COMMUNICATIONS WEB FOR PSTN SUBSCRIBERS
FIELD OF THE INVENTION The present invention is related to a system for interconnecting several devices and, more particularly, to a system for wirelessly interconnecting telephony devices and computers.
BACKGROUND OF THE INVENTION Demand for access to voice and data communications on the public switched telephone network ("PSTN") is growing exponentially. Not only is the subscriber base expanding logarithmically, but even more significantly, individual subscribers are beginning to require more than one number and frequently multiple numbers. In addition to cellular telephones, pagers, and other mobile devices, home-based connectivity is a significant factor in this exponential growth of the PSTN. Subscribers have begun in recent times and in significant volume, to require second and third lines as a matter of course, such as for Global Information Infrastructure (so-called "Internet") connectivity and data commumcations and for childrens' lines.
Although it is conventional for a residence to contain standard telephony devices in various rooms supported by one line and perhaps a computer supported by another, the days of standard analog "plain old telephone service" or "POTS" are waning as demand for bandwidth to support graphics, interactive technology and the' so-called "push technology" on computer devices grows. In 1995, for instance, the Regional Bell Operating Companies ("RBOC's") began transporting more data than voice communications. Accordingly, not only are subscribers employing more lines; the nature of the connection is also changing. The rate of change will only increase over time. The increased demand for residential subscriber lines, and the ever changing nature of those lines as new standards are developed in order to accommodate new and different services, occur in the face of a major residential constriction: wiring of the residence. Standards such as ADSL aim to minimize that problem by delivering multiple channels on a single line and splitting analog and digital channels at the customer demarcation point in a manner that allows digital signals to be delivered in the vicinity of
the computer. That paradigm is compromised as, inevitably, subscribers require computers and other connected electronic devices throughout the residence. These devices will not only resemble computers or televisions in nature, they may be any electronic device one wishes to access remotely. The anticipated 128-bit Internet protocol address format will, it is estimated, accommodate every lightbulb in the world.
Presently, however, most residences feature only single twisted pair wiring in the walls. Rewiring for additional lines throughout the house, whether via today's twisted pair or perhaps coax standard, is trouble and expense enough, and a great disincentive which constricts demand for increased residential bandwidth. As time passes and the rate of technology change increases, however, subscribers could find themselves needing to rewire every several years in order to accommodate changing standards and increasing bandwidth.
These factors create a need for connectivity in the residence between the PSTN customer demarcation point and telephones, computers, fax machines, and any other device which may be connected to the PSTN or feature an IP address. Such connectivity must suffice not only for today; it must alleviate the need to rewire the residence in order to accommodate new changes, it must accommodate new devices, formats, protocols and standards, whether analog or digital, and it must be flexible and modular in design in order to accommodate a wide-ranging set of needs and preferences among the subscriber base. As more peripherals enter the home, the interconnectivity of these peripherals becomes more important.
Interconnectivity poses additional problems, however, such as bandwidth limitations. The bandwidth problem originates from the fact that the telephone systm was designed and put in place before computers became widely used. The telephone system in use today was originally designed for the use of voice only. By limiting the spectrum to just those frequencies relevant to human speech, the industry reduced the bandwidth of each channel to 3.1kHz, thereby increasing the number of potential simultaneous channels or calls. That bandwidth limitation has recently become significant in the face of demand for broader band communications including graphics, video and high fidelity audio. In his seminal Bell Labs Paper "A Mathematical Theory of Communication,"
Claude Shannon recognized that the theoretical maximum rate for error-free data communication (i.e., a defined bandwidth channel with noise present) over a telephone
line is approximately 35K bps, depending upon the telephone link. Thus, sampling at a rate higher than 8 Khz is unnecessary, and that sampling rate has become industry standard. Indeed, sampling faster than 8K leads to little or no improvement in the face of the 3.1kHz bandwidth limitation. Systems of the present invention, by virtue of their connection to the telecommunications network through a Network Control Unit, and from there interconnection to a number of other devices through a digital radiofrequency link, present a need for proper matching and compensation to accommodate line loss in the telecommunications network and other errors. For instance, if analog signals from the telecommunications network were encoded and digitized in systems according to the present invention using standard mu-law encoding, there is the possibility of quantization offset error (which can be analogized to dc offset in an analog system) and gain offset due to improper matching of the line-card generated maximum and the maximum generated by the applicable codec in the system's network control unit. Although quantization offset may be relatively small, gain offset may be more significant. Gain offset could perhaps be minimized by measuring and compensating for its major component, line loss. Line loss can be at least partially compensated for according to one straightforward method by measuring loop current and applying a gain value that is inversely proportional to current. Some current modems employ such techniques, and older equipment occasionally employed a series varistor for such purposes, although gain compensation circuitry does not appear to be widely employed, if employed at all, in cordless telephones.
Designers of recent 56K modems rely on filtering and leverage on the fact that switched capacitor or digital post conversion reconstruction filters in a standard codec operate in a highly predictable manner. That is, although they introduce considerable interference into an incoming digital 56K signal, the interference is precise and predictable. However, routing the signal through two codecs in series as is required in the present invention on either side of the radiofrequency link, would create not only gain mismatch and quantization offset, but also an additional stage of quantization noise plus echo and therefore cause serious degradation and perhaps ultimately a fall back to a lower data rate.
