Abstract:
A new method and system for adapting standard home network protocol communication signals for communication between networked computation devices over the AC power line is provided. This invention provides improvements to the standard home network protocol required for use over the AC power line, including such features as encrypting, signal amplification and improved signal to noise ratio.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is based on U.S. Provisional Application Ser. No. 60/201,221, which was filed on May 2, 2000, and priority is claimed thereto. 
     
    
     
       BACKGROUND OF INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to voice and data communication systems and methods. More specifically, this invention relates to voice and data communication systems and methods that adapt telephone voice and modem signals for use on an AC power line, which uses a high speed computer networking phone line modem standard.  
           [0004]    2. Description of Related Art  
           [0005]    A variety of AC power line communication systems have been developed and are widely used in order to facilitate communication within a facility where dedicated wiring is unavailable. A variety of “home networking” computer communication standards have also been proposed. Included in these “standards” are HomePNA 2.0, CEA R.7.3, HomePlug 1.0, IEEE 8.02.11, HomeRF and Bluetooth 803.xx. However, the use of a power line communication channel imposes several important requirements on the method and system of networking computers and other digital devices. No prior system or method specifically addresses the requirements of AC power line communications while providing a standard for data communication as required to effectively network computer, and other similar devices, within a structure or facility. This is the subject matter of this invention.  
         SUMMARY OF INVENTION  
         [0006]    It is desirable to provide a method and system for adapting high-speed computer modem signals for transmission over an AC power line. Moreover, it is desirable to provide such a method and system that meets the specific requirements of wireless networking over the AC power line.  
           [0007]    Therefore, it is the general object of this invention to provide a system, which employs a standard “home” computer networking protocol.  
           [0008]    It is a further object of the preferred embodiment of this invention to employ a HomePNA-type standard protocol.  
           [0009]    Another object of this invention is to provide enhancements, such as additional signal amplification, error correction, filtering, and security encryption as required to facilitate the use of the AC power line communication channel.  
           [0010]    A still further object of this invention is to provide a method of communicating between two or more digital computation devices using a standard protocol over the AC power line channel.  
           [0011]    It is another object of this invention to provide a method and device for communicating over the AC power line that permits the use of a wide range of modulation methods.  
           [0012]    These and other objects of this invention will be readily apparent to those of ordinary skill in the art upon review of the following drawings, detailed description and claims. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0013]    [0013]FIG. 1 is a top-level block diagram of the preferred embodiment of this invention.  
         [0014]    [0014]FIG. 2 is a block diagram of the preferred embodiment of the power line interface section of this invention.  
         [0015]    [0015]FIG. 3 is a schematic of the preferred power line coupler of this invention.  
         [0016]    [0016]FIG. 4 is a detailed diagram of the preferred isolation RF coupling section of this invention.  
         [0017]    [0017]FIG. 5 is a detailed block diagram of the analog front end processing of this invention.  
         [0018]    [0018]FIG. 6 is a schematic of the preferred variable gain amplifier of this invention.  
         [0019]    [0019]FIG. 7 is a detailed block diagram of the preferred modem/phone line physical layer digital processing.  
         [0020]    [0020]FIG. 8 is a more detailed diagram of the preferred variable gain amplifier controller of this invention.  
         [0021]    [0021]FIG. 9 is a block diagram of the back end interface section of the preferred embodiment of the invention.  
         [0022]    [0022]FIG. 10 is a flow chart of the preferred steps of the method for the transmit of data from a computer to the AC power line.  
         [0023]    [0023]FIG. 11 is a flow chart of the preferred steps of the method of the receipt of data by a computer from the AC power line.  
         [0024]    [0024]FIG. 12 is a drawing of the preferred spectrum used with this invention.  
         [0025]    Reference now is made to the foregoing drawings in the following detailed description of this invention. 
