WO2007103837A1 - Métrique de trajet de bande passante effective et procédé de calcul de trajet pour des réseaux maillés sans fil à liens câblés - Google Patents

Métrique de trajet de bande passante effective et procédé de calcul de trajet pour des réseaux maillés sans fil à liens câblés Download PDF

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Publication number
WO2007103837A1
WO2007103837A1 PCT/US2007/063247 US2007063247W WO2007103837A1 WO 2007103837 A1 WO2007103837 A1 WO 2007103837A1 US 2007063247 W US2007063247 W US 2007063247W WO 2007103837 A1 WO2007103837 A1 WO 2007103837A1
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Prior art keywords
path
wireless
link
links
wireless links
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PCT/US2007/063247
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English (en)
Inventor
Bhargav Bellur
Ravi Prakash
Amar Singhal
Jorgeta Jetcheva
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Firetide, Inc.
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Publication date
Priority claimed from US11/618,073 external-priority patent/US7768926B2/en
Application filed by Firetide, Inc. filed Critical Firetide, Inc.
Priority to GB0817802A priority Critical patent/GB2449826B/en
Priority to CA2645336A priority patent/CA2645336C/fr
Priority to CN2007800127496A priority patent/CN101421982B/zh
Publication of WO2007103837A1 publication Critical patent/WO2007103837A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/66—Arrangements for connecting between networks having differing types of switching systems, e.g. gateways

Definitions

  • the invention may be implemented in numerous ways, including as a process, an article of manufacture, an apparatus, a system, a composition of matter, and a computer readable medium such as a computer readable storage medium or a computer network wherein program instructions are sent over optical or electronic communication links.
  • these implementations, or any other form that the invention may take, may be referred to as techniques.
  • the order of the steps of disclosed processes may be altered within the scope of the invention.
  • the Detailed Description provides an exposition of one or more embodiments of the invention that enable improvements in performance, efficiency, and utility of use in the field identified above.
  • the Detailed Description includes an Introduction to facilitate the more rapid understanding of the remainder of the Detailed Description.
  • the Introduction includes Example Embodiments of systems, methods, and computer readable media in accordance with the concepts taught herein. As is discussed in more detail in the Conclusions, the invention encompasses all possible modifications and variations within the scope of the issued claims.
  • Fig. 1 illustrates an embodiment of a mixed wireless and wired mesh network.
  • Fig. 2 illustrates portions of the mesh network of Fig. 1 for an example calculation of an effective bandwidth metric.
  • Fig. 3 illustrates portions of the mesh network of Fig. 1 for an example calculation of optimal paths.
  • FIGs. 4A-D illustrate various aspects of an embodiment of a path computation technique.
  • FIG. 5 illustrates selected details of hardware aspects of an embodiment of a node.
  • Fig. 6 illustrates selected details of software aspects of an embodiment of a node.
  • word labels including but not limited to: first, last, certain, particular, select, and notable
  • word labels may be applied to separate sets of embodiments; as used herein such labels are expressly not meant to convey quality, or any form of preference or prejudice, but merely to conveniently distinguish among the separate sets.
  • multiple embodiments serve to illustrate variations in process, method, and/or program instruction features
  • other embodiments are contemplated that in accordance with a predetermined or a dynamically determined criterion perform static and/or dynamic selection of one of a plurality of modes of operation corresponding respectively to a plurality of the multiple embodiments. Numerous specific details are set forth in the following description to provide a thorough understanding of the invention.
  • Enhanced mesh network performance is provided by computation of a path metric with respect to multi-hop paths between nodes in a mesh network and determination of a path through the mesh network that is optimal according to the path metric.
  • Information such as in the form of data packets, is communicated in the mesh network according to the determined path.
  • Nodes in the mesh network are enabled to communicate via one or more wireless links, one or more wired links, or both.
  • Each wireless link is tuned to a specific channel (i.e. the channel is assigned to or associated with the wireless link), and all wireless links use a single channel or alternatively various wireless links use a plurality of channels, such that communication is enabled to occur in parallel over the channels.
  • the assignment of channels to wireless links is permanent, in some embodiments, or temporary (varying over time), in other embodiments.
  • the path metric optionally includes an effective bandwidth path metric having elements (listed from highest to lowest conceptual priority) including an inverse of a sustainable data rate, a number of wireless links, and a number of wireless and wired links.
  • the sustainable data rate is a measure of communication bandwidth that is deliverable by a path for a significant period of time. A higher sustainable data rate indicates a relatively better path.
  • the number of wireless links is a measure of the amount of wireless communication resources used along the path. A lower number of wireless links indicates a relatively better path.
  • the number of wireless and wired links (or total links) is a measure of wireless and wired communication resources used along the path. A lower number of total links indicates a relatively better path.
  • the path through the mesh network is managed by one or more mesh routing protocols.
  • the routing protocols optionally stores topological information about the mesh network according to links, where a link between a pair of nodes in the mesh network indicates the pair of nodes is enabled to communicate with each other.
  • a path between the pair of mesh nodes traverses other mesh nodes and thus includes one or more links.
