Hierarchical modulation based cooperative relaying over a multi-cell OFDMA network
The relay-assisted cooperative technique is a promising solution for guaranteeing quality of service and improvement in channel capacity. This paper proposes a hierarchical modulation based cooperative relaying method via a fixed relay station (FRS) to improve the performance of cell edge users for orthogonal frequency division multiple access (OFDMA) systems over a multi-cell environment. The grafting of both FRS and hierarchical modulation onto an OFDMA based cooperative system provides opportunities to reduce the interferences, i.e. inter-cell and inter-relay interferences, and to achieve cooperative diversity in a multi-cell environment, simultaneously. Under conditions of severe inter cell interference caused by high carrier collisions, the proposed scheme leads to an improvement in both channel capacity and bit error rate for cell boundary users.
inter-relay interference cooperative diversity interference cancellation inter-cell interference collision probability