Multi-band coax extender for in-building digital communicaton systems

Multi-band coaxial extender for digital communication system in building

The present invention claims priority to the provisional application of US Serial No. 60/267,046 filed on February 7, 2001. This invention provides a way to increase the signal carrying capacity of the system to provide the local coaxial cable as described in the pending application 09/482,836 according to the provisional application No.60/115,646 filed on January 13, 1999 High-speed data communication. Another application that describes the environment of the present invention and is assigned to the common assignee coaXmedia is Architecture and Method for Automated Distributed Gain Control for Internet Communications for MDUs and Hotels (application No. 09/ based on provisional application No. 60/193,855). 818,378). The filing date of No.60/193,855 application is March 30, 2000.

For the convenience of readers, the applicant has added some subtitles to make the internal structure of this manual clear and to facilitate the positioning of certain discussions. These subheadings are just convenient aids, not for restrictions on the text under a particular heading.

To make the description clearer, generic terminology for components is used. The use of component-specific terms suitable for accomplishing some purposes in the disclosure of the present invention should be understood to include all technical equivalents that achieve the same purpose regardless of whether the internal operation of the named component or replacement component utilizes the same principle. The specificity used in order to make the description clearer should not be misunderstood as limiting the scope of disclosure to the named elements, unless such limitation is explicitly stated in the following description or claims.

Technical field

The invention relates to the field of data communication. More specifically, the present invention is one of the ongoing improvements in the field of data communication, dedicated to the use of a tree and branch distributed system for upstream and downstream data communication between a hub server and a group of two or more client modems. Preferably, the client modem is suitable for allowing plug-and-play connections or other simple connections between the portable computer and the tree and branch network. The tree and branch network are preferably connected to the Internet. Therefore, the present invention can be used in a hotel or a multi-dwelling unit (MDU) and similar buildings to allow plug-and-play access to the Internet on the existing coaxial TV network. It should be noted that the present invention is not limited to installation in hotels or multi-family residential units (MDU) and similar buildings, these are just examples of locations that can benefit from the present invention.

Background technique

Application No.09/482,836 describes a system capable of connecting devices such as personal computers to a specific modem that is the same as the genetic tree and branch in similar buildings such as hotels and multi-family residential units (MDUs). The shaft network is connected. The system described in the No.09/482,836 application utilizes two frequency bands outside the range of cable television. Therefore, this system will have a frequency range of a downlink data channel and a frequency range of an uplink data channel. Since this is a tree and branch network, all modem devices will receive communications, so all downstream communications must identify which modem device(s) are addressed. Instead, communication from multiple independent modem devices to the upstream end of the network must be controlled so that at any one time, only one modem device sends upstream communications to avoid simultaneous transmissions on the same frequency by more than one client modem ("bus connection ") Distortion of uplink data caused by. The control method used in the reference application is based on the polling and response model.

The assignee, coaXmedia, improves the prior art by providing a way to increase the load direction of the main feeder cable and the communication capability from the client modem.

In a preferred embodiment, client modems are mass-produced to operate in the same pair of upstream and downstream frequency bands.

The situation described by the two reference applications and the present invention is generally shown in FIG. 1.

Figure 1 can summarize the above-mentioned solutions. In Figure 1, the bandwidth (108) between 50MHz and 860MHz is allocated for the downstream transmission of television signals. The frequency band (104) from 5 MHz to 42 MHz is used for existing services that utilize uplink services such as pay programs. Many frequency bands (112) between 860MHz and 900MHz are used for other applications such as portable phones. Due to the relatively high radiation field strength of portable phones, care should be taken to avoid using frequencies close to those used for portable phones.

The genetic coaxial distribution network has splitters and couplers that can operate satisfactorily up to about 1 GHz (1000 MHz). Therefore, the No.09/482,836 application and the No.09/818,378 application both suggest having a data downlink frequency and a data uplink frequency located in the frequency band between 900MHz and 1000MHz. In Fig. 1, the upstream frequency is represented at 915 MHz (116), and the downstream frequency is represented at 980 MHz (120). It is believed that a single uplink and downlink frequency pair is sufficient for 50 to 100 users or client modems to access the Internet in both directions.