  • a path having a single link indicates the pair of mesh nodes are enabled to communicate directly with each other, and a path having two or more links indicates corresponding intermediary nodes.
  • a routing protocol optionally computes a path between two mesh nodes based on links (and associated link characteristics) the routing protocol is aware of.
  • the path computation optionally discovers a path having a highest (or relatively higher) throughput (or bandwidth).
  • the path computation optionally finds a path having a lowest (or a relatively lower) traversal latency.
  • the path computation optionally determines a path having a lowest (or relatively lower) packet loss.
  • Various path computations are directed to select a path according to any computation of maximized bandwidth, minimized latency, and minimized packet loss, according to various embodiments.
  • the computed path is then optionally used for delivering traffic between the nodes the path is between.
  • Links in a mesh network are wireless, wired, or both, and each node in the mesh implements any number and combination of wireless and wired interfaces. Transmissions via the wireless interfaces are broadcast in nature, so any two wireless interfaces that are tuned to the same channel and are within transmission range of each other optionally form a wireless link. Similarly, any two wired interfaces that are coupled together optionally form a wired link.
  • Wireless transmissions on the same channel interfere with each other when transmitting nodes are within interference range of each other.
  • wireless transmissions on non- overlapping channels do not interfere with each other.
  • a node having more than one wireless interface, each assigned to a unique channel is enabled to simultaneously communicate via each of the wireless interfaces.
  • Wired transmissions in contrast, do not interfere with transmissions on any other wired or wireless links.
  • Each link has an associated link metric or cost that reflects desirability of the link with respect to forwarding traffic, i.e. a link having a lower cost is relatively more attractive for communicating data.
  • Some metrics have associated multiple characteristics or sub-metrics that are combinable in various ways to arrive at an overall link metric.
  • Link sub-metrics include any combination of raw data rate, link utilization, tendency of the link to lose data (referred to as lossy-ness hereinafter), available bandwidth, and other characteristics of the link.
  • a path metric or cost is a function of the individual link metrics, costs, and characteristics associated with the links of the path.
  • Various path metrics are computed for the same path according to differently chosen individual link metrics, costs, and characteristics, and differing manners of combining the individual link metrics, costs, and characteristics, according to various embodiments.
  • Fig. 1 illustrates an embodiment of a mixed wireless and wired mesh network having a collection of nodes each including at least one wireless interface (such as Node IOOA having wireless interface 121 A operating on channel 1). Some of the nodes include more than one wireless interface (such as Node IOOS having wireless interfaces 121S and 122S operating on channels 1 and 2, respectively).
  • Some of the nodes include a wired interface (such as Nodes IOOC and IOOS having respective wired interfaces coupled to wired link 110CS). Communications traveling via wireless links on the same channel (such as wireless links 11 IBS and 11 IDS on channel 2) may interfere with each other, but do not interfere with transmissions on other channels. Communications carried via wired links (such as via wired links IIOCS and 11 OBE) do not interfere with each other or any other wireless link.
  • a wired interface such as Nodes IOOC and IOOS having respective wired interfaces coupled to wired link 110CS.
  • element identifiers beginning with "100” are associated with nodes of the mesh network (such as Nodes IOOA and 100B).
  • Element identifiers beginning with "12” are representative of wireless interfaces, with the third character of the identifier describing a channel associated with the wireless interface, and the last character of the identifier indicating the node the wireless interface is included in.
  • An example of a wireless interface identifier is wireless interface 125F operating on channel 5 and included in Node 10OF.
  • Element identifiers starting with "111” represent wireless links formed via wireless interfaces, with the fourth and last characters of the identifier indicating nodes the wireless link couples.
  • An example of a wireless link is wireless link 111EH coupling Nodes IOOE and 10OH.
  • Element identifiers starting with "110" are used for wired links, with the fourth and last characters of the identifier indicating nodes the wired link couples.
  • An example of a wired link is wired link 110BE coupling Nodes IOOB and IOOE.
  • a first illustrative combination of a system comprising means for determining an effective wireless bandwidth for a path according to one of a plurality of techniques, the path having a length of contiguous wireless links; and means for selecting one of the techniques based at least in part on the length.
  • the first illustrative combination further comprising means for determining a best path through a mesh network that includes the contiguous wireless links.
  • the foregoing illustrative combination further comrpising means for routing traffic according to the best path.
  • the mesh network includes a plurality of nodes.
  • at least two of the nodes are enabled to route a portion of the traffic via a wired link.
  • at least a pair of the nodes are enabled to route the portion of the traffic via a wireless link.
  • the wireless link is one of the contiguous wireless links.
  • the first illustrative combination wherein the means for determining comprises means for calculating the effective wireless bandwidth as a function of a reciprocal of an inverse effective data rate, the inverse effective data rate being a sum of respective reciprocal bandwidths corresponding to each of the contiguous wireless links.
  • the first illustrative combination wherein the means for determining comprises means for calculating the effective wireless bandwidth as a function of a plurality of inverse effective data rates, each of the inverse effective data rates corresponding to a respective set of contiguous wireless links, the sets of contiguous wireless links including all sequences of wireless links in the contiguous wireless links having a respective length equal to a threshold.
