JPH11220716A - Bidirectional catv system and in-building transmission system for multiple dwelling house - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bidirectional CATV system for multiple dwelling houses which is difficult to transmit because of noises superimposed upon an incoming signal. SOLUTION: This device is an in-building transmission system for a multiple dwelling house in which a frequency band of an outgoing signal and an incoming signal flowing in a trunk is connected to the trunk in a bidirectional CATV, which uses the frequency band higher in the outgoing signal. In this case, the device is equipped with a head end 10 for bidirectionally connecting to the trunk, a transmission line 11 which is connected to the head end 10 and wired in the multiple dwelling house, and a connector 12 for connection of a reception terminal 13 installed with the transmission line 11. Then, a transmission frequency of the incoming signal transmitted to the transmission line 11 by way of the connector uses a frequency band which is higher than the transmission frequency of the outgoing signal flowing in the trunk and a line for transmitting the incoming signal in the head end 10 is equipped with a frequency converter 10e, which converts the transmission frequency for the incoming signal in the transmission line 11, in accordance with the frequency band of the incoming signal flowing in the truck.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-way CATV system and an in-building transmission system for an apartment house. Rather, the present invention relates to the technology of two-way CATV, which can transmit a signal from a general household on the receiving side to a transmission source such as a broadcasting station using the same CATV via the Internet or a telephone. The present invention relates to a technology for eliminating noise (inflow noise to an upstream signal) generated when a signal is transmitted to a transmission source such as a broadcasting station by telephone or the Internet while using an existing in-building transmission system as it is.

[0002]

2. Description of the Related Art As is well known, a CATV (cable television) is provided with a common antenna and a cable to prevent a TV image from being displayed poorly in a valley or a mountain of a building. This is transmitted to the subscriber's home. In addition, since the connection is established by the wired cable in this manner, the viewer / customer can be specified, and thus the television receiver is used as a pay television.

The conventional CATV access system (C
The ATV network has a tree-like network configuration using a coaxial cable from a broadcasting station (center) side to users such as ordinary homes and businesses. That is, as an example, as shown in FIG. 1, a node 3 serving as a branch point is arranged at a required point on a transmission line of a main line 2 connected to a broadcasting station 1 and terminal equipment installed in each home or the like. 4 is connected to the node 3 directly or via some nodes 5. And since the coaxial cable that constitutes the transmission path has a large transmission loss,
A repeater (amplifier) 6 is interposed every several hundred meters. Of course, the repeater 6 is of a standard that matches the transmission frequency.

[0004] The conventional system is a CATV that transmits information from the broadcast station 1 to the home (downlink signal) and that transmits unidirectionally. Recently, however, a receiver using the CATV transmission network is used. A general household has also developed a two-way CATV capable of transmitting information (up signal). At this time, since the downlink signal and the uplink signal use the same transmission path, the transmission frequency is usually changed in order to avoid crosstalk.

That is, the downstream signal uses a frequency band of 450 to 550 MHz in the case of a digital channel, and 70 to 450 MHz in the case of an analog channel.
A frequency band of z is used. The upstream signal is 10 to 50 M which is not mixed with the frequency band of the downstream signal.
A frequency band of Hz is used.

In the case of an apartment house 7 such as an apartment house having a large number of houses, which is the object of the present invention, a premises head end for collectively connecting to the trunk line 2 or the like is provided on the roof of the apartment house or the like. By arranging in a predetermined position and arranging coaxial cables from the head end of the premises in the building in a tree shape, it can be routed to each home, and facilities (reception terminals) capable of watching CATV can be installed and connected later. I can do it.

[0007]

However, when the bidirectional CATV is constructed using the frequency band of 10 to 50 MHz for the upstream signal as described above, noise is included in the upstream signal (ingress noise), and the upstream signal to be transmitted is transmitted. Affect. This means that in the 10 to 50 MHz band, short-wave broadcast waves and C
This is because the amount of noise mixed from the B radio wave and the like is extremely large, and the level of this mixing is large.

In order to solve such a problem, it is conceivable to transmit an uplink signal using a high frequency band which is not easily affected by noise. That is, assuming that the upper limit of the frequency band of the downlink signal is 550 MHz, if the frequency band is a high frequency band having a certain margin, there is no crosstalk with the downlink signal and the noise is strong.

