Enhanced On-demand WSN in terms of MC-CDMA with MPOMS

In this paper, the code division multiple access (CDMA) based on-demand wireless sensor network (WSN) is considered. The multicarrier-CDMA (MC-CDMA) with modified pseudo orthogonal M-sequences (MPOMS) has been proposed for CDMA based on-demand WSN. In our system, the lifeitem of sensor nodes can be extended because the sensor nodes effectively utilize the sleep/wake-up control function. Moreover, the cochannel interference between sensor nodes can be reduced by using MC-CDMA with MPOMS. However, the packet success rate (PSR) performance deteriorates by increasing node density. Because the number of nodes that sense the same target increases when node density becomes high, it is expected that packets having the same data also increase. In this paper, in order to improve PSR performance on the reverse link, a PSR enhancement method by combining packets from the sensor nodes that sense the same target is proposed. The proposed system can combine the packets by assigning same MPOMS to those nodes. Moreover, a PSR performance is evaluated by computer simulation. Consequently, it is found that PSR of the proposed system is better than that of the conventional system significantly. PSR of the proposed system can achieve 1 under an additive white Gaussian noise channel when the maximum number of activation nodes is 10, a packet length is 128[bit] and $E_{b}/N_{0} > 6[\mathbf{dB}]$.