The impact of channel estimation errors in wireless sensor networks over cooperative modulation diversity

Channel estimation errors can impact the performance of a cooperative wireless sensor network. In this paper the authors evaluate that impact, related to the packet loss rate and network lifetime. The LMS algorithm and a first order PLL are used to estimate the modulus and phase information, respectively. The network assumes a heterogeneous architecture, with the cooperation of cluster-heads and vice cluster-heads, if transmission errors occur. The cooperative scheme is formed by the rotation of a QPSK constellation and the independently interleaving of the in-phase and quadrature symbol components. The simulation results show that, even in the presence of channel estimation errors, the cooperative scheme overcomes the performance of the simple QPSK, regarding the packet loss rate. However, the network lifetime is longer for the QPSK scheme and for the cooperative modulation diversity with perfect channel estimation.