Private 5G for Small Sites: A Practical CBRS Playbook for Coverage, SIMs, and Real Apps

Private cellular is no longer only for stadiums and megafactories. Shared spectrum, turnkey cores, and small cells have brought 4G/5G down to the scale of a warehouse aisle, a construction site, or a school campus. If you’ve ever wished Wi‑Fi acted more like a managed utility—predictable mobility, deterministic QoS, SIM‑based identity—then a small private 5G or LTE network is now within reach. This guide shows how to plan, deploy, and operate a compact system that solves real problems fast, with an emphasis on Citizens Broadband Radio Service (CBRS) in the U.S. and equivalent local licensing elsewhere.

Why private 5G is arriving for small sites

Three changes made this moment possible:

Shared and local spectrum. In the U.S., CBRS at 3.55–3.7 GHz (LTE band 48, NR n48) is coordinated by a Spectrum Access System (SAS) so enterprises can operate without buying nationwide licenses. Similar local or shared options exist in the UK, Germany, and Japan.
Appliance‑style cores and radios. Where you once needed a room of EPC/5GC racks and specialists, now you can deploy all‑in‑one small cells and compact software cores on a single server or edge box.
Device readiness. Modern handsets, tablets, CPEs, and industrial modems support LTE band 48 and, increasingly, 5G n48 or n77/n78 in local bands abroad. You can put real users on your private network immediately.

The result is a network with mobility that works, SIM‑based access control, and predictable radio behavior across large areas, even in RF‑hostile spaces with moving equipment. It complements, not replaces, Wi‑Fi.

What a simple private 5G network includes

At small scale, your design is surprisingly clean. Think three layers: radios, a core, and devices.

Radios and spectrum

Private cellular rides on licensed or coordinated mid‑band spectrum with controlled power and interference management.

CBRS (U.S.). Radios are called CBSDs. Category A devices cover indoor/outdoor small cells at moderate EIRP; Category B supports higher power and typically requires a certified professional installer and GPS timing. A SAS dynamically assigns your channels and power limits to protect incumbents.
Local 5G bands (international). UK Shared Access licenses (3.8–4.2 GHz), Germany’s local 3.7–3.8 GHz permits, and Japan’s local 5G bands enable similar enterprise operations. Rules and power limits vary, so check your regulator’s site.
LTE vs 5G. For many first deployments, LTE over CBRS is simpler and supports the widest device base. 5G NR adds lower latency and advanced scheduling but requires careful device selection. Mixed networks are common: LTE for baseline coverage and 5G where you need capacity.

The core network (EPC or 5GC)

Your core handles mobility, authentication, QoS, and routing. You can:

Run an on‑prem appliance/core VM. Low latency, direct control, and no dependency on a cloud path for local traffic. Open source (e.g., Open5GS) and commercial appliances (Celona, Athonet, and others) are viable.
Use a managed service. A vendor hosts the core, and you bring radios and SIMs. This reduces ops burden but introduces WAN dependency for control‑plane and sometimes user‑plane traffic.

Either way, plan where user traffic exits: keep operational traffic local for deterministic performance and route internet traffic through a controlled egress.

SIM and identity

Cellular networks authenticate with SIMs (or eSIM/iSIM), which store keys and profiles. For small deployments:

Physical SIMs are easy to start with. Preprogrammed IMSIs and keys map to your user database.
eSIM enables over‑the‑air activation. You’ll use an SM‑DP+ service to deliver profiles securely to devices, which is useful for distributed sites and contractor fleets.
Role‑based access ties a SIM to an APN/DNN and QoS tier. Lost phone? Disable at the SIM and it’s out instantly.

Planning coverage without RF drama

You don’t need a giant RF design exercise to start smart. A few disciplined steps prevent surprises.

Room‑by‑room thinking

Map materials. Concrete and metal racks can eat mid‑band signals. Dense drywall and glass attenuate less. Walk the site and annotate signal blockers on your plan.
Place for line‑of‑sight first. Mount small cells high enough to see across your critical zones. Use directional antennas for long aisles or drive lanes to concentrate energy.
Overlap modestly. Target 10–20% overlapping coverage between cells so handovers stay stable without excessive interference. A 3–6 dB overlap zone is a good starting point.
Start conservative on power. More power is not always better indoors. Right‑size power to your floor plan, then adjust with real measurements.

Power, timing, and backhaul

Backhaul. Each small cell needs reliable Ethernet and sufficient uplink. If you expect many video flows, plan your switch and uplink capacity accordingly and keep user traffic off the control plane.
Timing. 5G TDD radios need accurate timing. Use GPS where possible or a grandmaster clock feeding PTP to your radios. Indoors without sky view, use PTP with boundary clocks in switches.
Power. PoE or local DC works; ensure clean power and a UPS for continuity. Stability matters more than peak capacity.