     
    
     DETAILED DESCRIPTION  
       [0026]    This invention is a method and system for adapting telephone-modem communication signals to use a wireless (non-dedicated wire) communication channel. In its preferred embodiment an AC power line communication channel is used. Alternative embodiments may use an RF over-the-air channel. The substitution of RF over-the-air can generally be substituted without departing from the concept of this invention. The AC power line communication channel permits communication between telephones, computers and other electronic equipment without requiring dedicated or telephone wiring. This approach makes use of the existing AC power wiring by imposing the communication signal on the AC power lines and by facilitating the transmission and reception of the signals by standard telephones, computers or other communication equipment. This invention also employs a standard communication or networking protocol. In its preferred embodiment, this invention employs the HomePNA 2.0 protocol, although alternative protocols can be substituted without departing from the concept of this invention. Such alternative communication protocols, include but are not limited to: CEA R.7.3, HomePlug 1.0, IEEE 802.11, HomeRF, Bluetooth 803.xx, and other versions of each as well as HomePNA.  
         [0027]    HomePNA, the preferred protocol of this invention, is adapted specifically for networking multiple computers and/or other devices within a local area. Generally, designed for use with telephone wiring, this invention permits the substitution of AC power lines, for communicating between the multiple computers, telephones or other devices, while still providing the advantages of HomePNA, or the alternative, protocols. The use of a HomePNA type networking protocol, in combination with an AC power line communication channel provides a method and system for communication at rates of between 1 Mbit/sec and 10 Mbit/sec, using a standard proven protocol that works with existing personal computer operating systems, while avoiding the requirement of dedicated telephone or other wiring, otherwise required to provide the communication channel or medium. This system also facilitates the communication of data, voice, fax, and multimedia signals over the common AC power line. This invention provides improved signal strength, signal-to-noise ratios, and data security. Sophisticated, modulation, error correction and encryption techniques are employed.  
         [0028]    Referring now to the figures and particularly FIG. 1, which is a top-level block diagram of the preferred embodiment of this invention. A power line interface  101  connects the system to an AC power line. In electrical communication with the power line interface  101  is an analog front-end processor  102 , which amplifies, filters and converts analog signals to digital signals, as well as digital signals to analog signals, for processing. Connected to the analog front-end processor  102  is the modem/phone line physical layer digital processor  103 , where, in the preferred embodiment, the HomePNA-type protocol is performed. The modem/phone line physical layer digital processor  103  is connected to the back end interface  104 , which provides the handshaking with the computer or other networked device  105 . The preferred computer or other networked device  105  may be interfaced to a network device, using such network protocols as ISA, MII, PCI, USB, PCMCIA, and/or Ethernet. Preferably, within the computation device  105  encryption/decryption is provided to provide communication channel security.  
         [0029]    [0029]FIG. 2 shows a block diagram of the preferred embodiment of the power line interface  101  section of this invention. The power line interface  101  couples the usable RF band on to and off of the AC power line. The preferred power line interface  101  includes a power line coupler  202 , which is electrically connected to a standard AC power outlet, via a standard power plug  201 . Electrically connected to the power line coupler  202  is a connector, typically and preferably and standard RJ-11 connector. The connector  203  is electrically connected to an RF isolator/coupler  204 .  
         [0030]    [0030]FIG. 3 shows a schematic of the preferred power line coupler  202  of this invention. This preferred coupler  202  is designed for low loss, and has a low frequency isolation capacitor  301 , as well as a low loss transformer  302 . The preferred capacitor  301  has a capacitance of 0.01 μF. The preferred transformer  302  has a resistance of about 50 Ω and approximately 50 micro Henries. The preferred coupler  202  uses magnetic coupling, although alternative couplers, including but not limited to optical and/or capacitive coupling can be substituted without departing from the concept of this invention.  
         [0031]    [0031]FIG. 4 shows the detailed diagram of the preferred RF isolation coupling section  204  of this invention. A high pass filter capacitor  404  is provided connected to a common mode filter  401 , the other side of which is connected to a band pass filter  402 . The preferred band pass filter  402  passes signals in the frequency range of between 4.5 MHz and 9.5 MHz, to facilitate the use of the HomePNA protocol. An RF transformer  403  is electrically connected to the band pass filter  402  to provide line isolation. The RF transformer  403  has two connections,  404  for outgoing signals and  405  for incoming signals.  
