Patent 6842445 was granted and assigned to Nokia on January, 2005 by the United States Patent and Trademark Office.
An automatic repeat request mechanism (such as Type II/III hybrid ARQ) which includes (soft or hard) combining of initially transmitted and retransmitted versions of a packet, is provided for retransmission of erroneous packets. According to the present invention, in association with each retransmission, there is outband signaling from a transmitter to a receiver that unambiguously indicates when, e.g. the exact time or physical location, the first transmission of the packet was carried out, so that it is possible to combine the retransmitted version with the previous version(s) of the packet. Soft combining requires that the initial packet and the retransmitted packet be identical. In an embodiment of the invention, in order to overcome this problem, the information that needs to be changed between the initial transmission and the retransmission(s) of a packet is sent outband with other outband signaling information. Thus, the retransmitted packet can be maintained unchanged and the requirement for identical packets in soft combining is met.