SUMMARY OF THE INVENTION
Systems according to the present invention feature a Network Control Unit or Web Control Unit ("NCU") which interfaces to any desired number of PSTN lines. Where the lines are analog, a Network Interface in the NCU digitizes the signals and otherwise renders them compatible for delivery to a cross-connect switch / conference bridge / accessory block ("CAB") module which may be programmed in the residence or remotely to connect signals from each line to any predetermined combination of telephony, computer, or other electronic devices in the residence. The CAB is coupled to a radio multiplex engine which multiplexes the signals for bandwidth efficiency and other purposes, and delivers them to an NCU Radio Transceiver for delivery via RF link, which may also be multiplexed if desired, throughout the residence.
At the other end of the RF link, the system features handsets and/or Wireless Access Units or "wireless jacks." The handsets include a transceiver, multiplex / demultiplex circuits, analog / digital conversion circuits such as so-called "codec's" and control circuitry with a combination of, for instance, microphone and earphone for voice communications, and perhaps a jack for data communications. The Wireless Access Unit contains circuitry similar to the handset in analog environments, plus additional circuitry for delivery of the signal to a standard interface such as an RJ-11 jack. Such Wireless Access Units can be made available, according to the present invention, to accommodate any physical and electrical interface standard, such as Wireless Access Units for ISDN interfaces and any other desired digital services.
Accordingly, the PSTN lines may terminate in the residence at a Network Control Unit which may be physically small and innocuous in appearance, perhaps mounted on a wall and, if desired, coupled to a nearby electrical outlet and to a personal computer or other interface if the user desires control other than by interfaces on the Network Control Unit itself. The unit may feature a stub antenna or other desired antenna. Throughout the residence, any device desired to connect to the PSTN can contain its own Wireless Access Unit which may be battery powered and connect to the NCU via RF link.
The present invention accordingly makes possible wireless, efficient, flexible and modular connectivity between any desired device and the PSTN within the residence. The Network Control Unit itself may be modular in design to accommodate various circuit boards for various changing and evolving standards and protocols. New Wireless
Access Units may be purchased for whatever particular devices a particular subscriber desires, and he or she may update the system with new circuit boards and new Wireless Access Units and perhaps new handsets as time passes, new devices and services evolve, and standards change. In order to compensate for line loss, mismatch and other incompatibilities between the public telecommunications network on the one hand and systems according to the present invention which convey signals to a number of devices over a digital link and thus require two stages of conversion, the present invention employs an encoding process that differs from standard American mu-law encoding techniques. According to one paradigm, the new encoding techniques according to the present invention can be considered a superior implementation of a low pass reconstruction filter using digital signal processing techniques. These techniques allow the signal to continue to be sampled at an 8K rate with low or no distortion.
Encoding techniques according to the present invention employ 6 amplitude bits, 3 chord bits and 1 sign bit, as compared to the 4 amplitude bits, 3 chord bits and 1 sign bit characteristic of mu-law encoding. Sampling is performed at an 8K or higher rate. The resulting 16 bit performance yields a subjective ~90dB signal to noise ratio over the radiofrequency link of systems of the present invention. Such encoding techniques and 10 bit code segments can easily be accommodated by present processing capacity. Another encoding technique employes 16-bit linear quantization and 16 kHz or higher sampling rate, twice or more the conventional 8 kHz sampling rate. After this oversampling, the signal is decimated to a lower sampling rate prior to transmission over the wireless media. This minimizes the aggregate bit rate over the air, and preserves wireless link margin and system performance by maximizing the amount of energy per bit.
- ^To reproduce the signal, the decimated signal may be converted back into analog form, processed through a reconstruction filter, and passed to a 4-wire to 2-wire hybrid and coupled out to the RJ-11 connector of the wireless access jack. The decimated signal may also be interpolated back up to 16 kHz or higher in order to make the reconstruction filtering simpler, more practical, or more economical.
An echo canceller may also be employed with either of the above-mentioned encoding techniques to mimmize near-end echo and thereby improve performance. Since
the circuit from the hybrid at the PSTN connection to the hybrid at the access jack is a four-wire wireless circuit, the echo canceller may be located at either end of the circuit. The echo canceller may be fixed with preset coefficients that are calibrated to a given line condition or adaptive to automatically correct for variations in line conditions. It is an object of the present invention to provide business and residential wireless connectivity between the PSTN and computers, handsets, and other devices which eliminates the need to rewire businesses and residences in order to accommodate new standards and services.
It is an additional object of the present invention to provide RF based connectivity between any number of PSTN lines and any number of now existing or future electronic devices, in a modular and flexible manner.
It is an additional object of the present invention to provide a flexible, modular, system which provides connectivity between the PSTN and any desired electronic devices a subscriber wishes to connect, via RF link. It is an additional object of the present invention to provide such systems that accommodate line loss, mismatch and other incompatibilities with the public telecommunications network in a manner that does not require analog gain control techniques, synchronization to a system clock, but which yields excellent signal to noise ratios and signal quality across the digital radiofrequency link. It is an additional object of the present invention to provide such systems that implement a reconstruction filter with expanded quantization segments in order to provide enhanced audiofidelity performance within the systems and simultaneously to accommodate incompatibilities with the public telecommunications network.
It is an additional object of the present invention to provide such systems which use encoding featuring expanded quantization segments in order to provide signal quality that ensures compatibility with multiplexing techniques according to which such signals are transported on radiofrequency links according to the present invention.
