H-ARQ
Hybrid ARQ error-control mechanism is part of the mobile WiMAX specifications to improve link utilization and optimize packet-errors. All processing (transmit and receive) is handled by the PHY inside the system-on-chip (SoC). Using H-ARQ the receiver aggregates the energy from a faulty packet with the re-transmissions of the same packet to improve CINR until the entire burst can be decoded in its entirety. There is provision for multiple parallel H-ARQ channels for increased throughput. Mobile users and real-time applications benefit the most because the errors are corrected at the physical-layer itself, without requiring re-transmissions from upper layers.