JP2002084253A - Ofdm transmitting device and ofdm receiving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a delay time of information transmitted through transmission channels without the need for a delay device for adjusting the delay time. SOLUTION: In a relay system adopting this invention, video signals of each television broadcast photographed by relay points are transmitted to a base station by ground wave signals. In this case, each transmitting device uses OFDM modulation and variably sets a delay amount of time interleaving according to a delay time of each transmission channel. Thus, shift in a transmission delay of signals sent from each relay point can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to orthogonal frequency division multiplexing transmission (OFDM).
The present invention relates to an OFDM transmitting apparatus and an OFDM receiving apparatus applied to digital broadcasting and a broadcast relay apparatus using a multiplexing (modulation) method.

[0002]

2. Description of the Related Art Conventionally, in the relay broadcasting of television such as news programs, sports programs, and various event programs, materials (video, audio, data, etc.) photographed at a plurality of relay points (or a plurality of television cameras). ) Are switched or combined in real time to generate a broadcast signal and provide it to the user.

[0003] In the case of such a relay broadcast, a material photographed at a certain relay point is transmitted from the relay point to a base station using a ground line, for example. Further, for example, a material shot at a certain relay point is sent from the relay point to a base station via a satellite line. Further, for example, the material at a certain relay point is sent from the relay point to a relay vehicle using a ground line, and further transmitted from the relay vehicle to a base station via a satellite line. When relay broadcasting is performed in this way, the transmission path through which the material is transmitted from the relay point to the base station differs for each relay point. Also,
For example, even if the material is sent from all the relay points to the base station using the terrestrial line, the transmission distance is different and the route is different. Will be different.

[0004] If the transmission paths from each relay point to the base station are different as described above, the delay time of each transmission path will be different. Therefore, when the base station switches or combines materials from each relay point, if no processing is performed, time continuity between relay points is lost. In order to ensure time continuity between such relay points, in a conventional television relay system, generally, a delay device is provided in a stage preceding a material selection device, and all of the delay devices are arranged in accordance with the delay time of the most delayed material. Adjustment was made by delaying the material.

A conventional television relay system in which a delay time is adjusted by such a delay device to select a material will be described with reference to FIG.

A conventional television relay system 100
6, a relay device 111A that performs shooting at a relay point A and a relay device 111 that performs shooting at a relay point B, as shown in FIG.
B. Further, the conventional television relay system 100 includes the relay devices 111A and 111A.
A base station that receives transmission signals from B, restores materials (video, audio, data) from those transmission signals, and switches or combines the restored materials to generate broadcast signals to be provided to users. 112.

The transmission path of the transmission signal transmitted from each of the repeaters 111A and 111B to the base station 112 may use any transmission line. For example, the relay point A uses a satellite link, and the relay point B uses a terrestrial link.

[0008] Each of the relay devices 111A, 111B is a television camera 121 (121A, 121B).
And the microphone 122 (122A, 122B)
It comprises an information source coding device 123 (123A, 123B), a transmitting device 124 (124A, 124B), and a transmitting antenna 125 (125A, 125B).

The television camera 121 captures an image at each relay point and converts it into a video signal. The video signal captured by the television camera 121 is supplied to the information source coding device 123.

[0010] The microphone 122 collects sound at each relay point and converts the sound into a sound signal. The audio signal collected by the microphone 122 is supplied to the information source encoding device 123.

[0011] The source coding apparatus 123 is, for example, an MP.
It is a video / audio / data compression / multiplexing device such as an EG2 encoder. The information source encoding device 123 receives the video signal supplied from the television camera 121, the audio signal collected by the microphone 122, and a predetermined data signal, and compresses and encodes them according to, for example, the MPEG2 system. Then, these compressed data are multiplexed to generate multiplexed data such as a transport stream defined in MPEG2 Systems, for example. The multiplexed data generated by the information source coding device 123 is supplied to the transmitting device 124.

The transmitting device 124 applies, for example, OFDM (Orthogonal Frequency D) to the input multiplexed data.
Transmission line modulation is performed by an ivision multiplexing method.
Then, the transmitting apparatus 124 up-converts the OFDM signal generated by the OFDM modulation to a frequency corresponding to the channel of the line used in each relay apparatus,
It radiates into the air by the transmitting antenna 125.