It is an additional object of the present invention to provide new techniques for encoding a signal to be conveyed on a wireless link in a manner that ensures superior sound quality at high data rates, while maintaining compatibility with the traditional 3.1kHz bandwidth and 8K sampling rate standards.
Other objects, features and advantages of the present invention will become apparent with respect to the remainder of this document.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of a residence which features one embodiment of a system according to the present invention.
Figure 2 is a schematic, greatly simplified, representation of a Time Division
Multiplex Access ("TDMA") frame having eight slots supporting four bi-directional channels in accordance with one embodiment of the present invention. Figure 3 A is a high level functional block diagram of a Network Control Unit according to one embodiment of the present invention.
Figure 3B is a schematic diagram, at a lower level than Figure 3 A, of a Network
Control Unit according to one embodiment of the present invention in which four coder / decoder or "codec's" are employed in connection with four analog POTS lines. Figure 3C is a functional block diagram of a single codec which may accommodate the four lines, for instance, shown in Figure 3B as an alternative design for purely analog POTS lines.
Figure 4 is a functional block diagram of one embodiment of a handset according to the present invention. Figure 5 is a functional block diagram of one embodiment of a Wireless Access
Unit according to the present invention.
Figure 6 is a functional block diagram of a Network Control Unit which is adapted to accommodate the ISDN standard, alone or in connection with other analog PSTN connections. Figure 7 is a functional block diagram of a Network Control Unit according to the presentinvention adapted to accommodate three analog and one digital PSTN connections.
Figure 8 is a functional block diagram of one embodiment of a digital Wireless
Access Unit according to the present invention. Figures 9A and 9B are functional block diagrams as one embodiment of switching
/ processing circuitry contained in one embodiment of a Wireless Access Unit or handset according to the present invention.
Figure 10 is a high level functional block diagram of transceiver circuitry which may be employed in the present invention if desired.
Figure 11 A is a simplified flow diagram illustrating one configuration sequence of the Network Control Unit of Figure 3. Figure 1 IB is a table showing configuration of the Network Control Unit of
Figure 3 resulting from the configuration sequence shown in Figure 11 A.
Figures 12A and 12B are schematic diagrams showing operation of a communications web according to the present invention according to Example 1 discussed below. Figures 13A and 13B are a schematic diagrams showing operation of another communications web according to the present invention according to Example 2 discussed below.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 1 is a schematic hypothetical floor plan for a residence or business containing a communications web according to the present invention. The floor plan shows a Network Control Unit or "NCU" 100 which terminates four central office POTS lines designated "CO1" through "CO4." A number of Wireless Access Units or wireless jacks ("WAU's") 201 - 203 may be found throughout the floor plan, linked via RF link to the NCU. Additionally, a number of handsets and conventional telephones 300 - 304 whether portable or connected to a WAU may also be found throughout the floor plan. Other electronic devices such as a fax 400 may be included; fax 400 in Figure 1 is shown connected to a WAU 202.
Any number of PSTN lines or connections may terminate in one or more NCUs for a particular location according to the present invention. The PSTN lines may be analog-or digital, and may incorporate any desired present or future analog or digital standard, format or protocol. Similarly, WAUs according to the present invention, which may be RF linked to one or more NCUs for a particular location, can be adapted to accommodate any telecommunication, consumer electronic or other required standard, format or protocol, whether analog or digital and can be manufactured and sold individually for that purpose to render commumcations webs according to the present invention modular in nature with a mix of components to suit every reasonable taste and
preference. A WAU may connect to, for instance, a "telephone", such as telephone instrument 300 in Figure 1, a conventional modem, directly to a personal computer via ISDN WAU, to a fax machine via fax WAU, or any other desired electronic device. A number of WAUs and handsets may be employed according to the present invention to accommodate any particular combination of electronic devices the subscriber desires to have connected to the PSTN. Figure 1 is purely a simple hypothetical floor plan in order to provide a modicum of perspective relative to NCUs, WAUs, handsets and other electronic devices as employed in communications webs of the present invention.
NETWORK CONTROL UNIT
Figures 3A through 3C show, in functional block diagram format, embodiments and portions of embodiments of Network Control Units ("NCU's") according to the present invention. According to a preferred embodiment of the present invention, NCU 100 includes interface circuitry for interfacing with PSTN lines or connections from a switch or other component of the PSTN, whether analog or digital. This circuitry, denominated "Network Interface" 650 as shown in Figure A, couples to switching, bridging and accessory circuitry as shown with numeral 660 in Figure 3A. This discussion considers signals in a "downstream" or a PSTN to NCU to WAU direction, from which corresponding signal flow in the opposite direction is apparent. The Cross Connect Switch / Conference Bridge / Accessory Block ("CAB") components couple signals from the Network Interface corresponding to incoming lines, in a predetermined and programmable manner, with additional functionality, if desired, to downstream circuitry for eventual RF transmission to WAU's and handsets. The switching and bridging components of the CAB are the portion of the Network Control Unit that allow the subscriber either remotely or locally to designate by programming into the NCU which of his or her telephone instruments, computers, fax machines, and other devices connect to various PSTN lines at particular times of day or under particular conditions.
