Algebraic space-time codes for quasi-synchronous cooperative diversity

Li and Xia have recently investigated the design of space-time codes that achieve full spatial diversity for quasi-synchronous cooperative communications. They show that certain of the binary space-time trellis codes derived from the Hammons-El Gamal stacking construction are delay tolerant and can be used in the multilevel code constructions by Lu and Kumar to produce delay tolerant space-time codes for PSK and QAM signaling. In this paper, we present various generalizations of the Lu-Kumar construction that also preserve the delay tolerance of the underlying constituent codes. We investigate the delay tolerance of short block codes derived from the stacking construction. We identify an algebraic constraint that, if satisfied, is sufficient to guarantee a certain level of delay tolerance and, based on this constraint, exhibit a new construction of short block codes that achieve significant levels of delay tolerance.