Abstract:
The Hi-SD CBS includes a termination unit and pluralities of distributed customer premise units connected through the cable TV (CATV) network. The radio signals in Hi-SD CBS are propagating inside the co-axial cable. To insure the linking quality between the termination unit and customer premise devices, preamble procedures are required to adjust the transmitting radio power, the receiver sensitivity, the channel equalization, and to synchronize the transceivers for data transmission between the termination unit and the customer premise devices. To guarantee a secure link between the termination unit and an individual customer premise device or a group of premise devices, the termination unit provides different encryption keys to different customer premise device groups.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates to a cable broadband system, and more particularly to a high-speed distributed cable broadband system (Hi-SD CBS) that employs access points (APs) and client devices in wireless local access network (WLAN) systems.  
         [0003]     2. Description of the Prior Art  
         [0004]     In a typical cable network system providing cable broadband service, a headend unit with Cable Modem Termination System (CMTS) unit and customer premise devices with cable modems are shown in  FIG. 1 . CMTS and cable modems apply the standard based on DOCSIS. The downstream data from CMTS to a customer premise applies the upper band of frequencies up to 900 MHz, while the upstream data from a customer premise device to CMTS applies the lower bands of the frequency channels. The typical downstream and upstream bandwidths are 27 Mbps, and 500 Kbps to 10 Mbps depending on the service level agreement, respectively. Typical 500 to 2000 active subscribers in a cable network segment share the downstream and upstream bandwidths.  
         [0005]     Referring to  FIG. 1 , the cable headend  100  distributes the TV program and data communication to customer premises  108 . The cable headend  100  comprises a backplane  101  electrically connected an internet  102 . In general, the backplane  101  is made of a PCB to provide a connection by controlling cards, such as display card, audio card or network card, of an electrical system. Moreover, the backplane  101  may be designed with a fiber channel to communicate with the internet  102  with fiber transmission. A receiver  103  is electrically connected with the backplane  101  to receive a TV broadcasting  104  signals. A transmitter module  105  is electrically connected with the backplane  101  to transmit the TV broadcasting  104  signals. CMTS  106  connects with the customer premise  108  through a cable network  107 . Besides, MPEG module  109  is electrically connected with the backplane  101 . In general, the MPEG module  109  comprises a MPEG encoder and a MPEG decoder. A web server  110  is electrically connected with the backplane  101  to communicate with the internet  102 . A video server  111  is electrically connected the backplane  101  to process the received TV broadcasting  104  signals. A statmux port concentrator  112  is electrically connected the backplane  101  to optimize the data flow. The customer premise  108  may comprise a set top box  113  and a cable modem  114 .  
         [0006]     Due to the fast growth and technology advance in WLAN system, the performance of WLAN systems has been improving dramatically in recent years, while the cost for WLAN systems remains a good economic value. Besides its success in Small Office and Home Office (SOHO) areas, WLAN technologies have further been applied to enable the wireless environment in different applications such as public communications, surveillance systems, voice services, and video services. It is specially appreciated that with its low cost, various functionalities, and high performance, WLAN system is the first time to be applied in cable TV network systems. The proposed High-Speed Distributed Cable Broadband System (Hi-SD CBS) using WLAN-like systems provide a very attractive and competitive alternative for high-speed cable broadband service besides the conventional cable modem systems.  
         [0007]     In view of the aforementioned, the present invention provides a system and method for High Speed Distributed Cable Broadband System to overcome the above drawback.  
       SUMMARY OF THE INVENTION  
       [0008]     This invention relates to systems and methods to enable high-speed broadband service in cable TV networks. In particular, High-Speed Distributed Cable Broadband System (Hi-SD CBS) consists of termination devices and customer premise devices similar to access points and client devices in Wireless Local Access Network (WLAN) systems, respectively. The radio signals from the termination device and customer premise devices are directly fed into the co-axial cables in cable TV network systems in contrast to the radio signals propagating in the air between access point and client devices in WLAN systems. All the ideas and technologies designed for WLAN systems such as hardware and software protocols for network management, security, and Quality of Service (QoS) can be sufficiently applied to the proposed High-Speed Distributed Cable Broadband System (Hi-SD CBS).  
