Economic Issues within Mobile Ad Hoc Metropolitan Networks

1
Economic Issues withinMobile Ad HocMetropolitan
Networks

• Sven Östring

MobileMAN Project
Computer Laboratory
2
Rewarding Cooperation

• Investigated a method of providing incentives for
  cooperation in mobile ad hoc networks

Bandwidth Price Power Price

Hop cost
Credit Balance ? Transmission Rate
3
Price Update Algorithms

• Each node measures its total traffic load and
  power consumption
• Prices are adapted as follows
• Bandwidth Price
• Power Price

4
Credit Balance

• Provide incentives for users to forward traffic
• Users receive credit for forwarding traffic
• Amount of credit received is dependent on the
  node prices and the magnitude of the flow.
• Users receive an initial credit balance of 1
• Willingness-to-pay is proportional to Bs
• Update algorithm

5
Random Static Network
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Static Nodes Power Prices

• Power prices are strongly dependent on location
• N8 has the highest power price
• It is often used by other nodes to forward
  traffic
• Its location requires higher energy to transmit
  to neighbouring nodes.
• N1 has very low power price.

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Path of Mobile Node
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Mobility Node Power Prices

• Power price of N1 increases as it moves towards
  the centre of the network
• Routes are increasingly chosen with N1 as a
  forwarding node
• Power price of N8 decreases
• N1 provides competition for N8
• Less energy is required to transmit to N1 as it
  moves closer.

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Total Network Throughput

• Total network throughput increases
• Increased throughput for N1 has not been at the
  expense of the overall network throughput
• Mobility (in an appropriate direction) has
  increased the performance of the system
• Total Credit in system is constant.

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The Issue of Interference

• Wireless links are affected by interference
• Interference from entirely separate traffic flows
  can result in packets not being transmitted
  successfully
• Packets must be re-transmitted
• Reduce the network throughput
• Our model used a basic capacity constraint
• Extend to include a realistic interference model
• Mechanism for pricing the effect of interference

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Signal-to-Inference Ratio

• Conventional Approach
• Vasilios Siris Resource control in CDMA networks
• Peter Marbach Bandwidth allocation in Ad-hoc
  networks
• SIR maps to the probability that
• a packet is successfully received
• Throughput

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Clique Prices Concept

• Paper by Xue, Li and Nahrstedt
• A wireless ad hoc network is mapped onto a
  wireless link contention graph
• Optimality, fairness, convergence

q2
q1
6
23
62
45
q3
5
1
2
3
4
47
7
34
12
78
8
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Clique Prices Algorithms

• Price of a flow
• Sum of clique prices for all the links
• Per-clique price calculation
• Standard price adaptation algorithms
• Centralised (within the clique)
• Per-node price calculation
• Connectivity information is shared amongst
  neighbours
• Individual nodes determine cliques that a flow
  traverses and calculates clique prices

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Parameter Selection

• Kappa
• Gain parameter used in update algorithms
• Much studied in rate control algorithms
• Beta
• Adjusts total credit, so that it correctly tracks
  number of users in the network
• Used to replenish credit to nodes whose income is
  below average
• Investigate the choice of beta on the throughput
  of edge nodes

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Adapting Routing Algorithms

• Extending DSR
• Use pricing information to determine optimal
  routes
• Piggy-back pricing information in ROUTE REPLY
• Probing of routes for pricing information
• DSR caches as many segments of routes as possible
• Timeouts for pricing information associated with
  routes in cache
• Extending AODV
• Piggy-back pricing information in ROUTE REPLY
  messages
• Need method of probing for cheaper routes

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Economics of Ad Hoc Gaming

• Relevant application for two groups
• Students
• Elderly folk
• Similarities
• Credit Balance (Remaining Life)
• Dynamic membership
• Sharing resources / Impact of other players
• Research in network gaming can feed back into our
  model
• Player durations are exponentially distributed
• Distribution of interarrival times is
  heavy-tailed
• Decision to join is dependent on number of
  players
• Pricing multicast communications in ad hoc
  networks

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Conclusions Further Work

• Described our model of incentives
• Investigating approaches of addressing
  interference
• Parameter selection
• Developing adaptive routing protocols
• Including pricing information
• Investigate the performance through simulations
• Gaming Applications