Patent ID: 7298730

Claim:
A method to prevent hyper frame number (HFN) unsynchronization for unacknowledged mode (UM) radio link control (RLC) between a transmitter and a receiver in high speed downlink packet access (HSDPA) of a high speed wireless communication system; wherein the transmitter assigns a Transmission Sequence Number (TSN) to each sending data package and temporarily keeps the sent data package until receiving a corresponding response from the receiver, meanwhile due to the change of the communication condition, the system switches to use different sizes of data package—media access control-high speed (MAC-hs) protocol data unit (PDU) for transmitting, the method comprising the steps of: at the transmitter: receiving a request to switch using a smaller size data package, a new MAC-hs PDU to be transmitted; until all unacknowledged MAC-hs PDUs have been processed, processing everyone of the unacknowledged MAC-hs PDUs affected by the size change request one at a time with the following steps a to f; a. extracting subsets from the contains of the unacknowledged MAC-hs PDU; b. filling up the new MAC-hs PDU with the extracted subsets; c. assigning the TSN of the unacknowledged MAC-hs PDU to the new MAC-hs PDU; d. indicating the new MAC-hs PDU containing new data; e. discarding the extracted unacknowledged MAC-hs PDU; and f. putting the new MAC-hs PDU ready to be transmitted.