lteNPRACH
Description
[
generates waveform
,info
,resourceGrid
] = lteNPRACH(ue
,chs
)waveform
, a time-domain narrowband physical random access
channel (NPRACH) frequency-division duplexing (FDD) waveform for user equipment (UE)
settings ue
and channel transmission configuration
chs
. The function also returns info
, a structure
containing NPRACH information, and resourceGrid
, an NPRACH resource
grid.
Examples
Generate NPRACH FDD Waveform
Generate an NPRACH waveform for specified UE settings and channel transmission configuration.
Specify the narrowband physical layer cell identity and subcarrier spacing.
ue = struct('NNCellID',0,'NBULSubcarrierSpacing','15kHz');
Specify the NPRACH format, periodicity, subcarrier offset, number of subcarriers, and number of preamble repetitions.
chs = struct('NPRACHFormat','0','Periodicity',80, ... 'SubcarrierOffset',0,'NumSubcarriers',12,'NRep',1);
Generate the NPRACH waveform, NPRACH information, and resource grid.
[waveform,info,grid] = lteNPRACH(ue,chs);
Input Arguments
ue
— UE-specific settings
structure
UE-specific settings, specified as a structure containing these fields.
Field | Required or Optional | Values | Description | Data Type |
---|---|---|---|---|
NNCellID | Required | Integer in the interval [0, 503] | Narrowband physical layer cell identity. | double |
NBULSubcarrierSpacing | Required | '3.75kHz' , '15kHz' | Narrowband internet of things (NB-IoT) uplink subcarrier spacing. To set
a subcarrier spacing of 3.75 kHz, specify this field as
'3.75kHz' . To set a subcarrier spacing of 15 kHz, specify
this field as '15kHz' . | char , string |
Windowing | Optional | Nonnegative integer, default value depends on NPRACH preamble format in accordance with section F.5.F of [1] | Number of time-domain samples over which the function applies windowing and overlapping of OFDM samples. If you do not specify
this field, this function returns the | double |
Data Types: struct
chs
— Channel transmission configuration
structure
Channel transmission configuration, specified as a structure containing these fields.
Field | Required or Optional | Values | Description | Dependencies | Data Types |
---|---|---|---|---|---|
NPRACHFormat | Required | '0' , '1' ,
'2' | NPRACH preamble format | Not applicable | char , string |
Periodicity | Required | 40 , 80 , 160 ,
240
(since R2024b), 320 ,
640 , 1280 , 2560 ,
5120 | NPRACH resource periodicity, in milliseconds | If you set the If you set the
| double |
SubcarrierOffset | Required | 0 , 2 , 6 ,
12 , 18 , 24 ,
34 , 36 , 42 ,
48 , 54 , 60 ,
72 , 78 , 84 ,
90 , 102 ,
108 | Frequency location of the first subcarrier allocated to NPRACH | If you set the If you set
the | double |
NumSubcarriers | Required | 12 , 24 , 36 ,
48 , 72 , 108 ,
144 | Number of subcarriers allocated to NPRACH | If you set the If you set the
| double |
NRep | Required | 1 , 2 , 4 ,
8 , 16 , 32 ,
64 , 128 | Number of NPRACH repetitions | Not applicable | double |
StartTime | Optional | 8 (default), 16 ,
32 , 64 , 128 ,
256 , 512 ,
1024 | NPRACH starting time, in milliseconds | Not applicable | double |
NInit | Optional | 0 (default), integer in the interval [0,
NumSubcarriers – 1] | Initial subcarrier for NPRACH | Not applicable | double |
NPRACHPower | Optional | 0 (default), real-valued scalar | NPRACH power scaling, in decibels | Not applicable | double |
Data Types: struct
Output Arguments
waveform
— Time-domain NPRACH FDD waveform
complex-valued column vector
Time-domain NPRACH FDD waveform, returned as a complex-valued column vector of
length (chs
.
Periodicity
× info
.
SamplingRate
÷ 1000). The waveform consists of:
A period of zeros corresponding to the time,
chs
.
StartTime
, between the start of the transmission and the first frame occupied by an NPRACH symbol.The NPRACH transmission, defined in section 10.1.6.1 of [2] as a repetition of
chs
.
NRep
NPRACH preambles. An NPRACH preamble is a set ofinfo
.
P
symbol groups. A symbol group is a sequence ofinfo
.
N
identical symbols preceded by a cyclic prefix. The duration of an NPRACH preamble is a function of the preamble format as described in Table 10.1.6.1-1 of [2].A period of zeros corresponding to the time between the end of the transmission and the value of the
chs
.
Periodicity
input.
The function samples the waveform at the same sampling rate as for a narrowband
physical uplink shared channel (NPUSCH) waveform, defined by the
NBULSubcarrierSpacing
field of the ue
input.
For preamble formats 0 and 1, the function adds an additional 40 ms gap every 64 preambles. For preamble format 2, the function adds an additional 40 ms gap every 16 preambles.
For more information about NPRACH waveform generation, see the NB-IoT PRACH Waveform Generation example.
Data Types: double
Complex Number Support: Yes
info
— NPRACH resource information
structure
NPRACH resource information, returned as a structure containing these fields.
Field | Values | Description | Data Type |
---|---|---|---|
Nfft | Positive integer | Number of fast Fourier transform (FFT) points. | double |
SamplingRate | Positive scalar | Sampling rate, in Hz, of the time-domain waveform. | double |
Windowing | Nonnegative integer | Number of time-domain samples over which the function applies windowing and overlapping of OFDM symbols. | double |
FrequencyLocation | Row vector of nonnegative integers | Frequency location for all symbol groups in an NPRACH transmission. For more information about NPRACH symbol groups, see the NB-IoT PRACH Waveform Generation example. The kth element of this output represents the frequency location of the kth symbol group. | double |
K | Positive integer | Ratio of uplink data to NPRACH subcarrier spacing. | double |
NULSC | Positive integer | Number of subcarriers for the specified uplink bandwidth. | double |
PreambleParameters | Structure | Random access preamble parameters for the specified preamble format and frame structure type 1, as specified in Table 10.1.6.1-1 of [2]. | struct |
PreambleParameters
Field
The PreambleParameters
field of this output contains these
fields.
Field | Values | Description | Data Type |
---|---|---|---|
G | Positive integer | Number of time-contiguous symbol groups. | double |
P | Positive integer | Total number of symbol groups. | double |
N | Positive integer | Number of symbols in a symbol group. | double |
T_CP | Positive integer | Cyclic prefix length, in multiples of Ts, where Ts is the basic time unit, defined in section 4 of [2] as 1 ÷ (15000 × 2048) seconds. | double |
T_SEQ | Positive integer | Length of symbols in a symbol group, in multiples of Ts. | double |
Data Types: struct
resourceGrid
— NPRACH resource grid
real-valued matrix
NPRACH resource grid, returned as a real-valued matrix of size K-by-L, where:
K is the number of subcarriers.
L is the number of NPRACH symbols that fit the value of
chs
.
Periodicity
.
Data Types: double
References
[1] 3GPP TS 36.101. “Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio transmission and reception.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. https://www.3gpp.org.
[2] 3GPP TS 36.211. “Physical channels and modulation.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA). https://www.3gpp.org.
Version History
Introduced in R2021aR2024b: Generate NPRACH waveforms for 240 millisecond resource periodicity
You can now generate NPRACH waveforms for channel transmission configurations with an
NPRACH resource periodicity of 240 milliseconds. To use this feature, specify the
Periodicity
field of the chs
input as
240
. You must specify the NPRACHFormat
of
chs
as 0
or 1
.
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