Application No. 09/818,378 teaches that additional downlink spectrum can be allocated in the frequency band between 1 GHz and about 1.6 GHz, and replacement of existing components with components sufficient to operate in this frequency band can provide such a frequency band. This solution will require a device for the client modem to recognize the request to switch from the 980MHz regular downstream channel to the high-frequency channel. Therefore, in addition to the cost of updating the components of the genetic coaxial network, there is also a need to provide a more expensive client modem that can operate on multiple downstream frequencies.

As shown in Figure 2, the coaxial cable TV distribution system inside a larger multi-family residential unit (MDU) building usually has far more than 50 coaxial sockets. In addition to television channels, these larger distribution systems usually have hybrid equipment 604 for local area services. In a hotel, local area services can include digital video servers, checkout information, and information about hotel restaurants.

The local service 604 and the cable TV channel 608 are combined at element 612 and amplified by the central location amplifier 620 before the feeder cable 624 (sometimes called a coaxial riser).

Larger systems may include one or more central location splitters 630 feeding an additional amplifier 634 and another long feeder cable 638 pair. In order to avoid confusion in the figure, the local distribution network connected to the long feeder cable 638 is not shown. These distribution systems require intermediate amplifiers 650 to boost signal levels that have been attenuated by the loss of coaxial cables, splitters, and direction taps in order to provide sufficient signals to televisions and/or other entertainment equipment Level. These intermediate amplifiers 650 are distributed in MDUs at a certain distance from the central feed point to buildings that can provide services from CATV, television broadcast antennas, or through devices such as optical fibers. These intermediate amplifiers 650 usually carry TV channel signals in a single direction at frequencies in the range of 50 MHz to 750 MHz. In some cases, these amplifiers are equipped with inverting amplifiers that can load signals in the frequency range of 5MHz to 42MHz. The opposite channel is sometimes used to load a command signal requesting a pay-per-view (PPV) television service or to load an upstream channel of a cable modem for Internet access at an increased frequency.

When the TV coaxial distribution system is used to load data outside the CATV frequency band, a bypass amplifier connected to the coaxial cable through a frequency selective duplexer needs to be provided for each signal direction. In this way, when implementing a system that loads data on an existing cable television network, a circuit as shown in FIG. 3 is needed to boost the data signal.

Figure 3 is performed without interfering with the operation of the existing CATV line expansion amplifier 650. The amplifier 650 is isolated by a pair of low-pass filters 654 in the duplexer 660. A pair of high-pass filters 658 provide a high-frequency bypass bypassing the existing amplifier 650. The splitter 664 divides the bypass into a downstream channel and an upstream channel. The shielding 668 isolates the downstream channel and the upstream channel from each other.

For a system that uses 980 MHz as the downstream frequency and 915 MHz as the upstream frequency, the downstream channel includes a 980 MHz bypass filter 672, a variable attenuator 676, an amplifier 680, and a 915 MHz band rejection filter 684. The upstream channel includes a 915 MHz band pass filter 688, a variable attenuator 676, an amplifier 692, and a 980 MHz band rejection filter 696.

When too many users share a data distribution system, there may be insufficient capacity. Insufficient capacity can lead to service degradation in the form of lost or delayed data packets. The number of "excessive" users is a function of the type of data required by individual users. How many users are "too many" users? It depends on whether users are likely to connect at the same time, whether they need to receive or transmit large amounts of data, and whether the application is sensitive to delays in receiving data packets. With the evolution toward multimedia, video conferencing, and other data-intensive applications, the amount of data communicated with a single connected user increases, and the number of users that can be supported by the data network decreases. Low-latency applications such as video conferencing or IP (Internet Protocol) telephony exacerbate this problem.

Although simply using additional uplink or downlink channel frequencies may seem attractive, it is not an attractive solution.

There are some advantages to having a group of client modems tuned to receive a single downstream frequency and transmit on a single upstream frequency. For example, if there is no need to provide a modem that can be tuned to operate in the range of reception or transmission frequencies, manufacturing and installation costs are reduced.

