lteSLSCFDMAInfo

Sidelink SC-FDMA modulation information

Syntax

info = lteSLSCFDMAInfo(ue)

Description

info = lteSLSCFDMAInfo(ue) returns a structure containing information related to the sidelink SC-FDMA modulation performed by lteSLSCFDMAModulate, using the specified UE settings structure.

For details, see Sidelink SC-FDMA Modulation.

Examples

Sidelink Waveform Sampling Rate for 5 MHz Channel

Calculate the sampling rate of a 5 MHz sidelink waveform after sidelink SC-FDMA modulation.

Create a UE settings structure. Specify 25 resource blocks, which corresponds to 5 MHz channel bandwidth.

ue = struct('NSLRB',25);

For the specified channel bandwidth, find the sidelink SC-FDMA modulation sampling rate.

slscfdmaInfo = lteSLSCFDMAInfo(ue);
samplingRate = slscfdmaInfo.SamplingRate

samplingRate = 
7680000

Input Arguments

ue — User equipment settings

structure

User equipment settings, specified as a parameter structure containing these fields:

NSLRB — Number of sidelink resource blocks

integer scalar from 6 to 110

Number of sidelink resource blocks, specified as an integer scalar from 6 to 110.

Example: 6, which corresponds to a channel bandwidth of 1.4 MHz.

Data Types: double

CyclicPrefixSL — Cyclic prefix length

'Normal' (default) | 'Extended' | optional

Cyclic prefix length, specified as 'Normal' or 'Extended'.

Data Types: char | string

Windowing — Number of time-domain samples

positive integer scalar | optional

Number of time-domain samples over which windowing and overlapping of sidelink SC-FDMA symbols is applied, specified as a positive integer scalar.

ue.Windowing must be even. For the ue.Windowing field, the default depends on NSLRB and CyclicPrefixSL.

Data Types: double

Data Types: struct

Output Arguments

info — Sidelink SC-FDMA modulated waveform information

structure

Sidelink SC-FDMA modulated waveform information, returned as a parameter structure containing these fields:

SamplingRate — Sampling rate

positive numeric scalar

Sampling rate of the time-domain sidelink waveform, in Hz, returned as a positive numeric scalar. SamplingRate = Nfft × (30.72e6 / 2048).

Nfft — Number of FFT points

positive integer scalar

Number of FFT points, returned as a positive integer scalar. Nfft is a function of the number of resource blocks, $$N_{\text{RB}}^{\text{SL}}$$.

NSLRB ($$N_{\text{RB}}^{\text{SL}}$$)	Nfft
6	128
15	256
25	512
50	1024
75	2048
100	2048

In general, Nfft is the smallest power of 2 greater than or equal to (12 × $$N_{\text{RB}}^{\text{SL}}$$) / 0.85. Specifically, Nfft is the smallest FFT that spans all subcarriers and results in no more than 85% of bandwidth occupancy (12 × $$N_{\text{RB}}^{\text{SL}}$$ / Nfft).

Windowing — Number of time-domain samples

positive integer scalar

Number of time-domain samples over which windowing and overlapping of sidelink SC-FDMA symbols is applied, returned as a positive integer scalar.

CyclicPrefixLengths — Cyclic prefix length

positive integer vector

Cyclic prefix length in symbols for each sidelink SC-FDMA symbol in a subframe, returned as an N_SYM-by-1 integer vector. N_SYM is 14 for normal cyclic prefix and 12 for extended cyclic prefix.

The vector returned for info.CyclicPrefixLengths depends on the FFT size.

• When info.Nfft = 2048, then CyclicPrefixLengths is:

  • [160 144 144 144 144 144 144 160 144 144 144 144 144 144] for normal cyclic prefix

  • [512 512 512 512 512 512 512 512 512 512 512 512] for extended cyclic prefix

• For other values of info.Nfft, these element values in CyclicPrefixLengths are scaled by info.Nfft / 2048.

More About

Sidelink SC-FDMA Modulation

The sidelink SC-FDMA modulation processing in lteSLSCFDMAModulate performs IFFT calculation, half-subcarrier shifting, cyclic prefix insertions, and optional raised-cosine windowing and overlapping of adjacent sidelink SC-FDMA symbols. TS 36.211 specifies that for PSSCH (Section 9.3.6), PSCCH (9.4.6), PSDCH (9.5.6) and PSBCH (9.6.6), resource elements in the last SC-FDMA symbol within a subframe should be counted in the mapping process but not transmitted. Therefore, before performing the IFFT, the last SC-FDMA symbol of each subframe in the input resource grid is set to zero.

For sidelink SC-FDMA modulation, calling lteSLSCFDMAModulate on a multi-subframe array of resource grids is recommended.

• When the resource element grid input to lteSLSCFDMAModulate spans multiple subframes, the windowing and overlapping is applied between all adjacent SC-FDMA symbols, including the last symbol of the previous subframe and the first symbol of the next subframe. Multi-subframe modulation processing results in a waveform that does not have discontinuities between subframes.

• A time-domain waveform that concatenates individually modulated subframes has discontinuities at the start and end of each subframe. To avoid these discontinuities, the resulting multi-subframe time-domain waveform must be created by manually overlapping symbols at the subframe boundaries.

• If the value for windowing is zero, issues concerning concatenation of subframes before sidelink SC-FDMA modulation do not apply.

If ue.Windowing is absent, info.Windowing returns a default value chosen as a function of NRB. The chosen value is a compromise between:

• The effective duration of cyclic prefix, and therefore the channel delay spread tolerance

• The spectral characteristics of the transmitted signal, not considering any additional FIR filtering

Version History

Introduced in R2016b