英语论文网

e 2.2. The certification is not provided to components but to the equipment. The test is done by WiMAX laboratory. The first official certification laboratory chosen by the WiMAX Forum is Cetecom in Malaga, Spain[2].

However, if equipment conforms to the 802.16 and ETSI HiperMAN standards, it might not achieve WiMAX certification. To pass the test programme, it does not need only compliance with the standard but also interoperability with equipment from other companies. There are at present more than 300 companies joining the WiMAX Forum from different industries, such as network equipment manufacturers, service providers, and chip manufacturers.

2.6 VERSIONS of the IEEE 802.16 STANDARD
The IEEE 802.16 Working Group has been adopting a number of projects to enlarge the IEEE Std 802.16 functionality. This section provides the general idea of the IEEE 802.16 standard and its amendments as of January 2006[21].

2.6.1 IEEE Std 802.16-2001
The IEEE 802.16-2001 standard is first edition of the IEEE 802.16 standard. It was accepted on 23 rd December 2001 and in print in April 2002. MAC and PHY are defined by the standard for fixed PMP BWA systems. The MAC structure support multiple PHY specifications. A system can provide multiple services for its subscribers through PMP connections[21]. It operates in the 10-66 GHz bands. Because of its high frequencies, the standard can function only in LOS environments to decrease multipath distortion.

2.6.2 IEEE Std 802.16c-2002
The first revision to the IEEE Std 802.16-2001standard is IEEE standard 802.16c-2002. The revision specifies the complete system profiles for working in 10-66 GHz. It standardizes the wireless technology in more details. Namely, it defines collections of aspects and functions used in execution [21]. These defined sets boost the consistency and interoperability between equipment from different companies.

2.6.3 IEEE standard 802.16a-2003

The second revision for the IEEE standard 802.16-2001 is IEEE standard 802.16a-2003. It supports working at the 2-11 GHz frequencies, both licensed and license-exempt bands. The standard improves PMP MAC and defines new PHY specifications. By MAC functionality, the standard introduces a number of features, such as a specific quality of service (QoS) to optimize data, video, and voice services, Automatic Retransmission Request (ARQ) to get better end-to-end performance. The MAC in addition defines optional Mesh mode which enables every node to directly connect to others through multipoint-to-multipoint air interface and as a result extends the coverage of communication. Because low frequencies have capability to penetrate barriers, the IEEE 802.16a standard can function in near LOS and NLOS environments enabled by the new PHY functionality[21].

2.6.4 IEEE Std 802.16-2004
The revision and consolidation of the IEEE standard 802.16-2001, the IEEE standard 802.16a-2003, and the IEEE standard 802.16c-2002 is IEEE standard 802.16-2004. It is intended for both licensed and un-licensed frequencies. In 10 to 66 GHz bands, it requires LOS environment, whereas, in frequencies below 11 GHz, it provides the facility to support NLOS environment. The MAC supports both PMP and Mesh modes[21].

2.6.5 IEEE standard 802.16f-2005
The revision of the IEEE standard 802.16-2004 is IEEE standard 802.16f-2005. It defines a mana本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。