Even if the designer is willing to give up the advantage of using the same transmission and reception frequency pair for the entire set of client modems, there is still a practical limit to the number of frequency bands that can be used above 900 MHz. One problem is that about 1 GHz is the upper limit of the effective frequency. This limitation stems from the fact that the splitter, directional taps, connectors in the distal part of the coaxial distribution tree and the branch network, and sometimes the coaxial cable itself has poor frequency performance at frequencies higher than 1 GHz.

Utilizing several frequency channels in the frequency spectrum above 900 MHz and below 1 GHz has its own problems. One problem is that adding additional channels will result in an increase in total signal power. Thus, this additional signal power will increase the risk of signal overload in the active components of the network. This overload can adversely affect the delivery of television services. An incidental problem is that adding more channels will increase the complexity of the filters required to separate the individual channels.

Fortunately, the main (feeding) coaxial distribution cables (624, 638) that connect the TV signal between the feed point to the building and the distribution "boost" amplifier 650 can usually load frequencies higher than 1 GHz well. Because these feeder cables usually do not include directional taps or splitters. Even if there are some taps or splitters in front of the boost amplifier, it is easy to replace or update these components. It's easy because even if there are taps or splitters in front of the boost amplifier, there are only a few and it's easy to connect. This is the opposite of the situation behind the boost amplifier. There are many taps behind the boost amplifier, and most of them are difficult to access.

Summary of the invention

The present invention solves the limitations of the prior art by using a two-stage system. In a preferred embodiment, the feeder cable stage utilizes the capacity of the feeder cable to load multi-band data in the frequency spectrum above 1 GHz. The local level is in the position of the TV "boost" amplifier, converts the data of these frequency bands into corresponding frequency bands in the frequency range of 900MHz to 1GHz, and amplifies these downstream communications, and transmits them forward to the independent TV coaxial distribution system. The local tree and the branch network are connected in groups by end users. Similarly, at least some of the uplink communications are shifted to frequencies above 1 GHz for uplink transmission on the feeder cable. The solution of the present invention provides a higher data capacity in a system where all data interface "modems" can be the same and do not have complex tuning functions. In this way, it is possible to mass-produce the modems used at the end user termination points of the tree and branch networks, and since multiple upstream and downstream frequency bands will be converted into distributed local-level standard upstream and downstream channels, the modem can be preset as The given upstream and downstream channels. These modems can be used interchangeably on several different local trees and branch networks.

Optionally, a set of upstream and downstream communications can be propagated on the feeder cable at the frequency used by the client modem, so that this part of the communication does not require frequency shifting. Although due to administrative or economic elements, it may be desirable for all client modems to utilize the same frequency, the present invention is not limited to networks where all client modems only operate on a pair of upstream and downstream frequencies. In alternative embodiments, it is recommended to use alternative frequency bands other than above 1 GHz.

Description of the drawings

Fig. 1 shows frequency bands related to the application of uplink (116) and downlink (120) data transmission on the genetic tree and branch distribution network of cable television.

Figure 2 depicts the relationship between the feeder cables (624 and 638) and the local coaxial distribution networks 762, 766, 768, and 770.

Figure 3 depicts the components used in the line extender (extender) to provide amplified signals for the data sent on the genetic tree and branch distribution network.

FIG. 4 illustrates an embodiment of the present invention that utilizes three different downstream frequencies on the feeder cable 624 and only uses one upstream frequency on the feeder cable 624.

FIG. 5 illustrates another embodiment of the present invention that utilizes three different downstream frequencies on the feeder cable 624 and three different upstream frequencies on the feeder cable 624.

detailed description

Figures 4 and 5 show two main embodiments of the present invention. These two embodiments are shown in a combination of the figure A showing the upstream device of the feeder cable 624 and the figure B showing the downstream device of the feeder cable 624.

Both embodiments have a central system that feeds one or more feeder cables (624 or 638) and multiple local area networks. In a preferred embodiment, each local area network will utilize a standard client modem with preset frequencies for transmission and reception.