The signals being properly switched and routed in the CAB as designated for the subscriber's devices are then delivered to the NCU's "Radio Multiplex Engine" ("RME") as shown in Figure 3A with numeral 670. The RME multiplexes the signals as, for instance, by time division multiplex access, or according to any desired format, onto a
number of predetermined channels for bandwidth and RF frequency conservation. The multiplexed signals are delivered to Radio Transceiver 680 where the signals may be conditioned, again multiplexed according to any desired format, and modulated onto an appropriate RF carrier or carriers in a programmable manner or as otherwise desired for transmission to WAUs 200, handsets 300 and other devices if desired.
An NCU Controller 690 connects to all circuits in the NCU and may be programmed via user interface on the NCU, via computer coupled to the Controller or other portions of the NCU, or remotely over one of the incoming lines 640.
NETWORK INTERFACE
In greater detail, the Network Interface 650 of the NCU may be modular in design and contains the circuits that connect to the public switched telephone network for accommodating various media, including twisted pair, coax, fiber and wireless, and various modes, including analog, digital or a hybrid. A Network Interface may be modular and portions for all lines may be implemented in applications specific integrated circuitry ("ASIC") medium to accommodate analog circuits, or services requiring, among other interfaces, ISDN, T-l, CATV/COAX, ATM, micro-ATM, AMPS, N-AMPS, TDMA digital cellular, CDMA digital cellular, analog or digital SMR (Nextel), PCS, LEO satellite, geosychronous satellite, Internet protocol or any other present or future form of wireless or wireline local loop or other PSTN service. As shown in Figure 3B, the Network Interface for a system according to the present invention which accommodates four POTS lines, could take the form of a quad arrangement of independent Direct Access Arrangement ("DAA") circuits 690, each having appropriate transformer, isolator and line protection circuitry as required, a two to four wire hybrid 700, and a coder / decoder ("codec") 10. The Network Interface circuitry is accordingly adapted for appropriate isolation, impedance matching, line protection, medium conversion (two wire to four wire) and analog-to-digital / digital-to-analog conversion in order for its output signal 720 to be coupled to CAB 660. (The functionality in POTS versions of direct access arrangement circuits 690 comprises conventional components and is conventionally implemented.).
Codecs according to the present invention in additional to their conventional functionality also compensate for line loss, mismatch and other incompatibilities with the
public telecommunications network by providing superior lowpass filtering implemented in digital signal processing techniques. Codecs 710 encode signals using an 8K or higher sampling rate as in mu-law logarithmic encoding, but quantize using segments which correlate to expanded length code words. According to a preferred embodiment of the present invention, such encoding is conducting using a 10-bit word length rather than the 8-bit length employed in mu-law encoding.
Such encoding techniques are preferably implemented in a conventional 16-bit analog to digital converter such as used for digital audio applications, and decoding is performed in such digital to analog converters. These may be integrated into the ASIC medium employed by the network interfaces according to the present invention. The resulting 16 bit performance yields an approximately 90 dB or better signal-to-noise ratio over the radiofrequency link, and allows the multiplexing techniques according to the present invention to accommodate the encoded signals. The resulting signal quality in the wireless compenents of the present invention is commensurate with wireline signal quality. Yet such techniques allow full 56K data rate transport capacity in a conventional 3. IK bandwidth. It is recognized that such performance degrades to conventional performance levels once signals processed according to such encoding are routed to the public telecommunications system, through standard line card codecs and mu-law encoding techniques if not due to line loss. In addition to the encoding technique described above, codecs of the present invention may encode using an oversampling, decimation, and interpolation ("OSDI") technique. According to the OSDI technique, 16-bit linear quantization and 16 kHz or higher sampling rate is initially employed on analog signals. After the oversampling, the signal is decimated to a lower sampling rate, preferably 10 kHz prior to transmission over wireless media.
- -To reproduce the signal accurately at the other end (e.g., Wireless Access Units), the decimated signal may be converted back into analog form and processed through a reconstruction filter. The reconstruction filter may be digital, wherein the reconstruction would take place prior to digital-to-analog conversion. If the reconstruction filter is analog, the reconstruction would take place following the digital-to-analog conversion. Alternatively, the reconstructioned signal may be mixed with the digital portion of the reconstruction occuring prior to D/A conversion and the analog portion occuring after
D/A conversion. The signal is then passed to a 4-wire to 2-wire hybrid and coupled out to the RJ-11 connector of the wireless access jack. The decimated signal at the access jack may be interpolated back up to 16 kHz or higher sampling rate to simplify the reconstruction filtering. An echo canceller may be used in conjunction with the mu-law encoding or the
OSDI encoding techniques described above in order to minimize near-end echo and thereby improve performance. Since the circuit from the hybrid at the PSTN connection to the hybrid at the access jack is a four-wire wireless circuit, the echo canceller may be located at either end. The echo canceller may also be split with portions of it located at either end. The echo canceller may be a fixed type echo canceller with preset coefficients that are calibrated to a given line condition. Alternatively, the echo canceller may be adaptive, such that it automatically corrects for variations in line conditions. The correction may occur using either a training sequence preamble that precedes certain transmission. The correction may alternatively occur based on stored coefficients from a previous session. The echo canceller would then adaptively select new coefficients based upon current real-time data.
