CN115379502A

CN115379502A - Novel protocol sequence set construction method for authorization-free access

Info

Publication number: CN115379502A
Application number: CN202210638396.7A
Authority: CN
Inventors: 郑一廿; 张一晋; 刘芳; 罗元勋
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2022-06-08
Filing date: 2022-06-08
Publication date: 2022-11-22

Abstract

The invention discloses a novel protocol sequence set construction method for license-free access, which comprises constructing a primary selection new sequence set based on any sequence of a CRT sequence set, selecting the primary selection new sequence set with the minimum sum of maximum Hamming cross correlation with other sequences to form an alternative new sequence set, selecting the minimum uniformity sequence in the alternative new sequence set to replace the current sequence, and constructing a novel protocol sequence set which meets the target code re-requirement in an iteration mode based on the processes. The invention can construct a novel protocol sequence set with higher code weight, lower Hamming cross correlation and lower sequence uniformity aiming at any total equipment number, and can provide sending opportunities with reasonable times and even distribution for each equipment, thereby reducing the average time delay, and having better time delay performance compared with other authorization-free access schemes.

Description

Novel protocol sequence set construction method for authorization-free access

Technical Field

The invention belongs to the technical field of wireless network communication, and particularly relates to a novel protocol sequence set for unauthorized access.

Background

With the rapid development of information technology, a new generation of network based on and expanded by the internet, namely the internet of things, is generated. Many application scenarios of the internet of things require each data packet to be transmitted with high reliability within a strict transmission time limit, so that it is important to design a transmission strategy under the constraint of a time limit with excellent performance. Massey and Mathys propose a protocol sequence set in 1985 to ensure feedback-free high-reliability transmission, wong proposes a UI property taking minimum maximum time delay as a design target in 2007 to simultaneously ensure the reliability and timeliness of transmission, shum et al constructs a CRT sequence set with the UI property in 2010, and Zhang et al constructs a CRTm sequence set with higher code weight and UI property in 2019. However, past work has focused on how to construct UI sequence sets with as short sequence periods as possible to minimize the maximum delay, and lack optimization of code weights and sequence structure to reduce the average delay. The invention aims to provide a novel protocol sequence construction method for the unlicensed access, the constructed protocol sequence has higher code weight, lower Hamming cross-correlation and lower sequence uniformity, and can provide sending opportunities with reasonable times and even distribution for each device, thereby reducing the average time delay and having better time delay performance compared with other unlicensed access schemes.

Disclosure of Invention

The invention aims to provide a novel protocol sequence set construction method for the unlicensed access, which can provide more reasonable sending times and more evenly distributed sending opportunities for each device, thereby reducing the average time delay and having better time delay performance compared with other access protocols. The technical scheme for realizing the purpose of the invention is as follows: a novel protocol sequence set construction method for authorization-free access comprises the following specific steps:

step 1: given the number of devices M, define p _M Setting the current constructed sequence set U as the period length L = p for the minimum prime number not less than M _M (2M-1) 0,1 binary CRT sequence set U. The target code weight value is set to N =2M, and i =1 is set.

And 2, step: obtaining a current U sequence S _i Code weight w of _i If w is _i If < N, entering step 3, otherwise, ending the sequence construction.

And step 3: respectively combine the sequences S _i Setting the 0 position in (A) to 1 to obtain L-w _i Initial selection of new sequence S _i ', select the sequence S in the current U _i Several alternative new sequences S with minimum sum of maximum Hamming cross-correlation of other sequences _i ', constituting an alternative set C _i 。

And 4, step 4: at C _i To select a sequence S with the minimum uniformity to replace the current U sequence _i And generating a new U.

And 5: if i < M, set i = i +1 and return to step 2, otherwise set i =1 and return to step 2.

Drawings

Fig. 1 is a flow chart of a novel protocol sequence set construction method of the present invention.

Fig. 2 is a comparison of average delay of three unlicensed transmission strategies in embodiment 1 under different device numbers M.

Detailed Description

The invention constructs a novel protocol sequence set for the authorization-free access. As shown in fig. 1, the specific implementation process includes:

Step 1-1: given the number M of devices, finding the minimum prime number p not less than the number M of devices _M Setting sequence period to be L = p _M (2M-1)；

Step 1-2: define the set of arbitrary positive integers modulo n as

Step 1-3: according to the Chinese remainder theorem, defining a mapping relation:

to make one-dimensional sequence correspond to two-dimensional matrix one-to-one, define:

obtaining a sequence feature set I according to the formula _g Comprises the following steps:

wherein g may be from 1 to p _M Of an arbitrary integer, set of sequence features I _g Characterization of CRT sequence set sequence S _g Position of 1.

And step 3: respectively combine the sequences S _i Set the 0 position in (1) to obtain L-w _i Primary selection of new sequence S _i ', select the sequence S in the current U _i Several alternative new sequences S with minimum sum of maximum Hamming cross-correlation of other sequences _i ', constituting an alternative set C _i 。

Step 3-1: sequentially converting the sequence S in the current U _i Respectively set to 1 at the 0 position in the sequence to obtain L-w _i Primary selection of new sequence S _i '；

Step 3-2: defining maximum Hamming cross-correlation as the maximum value of the number of positions of two sequences which simultaneously take the value of 1 under any cyclic displacement, and respectively calculating L-w _i Initial selection of new sequence S _i ' with the sequence S in the current U _i The maximum Hamming cross-correlation of each sequence except the other sequences is selected to be related to the sequence S in the current U _i Initial selection of new sequence S with minimum sum of maximum Hamming cross-correlation of other sequences _i ', constituting an alternative set C _i 。

And 4, step 4: at C _i To select a sequence with the minimum uniformity to replace the sequence S of the current U _i And generating a new U.

