A Hierarchical Model for Bandwidth
Management and Admission Control in
Integrated IEEE 802.16&802.11 Wireless
Networks
Dusit Niyato and Ekram Hossain
IEEE Wireless Communications and Networking Conference (WCNC), March 2007
報告者：李宗穎
Outline
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Introduction
System Model and Assumptions
Bandwidth Allocation
Admission Control
Performance Evaluation
Conclusion
2
Introduction
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This paper present a hierarchical bandwidth
management and admission control
framework for integrated IEEE
802.16/802.11 wireless networks
Related works considered connections only
from standalone subscriber stations
3
Network Model
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two-level hierarchical model
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first level a bargaining game between the set of
standalone SSs and the WLAN APs
second level, connections corresponding to the
different service types in the standalone SSs
4
IEEE 802.11/16
AP/wireless router
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Paper assume that the dual radio interface at
a 802.11/802.16 AP/wireless router uses
different frequency bands
Data packets corresponding to local and
Internet traffic are stored in separate queues
5
Uplink Transmission in the IEEE
802.16 Air Interface
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Paper consider a single BS with multiple
connections from SSs using the TDMA/TDD
access mode
Bi : burst size
Ri : transmission rate for any connection i in a frame
C : channel bandwidth
In : the number of transmitted bits per symbol for AMC state n
Prn : the probability of using AMC state n
F : frame size
6
Hierarchical Model for
Bandwidth Management
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Paper use sigmoid utility function which
represents quantitatively the satisfaction on
received transmission rate R
7
Bargaining Game (1/3)
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The average transmission rate for the
groups of standalone SS and WLAN
connections can be obtained from
γSS, γWL, NSS, NWL denote the average SNR
and the total number of standalone SSs and
WLAN APs/routers
8
Bargaining Game (2/3)
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The utilities for these groups of connections
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φSS(ΣBSS) = U(RSS(ΣBSS))
φWL(ΣBWL) = U(RWL(ΣBWL))
If an agreement between both the players in the
game cannot be reached, the utility that the players
will receive is given by the threat point
is the threat point for this
bargaining game
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Bargaining Game (3/3)
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The equilibrium strategy of this game refers
to the set of strategies for which all the
players are satisfied with their received
payoff
[8] S. Chae and P. Heidhues, “A group bargaining solution,
” Elsevier Mathematical Social Sciences, vol. 48, no. 1, pp. 37-53, 2005.
10
N-Person Game in Coalition
Form (1/2)
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define a finite set A of players (i.e., A =
{UGS,PS,BE})
the required burst size for service type (i.e.,
player) j can be obtained from
λ(j)SSis the bandwidth requirement
(j) is the number of connections in service type j from standalone SSs
NSS
11
N-Person Game in Coalition
Form (2/2)
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A coalition S is defined as a subset of A, S
⊂A
The coalition form of an N-person game is
defined by the pair (A, ν) where ν is a
characteristic function of the game
12
Shapley Value
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the value function φ(ν) as the worth or value
of player j in the game with characteristic
function ν
The Shapley value φ = [φ1,…,φi,…,φn] can
be computed as follows
[9] L. S. Shapley, “A value for N-Person game,
” Annals of Mathematics Studies, Princeton University Press, vol. 2, pp. 307-317, 1953
13
Admission Control of Connections
in Standalone SSs (1/2)
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For connections in service type j, the burst
size allocated to connection k depends on
the channel quality as follows
14
Admission Control of Connections
in Standalone SSs (2/2)
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a new connection in service type j arrives, the
802.16 BS decides whether this connection can be
accepted or not by considering the change in total
utility
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a new connection is accepted only when the total
utility increases, and rejected otherwise
15
Admission Control of WLAN
Nodes
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This WLAN initial message contains the
bandwidth requirement of the new
connection
If the link between the AP and the 802.16
BS lacks sufficient bandwidth, the BS
performs bandwidth reallocation among
standalone SSs and WLAN APs
16
Transmission Rate in WLAN
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in the saturated case, the estimated received
bandwidth is obtained as follows
λ(j)WL(k) : the bandwidth requirement of connection k in WLAN j,
CWL : the channel rate in the WLAN
Ps : the measured probability of successful transmission
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Formulation of the Admission
Control Game for WLAN (1/2)
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The burst size allocated to WLAN
connection j depends on the channel quality
as follows
18
Formulation of the Admission
Control Game for WLAN (2/2)
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The payoff for the case when a new connection is
accepted can be obtained as follows
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A new connection from node k in WLAN j is
accepted if for WMAN and WLAN the pure
strategy (accept, accept) is a Nash equilibrium
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Parameter Setting
Transmission Mode
TDMA
Transmission bandwidth
25 MHz
Frame size
1 ms
Cell size
5 km
Average receive SNR
7 ~ 26 dB
UGS, PS, BE
400/500/300 kbps
WLAN channel rate
10 Mbps
WLAN cell radius
50 meters
WLAN bandwidth
400 kbps
20
Variation of Allocated Bandwidth
Under Different Channel Qualities
21
Variation of Total Utility of
Standalone SSs

the number of PS and
BE connections is 15
and 20
22
Performance of Admission
Control Method for WLANs
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Conclusions
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A bargaining game has been used to determine the
optimal burst size for WMAN and WLAN
connections
The Shapley value has been used to obtain the
solution of the bandwidth allocation problem for
different types of WMAN connections
An admission control scheme based on variation
in total utility has been presented
24