Small cells sit alternately on either side of the street. Each has a 28 GHz mmWave link to the moving handset. Path loss follows the free-space 3GPP formula:
FSPL(dB) = 32.4 + 20·log10(f_GHz) + 20·log10(d_m)
RSRP = P_tx − FSPL − L_block (L_block ≈ 25 dB if a body/vehicle blocks the line of sight)
SINR ≈ 10^((RSRP − N0)/10), N0 = −95 dBm noise floor
Throughput = BW·log2(1 + SINR), BW = 100 MHz
Verified numerically: at the 1 m reference distance and 28 GHz this gives FSPL ≈ 61.3 dB, matching the published 3GPP mmWave reference path loss — the formula is internally consistent, so this 2D engine reuses it unchanged (only the presentation, a top-down map, is new; the distance fed into it still includes the real 6 m cell-height/1.5 m handset-height difference, not just the flat road distance).
Because mmWave range is short and easily blocked, the phone must switch cells far more often than on 4G. The handover uses the real 3GPP A3 event: a neighbour must beat the serving cell's RSRP by the hysteresis margin continuously for the time-to-trigger window before the switch fires (this debounce stops rapid "ping-pong" handovers from noise). Every handover briefly interrupts the link — count and interruption time both feed the outage stat.
- Cell spacing — denser small cells raise average RSRP but trigger more handovers.
- Blockers — pedestrians/vehicles crossing the line of sight add ~25 dB of loss, which can push RSRP below the −100 dBm outage floor even with a nearby cell.
- Hysteresis / time-to-trigger — larger values cut ping-pong handovers but let the phone linger on a fading cell longer, hurting throughput.
- Telemetry strip (below the map) traces serving RSRP against the best rival cell — the gap between the two lines is exactly the margin the A3 rule watches, so a handover always fires right as the thin line crosses above the bold one by more than the hysteresis band.
This is the same trade-off 5G mmWave network planners tune between capacity (many small cells), mobility robustness (handover parameters) and blockage sensitivity — the reason mmWave 5G is deployed as dense urban "hot zones" rather than wide-area coverage. Drag the map to pan, scroll to zoom, or click "Follow" to snap the camera back onto the phone.