CN115801213A - Planning method for random access sequence - Google Patents

Abstract

The invention discloses a planning method of a random access sequence, which comprises the steps of determining system parameters; calculating the minimum interval D (u) of adjacent correlation peaks of different u-value PRACH sequences; obtaining a sequencing logic root sequence list T; constructing a list of available ordered logical root sequences

To generate

Delivery in post-system broadcast messages

The sequence number of the first PRACH logic root sequence available for the cell is used; in PRACH detection, the base station uses

Description

Planning method for random access sequence

Technical Field

The invention relates to the technical field of wireless communication, in particular to a planning method of a random access sequence.

Background

In the current mobile communication technology represented by LTE (long term evolution, i.e., fourth generation mobile communication technology) and NR (new air interface, i.e., fifth generation mobile communication technology), a system completes uplink initial access synchronization of a terminal through a Physical Random Access Channel (PRACH). According to the protocol (the protocols in the invention refer to 3GPP TS38.211Realease16 edition protocol), in the transmitting process of PRACH, UE uses ZC sequence as PRACH root sequence to generate PRACH transmitting signal according to the protocol, base station transmits PRACH logical root sequence set which can be used by current cell through broadcast channel (different PRACH logical root sequences correspond to PRACH physical root sequences with same length and different u values (the physical root sequence of a certain u value represents ZC sequence generated by using the u value according to the protocol), the corresponding relation between the two is designed according to a certain rule, the introduction will be given below), different terminals randomly select 1 PRACH logical root sequence from PRACH logical root sequence set which can be used by current cell to generate PRACH transmitting signal. Because users in the cell all adopt the random access strategy, PRACH emission signals of different users at the same time-frequency position are possibly superposed in a base station receiving signal, and if different users select different PRACH logic root sequences in the PRACH detection process, the base station generates certain interference among the different users. Although the ZC sequence still has good cross-correlation characteristics (the interference between different physical root sequences is small) after Fourier transformation, in order to minimize the interference between different users in the process of detecting the PRACH of the base station and reduce the system signaling overhead, the protocol firstly carries out sequencing optimization on the ZC sequences with different u values according to the cross-correlation (the physical root sequences with small correlation are sequenced close to each other, and the sequencing is widened to the contrary), a PRACH logical root sequence list is obtained after sequencing, then the base station only needs to broadcast the available initial PRACH logical root sequence number of the current cell, and the terminal takes the initial PRACH logical root sequence number as the continuous starting point

And randomly selecting 1 PRACH logical root sequence to generate the PRACH transmitting signal.

In the prior art, when detecting the PRACH, the base station generally uses the size and position of the time domain correlation peak between the received signal and the PRACH logical root sequence to detect whether there is a user access request, and calculates the uplink time frequency offset of the user. In a large-delay large-frequency-offset scene (such as a low-orbit satellite communication system), a single user has multiple time-domain correlation peaks in a base station detection process, the base station estimates frequency offset through large-scale offset (the large-scale offset is defined as a part where the offset of a correlation peak exceeds the minimum interval of adjacent correlation peaks) of the correlation peaks, estimates time offset through small-scale offset (the small-scale offset is defined as a part where the offset of a correlation peak does not exceed the minimum interval of adjacent correlation peaks) of the correlation peaks, and in the process, the minimum interval of the adjacent correlation peaks is required to be not smaller than the maximum time offset of the system, otherwise, the base station cannot distinguish the large-scale offset from the small-scale offset. According to the existing theoretical analysis, it can be proved that the interval between adjacent correlation peaks depends on u values corresponding to the logical root sequence of the PRACH (a one-to-one correspondence relationship is formed between the two u values), so that the minimum interval between adjacent correlation peaks for the logical root sequence of the PRACH with some u values is smaller than the maximum time offset of the system, and the PRACH time frequency offset estimation cannot be completed by the base station.

Disclosure of Invention

Based on the defects in the prior art, the invention provides a planning method of a random access sequence, which has the following specific technical scheme:

a planning method of a random access sequence comprises the following steps:

s1, determining parameters based on a 3GPP TS38.211Realease16 version protocol system;

s2, calculating the minimum interval D (u) of adjacent correlation peaks of different u-value PRACH sequences;

wherein u is a PRACH serial number described in a 3GPPTS38.211Realease16 version protocol;

s3, obtaining a sequencing logic root sequence list T;

s4, forming a list of available sequencing logic root sequences

；

S5, during PRACH detection, the base station uses

The PRACH logic root sequence in the PRACH detection and time frequency offset estimation is carried out.

Specifically, the system parameter in step S1 includes a length of a PRACH sequence configured by the system

And the number of PRACH logical root sequences which can be used by the current cell

。

Specifically, the minimum interval between adjacent correlation peaks in step S2

The calculation formula of (A) is as follows:

wherein,

indicating the cyclic shift interval of adjacent correlation peaks,

to meet the need

And

is the smallest non-negative integer.

