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Motivation & Objectives1
Schemes under Studied2
Simulation Framework & Results3
Conclusion 4
Multimedia services is so common nowadays.
MAC protocols to provide different quality of services (QoS) for different classes of traffic are needed.
Different priorities of traffic can be effectively differentiated during reservation periods.
Reservation-based MAC protocols: FPT (Fix Probability Technique) and its extensions
Motivation & Objectives
1. FPT with Multiple Probability (FPT+MP)
2. FPT with Multiple Limited Token (FPT+MLT)
3. FPT with Partitioned Contention Period (FPT+PCP)
4. FPT with Shifted Contention Slots (FPT+SCS)
5. FPT with High-priority Finished First (FPT+HFF)
5 MAC Schemes under Studied
Frame Work and Assumptions 2 Classes of traffic (class-1 and class-2 users) Class-1 users has higher priority than that of class-2 users. M = the total number of active users N = the number of available contention slots M1,M2 = the number of users in the class, M1+M2 = M N1,N2 = the number of available slots for each class, N1+N2 = N p1, p2 = the permission probabilitiesT1 ,T2 = the number of tokens for class-1 and Class-2 users
...
p1
M1 Class-1
p2
M2 Class-2
A frame with N slots
Performance Metric
1 1 2 2/ / / .S M S M
2. The overall average number of successful reservations per frame in a reservation period is calculated as follows:
1. For the two-class traffic, we define to examine the controllable range for various mixtures of the two traffic classes as follows:
1 2 .TS S S
...
FPT (Fixed Probability Technique)
M
N slots
P
Single class user
FPT (Fixed Probability Technique)
Average number of successful reservations vs. number of
contention slots for FPT.
Average number of successful reservations vs. permission
probability of FPT.
FPT with Multiple Probability (FPT+MP)
...
P2
N slots
M2 Class-2
P1
M1 Class-1
M = 8, N = 16 P1 = 0.18
FPT+MP
= [1-2.5]
...
FPT with Multiple Limited Token (FPT+MLT)
T2=2
M2 Class-2
T1=3
M1 Class-1
N slots
P1 P2
N = 16, M = 8, P1=P2 = 0.18 T1 = 16
FPT+MLT
= [1-2.3]
FPT with Partitioned Contention Period (FPT+PCP)
M1 Class-1 M2 Class-2
N slots
P1 P2
N = 16, M = 8, P1=P2 = 0.18 N2 = 16-N1
FPT+PCP
= [1-18]
FPT with Shifted Contention Slots (FPT+SCS)
Ns = 3 N - Ns
M1
Class-1
M2 Class-2
N slots
P1 P2
N = 16, M = 8, P1=P2 = 0.18
FPT+SCS
= [1-18]
FPT with High-priority Finished First (FPT+HFF)
M1 Class-1 M2 Class-2
N slots
P1 P2
FPT+HFF N = 16, M = 8, P1=P2 = 0.18
is an exact value !!!
Performance comparison of all proposed schemes for different two traffic classes.
5 different channel reservation schemes for multi-class traffic have been evaluated.
Objectives: ◦ Maximizing the average no. of successful reservations◦ Large and fine-grained controllable range of
FPT+SCS+MP is found to be superior to all other schemes.
Strictly discriminated prioritization policy (FPT+HFF) lacks of flexibility in controlling .
Conclusion
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