Broadband Wireless Access
Broadband Wireless Access
Broadband Wireless Access (BWA) allows for the provision of high-speed Internet services without building physical structures consisting of fiber, coax or category 5 twisted pair in residential houses and business premises, relying instead on base transceiver stations (BTS) to transmit the bandwidth. However, at the initial stages, there werent any defined standards for building the Systems which resulted in a variety of software and hardware. The acceptance level is therefore low as the prices for these products are often kept high.
As such, IEEE standard 802.16 was developed by The Institute of Electrical and Electronics Engineers Standards Association (IEEE-SA) which sought to make Broadband Wireless access (BWA) more acceptable. The official standard was approved in April 2002 and is now known as “Air Interface for Fixed Broadband Wireless Access System”. It is also known as wireless Metropolitan Area Network (MAN) or wireless Local Loop.
(References from Computer Network, Andrew S. Tanenbaum, Person Education, 4th Edition)
IEEE 802.16 deals with the “first-mile/last-mile” connection in wireless MAN which refers to the topology between customer and central office/head end. It characterises the medium access control (MAC) layer that supports multiple physical layer specifications which customise the bandwidth between 10 and 66 GHz to the frequency band usage. The standard defines per station and per connection as the 2 forms of bandwidth allocation. For per station, the bandwidth is released to its users after it amasses all the requests and when it has been allocated the resources. For per connection, the BTS manages each connection directly.
IEEE 802.16 standard specifies a protocol that support low latency applications such as voice and videos and provides broadband connectivity without requiring a direct line of sight between subscriber terminals and the base transceiver station (BTS). It can support a large number of subscribers from a single BTS, accelerating the introduction of wireless broadband equipment into the marketplace, speeding up last-mile broadband deployment worldwide by enabling service providers to increase system performance and reliability while reducing their equipment costs and investment risks due to mass production of the software/hardware.
The 802.16 Protocol Stack is different from the Logical Link Control protocols which have been used with other LAN standards. The difference lies in the security sublayer that provides customer separation through encryption mechanisms and encryption key management. The MAC sublayer manages the data transfer mechanism while the service specific convergence sublayers deal with different services such as voice, video, data transfer and basic Internet access that can be provided over 802.16. As such, the 802.16 Protocol Stack is different from most other IEEE standards.
The physical layer specifies the frequency band, the modulation scheme,