Figure 3C shows an alternative arrangement for a Network Interface adapted to accommodate four POTS lines. There, the line conditioning circuitry which can include hybrids 700 and other components cross-couples to a single codec 710, instead of the requirement that a codec be employed for each line 640. Output of the Network Interface may be on a bus 730 instead of individual outputs coupled to CAB 660, in order to couple Network Interface 650 to CAB 660 via a multiplexed connection for physical simplicity and logical implementation. For ISDN, the Network Interface may be the so-called "U- Interface" and associated 4 level dibit modem circuitry. Other digital services require a Network Interface especially adapted to interface to a particular medium, format and protocol.
Network interface 650 may be further adapted to include an additional RJ-11 connector that allows hardwiring to a single-line telephone or existing in-home wiring. This would permit the NCU to manage existing telephones as a resource in addition to the handsets of the web. The NCU may include a dropout relay that automatically switches the hardwired extra RJ-11 connector over to one of the incoming lines in the event of a power failure or a system failure within the NCU.
For any of the wireless local loop or so called fixed wireless services including satellite, the Network Interface may be a wireless modem which includes a radio receiver or transceivers and appropriate modulation / demodulation, coding and decoding circuitry. When the Network Interface is a wireless modem / Radio Transceiver, the NCU 100 operates as a radio transponder or rebroadcast unit, communicating with the PSTN via one wireless protocol, and with the WAUs 200, handsets 300 and other components of systems according to the present invention via the same or perhaps different protocols. This aspect of the invention may be counter-intuitive: If the connection to the PSTN is wireless, one approach is simply to connect directly to any location in the residence instead of relaying signals through the NCU 100. However, systems according to the present invention address a problem this approach would present, because Radio Transceivers that interface to the PSTN typically must comply with elaborate air interface standards having precise frequency control, well-defined RF bandwidth, higher transmit power (to accommodate the greater distance to a cell tower or PCS antenna), better receiver sensitivity, higher battery drain and shorter battery life, and increase complexity and expense. A handset 300 or a WAU 200 according to the present invention, however, is a far simpler and less expensive device which need only accommodate the present invention's less stringent internal air interface standards, but nevertheless retain the functionality to provide corded quality and reliability for indoor / nearby outdoor service that is inexpensive, compact, lightweight, flexible and manufactured and sold, if desired, tailored to specific devices such as faxes or various digital standards which not every subscriber may wish to employ.
Incoming connections to the Network Interface 650 could be physically separate twisted pairs as in the case of analog POTS lines where each line terminates from the PSTN via an independent twisted pair; alternatively, each incoming circuit can be multiplexed over a single twisted pair, such as two digital circuits provided by a conventional, basic rate (2B + D) ISDN line. A 6 megabit per second micro- ATM fiber connection could provide digital voice service, MPEG video and other services over a single optical fiber which could be de-multiplexed (multiplexed for outgoing or upstream information) in the Network Interface, and incoming lines could be virtual. That is, additional lines could be assigned on an as needed basis and charged accordingly. For example, a subscriber might have connection to one line from 10:00 p.m. to 7:00 a.m, two
lines from 7:00 a.m. to 9:00 a.m. and four lines from 9:00 a.m. to 7:00 p.m. and be billed accordingly for the partial use. As discussed below, the CAB 660 can be programmed to accommodate changes in the PSTN connections in real time in order to distribute bandwidth and service as desired among various WAUs 200, handsets 300 and the other end user interface devices.
CROSS CONNECT SWITCH / CONFERENCE BRIDGE / ACCESSORY BLOCK
Cross connect switch / conference bridge / accessory blocks ("CAB's") according to the present invention may be, electronically or virtually, an n x m switch which is programmed to interconnect any incoming signal 720 from the Network Interface 650, (whether physical, virtual, multiplexed or wireless) to a number of output signals or interfaces which correspond to communications channels, according to one topology, or to combinations of the handsets, telephones, fax machines, computers or other devices serviced by WAU's 200 and/or handsets 300 of the present invention, according to another topology. The CAB 660 can, but need not, include functionality simply to bridge or conference these same circuits and/or remote devices, thus eliminating the need for further processing of the signals beyond CAB 660. A CAB may additionally contain a variety of decoders, generators, synthesizers and other circuits as desired.
CAB 660 is preferably coupled to a local Control Processor and/or an external computer and/or network or server, if desired. The external connection may be directly by bus or synchronous connection, or via any of the PSTN lines 640. In systems according to the present invention having multiple NCUs, CABs 660, Control Processors 690 and other components may be coupled and/or networked among various NCUs and/or external / or server control capacity. The CAB shown in Figure 3 A is under control of a local Control Processor 685 and personal computer 687. For voice services, the CAB 660 may function similar to a central switchboard and conference bridge routing each line to one or more Wireless Access Units 200 and/or handsets 300 as programmed in Control Processors 685 and/or PC 687. Multiple lines 640, handsets 300, telephones connected to WAUs 200, and other devices may be conferenced to form any number of permutations and combinations of conferences. One wireless handset can call another without using any of external lines 640 simply using the allotted time slots, codes or RF channels involving the two handsets
300, or telephones connected to a WAU 200. A conference call of any two or more internal handset or telephone devices can similarly occur. Calls or conferences among multiple devices on multiple networked or shared NCU's can similarly occur.
The CAB 660, like other components in the NCU, the WAU's and the handsets, can be implemented in analog circuits including relays, transistors, CMOS media or any other application specific or nonspecific analog components and/or integrated circuits, but preferably signals 720 arriving at CAB 660 are digital so that CAB 660 may be implemented entirely digitally.
