Integration of IEEE 802'11 WLANs with IEEE 802'16Based Multihop Infrastructure MeshRelay Networks: A

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Integration of IEEE 802.11 WLANs with IEEE
802.16-Based Multihop Infrastructure Mesh/Relay
Networks A Game-Theoretic Approach to Radio
Resource Management

• Dusit Niyato and Ekram Hossain, TRLabs and
  University of Manitoba
• ?????

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Outline

• Introduction
• Overview of the IEEE 802.16/WiMAX Standard
• An Integrated WMAN/WLAN Network
• Research Issues in an Integrated WLAN/WMAN
  Network
• Bandwidth Management and Admission Control A
  Game-Theoretic Model
• Performance Evaluation
• Conclusions

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1. Introduction (1/2)

• Wireless hotspots based on IEEE 802.11 wireless
  LAN (WLAN) have become very popular.
• A wired infrastructure may not be available in
  remote rural or suburban areas.
• The evolving family of IEEE 802.16 (WiMAX) -based
  wireless metropolitan area network (WMAN)
  technologies is a promising solution to provide
  backhaul support for WLAN hotspots.
• In an infrastructure wireless mesh network, the
  mesh routers form a backbone network for the mesh
  clients to connect to the Internet.

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1. Introduction (2/2)

• In such a mobile hotspot, a WLAN access
  point/router with a dual radio interface connects
  to a 802.16 base station (BS)/mesh router, and
  the WLAN traffic is relayed to an Internet
  gateway through multiple 802.16 base stations
  operating in mesh mode.
• Radio resource management remains an open
  research issue in the IEEE802.16 standard.
• Based on a game-theoretic model, we present a
  bandwidth management and admission control
  framework for 802.16 BSs to allocate bandwidth
  among connections from standalone subscriber
  stations and WLAN access points as well as relay
  traffic from upstream BSs.

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2. Overview of the IEEE 802.16/WiMAX Standard
(1/6)

• Physical Layer
• The physical layer of the IEEE 802.16 air
  interface operates
• 1066 GHz band for IEEE 802.16 (LOS)
• 211 GHz band for IEEE 802.16a (NLOS)
• The physical layer supports data rates in the
  range of 32130 Mb/s depending on the
  transmission bandwidth (e.g., 20, 25, or 28 MHz)
  as well as the modulation and coding schemes
  used.

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2. Overview of the IEEE 802.16/WiMAX Standard
(2/6)

• In the 1066 GHz, the air interface used for this
  band is Wireless-SC (single carrier).
• In the 211 GHz band three different air
  interfaces can be used as follows
• WirelessMAN-SCa for single-carrier modulation
• WirelessMAN-OFDM. The MAC scheme for the
  subscriber stations is TDMA.
• WirelessMAN-OFDMA for OFDM-based transmission
  using2048 subcarriers.
• To enhance data transmission rate, an adaptive
  modulation and coding (AMC) technique is
  supported in the IEEE 802.16 standard.

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2. Overview of the IEEE 802.16/WiMAX Standard
(3/6)

• Since the quality of the wireless link between a
  BS and a subscriber station depends on the
  channel fading and interference conditions,
  through AMC the radio transceiver is able to
  adjust the transmission rate according to the
  channel quality (i.e., signal-to-noise ratio
  SNR at the receiver).
• Reed-Solomon (RS) code concatenated with an inner
  convolution code is used for error correction.

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2. Overview of the IEEE 802.16/WiMAX Standard
(4/6)

• Medium Access Control Layer (PMP)
• IEEE 802.16/WiMAX uses a connection-oriented MAC
  protocol that provides a mechanism for the
  subscriber stations to request bandwidth from the
  BS.
• A 16-bit connection identifier (CID) is used
  primarily to identify each connection to the BS.
• On the downlink, the BS broadcasts data to all
  subscriber stations in its coverage area. Each
  subscriber station processes only the MAC
  protocol data units (PDUs) containing its own CID
  and discards the other PDUs.

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2. Overview of the IEEE 802.16/WiMAX Standard
(5/6)

• For TDD-based access, a MAC frame (i.e.,
  transmission period) is divided into uplink and
  downlink subframes.
• The lengths of these subframes are determined
  dynamically by the BS and broadcast to the
  subscriber stations through downlink and uplink
  MAP messages (DL-MAP and UL-MAP) at the beginning
  of each frame.
• The MAC protocol in the standard supports dynamic
  bandwidth allocation.

