ltePRACHInfo
PRACH resource information
Description
returns info
= ltePRACHInfo(ue
,chs
)info
, a structure containing PRACH resource information
given UE-specific settings, ue
, and channel transmission
configuration, chs
. For more information, see PRACH Information.
Examples
Find Root Zadoff-Chu Sequences from PRACH Information
Find the set of root Zadoff-Chu sequences required for all preamble indices (0,...,63) in a cell.
ue.NULRB = 6; config.Format = 0; config.CyclicShiftIdx = 8; config.PreambleIdx = (0:63); prachInfo = ltePRACHInfo(ue,config); unique(prachInfo.RootSeq)
ans = 1×4
129 140 699 710
Input Arguments
ue
— UE-specific settings
structure array
UE-specific settings, specified as a structure array that can contain these parameter fields.
Parameter Field | Required or Optional | Values | Description |
---|---|---|---|
NULRB | Required | 6, 9, 11, 15, 25, 27, 45, 50, 64, 75, 91, 100 | Number of uplink resource blocks. () |
DuplexMode | Optional |
| Duplexing mode, specified as either:
|
The following parameters
are dependent upon the condition that | |||
TDDConfig | Optional | 0, 1 (default), 2, 3, 4, 5, 6 | Uplink–downlink configuration |
SSC | Optional | 0 (default), 1, 2, 3, 4, 5, 6, 7, 8, 9 | Special subframe configuration (SSC) |
The following parameter
fields are dependent upon the condition that | |||
NSubframe | Optional | 0 (default), Nonnegative scalar integer | Subframe number |
NFrame | Optional | 0 (default), nonnegative scalar integer | Frame number |
The following parameter
fields are dependent upon the condition that the Preamble Format, | |||
CyclicPrefix | Optional |
| Cyclic prefix length |
Data Types: struct
chs
— Channel transmission configuration
scalar structure
Channel transmission configuration, specified as a scalar structure that can contain these parameter fields.
Parameter Field | Required or Optional | Values | Description |
---|---|---|---|
Format | Optional | 0, 1, 2, 3, 4 (default is determined by |
Preamble format See Note. |
SeqIdx | Optional | Scalar integer from 0 to 837. The default value is 0. | Logical root sequence index (RACH_ROOT_SEQUENCE) |
ConfigIdx | Optional | Scalar integer from 0 to 63. The default value is determined by
|
PRACH Configuration Index (prach-ConfigurationIndex) See Note. |
PreambleIdx | Optional | Scalar integer or vector of integers from 0 to 63. The default value is 0. | Preamble index within cell (ra-PreambleIndex) |
CyclicShiftIdx | Optional | Scalar integer from 0 to 15. The default value is 0. | Cyclic shift configuration index (zeroCorrelationZoneConfig, yields NCS) |
HighSpeed | Optional | 0 (default) or 1 | High Speed flag (highSpeedFlag). A value of 1 signifies a restricted set. A value of 0 signifies an unrestricted set. |
The following parameters
are dependent upon the condition that | |||
FreqIdx | Optional | 0 (default), 0, 1, 2, 3, 4, 5 | Frequency resource index (fRA).
Only required for |
The following parameter
fields are dependent upon the condition that the Preamble Format, | |||
FreqOffset | Optional | Scalar integer from 0 to 94. The default value is 0. | PRACH frequency offset (nPRBoffset). Only required for Preamble format 0–3. |
Note Although the parameters |
Data Types: struct
Output Arguments
info
— PRACH resource information
scalar structure
PRACH resource information, returned as a scalar structure. info
contains
the following fields.
