data is provided to frame builder 26 after being encoded and modulated. The frame builder 26 is configured to form data to be transmitted in payload data frames or transmission time frames corresponding to time division units. For each payload data frame, physical layer signaling data is provided by a physical layer data block 28 and transmitted in addition to each payload data frame. That is, for each of the audio/video channels 20, 22, and 24, a plurality of payload data for each of a plurality of time frames corresponding to a plurality of transmission frames generated in a transmission signal by the transmitter shown in FIG. Audio/video data is formed into frames. The frame comprises a time division or frequency division interval with a preamble in which physical layer signaling is transmitted, and one or more data transmitting audio/video data generated by audio/video channels 20, 22, and 24. It may also include a transmission period. The data may be interleaved, formed into symbols, and then supplied to the OFDM modulation section 30. The output of the OFDM modulation section 30 is passed through a guard insertion section 32 that inserts a guard interval, and the obtained signal is supplied to the transmission section 40. The signal is transmitted from the transmitter 40 by the antenna 42. The signaling and synchronization information generated by the signaling and synchronization generation section 34 may be provided to the guard insertion section 32. Signaling information transmitted together with the frame synchronization signal and the first signaling symbol is generated by the signaling information unit 36 and supplied to the synchronization signal generation unit 38. The synchronization signal generation unit 38 generates a frame synchronization signal and a first signaling symbol. As explained below, the signaling information may be expressed as a signature sequence that modulates a first signaling OFDM symbol relative to a signature sequence of frame-aligned OFDM symbols as a relative cyclic shift of the frame-aligned OFDM symbols in the time domain.

Similar to conventional configurations, OFDM is configured to generate symbols in the frequency domain. In the frequency domain, data symbols to be transmitted are mapped onto subcarriers. The subcarriers are transformed to the time domain using an inverse Fourier transform. The inverse Fourier transform may constitute a part of the OFDM modulation section 30. In this way, the data to be transmitted is formed in the frequency domain and transmitted in the time domain. As shown in FIG. 3, each time-domain symbol is generated with a useful part of duration Tu seconds and a guard interval of duration Tg seconds. The guard interval is generated by copying part of the useful part of the symbol with duration Tg in the time domain. However, the copied portion may be generated from the end of the symbol. By correlating the useful part of the time-domain symbol with the guard interval, the receiving device can be configured to detect the beginning of the useful part of the OFDM symbol. Starting from this starting point, the samples of time-domain symbols can be transformed into the frequency domain using a fast Fourier transform. Transmitted data can be restored from the frequency domain. Such a receiving device is shown in FIG.

In FIG. 4, a receiving antenna 50 is configured to detect an RF signal that has passed through a tuner 52 and has been converted into a digital signal by an analog/digital converter 54. Thereafter, the guard interval is removed by the guard interval removal unit 56. After detecting the optimal position to perform a fast Fourier transform (FFT) and transforming the time domain samples to the frequency domain, the FFT unit 58 transforms the time domain samples to form frequency domain samples. The samples are supplied to a channel estimation and correction unit 60. Channel estimation and correction section 60 estimates a transmission channel used for equalization, for example, using pilot subcarriers embedded in OFDM symbols. After excluding the pilot subcarriers, all subcarriers containing data are provided to the demapper section 62. Demapper section 62 extracts data bits from subcarriers of OFDM symbols. These data bits are then provided to a deinterleaver 64 which deinterleaves the subcarrier symbols. The data bits are then provided to a bit deinterleaver 66. The bit deinterleaver 66 performs deinterleaving so that the error correction decoder can correct errors according to the error correction operation, for example, using redundant data included in forward error correction encoding processing.

Framing Structure FIG . 5 shows a schematic diagram of the framing structure of frames according to an embodiment of the present technology that can be transmitted and received in the systems described with reference to FIGS. 1-4. FIG. 5 shows a proposed general structure of a transmit signal for transmitting data from different channels. For example, this structure can be used to transmit different television channels within an ISDB-T3 frame. As shown in FIG. 5, the transmission frame includes the following:
- Frame synchronization OFDM symbol 501 used by the receiving device to detect the beginning of the frame and estimate the carrier frequency offset.
- A first preamble containing one or more (m) special OFDM symbols. The special OFDM symbol may be referred to as the first signaling OFDM symbol 502 (P1). The first signaling OFDM symbol 502 (P1) conveys initial signaling information regarding the structure of the second preamble.
- A second preamble containing one or more OFDM symbols. The OFDM symbols may be referred to as second signaling OFDM symbols 504 and 505 (P2) that convey physical layer (layer 1) parameters. The parameters describe how to transmit the payload with the post-preamble waveform for every segment of the frame. Suitable parameters are described, for example, in the DVB standard and the draft ATSC 3.0 physical layer standard at the filing date. In embodiments, the signaling data carried by each of the one or more second signaling OFDM symbols within a frame is the same. In one example, this may be structured in a loop that transmits data for each segment. That is, the different frequency segments 507.1, 507.2, and 507.3 of the second signaling OFDM symbols 504 and 505 (P2) are This is an example of band information that defines the structure of payload OFDM symbol 506.
- A post-preamble section containing a number of payload OFDM symbols 506. The payload OFDM symbol 506 carries a payload and includes services formed from audio/video data generated by different channels and divided into physical layer pipes (PLPs). The number of payload OFDM symbols 506 may be signaled by second signaling OFDM symbols 504 and 505. The term physical layer pipe (PLP) is used to identify the channel of audio/video data that can be recovered from a transmitted frame.
- Each channel provided by frequency segments 507.1, 507.2, and 507.3 of the payload OFDM symbol It terminates with a closing symbol (FCS) 508.

In embodiments, a frame frequency synchronized OFDM symbol 501 is immediately followed by one or more first signaling OFDM symbols 502. In embodiments, the last symbol of one or more first signaling OFDM symbols 502 in a frame is immediately followed by one or more second signaling OFDM symbols 504 and 505. In embodiments, the last symbol of one or more second signaling OFDM symbols 504 and 505 in a frame is immediately followed by a payload OFDM symbol 506.

As mentioned above, the transmitted frame is further divided into M frequency segments 505.1, 507.2, and 507.3, thereby also dividing each OFDM symbol of the frame. The number M of segments per frame is configurable and signaled by the first signaling OFDM symbol.

The frame synchronization OFDM symbol and the first signaling OFDM symbol are inherently wideband because they are configured to span the entire channel bandwidth. However, these symbols can be detected and decoded both in wideband receivers, where the bandwidth spans the entire channel, and in narrowband receivers, where the bandwidth is equal to the bandwidth of one of the M segments. Both the second signaling OFDM symbol and the payload OFDM symbol are modulated separately for each segment and then concatenated in the frequency domain in segment order prior to transformation to the time domain by IDFT. Therefore, when performing frequency segmentation, the second signaling OFDM symbol and the payload OFDM symbol must be decoded for each segment.

