For these applications, availability of a large spectrum to deliver higher capacity
was certainly more important than the need for non-line-of-sight (NLOS) operation or
spectrum licensing. A large spectrum was (and still is) potentially available between
10??“66 GHz. Therefore, the early PHY standard, targeted for LOS applications, was
developed for spectrum between 10??“66 GHz without locking it to a specific band of
spectrum. The 10+ GHz frequencies allowed for implementation of broadband channels
delivering high bandwidth and the creation of narrow beams using highly directional
antennas. This standard was based on a single-carrier modulation scheme.
The single-carrier standard operating at frequencies between 10 GHz and 66 GHz
is not practical for two other applications of WiMAX that gained momentum during
the later stages of the standard??™s development: NLOS in general and mobility specifically.
Higher data rate single carrier schemes are susceptible to the adverse effects of
multipath signal propagation in NLOS applications. Additionally, RF signals in the
Cryptographic Suite Encryption Method Authentication Method Key Exchange Method
1 No encryption No authentication 3-DES, 128
2 CBC-mode 56-bit DES No authentication 3-DES, 128
3 No nncryption No authentication RSA, 1024
4 CBC-mode 56-bit DEC No authentication RSA, 1024
5 CCM-mode AES No authentication AES,128
TABLE 15.
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