A starter bill of materials

2–6 small cells supporting your band (CBRS Category A/B or local licensed band)
One core instance (appliance or server VM) with EPC or 5GC
SIMs (physical and/or eSIM service)
PoE switches with VLANs and, if needed, boundary clocks for PTP
Mounts and antennas appropriate for your layout
Test devices (a phone, a CPE/router, an industrial modem)

Devices and onboarding that won’t frustrate users

Device support is the #1 surprise factor. Avoid it.

Check bands precisely. For CBRS, ensure the device supports LTE band 48 and/or 5G NR n48. Internationally, confirm support for your regulator’s local band (e.g., 3.7–3.8 GHz in Germany).
Use CPEs for fixed endpoints. For cameras and machines, a cellular CPE with Ethernet/Wi‑Fi bridging keeps client hardware simple and lets you centralize SIM management.
Plan SIMOps. Assign SIM ranges to departments, define APNs/DNNs by role, and automate revocation. eSIM reduces shipping and improves turnaround for contractors.
Make joining boring. Users should insert a SIM or scan an eSIM QR code, see a network name, and connect. That’s it. Publish a short one‑page guide with screenshots.

QoS, slicing, and traffic separation made practical

You don’t need full network slicing on day one. You do need clear traffic tiers and separation.

APN/DNN separation. Create different data networks for critical control (e.g., AGV controls, alarms), operations (scanners, tablets), and guest/internet. This keeps traffic classes from interfering.
QoS profiles. LTE uses QCI; 5G uses 5QI. Assign a low‑latency 5QI/QCI to control loops and PTT, best‑effort to general data, and lower priority to background sync. Map QoS to DSCP at your LAN edge if you span domains.
Rate and policers. On your user plane, enforce per‑APN or per‑SIM policies that match device capabilities and radio capacity. Set realistic uplink limits to protect the cell.

Most sites see big wins just by separating control traffic and assigning a higher priority class. If you later adopt advanced slicing, your groundwork already matches that model.

Security and safety along the way

Private cellular inherits strong, SIM‑based security. A few choices make it even better.

Keep user traffic local by default. For on‑site apps, hairpinning to the cloud adds avoidable latency and failure modes. Place the user plane near devices.
Protect RAN‑to‑core links. Use segmentations and, where supported, IPsec for control and user plane connectivity between radios and the core.
Manage credentials carefully. Store SIM keys securely and track IMEI/IMSI pairing. In 5G, SUCI protects subscriber identity in the air; keep your core’s crypto up to date.
Log and alert simply. Start with KPIs and auth logs. Alert on attach failures, reject spikes, and sudden drops in signal quality across a cell.

Apps that benefit today

Pick one or two use cases that monetize or save time immediately. Popular options include:

Reliable push‑to‑talk. Replace crackly radios with VoLTE/VoNR group calls that work across big sites and inside tough buildings. Tie talk groups to job roles via SIM policy.
Mobile HMIs and service tools. Tablets can stream PLC diagnostics or digital work instructions while walking the floor, with fewer drops in noisy RF zones.
Video where Wi‑Fi struggles. A few uplink‑hungry cameras can swamp a shared Wi‑Fi channel. With private LTE/5G, you can assign a separate slice/APN and cap rates to avoid collateral damage.
Outdoor job sites. Temporary cells bring coverage to construction areas, remote yards, or event venues with moving people and equipment.

Focus on one measurable outcome—fewer dropouts on radios, faster audit time, or reduced truck rolls—so you can justify the project and guide tuning.

Pilot in a weekend: a step‑by‑step checklist

Confirm spectrum access. In the U.S., establish an account with a SAS provider through your radio vendor. Elsewhere, apply for a local/shared license or partner with a licensed operator.
Order two small cells and a core. Start with a pair to test handover. For cores, choose a turnkey appliance or spin up Open5GS on a dedicated server with two NICs.
Get SIMs. Buy a small batch of physical SIMs from your vendor or set up an eSIM SM‑DP+ service. Assign profiles to test users and a CPE.
Prep the LAN. Create VLANs for RAN, core management, and user traffic. If using PTP, enable boundary or transparent clocks on your switches.
Mount radios high and safe. Choose locations with the clearest view over your target area. If you can, mount one directional antenna facing an aisle and one omni in an open space.
Turn up the core. Define PLMN, TAC, APNs/DNNs, users, and QoS profiles. For LTE, configure the MME/SGW/PGW roles; for 5G, ensure AMF/SMF/UPF are online. Add DNS and DHCP where needed.
Connect radios to the core. Register CBSDs with the SAS, set EARFCN/NR‑ARFCN, set power conservatively, and confirm the radios attach to the core.
Attach devices. Activate SIMs, insert or download eSIM profiles, and place test calls or data sessions. Verify APN/DNN selection and IP assignment.
Test mobility and load. Walk test with a coverage app; run uplink tests; stream a video from a mobile device. Tune power and handover thresholds.
Document and freeze. Capture a stable config backup, site photos, and a simple runbook covering resets, logs, and contacts for SAS and vendor support.

