Training-Based Schemes Are Suboptimal for High Rate Asynchronous Communication
Synchronization and information transmission of virtually all practical communication systems are performed separately, on the basis of different communication bits. Moreover, in general, the rate of these strategies is computed with respect to the information transmission time period, ignoring the delay overhead caused by various hand-shake protocols used to guarantee synchronization. In these cases, the notions of 'High rate' or 'Capacity-achieving' communication strategies clearly raises questions. Building on an extension of Shannon's original point-to-point synchronous communication channel model to assess the overall rate performance of asynchronous communication systems, the authors showed that training-based schemes perform suboptimally at high rates. In this regime, it is necessary to envision communication strategies that integrate synchronization into information transmission.