The IEEE 802.16 Air Interface - Standard
Is truly a state-of-the-art specification for fixed broadband wireless access systems employing a point-to-multipoint (PMP) architecture standard and is designed to cover application to diverse markets from very high bandwidth enterprise businesses, to Small to medium Business (SMB) as well as to SOHO & Residential users.
The IEEE 802.16
Air Interface - Standard 
The standard is designed to accommodate either Time Division Duplexing
TDD) or Frequency Division Duplexing (FDD) deployments, allowing for
both full and half duplex terminals.
WiMAX can be used for:
a number of applications, including
"last mile" broadband connections, hotspot, cellular backhaul,
and high-speed enterprise connectivity for businesses.
WiMAX (Worldwide Interoperability for Microwave Access) provides high throughput broadband connections over long distances.
WiMAX Benefits
for Consumers:
1. Receive services in areas that were
previously out of the broadband loop.
2. Quick effect of cost savings to consumers, translating into lower
monthly rates.
The IEEE 802.16 Working Group has developed point-to-multipoint broadband wireless access standard for systems in the frequency ranges 10-66 GHz and sub 11 GHz. The standard covers both the Media Access Control (MAC) and the Physical (PHY) Layers.
Physical
(PHY) Layers give IEEE 802.16 the
ability to provide very high capacity links on both the uplink and the
downlink. The frame structure allows terminals to be dynamically assigned
uplink and downlink burst profiles according to their link conditions.
This allows a trade-off between capacity and robustness in real-time,
and provides roughly a two times increase in capacity on average while
maintaining appropriate link availability.
The Physical Layer (PHY) defines the electrical,
mechanical, procedural, and functional specifications to
activate, maintain, and de-activate the physical link between
communicating network systems. Physical layer specifications
define characteristics such as voltage levels, timing of
voltage changes, physical data rates, maximum transmission
distances, and physical connectors.
WiMAX has defined two primary Physical (PHY) Layers
system profiles:
a. 25 MHz wide
channel for (typically U.S. deployments) used in the 10-66
GHz range.
b. 28 MHz wide channel for (typically
European deployments) used in the 10-66 GHz range.
Media
Access Control (MAC) uses a self-correcting bandwidth request/grant
scheme that eliminates the overhead and delay of acknowledgements,
while simultaneously allowing better QoS handling than traditional
acknowledged schemes. WiMAX has defined two Media Access Control (MAC)
System Profiles for 10-66 GHz those were rolled back into IEEE 802.16c:
1. Basic ATM
system MAC (Media Access Control) Profile.
2. Basic IP system MAC (Media Access Control)
Profile
The 802.16 MAC uses a variable length Protocol Data Unit (PDU) that greatly increased the efficiency of the standard. Multiple MAC PDUs can be concatenated into a single burst saving on Physical (PHY) overhead. Multiple Service Data Units (SDU) can be concatenated into a single MAC PDU, saving on MAC header overhead.
IEEE 802.16 standard was expanded with the adoption of the 802.16a amendment, focused on Broadband Wireless Access in the frequencies from 2 to 11 GHz.
I n t e r c o n n e c t i n g t h e W o r l d