         [0009]     The main objective of the present invention is to provide a high-speed distributed cable broadband system (Hi-SD CBS) that employs access points(APs) and client devices in wireless local access network (WLAN) systems. The present invention proposes an innovative high-speed distributed cable broadband system similar to those using WLAN technologies. The proposed system applies the access point and client devices as the CMTS and cable modems in the conventional cable broadband network systems, respectively.  
         [0010]     Another objective of the present invention is to provide the Hi-SD CBS based on the system infrastructure of wireless local access network (WLAN).  
         [0011]     The yet objective of the present invention is to provide the Hi-SD CBS with lower propagating loss.  
         [0012]     The further objective of the present invention is to provide the Hi-SD CBS with larger reachable propagating range.  
         [0013]     The radio signals propagate through the entire cable networks to make links between the access point and client devices. Although there is some amount of radio signal loss propagating along co-axial cables the propagating loss is far less than those radiating from devices&#39; antennas in wireless environments. The network reachable range in cable network system shall be larger than in wireless environments.  
         [0014]     The Hi-SD CBS of the present invention comprises a termination unit having a first network bridging device, a plurality of second network bridging devices connected with the first network bridging device through a cable network, and a customer premise unit connected to the second network bridging device through the cable network. The customer premise unit, the first network bridging device and second network bridging device are communicated with each other through a communication protocol.  
         [0015]     The termination unit further comprises a backplane electrically connected with an internet. A receiver is electrically connected with the backplane to receive a TV broadcasting signal. A transmitter module is electrically connected with the backplane and second network bridging device to transmit the TV broadcasting signal. A MPEG module is electrically connected with the backplane. A video server is electrically connected the backplane to process the received TV broadcasting signal. A web server is electrically connected with the backplane to communicate with the internet. A statmux port concentrator is electrically connected the backplane.  
         [0016]     The first and second network bridging devices comprise an AP, bridge or router. The transmitter module comprises a transmitter and a modulator. MPEG module comprises a MPEG encoder and a MPEG decoder. The customer premise unit comprises a set top box and client device. The client device comprises a PC connected the set top box.  
         [0017]     Based on the spirit of the present invention, the present invention provides a high-speed distributed cable broadband system (Hi-SD CBS). The Hi-SD CBS comprises at least one client device connected with an AP through a cable network. A modem is connected with the AP and an internet through the cable network. The client device and the AP are communicated with each other through a communication protocol. The modem comprises a broadband modem or leased lines.  
         [0018]     A Hi-SD CBS comprises first client device, second client device having a short-range wireless transmission module to transmit or receive the radio signals, and an AP connected with the first client device and the second client device through a cable network. The AP is connected with an internet through the cable network. The first, second client device and the AP are communicated with each other through a communication protocol.  
         [0019]     The short-range wireless transmission module transmit the radio signals to facilitate receiving by the second short-range wireless transmission module of another client device, and the short-range wireless transmission module may receive a radio signals emitted by the second short-range wireless transmission module. Another client device is communicated with the second client device through a communication protocol.  
         [0020]     A cable network system comprises one or more client devices having a short-range wireless transmission module, and an AP connected with the one or more client devices through a cable network. The AP is connected with an internet. The one or more client devices and the AP are communicated with each other through a communication protocol.  
         [0021]     A cable network system comprises one or more client device groups. An AP is connected with the one or more client device groups through a cable network. A gateway is connected with the AP and a local network. A security server is communicated with the AP through the gateway. The one or more client device groups and the AP are communicated with each other through a communication protocol. The one or more client device groups can be secured and isolated by sending out different encryption keys from the AP. The local network comprises WAN, MAN or LAN. The cable network system further comprises a switch connected with the AP and the gateway.  
