Abstract:
Systems and methods for supporting communications over powerlines are provided. The system can include a frequency and amplitude selective optical converter coupled to a powerline, an optical multiplexer coupled to the optical converter and an optical demultiplexer coupled to the optical multiplexer. The optical converter can be tuned to a frequency and amplitude corresponding to voice or data communication signals carried on the powerline.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    There are a variety of different transmission interfaces for communications, including wireless and wired communications. Wired communications are typically employed over wires dedicated solely for supporting communications, e.g., the public switched telephone network (PSTN). Another type of wired communications, commonly referred to as powerline communications, employs electrical powerlines to carry communications. In particular, communication signals are modulated onto the powerline by a transmitter and then demodulated by a receiver. Because there is a much larger existing infrastructure for electrical powerlines compared to dedicated communication lines, the infrastructure costs of deploying a powerline communication system can be reduced compared to dedicated communication line systems. 
       SUMMARY OF THE INVENTION 
       [0002]    Powerlines are noisy environments. For example, powerlines typically act like large antennas, absorbing a variety of radio frequency interference. Moreover, appliances typically introduce interference into powerlines. Conventional techniques for mitigating noise on powerlines involve line filters. These filters, however, are ineffective in removing in and out of band hystersis and noise levels. 
         [0003]    In view of the above-identified and other deficiencies of conventional powerline communication techniques, exemplary embodiments of the present invention provide systems and methods of mitigating noise in powerlines. An exemplary system includes a frequency and amplitude selective optical converter coupled to a powerline. The system also includes an optical multiplexer coupled to the optical converter and an optical demultiplexer coupled to the optical multiplexer. The optical converter is tuned to a frequency and amplitude corresponding to voice or data communication signals carried on the powerline. 
         [0004]    The optical converter can include a first diode tuned to pass signals with a first frequency and a first amplitude and a second diode tuned to pass signals with a second frequency and a second amplitude, where the first and second frequencies correspond to a frequency bandwidth of a communication signal. The first and second diodes can be PIN diodes or light emitting diodes (LEDs). 
         [0005]    The optical converter can also include a third diode tuned to pass signals with a third frequency and the first amplitude and a fourth diode tuned to pass signals with a fourth frequency and the second amplitude, where the third and fourth frequencies correspond to a frequency bandwidth of another communication signal. 
         [0006]    The first frequency can be approximately 2.4 GHz, the second frequency can be approximately 2.5 GHz, the third frequency can be approximately 1800 MHz and the fourth frequency can be approximately 1900 MHz. 
         [0007]    The first and third diodes are light diodes and the second and fourth diodes are dark diodes. 
         [0008]    The system can also include an optical-to-wireless converter coupled to the optical demultiplexer. The optical-to-wireless converter transmits wireless communication signals corresponding to the voice or data communication signals carried on the powerline. 
         [0009]    Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0010]      FIG. 1  is a block diagram of an exemplary powerline communication system in accordance with the present invention; 
           [0011]      FIGS. 2A and 2B  are block diagrams of exemplary systems for filtering powerline signals in accordance with the present invention; and 
           [0012]      FIG. 3  is a graph of an exemplary powerline waveform and an exemplary filter in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]      FIG. 1  is a block diagram of an exemplary powerline communication system in accordance with the present invention. The exemplary system couples a plurality of buildings  128 ,  140 ,  148  and  152  to a power source  110  and a communications network  102 . Specifically, communications network  102  is coupled to gateway  104 , which in turn is coupled by communications link  106  to powerline-communications coupler  108 . Power source  110  is coupled by powerline  112  to powerline-communications coupler  108 . Powerline-communications coupler  108  modulates communication signals from gateway  104  onto the power signals received from power source  110 , and demodulates communications signals received from cable  114  for transmission to gateway  104 . The communication signals can carry voice and/or data communications. 
         [0014]    Powerline-communications coupler  108  provides the combined power and communication signal via cable  114  to transformer  116 , which then provides the combined signal via powerline  118  to powerline-communications coupler  120 . Powerline-communications coupler  120  can include a filtering and optical conversion system, such as that described in more detail below in connection with  FIGS. 2A and 2B . Powerline-communications coupler  120  passes the filtered signal to transformer  124  via cable  122 . Transformer  124  can provide the filtered signal to building  128  via powerline  126 , and to another powerline-communications coupler  132  via powerline  130 . Accordingly, building  128  not only receives power via powerline  126  but also can access communication network  102 . 