The difference between Fig. 4 and Fig. 5 is that Fig. 4 considers the situation where one uplink frequency is sufficient for the entire group of client modems and the demand for downlink data exceeds the bandwidth of a single downlink frequency. In Figures 4 and 5, before being converted to a standard downlink frequency for transmission on a parallel local area network, the system uses several frequencies to load downlink transmission on the feeder cable. The embodiment shown in Figure 4 will be suitable for situations where there is much more information sent downstream to the client modem than the information sent upstream from the client modem. Web browsing is an example of an application with this downstream/uplink imbalance. The transmission of the data required to construct the webpage requires more downlink capacity than the data required for the simple request of the uplink communication to display this webpage. The additional load on downstream capacity is value-added (VA) services such as local digital video services that require broadband capacity. The combination of downstream data from Internet service providers and bandwidth-sensitive value-added services will often result in the need for more downstream capacity than upstream capacity. In many cases, there are too many downlink services for the existing feeder cables, and it is impossible to load all services on one downlink frequency in the 900MHz to 1GHz spectrum.

The system described in Figure 5 is similar to Figure 4 in that the system described has multiple downstream frequencies of the feeder cable. The embodiment shown in Fig. 5 differs from Fig. 4 in that it has more than one upstream frequency that propagates upstream through the feeder cable. Figure 5 is suitable for working in situations where both upstream and downstream services exceed the bandwidth of a single frequency on the feeder cable. E-mail or IP telephony is an application that is more evenly distributed between upstream and downstream data.

Before reaching the low frequency lead of the duplexer 316, the amplifier 312 amplifies the cable television signal from the coaxial cable 608 connected to the CATV overhead line.

The high frequency leads of the duplexer 316 receive data from Internet access, local value-added services (if any), and from the digital video server 712 (if any). More specifically, the connection to the Internet 704 may be branched from the CATV overhead drop cable 608, or the connection to the Internet 704 may come from another communication route such as optical fiber, cable modem, or wireless.

In Figure 4A, the role of the central hub is designated to bridge a group of components. The conversion from the Internet protocol to the local area network protocol is performed in the central server 708. Typically, this conversion is from the Internet to PPPoE (PPP over Ethernet) in the downstream direction, while the upstream transmission is the other way around. Optionally, other local value-added services can be managed in the central server 708. Part of the local value-added service may include a request to transfer content from the digital audio server 712.

Downstream data including data from the digital video server 712 passes through a router 716 that distributes the data to a set of two or more central modems (720, 722, and 724). Since this embodiment is set for relatively few upstream services, only one central modem 720 is used to receive upstream services. In the example shown in Figure 4A, the signal is transmitted to a group of client modems at a feeder cable frequency of 980 MHz. The downstream service carried to another set of client modems at the feeder cable frequency of 1.05 GHz to take advantage of the feeder cable's ability to load frequencies higher than one gigahertz. Downlink service carried to another group of client modems at the feeder cable frequency of 1.10GHz.

In a preferred embodiment, there are additional modems for each additional feeder cable frequency used for downlink traffic. As is apparent in FIG. 4B, the application of the downstream frequency used by the client modem as one of the feeder cable frequencies reduces the number of components used in FIG. 4B. Instead, a system can be established to use a downstream feeder cable frequency higher than one gigahertz for all central modems, and then convert all downstream traffic to the downstream frequency used by the client modems.

On a single upstream feeder cable frequency of 915 MHz, which is the same frequency used by the client modems, the upstream traffic from all client modems is transmitted. The coaxial cables from each of the three central modems are connected to a combiner 734, which is connected to the high frequency lead of the duplexer 316.

Figure 4B depicts a multi-band coax extender used with Figure 4A. As an overview, the multi-band coaxial extender receives each of the three downstream frequency bands, and uses local frequency synthesizers and mixing components to convert two of the received frequency bands into a connection with the main feeder cable. Load two separate streams of the same frequency band as the third spectrum. Then, using a spectrum duplexer, each of these streams is directed into a separate coaxial cable branch that can feed 50 or more client modems (for example, coaXmedia SandDollarTM client modems). In the upstream direction, use directional taps to combine the signals of the same frequency spectrum from each individual coaxial cable branch, filter to remove out-of-band noise, and insert it as an upstream signal on the feeder cable 624 and return Amplify before going to the central modem 720 with the upstream receiver.

