In order to realize the multi-hop DSTBC based CMISO transmission, [N.sub.D] RNs ([R.sub.D](1),...,[R.sub.D](i),...,[R.sub.D]([Nd)) are deployed between the S and the D, [N.sub.d]+1 CNs ([C.sub.D](1),...,[C.sub.D](i),...,[C.sub.D([N.sub.D]+1)) are deployed the each hop.
Similar to multi-hop CB based CMISO transmission, the multi-hop DSTBC based CMISO transmission scheme in each hop is also consists of BTP and CTP.
3.2 Nodes deployment optimization for Multi-hop DSTBC based CMISO Transmission
For DSTBC based CMISO transmission, the optimal [N.sub.D] is 2, the global minimum energy consumption is 2.4769x[10.sup.-2]J and the corresponding optimal nodes deployment ([N.sub.D,opt], [D.sub.D,opt](i) (i=1,2,..., [N.sub.D,opt]+1), [beta.sub.D,opt](i) (i=1, 2,..., [N.sub.D,opt]+1), [d.sub.D,opt](i) (i=1,2,..., [N.sub.D,opt]+1)), [[alpha].sub.D,opt](i) (i=1,2,..., [N.sub.D,opt] +1) are 2,33.33m, 0[degrees],9.03m, 0[degrees], respectively.
8 show the optimal nodes deployment for SISO, DSTBC based CMISO and CB based CMISO transmissions, respectively.
In contrast to hard decision MSD in DSTBC UWB systems , the proposed MSD provides more reliable detection due to using soft information.
Inspired by the forward and backward message passing, the proposed SISO MSD facilitates the bidirectional message passing implementation by means of DSTBC trellis.
A mathematical model for MSD metric is analyzed for the proposed SISO MSD in DSTBC UWB systems.
System description of a DSTBC UWB system is introduced in Section 2.
We consider a DSTBC system, which is equipped with Q (Q [greater than or equal to] 1) receive antennas.