NZC
— Zadoff-Chu sequence length
positive integer
Zadoff-Chu sequence length, returned as a positive integer. (N_ZC)
Data Types: double
SubcarrierSpacing
— Subcarrier spacing of PRACH preamble
positive integer
Subcarrier spacing of PRACH preamble, in Hz, returned as a positive integer. (deltaf_RA)
Data Types: double
Phi
— Frequency-domain location offset
positive integer
Frequency-domain location offset, returned as a positive integer. (phi)
Data Types: double
K
— Ratio of uplink data to PRACH subcarrier spacing
numeric scalar
Ratio of uplink data to PRACH subcarrier spacing, returned as a numeric scalar. (K)
Data Types: double
TotSubframes
— Number of subframes duration of PRACH
numeric scalar
Number of subframes duration of the PRACH, returned as a numeric
scalar. Each subframe lasts 30720 fundamental periods, therefore TotSubframes
is ceil(sum(Fields)/30720)
,
the number of subframes required to hold the entire PRACH waveform.
The duration of the PRACH is a function of the Preamble Format as
described in TS 36.211, Table 5.7.1-1 [2].
Data Types: double
Fields
— PRACH field lengths
1-by-4 numeric vector
PRACH field lengths, returned as a 1-by-4 numeric vector. The elements are [OFFSET T_CP T_SEQ GUARD]. T_CP and T_SEQ are the lengths in fundamental time periods (T_s), of cyclic prefix and PRACH sequence, respectively. OFFSET is the number of fundamental time periods from the start of configured subframe to the start of the cyclic prefix, and is non-zero only for TDD special subframes. GUARD is the number of fundamental time periods from the end of the PRACH sequence to the end of the number of subframes spanned by the PRACH.
Data Types: double
PRBSet
— PRBs occupied by PRACH preamble
nonnegative integer column vector
PRBs occupied by PRACH preamble, returned as a nonnegative integer column vector. (starts at n_PRB, zero-based).
Note
The PRACH uses a different SC-FDMA symbol construction from
the other channels, PUCCH, PUSCH, and SRS. Specifically, the PRACH
does not occupy the set of 12 subcarriers in each RB in the same fashion
as other channels. Therefore, the PRBSet
indicates
the frequency range, 180 kHz per RB, occupied by the PRACH. The PRACH
occupies a bandwidth approximately equal to 1.08 MHz, or 6RBs.
Data Types: uint32
NCS
— Length of zero correlation zone plus 1
positive integer
Length of zero correlation zone plus 1, specified as a positive
integer (NCS). NCS
corresponds
to the complete extent of autocorrelation lags (0 and NCS–1
non-zero) that exhibit perfect correlation properties (1 at 0 lag,
0 at non-zero lags). NCS
is expressed directly,
as in the standard, related to the fundamental Zadoff-Chu sequence
construction. The actual sample span of the zero correlation zone
in the waveform generated by ltePRACH
is
a function of the sampling rate.
Data Types: double
CyclicShift
— Cyclic shift or shifts of Zadoff-Chu sequence
numeric row vector
Cyclic shift or shifts of Zadoff-Chu sequence, returned as a numeric row vector. (C_v).
For High Speed mode, any element of CyclicShift
equal
to –1 indicates that there are no cyclic shifts in the restricted
set for the corresponding preamble index.
Data Types: double
RootSeq
— Physical root Zadoff-Chu sequence index or indices
numeric row vector
Physical root Zadoff-Chu sequence index or indices, required
to generate the PRACH for each of the configured set of preamble indices
returned as a numeric row vector. (u) RootSeq
is
either a vector or a scalar aligned with the configuration of chs.PreambleIdx
Data Types: double
CyclicOffset
— Cyclic shift or shifts corresponding to Doppler Shift
vector
CyclicOffset
values are cyclic shifts corresponding
to a Doppler Shift of 1/T_SEQ (d_u).
For High Speed mode, the field CyclicOffset
is present. It contains cyclic
offset values for each of the configured set of preamble
indices. CyclicOffset
is either a vector or a
scalar aligned with the configuration of
chs.PreambleIdx
.
