Space-time network coding with optimal node selection for amplify-and-forward cooperative networks

In a wireless network with multiple amplify-and-forward (AF) nodes, the many-to-many cooperative communication is achieved through the novel concept of space-time network coding with optimal node selection (STNC-ONS). The communication under the STNC-ONS scheme is split into two phases: 1) the broadcasting phase (BP) in which each node in its allocated time-slot broadcasts its data symbol to all the other nodes in the network, and 2) the cooperation phase (CP) in which the optimal node corresponding to each desired data symbol is selected for relaying it to the destination node in its own time-slot. The optimal node selection is based on the maximum harmonic mean value of the source, intermediate, and destination nodes´ scaled instantaneous channel gains. An approximate symbol-error-rate (SER) expression for M-ary phase shift keying (M-PSK) modulation is derived along with an upper bound SER approximation which is shown to be asymptotic at high signal-to-noise ratio. The derived analytical expressions verify that for a network of N nodes, a full diversity order of (N - 1) per node is achieved by the STNC-ONS scheme. It is concluded that the STNC-ONC scheme is a potential many-to-many cooperative communication scheme with applications spanning sensor and mobile wireless networks.