On the other hand, base station 112 includes receiving antenna 126 (126A, 126B) and receiving device 127 (127A, 127B) corresponding to each transmission line, information source decoding device 128 (128A, 128B), and delay device 129.
And a selection device 130. The base station 112 is provided with at least the same number of receiving antennas 126, receiving devices 127, and information source decoding devices 128 as the number of relay devices (two in this example).

The receiving device 127 is tuned to a channel corresponding to the transmission line and receives a signal. For example, the receiving device 127A receives the transmission signal transmitted from the relay device 111A via a satellite line, and
B receives the transmission signal transmitted from the relay device 111B via the ground line. Each receiving apparatus 127 also demodulates the multiplexed data from the received signal by, for example, demodulating a transmission path by an OFDM method. The demodulated multiplexed data is supplied to each information source decoding device 128.

The information source decoding device 128 includes, for example, an MPE
It is a video, audio, and data decoding device such as a G decoder.
The information source decoding device 128 decodes the multiplexed data and outputs a video signal, an audio signal, and data of the material. For example, the information source decoding device 128A restores the material (video, audio, data) photographed at the relay point A, and the information source decoding device 128B restores the material (video, audio,
Voice, data).

Here, the delay time of the transmission line at the relay point A,
That is, after capturing the material in television cameras 121A, the original material in the information source decoding apparatus 128A is the time to be restored, and T _1. Further, the delay time of the transmission path at the relay point B, that is, the television camera 121B
Let T ₂ be the time from when the material is photographed in the above to when the original material is restored by the information source decoding device 128B. And
It is assumed that these delay times have a relationship of T ₁ > T ₂ . In this case, the conventional television relay system 1
In 00, a delay device 129 is provided at a stage subsequent to the information source decoding device 128B.

In the delay device 129, the information source decoding device 12
Material (video, audio, data) restored by 8B
Is delayed by ΔT (= T ₂ −T ₁ ) time. Thus, the delay device 129 removes the time error between the material transmitted from the relay point A and the material transmitted from the relay point B by delaying the material transmitted from the relay point B. Can be.

The selection device 130 includes an information source decoding device 128
A, the restored material output from A and the restored material delayed by the delay device 129 are input, and either one of them is selected and output, or these are combined and output. Generate a broadcast signal to be provided to the user.

[0019]

By the way, in such a conventional television relay system 100, the difference in the transmission delay time at each relay point is adjusted by using the delay device 129. Was getting bigger.

The present invention has been made in view of such circumstances, and adjusts the delay time of information transmitted through a plurality of transmission paths without using such a delay adjustment delay device. An object of the present invention is to provide an OFDM transmitting apparatus and an OFDM receiving apparatus that can perform the operations.

[0021]

To solve the above-mentioned problems, an OFDM transmitting apparatus according to the present invention converts an input digital data sequence into a data structure in OFDM symbol units composed of a predetermined number of modulation symbols. Data interleaving means for interpolating the input digital data sequence for each modulation symbol with a time delay amount of an OFDM symbol unit, and the time interleaving means according to a transmission delay time of a transmission signal. Delay time control means for adjusting the amount of time delay by the means in OFDM symbol time units, and OFDM for generating OFDM signals by OFDM modulating transmission data time-interleaved by time interleaving means in OFDM symbol units.
Modulating means and the ODM generated by the OFDM modulating means.
Transmitting means for transmitting the FDM signal.

In this OFDM transmission apparatus, the amount of time delay caused by the time interleaving means is determined according to the transmission delay time.
Control is performed in OFDM symbol units.

Further, an OFDM receiving apparatus according to the present invention includes a receiving means for receiving an OFDM signal, a demodulation of the OFDM signal received by the receiving means, and a transmission in an OFDM symbol unit composed of a predetermined number of modulation symbols. OFDM demodulating means for generating data, and transmitting data demodulated by the OFDM demodulating means,
Time deinterleaving means for performing time deinterleaving with a time delay amount in FDM symbol units, and delay time control means for adjusting the time delay amount by the time deinterleaving means in OFDM symbol units according to the propagation delay time of a received signal And characterized in that:

In this OFDM receiving apparatus, the amount of time delay caused by the time interleaving means is determined according to the transmission delay time.
Control is performed in OFDM symbol units.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as a preferred embodiment of the present invention, a television relay system for transmitting television broadcast materials (video, audio, data, etc.) obtained at a plurality of relay points to a base station will be described. do. Here, an example is shown in which broadcast materials obtained from three points (points A, B, and C) as relay points are transmitted to one base station.

