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21 Wireless Local Area Networks
and modulation all enable the mobile WiMAX technology to support peak
downlink data rates of 63 Mbps per sector and peak uplink data rates of up
to 28 Mbps per sector in a 10 MHz channel.
Quality of service (QoS)
. The fundamental premise of the IEEE 802.16
MAC architecture is QoS. It defi nes service fl ows which can map to DiffServ
code points or MPLS fl ow labels that enable end-to-end IP based QoS. Addi-
tionally, sub-channelization and MAP-based signaling schemes provide a
fl exible mechanism for optimal scheduling of space, frequency, and time
resources over the air interface on a frame-by-frame basis.
Scalability.
Mobile WiMAX is designed to be able to scale to work in dif-
ferent channelization from 1.25 to 20 MHz to comply with varied world-
wide requirements as efforts proceed to achieve spectrum harmonization in
the longer term.
Security.
Support for a diverse set of user credentials exists including SIM/
USIM cards, smart cards, digital certifi cates, and user name/password
schemes based on the relevant extensible authentication protocol (EAP)
methods for the credential type.
Mobility.
Mobile WiMAX supports optimized handoff schemes with laten-
cies less than 50 ms to ensure that real-time applications such as VoIP can be
performed without service degradation. Flexible key management schemes
assure that security is maintained during handoff.
