A comparison of wi-fi and wimax with case studies - Florida State ...

Best-effort service (BE)
This scheme is used only for service that does not require strict QoS, such as web browsing.
The MS uses merely contention-based polling opportunities to request bandwidth and sends data
whenever channels are available.
4.3.1.2.4. Security
4.3.1.2.4.1. Overview
The security of IEEE 802.16 is called the privacy sublayer at the bottom of the MAC layer.
It is mainly used to provide access control and confidentiality of the data link. The configuration
of the IEEE 802.16 security has five components and will be introduced in the following.
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Security Associations (SA)
This component is mainly concerned about connection. IEEE 802.16 has two types of SA;
data SA and authorization SA. Only data SA has a clear definition. The data SA is used to
protect transmit connections between SS (Subscriber Station) and BS (Base Station).
The authorization SA is a state which is shared between two particular SS and BS. The BS
uses authorization SAs to configure data SAs on the SS.[52]
For securing a transmit connection, a SS first uses a “create-connection” request to initiate a
data SA. The standard will let several connection IPs share a SA to support multicast. On
network entry, the standard automatically establishes a SA for the secondary management
channel. Thus, a SS may have two or three SAs, one for the secondary management channel,
others for uplink and downlink connections. Each multicast group requires a SA to share with
group members.
X.509 certificate profile
This is used to identify communication parities and 802.16 does not define its extensions.
This standard defines two types: manufacturer certificates and SS certificates. There are no
certificates of BS. A manufacturer certificate is used to identify the manufacturer of an IEEE
802.16 device. It can be self-signed or issued by a third party. An SS certificate can identify a
particular SS and also its MAC address. The SS certificates are created and signed by
manufacturers.
The BS uses the manufacturer certificate’s public key to confirm the SS certificate and also
verify the device. The SS must take care of the private key corresponding to its public key to
prevent intrusion from attackers.
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