FIG. 1 shows a configuration diagram of a television relay system according to an embodiment of the present invention.

As shown in FIG. 1, the television relay system 1 includes a first relay device 11 for taking a picture at a relay point A.
, A second relay device 12 that performs imaging at the relay point B, and a third relay device 13 that performs imaging at the relay point C. In addition, the television relay system 1
Receives transmission signals from each of the relay devices 11, 12, and 13 and extracts materials (video, audio, data) from those transmission signals.
And a base station 14 for generating a broadcast signal to be provided to the user by switching or combining the restored materials.

The base station 1 is transmitted from each of the repeaters 11, 12, and 13.
Any transmission line may be used for the transmission path of the transmission signal transmitted to the transmission line 4. For example, the relay point A uses a satellite link, the relay point B uses a terrestrial link,
At the relay point C, a terrestrial line via a relay antenna is used.

Each of the relay devices 11, 12, 13 is provided with a television camera 21 (21A, 21B, 21).
C) and the microphone 22 (22A, 22B, 22
C) and the information source coding device 23 (23A, 23B, 23
C), the transmitting device 24 (24A, 24B, 24C),
The transmission antenna 25 (25A, 25B, 25C) is provided.

The television camera 21 captures a video at each relay point and converts it into a video signal. The video signal captured by the television camera 21 is supplied to the information source coding device 23.

The microphone 22 collects sound at each relay point and converts the sound into a sound signal. The audio signal collected by the microphone 22 is supplied to the information source encoding device 23.

The information source coding device 23 is, for example, an MPE
It is a video / audio / data compression / multiplexing device such as a G2 encoder. The information source encoding device 23 receives the video signal supplied from the television camera 21, the audio signal collected by the microphone 22, and a predetermined data signal, and compresses and encodes them according to, for example, the MPEG2 system. Then, these compressed data are multiplexed to generate multiplexed data such as a transport stream defined in MPEG2 Systems, for example. The multiplexed data generated by the information source coding device 23 is supplied to the transmission device 24.

The transmitting device 24 applies OFDM (Orthogonal Frequency Division) to the input multiplexed data.
Multiplexing) performs transmission path modulation. The transmitting device 24 generates an OFDM signal generated by OFDM modulation.
The signal is up-converted to a frequency corresponding to the channel of the line used by each of the relay devices 11, 12, and 13 and radiated into the air by the transmission antenna 25.

On the other hand, the base station 14 includes a receiving antenna 26 (26A, 26B, 26C) and a receiving device 27 (27A, 27B, 27C) corresponding to each transmission line, and an information source decoding device 28 (28A, 28B, 28C). ) And the selection device 29
And is provided. The base station 14 is provided with at least the same number of receiving antennas 26, receiving devices 27, and information source decoding devices 28 as the number of relay devices.

The receiving device 27 is tuned to a channel corresponding to the transmission line, and receives a signal via each receiving antenna 26. For example, the reception device 27A receives a transmission signal transmitted from the first relay device 11 via a satellite line, and the reception device 27B receives a transmission signal transmitted from the second relay device 12 via a terrestrial line. Receiving, the receiving device 27C receives the transmission signal transmitted from the third relay device 13 via the relay antenna. Further, each receiving device 27 performs transmission path demodulation by the OFDM method from the received signal and demodulates multiplexed data. The demodulated multiplexed data is supplied to each information source decoding device 28.

The information source decoding device 28 is, for example, an MPEG
It is a video, audio and data decoding device such as a decoder. The information source decoding device 28 decodes the multiplexed data and outputs a material video signal, audio signal, and data. For example,
The information source decoding device 28A restores the material (video, audio, data) captured at the relay point A, and
B restores the material (video, audio, data) captured at the relay point B, and the information source decoding device 28C recovers the material (video, audio, data) captured at the relay point C.

