Abstract:
The present invention discloses a system and method to use powerline and wireless communications for delivery of data and voice messages over IP (Internet Protocol). In order to achieve high reliability in communication service over powerline, wireless network is used as a redundant network to switch over in case of failover. The invention provides an integrated algorithm that provides seamless switching between powerline and wireless communication methods in real time.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to communications over electrical powerlines using one or more communication technology. 
       BACKGROUND OF THE INVENTION 
       [0002]    Powerline communication allows transmission of data and voice over the existing powerline network. The data and voice communications systems including wireless and powerlines require very high availability rates to facilitate minimum interruptions to the communication. The telecommunications industry uses the “five nines” 99.999% rate as the criteria for network availability. 
         [0003]    However, powerline and wireless, both being a non predictable medium, and highly susceptible to RF interference, are unable to reach that level of high availability without having built-in redundancy and failover. 
         [0004]    Communications using powerline medium require a mechanism to facilitate minimum interruptions and hence enhance data and voice communication. 
       SUMMARY OF THE INVENTION 
       [0005]    Accordingly, the present invention provides a method and system for communications over electrical powerlines where two communication technologies are used. The redundant communication methods used in the invention provides higher network availability between the nodes in a network. The invention uses a software algorithm to switch between a point to point powerline communication link and a point to point wireless link. 
         [0006]    The invention uses two communication technologies, wireless and powerline communications, for delivery of data and voice services over IP (Internet Protocol). Specifically, the invention makes use of an integrated algorithm that provides seamless switching between the two communications methods in real time. The switching between wireless and powerline communications is used for redundancy and failover capabilities. 
         [0007]    The software algorithm monitors the state of the powerline communications interface and switches to a wireless link when it crosses below a pre-configured threshold level. The same algorithm continues to monitor the state of the powerline communications interface and switches back from the wireless link when another pre-configured threshold level is crossed. 
         [0008]    This switching algorithm provides a built-in failover capability, protecting the system against temporary noise events that impede the powerline signal and bring down the powerline communication link. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]    The present invention is described with reference to the accompanying drawings, where: 
           [0010]      FIG. 1  shows a Powerline/Wireless network block diagram 
           [0011]      FIG. 2  shows a generic Powerline/Wireless system node block diagram 
           [0012]      FIG. 3  shows a second Powerline/Wireless node block diagram 
           [0013]      FIG. 4  is a switcher flow chart 
       
    
    
     DETAILED DESCRIPTION 
     Definitions 
       [0014]    The definitions used to explain the invention are provided below:
       STP software is a computer readable software.   OK represents positive response to the condition being checked.   NOK represents negative response to the condition being checked.   Wake Up represents activation of the component from its given state.   LONG represents a pre-configured duration as the maximum duration of time allotted for the system to be in a specific state.   MAX represents a pre-configured number as the maximum number of times a process can be attempted.   Sleep mode indicates that the Watch dog timer is in sleep mode   CU/WD represents Control Unit Watch Dog   Reboot represents the resetting of the powerline modem and reinitializing the software       
 
