LPPS: A Distributed Cache Pushing Based K-Anonymity Location Privacy Preserving Scheme

Algorithm 1

Cache pushing strategy for each cache proxy .

Input:

   Pushing round number, ;

    -anonymity, ;

   Cache proxies Caches, ;

   All cache data in , ;

   For , each item is in the format ;

   For , each group generates an index in the form ;

   Received feedback index for , ;

   Received feedback content for , ;

Output:

   None

 (1)  while True do

 (2)    broadcasts following to users passing-by round with each round items:

      with cache group index.

 (3)   if receives the grouped cache items index then

 (4)     broadcasts the th group of .

 (5)   end if

 (6)    if receives feedback index from user then

 (7)    

 (8)    if needs to update its cache then

 (9)       requests feedback content about feedback index from LBS server.

 (10)        

 (11)     if reaches the limit of cache size then

 (12)      LRU (Least Recently Used) policy will be used replace

 (13)     end if

 (14)     end if

 (15)    end if

 (16) end while

 (17) return;