CABs 660, according to the present invention, are adapted to route and direct data signals, such as, for example, when using external data services via Internet or internal networks within the subscriber's location. In the voice case, virtual circuits may be established for each call which can remain in place for the duration of a call. In the data case, a Carrier Sense Multiple Access ("CSMA") or packet switching protocol can be employed, among other formats or protocols, in order to support a larger number of bursty devices. A combmation of virtual data circuits and CSMA can be employed if desired. In similar fashion, CABs 660, according to the present invention, are also adapted to accommodate voice and data traffic simultaneously, routing traffic and managing resources as desired.
Conference Bridge functionality in the CAB 660 is preferably implemented as a high quality digital bridge which maintains all connections at suitable and equal audio levels. Although the Conference Bridge functionality can be implemented in analog circuits, again it is preferably implemented digitally using logic or digital signal processing. Digital leveling and noise control may be used to maintain voice circuit quality regardless of the numbers of parties bridged together. The Conference Bridge may also be adapted to bridge in one or more outside lines onto an existing circuit, adding handsels 300 and/or WAUs 200 to the circuit.
The Accessory Block functionality, which may, but need not, form a portion of CABs 660 according to the present invention, may contain features which add flexibility and additional levels of services to communications webs according to the present invention. The Accessory Block functionality may include, for instance, DTMF generator, DTMF decoder, speech synthesizer, speech recognizer, caller ID decoder, low or high speed telephone modem, fax modem capable of group III or similar functions, real
time clock / calendar and other functionality as desired. These functions are provided in conjunction with the Control Processor 685 and other portions of CAB 660 to implement capability such as autodialing, remote programmability, voice command features, digital voice prompting, and other advanced functionality. Portions or all of the Accessory Block Functionality may be sited on board or remote to NCU 100 as desired for particular implementations.
The NCU Switching, Bridging and Accessory Block functionality or any other software employed by NCU 100 may reside on board the NCU and may but not be remotely programmable or upgradeable. It may also incorporate remotely accessed or pushed program and or data objects and/or applications as desired, including in the JAVA, Active/X, or other languages.
NCU's 100 according to the present invention preferably include a standard connector such as an RJ-11 connector which may be hardwired to a single line telephone or connected, for example, to existing in-home wiring. This connector permits the NCU 100 to manage the existing telephone or wiring as part of its network, perhaps permitting them to answer any ringing line. Alternatively, a POTS NCU 100 could have a drop out relay or FET circuit which may automatically switch the existing wiring over to this connector in the event of a power failure or a system failure. If the NCU 100 is equipped with backup batteries or other auxiliary power, it may continue to function either until mainspower is restored or its batteries become exhausted in which case it drops off-line and switches to the emergency bypass routing to the external connector.
Control Processor 685 according to the present invention commands switching, routing, RF, accessory and other functionality implemented in CAB 660, Radio Transceiver 680 and other circuits in NCU 100s according to the present invention. Control Processor 685 could be a small micro-controller set, although more processing power may be required to accommodate ISDN and other digital interface NCUs 100. Then, external PCS 687 and, if desired, servers, may participate in the control functions. A very simple algorithm by which the Control Processor 685 governs CAB 660 for the topology shown in Figure 1 is shown in Figures 11 A and 1 IB, in which, step-by-step, lines 640 are matched in the CAB 660 to various WAUs 200, handsets 300, and other devices. The control algorithms and programming itself may occur locally as by an interface 689 which may be implemented in buttons or a keyboard, by PC 687 or external
connection, including network or PSTN.
Alternatively, systems of the present invention are adapted to permit control of the NCU 100, including Control Processor 685 and CAB 660 from a remote service center so that a subscriber can call the service center in the event the subscriber feels technically short of the task of programming his or her NCU to accommodate various WAUs 200 and handsets 300.
PC and other external connectivity leverages on higher intelligence of the PC, additional mass memory functionality for updates and databases and similar applications, the more convenient user interface, and more elaborate applications software such as, for instance, directory management, spreadsheets and database managers.
RADIO MULTIPLEX ENGINE
CAB output signals 750 are coupled to a radio multiplex engine 670 according to the present invention which can comprise a digital logic block that implements any of the following functionality: multiplexing / demultiplexing, preferably but not necessarily TDMA / TDD (Time Division Multiplex Access / Time Division Duplex), forward error control and general error management, speech compression if required, code division multiplex and demultiplexing, if any, hopset generation if any, and other critical timing, synchronization and coding functions critical to the operation of the systems according to the present invention.
RME's 670 according to the present invention generally but not necessarily operate at speeds sufficiently high to render Control Processor 685 management ineffective, although that need not be the case.
RME signals 770 are coupled, in systems of the present invention, to wireless Radio Transceiver ("RT") circuitry 680 as shown in Figure 3 A. The RT 680 may be a low cost multiplexed Radio Transceiver or set of transceivers which provides proper modulation onto RF carriers as desired with or without multiplexing and duplexing according to any of the following formats or others: TDMA / TDD, TDMA / FDD, CDMA / FDD, CDMA / TDD, FHMA / TDD, or FHMA / FDD. The primary function is to achieve transmission of multiple simultaneous independent data streams to WAUs 200 and handsets 300.
Conveniently, the RT circuitry 680 need not conform to any error interface
standard, since it communicates only with like equipment and usually does not interface to the PSTN or any other public network except via a separate, higher quality transceiver if any is implemented in the Network Interface 650 or connected to it.
