Rajant Mesh Backhaul

Overview

Most open-pit mines already run a Rajant Kinetic Mesh. BreadCrumb nodes on haul trucks, shovels, drills and light plants form a peer network that moves with the operation, and the autonomous haulage systems are validated on it. A private network has to work alongside the mesh rather than replace it.

The mesh's limit is hop count. InstaMesh routes over half-duplex unlicensed radios, so every hop adds latency and roughly halves the throughput that remains, and reaching the pit bottom from the ROM pad can take five to eight of them. The 2.4 and 5.8 GHz bands are crowded as well, with drills, dozers and everything else unlicensed on site.

A private LTE cell on a crest or a ROM-pad mast covers kilometers of pit in a single RF hop, on spectrum the mine licenses and controls. Attaching BreadCrumbs to that cell gives InstaMesh a second route to choose from. The mesh still handles the last hop to moving equipment, and the cellular link carries the traffic behind it. Rajant sells a module built for this.

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How It Works

The mesh keeps the last hop. The LTE path is an additional route InstaMesh can choose, not a replacement for the RF links.

What each component does

Component	Role in this workflow
BreadCrumb node	The mesh radio on a truck, shovel, drill or light plant. Peers with every other node in range
InstaMesh	Rajant's routing protocol. Scores every available link and selects a path per packet
Cellular attachment	An LTE Enhance module, a Peregrine BreadCrumb with the modem built in, or a GXC CPE on the node's Ethernet port
Onyx AP	The cell, sited for reach across the pit rather than for capacity at a point
Onyx Edge	Terminates the session and bridges it, so mesh nodes stay in one Layer 2 domain
APN on a VLAN	The mesh transport network, carried without NAT so nodes remain directly addressable
Local breakout	Keeps mesh traffic on the mine network, never leaving site
Onyx Portal	Per-node attachment, session state and link quality, alongside the mesh's own view
AHS and fleet systems	The dispatch, autonomy and telemetry platforms the mesh was built to carry

The path, hop by hop

#	From → To	Interface	What happens
1	Truck BreadCrumb → neighbor nodes	unlicensed RF	The local mesh forms as it always has. Nothing changes here
2	BreadCrumb → cellular attachment	Ethernet	The node sees an ordinary wired peer link
3	Attachment → Onyx AP	LTE Uu, uplink-leaning	One RF hop, on licensed spectrum, replacing several mesh hops
4	Onyx AP → Onyx Edge	backhaul	Standard IP transport from the cell
5	Onyx Edge → VLAN	bridge, no NAT	Nodes land in one broadcast domain, which is what lets them peer
6	VLAN → the far BreadCrumb	the same path back	InstaMesh now sees a link it can score
7	InstaMesh → path selection	continuous	Per packet, the cheapest route wins, cellular or RF

Where the time goes

Stage	Typical
BreadCrumb to cellular attachment, over Ethernet	< 1 ms
Attachment to Onyx Edge, over the air	10 to 20 ms
Bridge and VLAN forwarding	1 to 3 ms
Return leg to the far node	10 to 20 ms
Equivalent mesh path, five to eight RF hops	40 to 120 ms, and variable

The cellular route usually wins on both latency and consistency. The consistency is the part that matters, for the reason below.

InstaMesh decides whether to use the link, and it judges consistency

Most workflows are sized by throughput. This one is sized by how stable the link looks to somebody else's routing algorithm.

InstaMesh continuously scores every link it can see and chooses a path per packet. The cellular route is not privileged. It competes with the RF links on observed quality, and a bearer with excellent peak throughput but variable latency gets scored down and routed around. The capacity is installed, paid for, and unused, and nothing in the mesh reports a fault because the mesh is working exactly as designed.

So the bearer is engineered for predictable latency rather than peak rate. A reserved GBR bearer with a firm delay budget will be used. A best-effort bearer that is fast when the pit is quiet and slow at shift change will be used only when the pit is quiet, which is when it was needed least.

The same property makes failure graceful. Rajant's make-make-never-break behavior means the cellular link joins the link set rather than replacing it. If the cell drops, the RF mesh carries on at its old hop count. If RF degrades behind a highwall, the cellular route absorbs it. Neither side needs to detect the other's failure, because InstaMesh was already measuring both.

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Network Requirements

Per-node sustained rate	10 to 50 Mbps, uplink-leaning
Aggregate per cell	sized on the number of attached nodes, not on peak demand
One-way latency, node to Edge	< 30 ms
Jitter	< 10 ms, the figure that decides whether the link is used
Packet loss	< 0.1%
Availability	99.9% during production shifts
Mesh transport QoS	reserved GBR bearer, LTE QCI 3 or 5G 5QI 83 as the starting point
Bulk and update traffic	non-GBR, scheduled outside shift change
Networking mode	Bridge, APN on VLAN. NAT breaks node-to-node peering

Read the jitter row, not the throughput row. Throughput determines what the link could carry. Jitter determines whether InstaMesh offers it any traffic at all.