Data Types: double
SamplingRate
— Sampling rate of PRACH modulator
numeric scalar
Sampling rate of the PRACH modulator, returned as a numeric scalar. The function computes the
sampling rate using the following equation:
SamplingRate = 30720000
/ 2048
×Nfft where
Nfft is a function
of the Number of Resource Blocks given by
ue
.
NULRB
.
NRB | 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×NRB/0.85
. It is the smallest FFT that spans all subcarriers and results in a bandwidth occupancy (12×NRB/Nfft) of no more than 85%.
Data Types: double
BaseOffset
— Base timing offset
numeric scalar
Base timing offset, in microseconds. This field is used for the detection test in TS 36.104 [1]. (duration of NCS/2)
Data Types: double
Data Types: struct
More About
PRACH Information
The parameters “PRACH Mask Index”
and “PRACH Resource Index,” described in TS 36.321 [3], are not explicit in the configuration,
but are implicit in the choice of ue
.NSubframe
and ue
.NFrame
.
The PRACH is always be generated provided it fits with the overall
duplexing arrangement. For FDD, the PRACH is generated in any subframe.
For TDD, the PRACH is generated only in special subframes for Preamble
Format 4, and in uplink subframes for Preamble Format 0-3, provided
there are info
.
TotSubframes
consecutive
uplink subframes for the chosen TDD configuration starting from the
current subframe.
If chs
.ConfigIdx
is
present, further validation is used to comply with TS 36.211 [2], Table 5.7.1-2 for FDD and
Table 5.7.1-4 for TDD. Specifically, chs
.Format
,
if present, is validated against chs
.ConfigIdx
and
a preamble is only generated in appropriate frames and subframes.
If chs
.Format
is absent, the
format is inferred, if possible, from chs
.ConfigIdx
.
If the entry in TS 36.211 [2],
Table 5.7.1-2 for FDD or Table 5.7.1-4 for TDD indicates “N/A”
for the preamble format, an error is issued.
For TDD, chs
.FreqIdx
corresponds
to the first entry in the quadruples in TS 36.211 [2], Table 5.7.1-4. The other three
entries (, , )
in the quadruple are specified by ue
.NSubframe
and ue
.NFrame
.
The PRACH is generated if a combination of chs
.ConfigIdx
, ue
.TDDConfig
, , ,
and given
by ue
.NSubframe
, ue
.NFrame
,
and chs
.FreqIdx
appears in
TS 36.211 [2], Table 5.7.1-4.
Note
In accordance with this logic,
if
chs
.ConfigIdx
is absent,ue
.NSubframe
andue
.NFrame
are not required at all for FDD.In the case that a preamble is not generated under these rules,
info
.
PRBSet
is empty and the waveform generated byltePRACH
consists of all zeros.
References
[1] 3GPP TS 36.104. “Evolved Universal Terrestrial Radio Access (E-UTRA); Base Station (BS) Radio Transmission and Reception.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.
[2] 3GPP TS 36.211. “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.
[3] 3GPP TS 36.214. “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer; Measurements.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.
Version History
Introduced in R2014a
See Also
Comando de MATLAB
Ha hecho clic en un enlace que corresponde a este comando de MATLAB:
Ejecute el comando introduciéndolo en la ventana de comandos de MATLAB. Los navegadores web no admiten comandos de MATLAB.
Select a Web Site
Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select: .
You can also select a web site from the following list:
How to Get Best Site Performance
Select the China site (in Chinese or English) for best site performance. Other MathWorks country sites are not optimized for visits from your location.
Americas
- América Latina (Español)
- Canada (English)
- United States (English)
Europe
- Belgium (English)
- Denmark (English)
- Deutschland (Deutsch)
- España (Español)
- Finland (English)
- France (Français)
- Ireland (English)
- Italia (Italiano)
- Luxembourg (English)
- Netherlands (English)
- Norway (English)
- Österreich (Deutsch)
- Portugal (English)
- Sweden (English)
- Switzerland
- United Kingdom (English)