Summary: TCP-DCR: A Novel Protocol
for Tolerating Wireless Channel Errors
Sumitha Bhandarkar, Student Member, IEEE Computer Society, Nauzad Erach Sadry,
A.L. Narasimha Reddy, Senior Member, IEEE Computer Society, and
Nitin H. Vaidya, Senior Member, IEEE Computer Society
Abstract--This paper presents TCP-DCR, a set of simple modifications to the TCP protocol to improve its robustness to channel
errors in wireless networks. TCP-DCR is based on the simple idea of allowing the link-level mechanism to recover the packets lost, due
to channel errors, thereby limiting the response of the transport protocol to mostly congestion losses. This is done by delaying the
triggering of congestion response algorithms for a small bounded period of time to allow the link-level retransmissions to recover the
loss due to channel errors. If at the end of the delay the packet is not recovered, then it is treated as a packet lost due to congestion.
We analyze TCP-DCR to show that the delay in congestion response does not impact the fairness towards the native implementations
of TCP that respond to congestion immediately after receiving three dupacks. We evaluate TCP-DCR through simulations to show that
it offers significantly better performance when channel errors contribute more towards packet losses in the network with no or minimal
impact on the performance when congestion is the primary cause for packet loss. We also present an analysis to show that protocol
evaluation in the wireless networks is significantly influenced by the number of flows in the network.
Index Terms--Wireless network, channel errors, TCP, delayed congestion response, local recovery.
THE popularity of wireless networking has increased
dramatically over the past few years. However, inte-