Wireless Sensor Networks

1.3 Sensor Network Applications 9

power received at a distance r is

P

receive

∝

P

source

r

2

,

which assumes an inverse distance squared attenuation. The SNR is

given by

SNR

r

= 10 log

P

receive

P

noise

= 10 log P

source

− 10 log P

noise

− 20 log r.

Increasing the sensor density by a factor of k reduces the average

distance to a target by a factor of

1

√

k

. Thus, the SNR advantage of the

denser sensor network is

η

snr

= SNR

r

√

k

− SNR

r

= 20 log

r

r

√

k

= 10 log k. (1.2)

Therefore, an increase in sensor density by a factor of k improves the

SNR at a sensor by 10 log k db.

1.3 Sensor Network Applications

A sensor network is designed to perform a set of high-level infor-

mation processing ...