Title: Dynamic handoff scheme in differentiated QoS wireless multimedia networks
1Dynamic handoff scheme in differentiated QoS
wireless multimedia networks
- Source Computer Communications, Vol.27,
Issue.10, June 20, - 2004, pp.1001-1011
- Authors Wei, Yaya Lin, Chuang Ren, Fengyuan
Raad, Raad - Dutkiewicz, Eryk
- Speaker KunMing Tsai(???)
- Date 2009/12/24
2Outline
- Introduction
- Multi-GC (GC Guard Channel)
- DGC (Dynamic Guard Channel)
- Simulation
- Conclusions
- My comments
3Introduction
- Handoff is one of the key elements in ensuring
quality of service (QoS) in mobile wireless
network. - Handoff connections usually have higher priority
than new connections.
4Introduction
Handoff connections
New connections
Handoff connections usually have higher priority.
5Multi-GC1/3
- Guard Channel (GC)
- Each cell reserves a fixed number of channels
exclusively for handoff connections.
reserve some channels for handoff ex 5GC
if no available channels, handoff channel will
drop
6Multi-GC2/3
- Multi-GC
- extended from GC
- add different channel thresholds
- Two-bit Differentiated Services Architecture
(TDSA) incorporates three services premium,
assured, and best-effort services.
7Multi-GC3/3
channel pool
queue1
Cn
queue2
Ci
queue3
C1
. . .
queueN
each class of calls may have a different cutoff
threshold ? Ci
8Dynamic Guard Channel1/5
- There are four priorities
- P(M, H, P)
- P(M, N, P)
- P(M, H, A)
- P(M, N, A)
M stands for media type
H handoff connection N new connection
P premium service class A assured service class
P(M, N, A) lt P(M, H, A) lt P(M, N, P) lt P(M, H, P)
9Dynamic Guard Channel2/5
- Each service has a corresponding threshold
associated with it.
Thc(M, N, A)
Thc(M, H, A)
Thc(M, N, P)
Thc(M, N, P)
Traffic Priority P(M, N, A) lt P(M, H, A) lt
P(M, N, P) lt P(M, H, P)
- Each channel threshold Thc(i) is used to admit or
reject the coming connection of its type.
10Dynamic Guard Channel3/5
Pseudo-code
(M, H, A) connection is drop
blocking counter 4
51
54
60
51-1 50
54 (no change)
4
4
5
5
(M, N, A)
(M, H, A)
5 gt 5
5 lt 50
5
50
Tlb
Thb
Threshold for blocking counter of low priority
Threshold for blocking counter of high priority
11Dynamic Guard Channel4/5
- priority (i1)s blocking counter Bl(i1) may
cause Thc(i) to decrease when Bl(i1) exceeds
Tlb(i1) - priority i services blocking counter Bh(i) may
cause it to increase when Bh(i) exceeds Thb(i) - When the system is steady, the decreasing rate
and the increasing rate should be equal.
12Dynamic Guard Channel5/5
prove
- is weighting factor.
- In theory, both and can be set as
arbitrary numbers.
w1 0.1 P(M,N,A) / P(M,H,A) 1/w1
101 P(M,N,A) lt 1 P(M,H,A) lt 0.1
13Simulation1/6
DGC scheme admits more new connections to
improve system utilization when in light traffic.
try to decrease blocking probabilities of higer
priority service.
14Simulation2/6
DGC scheme has much lower assured service HBP
than in Multi-GC scheme
15Simulation3/6
16Simulation4/6
try to keep a balance between the different
metrics to guarantee the fairness
17Simulation5/6
18Simulation6/6
19Conclusions
- combines differentiated QoS service model and
priority handoff mechanism - provides fairness for differentiated QoS services
- adapts to various traffic loads
- easy to implement
- utilizes network resource efficiently
20My comments
- Test this method in NS-2.(This papers simulator
is SMPL) - Find a method resolve HBP and NBP.
- Using dynamic unit in decreasing threshold and
increasing threshold.back to example
21Pseudo-code of DGC scheme
Back
22Dynamic Guard Channel
Back
- Thc(i)s decreasing rate
- Thc(i)s increasing rate
- decreasing rate and increasing rate should be
equal.( )