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2. Overview of the IEEE 802.16/WiMAX Standard
(6/6)

• Mesh Operation Mode
• In addition to the single-hop PMP operation
  scenario, the WiMAX standard (e.g., IEEE 802.16a)
  also defines the multihop mesh networking
  scenario among the subscriber stations (i.e.,
  client meshing).
• Meshing among the BSs (i.e., infrastructure
  meshing) has not been standardized yet.
• Task Group 802.16j established by the IEEE 802.16
  mobile multihop relay (MMR) study group is
  working on the standardization of relay-based
  infrastructure meshing.

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3. An Integrated WMAN/WLAN Network (1/6)

• The network architecture the backhaul multihop
  mesh infrastructure consisting of the IEEE 802.16
  BSs/mesh routers and the interface between a WLAN
  access point and an 802.16 BS.

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3. An Integrated WMAN/WLAN Network (2/6)

• Each of the edge routers has a dual radio (802.11
  and 802.16) interface.
• The 802.16 BS allocates bandwidth to each of the
  subscriber stations and edge routers separately.
• To avoid co-channel interference, adjacent BSs
  use different frequency bands.

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3. An Integrated WMAN/WLAN Network (3/6)

• With OFDM/TDMA all subchannels are allocated to
  one connection at a time.
• Each of the IEEE 802.16 BSs uses 50 subchannels
  each having a bandwidth of 200 KHz. The total
  bandwidth required (including the guard bands) is
  20 MHz. The frame size is assumed to be 2 ms.
• AMC with seven transmission modes is used in each
  subchannel independently based on the subchannel
  quality.
• The transmission rate

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3. An Integrated WMAN/WLAN Network (4/6)

• Air Interface between Edge Router and Mesh Router
• Data packets corresponding to local and Internet
  traffic (which can be distinguished based on the
  IP packet header) are stored in separate queues
• The local traffic is due to the connections among
  nodes in the coverage area of a WLAN, and
  Internet (or relay) traffic is due to connections
  traversing the mesh backbone to an Internet
  gateway.
• For the Internet traffic, the IEEE 802.11 header
  is removed and then the data unit (including
  header of higher layer protocol such as IP) is
  fragmented into PDUs for the IEEE 802.16 uplink
  subframe.

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3. An Integrated WMAN/WLAN Network (5/6)

• Model for IEEE 802.11 WLAN
• We consider IEEE 802.11 WLANs with direct
  sequence spread-spectrum (DSSS)-based physical
  layer and distributed coordination function (DCF)
  as the MAC scheme. The length of a time slot is
  20 µs, the minimum and maximum values of the
  backoff window size are CWmin 32 and CWmax
  1024 time slots, respectively, and the packet
  size is 8000 bits.

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3. An Integrated WMAN/WLAN Network (6/6)

• The traffic load condition (e.g., unsaturated or
  saturated) is estimated by
• probability of successful transmission Ps.
• probability of collision Pc.
• To determine whether the WLAN is in unsaturated
  or saturated condition, we use a threshold tcol
  (e.g., tcol 0.2) for collision probability.
• In the unsaturated case the estimated received
  bandwidth i by node i in a WLAN is assumed to
  be equal to the transmission rate ?i of that
  node.
• In the saturated case it is proportional to the
  ratio of the user transmission rate to the
  maximum achievable transmission rate and a
  function of the successful packet transmission
  probability Ps.

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4. Research Issues in an Integrated WLAN/WMAN
Network (1/2)
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4. Research Issues in an Integrated WLAN/WMAN
Network (2/2)
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5. Bandwidth Management and Admission Control
A Game-Theoretic Model (1/10)

• Developed mainly for use in the field of
  economics, game theory has been used for radio
  resource management and protocol engineering.
• A game is described by a set of rational players,
  the strategies associated with the players, and
  the payoffs for the players.
• A rational player has his/her own interest, and
  therefore will act by choosing an available
  strategy to achieve that interest.
• A player is assumed to be able to evaluate
  exactly or probabilistically the outcome or
  payoff of the game, which depends not only on
  his/her action but also on other players
  actions.

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5. Bandwidth Management and Admission Control
A Game-Theoretic Model (2/10)

• Two important characteristics of a game
• Individualism
• It influences the rationality (i.e.,
  self-interest) and cooperation among players.
• mutual independence
• It determines the actions of players in response
  to those of other players.
• A game-theoretic model can be used for efficient
  resource allocation among the different
  connections.