         [0032]    [0032]FIG. 5 shows a detailed block diagram of the analog front-end processor  102  of this invention. An outgoing signal amplifier  501 , preferably but not necessarily a discrete amplifier, received the outgoing signal  404 . The output of the outgoing signal amplifier  501  is connected to the input of an anti-aliasing filter  502 . The anti-aliasing filter  502  feeds a variable gain amplifier  503 , which is controlled  508  from the variable gain amplifier controller  701  (see FIG. 7). The output of the variable gain amplifier  503  is received by an analog-to-digital converter  504 , which in turn produces a digital version of the outgoing signal  509  for use by the modem/phone line physical layer digital processor  103 . The preferred A/D converter  504 , is a 12-bit A/D. The incoming signal  405  is amplified by an amplifier  505 , after being filtered by a reconstruction filter  506 . The reconstruction filter  506  receives its input signal from a digital-to-analog converter  507 , which receives the input source signal  510  from the modem/phone line physical layer digital processor  103 . The current preferred D/A converter  507  is a 10-bit D/A. The amplifiers  501 ,  505  are provided to increase the signal power on the power line from about 35 bm to about 10 dbm to −20 dbm.  
         [0033]    [0033]FIG. 6 shows a schematic of the preferred variable gain amplifier  503  of this invention. This amplifier  503  has buffer  601 , which receives a control voltage  508  from the variable gain amplifier controller  701 . The buffer  601  selects the appropriate resistance value from a set of series and parallel resistors  603   a - f ,  604   a - e . The input signal  602  reaches the input of the gain stage  605 , which is provided with a feed back path resistance  606  and which provides the output  607  of the variable gain amplifier  503 .  
         [0034]    [0034]FIG. 7 shows a detailed block diagram of the preferred modem/phone line physical layer digital processor  103 . A variable gain amplifier controller  701  is provided to optimize the input levels and to thereby cooperate with the variable gain amplifier  503  to compensate for power losses. The variable gain amplifier controller  701  is controlled by a signal  716  from the media access controller  901  (see FIG. 9). A dc reject  702  receives the outgoing signal  509  to remove dc bias. The preferred dc reject  702  circuit is an averager followed by a subtractor. The output of the dc reject  703  is the input to a serial-to-parallel converter  703 , which preferably provides between  64  and  512  parallel output signals  708 . These parallel signals  708  are received by a transform circuit  704 , typically and preferably in the HomePNA protocol, either a discrete Fourier transform or a fast Fourier transform. The transform circuit  704  outputs the transformed signal to a decoder  706 , which is provided to turn received symbols into bits using modulation tone estimates from the channel estimator  705 , under control of the modulator and tone manager  713 . The channel estimator  705  is controlled by signals from the media access controller  901 . The channel estimator  705  is used to compensate for degradation in the channel, by estimating the usable frequencies or channel quality for each tone, for OFDM modulation. The quality of the channel is generally described by the signal-to-noise ration and/or the signal strength. The decoder  706  output is fed to an error decoder  707 , which is used to implement forward error correction, preferably using such techniques as Reed-Solomon, Viterbi, RS-Viterbi, Iterative Viterbi, Turbo Viterbi, and/or Turbo Product Codes. The output of the error decoder  707  is received by the receiver and transmitter buffer  715 , from which the data  717  is communicated to the media access controller  901 . The input signal  510  within the modem/phone line physical layer digital processor  103  begins in the receiver and transmitter buffer  705 . The received data is output from the receiver and transmitter buffer  715  to an error encoder  714 . The error encoder  714  is used to implement forward error correction, preferably using such techniques as Reed-Solomon, Viterbi, RS-Viterbi, Iterative Viterbi, Turbo Viterbi, and/or Turbo Product Codes. The output of the error encoder  714  is received by an encoder  712 , which turns bits into symbols using modulation tone estimates per frequency bin, in the preferred OFDM modulation implementation. The encoder  712  is controlled by the modulation and tone manager  713 . The preferred modulation technique of this invention is OFDM, although alternatives, such as BPSK, DBPSK, QPSK, DQPSK, OGPSK, 8-PSK, D8-PSK, QAM 16, QAM 32, QAM 64 and other similar modulation techniques can be substituted without departing from the concept of this invention. The modulation and tone manager  713  uses channel estimates to compensate for channel characteristics; specifically it selects or differentiates between usable channels in the transmission medium. The output of the encoder  712  is received by an inverse transformer  711 , preferably an inverse discrete Fourier transform or an inverse fast Fourier transform. The output of the inverse transformer  711  is typically a bus of 64 to 512 parallel input lines  709 , which feed into a parallel-to-serial converter  710 , the output of which is the input signal  510 .  