In embodiments, the radio frequency transmission bandwidth 514 of the transmitted signal shown in FIG. 5 represents a bandwidth for a frame of about 6 Mhz or about 8 Mhz. However, it will be appreciated that these are merely examples and other radio frequency transmission bandwidths may be used such that embodiments of the present disclosure are not limited to these bandwidths.

The following paragraphs describe how the first signaling OFDM symbol can be configured, how the first signaling OFDM symbol can convey signaling information, how the first signaling OFDM symbol can convey not only how the information to be transmitted is decoded at the receiving device, but also how the frame-aligned OFDM symbols can be constructed at the transmitting device and how the frame-aligned OFDM symbols can be detected at the receiving device. Describe it.

Synchronization Signal FIG. 6 is a schematic block diagram of a portion of the transmitter shown in FIG. 2 configured to transmit a frame synchronization signal. In FIG. 6, a signature sequence generation section 600 is configured to generate a signature sequence that is mapped to subcarriers of OFDM symbols constituting a frame synchronization OFDM symbol by a subcarrier mapping and zero padding section 602. The frequency domain signal is then transformed into the time domain by an inverse Fourier transform unit 604. Signaling information transmitted in the frame synchronization signal is provided by a first input 605 to a cyclic shift unit 606 . The cyclic shift unit 606 also receives, by a second input 607, time-domain OFDM symbols representing frame-aligned OFDM symbols. In embodiments of the present technology, the combination of operation of the cyclic shifter 606 and its inputs may correspond to the signaling and synchronization generator 34 shown in FIG. 2. As explained below, the signaling information is represented as a relative cyclic shift of the frame-aligned OFDM symbols in the time domain as a signature sequence that modulates a first signaling OFDM symbol to a signature sequence of frame-aligned OFDM symbols. The first signaling OFDM symbol is then provided to a guard interval inserter 608. Guard interval insertion section 608 adds a guard interval to the frame-synchronized OFDM symbol in a format in which the OFDM symbols constituting the frame-synchronized OFDM symbol are transmitted by transmitting section 609.

The frame synchronization OFDM symbol has a similar structure to the first ATSC 3.0 bootstrap symbol described in A/321 ^[2] . The frame synchronization OFDM symbol is a 2048p FFT size OFDM symbol. The value of p can be one of {0.25, 0.5, 1, 2, 4}, which allows frame-synchronized OFDM symbols to be of {512, 1K, 2K, 4K, 8K} FFT size, respectively. OFDM symbol.

As shown in FIG. 6, the signature sequence generation section 600 includes a pseudorandom sequence generation section 610 and a Zadoff-Chu (ZC) sequence generation section 612 used to generate the signature sequence. These two sequences are multiplied by a multiplier 614, and the multiplied sequence is mapped onto subcarriers of the OFDM symbol by a subcarrier mapping and zero padding unit 602. As shown in FIG. 6, a seed value for the pseudorandom sequence generator 610 is provided at a first input 620, and a second input 622 provides an indication of the root of the Zadoff-Chu sequence generator 612. The ZC sequence is generated using Equation 1 below.

（ｑは、ＺＣ系列のルートとして定義されている。）

(q is defined as the root of the ZC sequence.)

As explained with reference to FIG. 6, a frame-synchronized OFDM symbol consists of coefficients of a Zadoff-Chou (ZC) sequence multiplied by positive and negative coefficients generated by the pseudo-noise (PN) sequence generator shown in FIG. Configured in the frequency domain by mapping to carriers. Therefore, the multiplied sequences according to embodiments are described as (ZC*PN) sequences.

FIG. 7 is a schematic diagram showing a pseudo-noise generation circuit 610 that constitutes a part of the signature sequence generation section 600 shown in FIG. 6, which is used when generating a frame-synchronized OFDM symbol according to an embodiment of the present technology. . The PN sequence is generated by the generation circuit shown in FIG. 7 using (polynomial) Equation 2 below. At the beginning of each frame, each element 701, 702, 704, and 706 (r _I ) is initialized with a selected 16-bit seed g. This seed takes the form shown in Equation 3.

（ただし、各ビット７１１、７１２、７１４、７１６、７１８、及び７１９（ｇ_ｉ）は、０又は１のいずれかのバイナリ値を有する。１６ビットシードｇを形成するために、これらを複数の加算要素７２１、７２２、７２４、及び７２６により組み合わせる。）

(where each bit 711, 712, 714, 716, 718, and 719 (g _i ) has a binary value of either 0 or 1. To form the 16-bit seed g, combined by elements 721, 722, 724, and 726).

FIG. 8 shows the mapping of (ZC*PN) sequences to symmetrically form signature sequences on OFDM symbols.

As shown in FIG. 8, in the frequency domain, the frame synchronization signal can be considered to include a bisection 810 of a symmetric Zadoff-Chu (ZC) sequence. Each symbol in the Zadoff-Chu sequence is configured to modulate an active carrier 812. Correspondingly, the PN sequence is configured to modulate subcarriers as shown in line 814. The other subcarriers of the frame sync signal are not used and are therefore set to zero, as shown, for example, at the ends of frame sync signals 820 and 822.

The length of the (ZC*PN) sequence N _a is a configurable parameter called the number of useful subcarriers per frame synchronization OFDM symbol. This means that the (ZC*PN) coefficient is mapped only to the central _Na subcarrier of the frame-aligned OFDM symbol, and the other subcarriers (at the low and high band edges of the symbol) are set to zero. means. The (ZC*PN) sequence has mirror symmetry in its construction, and the central coefficient is set to zero.

As shown in FIG. 8, the ZC sequence and PN sequence are mapped onto OFDM subcarriers in mirror symmetry with respect to the central DC subcarrier of the OFDM symbol. The subcarrier value of the nth symbol of frame synchronization (0≦n<N _B ) can be calculated as shown in Equations 4 and 5 below. However, N _H =(N _ZC -1)/2, N _B is the number of symbols, and p(k) is an element of the PN sequence. A ZC sequence is determined by its root q. The root q may be the same for each symbol, but the PN sequence increases with each symbol.

The last symbol has the phase of the subcarrier values of that particular symbol reversed (ie, rotated 180 degrees). This provides frame synchronization and a clear end indication of the preamble signal. This is provided if there is another symbol, in which case the receiving device provides an unambiguous indication of the last OFDM symbol. That is, any number of synchronization and signaling OFDM symbols can be used. Therefore, the receiving device can detect the phase reversal and therefore the end of the frame synchronization signal.

In one example, signaling data may be transmitted in a first signaling symbol by performing a data-determined cyclic shift of a frame-aligned OFDM symbol in the time domain. This is done by the cyclic shift block shown in FIG. FIG. 9 summarizes the process for transmitting signaling bits.

