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Short note: WiMAX

Short answer

WiMAX, based on IEEE 802.16, provides broadband wireless access for metropolitan areas. It employs OFDM/OFDMA, adaptive modulation (BPSK to 64-QAM), MIMO, and operates in 2–11 GHz bands with ranges up to 50 km. Standards include fixed (802.16d) and mobile (802.16e) versions with QoS classes, PKM security, and both TDD and FDD duplexing.

Write a short note on WiMAX.

WiMAX (Worldwide Interoperability for Microwave Access) is a broadband wireless access technology based on the IEEE 802.16 standard. It provides high-speed data over metropolitan areas (WMAN) as a wireless alternative to cable and DSL, for "last mile" access.

Key features

  • Standards: 802.16d (2004) for fixed access; 802.16e (2005) "Mobile WiMAX" with handoff; 802.16m (WiMAX 2) aimed at 4G.
  • Physical layer: OFDM (fixed) and OFDMA (mobile, scalable FFT 128–2048); adaptive modulation and coding (BPSK, QPSK, 16-QAM, 64-QAM).
  • Spectrum: 2–11 GHz for non-line-of-sight; 10–66 GHz for line-of-sight. Common bands 2.3, 2.5, 3.5 GHz; channel widths 1.25–20 MHz.
  • Range and rate: up to about 50 km (fixed, LOS) and typically 5–10 km NLOS; data rates up to ~70 Mbps shared (802.16e), ~1 Gbps target in 802.16m.
  • Duplexing: TDD and FDD.
  • MIMO and smart antennas for capacity and coverage.
  • QoS classes: UGS, rtPS, nrtPS, ertPS and best effort; connection-oriented MAC with scheduling by the base station.
  • Security: PKM authentication, AES encryption.
 Internet--[WiMAX BS]~~~~~~~~[CPE]--home LAN
               ~~~~~~~~~~[laptop/mobile]
               ~~~~[relay]~~~[remote user]

Applications: broadband in rural areas, backhaul for Wi-Fi hotspots and cell sites, mobile broadband. WiMAX lost the 4G market to LTE, but is still used for fixed wireless access in some places.

✓ Answer checked by Claude Opus 5.5 (high effort)

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