LoRaWAN Range and Gateway Planning: How Many Gateways Does a Building Need?

LoRaWAN range indoors depends on construction, antenna position and spreading factor. Here is how to estimate coverage, place gateways and survey a building.

Vendors quote LoRaWAN ranges of 10 or 15 kilometres. Those figures are real, but they are measured outdoors with clear line of sight. Inside a building with concrete floors, steel decks, foil-backed plasterboard and lift shafts, the picture is very different. This guide explains what affects LoRaWAN range in buildings, how to plan gateway numbers and positions, and how to survey a site before you commit to a design.

How far does LoRaWAN reach?

Typical, realistic ranges for planning:

The honest answer for any specific building is "it depends", which is why a short survey is worth doing. But LoRa's chirp spread spectrum modulation can receive signals below the noise floor, which gives it much better penetration than Wi-Fi or Bluetooth. In most buildings one well-placed gateway covers far more than people expect.

What affects LoRaWAN range indoors?

Building materials

Every wall and floor absorbs part of the signal. Approximate attenuation at 868 MHz, which varies with thickness and moisture:

Concrete floors are the main limit on vertical coverage. Metal is the worst offender: a sensor inside a steel cabinet, or a gateway antenna inside a metal panel, can lose most of its range.

Antenna position

The single biggest factor you control. A gateway antenna mounted high, central, and clear of metal outperforms one tucked into a plant room cupboard by a large margin. Practical rules:

• mount the antenna, not just the gateway, as high as practical
• keep it at least 30 cm or so from metal surfaces and cable trays
• never leave the antenna inside a steel enclosure; use an extension cable and an external antenna
• in multi-storey buildings, a central riser or core position on a middle floor covers floors above and below

Spreading factor and data rate

LoRaWAN uses spreading factors SF7 (fast, short range) to SF12 (slow, long range). A higher SF is heard further away but keeps each message on air much longer: an SF12 message takes roughly 20 times longer than SF7. That costs battery life and uses network capacity. A network that relies on SF12 for many devices is a network that needs another gateway.

Adaptive data rate (ADR) moves each device to the fastest data rate that works reliably, so good coverage directly improves battery life.

Sensor placement

Sensors behind radiators, inside metal ceiling voids, under desks with steel frames, or in fridges and freezers (common for temperature monitoring) need special attention. Some devices offer external antennas or probes on cables so the electronics can sit outside the metal box.

Interference

The 868 MHz band is shared licence-exempt spectrum. In most buildings interference is not the limiting factor, but other 868 MHz systems (some alarm systems, other LoRa networks, RFID) can add noise. A survey shows the noise floor.

Reading RSSI and SNR

Two numbers tell you how good a link is:

• RSSI (Received Signal Strength Indicator), in dBm. Closer to zero is stronger. Around −100 dBm and above is comfortable; −110 to −120 dBm is workable at higher spreading factors; beyond that, the link is marginal.
• SNR (Signal-to-Noise Ratio), in dB. LoRa can decode signals with negative SNR (below the noise), down to about −7.5 dB at SF7 and −20 dB at SF12. Positive SNR is good. Values near the limit for the spreading factor in use mean the device is close to dropping out.

Look at both. A device with acceptable RSSI but poor SNR is in a noisy location. A device that only works at SF12 is a candidate for a better position or another gateway.

How many gateways does a building need?

Start with coverage, then check capacity and resilience.

Coverage

As a starting point for planning:

• Small to medium office or school (up to 3–4 storeys): often one gateway, centrally placed
• Larger concrete-framed building: one gateway every few floors, typically in the core
• Campus: one gateway per building, or rooftop gateways covering several buildings with line of sight
• Basements and plant rooms: often a dedicated gateway, or the plant room controller's integrated gateway (see IONA option cards)

Capacity

A single gateway can handle large numbers of typical building sensors, because each sends a few bytes every few minutes. Capacity becomes a concern when:

• hundreds of devices report every minute
• many devices are stuck at high spreading factors
• the application needs frequent downlinks (commands to devices), since a gateway cannot receive while it transmits

Resilience

LoRaWAN's star-of-stars design means every gateway in range hears every device. A second gateway with overlapping coverage gives redundancy: if one fails, the other still receives the data, and the network server removes duplicates automatically. For critical monitoring (cold stores, leak detection, legionella) overlapping coverage is good practice.

How to survey a building for LoRaWAN

A survey takes a few hours and avoids expensive surprises.

1. Choose candidate gateway positions with power, network (or 4G) and a high antenna location.
2. Install a temporary gateway at the first candidate position, connected to a network server you can watch live.
3. Walk the building with a field tester or a sample sensor set to send frequently (for example, every 30 seconds) and a known spreading factor, ideally the one your real sensors will use.
4. Record RSSI, SNR and packet loss at each planned sensor location, including the awkward ones: basements, plant rooms, corners of the top floor, inside cabinets.
5. Mark weak areas and test a second gateway position if needed.
6. Document the result as a coverage plan with gateway positions and expected link quality at each sensor location.