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Deploying It

1

Map the existing mesh first

Record the current hop count from the deepest working face to the core, and the throughput available at the far end. That number is the benchmark. Without it there is no way to show what the cellular route bought.

2

Site cells for reach, not for capacity

Pit cells go high: crest positions, ROM-pad masts, existing comms towers. The design goal is line of sight into the pit across the longest span, not throughput at a point.

3

Choose the attachment per node class

Fixed and semi-mobile nodes take a CPE on the Ethernet port. Mobile plant is usually better served by an LTE Enhance module or a Peregrine node, which survive the vibration and dust without a separate enclosure.

4

Configure Bridge mode before anything else

Put the mesh transport on its own APN mapped to a VLAN, bridged without NAT. Mesh nodes have to be directly addressable to peer. Confirm this on two nodes before scaling, because retrofitting it later means re-provisioning every SIM.

5

Reserve the bearer

Put mesh transport on a GBR bearer with a delay budget, separate from bulk traffic. Schedule firmware and map updates outside production shifts.

6

Check MTU end to end

Any encapsulation between the node and the Edge reduces the usable MTU, and fragmentation degrades mesh throughput more than the lost bytes suggest. Measure the path MTU rather than assuming it.

7

Verify InstaMesh is choosing the route

Confirm in Rajant's own tools that traffic moves to the cellular path under load. A link that exists but is never selected is the failure mode for this design, and it is silent.

8

Re-measure the hop count

Repeat the first measurement. The deliverable is a shorter path from the working face to the core, with throughput and latency to prove it.

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Devices & Ecosystem

• Rajant LTE Enhance: the purpose-built integration module, attached to an existing BreadCrumb. Designed for the vibration, dust and temperature range of mobile mining plant.
• Rajant Peregrine: a BreadCrumb with the cellular modem integrated, where one box is preferable to two.
• GXC CPE: a cellular unit on the BreadCrumb's Ethernet port, for fixed and semi-mobile positions.
• BreadCrumb nodes: the existing mesh estate, unchanged.
• Autonomous haulage and fleet management: the dispatch and autonomy platforms carried over the combined network.
• Drill and shovel automation, teleremote: the other mesh-borne workloads that benefit from a shorter path.
• Onyx Edge: hosting the mine-side applications that the mesh reaches.

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Design Considerations

Bridge mode is a prerequisite, not a preference. Mesh nodes peer at Layer 2. Behind NAT they are not directly addressable and InstaMesh cannot form the link, so the whole design fails at the first node pair. Settle the networking mode before the SIM order.

Broadcast and multicast cross the bearer too. A Layer 2 mesh floods, and autonomous haulage traffic is frequently multicast. Every flooded frame crosses the cellular link and reaches every node on the VLAN. Scope the broadcast domain deliberately rather than putting the entire mesh estate on one VLAN.

Two nodes on one cell hairpin. Traffic from one BreadCrumb to another on the same cell travels up to the Onyx Edge and back. Local breakout keeps it on site, but it is still a longer path than the direct RF hop those nodes may already have. The cellular route earns its place between distant nodes, not adjacent ones.

Fault attribution crosses a vendor boundary. When a truck stops, the question is whether the mesh, the cellular link or the autonomy stack caused it. Correlate Onyx Portal session records with Rajant's link history on a common clock, and agree who looks first before the first incident rather than during it.

The pit changes shape and the cells do not. Mesh nodes move with the operation by design. A cell on a crest position may be overlooking a different pit profile in six months. Review cell siting against the mine plan, not just against today's survey.

LTE today does not foreclose 5G. The architecture is unchanged by the generation: a bridged bearer presenting a link InstaMesh can score. Moving to 5G raises throughput and tightens the delay budget without altering the design.

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Validation Checklist

• Baseline hop count and far-end throughput recorded before any cellular attachment
• Bridge mode confirmed on two nodes, with node-to-node peering proven across the bearer
• Path MTU measured end to end, with no fragmentation under load
• Mesh transport on a reserved GBR bearer, separate from bulk traffic
• Jitter measured at the working face during shift change, not at rest
• InstaMesh confirmed to select the cellular route under load, in Rajant's own tooling
• Failover tested both ways: cell down with RF carrying, RF degraded with the cell carrying
• Broadcast domain scoped, with flooded traffic volume measured across the bearer
• Coverage verified at the deepest working face and behind the highwall
• Hop count re-measured and the improvement documented
• Portal and Rajant link records correlated on a common clock

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Next steps

• Size it. Take these requirements through Plan Your Network: capacity, coverage, architecture, and a preliminary bill of materials.
• Compare it. Network Requirements at a Glance puts every workflow side by side, for sites carrying more than one.
• Talk to us. For a validated design and a quote, contact GXC.

Related reading

• 4G & 5G Onyx Networking Modes : NAT and Bridge modes, and how an APN maps to a VLAN
• AGV and AMR Fleet Control : closed-loop vehicle control on a private network indoors
• Network Requirements at a Glance : all workflows side by side