However, if you do so,
In the constructed CATV network, it is necessary to exchange all the equipment set according to the frequency band of the uplink signal, such as at least a repeater provided for the uplink signal, which not only complicates the exchange work, It is not preferable because the existing equipment installed is wasted. And the influence of the noise is not based on the uplink signal output from all the receiving terminals, and some of the already installed ones are operating without any problem,
Since the equipment including the normally operating equipment must be replaced, the influence of the replacement is immeasurable. Further, as the frequency increases, the transmission distance decreases, so that many relay points must be installed.

In order to cope with this, a LAN is often constructed in an office of a company or the like. Therefore, appropriate technical measures are taken to block noise from being transmitted to a transmission line. ing. In addition, a resident of a single-family house who wants to participate in bidirectional CATV can be provided with a control device such as a modem, and can also take protective measures for suppressing noise from being transmitted to the main line. Furthermore, even when a plurality of houses are connected to a certain node, each house may be located away from each other, and it is not possible to specify a source of noise or a line transmitting noise. Since it can be performed relatively easily, a desired countermeasure can be taken for the specified noise source or line. In addition, conducting the necessary inspections to make such identification, at least connecting to the node, if you are already watching or wanting to watch CATV, you want to eliminate the effects of noise and take the necessary measures. We should not spare any cooperation.

On the other hand, in the case of a condominium such as a condominium with a large number of units, which is the object of the present invention, a CATV line is laid to each room, and the resident
If the user wants to use the ATV, a receiving terminal for viewing is connected to the line (connector for connection). Further, as shown in FIG. 1, although usually divided into a plurality of lines L, a plurality of connection connectors 8 are often attached to each line L in series. Therefore, when one line L is viewed, the receiving terminal 4 is not connected to all connectors, and some connectors may be partially unconnected.

That is, in many cases, the consciousness of the residents of an apartment house to the communication technology is largely different between those who are interested and those who are not. Accordingly, as in the case of the above-mentioned single-family house, the residents of the apartment house using the CATV desire the noise reduction measures and cooperate with the necessary work, but include the noise reduction measures including the residents who do not use the CATV. It is often difficult to get support for

Particularly, in the case of an apartment house, as described above, a plurality of connection points are arranged in series on a single line, and noise sources are also diversified.
Noise generated from homes that do not use TV may be superimposed on the transmission path. Therefore, when conducting surveys to identify noise sources and transmission lines affected by noise, and performing maintenance and repair after identification, regardless of whether CATV is used or not, the cooperation of residents of apartment houses・ Licensing is often essential. However, in practice, there is a problem that it is difficult to obtain a large number of approvals as described above. Further, for example, if the transmission path is buried in a wall, it may be difficult to take measures to eliminate noise.

As a result, the bidirectional CATV is used in a state where the influence of noise is allowed or the unidirectional CATV is used only by giving up, so that the bidirectional CATV in a comfortable environment is used. It was not easy to use. In addition, it is conceivable that each person individually takes some countermeasures. However, it is not preferable in terms of promoting interactive CATV, because the individual and individual countermeasures are burdened technically and costly.

Incidentally, it is assumed that noise countermeasures on the upstream signal are taken as in the present invention. Conventionally, as shown in Japanese Patent Application Laid-Open No. 5-268605, an uplink signal is transmitted by using a vacant channel in a frequency band used for a downlink signal. That is, two-way communication is performed between the upper and lower signals using the same frequency band. In the present invention, it is assumed that the user can individually respond like a detached house, and the present invention is not applied to an apartment house as in the present invention.

In order to solve the problem of the noise of the upstream signal in the apartment house as in the present invention, for example, there is an "interactive television enhancement facility" disclosed in Japanese Patent Application Laid-Open No. 9-83830. In the present invention, an upstream signal is transmitted using an empty channel in the frequency band of the downstream signal. And because they use the same frequency band,
When the signal flows on the same line, a downstream signal and an upstream signal are identified, and only the upstream signal is extracted and sent to the broadcasting station.

The present invention has been made in view of the above background, and has as its object to solve the above-described problems, and to cope individually with the CATV line. It is intended to eliminate the inevitable situation and allow any resident of an apartment house to respond to the two-way CATV without noise. In this case, the transmission equipment installed in the existing apartment house must be installed. It is an object of the present invention to provide a two-way CATV system and a transmission system in a building of a multi-family house, which can be used as it is so as not to impose an economic burden on residents.

