Abstract:
The presently disclosed subject matter is directed to methodologies, apparatuses, and systems for providing cell router (relay) failure detection in a mesh network. Individual cell relays heading up cells within a mesh network transmit synchronization signals including as a portion thereof a counter value. Nodes with the cells monitor the counter value and search for a new connection to a central facility if the counter value fails to update within a predetermined value.

Description:
FIELD OF THE SUBJECT MATTER 
     The presently disclosed subject matter relates to information management within automated metering infrastructure (AMI) architecture. More particularly, the presently disclosed subject matter relates to improvements in cell router failure detection through provision of a counter functionality within a cell router synchronization signal in an automated metrology infrastructure (AMI) environment. 
     BACKGROUND OF THE SUBJECT MATTER 
     Automatic meter reading (AMR) systems are generally known in the art. Utility companies, for example, use AMR systems to read and monitor customer meters remotely, typically using radio frequency (RF) communication. AMR systems are favored by utility companies and others who use them because they increase the efficiency and accuracy of collecting readings and managing customer billing. For example, utilizing an AMR system for the monthly reading of residential gas, electric, or water meters eliminates the need for a utility employee to physically enter each residence or business where a meter is located to transcribe a meter reading by hand. 
     There are several different ways in which some current AMR systems are configured, including fixed network and mobile network systems. In a fixed network, encoder-receiver-transmitter (ERT) type endpoint devices at meter locations communicate with readers that collect readings and data using RF communication. There may be multiple fixed intermediate readers located throughout a larger geographic area on utility poles, for example, with each endpoint device associated with a particular reader and each reader in turn communicating with a central system. Other fixed systems can utilize a system including repeaters or relay devices that expand the coverage area for each reader, cell control units (CCUs) that concentrate data and forward the same on to the system head end using a wide area network (WAN), or other suitable communication infrastructure. In simple fixed systems, only one central reader may be utilized with all of the endpoint devices. In a mobile network AMR environment, a handheld, vehicle-mounted, or otherwise mobile reader device with RF communication capabilities is used to collect data from endpoint devices as the mobile reader is moved from place to place. 
     One design criterion for utility meter reading systems involves meter data management (MDM) systems that generally involve a centralized processing model. Such centralized processing models, however, are subject to various problems including, but not limited to, system performance, scalability, data latency, fault tolerance, complexity, infrastructure cost, and batch processing issues. 
     For example, performance throughput and scalability can generally only be maintained by providing parallel processing technology. Data latency is becoming more of an issue as expectations are rapidly approaching real-time. Fault tolerance requirements demand that sufficient computing power, including provision of disaster recovery sites, be provided. A whole host of concerns arise from commonly used centralized solutions including complexity, the high cost of powerful computer infrastructure, and the inherent requirements imposed on centralized solutions from batch processing of data and other infrastructure communications requirements. 
     In view of such concerns, it would be advantageous, therefore, to provide methodologies and associated apparatuses/devices wherein failure of critical components may be quickly identified. 
     SUMMARY OF THE SUBJECT MATTER 
     In view of the recognized features encountered in the prior art and addressed by the presently disclosed subject matter, improved methodology, apparatus, and systems are provided for detecting cell relay failure in a mesh network. 
     In one present exemplary embodiment, the presently disclosed subject matter broadly speaking relates to methodology for providing cell router failure detection. In such methodology, a value based on a value received from a cell relay is periodically updating, compared to a previously received value, and determines whether communications with the cell relay have failed based on the results of such comparison. In selected embodiments, the value may be a numeric value or a time value. In such exemplary embodiments, the value may be received by the node as a portion of a synchronization frame. 
     In instances where the value is a numeric value, exemplary present methodology may call for determination of whether communications with the cell relay have failed by determining whether the numerical value has changed within a predetermined period of time. 
     In other embodiments, the value corresponds to a time value and the exemplary methodology may in those instances determine whether communications with the cell relay have failed by determining whether the time value has changed within a predetermined period of time. 
