Time Domain (Custom OFDM)

Time Domain is a subset of the General Frame Parameters parameter group and contains parameters that apply to all allocations within the frame.

System Rate sets the OFDM Orthogonal Frequency Division Multiplexing: OFDM employs multiple overlapping radio frequency carriers, each operating at a carefully chosen frequency that is Orthogonal to the others, to produce a transmission scheme that supports higher bit rates due to parallel channel operation. OFDM is an alternative tranmission scheme to DSSS and FHSS. system rate in Hz.

Default: 1 GHz Gigahertz: A frequency measurement which equals one billion hertz.

Resource Map Length sets the length of the resource map in number of symbols. This value defines the total number of symbols in the resource map defined by all of the allocations (see Frame Parts and Allocation Summary). If the result length is larger than length of the resource map, Resource Map Repeat Index is used to decide where to loop back in the resource map after the end is reached.

Default: 64 Symbols

Resource Map Repeat Index sets how to loop back if the end of the Resource Map is reached. If Resource Map Length is shorter than the result length, the this parameter specifies where to loop back in the resource map after the end is reached. The value is specified in terms of symbol number. For example, a value of zero means that the analyzer loops back to the beginning of the resource map, while a value of one means that the analyzer loops back to the second symbol of the resource map.

Default: 0 Symbols

CP Length (Ratio) specifies the length of the cyclic prefix (also referred to as guard interval) as an array of values, one value for each symbol in the signal. The array is constrained to always contain at least one value. The default value is an array of length equal to one, with a value equal to 0.25.

CP 1) Contention period, or 2) Cyclic prefix Length is specified as a fraction of the OFDM 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. length. The value is unitless (not as percent). CP Length is used to ensure that distinct transmissions do not interfere with one another. The purpose of CP Length is to introduce immunity to propagation delays, echoes and reflections, to which digital data is normally very sensitive.

CP Repeat Index specifies the cyclic prefix (also referred to as guard interval) repeat index - If the CP Length is at least as long as the measurement result length, it provides a cyclic prefix value for each symbol. If the array is shorter than the measurement result length, processing loops back and re-uses the array (and keeps looping back every time the end of the array is reached again). The location within the array that is looped back to is determined by the CP Repeat Index. For clarity in the explanation below, let RepeatIndex equal the CP Repeat Index, and ArrayLength equal the length of the CP Length array. There are four possible cases:

RepeatIndex ≥ 0 and RepeatIndex < ArrayLength

(this is the normal case)

The repeat index specifies which entry in the array to loop back to (the index is zero-based). Each time the end of the array is reached, it loops back to this entry in the array. A value of zero (which is the default) therefore means that it loops back to the start of the array. A value of ArrayLength−1 means that it loops back to the last value in the array, so the last value is used over and over.
RepeatIndex ≥ ArrayLength

The repeat index points beyond the end of the array. It is treated as though RepeatIndex = ArrayLength−1, so the last value in the array is repeated over and over.
RepeatIndex < 0 and RepeatIndex ≥ −ArrayLength
A negative value means the repeat index is an offset from the end of the array. A value of −1 means the last value in the array is repeated over and over. A value of –ArrayLength means that it loops back to the start of the array.

Default: 0