Step 4-1: the uniformity of a sequence is calculated as the sum of the squares of the distances between adjacent 1-valued locations in the sequence.

Step 4-2: in alternative set C _i In the random selection of oneReplacing the sequence S in the current U with the sequence with the least uniformity _i And generating a new U.

Example 1

The method is implemented by MATLAB software. Setting M =10, adopting the invention to construct a novel protocol sequence set, each sequence S of which _i Feature set I of _i As follows.

I ₁ ＝{1,20,29,39,49,58,68,77,87,96,115,125,134,144,153,163,172,181,191,200}

I ₂ ＝{1,14,28,44,52,60,71,79,87,95,103,111,119,127,135,148,162,178,194,202}

I ₃ ＝{1,12,24,30,36,47,59,65,71,82,94,105,117,128,140,152,164,175,186,198}

I ₄ ＝{1,12,22,32,43,54,64,74,85,95,106,116,127,137,148,158,169,179,190,200}

I ₅ ＝{1,13,26,40,53,65,72,79,91,104,111,118,131,143,157,170,182,189,196,203}

I ₆ ＝{1,13,25,31,38,50,62,74,86,93,99,111,123,129,136,148,160,173,185,197}

I ₇ ＝{1,15,29,38,46,54,63,71,80,88,97,111,125,134,142,159,167,176,184.193}

I ₈ ＝{1,21,31,41,51,61,71,81,91,101,111,121,131,141,151,161,171,181,191,201}

I ₉ ＝{1,14,27,42,49,57,70,83,90,98,111,124,132,139,154,167,180,188,195,203}

I ₁₀ ＝{1,12,23,34,45,56,67,73,78,89,100,111,122,133,144,155,166,177,188,199}

In the simulation scenario, M devices with unknown asynchronous clocks in a wireless network send data to a base station, and it is assumed that each device always has a data sending requirement and is within a receivable range of the base station, channel time is in a unit of time slot, and all data packet lengths are one unit of time slot. When each device adopts the authorization-free connection based on the protocol sequence setWhen entering the scheme, the distributed protocol sequence values are read according to time slots, and data can be sent if and only if the sequence value is 1; and when each device adopts the ALOHA-based unlicensed access scheme, data is transmitted with a fixed probability by time slots. And comparing the time delay performance of the following three authorization-free access schemes in the simulation scene. The first scheme is as follows: and based on the optimal ALOHA authorized access with the fixed access probability of 1/M. Scheme II: based on the period length of L = p _M (2M-1) and accessing the CRT sequence set with the code weight of M without authorization. The third scheme is as follows: based on the novel protocol sequence set constructed by the invention, the access is free from authorization.

As shown in table 1, it can be seen that the new protocol sequence set designed by the present invention for unlicensed access can achieve better average latency performance under the condition of M =10,12.

Claims

1. A novel protocol sequence set construction method for authorization-free access is characterized by comprising the following specific steps:

And 2, step: obtaining the current U sequence S _i Code weight w of _i If w is _i If the result is less than N, the step 3 is carried out, otherwise, the sequence construction is finished.

And 3, step 3: respectively combine the sequences S _i Setting the 0 position in (A) to 1 to obtain L-w _i Primary selection of new sequence S _i ', select the sequence S in the current U _i Several alternative new sequences S with minimum sum of maximum Hamming cross-correlation of other sequences _i ', constituting an alternative set C _i 。

2. The method for constructing a novel protocol sequence set of unlicensed access according to claim 1, wherein the specific method for constructing CRT sequence set U according to the parameters in step 1 is:

step 1-1: given the number of devices M, finding the minimum prime number p not less than the number of devices M _M Setting sequence period as L = p _M (2M-1)；

Step 1-2: define the set of any positive integer modulo n as

wherein g may be 1 to p _M Of an arbitrary integer, set of sequence features I _g Characterization of CRT sequence set sequence S _g Position of 1.

3. The method for constructing a novel protocol sequence set free from authorized access according to claim 1, wherein the specific method in step 2 is as follows: obtaining a current U middle sequence S _i Code weight w of _i I.e. sequence S _i Number of 1 in (1). If w is _i If the result is less than N, the step 3 is carried out, otherwise, the sequence construction is finished.

4. The method for constructing new protocol sequence set without authorization access according to claim 1, wherein the step 3 of searching and current S in U is _i Alternative set C with minimum sum of maximum Hamming cross-correlation of other sequences _i The specific method comprises the following steps:

Step 3-2: defining maximum Hamming cross-correlation as the maximum value of the number of positions of two sequences which simultaneously take the value of 1 under any cyclic displacement, and respectively calculating L-w _i Primary selection of new sequence S _i ' with sequence S in current U _i The maximum Hamming cross-correlation of each sequence except the other sequences is selected to be related to the sequence S in the current U _i Initial selection of new sequence S with minimum sum of maximum Hamming cross-correlation of other sequences _i ', constituting an alternative set C _i 。

5. The method for constructing a novel protocol sequence for unlicensed access according to claim 1, wherein step 4 is performed in alternative set C _i Selecting a sequence with the minimum evenness to replace the sequence S in the current U _i The specific method comprises the following steps:

step 4-1: the uniformity of a sequence is calculated as the sum of the squares of the distances between adjacent 1-valued positions in the sequence.

Step 4-2: in alternative set C _i Randomly selecting a sequence with the minimum uniformity to replace the sequence S in the current U _i And generating a new U.

6. The method for constructing a novel protocol sequence set free from authorized access according to claim 1, wherein the specific method in step 5 is as follows: if i < M, set i = i +1 and return to step 2, otherwise set i =1 and return to step 2.