In FIG. 9, in step S900, the sequence generation unit 600 forms a frequency domain sequence in the frequency domain. In step S902, the IFFT unit 604 performs inverse Fourier transform to transform the frequency domain signal into the time domain. In this way, in step S904, the sequence is formed in the time domain. As shown in step S906, signaling bits are formed and then interpreted as relative cyclic shift values in step S908. In step S910, the relative shift value is converted to an absolute shift value. As shown by arrow S912, the time domain sequence formed in step S904 is then shifted according to the absolute cyclic shift determined in step S910. Finally, in step S914, a time domain sequence to be transmitted is generated.

In one example time-domain structure , each frame-synchronized OFDM symbol is formed from three parts, referred to as A, B, and C by the transmitter. As described above, an OFDM symbol is usually formed by using a guard interval, which is generated by copying an interval of an OFDM symbol in the time domain, as a preamble to the OFDM symbol in order to take into account multipath reception in a receiving device. Each frame synchronized OFDM symbol is formed in one of two ways. Frame synchronization OFDM symbols and first signaling symbols formed by different methods in the time domain are shown in FIGS. 10 and 11. As shown in FIGS. 10 and 11, the data transmission portion of the symbol, which is the original configuration of the OFDM symbol before the guard interval is added, is represented as section A (1001, 1101). Therefore, interval A (1001, 1101) is derived as a 2048p point IFFT of the frequency domain structure with or without the cyclic shift described above to represent the signaling bits transmitted by the frame-synchronized OFDM symbol. However, section A (1001, 1101) is an effective part of a symbol made up of 2048p samples formed by IFFT. Intervals B (1002, 1102) and C (1004, 1104) are changed from interval _A (1001, 1101) and correspondingly removed at the receiving device. Each frame sync OFDM symbol and first signaling symbol consists of 3072p samples consistently. However, section A (1001, 1101) consists of 2048p samples, section C (1004, 1104) consists of 520p samples and 1006 and 1008, 1106 and 1108 of section A (1001, 1101), and section B ( 1002, 1102) consists of the last 504p samples and 1006 and 1106 of section C (1004, 1104) to which a frequency shift of ±f _Δ has been applied.

The frame synchronization OFDM symbol is provided for the synchronization detection of the specific (ZC*PN) sequence that it transmits, and adopts the C-A-B structure as shown in Fig. 10, with a frequency shift of +f _Δ in the interval. Apply to B (1002). By selecting (ZC*PN), you can signal the major and minor standards in use, the alert status that can be used to provide an emergency alert condition, the identification of the transmitting device, the location of the transmitting device, etc. can.

The one or more first signaling symbols may have a B-CA structure as shown in FIG. 11 that carries signaling information and includes a phase-reversed final symbol that provides termination of the preamble signal as described above. A frequency shift of −f _Δ is applied to section B (1102).

Frame synchronization OFDM symbols shall be used for initial time synchronization and may signal other aspects of the system through selection of ZC root and/or PN seed parameters. This symbol does not signal any additional information. Further, the cyclic shift of this symbol is always 0.

A differentially encoded absolute cyclic shift M _n (0≦M _n <N _FFT ) is applied to the nth first signaling OFDM symbol, modulo the length of the time-domain sequence, with the absolute It is calculated by summing the cyclic shift and the relative cyclic shift for symbol n.

Then, an absolute cyclic shift is applied to obtain a shifted time-domain sequence from the output of the IFFT operation.

Frame synchronization at the receiver: The wideband receiver needs to detect the presence of a frame synchronization OFDM symbol as a marker of the start of a frame. The receiving device will be pre-configured with proper values for p, N _a and Δf. Frame-synchronized OFDM symbols can be detected in the time domain, but may require additional processing, e.g. to discover any carrier frequency offset and/or to ascertain which (ZC*PN) sequence is used. processing must be performed in the frequency domain. However, detecting a frame synchronization OFDM symbol is equivalent to detecting the start of a frame.

FIG. 12 is a schematic block diagram illustrating the application of the receiving device shown in FIG. 4 when operating to detect the presence of frame-aligned OFDM symbols. As shown in FIG. 4, the signal detected by the antenna 50 is supplied to an RF tuner 52 and then to an A/D converter 54. Thereafter, the received digital sampling signal is supplied to the forward Fourier transform processing section 58 and also to the first input of the switch 1201. The switch 1201 is controlled by the control unit 1202 and switches the received digital sampling signal between the frame synchronization detection unit 1204 and the second frame synchronization processing unit of the two frame synchronization processing units 1206 and 1210. The frame synchronization detector 1204 performs FFT processing via a channel 1208 to identify the most effective portion of the received signal that is transformed from the time domain to the frequency domain for the purpose of verifying the frame synchronization signal and restoring the signaling data. generates a trigger signal that is supplied to section 58; The received signal converted into the frequency domain by the output of the FFT processing section 58 is provided to the first frame synchronization processing section 1210 . The first frame synchronization processor 1210 is configured to generate a first estimate of a channel transfer function (CTF) H(z) on the output channel 1212.

An exemplary detector of frame-aligned OFDM symbols of a preamble signal is shown in FIG. As mentioned above, only the first frame synchronization OFDM symbol has a CAB structure that is transmitted for initial synchronization. FIG. 13 is an exemplary block diagram illustrating a frame synchronization OFDM symbol detector. As shown in FIG. 13, the received discrete time signal r(n) is supplied to a delay section 1301 and a CAB structure detection section 1302. The CAB structure detector 1302 generates an estimate of the fine frequency offset (FFO) through a first output 1304 . The fine frequency offset is a frequency shift that is smaller than the OFDM symbol subcarrier spacing and may occur during the transmission of frame-aligned OFDM symbols. Additionally, the output from the second channel 1306 is a timing trigger instruction indicating the period of the received OFDM symbol, which is converted by the FFT processing unit 58 to capture as much energy as possible of the received OFDM frame-synchronized OFDM symbol. be done. However, before converting the received frame-aligned OFDM symbols to the frequency domain, all frequency offsets are removed in multiplier 1308. The multiplier 1308 receives at a first input the delayed received signal from the delay section 1301 and receives at a second input the inverse of the total frequency offset formed by the adder 1310 and the tone generator 1312. The total frequency offset is one of the fine frequency offset (FFO) estimated by the CAB structure detection unit 1302 and supplied to the first input, and the integer frequency offset (IFO) estimated by the frame synchronization signal processing unit 1310. Or it is formed by the adder 1310 from both. The total frequency offset is input to tone generator 1312, causing tone generator 1312 to generate a sinusoidal tone at a frequency equal to the total frequency offset. The frame synchronization signal processing unit 1210 generates an IFO by correlating the frequency domain subcarrier with a regenerated signature sequence generated by a combination of ZC sequences modulated with a PN sequence. Then, the IFO is estimated using the position of the peak of the correlation output. The IFO is the frequency domain displacement of a number of subcarriers with respect to a reference frequency within the main frequency band of the frame synchronization signal. In this way, all frequency offsets are estimated and removed by the multiplier 1308 and the tone generator 1312 from the FFO estimated by the structure detector 1302 and the IFO estimated by the frame synchronization signal processor 1210.

As mentioned above, the CAB structure detector 1302 shown in FIG. 13 for detecting frame synchronized OFDM symbols generates an FFO and converts the effective portion of the input signal burst for forward Fourier transform (FFT). used to indicate

FIG. 14 is a schematic block diagram illustrating a correlator configured to detect frame-aligned OFDM symbols according to an embodiment of the present technology. This detection indicates the start of the A portion of the frame synchronization OFDM symbol on which an FFT can be performed. The remainder of the process includes detection of the (ZC*PN) sequence used in the frame synchronization OFDM symbol followed by decoding of the signaling parameters carried by the next first signaling OFDM symbol. Each subsequent first signaling OFDM symbol uses the same known segments of the ZC and PN sequences as its frame synchronization OFDM symbol. Therefore, first, it is posted which ZC (sequence root) sequence and PN (sequence seed) sequence was used.

As shown in FIG. 14, the received discrete time signal r(n) is supplied to a delay section 1402 and a multiplication section 1408, and is frequency shifted in accordance with the frequency adjustment e ^j2πfT of the tone generation section 1401. The output of the multiplication section 1408 is fed to two further delay sections 1404 and 1406. Delay units 1404 and 1406 serve to delay the received signal by a number of samples equal to the number of A, A_B, and B portions of the frame synchronization OFDM symbol. The output of each delay unit is passed to further multiplier units 1410 , 1412 and 1414 where it is multiplied by the complex conjugate of the received discrete time signal r(n) and fed to moving average filters 1416 , 1418 and 1420 . This forms a correlation with the received signal according to delays A, A+B, and B. The output of moving average filter 1416 is delayed by delay element 1422, and the output of moving average filters 1418 and 1420 is upscaled by scaling elements 1424 and 1426, respectively. The outputs of the two scaling elements 1424 and 1426 are summed in an adder 1428. The output of the adder is then multiplied by the output of delay element 1422 by multiplier 1430 to produce a peak-combined sample. The peak-combined samples are generated by correlating each section C, A, and B of the received signal with its respective copy to identify the peak at which the FFT trigger point is detected at output 1432. Accordingly, the phase of that peak determines the FFO provided by output 1434.

The used (ZC*PN) sequences are mapped to subcarriers of frame synchronization OFDM symbols. For ATSC3.0, the used sequence is formed by the following multiplication.
Multiply the ZC series by root q=137,
The PN sequence is multiplied by one of the generator seeds in Table 2 below.

Other PN sequence seeds and other possible generator polynomials can be defined and used. Therefore, for ATSC 3.0, there are 8 possible (ZC*PN) sequences that the transmitting device can use. In embodiments of the present technology, all eight sequences are generated and stored in advance at the receiving device. When attempting to detect which of the eight sequences was used, the receiving device may correlate each stored sequence in turn with the FFT result of the A portion of the frame-aligned OFDM symbol. The sequence that yields the highest peak correlation is the (ZC*PN) sequence used at the transmitter. The frequency offset is the relative bin position of the peak correlation from -F _max to F _max . where F _max is the maximum target integer frequency offset in the FFT bin.

A flowchart of this procedure is shown in FIG. R ₁ (k) is the FFT of the frame-synchronized OFDM symbol, and C _i (k) is the i-th (ZC*PN) sequence. Once the integer frequency offset and the (ZC*PN) sequence are detected, the receiving device can proceed to decoding the first signaling OFDM symbol after frequency offset correction.

The flowchart shown in FIG. 15 may be summarized as follows.
Start: At the beginning of the process, the received symbols are in the frequency domain, as shown in FIG. In embodiments, the symbol spectrum may be derived from an FFT of more than 2048p spectral output components and may be oversampled.
S1501: At the start of the loop, initialize the variable index of the reference signature series to i=1.
S1502: Thereby, cyclic correlation is performed between the received frequency domain OFDM symbol and the i-th signature sequence.
S1504 and S1506: If the reference signature sequence i is the same as the one used in the transmitter, a significant peak value is detected in the cross-correlation output within the IFO. If no significant peak value is detected, processing proceeds to step S1508, where the variable index i of the reference signature sequence is increased and cross-correlation is attempted on the next reference signature sequence. The candidate reference signature sequence may be stored in advance in the receiving device along with an index based on a combination of the Zadoff-Chu root and the PN generator seed used to generate the particular sequence.
S1510: If no significant peak of cross-correlation is detected, the current value i becomes the index of the desired reference signature sequence. If the spectrum is oversampled, the relative positions of the peaks in the cross-correlation output are used to determine the integer frequency offset (IFO) and fine frequency offset (FFO).
At stop, processing ends.

Detection of first signaling data signaling is transmitted by each first signaling OFDM symbol. The signaling parameters are encoded as relative cyclic shifts by the A part of the first signaling OFDM symbol. Also, the relative cyclic shift is differentially encoded from symbol to symbol. In one example, the decoding process can detect a cyclic shift in a given symbol, which can then be differentially decoded with the cyclic shift of the previous symbol. In one example, the differential cyclic shift is determined as part of the decoding process itself. This is advantageous in that it avoids explicit channel estimation and correction, which is quite computationally intensive.

Let R _n (k), H _n (k), P _n (k), and Z _n (k) be the received spectrum sequence, channel transfer function, used PN sequence, and used ZC sequence for the nth symbol, respectively. do. However, k is a subcarrier index. Also, let M _n-1 be the absolute cyclic shift in symbol n-1. On the other hand, let m be the incremental cyclic shift for symbol n-1 that encodes the signaling parameter transmitted by symbol n. It is assumed that the following equation 16 holds for a given frame for the first signaling OFDM symbols n-1 and n.

That is, if the same ZC sequence is used for the frame synchronization OFDM symbol and all the first preamble symbols of a given frame, and the noise of symbol n is specified as N _n (k), it can be written as in Equation 17 below. be able to.

Assume that n-1=0, M _n-1 =0, that is, there is no cyclic shift in the frame synchronization OFDM symbol of the frame. The decoding algorithm involves dividing R _n (k) by R _n-1 (k) and determining the phase gradient of the residual signal representing the cyclic shift of m samples between the two symbols. Therefore, it can be calculated as shown in Equation 18 below.

If the duration of each frame synchronization OFDM symbol or the first preamble symbol is short, then for a given center frequency f ₀ and relative receiver speed v = c/f _o (where c is the speed of light), two successive symbols It is reasonable to assume that the channel remains essentially constant between. That is, the following equation 19 holds true.

As an example, for f ₀ =690 MHz, which is at the highest range of the UHF band used for television, v would need to exceed approximately 1564 km/h for the channel to vary significantly from symbol to symbol.

