Mesh network requirements have evolved from their military origins as requirements have moved from battlefields to enterprise networking environments. Growing demands for Time Sensitive, Video, Voice and M2M streams require packets be moved at high throughput and low latency. Additionally, Outdoor Enterprises e.g. Military, Mining, Video Surveillance, require costly Cellular or Satellite links be efficiently distributed over larger areas ("hops") for machinery ("things"), operating at the "edge"
IOT-Ready Mesh Networks must also be future-proof: supporting legacy and emerging communication protocols. Fog resident Machine Controllers will require a time sensitive SDN-aware fabric. These real time mesh networks for industrial automation and the Industrial Internet will be required to be Scalable, Synchronous, Secure, Future-Proofed and SDN-Aware.
1. Tree Based Multi-Radio Mesh Architectures Scale.
Fig. 1: Ad hoc (Peer-to-Peer) Mesh Architectures vs. Meshdynamics Scalable Tree Based Architecture.
Three evolutions of mesh architectures are shown above. Note: First and Second, both use a single radio as backhaul:
First Generation: 1-Radio Ad Hoc Mesh (left). This network uses one radio channel both to service clients and backhaul. This architecture provides the worst of all the options, as expected, since both backhaul and service compete for bandwidth.
Second Generation: Dual-Radio with Single Radio Ad-Hoc meshed backhaul (center). A single radio ad hoc mesh is still servicing the backhaul, packets traveling toward the Internet share bandwidth at each hop along the backhaul path with other interfering mesh backhaul nodes - all-operating on the same channel. "Peer-to-Peer" don't scale. More
Third Generation: 3-Radio Meshdynamics Mesh (right). Provides separate backhaul and service functionality and dynamically manages channels of all uplink and downlink radios so that backhauls (and "hops") are on non-interfering channels. More
The Two Radio, (Uplink and Downlink) Backhaul, mitigates RF interference using non-interfering channel assignments.
2. Conventional Single Channel Backhauls Cannot Scale
Fig.2: (left) Competing mesh products suffer from ½ Bandwidth loss with each hop. Enlarge.
Fig 3: (right): Meshdynamics Distributed Control Software engenders Frequency Agility everywhere. Enlarge
With one backhaul radio available for relaying packets, all nodes communicate with each other on one radio channel. For data to be relayed from mesh node to mesh node, that node must repeat it in a store-and-forward manner. A node first receives the data and then retransmits it. These 2 operations cannot occur simultaneously because, with only a single radio channel, simultaneous transmission and reception would interfere with each other.
This inability - to simultaneously transmit and receive - is a serious disadvantage. If a node cannot send and receive at the same time, it loses ½ of its bandwidth as it attempts to relay packets up and down the backhaul path. A loss of ½ with each hop implies that after 4 hops, a user would be left with (½*½*½*½) = 1/16 of the bandwidth available at the Ethernet link: 1/(2H) relationship defines the fraction of the bandwidth available to a user after H hops, see Figure 2. More
Meshdynamics multi-radio backhaul is active in mining tunnels with string of pearls topologies 64+ hops deep.
3. Managing RF Interference and Jamming Proactively
Switching to another channel contains local interference at one "dirty" section of the network. With one radio backhauls, this is not possible: the entire network is on the same channel and switching to another channel is just not possible. (Fig 3)
The performance of single channel backhauls is thus heavily compromised in RF polluted environments or under malicious attacks. Military field trials with our dual channel backhaul demonstrated frequency agility, ensuring that the network is active - even with malicious RF interference. Our blue backhaul radios (Fig. 3) simply switch to non-interfering channels. More
Figs 4: A wired switch stack (tree) Fig 5: Meshdynamics Wireless Equivalent of Tree Architecture
Enterprise class network switches use an efficient tree structure for routing. The switch stack tree like structure uses simpler routing mechanisms - trees have no loops and complications of looping are thus eliminated. More
As wired network trees scales up, the wired networks scale accordingly - more switches are added to continue to segment and manage (divide and conquer) the expanding collision domains. For broadcasting trees with height H of O(logn), routing overhead in tree based routing protocols is O(nlogn). It "keeps up" with Moore's Law. Tree based networks are future-proof.