Via an independent communications protocol, the RT unit 680 can communicate with other NCUs 100 that fall within radio range. The NCUs 100 can share hopset data interference records, timing and usage information, all toward the end of avoiding one another's transmissions. In like manner, the components of each system, NCUs 100, WAUs 200, handsets 300 all transmit at the lowest power possible to provide reliable communications, using power management sensing and response to the circuits. In this manner, each system minimizes its "radius of interference," the approximate circular area surrounding a given system within which it is capable of generating interference in other systems operating in the same band.
WIRELESS ACCESS UNITS Wireless Access Units 200 according to the present invention may be of two general sorts: (1) analog for a wireless telephone jack function such as one that can accommodate a telephone or a conventional modem; or (2) digital, for a wireless computer or digital device connection (such as DB-25, USB, Ethernet, ISDN-ST, PCMCIA or similar serial or parallel data communications connection). Figure 5 shows one form of analog WAU 200 according to the present invention.
The analog WAU 200 may include a Radio Transceiver 800 which links WAU 200 via RF connection to NCU 100, a Radio Multiplex Engine 802, a Control Processor 804, and circuitry that provides basic subscriber loop functions of battery, over voltage protection, ringing, supervision (off hook sensing), codec, hybrid and test functionality (so called borscht) functionality. The codec employs the expanded code word encoding / decoding techniques described above with reference to Network Interface 650. The analog WAU 200 of Figure 5 may be implemented in a small unit which resembles a wall transformer with one or more RJ-11 jacks on the back or side, and it can, if desired, draw power from any AC outlet and provide an analog telephone type connection to a computer modem, a fax machine, a telephone answering device, a standard telephone or any other device that connects with a standard RJ-11 jack. The unit is transparent to caller ID information, and passes it through. Similarly, the unit passes through coded ringing and other custom
signaling. Its power supply provides power for standard telephones which are line powered. Its high voltage ring generator rings telephones with the standard 60 volt rms., 20-Hz ring signal. Note that while this unit is typically though not necessarily "wired" to the AC power wiring and therefore is not totally "wireless," the length between this unit and the incoming lines 640 connected to NCU 100 is wireless. It therefore eliminates the subscriber's need to place telephones where telephone outlets are located. Battery power, if employed, provides even more flexibility in location.
A digital Wireless Access Unit 200 of one sort according to the present invention is shown in Figure 6. Such a Wireless Access Unit 200 can provide wireless connection to computers, computer peripherals, ISDN-ST telephone sets and other digital devices. Since the radio link used in systems according to the present invention is digital, the digital circuitry in the Wireless Access Unit 200 principally performs a buffering, error control, and protocol conversion function. The external digital interface can take many forms, including DB-25, the standard serial port connector; USB, Intel's new universal serial bus standard; parallel-port (printer) connection; Ethernet; 10-base-T; 100-base-T, Fast or Gigabit Ethernet; PCMCIA and others. Digital Wireless Access Unit 200, like analog Wireless Access Unit 200, may be main or battery powered, so that they may provide untethered convenience to the user.
WIRELESS CONTROL / MONITORING ACCESSORIES
Systems according to the present invention can also perform many control and monitoring functions at a subscriber's location for convenience and increased efficiency. For instance, a wireless doorbell accessory or WAU 200 can emit a coded ring in response to a ringing doorbell signal. The subscriber could then press an "intercom" soft key, placing the subscriber in full duplex communications with the front door visitor and possibly calling up his or her image on a display. Other wireless accessories can provide control over home lighting, garage door opening, and security monitoring. Likewise, via appropriate soft key, the handset or other interface device can control televisions, stereo equipment, heating, air conditioning and appliances. Baby monitoring via wireless audio monitor and other consumer electronics functionality are accommodated by the present system, whether or not via the CE-bus.
In addition, individual handsets may be monitored and located using handset
locator information programmed into the NCU controller. For instance, NCU controller may be programmed to monitor the extra RJ-11 jack for particular commands or patterns. Thus, when an individual enters a particular code into a handset (e.g., "***"), the NCU sends a locator signal to one or more handsets. The handset, in turn, emits an audible signal. In this manner, handsets may be easily located throughout the house.
PROGRAMMING CONFIGURATION INFORMATION
In addition to programming the system via the wireless access unit 200, the system may be programmed remotely from a computer via TCP/IP access to the internet. The user may utilize a web browser to locate a web page specified by the manufacturer of the system. The web page is located on an internet server and contains information specific to the manufacturer. At the web page, the user may enter a serial number for the system. Preferably, the serial number is located on the network control unit 100 or on each of the wireless access units 200. The web page may include a verification procedure, such as a CRC or PN algorithm to ensure that the user has entered a proper serial number. The web page may require the user to enter additional information about the system, as well.
Once the user has passed the verification procedure, a second web page is displayed by the browser. On the second web page, a questionnaire is provided regarding system configuration. The questionnaire allows the user to specify configuration information regarding the system. For instance, the questionnaire allows the user to specify a plurality of names and telephone numbers to be stored in the network control unit memory. Once the user has entered all of the desired configuration items, the user may press an END button in the second web page. The information specified in the web page is then downloaded to the manufacturer. The server will return a session identifier to the user.
