World-Class WiMAX: Radio Technologies
NEC's Mobile WiMAX solution is based on our suite of innovative radio technologies, which work in sync to maximize network reliability and business opportunities.
Orthogonal Frequency Division Multiple Access (OFDMA)
OFDMA is a multiplexing technique that subdivides the available bandwidth into sub-carriers capable of handling multiple frequencies. Mobile WiMAX uses OFDMA as the radio access method for the air interface, thereby improving multipath performance in Non-Line-Of-Sight (NLOS) environments.
Hybrid Automatic Retransmission Request (HARQ)
HARQ uses a PHY layer "Stop-and-Wait" protocol that provides fast response to packet errors. This improves cell-edge coverage.
Optimized HO Schemes
NEC's Mobile WiMAX supports mobility by offering three handoff schemes: Hard Handoff (HHO), Fast Base Station Switching (FBSS) and Macro Diversity Handover (MDHO). The HHO method is mandatory. The other two schemes are optional.
Sleep and Idle Modes
Sleep and Idle modes are power-saving features, designed for economical MS operation. These modes define the states when the MS is inactive or listening to broadcast traffic without registration on any base system.
Adaptive Array Antenna System (AAS)
Available as an optional smart-antenna technology, AAS uses the beam-forming technique to adjust the width and angle of the antenna radiation pattern (i.e., beams and nulls). AAS offers benefits such as extended transmission and reduced interference.
Multiple Input Multiple Output (MIMO)
MIMO is another smart-antenna technology. It uses multiple antennas with Spatial Multiplexing (MIMO-SM) or a Space-Time Coded System (MIMO-STC). Taking advantage of the multi-path phenomena, this technology delivers high throughput and low bit-error rates. MIMO works best in a clutter-rich environment and is ideal for mobile applications.
