A communication system comprising: remote units (26a-26i, 128a-128l), each of the remote units (26a-26i, 128a-1281) comprising one or more radio frequency, RF, units to exchange RF signals with mobile devices, at least some of the RF signals comprising information destined for, or originating from, a mobile device; and a controller (22, 24, 124) separated from the remote units (26a-26i, 128a-1281) by one or more networks, the controller (22, 24, 124) being connected to an external network, the controller (22, 24, 124) for implementing a scheduler, the scheduler for allocating resources for transmission of data representing the information, and the scheduler being configured to override a pending hybrid automatic repeat request, HARQ, transmission sent by the mobile device on a HARQ process by scheduling a new HARQ transmission on the HARQ process; and wherein the controller (22, 24, 124) is configured to accelerate retransmission of data in the overridden HARQ transmission sent by the mobile device by performing operations comprising: detecting, at a media access control instance of the controller (22, 24, 124), an unrecoverable error for the overridden HARQ transmission sent by the mobile device; sending cross-layer indications to a radio link control instance in the controller (22, 24, 124) to place a timer in an expired state, resulting in transmission of a status message to the mobile device, the status message indicating an error in the data; and receiving, from the mobile device, a retransmission of the data in response to the status message. remote units (26a-26i, 128a-128l), each of the remote units (26a-26i, 128a-1281) comprising one or more radio frequency, RF, units to exchange RF signals with mobile devices, at least some of the RF signals comprising information destined for, or originating from, a mobile device; and a controller (22, 24, 124) separated from the remote units (26a-26i, 128a-1281) by one or more networks, the controller (22, 24, 124) being connected to an external network, the controller (22, 24, 124) for implementing a scheduler, the scheduler for allocating resources for transmission of data representing the information, and the scheduler being configured to override a pending hybrid automatic repeat request, HARQ, transmission sent by the mobile device on a HARQ process by scheduling a new HARQ transmission on the HARQ process; and wherein the controller (22, 24, 124) is configured to accelerate retransmission of data in the overridden HARQ transmission sent by the mobile device by performing operations comprising: detecting, at a media access control instance of the controller (22, 24, 124), an unrecoverable error for the overridden HARQ transmission sent by the mobile device; sending cross-layer indications to a radio link control instance in the controller (22, 24, 124) to place a timer in an expired state, resulting in transmission of a status message to the mobile device, the status message indicating an error in the data; and receiving, from the mobile device, a retransmission of the data in response to the status message. detecting, at a media access control instance of the controller (22, 24, 124), an unrecoverable error for the overridden HARQ transmission sent by the mobile device; sending cross-layer indications to a radio link control instance in the controller (22, 24, 124) to place a timer in an expired state, resulting in transmission of a status message to the mobile device, the status message indicating an error in the data; and receiving, from the mobile device, a retransmission of the data in response to the status message.