leaky bucket

1
????? ????? ?? ??????leaky bucket
???? ??????? ??????? ????? ?? ?????? ?? ?????
???? ?? ???? ?-bucket ???? ???? ?????????
??????? ?????? ????.
???? ?"? ???? ???
?????? ???? ??? ????? ??????
2
?????? ????? ?????? ????? MPEG ??? ?????????
????. ????? ??? ???????? ??????? ??? ??????
?????? ?????? ????? ??????, ??????? ???? ????
?????? ????? ????.
MPEG - Compressed video stream
Frame number

• Fixed GoP pattern such as IBBPBBP IBBPBBP
• I frames are JPEG encoded
• B and P frames exploit temporal redundancy and
  hence much smaller

3
??? MPEG video traces ?????? ????? 200,000
??????. ?? ???? ???? ???? Frame ??????.
4
???? ?????? ????? ?????? ????? EPCRTT
?????? ????? ?? ??? ????? ????? ????, ???? ????
???????? ?????.
5
???? ?????? ????? ?????? ????? leaky bucket
policing .?? ????? ?? ?????? ???? ?????? ??
??????.
r2
Token arrival Bits/sec
r 1
s2
Bucket size bytes
s1
Mpeg source
Network
6
????? ?????? LB ?? ??? ????? ???????
7
???? ???? ?????? ?????? ????? ????????? ?
?????? empirical envelop
8
???????? ?- sampled E. ??????? ?????? ???? ?-E
?????? ?????? ?? ??????? ????? ?? ????????. ????
????? ?? ?????? ???????? ??????.
9
?????? ???? ????? Sampled E ????? E ????
????????? ???? M ???? ??????? ???? K
???? ????????? N M/K ????? E ????
????????? ????? ?????? L.B. ? E ???? ??? ??????
?????? L.B. ? E ????
10
Mpeg trace
Smoothing EPCRTT
Computing the empirical envelope (expensive)
Computing the sampled empirical envelope (fast)
Finding the concave hall Best LB policer
Select the best LB pair by minimizing a cost
Function
11
INTERNET PROVIDER
CLIENT
MPEG-SERVER
Request movie client buffer size
Smoothing the requested movie using the E-pcrtt
algorithm with the maximal interval (according to
the buffer size)
Characterize the smoothed movie with the
sampled-E algorithm and find a set of (s,r) LB
pairs.
Cost function
Choose the best pair (s,r) in order to minimize
the cost.
12
INTERNET PROVIDER
CLIENT
MPEG-SERVER
Request allocation of (s,r)
O.K / No resources
Price proposal
O.K / Drop request
Set connection and Send the requested movie
13
Smooth vs. original
14
Smooth vs. original
15
Smooth vs. original
16
Smooth vs. original
17
Smooth vs. original
18
Smooth vs. original
19
??????
????? ?????? ??? ?????? ????? ?-LB ??????. ?????
???? ????? ?? ????? ????? CBR.
?????? ??????? ????? ?????? ??? ????? ??????
????? ????? ????, ???? ?????? ?? ?????? ????.
??? ???? ?? ?????? ????? ?? ?????? ?????? ????
??????????.