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User activity-based contention transmission unit (CTU) allocation method in uplink license-free SCMA

A technology of user activity and allocation method, which is applied in the field of CTU allocation in uplink authorization-free SCMA, can solve problems such as high computational complexity and high probability of CTU collision, and achieve low complexity, reduced collision probability, and reduced complexity Effect

Active Publication Date: 2018-11-13
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to solve the problem of high probability of CTU collision between users and high computational complexity in the existing CTU allocation, and propose an uplink authorization-free SCMA CTU allocation method based on user activity

Method used

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  • User activity-based contention transmission unit (CTU) allocation method in uplink license-free SCMA
  • User activity-based contention transmission unit (CTU) allocation method in uplink license-free SCMA
  • User activity-based contention transmission unit (CTU) allocation method in uplink license-free SCMA

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specific Embodiment approach 1

[0029] Specific implementation mode 1: The specific process of the CTU allocation method of the uplink license-free SCMA based on user activity in this implementation mode is as follows:

[0030] Therefore, in order to reduce the packet loss rate caused by CTU collision and further improve the sum rate of the entire uplink SCMA system, the present invention introduces user activity as an evaluation index to assist the base station in completing the allocation of CTU resources. The present invention considers the following Internet of Things scenario: the activity of each user is different, and their activity is in a quasi-static state, that is to say, the probability that each user is allowed to access within a period of time obeys a distribution of its activity. At the same time, the user's access probability within a period of time can also be used to estimate the user's activity in the next period of time. In addition, the present invention deduces the expression of CTU co...

specific Embodiment approach 2

[0068] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that in the step 1, in the license-free uplink SCMA system, the average CTU corresponding to the L CTUs of N_length users is calculated in T' time slots Collision probability, the average CTU collision probability is simplified to obtain the NP-hard optimization formula; the specific process is:

[0069]

[0070] in,

[0071] g nl ={0,1} indicates the allocation relationship between the nth user and the lth CTU, if g nl =1, it means that the nth user is assigned to the lth CTU, otherwise if g nl = 0 means that the nth user and the lth CTU are not paired;

[0072] g n =[g n1 g n2 ... g nL ] T Indicates the allocation relationship vector of the nth user; T is the transpose;

[0073] g l =[g 1l g 2l ... g N_lengthl ] T Indicates the allocation relationship vector of the lth CTU;

[0074] W n (t) is the activity used to represent the probability that the nth use...

specific Embodiment approach 3

[0085] Specific implementation mode three: the difference between this implementation mode and specific implementation mode one or two is: set P in the step three co (m) represents the CTU collision probability of the first m users in the set N' obtained in step 2, ΔP(m)=[P co (m)-P co (m-1)] represents the CTU collision increment that occurs when the mth user is considered to access the license-free uplink SCMA system, and iteratively optimizes ΔP(m) to obtain the optimal solution g for each time m , according to each optimal solution g m , get the optimal solution set G'={g 1 ,...g m ,..., g N_length′}; the specific process is:

[0086] m=0, when the number of access users m≤L, it is not necessary to complete the CTU allocation through optimization calculation at this time, according to Just assign a different CTU to each user;

[0087] mod is to take the remainder;

[0088] When the number of access users m>L, the CTU collision increment that occurs when the mth us...

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Abstract

The invention relates to a user activity-based contention transmission unit (CTU) allocation method in uplink license-free SCMA. The invention relates to the CTU allocation method. The invention aimsto solve problems in the existing CTU allocation method that CTU collision probability between users is high and the calculation complexity is high. The method comprises the steps of first, in a license-free uplink SCMA system, calculating and obtaining an average CTU collision probability corresponding to L CTUs of N_length users in T' timeslots, and simplifying the average CTU collision probability so as to obtain a NP-hard optimization formula; second, ranking users n according to activity Wn in a descending order, and allocating different priorities, wherein N' represents a new set generated by ranking user sets N according to activity in a descending order; third, obtaining an optimal solution set; and fourth, obtaining a user-CTU allocation relationship matrix according to N, N' andthe optimal solution set. The method is used in the field of allocation of CTU of SCMA.

Description

technical field [0001] The invention relates to a CTU allocation method in uplink license-free SCMA. Background technique [0002] The huge demand of wireless communication for massive access, low latency, and high throughput makes the fifth generation mobile communication (the fifth generation, 5G) a hot topic in current research. 5G can meet higher quality of service (QoS) requirements and meet Internet of things (IoT) scenarios. [0003] However, as a key technology of the Long Term Evolution (LTE) system, the orthogonal multiple access technology (orthogonal frequency division multiple access, OFDMA) divides the frequency band into multiple mutually orthogonal subcarriers, and divides these subcarriers They are assigned to different users to achieve multiple access. Limited by this orthogonal division method, the user gain of OFDMA will not exceed 1, which cannot meet the needs of massive access. At the same time, the transmission of uplink LTE follows the mode of req...

Claims

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Application Information

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IPC IPC(8): H04W72/10H04W72/04H04W74/08
CPCH04W74/08H04W72/53H04W72/56
Inventor 吴玮孙俊伟吴宣利薛彤郭珊张立强
Owner HARBIN INST OF TECH
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