WiMAX, meaning Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides wireless transmission of data using a variety of transmission modes, from point-to-multi-point links to portable and fully mobile internet access. Mobile WiMAX enables the convergence of mobile and fixed broadband networks through a common wide-area radio-access technology and flexible network architecture. The next-generation mobile WiMAX will be capable of data-transfer rates in excess of 1 Gbps. It is expected to support a wide range of high quality and high capacity IP-based services and applications while maintaining full backward compatibility with the existing mobile WiMAX systems.
IEEE 802.16m (new version of the 802.16) uses OFDMA as the multiple access scheme in the DownLink and UpLink. It supports both time-division duplex (TDD) and frequency-division duplex (FDD) schemes including the half-duplex FDD (HFDD) operation of the mobile stations in the FDD networks. The frame structure attributes and base-band processing are common for both duplex schemes. The modulation schemes supported include quadrature-phase shift-
keying (QPSK), 16-QAM, and 64-QAM.To overcome the issue of performance of adaptive modulation, a constellation rearrangement scheme is utilized. The next generation mobile Wimax suppports advanced multi-antenna techniques like single and multiuser MIMO, alongwith various transmit diversity schemes. The MAC features are an extension of the existing standard.
The next gen system is designed to provide state-of-the-art mobile broadband wireless access in the next decade and to satisfy the growing demand for advanced wireless multimedia applications and services.