         [0035]    [0035]FIG. 8 shows a more detailed diagram of the preferred variable gain amplifier controller  701  of this invention. This controller  701 , which serves to estimate signal power and to calculate the necessary power gain required, has a power detector  801 , which is connected to an integrator or low-pass-filter  802 , the output of which is a gain converter  803 . The gain converter  803  serves to “calculate” the gain from the power in the estimate.  
         [0036]    [0036]FIG. 9 shows a block diagram of the back end interface section  104  of the preferred embodiment of the invention. A media access controller  901  in electronic communication  903  with the physical layer interface buffers  902 . The media access controller  901  is preferably connected to a serial/parallel control interface  904 . The preferred media access controller  901  employs carrier sense multiple access collision avoidance (CSMA/CA) to control access to the power line physical medium by monitoring line or channel access availability. The preferred physical layer interface buffers  902  are FIFOs, typically 2 k by 8 bits and are provided to permit data handshaking at different rates. These FIFOs may be installed within a digital computer device.  
         [0037]    [0037]FIG. 10 is a flow chart of the preferred steps of the method of the transmit of data from a computer to the AC power line. This process starts  1001  with data being read  1002  from computer memory. This data is then encrypted  1003  to provide channel security. The encrypted data is stored  1004 . A test is made  1005  to determine if the channel medium is clear. If the channel is not clear, the test  1005  is repeated. If the channel is clear, data is fetched  1006  and is stored  1007  in the transmit buffer. Error encoding  1008  is performed, preferably using a forward error correction method. The bits/frequency tone is modulated  1009 , preferably using OFDM, although other alternative modulation techniques can be substituted without departing from the concept of this invention. Bad tones are mapped out  1010 . Data is converted  1011  to OFDM symbols. A parallel to serial conversion is performed  1012 . A digital-to-analog conversion  1013  of the data is made. The analog data is then filtered  1014  and amplified  1015 , before coupling  1016  the signal to the AC power line.  
         [0038]    [0038]FIG. 11 shows a flow chart of the preferred steps of the method of the receipt of data by a computer from the AC power line. This process starts  1101  with the reception of a power line signal  1102 . The signal is amplified  1103  and filtered  1104 . The filtered data is next converted  1105  from an analog form to a digital form. The resulting digital form is converted  1006  from serial to parallel. OFDM symbols are next converted  1107  to data. The data (tones) is demodulated  1108  to bits. Channel estimating occurs  1109 . Error decoding is performed  1110 , using a forward error correction decoder. The resulted error corrected data is stored in a receive buffer  1111 . The stored data is sent  1112  to the digital communication device, where the data is stored  1113 , decrypted  1114  and the decrypted data is stored  1115  in computer memory.  
         [0039]    [0039]FIG. 12 is a drawing of the preferred spectrum  1201  used with this invention. The signal frequency band preferred for use in HomePNA systems has a band between 4.5 MHz and 9.5 MHz with a notch  1202  of approximately 40 MHz to accommodate the HAM band.  
         [0040]    It is to be understood that the above-described embodiment of this invention is merely illustrative of numerous and varied other embodiments, some of which are noted in the description, which may constituted applications of the principles of the invention. Such other embodiments may be readily devised by those skilled in the art without departing from the spirit or scope of this invention and it is our intent that they are deemed to be within the scope of this invention.