The selection device 29 includes each information source decoding device 28
Is input. The selection device 29
Each material is appropriately switched and output as necessary, or synthesized to generate a video signal to be broadcast to the user.

Next, the transmitting device 24 in each relay device will be described in more detail with reference to FIG.

As described above, the transmitting device 24 uses the MPEG
OFDM for multiplexed data such as transport streams
This is a device that modulates by a modulation method and transmits the material to the base station 14.

[0040] As shown in FIG.
Transmission path encoding section 31 and OFDM frame creation section 32
, A time interleave unit 33 and a delay time control unit 34
, A frequency interleaving section 35 and an OFDM modulating section 36
And a front end 37.

The transmission path encoding unit 31 performs an energy spreading process and an RS
An encoding process, a convolutional interleaving process, an inner coding process, a bit interleaving process, a symbol interleaving process, and a mapping process according to a modulation scheme are performed.
Then, the transmission path coding unit 34 performs a modulation symbol unit (I, Q
Output the transmission data of each data set.

The OFDM frame creation section 32 forms the transmission data in modulation symbol units output from the transmission path encoding section 31 into an OFDM symbol and an OFDM frame.

When the OFDM modulation method is adopted, a data structure called an OFDM symbol is generally formed in a predetermined number of modulation symbol units (one set of I and Q data).
The OFDM symbol is a data unit for performing the IFFT operation collectively, and each I and Q data in the OFDM symbol is allocated to each subcarrier (subcarrier). Also, OFDM symbols are given in units of a predetermined number of OFDM symbols.
A frame structure for transmission called a DM frame is formed. This OFDM frame is, for example, TPS or TM
It is a unit for inserting transmission control information such as CC, and is also a unit for switching modulation schemes.

For example, ISDB-T (Integrated Services Digit), which is one of digital terrestrial broadcasting systems, is used.
al Broadcasting-Terrestrial) standard (in the case of mode 1) has a frame configuration in which the number of modulation symbols (I, Q data) transmitted in one OFDM symbol is
108 (carrier numbers # 0 to # 107). In addition, 204 OFDM symbols (symbol numbers # 0 to # 0)
# 203) constitutes one OFDM frame.

The OFDM frame creation section 32 converts the input transmission data into such an OFDM symbol and
The frame configuration is performed by dividing the frame into FDM frames. The frame-structured transmission data is supplied to the time interleave unit 33.

The time interleave unit 33 performs time interleave processing on the input transmission data.
At this time, the time interleaving section 33 sets the interleaving depth so that the delay time of each time-interleaved modulation symbol is an integral multiple of the OFDM symbol.

For example, when time interleaving is performed using convolutional interleaving, as shown in FIG. 3, a plurality of branches (0 to (n-1)) provided with delay elements having different delay amounts are provided. This is performed by the interleaving circuit. Here, n corresponds to the number of modulation symbols constituting one OFDM symbol. In this interleaving circuit, branches are switched in synchronization with a symbol clock of a modulation symbol. In addition, the same branch is selected for both input and output, for example, 0,
1, 2, 3, 4,... N-2, n-1, 0, 1, 2
... The branches are sequentially switched as described above.
Then, for one modulation symbol (one I, Q data) input, one modulation symbol (one I, Q data) is output. By performing such processing, convolutional interleaving is realized.

Here, the delay amount m of the delay element of each branch
_i is represented by m _i = P ₀ × {(i × P ₁ ) mod P ₂ }.

I is a branch number of each branch, and 0,
1, 2, 3, 4,... N-2, n-1.

P ₀ is a parameter indicating the interleave depth, and its value is a positive integer.

P ₁ is the number of interleaving steps of each modulation symbol, and is expressed as a multiple of the number of modulation symbols constituting one OFDM symbol.

P ₀ is a value for determining the maximum delay time of the modulation, and is represented by a multiple of the number of modulation symbols constituting one OFDM symbol.

For example, P ₀ = 1, P ₁ = 5 (OFDM symbol),
If P ₂ = 96 (OFDM symbol), the maximum delay time is P ₀ × P ₂ = 96 (OFDM symbol), and each branch has the following delay time. m ₀ = ₀ (OFDM symbol) m ₁ = 5 (OFDM symbol) m ₂ = 10 (OFDM _{symbols) · · · m 19 = 95} (OFDM symbols) m ₂₀ = 4 (OFDM symbol) · · · m ₁₉ = 94 (OFDM symbol) m ₂₀ = 3 (OFDM symbol)

For example, if P ₀ = 2, P ₁ = 5 (OFDM symbol) and P ₂ = 96 (OFDM symbol), P ₀ ×
P ₂ = 192 (OFDM symbol), and each branch has the following delay time. m ₀ = 0 (OFDM symbol) m ₁ = 10 (OFDM symbol) m ₂ = 20 (OFDM symbol) m ₁₉ = 190 (OFDM symbol) m ₂₀ = 8 (OFDM symbol) m ₁₉ = 188 (OFDM symbol) m ₂₀ = 6 (OFDM symbol)

By using such a convolutional interleave circuit, the delay time of each modulation symbol can be reduced by the OFDM
The interleaving depth can be set as an integral multiple of the symbol.

Here, the value of the parameter P ₀ indicating the interleave depth is controlled by the delay time control unit 34. That is, the delay time control unit 34 is a circuit that controls the delay time of each branch in OFDM symbol units.

The transmission data time-interleaved in this way is supplied to a frequency interleaving section 35.

Frequency interleaving section 35 changes the order of subcarriers in the OFDM symbol for the input transmission data, and performs interleaving processing in the frequency direction. The frequency-interleaved transmission data is supplied to an OFDM modulator 36.

The OFDM modulator 36 collectively performs IFF processing on the input transmission data in OFDM symbol units.
Perform T operation. After the IFFT operation, the signal waveform of the latter half of the effective symbol signal obtained by the operation is copied and added to the head of the effective symbol, and a guard interval is added. The data to which the guard interval has been added is supplied to the front end 37.

The front end 37 converts a digital signal into an analog signal, performs frequency up-conversion to an RF band, and radiates it into the air via the transmitting antenna 25.

Next, the receiving device 27 in the base station 14 will be described in more detail with reference to FIG.

The receiving device 27 receives the transmission wave from each relay device and demodulates it by the OFDM method as described above,
This is a device that outputs multiplexed data such as an EG transport stream.

The receiving device 27 includes a front end 41,
OFDM demodulator 42, frequency deinterleave 43,
A time deinterleave 44, a delay time controller 45,
An FDM frame reconstructing unit 46 and a transmission line decoding unit 47 are provided.

The front end 41 is connected to the receiving antenna 26
Performs frequency down-conversion of the received RF signal into an IF signal. The down-converted IF signal is
The signal is supplied to the OFDM demodulation unit 42.

The OFDM demodulation section 42 performs channel selection processing and quadrature demodulation processing on the input IF signal. Further, the OFDM demodulation unit 42 performs an FFT (Fast Fourier) for each effective symbol while performing various synchronization processes such as an FFT window synchronization process and a symbol timing synchronization.
Transform) process to demodulate the transmission data. The transmission data demodulated in this way is supplied to the frequency deinterleaving section 43.

The frequency deinterleaving section 43 rearranges the order of the subcarriers in the OFDM symbol in the inverse procedure to the frequency interleaving performed on the transmission side, with respect to the input transmission data. Perform a restore. The frequency deinterleaved transmission data is supplied to the time deinterleaving section 44.

The time deinterleaving section 44 performs time deinterleaving processing on the input transmission data in a procedure reverse to the time interleaving performed on the transmission side.
Restore transmission data. This time deinterleaving unit 4
4, the delay time of each modulation symbol is
The interleaving depth is set so as to be an integral multiple of the OFDM symbol.

