Physical-layer Differential Network Coding In Twrc

The network coding method is a new kind of technogy that increases the network throughput, which could allow the intermediate nodes in the multicast network to process the received the information and retransmit it. At the same time, the link nodes translate the information of the source through some signal processing methods, and the whole network can improve the receiving rate of the nodes via extra signal processing.But, most studies on the network coding are based on the receivers could estimate the current channel situation accurately. Compared to the channels with slow changing rate, this is reasonable. However, in order to decrease the cost and complexity in some situations, or the channel attenuation coefficient changes very fast, we cannot do any estimation of the channels at all. This needs us to resort to a new method without knowing the channels situation-differential coding technology.This paper mainly proposes PCNC (physical cooperative network coding) and DPCNC (differential physical cooperative network coding) using cooperative and differential modulation technology in the TWRC (Two-Way wireless relay channels). Using the Linearity of the cooperative network coding, it makes the relay signals reflect the differential relations between the succeeding two time slots. Thus, we could use the non-correlated method, and use the mapping and achieve the signals denoising as well as enlarge the Euclidean distance. Hence, we enhance the quality of the mixing signals. Therefore, PCNC has more advantages than the traditional physical layer hybrid coding.At the same time, a general method named linear differential detection method is also proposed for the PCNC and DPCNC model mentioned in this article as well as the usual differential modulation used at the relay. It simplifies the detection processing at the receivers and has its common usage.