Historical Perspective: This analysis draws on experience from late 1990s European cable and mobile launches (Projects #29, #47, #48, #49: 1998-2000), when indoor coverage first emerged as a critical enterprise requirement. While technology has evolved (DAS → small cells → neutral hosts), the fundamental economic and technical trade-offs remain relevant.
Whilst mobile network operators have significantly expanded the extent and quality of outdoor coverage, indoor mobile connectivity has not kept pace with this progress—even as mobile has increasingly substituted for fixed-line communications. This gap presents both challenges and opportunities for enterprises and building owners.
Research indicates that approximately 80% of professional mobile calls are made or received from business premises, including offices, commercial spaces, exhibition centres, factories, and industrial sites [1]. Yet indoor coverage quality frequently fails to meet user expectations.
The Indoor Coverage Challenge
Root Causes of Coverage Gaps
Indoor coverage deficiencies arise from multiple technical and environmental factors.
Physical Barriers:
| Barrier Type | Signal Attenuation | Common Locations |
|---|---|---|
| Reinforced concrete | 15-25 dB | Modern office buildings |
| Metal structures | 20-30 dB | Industrial facilities, warehouses |
| Low-E glass | 25-40 dB | Energy-efficient buildings |
| Underground levels | 30-50 dB | Parking, basements, metro |
| Dense partitioning | 10-20 dB | Open-plan offices with glass walls |
Environmental Factors:
| Factor | Impact | Trend |
|---|---|---|
| Building height | Reduced macro cell coverage at upper floors | Increasing (urbanisation) |
| Building density | Interference, reduced signal penetration | Increasing |
| Energy efficiency | Low-E glass blocks RF signals | Increasing (regulations) |
| User density | Capacity constraints | Increasing (densification) |
| Frequency bands | Higher frequencies penetrate less | Increasing (5G) |
Coverage Gap Categories:
| Category | Definition | Typical Cause | Solution Complexity |
|---|---|---|---|
| White zone | No usable signal | Remote location, heavy shielding | High |
| Grey zone | Intermittent coverage | Building materials, interference | Medium |
| Capacity constraint | Signal present but congested | High user density | Medium |
| Quality issue | Coverage exists but poor QoS | Interference, handover issues | Low-Medium |
Business Impact
Poor indoor coverage affects enterprise operations across multiple dimensions.
Productivity Impact:
| Issue | Business Impact | Quantification |
|---|---|---|
| Dropped calls | Customer dissatisfaction, lost sales | 2-5% revenue at risk |
| Poor voice quality | Communication inefficiency | 15-30 min/employee/week |
| Missed calls | Delayed response, missed opportunities | Variable |
| Workarounds | Time spent finding coverage | 10-20 min/employee/day |
| Shadow IT | Unsanctioned solutions, security risk | Compliance exposure |
Use Case Enablement:
Robust indoor coverage enables enterprise digital transformation applications.
| Application | Connectivity Requirement | Business Value |
|---|---|---|
| Unified communications | Reliable voice, video | Collaboration efficiency |
| IoT/sensors | Low-latency data | Operational visibility |
| Asset tracking | Indoor positioning | Inventory optimisation |
| Mobile workforce | Seamless connectivity | Productivity |
| Visitor services | Guest connectivity | Customer experience |
| Emergency services | Reliable E911/E112 | Safety compliance |
Technical Solutions
Multiple technical approaches address indoor coverage challenges, each with distinct characteristics.
Solution Comparison Matrix
| Solution | Coverage Area | Capacity | Multi-Operator | CAPEX | OPEX | Best For |
|---|---|---|---|---|---|---|
| Femtocell | <100 m² | Low | No | € | € | SOHO, small retail |
| Picocell | <5,000 m² | Medium | No | €€ | €€ | SME offices |
| Repeater | <5,000 m² | Low | Yes/No | €€ | € | Warehouses, parking |
| Small cells | <10,000 m² | High | No | €€€ | €€ | Offices, retail |
| Passive DAS | >5,000 m² | High | Yes | €€€€ | €€ | Large venues |
| Active DAS | >10,000 m² | Very High | Yes | €€€€€ | €€€ | Stadiums, airports |
| Hybrid DAS | >5,000 m² | High | Yes | €€€€ | €€ | Offices, hospitals |
Femtocell
Consumer-grade solution connecting to broadband internet to create a local mobile network.
Characteristics:
| Attribute | Specification |
|---|---|
| Coverage | <100 m² |
| Capacity | 4-8 simultaneous users |
| Backhaul | Broadband internet |
| Operator support | Single operator |
| Installation | Plug-and-play |
| Cost | €200-500 device |
Use Cases: Home offices, small retail, remote workers.
Limitations: Limited capacity, single operator, consumer-grade reliability.
Picocell
Operator-deployed small base station connected to mobile network via dedicated backhaul.