For example, when time deinterleaving is performed using convolutional interleaving, as shown in FIG. 5, a plurality of branches (0 to (n-1)) provided with delay elements having different delay amounts are provided. This is performed by the provided deinterleave circuit. Here, n corresponds to the number of modulation symbols constituting one OFDM symbol. In this deinterleave circuit, branches are switched in synchronization with a symbol clock of a modulation symbol. In addition, the same branch is selected for input and output for the switching, for example,
0, 1, 2, 3, 4, ... n-2, n-1, 0,
The branches are sequentially switched such as 1, 2,.... Then, for one modulation symbol (one I, Q data) input, one modulation symbol (one I, Q data)
Q data) is output. By performing such processing, convolution deinterleaving is realized.

Here, the delay amount k of the delay element of each branch
_i is represented by k _i = (P ₀ × P ₂ ) −P ₀ × {(i × P ₁ ) mod P ₂ }.

The values of P0, P1, and P2 are the same as those set in the transmitting device of the corresponding relay device.

For example, P ₀ = 1, P ₁ = 5 (OFDM symbol),
If P ₂ = 96 (OFDM symbol), each branch has the following delay time. k ₀ = 96 (OFDM symbols) k ₁ = 91 (OFDM symbols) k ₂ = 86 (OFDM _{symbols) · · · k 19 = 1} (OFDM symbol) k ₂₀ = 92 (OFDM symbols) · · · k ₁₉ = 4 (OFDM symbol) k ₂₀ = 93 (OFDM symbol) ....

For example, if P ₀ = 2, P ₁ = 5 (OFDM symbol), and P ₂ = 96 (OFDM symbol), each branch has the following delay time. k ₀ = 192 (OFDM symbol) k ₁ = 182 (OFDM symbol) k ₂ = 172 (OFDM symbol) k ₁₉ = 2 (OFDM symbol) k ₂₀ = 184 (OFDM symbol) k ₁₉ = 4 (OFDM symbol) k ₂₀ = 186 (OFDM symbol).

By using such a convolutional deinterleave circuit, the delay time of each modulation symbol
The depth of deinterleaving can be set as an integral multiple of the DM symbol.

Here, the value of the parameter P ₀ indicating the interleave depth is controlled by the delay time control unit 45. That is, the delay time control unit 45 is a circuit that controls the delay time of each branch in OFDM symbol units.

The controlled delay time is set to the same value as the delay time set in the corresponding relay device.

The transmission data time-deinterleaved in this way is supplied to the frame reconstruction unit 45.

The frame reconstructing unit 45 reconstructs the data frame structure in data processing units to be processed by the transmission path decoding unit 47 at the subsequent stage. The reconstructed transmission data is supplied to the transmission path decoding unit 47.

The transmission path decoding unit 47 performs a demapping process,
Symbol deinterleaving, bit deinterleaving, inner code decoding, convolutional deinterleaving, R
Transmission path decoding processing such as S decoding processing and energy despreading processing is performed, and the transmitted transport stream is restored.

Next, the parameter P ₀ indicating the depth of interleaving and de-interleaving will be described.

The parameter P ₀ is determined, for example, as follows.

For example, when the material is photographed by the television camera 21A of the relay device 11 at the relay point A,
The delay time until the material reaches the selection device 24 of the base station 14 is defined as t _11, and from the time when the material is photographed by the television camera 21B of the relay device 12 at the relay point B,
The delay time until the material reaches the selection device 24 of the base station 14 is t ₁₂ , and when the material is photographed by the television camera 21C of the relay device 13 at the relay point C, the material is selected by the base station 14. the delay time to reach the device 24 and t _13. And t ₁₁ > t ₁₂ > t ₁₃ , t ₁₁ ,
_{t 11 -t 12 = Δt 1,} t 11 and there is a relationship -t ₁₃ = Δ _t2.

At this time, for relay point B, parameter P _{0 is set} so that Δt ₁ is further added to the delay time caused by time interleaving and time de-interleaving.
Set. For the relay point C, the parameter P ₀ is set so that Δt ₂ is further added to the delay time caused by the time interleaving.

Here, the delay time Δt caused by time interleaving is Δt = mi + ki = P ₀ × P ₂ . Note that (mi + ki) is constant.

That is, for relay point B, P ₀ ×
A value that satisfies P ₂ = Δt ₁ is further added to the delay time of time interleaving and deinterleaving so that the transmission delay time matches the relay point A. For the relay point C, a value that satisfies P ₀ × P ₂ = Δt ₂ is further added to the delay time of the time interleaving and the de-interleaving, so that the transmission delay time matches the relay point A.

