Skip to main content

Handoff margin

Short answer

Handoff margin is Δ = Pr,handoff − Pr,minimum usable. Too large a margin causes unnecessary handoffs; too small a margin risks dropped calls. Typical margins are 6–12 dB for 1G and 0–6 dB for 2G with mobile-assisted handoff.

Define handoff margin with appropriate figure.

Handoff margin Δ is the difference between the signal level at which a handoff is initiated and the minimum usable signal level for acceptable voice quality:

Δ = Pr,handoff − Pr,minimum usable

 Received
 power (dBm)  BS1                     BS2
    │ \                               /
 Pr,handoff ─ ─\─ ─ ─ ─ ─ ─ ─ ─ ─ ─ /─ ─
    │  ↑ Δ       \                /
 Pr,min ─ ─ ─ ─ ─ ─\─ ─ ─ ─ ─ ─ /─ ─ ─ ─
    │                \         /
    └──────────────────────────────── distance
     BS1         handoff region    BS2
  • Typical minimum usable level: −90 to −100 dBm.
  • If Δ is too large, unnecessary handoffs occur, loading the MSC.
  • If Δ is too small, there may not be enough time to complete the handoff before the signal falls below Pr,min, and the call drops.
  • Δ depends on handoff processing time: 1G systems needed about 6–12 dB; 2G systems with mobile-assisted handoff need only about 0–6 dB.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Wireless Communication chapter 2 questions →