  • the function selects a minimum bandwidth based at least in part on the inverse effective data rates.
  • the foregoing illustrative combination wherein the minimum bandwidth corresponds to a minimum of reciprocals of the inverse effective data rates.
  • a second illustrative combination of a system comprising a processor; at least one interface coupled to the processor; wherein the processor is enabled to execute instructions to determine an effective wireless bandwidth of a path according to one of a plurality of techniques selected based at least in part on a length of the path; and wherein the path is via a plurality of contiguous wireless links equal in number to the length.
  • the interface is at least one of a wireless interface and a wired interface.
  • the processor is further enabled to execute further instructions to determine a best path through a mesh network that includes the contiguous wireless links.
  • the processor is further enabled to execute additional instructions to route traffic according to the best path.
  • the processor is included in one of a plurality of nodes included in the mesh network.
  • the at least one interface implements an endpoint of at least one link of the contiguous wireless links.
  • a third illustrative combination of a method comprising of computing an effective wireless bandwidth for a path according to one of a plurality of techniques selected based at least in part on a length of the path; and wherein the path is via a plurality of contiguous wireless links equal in number to the length.
  • a fourth illustrative combination of the third illustrative combination further comprising computing a best path through a mesh network that includes the contiguous wireless links.
  • a fifth illustrative combination of the fourth illustrative combination further comprising routing traffic according to the best path.
  • any of the second, third, and sixth illustrative combinations wherein a first one of the techniques is selected if the length is less than a threshold.
  • a second one of the techniques is selected if the length is greater than the threshold.
  • the second one of the techniques is selected if the length is equal to the threshold.
  • at least one of the techniques includes calculating the effective wireless bandwidth as a function of a reciprocal of an inverse effective data rate, the inverse effective data rate being a sum of respective reciprocal bandwidths corresponding to each of the contiguous wireless links.
  • the function selects a minimum bandwidth based at least in part on the inverse effective data rates.
  • the foregoing illustrative combination wherein the minimum bandwidth corresponds to a minimum of reciprocals of the inverse effective data rates.
  • the foregoing illustrative combination wherein the wireless link is one of the contiguous wireless links.
  • a ninth illustrative combination of a system comprising means for evaluating a first cost associated with traversing a first path of links in a mesh network, the first path being associated with a source node and a destination node of the mesh network; means for evaluating a second cost associated with traversing a second path of links in the mesh network, the second path being associated with the source and the destination nodes; wherein the last link of the first path is a wired link; and wherein the last link of the second path is a wireless link.
  • the foregoing illustrative combination wherein the first cost is a first current cost and the first path is a first current path; and further comprising means for replacing a first minimum cost having an associated first best path with the first current cost and replacing the first best path with the first current path if the first current cost is less than the first minimum cost.
  • the foregoing illustrative combination wherein the second cost is a second current cost and the second path is a second current path; and further comprising means for replacing a second minimum cost having an associated second best path with the second current cost and replacing the second best path with the second current path if the second current cost is less than the second minimum cost.
  • the foregoing illustrative combination further comprising means for selecting a routing path that corresponds to the respective best path associated with the minimum of the first and the second minimum costs.
  • the foregoing illustrative combination further comprising means for routing traffic along the routing path.
  • the ninth illustrative combination wherein the means for evaluating the first cost comprises means for determining an effective bandwidth for any contiguous wireless links along the first path.
  • the ninth illustrative combination wherein the means for evaluating the second cost comprises means for determining an effective bandwidth for any contiguous wireless links along the second path.
  • a tenth illustrative combination of a system comprising a processor; at least one interface coupled to the processor; wherein the processor is enabled to execute instructions to determine respective first and second costs associated with traversing respective first and second paths of links in a mesh network; wherein the last link of the first path is a wired link; and wherein the last link of the second path is a wireless link.
  • the foregoing illustrative combination wherein the interface is at least one of a wireless interface and a wired interface.
  • the foregoing illustrative combination wherein each of the paths are associated with a source node and a destination node.
  • the foregoing illustrative combination wherein the first cost is a first current cost and the first path is a first current path; and wherein the processor is further enabled to execute further instructions to replace a first minimum cost having an associated first best path with the first current cost and to replace the first best path with the first current path if the first current cost is less than the first minimum cost.
  • the second cost is a second current cost and the second path is a second current path; and wherein the processor is enabled to further execute additional instructions to replace a second minimum cost having an associated second best path with the second current cost and to replace the second best path with the second current path if the second current cost is less than the second minimum cost.
  • the processor is further enabled to execute other instructions to select a routing path that corresponds to the respective best path associated with the minimum of the first and the second minimum costs.
  • An eleventh illustrative combination of a method comprising evaluating respective first and second costs associated with traversing respective first and second paths of links in a mesh network; wherein the last link of the first path is a wired link; and wherein the last link of the second path is a wireless link.
  • each of the paths are associated with a source node and a destination node.
  • the foregoing illustrative combination wherein the second cost is a second current cost and the second path is a second current path; and further comprising if the second current cost is less than a second minimum cost associated with a second best path, then replacing the second minimum cost with the second current cost and replacing the second best path with the second current path.
