On embedded diversity codes
Diversity-embedded codes for fading channels are high-rate codes that are de-signed so that they have a high-diversity code embedded within them [3, 4]. This is equivalent to coding the data into two streams such that the high-priority stream has higher reliability (designed in terms of diversity order) than the low-priority stream. These codes also allow a form of opportunistic communication where the high-rate code opportunistically takes advantage of good channel realizations whereas the embedded high-diversity code ensures that at least part of the infor-mation is received reliably. In this paper we give the design for a class of such codes for a fixed transmit alphabet constraint. These constructions are a natural generalization of multilevel codes to diversity embedding. These codes give prov-able performance guarantees by using binary matrices with rank guarantees as the building blocks to generate the desired diversity embedding in the complex do-main. We also investigate the systems implications of these codes by examining its applications to unequal error protection, rate opportunism and packet delay optimization. Preliminary results in these applications demonstrate that diversity-embedded codes can outperform traditional single-layer codes in moderate SNR regimes.