         [0022]     In the present invention, links between the client device and the AP are through a preamble sequences to adjust the transmitting radio power, the receiver sensitivity, and channel equalization, and to synchronize the transmitter and the receiver for data transmission between the client device and the AP.  
         [0023]     The communication protocol comprises 802.3 and 802.11 including but not limited to, 802.11a, 802.11b, 802.11g, 802.11i or 802.11x. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     The above objects, and other features and advantages of the present invention will become more apparent after reading the following detailed description when taken in conjunction with the drawings, in which:  
         [0025]      FIG. 1  illustrates cable TV network systems with conventional cable modems providing both TV service and cable broadband service.  
         [0026]      FIG. 2  illustrates a wireless local access network system.  
         [0027]      FIG. 3  illustrates two clusters of WLANs with wireless bridges aggregating into an AP to Internet.  
         [0028]      FIG. 4  illustrates an AP and several client devices connected to nodes of a cable TV network system.  
         [0029]      FIG. 5  shows the propagation loss for length of 100 meters for different co-axial cables versus radio frequencies.  
         [0030]      FIG. 6  shows a 2.4 GHz radio signal propagating before and after 100 meters of RG-58 co-axial cable.  
         [0031]      FIG. 7  illustrates a client device and an AP sending preamble sequences.  
         [0032]      FIG. 8  illustrates the security and network management system implemented in Hi-SD CBS.  
         [0033]      FIG. 9  illustrates a large cable operator system with cable headend and customer premise.  
         [0034]      FIG. 10  illustrates a small or a medium size of Hi-SD CBS applied to a cable TV network systems.  
         [0035]      FIG. 11  illustrates the client devices in Hi-SD CBS can be used as an AP client device to provide wireless connection in the customer premise site. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0036]     The present invention proposes an innovative High-Speed Distributed Cable Broadband System (Hi-SD CBS). Although we illustrate the proposed embodiment using 802.11 WLAN systems, the applications of the proposed technologies are not limited to different frequency bands and varieties of communication methods.  
         [0037]     The matched impedance connectors increase the transmitting radio signals into co-axial cable system and reduce the reflective radio signals back to the transmitting devices. The radio signals propagate through the entire cable networks to make links between the access point and client devices. The cables in the network act like extended ultra-high gain antennas inter-connected between access point and client devices as shown in  FIG. 2 .  
         [0038]     While CMTS and cable modems currently provide all the broadband services in cable TV network systems, we propose another alternative for the cable broadband service based on the system infrastructure of Wireless Local Access Network (WLAN). The typical WLAN System consists of an access point and several client devices ( FIG. 2 ) or plural access points and clusters of client devices bridging between clusters or aggregating from clusters ( FIG. 3 ). The radio signals in WLAN systems are propagating through air. In this newly proposed cable broadband system, we feed the radio signal direct into the cable TV network to form a distributed cable broadband system as shown in  FIG. 4 .  
         [0039]     The proposed system of the present invention applies the access points (APs) and client devices as the CMTS and cable modems in the conventional cable broadband network systems, respectively. In other words, the present invention proposes an innovative high-speed distributed cable broadband system (Hi-SD CBS) that may provide a cable broadband service for conventional cable TV network system. The access point (AP) is an entrance device to provide a short-range wireless transmission device (computer or personal digital assistance phone) connecting a network.  
         [0040]     The radio signals propagate through the entire cable networks to make links between the access point and client devices. Although there is some amount of radio signal loss propagating along co-axial cables the propagating loss is far less than those radiating from devices&#39; antennas in wireless environments. The network reachable range in cable network system shall be larger than in wireless environments. The communication protocol between the client device and the AP comprises 802.3 and 802.11 including but not limited to, 802.11a, 802.11b, 802.11g, 802.11i or 802.11x.  