  • the foregoing illustrative combination further comprising selecting a routing path that corresponds to the respective best path associated with the minimum of the first and the second minimum costs.
  • the foregoing illustrative combination further comprising routing traffic along the routing path.
  • the eleventh illustrative combination wherein the evaluating of the first cost comprises determining an effective bandwidth for any contiguous wireless links along the first path.
  • the eleventh illustrative combination wherein the evaluating of the second cost comprises determining an effective bandwidth for any contiguous wireless links along the second path.
  • the foregoing illustrative combination wherein the first cost is a first current cost and the first path is a first current path; and wherein the operations further comprise if the first current cost is less than a first minimum cost associated with a first best path, then replacing the first minimum cost with the first current cost and replacing the first best path with the first current path.
  • the foregoing illustrative combination wherein the second cost is a second current cost and the second path is a second current path; and wherein the operations further comprise if the second current cost is less than a second minimum cost associated with a second best path, then replacing the second minimum cost with the second current cost and replacing the second best path with the second current path.
  • the operations further comprise selecting a routing path that corresponds to the respective best path associated with the minimum of the first and the second minimum costs.
  • the operations further comprise routing traffic along the routing path.
  • a thirteenth illustrative combination of a method comprising determining an effective wireless bandwidth for a path according to a first technique if a length of the path is less than a threshold; and determining the effective wireless bandwidth according to a second technique if the length is not less than the threshold; and wherein the path is via a plurality of contiguous wireless links equal in number to the length.
  • the thirteenth illustrative combination wherein the first technique comprises calculating the effective wireless bandwidth as a function of a reciprocal of an inverse effective data rate, the inverse effective data rate being a sum of respective reciprocal bandwidths corresponding to each of the contiguous wireless links.
  • the second technique comprises calculating the effective wireless bandwidth as a function of a plurality of inverse effective data rates, each of the inverse effective data rates corresponding to a respective set of contiguous wireless links, the sets of contiguous wireless links including all sequences of wireless links in the contiguous wireless links having a respective length equal to the threshold.
  • the foregoing illustrative combination wherein the function selects a minimum bandwidth based at least in part on the inverse effective data rates.
  • a fourteenth illustrative combination of a method comprising determining a best path through a mesh network, the best path being via a plurality of wireless links; routing traffic via the best path; wherein the determining comprises computing an effective wireless bandwidth for a number of contiguous wireless links of the wireless links.
  • the fourteenth illustrative combination wherein the computing of the effective wireless bandwidth comprises if the number of contiguous wireless links is less than a threshold, then determining the effective wireless bandwidth as a reciprocal of a sum of reciprocal bandwidths corresponding to each of the contiguous wireless links.
  • the foregoing illustrative combination wherein the computing of the effective wireless bandwidth further comprises if the number of contiguous wireless links is not less than the threshold, then determining the effective wireless bandwidth according to a minimum of a set of sums, each of the set corresponding to a respective reciprocal of a respective sum of a respective set of reciprocal bandwidths for each possible path having a respective length equal to the threshold and being encompassed by the contiguous wireless links.
  • a path metric along a path that includes wireless links is dependent on the level of wireless interference along the path because interference reduces throughput and increases packet latency and loss. Interference, in some usage scenarios, depends on the channel assignment of the wireless links and on the order of wireless and wired links along the path because a wired mesh link may separate the sequence of wireless links before the wired link in the path and the sequence of wireless links after the wired link in the path into non- interfering zones. Therefore, the path metric takes into account not only the individual metrics of each link along a path, but also the order the links appear along the path.
  • a path metric called "effective bandwidth” is defined that takes into account both wireless and wired links, and incorporates the available bandwidth along each link in the path along with effects of interference of consecutive wireless links in the path that are assigned to the same channel.
  • a path computation technique is then defined that given a set of links, computes the best possible paths from a node to all other nodes reachable through the set of links, according to the effective bandwidth path metric.
  • the path metric incorporates the effects of interference along a multi-hop path that includes wireless and wired links, where each node optionally has more than one wireless and/or wired interface.
  • the effective bandwidth path metric has three components, in lexicographic (or priority) order: inverse of the sustainable data rate, number of wireless links, and total number of links.
  • the inverse of the sustainable data rate is the most significant component of the path metric and is a measure of the inverse of the data rate sustainable on the path.
  • the metric incorporates the current data rate of each link along the path and also depends on the order in which wired and wireless communications links appear in the path, as well as the channel assigned to each wireless link. The lower the inverse of the sustainable data rate (e.g., the higher the sustainable data rate), the better the path.
  • the number of wireless links along a path is a measure of the amount of wireless communication resources that are used along the path, and reflects the level of interference generated in the network and possibly along the path itself, as well as the probability of packet loss. That is, the more wireless links a packet has to traverse, the more likely the packet will be dropped due to full router queues, or that the packet will collide with other packets if the link is wireless. The smaller the number of wireless links along a path, the more desirable the path.
