A Novel Threshold Scheme for Reducing Spatial Intersymbol Interference in Vehicular Visible Light Communication Based on Image Sensors

Algorithm 1

Threshold calculation algorithm based on probability distribution.

Given blooming coefficient σ, the interval of neighbour LEDs d, LED transmission power P_i(t), communication distance U, 256 LEDs statuses matrices L and noise power N.

 Initialization transmission distance u.

 for u=1: U

  The optical power without interference is calculated by the formula (6);

  Using the formula (10) to calculate the spacing among LED_R,C to eight neighbour LEDs in the image sensor;

  According to the state matrix L, the sum I_SISI of eight surrounding LEDs is calculated using formula (8);

   ifLED_R,C is on,

    Received optical power is Y_ON=Y_o+ I_SISI +N;

    Y_o is calculated using formula (6);

    Calculate probability distribution of Y_ON;

   else

    Received optical power is Y_OFF= I_SISI +N;

    Calculate probability distribution of Y_OFF;

   end

   if the probability curves of Y_ON and Y_OFF distribution intersect,

   that is Y_ON,min≤Y_OFF,max

    for Th_u = Y_ON,min : Y_OFF,max

    The sum of the probabilities of status misjudgement is calculated, which is the BER;

    Find out Th_u with the minimum BER, and set this value as

    the judgment threshold;

    end

   else

    Set the threshold value Th_u equals to the mean value of the Y_ON,min and Y_OFF,max;

   end

 end