A method for searching free time slots in vdes frame mapping table based on block division

A technology of idle time slot and time slot, which is applied in the field of searching for idle time slots in the VDES frame map table based on block division, can solve the problem of reducing time slot reservation and access delay, and increasing time slot reservation and access delay , search conflicts and other problems, to achieve the effect of reducing reservation and access delays, and reducing the number of search conflicts

Active Publication Date: 2022-04-12
山东星通易航通信科技有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These free time slot search methods are prone to time slot conflicts (that is, the slots are already occupied), and when encountering continuous free time slot requests, the probability of finding conflicts will be greater
Moreover, with the increase in the number of ships at sea, the number of search conflicts of these free time slot search methods will also increase, resulting in increased time slot reservation and access delays, and increased data transmission delays.
However, the current development of the marine transportation industry has put forward higher and higher requirements for maritime communications. The existing search methods for free time slots cannot meet the actual needs due to the large delay when there are a large number of ships. Therefore, it is necessary to develop search methods. A free time slot search method with less conflicts to reduce time slot reservation and access delay

Method used

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  • A method for searching free time slots in vdes frame mapping table based on block division
  • A method for searching free time slots in vdes frame mapping table based on block division
  • A method for searching free time slots in vdes frame mapping table based on block division

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Embodiment 1

[0037] Such as figure 1 Shown, a kind of VDES frame mapping table free time slot search method based on block division disclosed by the present invention comprises the following steps:

[0038] Step 1: Initialize the frame mapping table, that is, divide the time slots in the frame mapping table into areas and blocks:

[0039] Such as figure 2 The division and block division of the frame mapping table shown in the frame mapping table first divides the time slots in the frame mapping table into areas, assuming that there are L request access messages, and the lth request access message needs to occupy R l consecutive free time slots, l∈{1,2,…,L}, suppose there are three kinds of continuous free time slot requirements, which are 1 to 3 consecutive free time slots, that is, R l∈{1,2,3}, corresponding to divide the frame mapping table into 3 areas, the first area is from 0 to N-1 time slots, the number of time slots T 1 =N, the channels in this area are all R l =1 needs to acc...

Embodiment 2

[0059] Embodiment 2 (experimental example)

[0060] The following is a simulation experiment of MATLAB software carried out according to a VDES frame mapping table free time slot search method based on block division disclosed by the present invention, to illustrate the feasibility and effectiveness of the method of the present invention.

[0061] During the simulation, the number of time slots in one frame in the mapping table is 2250, assuming that half of the time slots in the current frame have been randomly occupied, that is, the network load is heavy. The division of the three areas is N=1000, M=2100, and the division of the block is Q=5. The number of consecutive idle time slots required for the access request message is randomly generated among 1, 2, and 3.

[0062] Figure 4 The "sequential search of SOTDMA", "random search of RATDMA" and "incremental search of ITDMA" in the existing G1139 standard proposal are the free time slot search methods, and the "search base...

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Abstract

The invention belongs to the technical field of wireless communication, and in particular relates to a method for searching free time slots in a VDES frame mapping table based on block division. Block division; according to the frame mapping table divided into areas and blocks, search and reserve free time slots for request access messages. Compared with the sequential search of existing SOTDMA, the random search of RATDMA, and the increment search method of ITDMA, the present invention increases the block division of the frame map table, and for the frame map table after the block is divided, according to the block Small-scale search is performed in a distributed manner, so the method disclosed in the present invention can effectively reduce the number of conflicts in the free time slot search, and reduce time slot reservation and access delay.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, and in particular relates to a block division-based VDES frame mapping table idle time slot search method. Background technique [0002] VHF Data Exchange System (VDES) is a new generation of maritime communication system, which provides security and data communication services for ships navigating at sea. [0003] Ships within the range of communication capabilities form an ad hoc cell, and use channel resources in a Time-division Multiple Access (TDMA) manner. Time is divided into segments in units of frames, each frame is 1 minute in length, and each frame is divided into 2250 time slots. Each ship in the self-organizing cell saves and updates a frame mapping table, which is used to record whether the time slot in the current frame is idle or in use. If the ship needs to send data, it needs to send a request access message first, and the system searches the free time slots in ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04W72/04H04L5/00
CPCH04W72/0446H04L5/0078H04L5/0058H04W72/53
Inventor 李洪星丁晓光
Owner 山东星通易航通信科技有限公司
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