Performance Analysis for Bit Error Rate of DS- CDMA SensorNe(4)

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= +∑

( ) ISSN: 1693-6930 ( , , ) (10)

(t) If m0= 1, the output of the integrator can be explained to

= + /2 (11)

Let δ= Tb, we have

( )( ) = . ≥ + < (12) .

2 As SNRME approach constant, ∑MK=2(ɑK pk/2) σi(k)→∞ as M→∞ and P0(t)>>P1(t) under these condition, under these condition we can simplify Pb as:

Pb = (1- ɑ1) Q( ME) (13)

where Q(x)=

3. Results and Analysis

Figure 1 illustrates variation of the SNR to the number of users (receivers). The SNR increases for different values of the percentage of high bits for ( ) during the transmission duration of T second ( ) when the number of users increases the interference with the users are increased. Thus such behavior leads to increase amount of the MAI power and the SNR decreases.

∞ 2/21 du. Figure 1. SNR for DS-CDMA energy efficient to the number of users and different values of .

Figure 2 shows that when the is increased, the SNR increases linearly at certain values, following that, the SNR become autonomous of . This can be illustrated as follows, for minimum amount of the noise power caused by multiple receivers is trivial. Then, for lower values of , SNR is associated with , so the noise power get marginal.

Figure 3 explains variation of the probability of bit error rate

to number of users. It is increasing as number of user (M) increases for different levels of ɑ1. The probability reaches to the same value in specific number of users, which leads to the save power in more than specific number of users.

TELKOMNIKA Vol. 10, No. 1, March 2012 : 165 – 170