09-04-2011, 10:22 AM
[attachment=11900]
ARQ Protocols
Automatic Repeat Request (ARQ)
Stop-and-Wait ARQ
S&W ARQ - Sequence Numbers
S&W ARQ - Sequence Numbers in ACK
1-Bit Sequence Numbering suffices for Stop-and-Wait ARQ
Stop-and-Wait ARQ
Applications of Stop-and-Wait ARQ
Stop-and-Wait Efficiency
Stop-and-Wait Model
Stop & Wait Efficiency on Error-free channel
Example: Impact of Delay-Bandwidth Product on Transmission Efficiency
Stop and Wait Efficiency in Channel with Errors
Example: Impact of Bit Error Rate on Transmission Efficiency
Go-Back-N (GBN)
Go-Back-N ARQ
S&W timeout and GBN window size long enough to cover round trip time
Go-Back-N with Timeout
Go-Back-N Transmitter & Receiver
Sliding Window Operation
Maximum Allowable Window Size is Ws = 2m-1
ACK Piggybacking in Bidirectional GBN
Required Timeout & Window Size for Bidirectional GBN
Applications of Go-Back-N ARQ
Required Window Size for Delay-Bandwidth
Efficiency of Go-Back-N
Example: Impact of Bit Error Rate on GBN
Selective Repeat ARQ
Selective Repeat ARQ
Selective Repeat ARQ
Send & Receive Windows
What size Ws and Wr allowed?
Ws + Wr = 2m is maximum allowed
Why Ws + Wr = 2m works
Applications of Selective Repeat ARQ
Efficiency of Selective Repeat
Example: Impact of Bit Error Rate on Selective Repeat
Comparison of ARQ Efficiencies
ARQ Efficiencies