     In certain of the foregoing presently disclosed exemplary methodologies, the cell relay may be operative in a mesh network associated with a collection engine, other such cell relays, and a plurality of associated nodes. Still further, in some such methodologies, at least some of the associated nodes may be respectively associated with metering endpoints, and the collection engine may be operative for collecting metering data from such metering endpoints. 
     The presently disclosed subject matter equally relates to both methodology and associated or corresponding apparatus/device subject matter. For example, another presently disclosed exemplary embodiment may relate to network enabled node devices. In such embodiments, an exemplary such node device may include a counter configured to be updated based on a received network signal, a comparator configured to compare a counter value with a previous counter value, and a processor configured to search for network access based on results of a comparison of the counter value and a previous counter value. 
     In selected such embodiments, the exemplary counter may be updated based on a portion of a network synchronization frame. In certain embodiments, such portion may contain a numerical value while in other embodiments such portion may contain a time value. 
     In some presently disclosed exemplary embodiments, the processor may search for network access if the counter fails to be updated within a predetermined time period while in other embodiments, the processor may search for network access if the time value has not changed within a predetermined period of time. 
     In other presently disclosed exemplary embodiments of the foregoing, such device may be configured for operation with a mesh network having a data collection engine, at least one cell relay, and a plurality of such node devices. 
     Various presently disclosed exemplary embodiments also may relate to a mesh network. In such embodiments, an exemplary such mesh network may comprise a collection engine, at least two cell relays, and at least one node respectively associated with each of the at least two cell relays. In such embodiments, the at least one node respectively associated with each of the at least two cell relays forms with its associated cell relay a cell within the network. In such arrangements, the cell relays preferably transmit synchronization signals including at least a counter value to nodes within their own cell. Such nodes monitor the counter value and search for network access to the collection engine upon failure to receive updated counter values from its associated cell relay within a predetermined time period. 
     In selected such embodiments, an exemplary cell relay may transmit a numeric counter value, while in other embodiments an exemplary cell relay may transmit a time counter value. In certain specific embodiments, an exemplary node may be forbidden (or prevented) from searching within the cell of its previously associated cell relay during a predetermined time period. 
     In still other of the foregoing exemplary embodiments, at least some of the associated nodes may be respectively associated with metering endpoints, and the collection engine may be operative for collecting metering data from such metering endpoints. 
     Additional objects and advantages of the presently disclosed subject matter are set forth in, or will be apparent to, those of ordinary skill in the art from the detailed description herein. Also, it should be further appreciated that modifications and variations to the specifically illustrated, referred and discussed features, elements, and steps hereof may be practiced in various embodiments and uses of the subject matter without departing from the spirit and scope of the subject matter. Variations may include, but are not limited to, substitution of equivalent means, features, or steps for those illustrated, referenced, or discussed, and the functional, operational, or positional reversal of various parts, features, steps, or the like. 
     Still further, it is to be understood that different embodiments, as well as different presently preferred embodiments, of the presently disclosed subject matter may include various combinations or configurations of presently disclosed features, steps, or elements, or their equivalents (including combinations of features, parts, or steps or configurations thereof not expressly shown in the figures or stated in the detailed description of such figures). Additional embodiments of the presently disclosed subject matter, not necessarily expressed in the summarized section, may include and incorporate various combinations of aspects of features, components, or steps referenced in the summarized objects above, and/or other features, components, or steps as otherwise discussed in this application. Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the remainder of the specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the presently disclosed subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  illustrates partial block diagrams of a representative cell relay (router) and a representative node (meter device) constructed in accordance with the presently disclosed subject matter; 
         FIG. 2  is a block diagram overview illustrating, in part, portions of a known Advanced Metering System (AMS) with which are otherwise practiced devices in which the presently disclosed subject matter may be incorporated; and 
         FIG. 3  is a flow chart illustrating exemplary presently disclosed methodology for providing cell router (or relay) failure detection. 
