• شماره ركورد
    34409
  • پديد آورنده

    فاطمه رئيسي امجد

  • عنوان
    ﺑﻬﺒﻮد واﮔﺬاري در ﺳﯿﺴﺘﻢ ﻫﺎي ﻣﻮﺑﺎﯾﻞ ﻧﺴﻞ ﭘﻨﺠﻢ ﺑﺎ ارﺗﺒﺎﻃﺎت ﻣﺎﻫﻮاره اي
  • مقطع تحصيلي
    ارشد
  • رشته تحصيلي
    مهندسي كامپيوتر - شبكه هاي كامپيوتري
  • سال تحصيل
    1401
  • تاريخ دفاع
    1404/07/30
  • استاد راهنما
    دكتر ناصر مزيني
  • استاد مشاور
    دكتر احمد اكبري ازيراني
  • دانشكده
    كامپيوتر
  • چكيده
    ﻫﻤﮕﺮاﯾﯽ ﺷﺒﮑﻪ ﻫﺎي ﻣﺨﺎﺑﺮاﺗﯽ ﻧﺴﻞ ﭘﻨﺠﻢ و ﺷﺒﮑﻪ ﻫﺎي ﻏﯿﺮزﻣﯿﻨﯽ، ﺑﻪ وﯾﮋه ﺑﺎ ﺑﻬﺮه ﮔﯿﺮي از ﻣﺎﻫﻮاره ﻫﺎي ارﺗﻔﺎع ﭘﺎﯾﯿﻦ زﻣﯿﻦ، راﻫﮑﺎري ﻣﻬﻢ ﺑﺮاي ﺗﺤﻘﻖ ﭘﻮﺷﺶ ارﺗﺒﺎﻃﯽ ﺟﻬﺎﻧﯽ، ﻓﺮاﮔﯿﺮ و ﺑﺎﮐﯿﻔﯿﺖ اﺳﺖ. ﺑﺎ اﯾﻦ ﺣﺎل، ﭘﻮﯾﺎﯾﯽ ﺑﺴﯿﺎر ﺑﺎﻻي ﻣﺎﻫﻮاره ﻫﺎي ﻣﺪارﭘﺎﯾﯿﻦ زﻣﯿﻦ ﻧﺴﺒﺖ ﺑﻪ ﭘﺎﯾﺎﻧﻪ ﻫﺎي زﻣﯿﻨﯽ، ﻣﻨﺠﺮ ﺑﻪ ﭼﺎﻟﺸﯽ ﺟﺪي ﺑﺮاي واﮔﺬاري ﻣﮑﺮر در اﯾﻦ ﺳﯿﺴﺘﻢ ﻣﯽ ﺷﻮد. اﯾﻦ ﻓﺮآﯾﻨﺪ در ﺷﺒﮑﻪ ﻫﺎي ﻣﺎﻫﻮاره اي، ﺑﺮﺧﻼف ﺷﺒﮑﻪ ﻫﺎي زﻣﯿﻨﯽ، ﻋﻤﺪﺗﺎ ً ﻧﺎﺷﯽ از ﺣﺮﮐﺖ ﺳﺮﯾﻊ ﻣﺎﻫﻮاره اﺳﺖ و ﺗﮑﺮار ﺑﯽ روﯾﻪ آن ﺑﻪ اﻓﺰاﯾﺶ ﺳﺮﺑﺎر ﺳﯿﮕﻨﺎﻟﯿﻨﮓ، اﻓﺖ ﮐﯿﻔﯿﺖ ﺧﺪﻣﺎت و ﺗﺠﺮﺑﻪ ﮐﺎرﺑﺮي ﻧﺎﻣﻄﻠﻮب ﻣﻨﺠﺮ ﻣﯽ ﮔﺮدد. اﯾﻦ ﭼﺎﻟﺶ ﺑﺎ رﻗﺎﺑﺖ ﻫﻤﺰﻣﺎن ﮐﺎرﺑﺮان ﻣﺘﻌﺪد ﺑﺮاي اﺗﺼﺎل ﺑﻪ ﻣﺎﻫﻮاره ﻫﺎﯾﯽ ﺑﺎ ﺑﻬﺘﺮﯾﻦ ﺷﺮاﯾﻂ ﺳﯿﮕﻨﺎﻟﯽ ﺗﺸﺪﯾﺪ ﺷﺪه و ﺑﻪ اﯾﺠﺎد ﮔﻠﻮﮔﺎه ﻫﺎي ﺗﺮاﻓﯿﮑﯽ و اﻓﺰاﯾﺶ ﻧﺮخ اﻧﺴﺪاد ﻣﯽ اﻧﺠﺎﻣﺪ. روش ﻫﺎي واﮔﺬاري ﺳﻨﺘﯽ ﮐﻪ ﻣﺒﺘﻨﯽ ﺑﺮﻣﻌﯿﺎرﻫﺎي ﻣﺤﻠﯽ )ﻣﺎﻧﻨﺪ ﻗﺪرت ﺳﯿﮕﻨﺎل( ﻫﺴﺘﻨﺪ، ﺑﻪ دﻟﯿﻞ ﺗﺄﺧﯿﺮ اﻧﺘﺸﺎر ﺑﺎﻻ و ﻋﺪم دﯾﺪ ﺟﺎﻣﻊ از وﺿﻌﯿﺖ ﺷﺒﮑﻪ، در اﯾﻦ ﻣﺤﯿﻂ ﭘﻮﯾﺎ ﮐﺎراﯾﯽ ﺧﻮد را از دﺳﺖ ﻣﯽ دﻫﻨﺪ. اﯾﻦ ﭘﮋوﻫﺶ ﺑﺎ ﻫﺪف ﻏﻠﺒﻪ ﺑﺮ ﭼﺎﻟﺶ ﻫﺎي ﻣﺬﮐﻮر، ﯾﮏ ﭼﺎرﭼﻮب ﻫﻮﺷﻤﻨﺪ و آﯾﻨﺪه ﻧﮕﺮاﻧﻪ ﺑﺮاي ﻣﺪﯾﺮﯾﺖ ﻓﺮآﯾﻨﺪ واﮔﺬاري اراﺋﻪ ﻣﯽ دﻫﺪ. در اﯾﻦ ﭘﮋوﻫﺶ ﻣﺴﺌﻠﻪ واﮔﺬاري ﺑﻪ ﻋﻨﻮان ﯾﮏ ﻓﺮاﯾﻨﺪ ﺗﺼﻤﯿﻢ ﮔﯿﺮي ﻣﺎرﮐﻮف ﻣﺪل ﺳﺎزي ﺷﺪه ﮐﻪ در آن، ﮐﺎرﺑﺮ ﺑﻪ ﻋﻨﻮان ﯾﮏ ﻋﺎﻣﻞ ﻫﻮﺷﻤﻨﺪ، از ﻃﺮﯾﻖ ﺗﻌﺎﻣﻞ ﺑﺎ ﻣﺤﯿﻂ ﺷﺒﮑﻪ و ﺑﺎ ﺑﻬﺮه ﮔﯿﺮي از اﻟﮕﻮرﯾﺘﻢ ﯾﺎدﮔﯿﺮي ﺗﻘﻮﯾﺘﯽ ﻋﻤﯿﻖ ﺳﯿﺎﺳﺖ ﺑﻬﯿﻨﻪ اي ﺑﺮاي اﻧﺘﺨﺎب ﻣﺎﻫﻮاره ﻫﺪف ﻣﯽ آﻣﻮزد. ﯾﮑﯽ از ﻧﻮآوري ﻫﺎي ﮐﻠﯿﺪي اﯾﻦ ﭘﮋوﻫﺶ، ﻃﺮاﺣﯽ ﯾﮏ ﺗﺎﺑﻊ ﭘﺎداش