In the above equation, the noise increases multiplicatively, making analysis difficult and reducing performance. Nevertheless, since the relative cyclic shift that is desired to be decoded is within the phase gradient, the amplitudes of the component results in the above equations are not particularly important. Therefore, division by R _n-1 (k) can be changed to multiplication by its conjugate. This avoids unwieldy calculations and adds all noise to the main phase signal. As far as the phase gradient is concerned, the result of division is equal to the result of multiplication by the conjugate.

The second and third terms on the right side are modulation noise. On the other hand, since P _n and P _n-1 are positive and negative series, the last term is just white noise. Since all noise increases additively, the coupling index of these terms depends on the SNR of the received signal. Therefore, at reasonable levels of SNR, it is expected that the resulting argument or phase trajectory will be dominated by the first term on the right-hand side. In this way, by detecting the resulting phase gradient, the relative cyclic shift m between two symbols can be detected. Further, since the following equation 22 holds true, the cyclic shift can also be detected by performing IFFT on the result and obtaining the sample position of the peak amplitude.

This algorithm is shown in FIG. According to the receiving device shown in FIG. 16, a signal down-converted by the RF tuner 52 is received, and after the received signal passes through the guard interval removing section 56, all prefixes and postfixes are removed. The received signal is fed into two branches. In the first branch, the received signal is delayed by a delay unit 1601 by a number of samples equal to the effective part of the OFDM symbol so that the previous received spectrum sequence R _n−1 is transformed by the first FFT unit 1604. Ru. The received signal is also provided through a second branch such that each received symbol is also transformed by a second FFT section 1602. Here, the conjugate 1606 of the output of the first FFT section 1604 is multiplied by the output of the second FFT section 1602 in a multiplication section 1608. The result of the multiplication unit 1608 is then divided by a division unit 1610 into multiple PN sequences used for the current and previous symbols 1620 and provided to an IFFT unit 1612. The signal passed through the IFFT section 1612 and subjected to IFFT conversion is input to the peak detection section 1614, and is subtracted from the spectral output component of 2048p by the subtraction section 1618.

Further processing of the peak position at the output of the peak detector, ie subtraction from 2048p, can be avoided if R _n-1 (k) is divided by R _n (k). In this case, using conjugation instead of division, the related expression becomes Equation 23 below.

This method is shown in FIG.

Since FIG. 17 is substantially the same as FIG. 16, only the differences will be described. In contrast to FIG. 16, the receiving device shown in FIG. 17 forms the conjugate of the currently received spectral sequence R _n . The spectral sequence R _n is conjugated by a conjugate unit 1606, and multiplied by the output of the received spectral sequence R _n−1 before being subjected to FFT transformation by a multiplier 1608. The result of the multiplier 1608 is then divided by a plurality of PN sequences used for the current and previous symbols 1720 by a divider 1610. No subtraction from 2048p is needed here. Therefore, the final output is received from peak detector 1614.

As shown in the examples of FIGS. 16 and 17, according to embodiments of the present technology, by detecting a cyclic shift in the signature sequence carried by the frequency synchronized OFDM symbol and one first signaling OFDM symbol, An arrangement for estimating first signaling data is provided. As shown in the example of FIG. 16, FFT sections 1602 and 1604 continuously transform the time length of each effective portion of the frequency synchronized OFDM symbol and one or more first signaling OFDM symbols into the frequency domain. It is composed of It will be appreciated that in other examples, a single FFT section can be used instead of the two FFT sections 1602 and 1604 and operated sequentially. Multiplying unit 1608 receives each frequency domain sample of the current first signaling OFDM symbol, and receives one or more first signaling OFDM symbols immediately preceding one of the frame synchronization OFDM symbols or the current first signaling OFDM symbol. Each sample is configured to be multiplied by the conjugate generated by the conjugate section 1606 of one corresponding sample of the OFDM symbol to generate an intermediate sample for each subcarrier sample. The IFFT unit 1612 is configured to transform intermediate samples obtained from the current first OFDM symbol into the time domain. A cyclic shift detector formed from the peak detector 1614 detects a cyclic shift of the signature sequence present in each of the one or more first signaling OFDM symbols from the peak of the intermediate sample transformed into the time domain. is configured to estimate first signaling data transmitted by each of the one or more first signaling OFDM symbols.

Accordingly, according to embodiments of the present technology, a receiving apparatus is configured to detect first signaling data by detecting a relative cyclic shift between a frequency synchronized OFDM symbol and a first signaling OFDM symbol. can do. As a result, only addition noise exists in the detection process. Therefore, conjugate multiplication as shown in FIGS. 16 and 17 provides an advantage, since the signaling data can be accurately estimated by detecting the cyclic shift of the signature sequence with a lower signal-to-noise ratio.

FIG. 18 shows the block error rate versus symbol-to-noise ratio showing the difference in performance between a method using conjugate multiplication and a frequency domain decoding algorithm using division as shown in FIGS. 16 and 17 according to an embodiment of the present technology. It is a graph.

The plot is for an additive white Gaussian noise (AWGN) channel and shows that the algorithm of conjugate multiplication, as employed in embodiments of the present technique, has a significant difference in SNR compared to using actual division. You can clearly see that it is very good. This comparison becomes more pronounced in the presence of multipath.

In narrowband reception, the receiving device tunes only to the relevant segment. This is illustrated in the representation of a signal transmitted in a structure by a transmitting device according to an embodiment of the present technology in FIG. FIG. 19 is a plot of frequency versus signal power of the frequency-divided OFDM symbols used to transmit the second signaling and payload data by the exemplary receiver shown in FIG. 20 for the case γ=7. shows. The receiving device shown in FIG. 20 corresponds to the example shown in FIG. 16, so only the differences between FIG. 16 and FIG. 19 will be described. It will be appreciated that an exemplary narrowband receiver may also be implemented by making corresponding changes to the example shown in FIG. 17.

In the example of the narrowband receiving device shown in FIG. 20, the radio frequency detection section/tuner 52 and the receiving section only receive signals within the narrowband frequency Seg3 of FIG. 19, so the received signal can be sampled at a lower rate. can. Therefore, the input sampling rate of the receiving device can be reduced by a factor γ. Similarly, with respect to the examples shown in FIGS. 16 and 17, the following adjustments are made to the exemplary receiving apparatus shown in FIG.
The delay section 1601 at the input is reduced to N _u /γ.
Correspondingly, the sizes of FFT sections 1602 and 1604 are reduced by N _u /γ.

