The Global 21 cm Signal of a Network of Cosmic String Wakes
  In previous works we discussed the 21 cm signature of a single cosmic string
wake. However the 21 cm brightness temperature is influenced by a network of
cosmic string wakes, and not one single wake. In this work we consider the
signal from a network of wakes laid down during the matter era. We also improve
on the previous calculation of a single wake signature. Finally we calculate
the enhancement of the global 21 cm brightness temperature due to a network of
wakes and discuss its affects of the signal measured in the Wouthuysen-Field
absorption trough. We estimated that for string tensions between $10^{-8}$ to
$10^{-7}$ there would be between a 10% to a factor 2 enhancement in the signal.