[0018]

In order to achieve the above-mentioned object, in the bidirectional CATV system according to the present invention, the frequency bands of the downstream signal and the upstream signal flowing through the trunk line are set such that the frequency band of the downstream signal is higher. In the bidirectional CATV system to be used, an upstream signal in a transmission line in an apartment house connected to the trunk via a head end is transmitted using a higher frequency band than a downstream signal flowing through the trunk, When transmitted from the end to the trunk, the transmission frequency of the uplink signal in the transmission line is converted in accordance with the frequency band of the uplink signal flowing through the trunk.

Further, in the transmission system in a building of an apartment house according to the present invention, the frequency band of the downstream signal and the upstream signal flowing through the trunk is connected to the trunk in the bidirectional CATV using the higher frequency band of the downstream signal. A transmission system in a ridge of a multi-family dwelling that enables two-way communication, a head end for two-way connection with the main line, and a transmission line connected to the head end and wired in the multi-family dwelling. And a connector for receiving terminal connection, which is attached to the transmission line. The transmission frequency of the upstream signal sent to the transmission line via the connector uses a frequency band higher than the transmission frequency of the downstream signal flowing through the trunk, and the transmission frequency of the upstream signal in the head end is on the line. And a conversion unit configured to convert a transmission frequency of the upstream signal in the transmission path in accordance with a frequency band of the upstream signal flowing through the trunk line (claim 2).

According to the present invention, when the signal flows through the transmission line in the building, even if the signal is an upstream signal, the signal has a high frequency band, so that the signal is resistant to noise. Then, when leaving the headend, the upstream signal is converted into the frequency band of the upstream signal in the main line, so that the bidirectional CATV can be used similarly to the already installed main line and other facilities.

Also, since different frequency bands are used, the upstream signal and the downstream signal can be easily distinguished.

The transmission frequency of the upstream signal sent to the transmission line in the building is 650 to 900 MHz.
(Claim 3). That is,
Since it is a predetermined area, it may be the whole of the above range or a part of it. And the upper limit is 900MHz
The reason is that, in a frequency band of 950 MHz or higher, channels used by other communication devices such as a mobile phone are allocated, so that the influence is eliminated.

On the other hand, the lower limit is set to 650 MHz so that the upper limit of the frequency band of the downstream signal used in many existing CATVs is 450 MHz or 550 MHz, so that the lower limit is not mixed.

Since the predetermined area in the third aspect of the invention is, of course, required to satisfy the requirements of the second aspect, which is a prerequisite, the transmission frequency band of the downlink signal flowing through the main line is assumed. Is 650 MHz or more, the lower limit of the predetermined area is also set to 650 MHz.
It is limited to a range higher than z. And the conventional CA
The upper limit of the frequency band of the downlink signal in TV is 550 MH
Since z is large, the lower limit of the predetermined area is 650 M as described above.
Even if it is set to Hz, there is a sufficient margin and no crosstalk occurs. In some cases, the upper limit is expanded to about 770 MHz by widening the downlink signal due to the increase in the number of channels. In such a case, for example, a predetermined area within 850 to 900 MHz may be used.

According to the present invention, when converting from a one-way CATV system in an apartment house or the like to a two-way CATV for transmitting to a source such as a broadcasting station by telephone or the Internet, or in order to use the two-way CATV from the beginning. When deploying, the frequency of the upstream signal from each household in the apartment complex is set to a high frequency (eg, a high frequency of 650 to 900 MHz) that has not been used as the frequency of the upstream signal.
However, the upstream signal to the trunk at the headend in the building of the apartment house is the frequency band of the upstream signal (for example, 1
0 to 50 MHz), the ingress noise can be eliminated. As equipment for that purpose, a frequency conversion means may be provided on the upstream line of the head end, or a function of transmitting a signal at a high frequency to the receiving terminal may be provided. Therefore, protection measures for transmission lines and inspections and
Maintenance is not required.

[0026]

FIG. 2 shows a main part of an embodiment of the present invention. In the present invention, by changing a part of the system configuration in the apartment house 7 shown in FIG.
In addition to the existing access system (CATV network) such as the trunk line 2 shown in FIG. 1, most of the in-building transmission system of the apartment house 7 can be used as it is.