The system generally described above is implemented in an embodiment with the following details shown in FIG. 4B. Starting at the end of the feeder cable 624 shown in FIG. 4B, the feeder cable 624 feeds the duplexer 750. In a preferred embodiment, the duplexer 750 is provided with a low pass from DC to 865 MHz and a high pass above 905 MHz. The low frequency lead of the duplexer 750 will feed to the input of the TV amplifier 650, which feeds the duplexers 754, 756, and 758 in turn. Each of the duplexers (754, 756, and 758) feeds local coaxial distribution networks 762, 766, and 770.

Depending on the expected load, the distributed network serves approximately fifty end users. The distribution network is terminated in the device as described in module 400. The details of one of the multiple blocks are shown on FIG. 4B. For the purpose of the present invention, the actual layout of the internal components of the module 400 is not important, and the given examples should not be construed as limiting the scope of the present invention. For the purpose of description, the internal components of the module 400 are as follows: Inside the component 400, the client modem 408 is connected to the Qualcomm port on the duplexer 406. The duplexer 406 is connected to the coaxial socket 404. The sampling values of the downstream leads of the duplexer 406 are LP 5MHz to 860MHz and HP 900MHz to 1GHz. A conventional TV coaxial cable 412 connects the TV 416 to the low-pass port on the duplexer 406. The client modem 408 is shown as a sand dollar to distinguish it from the trademark name of the assignee's client modem.

The user can connect the downlink device 420 to the datacord of the client modem 408. The user's downlink device 420 may be a personal computer ("PC"). Although the downstream device 420 may be a desktop or portable personal computer, it may also be some other device capable of interfacing with an external source of digital data. One such example is a device called a PDA ("Personal Digital Assistant"). Therefore, the present invention can communicate between the downlink device 420 and the Internet by substantially utilizing the existing infrastructure for transmitting cable TV signals to the user TV 416.

Each of the three duplexers (754, 756, and 758) receives 980MHz downstream transmission and 915MHz upstream transmission. Although the total downlink traffic of all three local coaxial distribution networks (762, 766, and 770) is too much to be transmitted on one frequency on the feeder cable 624, when it is divided into three parallel When in a local area network, it is not a problem to have all downlink services on the same frequency.

The components in module 800 handle the conversion from three feeder cable frequencies to three parallel local area networks. The downstream path starts from the duplexer 750 upstream of the amplifier 650. The high frequency lead of the duplexer 750 is fed to the splitter 804. The downstream path continues from the splitter 804 to the amplifier 808. The 980MHz downstream traffic part passes through a bandpass filter 812 set at 980MHz (passes plus or minus 20MHz-the same goes for bandpass filters 836 and 852). Since 980 MHz is the standard frequency used by the client modem 408, there is no need for any conversion, and the downstream traffic passes through the direction tap 816 to the high frequency lead of the duplexer 754 on the route to the local coaxial distribution network 762.

Parallel to the downlink service path leading to the local coaxial distribution network 762, there is a downlink service path leading to the local coaxial distribution network 766. In the amplifier 808, there is a downstream service of a network 766 with a feeder cable frequency of 1.05 GHz, and a high-pass filter 820 that is set to pass a frequency higher than 1.02 GHz is passed. The high-pass filter 820 is used to prevent the residual low-band spectrum that may pass directly through one of the mixers (832 or 848), which interferes with the down-conversion of the higher spectrum band of the downstream service of the local coaxial distribution network 756 or 758. A similar spectrum of 980MHz is obtained.

By using the oscillator 824, the synthesizer 828, and the mixer 832, the frequency of the downlink service is shifted to 980 MHz, and the band pass filter 836 and the direction tap 840 are used to reach the high frequency lead of the duplexer 756. (A typical synthesizer output value is 70 MHz or 2.03 GHz.) The duplexer 756 is connected to the local distribution network 766.