Since the signal is sampled at a lower rate than the full band radio frequency transmission bandwidth signal, the length of each CAB region of the time domain symbol is reduced by /γ. Correspondingly, the lengths of all delays and moving average filters in FIG. 14 will also be reduced by a factor γ. The scaling unit 1622 also divides (or multiplies) the section of the PN sequence by P _n *P _n-1 using samples from the received narrowband signal generated as an intermediate result at the output of the multiplier 1608. It is composed of

In detecting the relative cyclic shift, all relevant subcarriers as described above are processed using either the scheme shown in FIG. 16 or FIG. 17. Before performing the final IFFT, the segment of the related subcarrier obtained by dividing by P _n *P _n-1 (or multiplying by - since both are positive and negative) from the scaling unit 1622 is sent to the IFFT unit 1612. provided, each subcarrier is in the correct position and all other subcarriers are set to zero. That is, upsampling section 2001 is configured to add zero samples to the frequency domain samples provided at the output of division section 1610. The IFFT size applied by IFFT section 1612 is then applied as if a full-band receiver was being used. That output then provides a phase gradient in a manner corresponding to the case of FIGS. 16 and 17. The peak height of the output of IFFT section 1612 is affected by the absolute number of subcarriers in the processing segment. This means that if the FFT size of the first signaling OFDM symbol is small, the peak will be significantly smaller, so that block errors are more likely to occur than if the FFT size is large.

Thus, according to embodiments of the present technology, the radio frequency demodulation circuit of the receiving device is configured to The device is configured to detect and recover wireless signals within a corresponding bandwidth. The inverse Fourier transform is configured to transform the intermediate samples produced by multiplying the frequency domain samples of the current first signaling OFDM symbol by the conjugate of the previous frequency synchronized OFDM symbol (where each sample corresponds to a complex sample of each detected subcarrier of a segment of an OFDM symbol). The intermediate samples are transformed to the time domain and represent the result of the current symbol of the one or more first OFDM symbols, but are upsampled according to a bandwidth corresponding to the radio frequency transmission bandwidth. Thereby, the cyclic shift detection unit can detect the cyclic shift of the signature sequence from the time domain intermediate samples generated for the intermediate samples whose bandwidth is increased to the radio frequency transmission bandwidth.

Thus, according to one example, the upscaling unit 2001 is configured to receive intermediate samples in the frequency domain and append zero samples to the intermediate samples. The intermediate samples correspond to the frequency domain equivalent of a radio frequency transmission bandwidth.

As can be understood from the above description, embodiments of the present technology may provide an arrangement that enables both time division multiplexing and frequency division multiplexing of services within the same radio frequency channel. can. This is achieved according to embodiments of the present technology by employing the proposed frame structure shown in FIG. This allows the capacity of mobile services to be increased.