ﭼﻨﺪﻫﺪﻓﻪ اﺳﺖ ﮐﻪ ﺑﺎ ﺟﺮﯾﻤﻪ دﻫﯽ ﺑﻪ واﮔﺬاري ﻫﺎي ﻏﯿﺮﺿﺮوري و ﭘﺎداش دﻫﯽ ﺑﻪ اﻧﺘﺨﺎب ﻫﺎي ﺑﻬﯿﻨﻪ، ﻋﺎﻣﻞ را ﺑﻪ ﺳﻤﺖ اﺗﺨﺎذ ﺗﺼﻤﯿﻤﺎﺗﯽ ﻫﺪاﯾﺖ ﻣﯽ ﮐﻨﺪ ﮐﻪ ﺑﻪ ﻃﻮر ﻫﻤﺰﻣﺎن ﺳﻪ ﻫﺪف ﮐﻠﯿﺪي را ﻣﺤﻘﻖ ﺳﺎزد: ﮐﺎﻫﺶ ﺗﻌﺪاد واﮔﺬاري ﻫﺎ، ﺗﻮازن ﺑﺎر ﺗﺮاﻓﯿﮑﯽ در ﺷﺒﮑﻪ و ﺣﻔﻆ ﮐﯿﻔﯿﺖ ﺧﺪﻣﺎت. ﻧﺘﺎﯾﺞ ﺷﺒﯿﻪ ﺳﺎزي ﻫﺎ ﻧﺸﺎن ﻣﯽ دﻫﺪ ﮐﻪ روﯾﮑﺮد ﭘﯿﺸﻨﻬﺎدي ﻧﻪ ﺗﻨﻬﺎ ﻓﺮﮐﺎﻧﺲ واﮔﺬاري را ﺑﻪ ﺷﮑﻞ ﭼﺸﻤﮕﯿﺮي ﮐﺎﻫﺶ ﻣﯽ دﻫﺪ، ﺑﻠﮑﻪ ﺑﺎ ﺗﻮاﻧﺎﯾﯽ در ﭘﯿﺶ ﺑﯿﻨﯽ اﻓﺖ ﮐﯿﻔﯿﺖ ﺳﯿﮕﻨﺎل و ﺗﺼﻤﯿﻢ ﮔﯿﺮي ﭘﯿﺸﮕﯿﺮاﻧﻪ دارد ﻫﻤﭽﻨﯿﻦ ﻧﺮخ اﻧﺴﺪاد اﺗﺼﺎل را ﻧﯿﺰ ﺑﻪ ﻃﻮر ﻗﺎﺑﻞ ﻣﻼﺣﻈﻪ اي ﻣﻬﺎر ﮐﺮده و ﭘﺎﯾﺪاري و ﮐﺎراﯾﯽ ﮐﻞ ﺳﯿﺴﺘﻢ را در ﺷﺒﮑﻪ ﻫﺎي ﻧﺴﻞ آﯾﻨﺪه ﺑﻪ ﺷﮑﻞ ﻣﺆﺛﺮي ﺗﻀﻤﯿﻦ ﻣﯽ ﻧﻤﺎﯾﺪ.
  • تاريخ ورود اطلاعات
    1404/09/26
  • عنوان به انگليسي
    Improvement of Handover in 5G Mobile Systems using Satellite Communications
  • تاريخ بهره برداري
    1/21/2026 12:00:00 AM
  • دانشجوي وارد كننده اطلاعات

    فاطمه رئيسي امجد

  • چكيده به لاتين
    The convergence of 5G communication networks an‎d non-terrestrial networks (NTNs), particularly leveraging Low Earth Orbit (LEO) satellites, is a key strategy for achieving global, ubiquitous, an‎d high-quality connectivity. However, the extremely high mobility of LEO satellites relative to ground terminals introduces a significant challenge: frequent han‎dovers. In satellite networks, unlike terrestrial ones, this process is primarily driven by the satellite’s rapid movement, an‎d its excessive repetition leads to increased signaling overhead, degraded Quality of Service (QoS), an‎d a poor user experience. This challenge is further aggravated by the simultaneous competition of multiple users vying for connection to satellites with the best signal conditions, leading to traffic bottlenecks an‎d increased blocking