         [0015]    Powerline-communications coupler  132  filters the combined power and communication signals and passes the filtered signals via cable  134  to transformer  136  for delivery to building  140  via powerline  138 . Powerline-communications coupler  132  also passes the combined signals via cable  142  to antenna  144  for delivery to buildings  148  and  152  via wireless communication links  146  and  150 , respectively. Thus, building  140  can receive both power and access to communication network  102  via powerline  138 . Additionally, buildings  148  and  152  can access communications network  102  without being connected by a powerline. 
         [0016]    It should be recognized that the system of  FIG. 1  is exemplary and that other arrangements are possible. Specifically, the system can include more than three powerline-communications couplers, more than one antenna, more than one communications network and/or the like. Additionally, although  FIG. 1  illustrates buildings including antennas for accessing communications network  102 , stationary or mobile wireless devices can likewise access communications network  102  via antenna  144 . Thus, antenna  144  can provide a communications cell, the size of which depends upon the power of transmissions from the antenna. Furthermore, it should be recognized that antenna  144  can be configured as a repeater or a base station. When configured as a repeater, antenna  144  will include at least a power amplifier. When configured as a base station, antenna will include at least a power amplifier, a modulator/demodulator and one or more transceivers. 
         [0017]      FIGS. 2A and 2B  are block diagrams of exemplary systems for filtering powerline signals in accordance with the present invention. The system of  FIG. 2A  includes optical converter  210  coupled to an optical multiplexer  220 , which in turn is coupled to an optical demultiplexer  230 . When it is desired to provide the communication signals to an antenna, then optical demultiplexer  230  is coupled to optical-to-wireless converter  240 . Otherwise, as illustrated in  FIG. 2B , converter  240  is omitted and the output from demultiplexer  230  is passed to transformer  250 . The arrangements of  FIGS. 2A and 2B  are not necessarily alternatives. Specifically, the filtering system of  FIGS. 2A and 2B  can be combined when used in powerline-communications coupler  132  such that the output of optical multiplexer can be coupled to both optical-to-wireless converter  240  and transformer  250 . 
         [0018]    The operation of the systems of  FIGS. 2A and 2B  begins with optical converter  210  receiving the combined power and communication signal and filtering the combined signal using filters  212   A - 212   N . Each of these filters includes two diodes,  214  and  216 , which can be PIN diodes, light emitting diodes (LEDs) and/or the like. As illustrated in  FIG. 2 , diode  214  is a dark diode and diode  216  is a light diode. The dark and light diodes  214  and  216  are tuned to particular amplitudes and frequencies. Specifically, referring now to  FIG. 3 , dark diode  214  is tuned to pass signals with a power level between 0 and P 2  and a frequency between F 2  and F 3 . All other signals input to dark diode  214  are filtered and not output from the diode. Similarly, light diode  216  is tuned to pass signals with a power level between 0 and P 1  and a frequency between F 1  and F 2 . All other signals input to light diode  216  are filtered and not output from the diode. The outputs from dark diode  214  and light diode  216  of each filter are combined to form the square wave illustrated in  FIG. 3 . 
         [0019]    Optical converter  210  includes a set of light and dark diodes tuned for each set of frequencies that carry communication signals. For example, assuming that the communication signals are in both the 1800 MHz band and the 2.4 GHz band, then a first filter  212   A  can have one diode tuned between 1800 MHz and 1850 MHz and a second diode tuned between 1850 MHz and 1900 MHz, and a second filter  212   B  can have one diode tuned between 2.3 GHz and 2.4 GHz and a second diode tuned between 2.4 GHz and 2.5 GHz. The amplitudes P 1  and P 2  are selected to be higher than the highest amplitude expected for a communication signal on the powerline. These amplitudes can also include an added hystersis amount above the highest amplitude expected for a communication signal on the powerline to account for any unexpected variations. 
         [0020]    The output of filters  212   A - 212   N  are passed to optical multiplexer  220 , which combines the filtered signals and passes them to optical demultiplexer  230 , which again separates the filtered signals into their respective frequency bands. Optical multiplexer  220  and demultiplexer  230  each include a number of lenses that, in addition to the multiplexing and demultiplexing, provide further noise reduction. When the signal is to be passed to an antenna then the signal is passed to optical-to-wireless converter  240 . When the signal is to be recombined with a power signal, then the output is passed to recombiner/transformer  250 . 
         [0021]    The present invention provides an exemplary system for removing noise from communication signals carried on powerlines. In-band noise that occurs at the same frequency as the carrier of the communication signals are filtered by controlling the amplitude passed by the filter and out-of-band noise is filtered by controlling the frequency of the filter. Additionally, the present invention does not require an external power source to operate the system. Instead, the power that is not passed by the filters can be used to power the filters, multiplexer, demultiplexer, optical-to-wireless converter and recombiner/transformer. 
         [0022]    The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.