The following numbered paragraphs define further exemplary aspects and features of the present technology.
paragraph 1
A transmitting device that transmits payload data using orthogonal frequency division multiplexed OFDM symbols, the transmitting device comprising:
a frame builder configured to receive the payload data transmitted from a plurality of different channels and frame the payload data received from each of the channels into a plurality of payload data frames for transmission for a plurality of time frames;
Generate a frame synchronization OFDM symbol, one or more first signaling OFDM symbols, and one or more second signaling OFDM symbols for each of the plurality of payload data frames, and generate the payload data received from each of the channels. a modulator configured to modulate one or more payload OFDM symbols by;
comprising a transmitter that transmits the plurality of payload data frames as a plurality of transmission frames,
Each of the plurality of transmission frames includes one or more payload OFDM symbols, and a frame synchronization OFDM symbol for the one or more payload OFDM symbols, followed by the one or more first signaling. preceded by an OFDM symbol followed by said one or more second signaling OFDM symbols;
The frame synchronization OFDM symbol and the one or more first signaling OFDM symbols are transmitted with a bandwidth equal to a radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more A plurality of payload OFDM symbols are transmitted in the radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more payload OFDM symbols are each frequency-divided into a plurality of frequencies. the plurality of frequency segments each transmit payload data from a different channel, and the one or more second signaling OFDM symbols in each frequency segment transmitting one instance of a plurality of instances of physical layer signaling for channel-by-channel detection and recovery of the payload data transmitted by the plurality of frequency segments from symbols; A signaling OFDM symbol transmits first signaling data for detecting the second signaling OFDM symbol. A transmitting device.
paragraph 2
The transmitting device according to paragraph 1, further comprising:
modulating the frame-synchronized OFDM symbols with a signature sequence to generate one or more first signaling OFDM symbols in the time domain that are cyclically shifted with respect to the one or more first signaling OFDM symbols and preceding symbols; a signature sequence combination unit configured to modulate;
A cyclic shift of the one or more first signaling OFDM symbols in the time domain represents the first signaling data transmitted in the one or more first signaling OFDM symbols.
paragraph 3
The transmitting device according to paragraph 1 or 2,
The first signaling data includes an indication of the number of frequency segments. The transmitting device.
paragraph 4
The transmitting device according to any one of paragraphs 1, 2, or 3,
The first signaling data includes an indication of an emergency situation. The transmitting device.
Paragraph 5
The transmitting device according to any one of paragraphs 1, 2, 3, or 4,
The first signaling data includes an indication of a Fourier transform size and a guard interval used for the one or more second signaling OFDM symbols and the one or more payload OFDM symbols.
paragraph 6
The transmitting device according to any one of paragraphs 1 to 5,
The modulation unit combined with the transmitter includes a first part C comprising a plurality of samples of the useful part of the frame-synchronous OFDM symbol, and a part A comprising the useful part of the frame-synchronous OFDM symbol. 1, configured to form the frame-synchronized OFDM symbol according to a time-domain structure of
Part B of the first part is copied to form a postamble of the frame synchronized OFDM symbol.
paragraph 7
The transmitting device according to any one of paragraphs 1 to 6,
The modulation unit combined with the transmitter includes a first portion B consisting of a plurality of samples of the effective portion of the first signaling OFDM symbol, and a portion A including the effective portion of the first signaling OFDM symbol. and a portion C comprising a valid portion of the first signaling OFDM symbol, the one or more first signaling OFDM symbols are configured to form the one or more first signaling OFDM symbols;
The part A is copied to form a second part of the first signaling OFDM symbol.
paragraph 8
The transmitting device according to paragraph 1,
The signature sequence includes a combination of a Zadoff-chu sequence and a pseudorandom noise sequence.
paragraph 9
A transmission method for transmitting payload data using orthogonal frequency division multiplexed OFDM symbols, the method comprising:
receiving the above payload data transmitted from multiple different channels;
Framing the payload data received from each of the above channels for multiple time frames into multiple transmission payload data frames,
generating a frame synchronization OFDM symbol, one or more first signaling OFDM symbols, and one or more second signaling OFDM symbols for each of the plurality of payload data frames;
modulating one or more payload OFDM symbols with the payload data received from each of the channels;
transmitting the above multiple payload data frames as multiple transmission frames,
Each of the plurality of transmission frames includes one or more payload OFDM symbols, and a frame synchronization OFDM symbol for the one or more payload OFDM symbols, followed by the one or more first signaling. preceded by an OFDM symbol followed by said one or more second signaling OFDM symbols;
The frame synchronization OFDM symbol and the one or more first signaling OFDM symbols are transmitted with a bandwidth equal to a radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more A plurality of payload OFDM symbols are transmitted in the radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more payload OFDM symbols are each frequency-divided into a plurality of frequencies. the plurality of frequency segments each transmit payload data from a different channel, and the one or more second signaling OFDM symbols in each frequency segment transmitting one instance of a plurality of instances of physical layer signaling for channel-by-channel detection and recovery of the payload data transmitted by the plurality of frequency segments from symbols; A signaling OFDM symbol transmits first signaling data for detecting the second signaling OFDM symbol. A transmission method.
paragraph 10
The transmission method described in paragraph 9, further comprising:
modulating the frame-synchronized OFDM symbol with a signature sequence;
modulating one or more first signaling OFDM symbols in the time domain that are cyclically shifted with respect to the one or more first signaling OFDM symbols and preceding symbols;
A cyclic shift of the one or more first signaling OFDM symbols in the time domain represents the first signaling data transmitted in the one or more first signaling OFDM symbols.
paragraph 11
The transmission method according to paragraph 9 or 10,
The first signaling data includes an indication of the number of frequency segments.
paragraph 12
The transmission method according to any one of paragraphs 9, 10, or 11,
The first signaling data includes an indication of an emergency situation. Transmission method.
paragraph 13
The transmission method according to any one of paragraphs 9, 10, 11, or 12,
The first signaling data includes an indication of a Fourier transform size and a guard interval to be used for the one or more second signaling OFDM symbols and the one or more payload OFDM symbols.
paragraph 14
The transmission method according to any one of paragraphs 9 to 13, further comprising:
Said frame-synchronized OFDM symbol according to a first time-domain structure comprising a first portion C consisting of a plurality of samples of said useful portion of said frame-synchronized OFDM symbol, and a portion A comprising said useful portion of said frame-synchronized OFDM symbol. form,
Part B of said first part is copied to form a postamble of said frame synchronized OFDM symbol.
paragraph 15
The transmission method according to any one of paragraphs 9 to 14, further comprising:
a first part B consisting of a plurality of samples of the effective part of the first signaling OFDM symbol; a part A including the effective part of the first signaling OFDM symbol; and an effective part of the first signaling OFDM symbol. forming the one or more first signaling OFDM symbols,
Said part A is copied to form a second part of said first signaling OFDM symbol. A transmission method.
paragraph 16
The transmission method described in paragraph 9,
The signature sequence includes a combination of a Zadoff-chu sequence and a pseudo-random noise sequence. Transmission method.
paragraph 17
A receiving device for detecting and restoring payload data from a received signal, the receiving device comprising:
configured to detect and recover the received signal formed and transmitted by a transmitter that transmits the payload as orthogonal frequency division multiplexed (OFDM) symbols from a plurality of different channels in one or more of a plurality of transmit frames; The plurality of transmission frames each include a frame synchronization OFDM symbol, followed by one or more first signaling OFDM symbols, and one or more second OFDM symbols. and one or more payload OFDM symbols following it, the one or more payload OFDM symbols transmitting payload data for each of the plurality of different channels from one time frame of the plurality of time frames. and the frame synchronization OFDM symbols and the one or more first signaling OFDM symbols are transmitted with a bandwidth equal to a radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more first signaling OFDM symbols are transmitted with a bandwidth equal to a radio frequency transmission bandwidth. one or more payload OFDM symbols are transmitted in the radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more payload OFDM symbols are each frequency-divided into multiple frequency segments, each of the plurality of frequency segments transmitting payload data from a different channel and the payload data transmitted by the plurality of frequency segments from a corresponding segment of the one or more payload OFDM symbols to a channel. providing one instance of a plurality of instances of physical layer signaling for detection and recovery of the one or more first signaling OFDM symbols for detecting the second signaling OFDM symbol; a radio frequency demodulation circuit for transmitting first signaling data;
a detection circuit configured to detect, from the frequency synchronized OFDM symbol, a synchronization timing for converting the time length of the effective portion of the one or more first signaling OFDM symbols of the payload OFDM symbol into the frequency domain;
a forward Fourier transform circuit configured to transform the time length of the one or more first signaling OFDM symbols or the payload OFDM symbol from the time domain to the frequency domain according to the identified synchronization timing; ,
recovering said first signaling data from said first signaling OFDM symbol; and using said first signaling data, said one or more second signaling OFDM symbols from one of said frequency segments. a demodulator configured to detect and recover the physical layer signaling data and recover the payload data from one of the frequency segments of the one or more payload OFDM symbols for each time frame; A receiving device comprising a circuit.
Various further aspects and features of the technology are defined in the appended claims and variously combine the features of the dependent claims with the features of the independent claims other than in the specific combinations recited for dependence of the claims. Can be combined. Modifications may be made to the embodiments described above without departing from the scope of the present technology. For example, processing elements of embodiments may be implemented in hardware, software, and digital or analog circuitry. Furthermore, although certain features are described in connection with particular embodiments, those skilled in the art will appreciate that various features of the embodiments described above may be combined in accordance with the present technology.
[1] ATSC Standard: A/321, System Discovery and Signaling (ATSC Standard: A/321, System Discovery and Signaling Doc. A/321:2016): March 23, 2016 [2] ATSC Candidate Standard: System Discovery ATSC Candidate Standard: System Discovery and Signaling (Doc. A/321 Part 1), Advanced Television Systems Committee, July 15, 2015.

Claims (17)