Similarly, as Meshdynamics "wireless switch stacks" scale up, the dynamic channel management algorithms, running in each mesh node, change the RF radio channels, to segment and manage the shared RF mediums, also as O(nlogn).
Single radio Peer-to-peer networks have routing protocol overhead O(n2). Update times grow exponentially as n increases. When clients or mesh nodes are moving, routing tables are not in sync: higher latency and jitter in time sensitive traffic. More
Our nodes always connect as branches of a dynamic tree. Tree based routing is scalable, efficient, and deterministic.
5. Abstraction Layer Supports Legacy and Emerging Wireless Radio Protocols
Future Proofing: Decoupling the logical channel-selection and topology-definition processes from the specific physical radio in this fashion delivers distributed dynamic radio intelligence benefits for current as well as emerging radio standards. More
For our OEM software licensees. this substantially decreases time to market and better manufacturing scale, reducing both development- and unit cost over custom development, while still supporting newer protocols, Sharp QCX-300 Example
6. Modular Multi-Radio Design Securely connects Edge Devices
Fig 6: Configurable Board supports up to 4 radios Fig 7: Interoperability between 5 GHz and 2.4 GHz sub trees
Our products take Channel and Frequency Agility one step further. The "RF robot" control software runs at a radio-abstracted layer: the same mesh control supports radios operating on diverse wireless communication protocols.
Fig. 6 shows how this level of flexibility is leveraged in the MD4000 Modular Mesh Products. There are 4 mini-PCI slots on the board, two on the bottom and two on top. Each of the four slots can house a different frequency radio. This opens up some interesting possibilities including 2.4 GHz backhaul sub tree being part of a mesh tree with 5.8 GHz backhauls.
Since the service and backhaul radios are distinct, service radios may bridge over from a 5.8 GHz backhaul to 2.4 GHz backhaul – forming a new 2.4 GHz branch of the tree, Fig. 7. The 4325 Mobility Relay node on the bottom left has joined the mesh – even though the upper links are 5.8 GHz (blue) – through the service radio (pink). More
In Infrastructure mode, device to device M2M messaging " goes up the tree". When (not if) IOT devices are compromised, the uplink radios of the corrupted branches are temporarily "cut off". This is not possible in single radio, peer-to-peer networks.
7. Embedded Machine Controllers For Local Control Loops
Fig. 8: Machine controller applications, in mesh nodes, orchestrating local and remote (supervisory) control loops. Enlarge
Machine controller applications ("apps"), running on the mesh nodes, monitor and control enterprise assets at the network edge. M2M messaging is latency and jitter aware. A low latency Pub/Sub messaging framework manages periodic packet shuttle services. Performance is analyzed in the cloud. We assume intermittent, unreliable, cloud connectivity. More
Our radio and protocol abstraction layer enables "apps" to manage a plethora of both IP and Non IP ("Chirp") devices. More
A device and communication protocol abstracted framework emerges, capable of tight integration with "machine controller" applications - on the mesh nodes - to orchestrate sensor-actuator interactions and feedback command and control loops.
New mesh requirements e.g. more hops to cover larger areas, efficient bandwidth distribution, low latency and jitter for Video, Voice and M2M communications, have given rise to new mesh architectures. Meshdynamics patented multi-radio backhaul architectures delivers consistent throughput and more-deterministic performance needed to meet these new requirements.
Our device and protocol abstractions support distributed dynamic radio intelligence, frequency agility, automated channel selection, dynamic topology configuration, and seamless extensions for the network "edge".. These capabilities provide single framework solutions for larger scale and diverse application environments at the edge: e.g. Industrial Internet of Things. More
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