Designing Wi-Fi in a single-tenant low-rise is one thing. Doing it in a 25-storey, multi-tenant block with concrete cores, mirrored lift shafts, strict landlord rules and a forest of neighbour SSIDs is another. Success isn’t about louder APs or wider channels; it’s about predictable airtime, disciplined power, clean backhaul, and a rollout that respects building constraints.
Here’s how to engineer a multi-tenant wireless network that behaves at 11am on a Wednesday (when it matters), not just at 7pm on a quiet Friday.
Agree outcomes and risks up front
- Coverage & SNR: ≥ -67 dBm at the seating plane; SNR ≥ 25 dB even when adjacent tenants are busy.
- Capacity: Concurrency per zone—boardrooms, collaboration areas, lift lobbies—designed for the crowd you actually see.
- Roaming: Sub-150 ms hand-off between cells and across corridors/lift lobbies.
- Security: 802.1X for corporate; guest isolation; strict ACLs that default to deny.
- Programme risks: Landlord permits, out-of-hours work, lift bookings, listed interiors, global parts lead times. Make timelines honest.
Stakeholders & permissions (skip this and you’ll slip)
- Landlord & building management: Method statements (RAMS), riser access rules, hot-works permits, fixing permissions for ceilings and walls.
- Other tenants: Coordinating noisy works; avoiding channel trains wrecked by neighbour “extenders”.
- Facilities & fit-out: Ceiling types, lighting positions, exposed services—where can APs live without shadowing or upsetting the design intent?
Get these in writing before the first ladder goes up.
RF in a tower: physics beats wishful thinking
- Channel widths: Start at 20/40 MHz on 5 GHz. In a tower, there are too few clean channels for 80 MHz everywhere.
- 2.4 GHz: Treat as legacy-only; raise minimum data rates so clients don’t crawl.
- 6 GHz overlay: Where devices support it, apply 6 GHz in high-value rooms to reclaim clean airtime without wrecking 5 GHz for neighbours.
- TX power discipline: Lower power, smaller cells; overlapping just enough for roaming. Loud APs bleed through floors and walls and create co-channel pain.
- AP placement: Ceiling-mount with clear lobes to seating; keep away from metal light troughs and mirrored glass that cause reflections. In lift lobbies, mount for across-lobby coverage to avoid dead corners.
The wired spine: risers, cabinets, PoE
- Risers & diversity: Map real routes; “diverse” paths that share a riser aren’t diverse. Photograph and label trays and penetrations; fire-stop properly.
- Backbone: Fibre cabinet-to-cabinet. Avoid long copper uplinks between floors.
- PoE budgets: Keep 20–30% headroom at switches; don’t strand AP radios because a switch is starved.
- Cabinet hygiene: Right-length patching, labelled ports, blanking panels, A/B power rails; many “wireless” faults start here.
Fit-out patterns that age well
- Three SSIDs done right: Corporate (802.1X), Guest (isolated), AV/IoT (per-device PSKs bound to a scoped VLAN).
- Discovery tamed: mDNS/Bonjour proxy and IGMP snooping; advertise only what rooms need.
- VLAN/ACL templates: Per floor, repeatable and minimal; default-deny east-west on IoT/guest.
Mid-build, if you’re juggling landlords, joinery and RF, it’s often faster and safer to bring in a team used to tower constraints; scope, survey, design, permits and proof are packaged in specialist Wi-Fi installation for London offices so your fit-out doesn’t stall on building rules or neighbour interference.
Acceptance tests that hold up in a tower
- Pre- vs post-install heatmaps at the seating plane (coverage & SNR).
- Busy-hour validation: Real call loads and screen shares with median/p95 latency/jitter recorded.
- Roaming walk-tests: Calls moving through lift lobbies/corridors; record transition times.
- Spectrum snapshots: Document neighbour occupancy and your channel choices.
- Wired proof: PoE draw logs, fibre test results (OTDR/LSPM) for the backbone, DHCP/DNS response-time baselines.
- Config artefacts: Controller/AP backups, VLAN/ACL/QoS maps, port-to-AP patch schedule.
Refuse sign-off without raw files as well as pretty dashboards.
Operations & change (because towers never sit still)
- Monitoring that matters: Client failure reasons (DHCP, RADIUS, PSK), retransmits, DFS events, noise floor, AP health.
- Firmware lifecycle: Quarterly reviews; staged rollouts floor-by-floor; lab-test against conferencing bars and laptops first.
- Change control (lightweight): SSID tweaks, VLAN moves and AP relocations documented; floor plans updated the same day.
- Neighbour awareness: If a tenant next door “optimises” their Wi-Fi, expect your channel plan to change—schedule quick re-surveys after major neighbour moves.
Ten-step fit-out sequence that avoids drama
- Discovery & RF sweep (busy hours), plus a cabling audit.
- Scaled floor-plan design (coverage, SNR, capacity, channel plan).
- Programme & permits (landlord approvals, out-of-hours windows, lift bookings).
- Cabling & cabinet prep (Cat6A to APs, fibre between cabinets, PoE headroom).
- AP install (mounts, aesthetics, line-of-sight).
- Initial config (three SSIDs, VLAN/ACL templates, mDNS proxy, IGMP snooping).
- RF tuning (TX power caps, minimum data rates, 20/40 MHz channels).
- Validation (busy-hour tests, roaming walk-tests, spectrum snapshots, OTDR/LSPM).
- Punch-list & tidy-ups (tilts, channel trims, patch/cabinet fixes).
- Handover (run-book, monitoring, quarterly tune-up schedule, rollback config).
Pitfalls we still see (and quick fixes)
- 80 MHz everywhere. In a tower, that’s wishful thinking. Start at 20/40 MHz.
- “Turn the power up.” Bloated cells and co-channel misery; cap TX power and shrink.
- 2.4 GHz dependence. Keep it for genuine legacy only.
- Captive portal bloat. Slow joins at peak; keep guest onboarding lightweight.
- Messy risers and cabinets. Micro-bends, unlabeled fibres, starved PoE—wired problems wearing Wi-Fi masks.
- No proof. If you didn’t measure busy hour and roaming, you didn’t finish the job.
The takeaway
High-rise Wi-Fi is a physics and logistics problem, not a brand exercise. Respect building constraints, keep RF disciplined, stand everything on clean fibre and PoE, and prove performance with real loads. Do that, and the office stops thinking about the network—because it just works, floor after floor.
