Setting the Center Frequency (802.16 OFDMA)
For OFDMA signals, the analyzer's center frequency must be set within the carrier lock range of the transmitted carrier frequency to achieve carrier lock. The carrier lock range of the VSA varies depending on the signal BW, BW Ratio, FFT Fast Fourier Transform: A mathematical operation performed on a time-domain signal to yield the individual spectral components that constitute the signal. See Spectrum. Size, Subframe Type, and Zone Type as described below:
Downlink subframe carrier lock range:
All zone types: Carrier Frequency +/- 4.5*SubcarrierSpacing
Uplink subframe carrier lock range:
PUSC partial usage of subchannels: Some of the subchannels are allocated to the transmitter., OPUSC zones: Carrier Frequency +/-1.5*SubcarrierSpacing
AMC Adaptive Modulation and Coding zone: Carrier Frequency +/-4.5*SubcarrierSpacing
Example frequency lock range calculation
Signal characteristics: BW = 8.75 MHz Megahertz: A unit of frequency equal to one million hertz or cycles per second., BWRatio = 8/7, and FFTSize = 1024
Using these parameters in the following equation
SubcarrierSpacing = BW*BWRatio/FFTSize
The subframe carrier lock ranges are:
Downlink subframe:
All zone types: ~ +/- 43 kHz kiloHertz: A radio frequency measurement (one kilohertz = one thousand cycles per second). of the Carrier Frequency
Uplink subframe:
PUSC, OPUSC: ~ +/-14 kHz of the Carrier Frequency
AMC: ~ +/- 43 kHz of the Carrier Frequency
See Also
Available Features (802.16 OFDMA)
About Option B7Y IEEE 802.16 OFDMA Modulation Analysis
Selecting the 802.16 Demodulator