  • the total number of links is the least significant part of the path metric, and is a measure of the amount of (wired and wireless) network resources that are used along the path and also reflects the probability of packet loss. The lower the total number of links in a path, the more desirable the path.
  • Delta 0.1, 0.2, or some other similar small value
  • the inverse sustainable data rate is computed based on the available bandwidth at each link.
  • the available bandwidth is computed by a routing protocol or by a link layer based on information collected at the link layer and also optionally at a network layer. Possible inputs into the computation of the available bandwidth metric are raw data rate, link utilization, link availability, and lossy-ness. Information on the metric associated with a link and its channel assignment is discovered by the routing protocol along with discovering the link itself.
  • a path is divided into a set of segments (or sub-paths) such that the metric of each segment is computable independently of the metrics of the other segments, and the metric for the entire path is the minimum of the bandwidths of the segments.
  • segment boundaries are chosen to coincide with wired links, since in some usage scenarios the wired links separate a path into non-interfering segments.
  • all the wireless links within a segment that are assigned to the same channel do not interfere with each other. This occurs, for example, when the links are not within interference range of one another.
  • the interference range is larger than the transmission range, and in some situations is twice as large as the transmission range.
  • Intfllops is a small integer, such as 4 or 5. See the section "Contiguous Wireless Links Sustainable Data Rate", located elsewhere herein, for details of a computation of the sustainable data rate across a contiguous sequence of wireless links on the same channel assuming bandwidth degradation after IntfHops is ignorable.
  • Fig. 2 illustrates portions of the mesh network of Fig. 1 for an example calculation of an effective bandwidth metric.
  • a five hop path is illustrated, from Node IOOG to Node lOOC, and is analyzed according to two segments: X (from Node IOOG to Node 100B) and Y (from Node IOOB to Node lOOC). The sustainable data rate along the path is computed according to the two segments X and Y.
  • the (inverse of) the sustainable data rate for the entire path from Node IOOG to Node lOOC is thus the scalar value: maximum(InvSRSegmentX, InvSRSegmentY).
  • the effective bandwidth metric calculation then combines the inverse sustainable data rate for the path along with the number of wireless and total links for the path. According to the path in Fig. 2, the number of wireless links along the path is three, and the total number of links is five. Path Computation
  • An embodiment of a path computation technique is based on the foregoing effective bandwidth metric and computes optimal paths from a source node src to all other reachable nodes in a mesh network. The embodiment is described for a special case where each node of the mesh has at most one wireless interface and all of the wireless interfaces are assigned to the same channel.
  • the path computation technique maintains, for any node x, selected variables associated with up to two paths.
  • the variables maintained optionally include respective cost and predecessor information.
  • the variables maintained omit other information about the paths (such as nodes along each path).
  • a prefix of "0" denotes a wired (or Ethernet) interface while a prefix of "1" denotes a wireless interface.
  • the paths are: Path[0](x): The currently known minimum cost path from node src to node x such that the last link is an Ethernet link; and Path[l](x): The currently known minimum cost path from node src to node x such that the last link is a wireless link.
  • Cost[i](x) is represented by a 3 -tuple where the first entry is a vector.
  • Cost[i](x) (vectorInvSR[i](x), num_wireless _links ⁇ (x), num_hops[i](x)).
  • Cost[i](x) (InvSR[i](x), num_wireless_links[ ⁇ (x), num_hops[i](x)).
  • the path computation technique maintains predecessor information for paths Path[0](x) and Path[ ⁇ ](x).
  • the representation of the predecessor of a node includes an identifier of a parent node and a type of shortest path from the parent node to the node (i.e. via a wired/Ethernet or wireless interface).
  • the path computation technique proceeds by "marking" nodes one at a time. A set of “unmarked” nodes is maintained, and during each iteration a one node y among the unmarked nodes having the minimum Costiy) is "marked”. Then variables Cost[0] (x) and Cost[l](x) of all unmarked nodes that are neighbors of the marked node y are updated (or reduced) via a process termed relaxation (see the section "Path Computation Implementation", located elsewhere herein, for more information). Appropriate variables are maintained and updated for up to two paths (corresponding to wired and wireless terminating links), thus enabling computation of an effective bandwidth path metric corresponding to possible optimal paths.
  • the computation also estimates bandwidth degradation across a contiguous sequence of wireless links by maintaining additional variables for a path ending in a wireless link: WirelessHops[l](v) - Number of contiguous wireless links immediately preceding node v in the best known path to node v such that the last link is a wireless link; and WirelessTotalInvSR[l](v) - Inverse of the sustainable data rate on the entire sequence of contiguous wireless links immediately preceding node v in the best known path to node v such that the last link is a wireless link.
  • the path computation assumes that any two wireless links (of a contiguous sequence of wireless links) that are on the same channel do interfere with each other. Even though interference within a contiguous sequence of wireless links ceases (or in some circumstances is ignorable) after links are Intfllops apart, the assumption tends to penalize paths with more wireless links even when the paths have higher sustainable data rates than paths with fewer wireless links. The assumption is in addition to penalizing paths having a similar sustainable data rate but a higher number of wireless links (i.e. the number of wireless links is second in the lexicographic ordering associated with path comparison). Use of more wireless resources creates interference for nearby links and networks and in some usage scenarios is undesirable.
