RuggedCom WiN51 Series, Руководство пользователя и инструкция по установке

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WiN5200 Product Description | 17
characteristics of a subscriber’s particular frequency channel. One such STC technique,
known as the Alamouti Code, was published in 1998[4] and has been incorporated into the
WiMAX 16e standard.
2.4.2 Security
Security was a key failing of older broadband wireless systems of the past. The why of it is
easy to comprehend---any network that transmits its data across wireless signals rather than
wires is inherently more open to interference, intrusion or assault. This does not mean solid
broadband wireless security is impossible, just much more difficult.
As broadband wireless networks have matured security features have improved. With the
advent of WiMAX, the security toolsets available to broadband wireless service providers
have reached all time highs of functionality. Today's WiMAX networks can be secured more
effectively than ever before.
WiMAX and IEEE 802.16 Security Sub layer provides for privacy, authentication and
confidentiality across the broadband wireless network. Defined initially by IEEE 802.16-2004
and then corrected and amended by Corrigendum 1 and IEEE 802.16e-2005 respectively, the
Security Sub layer now supports Fixed and Mobile operation.
There are two major differences between the standards. The first difference is that the security
mechanism of the IEEE 802.16-2004 is based on the DOCSIS standard. In the 802.16e-2005
many changes have been made in the security mechanisms. The second difference is in the
flexibility of SS's connection characteristics with the BST. The IEEE 802.16-2004 only supports
fixed access. In fixed access, an SS cannot mitigate to the air interface of a new Base Station
(BST) without performing the network entry again after a connection termination. The IEEE
802.16e-2005 supports mobile access. Mobile access enables an SS to move between various
BST cells while keeping the connection established.
There are five primary aspects of WiMAX security that should be considered when designing
a security plan for a WiMAX network. These range from mitigation techniques at the physical
layer to improved wireless authentication and encryption to intrusion protection and data
transport security. At each level, choices in implementation and security levels can be made;
although in the case of the physical layer options are limited.
2.4.2.1 Physical Layer Security
There are two basic types of attacks that can affect the physical layer of WiMAX. One is
jamming and the other is packet scrambling. The first is relatively straightforward, and is
sometimes the result of interference rather than an attack. Jamming consists of a stronger