Anti error propagation methods for wireless uplink using network coding

Abstract

Abstract-Wireless network coding suffers the error propagation issues that may severely degrade the diversity performance. In this work, we develop two power scaling schemes at the relay side and two detection schemes at the receiver side, respectively, to mitigate error propagation in network-coded uplink channel and thus achieve full diversity. For the soft power scaling based link adaptive relaying, we develop a virtual channel model and demonstrate that the relay power should be such to balance the signal-to-noise ratios of the source-relay channel and relaydestination channel. As for the hard power scaling based ON-OFF relaying, we first design a decision rule based on total pairwise error probability, and then simplifies it to the thresholdbased relaying strategy. At the receiver side, we show that the weighted minimum distance detection with the weight being determined by the relative link quality of source-relay channel and relay-destination channel can achieve full diversity once the global channel state information is available, otherwise the maximum likelihood detection that explicitly takes into account relay decoding error should be employed to achieve full diversity.

On analysis of wireless uplink using analog network coding with non-coherent modulations

“…The resulting throughput can be greatly enhanced at a cost of more complicated receiver design and increased signaling overhead. For example, special detection schemes have to be leveraged to address the error propagation issue associated with digital network coding [5] [6], and multiuser interferences have to be suppressed if analog network coding (ANC) is used instead [7] [8]. For both strategies, knowing global channel state information (CSI) is necessary for coherent detection, thus the channel estimation overhead increases linearly with the product of the number of users and the number of relays.…”