Xidian Univ. 分组4的等效服务时间开始点 分组1的等效服务时间 分组2的等效服务时间 】 n+1 +3 传输的分组 出错 分组1的最出错 分组2的最后 正确出错 出错 后一次传输 一次传输 1.A given packet transmitted in frame i might be rejected at the receiver due to errors, in which case the transmitter will transmit packets in frames i+1,i+2,...,i+n-1, (if any are available),and then go back to retransmit the given packet in frame i+n. 2.A packet transmitted in frame i might be accepted at the receiver,but the correspond- ing acknowledgment (in the form of the receive number)might not have arrived at the transmitter by the time the transmission of packet i+n-1 is completed.This can happen due to errors in the return channel,large propagation delays,long return frames relative to the size of the goback number n,or a combination thereof. Broadband Wireless Communications Laboratory,Xidian University Xidian Univ. Broadband Wireless Communications Laboratory, Xidian University P-K公式