A transmitting device that transmits payload data using orthogonal frequency division multiplexed OFDM symbols, the transmitting device comprising:
a frame builder configured to receive the payload data transmitted from a plurality of different channels and frame the payload data received from each channel into a plurality of payload data frames for transmission for a plurality of time frames;
generating a frame synchronized OFDM symbol, one or more first signaling OFDM symbols, and one or more second signaling OFDM symbols for each of the plurality of payload data frames, and generating the payload data received from each of the channels. a modulator configured to modulate one or more payload OFDM symbols by;
comprising a transmitter that transmits the plurality of payload data frames as a plurality of transmission frames,
Each of the plurality of transmission frames includes one or more payload OFDM symbols, and a frame-aligned OFDM symbol for the one or more payload OFDM symbols, followed by the one or more first signaling. preceded by an OFDM symbol followed by the one or more second signaling OFDM symbols;
The frame synchronization OFDM symbol and the one or more first signaling OFDM symbols are transmitted with a bandwidth equal to a radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more A plurality of payload OFDM symbols are transmitted in the radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more payload OFDM symbols are each frequency-divided into a plurality of frequencies. the plurality of frequency segments each transmit payload data from a different channel, and the one or more second signaling OFDM symbols in each frequency segment transmitting one instance of a plurality of instances of physical layer signaling for channel-by-channel detection and recovery of the payload data transmitted by the plurality of frequency segments from symbols; A signaling OFDM symbol transmits first signaling data for detecting the second signaling OFDM symbol. A transmitting device. The transmitting device according to claim 1, further comprising:
modulating the frame synchronized OFDM symbols with a signature sequence to generate one or more first signaling OFDM symbols in the time domain that are cyclically shifted with respect to the one or more first signaling OFDM symbols and preceding symbols; a signature sequence combination unit configured to modulate;
A cyclic shift of the one or more first signaling OFDM symbols in the time domain represents the first signaling data transmitted in the one or more first signaling OFDM symbols. The transmitting device according to claim 1 or 2,
The first signaling data includes an indication of the number of frequency segments.
The transmitting device according to claim 1, 2, or 3,
The first signaling data includes an indication of an emergency situation. Transmitting device. The transmitting device according to claim 1, 2, 3, or 4,
The first signaling data includes an indication of a Fourier transform size and a guard interval used for the one or more second signaling OFDM symbols and the one or more payload OFDM symbols. The transmitting device according to any one of claims 1 to 5,
The modulation unit combined with the transmitter includes a first part C consisting of a plurality of samples of the useful part of the frame-synchronous OFDM symbol, and a part A including the useful part of the frame-synchronous OFDM symbol. 1, configured to form the frame-synchronized OFDM symbol according to a time-domain structure of
Part B of the first part is copied to form a postamble of the frame-synchronized OFDM symbol. The transmitting device according to any one of claims 1 to 6,
The modulation unit combined with the transmitter comprises a first part B consisting of a plurality of samples of the useful part of the first signaling OFDM symbol, and a part A including the useful part of the first signaling OFDM symbol. and a portion C comprising a valid portion of the first signaling OFDM symbol, the one or more first signaling OFDM symbols are configured to form the one or more first signaling OFDM symbols;
The part A is copied to form a second part of the first signaling OFDM symbol. The transmitting device according to claim 1,
The signature sequence includes a combination of a Zadoff-chu sequence and a pseudorandom noise sequence. A transmission method for transmitting payload data using orthogonal frequency division multiplexed OFDM symbols, the method comprising:
receiving the payload data transmitted from a plurality of different channels;
framing payload data received from each channel for a plurality of time frames into a plurality of transmission payload data frames;
generating a frame synchronization OFDM symbol, one or more first signaling OFDM symbols, and one or more second signaling OFDM symbols for each of the plurality of payload data frames;
modulating one or more payload OFDM symbols with payload data received from each channel;
transmitting the plurality of payload data frames as a plurality of transmission frames;
Each of the plurality of transmission frames includes one or more payload OFDM symbols, and a frame-aligned OFDM symbol for the one or more payload OFDM symbols, followed by the one or more first signaling. preceded by an OFDM symbol followed by the one or more second signaling OFDM symbols;
The frame synchronization OFDM symbol and the one or more first signaling OFDM symbols are transmitted with a bandwidth equal to a radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more A plurality of payload OFDM symbols are transmitted in the radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more payload OFDM symbols are each frequency-divided into a plurality of frequencies. the plurality of frequency segments each transmit payload data from a different channel, and the one or more second signaling OFDM symbols in each frequency segment transmitting one instance of a plurality of instances of physical layer signaling for channel-by-channel detection and recovery of the payload data transmitted by the plurality of frequency segments from symbols; A signaling OFDM symbol transmits first signaling data for detecting the second signaling OFDM symbol. A transmission method. 10. The transmission method according to claim 9, further comprising:
modulating the frame-synchronized OFDM symbol with a signature sequence;
modulating one or more first signaling OFDM symbols in the time domain that is cyclically shifted with respect to the one or more first signaling OFDM symbols and preceding symbols;
A cyclic shift of the one or more first signaling OFDM symbols in the time domain represents the first signaling data transmitted in the one or more first signaling OFDM symbols. The transmission method according to claim 9 or 10,
The first signaling data includes an indication of the number of frequency segments. The transmission method according to claim 9, 10, or 11,
The first signaling data includes an indication of an emergency situation. Transmission method. The transmission method according to claim 9, 10, 11, or 12,
The first signaling data includes an indication of a Fourier transform size and a guard interval to be used for the one or more second signaling OFDM symbols and the one or more payload OFDM symbols. The transmission method according to any one of claims 9 to 13, further comprising:
the frame-synchronized OFDM symbol according to a first time-domain structure comprising a first portion C consisting of a plurality of samples of the useful portion of the frame-synchronized OFDM symbol; and a portion A comprising the useful portion of the frame-synchronized OFDM symbol; form,
Part B of the first part is copied to form a postamble of the frame-synchronized OFDM symbol. The transmission method according to any one of claims 9 to 14, further comprising:
a first part B consisting of a plurality of samples of the useful part of the first signaling OFDM symbol; a part A including the useful part of the first signaling OFDM symbol; and a part A including the useful part of the first signaling OFDM symbol; forming the one or more first signaling OFDM symbols by a portion C comprising:
The part A is copied to form a second part of the first signaling OFDM symbol. The transmission method according to claim 9,
The signature sequence includes a combination of a Zadoff-chu sequence and a pseudorandom noise sequence. A transmission method. A receiving device for detecting and restoring payload data from a received signal, the receiving device comprising:
configured to detect and recover the received signal formed and transmitted by a transmitter that transmits the payload as orthogonal frequency division multiplexed (OFDM) symbols from a plurality of different channels in one or more of a plurality of transmit frames; a radio frequency demodulation circuit, wherein each of the plurality of transmission frames includes a frame synchronization OFDM symbol followed by one or more first signaling OFDM symbols and one or more second OFDM symbols. and one or more payload OFDM symbols following it, the one or more payload OFDM symbols transmitting payload data for each of the plurality of different channels from one time frame of the plurality of time frames. and the frame synchronization OFDM symbol and the one or more first signaling OFDM symbols are transmitted with a bandwidth equal to a radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one one or more payload OFDM symbols are transmitted in the radio frequency transmission bandwidth, and the one or more second signaling OFDM symbols and the one or more payload OFDM symbols are each frequency-divided into multiple the plurality of frequency segments, each of which provides payload data from a different channel and the payload data transmitted by the plurality of frequency segments from a corresponding segment of the one or more payload OFDM symbols. providing one instance of a plurality of instances of physical layer signaling for detection and recovery of the one or more first signaling OFDM symbols for detecting the second signaling OFDM symbol; a radio frequency demodulation circuit for transmitting first signaling data;
a detection circuit configured to detect, from the frequency synchronized OFDM symbol, a synchronization timing that converts the time length of the effective portion of the one or more first signaling OFDM symbols of the payload OFDM symbol into the frequency domain;
a forward Fourier transform circuit configured to transform the time length of the one or more first signaling OFDM symbols or the payload OFDM symbol from the time domain to the frequency domain according to the identified synchronization timing; ,
recovering the first signaling data from the first signaling OFDM symbol and using the first signaling data to generate one segment of the frequency segments of the one or more second signaling OFDM symbols; and configured to detect and recover the physical layer signaling data from one segment of the frequency segments of the one or more payload OFDM symbols for each time frame. A receiving device comprising a demodulation circuit.