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sporadic high bit-error rate, high latencies

temporary disconnection due to handoff

Breaks the TCP connection between FH and MH into two connections at MSR

Connection between FH and MSR is regular TCP

Connection between MSR and MH is any transport layer protocol tuned for wireless links.

BS cache packets from FH and send back ACK for MH.

if MH switches to another cell the center point of the connection moves to the new MSR, no need of reconnection.

FH is completely unaware of the indirection and is not affected even when the MH switches cells.

Modify the IP layer in the BS, and let BS cache the TCP packets sent from FH before route it to the MH.

If packet lost on wireless link, IP layer on the BS will retransmit the packet .

BS suppress DUPACKs sent from MH to FH.

BS use shorter local timer for local timeout.

A new packet in the normal TCP sequence. (common case)

An out-of-sequence packet that has been cached earlier. (sender retransmission)

An out-of-sequence packet that has not been cached earlier. (congestion loss)

ACC and AF are schemes to reduce the frequency of acks on the reverse channel.

SA and AR are schemes to overcome the adverse effects of reduced ack feedback.

In experiments, we use ACC conjunction with SA, and AF in conjunction with SA or AR.

Acks-first scheduling scheme is designed to prevent the forward transfer from being starved by data packets of the reverse transfer

Official Notes

Notes from other sources

Wireless TCP.ppt

Model question papers

Previous year question papers

Useful links