First, the in-building transmission system of the apartment house 7 will be described with reference to FIG. A plurality of transmission lines 1 are connected to a premises headend 10 connected to a CATV trunk line (not shown).
1 are connected in parallel. This transmission line 11
Are installed in each level of the apartment house 7 in this example. A connector terminal 12 provided in each room of the same level in series is connected to the transmission line 11.
Therefore, a user who wants to use CATV obtains the receiving terminal 13 from a CATV trader or the like, and transfers it to the connector terminal 1
2 can be connected to the CATV network.

The receiving terminal 13 receives the downlink signal at the home terminal 13a and outputs audio / image data based on the received signal to the television 13b in order to perform bidirectional transmission. On the other hand, the upstream signal is generated using, for example, a personal computer 13c, sent to the transmission line 11 via the modem 13d, and
Has been reached. Then, the signal is sent from the local headend 10 to the trunk line, and the upstream signal is transmitted to the broadcasting station.

Further, the local headend 10 separates the upstream signal and the downstream signal and transmits them inside, and amplifies the signals in the middle so that each signal can be transmitted to the other party without being attenuated. For this purpose, a duplexer 10a is provided at the input / output end, and a down line 10b and an up line 10b are provided.
c. Each of the above-described configurations is the same as the conventional one.

Here, in the present invention, the transmission frequency of each signal flowing through the trunk line is 70 to 550 M
Hz and the upstream signal was 10 to 50 MHz. And the frequency of each signal flowing through the transmission line 11 in the building is
The downlink signal is set to 70 to 550 MHz, but the uplink signal is set to 650 MHz to 650 MHz, which is higher than the frequency band of the downlink signal.
850 MHz (see FIG. 3A). This allows
Since both the upstream and downstream signals flowing through the line 11 in the ridge of the apartment complex 7 are in the high-frequency band, they are resistant to noise,
It is possible to suppress as much as possible that noise is superimposed on the uplink signal and transmitted to the broadcasting station. In such a system configuration, since the trunk line is the same as the conventional one, not only the equipment for the trunk line but also, for example, already the upstream signals 20 to 5
The terminal equipment using the bidirectional CATV using 0 MHz can be used as it is, and such continued use is economical because there is no need to replace the equipment or the like.

Then, in order to realize such a system,
First, a function of outputting at a high frequency of 650 to 850 MHz is added to the receiving terminal 13. That is, a modem is prepared such that the transmission frequency of the signal output from the modem 13d is in the high frequency band. This can be manufactured, for example, by changing the oscillation frequency of the local oscillator and mixing the local oscillator and the signal with a mixer. Of course, other structures may be used. Then, the frequency of the upstream signal from each house of the apartment house 7 is set to 650-85.
There is almost no problem with setting a high frequency of 0 MHz because the capability of the personal computer 13c has been improved recently.

Further, as the premises head end 10,
Downstream signal amplifier 10d is 70 to 550 in the same manner as the conventional one.
The one that amplifies the signal of MHz is used. On the other hand, the upstream signal amplifier 10e not only amplifies the amplitude,
It is configured using an amplification frequency converter that also converts the frequency. The frequency conversion is performed by converting the frequency of the upstream signal (650 to 850 MHz) flowing in the building into the frequency of the upstream signal (10 to 50 MHz) flowing in the trunk line 2.

Note that, among the receiving terminals 13, at least the home terminal 13a is manufactured and sold by the CATV trader with responsibility. Therefore, if a CATV provider prepares a modem for transmitting at a high frequency as described above, the burden on the user side can be reduced. Further, as a means for transmitting at a high frequency, the function related to the modem may be incorporated as described above. However, the present invention is not limited to this, and the modem may use a normal low frequency (10 to 5).
(0 MHz), and a frequency converter may be provided between the modem and the connector to convert the signal into a desired high-frequency signal and transmit the signal.