In a similar manner, the downlink traffic of the local coaxial distribution network 770 is propagated on the coaxial feeder cable 624 at 1.10 GHz. The downlink service passes through the high-pass filter 820. By using the oscillator 824, the synthesizer 844, and the mixer 848, the frequency of the downstream transmission is shifted to 980 MHz, and the band pass filter 852 and the direction tap 856 are used to reach the high frequency lead of the duplexer 758. (A typical synthesizer output value is 120 MHz or 2.08 GHz.) The duplexer 758 is connected to the local distribution network 770.

As described in connection with FIG. 4A, the feeder cable 624 can be loaded with downstream services reaching the local coaxial distribution network 762 at frequencies other than the standard downstream frequency (980 MHz) used by the client modem 408. This choice will require adjustments to the filter scheme and additional synthesizers and mixers.

The standard frequency 915MHz is used to transmit uplink services from three local coaxial distribution networks. The upstream path is from the duplexers 754, 756, and 758 through the direction taps 816, 840, and 856 to the combiner 860.

The combined uplink service passes through a band pass filter 864 set for 915 MHz (plus or minus 10 MHz). At 868, the upstream traffic is amplified and passed through the filter 804 to the high frequency lead of the duplexer 750 to the feeder cable 624.

Figure 4 depicts a system with three modem pairs serving three local area distribution networks. In fact, in this case, considering the required downstream capacity, any number of modem pairs can be combined. Two small local area distribution networks can share a pair of modem and feeder cable frequencies. The present invention can be used in the case of two or more local coaxial distribution networks.

Figure 5A depicts an arrangement similar to Figure 4A, except that each central modulator demodulator (720, 726, and 728) includes an uplink receiver. Tune each receiver to a different coaxial feed upstream frequency. The advantage of this arrangement is to increase the upstream capacity. Just as a principle that can be independently applied to the frequency or spectrum used, a specific frequency band is shown by way of example. As the downlink frequency, using the standard transmission frequency of the customer-adjusted demodulator 408 as one of the coaxial feed uplink frequencies has a little advantage. However, one of the upstream frequencies of the coaxial feed is not required to be the same as the standard transmission frequency of the client modem 408.

Figure 5B depicts an arrangement similar to that of Figure 4B, except that prior to combining for transmission in the upstream direction on the main coaxial feeder cable 624, the same frequency spectrum from two separate local coaxial distribution networks The uplink frequency band is shifted. In this example, the downlink traffic at the splitter 804 is loaded at frequencies 980 MHz, 1.11 GHz, and 1.24 GHz. The uplink traffic at the load splitter 804 at frequencies 915MHz, 1.045GHz and 1.175GHz.

More specifically, in a preferred embodiment, the uplink traffic from the local coaxial distribution network 762 reaches the combiner 860 through the duplexer 754, the direction tap 816, and the band pass filter 872 without changing the uplink frequency of 915 MHz. (Typical values of bandpass filters 872, 876, and 880 are 915+/-20MHz.) The upstream service from the local coaxial distribution network 766 is also at 915MHz, but it is passed through the duplexer 756, the direction tap 840 and the band After the pass filter 876, the frequency of the uplink service is shifted to 1045 MHz by the mixer 884 using the synthesizer 838 with an output of 130 MHz. The frequency-shifted uplink service passes through a band-pass filter 892 set at 1045MHz+/-20MHz.

Similarly, the uplink service from the local coaxial distribution network 770 also starts at 915 MHz. After passing through the duplexer 758, the direction tap 856, and the band pass filter 880, the frequency of the uplink service is shifted to 1075 MHz by the mixer 888 using the synthesizer 844 whose output is 260 MHz. The frequency-shifted uplink service passes through a band-pass filter 896 set at 1075MHz+/-20MHz.

In the embodiment shown in FIG. 5, a single heterodyne frequency source set by the synthesizer is used for frequency shifting downlink and uplink signals. Therefore, for transmission in both directions, the number of frequency shifts will be the same. Instead, an independent heterodyne frequency can be used, thereby enabling a more flexible frequency scheme.

