Apparatus and method for broadband data communication

[0002] The present invention relates to computer networks, and more particularly, but not by way of limitation, to a phone Local Area Network (LAN) for providing broadband data communication between network elements over a two-wire medium.

[0003] As prices for computers and peripherals decrease more homes and small business are increasing the number of computers and peripherals present in these computing environments. As the number of computers, peripherals, and other automated equipment, such as computerized home appliances, increases in the home or small business environments, it is increasingly important for such elements to be interconnected, for example, in a Local Area Network or LAN configuration. Interconnection allows hardware resources, such as printers, to be shared between a number of computers or accessed from many locations, allows high speed data transfer between devices, and further allows devices to be controlled remotely by other devices in the network.

[0004] Many high speed networking alternatives are available for large businesses but such alternatives require a large investment in networking resources. In contrast, choices for a home or small business network are limited by practical and economic factors such as the cost of the new wiring or cabling, especially given that utility wiring may already exist at the respective premises. It should be understood that the cost associated with rewiring a home to provide cable capable of carrying signals at network frequencies can be prohibitive.

[0005] Ethernet technology is commonly used in businesses for providing network connectivity, and has evolved into successively more robust forms over many years. One commonly used baseband Ethernet technology is known as the 10BASE-T network. The 10BASE-T network has an operating rate of 10 Mbps, is compliant with LAN 802.3 standards and specifications, and thereby provides moderate to high speed interconnectivity between many workstations and peripherals for most applications.

[0006] In a conventional business LAN application, workstations and peripherals, such as printers and disk towers, are wired together to allow shared access, data transfer, and communication between individual user workstations and network devices. A typical 10BASE-T network interface card (NIC) is located at each workstation and network device and accommodates two pairs of (category 5) unshielded twisted-pair wires. Under the 10BASE-T standard, one twisted pair is used for data transmission and another twisted pair is used for data reception. Due to the specialized nature of the interface circuitry and the common mode noise rejecting capability of the “twisted” configuration of the actual wire pair or, alternatively, the noise rejecting capability of shielded coaxial cable, relatively high data rates may be achieved. In the typical home, however, existing coaxial cables for cable TV service cannot be used to transmit data because of the resulting signal interference, and twisted wires pairs are unavailable. Accordingly, high data rate networks are not possible without expensive rewiring.

[0007] Some proposed solutions to home networking include standard modem technology, digital subscriber line (xDSL) technology, and wireless technology. Standard modem technology has traditionally been limited to data speeds of 56 kbps and requires very complicated circuitry and high quality line characteristics not readily available in a typical home. Although, xDSL technology can transmit data at a much higher rate than standard modem technology, the cost of implementation of xDSL is at present very high and requires very complicated modulation methods. High quality line characteristics, such as signal-to-noise ratio, may also be required with xDSL technology to meet theoretical objectives.

[0008] Wireless solutions allow for connectivity between elements, typically using frequencies around 900 MHz, but have certain drawbacks. Since wireless portable phones are often operated in neighboring bands, there is a high likelihood of signal interference between a wireless LAN and portable phones or household devices, such as televisions, computers, garage door openers, alarm systems, and the like.

[0009] Despite the many potential solutions to home and small business networking, problems arise in providing LAN type networking in view of the presence of existing customer premises traffic whether voice traffic, xDSL traffic, or both. In addition, the cost associated with independent wiring to accommodate LAN networking on the customer premises has been prohibitive.

[0010] Therefore, as can be appreciated, there is a need to provide LAN compliant home networking that is available at a low cost, and that can provide high data rates while taking advantage of existing four wire phone lines without disrupting existing traffic.

[0011] The present invention overcomes the above-identified problems, as well as other shortcomings and deficiencies of existing technologies, by providing a phone Local Area Network (LAN), including a phone HUB for routing LAN traffic between network elements within the customer premises and for routing analog and digital traffic from a Public Switched Telephone Network (PSTN) to network elements and telephone sets within the customer premises.