  • the path computation assumes a penalty on a path proportional to the number of wireless links in the path while assuming interference between wireless links is negligible after IntfHops.
  • the proportional penalty reduces apparent sustainable data rate by a fixed value at each wireless link even though the respective wireless link do not, in some usage scenarios, reduce the sustainable data rate when there is no additional interference experienced. See the section "Contiguous Wireless Links Sustainable Data Rate", located elsewhere herein, for further details.
  • Fig. 3 illustrates portions of the mesh network of Fig. 1 for an example calculation of optimal paths.
  • the portion is shown with three of the nodes having only a single wireless interface and a fourth node having a pair of wireless interfaces.
  • Three of the wireless interfaces operate on a single first channel (channel 2) and the remaining wireless interfaces operate on a non-interfering second channel (channel 1).
  • the resulting communication pathways are three wireless links, two that interfere with each other (wireless links HlBK, and 111BS) and one that does not interfere with the others (wireless link HIES).
  • the portion is shown with only a single wired link (wired link HOBE).
  • bandwidth(lllBS) 40
  • bandwidth(lllES) 30
  • bandwidth(l 1 OBE) 30
  • bandwidth(lllBK) 40.
  • the path computation considers two paths from Node IOOS to Node 10OB.
  • the paths correspond to the previous link being a wired (Ethernet) link or the previous link being a wireless link.
  • the path computation further considers two paths (with the previous link being respectively wired and wireless) from Node IOOS to Node 10OK.
  • the second candidate Cost(Node IOOK) is (maximum(l/30, 1/30, 1/40), 2, 3) or (1/30, 2, 3). The minimum of the two candidates is selected as (1/30, 2, 3).
  • Figs. 4A-D illustrate various aspects of an embodiment of the path computation technique.
  • G (V, E): A directed weighted graph, with a vertex set V (corresponding to nodes of the mesh network) and an edge set E (corresponding to wired and wireless links of the mesh network;
  • src The source node for which all shortest paths are being computed;
  • S The set of nodes for which all shortest (best) paths have been determined;
  • Q A queue containing all nodes from V not already in S (i.e.
  • Adj[v] The neighbors of node v (i.e. those nodes reachable from v in one wired or wireless hop); and b(u, v): The available link bandwidth on link(w, v).
  • the path metric corresponding to a path is a 3 -tuple: (vectorlnvSR, num_wireless Jinks, numjiops)
  • vectorlnvSR is a vector representation of the inverse of the sustainable data rate along the path — in a single wireless interface scenario, the vector is size 2 (i.e. m + 1 where m is one) where member 0 of the vector denotes Ethernet (wired) and member 1 denotes wireless
  • num_wireless Jinks is the number of wireless links along the path
  • numjiops is the total number of hops (or links), wired and wireless, along the path.
  • Cost[0] (v) be the (current minimum) cost metric of the best known path to node v such that the last link is an Ethernet (or wired) link.
  • Pred[0](v) (parent[0](v), typejrom_parent[0](v)) is the predecessor of node v for Path[0](v), where parent[0](v) is the identifier of the parent node, and typejrom_parent[0](v) indicates the type of path (i.e, Ethernet or wireless) to be taken from the parent.
  • C(Mt[I ](v) be the (current minimum) cost metric of the best known path to node v such that the last link is a wireless link.
  • Pred[ ⁇ ](v) (parent[ ⁇ ](v), typejrom_parent[ ⁇ ](v)) is the predecessor of node v for Path[l](v).
  • WirelessHops[l](v) is the number of contiguous wireless links immediately preceding node v in the best known path to node v such that the last link is a wireless link
  • WirelessTotalInvSR[l](v) is the inverse of the sustainable data rate on the entire sequence of contiguous wireless links immediately preceding node v in the best known path to node v such that the last link is a wireless link.
  • Cost(v) denote the minimum of Cost[0] (v) and Cost[ 1 ] (v) .
  • Cost(v) minimum(CW[O] (v), Cost[ 1 ] (v)) using the foregoing lexicographic-computed comparison for 3-tuples.
  • Fig. 4A illustrates a top-level flow diagram of an embodiment of the path computation.
  • Flow begins (“Start” 401) and continues to set various variables relating to the computation to starting values ("Initialize” 402). It is then determined if there are any remaining nodes to process ("More Nodes?" 403). If not (“No” 403N), then processing is complete ("End” 499). If so ("Yes", 403Y), then processing continues to select another node to process ("Next Node” 404). Best path information for all nodes adjacent to the selected node (i.e. one link away according to the topology of the mesh network) is then updated ("Process Node Neighbors" 405). Processing then flows back to determine if there are additional nodes to process ("More Nodes" 403).
  • ⁇ F; where vectorlnvSR is of size two and all elements therein are set to either zero or infinity as appropriate.
