  A recent density functional theory (DFT) based analysis, complemented with
Quantum Monte Carlo calculations revealed a highly spin-frustrating nature of
the one-dimensional spin-$\frac{1}{2}$ compound $Cs_2CuAl_4O_8$ that comprises
of unique bond alternations and relatively strong next nearest neighbor
interactions. This article gives a brief account on possible magnon excitations
that can appear in the ground state of such systems. We find that the spin
waves obtained on top of coplanar helical reference states show multiple magnon
modes (both acoustic and optical). However, those magnon modes turn out to be
stable only in the absence of bond alternations.