As described above, by adding the delay time difference from the relay point having the shortest transmission delay to the base station 14 to the delay time caused by time interleaving and deinterleaving, the transmission time of the material from each relay point is the same. Becomes Further, since the time interleave length becomes longer, more stable transmission can be performed.

Note that the transmission delay time from each relay point is
The measurement or prediction is made, and the time interleave length is set based on the value by inputting a delay amount correction value from outside. Further, the depth of the time interleaving may be set to zero.

As described above, in the television relay system 1 according to the embodiment of the present invention, the amount of time delay caused by the time interleave unit and the time deinterleave is calculated in OFDM symbol units according to the transmission delay time of each transmission path. It is variable. Thus, in the television relay system 1, the transmission delay time from each relay point can be matched with a very simple configuration without using a delay device. Also, in this television relay system 1,
Since the amount of time interleaving becomes longer, transmission quality can be improved.

Although the television relay system used for a broadcasting station has been described as an embodiment of the present invention, the present invention is not limited to such a broadcasting system and can be applied. For example, the present invention can be applied not only to security monitoring and broadcasting stations such as home use, and the transmitting side is not limited to a camera device, but may be any device that wirelessly transmits data. You may.

[0089]

In the OFDM transmitting apparatus and receiving apparatus according to the present invention, the amount of time delay by the time interleaving means is controlled in OFDM symbol units according to the transmission delay time. As a result, in the present invention, the delay time of time interleaving is adjusted according to the transmission delay time from each different point, so that the transmission delay from each point is very simple without using a delay device. Time can be matched. Further, according to the present invention, the amount of time interleaving becomes longer, so that transmission quality can be improved.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a television relay system to which the present invention is applied.

FIG. 2 is a block diagram of a transmission device provided in each relay device.

FIG. 3 is a diagram showing a time interleave circuit.

FIG. 4 is a block diagram of each receiving device provided in the base station.

FIG. 5 is a diagram showing a time deinterleaving circuit.

FIG. 6 is a system configuration diagram of a conventional television relay system.

[Explanation of symbols]

1 television relay system, 11, 12, 13 relay device, 14 base stations, 33-hour interleave section,
34 delay time control section, 44 time deinterleave section,
45 Delay time control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/455 H04N 5/455 7/06 7/06 F term (Reference) 5C025 AA03 AA08 AA09 AA11 5C063 AB03 AB06 AB07 AB15 AC01 AC05 AC10 CA11 CA16 CA20 CA34 CA38 5K022 AA03 AA11 AA21 AA31 DD01 DD19 DD21 DD31 5K060 BB07 CC13 DD03 FF06 GG06 HH34 KK08

Claims (2)

[Claims] 1. An OFDM transmission apparatus for transmitting an orthogonal frequency division multiplexing (OFDM) signal, comprising: a data configuration unit configured to configure an input digital data sequence into an OFDM symbol unit data structure including a predetermined number of modulation symbols. And the input digital data sequence is converted into O
Time interleaving means for performing time interleaving with a time delay amount in FDM symbol units; delay time control means for adjusting the time delay amount by the time interleaving means in OFDM symbol time units according to the transmission delay time of a transmission signal; The transmission data time-interleaved by the interleaving means is OFDM-modulated in OFDM symbol units and
An OFDM modulator comprising: an OFDM modulator for generating an FDM signal; and a transmitter for transmitting the OFDM signal generated by the OFDM modulator.
Transmission device. 2. An OFDM receiving apparatus for receiving an orthogonal frequency division multiplexing (OFDM) signal, comprising: receiving means for receiving an OFDM signal; demodulating the OFDM signal received by the receiving means;
OFDM demodulation means for generating transmission data in OFDM symbol units composed of a predetermined number of modulation symbols, and transmission data demodulated by the OFDM demodulation means in a time delay amount in OFDM symbol units for each modulation symbol,
A time deinterleaving means for performing time deinterleaving; and a delay time control means for adjusting a time delay amount by the time deinterleaving means in OFDM symbol units according to a propagation delay time of a received signal.
FDM receiver.