Characteristics:
| Attribute | Specification |
|---|---|
| Coverage | 1,000-5,000 m² |
| Capacity | 32-64 simultaneous users |
| Backhaul | Fibre, Ethernet, xDSL |
| Operator support | Single operator |
| Installation | Professional |
| Cost | €5,000-15,000 per unit |
Use Cases: SME offices, retail stores, small venues.
Limitations: Single operator, requires operator cooperation, backhaul dependency.
Signal Repeaters
Devices that capture outdoor signal and re-amplify it indoors.
Types:
| Type | Coverage | Operators | Cost | Complexity |
|---|---|---|---|---|
| Analogue repeater | <2,000 m² | Single/Multi | €2,000-10,000 | Low |
| Digital repeater | <5,000 m² | Single/Multi | €5,000-20,000 | Medium |
| Fibre-fed repeater | <10,000 m² | Multi | €15,000-50,000 | Medium |
Characteristics:
| Attribute | Specification |
|---|---|
| Coverage | 500-10,000 m² (depending on type) |
| Capacity | Limited by donor signal |
| Backhaul | RF (outdoor antenna) |
| Operator support | Single or multi-operator |
| Installation | Professional |
| Regulatory | Requires operator approval in most jurisdictions |
Use Cases: Warehouses, parking structures, open-plan spaces.
Limitations: Dependent on outdoor signal quality, potential interference, regulatory constraints.
Small Cells
Compact base stations providing localised coverage and capacity.
Characteristics:
| Attribute | Specification |
|---|---|
| Coverage | 1,000-10,000 m² |
| Capacity | 64-256 simultaneous users |
| Backhaul | Fibre, Ethernet |
| Operator support | Single operator (typically) |
| Installation | Professional |
| Cost | €10,000-30,000 per unit |
Use Cases: Offices, retail, hospitality, healthcare.
Advantages: High capacity, good coverage, 4G/5G support.
Limitations: Single operator per unit, requires operator partnership, backhaul infrastructure.
Distributed Antenna System (DAS)
Network of antennas distributed throughout a building, connected to a central head-end.
DAS Types:
| Type | Architecture | Coverage | Cost | Best For |
|---|---|---|---|---|
| Passive DAS | Coaxial distribution | 5,000-50,000 m² | €€€ | Medium buildings |
| Active DAS | Fibre distribution | 10,000-500,000 m² | €€€€€ | Large venues |
| Hybrid DAS | Mixed distribution | 5,000-100,000 m² | €€€€ | Complex buildings |
| Digital DAS | IP-based distribution | 10,000-200,000 m² | €€€€ | Modern deployments |
Passive DAS Characteristics:
| Attribute | Specification |
|---|---|
| Coverage | 5,000-50,000 m² |
| Capacity | High (depends on head-end) |
| Distribution | Coaxial cable |
| Operator support | Multi-operator |
| Installation | Professional, significant civil works |
| Cost | €50-150/m² |
Active DAS Characteristics:
| Attribute | Specification |
|---|---|
| Coverage | 10,000-500,000 m² |
| Capacity | Very high |
| Distribution | Fibre optic |
| Operator support | Multi-operator |
| Installation | Professional, extensive infrastructure |
| Cost | €100-300/m² |
Use Cases: Airports, stadiums, convention centres, large office complexes, hospitals.
Advantages: Multi-operator, high capacity, scalable, future-proof.
Limitations: High cost, complex installation, long deployment timeline.
Voice over Wi-Fi (VoWiFi)
Utilisation of Wi-Fi infrastructure to extend mobile voice coverage.
Characteristics:
| Attribute | Specification |
|---|---|
| Coverage | Depends on Wi-Fi deployment |
| Capacity | Depends on Wi-Fi capacity |
| Backhaul | Existing Wi-Fi infrastructure |
| Operator support | Operator and device dependent |
| Installation | Minimal (if Wi-Fi exists) |
| Cost | Minimal incremental |
Use Cases: Offices with existing enterprise Wi-Fi, hospitality.
Advantages: Low cost, leverages existing infrastructure.
Limitations: Handset compatibility, operator support required, Wi-Fi quality dependent, handover challenges.