In the above-described example, the transmission frequency of the upstream signal in the building is 650 to 850 MHz. However, the present invention is not limited to this, and the point is that the transmission frequency is higher than the frequency of the downstream signal (to reduce noise). Strong), and it is sufficient to take a certain margin with respect to the upper limit of the transmission frequency range of the downlink signal (it does not interfere with the downlink signal and is less affected by noise). For example, as shown by a two-dot chain line in FIG. Alternatively, the upper limit of usable frequencies may be increased to 900. Also, instead of such an expansion, the lower limit may be increased in accordance with the increase of the upper limit. Of course, the frequency band to be set may be narrow. In Japan, 950 MHz or more is allocated to a frequency band used by a communication device such as a mobile phone. Therefore, it is necessary to avoid interference with such communication devices. Therefore, the upper limit is set to 900 MHz by taking a certain margin as described above.

Further, as shown in FIG. 3 (B), recently, with the increase in the number of channels, the frequency of the
Some increase to about MHz. In that case,
As shown in FIG. 3B, the frequency of the upstream signal in the building is 8
As in the case of 50 to 900, it may be shifted to the wide area side so as not to interfere with the downlink signal.

Next, in order to demonstrate the effects of the present invention, the following experiments were performed. That is, in order to grasp the state of noise distribution in the upstream transmission band in an apartment house or the like, an ingress noise was measured in an actual building apartment. One is a general CATV upstream band of 10 to 10.
The other is about 650 to 850 MHz, which is the upstream band of the high frequency band.

FIG. 4 shows a television common listening wiring system measured in a construction office building owned by the applicant. The output of the in-building amplifier A1 in the in-building head end 10 is distributed to the distributor 2
0, a tree-shaped transmission path is formed, and a terminal connector 12 is connected to an end of the transmission path. The building used for the experiment consisted of a main building and an annex, with one headend in the building.
0 is used for management.

In an actual experiment, at the output terminal of the in-building amplifier (bidirectional) A1 at the in-building head end, noise coming from each terminal (connector 12) in the building through an auxiliary amplifier was analyzed by a spectrum analyzer. The maximum value of the noise was recorded using the max hold function. The measurement was continuously performed alternately for about 30 minutes between 13:00 and 17:00 in the above two frequency bands.

The measuring instruments used were two spectrum analyzers (R3361NK manufactured by Advantest), one pilot generator (48 MHz) and one plotter (manufactured by Michal Communication), and 5 to 5 auxiliary communication devices.
1 unit for 5MHz band amplification (MBSA-4 manufactured by Miharu Communication Co., Ltd.)
5-A gain 20 dB), one for 470-770 MHz band amplification (NW Antenna BW-35A, gain 33d)
B) was used. Although illustration is omitted, an amplifier and an attenuator are installed on the actual transmission line in the building, but in this experiment, the amplifier is turned off (actually, the input / output terminals are short-circuited). At the same time, the attenuator was removed. This is the same in the next transmission loss experiment.

FIG. 5 shows a noise distribution as a result of measuring ingress noise in a 10 to 50 MHz band which is a general CATV upstream band. The horizontal axis indicates frequency, and the vertical axis indicates noise intensity in dB. It can be seen that the noise intensity is high over the entire frequency and that the noise level tends to decrease as the frequency increases. It can be seen that many types of noise are impulsive from electrical equipment and the like, and some radio waves such as short-wave broadcast waves are also mixed.

FIG. 6 shows a high-order upstream band of 650-8.
It is a noise distribution as a result of measuring ingress noise at 50 MHz. Irrespective of the numerical value of the frequency, the noise intensity is extremely small, radio waves are mixed in to some extent, and impulsive noise is not mixed in from electrical equipment or the like.

The radio wave with a high noise intensity observed at 810 to 830 MHz has a base station of a mobile phone installed on the roof of the above-mentioned construction office, which is 818 to 826 MHz.
It is considered that z radio waves are being generated.

As is clear from a comparison between FIG. 5 and FIG. 6, it can be seen that the ingress noise in the high frequency band of 650 to 850 MHz is smaller.

The above two types of measurements are performed between about 13:00 and 17:00. The measurement results near the end of the measurements are shown in FIG.
FIG. 8 shows the results in the 50 MHz band. The comparison with FIG. 5 and FIG. 7 clearly shows that the comparison with FIG.
The noise intensity was generally higher in the evening than in the daytime, whereas in the frequency of the present invention, as is clear from a comparison between FIG. 6 and FIG. I was not able to admit. Note that, although not specifically illustrated, the above tendency also appears in the experimental results in an intermediate time zone. Further, according to the experimental results, the radio wave bands 818 to 8 of the mobile phone shown in FIG.
It goes without saying that it is safer to avoid 26 MHz. It should be noted that even if the provisional range is used, noise is not always generated, so that the effect of reducing the influence of noise can be sufficiently expected as compared with a conventional device such as a 5-55 MHz band.

