Wimax standards and Security The Wimax

Radio Conformance Testing and Measurements

The overall WiMAX system performance largely depends on the RF char- acteristics of the WiMAX devices. These RF specifications are defined in both the IEEE 802.16-2004, IEEE 802.16 radio conformance test [10], and “WiMAX Certification’’ documents. This section describes the major testing and measurement procedures for the RF transmitter and the receiver.
The WiMAX transmitter requirements are defined in Sections 8.3.10 and

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   of IEEE 802.16-2004, and they include:
   
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     8.3.10.1 Transmit power level control
     
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     8.3.10.1.1 Transmitter spectral flatness
     
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     8.3.10.1.2 Transmitter constellation error
     
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     8.5.2 Transmit spectral mask (for unlicensed band operations)
     

Some other key transmitter measurements such as adjacent channel power ratio (ACPR), maximum output power, spurious, and harmonics are not defined in the standards but are left to the local regulations [11].

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   Transmitter Power Level Control
   

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The transmitter power level control requirement means that the BS and SS must be able to adjust their output power over a defined range [11]. As WiMAX systems can be used for nonline-of-sight applications, gain control of the transmitter is necessary to adjust the output transmit level depending on the channel quality. According to 802.16-2004 standards, a BS is required to have a minimum adjustment range of 10 dB, where SS must have a minimum adjustment range of 30 dB for devices not supporting subchannelization and 50 dB for devices that support subchannelizations. Within these ranges, step sizes must be a minimum of 1 dB and relative accuracy of all steps less than 30 dB must be 1.5 dB. Larger steps have a 3 dB relative accuracy.
The recommended RF test equipment for test and measure transmitter power level control requirement may include a spectrum analyzer, average power meter, and VSA. For the measurement for transmit power level con- trol, the device under test (DUT) is set to various output power settings. The

DUT is set to transmit at valid output power with a frame structure that has a proper preamble and data burst. The preamble symbols are transmitted at a 3 dB higher power than the data bursts. The DUT output power of data burst is measured with the test equipment.

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