The user then uses a handset to call a toll-free number specified by the manufacturer. The user is then prompted to enter a session ID. Once the session ID is entered, telephony provided by the manufacturer emits a series of tones that are recognized by the network control unit 100. The network control unit 100 then enters a configuration download mode. The manufacturer's telephony then downloads the data specified by the user.
OPERATION
The four main component parts of systems of the present invention, as disclosed above, are the Network Control Unit 100, Wireless Access Units 200, handsets 300 and Wireless Control / Monitoring Accessories 350. While each component may contain an onboard microcontroller which governs its basic functions, the NCU 100 alone or acting in concert with external controller capacity is preferably the principal controller and manager of the entire communications web. All remote components are preferably simple, reliable and preferably of limited intelligence / functionality for reduced costs and increased modularity and so that system performance and functions are principally determined by the NCU 100. The NCU 100 may contain on-line firmware and/or software upgrade capability as discussed above. Through this capacity and the centralized intelligence architecture of the systems according to present invention, functioning of the entire system can be upgraded, new features added, software bugs repaired and hardware bugs patched, all by downloading new firmware into the new NCU 100. The majority of the NCU's computer program code is preferably maintained in flash, reprogrammable memory. Firmware in remote units are preferably implemented in ROM memory, although not necessarily.
The NCU 100 is the central part of the systems' star network topology, for the entire system, the NCU 100 selects RF channels, hop sequences if any, and spreading codes if any; it manages ID strings for the various remotes, and it performs the other functions related to network management, remote unit registration and authentication, and communications protocol management. The NCU 100 also controls the switching and interconnection of the CAB 660, and drives all the Accessory Block features of CAB 660. The following examples describe operation of two embodiments of the communications webs according to the present invention.
EXAMPLE 1
A system according to the present invention is shown in Figure 12 with four incoming POTS lines, an NCU 100 in the basement or attic, a wireless handset, and three Wireless Access Units 200 which correspond to a telephone, a computer, and a fax machine. The system may be programmed as follows: POTS line 1 is programmed in the
CAB 660 to ring through and connect to the LCD handset 300. POTS line 2 rings through and connects to Wireless Access Unit number 1 which is connected to a standard telephone via an RJ-11 jack. POTS line 3 connects to Wireless Access Unit number 2, which is, in turn, adapted to accommodate a fax machine. POTS line 4 connects to Wireless Access Unit number 3 which connects via RS-232 interface to a personal computer.
Signals from POTS lines 1-4 are coupled to Radio Multiplex Engine 670, multiplexed as in TDMA format and modulated onto an RF carrier in RT or digital radio modem 680 for transmission. Handset 300 receives the signal from the NCU 100, and demodulates, demultiplexes and processes the information intended for handset 300. That information is contained in a signal provided to the interfacing circuitry and coder / decoder 650 for delivery to the human interface. The signals are also provided to an LCD driver and screen. In an upstream direction, signals from the keypad and microphone are processed, multiplexed, modulated and forwarded to NCU 100 which ultimately demodulates, demultiplexes and processes the signals for delivery to POTS line 1. Wireless Access Units 1-3 operate generally in a similar manner as far as the RF and multiplexing circuitry are concerned. However, Wireless Access Unit number 1 contains interface circuitry adapted to accommodate a standard telephone, including, for example, coder / decoder circuitry, line interface, battery, supervision, and ring generator circuitry which interfaces to an RF-11 jack. Wireless Access Unit number 2 interface circuitry intended for a fax machine may be similar or identical to Wireless Access Unit number 1.
Wireless Access Unit number 3 is configured with interface circuitry to accommodate a RS-232 port rather than an RF-11 analog jack. Accordingly, forward error correction, universal asynchronous receiver / transmitter and handshaking circuitry is included in connection with RS-232 serial port standards.
, if the subscriber desires to eliminate POTS line 4, for example, or only to subscribe to it for a portion of the day, POTS line 3 could be reprogrammed in the CAB 660 to accommodate Wireless Access Unit number 3 for computer commumcations while POTS line 2 is configured to ring through to Wireless Access Units 1 and 2 for the telephone and fax machine. Any other combination may be employed as desired, as the user desires new services or different services, or adds devices to the communications web with their attendant Wireless Access Units.
EXAMPLE 2
Another system according to the present invention is shown in Figure 13 with two incoming POTS lines and an ISDN line. POTS line 1 is programmed in CAB 660 of Network Control Unit 100 to ring through and connect to LCD handset 300. POTS line 2 is programmed to ring through and connect to Wireless Access Unit number 1 and number 2, which in turn connect to the standard telephone and a fax machine, respectively. The ISDN line is programmed to connect to Wireless Access Unit number 3 and thus to a computer via a serial port. Again, the lines may be programmed to connect to various handsets 300 and Wireless Access Units 200 as desired as the user desires new or additional services or adds other devices. With the existing devices shown in Fig. 13, for instance, the user could program CAB 660 to connect POTS line 1 to handset 300 and Wireless Access Units 1 and 2 in order to eliminate the second POTS line. Similarly, line 1 could be designated the voice line for connection to handset 300 and Wireless Access Unit number 1. Line 1 or Line 2 could also be wired in the Network Interface 650 or otherwise to connect directly through to existing wiring as shown in Figure 13
The foregoing discloses a preferred embodiment of the present invention. Various modifications, adaptations, and alternative embodiments may be made within the scope and spirit of the present invention. The invention is further defined by the following claims: