Maximizing reliability in multi-hop wireless networks

Distributed space-time block coding is a diversity technique to mitigate the effects of fading in multi-hop wireless networks, where multiple relay stages are used by a source to communicate with its destination. This paper proposes a new distributed space-time block code called the cascaded orthogonal space-time block code (COSTBC) for the case where the source and destination are equipped with multiple antennas and each relay stage has one or more single antenna relays. Each relay stage is assumed to have receive channel state information (CSI) for all the channels from the source to itself, while the destination is assumed to have receive CSI for all the channels. To construct COSTBC, multiple orthogonal space-time block codes are used in cascade by the source and each relay stage. COSTBC is shown to achieve the maximum diversity gain in a multi-hop wireless network with flat Rayleigh fading channels. An explicit construction of COSTBCs is also provided. It is also shown that COSTBC requires minimum decoding complexity thanks to the connection to orthogonal space-time block codes.