QPSK (Quadrature Phase Shift Keying)

Quadrature Phase Shift Keying encodes two bits per symbol by selecting between four phases of the carrier wave. QPSK offers a good balance of spectral efficiency and noise tolerance, and is widely used in satellite communications, LTE/5G control channels, and many other systems where robust transmission matters more than peak data rate.

Categories: Radio Access NetworkEncryption and Cryptography

QPSK in context

The radio access network is the layer where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations, downgrade attacks and jamming, and defenses hinge on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

Cryptography in telecom spans air-interface ciphers (A5/1, A5/3, ZUC, SNOW, NEA/NIA), transport (IPsec, TLS), and identity (AKA, 5G-AKA, EAP-AKA'). Weak or downgradeable ciphers remain a live risk on 2G/3G fallback, and post-quantum migration is now on the roadmap for interconnect and roaming keys.

To place QPSK in the wider telecom-security picture, review Private 5G, RFID, MACsec, AP, GNSS Jamming and MAC.

Related terms

Related topic hubs

  • Diameter Security 4G/LTE Diameter threats across IPX/roaming and DEA defenses.
  • Diameter Attacks S6a IDR/PUR/CLR abuse, subscriber tracking, LTE signaling attacks.
  • 5G Security 5G SBA, SEPP, SUCI, 5G-AKA, N32 and service-based interface security.
  • 5G NEF Security Network Exposure Function security in the 5G core.

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.