  • Fig. 4B illustrates an embodiment of processing associated with "Process Node Neighbors" 405 of Fig. 4A. Processing begins (“Start” 405A) and continues to check if all neighbor nodes have been completed ("All Processed?" 405B). If so ("Yes" 405BY), then processing is complete ("End” 405Z). If not ("No" 405BN), then processing proceeds to select a remaining node ("Next Neighbor Node” 405C). Flow then continues to determine whether the link type associated with the selected node is wired (i.e. Ethernet) or wireless ("Link Type?" 405D).
  • Processing associated with "All Processed?" 405B is described by the following pseudo-code: For each node v in Adj[u] where processing associated with "Next Neighbor Node” 405C skips node v if v is already present in S.
  • Fig. 4C illustrates an embodiment of processing associated with either of "Evaluate Wired Link” 405E and “Evaluate Wireless Link” 405F of Fig. 4B.
  • Processing begins (“Start” 405EF.1) and proceeds to determine if a new best path is available based on a link currently being evaluated.
  • the currently evaluated link is processed twice, according to two contexts, a first context where the last link in the path thus far is a wired link, and a second context where the last link in the path thus far is a wireless link.
  • the first context (“Evaluate Wired Last Link Path" 405EF.2) and the second context (“Evaluate Wireless Last Link Path” 405EF.3) are evaluated independently and in any order (such as in parallel as illustrated), in some embodiments.
  • Evaluating bandwidth of a set of contiguous wireless links includes computing an effective bandwidth metric by assuming a wireless link interferes only with other wireless links that are on the same channel and within IntfHops wireless links away.
  • results of the computation is used in evaluating paths (such as computations performed with respect to one or more elements of Fig. 4B and Fig. 4C).
  • the results is used by a routing protocol that compares paths to each other and computes the effective bandwidth metric for respective paths.
  • Intfliops is an (assumed or estimated) number of hops beyond which there is no additional bandwidth degradation due to interference between contiguous wireless links operating on the same channel, and in some scenarios is a small integer such as 4 or 5.
  • Fig. 5 illustrates selected details of hardware aspects of an embodiment of a node.
  • the illustrated node includes Processor 510 coupled to various types of storage, including volatile read/write memory (Memory Banks 501A and 501) via Dynamic Randomly Accessible read/write Memory (DRAM) Memory Interface 502, and non-volatile read/write memory (FLASH 503 and Electrically Erasable Programmable Read Only Memory (EEPROM) 504).
  • the processor is further coupled to Ethernet Interface 521 providing a plurality of Ethernet Ports 522 for establishing wired links, and via PCI Interface 505 to Wireless Interfaces 525A and 525B for providing radio communication of packets for establishing wireless links.
  • one or more of the wireless interfaces are compatible with an IEEE 802.11 wireless communication standard (such as any of 802.1 Ia, 802.1 Ib, and 802.1 Ig).
  • one or more of the wireless interfaces operate (in conjunction with any combination of other hardware and software elements) to collect statistics with respect to neighboring nodes of a mesh. The statistics include any combination of signal strength and link quality, in various embodiments.
  • one or more of the wireless interfaces are configurable to drop all packets below a settable Received Signal Strength Indicator (RSSI) threshold.
  • RSSI Received Signal Strength Indicator
  • one or more of the wired interfaces are 10Mb, 100Mb, lGgb or 10Gb compatible.
  • Node implementations include any combination of wireless and wired interfaces, such as only a single wireless (or wired) interface, or one of each type, or two of each type. Other equivalent embodiments of a node are contemplated, as the illustrated partitioning is only one example.
  • the illustrated node optionally functions as any one of the mesh nodes illustrated in Fig. 1 (such as any of Node A 10OA, Node S 10OS, and so forth).
  • the illustrated wireless interfaces of Fig. 5 enable communication between nodes and provide low-level transport for packets moving between elements of the mesh, such as by implementing wireless interfaces 121S and 122S associated with Node S IOOS of Fig. 1.
  • the Ethernet ports of Fig. 5 provide for wired communication between nodes, such as for implementing wired link 11 OCS associated with Node C IOOC and Node S IOOS of Fig. 1.
  • the processor fetches instructions from any combination of the storage elements (DRAM, FLASH, and EEPROM) and executes the instructions. Some of the instructions correspond to execution of software associated with operations relating to processing for effective bandwidth path metric computation and path computation using the metric.
  • Fig. 6 illustrates selected details of software aspects of an embodiment of a node.
  • the illustrated software includes Network Management System (NMS) Manager 650 interfacing to Network Interface Manager 640 and Fault, Configuration, Accounting, Performance, and Security (FCAPS) Manager 630.
  • NMS Network Management System
  • FCAPS Fault, Configuration, Accounting, Performance, and Security
  • the NMS interfaces between management software operating external to the node and software operating internal to the node (such as various applications and FCAPS).
  • the Network Interface Manager manages physical network interfaces (such as the Ethernet and Wireless Interfaces).
  • the Network Interface Manager assists the NMS in passing dynamic configuration changes (as requested by a user) through the management software to FCAPS.
  • FCAPS includes functions to store and retrieve configuration information, and FCAPS functions serve all applications requiring persistent configuration information.
