Patent ID: 7990939
Filing Date: 2011-08-02
Classification: H04L,H04W

Abstract:
1. An information transmitting method for transmitting information through a plurality of base stations from a master station to a plurality of slave stations which communicate with the base stations, including: determining, on the basis of a packet error rate from the master station to the slave stations, a number of times of multicast transmission such that an expected value of a number of slave stations that transmit a retransmission request is equal to or smaller than a predetermined ratio, or an expected value of a number of retransmitted packets responding to the retransmission request is equal to or smaller than a predetermined ratio, or a probability that the slave stations receive all packets forming information is equal to or larger than a probability set in advance; notifying the determined number of times of multicast transmission to the slave stations; transmitting, to plural slave stations in multicast, same information formed of plural packets the determined number of times of multicast transmission; connecting unicast connection to a slave station that identifies a lacking packet after receiving information the notified number of times of multicast transmission; receiving, from the slave station that receives information in multicast, a retransmission request including an identifier of the lacking packet among packets forming the information, by the unicast connection; and retransmitting a packet corresponding to the identifier of the packet to the slave station by the unicast connection, wherein the base stations have plural areas in which a radio wave is reached, in the determining, the numbers of times of multicast transmission are determined for each of the plural areas of base stations communicating with the slave stations, and in the transmitting to the plural slave stations, the same information is transmitted in multicast to the slave stations in the respective areas, the determined number of times of multicast transmission in the respective areas.