spistats.collision package

Module contents

This module defines an interface to the probability law of the number of collisions per packet sent in a sequential pseudonyms scheme.

class spistats.collision.Collision(nbr_dev, nbr_adr, adr_per_dev)

Bases: object

Probabaility law of the number of collisions in function of various network parameters.

__init__(nbr_dev, nbr_adr, adr_per_dev)

Parameters:

• nbr_dev (int) – Number of devices in the network.

• nbr_adr (int) – Number of addresses to chose from. For instance an 8 bit scheme has 2**8 addresses.

• adr_per_dev (int) – Number of pseudonymes maintained by each device.

cdf(n)

Cumulativ distribution function of the number of collision evaluated at n. In other words: P(number of collision <= n):

Parameters:

n (int) – Number of collisions.

Returns:

P(number of collision <= n)

Return type:

float in [0,1]

cdfinv(p)

Inverse function of the cdf. This function return n such that P(number of collision <= n) = p

Parameters:

p (float in [0,1]) – Probability that the number of collisions is lesser or equal than n.

Returns:

n such that P(number of collision <= n) = p.

Return type:

int

mass(n)

Mass function of the number of collisions for each packet sent evaluated at n. In other words: P(number of collision = n).

Parameters:

n (int) – Number of collisions.

Returns:

P(number of collision = n)

Return type:

float in [0,1]

mean()

Expectation of the number of collisions for each packet sent.

Returns:

E(number of collisions)

Return type:

int