[0012] The phone hub of the present invention may be coupled between the PSTN and particular Customer Premises.Equipment (CPE). One or more network elements, each having a specially adapted network interface controller (NIC), are interconnected through the customer premises wiring plant and a router. Analog voice signals are transparently transferred from the PSTN to the customer premises wiring plant through the phone hub using a splitter, such that voice traffic in either direction is unaffected by the presence or the absence of digital data. Inbound digital data, advanced DSL or ADSL data for example, separated from voice signals at the splitter at a first frequency, is transported using the router at a second higher frequency to a specially adapted NIC at each network element. Outbound digital data at the first frequency is transported to the router at the second frequency by the specially adapted NIC. Outbound digital data transported at the second frequency may be frequency shifted by the router back to the first frequency for transport in the conventional manner over the PSTN.

[0013] The specially adapted NIC operates at broadband 10BASE-T Ethernet frequencies and can accommodate common telephone connectors, such as RJ-11 style connectors used in standard residential telephone communications. A Media Access Control (MAC) function of such a specially adapted NIC provides one fixed frequency channel, a frequency channel at a higher range, such as the range at 1 MHz above the ADSL range from about 2-3 MHZ would be occupied by 802.3 LAN traffic at 8 Mbps.

[0014] Standard telephone units are accommodated by the phone LAN in that standard RJ-11 style connectors and the customer premises wiring plant are used. The phone hub provides an interface between the local loop connection and the customer premises wiring. By plugging into, for example, the standard RJ-11 wall outlet, a standard telephone unit would receive the 4 KHz analog voice band channel routed transparently through the splitter for reception by any standard telephone unit of standard voice traffic whether or not phone LAN traffic was being processed at the higher frequency bands.

[0015] A more complete understanding of the present invention is made by reference to the following Detailed Description and appended claims when taken in conjunction with the accompanying Drawings wherein:

[0016] FIG. 1A is a block diagram illustrating an exemplary phone LAN;

[0017] FIG. 1B is a more detailed block diagram further illustrating an exemplary phone hub in accordance with the present invention; and

[0018] FIG. 2 is a graph illustrating the allocation of frequency bands for signals transported in an exemplary phone LAN in accordance with the present invention.

[0019] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. With reference now to FIG. 1A, there is shown a block diagram of a phone hub 100, which may provide Local Area Network or LAN routing for relatively high rate data communications between network elements, including various telephone sets 102 and a number of network elements, generally referenced by the numeral 103. It should be understood that network element 103 is so designated for the sake of simplicity, but may represent a variety of network elements, including a computer, a printer or peripheral, an automated home appliance, a modem, and the like. It should also be understood that the respective telephone sets 102 may each represent an analog voice telephone of the kind typically contemplated for subscriber service in a Digital Loop Carrier system.

[0020] Public Switched Telephone Service (PSTN), generally referenced by the numeral 101, is shown terminating at a Customer Premises Equipment (CPE) boundary 105 at a given customer premises, designated in outline form by the reference numeral 104. Phone hub 100 of the present invention may be connected between PSTN 101 and one or more network elements 103 and, optionally, a standard telephone set 102, as illustrated in FIG. 1A. As shown in greater detail in FIG. 1B, however, phone hub 100 receives signals from PSTN at voice band or a digital band, for example via ADSL, both of which require transport to their ultimate destination, which may be the telephone set 102 in the case of a voice band signal or the network element 103 in the case of a digital band signal. It should be understood that it is not inconsistent with the teachings of the present invention for both voice band and digital band signals to be received from the PSTN 105 and both processed in the phone hub 100.