Economic Models
Cost-Benefit Framework
| Factor | Consideration | Quantification Approach |
|---|---|---|
| Costs | ||
| CAPEX | Equipment, installation, civil works | Vendor quotes, benchmarks |
| OPEX | Maintenance, power, backhaul | Annual percentage of CAPEX |
| Opportunity cost | Space, disruption during installation | Internal valuation |
| Benefits | ||
| Productivity | Reduced time lost to coverage issues | Employee cost × time saved |
| Revenue | Enabled sales, customer satisfaction | Attribution analysis |
| Risk mitigation | Compliance, safety, security | Risk-adjusted value |
| Asset value | Building attractiveness | Rental premium analysis |
Solution Economics by Building Type
| Building Type | Recommended Solution | CAPEX (€/m²) | Annual OPEX | Payback |
|---|---|---|---|---|
| Small office (<1,000 m²) | Femtocell/Picocell | €5-15 | €500-2,000 | 1-2 years |
| Medium office (1,000-10,000 m²) | Small cells/Hybrid DAS | €30-80 | €5,000-20,000 | 2-4 years |
| Large office (>10,000 m²) | Active/Hybrid DAS | €80-150 | €20,000-100,000 | 3-5 years |
| Retail (<5,000 m²) | Small cells/Repeaters | €20-50 | €3,000-10,000 | 2-3 years |
| Shopping centre | Active DAS | €100-200 | €50,000-200,000 | 4-6 years |
| Stadium/Arena | Active DAS | €150-300 | €100,000-500,000 | 5-8 years |
| Hospital | Hybrid DAS | €80-150 | €30,000-100,000 | 4-6 years |
| Industrial | Repeaters/Small cells | €10-30 | €5,000-20,000 | 2-4 years |
Neutral Host Model
Shared infrastructure model where a third party deploys and operates indoor coverage, providing wholesale access to multiple operators.
Stakeholder Benefits:
| Stakeholder | Benefits |
|---|---|
| Building owner | Single deployment, reduced complexity, potential revenue |
| Operators | Reduced CAPEX, faster deployment, shared OPEX |
| Tenants | Multi-operator coverage, better service |
| Neutral host | Recurring revenue, portfolio scale |
Revenue Model:
| Revenue Stream | Typical Pricing | Annual Revenue (10,000 m² office) |
|---|---|---|
| Operator access fees | €2-5/m²/operator/year | €40,000-100,000 |
| Capacity charges | €500-2,000/carrier/month | €24,000-96,000 |
| Installation fees | One-time | €20,000-50,000 |
| Managed services | 10-15% of CAPEX/year | €15,000-30,000 |
Implementation Framework
Project Phases
| Phase | Activities | Duration | Deliverables |
|---|---|---|---|
| Assessment | Site survey, coverage measurement, requirements gathering | 2-4 weeks | Assessment report |
| Design | Solution selection, technical design, cost estimation | 4-8 weeks | Technical specification |
| Procurement | Vendor selection, operator engagement, contracting | 4-12 weeks | Contracts |
| Installation | Civil works, equipment installation, integration | 8-24 weeks | Installed system |
| Commissioning | Testing, optimisation, acceptance | 2-4 weeks | Acceptance certificate |
| Operations | Monitoring, maintenance, optimisation | Ongoing | SLA compliance |
Decision Framework
| Criterion | Weight | Femtocell | Picocell | Repeater | Small Cell | DAS |
|---|---|---|---|---|---|---|
| Coverage area | 20% | 1 | 2 | 3 | 3 | 5 |
| Capacity | 20% | 1 | 2 | 2 | 4 | 5 |
| Multi-operator | 15% | 1 | 1 | 3 | 2 | 5 |
| Cost efficiency | 15% | 5 | 4 | 4 | 3 | 2 |
| Deployment speed | 10% | 5 | 4 | 4 | 3 | 2 |
| Future-proofing | 10% | 1 | 2 | 2 | 4 | 5 |
| Reliability | 10% | 2 | 3 | 3 | 4 | 5 |
Conclusion
Indoor mobile coverage represents a critical infrastructure requirement for modern enterprises. The proliferation of mobile-first applications, unified communications, and IoT deployments makes reliable indoor connectivity essential for business operations.
Key takeaways:
- Assess before investing: Comprehensive site survey and requirements analysis prevents over- or under-engineering
- Match solution to need: Solution selection should align with coverage area, capacity requirements, and multi-operator needs
- Consider total cost: CAPEX is only part of the equation; OPEX, disruption, and opportunity costs matter
- Explore neutral host: Shared infrastructure models can reduce costs and complexity for all stakeholders
- Plan for evolution: 5G and future technologies require infrastructure that can adapt
For deeper exploration of benchmarking and techno-economic analysis methodologies, consult our articles on international benchmarking and LRIC analysis.
Planning an indoor coverage project?
EXXING combines deep technical expertise (DAS, small cells, repeaters) with mastery of economic models (CAPEX/OPEX, neutral host, infrastructure sharing). We help you select the optimal solution for your buildings.
Schedule a consultation | View our track record
References
[1] Small Cell Forum (2023). Enterprise Small Cells Market Status Report. Small Cell Forum.
[2] ABI Research (2023). In-Building Wireless Market Data. ABI Research.
[3] GSMA (2022). Indoor Coverage and Capacity Solutions. GSM Association.
[4] Ofcom (2021). Indoor Mobile Coverage: Consumer Research. Ofcom.
