Transmission control method in a radio access network implementing an automatic repetition request (ARQ) protocol at the base station
A method of controlling the sending of data packets from a Base Station (BS) of a Radio Access Network (RAN) to a UE, where the BS is one of a set of BSs transmitting identical data to the UE and each said data packet has a sequence number. The method comprises implementing at the BS an Automatic Repetition reQuest (ARQ) mechanism for resending data packets erroneously received by the UE and, upon receipt of an ARQ status message from the UE, advancing a transmission window of the BS so that its lower region covers the packet having the highest sequence number for which an ARQ acknowledgement has nor yet been received. Where a single BS is transmitting in the downlink direction, and a soft handover set exists for an uplink reverse channel, downlink sending buffers of the BSs of the soft handover set may be synchronized by the exchange of ARQ messages between BSs.
1. A method of controlling the sending and resending of data packets forming a Link Layer Service Data Unit (LL SDU) from a User Equipment (UE) to a plurality of Base Stations (BSs) of a Radio Access Network(RAN), the UE implementing an Automatic Repetition reQuest (ARQ) mechanism for resending data packets erroneously received by the RAN, the method comprising receiving ARQ status messages at the UE from a plurality of BSs, identifying missing or erroneously received data packets, and retransmitting the identified data packets to all of the BSs, the BSs exchanging correctly received data packets to provide at least one of the BSs with the complete LL SDU.
2. A method according to claim 1 , wherein, once a BS has obtained a complete LL SDU, that BS informs other BSs of a soft handover link set by sending an ARQ status message.