Vehicle Density Based Forwarding Protocol for Safety Message Broadcast in VANET

Pseudocode 1

Pseudocode of VDF.

Parameters:

 {

  𝑅: The transmission range;

  CW_max: The maximum contention window;

  CW_min: The minimum contention window;

  𝑛𝑒𝑖𝑔ℎ𝑏𝑜𝑢𝑟_𝑙𝑖𝑠𝑡: The vehicle set in the transmission range;

  𝑛_𝑣: The vehicle number in 𝑛𝑒𝑖𝑔ℎ𝑏𝑜𝑢𝑟_𝑙𝑖𝑠𝑡;

  𝐹: The forwarder vehicle;

  𝑑_𝑓: The distance from 𝐹 to the current vehicle;

 }

Initialization:

 {

  𝑛_𝑣=0;

  𝐹=Ø;

  𝑑_𝑓=0;

  𝑛𝑒𝑖𝑔ℎ𝑏𝑜𝑢𝑟_𝑙𝑖𝑠𝑡 = Ø;

 }

On receiving a beacon from vehicle  𝑣:

 {

 if  𝑣 is not  in 𝑛𝑒𝑖𝑔ℎ𝑏𝑜𝑢𝑟_𝑙𝑖𝑠𝑡  then

  {

   𝑛_𝑣=𝑛_𝑣+1;

   add 𝑛_𝑣 into 𝑛𝑒𝑖𝑔ℎ𝑏𝑜𝑢𝑟_𝑙𝑖𝑠𝑡;

   update the vehicle density 𝛼;

   }

 if  𝑣 is the forwarder 𝐹  then

     update 𝑑_𝑓 as the distance from 𝐹 to the current vehicle;

   }

On receiving a message from the forwarder  𝐹:

 {

 if  𝑡ℎ𝑒𝑚𝑒𝑠𝑠𝑎𝑔𝑒𝑖𝑠𝑛𝑒𝑤  then

  {

   calculate CW with (11);

   start the waiting timer;

    }

 else

  stop the waiting timer;

   }

On the waiting time expire:

 {

  broadcast the received message;

  the current vehicle becomes the forwarder 𝐹;

   }