Budgets, scale, and the costs people forget

Expect a modest pilot to land in the price range of $10k–$35k depending on radios, core choice, and device mix. A rough breakdown:

Small cells: $2k–$6k each for CBRS indoor/outdoor models; more for ruggedized or high‑power options.
Core: Open source on your server (your time cost) or $5k–$15k for an appliance or subscription.
SIM/eSIM: $1–$3 per SIM plus any eSIM platform fees; volume pricing is common.
Switching and mounts: $2k–$5k depending on PTP requirements and cabling.

Commonly missed items include: PTP timing hardware, licensing or SAS fees, spare SIMs, coverage testing tools, and labor for cable runs. If you plan outdoor coverage, budget for weatherproof enclosures and professional mounting.

Operate and optimize

Private cellular is remarkably stable once tuned. A lightweight operational rhythm keeps it that way.

Watch RF health. Track RSRP (signal), RSRQ (quality), and SINR (interference). Aim for RSRP better than −100 dBm and SINR above 10 dB for most areas. Investigate dips quickly.
Monitor attach and handover. Spikes in attach rejects or handover failures mean coverage gaps or mis‑tuned thresholds. Adjust overlap and power before adding more radios.
Keep firmware current. Update radios and core during planned windows. Vendors fix scheduler and NR/LTE interoperability bugs often—updates are worth it.
Review SAS and licenses. Note renewal dates and confirm your CBSD registrations are healthy. Avoid unplanned outages from expired entries.
Measure the promise. Track your chosen success metric: PTT call reliability, latency on a control flow, or uptime for a camera APN.

Common pitfalls you can dodge

Device mismatch. The phone or modem didn’t actually support your band or 5G mode. Always pilot with the exact device SKUs you plan to deploy.
Too much power indoors. Excess power creates coverage “hotspots” and handover chaos. Start low, measure, and nudge upward.
Single VLAN for everything. Mixing RAN, core management, and user traffic invites latency and blast radius. Segment from day one.
Cloud dependency for local apps. If your core lives far away, control loops will jitter. Bring the user plane local for real‑time cases.
Skipping timing. TDD without good timing leads to strange throughput and interference symptoms. Treat PTP or GPS as a first‑class requirement.

When Wi‑Fi is still the better tool

Wi‑Fi remains the best fit for ultra‑high throughput indoors, commodity clients, and dense office settings. It’s faster to reconfigure and the client ecosystem is huge. Use private cellular for:

Mobility that must not drop. Moving devices that roam often and need seamless handover over wide areas.
Uplink stability at range. Sensors, PTT, and moderate video where you need strong uplink far from the AP.
Identity and control. SIM‑based access and policy, dedicated APNs, and per‑SIM shutoff.

Most real sites run both—and that’s the point. Use the right radio for each job.

Going beyond the pilot

After a stable pilot, scale deliberately:

Add a cell only when needed. If performance dips in a specific zone, confirm you’ve tuned power and handover before adding hardware.
Automate SIMOps. Integrate SIM issuance with HR or device management. Expire contractor profiles automatically.
Consider dual‑mode. Introduce 5G NR radios in problem areas for capacity or latency while leaving LTE in place for broad coverage.
Introduce MEC apps. Host PTT servers, video analytics, or control apps on the same edge as your user plane to keep latency low.

Keep your success metric front and center as you grow. If you can tie each change to a measurable improvement, you’ll avoid tech‑for‑tech’s‑sake sprawl.

Summary:

Private 5G/LTE is now practical for small sites thanks to shared/local spectrum, turnkey cores, and device support.
Start simple: a couple of small cells, a compact core, and a handful of SIMs are enough to pilot real use cases.
Plan coverage with modest overlap, careful power, and reliable timing; segment your LAN for RAN, core, and users.
Use APNs/DNNs and QoS tiers instead of full slicing at first; keep control and critical traffic local for stability.
Operate by watching RF KPIs, handovers, firmware, and licenses; measure an explicit success metric.
Deploy private cellular where mobility, uplink stability, and SIM‑based control beat Wi‑Fi; run both where each fits best.