Abstract:
Techniques for communicating between a data user and a destination through a mesh network. The mesh network includes a communication node having a downstream component logically connected over a downlink to provide communications for a data user and a plurality of upstream components. The plurality of upstream components includes a first upstream component that is logically connected to a first data destination over a first uplink. The communication node also has a controlling component that selects the first upstream component based on a first comparative link quality of the first uplink, where the first downstream component is electrically coupled to the first upstream component. The controlling component determines the first comparative link quality from a plurality of link quality metrics, where a corresponding weight is associated with each link quality metric.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to interconnecting communication nodes in a mesh network. 
       BACKGROUND 
       [0002]    A wireless mesh network is a communications network often made up of radio nodes organized in a mesh topology. The coverage area of the radio nodes working as a single network is sometimes called a mesh cloud. Access to this mesh cloud is dependent on the radio nodes working in harmony with each other to create a radio network. A mesh network should be reliable by offering redundancy. When one node can no longer operate, the rest of the nodes can still communicate with each other, directly or through one or more intermediate nodes. A wireless mesh network may be seen as a type of wireless ad hoc network, where all radio nodes are static and doesn&#39;t experience direct mobility. Wireless mesh architecture is often a first step towards providing high-bandwidth network over a specific coverage area. Wireless mesh architecture&#39;s infrastructure is, in effect, a router network minus the cabling between nodes. A mesh network is typically built of peer radio devices that don&#39;t have to be cabled to a wired port like traditional WLAN access points (AP) do. Mesh architecture typically sustains signal strength by breaking long distances into a series of shorter hops. Intermediate nodes may not only boost the signal, but cooperatively make forwarding decisions based on their knowledge of the network, i.e., performs routing. Such an architecture may, with careful design, may provide high bandwidth, spectral efficiency, and economic advantage over the coverage area. 
         [0003]    Consequently, there is a real need to facilitate effective operation of a mesh network in providing reliable communications for a data user. 
       SUMMARY 
       [0004]    The present invention supports a communication node having a downstream component logically connected over a downlink to provide communications for a data user. 
         [0005]    With an aspect of the invention, the communication node has a plurality of upstream components, the plurality of upstream components including a first upstream component being logically connected to a first data destination over a first uplink. The communication node also has a controlling component that selects the first upstream component based on a first comparative link quality of the first uplink, where the first downstream component is electrically coupled to the first upstream component. 
         [0006]    With another aspect of the invention, the communication node of claim  1 , the controlling component determines the first comparative link quality from a plurality of link quality metrics, where a corresponding weight is associated with each link quality metric. 
         [0007]    With another aspect of the invention, an upstream component includes an upstream radio and an upstream directional antenna. 
         [0008]    With another aspect of the invention, a downstream component includes a downstream radio and a downstream directional antenna. 
         [0009]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the clamed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]    The foregoing summary of the invention, as well as the following detailed description of preferred embodiments, is better understood when read in conjunction with the accompanying drawings, which are included by way of example, and not by way of limitation with regard to the claimed invention. 
           [0011]      FIG. 1  shows an architecture of a node in a mesh network in accordance with an embodiment of the invention. 
           [0012]      FIG. 2  a mesh network in accordance with an embodiment of the invention. 
           [0013]      FIG. 3  shows an evaluation matrix in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Overview 
         [0015]      FIG. 1  shows an architecture of node  100  in a mesh network in accordance with an embodiment of the invention. A communication system comprises a wireless mesh network (e.g., mesh network  200  as shown in  FIG. 2 ) having a plurality of communication nodes. Communication node  100  includes a logic element  109  interconnecting one or more upstream radios  105  and  107  with each upstream radio having an associated gain (e.g. directional) antennas  115  and  117 . The downstream radios  101  and  103  are connected to antennas  111  and  113 , respectively. Communication node  100  communicates with other communication nodes over uplinks  155  and  157  and downlinks  151  and  153 . 
         [0016]    Embodiments of the invention support directional antennas providing performance improvement while offering desirable characteristics of mesh network operation. However, embodiments of the invention may have a network topology with omnidirectional coverage patterns. 
         [0017]    Mesh Network 
         [0018]      FIG. 2  a mesh network in accordance with an embodiment of the invention. With this architecture, the local network is connected to global Internet by  201  through one or more links  210  and  211 . Load-sharing and fallback is provided by the operation of wired router, as is understood by one skilled in the art. 
         [0019]    Immediately below this layer are several “layer 1” access points  215  and  216 , each with its own connection to router  212 . Each of these is equipped with its own (typically directional) antennas  217  and  218 . 
         [0020]    Mesh network  200  include intermediate nodes  220 ,  221 ,  222 , and  223 , each equipped with one or more upstream antennas  230 - 235 , and one or more downstream antennas  246 . Mesh network  200  provides connection flexibility. For example, communication node  220  may connect directly with access point  215  via antenna  230 , and/or with access point  216  via antenna  231 . Similarly, communication nodes  221  and  222  may connect with both or either access points  215  and  216 . (In the following discussion, a communication node is referred as a node.) 
         [0021]    With embodiments of the invention, node  223  does not connect to either access points  215  and  215 , but rather can reach either of node  220  or node  221  through antenna  236 . Node  223  can also communicate with node  222  via antenna  237 . It could also be located as to reach access point  216  through either antenna. With embodiments of the invention, a layer of links may be included or skipped. 
         [0022]    Terminal nodes  250 ,  251 , and  252  are each equipped with one upstream antenna, corresponding to antennas  260 ,  261 , and  262 , respectively, and are connected to wired IP connections  270 ,  271 , and  272 , respectively. Terminal nodes  250 ,  251 , and  252  may also be equipped with two or more upstream antennas. In such a case, terminal module  250  may configure a connection to node  220  through antenna  241  and to node  221  through antenna  243 . Node  251  connects only to node  221 , while node  252  connects only to node  223  in the exemplary configuration shown in  FIG. 2 . 
         [0023]    Operation 
         [0024]    As illustrated in  FIG. 2 , each of the nodes  220 - 223  operate to connect traffic received on any of their downlink antennas, while terminal modules  250 - 252  operate to connect traffic received on wired IP connections  260 - 262 . The logic element  109  (as shown in  FIG. 1 ) within each node or terminal module operates so as to choose a selected connection for each of the nodes, terminal modules, or wired connection depending from it. A connection may be chosen separately. Thus, for example, node  221  may choose to connect terminal module  250  received on antenna  243  and to access point  215  through antenna  232 , while connecting node  223  received on antenna  243  to access point  216  through antenna  233 . 
         [0025]    Logic element  109  may employ one or more of several methods to differentiate among the links available as will be discussed. 
         [0026]    Link Quality Metrics 
         [0027]    There are several ways to choose among the links available at any one node in the mesh. These include the following:
       1. Signal Quality (Q): With this method, the quality of the signal is evaluated by circuitry associated with the link receiver corresponding to each available uplink. The signal quality must consist of more information than the commonly-used Receive Signal Strength Indicator (RSSI), since path impairments, e.g., multipath reception, may have a major effect that RSSI does not detect.   2. Number of hops (H): This may be considered as “logical distance”. The number of hops can often be determined from the appropriate field in the InterNet Protocol (IP) datagram header. It is often used in ordinary routers in wired systems.   3. Load Sharing (L): With this method, some packets are sent via one path, and some via the other (or others), with the proportion of packets being determined by the relative capacity of the various links available. This may be more difficult to manage from the downstream side of the link, since the router at the upstream side must be involved in the decision.   4. Ping Time (P): With this method, the logic circuit in the individual node sends regular IP “ping” requests to a known upstream address via each of the available uplinks, and measures the time for a response. This method is attractive because the ping time is responsive to many of the key elements—path quality, link speed, and link loading all affect the response time.   5. Physical Distance (D): This may be a useful measure, since the net interference possibility is proportional to the coverage area of the associated antenna pair and thus to the physical length of the link. This method can also be improved by using the length of the longest link as a weighting factor.   6. Timing Information (T): Radios may use timing information to coordinate the transmissions from the various nodes, so as to minimize interference and therefore maximize the use of the radio spectrum (extensions of this are described in another part of this application). This timing information may be extended from hop to hop in a mesh network, but may degrade according to the number of hops (links) and link quality. In the case, where more than one uplink is available, the timing from each link can be observed, where a “filtered reference” is developed from their combination (using for example multidimensional Kalman filtering). Each available link&#39;s timing may be compared to that reference to develop a link quality metric.       
 