The systems described in FIGS. 5A and 5B use 915 MHz for uplink communication, and 980 MHz for downlink communication in the local coaxial distribution network (762, 766, and 770). As shown in FIG. 5B, a pair of frequencies transmitted on the feeder cable 624 are 915 MHz and 980 MHz, and this pair of frequencies is used by one of the local coaxial distribution networks 762 without frequency shifting. This reduces the extra set of components required to shift these signals. Although this is advantageous, it is not necessary, and all these frequency bands can be shifted without departing from the scope of the invention.

The band-pass filter included in FIG. 5B can be conveniently and economically manufactured using printed circuit board stripline components. Instead, other forms of filters such as ceramic or surface acoustic wave type filters may be used.

The adopted solution may have multiple local coaxial distribution networks using the same upstream or downstream frequency on the feeder cable 624, where the total traffic on the feeder cable does not exceed its load capacity for a given frequency. In this way, several local coaxial distribution networks can use the same feeder cable frequency as the feeder cable used in this local coaxial distribution network. One or more of the other local coaxial distribution networks will shift one or two of the communication frequencies to increase the load capacity of the feeder cable 624.

The described method can be used in a digital transmission system that utilizes any form of modulation or different forms of modulation on any part of a coaxial distribution system.

The subject and disclosed embodiments of the present invention are given in the context of data communication using genetic cable coaxial trees and branch networks. The frequencies selected for upstream and downstream communications reflect this environment. It should be noted that those skilled in the art can choose other frequencies or modulation schemes to implement the present invention, especially in any tree and branch network other than the coaxial network that is not used for distributing cable TV signals, or when not using Coaxial cable in the tree and branch network.

When the preferred embodiment is used in data communication related to the use of genetic cable coaxial trees and branch networks, the preferred embodiment uses frequencies above the useful frequency range of the local distribution network on the feeder cable (usually above 1.0 GHz). frequency). Those skilled in the art can use the teachings of the present invention to use an additional carrier frequency on the feeder cable to increase the bandwidth of the feeder cable by using frequencies below 1.0 GHz. Generally, there are hurdles that can be overcome in the use of these other frequencies. The frequency band from 5 to 42 MHz can be used, especially for the downstream frequency of an additional feeder cable, but this frequency band has many uses that change over time.

The frequency band set for the TV band is extended to 860MHz. Many systems do not use the frequency band from approximately 750 MHz to 860 MHz. This bandwidth can be used for additional feeder cable frequencies. The downward trend in using this frequency band is that cable TV providers in some areas may have already used the 750MHz to 860MHz frequency band, so this solution is not universally available. Another possible location for placing additional feeder cable frequencies is unused TV channels in the frequency band used for TV channels. Depending on the modulation and filtering equipment used to transmit the feeder cable frequency, it may be necessary to find some nearby unused TV channels in order to load a feeder cable frequency. The problem with the use of unused channels is that the cable provider re-arranges the channels used to transmit TV signals from time to time. When an unused TV channel becomes a valid TV channel, the rearrangement of the cable TV provider may cause a conflict with the plan to have an additional feeder cable frequency, requiring adjustment of the equipment to utilize a different frequency.

The frequency band of approximately 900 MHz to 1.0 GHz is another possible frequency band that loads additional feeder cable frequencies. As mentioned above, in the total signal power, and since the preferred embodiment has used 915MHz and 980MHz, in order to increase the additional feeder cable rate in this frequency band, there are possible problems in terms of the need for stricter filtering schemes. Although these factors point to the use of frequency bands above 1.0 GHz, the frequency band between 900 MHz and 1.0 GHz can carry three or more feeder cable frequencies instead of two feeder cable frequencies.

Those skilled in the art can realize that the method and device of the present invention have many applications, and the present invention is not limited to the specific examples given to promote the understanding of the present invention. In addition, as is clear to those skilled in the art, the scope of the present invention covers the scope of modifications, improvements and substitutions to the system components described herein.

The statutory limitations on the scope of the present invention are set forth in the appended claims extending to their statutory equivalents. Those who are unfamiliar with statutory tests for equivalents should consult with personnel previously trained in patent agencies such as the United States Patent and Trademark Office that granted this patent.