This paper is motivated by the modifications recently suggested to enhance
TCP performance over wireless channels. We argue that TCP end-to-end error-
control mechanism lacks the functionality to respond appropriately in situa
tions where errors vary in nature, frequency, or duration. As a result, thi
s mechanism could, under some circumstances, yield zero throughput achievem
ents at high energy-cost, or degrade throughput performance without conserv
ing energy. This incompetent behavior with respect to the energy/throughput
tradeoff puts in question TCP's suitability as a universal, reliable trans
port protocol of choice, especially for battery-powered mobile devices for
which energy is a critical resource and congestion is not the exclusive cau
se of errors.
We propose "Wave" and "Probing" communication and control mechanisms that p
ermit end-to-end protocols to detect congestion without necessarily experie
ncing packet drops, to distinguish random and burst errors from congestion,
and, as conditions vary, to rapidly adjust the transmission window upwards
or downwards depending on the nature of the error. We report extensively o
n the performance of these new mechanisms to demonstrate their energy-conse
rving and high-throughput capabilities.