         [0034]    Combinatorial Link Evaluation 
         [0035]      FIG. 3  shows evaluation matrix  300  in accordance with an embodiment of the invention. The selection of a link between an upstream component and data destination. With embodiments of the invention, the selection of a wireless link (e.g., link  231  as shown in  FIG. 2 ) is based on a combination of a plurality of characteristics (e.g., the link quality metrics as discussed above). The overall link figure of merit M may be determined by: 
         [0000]    
       
         
           
             
               
                 
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         [0036]    where the S x  factors are the weights corresponding to the associated parameter. 
         [0037]    With embodiments of the invention, the actual values in EQ. 1, the scaling for each parameter, and the actual parameters selected for evaluation may be different for different mesh networks. For example, if the observed packet error rate and the variation of packet arrival time are considered significant parameters for a mesh network, the corresponding factors may be added to the evaluation matrix in  FIG. 3 . 
         [0038]    Central Control 
         [0039]    In an alternative embodiment, control of each link can be asserted from a central point, where one of two command schemes may be implemented: automatic control, or manual control. In either case, logic at the central point may keep track of one or more of the aforegoing evaluation methods, either by querying logic element  109  in each node, or by direct measurement. With the manual method, this information may be presented for the use of a human operator, most desirably in the form of a system diagram or graph with the characteristics of each link clearly displayed, for instance, by showing better links as thicker lines. The human operator would then make the appropriate decisions about routing at each of the nodes, using for example a computer mouse or keyboard to indicate the links to be used. 
         [0040]    With the case of automatic implementation, the logic at the central control point may use the link quality information gathered as described above to choose the preferred link or links for each path, in the same manner as the automatic routing for a mapping program chooses a route for a driver to follow—by tracing a number of alternative routes, and picking the one with the best overall performance. The route so chosen may then be displayed on a computer screen, using the same sort of techniques described for presentation to a human operator. 
         [0041]    Alternative Implementations 
         [0042]    There of course is no reason to limit the type of system controlled by this logic to wireless system. Links may assume a wireless configuration, as shown in  FIGS. 1 and 2 . Moreover, links may be any data bearer or combinations thereof, such as coaxial cable, twisted pair, optical fiber, and so forth. 
         [0043]    As can be appreciated by one skilled in the art, a computer system with an associated computer-readable medium containing instructions for controlling the computer system can be utilized to implement the exemplary embodiments that are disclosed herein. The computer system may include at least one computer such as a microprocessor, digital signal processor, and associated peripheral electronic circuitry. 
         [0044]    Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.