[0021] To ensure that voice band signals are unaffected by the presence or absence of digital signals, a splitter 110 may incorporate ADSL MODEM functionality and may further integrate ADSL Transmission Unit Remote (ATU-R) functionality to split the voice band signals and ADSL band signals. As shown in FIG. 1B, voice signals are then routed transparently through a two wire plant 150 and to a number of connectors 122, which may be common connectors, such as RJ-11 connectors, as known in the art to be commonly used in household telephone outlets. Thus, any telephone set 102 may be connected to any connector 122 and receive normal voice band telephone service regardless of the presence of out of band signals, such as ADSL signals, and, as will be described hereinafter, LAN signals at LAN frequencies in accordance with the present invention. The splitter 110 may further route ADSL signals to a LAN router 120, which may be an intelligent router configured to transport ADSL data at a LAN frequency, through the two wire plant 150 and the connector 122 to a given network element 103A by way of a Network Interface Card (NIC) 130.

[0022] The NIC 130 may be a 10BASE-T Ethernet NIC specially adapted for use in the phone LAN of the present invention by being equipped with, for example, a standard RJ-11 style connector 131, as shown in FIG. 1B. Since the wiring in the two wire plant 150, in a residential or small business application, is within a reasonable range, e.g., not greater than 1 km, it is practical to transmit data, including frequency-shifted ADSL, at phone LAN frequencies throughout the customer premises using the phone LAN of the present invention. Conversion of frequency-shifted ADSL to baseband for transfer to the network element 103, which may be, for example, a personal computer system, may be accomplished using a specially adapted Media Access Control (MAC) 132.

[0023] The MAC 132 may be specially adapted for use in the phone LAN of the present invention. A first frequency channel may be provided by the MAC 132 using, for example, an ADSL module 133. The ADSL module 133 may decode data embedded in a LAN data packet received at the NIC 130 from the LAN router 120, convert it back into ADSL baseband, and pass the ADSL data to the network element 103 for processing if appropriate. A second higher frequency may be provided by LAN module 134 for data transfer to network element 103 at LAN frequencies. LAN data from any of the network elements 103 may be routed through the LAN router 120 to any other network element 103, for example, based on conventional LAN 802.3 addressing. The LAN router 120 is preferably an intelligent router capable of providing a bridge between ADSL protocol and a higher frequency LAN protocol used within the phone LAN of the present invention. Similarly, the LAN router 120 is preferably capable of converting ADSL, transported from network element 103 at LAN frequencies using LAN protocols, back to ADSL for transfer through the splitter 110 and back through the PSTN 101 to its ultimate destination, for example, an ATU-C located at a Central Office serving the customer premises 104.

[0024] With reference now to FIG. 2 of the Drawings, a graph is shown indicating the frequency bands occupied by signals transported in accordance with the present invention. Voice signals are shown occupying a voice band, generally designated by the reference numeral 220, a 4 KHz band between 4 KHz and 8 KHz, as is conventionally known in the art. A buffer zone 221 is shown as a 22 KHz buffer to provide isolation between the aforementioned voice band 220 and a digital band, generally designated by the reference numeral 210, which may be from around 30-300 kHz to provide digital signals ranging from 64-640 kbps, as might be used for example in ADSL. A second buffer zone 222 of about 1 MHz may be established from the upper boundary of the digital band 210 to the beginning of another digital band 200, which ranges from about 2 to about 3 MHz, as is shown in FIG. 2, and can accommodate digital signals ranging from around 8 Mbps, as is used, for example, in 802.3 LAN transport. It should be understood that, in accord with the preferred embodiment of the present invention, for example, voice signals within the voice band 220 may be transparently routed from the PSTN 101, shown in FIGS. 1A and 1B, through the phone hub 100, to the customer premises wiring plant 150 where a standard telephone set 102 may, if connected at one of the connectors 122, receive and transmit voice signals, which are unaffected by the presence of signals in the digital bands 210 and 200. Moreover, signals in digital band 210 may be separated in the splitter 110, coupled to the router 120, and transported through the router 120 in the digital band 200 in accordance with the invention as previously described for example, in reference to FIG. 1B of the Drawings.

[0025] Although a preferred embodiment of the present invention has been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it will be understood that the invention is not limited to the embodiment disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the spirit of the invention as set forth and defined by the following claims.