If a survey is not possible, deploy a few sensors in the most difficult locations first and check their link quality before rolling out the rest.

Worked example: a five-storey office

Consider a concrete-framed, five-storey office with a basement plant room, about 2,000 m² per floor, and a plan for 150 sensors: CO2 sensors in meeting rooms, temperature sensors in open-plan areas, desk sensors on two floors, and leak sensors in the basement and risers.

First design: one indoor gateway in the second-floor comms room. The survey shows good links on floors 1 to 3, marginal links on floor 5, and nothing reliable in the basement.

Revised design:

• move the main gateway's antenna to a high position in the core on floor 3, out of the comms cabinet; floors 1 to 5 now all show workable links, with floor 5 at moderate spreading factors
• add LoRaWAN to the basement plant room controller (for example an IONA with the LoRaWAN option) to cover the basement and the leak sensors directly
• confirm that the two gateways overlap on the ground and first floors, giving redundancy where the most critical sensors are

Result: two gateways, no sensors relying on SF12, and the critical leak sensors heard by the gateway nearest to them. The extra gateway cost a fraction of what battery replacements would have cost had half the sensors been stuck at the slowest data rate.

Indoor or outdoor gateway?

An outdoor gateway on a rooftop can often cover a whole campus of low-rise buildings, and the top floors of the building it sits on, but may struggle to reach its own basement. A combination of a rooftop gateway and an indoor gateway (or plant room controller with LoRaWAN) is common.

See our range of LoRaWAN gateways and LoRaWAN antennas and accessories.

Antennas

• Gain: higher-gain omnidirectional antennas extend horizontal range but flatten the coverage pattern, which can reduce coverage directly above and below. Indoors, a modest-gain antenna is often better.
• Cable loss: long antenna cables lose signal; use low-loss coax and keep runs as short as practical.
• Band: use antennas tuned for 868 MHz.
• Lightning protection: rooftop installations need surge protection and earthing.

Common planning mistakes

• Trusting the brochure range. Kilometre figures are outdoor line-of-sight results.
• Gateway in the comms room cupboard. Convenient for network and power, terrible for radio.
• Antenna inside a steel panel. Always bring the antenna outside.
• Forgetting basements and plant rooms, which are often where the most valuable sensors (leaks, temperatures) live.
• Sensors on SF12 everywhere. A sign of poor coverage: batteries will not last and capacity drops.
• No redundancy for critical alarms. A single gateway is a single point of failure.

Battery life and coverage

Coverage and battery life are linked. A sensor reporting every 10 minutes at SF7 can last many years on its battery; the same sensor at SF12 may last a fraction of that, because each transmission takes far longer. Investing in good gateway coverage is therefore also an investment in lower battery replacement costs, which on a site with hundreds of sensors is a real maintenance saving.

Frequently asked questions

How far does LoRaWAN reach inside a building?

Typically several floors per gateway in a concrete-framed building and often a whole building in lighter construction. Basements, metal enclosures and lift cores reduce range sharply.

How many LoRaWAN gateways do I need?

Often one per medium-sized building, centrally placed with a high antenna. Larger or heavier buildings need one every few floors; campuses may use rooftop gateways to cover several buildings. Add overlapping coverage for critical sensors.

What is a good RSSI for LoRaWAN?

Above about −100 dBm is comfortable; down to around −115 dBm is workable at higher spreading factors. Check SNR too: positive values are good.

Does LoRaWAN work through concrete?

Yes, better than most wireless technologies at 868 MHz, but each reinforced concrete floor reduces the signal noticeably. Plan gateways so sensors are not separated from them by many floors.

What is the difference between LoRa range and LoRaWAN range?

None physically: the range comes from the LoRa radio. LoRaWAN adds the network features, such as adaptive data rate and multiple gateways hearing each device, that make the range usable reliably.

Do more gateways shorten sensor battery life?

No, the opposite. More gateways mean sensors are closer to one, so adaptive data rate moves them to faster spreading factors and shorter transmissions, which extends battery life.

Can LoRaWAN signals be repeated or relayed?

Classic LoRaWAN has no mesh or repeating; the usual fix for a coverage gap is another gateway. Newer relay features exist in the specification, but an extra gateway remains the simplest and most reliable option in buildings.

Does a better antenna improve LoRaWAN range?

Often more than anything else. Moving the gateway antenna higher, into the open and away from metal usually improves coverage more than a higher-gain antenna in a poor position.

Can I use an outdoor gateway to cover the inside of a building?

Often yes for upper floors and nearby buildings, but basements and the building's core may need an indoor gateway as well.

Related guides

• What is LoRaWAN?
• LoRaWAN indoor air quality and CO2 sensors
• People counting and occupancy sensors
• IONA option cards: integrated LoRaWAN gateway