Path-permutation codes for end-to-end transmission in ad hoc cognitive radio networks

Cognitive radios (CRs) improve the spectrum efficiency in wireless communications. Nonetheless, owing to the intrinsic randomness of ad hoc cognitive radio networks (CRNs), e.g., the opportunistic links, the traditional realization of ad hoc networking that demands the end-to-end control information, is unscalable and impractical. A virtual multiple-input multiple-output (MIMO) framework has been recently developed for the realization of error-resilient end-to-end transmission without the necessity of feedback information. In this paper, we propose an end-to-end path-permutation coded (PPC) transmission in which one relay path is accessed at a time and the transmission is hopped among multiple relay paths. The hopping order is specified by a permutation array that encodes the data, meaning that the data is conveyed by the order of indices of the accessed paths. With the PPC scheme, the control overhead and data processing complexity of the end-to-end transmission become relatively low. The PPC technique can also be utilized as a multiuser technique. At the destination node, a joint sphere decoder efficiently implements the maximum a posteriori (MAP) probability decoding that simultaneously identifies the order of accessed paths and erasures. Comprehensive theoretical analyses and simulations are conducted to demonstrate the superior performance of the PPC technique in ad hoc CRNs.