RF Engineer interview prep

What the job involves

RF Engineers in telecom and internet plan, design, and optimise radio access networks (2G/3G/4G/5G) so that subscribers get strong coverage, high data speeds, and low call drops. Day to day they work with drive test data, KPIs, propagation tools, and site surveys to tune parameters, fix interference, and support new site rollouts. They coordinate with planning, field operations, and core teams to keep the network performing within targets.

Role and Technical Knowledge

1. 1

   Explain the difference between RSRP, RSRQ, and SINR in LTE. How would you use them to judge cell edge performance?

   Define each metric clearly: RSRP is signal strength, RSRQ includes interference and load, SINR is signal to interference plus noise ratio. A strong answer links low SINR and poor RSRQ at cell edge to throughput drops and suggests tilt or power adjustments.

2. 2

   What is a link budget and why is it important for RF planning?

   Cover the equation: transmitted power plus gains minus losses equals received power. Mention margins for fading, penetration, and interference, and how it decides cell radius and site density.

3. 3

   Describe the basic architecture of a 5G NR network. How does it differ from LTE in terms of spectrum and frame structure?

   Mention gNodeB, AMF/UPF, and NR bands including sub-6 GHz and mmWave. Highlight flexible numerology, wider bandwidths, and beamforming as key differences from LTE.

4. 4

   What is MIMO and how does massive MIMO improve capacity and coverage?

   Explain spatial multiplexing and beamforming. A good answer notes that massive MIMO uses many antenna elements to focus energy, reduce interference, and serve multiple users on the same resource.

Practical Scenarios

1. 5

   A drive test shows a cluster with high drop call rate and poor SINR. How would you troubleshoot?

   Walk through checking interference, overshooting cells, missing neighbours, and physical blockers. Suggest parameter changes like tilt, power, or handover thresholds, and a re-drive to validate.

2. 6

   You need to plan a new site in a dense urban area with high traffic. What factors would you consider?

   Consider clutter type, building heights, traffic density, spectrum band, antenna height and tilt, and backhaul availability. Mention using planning tool simulations and site surveys before finalising.

3. 7

   How would you handle a complaint of poor indoor coverage in a high-rise building?

   Suggest indoor small cells, DAS, or repeaters after checking outdoor signal penetration. Mention using a walk test to map coverage and choosing a solution based on cost and capacity needs.

4. 8

   What is PIM and why is it a concern at cell sites? How can it be reduced?

   Explain passive intermodulation as interference generated by non-linear junctions. Strong answers mention proper torque on connectors, clean metallic contacts, and using low-PIM components.

Tools and Technology Awareness

1. 9

   Which RF planning or drive test tools have you used or studied? Describe a typical workflow.

   Name tools like Atoll, TEMS, NEMO, or Actix. Describe importing site data, running predictions, collecting logs, and post-processing to identify coverage holes or interference.

2. 10

   What is the role of a spectrum analyzer and a site master in RF field work?

   Spectrum analyzer checks frequency interference and signal quality. Site master measures VSWR and cable loss. Mention that both help validate installation quality and clear interference issues.

3. 11

   How do you ensure RF safety while working near antennas?

   Mention maintaining safe distance based on power and frequency, using personal RF monitors, and following lockout or power-down procedures. Show awareness of Indian RF exposure norms.

4. 12

   What are the key differences between 4G and 5G KPIs that an RF engineer monitors?

   For 5G, mention SS-RSRP, SS-SINR, and beam-specific metrics. Note that 5G adds beam management and higher throughput targets while retaining accessibility and retainability KPIs.

Behavioural and HR Questions

1. 13

   Tell me about a time you worked in a team to solve a technical problem.

   Use the STAR method. Pick a college project or internship where you diagnosed an issue, divided tasks, and achieved a measurable result. Highlight your specific contribution.

2. 14

   Are you willing to travel to field sites or relocate for work?

   Be honest and positive. Mention that you understand RF roles often involve field visits and that you are open to travel and learning on site.

3. 15

   How do you keep your telecom knowledge updated?

   Mention following telecom news, TRAI reports, vendor blogs, and online courses on 5G. Show curiosity by referencing a recent technology trend you read about.

4. 16

   Why do you want to work as an RF Engineer in the telecom and internet sector?

   Connect your interest in wireless communication and network performance to the impact on millions of users. Mention a specific area like 5G rollout or network optimisation that excites you.