Chip-Level HARQ Chase Combining for HSUPA

摘要

Hybrid automatic repeat request (HARQ) is used in high-speed uplink packet access (HSUPA) to increasethe data rate. Chase combining is the simplest of HARQ algorithms. It provides a time diversity and requires a small memory. In this paper, we propose a technique to increase the chase combining efficiency. In thismethod, HARQ transmissions are seen as additional receive antennas which are jointly combined at chip-levelusing a space-time linear minimum square error (LMMSE). We demonstrate that the chase combining diversitygain is considerably increased especially for high-order modulation.