         [0024]    The present invention comprises of a method and system for communications wherein electrical powerlines and wireless communication media are used. The invention facilitates the usage of wireless communication medium as a failover option when the powerline communication crosses below a pre-configured threshold. 
         [0025]    The invention uses two communication technologies, wireless and powerline communications, for delivery of data and voice services over IP (Internet Protocol).  FIG. 1  illustrates a typical network segment configuration with nodes where each of the nodes in the network is equipped with one or two powerline modem interfaces and a single or dual wireless radio. In the figure, Node  101  communicates with upstream neighbor (US)  103  and Downstream Neighbor (DS)  102  using the powerline communication medium  105 ; the invention provides wireless as a failover communication medium  104 ; the circle in the figure represents the wireless cell coverage area for servicing wireless clients. 
         [0026]    The invention makes use of an integrated algorithm that provides seamless switching between the two communications methods in real time. The invention comprises of a software algorithm that applies to any point to point communications over powerline, using wireless transmission as an alternate communication method. The switching between wireless and powerline communications is used for redundancy and failover capabilities. 
         [0027]      FIG. 2  shows a generic Powerline/Wireless system node block diagram. Further,  FIG. 2  shows an implementation of switching between the powerline and wireless interfaces using the Spanning Tree Protocol (STP). There are two powerline modem interfaces for upstream and downstream powerline communications, represented by blocks B 1   204  and B 2   205  in the figure, are connected to the Switch  203  by the Ethernet ports, port  1  and port  2  respectively. The two wireless interfaces for upstream and downstream communications represented by blocks W 1   201  and W 2   202  in the figure are connected to the switch by the Ethernet ports, port  3  and port  4  respectively. The node communicates with its neighbors using the powerline communication medium  105 , the invention further provides wireless as a failover communication medium  104 . 
         [0028]      FIG. 3  shows a second Powerline/Wireless node block diagram. Further,  FIG. 3  shows a second implementation of the said switching where one or more wireless radio W 1   301  and W 2   302  are connected to a CPU motherboard  303  and through the motherboard to port  3  of the Ethernet switch  304 . The powerline modems represented by blocks B 1   305  and B 2   306  in the figure are connected to the switch  304  by the Ethernet ports, port  1  and port  2 . The node communicates with its neighbors using the powerline communication medium  105 , the invention further provides wireless as a failover communication medium  104 . 
         [0029]    In the above implementations of the invention, each port is assigned an initial cost (weight) by the software. The cost is used by the STP software to switch between interfaces connected to the Ethernet switch. The said interfaces according to the invention are the powerline interface and the wireless interface. The STP algorithm will always select the lowest cost path through the switch, and block all higher cost paths. 
         [0030]    In the said implementation, the initial cost values for the powerline interfaces are lower than the wireless interfaces to enable primary communications via powerline and secondary communications over wireless wherein the wireless communication protocol includes but is not limited to WDS, WiMAX (802.16, 802.16e), and WiFi (802.11a, 802.11b, 802.11g, 802.11n). 
         [0031]    The state of the powerline medium is measured in bit per carrier (BPC) or bit per symbol values (BPS) and is bounded by low and high threshold markers. The low and high threshold levels are pre-configured by the system operator. 
         [0032]    The condition for switching between the two said media is achieved by the STP software by measuring the state of the powerline as described hereinabove. Pre-configured thresholds are used to trigger the switching to enable the communication to be maintained wherein the thresholds are low and high. 
         [0033]      FIG. 4  illustrates an embodiment wherein the methodical steps and the conditions that the STP software uses to determine the switching between the communication channels are described. The figure explains the implementation of switching between powerline and wireless communication medium nodes wherein block diagrams of the powerline and wireless radio nodes for two of the implementations are provided by  FIG. 2  and  FIG. 3 . 
         [0034]    The initialization of the system involves the downloading of the conditioning unit (CU) configuration  401 . The status of the CU/WD is set to sleep  402  after the initialization. 
         [0035]    The CU/WD in the sleep mode  402  is activated as shown by Wake up in the figure. 
       Powerline Network Available 
       [0036]    The network availability is checked by using the ping utility  403 . If the availability of the network is verified by the ping utility as indicated by OK in the figure, the status of BPC is checked  404  by the STP software wherein it is used as a measurement of the state of the powerline medium as explained hereinabove. 
         [0037]    If the state of the BPC is certified to be OK by the STP software wherein the BPC number is above the lowest threshold of acceptable powerline communications where the threshold is pre-configured as described hereinabove, the state of the CU/WD is set to sleep  402 . 
         [0038]    If the state of the powerline is certified to be NOK by the STP software wherein the BPC number is below the lowest threshold of acceptable powerline communications where the threshold is pre-configured as described hereinabove, the STP software checks the duration for which the powerline has been in the said state  405  wherein the state is measured by the number of BPC. If the duration of the said state of powerline communication is not equal to or has not exceeded the LONG duration, the CU/WD is configured to be in sleep mode  402 . If the powerline has been in the said state for a duration equal to or exceeded the LONG duration, the secondary communication medium, wireless is enabled  410 . The said low BPC is an indication of a noise event that is interfering with the powerline signal and disrupting communication. 
       Network Unavailable 
       [0039]    The network availability is checked by using the ping utility  403 . If the availability of the program is not verified by the ping utility, as indicated by NOK in the figure, the number of attempts to verify the network availability as mentioned above is checked. If the number of attempts is not equal to or has not exceeded the MAX number, the status of CU/WD is configured to be in sleep mode  402 . 
         [0040]    If the number of said attempts exceeds MAX, the CU is Rebooted  407 . The STP software checks the status of the said Reboot, if the Reboot is certified as OK, the status of CU/WD is configured to be in sleep mode  402 . 
         [0041]    If the CU is not rebooted properly, the number of attempts to perform the said Reboot is checked against the maximum number of attempts permissible by the STP software  409 . If the number of attempts to reboot is not equal to or has not exceeded the maximum number, the CU is rebooted  407  again. If the number of attempts to reboot is equal to or has exceeded the maximum number of attempts, the secondary communication medium, wireless is enabled  410 . 
       Switching to Wireless Communication Medium 
       [0042]    If the STP software blocks the powerline medium for communication due to low cost indicating low BPC number, the communication switches to alternate medium, wireless provided by this invention through the Ethernet switch. The STP software assigns high cost to the powerline modem interface and blocks the respective port and the communication is switched to the wireless interface. In  FIG. 4 , wireless is enabled  410  by the STP software when the primary communication medium, powerline is blocked as described hereinabove. 
       Switching to Powerline Communication Medium 
       [0043]    The STP software continues to monitor the status of powerline and switches the communication to it if the number of BPC is above the high threshold limit which is configured as described above. 
         [0044]    The status of the CU/WD is configured to sleep  411 . The CU/WD is activated as shown by Wake up in the figure and the status of the powerline is checked by measuring the number of the BPC  412 . If the powerline is certified as NOK by the STP software, the duration for which the powerline has been in the said state is checked  415 . If the state of the powerline in the state with the number of BPC being below the high threshold limit is not equal to or has not exceeded the LONG duration, the CU/WD is configured to be in sleep mode  411 . If the powerline as mentioned above has been in the said state for duration equal to or has exceeded the LONG duration, the CU is rebooted  416 ; the STP software then configures the CU/WD to sleep mode  411 . 
         [0045]    If the STP software certifies the number of BPC to be OK where the number of BPC is higher than the pre-configured high threshold limit indicating acceptable powerline communications following a noise event that affected powerline communication  405 . If the powerline is certified as OK as described hereinabove, the duration for which the powerline has been in the said state is checked. If the powerline has not been in the said state for a LONG duration of time, the state of the CU/WD is configured to sleep  411 . If the powerline has been in the said state for duration equal to or has exceeded the LONG duration, the wireless is disabled  414 . The STP software assigns low cost to the already blocked powerline modem port, unblocks the powerline modem port and enables powerline communication. The STP software configures the CU/WD to sleep  402 . 
         [0046]    Although the present invention has been described with particular reference to a specific example, variations and modifications of the present invention can be effected within the spirit and scope of the following claims.