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Telecom Professional Qualification study materials
Telecom Professional Qualification study resources

Telecom Professional Qualification: Wireless and Mobile Communications (2G/3G/4G/5G, WLAN)

Telecom Professional Qualification · Work through your exam, one topic at a time.

All guide sections

Wireless and Mobile Communications (2G/3G/4G/5G, WLAN)

This domain tests radio reuse, the air-interface parameters that distinguish each generation, and WLAN channel planning. Expect mix-and-match questions on which technology uses which multiple access scheme, plus reuse and numerology calculations.

Cellular fundamentals

  • Frequency reuse clusters N cells; N = i² + ij + j² for integer i, j. The co-channel reuse ratio Q = D/R = √(3N): larger N means more distance between co-channel cells (less interference) but fewer channels per cell.
  • Mobility functions: handover (intra/inter-system), paging, location update, and cell breathing as load changes. Link budget = transmit power + gains − losses − margins (shadow, body, interference) versus receiver sensitivity.

Generations

  • GSM: 200 kHz carriers, 8 TDMA timeslots, GMSK modulation, 900/1800 MHz; GPRS and EDGE add packet data.
  • UMTS: WCDMA with 5 MHz carriers, spreading codes, soft handover; HSDPA/HSUPA add faster packet access.
  • LTE: OFDMA downlink, SC-FDMA uplink, channel widths 1.4–20 MHz, resource block = 180 kHz = 12 subcarriers × 15 kHz, MIMO. Core is the EPC: MME, S-GW, P-GW, HSS. KPIs: RSRP (power), RSRQ (quality), SINR.
  • 5G NR: FR1 410 MHz–7.125 GHz, FR2 24.25–52.6 GHz (mmWave); scalable numerology with subcarrier spacing 15 × 2^μ kHz (15/30/60/120); massive MIMO and beamforming; SA and NSA architectures; service classes eMBB, uRLLC, mMTC; network slicing.
  • WLAN: 802.11n/ac/ax; 2.4 GHz uses non-overlapping channels 1/6/11 at 20/40 MHz; 5 GHz supports 80/160 MHz; 6 GHz for Wi-Fi 6E; WPA3 for security.

Worked example

For i = 2, j = 1: N = 4 + 2 + 1 = 7, and Q = √(3 × 7) = √21 ≈ 4.58. Co-channel cells must be separated by about 4.58 cell radii. If the operator instead chooses N = 4 (i = 2, j = 0), Q = √12 ≈ 3.46: capacity per cell rises but co-channel interference worsens, so a tighter reuse plan needs stronger coding or beamforming to hold quality.

Traps that cost marks

  • Mixing uplink and downlink schemes in LTE (SC-FDMA uplink, OFDMA downlink).
  • Quoting RSRP as a positive dBm value; good coverage is around −80 to −100 dBm.
  • Confusing FDD and TDD, or FR1 and FR2 frequency ranges.
  • Using overlapping 2.4 GHz channels (2, 3, 4) rather than 1/6/11.
  • Forgetting that 5G subcarrier spacing doubles with each numerology step.