Information Technology Reference
In-Depth Information
By using
n
∑
1
0
P
x
=
,
x
=
the steady-state probability
P
i
can then be obtained. Equation 1.2 shows the
calculation result of
P
0
where ρ = λ/μ. Since each element of
P
i
is directly
related to
P
0
this can be used to derive
P
i
. For more detail of the calculation,
please refer to Wu, Lee, Gau, and Hwang [58].
1
1
−
−
ρ
ρ
,
if
ρ
≠
1
n
P
=
.
(1.2)
0
1
,
if
ρ
=
1
1
+
n
1.5.2 Overcoming Burst Packet Loss by a Multisource Peer-to-
Peer System with Forward error Correction Scheme
To overcome burst packet loss caused by parent departure, a multisource P2P
live streaming system with a packet-level FEC scheme is proposed in Wu, Lee,
Gau, and Hwang [58], as shown in Figure 1.34, where each parent is responsible
for forwarding only partial streaming content, to reduce the impact of parent
departure. Packet level FEC is a receiver-driven error correction scheme that
overcomes the packet loss problem by adding a certain number of redundant
packets that can be used to reconstruct the originally transmitted data packets
after packet losses. For a packet level FEC scheme [60-64], FEC(
n, k
), when
n
packets are transmitted, the receiver can fully recover all
k
i n for mat ion packets
if
n - k
or fewer packets are lost during transmission. In a multisource system
with packet level FEC, as long as the remaining parents can provide sufficient
packets, the lost packets can thus be recovered by FEC. In the example shown
in Figure 1.34, an eight-source multicast structure with packet level FEC(8,5) is
used. For every five data packets, three redundant FEC packets are added. For
S
1
S
2
S
3
S
4
S
5
S
6
S
7
S
8
D
1
D
2
D
3
D
4
D
5
FEC
1
FEC
2
FEC
3
Figure 1.34
An example of eight sources structure with an FEC(8,5) scheme.