         [0041]     Referring to  FIG. 2 , it illustrates a wireless local access network system. Client devices  122  in the coverage range are communicated wirelessly with a short-range wireless transmission module  121  of an access point  120  through short-range wireless transmission module  123 . The access point  120  may connect an internet  124 , such as Ethernet, to act like an entry point to access Internet for client users. In other words, the client devices  122  may transmit or receive data through the internet  124 . The radio outputs of access point and client devices are replaced with impedance matched cable connectors. The proposed Hi-SD CBS applies the modified 802.11 WLAN access point and client devices as the CMTS and cable modems in the conventional cable broadband network systems, respectively. Referring to  FIG. 3 , it illustrates two clusters of WLANs with wireless bridges aggregating into an AP to Internet. In the first cluster, client devices  132  in the coverage range are communicated wirelessly with a short-range wireless transmission module  131  of a network bridging device  130  through short-range wireless transmission module  133 . As the same, in the second cluster, client devices  139  in the coverage range are communicated wirelessly with a short-range wireless transmission module  138  of a network bridging device  137  through short-range wireless transmission module  140 . Moreover, the network bridging device  130 ,  137  may be communicated wirelessly with a short-range wireless transmission module  135  of a network bridging device  134  through short-range wireless transmission module  131 ,  138 , respectively. In one embodiment, the network bridging device  130 ,  134  and  137  comprise an access point (AP), bridge or router. The access point  134  may connect an internet  136 , such as Ethernet, to act like an entry point to access the Internet  136  for client devices  132 ,  139 . In other words, the client devices  132 ,  139  may transmit or receive data through the internet  136 .  
         [0042]     Referring to  FIG. 4 , it is an AP and several client devices connected to nodes of a cable TV network system. Client devices  141  are connected with an AP  143  through node  144  of a cable TV network  142 . The node  144  is an example. The access point  143  may connect an internet  145 , such as Ethernet, to act like an entry point to access the Internet  145  for client devices  141 . In other words, the client devices  141  may transmit or receive data via the access point  143  through the internet  145 . Furthermore, the client devices  141  may receive the transmitted data from the internet  145  through the cable TV network  142 . The radio signals from the AP  143  and the client devices  141  are propagating in the cable network system. Here, the cables act like the extended antennas with ultra-high gains along the cable propagation directions.  
         [0043]     Referring to  FIG. 5 , it shows the propagation loss for length of 100 meters for different co-axial cables versus radio frequencies. The propagation loss increases with higher frequency for a fixed cable length of 100 meters. Due to much less radio signal loss propagating along co-axial cable network systems than the path-loss in wireless environments, the transmitting distance along a co-axial cable from a transmitter to a designated receiver in a cable network is much longer than the distance from a transmitter radiating radio signal to a designated receiver. The co-axial cable for the radio signal can be considered as extended ultra-high gain antennas to inter-connect the termination device and customer premise devices in cable network systems. The antenna gains are very high along with the cable propagation directions. A typical signal loss propagating in 100 meters versus different cables and radio frequencies is shown in  FIG. 5 . The frequency bands 2.4 GHz-2.48 GHz and 4.9 GHz-5.9 GHz used for 802.11 b/g and 802.11a shall be able to propagate significant distances along the cable network. With auto gain control (AGC) and high receiver sensitivity, the signal dynamic range for 802.11 WLAN receivers can be as large as 70 dB. This indicates that 802.11 transceivers shall be able to adapt wide range of radio signal strengths for complicated cable network systems. The WLAN systems are more tolerated to various cable network environments.  
         [0044]     Referring to  FIG. 6 , it shows a 2.4 GHz radio signal propagating before and after 100 meters of RG-58 co-axial cable. Since radio environments are more stable in cable network systems than in complicated wireless environments, the issues associated with interference and multi-paths are less severe and easier to control in cable network systems. Thus the planning for network system is easier to achieve in cable systems.  
