Wireless coverage problems are not always caused by the radio at the base station or the antenna at the user end. Often, the real difficulty is everything in between: a building corner, a concrete wall, an uneven street, a metal structure, or simply a target area that sits outside a useful propagation path.

Traditional network design treats much of that environment as a fixed constraint. Engineers can adjust antennas, power, topology, and site density, but the path itself remains largely uncontrolled. A reconfigurable intelligent surface, or RIS, introduces a different idea: make part of the propagation environment adjustable.

That does not make RIS a universal answer to every coverage problem. It gives RF planners another tool—one that must still be evaluated through donor measurements, site geometry, link budget, interference analysis, installation constraints, and acceptance testing.

What is a reconfigurable intelligent surface?

A reconfigurable intelligent surface is an engineered electromagnetic surface whose response can be adjusted to influence how radio energy is reflected, transmitted, or directed. Depending on the design, the surface may use arrays of tunable elements, metasurface-inspired structures, or a hybrid RF architecture.

The practical point is more important than the label. A conventional wall or façade interacts with radio waves according to its material and geometry. An RIS is designed so that this interaction can be controlled. The network can then use the surface to form a more useful path toward a defined coverage area.

This is why RIS is often discussed as part of a programmable wireless environment. The phrase is useful, but it should not be read as a promise that every reflection can be perfectly controlled. Real sites still have path loss, blockage, sidelobes, interference, mounting limits, and changing propagation conditions.

RIS is a family of architectures, not one product type

One reason RIS discussions become confusing is that the same term is used for different engineering approaches.

Some designs are based on patch arrays and familiar RF materials. Others use metasurface-inspired structures to achieve finer control over electromagnetic behavior. Hybrid designs may combine surface elements, antennas, sensing, control, and active RF functions.

The right architecture depends on the frequency band, required aperture, target direction, control resolution, surface loss, available power, installation environment, weather protection, maintenance plan, and project economics. There is no credible one-size-fits-all answer.

Passive RIS and active RIS solve different link-budget problems

The most useful comparison is not which category is “better,” but what each one contributes to the RF path.

Design approach	What it does	Main strengths	Main engineering limits
Passive RIS	Redirects or shapes incident radio energy without RF amplification at the surface	Low operating power and a relatively simple RF role	Performance depends heavily on incident signal strength, geometry, surface loss, and path length
Optimized passive RIS	Uses surface and control design to reduce losses and improve directional behavior while remaining non-amplifying	Retains the passive operating principle while improving usable control	Still cannot compensate for an inadequate link budget through amplification
Active RIS	Combines controllable beam behavior with active RF amplification	Gives the RF designer more flexibility when passive redirection alone cannot close the link budget	Requires power, active-RF design, noise and interference review, thermal planning, monitoring, and market-specific compliance checks

At RFCOM, our Active RIS positioning follows the third approach. We present Active RIS as an engineered coverage solution that combines controllable beam behavior with active RF amplification. We keep that statement at the solution-principle level: exact gain, output power, range, energy use, and coverage results must be confirmed against the relevant model and project design.

How RIS changes the propagation path

Consider a target area that cannot receive a useful direct path from the serving site. Adding another full radio site may be possible, but it may also introduce new requirements for location, backhaul, power, civil work, integration, and operations.

An RIS-based design starts with a different question: is there a suitable point where radio energy can be accessed and directed toward the target?

If the answer is yes, the surface can be configured to influence the outgoing wavefront. In practical terms, this may mean changing the direction of a reflected path or concentrating energy toward a defined zone. The design objective is not to scatter more energy everywhere. It is to create a controlled path where the existing geometry provides a poor one.

This process still begins with measurement. If donor quality is inadequate, the geometry is unfavorable, or the required path cannot meet the link budget, an RIS panel alone will not repair the project.

Where an RIS discussion may be useful

RIS is worth evaluating when the problem is specific and geographically clear. Examples may include:

an outdoor route or courtyard shadowed by a building;
a street-level area with limited direct propagation from the serving site;
an industrial or campus zone where mounting options are constrained;
a large indoor space where the layout creates a persistent weak-signal area;
a temporary or phased project that needs a targeted coverage option before a larger architecture is justified.

These are evaluation scenarios, not guaranteed use cases. The same location may be better served by a DAS, RF repeater, small cell, antenna redesign, or another network change. RIS should be compared with those alternatives using the same coverage objective and acceptance criteria.

What RFCOM evaluates before proposing Active RIS

From our perspective, the product should never be the first question. The first question is whether the propagation and project conditions support the architecture.

1. Coverage objective and baseline

Define the target area, present service condition, required bands, traffic expectations, and the measurements that will be used to judge success. A vague goal such as “improve coverage” is not enough for design or acceptance.

2. Donor signal condition

The donor path must be measured for signal level and quality. The source cell, spectrum, bandwidth, duplex mode, synchronization, loading, and variability can all affect the result.

3. Site geometry

The positions and heights of the donor source, RIS equipment, obstructions, and target area determine whether a controllable path is physically useful. Drawings, maps, photographs, and line-of-sight observations are part of the engineering input.

4. Link budget and interference

The complete path—not one isolated product specification—must be checked. The review should include expected losses, required margin, uplink and downlink behavior, isolation, adjacent signals, and the risk of creating unwanted coverage or interference outside the target zone.

5. Installation and operations

Mounting, wind loading, weather protection, power, transport, access, grounding, maintenance, monitoring, and local approval requirements all influence the architecture. Active RIS adds flexibility, but it also adds active-system responsibilities.

6. Acceptance plan

Baseline and post-installation tests should be agreed before deployment. Measurement locations, test devices, traffic conditions, RSRP, SINR, throughput, continuity, and mobility checks should match the actual project objective. Results from one site should not be generalized to another without a new design review.

RIS in the path toward 6G

RIS is already part of formal industry study rather than only a laboratory concept. ETSI’s RIS Industry Specification Group documents use cases, deployment scenarios, communication models, implementation considerations, and evaluation methods. ITU-R also includes reconfigurable intelligent surfaces among future radio-interface technology trends toward 2030 and beyond.

That makes RIS relevant to the 6G conversation, but it does not make every current RIS product a “6G product,” nor does it guarantee a single architecture will become universal. The more useful near-term work is practical: define the coverage problem, compare architectures, test controllable propagation under real site conditions, and build repeatable evaluation methods.

A smarter environment still needs disciplined RF engineering

The strongest idea behind RIS is simple: network design does not have to stop at the transmitter and receiver. In suitable scenarios, the propagation environment itself can become part of the engineered system.

At RFCOM, we see Active RIS as one option in a wider coverage toolkit. Its value depends on scenario fit, not on the novelty of the technology. A good project starts with measurements, geometry, and acceptance criteria—and only then decides whether controllable beam behavior with active RF amplification is the right approach.

To evaluate a site, share the target-area map, donor measurements, frequency band, distance, obstructions, mounting conditions, and required service level with RFCOM. We can review whether Active RIS, DAS, an RF repeater, or another architecture is the better fit.

Reconfigurable Intelligent Surfaces for 5G and 6G: How RIS Changes the Radio Environment