Offset (Zone Definition) (802.16 OFDMA)
: Downlink 1
Uplink 0 (See OFDMA Standard Presets Table.)
The Zone Definition parameter specifies the symbol offset within the measurement frame the data analysis region begins relative to the start of the downlink subrame or start of the uplink subframe.
The start of the subframe is determined by the Downlink Frame Ratio.
Legacy zone offset implementation (SW version 6.1 and earlier)
The zone offset parameter was implemented differently for 89600 VSA versions 6.1 and earlier. For the legacy VSA applications, the IEEE Institute of Electrical and Electronics Engineers. A US-based membership organisation that includes engineers, scientists, and students in electronics and related fields. The IEEE developed the 802 series wired and wireless LAN standards. Visit the IEEE at http://www.ieee.org 802.16 OFDMA uplink zone symbol Offset was specified relative to start of the downlink subframe location. Legacy saved setup files (created using 6.10 or earlier versions of the 89600 software) will need to be modified to run on post legacy VSA software implementations:
- Downlink Frame Ratio defines where in the frame the Uplink subframe begins, as a percentage of the frame length.
- Downlink Ratio = (Uplink subframe start time)/FrameLength
As an example, the 802.16e_ULPuscQ16.set file included with the 6.10 release had SymbolOffset set to 26 symbols for the UL Up Link (reverse link: from cell phone to base station)-PUSC partial usage of subchannels: Some of the subchannels are allocated to the transmitter. zone. To update this setup, DownlinkRatio would be set to 0.53, and SymbolOffset would be changed to 0.
The 0.53 DownlinkRatio is calculated as:
52.4% = (ZoneSymbolOffset*Ns/Fs)/FrameLength
where:
- ZoneSymbolOffset: 26 symbols
- Ns is the number of samples per OFDMA symbol (FFTSize*(1+Guard Interval)): 1152 samples
- Fs is the non-oversampled sample rate for the 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 and BW value: 11.424MHz
- We round-up to 53% to ensure the Uplink subframe start occurs within the 26th symbol interval, relative to the frame start. This ensures the PRBS Pseudo-Random Binary Sequence sequence will match the existing recording (Since it uses the "Cor1/D2" compatible PRBS generator).
See Also