Specifically, the sorting logic root sequence list T in step S3 is

And sorting u from large to small.

Specifically, the list of the available logical root sequences in the step S4

Selecting available ones in T for the base station according to the system configuration

Serial numbers of the continuous logic root sequences;

wherein,

sorting logical root sequence lists for availability

The first item of (a) is,

sorting a list of logical root sequences for availability

The last item in (a) is,

the number of logical root sequences of PRACH which can be used by the current cell.

Specifically, the method also comprises the step of sending down in the system broadcast message

And the sequence number of the first PRACH logical root sequence available for the cell.

The invention firstly provides a calculation method of the minimum interval of adjacent correlation peaks of different u-value PRACH physical root sequence time domains, then uses the calculation result of the method to sequence and optimize the PRACH sequence of a protocol to generate a sequenced PRACH logical root sequence list, uses the sequenced PRACH logical root sequence list to replace the PRACH logical root sequence list of the existing protocol, and finally a base station selects and broadcasts the sequence number of a first logical root sequence in a cell.

The invention can achieve the following beneficial effects:

1) The invention maximizes the minimum interval of the correlation peaks of the PRACH logic root sequence selectable by the cell terminal, thereby remarkably improving the time-frequency offset estimation performance of the PRACH in a large time-frequency offset scene;

2) The invention only needs to replace the PRACH logic root sequence list in the protocol, and does not need to modify other communication behaviors of the base station and the terminal.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present invention, specific embodiments of the present invention will now be described.

Example 1

In this embodiment, the number of OFDM points of the system is assumed to be

Each time slot has 14 OFDM symbols (index is 0, …, 13), the CP length of the first OFDM symbol is 352, and the cyclic prefix length of the non-first symbol

The time domain signal length of the whole time slot is 61440 noted as

The 2 pilot symbols for frequency offset estimation are respectively located at symbol 2 and symbol 11, the number of pilot subcarriers configured for each symbol is M =1638 (the pilot subcarrier indexes are 410,412, …,3682,3684), the system subcarrier interval is f =30kHz, and the maximum possible frequency offset of the system is

Then, the embodiment mainly includes:

(1) Determining system parameters: the length of PRACH sequence configured by the system is

The number of logical root sequences of the PRACH that can be used by the current cell is 64;

(2) Calculating the minimum interval of adjacent correlation peaks of PRACH sequences with different u values

:

Wherein

To satisfy

The smallest non-negative integer of (c);

(3) According to

Ordering u from large to small (if different values of u are used)

Same, they can be sorted arbitrarily), a sorted logical root sequence list is obtained

As shown in table 1;

(4) Assuming that other PRACH logical root sequences except for {0,1,136,137} of the current cell configured by the high layer can be used, the base station generates

Then is sent down in the system broadcast message

The sequence number is used as the first PRACH logical root sequence number available for the cell;

(5) In PRACH detection, the base station uses

The PRACH logic root sequence in the PRACH detection and time frequency offset estimation is carried out.

The logical root sequence of the sequenced PRACH in this embodiment is shown in table 1:

table 1 ordered PRACH logical root sequence list

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed.

Claims (6)

1. A method for planning a random access sequence is characterized by comprising the following steps:

s1, determining parameters based on a 3GPP TS38.211Realease16 version protocol system;

s2, calculating the minimum interval D (u) of adjacent correlation peaks of different u-value PRACH sequences;

wherein u is a PRACH serial number described in a 3GPPTS38.211Realease16 version protocol;

s3, obtaining a sequencing logic root sequence list T;

s4, forming a list of available sequencing logic root sequences

；

S5, during PRACH detection, the base station uses

The PRACH logic root sequence in the PRACH detection and time frequency offset estimation is carried out.

2. The method for planning a random access sequence of claim 1, wherein the system parameters in step S1 include a length of a PRACH sequence configured by a system

And the number of PRACH logical root sequences which can be used by the current cell

。

3. The method for planning a random access sequence of claim 2, wherein the minimum interval between adjacent correlation peaks in step S2

The calculation formula of (A) is as follows:

wherein,

representing the cyclic shift interval of adjacent correlation peaks,

to meet the need

And

is the smallest non-negative integer.

4. A method for random access sequence planning as claimed in claim 2, characterized in thatThe sorting logic root sequence list T in the step S3 is

And sorting u from large to small.

5. The method for planning random access sequence of claim 2, wherein the list of available logical root sequences of the ordering in step S4

Selecting available ones in T for the base station according to the system configuration

Serial numbers of continuous logic root sequences;

wherein,

sorting a list of logical root sequences for availability

The first item of (a) is,

sorting a list of logical root sequences for availability

The last item in (2) is,

the number of logical root sequences of PRACH which can be used by the current cell.

6. The method of claim 5, further comprising down-sending in a system broadcast message

And the sequence number of the first PRACH logical root sequence available for the cell.