         [0045]     Referring to  FIG. 8 , it illustrates the security and network management system implemented in Hi-SD CBS. The security between access point and client devices is accomplished by providing an encryption key to a group of logistic client users (or a single user). Network management software can be installed to control each individual client user to guarantee the quality of service according to access privilege, priority, and data flow. Client devices  800 ,  802 ,  804  and  806  of different user groups can be secured and isolated by sending out different encryption keys  801 ,  803 ,  805  and  807 , respectively from AP  808 . The client devices  800 ,  802 ,  804  and  806  are communicated with the AP  808  through a cable TV network  809 . The AP  808  can pass the user information and receive instructions from a gateway  811  and security server  812 . Moreover, a switch  810  may connect with the AP  808  and the gateway  811  to control the data flow among the AP  808 , the gateway  811  and security server  812 . The AP  808  can pass the information and receive instructions from the gateway  811  or an AAA server (Authentication, Authorization, Accounting)  812 , as shown in  FIG. 8 . The gateway  811  is connected with a local network  813 . In one embodiment, the local network  813  comprises WAN, MAN or LAN.  
         [0046]     The client devices  800 ,  802 ,  804  and  806  are communicated with the AP  808  through a communication protocol. For security, the 802.1x and 802.11i protocols implemented in WLAN can be applied to this Hi-SD CBS without significant modification.  
         [0047]     Referring to  FIG. 9 , it illustrates a large cable operator system with cable headend and customer premise. In one embodiment, a network bridging device  901  comprises an AP, bridge or router. The cable headend  900  comprises a backplane  902  electrically connected an internet  903 . In general, the backplane  902  is made of a PCB to provide a connection by controlling cards, such as display card, audio card or network card, of an electrical system. Moreover, the backplane  902  may be designed with a fiber channel to communicate with the internet  903  with fiber transmission. A receiver  904  is electrically connected with the backplane  902  to receive a TV broadcasting  905  signals. A transmitter module  906  is electrically connected with the backplane  902  and a network bridging device  907  to transmit the TV broadcasting  905  signals. The network bridging device  907  is connected to a customer premise  909  through the cable network systems, while the other ports of the network bridging device  907  are connected to either optical fiber backbone or a satellite link. In one embodiment, the network bridging device  907  comprises an AP, bridge or router. The APs/Bridges  907  in between the cable headend  900  and the customer premise  909  illustrate the relay for large cable network. Besides, MPEG module  910  is electrically connected with the backplane  902 . In general, the MPEG module  910  comprises a MPEG encoder and a MPEG decoder. A web server  911  is electrically connected with the backplane  902  to communicate with the internet  903 . A video server  912  is electrically connected the backplane  902  to process the received TV broadcasting  905  signals. A statmux port concentrator  913  is electrically connected the backplane  902  to optimize the data flow.  
         [0048]     The customer premise  909  may comprise a set top box  914  and a client device  915 . The client device  915  comprises a PC connected the set top box  914 . The customer premise  909  and the AP  901 ,  907  are communicated with each other through a communication protocol.  
         [0049]     Referring to  FIG. 10 , it illustrates a small or a medium size of Hi-SD CBS applied to a cable TV network systems. The small or medium size of Hi-SD CBS may be applied to those used in motels or hotels. The WAN ports of the AP/router device  920  are connected to a leased line or a broadband modem  923 , while the radio signal port is connected to the cable end in the existing cable TV network systems  922  distributed to different rooms and locations. The AP  920  connected to either a broadband modem or a leased line  923 , provides the Internet  924  entry point for client devices  921  through the cable TV network systems  922 . The broadband modem or leased line  923  is connected with the Internet  924 . The radio signal ports of the client devices  921  are connected to the output nodes of the distributed cable TV network  922 . To access the broadband network, a computer device can be connected or coupled to the client device  921  either by an Ethernet LAN port or a UBS port. The AP  920  is communicated with the client devices  921  through a communication protocol.  