     
    
    
     Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features, elements, or steps of the presently disclosed subject matter. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As discussed in the Summary section, the presently disclosed subject matter is particularly concerned with methodologies (and associated and/or corresponding apparatus/device subject matter) for providing improvements in cell router failure detection through provision of a counter functionality within a cell router synchronization signal in an automated metrology infrastructure (AMI) environment. With initial reference to  FIG. 2 , there is illustrated a block diagram overview illustrating, in part, a known Advanced Metering System (AMS)  200  illustrating the use of a centralized meter data management system  292 . The known portions of such  FIG. 2  illustration primarily relate to the middle and left sides thereof, coupled with the public backhaul and related connections to the collection engine, as described in commonly owned published US Patent Application Publication No. 20080068215 A1, the complete disclosure of which is fully incorporated herein by reference for all purposes. 
       FIG. 2  illustrates for exemplary purposes only a first RF LAN cell, with multiple member nodes organized into three levels. In such exemplary arrangement/system, respective meter devices (or metering endpoints)  210 ,  220 ,  230 ,  232 ,  240 ,  242 ,  250 ,  252 ,  254 ,  256 ,  260 ,  262 ,  264 ,  266 , Cell Relay  202 , and Collection Engine  290 , preferably may have C12.22 network addresses. In the illustrated representation, meter data management system  292  is implemented so as to communicate over the Utility LAN  294  to Collection Engine  290  via Web Services. Communications between Cell Relay  202  and Utility LAN  294  in the illustrated representative arrangement variously involve Public Backhaul  280  and firewall  296 . 
     In such configuration, the meter data acquisition process begins with the Meter Data Management System  292  initiating a request for data. Such operation is done through a web services call to Collection Engine  290  and may be performed without knowledge of the configured functionality of the variously associated end devices. Collection Engine  290  analyzes the request for data (such as metering data from the respective metering endpoints), and formulates a series of multicast (or broadcast) data requests. Such requests may then be sent out either directly to the device, or to Cell Relay  202  that relays the message out to all appropriate nodes. Broadcast and multicast messages may be sent by Cell Relay  202  to all members of the cell, such as by either an AMS RF LAN-level broadcast, or by the Cell Relay  202  repeating the message. 
     In instances when a message is broadcast, multicast, or specifically addressed to an individual network node (meter), a protocol stack for the RF LAN may advantageously take the message and construct a node path for the message to take before actually transmitting the packet. Such pre-constructed node path allows Cell Relay  202  to push a message down through the tree of the cell without creating redundant radio messages. 
     As may be seen from the foregoing, all messages between the various meter devices  210 ,  220 ,  230 ,  232 ,  240 ,  242 ,  250 ,  252 ,  254 ,  256 ,  260 ,  262 ,  264 ,  266 , Cell Relay  202 , and Collection Engine  290  may pass in both directions through Cell Relay  202 . Thus, it may be seen that any failure occurring at Cell Relay  202  may have a serious impact on communications (in either direction) between the various meter devices and Collection Engine  290 . 
     In accordance with the presently disclosed subject matter, and as more fully explained herein, if Cell Relay  202  fails and there are no other changes, the various meter devices  210 ,  220 ,  230 ,  232 ,  240 ,  242 ,  250 ,  252 ,  254 ,  256 ,  260 ,  262 ,  264 ,  266  will not be able to communicate with collection engine  290 . During normal operation of the various meter devices (nodes), such nodes may not immediately realize that Cell Relay  202  has failed, but when they do so realize, they will try to find alternate routes through other nodes in close proximity to each other. 
     In the present exemplary configuration and with further reference to  FIG. 2 , if, for example, meter  220  realizes that Cell Relay  202  has failed, or, more particularly, that communications with the collection engine can not be carried out, such meter may attempt connections with an adjacent meter or, alternatively, with a cell headed up by another cell relay (for example, representative Cell Relay  202 B). In such instances, meter (node)  220  may attempt to connect via path  270  directly to Cell Relay  202 B or to another meter (node), for example device  230 B, by way of path  272 . Alternatively, meter  220  may attempt to connect to any of the meter devices (nodes)  210 B,  230 B,  232 B,  250 B,  252 B,  254 B, or  256 B of alternate cell or cells in an effort to regain communications capability with collection engine  290 . Such a process or approach of attempting to find a new connection path may actually take quite a while in very densely populated meter environments. 
