Patent ID: 11961409
Assignee: NANJING UNIVERSITY OF AERONAUTICS AND ASTRONAUTICS
Field: Control (Instruments)
Classification: CPC G  Y | IPC G

Claim 3:
4. An air-ground joint trajectory planning and offloading scheduling system for distributed multiple objectives, wherein all devices of the system comprise a UAV fixed at a flight altitude, a terrestrial BS at a fixed location, and a plurality of terrestrial users at fixed locations, and the UAV and the BS jointly serve the plurality of terrestrial users;
the UAV is configured to perform following operations: obtaining current state information, wherein the state information comprises a location of the UAV in a current timeslot t and a total amount of unprocessed data of all the devices in a previous timeslot t−1; selecting an action by minimizing a total energy consumption of all the devices and a total amount of unprocessed data of all the devices, selecting a flight direction from a preset flight direction set, and flying a fixed distance; after task offloading scheduling of the users is completed in the current timeslot t, updating the location as a location in a next timeslot t+1; and receiving a feedback for a current action, and obtaining an optimal flying strategy based on the state information and the feedback for the current action in the next timeslot;
wherein the total energy consumption of all the devices is calculated according to a following formula:, D
   t
  
  =
  
   
    
     ∑
     
      m
      =
      1
     
     
      m
      =
      M
     
    
    
     (
     
      D
      
       m
       ,
       t
      
     
     )
    
   
   +
   
    D
    
     UAV
     ,
     t
    
   
   +
   
    D
    
     
      B
      ⁢
      S
     
     ,
     t
    
   
  
 

wherein Dt represents a total energy consumption of all the devices in the timeslot t, M represents a quantity of users, m∈{1, 2, . . . , M}, and Dm,t, DUAV,t, and DBS,t respectively represent cumulative computing tasks in queues of a user m, the UAV, and the BS in the timeslot t; and
the total amount of the unprocessed data of all the devices is calculated according to a following formula:, E
   t
  
  =
  
   
    ∑
    
     m
     =
     1
    
    M
   
   
    (
    
     
      
       (
       
        
         E
         
          UAV
          ,
          m
          ,
          t
         
         trans
        
        +
        
         E
         
          UAV
          ,
          m
          ,
          t
         
         cp
        
       
       )
      
      ·
      
       α
       
        m
        ,
        t
        ,
        UAV
       
      
     
     +
     
      
       (
       
        
         E
         
          BS
          ,
          m
          ,
          t
         
         trans
        
        +
        
         E
         
          BS
          ,
          m
          ,
          t
         
         cp
        
       
       )
      
      ·
      
       α
       
        m
        ,
        t
        ,
        BS
       
      
     
     +
     
      
       E
       
        UE
        ,
        m
        ,
        t
       
       cp
      
      ·
      
       α
       
        m
        ,
        t
        ,
        UE
       
      
     
    
    )
   
  
 

wherein Et represents a total amount of unprocessed data of all the devices in the timeslot t, EUAV,m,ttrans and EBS,m,ttrans UAV respectively represent transmission energy consumptions of offloading a task by the user m to the UAV and the BS in the timeslot t, EUAV,m,tcp and EBS,m,tcp respectively represent energy consumptions of computing the task by the user m on the UAV and the BS in the timeslot t, and αm,t,UE, αm,t,UAV, and αm,t,BS respectively represent operations of performing local computing, offloading to the UAV, and offloading to the BS by the user m in the timeslot t, wherein when the local computing is performed, αm,t,UE=1, otherwise αm,t,UE=0; when the offloading to the UAV is performed, αm,t,UAV=1, otherwise αm,t,UAV=0; and when the offloading to the BS is performed, αm,t,BS=1, otherwise αm,t,BS=0;
wherein the feedback for the current action is as follows:, r
    _
   
   =
   
    
     [
     
      
       E
       ¯
      
      ,
      
       D
       ¯
      
     
     ]
    
    T
   
  
  ⁢
  

  
   
    E
    ¯
   
   =
   
    
     lim
     
      T
      →
      ∞
     
    
    
     sup
     ⁢
     
      1
      T
     
     ⁢
     ε
     ⁢
     
      {
      
       
        ∑
        
         t
         =
         0
        
        
         T
         -
         1
        
       
       
        e
        t
       
      
      }
     
    
   
  
  ⁢
  

  
   
    D
    ¯
   
   =
   
    
     lim
     
      T
      →
      ∞
     
    
    
     sup
     ⁢
     
      1
      T
     
     ⁢
     ε
     ⁢
     
      {
      
       
        ∑
        
         t
         =
         0
        
        
         T
         -
         1
        
       
       
        d
        t
       
      
      }
     
    
   
  
 

wherein r represents a column vector of the feedback, [ ]T represents transposition, Ē represents an average feedback for an energy consumption, D represents an average feedback for unprocessed data, T represents duration of the task,, sup
  ⁢
  
   1
   T, represents an upper bound of, 1
   T
  
  ,, , ε{ } represents averaging, et=−Et, and dt=−Dt; and
the user is configured to perform following operations: before the UAV reaches a new location, obtaining, by each user, current state information; selecting, by all the users, an action in parallel, determining a task offloading scheduling method of each user from a preset offloading strategy set by minimizing the total energy consumption of all the devices and the total amount of the unprocessed data of all the devices, and executing the task offloading scheduling method in the current timeslot t; and receiving the feedback for the current action, and obtaining an optimal offloading strategy based on the state information and the feedback for the current action in the next timeslot.