         [0050]     Referring to  FIG. 11 , it illustrates the client devices in Hi-SD CBS can be used as an AP client device to provide wireless connection in the customer premise site. In this embodiment, the client devices  930  having short-range wireless transmission module may provide an entry point to access another wireless client devices  932 , as shown  FIG. 11 . In other words, the short-range wireless transmission module  931  of the client devices  930  transmit the radio signals to facilitate receiving by the short-range wireless transmission module  933  of another client devices  932 , and the short-range wireless transmission module  931  may receive a radio signals emitted by the short-range wireless transmission module  933 . Moreover, client devices  934  are without short-range wireless transmission module. In another aspect of the Hi-SD CBS, the client device can support a cable client device and wireless access point at the same time. In one end, the client devices  930  make the Internet  937  link through the cable TV network  936 , while on the other end, it can provide the wireless access point in the client sites  932 . It is also appreciated that, in different aspects of this Hi-SD CBS, the different radio frequency bands and various communication protocols are applied in the system, and the varieties of different uplink and downlink network systems are connected to Hi-SD CBS. An AP  935  is connected with the client devices  934  and the client devices  930  through a cable TV network  936 . The AP  935  is connected with the internet  937  through the cable TV network  936 . The client devices  930 ,  934  and the AP  935  are communicated with each other through a communication protocol.  
         [0051]     Referring to  FIG. 7 , it illustrates a client device and an AP sending preamble sequences. In different aspects of this Hi-SD CBS, an AP  700  is connected with client devices  701  through a cable TV network  703 . With the cable connection between access point  700  and client devices  701  in distributed cable TV network systems, the links between access point  700  and each individual client devices  701  can be established by several preamble sequences to adjust transmission power and receiving sensitivity, channel selection, and channel equalization and to synchronize transceivers between the client device  701  and AP  700 , as illustrate in  FIG. 7 . To improve the pre-amble efficiency and ready for transmission with the client device  701 , the access point  700  may poll the cable network conditions from all the client devices  701  and store the link condition information in memory for data transmission. After establishing the links between access point  700  and client devices  701 , the data packets is ready to transmit and receive for client devices  701  throughout the cable network system  703 . As the same, the access point  700  is connected with an internet  702 .  
         [0052]     Since the cable TV network systems are designed for its original frequency bands for TV channels, the conventional boosters and some highly isolated splitters in the cable TV network systems prevent other frequency bands passing through. Splitters before those components (boosters and highly isolated splitters) are introduced to separate the radio frequencies bands in different paths. The splitter is designed to allow the TV band to pass the original components, while the other frequency bands pass through other path without letting the TV channel frequency bands through. A combiner is used to re-joint the two frequency bands back to the co-axial cable network systems.  
         [0053]     As in 802.11 WLAN systems, AP and client devices are sending out beacons through the entire cable network. A preamble sequence is applied between AP and a client device to adjust the transmitting radio power and the receiver sensitivity, and to synchronize the two transceivers. In the signal header, it determines the different PHYs used for this transmission, that is, different CCK for 802.11b or OFDM for 802.11g and 802.11a. Depending the link quality between AP and client, different transmission rates, 11 Mbps, 22 Mbps, 33 Mbps, 54 Mbps, and 108 Mbps, can be applied for the data transmission in the link. To avoid the interference between different links in the shared cable network systems, channel management can be applied to minimize the contention and more effectively to manage the communication traffic. For examples, some channels can be reserved for particular links according to priority, data flow, and their applications.  
         [0054]     In summary, the present invention proposed an innovative Hi-SD CBS for cable broadband service in existing cable TV network systems. The Hi-SD CBS is based on the system infrastructure of Wireless Local Access Network (WLAN). Due to the fast growth and technology advance in WLAN systems, Hi-SD CBS can become a very attractive and competitive alternative for high-speed cable broadband service in cable TV network systems besides the conventional cable modem systems.  
         [0055]     Although specific embodiments have been illustrated and described, it will be obvious to those skilled in the art that various modifications may be made without departing from what is intended to be limited solely by the appended claims.