     With present reference to subject  FIG. 1 , there are illustrated partial block diagrams of a Cell Relay  102  (router) and a meter device (node)  120  constructed in accordance with the presently disclosed subject matter. The presently disclosed subject matter corresponds to a failsafe mechanism whose implementation guarantees a maximum time after failure of the cell relay or router to which a node is assigned in which a meter (node) starts looking for another router (cell relay). The maximum time may be defined by the user (that is, the utility company) that owns or administers the meter. 
     As illustrated in  FIG. 1 , Cell Relay  102  may include a counter  104  that is periodically incremented by the router, generally (although not necessarily) by way of commands from processor  108 . The count from counter  104  is propagated through the network with each synchronizing frame from synchronization frame generator  106 . Those of ordinary skill in the art will appreciate that counter  104  and sync frame generator  106  may correspond to hardware and/or software within Cell Relay  102  and, if embodied as software may be stored in a memory associated with processor  108  by which the software is run. 
     Network nodes, such as node  120 , upon receiving a synchronization frame including the associated count value, may have their own counter  124  updated. If such updated counter value is higher than the last count value received by the node, and if the period of time between any currently received count value and the last count value heard does not exceed a predetermined time limit, the node determines that its cell relay (router) is still active. On the other hand, if no update to the counter is received within a predetermined time period, the node will conclude that its Cell Relay (for example, such as Cell Relay  202  of  FIG. 2 ) has failed or is otherwise out of service due, for example, to loss of contact with the cell relay, and such node will begin in accordance with presently disclosed subject matter to search for another available Cell Relay. 
     During such searches, the node associated with the old cell relay (router) is forbidden (prevented) from searching within the cell of its previously associated cell relay during a predetermined time period. Such time period preferably amounts to a window defined such that the window is long enough for all the nodes to realize the counter update has not occurred. Thus, for example, if node (meter)  220  loses contact with its cell relay  202 , all nodes associated with cell relay  202  (including meters  210 ,  230 ,  232 ,  240 ,  242 ,  250 ,  252 ,  254 ,  256 ,  260 ,  262 ,  264 , and  266 ) are excluded as possible new communications partners. In such way, node  220  is forced to seek out, for example, cell relay  202 B or nodes (meters) associated with cell relay  202 B including, exemplary node  230 B. 
     With present reference to subject  FIG. 3 , there is presented a flow chart generally  300  illustrating an exemplary method for providing cell router failure detection in accordance with presently disclosed subject matter. As illustrated, an exemplary method in accordance with the presently disclosed subject matter calls for, in step  302 , updating a counter (value) based on a count (value) received from a cell relay. Such counts or values are received by the individual nodes (meters) currently associated with a particular cell relay. 
     At step  304  the updated count received is compared to a previously received count (value) and then in step  306  a determination is made as to whether the associated cell relay has failed based on the results of the comparison. Such comparisons may take into consideration the differences in numeric values of the updated and previous counts, and in some instances may consider whether the numeric values have actually changed within a predetermined time period. In some instances, the numeric values may correspond to a time value. In such manner, if the previously stored count is found to not have changed for some predetermined time, or if a time value received from the cell relay differs significantly from a time value stored at the node (meter), a determination may be made in accordance with the presently disclosed subject matter that the cell relay has failed. In such instances, the node (meter) may then attempt to connect with the network by a different path. 
     In some exemplary configurations, the presently disclosed subject matter may be used to reduce the time required for nodes to associate with a new cell to, for example, about thirty minutes following failure or otherwise loss of contact with their previously associated cell, as compared to as much as several hours absent implementation of the presently disclosed subject matter. It should be appreciated that the time frame to begin a search may be controlled in part based on the count and time comparison conducted by comparator  128 , for example, incorporated into node  120 . 
     While the presently disclosed subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the presently disclosed subject matter as would be readily apparent to one of ordinary skill in the art.