Next, the transmission loss and frequency characteristics of the upstream band in the apartment house shown in FIG. 4 were measured. Specifically, a sweep signal of 5 to 55 MHz and a sweep signal of 650 to 850 MHz were inserted as test signals into the terminal 12a at the terminal end of the transmission line in the building, and the transmission loss characteristics with respect to frequency were determined by receiving the signals at the head end 10. .

As a result, FIG. 9 (5-55 MHz) and FIG.
0 (650 to 850 MHz). As is apparent from a comparison between the two figures, transmission loss is slightly observed in the frequency band of the present invention shown in FIG. 10 as compared with that shown in FIG. This is due to the increase in loss in coaxial cables due to the increase in frequency, but if the decrease is to this extent, consideration should be given to using an amplifier with a large up gain for the premises. There is no practical problem because it can be solved. Therefore, it can be said that it is not necessary for each individual in the apartment complex to treat it independently.

[0047]

As described above, the bidirectional CA according to the present invention is provided.
In the TV system and the in-building transmission system of a multi-family house, when changing from a one-way CATV in a multi-family house such as an apartment to a two-way CATV, or when already using a two-way CATV, each home in the multi-family house The frequency of the upstream signal is set to a high frequency such as about 650 to 900 MHz, but the ingress noise of the upstream signal can be eliminated simply by attaching a converter for converting the frequency to the conventional CATV premises head end. Having.

[0048] For this reason, there is no technical burden or economic burden on the residents of the apartment complex with any new equipment or the like.
In addition, it is possible to provide a technology capable of improving the conventional technology to the latest communication technology without imposing a great economic burden on the owner of the apartment house.

In addition, by possessing such latest technology, it can be used as a means of communication with the outside without worrying about noises in an emergency such as a disaster, so that it is a meaningful lifeline for residents. Become.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a configuration of a general CATV system.

FIG. 2 is a conceptual diagram showing an example of a transmission system in a building of an apartment house which is a main part of the present invention.

FIG. 3 is a diagram illustrating an example of a used frequency band in the present invention.

FIG. 4 is a diagram showing an apartment house used in an experiment for verifying the effects of the present invention.

FIG. 5 is a diagram showing experimental results.

FIG. 6 is a diagram showing experimental results.

FIG. 7 is a diagram showing experimental results.

FIG. 8 is a view showing an experimental result.

FIG. 9 is a view showing an experimental result.

FIG. 10 is a view showing an experimental result.

[Explanation of symbols]

 7 apartment house 10 head end in building 10e frequency converter 11 transmission line 12 connector 13 receiving terminal

Claims (3)

[Claims] 1. A bidirectional CATV system in which the frequency band of a downstream signal and an upstream signal flowing through a main line uses a higher frequency band of the downstream signal, and transmission in an apartment house connected to the main line via a head end. The upstream signal in the line is transmitted using a higher frequency band than the downstream signal flowing through the trunk, and when transmitted from the head end to the trunk, the transmission frequency of the upstream signal in the transmission line is A bidirectional CATV system adapted to perform conversion according to a frequency band of an upstream signal flowing through the trunk line. 2. A multi-dwelling building in which the frequency band of a downstream signal and an upstream signal flowing through a main line is connected to the main line in a two-way CATV using a higher frequency band of the downstream signal to enable two-way communication. A transmission system, comprising: a head end for bidirectional connection with the trunk line; a transmission line connected to the head end and wired in the housing complex; and a receiving terminal attached to the transmission line. The transmission frequency of the upstream signal sent to the transmission line via the connector uses a frequency band higher than the transmission frequency of the downstream signal flowing through the trunk, and transmits the upstream signal in the head end. On the line, a converter for converting the transmission frequency of the upstream signal in the transmission line in accordance with the frequency band of the upstream signal flowing through the trunk line. Building in the transmission system of the housing complex with a. 3. The in-building transmission system according to claim 2, wherein the transmission frequency of the upstream signal sent to the transmission line is a predetermined range in a range of 650 to 900 MHz.