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5. Bandwidth Management and Admission Control
A Game-Theoretic Model (3/10)

• We present a bargaining game model for
  distributed bandwidth management and admission
  control for a mesh router in an integrated
  WLAN/WMAN multihop network in a fair manner.
• We consider three different types of traffic
  local traffic from standalone subscriber
  stations, WLAN traffic, and relay traffic from
  upstream routers.
• The motivation of using a bargaining game
  particularly is that the allocation is efficient
  due to Pareto optimality , and fairness is
  achieved by satisfying the concept of
  equilibrium.

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5. Bandwidth Management and Admission Control
A Game-Theoretic Model (4/10)

• Pareto optimality defines an strategy for which
  one player cannot increase his/her utility
  without decreasing the utility (payoff) of the
  other player(s).
• Conversely, if an agreement is not Pareto
  optimal, there is another strategy that provides
  better payoff to the players.

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5. Bandwidth Management and Admission Control
A Game-Theoretic Model (5/10)

• Bandwidth Allocation and Admission Control
  Process

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5. Bandwidth Management and Admission Control
A Game-Theoretic Model (6/10)

• The utility for an admitted connection with
  transmission rate T is given as follows
• U(T) w log(1 aT)
• w and a are constants indicating the scale and
  shape of the utility function.
• The total utility for traffic type j (j wl,
  ss, re) can be obtained from

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5. Bandwidth Management and Admission Control
A Game-Theoretic Model (7/10)

• The admission control mechanism can be
  established based on utility and allocated burst
  size.
• The total utility of a WiMAX BS and a WLAN access
  point increases as the number of connections
  increases.
• At a certain point, it will decrease since the
  utility gained from a new connection cannot
  compensate for the performance degradation of the
  ongoing connections.
• In particular, a new connection is accepted only
  when the total utility increases, and rejected
  otherwise.

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5. Bandwidth Management and Admission Control
A Game-Theoretic Model (8/10)

• Bargaining Game Formulation
• The game-theoretic formulation for bandwidth
  allocation at a mesh router can be described as
  follows
• Players the traffic of three types.
• Strategy the total burst size for player j for
  traffic type j.
• Payoff the total utility Uj for player j
• In a multiplayer game, the players try to make
  an agreement on trading a limited amount of
  resource so that they can gain greater benefit
  than that without cooperation.

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5. Bandwidth Management and Admission Control
A Game-Theoretic Model (9/10)

• The payoff for the players is given by
• O (Uwl(Bwl), Uss(Bss), Ure(Bre)) 0
  Uwl(Bwl), Uss(Bss), Ure(Bre) .
• If an agreement among the players cannot be
  reached, the utility of the players is given by
  the
• threat point (U'wl(0), U'ss(0), U're(0)) (0,
  0, 0).
• The bargaining game model is formulated as
• f(O, U'wl(0), U'ss(0), U'r(0)) (U'wl(Bwl),
  U'ss(Bss), U're(Bre)).

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5. Bandwidth Management and Admission Control
A Game-Theoretic Model (10/10)

• The Pareto optimality can provide the candidate
  strategies (i.e., Bwl, Bss, and Bre Bwl Bss
  Bre F, where F is the total frame size) for
  which one of the players can achieve the highest
  utility.
• The equilibrium All the players are satisfied
  with the utilities they receive. The equilibrium
  can be obtained by using a search method.
• The burst size for connection i
• If the equilibrium does not exist, the burst size
  is proportional to the number of ongoing
  connections of that type and the corresponding
  weight.

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6. Performance Evaluation (1/4)

• Parameter Setting
• The average SNR
• BS-1??the gateway BS 12.5 dB
• BS-2 ?? BS-18.5 dB
• BS ??ss, edge router 1020 dB
• All of the WLAN nodes are assumed to use the same
  transmission rate.
• The parameters to evaluate the utility functions
  are set as follows wwl wss wre 1, awl
  are 1/100, and ass 1/70 (i.e., traffic from
  standalone subscriber stations has less priority
  than WLAN traffic and relay traffic).

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6. Performance Evaluation (2/4)
(17.49, 19.67, 33.78)
Burst size (ms)
(0.287, 0.225, 0.463 )
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6. Performance Evaluation (3/4)
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6. Performance Evaluation (4/4)
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7. Conclusions

• We have presented an architecture for integrating
  WLAN hotspots with IEEE 802.16-based multihop
  broadband wireless mesh networks.
• The research issues related to protocol design
  have been outlined.
• For this integrated architecture we have
  presented a game-theoretic framework for radio
  resource management in the mesh routers.
• Based on a bargaining game formulation, a
  bandwidth allocation scheme has been presented
  for fair resource allocation, and an admission
  control policy to maximize the utilities for the
  different types of connections.