  • FCAPS in some embodiments, assists in collecting fault information and statistics and performance data from various operating modules of the node. FCAPS optionally passes any portion of the collected information, statistics, and data to the NMS.
  • Kernel Interface 601 interfaces the Managers to Routing and Transport Protocols layer 610 and Flash File System module 602.
  • the Routing Protocols include all or portions of processing relating to effective bandwidth path metric computation and path computations using the metric, as well as general processing relating to operation as a node of the mesh and forwarding packets.
  • the Transport Protocols include TCP and UDP.
  • the Flash File System module interfaces to Flash Driver 603 that is illustrated conceptually coupled to FLASH file hardware element 503A that is representative of a flash file system stored in any combination of FLASH 503 and EEPROM 504 of Fig. 5.
  • Layer-2 Abstraction Layer 611 interfaces the Routing and Transport Protocols to Ethernet Driver 621 and Radio Driver 625.
  • the Ethernet Driver is illustrated conceptually coupled to Ethernet Interface 521 of Fig. 5.
  • the Radio Driver is illustrated conceptually coupled to Wireless Interfaces 525, representative of Wireless Interfaces 525A and 525B of Fig. 5.
  • the software also includes a serial driver.
  • the software is stored on a computer readable medium (such as any combination of the DRAM, FLASH, and EEPROM elements of Fig. 5), and is executed by the processor of Fig. 5.
  • the partitioning illustrated in Fig. 6 is an example only, and many other equivalent arrangements of layers and modules are contemplated.
  • interconnect and function-unit bit-widths, clock speeds, and the type of technology used may generally be varied in each component block.
  • the names given to interconnect and logic are merely illustrative, and should not be construed as limiting the concepts taught.
  • the order and arrangement of flowchart and flow diagram process, action, and function elements may generally be varied.
  • the value ranges specified, the maximum and minimum values used, or other particular specifications are merely those of the illustrative embodiments, may be expected to track improvements and changes in implementation technology, and should not be construed as limitations.
  • Specific variations may include, but are not limited to: differences in partitioning; different form factors and configurations; use of different operating systems and other system software; use of different interface standards, network protocols, or communication links; and other variations to be expected when implementing the concepts taught herein in accordance with the unique engineering and business constraints of a particular application.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)

Abstract

La présente invention concerne un procédé permettant d'améliorer la performance de réseau maillé par le calcul d'une métrique de trajet par rapport à des trajets multisauts entre noeuds dans un réseau maillé qui est optimal selon la métrique de trajet. Une information est communiquée dans le réseau maillé selon le trajet déterminé. Des noeuds dans le réseau maillé sont activés pour communiquer via un ou des liens sans fil et/ou un ou des liens câblés. La métrique de trajet comporte éventuellement une métrique de trajet de bande passante effective ayant des éléments (classés par priorité conceptuelle du plus élevé jusqu'au plus faible) comprenant une inversion d'un débit de données durable, une pluralité de liens sans fil, et une pluralité de liens câblés. Le débit de données durable est une mesure de bande passante de communication qui est apte à être délivrée par un trajet pour une période de temps. L'interférence entre des liens sans fil opérant sur le même canal est prise en compte.
PCT/US2007/063247 2006-03-09 2007-03-04 Métrique de trajet de bande passante effective et procédé de calcul de trajet pour des réseaux maillés sans fil à liens câblés WO2007103837A1 (fr)

Priority Applications (3)

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GB0817802A GB2449826B (en) 2006-03-09 2007-03-04 Effective bandwidth path metric and path computation method for wireless mesh networks with wired links
CA2645336A CA2645336C (fr) 2006-03-09 2007-03-04 Metrique de trajet de bande passante effective et procede de calcul de trajet pour des reseaux mailles sans fil a liens cables
CN2007800127496A CN101421982B (zh) 2006-03-09 2007-03-04 用于具有有线链路的无线网状网络的有效带宽路径度量和路径计算方法

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IN627DE2006 2006-03-09
IN627/DEL/2006 2006-03-09
US11/618,073 US7768926B2 (en) 2006-03-09 2006-12-29 Effective bandwidth path metric and path computation method for wireless mesh networks with wired links
US11/618,073 2006-12-29

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US8948015B2 (en) 2005-07-21 2015-02-03 Firetide, Inc. Method for enabling the efficient operation of arbitrarily interconnected mesh networks
US8559447B2 (en) 2005-07-30 2013-10-15 Firetide, Inc. Utilizing multiple mesh network gateways in a shared access network
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KR101068667B1 (ko) 2009-09-28 2011-09-28 한국과학기술원 히든 노드 및 감지 간섭을 고려한 라우팅 경로 설정 방법, 그 시스템 및 이를 기록한 기록매체
US20110304425A1 (en) * 2010-06-09 2011-12-15 Gm Global Technology Operations, Inc Systems and Methods for Efficient Authentication
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CN113507413A (zh) * 2021-07-22 2021-10-15 中国联合网络通信集团有限公司 一种路由优化方法、装置及计算设备
CN113507413B (zh) * 2021-07-22 2022-07-29 中国联合网络通信集团有限公司 一种路由优化方法、装置及计算设备

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