rates. Traditional han‎dover methods, which rely on local criteria (like signal strength), lose their effectiveness in this dynamic environment due to high propagation delays an‎d a lack of a comprehensive network view. To overcome these challenges, this research proposes an intelligent an‎d proactive framework for han‎dover management. The han‎dover problem is modeled as a Markov Decision Process (MDP), wherein the user, acting as an intelligent agent, learns an optimal policy for target satellite selec‎tion by interacting with the network environment an‎d leveraging a Deep Reinforcement Learning (DRL) algorithm. A key innovation of this research is the design of a multi-objective reward function. By penalizing unnecessary han‎dovers an‎d rewarding optimal selec‎tions, this function guides the agent to make decisions that simultaneously achieve three key objectives: minimizing the number of han‎dovers, balancing network traffic load, an‎d maintaining Quality of Service. Simulation results demonstrate that the proposed approach not only significantly reduces han‎dover frequency but also, through its ability to predict signal degradation an‎d make proactive decisions, considerably curbs the connection blocking rate. This effectively ensures the stability an‎d efficiency of the entire system in next-generation networks.
  • كليدواژه هاي فارسي
    ﺷﺒﮑﻪ ﻫﺎي ﻣﺎﻫﻮاره اي ارﺗﻔﺎع ﭘﺎﯾﯿﻦ , ﺷﺒﮑﻪ ﻧﺴﻞ ﭘﻨﺠﻢ , واﮔﺬاري , ﯾﺎدﮔﯿﺮي ﺗﻘﻮﯾﺘﯽ
  • كليدواژه هاي لاتين
    Low Earth Orbit Satellite Networks , 5G Network , Handover , Reinforcement Learning
  • Author
    Fateme Raisi amjad
  • SuperVisor
    Dr.nasser mozayani - Dr.Ahmad Akbari Azirani